锂金属高压电解液研究

Lithium metal batteries (LMBs) operating at high voltages are attractive for their energy storage capacity but suffer from challenges: cathode instability, electrolyte consumption, and lithium dendrite growth. Modulating the electrode/electrolyte interphase (EEI) with functional additives is a practical strategy. Herein, a cyano (‐CN)‐functionalized hybrid EEI strategy is proposed to develop electrolytes for high‐voltage Li||LiNi0.8Co0.1Mn0.1O2 (Li||NCM811) battery with ‐CN‐substituted tetrafluorobenzene derivatives (tetrafluorophthalonitrile (o‐TFPN), tetrafluoroisophthalonitrile (m‐TFPN)), and tetrafluoroterephthalonitrile (p‐TFPN)) as additives. The results demonstrate that the electrolyte‐containing additives, particularly o‐TFPN‐contained electrolyte, can derive a robust, and thermally stable cathode electrolyte interphase (CEI) enriched with LiF and ‐CN groups. Furthermore, the o‐TFPN‐contained electrolyte forms a stable solid electrolyte interface (SEI) with Li2O, LiF, and ‐CN. The ‐CN group generates electrostatic attraction, guiding Li+ flux, while LiF and Li2O with high ionic conductivity facilitate rapid Li+ deposition. The excellent EEI suppresses cathode degradation, electrolyte consumption, and dendrite formation. Therefore, the Li||NCM811 battery achieves stable performance over 200 cycles at 4.6 V, while the Li||Li symmetric cell stably cycles for over 350 h at a current density of 1 mA cm−2.

High‐voltage lithium metal batteries (LMBs) have garnered significant attention for their high energy density, but struggle with high‐rate capability and wide‐temperature operation. Balancing high‐temperature interfacial stability with rapid low‐temperature/high‐rate desolvation kinetics remains challenging. This study introduces a polyanion‐synergized weakly solvating electrolyte strategy. Using fluoroethylene carbonate (FEC) and ethyl methyl carbonate (EMC) as weakly solvating solvents, a ternary anion system (PF6−/TFSI−/BOB−) modulates the solvation structure. This results in an anion‐enhanced solvation structure enriched with contact ion pairs (CIPs) and ion aggregates (AGGs), which significantly reduces the Li⁺ desolvation energy barrier and enhances Li+ transport kinetics. Moreover, the electrolyte constructs a stable electrode/electrolyte interphase (EEI) enriched with inorganic components such as LiF, Li2S, Li2SOx, Li3N, and LixBOy, providing excellent mechanical and thermal stability. Additionally, LiBOB neutralizes harmful HF, further enhancing electrolyte stability. As a result, the Li||NCM811 battery demonstrates excellent cycling stability across a wide temperature range of ‐10‐60 °C at a high cutoff voltage of 4.6 V and achieves stable charge/discharge performance at a high rate of 5C. A 2.7 Ah pouch cell (359 Wh kg−1) also shows excellent cycling stability. This work provides novel perspectives on high‐voltage electrolyte engineering and propels LMBs toward expanded practical applications.

No abstract available

The stable operation of lithium metal batteries (LMBs) at high voltages is currently limited by the performance of conventional electrolytes. Fluoroethylene carbonate (FEC) exhibits unique physicochemical properties that positively impact interfacial chemistry, positioning it as a promising candidate to enhance the performance of LMBs. However, FEC is prone to the formation of corrosive HF under high voltage, which leads to the degradation of electrode interface. In this study, a hybrid gel polymer electrolyte (HGPE) based on pure FEC solvent with pentafluorophenyl methacrylate (PFPMA) monomer is presented to extend the voltage operating range. The PFPMA monomer forms a mixed‐layer solid electrolyte interphase with lithium difluoro(oxalato)borate (LiDFOB) on electrode surface, effectively inhibiting the decomposition of FEC. The triangular synergistic strategy involving FEC, PFPMA, and polymer segments improves the transport of Li ions in FEC, achieving a high Li+ transference number of 0.87. The designed electrolyte demonstrates good compatibility with Li metal and stabilizes LiNi0.8Co0.1Mn0.1O2 (NCM811) cathodes. As a result, the Li||NCM811 battery based HGPE exhibits a capacity retention of 83.4% after 300 cycles and 74.2% after 400 cycles, under a cut‐off voltage of 4.5 V. This study provides a promising strategy for the development of GPE for high‐voltage LMBs applications.

Currently, the design of lithium metal batteries primarily focuses on improving cycling stability by increasing the lithium fluoride (LiF) content in the interfacial layer. However, the extensive use of fluorides poses severe environmental concerns. In this study, a novel strategy is proposed to construct a Li3N/Li2O heterostructure via the in situ decomposition of lithium perchlorate (LiClO4) and lithium nitrate (LiNO3), replacing the role of LiF in the SEI. This unique heterostructure combines excellent lithium‐ion transport capability with robust electronic insulation properties, effectively preventing electron tunneling phenomena. When paired with the NCM811 cathode, the Li||NCM811 full cell exhibits exceptional electrochemical performance, including outstanding charge–discharge capabilities under extreme temperatures. At 60 °C and 1C conditions, the battery retains 82.11% of its capacity after 500 cycles; at 25 °C and 1C, it maintains a capacity retention rate of 80.61% after 800 cycles. Furthermore, under practical application conditions (100 µm lithium anode, N/P ratio of 3.09, and a 1.5 Ah pouch cell), the fluorine‐free lithium metal battery (LMB) retains 77.93% capacity after 100 cycles, demonstrating the superiority and practical value of this strategy.

The decomposition of 1,2‐dimethoxyethane (DME) in localized high‐concentration electrolytes (LHCEs) under high voltage produces fragile and unstable organic fragments at the cathode/electrolyte interphase, which greatly damages the cycling performance of high‐energy‐density lithium metal batteries. Herein, a robust strategy is proposed by adding ionic liquid of 1‐Methyl‐1‐propyl pyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr13TFSI) as co‐solvent into the bulk electrolyte to significantly improve the stability of solvated DME through reinforcing the ion‐dipole interaction between TFSI− and DME. The Pyr13TFSI can balance the interaction among the electrolyte components to reduce the dynamic de‐coordinated DME molecules and promote the formation of anion‐derived cathode electrolyte interphase with excellent electrochemical stability and high Li+ transport dynamics. The Li||LiNi0.8Co0.1Mn0.1O2 coin cells with Pyr13TFSI exhibit capacity retention of 76.1% after 1800 cycles at 1 C rate (4.5 V), and 77.1% after 800 cycles at a high cut‐off voltage of 4.6 V. Furthermore, the cells using Li anode with the thickness of 50 µm and high LiNi0.8Co0.1Mn0.1O2 loading of 18.68 mg cm−2 can operate for 175 cycles with high‐capacity retention of 73.35%. This work demonstrates that modulating the interactions among electrolyte components using ionic liquid can optimize the coordination chemistry for advanced high‐energy density Li metal batteries.

Widening the voltage window of the nickel‐rich layered oxide cathode‐based lithium metal batteries (LMBs) can effectively improve the energy density of rechargeable batteries. However, serious safety issues associated with the high reactivity between LiNi0.8Co0.1Mn0.1O2 (NCM811) and electrolyte at high cut‐off voltage remains challenging. Herein, a flame‐retardant electrolyte with the ability to form a robust armor‐like electrode electrolyte interphase (EEI) with LiF and LixByOz compounds for stabilizing Li||NCM811 batteries is proposed. Such electrolyte exhibits the high thermal stability with flame‐retardant effect for ensuring the battery safety at high voltage. The armor‐like EEI can effectively protect both NCM811 and lithium (Li) for improving the battery cycling performance. As a result, the capacity retention rate of the NCM811 cathode with such electrolyte reached 68% after 150 cycles at 4.6 V. This work provides an effective reference for the reasonable design of high‐voltage, flame‐retardant electrolytes for LMBs.

Poly(vinylidene fluoride) (PVDF)-based polymer electro-lytes are attracting increasing attention for high-voltage solid-state lithium metal batteries because of their high room temperature ionic conductivity, adequate mechanical strength and good thermal stability. However, the presence of highly reactive residual solvents, such as N, N-dimethylformamide (DMF), severely jeopardizes the long-term cycling stability. Herein, we propose a solvation-tailoring strategy to confine residual solvent molecules by introducing low-cost 3 Å zeolite molecular sieves as fillers. The strong interaction between DMF and the molecular sieve weakens the ability of DMF to participate in the solvation of Li+, leading to more anions being involved in solvation. Benefiting from the tailored anion-rich coordination environment, the interfacial side reactions with the lithium anode and high-voltage NCM811 cathode are effectively suppressed. As a result, the solid-state Li||Li symmetrical cells demonstrates ultra-stable cycling over 5100 h at 0.1 mA cm-2, and the Li||NCM811 full cells achieve excellent cycling stability for more than 1130 and 250 cycles under the charging cut-off voltages of 4.3 V and 4.5 V, respectively. Our work is an innovative exploration to address the negative effects of residual DMF in PVDF-based solid-state electrolytes and highlights the importance of modulating the solvation structures in solid-state polymer electrolytes.

High‐voltage lithium (Li) metal batteries (LMBs) emerge as a pivotal strategy for achieving high energy density applications. However, the electrolyte instability leading to inferior rate performance and short lifespan remains to be addressed. In this study, a new non‐concentrated gradient‐solvation electrolyte by solvent polarity discrepancy is developed. A highly donor‐capable ether forms the Li⁺‐solvated core through strong ion‐dipole interactions, while a weakly donating carbonate creates the shell structure. Such a gradient‐solvation structure enables the electrolyte with a high oxidation voltage (4.6 V vs. Li/Li+) and rapid Li+‐desolvated kinetic. Consequently, the electrolyte facilitates the LiNi0.8Co0.1Mn0.1O2 (NCM811)||Li cells to attain a specific capacity of 165.8 mAh g−1 at 5C, alongside 1000 stable cycles at 1C charge/3C discharge with 66% capacity retention. Even under lean conditions (N/P = 1.5, electrolyte: 20 µL), NCM811||Li cell still maintains 97.5% capacity retention over 100 cycles. Furthermore, a 3.2 Ah pouch cell achieves a specific energy density of 447.6 Wh kg−¹ with stable cycling. These findings highlight the promise of gradient‐solvation electrolytes for high‐voltage LMBs applications.

The development of high-voltage solid-state lithium-metal batteries (HVSSLMBs) is severely limited by unstable ion transport, insufficient oxidative stability, and poor electrode-electrolyte interface (EEI) compatibility of conventional solid electrolytes. Herein, we report a topologically entangled polymer electrolyte featuring ionophilic-protonation dual side chains. The ionophilic functional groups on these side chains provide abundant coordination sites, significantly enhancing Li+ transport, while exposed carboxyl (-COOH) groups induce protonation on the cathode surface, effectively suppressing transition metal (TM) ion migration. The topologically entangled polymer network ensures uniform electric-field distribution, mitigates lattice-oxygen release, and maintains continuous Li+ conduction. As a result, this electrolyte achieves a high room-temperature ionic conductivity of 0.81 mS cm-1 and an oxidation stability up to 4.9 V. Moreover, the in situ formed inorganic species (LiF, Li2O, and Li2CO3), stabilized the EEI, enabling stable cycling of the symmetric cell for 2000 hours. Batteries assembled with a high-voltage Li1.2Ni0.13Mn0.54Co0.13O2 (LRMO) cathode retain a specific capacity of 217.37 mAh g-1 after 250 cycles, and Ah-level pouch cell utilizing an LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode exhibits stable cycling performance over 150 cycles. These findings demonstrate the great promise of this strategy for the development of high-energy-density lithium-metal batteries with outstanding cycling performance and long-term stability.

The incorporation of lithium metal as an anode material in lithium metal batteries (LMBs) offers a transformative pathway to surpass the energy density limits of conventional lithium-ion batteries (LIBs). However,...

Polyethylene glycol (PEG)‐based polymer electrolyte has emerged as a class of promising solid electrolytes for lithium metal batteries (LMBs), but suffer from incompatibility with high‐voltage cathodes and uneven plating/stripping of Li metal anode. Herein, a modified C3N4 additive with dual defect sites of cyano‐groups and nitrogen‐vacancies (CN─Nv─C3N4) in PEG‐based polymer electrolyte is demonstrated, which can serve as an effective dual functional ion rectifier to mitigate the cathode crosstalk, and optimize ion conductive environment. Experimental characterization and density functional theory (DFT) calculations reveal that the high electronegative cyano‐groups effectively traps the transition metal cations through coordination, while N‐vacancies generate abundant electron‐deficient centers to anchor anions and thus significantly increase Li+ transfer number. Specifically, the CN─Nv─C3N4 modulated PEG‐based polymer electrolyte (GPE‐CNC) achieved an ultra‐high Li+ transfer number of 0.72 and an Li+ conductivity of 0.6 mS cm−1 at room temperature. Moreover, when matched with high‐voltage LiNi0.6Co0.2Mn0.2O2 cathode, GPE‐CNC can operate stably at a rate of 0.5 C, with an outstanding capacity retention rate of 71% after 700 cycles. This multiple ion rectification strategy not only enhances voltage compatibility, but also promotes high Li+ transfer number of PEG‐based polymer electrolyte, offering inspiration for the development of high energy density solid‐state batteries.

Although polymer‐based electrolytes offer advantages like low cost, favorable interfacial compatibility, and processability for solid‐state lithium metal batteries with high safety and high energy density, conventional linear polymer‐based electrolytes suffer from inadequate oxidation resistance and mechanical strength at operating voltages above 4.5 V, causing rapid capacity degradation and reduced battery lifespan. Inspired by the mechanical slide‐ring structure of polyrotaxanes (PR), a series of high‐voltage‐resistant sliding crosslinked quasi‐solid electrolytes (PMBA‐PPRx) is designed and synthesized via in situ thermal polymerization of varying amounts of vinyl functional polyrotaxanes (PPRs) with N,N'‐methylenebisacrylamide (MBA). The optimal PMBA‐PPR5 electrolyte realizes the synergistic enhancement of both mechanical properties and high‐voltage‐resistant electrochemical properties as well as the good interfacial compatibility. The dynamic slide ring structure of PPRs effectively dissipates the energy generated by lithium dendrite growth, thereby maintaining the mechanical robustness of the electrolyte during battery cycling and achieving lithium deposition/stripping behavior for more than 2000 h at 0.5 mA cm−2. The strong polar amide groups of MBA not only improve the lithium‐ion transference number (0.69), but also enhance the high‐voltage stability of the electrolyte (∼ 5.5 V), ultimately resulting in excellent cycling stability and capacity retention of Li|PMBA‐PPR5|LFP and Li|PMBA‐PPR5|NCM811 cells. This slide‐crosslinked polyrotaxane topological dynamic structure provides a new strategy for the design of high‐voltage lithium metal electrolytes.

A rechargeable lithium (Li) metal anode combined with a high-voltage nickel-rich layered cathode has been considered a promising combination for high-energy Li metal batteries (LMBs). However, they usually suffer from insufficient cycling life because of the unstable electrochemical stability of both electrodes. In this work, we report an advanced multi-functional additive, 1,3,6-hexanetricarbonitrile (HTCN), in a conventional carbonate-based electrolyte. This rationally designed electrolyte formation generates an ideal cathode electrolyte interphase (CEI) for LiNi0.8Co0.1Mn0.1O2 (NCM811) and a solid electrolyte interphase (SEI) for Li metal, successfully realizing stable ion transport kinetics. Then, theoretical calculations, physical characterization and electrochemical tests confirm that HTCN is more easily adsorbed on the NCM811 surface where it is oxidized to construct a stable CEI film involving the detachment of the CN group in a linear chain. Simultaneously, HTCN shows a more negative electron affinity and is easier to reduce, constructing a robust SEI film resulting from the detachment of the CN group in the side chain. Consequently, the assembled 50 μm-thin NCM811//Li (9.0 mg cm−2 of mass loading) delivers a desired energy density of ∼330 W h kg−1 at the cell level and an excellent cycling stability of 120 cycles with 88% capacity retention at 1C.

This work demonstrates the low‐temperature operation of solid‐state lithium metal batteries (LMBs) through the development of a fluorinated and plastic‐crystal‐embedded elastomeric electrolyte (F‐PCEE). The F‐PCEE is formed via polymerization‐induced phase separation between the polymer matrix and plastic crystal phase, offering a high mechanical strain (≈300%) and ionic conductivity (≈0.23 mS cm−1) at −10 °C. Notably, strong phase separation between two phases leads to the selective distribution of lithium (Li) salts within the plastic crystal phase, enabling superior elasticity and high ionic conductivity at low temperatures. The F‐PCEE in a Li/LiNi0.8Co0.1Mn0.1O2 full cell maintains 74.4% and 42.5% of discharge capacity at −10 °C and −20 °C, respectively, compared to that at 25 °C. Furthermore, the full cell exhibits 85.3% capacity retention after 150 cycles at −10 °C and a high cut‐off voltage of 4.5 V, representing one of the highest cycling performances among the reported solid polymer electrolytes for low‐temperature LMBs. This work attributes the prolonged cycling lifetime of F‐PCEE at −10 °C to the great mechanical robustness to suppress the Li‐dendrite growth and ability to form superior LiF‐rich interphases. This study establishes the design strategies of elastomeric electrolytes for developing solid‐state LMBs operating at low temperatures and high voltages.

Electrolyte engineering is emerging as a key strategy for enhancing the cycle life of lithium metal batteries (LMBs). Fluorinated electrolytes have dramatically extended cycle life; however, intractable challenges regarding the...

All‐climate lithium metal batteries are highly needed, but remains a huge challenge in cycling life due to the existence of unstable electrode electrolyte interphases, especially with nickel‐rich layered oxide cathode at high cut‐off voltage. To address this question, a functional and robust sandwich‐model cathode electrolyte interphase (CEI) is proposed, derived from a LiBF4‐based electrolyte modified with para‐fluorobenzeneacetonitrile (P‐FBCN) additive, to realize the stability of 4.8 V Li||LiNi0.94Co0.05Mn0.01O2 (NCM94) battery operated from −60 to 60 °C. The LiF‐rich sandwich‐model CEI features an outer layer of LiBxOy‐rich to enhance mechanical/thermal stability, and the inner −C≡N‐rich anchoring layer to facilitate Li⁺ conduction and inhibit the dissolution of transition metal ions. Notably, the 7.6 Ah‐grade Li||NCM94 pouch cell with such electrolyte can yield a high energy density of 544 Wh kg−1 with a long lifespan of 158 cycles.

No abstract available

Phosphate‐based localized high‐concentration electrolytes (LHCE) feature high flame retardant and satisfactory cathodic stability for lithium metal batteries. However, stable cycling of those electrolytes at ultra‐high upper cut‐off voltages for long‐term stability remains challenging. Herein, an ether‐modified phosphate, diethyl (2‐methoxy ethoxy) methylphosphonate (DMEP), is designed for high‐voltage applications. The ether modification enhances the stability of the Li+‐DMEP‐FSI− coordination structure, promoting the formation of cation‐anion aggregates (AGG) dominated solvation structure, which favors the generation of LiF‐rich cathode electrolyte interphase layers compared to triethyl phosphate (TEP)‐based LHCE. Consequently, cathode degradation, including transition‐metal dissolution and electrode cracking, is well‐suppressed. The LiNi0.8Co0.1Mn0.1O2 (NCM811)||Li full cells using DMEP‐based LHCEs show more than 90.7% capacity retention at an ultrahigh upper cut‐off voltage of 4.7 V after 100 cycles. Notably, DMEP‐LHCE exhibits enhanced safety than that of TEP‐LHCE, suggesting its versatility and potential for next‐generation lithium metal batteries.

Solid polymer electrolytes with high interfacial stability are considered among the most promising alternatives for replacing liquid electrolytes in high‐voltage lithium (Li) metal batteries. However, their application faces significant challenges, such as random dendrite deposition, interfacial side reactions, and sluggish ion transport, leading to performance degradation and safety hazards. Herein, an inherently stable difluorinated polyether electrolyte (DPE) is proposed that exhibits superior interfacial stability and ion conductivity, enabling the reliable operation of high‐voltage all‐solid‐state Li metal batteries (ASSLMBs). Due to the synergistic electron‐withdrawing and ion solvation effects of difluorinated functional groups, DPE shows an improved oxidation voltage of 4.9 V and high Li+ conductivity of 2.0 × 10−4 S cm−1. The generated LiF‐rich electrolyte/electrode interphase further improves the stability of DPEs against both Li metal anode and high‐voltage cathode. Consequently, the assembled all‐solid‐state Li||LFP battery retains 73.17% of its capacity after 700 cycles. The high‐voltage all‐solid‐state Li||LiNi0.6Co0.2Mn0.2O2 (NCM622) battery remains stable over 300 cycles with a high capacity retention of 76.02%. Moreover, the high‐voltage ASSLMB shows negligible capacity degradation during 3000 bending cycles at a small radius curvature of 4.0 mm. This work provides a feasible strategy for designing antioxidant polymer electrolytes for the stable operation of high‐voltage Li metal batteries.

Currently, non-flammable deep eutectic electrolytes (DEEs), typically based on N-methylacetamide (NMAC), have been deemed as high-quality electrolytes employed in lithium-metal batteries (LMBs). However, the unstable interphase chemistry derived from high reactivity of amide groups towards aggressive electrodes (Li and NCM cathode) and tight Li+-amide coordination still exists as the unavoidable "sore point" for DEEs innovation as yet. Herein, inspired by fluorinated solvent strategy, N-Methyl-2,2,2-trifluoroacetamide (FNMAC), is proposed to design the FNMAC-based DEE (F-DEE-1:n, n = 2 ∼ 8) solely containing lithium bis(trifluoromethanesulphonyl)imide (LiTFSI) salt. Introducing electron-withdrawing -CF3 group is conducive to realizing excellent oxidation resistance as well as stable interphase chemistry, which impairs Li+-amide strong coordination bringing forth anion-rich solvation sheath and robust solid electrolyte interface (SEI) with high inorganic content, together with promoting the fast desolvation of Li+. Consequently, the F-DEE-1:4 endows NCM622||Li cells with excellent rate capability and outstanding long lifespan along with high capacity retention of ∼91.3 % after cycling 420 times, much superior to those using NMAC-based DEE (N-DEE-1:4). This work is instructive for high-quality DEEs innovation and emphasizes the close correlation between Li+ coordination environment and stable interphase chemistry within LMBs.

Poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs) are among the most promising materials for solid-state lithium metal batteries (LMBs) due to their inherent safety advantages; however, they suffer from insufficient room-temperature ionic conductivity (up to 10–6 S cm–1) and limited oxidation stability (<4 V). In this study, a novel “polymer-in-high-concentrated ionic liquid (IL)” (PiHCIL) electrolyte composed of PEO, N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl) imide (C3mpyrFSI) IL, and LiFSI is designed. The EO/[Li/IL] ratio has been widely varied, and physical and electrochemical properties have been explored. The Li-coordination and solvation structure has been explored through Fourier-transform infrared spectroscopy and solid-state magic-angle spinning nuclear magnetic resonance. The newly designed electrolyte provides a promisingly high oxidative stability of 5.1 V and offers high ambient temperature ionic conductivity of 5.6 × 10–4 S cm–1 at 30 °C. Li|Li symmetric cell cycling shows very stable and reversible cycling of Li metal over 100 cycles and a smooth dendrite-free deposition morphology. All-solid-state cells using a composite lithium iron phosphate cathode exhibit promising cycling with 99.2% capacity retention at a C/5 rate over 100 cycles. Therefore, the novel approach of PiHCIL enables a new pathway to design high-performing SPEs for high-energy-density all-solid-state LMBs.

Nickel-rich ternary cathodes are highly favored for lithium metal batteries due to their high energy density and operating voltage. However, challenges such as interfacial side reactions, thermal instability, and capacity...

The electrochemical instability of ether-based electrolyte solutions hinders their practical applications in high-voltage Li metal batteries. To circumvent this issue, here, we propose a dilution strategy to lose the Li^+/solvent interaction and use the dilute non-aqueous electrolyte solution in high-voltage lithium metal batteries. We demonstrate that in a non-polar dipropyl ether (DPE)-based electrolyte solution with lithium bis(fluorosulfonyl) imide salt, the decomposition order of solvated species can be adjusted to promote the Li^+/salt-derived anion clusters decomposition over free ether solvent molecules. This selective mechanism favors the formation of a robust cathode electrolyte interphase (CEI) and a solvent-deficient electric double-layer structure at the positive electrode interface. When the DPE-based electrolyte is tested in combination with a Li metal negative electrode (50 μm thick) and a LiNi_0.8Co_0.1Mn_0.1O_2-based positive electrode (3.3 mAh/cm^2) in pouch cell configuration at 25 °C, a specific discharge capacity retention of about 74% after 150 cycles (0.33 and 1 mA/cm^2 charge and discharge, respectively) is obtained. Ether solvents have poor anodic stabilities in lithium metal batteries. Here, the authors propose a non-aqueous electrolyte solution with a non-polar and non-fluorinated ether solvent. The electrolyte enables stable cycling of high-voltage Li metal batteries in pouch cell configuration.

The safety and cycle stability of lithium metal batteries (LMBs) under conditions of high cut‐off voltage and fast charging put forward higher requirements for electrolytes. Here, a sulfonate‐based deep eutectic electrolyte (DEE) resulting from the eutectic effect between solid sultone and lithium bis(trifluoromethanesulfonyl)imide without any other additives is reported. The intermolecular coordination effect triggers this eutectic phenomenon, as evidenced with nuclear magnetic resonance, and thus the electrochemical behavior of the DEE can be controlled by jointly regulating the coordination effects of F···H and Li···O intermolecular interactions. The DEE with a properly coordinated environment of Li+ presents a low motion barrier and a high transport rate of localized Li+, leading to a 10 C fast‐charging LiFePO4||Li battery with a capacity retention of 95.1% after 500 cycles. Meanwhile, the strengthened α−H···F coordination broadens the electrochemical stability window of the DEE, thus enabling the cycle stability of high‐capacity and high‐voltage cathode materials in LMBs, e.g., a cycle stability at 4.5 V in the LiNi0.88Co0.07Mn0.05O2||Li battery with a capacity retention of 81.0% after 500 cycles, and an excellent compatibility in 4.5 V LiCoO2||Li and 4.8 V Li1.13Mn0.517Ni0.256Co0.097O2||Li batteries. The practical applicability of the carefully designed DEE is underscored through successful implementation in pouch cells.

The instability of the cathode/electrolyte interface and the increased difficulty of lithium-ion desolvation at low temperatures significantly limit the development of rechargeable lithium metal batteries (LMBs). In this work, a local high-concentration electrolyte based on methyl acetate was prepared using the diluent 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether. Theoretical calculations and experimental results show that optimizing the solvent structure of the electrolyte by adjusting the lithium salt concentration and adding a diluent facilitates the desolvation process of Li+. As a result, the Li/LiCoO2 cell with the optimized 5M-AFDT electrolyte exhibits stable long-term cycling at 4.5 V under room temperature, achieving a capacity retention of 81.1% after 400 cycles at 1 C. In addition, the electrolyte demonstrates outstanding low-temperature performance, allowing the cell to deliver 86.4% of its room-temperature capacity at -40 °C and maintain stable cycling for 100 cycles. This study offers a detailed analysis of the impact of the electrolyte's solvation structure on battery performance, providing a promising approach for designing electrolytes for low-temperature, high-voltage LMBs.

The compatibility of lithium metal with organic solvents is the most crucial for lithium metal batteries (LMBs). Even though ether solvents show excellent compatibility toward lithium metal, the reactivity of the ether solvents at elevated temperatures and high voltages hinders their utilization in lithium metal battery systems. In this study, a high‐temperature ether electrolyte is designed comprising lithium oxalyldifluoroborate (LiODFB), diethylene glycol dibutyl ether (DGDE), 3‐methoxypropionitrile (MPN), and fluorinated ethylene carbonate (FEC), which is abbreviated as MDF electrolyte. The presence of MPN in the electrolyte changes the solvation structure, thereby facilitating increased redox reactions of ODFB− and synergizing with FEC to build a robust solid electrolyte interface (SEI), effectively inhibiting lithium dendrites growth and solvent decomposition. Consequently, the MDF electrolyte exhibits not only long cyclic stability and high coulombic efficiency in Li||Cu and Li||Li cells but also excellent cyclic characteristics in both Li||LiFePO4 (LFP) and Li||LiNi0.8Co0.1Mn0.1O2 (NCM811) cells. Remarkably, these cells demonstrate stable operation even when exposed to higher temperatures of up to 80 °C, while the Li||NCM811 cell maintains consistent cyclic stability at an elevated voltage level of 4.5 V.

Ether‐based electrolytes show great potential in low‐temperature lithium metal batteries (LMBs) for their low viscosity and decent reduction stability. However, conventional ethers with multidentate chelate sites suffer from low oxidation stability and high desolvation energy barrier due to the strong coordination between oxygen and Li+. Herein, cyclic tetrahydropyran (THP) with a unidentate site is designed as a solvent, and fluoroethylene carbonate (FEC) and lithium nitrate (LiNO3) serve as additives for low‐temperature LMBs. The cyclic strain and unidentate chelate effect endow THP with a weak affinity to Li+ ions, which accelerates Li+ desolvation process and induces the anion‐derived electrode/electrolyte interface at low temperature. The formed inorganic‐rich interface further improves the oxidation stability and expedites the interfacial ion transportation. As a result, the assembled Li‐LiNi0.8Mn0.1Co0.1O2 (NMC811) cell stably cycles with 87% capacity retention after 100 cycles at −40 °C and 4.5 V. The 2.7 Ah Li‐NMC811 pouch cell with an energy density of 403 Wh kg−1 delivers 53% of the room‐temperature capacity at −50 °C. This work reveals that regulating the chelate site of solvents can well optimize the electrolytes to realize low‐temperature LMBs.

High‐nickel cathode materials is known to have high specific capacity but poor stability and safety due to nickel diffusion. While Al‐doped high‐nickel cathode (NCMA) particles exhibit enhanced stability, their durability under high‐charge cut‐off voltages remains uncertain. Herein, a polymer electrolyte with semi‐interpenetrating network (SIPN) structure is designed for high‐voltage lithium‐metal battery application. The matrix of the polymer electrolyte is composed of a CO2‐derived thermoplastic polyurethane (TPU) and an in situ polymerized polyacrylonitrile (PAN), where the PAN provides strength and the TPU offers excellent high‐voltage resistance and abundant ion‐complexing sites. With the assistance of additives, the PAN‐TPU‐based electrolyte performs excellent flame retardancy, wide electrochemical stability window (>5.1 V) and can lead to stable organic–inorganic hybrid cathode‐electrolyte interface during cycling. The Li‖PAN‐TPU/TEP‐E‖Li cell lasts over 3400 h at 0.2 mA cm−2. With the construction of well‐connected ion pathway by incorporating of the TPU as binder for cathode and in situ forming the PAN‐TPU‐based electrolyte. The NCMA@TPU‖PAN‐TPU/triethyl phosphate‐based electrolyte (TEP‐E)‖Li cell shows outstanding performances, which maintains a capacity of 186 mAh g−1 at a 4.3 V charging cut‐off voltage, retaining 82% capacity after 300 cycles at 0.5 C. Even at a 4.5 V cut‐off voltage, it retains 78% capacity after 200 cycles at 0.5 C.

The practical application of LiBH4 in all‐solid‐state Li metal batteries (ASSLMBs) is hindered by low Li‐ion conductivity at room temperature, poor oxidative stability, and severe dendrite growth. Herein, porous [LiNBH]n with a hydrogen‐deficient chain‐like molecular structure are designed for in situ space‐confining LiBH4, which enables strong attraction of negatively charged Hδ− atoms of [BH4]− anions by Li+ of [LiNBH]n chains that weakens Coulombic interaction between Li+ and [BH4]− anions and hence promotes Li ion diffusion. Additionally, the electron‐withdrawing effect of [LiNBH]n chains induces the local electron localization of LiBH4 that enhances oxidative stability of LiBH4. Therefore, the Li ion conductivity of LiBH4 reaches 2.2 × 10−4 S cm−1 at 30 °C, nearly 4 orders of magnitude higher than that of LiBH4, with a voltage window of 5 V. Moreover, the interaction between Li metal and [LiNBH]n chains results in in situ formation of ultrathin layer composed of Li3N and LiB alloys that hinders Li dendrites growth, leading to a critical current density value of 7.5 mA cm−2 and a cycling life of 100 h at 4 mA cm−2 with an overpotential of 125 mV. Hence, LiCoO2|LiBH4‐70LiNBH|Li cell at 0.5 C deliver a high capacity of 89.5 mA h g−1 after 400 cycles.

Lithium metal batteries (LMBs) coupled with a high-voltage Ni-rich cathode are promising for meeting the increasing demand for high energy density. However, aggressive electrode chemistry imposes ultimate requirements on the electrolytes used. Among the various optimized electrolytes investigated, localized high-concentration electrolytes (LHCEs) have excellent reversibility against a lithium metal anode. However, because they consist of thermally and electrochemically unstable solvents, they have inferior stability at elevated temperatures and high cutoff voltages. Here we report a semisolvated sole-solvent electrolyte to construct a typical LHCE solvation structure but with significantly improved stability using one bifunctional solvent. The designed electrolyte exhibits exceptional stability against both electrodes with suppressed lithium dendrite growth, phase transition, microcracking, and transition metal dissolution. A Li||Ni0.8Co0.1Mn0.1O2 cell with this electrolyte operates stably over a wide temperature range from -20 to 60 °C and has a high capacity retention of 95.6% after the 100th cycle at 4.7 V, and ∼80% of the initial capacity is retained even after 180 cycles. This new electrolyte indicates a new path toward future electrolyte engineering and safe high-voltage LMBs.

The poor compatibility of carbonate-based electrolytes with lithium metal anodes results in unstable solid electrolyte interphase, leading to lithium dendrite formation, low Coulombic efficiency, and short cycle life. To address this issue

Solid-state electrolytes (SSEs) show considerable potential for improving the safety of lithium metal batteries by replacing flammable organic liquid electrolytes. However, the practical application of SSEs is constrained by low...

Lithium (Li) metal batteries hold significant promise in elevating energy density, yet their performance at ultralow temperatures remains constrained by sluggish charge transport kinetics and the formation of unstable interphases. In conventional electrolyte systems, lithium ions are tightly locked in the solvation structure, thereby engendering difficulty in the desolvation process and further exacerbating solvent decomposition. Herein, we propose a new push-pull electrolyte design strategy, utilizing molecular electrostatic potential (ESP) screening to identify 2,2-difluoroethyl trifluoromethanesulfonate (DTF) as an optimal cosolvent. Importantly, DTF exhibits a moderate ESP minimum (-21.0 kcal mol-1) to strike a balance between overly strong and overly weak Li ion affinity, which allows the sulfonyl group to effectively pull Li ions without disrupting the anion-rich solvation structure. Simultaneously, the difluoromethyl group, with a high ESP maximum (37.3 kcal mol-1), pushes solvent molecules via competitive hydrogen bonding. This design reconstructs existing solvation structures and expedites Li ion desolvation. Furthermore, fluorinated DTF demonstrates excellent stability at elevated voltage and facilitates the formation of robust inorganic-rich interphases. Impressively, rapid charge transfer kinetics can be achieved employing designed electrolyte, and the LiNi0.8Mn0.1Co0.1O2 (NMC811)||Li cells demonstrate excellent charge-discharge cycling stability with a high capacity exceeding 153 mAh g-1 even at -40 °C, retaining over 93% of initial capacity after 100 cycles under a 4.8 V charging cutoff. This work provides insights into the design of low-temperature electrolytes with a wide electrochemical window, advancing the development of batteries for extreme conditions.

Li metal batteries (LMB) based on high‐nickel cathode are potential high‐energy‐density next‐generation batteries. The inherent issue of LMBs is the formation and growth of Li dendrite at Li anode and intensification of failure of Li anode under higher charge cut‐off voltage than 4.2 V, which causes short circuit and safety hazard. To address those issues, a fluorinated carbonate and sulfate‐based flame‐retarding (FR) liquid electrolyte formulation is reported that improves performance of a highly loaded (3.5 mAh cm−2) Li//LiNi0.88Co0.08Mn0.04O2 (NCM‐88) LMB under a simultaneously aggressive condition of high voltage (4.3 V), high temperature (45 °C), and 1 C rate. Fluorine and sulfur‐containing robust cathode–electrolyte interphase species form, which provides high‐voltage and thermal stability, and suppresses metal dissolution. Highlighted is the surface passivation of Li anode with robust solid electrolyte interphase and prevention of Li dendrite, leading to excellent LMB cycling performance (capacity retention of 70% at 100 cycles) and safety. High stability of Li//Li symmetric cell is achieved with the FR electrolyte under current of 1 mA cm−2 (Li stripping‐plating in 1 h) for a prolonged time of 300 h. The present study gives an insight into the design of alternative electrolyte formulation to ether‐based one for safer high‐energy LMBs.

Lithium metal battery (LMB) is a potential next-generation battery for higher energy storage device than state-of-the-art lithium-ion batteries. To obtain a high energy density of LMB, high mass loading of high-capacity cathode such as high-nickel LiNixCoyMnzO2 (NCM, x ≥ 0.8) and/or high-voltage operation (> 4.2 V) are needed. The inherent issues of LMBs at high-voltage are interface and thermal instability and structural degradation of NCM cathode. Moreover, the uncontrollable growth of lithium (Li) dendrites at Li anode often occur when using traditional carbonate-based flammable liquid electrolyte, resulting in the risk of battery safety. A suggested solution to mitigate those issues is the development of a less flammable liquid electrolyte that also forms stable solid electrolyte interphase (SEI) at the surface of cathode and anode. Herein, we report a flame-retarding electrolyte approach that enables the stable operation of a high-nickel NCM-based LMB under high voltage and high temperature.

Electrolyte engineering is crucial for developing high-performance lithium metal batteries (LMB). Here, we synthesized two cosolvents methyl bis(fluorosulfonyl)imide (MFSI) and 3,3,4,4-tetrafluorotetrahydrofuran (TFF) with significantly different reduction potentials and add them into LiFSI-DME electrolytes. The LiFSI/TFF-DME electrolyte gave an average Li Coulombic efficiency (CE) of 99.41% over 200 cycles, while the average Li CEs for MFSI-based electrolyte is only 98.62%. Additionally, the TFF-based electrolytes exhibited a more reversible performance than the state-of-the-art fluorinated 1,4-dimethoxylbutane electrolyte in both Li||Cu half-cell and anode-free Cu||LiNi0.8Mn0.1Co0.1O2 full cell. More importantly, the decomposition product from bis(fluorosulfonyl)imide anion could react with ether solvent, which destroyed the SEI, thus decreasing cell performance. These key discoveries provide new insights into the rational design of electrolyte solvents and cosolvents for LMB.

Lithium metal battery (LMB) is a potential next-generation battery that can provide higher energy density than Li-ion batteries. However, during fast charging, lithium dendrites growth occur at the surface of Li metal anode, resulting in short circuiting, thermal runaway, and fire event. Under high-voltages beyond 4.2 V, lithium dendrites growth and structural degradation of cathode active material will be accelerated, leading to faster performance fade and higher risk of short circuiting. Herein, we demonstrate the significant impacts of fluorinated organic additive that enables ultrafast charging 400 cycles performance of Li//Mn-rich LMB under extreme conditions of 20 C (charged in 3 minutes) and charge cut-off voltage of 4.8 V, without lithium dendrites. Stable performance and high tolerance to extreme conditions are ascribed to the additive-derived formation of uniform and robust solid electrolyte interphase (SEI) layers at Li metal anode and Mn-rich cathode. Studies of the correlation between SEI stability, performance, and battery safety will be discussed in the meeting. Acknowledgements This research was supported by the Ministry of Trade, Industry & Energy (20007034) and National Research Foundation grant funded by the Ministry of Science and ICT (2019R1A2C1084024 & RS-2023- 00217581) of Korea.

We need batteries to get the best out of renewable energies and other low-carbon energy sources, and the most promising path forward is to invest in high-energy-density battery technologies. In this regard, lithium metal is the best candidate for the anode electrode as it is the lightest metal on earth and has the lowest electrochemical potential (-3.04 V vs. SHE). However, the challenge to overcome for mass commercializing lithium-metal batteries (LMB) is stabilizing the solid electrolyte interphase that naturally grows at the electrode-electrolyte interface to avoid uncontrolled reactions leading to lithium depletion. Since the successful introduction of lithium-ion batteries (LIB), it has been known that tuning of the SEI composition and morphology is fundamental to prolong the battery life span; a well-engineered SEI layer simultaneously serves as an electron barrier and favors Li+ ion conduction across it, ensuring proper battery performance. However, the engineering of the SEI layer in LMB is more complex than its counterpart LIB batteries, given that lithium metal is overwhelmingly more reactive than graphite and the overall Li+ ion current across it is orders of magnitude higher. The up-to-date knowledge on the SEI morphology indicates that inorganic phases produced upon the decomposition of lithium salts present in the electrolyte tends to grow dominantly buried within the SEI layer, acting as an intermediate between the surviving lithium metal and the outermost organic SEI phase grown after decomposition of solvent molecules. The effect of electrolyte additives and diluents is to tweak the SEI composition. The narrative built after years of experimentation tells that proper battery functioning depends heavily on the ability of the incoming Li+ ions to desolve near the SEI outermost layer without triggering further side reactions, penetrate the inner SEI, and deposit in the anode as reduced lithium. However, the intricacies of the elementary reactions and the stage where the reduction takes place still fall beyond detailed comprehension, even though the development of in situ and operando analytical techniques has brought us a level of understanding on the subject that was unimaginable a few decades ago. In this talk, we discuss the instrumental impact that multiscale modeling techniques have played in clarifying the elementary steps of the SEI formation on pristine lithium metal, providing a comprehensive understanding of the precursors formed in the early stages of Solid-Electrolyte Interphase (SEI) growth. For instance, density functional theory (DFT) calculations have revealed that electrolyte diluents, such as TTE, previously considered inert to lithium metal, actively modify the liquid electrolyte solvation structure by weakly interacting with Li+ ions. Additionally, these diluents decompose against lithium metal, releasing fluoride ions and inundating the SEI layer with LiF. Similarly, DFT-based molecular dynamics (MD) techniques, including ab initio (AIMD) and reactive classical molecular dynamics methods (ReaxFF MD, among others), have facilitated a picoseconds (ps) scale observation of the temporal evolution of these SEI precursors, propelling a mechanistic understanding of the dynamics of the SEI formation; it is now recognized that there is an initial and rapid electrolyte decomposition occurring within the first tens of picoseconds after contact with lithium metal, preceding a longer-scale mass transfer segregation process leading to the formation of a myriad of organic and inorganic microphases within the SEI structure. However, the accessible time and space windows to MD methods fall within few hundred ps, leaving out the study of the morphological aspects of the SEI over extended cycling. In this sense, we discuss through kinetic Monte Carlo (kMC) calculations the evolution of the SEI formation on lithium metal and confirm the critical role that dislocations and grain boundaries play in ensuring proper lithium plating and mobility within the SEI layer over cycling. We confirm that bulk lithium diffusion within the inorganic SEI microphases, such as LiF and Li2O, is significantly lower than lithium mobility across LiF/Li2O interfaces. We also discuss the impact of electrolyte tunning on SEI morphology and provide insights into developing an SEI formation strategy based on the electrolyte molecules electrochemical stability and their relative contents of heteroatom species, such as F and O, to seed in the SEI composition and morphology, which we believe could have a significant impact on the development of stable LMB batteries.

No abstract available

Localized high-concentration electrolytes (LHCEs) are very promising strategies for the high-energy-density lithium (Li) metal batteries (LMBs). Nonsolvating diluents introduced in the LHCEs plays a critical role in physicochemical properties of LHCE and the overall LMB performance. However, there is a lack of design strategies for ideal nonsolvating diluents, and the reported cases are limited to fluorinated nonsolvating diluents (FNDs). FNDs suffer from accelerated decomposition at lithium metal, leading to electrolyte dry-up and ultimately battery failure. Furthermore, the high cost and potential environmental hazards of FNDs necessitate the development of non-fluorinated nonsolvating diluents (NFNDs). Here, we present a design rule for the ideal NFNDs by spectroscopically characterizing the Li+ solvation ability and miscibility. Our design rule identifies the ideal NFNDs, based on the superior cycling performane of candidate diluents over 350 cycles (99.0% ethoxybezene), 500 cycles (98.5% anisole), and 1400 cycles (99.0%, furan). NMR spectra revealed that the designed NFNDs were highly stable in electrolytes during extended cycles. Raman spectroscopy and theoretical calculation reveal that resonance of an electron pair on the oxygen atom of NFND molecules decreases the lithium-ion solvation ability, thereby achieving desirable non-solvating characteristics while maintaining good miscibility, superior cathodic stability, and low prices. Figure 1

Despite the reported benefits of lithium difluorophosphate (LiDFP), studies on its physical and electrochemical properties remain limited. This work systematically investigates LiDFP and its potential for lithium metal battery (LMB) electrolytes using a combined experimental and theoretical approach. Solubility, ionic conductivity, viscosity, lithium‐ion transference number, diffusion coefficient, and contact angle were experimentally evaluated to provide a comprehensive understanding of its behavior. A key finding was the decoupling of ionic conductivity and viscosity at high concentrations. Additionally, Raman and NMR spectroscopy, along with molecular dynamics simulations, revealed the formation of large cation‐anion aggregates at high concentrations, which facilitated lithium‐ion transport and contributed to the stabilization of the solid electrolyte interphase. The results reported herein emphasize the potential of LiDFP as an attractive component for advanced electrolyte formulations in energy storage, providing new insights into optimizing LMB performance.

Electrolytes play a decisive role in governing the electrochemical performance of Li-metal batteries (LMB). In this paper, we suggest synthesis and electrochemical study of fluorinated ethoxymethoxyalkanes as potential candidates for new-generation electrolyte solvents for LMB. 1- Methoxy-2-(2,2,2-trifluoroethoxy)propane (3FEMP) and 1-methoxy-2-(2,2,2-trifluoroethoxy)butane (3FEMB) were tested in Li||NMC622 and Li||NMC811 cell configurations revealing high coulombic efficiencies exceeding 99.85% (99.75% for Li||NMC811) and 99.70% (99.95% for Li||NMC811) and specific discharge capacity retention of 90% and 99% over 55 cycles for potentials up to 4.5 V for 3FEMP and 3FEMB respectively. This study opens up new perspectives in targeted design of organic ether molecules as LMB electrolyte components.

Metallic lithium as the anode material in batteries offer extraordinarily high specific capacity and low electrochemical potential, allowing lithium metal batteries (LMBs) to achieve gravimetric energy densities unobtainable by traditional intercalation-based chemistry. However, one must control the morphology and composition of its solid electrolyte interphase (SEI) in order to suppress the growth of separator-piercing Li dendrites and combat electrolyte depletion. Here, we find the usage of small amounts of organofluorine additives to the commercial ethylene carbonate and diethyl carbonate (EC-DEC) electrolyte mixture improves the specific capacity and capacity retention (>99% over 100 cycles at C/3 rate) of LiNi8.15Co1.5Al0.35O2 (NCA) LMB cells. Esters, carboxylic acids, and ketoesters with various degrees of fluorination were explored as potential electrolyte additives. Figure 1

Significance Lithium metal batteries (LMBs) hold tremendous potential for next-generation energy storage due to their high energy density, but their commercial adoption is hindered by poor stability and safety concerns. This work introduces an electrolyte design strategy that uses minimal fluorination combined with a modified molecular backbone structure to achieve stable, high-performance LMBs. Unlike previous approaches that relied on heavy fluorination—which raises environmental concerns and reduces ion transport—this electrolyte achieves excellent performance with just two fluorine atoms per molecule. The electrolyte enables faster charging, better stability, and reduced formation of dead lithium compared to existing solutions. This work demonstrates that strategic molecular design can achieve optimal battery performance.

No abstract available

Solid‐state electrolytes (SSEs) hold significant potential for advancing lithium metal batteries (LMBs) by enhancing safety through the replacement of liquid electrolytes. However, challenges such as low ionic conductivity, limited electrochemical stability, and poor electrolyte/electrode interface compatibility hinder the development of high‐energy‐density LMBs. Herein, a strategy for designing SSEs is proposed using multiple‐bridge engineered composite elastomer electrolytes (CEEs) that incorporate ion‐rotating dipole interactions, ion‐anchoring dipole interactions, and hydrogen bonding, along with a CEE‐based composite elastomer cathode (CEC). This design combines a volume‐adaptive elastomer matrix, a high‐Li+ conducting deep eutectic electrolyte, and robust nanowires. The resultant CEE exhibits high ionic conductivity (1.7 × 10−3 S cm−1), a lithium transference number of 0.72, and a wide electrochemical stability window (up to 4.9 V) at 298 K. The engineered uniform Li+ flux also promotes stable Li plating/stripping for over 900 h at 0.1 mA cm−2. Furthermore, the LFP‐based CEC|CEE|Li full cells deliver a reversible capacity of 133 mAh g−1 with 95% retention after 300 cycles in coin cells, and 129 mAh g−1 with 96% retention after 250 cycles in pouch cells at 1 C. This strategy presents a promising approach for designing solid‐state polymer electrolytes to extend the lifespan of high‐energy‐density LMBs.

Solid-state electrolytes (SSEs) are increasingly recognized for their potential to enhance the performance of lithium-metal batteries (LMBs). In this study, to tackle the inherent trade-offs in SSEs between mechanical stability and ionic conductivity, we propose a composite solid electrolyte (CSE) by integrating perovskite Li1.5La1.5TeO6 (LLTeO) with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and a polymer blend of poly(methyl methacrylate) (PMMA) and poly(vinylidene fluoride) (PVDF). This rational design features an ion-conducting double-network, enhanced mechanical flexibility, and robustness, which facilitate improved ion migration, excellent compatibility with lithium electrodes, and effective dendrite suppression. The CSE demonstrates a mechanical strength of 27 MPa, an impressive ionic conductivity of 0.826 mS cm-1, and a broad electrochemical window of 4.88 V. The Li//Li symmetric cells display stable cycling for over 600 h at 1 mA cm-2. Additionally, the corresponding Li//LiFePO4 (LFP) and Li//LiNi0.8Co0.1Mn0.1O2 (NCM811) cells exhibit remarkable rate performance and cyclic stability. Specifically, the Li/CSE/LFP cell sustains a high capacity of 131.7 mAh g-1 after 300 cycles at 3C, achieving a capacity retention rate of 98.1% and an average Coulombic efficiency of 100%. This research presents a viable strategy for the development of solid-state LMBs, offering high energy density, extended cycle life, and enhanced safety.

In the pursuit of high-energy-density lithium metal batteries (LMBs), the development of stable solid electrolyte interphase (SEI) is critical to address issues such as lithium dendrite growth and low Coulombic efficiency. Herein, we propose a facile strategy for the in-situ fabrication of a LiCl-rich artificial SEI layer on Li surfaces through reaction of MoCl5 with Li (Li@MoCl5). The resulting artificial SEI significantly enhances the uniformity of Li deposition, effectively suppresses dendrite formation, and improves electrochemical performance. As a result, Li@MoCl5 symmetric cells demonstrate remarkable stability, achieving continuous cycling of 4200 h under a high current density of 10 mA cm-2 with an areal capacity of 1 mAh cm-2. Full-cells employing Li@MoCl5 exhibit superior cycling stability and rate capability, even at high cathode loading (17 mg cm-2). These results highlight the potential of this interface engineering strategy for advanced practical application of LMBs.

Lithium-metal batteries (LMBs) incorporating nickel-rich cathodes have the potential to achieve superior energy densities. However, challenges associated with the electrolyte-electrode interphases (EEIs) have impeded the successful transition of these advanced systems into practical applications. In this study, azidotrimethylsilane (ATMS) is introduced as a multifunctional additive for traditional carbonate-based electrolytes. The azido group in ATMS plays a dual role in electrochemical reactions, with multiple nitrogen (N) atoms engaging in both nucleophilic and electrophilic interactions. These N atoms tend to undergo preferential oxidation reactions at the cathode, forming a stable cathode electrolyte interphase, while also undergoing preferential reduction reactions at the anode to inhibit lithium dendrite growth. The Si-N bond in the ATMS structure has unique reactivity, effectively neutralizing HF produced from LiPF6 decomposition, thus preventing the recurrent formation of EEIs in the battery. As a result, the long-cycle performance of Li||NCM811 is significantly improved, with capacity retention increasing from 34.7% in baseline electrolyte to 82.6% after 600 cycles. Similarly, ATMS enhances the cycling performance of Li||Li symmetric cells, extending their lifespan to over 800 h, and improves the Coulombic efficiency of Li||Cu cells from 81.6 to 91.6%. The synergistic effect of ATMS on both anodes and cathodes further significantly enhances the high-voltage performance of the LMBs.

The rapid development of the electronics market necessitates energy storage devices characterized by high energy density and capacity, alongside the ability to maintain stable and safe operation under harsh conditions, particularly elevated temperatures. In this study, a semi‐solid‐state electrolyte (SSSE) for Li‐metal batteries (LMB) is synthesized by integrating metal–organic frameworks (MOFs) as host materials featuring a hierarchical pore structure. A trace amount of liquid electrolyte (LE) is entrapped within these pores through electrochemical activation. These findings demonstrate that this structure exhibits outstanding properties, including remarkably high thermal stability, an extended electrochemical window (5.25 V vs Li/Li+), and robust lithium‐ion conductivity (2.04 × 10−4 S cm−1), owing to the synergistic effect of the hierarchical MOF pores facilitating the storage and transport of Li ions. The Li//LiFePO4 cell incorporating prepared SSSE shows excellent capacity retention, retaining 97% (162.8 mAh g−1) of their initial capacity after 100 cycles at 1 C rate at an extremely high temperature of 95 °C. It is believed that this study not only advances the understanding of ion transport in MOF‐based SSSE but also significantly contributes to the development of LMB capable of stable and safe operation even under extremely high temperatures.

Solid‐state electrolytes (SSEs) are key to unlocking the potential of lithium metal batteries (LMBs), but their high thickness (>100 µm) due to poor mechanical properties limits energy density improvements. Herein, an ultrathin (≈5 µm) polymer SSE with a high Young's modulus (10.6 GPa), made from a polyvinylidene fluoride‐hexafluoropropylene (PVDF‐HFP) matrix and an ethylene diamine tetraacetic acid (EDTA) additive is proposed. By virtue of the electron‐donating property, EDTA induces the conformation transformation of PVDF‐HFP, enhancing the mechanical strength by a fine‐grain strengthening mechanism. In addition, PVDF‐HFP with cis‐conformation shortens the pathway for Li+, promotes the Li+ dissociation and immobilizes the anions of lithium salt, thus increasing the ionic conductivity (2.47 × 10−4 S cm−1) and transfer number (0.59) of the electrolyte. Moreover, the electrolyte also possesses a wide voltage window (4.7 V) and good heat/flame resistance. The half cells and full cells with the electrolytes show good cycling and rate performance. Notably, a pouch cell based on the electrolyte exhibits impressive energy densities of 516 Wh kg−1 and 1520 Wh L−1 (excluding packages), showing great potential for practical use in LMBs.

Ultra-low-temperature lithium metal batteries face significant challenges, including sluggish ion transport and uncontrolled lithium dendrite formation, particularly at high power. An ideal electrolyte requires high carrier ion concentration, low viscosity, rapid de-solvation, and stable interfaces, but balancing these attributes remains a formidable task. Here, we design and synthesize a multifunctional additive, perfluoroalkylsulfonyl quaternary ammonium nitrate (PQA-NO3), which features both cationic (PQA+) and anionic (NO3−) components. PQA+ reacts in situ with lithium metal to form an inorganic-rich solid-electrolyte interphase (SEI) that enhances Li+ transport through the SEI film. NO3− creates an anion-rich, solvent-poor solvation structure, improving oxidation stability at the positive electrode/electrolyte interface and reducing Li+-solvent interactions. This allows ether-based electrolytes to achieve high voltage tolerance, increased ionic conductivity, and lower de-solvation energy barriers. The Li (40 µm)||NMC811 (3 mAh cm−2) coin cells with the developed electrolyte exhibited stable cycling at -60 °C and a 450 Wh kg−1 pouch cell retained 48.1% capacity at -85 °C, achieving a specific energy (except tabs and packing foil, same hereafter) of 171.8 Wh kg−1. Additionally, the pouch cell demonstrated a discharge rate of 3.0 C at -50 °C, reaching a specific power (except tabs and packing foil, same hereafter) of 938.5 W kg−1, indicating the electrolyte’s suitability for high-rate lithium metal batteries in extreme low-temperature environments. Ultra-low-temperature lithium metal batteries struggle with slow ion transport and dendrite growth. Here, authors develop a multifunctional electrolyte additive (PQA-NO3) that forms a protective SEI layer and modifies ion interactions, enabling stable operation at extreme cold condition of −85 °C.

No abstract available

Coulombic efficiency (CE) is a quantifiable indicator for the reversibility of lithium metal anodes in high-energy-density batteries. However, the quantitative relationship between CE and electrolyte properties has yet to be established, impeding rational electrolyte design. Herein, an interpretable model for estimating CE based on data-driven insights of electrolyte properties is proposed. Hydrogenbond acceptor basicity (β) and the energy level gap between the lowest unoccupied and the highest occupied molecular orbital (HOMO-LUMO gap) of solvents are identified as the top two parameters impacting CE by machine learning. β and HOMO-LUMO gap of solvents govern anode interphase chemistry. A regression model is further proposed to estimate the CE based on β and HOMOLUMO gap. Using the new solvent screened by above regression model, the Li metal anode in the pouch cell with an energy density of 418 Wh kg-1 achieves the highest CE of 99.2%, which is much larger than previous CE ranging from 70-98.5%. This work provides a reliable interpretable quantitative model for rational electrolyte design.

Electrolyte is the key component dictating lithium battery performance, especially under extreme conditions such as fast cycling and low temperatures. However, conventional electrolyte design principles, which generally rely on a homogeneous mixture of solvents, salts, and functional additives, fail to simultaneously meet the requirements for both anodic/cathodic interfacial stability and bulk ion-transport kinetics in lithium metal batteries. Herein, we present a self-compartmented electrolyte design methodology. Lithium 4,5-dicyano-2-(trifluoromethyl)imidazol-1-ide (LiTDI), featuring the ability to selectively self-assemble on the cathode/electrolyte interface, compartmented the electrolyte into a heterogonous one. Close to the cathode side, LiTDI could induce an interfacial high-concentration region, where the anion-rich solvation structure facilitates the formation of a stable cathode-electrolyte interphase (CEI). In the bulk, the electrolyte maintains a low concentration with low viscosity, ensuring fast ion transport and superior rate performance. Li||NCM811 cells achieve over 500 stable cycles with 80.3% capacity retention and deliver 169.3 mAh g-1 at a 10C discharge rate. Under low-temperature conditions (-20 ℃), the cells maintained outstanding stability over 700 cycles at 0.5C charge/discharge, achieving capacity retention of 96.6% and an average Coulombic efficiency of 99.2%. This work provides a new electrolyte design paradigm, addressing the critical challenges of LMBs for high-voltage and low-temperature applications.

Unwanted side reactions occurring at electrode|electrolyte interfaces significantly impact the cycling life of lithium metal batteries. However, a comprehensive view that rationalizes these interfacial reactions and assesses them both qualitatively and quantitatively is not yet established. Here, by combining multiple analytical techniques, we systematically investigate the interfacial reactions in lithium metal batteries containing ether-based non-aqueous electrolyte solutions. We quantitatively monitor various nanoscale-driven processes such as the reduction and oxidation pathways of lithium salt and organic solvents, the formation of various solid-electrolyte interphase species, the gas generation within the cell and the cross-talk processes between the electrodes. We demonstrate that the consumption of lithium ions owing to the continuous decomposition of the lithium bis(fluorosulfonyl)imide salt, which dominates the interfacial reactions, results in ion depletion during the cell discharge and battery failure. On the basis of these findings, we propose an electrolyte formulation in which lithium bis(fluorosulfonyl)imide content is maximized without compromising dynamic viscosity and bulk ionic conductivity, aiming for long-cycling battery performance. Following this strategy, we assemble and test Li (20 μm thickness)||LiNi0.8Mn0.1Co0.1O2 (17.1 mg cm−2 of active material) single-layer stack pouch cells in lean electrolyte conditions (that is, 2.1 g Ah−1), which can effectively sustain 483 charge (0.2 C or 28 mA)/discharge (1 C or 140 mA) cycles at 25 °C demonstrating a discharge capacity retention of about 77%. Tailored non-aqueous electrolyte solutions are formulated using data obtained from extensive analytical measurements and analyses. These optimized electrolytes improve the cycling performance of single-layer stack lithium metal pouch cells, particularly in lean electrolyte conditions.

Developing solvents with balanced physicochemical properties for high-voltage cathodes and lithium metal anodes is crucial for a sustainable and intelligent future. Herein, we report fully methylated tetramethyl-1,3-dimethoxydisiloxane (TMMS) as a single solvent for lithium metal batteries. We demonstrate that the fully methylated structure and Si-O bonds within TMMS can effectively elevate the dehydrogenation energy barrier, migrating the oxidation decomposition of the electrolyte. Additionally, the weak solvating power of TMMS favors the formation of an anion-rich solvation structure that induces the generation of an inorganic-rich electrode/electrolyte interphase layer at both the cathode and anode. Accordingly, the formulated electrolyte exhibits remarkable stability against high-voltage cathodes and lithium metal anodes. Notably, LiNi0.8Co0.1Mn0.1O2||Li (NCM811||Li) full cells with TMMS-based electrolytes realize a significant improvement in capacity retention compared with a dimethoxyethane-based electrolyte at both room temperature and 50 °C. This work provides insight into full methylation and the Si-O bond strategy and paves the way for the development of high-voltage lithium metal batteries.

Stable operation of Li metal batteries with gel polymer electrolytes in a wide temperature range is highly expected. However, insufficient dynamics of ion transport and unstable electrolyte-electrode interfaces at extreme temperatures greatly hinder their practical applications. We report a bioinspired gel polymer electrolyte that enables high-energy-density Li metal batteries to work stably in a wide temperature range from –30 to 80 °C. The wide-temperature gel polymer electrolyte is fabricated by using a branched polymer of which side chains are double coupled with their asymmetric analogues. The double dipole coupling regulates the Li+ coordination environment to form a weak solvation structure that offers fast and uniform Li+ deposition at extreme temperatures. Consequently, the non-flammable gel polymer electrolyte displays an ionic conductivity of 1.03 × 10–4 S cm−1 at –40 °C and a Li+ transference number of 0.83. The Li metal batteries with LiNi0.8Co0.1Mn0.1O2 positive electrode deliver initial specific discharge capacities of 121.4 mAh g–1 at –30 °C and 172.2 mAh g–1 at 80 °C, with corresponding discharge currents of 18.8 mA g–1 and 188 mA g–1, respectively. Additionally, a pouch cell delivers a specific energy up to 490.8 Wh kg−1. Lithium-metal batteries struggle in extreme environments, restricting their applications. Here, authors report a bioinspired gel polymer electrolyte that employs double dipole coupling to form a weak solvation structure, enabling stable operation of lithium-metal batteries from −30 to 80 °C.

Polyethylene oxide (PEO)‐based solid polymer electrolytes exhibit promising commercial prospects due to their superior processability and scalability. However, limited ion transport and unstable electrode/electrolyte interface restrict their practical application. Herein, the paraelectric strontium titanate (STO) is introduced into PEO‐based electrolytes to solve those problems. The electrostatic force originating from polarized STO weakens the coordination between EO and Li+ and releases more free Li+, thus promoting ion transport inside the electrolyte. Numerous STOs form a new reverse electric field that inhibits lithium dendrites' vertical growth at the anode interface. Polarized STO triggers the generation of LiF, Li2O, and Li3N‐riched solid electrolyte interphase (SEI), contributing to interfacial stability and Li+ mobility. Consequently, polarized STO‐modified PEO‐based solid electrolyte has an outstanding ion conductivity of 0.61 mS cm−1 with a superior lithium stability of 5.29 V. Li/Li symmetric battery with STO‐modified electrolyte undergoes >1200 h at 0.2 mA cm−2. A large capacity retention of 85.3% after 850 cycles at 1 C is achieved for LFP/Li battery and be cycled 600 times even against a high‐loading cathode (LFP:6 mg cm−2). This study provides a novel strategy to prepare composite‐modified solid‐state electrolytes that can be utilized in lithium metal batteries.

Polymers with strong electron-withdrawing groups (e.g., cyano-containing polymers) are attractive for a wide range of applications due to their high dielectric constant and outstanding electrochemical stability. However, the polymerization of such monomers is difficult to control with trace of water affording instant reactions, and copolymerization with other monomers without using strong acid is even more challenging. The present study demonstrates a facile approach enabling efficient and controllable copolymerization of ethyl cyanoacrylate (ECA) without adding undesired additives, achieving mechanically robust and high ion-conduction gel polymer electrolyte (GPE) for safe and long cycle-life lithium-metal batteries (LMBs). The incorporated dual-lithium salts, i.e., lithium difluoro(oxalato)borate (LiDFOB) and lithium bis(trifluoromethanesulphonyl)imide (LiTFSI) not only facilitate radical polymerization of ECA monomers by suppressing their anionic polymerization, but also promote the formation of high-ionic conducting GPE. The incorporated methyl methacrylate (MMA) monomer accelerates the radical polymerization of ECA (confirmed by DFT calculations), achieving controlled copolymerization of ECA-based copolymers. The mechanically robust polymer network made by the ECA copolymer enables LMBs with both LFP cathodes and high-voltage LCO cathodes (4.5 V) operatable at different temperatures with ultra-long cycle life at 1 C (capacity retention of 81.1% and 83.8%, respectively, over 1000 cycles).

The components and structures of the solid-electrolyte interphase (SEI) are critical for stable cycling of lithium metal batteries (LMBs). LiF has been widely studied as the dominant component of SEI, but Li2O, which has a much lower diffusion barrier for Li+, has rarely been investigated as the dominant component of SEI. The effect of Li2O-dominated SEI on electrochemical performance still remains elusive. Herein, an ultrastrong coordinated cosolvation diluent, 2,3-difluoroethoxybenzene (DFEB), is designed to modulate solvation structure and tailor Li2O-dominated SEI for stable LMBs. In the DFEB-based LHCE (DFEB-LHCE), DFEB intensively participates in the first solvation shell and synergizes with FSI- to tailor an Li2O-dominated inorganic-rich SEI which is different from the LiF-dominated SEI formed in conventional LHCE. Benefiting from this special SEI architecture, a high Coulombic efficiency (CE) of 99.58% in Li||Cu half cells, stable voltage profiles, and dense and uniform lithium deposition, as well as effective inhibition of Li dendrite formation in the symmetrical cell, are achieved. More importantly, the DFEB-LHCE can be matched with various cathodes such as LFP, NCM811, and S cathodes, and the Li||LFP full cell using DFEB-LHCE possesses 85% capacity retention after 650 stable cycles with 99.9% CE. Especially the 1.5 Ah practical lithium metal pouch cell achieves an excellent capacity retention of 89% after 250 cycles with a superb average CE of 99.93%. This work unravels the superiority of the Li2O-dominated SEI and the feasibility of tailoring SEI components through modulation of solvation structures.

Solid polymer electrolytes (SPEs) are regarded as promising candidates that could address the safety concerns associated with liquid electrolytes. Nonetheless, SPEs are still confronting serious lithium dendrite issues, and there is a lack of systematic studies regarding the formation of lithium dendrites within SPEs. Herein, Sand equation is employed to elucidate the determinants of dendrite growth in SPEs, revealing that three factors including the Li+ transference number, Li+ diffusion coefficient, and Li+ concentration are positively correlated with Sand's time (τ) which determine the plating/striping behaviors of Li anode. More importantly, an effective and universal approach is proposed to construct dendrite‐free polymer lithium metal batteries with dual‐Lewis‐acid materials such as Zinc Borate (ZB). Endowed with ZB materials, the PVDF‐HFP based electrolyte possesses sufficient Li+ supply and swift transport channel and thus achieves an impressively high Li+ transference number of 0.9 and outstanding ionic conductivity at 30 °C (9.2 × 10−4 S cm−1), outperforming the polymer electrolytes with single Lewis‐acid fillers. The electrolyte imparts the LFP//Li cell with exceptional capacity retention, showing almost no decay in discharge capacity even after 700, 500, and 300 cycles at 2 C, 3 C, and 5 C, respectively. Additionally, it capacitates the LiNi0.6Mn0.2Co0.2O2//Li cell to outperform by achieving over 1900 cycles at 1C and stably cycling under a cut‐off voltage of 4.5V.

High-safety and high-energy-density solid-state lithium metal batteries (SSLMBs) attract tremendous interest in both academia and industry. Especially, composite polymer electrolytes (CPEs) can overcome the limitations of single-component solid-state electrolytes. In this work, a strategy of combining a rigid functional skeleton with a soft polymer electrolyte to prepare reinforced CPEs was adopted. The in situ grown zeolitic imidazolate frameworks (ZIFs) with three-dimensional cellulose fiber skeleton (ZIF-67@CF) and succinonitrile (SN) plasticizer into poly(ethylene oxide) (PEO) together form ZIF-67@CF/PEO-SN CPEs. The addition of ZIF-67@CF and SN to PEO synergistically enhanced the physical and electrochemical properties of CPEs. Furthermore, the conduction mechanism of lithium-ion (Li+) in CPEs was studied using density functional theory. It is impressive that the ZIF-67@CF/PEO-SN CPEs at 30 °C exhibit a high ionic conductivity of 1.17 × 10-4 S cm-1, a competitive Li+ transference number of 0.40, a wide electrochemical window of 5.0 V, a notable tensile strength of 18.7 MPa, and superior lithium plating/stripping stability (>550 h at 0.1 mA cm2). Such favorable features endowed LiFePO4/(ZIF-67@CF/PEO-SN)/Li cell at 30 °C with a high discharging capacity (152.5 mA h g-1 at 0.2 C), a long cycling lifespan (>150 cycles with 99% capacity retention), and superior operating safety. This work provides insights and promotes the application of functionalized CPEs for SSLMBs.

The solid electrolyte interphase (SEI) with lithium fluoride (LiF) is critical to the performance of lithium metal batteries (LMBs) due to its high stability and mechanical properties. However, the low Li ion conductivity of LiF impedes the rapid diffusion of Li ions in the SEI, which leads to localized Li ion oversaturation dendritic deposition and hinders the practical applications of LMBs at high‐current regions (>3 C). To address this issue, a fluorophosphated SEI rich with fast ion‐diffusing inorganic grain boundaries (LiF/Li3P) is introduced. By utilizing a sol electrolyte that contains highly dispersed porous LiF nanoparticles modified with phosphorus‐containing functional groups, a fluorophosphated SEI is constructed and the presence of electrochemically active Li within these fast ion‐diffusing grain boundaries (GBs‐Li) that are non‐nucleated is demonstrated, ensuring the stability of the Li || NCM811 cell for over 1000 cycles at fast‐charging rates of 5 C (11 mA cm−2). Additionally, a practical, long cycling, and intrinsically safe LMB pouch cell with high energy density (400 Wh kg−1) is fabricated. The work reveals how SEI components and structure design can enable fast‐charging LMBs.

Unstable interphase formed in conventional carbonate-based electrolytes significantly hinders the widespread application of lithium metal batteries (LMBs) with high-capacity nickel-rich layered oxides (e.g., LiNi0.8Co0.1Mn0.1O2, NCM811) over a wide temperature range. To balance ion transport kinetics and interfacial stability over wide temperature range, herein a bifunctional electrolyte (EAFP) tailoring the electrode/electrolyte interphase with 1,3-propanesultone as an additive was developed. The resulting cathode-electrolyte interphase with an inorganic inner layer and an organic outer layer possesses high mechanical stability and flexibility, alleviating stress accumulation and maintaining the structural integrity of the NCM811 cathode. Meanwhile, the inorganic-rich solid electrolyte interphase inhibits electrolyte side reactions and facilitates fast Li+ transport. As a result, the Li||Li cells exhibit stable performance in extensive temperatures with low overpotentials, especially achieving a long lifespan of 1000 h at 30 °C. Furthermore, the optimized EAFP is also suitable for LiFePO4 and LiCO2 cathodes (1000 cycles, retention: 67%). The Li||NCM811 and graphite||NCM811 pouch cells with lean electrolyte (g/Ah grade) operate stably, verifying the broad electrode compatibility of EAFP. Notably, the Li||NCM811 cells can operate in wide climate range from -40 °C to 60 °C. This work establishes new guidelines for the regulation of interphase by electrolytes in all-weather LMBs.

Ultrathin all‐solid‐state electrolytes with an excellent Li+ transport behavior are highly desirable for developing high‐energy‐density solid‐state lithium metal batteries. However, how to balance the electrochemical performance and their mechanical properties remains a huge challenge. Herein, an ultrathin solid electrolyte membrane with a thickness of only 3 µm and a weight of 11.7 g m−2 is well constructed by integrating individual functionalized organic with inorganic modules. Impressively, the optimized hybrid electrolyte membrane shows a set of merits including a high room‐temperature ionic conductivity of 1.77 × 10−4 S cm−1, large Li+ transference number of 0.65, and strong mechanical strength (strength of 29 MPa, elongation of 95%), as well as negligible thermal shrink at 180 °C. The analysis results reveal that the lithium sulfonate‐functionalized mesoporous silica nanoparticles in the membrane play a crucial role in the selective transport of Li+ through anion trapping and cation exchange. The pouch full cell is further assembled with a high‐voltage NCM cathode and thin lithium anode, which exhibits excellent long‐term cycling stability, outstanding rate performance at room temperature, and high safety against abused conditions. The current work provides an innovative strategy for achieving lithium metal batteries with ultrathin all‐solid‐state electrolytes.

Lithium metal batteries utilizing lithium metal as the anode can achieve a greater energy density. However, it remains challenging to improve low-temperature performance and fast-charging features. Herein, we introduce an electrolyte solvation chemistry strategy to regulate the properties of ethylene carbonate (EC)-based electrolytes through intermolecular interactions, utilizing weakly solvated fluoroethylene carbonate (FEC) to replace EC, and incorporating the low-melting-point solvent 1,2-difluorobenzene (2FB) as a diluent. We identified that the intermolecular interaction between 2FB and solvent can facilitate Li+ desolvation and lower the freezing point of the electrolyte effectively. The resulting electrolyte enables the LiNi0.8Co0.1Mn0.1O2||Li cell to operate at -30 °C for more than 100 cycles while delivering a high capacity of 154 mAh g-1 at 5.0C. We present a solvation structure and interfacial model to analyze the behavior of the formulated electrolyte composition, establishing a relationship with cell performance and also providing insights for the electrolyte design under extreme conditions.

Localized highly concentrated electrolytes have revitalized the advancement of secondary batteries. However, fluorinated diluents typically have the drawbacks of high toxicity, serious environmental pollution, challenging synthesis, and high cost. This work develops a low‐cost, eco‐friendly localized highly concentrated electrolyte by utilizing benzene as a diluent, simultaneously achieving highly reversible lithium‐metal anodes and long‐term stable cycling of single crystal LiNi0.8Co0.1Mn0.1O2 (SC811) cathode. The unique conjugated structure and absence of electron‐withdrawing groups provide benzene the decent redox stability and inertness, which enables it to modulate the highly concentrated solvation structure. The PhH‐LHCE supports SC811‐Li cells with a cathode loading of 9 mg cm−2 achieving 87.3% capacity retention after 450 cycles. Cells consisting of ultra‐high loading Ni83 cathode (≈31 mg cm−2) and ultra‐thin Li (50 µm) anode achieve stable 70 cycles with a lean electrolyte condition. This work can be generalized to promising electrochemical energy storage systems such as sodium and potassium metal batteries to solve the cost and environmental pollution problems in the large‐scale production process.

The practical application of lithium metal batteries (LMBs) has been hindered by limited cycle-life and safety concerns. To solve these problems, we develop a novel fluorinated phosphate cross-linker for gel polymer electrolyte in high-voltage LMBs, achieving superior electrochemical performance and high safety simultaneously. The fluorinated phosphate cross-linked gel polymer electrolyte (FP-GPE) by in-situ polymerization method not only demonstrates high oxidation stability but also exhibits excellent compatibility with lithium metal anode. LMBs utilizing FP-GPE realize stable cycling even at a high cut-off voltage of 4.6 V (vs Li/Li+) with various high-voltage cathode materials. The LiNi0.6Co0.2Mn0.2O2|FP-GPE|Li battery exhibits an ultralong cycle-life of 1200 cycles with an impressive capacity retention of 80.1%. Furthermore, the FP-GPE-based batteries display excellent electrochemical performance even at practical conditions, such as high cathode mass loading (20.84 mg cm-2), ultrathin Li (20 μm), and a wide temperature range of -25 to 80 ℃. Moreover, the first reported solid-state 18650 cylindrical LMBs have been successfully fabricated and demonstrate exceptional safety under mechanical abuse. Additionally, the industry-level 18650 cylindrical LiMn2O4|FP-GPE|Li4Ti5O12 cells demonstrate a remarkable cycle-life of 1400 cycles. Therefore, the impressive electrochemical performance and high safety in practical batteries demonstrate a substantial potential of well-designed FP-GPE for large-scale industrial applications.

Lithium‐rich manganese‐based layered oxides (LRMOs) are promisingly used in high‐energy lithium metal pouch cells due to high specific capacity/working voltage. However, the interfacial stability of LRMOs remains challenging. To address this question, a novel armor‐like cathode electrolyte interphase (CEI) model is proposed for stabilizing LRMO cathode at 4.9 V by exploring partially fluorinated electrolyte formulation. The fluoroethylene carbonate (FEC) and tris (trimethylsilyl) borate (TMSB) in formulated electrolyte largely contribute to the formation of 4.9 V armor‐like CEI with LiBxOy and LixPOyFz outer layer and LiF‐ and Li3PO4‐rich inner part. Such CEI effectively inhibits lattice oxygen loss and facilitates the Li+ migration smoothly for guaranteeing LRMO cathode to deliver superior cycling and rate performance. As expected, Li||LRMO batteries with such electrolyte achieve capacity retention of 85.7% with high average Coulomb efficiency (CE) of 99.64% after 300 cycles at 4.8 V/0.5 C, and even obtain capacity retention of 87.4% after 100 cycles at higher cut‐off voltage of 4.9 V. Meanwhile, the 9 Ah‐class Li||LRMO pouch cells with formulated electrolyte show over thirty‐eight stable cycling life with high energy density of 576 Wh kg−1 at 4.8 V.

Lithium metal batteries (LMBs) have become a hot topic in the research of next-generation advanced battery technology due to their high specific energy. However, the high reaction activity between lithium metal and electrolyte is considered one of the key bottlenecks limiting large-scale applications of LMBs. As a classic electrolyte additive, LiNO3 significantly improves the stability of lithium metal in ether-based electrolytes. However, its solubility in carbonate-based electrolytes widely used in lithium-ion batteries is extremely low, and its protective effect on lithium metal is limited, which has become a key obstacle to the commercial application of lithium metal batteries. Here, we enhanced the local negative charge density of carbonyl oxygen atoms in carbonate molecules by introducing electron donors, making it easier for them to coordinate with Li+, thereby weakening the interaction between Li+ and NO3-, and significantly increasing the solubility of LiNO3 in ester electrolytes. The modified ester solvent promotes the derivatization and decomposition of salt anions, leading to the formation of a dense SEI layer rich in LiF and LiNxOy. This significantly improves the stability of lithium metal in ester-based electrolytes. The assembled Li||Li symmetric battery shows excellent cycling performance of over 4000 hours.

Acting as a passive protective layer, solid-electrolyte interphase (SEI) plays a crucial role in maintaining the stability of the Li-metal anode. Derived from the reductive decomposition of electrolytes (e.g., anion and solvent), the SEI construction presents as an interfacial process accompanied by the dynamic de-solvation process during Li-metal plating. However, typical electrolyte engineering and related SEI modification strategies always ignore the dynamic evolution of electrolyte configuration at the Li/electrolyte interface, which essentially determines the SEI architecture. Herein, by employing advanced electrochemical in-situ FT-IR and MRI technologies, we directly visualize the dynamic variations of solvation environments involving Li+-solvent/anion. Remarkably, a weakened Li+-solvent interaction and anion-lean interfacial electrolyte configuration have been synchronously revealed, which is difficult for the fabrication of anion-derived SEI layer. Moreover, as a simple electrochemical regulation strategy, pulse protocol was introduced to effectively restore the interfacial anion concentration, resulting in an enhanced LiF-rich SEI layer and improved Li-metal plating/stripping reversibility.

The serious dendrite formation and safety hazards associated with side reactions hinder the practical application of lithium metal batteries. A molecular customization strategy based on both physical and chemical properties is reported. A copolymer of acrylamide and hexafluorobutyl acrylate molecules is used as an artificial solid electrolyte interface(ASEI) for lithium metal to achieve dynamic interface protection during cycling. The amide group serves as the rigid unit, while the hexafluorobutyl group serves as the flexible unit, and imparts excellent mechanical properties to the copolymer. Synergistically abundant C─F bonds exhibit excellent water and oxygen resistance and have good electrolyte affinity. The ester and amide groups serve as amphiphilic sites for Li+ and PF6−, regulating the ion flux at the interface and achieving dendrite‐free lithium deposition. During cycling, the organic–inorganic composite SEI dynamically evolves to safeguard the lithium metal, preventing undue electrolyte consumption. The copolymer achieves stable cycling for 1500 and 950 h at 1 and 2 mA cm−2, respectively. It demonstrates excellent performance with LiNi0.8Co0.1Mn0.1O2 and LiFePO4 cathodes. This study introduces a new approach to designing polymers at the molecular level to optimize the physical properties/chemical activity of lithium metal interfaces.

The physical structure and chemical composition of the solid electrolyte interphase (SEI) affect the performance of the lithium metal anode. The tuning of the chemical composition and structure of the SEI through the surface modification of the lithium metal anode has been conducted. A series of dicarboxylic acids, oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid have been utilized to modify the surface of the lithium anode. Physical characterization methods have been employed to study the surface morphology and chemical composition of the SEI. Symmetrical (Li/Li) and asymmetrical (NMC622/Li) cells with pristine lithium and surface modified lithium electrodes have been assembled and tested. NMC622/Li cell with surface modified lithium shows improved performance compared to that of pristine lithium. Malonic acid-treated lithium outperforms all the electrodes by retaining 141 mAh/g specific capacity even after 100 cycles of charge-discharge. XPS depth profiling analysis reveals that the SEI on the MA-Li contains evenly distributed organic and inorganic components which are responsible for the performance of MA-Li.

Although great progress has been made in new electrolytes for lithium metal batteries (LMBs), the intrinsic relationship between electrolyte composition and cell performance remains unclear due to the lack of valid quantization method. Here, we proposed the concept of negative center of electrostatic potential (NCESP) and Mayer bond order (MBO) to describe solvent capability, which highly relate to solvation structure and oxidation potential, respectively. Based on established principles, the selected electrolyte with 1.7 M LiFSI in methoxytrimethylsilane (MOTMS)/ (trifluoromethyl)trimethylsilane (TFMTMS) shows unique hyperconjugation nature to stabilize both Li anode and high-voltage cathode. The 4.6 V 30 μm Li||4.5 mAh cm-2 lithium cobalt oxide (LCO) (low N/P ratio of 1.3) cell with our electrolyte shows stable cycling with 91% capacity retention over 200 cycles. The bottom-up design concept of electrolyte opens up a general strategy for advancing high-voltage LMBs.

Crafting a sustainable non‐aqueous electrolyte is paramount in the pursuit of high‐voltage lithium batteries that exhibit exceptional performance. Traditional carbonate‐based electrolytes encounter hurdles in maintaining electrochemical stability due to unstable interphases, as well as continuous degradation of the electrolyte itself. Herein, based on heterogeneous doping, a colloidal electrolyte with multiple functions via simple integrating methyl‐encapsulated fumed silica (MFS) into a conventional carbonate‐based electrolyte effectively addresses the aforementioned challenges. The produced colloidal electrolyte endowed with unexpected self‐purification capabilities effectively eliminates HF and H2O, consequently enhancing stability of the electrolyte, interphase, and electrode. Furthermore, MFS induces a weakly solvated Li+ structure that is heterogeneously doped into the original solvation matrix and contributes to the formation of tailored and stable electrode/electrolyte interphases for both anode and cathode. Using such electrolyte, Li||LiCoO2 batteries demonstrate capacity retentions of 83.6% and 95.4% within 3000 and 1000 cycles at charging voltages of 4.4 and 4.5 V, respectively. Remarkably, with addition of 2000 ppm H2O in this electrolyte, cells can be cycled stably over 400 cycles with a capacity retention of 88.6%. This simple and effective electrolyte engineering strategy has the sustainability to significantly advance the development of highly stable high‐voltage lithium batteries.

Nickel-rich layered cathodes and lithium metal anode are promising for the next generation high-energy-density batteries. However, the unstable electrode-electrolyte interface induces structural degradation and battery failure under high-voltage and high-loading conditions. Herein, we report a fluorosilane-coupled electrolyte stabilizer with 1H, 1H, 2H, 2H-perfluorooctyltrimethoxysilane (PFOTMS), which presents higher adsorption energy with LiNi0.8Co0.1Mn0.1O2 cathode than solvents through the conjugation of Si─O bonds and therefore is oxidized on its surface to derive an interfacial layer rich in F and Si─O species. This architecture effectively stabilizes the cathode structure, suppresses transition metal migration, and promotes Li+ conduction and uniform deposition, which also suppresses the side reactions of electrolyte with both cathode and anode. This unique interfacial stabilization mechanism enables the Li||NCM811 battery to achieve a capacity retention rate of 80.8% after 600 cycles at 4.7 V. The Li||LiCoO2 cell with a high mass loading of 20 mg cm-2 achieves a remarkably high-capacity retention of 92.79% after 500 cycles at 4.4 V. This work proposes an interfacial stabilization that overcomes high-voltage limitations in practical nickel-rich cathode/lithium metal batteries.

In recent years, the researches on lithium metal batteries have attracted a new upsurge due to the increasing demand for storage devices with high energy density. For the modification of lithium metal battery, how to inhibit effectively the growth of lithium dendrites has become a key challenge. Due to its good compatibility with lithium metal, the ether electrolytes have been used, but it is still difficult to be applied in a high voltage battery system because of its low oxidation stability. In this work, we have dissolved the lithium carboxylate, LiCO2CF3, into a DME-based ether solvent to achieve relatively outstanding performance in both positive and negative electrodes, even if in the dilute electrolyte of 1 mol L-1 concentration. Using above electrolyte, the coulombic efficiency of Li-Cu half-cells still remains 98.5% under the condition of (1 mA cm -2, 1 mAh cm-2) after 100-times cycling, and the Li//NCM523 full batteries normally charged/discharged in the voltage range of 3.0  4.3 V also remain nearly 80% capacity retention rate after 100 cycles. Moreover, when the concentration is increased to 5 mol L-1, the coulombic efficiency of the half-cells has stabilized at around 99.0% after 250 cycles under the condition of 1 mA cm-2 current density along with the average coulombic efficiency as high as 98.4%, and the capacity retention rate of the full-batteries is nearly 95.4% after 100 cycles and over 83.8% after 200 cycles.

The homogenous interface coordination chemistry at both lithium anode and high‐voltage cathode interfaces significantly limits the interfacial optimization efficiency and synergetic stabilization in high‐voltage solid‐state lithium metal batteries (SSLMBs) with poly(ethylene oxide) (PEO)‐based electrolytes. Herein, a heterogenous interface coordination chemistry between Li|PEO and PEO|LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) is tailored by asymmetric electrolyte design and interfacial coordination regulators to promote interfacial synergetic stabilization. At Li interface, the Lewis acid Bi site in tris(4‐trifluoromethylphenyl) bismuth dichloride (TBiCl) mitigates strong Li + −EO coordination and catalyzes bis(trifluoromethanesulfonyl)imide (TFSI − ) decomposition via intense TBi 2+ −LiTFSI interaction. This process boosts an in situ generation of dynamic stable mixed conducting interphase rich in LiF and Bi/Li 3 Bi and a favorable lithium plating/stripping cycle over 3000 h. Differently, at NCM811 interface, the strong PEO−lithium difluoro(oxalato)borate (LiDFOB) coordination and preferential passivation effect of LiDFOB facilitate the formation of LiF and B−O‐rich cathode electrolyte interphase, which suppresses continuous electrolyte oxidation and ensures rapid interfacial kinetics. Consequently, the 4.5 V Li/NCM811 cells with asymmetric electrolyte can achieve a high initial capacity of 214.1 mAh g −1 and steadily cycle over 100 cycles. Moreover, the 50 µm Li/NCM811 pouch cell delivers a capacity of 33.5 mAh and demonstrates stable operation under abuse conditions, highlighting the practicality of this asymmetric electrolyte.

Lithium metal batteries (LMBs) paired with high – voltage cathodes like Li and Mn-rich (LMR) offer high energy density exceeding 400 Wh/kg. However, their commercial adoption is hindered by electrolyte decomposition, cathode electrolyte interface (CEI) instability, dendrite formation, and capacity fade due to structural degradation at high voltages (> 4.6 V). In this study, we present a novel dual – salt localized high-concentration electrolyte (D-LHCE) formulation. This D-LHCE integrates LiPF 6 and LiTFSI in a fluoroethylene carbonate (FEC), Dimethyl carbonate (DMC), with 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) as a diluent. The dual-salt strategy aims to optimize solvation by enhancing the formation of contact ion pairs (CIP) and aggregates (AGG). This innovative electrolyte formulation is tailored to enhance the stability of both the cathode-electrolyte interphase (CEI) and the solid-electrolyte interphase (SEI) on the lithium metal anode, mitigating oxidative decomposition and parasitic reactions that degrade battery performance. The D-LHCE demonstrated a solvation structure with dual salts AGGs and CIPs, analyzed using Raman and 7 Li NMR. For example, Raman spectroscopy showed a shift in peaks at 745 cm -1 for coordinated PF₆ - and 741 cm -1 for TFSI - indicating a solvation structure dominated by CIP and AGG resulted from reduced free solvent molecules. 7 Li NMR exhibited upfield shifts such as -1.258 ppm and -1.322 ppm indicating enhanced Li-ion interaction with both PF 6 - and TFSI - anions, a synergic effect resulted in D-LHCE. Electrochemical property of D-LHCE was compared with a series of electrolytes including a baseline (1 M LiPF 6 in EC/EMC), FEC-baseline (1 M LiPF 6 in FEC/DMC), and single-salt LHCEs (3 M LiPF 6 or 3 M LiTFSI in FEC/DMC with TTE), and D-LHCE (2 M LiPF 6 + 1 M LiTFSI in FEC/DMC with TTE). Attributed to its increased interionic interaction and a reduction in the HOMO energy, the D-LHCE presented its superior anodic stability up to 4.75 V vs.Li , compared with the baseline (4.3 V vs.Li ) and the single-salt LHCE (4.6 V vs.Li ) electrolytes. As a result, D-LHCE electrolyte significantly extended the cycle life of LMR/Li cells, achieving 90.2% capacity retention after 100 cycles at 25 o C, compared to 21.9% with the baseline. The influence of D-LHCE on the properties of SEI and CEI layers in LMR/Li cells were investigated after 100 cycles at 25 o C. X-ray photoelectron spectroscopy (XPS) shows that Li SEI layer in D-LHCE has LiF rich composition (74.8%) compared with the baseline electrolyte (56.1% LiF), with no detectable Mn signals, indicating robust protection against transition metal dissolution. In addition, scanning electron microscopy (SEM) reveals that D-LHCE produces a compact and uniform SEI layer on Li, whereas the baseline electrolyte produces thicker and porous SEI with significant cracks. The CEI on aged LMR cathodes also benefits significantly from D-LHCE. XPS analysis revealed a thin, LiF-rich CEI layer (60.9%) on LMR compared to the baseline electrolyte (31.7% LiF). SEM images show minimal surface deposits on LMR after 100 cycles in D-LHCE, unlike the thick layers in baseline and FEC-baseline samples. Electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT) analyses indicate a low interfacial impedance (R int = 40.4 Ω in D-LHCE vs. 168.4 Ω in baseline), reflecting suppressed CEI growth. These results, demonstrating enhanced CEI stability, will be discussed in detail in the presentation.

High-voltage and fast-charging lithium metal batteries (LMBs) are crucial for overcoming electric vehicle range and charging limitations. However, conventional carbonate electrolytes face intrinsic limitations in simultaneously achieving compatibility with high-voltage and lithium metal anode. These limitations arise from sluggish Li+ transport kinetics and parasitic side reactions, both largely driven by excessive Li+ solvation energy inherent to carbonates. To address these challenges, we propose a conformational engineering strategy of fluorinated solvent molecules by developing a 2,2,3,3,4,4-hexafluoropentanedioic·anhydride (HFPA)-derived electrolyte (HFPE). The chair conformation of HFPA synergizes with its high F/C ratio to establish a low-polarity solvation environment, effectively reducing desolvation energy barriers. In addition, the HFPA-induced ligand preference for anion aggregation contributes to the formation of anion-rich dissolved sheaths while stabilizing the electrode-electrolyte interphases. The engineered HFPE demonstrates accelerated interfacial ion transport kinetics with an enhanced Li+ transference number of 0.64. When paired with LiNi0.8Co0.1Mn0.1O2 cathodes under stringent operating conditions (4.5 V cut-off voltage, 10 C-rate), HFPE-enabled cells exhibit exceptional cycling stability. Notably, industrial-scale 5.6 Ah lithium metal pouch cells employing HFPE maintain stable operation at 4.5 V, underscoring the practical viability of this conformation modulation approach. This work establishes a paradigm-shifting strategy for next-generation electrolyte design in practical high-energy-density LMBs.

Enhancing the tolerance of Li‐ion batteries (LIBs) to high charging voltage and extreme climates is pivotal for further widespread application. Nevertheless, practical capacity utilization is severely constrained by interfacial parasitic reactions, electrolyte consumption, and sluggish kinetics. Modulating the electrode/electrolyte interphase (EEIs) with functional additives is a favorable approach. Herein, a novel multifunctional electrolyte additive, diethyl [4‐(Trifluoromethyl) benzyl] phosphonate (DBP) containing fluorine, phosphate, and phenyl groups is proposed to simultaneously modify both cathode and anode of LIBs. The preferential decomposition of DBP facilitates the formation of a mechanically robust and ionically conductive EEIs. The DBP‐derived cathode‐electrolyte interphase (CEI) is capable of suppressing transition metal‐ion dissolution and cation disorder. Moreover, DBP exhibits multifunctional benefits, including accelerating Li+ transport, scavenging free radicals, and curbing the hydrolysis of LiPF6. Therefore, with optimized DBP additive, Li||NCM622 cell achieves advanced performance under harsh conditions, e.g. high temperature (60 °C), low temperature (−10 °C), and high cut‐off voltage (4.6 and 4.8 V). Furthermore, the Li||Li symmetric cell cycles for over 450 h at 0.5 mA cm−2/0.5 mAh cm−2 stably, which demonstrates the potential to be applied into practical LIBs.

Concentrated electrolytes based on lithium bis(fluorosulfonyl)imide (LiFSI) have been proposed as an effective Li-compatible electrolyte for anode-free lithium metal batteries (AFLMBs). However, these electrolytes suffer from severe aluminum corrosion at an elevated potential. To address this issue, we propose a binary ionic liquid (IL) electrolyte additive comprising the 1-methyl-1-butyl pyrrolidinium cation (Pyr14+), difluoro(oxalate)borate anion (DFOB-), and difluorophosphate (PO2F2-) anion to mitigate the Li inventory loss and Al corrosion in 4 M LiFSI/DME electrolyte simultaneously. On the anode side, the IL additive facilitates the formation of a robust Li3N- and LiF-rich solid electrolyte interphase, promoting highly reversible Li plating/stripping and uniform Li deposition. Additionally, the ILs alter the Li+ solvation structure, leading to enhanced tLi+ and rapid Li+ desolvation kinetics. Concurrently, on the cathode side, the ILs aid in the generation of dense LiF- and AlF-rich passivation films against Al corrosion. By using the IL-added electrolyte, the Cu||LiMn0.7Fe0.3PO4 cell operates stably at 4.5 V, and the Cu||NCM613 cell with a high loading of 4.0 mA h cm-2 sustains 142 cycles until 80% capacity retention. This research contributes to a deeper understanding of the IL additive mechanism at the electrode-electrolyte interfaces and offers a straightforward approach to designing practical high-voltage AFLMB electrolytes.

The pursuit of high-energy-density batteries (> 400 Wh kg -1 ) has intensified interest in lithium (Li)–metal batteries (LMBs) as a next-generation energy storage solution. Due to its remarkable specific capacity (3860 mAh g -1 ) and lowest electrochemical potential, Li metal presents a substantial energy advantage over conventional graphite anodes in lithium-ion batteries (LIBs). [1] Pairing Li metal with high-capacity transition metal oxides, such as high-nickel LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), holds significant promise. However, challenges such as interfacial instability and, more critically, inter-electrode species crossover must be addressed. While the migration of soluble species from the cathode and its effects on the anode are well-documented in LIBs, their influence on LMBs remains poorly understood. [2] Contradictory findings in previous studies likely stem from differences in cell configurations and operating conditions. [3,4] Additionally, despite its potential impact on long-term performance, the crossover of gaseous species has received little attention in LMBs. Many studies also rely on excess electrolytes, which do not accurately represent the lean-electrolyte, high-areal-capacity designs required for practical LMB applications. A thorough investigation of crossover mechanisms under realistic conditions is therefore essential for the advancement of LMB technology. This work systematically explores the influence of transition metal (TM) and gas crossover in high-capacity Li|NCM811 pouch cells using a lean electrolyte. To isolate the effects of crossover, cells were constructed with and without a ceramic separator, which serves as a physical barrier to species migration between electrodes. Cycling was conducted at an areal capacity exceeding 5 mAh cm -2 with two different charging cut-off voltages, 4.2 V and 4.5 V, using an electrolyte composed of 4 M lithium bis(fluorosulfonyl)imide (LiFSI) in 1,2-dimethoxyethane (DME). At 4.2 V, degradation of the Li metal anode was identified as the primary cause of capacity fade. Notably, the incorporation of a ceramic separator significantly enhanced cell lifespan by minimizing crossover effects. Chemical analysis of the Li electrode and gas evolution measurements confirmed the migration of transition metals and gaseous species from NCM811, which was largely mitigated by the ceramic separator. Furthermore, X-ray computed tomography (XCT) imaging revealed that unprotected Li electrodes exhibited increased porosity and more severe degradation than their protected counterparts. These results suggest that crossover-induced degradation of Li is the major contributor to capacity loss in LMBs at 4.2 V cut-off. At a higher cut-off voltage of 4.5 V, both the Li anode and NCM811 cathode suffered from increased instability. The extent of TM and gas crossover was significantly higher at this voltage, exacerbating degradation at both electrodes. Nevertheless, the use of a ceramic separator still contributed to improved cycling stability by reducing species migration. In addition to cathode-to-anode crossover, anode-to-cathode species transport was also considered, as soluble and gaseous products generated at the Li anode could affect the stability of NCM811. The results indicated that crossover effects significantly exacerbate the instability of both electrodes and play a crucial role in determining the cycle life of the cells. This presentation will provide a comprehensive evaluation of interelectrode crossover effects on LMB performance through electrochemical cycling, impedance spectroscopy, electron microscopy, gas analysis, chemical characterization, and XCT imaging. References: [1] Nat. Nanotechnol . 2017 , 12 , 194–206 [2] J. Phys. Chem. C 2014 , 118 , 24335−24348 [3] Adv. Energy Mater . 2019 , 9 , 1900574 [4] Adv. Funct. Mater . 2021 , 31 , 2010267

Poly(1,3-dioxolane) (PDOL)-based electrolyte has gained wide attention due to its high compatibility with the lithium metal anode, intimate contact with electrodes, and high ionic conductivity. However, its application in high-voltage batteries is limited because the residual DOL monomers are prone to oxidation at high voltage. Here, we report that LiDFOB-initiated in situ polymerization stabilizes these residual monomers, thus overcoming the oxidation-related limitations of PDOL-based electrolytes. This approach promotes the formation of a thermodynamically stable Li+-DOL-DFOB- solvation structure and DOL-PDOL clusters, reducing the oxidative decomposition of the residual DOL monomers and extending the electrochemical stability window up to 5.0 V vs Li+/Li. It also enhances ionic conductivity (4.39 mS cm-1), and facilitates the formation of a uniform, F-rich cathode-electrolyte interphase. Electrochemical tests and computational simulations reveal that the reduced Li+-PDOL interactions in the designed PDOL promote higher ionic mobility and electrochemical stability. Consequently, Li||LiCoO2 cells using the designed PDOL exhibit remarkable cycling performance, maintaining 80% capacity retention over 760 cycles at a cut-off voltage of 4.35 V. These findings establish PDOL as a transformative electrolyte for high-voltage lithium metal batteries.

Local high concentration electrolytes (LHCEs) have been proved to be one of the most promising systems to stabilize both high voltage cathodes and Li metal anode for next-generation batteries. However, the solvation structures and interactions among different species in LHCEs are still convoluted, which bottlenecks the further breakthrough on electrolyte development. Here, it is demonstrated that the hydrogen bonding interaction between diluent and solvent is crucial for the construction of LHCEs and corresponding interphase chemistries. The 2,2,2-trifluoroethyl trifluoromethane sulfonate (TFSF) is selected as diluent with the solvent dimethoxy-ethane (DME) to prepare a non-flammable LHCE for high voltage LMBs. This is first find that the hydrogen bonding interaction between TFSF and DME solvent tailors the electrolyte solvation structures by weakening the coordination of DME molecules to Li+ cations and allows more participation of anions in the first solvation shell, leading to the formation of aggregates (AGGs) clusters which are conducive to generating inorganic solid/cathodic electrolyte interphases (SEI/CEIs). The proposed TFSF based LHCE enables the Li||NCM811 (LiNi0.8 Mn0.1 O2 ) batteries to realize >80% capacity retention with a high average Coulombic efficiency of 99.8% for 230 cycles under aggressive conditions (NCM811 cathode: 3.4 mAh cm-2 , cut-off voltage: 4.4 V, and 20 µm Li foil).

The chemical properties of the Solid Electrolyte Interphase (SEI) layer and Cathode Electrolyte Interphase (CEI) are crucial for achieving high-energy-density lithium metal batteries, especially under extreme operating conditions. Herein, we propose a delicately designed tandem separator (CYANO-COF|PP|SnF2) to regulate the chemical stability of dual interfaces. The cyano group in CYANO-COF induces a stable CN-enriched CEI on the surface of high-nickel LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode through the adsorption/coordination effect with transition metals (TMs), inhibiting irreversible phase transitions, TMs dissolution, and other side reactions. Meanwhile, a straightforward in-situ conversion is used to construct an artificial hybrid SEI layer comprising LiF and Li-Sn alloy. As demonstrated theoretically and experimentally, the hybrid SEI with enhanced electron-blocking ability and rapid transmission characteristics can decrease the electron from the Li anode into the SEI and allow Li+ to rapidly diffuse through the SEI layer, achieving even dendrite-free lithium plating at the SEI/Li interface. With the synergistic effect of dual interfaces, the NCM811||Li battery maintains a capacity retention of 81.8% within 200 cycles at 4.5 V and 55 °C. This work emphasizes the significance of regulating the chemical properties of double interfaces and provides new insights into the rational design for tandem separators.

Increasing the upper cut‐off voltage of the LiNixCoyMn1‐x‐yO2 (NCM)‐based lithium‐metal batteries (LMBs) is highly pursued for achieving high battery energy density. However, the cycling stability of high‐voltage LMBs, which is associated with ethylene carbonate electrolytes, remains greatly challenging. Herein, an interphase‐designable additive‐enabled ethylene carbonate‐free electrolyte strategy is proposed for achieving 4.6 V Li||NCM811 battery with long cycling life from 55 to −30 °C. The solvent characteristics of ethyl methyl carbonate endow LMBs with potential merits in high voltage, wide temperature, and cycling stability, which are further strengthened by the additive, 1,5‐difluoro‐2,4‐dinitrobenzene (FNB), for optimizing electrode electrolyte interphases. The sturdy LiF‐rich and LiNxOy‐contained electrode/electrolyte interphase on cathode/anode surfaces can protect two electrodes well from electrolyte corrosion and also reduce excessive electrolyte decomposition. As expected, the Li||NCM811 batteries can maintain 70% capacity retention after 500 cycles with superior high‐temperature and low‐temperature performance (from 55 to −30 °C). The 6.8Ah pouch cells with this electrolyte can achieve a high energy density of up to 505 Wh kg−1.

High‐voltage lithium‐metal batteries (LMBs) are promising for energy storage applications but suffer from poor electrochemical window of solid polymer electrolytes (SPEs), which are difficult to achieve via a single polymeric functionality. Herein, a hybrid Si/F‐based polymeric 3D network is reported bearing polysiloxane backbone with fluorinated pendants to tune the highest occupied molecular orbital (HOMO)/the lowest unoccupied molecular orbital LUMO energies, thermodynamically expanding intrinsic electrochemical window of solid polymer electrolyte (SPE). Meanwhile, the hybrid Si/F functionalities with high fluorine abundance is identified to furnish dual interfacial kinetic stability at both anode and cathode interfaces with stabilized solid electrolyte interface (SEI) and cathode electrolyte interface (CEI), respectively. As a result, stable cycling in solid‐state high‐voltage LMBs is achieved up to an ultrahigh operating voltage of 4.9 V. Furthermore, it shows that in situ blending the Si/F SPE with eutectic electrolytes (EE) to form a non‐flammable gel polymer electrolyte can mitigate parasitic reactions of EE against metallic Li anode and achieve highly reversible charge–discharge cycling from 4.2 to 4.8 V at 25 °C.

Composite solid polymer electrolytes (CSPEs) are safer alternatives to liquid electrolytes and excellent candidates for high-voltage solid-state batteries. However, interfacial instabilities between the electrodes and CSPEs are one of the bottlenecks in pursuing these systems. In this study, a cross-linked CSPE was synthesized based on polypropylene carbonate, polyethylene glycol methyl ether acrylate, polyethylene glycol diacrylate with additives including lithium bis(trifluoromethane)sulfonimide salt, and tantalum-doped lithium lanthanum zirconium oxide (LLZTO). Mass fractions of 10, 20, and 40% LLZTO were added to the CSPE matrix. In a symmetric cell, lithium plating and stripping revealed that the interface between the lithium metal anode and CSPE with 10% of the LLZTO (CSPE-10LLZTO) shows the most stable interface. The CSPE-10LLZTO sample demonstrated high flexibility and showed no degradation over 800 h of cycling at varying current densities. The ionic conductivity for the CSPE-10LLZTO sample at 40 °C was 6.4 × 10–4 S/cm. An all-solid-state full cell was fabricated with LiNi0.5Mn0.3Co0.2O2 as the cathode, CSPE-10LLZTO as the electrolyte and separator, and Li metal as the anode, delivering approximately 140 mAh/g of capacity. Differential scanning calorimetry measurements on CSPE-xLLZTO showed high miscibility and the elimination of crystallinity. Raman spectroscopy revealed uniformity in the structure. These findings demonstrate the capability of the CSPEs to develop high-voltage solid-state lithium metal batteries.

The implementation of Li metal anode with high-voltage Ni/Co rich cathode is plagued by low coulombic efficiency and inferior cycling stability. Here authors propose an anion-enriched interface to facilitate the columnar-structure of Li deposits to solve this issue. Aggressive chemistry involving Li metal anode (LMA) and high-voltage LiNi_0.8Mn_0.1Co_0.1O_2 (NCM811) cathode is deemed as a pragmatic approach to pursue the desperate 400 Wh kg^−1. Yet, their implementation is plagued by low Coulombic efficiency and inferior cycling stability. Herein, we propose an optimally fluorinated linear carboxylic ester (ethyl 3,3,3-trifluoropropanoate, FEP) paired with weakly solvating fluoroethylene carbonate and dissociated lithium salts (LiBF_4 and LiDFOB) to prepare a weakly solvating and dissociated electrolyte. An anion-enrichment interface prompts more anions’ decomposition in the inner Helmholtz plane and higher reduction potential of anions. Consequently, the anion-derived interface chemistry contributes to the compact and columnar-structure Li deposits with a high CE of 98.7% and stable cycling of 4.6 V NCM811 and LiCoO_2 cathode. Accordingly, industrial anode-free pouch cells under harsh testing conditions deliver a high energy of 442.5 Wh kg^−1 with 80% capacity retention after 100 cycles.

While crossover effects, such as transition‐metal dissolution, are well‐understood in lithium‐ion batteries, there is a limited understanding of the effect of crossed‐over chemical species in cells with oxide cathodes and lithium‐metal anodes. In this work, the effects of cathode‐to‐anode and anode‐to‐cathode crossover are explored in cells with a high‐nickel cathode, lithium‐metal anode, and a localized high‐concentration electrolyte (LHCE). Dramatic differences are found among cells; a lithium‐metal anode paired with a high‐nickel cathode has three times less solid‐electrolyte interphase growth than a lithium‐metal anode paired with lithium metal. Meanwhile, the cathode paired with lithium metal has 2–3 times higher capacity fade than the same cathode paired with graphite. Decomposition and crossover of the FSI salt is identified as the main source of these changes. The fluorine in the salt is first stripped off at the lithium‐metal anode, and the remaining sulfur and nitrogen cross over to the cathode. Although the reduction in fluorine content harms the surface stability of the cathode, the lithium‐metal anode benefits from the increased fluorine content. Because the lithium‐metal anode is typically the bottleneck for cells with thin lithium, crossover is a major factor in the enhanced performance of lithium‐metal batteries with LHCE.

No abstract available

High energy density lithium metal batteries (LMBs) have garnered significant research interests in the past decades. However, the growth of lithium dendrites and the low Coulombic efficiency (CE) of Li metal anode pose significant challenges for the development of LMBs. Herein, we report a triethyl orthoformate (TEOF)-based localized high-concentration electrolyte (LHCE) that facilitates a highly reversible Li metal anode with dendrite-free deposition morphologies and an average Coulombic efficiency of 99.1% for 450 cycles. Mechanistic study reveal that the steric hindrance caused by the terminal ethyl groups in the TEOF solvent molecule results in a weak solvating ability, leading to the formation of anion-dominant solvation structures. The anion-dominant solvation sheaths play an essential role in the formation of a LiF-rich solid-electrolyte interphase (SEI), which effectively suppresses the growth of Li dendrites. Furthermore, the TEOF-based electrolyte demonstrates the stable cycling of high-voltage Li||NMC811 cells. These results provide insights into understanding of steric hindrance effect on electrolyte solvation structure and offer valuable guidance for the design of electrolyte solvents in the development of lithium metal batteries.

No abstract available

The high reactivity of Li metal anode and dendrite issues in lithium metal batteries (LMBs) pose serious challenges to the electrolytes. Herein, a novel Propylene Carbonate (PC) based localized high...

This work explores the effect of in situ electrochemical pretreatment of copper current collectors (CuCC), acting as anodes in anode‐free lithium‐metal battery (AFLMB) with sulfolane‐based localized high‐concentration electrolyte. Two electrochemical pretreatment methods, not involving lithium overpotential deposition are in focus. These strategies are investigated in terms of passive layer growth, surface morphology evolution, composition of the formed interphases, and electrochemical performance for AFLMBs. The passive layers formed on CuCC (Cu–solid‐electrolyte interphase [SEI]) are in situ characterized by means of electrochemical quartz crystal microbalance with damping monitoring, which indicates that the Cu–SEIs exhibit detectable viscoelastic properties. The morphological characterization of the modified CuCCs shows highly homogeneous Cu–SEI structure with low surface roughness. The composition and physical properties of the Cu–SEI layers are correlated with the electrochemical performance of the anodes. The observed positive effect of the procedures for SEI preformation is associated with the synergistic influence of balanced inorganic–organic composition, enhanced viscoelastic properties, and homogeneous morphology of the layer. The study demonstrates the positive impact of the designed pretreatments and provides an appropriate comparison between the proposed in situ approach and the state of the art.

No abstract available

Due to its low electrochemical potential and high theoretical specific energy, lithium-metal batteries (LMBs) have been considered as a promising advanced energy storage system for portable applications such as electric vehicles (EVs). However, the uncontrolled growth of lithium dendrites during cycling has remained a challenge. By utilizing an inert solvent to "dilute" the high concentration electrolytes, the concept of localized high-concentration electrolytes (LHCEs) has recently been demostrated as an effective solution to enable the dendrite-free cycling of LMBs. In this work, we investigated the reactions of 2 M lithium bis(fluorosulfonyl)imide (LiFSI) in a mixture of dimethoxyethane (DME)/tris(2,2,2-trifluoroethyl) orthoformate (TFEO) electrolyte at a Li metal anode. The SEI formation mechanism is investigated using a hybrid ab initio and reactive force field (HAIR) method. The 1n reactive HAIR trajectory reveals the important initial reduction reactions of LiFSI, TFEO, and DME. Particularly, both FSI anions and TFEO decompose quickly to release a considerable amount of F-, which leads to a LiF-rich SEI inorganic inner layer (IIL). Furthermore, TFEO produces a significant amount of unsaturated carbon products, such as thiophene, which can potentially increase the conductivity of SEI to increase the battery performance. Meanwhile, XPS analysis is utilized to further investigate the evolution of the atomic environment in SEI. Future designs of better electrolytes can be greatly aided by these results.

To achieve stable Li anode cycling with a high-voltage cathode and high efficiency, a novel ester diluent-based localized high-concentration electrolyte (LHCE) was successfully applied. The oxidation resistance of the high-concentration electrolyte is retained after dilution. More than 99.5% Coulombic efficiency is achieved in Li||Cu cells owing to the optimized physical properties, and the robust SEI film enables superior long-term operation with a high-voltage cathode. This strategy verifies the effectiveness of developing ester diluents for LHCEs applied in lithium metal batteries.

Conventional electrolytes in lithium metal batteries (LMBs) suffer from irreversible interfacial degradation at elevated temperatures and sluggish Li⁺ desolvation/transport kinetics under cryogenic conditions. Herein, we present an innovative semi-solvated hexafluoroisopropyl methyl ether (HFME) diluent in localized high-concentration electrolytes (LHCEs) that strategically addresses these limitations. Li⁺ hopping networks within the electrolyte can be preserved even at low temperature due to the coordination of lithiophilic groups in HFME molecules with Li⁺. Simultaneously, lithiophobic group induced spatial confinement effects promote the formation of anion-cation aggregates (AGGs), significantly optimizing Li⁺ desolvation kinetics and boosting the formation of inorganic-dominated solid electrolyte interphase (SEI) with exceptional thermal stability. Li||LiFePO4 (LFP) cell with the diluent-coordinated LHCEs (DCL) can deliver 125.4 mA h g-1 initial capacity at -20°C with 92.2% retention after 150 cycles. Under elevated temperatures (65°C), the DCL based Li||LFP cell can maintain the capacity retention of 91.3% over 60 cycles. The Li||NCM811 pouch cell (10 cm × 6.5 cm, capacity: 1000 mA h) based on the DCL exhibits outstanding cycling stability, retaining 91.6% of its initial capacity after 75 cycles. This work pioneers a solvent chemistry paradigm through spatially modulated solvation structures, establishing fundamental design principles for electrolyte for wide-temperature-range LMBs.

Carbonate‐based electrolytes generally suffer from low Coulombic efficiency and poor cycling stability in lithium metal batteries. In this work, localized high concentration electrolytes (LHCEs) based on dimethyl carbonate (DMC) with varying diluent additions are designed. LHCEs demonstrate higher Li+ transference numbers and a greater proportion of contact ion pairs (CIPs) and ion pair aggregates (AGGs) in the solvation structures, facilitating the formation of anion‐derived solid electrolyte interphase (SEI). Furthermore, LHCEs enhance the Coulombic efficiency of Li||Cu cells and improve the anodic stability against lithium. One of these LHCEs, prepared with appropriate diluent addition, exhibits excellent capacity retention in Li||NCM622 cells at 0.5 C after 150 cycles, thus presenting promising possibilities for the development of high energy density lithium metal batteries.

Ionogels, which are being considered as quasi-solid electrolytes for energy-storage devices, exhibited technical superiority in terms of nonflammability, negligible vapor pressure, remarkable thermostability, high ionic conductivity, and broad electrochemical stability window. However, their applications in lithium metal batteries (LMBs) have been hindered by several issues: poor compatibility with Li-metal anodes and high-voltage cathodes, high viscosity, and inadequate wettability. Little attention has been paid to ionogel-based low-concentration electrolytes, despite their potential advantages in terms of Li+ mobility, viscosity, electrode wettability, and cost. Here, we demonstrate the surprising capabilities of localized high-concentration ionogel (LHCI) and dilutedly localized high-concentration ionogel (DLHCI) electrolytes, utilizing the non-solvating fluorinated ether 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, to realize high-voltage quasi-solid-state lithium metal batteries (QSLMBs). Notably, the DLHCI electrolyte not only delivers superior ionic conductivity of 3.93 × 10−3 S cm−1 but also provides a high Li plating/stripping Coulombic efficiency exceeding 99%. Moreover, it significantly enhances anodic stability when paired with 4.4 V LiNi0.8Co0.1Mn0.1O2 (NCM811) and 4.8 V LiNi0.5Mn1.5O4 (LNMO). Consequently, substantial improvement in cycling performance of QSLMBs has been realized with the DLHCI electrolyte.

No abstract available

ABSTRACT In-situ fabricated gel polymer electrolytes (GPEs), characterized with superior interfacial properties and large-scale processibility, represent a promising electrolyte system for high-performance lithium metal batteries (LMBs). Herein, we propose an in-situ fabricated high-voltage GPE featuring a localized high-concentration solvation structure (LHCE-GPE). This tailored special solvation structure within a polymer matrix promotes the formation of an electrochemically robust electrode–electrolyte interphase. Furthermore, employing LHCE-GPE, Li||Li1.2Ni0.13Co0.13Mn0.54O2 cells operating at 4.8 V demonstrate a high specific capacity of 248 mAh g−1, and 4.5 V Li||LiNi0.8Co0.1Mn0.1O2 cells achieve a remarkable cycling stability over 1000 cycles. Significantly, our LHCE-GPE allows for the operation of practical solid-state 18650 cylindrical LMBs at 4.7 V and industrial Li-ion batteries at 4.6 V, achieving high energy densities of 250 and 283 Wh kg−1, respectively (excluding packaging), while also demonstrating robust safety during rigorous nail-penetration tests. Our LHCE-GPE design presents a practical and powerful strategy for realizing solid-state LMBs with high energy density and high safety.

The stability of the solid–electrolyte interphase (SEI) is critical to the cycle life of lithium‐metal batteries (LMBs). While the crossover effect of transition‐metal ions from cathode to anode is extensively studied in lithium‐ion batteries with graphite anodes, its impact on LMBs remains largely unexplored. Herein, this study investigates the electrochemical and chemical properties of SEI layers formed on lithium‐metal anodes in localized high‐concentration electrolytes (LHCEs) containing dissolved transition‐metal ions (Ni2+, Mn2+, and Co2+). It is demonstrated that transition‐metal ions in LHCEs reduce the coulombic efficiency (CE) and significantly degrade the cycle life of LMBs. Time‐of‐flight secondary‐ion mass spectrometry (ToF‐SIMS) reveals that SEI structures differ depending on the dissolved TM ion, with Mn2+ and Co2+ inducing severe destabilization, and Ni2+ exhibiting a less severe impact. These findings underscore the detrimental effects of transition‐metal crossover effects in LMB systems.

The ultralow temperature performance of lithium metal batteries (LMBs) is fundamentally limited by sluggish ion transport and interfacial instability in conventional electrolytes. To address this challenge, this work proposes a novel localized high‐concentration electrolyte (LHCE) system, which synergistically regulates solvation structures and interfacial chemistry to achieve efficient ion transport and stable electrode/electrolyte interfaces at low temperature. By leveraging weakly solvating solvents 1,2‐diethoxyethane/methyl acetate, the solvation sheath structure is altered in the LHCE, allowing more anions to enter, significantly reducing Li+ de‐solvation activation energy and interfacial resistance. Experimental and simulation results reveal that weakly solvating molecule‐driven anion‐dominated solvation facilitates the formation of inorganic‐rich interphases (LiF/Li3N), effectively suppressing lithium dendrite growth and cathode interface degradation. Therefore, the Li||Cu cell with the designed electrolyte exhibits high lithium plating/stripping coulombic efficiency at −20 °C (>98.8%). Under harsh conditions (4.5 V cutoff, −40 °C), the Li||NCM622 cell maintains 73.4% of the discharge capacity at room temperature and retains 88% of the initial capacity after 400 cycles. This study establishes a novel molecular engineering strategy for electrolyte design, leveraging solvation regulation and targeted interfacial chemistry to unlock high‐performance LMBs.

High-voltage lithium metal batteries (LMBs) have faced application obstacles derived from the unstable interfacial layers on both the cathode and anode sides. Herein, a dual-salt localized high-concentration electrolyte (LHCE) is optimized to modify the anion-derived inorganic-rich interfacial layers with conductive inorganic and robust organic components.

Localized high-concentration electrolytes have attracted much attention to researchers because they have lower viscosity and economic cost and also maintain relatively great electrochemical performance than the high-concentration ones do. In our work, 1.5 M (mol L-1) locally concentrated ether-based electrolyte has been obtained by adding 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (HFE) into the 4M LiFSI concentrated DME-based electrolyte. The optimal ratio is determined by DFT calculation and experimental combination, and finally DH(3/5)-1.5M-LiFSI (DME : HFE = 3 : 5 by volume) is obtained. The electrolyte not only owns relatively good physical properties such as low viscosity and high conductivity, but also has decent electrochemical performance. The coulombic efficiency of Li||Cu half-cells can maintain no less than 99% after circulating for 250 cycles under the condition of 1 mA cm-2 current density and 1 mAh cm-2 lithium deposition amount for each cycle and the stable battery polarization voltage was about 50 mV. Furthermore, 0.15 M lithium trifluoromethyl acetate (LiCO2CF3) has been added as additive to enhance the oxidation stability. The new electrolyte, DH(3/5)-1.65M-LiFC makes Li||NCM523 batteries to maintain about 83% capacity after cycling 250 times with 0.5 C charge current density and 1C discharge current density of 1 C (1 C = 160 mAh g-1) charged to 4.3 V. What's more, the lithium salt additive has little negative effect on Li||Cu half- cell performance under the same condition as before, indicating this new type of localized high concentration DME-based electrolyte benefits both high-voltage cathode and lithium metal anode.

Localized high-concentration electrolytes (LHCEs) are promising systems for improving the high-voltage performance and interfacial stability of lithium-metal batteries (LMBs). Unfortunately, they are always challenged by liquid–liquid phase separation during solution preparation. Further investigation is always required when the prepared electrolyte has encountered liquid–liquid phase separation previously. Here, we propose a “cognate cosolvent” strategy to mediate phase-separated LiBF4/fluoroethylene carbonate (FEC)|ethyl trifluoroacetate (TFAE) mixtures with ethyl acetate (EA), forming effective LiBF4/FEC/EA/TFAE-based LHCEs (B-LHCEs). Because of their unique solvation structure, the B-LHCEs exhibit high oxidative stability, facilitating Li+ transport. The optimized B-LHCEs help single-crystal LiMn0.8Mn0.1Co0.1O2/Li batteries form robust interphases, improving interfacial stability. As a result, distinct performance can be obtained (4.5 V, 500 cycles, ~90%, 1400, ~70%; 25 C, 128 mAh g−1, 4.7 V, 500, 82.5%). This work turns the “impossible” into an “effective” high-voltage electrolyte design, transcending the previous paradigms of electrolyte investigation and enriching LHCE preparation research.

The development of high energy density lithium batteries and their use under extreme temperatures present significant challenges for commercial carbonate-based electrolytes. This study reports a local high-concentration electrolyte based on ethyl acetate (EA)/fluoroethylene carbonate (FEC), with lithium difluoro(oxalato)borate (LiDFOB) as the primary lithium salt. By adjusting the lithium salt concentration and adding lithium difluorophosphate (LiPO2F2) to regulate the solvation structure of lithium ions, the desolvation process of Li+ is accelerated, resulting in a well-formed electrode/electrolyte interface. The formulated electrolyte enables the Li/Lithium Cobalt Oxide (LCO) battery to stably cycle at a high cutoff voltage of 4.5 V. After 800 cycles at a rate of 1C, the capacity retention is 81.2 %. Even under high-rate cycling at 10C, the initial capacity can be maintained at around 85.0 %.Additionally, it exhibits good conductivity at low temperatures, with batteries using this electrolyte demonstrating excellent low-temperature performance even at -40 °C. At a rate of 0.1C, it provides an initial capacity of 173 mAh g-1, with a capacity retention of 94.2 % after 200 cycles. This work enables high-voltage, fast-charging, and low-temperature capabilities in lithium batteries through optimized electrolyte formulation and artificial construction of solid electrolyte interfaces, presenting innovative strategies for electrolyte design across multi-scenario applications.

Lithium metal batteries (LMBs), when coupled with a localized high-concentration electrolyte and a high-voltage nickel-rich cathode, offer a solution to the increasing demand for high energy density and long cycle life. However, the aggressive electrode chemistry poses safety risks to LMBs at higher temperatures and cutoff voltages. Here, we decipher the interphase instability in LHCE-based LMBs with a Ni0.8Co0.1Mn0.1O2 cathode at elevated temperatures. Our findings reveal that the generation of fluorine radicals in the electrolyte induces the solvent decomposition and consequent chain reactions, thereby reconstructing the cathode electrolyte interphase (CEI) and degrading battery cyclability. As further evidenced, introducing an acid scavenger of dimethoxydimethylsilane (DODSi) significantly boosts CEI stability with suppressed microcracking. A Ni0.8Co0.1Mn0.1O2||Li cell with this DODSi-functionalized LHCE achieves an unprecedented capacity retention of 93.0% after 100 cycles at 80 {\deg}C. This research provides insights into electrolyte engineering for practical LMBs with high safety under extreme temperatures.

The poor compatibility with Li metal and electrolyte oxidation stability preclude the utilization of commercial ester‐based electrolytes for high‐voltage lithium metal batteries. This work proposes a quasi‐localized high‐concentration electrolyte (q‐LHCE) by partially replacing solvents in conventional LiPF6 based carbonated electrolyte with fluorinated analogs (fluoroethylene carbonate (FEC), 2,2,2‐trifluoroethyl methyl carbonate (FEMC)) with weakly‐solvating ability. The q‐LHCE enables the formation of an anion‐rich solvation sheath, which functions like LHCE but differs in the partial participation of weakly‐solvating cosolvent in the solvation structure. With this optimized electrolyte, inorganic‐dominated solid electrolyte interphases are achieved on both the cathode and anode, leading to uniform Li deposition, suppressed electrolyte decomposition and cathode deterioration. Consequently, q‐LHCE supports stable cycling of Li | LiCoO2 (≈3.5 mAh cm−2) cells at 4.5 V under the whole climate range (from −20 to 45 °C) with limited Li consumption. A practical ampere‐hour level graphite | LiCoO2 pouch cell at 4.5 V and aggressive Li | LiNi0.5Mn1.5O4 cell at 5.0 V with excellent capacity retention further reveals the effectiveness of q‐LHCE. The refinement of old‐fashioned carbonate electrolytes provides new perspectives toward practical high‐voltage battery systems.

Electrolyte plays a crucial role in ensuring stable operation of lithium metal batteries (LMBs). Localized high-concentration electrolytes (LHCEs) have the potential to form a robust solid-electrolyte interphase (SEI) and mitigate Li dendrite growth, making them a highly promising electrolyte option. However, the principles governing the selection of diluents, a crucial component in LHCE, have not been clearly determined, hampering the advancement of such a type of electrolyte systems. Herein, the diluents from the perspective of molecular polarity are rationally designed and developed. A moderately fluorinated solvent, 1-(1,1,2,2-tetrafluoroethoxy)propane (TNE), is employed as a diluent to create a novel LHCE. The unique molecular structure of TNE enhances the intrinsic dipole moment, thereby altering solvent interactions and the coordination environment of Li-ions in LHCE. The achieved solvation structure not only enhances the bulk properties of LHCE, but also facilitates the formation of more stable anion-derived SEIs featured with a higher proportion of inorganic species. Consequently, the corresponding full cells of both Li||LiFePO4 and Li||LiNi0.8 Co0.1 Mn0.1 O2 cells utilizing Li thin-film anodes exhibit extended long-term stability with significantly improved average Coulombic efficiency. This work offers new insights into the functions of diluents in LHCEs and provides direction for further optimizing the LHCEs for LMBs.

The localized high-concentration electrolyte (LHCE) propels the advanced high-voltage battery system. Sulfone-based LHCE is a transformative direction compatible with high energy density and high safety. In this work, the application of lithium bis(trifluoromethanesulphonyl)imide and lithium bis(fluorosulfonyl)imide (LiFSI) in the LHCE system constructed from sulfolane and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) is investigated. The addition of diluent causes an increase of contact ion pairs and ionic aggregates in the solvation cluster and an acceptable quantity of free solvent molecules. A small amount of LiFSI as an additive can synergistically decompose with TTE on the cathode and participate in the construction of both electrode interfaces. The designed electrolyte helps the Ni-rich system to cycle firmly at a high voltage of 4.5 V. Even with high mass load and lean electrolyte, it can keep a reversible specific capacity of 91.5% after 50 cycles. The constructed sulfone-based electrolyte system exhibits excellent thermal stability far beyond the commercial electrolytes. Further exploration of in-situ gelation has led to a quick conversion of the designed liquid electrolyte to the gel state, accompanied by preserved stability, which provides a direction for the synergistic development of LHCE with gel electrolytes.

Although lithium metal batteries using localized high concentration electrolytes (LHCEs) exhibit promising life, their safety and survivability in hot summers are of great concern due to highly flammable and volatile solvents and diluents comprising LHCEs. In this work we present a nonflammable high-concentration phase-change electrolyte (HPCE) by addition of sulfolane (SF) and demonstrate it in single-layer Cu/NMC811 anode-free batteries (AFBs). The high dielectric constant of SF raises the LiFSI concentration of HPCE, enabling the AFB cells to possess stable solid electrolyte interphase (SEI) and operate at 60 ◦ C with exceptional cycling stability of 76 cycles at 80 % capacity retention. In addition, the solidified HPCE at room temperature due to the high melting point of SF allows the AFB cells to rest under open circuit with low degradation and high safety. Moreover, the high boiling point and high autoignition temperature of SF as well as the low amount of volatile components in the HPCE thermodynamically suppress the potency of electrolyte combustion; consequently in the single-layer internal short circuit test, the HPCE-cell needs much higher shorting current (104.3 A) (i

Li||NMC811 battery, with lithium-metal (high specific capacity and low redox potential) as anode and LiNi0.8 Co0.1 Mn0.1 O2 (NMC811) as cathode, has been widely accepted to be a good candidate as one of the high-energy-density batteries. However, its cyclability needs improvement to fulfill the requirement for its future commercial use, especially under practical conditions. Electrolyte plays a key role in improving the cycling performance of Li||NMC811 batteries, where a high voltage/electrochemical window and good stability with the electrodes of the electrolyte are required. Herein, a localized high-concentration electrolyte with an additive of lithium difluoro(oxalate)borate (LiDFOB) is reported that improves the cycling performance of Li||NMC811 cells under crucial conditions with Li foil thickness of 50 µm, cathode areal loading of 4 mAh cm-2 , the areal capacity ratio between the negative and positive electrodes (N/P ratio) of 2.6 and the electrolyte/cell capacity ratio (E/C ratio) of 3.0 g (Ah)-1 . These cells can maintain 80% of the capacity after 195 cycles.

Localized high-concentration electrolyte is widely acknowledged as a cutting-edge electrolyte for the lithium metal anode. However, the high fluorine content, either from high-concentration salts or from highly fluorinated diluents, results in significantly higher production costs and an increased environmental burden. Here, we have developed a novel electrolyte termed "Localized Medium-Concentration Electrolyte" (LMCE) to effectively address these issues. This LMCE is designed and produced by diluting a medium concentration (0.5 M - 1.5 M) electrolyte which is incompatible with lithium metal anode before diluting. It has ultralow concentration (0.1 M) and demonstrates remarkable compatibility with lithium metal anode. Surprisingly, our LMCE, despite having an ultralow concentration (0.1 M), exhibits excellent kinetics in Li/Cu, Li/Li, LiFePO4/Li, and NCM811/Li batteries. Additionally, LMCE effectively inhibits the corrosion of the Al current collector caused by LiTFSI salt under high voltage (> 4 V) conditions. This groundbreaking LMCE design transforms the seemingly "incompatible" into the "compatible", opening up new avenues for exploring various electrolyte formulations, including all liquid electrolyte-based batteries.

High-nickel layered oxide cathodes and lithium-metal anode are promising candidates for next-generation battery systems due to their high energy density. Nevertheless, the instability of the electrode-electrolyte interphase is hindering their practical application. Localized high-concentration electrolytes (LHCEs) present a promising solution for achieving uniform lithium deposition and a stable cathode-electrolyte interphase. However, the limited choice of diluents and their high cost are restricting their implementation. Four novel cost-effective diluents and their performance with highly reactive LiNiO2 cathode and Li-metal anode are reported here. The results show that all the LHCE cells exhibit a Coulombic efficiency of >99.38% in Li | Cu cells and a capacity retention of >85% in Li | LiNiO2 cells after 250 cycles. Advanced characterizations unveil that the stable cell operation is due to well-tuned electrode-electrolyte interphases and Li deposition morphology. In addition, online electrochemical mass spectroscopy and differential scanning calorimetry reveal that the gas generation and heat-release are greatly reduced with the LHCEs presented. Overall, the study provides new insights into the role of diluents in LHCEs and offers valuable guidance for further optimization of LHCEs for high energy density lithium-metal batteries.

The rising deployment of portable devices and electric vehicles has accelerated the development of high energy-dense batteries and revived interest in lithium metal as an anode material in recent years. However, by employing the widely-used organic carbonate-based electrolyte formulations in lithium-metal batteries (LMBs), whisker-like Li deposits emerge during galvanostatic cycling, precipitating a rapid active material degradation.1 Consequently, researchers have shifted their focus towards novel electrolyte formulations aimed at facilitating a dense Li deposition and prolonging the cycle life of LMBs. A promising approach is the application of localized high-concentration electrolytes (LHCEs) due to their unique solvation structure, causing the formation of an effective anion-derived Solid Electrolyte Interphase (SEI) and a dense Li deposition morphology.2–5 One of the remaining challenges for this novel electrolyte concept is the low ionic conductivity and the resulting declining galvanostatic cycling performance at higher current densities (> 1 mA cm-2), thus making the increase of the ion mobility crucial to enable LHCEs to become viable electrolyte solutions for LMBs. In our study, we investigated inexpensive heat transfer fluids as effective co-diluents for LHCEs employed in LMBs. Incorporating these low-cost fluids into the electrolyte formulation results in lower viscosity and enhances molecular diversity, thereby improving transport properties and causing superior fast-charging capabilities of the resulting LMB chemistry. While the introduction of these novel co-diluents appears to have no discernible effect on the composition of the interphase layer formation, their presence promotes a more uniform lithium deposition morphology, particularly under higher charging rates. Additionally, the non-flammable nature of these components enhances the safety profile of the LMBs, rendering the novel components as multifunctional co-diluents for LHCEs and concurrently improving several crucial properties of the resulting electrolyte formulation. References: Horstmann, B. et al. Strategies towards enabling lithium metal in batteries: interphases and electrodes. Energy Environ. Sci. 14, 5289–5314 (2021). Cao, X., Jia, H., Xu, W. & Zhang, J.-G. Review—Localized High-Concentration Electrolytes for Lithium Batteries. J. Electrochem. Soc. 168, 010522 (2021). Ren, X. et al. Enabling High-Voltage Lithium-Metal Batteries under Practical Conditions. Joule 3, 1662–1676 (2019). Ren, F. et al. Solvent–Diluent Interaction-Mediated Solvation Structure of Localized High-Concentration Electrolytes. ACS Appl. Mater. Interfaces 14, 4211–4219 (2022). Angarita-Gomez, S. & Balbuena, P. B. Ion mobility and solvation complexes at liquid–solid interfaces in dilute, high concentration, and localized high concentration electrolytes. Mater. Adv. 3, 6352–6363 (2022).

Lithium metal batteries (LMBs) encounter critical challenges at low temperatures due to the sluggish ion transport and unstable lithium deposition. Localized high concentration electrolytes, a representative weak−solvation strategy, have been extended to gel polymer electrolytes with tunable solvation structures and improved low−temperature performance. Herein, a moderately fluorinated segment is selected for the localized high concentration polymer electrolytes (LHCPE) by balancing dilution, salt dissociation, and copolymerization compatibility through side chain screening. Fine−tuning the dilution effect within the polymer matrix enables the formation of anion−rich coordination that maintains structural integrity at low temperatures, reducing reliance on polymer segmental motion and enhancing Li + transport with high ionic conductivities (2.12 × 10 −3 S·cm −1 at 25°C). The compact, anion‐dominated solvation structure promotes the formation of an inorganic−rich solid electrolyte interphase, supporting long−term symmetric cell operation for over 4000 h at room temperature and 2800 h at −20°C. The initial capacity of the Li||NCM811 full cells retained 74.72% and 51.68% of their room‐temperature capacity at −20°C and −40°C, respectively, achieved 92.62% capacity retention after 125 cycles at −20°C and 80.91% after 55 cycles at −40°C. This study provides insight for the rational design of LHCPEs toward high−performance LMBs in extreme environments.

The development of high-energy-density lithium metal batteries (LMBs) using carbonate electrolytes is severely hindered by unstable interfacial chemistry, leading to uncontrolled lithium dendrite growth and rapid performance degradation. Given that the electrode/electrolyte interface property is highly dependent on the interface interactions, this work introduces 1,4-dithiane (1,4-DH), an environmentally benign cyclic thioether, as a multifunctional additive for stabilizing electrode-electrolyte interfaces in conventional carbonate electrolytes without fluorinated solvents. The 1,4-DH additive exhibits preferentially adsorption on both Li metal anodes and NCM811 (LiNi0.8Co0.1Mn0.1O2) cathodes, displacing solvent molecules from electrode surfaces to suppress solvent decomposition while driving localized PF6 - enrichment at the electrode interfaces via a robust binding interaction. The additive undergoes preferential self-decomposition during cycling to form sulfur-rich SEI (solid-electrolyte-interphase)/CEI (cathode electrolyte interphase), promoting synergistic decomposition of PF6 - simultaneously to form inorganic-dominated interphases (LiF, Li2S). As a result, the lithium iron phosphate full cell achieves 87.54% capacity retention and 99.99% average coulombic efficiency over 3000 cycles. Crucially, 1,4-DH stabilizes NCM811 cathodes against cracking, enabling prolonged cycle stability at 4.8 V. The additive further demonstrates exceptional adaptability under extreme conditions (-10 and 60 °C) and practical pouch cell configurations. This work provides a practical strategy for durable LMBs via non-fluorinated electrolyte engineering.

High-energy-density lithium secondary batteries can be realized by pairing lithium-metal anodes (LMAs) with high-voltage, nickel-rich layered oxide cathodes. However, these systems often suffer from rapid capacity loss caused by structural breakdown in the cathode and unwanted side reactions between the electrolyte and both electrodes. In this study, a fluoroethylene carbonate (FEC)-based electrolyte enhanced with multi-functional additives is introduced, enabling stable cycling of high-voltage (4.5 V) lithium-metal batteries with high areal capacities exceeding 4 mAh cm⁻². Optimized electrolytes play a crucial role in forming cathode electrolyte interphase (CEI), preventing microcracks, and promoting uniform current distribution within the cathode. The electrolyte also forms a highly robust and stable solid electrolyte interphase (SEI) on the LMA. When used with Li[Ni₀.₇₈Co₀.₁Mn₀.₁₂]O₂ cathodes composed of radially aligned, rod-shaped primary particles (20 mg cm⁻²), the resulting cell achieves a specific capacity of 230 mAh g⁻¹ at 0.1 C and maintains over 86% of its initial capacity after 200 cycles at 0.5 C. This work underscores the importance of interfacial engineering through electrolyte design and the selection of morphologically optimized cathode materials for enhanced mechanical and electrochemical stability. Reference s : [1] H. Kim, S.-H. Lee, J.-M. Kim, C. S. Yoon, Y.-K. Sun, ACS Energy Lett. 8 (2023) 2970-2978. [2] H. Kim, S.-H. Lee, N.-Y. Park, J.-M. Kim, J.-Y. Hwang, Y.-K. Sun, Adv. Energy Sustainability Res. 5 (2024) 2300151. [3] H. Kim, J.-M. Kim, G.-T. Park, Y.-J. Ahn, J.-Y. Hwang, D. Aurbach, Y.-K. Sun, Adv. Energy Mater. 15 (2025) 2403386.

The electrolyte stability under high‐voltage conditions considerably limits the upper cut‐off potential of solid‐state electrolytes (SSEs) and therefore the energy density of all‐solid‐state batteries (ASSBs). In this work, metal‐organic frameworks (MOFs) were fluorinated to lower the energy level of HOMO orbital and allow access to a 4F‐MOF that exhibit enhanced anodic stability. The composited 4F‐MOF/PEO electrolyte could not only transport Li+ ions in the ordered framework channels, but also provide a remarkable high‐voltage stability up to 5.0 V, shielding oxidative decomposition that would otherwise occur at around 3.9 V for conventional PEO electrolytes. In addition, stable lithium deposition was demonstrated for more than 1,300 hours at 0.1 mA·cm‐2, while reversible charge‐discharge cycling performance was delivered in assembled Li||LiNi0.5Mn1.5O4 (LNMO) ASSBs up to 5.0 V. Post‐mortem X‐ray photoelectron spectroscopy (XPS) investigation on cathodes revealed presence of a LiF‐rich cathode electrolyte interface (CEI), supporting promoted stability towards high‐voltage ASSBs.

Lithium metal batteries (LMBs) with Li metal anodes and high‐voltage LiCoO2 (LCO) cathodes offer high energy density but face challenges such as Li dendrite growth and LCO structure degradation, which primarily arises from the electrolyte's inability to form a stable interphase. Herein, a dual‐additive optimized carbonate‐based electrolyte is developed, incorporating tetraethylammonium nitrate (TEANO3) and lithium difluorobis(oxalato) phosphate (LiDFBOP) as regulators. LiDFBOP enhances interfacial stability and compactness, while TEANO3 facilitates Li+ transport and suppresses excessive decomposition of LiDFBOP. The synergistic effect of TEANO3 and LiDFBOP establishes robust, high ion‐conductive solid electrolyte interphase (SEI) and cathode–electrolyte interphase (CEI) enriched with P‐ and N‐containing inorganic compounds (including LiNxOy and P‐O/P‐F species), enabling dense Li deposition and stable cycling of LCO under a high cut‐off voltage of 4.5 V. The optimized electrolyte enables Li||LCO full cells with a high capacity retention of 84% even with high‐mass‐loading LCO cathode (3.5 mAh cm−2) and limited Li (N/P = 2). This work demonstrates a straightforward electrolyte design strategy for optimizing SEI and CEI, advancing the practical deployment of LMBs.

Raising the charging voltage and employing high‐capacity cathodes like lithium cobalt oxide (LCO) are efficient strategies to expand battery capacity. High voltage, however, will reveal major issues such as the electrolyte's low interface stability and weak electrochemical stability. Designing high‐performance solid electrolytes from the standpoint of substance genetic engineering design is consequently vital. In this instance, stable SEI and CEI interface layers are constructed, and a 4.7 V high‐voltage solid copolymer electrolyte (PAFP) with a fluoro‐cyanogen group is generated by polymer molecular engineering. As a result, PAFP has an exceptionally broad electrochemical window (5.5 V), a high Li+ transference number (0.71), and an ultrahigh ionic conductivity (1.2 mS cm−2) at 25 °C. Furthermore, the Li||Li symmetric cell possesses excellent interface stability and 2000 stable cycles at 1 mA cm−2. The LCO|PAFP|Li batteries have a 73.7% retention capacity after 1200 cycles. Moreover, it still has excellent cycling stability at a high charging voltage of 4.7 V. These characteristics above also allow PAFP to run stably at high loading, showing excellent electrochemical stability. Furthermore, the proposed PAFP provides new insights into high‐voltage resistant solid polymer electrolytes.

The development of solid‐state lithium‐metal batteries (SLMBs) is severely hampered by conflicting electrolyte needs of the reactive anode and high‐voltage cathode, leading to lithium dendrite growth and poor interfacial stability. Herein, an asymmetric solid polymer electrolyte (SIPE) is proposed, with the cathode‐facing ionogel polymer electrolyte (IPE) constructing a “High‐Speed Ion Path” and the anode‐facing solid polymer electrolyte (SPE) forming a “Li⁺‐Exclusive Channel.” The ionic liquid (IL) in IPE decouples polymer‐Li⁺ interactions, and the in‐situ produced SiO2 reinforces conduction networks, boosting ionic conductivity to 0.85 mS cm−1. MOF in the SPE layer utilizes its porous structure and Lewis acidic sites to restrict anions and enable single Li⁺ transport, achieving a high Li⁺ transference number of 0.79 and uniform flux. Consequently, Li||SIPE||Li cells could cycle stably over 2000 h at 0.2 mA cm−2. Paired with NCM9055, it retains 88.1% capacity after 120 cycles (0.5 C) with a thin cathode electrolyte interphase (CEI, ≈5.5 nm). SIPE also demonstrates wide‐temperature operation (0–80°C) and enables a scalable Li||SIPE||LFP pouch cell with high areal capacity (5.59 mAh cm−2) and 95.4% retention after 90 cycles. This asymmetric design synergizes high ionic conductivity and excellent interface stability, offering a promising strategy for high‐energy SLMBs.

The rapid evolution of portable electronics and electric vehicles necessitates batteries with high energy density, robust cycling stability, and fast charging capabilities. High-voltage cathodes, like LiNi0.8Co0.1Mn0.1O2 (NCM-811), promise enhanced energy density but are hampered by poor stability and sluggish lithium-ion diffusion in conventional electrolytes. We introduce a metal-organic framework (MOF) liquid-infusion technique to fully integrate MOF liquid into the grain boundaries of NCM-811, creating a thoroughly coated cathode with a thin, rigid MOF Glass layer. The surface electrically non-conductive MOF Glass layer with 2.9 Å pore windows facilitating Li-ion pre-desolvation and enabling highly aggregative electrolyte formation inside the Glass channels, suppressing solvated Li-ion co-insertion and solvent decomposition. While the inner Glass layer composes of Li-ion conducting components and enhancing fast Li-ion diffusion. This functional structure effectively shields the cathode from particle cracking, CEI rupture, oxygen loss, and transition metal migration. As a result, Li | |Glass@NCM-811 cells demonstrate good rate capability and cycling stability even under high-charge rates and elevated voltages. Furthermore, we also achieve a 385 Wh kg-1 pouch-cell (19.579 g, for pouch-cell), showcasing the practical potential of this method. This straightforward and versatile strategy can be applied to other high-voltage cathodes like Li-rich manganese oxides and LiCoO2. Li-ion batteries based on high-voltage Ni-rich layered oxides are hampered by stability and ion diffusion issues. Here, authors develop a metal-organic-framework liquid-infusion technique to create a rigid glass layer on the oxide particles, improving both Li+ diffusion and battery stability.

Increasing the charging cutoff voltage of LiCoO2 to 4.6 V is significant for enhancing battery density. However, the practical application of Li‖LiCoO2 batteries with a 4.6 V cutoff voltage faces significant impediments due to the detrimental changes under high voltage. This study presents a novel bifunctional electrolyte additive, 2-(trifluoromethyl)benzamide (2-TFMBA), which is employed to establish a stable and dense cathode-electrolyte interface (CEI). Characterization results reveal that an optimized CEI is achieved through the synergistic effects of the amide groups and trifluoromethyl groups within 2-TFMBA. The resulting CEI not only enhances the structural stability of LiCoO2 but also serves as a high-speed lithium-ion conduction channel, which expedites the insertion and extraction of lithium ions. The Li‖LiCoO2 batteries with 0.5 wt% 2-TFMBA achieves an 84.7% capacity retention rate after enduring 300 cycles at a current rate of 1 C, under a cut-off voltage of 4.6 V. This study provides valuable strategic insights into the stabilization of cathode materials in high-voltage batteries.

Lithium (Li) metal anodes are considered one of the most promising anodes for high-performance batteries with ultra-high specific energy density. However, uncontrolled dendrite growth and the unsuitability of common systems for high voltage hinder the development of Li metal batteries with long cycle life. Herein, we report a rationally designed artificial solid electrolyte interphase (SEI) for Li metal anodes, incorporating LiNO3 and lithium difluoro(oxalato)borate (LiDFOB) as additives within a porous poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer skeleton (referred to as PNF). LiNO3 and LiDFOB can release and synergistically react at the electrode surface, leading to the in situ generation of a homogeneously distributed inorganic/organic SEI during the electrochemical process. This SEI improves homogeneity, ionic conductivity and mechanical stability, contributing to the suppression of electrolyte side reactions and Li dendrite growth. Moreover, a uniform CEI with high Li+ conductivity can be constructed on the NCM811 particles, further enhancing the structural integrity of the NCM811 cathode. As a result, the artificial SEI layer on Li metal anodes enables stable cycling of Li-Cu half cells in an ester-based electrolyte and Li-LiNi0.8Mn0.1Co0.1O2 full cell even at a high voltage of 4.5 V. This work provides new insights into designing homogeneous SEIs for Li metal batteries.

Quasi-solid polymer electrolyte (QPE) lithium (Li)-metal battery holds significant promise in the application of high-energy-density batteries, yet it suffers from low ionic conductivity and poor oxidation stability. Herein, a novel self-built electric field (SBEF) strategy is proposed to enhance Li+ transportation and accelerate the degradation dynamics of carbon-fluorine bond cleavage in LiTFSI by optimizing the termination of MXene. Among them, the SBEF induced by dielectric Nb4C3F2 MXene effectively constructs highly conductive LiF-enriched SEI and CEI stable interfaces, moreover, enhances the electrochemical performance of the QPE. The related Li-ion transfer mechanism and dual-reinforced stable interface are thoroughly investigated using ab initio molecular dynamics, COMSOL, XPS depth profiling, and ToF-SIMS. This comprehensive approach results in a high conductivity of 1.34 mS cm-1, leading to a small polarization of approximately 25 mV for Li//Li symmetric cell after 6000 h. Furthermore, it enables a prolonged cycle life at a high voltage of up to 4.6 V. Overall, this work not only broadens the application of MXene for QPE but also inspires the great potential of the self-built electric field in QPE-based high-voltage batteries.

High‐voltage LiCoO2 is a promising cathode candidate for achieving high‐energy lithium metal pouch cells. However, further application is still hindered by irreversible structural degradation and severe interfacial side reactions that accelerate capacity decay. Herein, 1‐Azaphenothiazine (1‐APT) is incorporated as a cathode slurry additive (1 g mL−1 in N‐methyl‐2‐pyrrolidone) to promote the optimization of the LiCoO2 interface during the electrode coating process. The ultra‐soluble 1‐APT promotes the formation of inorganic‐rich components within the cathode‐electrolyte interphase (CEI), mitigates the reaction of Co4+ with the electrolyte, and enhances the interfacial stability of LiCoO2, thereby enabling 4.7 V LiCoO2 with an initial capacity of 229.8 mAh g−1 and 73.2% capacity retention after 200 cycles. More importantly, Li||LiCoO2‐1‐APT pouch cells exhibit remarkable electrochemical performance, achieving specific energies of 515.7 , 497.4 , and 484.9 Wh kg−1 at discharge rates of 0.5C, 1C, and 2C, respectively. Notably, the 5 Ah pouch cell exhibited the capability to maintain an energy density of 411.4 Wh kg−1 after 100 cycles at 0.5C. This work presents a practical and effective strategy for optimizing cathode interfaces, thereby enabling the stabilization of high‐voltage cathodes.

ABSTRACT Achieving stable cycling of lithium metal batteries (LMBs) at high voltages presents a significant challenge due to interfacial instability and uneven lithium-ion transport, leading to dendrite formation and cathode degradation. Constructing a solid-electrolyte interphase (SEI) that facilitates fast and uniform ion transport is crucial for enhancing the stability of electrode structures. However, current research mainly focuses on interfacial instability while neglecting uneven ion transport, which is even more critical. In this study, we develop a novel electrolyte system, PAFE, by incorporating aluminum ethoxide (Al(EtO)3), fluoroethylene carbonate (FEC), and pentafluorocyclotriphosphazene (PFPN) into a carbonate-based electrolyte. Al(EtO)3 serves as a crosslinking agent, facilitating the formation of a three-dimensional polymer network that promotes the uniform deposition of inorganic components such as LiF, Li3N, Li3P and Al2O3 within the SEI and cathode-electrolyte interphase (CEI). These uniform interphases lower the activation energy for lithium-ion transport, thereby ensuring consistent ion flow and reducing internal stress within the electrodes. As a result, Li||LiNi0.8Co0.1Mn0.1O2 (NCM811) cells with PAFE exhibit exceptional cycling stability, retaining 80% capacity over 140 cycles at a high cut-off voltage of 4.7 V. Furthermore, 1 Ah pouch cells demonstrate excellent cycling performance, highlighting the potential of this electrolyte system for practical high-energy-density LMB applications.

No abstract available

High-voltage lithium metal batteries suffer from poor cycling stability caused by the detrimental effect on the cathode of the water moisture present in the non-aqueous liquid electrolyte solution, especially at high operating temperatures (e.g., ≥60 °C). To circumvent this issue, here we report lithium hexamethyldisilazide (LiHMDS) as an electrolyte additive. We demonstrate that the addition of a 0.6 wt% of LiHMDS in a typical fluorine-containing carbonate-based non-aqueous electrolyte solution enables a stable Li||LiNi0.8Co0.1Mn0.1O2 (NCM811) coin cell operation up to 1000 or 500 cycles applying a high cut-off cell voltage of 4.5 V in the 25 °C−60 °C temperature range. The LiHMDS acts as a scavenger for hydrofluoric acid and water and facilitates the formation of an (electro)chemical robust cathode|electrolyte interphase (CEI). The LiHMDS-derived CEI prevents the Ni dissolution of NCM811, mitigates the irreversible phase transformation from layered structure to rock-salt phase and suppresses the side reactions with the electrolyte solution. High-voltage non-aqueous lithium metal batteries suffer from poor cycling stability due to the presence of impurities in the electrolyte solution. Here, the authors report lithium hexamethyldisilazide to scavenge HF and H2O, prevent the Ni dissolution and suppress side reactions during cycling.

The combination of lithium metal anodes and high-load Li-rich Mn-based cathodes (LMLO, Li1.2Mn0.54Co0.13Ni0.13O2) empowers lithium metal batteries (LMBs) to reach energy densities above 500 W h kg-1. However, sluggish kinetics, continuous interfacial reactions, and serious safety concerns impede their practical application. Herein, a flame-retardant carbonate-based electrolyte containing hexafluorocyclotriphosphazene (HFPN), lithium difluoro(oxalato) borate (LiDFOB), and 1-butyl-2,3-dimethylimidazolium nitrate (BDIN) coadditives has been designed to enable 528 W h kg-1 LMBs with enhanced safety performance by synchronously regulating the formation of kinetically enhanced cathode electrolyte interphase (CEI) and solid electrolyte interphase (SEI). Specifically, flame-retardant HFPN facilitates the formation of a stable CEI enriched with P-, F-, and N-containing inorganic species, thereby improving the thermal stability and Li+ transport kinetics. LiDFOB participates in forming a fast Li+ conducting SEI on the lithium metal anode, while the interaction between BDIN and FEC promotes the decomposition of FEC to induce an F-containing organic matter SEI, which achieves a Coulombic efficiency exceeding 95.9% in the Li||Cu cell. As a result, an LMLO||Li full cell with 6.4 mA h cm-2 delivers a capacity of 272 mA h g-1 and 94.7% retention after 50 cycles. This strategy for the interphase regulation and safety enhancement by synergistic additives can practically be extended to other high-energy lithium-ion batteries.

Flexible lithium metal batteries (LMBs) using polymer‐based solid‐state electrolytes (PSSEs) are highly desirable for wearable applications because of the potential advantages in energy density and safety. Recently, ether‐based polyelectrolytes have received extensive attention because of their good stability, high ionic conductivity, and Li metal anode compatibility. However, it typically forms organic‐rich cathode electrolyte interphase (CEI) at the cathode, which is still a pain point that impedes the high‐voltage performance. To address this challenge, herein a fluorinated plasticizer, bis(2‐fluoroethyl) ether (BFE) is reported, which can be easily blended into ether‐based PSSE and enables high‐voltage‐stable flexible LMBs. The BFE and PSSE molecules form an atypical hydrogen bond interaction, which weakens the interaction between PSSE and lithium ions. This leads to the formation of an anion‐rich solvation structure that generates inorganic‐rich and high‐voltage‐stable CEI. The oxidation stability of PSSE is improved from 4.4 V to over 4.7 V after introducing the BFE molecules. LMBs using BFE‐blended PSSE can couple with high‐voltage cathode and retain 80% capacity after 480 cycles at 1C. Full cells show high energy density (752.2 Wh L−1) outstanding capacity retention per cycle (99.88%), and high flexibility with almost identic charge/discharge characteristics after 4000 bending cycles.

The application of rechargeable lithium metal batteries (LMBs) has been hindered by the fast growth of lithium dendrites during charge and the limited cycling life because of the decomposition of the electrolyte at the interface. Here, we have developed a non-flammable triethyl phosphate (TEP)-based electrolyte with tris(hexafluoroisopropyl)phosphate (THFP) as an additive. The polar nature of the C-F bonding and the rich CF3 groups in THFP lowers its LUMO energy and HOMO energy to help form a stable, LiF-rich solid electrolyte interphase (SEI) layer through the reduction of THFP and increases the binding ability of the PF6- anions, which significantly suppresses lithium dendrite growth and reduces the electrolyte decomposition. Moreover, THFP participates in the formation of a thin, C-F rich electrolyte interphase (CEI) layer to provide the stable cycling of the cathode at a high voltage. The symmetric Li||Li and full Li/NCM622 cells with THFP additive have small polarization and long cycling life, which demonstrates the importance of the additive to the application of the LMBs.

Stabilizing high-voltage cathodes in lithium metal batteries (LMBs) remains a key challenge due to severe interfacial degradation. Although anion-derived, inorganic-rich cathode-electrolyte interphases (CEIs) offer a promising solution, most conventional anions are chemically inert and lack the multifunctionality required to undergo both chemical and electrochemical decomposition across a wide potential window. Existing strategies to enhance anion reactivity often involve trade-offs in salt concentration, anodic stability, or environmental concern, highlighting the need for novel anion design with intrinsic and synergistic interfacial activity. In this study, we designed a multifunctional anion, 1,1,1-trifluoro-2,5,8-trioxa-1-borate (FTOB), by integrating a chelating polyethylene glycol backbone with a terminal -BF3 group as a CEI precursor. The reactive B-O bond facilitates a stepwise interphase formation mechanism: chemical decomposition of FTOB and PF6- at lower potentials (<4.5 V vs Li+/Li) via their mutual interactions, followed by direct electrochemical oxidation of FTOB at higher potentials. These dual pathways enable the construction of LiF- and borate-rich CEIs, supporting stable cycling of LMBs with both 4.3-V high-nickel layered cathode and 5-V cobalt-free spinel cathode. This work highlights the potential of rational anion design to integrate multiple interfacial formation mechanisms, advancing interphase engineering for high-voltage LMBs.

Solid-state Li-metal batteries offer a great opportunity for high-security and high-energy-density energy storage systems. However, redundant interfacial modification layers, intended to lead to an overall satisfactory interfacial stability, dramatically debase the actual energy density. Herein, a dual-interface amorphous cathode electrolyte interphase/solid electrolyte interphase CEI/SEI protection (DACP) strategy is proposed to conquer the main challenges of electrochemical side reactions and Li dendrites in hybrid solid-liquid batteries without sacrificing energy density via LiDFOB and LiBF4 in situ synergistic conversion. The amorphous CEI/SEI products have an ultralow mass proportion and act as a dynamic shield to cooperatively enforce dual electrodes with a well-preserved structure. Thus, this in situ DACP layer subtly reconciles multiple interfacial compatibilities and a high energy density, endowing the hybrid solid-liquid Li-metal battery with a sustainably brilliant cycling stability even at practical conditions, including high cathode loading, high voltage (4.5 V), and high temperature (45 °C) conditions, and enables a high-energy-density (456 Wh kg-1) pouch cell (11.2 Ah, 5 mA h cm-2) with a lean electrolyte (0.92 g Ah-1, containing solid and liquid phases). The compatible modification strategy points out a promising approach for the design of practical interfaces in future solid-state battery systems.

Poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs) are favorable for all-solid-state lithium metal batteries (ASSLBs) to ensure safety and enhance energy density. However, their narrow work windows and unstable electrode/electrolyte interfaces hinder their practical application in high-voltage ASSLBs. Although introducing additives in SPEs has been proven to be effective to address the above issues, it could hardly optimize both cathode and anode interfaces by an individual additive. Herein, heterogeneously double-layer SPEs are constructed with two typical additives (LiPO2F2 and LiFSI), which are used to modify the LiNi0.6Co0.2Mn0.2O2 (NCM)-cathode/electrolyte interface (CEI) and lithium-anode/solid electrolyte interface (SEI), and further understand their respective mechanism in enhancing the capacity and cycling stability of ASSLBs. Specifically, LiPO2F2 not only leads to a uniform CEI layer to prevent the oxidation decomposition of PEO and LiTFSI but also ensures fast Li+ diffusion at high voltage (>3.9 V), improving the rate performances and life spans of the cells. The LiFSI contributes to a stable SEI layer with rich LiF, suppressing the growth of lithium dendrites and maximizing the specific capacity for ASSLBs. Integrating the advantages of the two functional molecules, the optimized ASSLB displays an excellent capacity of 141.4 mAh g-1 at 1C and an outstanding capacity retention of 81.6% after 400 cycles when using the NCM cathode, even reaching 154.2 mAh g-1 at 0.1 mA cm-2 with a high mass loading (6.4 mg cm-2). Additionally, the bilayer SPEs also match well with a LiFePO4 electrode with a high mass loading of 11.0 mg cm-2, displaying a high capacity of 155.7 mAh g-1 at 0.1 mA cm-2.

Hybrid solid/liquid electrolyte with superior security facilitates the implementation of high-energy-density storage devices, while suffers from inferior chemical compatibility with cathodes. Herein, an optimal lithium difluoro(oxalato)borate salt was introduced to in situ build an amorphous cathode electrolyte interphase (CEI) between Ni-rich cathodes and hybrid electrolyte. The formed CEI preserves the surface structure with high compatibility, leading to enhanced interfacial stability. Meanwhile, the space-charge layer can be prominently mitigated at the solid/solid interface via harmonized chemical potentials, acquiring promoted interfacial dynamics that revealed by COMSOL simulation. Consequently, the amorphous CEI integrates the bifunctionality to provide an excellent cycling stability, high Coulombic efficiency and favourable rate capability in high-voltage Li-metal batteries, innovating the design philosophy of functional CEI strategy for future high-energy-density batteries.

Constraining the electrochemical reactivity of free solvent molecules is pivotal for developing high-voltage lithium metal batteries, especially for ether solvents with high Li metal compatibility but low oxidation stability ( <4.0 V vs Li+/Li). The typical high concentration electrolyte approach relies on nearly saturated Li+ coordination to ether molecules, which is confronted with severe side reactions under high voltages ( >4.4 V) and extensive exothermic reactions between Li metal and reactive anions. Herein, we propose a molecular anchoring approach to restrict the interfacial reactivity of free ether solvents in diluted electrolytes. The hydrogen-bonding interactions from the anchoring solvent effectively suppress excessive ether side reactions and enhances the stability of nickel rich cathodes at 4.7 V, despite the extremely low Li+/ether molar ratio (1:9) and the absence of typical anion-derived interphase. Furthermore, the exothermic processes under thermal abuse conditions are mitigated due to the reduced reactivity of anions, which effectively postpones the battery thermal runaway. Advanced electrolyte is essential for high-energy-density lithium metal batteries. Here, the authors design a molecular anchoring dilute electrolyte via intermolecular hydrogen bonding with free solvents to improve the battery electrochemical and thermal stabilities.

No abstract available

Interfacial stability in high-energy-density lithium metal batteries (LMBs) hinges on precise regulation of dynamic interfacial electrolyte configuration. Although inert cations are frequently employed to stabilize Li-metal anode, their interfacial adsorption behavior and the resultant evolution of the electrolyte/electrode interface remain elusive. Herein, using in-situ spectroscopy, we visualized the adsorption of inert cations, exemplified by tetrabutylammonium (TBA+). Furthermore, the inherent anion-lean, solvent-rich interface formed during desolvation was mitigated by the electrostatic interaction between TBA+ and anions. This anion-anchoring effect promotes preferential anion decomposition, thereby suppressing parasitic reactions associated with solvent decomposition. Consequently, the cycling stability and reversibility of Li stripping/plating are significantly enhanced. This work not only refreshes the understanding of inert cations on regulating the interfacial electrolyte configuration, but also highlights the close relationship between the interfacial solvation configuration and the SEI architecture, offering fundamental insights for potential electrolyte design.

No abstract available

Optimizing liquid electrolytes is essential for achieving long‐term cycling stability and high safety in lithium metal batteries. However, severe side reactions and lithium dendrite formation during repeated cycling lead to low Coulombic efficiency (CE) and limited lifespan. Herein, a rapid and cost‐effective strategy that integrates high‐throughput molecular dynamics simulations with machine learning predictions is proposed, further validated through experimental evaluation. A mixed electrolyte composed of LiFSI (LiN(SO2F)2) as the main salt, DEE (1,2‐diethoxyethane) as the solvent, and LiNFS (LiC4F9SO3) as an additive achieves a significantly improved CE of 98.32%. Key molecular descriptors are identified for each performance label, and the most accurate model is selected through rigorous benchmarking. The optimal region reveals a preference for medium‐to‐high salt concentrations; low C, O, and N content; and high F content in salts, along with high C and low O content in solvents. This framework enables reusable and resource‐efficient modeling for targeted electrolyte design and accelerated optimization.

Solid‐state lithium metal batteries (SSLMBs) with poly (ethylene oxide) (PEO)‐based electrolytes have increasingly become one of the most promising battery technologies due to high energy density and safety. However, adverse electrode/electrolyte interface compatibility issues hinder further application. Herein, a PEO‐based composite solid electrolyte with excellent anode and cathode interfacial compatibility is designed via the coordination modulation strategy induced by lithium difluorobis(oxalato)phosphate (DFBOP). By utilizing this electrolyte, the robust inorganic‐rich interphase involving LiF, LixPOyFz, and P─O components is in situ generated on lithium (Li) anode and LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode surfaces via forceful coordination among PEO, lithium bis(trifluoromethanesulphonyl)imide, and DFBOP and subsequent adjustment of front orbital energy levels. It contributes to homogeneous lithium deposition and an effective impediment of PEO oxidation decomposition at high voltage, promoting superior interfacial stability. Consequently, Li‐symmetric cells with modified electrolyte can achieve a stable cycle over 7000 h at 0.2 mA cm−2. Specially, the cathode electrolyte interphase with a unique organic–inorganic interpenetration network structure enables the 4.5 V Li/NCM811 cells to cycle steadily over 100 cycles, with a high discharge capacity of 215.4 mAh g−1 and initial coulombic efficiency of 91.23%. This research has shed light on the interfacial design of PEO‐based electrolytes from the perspective of electrolyte coordination regulation to construct high‐performance SSLMBs.

Solid polymer electrolytes (SPEs) with high ionic conductivity, high lithium-ion transference number (tLi+), and good mechanical properties are highly desired for solid-state lithium metal batteries. However, developing SPEs with both high ionic conductivity and high tLi+ remains a challenge. Herein, a novel network structure single-ion polymer electrolyte (SIPU) with high ionic conductivity (0.12 mS cm-1), tLi+ (0.71) and mechanical strength (1.5 MPa) was prepared by UV-initiated free radical polymerization and chemically crosslinking of the functional groups. The characterization and Density functional theory (DFT) calculation demonstrate that the construction of a cross-linked network structure not only endows the electrolytes membranes with improved mechanical strength to inhibit dendrite growth but also facilitates fast dissociation of Li+ for boosting ionic kinetics. More importantly, a robust LiF-rich Solid Electrolyte Interface (SEI) was formed on the Lithium metal anode, enhancing the cycling performance of batteries. As a result, the Li symmetric cells using the SIPU electrolytes can stably cycle over 2000 h. The Li/SIPU/LiFePO4 cells deliver excellent cycle performance and maintain stably cycling over 1000 cycles at 0.5C. The Li/SIPU/LiNi0.8Co0.1Mn0.1O2 cells also have excellent cycling and rate performance. Furthermore, the Li/SIPU/LiFePO4 pouch cells exhibit excellent performance. This work provides valuable insights into the rational design of polymer electrolytes with mechanical and electrochemical stability.

High-energy-density lithium-metal batteries (LMBs) coupling lithium-metal anodes and high-voltage cathodes are hindered by unstable electrode/electrolyte interphases (EEIs), which calls for the rational design of efficient additives. Herein, we analyze the effect of electron structure on the coordination ability and energy levels of the additive, from the aspects of intramolecular electron cloud density and electron delocalization, to reveal its mechanism on solvation structure, redox stability, as-formed EEI chemistry, and electrochemical performances. Furthermore, we propose an electron reconfiguration strategy for molecular engineering of additives, by taking sorbide nitrate (SN) additive as an example. The lone pair electron-rich group enables strong interaction with the Li ion to regulate solvation structure, and intramolecular electron delocalization yields further positive synergistic effects. The strong electron-withdrawing nitrate moiety decreases the electron cloud density of the ether-based backbone, improving the overall oxidation stability and cathode compatibility, anchoring it as a reliable cathode/electrolyte interface (CEI) framework for cathode integrity. In turn, the electron-donating bicyclic-ring-ether backbone breaks the inherent resonance structure of nitrate, facilitating its reducibility to form a N-contained and inorganic Li2O-rich solid electrolyte interface (SEI) for uniform Li deposition. Optimized physicochemical properties and interfacial biaffinity enable significantly improved electrochemical performance. High rate (10 C), low temperature (-25 °C), and long-term stability (2700 h) are achieved, and a 4.5 Ah level Li||NCM811 multilayer pouch cell under harsh conditions is realized with high energy density (462 W h/kg). The proof of concept of this work highlights that the rational ingenious molecular design based on electron structure regulation represents an energetic strategy to modulate the electrolyte and interphase stability, providing a realistic reference for electrolyte innovations and practical LMBs.

No abstract available

Fluorinated-ethers are promising electrolyte solvents in lithium metal batteries, for their high antioxidant and excellent reductive stability on Li anode. However, fluorinated-ethers with high fluorination degree suffer from low ionic conductivity and narrow temperature adaptibility. Herein, we synthesize a mono-fluorinated linear ether of bis(2-fluoroethoxy) methane (BFME) with enhanced solvated ability. The -OCH2O- structure and fluoride substitution on the β-C position endows the BFME electrolyte with moderate affinity to Li+, thereby improving the ionic conductivity and decreasing the Li+-desolvation energy barrier at a wide temperature range of -60 ̶ 60 oC. Additionally, the electrolyte with anion-participated solvation structure demonstrates high film-forming ability by forming LiF-rich interfacial film on the electrode surfaces, rendering the graphite anode with an initial Coulombic efficiency (CE) of 94.9% and a Li plating/stripping CE of 99.8% by Aurbach method. Consequently, the Graphite||LiFePO4 pouch cells delivered 83.2%, 92.5% and 81.2% capacity retention after 1250, 200 and 300 cycles at 25, -20 oC and 60 oC, respectively. Moreover, the Li||LFP pouch cell with 3 Ah capacity can operate for 65 cycles with 99% capacity retention, verifying the effectiveness of the BFME electrolyte in stabilizing the interfaces and broadening the temperature adaptibility of lithium-ion and lithium metal batteries.

Ultrahigh-voltage lithium metal batteries based on cobalt-free LiNi0.5Mn1.5O4 (LNMO) cathode (5 V-class, vs. Li+/Li) and lithium metal anode (-3.04 V vs. the standard hydrogen electrode) have attracted extensive attention in...

No abstract available

The practical application of semisolid lithium metal batteries is impeded by inadequate ionic conductivity, suboptimal oxidation/reduction stability, and safety concerns of the electrolyte. Herein, a versatile molecular engineering strategy is proposed to construct a robust polymer framework for semisolid electrolytes, which creates highly compatible cross-linked networks by the in situ gelation of concentrated succinonitrile-based plastic crystal electrolytes and multifunctional nitrogen- and fluorine-rich monomers. This strategy allows the electrolyte to promote rapid Li-ion transpsort through weak coordination with the polymer segments. Meanwhile, the strong interactions between the polymer matrix and succinonitrile enhance their mutual solubility, reduce the crystallinity of succinonitrile, and establish fast ion-conductive pathways. The resultant electrolyte induces the formation of LiF/Li3N-rich solid electrolyte interphases and achieves uniform lithium deposition behaviors. Moreover, it mitigates fire risks by cothermally decomposing to produce fire-extinguishing gases (CO2 and NH3) and leveraging the nonflammability of succinonitrile. Significant improvements in electrochemical performance have been observed in Li symmetric, Li||LiFePO4, and Li||LiNi0.8Co0.1Mn0.1O2 cells both at room temperature and high temperature (60 °C). As a demonstration model, this molecular engineering strategy has been successfully applied to enhance thermal stability and safety in Li||LiNi0.8Co0.1Mn0.1O2 pouch cells, offering a promising solution for semisolid lithium metal batteries under extreme conditions.

Polycarbonate-based electrolytes are ideal electrolytes for solid-state lithium metal batteries (LMBs) due to their wider electrochemical windows and considerable ionic conductivities compared with conventional solid polymer electrolytes. However, polycarbonates encounter severe interfacial side reactions with lithium metal, leading to the interfacial degradation of polymers. Herein, a spontaneously formed restricted conformation is designed via the in situ anchoring of side chains to suppress the interfacial degradation of polycarbonate-based electrolytes. The restricted conformation enables the side chains to shield and protect the degradable ester bonds of cyclic carbonates, suppressing contact and interfacial degradation between polycarbonates and lithium metal anodes. As a proof of concept, the protected polycarbonate-based electrolyte demonstrates a stable cycling capability of the Li/Li cell beyond 1000 h at a current density of 0.5 mA cm-2, and the assembled LiNi0.8Co0.1Mn0.1O2/Li pouch cell also achieves similar improvement in cycling performance. This work indicates that the strategy of constructing restricted conformations via anchoring side chains is a feasible avenue for fabricating highly stable polycarbonate-based solid-state LMBs.

Electrolyte engineering plays a critical role in tuning lithium plating/stripping behaviors, thereby enabling safer operation of lithium metal anodes in lithium metal batteries (LMBs). However, understanding how electrolyte microstructures influence the lithium plating/stripping process at the molecular level remains a significant challenge. Herein, using a commonly employed ether‐based electrolyte as a model, the role of each electrolyte component is elucidated and a relationship between electrolyte behavior and the lithium plating/stripping process is established by investigating the effects of electrolyte compositions, including solvents, salts, and additives. The variations in Li+ deposition kinetics are not only analyzed by characterizing the lithium deposition overpotential and exchange current density but it is also identified that the intermolecular interactions are the previously unexplored cause of these variations by 2D nuclear overhauser effect spectroscopy (NOESY). An interfacial model is developed to explain how solvent interactions, distinct roles of anions, and critical effects of additives influence Li+ desolvation kinetics and the thermodynamic stability of desolvation clusters during lithium plating/stripping process. This model clarifies how these configurations of solvents and ions are related to the macroscopic properties of lithium plating/stripping chemistry. These findings contribute to more uniform and controllable lithium deposition, providing valuable insights for designing advanced electrolyte systems for LMBs.

All‐solid–state lithium metal batteries (LMBs) are currently one of the best candidates for realizing the yearning high‐energy–density batteries with high safety. However, even polyethylene oxide (PEO), the most popular polymeric solid‐state electrolyte (SSE) with the largest ionic conductivity in the category so far, has significant challenges due to the safety issues of lithium dendrites, and the insufficient ionic conductivity. Herein, molecular sieve (MS) is integrated into the PEO as an inert filler with the liquid metal (LM) as a functional module, forming an “LM‐MS‐PEO” composite as both SSE with enhanced ionic conductivity, and protection layer against lithium dendrites. As demonstrated by theoretical and experimental investigations, LM released from MS can be uniformly and efficiently distributed in PEO, which could avoid agglomeration, enable the effective blocking of lithium dendrites, and regulate the mass transport of Li ions, thus achieving even deposition of lithium during charge/discharge. Moreover, MS could reduce the crystallinity of PEO, improve lithium‐ion conductivity, and reduce operating temperature. Benefiting from the introduction of the functional MS/LM, the LM‐MS‐PEO electrolyte exhibits fourfold higher lithium ionic conductivity than the pristine PEO at 40 °C, while the as‐assembled all‐solid–state LMBs have four to five times longer stable cycle life.

The advancement of lithium metal batteries toward their theoretical energy density potential remains constrained by safety and performance issues inherent to liquid electrolytes. Quasi‐solid‐state electrolytes (QSSEs) based on poly‐1,3‐dioxolane (poly‐DOL) represent a promising development, yet challenges in achieving satisfactory Coulombic efficiency and long‐term stability have impeded their practical implementation. While lithium nitrate addition can enhance efficiency, its incorporation results in prohibitively slow polymerization rates spanning several months. In this work, high‐polymerization‐enthalpy 1,1,1‐trifluoro‐2,3‐epoxypropane is introduced as a co‐polymerization promoter, successfully integrating lithium nitrate into poly‐DOL‐based QSSEs. The resulting electrolyte demonstrates exceptional performance with 2.23 mS cm−1 of ionic conductivity at 25 °C, a Coulombic efficiency of 99.34% in Li|Cu cells, and stable lithium metal interfaces sustained through 1300 h of symmetric cell cycling. This co‐polymerization approach also suppresses poly‐DOL crystallization, enabling Li|LiFePO4 cells to maintain stability beyond 2000 cycles at 1C. Scale‐up validation in a ≈1 Ah Li|NCM811 pouch cell achieves 94.4% capacity retention over 60 cycles. This strategy establishes a new pathway for developing high‐performance, in situ polymerized quasi‐solid‐state batteries for practical energy storage applications.

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No abstract available

To achieve high-performance solid-state lithium-metal batteries (SSLMBs), solid electrolytes with high ionic conductivity, high oxidative stability, and high mechanical strength are necessary. However, balancing these characteristics remains dramatically challenging and is still not well addressed. Herein, a simple yet effective design strategy is presented for the development of high-performance polymer electrolytes (PEs) by exploring the synergistic effect between dynamic H-bonded networks and conductive zwitterionic nanochannels. Multiple weak intermolecular interactions along with ample nanochannels lead to high oxidative stability (over 5 V), improved mechanical properties (strain of 1320%), and fast ion transport (ionic conductivity of 10-4 S cm-1 ) of PEs. The amphoteric ionic functional units also effectively regulate the lithium ion distribution and confine the anion transport to achieve uniform lithium ion deposition. As a result, the assembled SSLMBs exhibit excellent capacity retention and long-term cycle stability (average Coulombic efficiency: 99.5%, >1000 cycles with LiFePO4 cathode; initial capacity: 202 mAh g-1 , average Coulombic efficiency: 96%, >230 cycles with LiNi0.8 Co0.1 Mn0.1 O2 cathode). It is exciting to note that the corresponding flexible cells can be cycled stably and can withstand severe deformation. The resulting polyzwitterion-mediated PE therefore offers great promise for the next-generation safe and high-energy-density flexible energy storage devices.

The lithium (Li) metal polymer battery (LMPB) is a promising candidate for solid-state batteries with high safety. However, high voltage stability of such a battery has been hindered by the use of polyethylene oxide (PEO), which oxidizes at a potential lower than 4 V versus Li. Herein, we adopt the polymer-in-salt electrolyte (PISE) strategy to circumvent the disadvantage of the PEO-lithium bis(fluorosulfonyl)imide (LiFSI) system with EO/Li ≤ 8 through a dry ball-milling process to avoid the contamination of the residual solvent. The obtained solid-state PISEs exhibit distinctly different morphologies and coordination structures which lead to significant improvement in oxidative stability. P(EO)1LiFSI has a low melting temperature, a high ionic conductivity at 60 °C, and an oxidative stability of ∼4.5 V versus Li/Li+. With an effective interphase rich in inorganic species and a good stability of the hybrid polymer electrolyte toward Li metal, the LMPB constructed with Li||LiNi1/3Co1/3Mn1/3O2 can retain 74.4% of capacity after 186 cycles at 60 °C under the cutoff charge voltage of 4.3 V. The findings offer a promising pathway toward high-voltage stable polymer electrolytes for high-energy-density and safe LMPBs.

Ether‐based electrolytes promise superior interfacial stability with lithium metal under high salt concentration, while poor oxidative stability limits the high‐voltage operation. Extending the intrinsic electrochemical window and reducing the salt concentration to design high‐voltage lithium metal batteries is challenging and urgent. Herein, lightweight electrolytes based on intermolecular interactions regulated by ternary anion chemistry are proposed. An anion‐enriched solvation structure is achieved at a standard salt concentration (1 m) via enhanced ion‐dipole interactions, generating an inorganic‐rich electrode‐electrolyte interphase and enabling facile lithium plating/stripping kinetics. This results in lithium metal exhibiting an average Coulombic efficiency of 97.9% and a prolonged cycling lifespan (1000 h) at 2 mA cm⁻2. The hydrogen bond‐like interactions between NO3−/TFSI− and tetrahydrofuran, coupled with the preferential decomposition of DFOB− on the Ni‐rich cathode, boosts the electrolyte oxidative stability and mitigates the structural degradation of the cathode. Consequently, the Li||LiNi0.8Co0.1Mn0.1O2 cells demonstrate improved cycling stability (retaining 75% capacity after 300 cycles) and superior rate capability (153.6 mAh g⁻1 at 5C) at high cathode loading. This work supplies a molecular‐level design strategy for low‐concentration electrolytes tailored for high‐voltage lithium metal batteries, offering a promising pathway toward practical high‐energy‐density storage systems.

Research progress to clarify the mechanism of the changes in the behaviors of free organic molecules after the addition of polymers impacting on oxidative stability of the electrolyte using quantum and molecular dynamics simulations.

Polyethylene oxide (PEO) electrolytes hold significant potential for the next‐generation all‐solid‐state lithium metal batteries. However, their practical application is limited by low ionic conductivity, unstable solid electrolyte interphase (SEI) and, especially, poor oxidative stability under high voltages. Herein, a filler‐modified PEO is proposed to address these challenges. The filler, TIO (SnO2 doped with In2O3), is rich in oxygen vacancies, acting as Lewis acids to interact with TFSI−, which releases more Li+ and achieves a higher ionic conductivity and Li+ transference number. Moreover, Sn4+/In3+ in the TIO can form alloy phases with lithium metal to facilitate Li+ deposition and transport across the SEI. Consequently, Li//LiFePO4 cells using the filler‐modified PEO exhibit a reversible capacity of ∼140 mAh g−1 and excellent capacity retention of 92% over 800 cycles at 0.2 C. Importantly, the TIO interacts with hydroxy groups and H atom on α‐C in PEO, reducing PEO's reactivity and extending its decomposition potential to 4.75 V. Owing to the inhibited oxidative decomposition upon high‐voltage cycling, the filler‐modified PEO enables Li//LiNi0.8Co0.1Mn0.1O2 cells to achieve an outstanding initial capacity of 170 mAh g−1 and maintain 70% capacity retention over 200 cycles at 0.5 C at a high cut‐off voltage of 4.3 V.

Lithium metal batteries (LMBs) are regarded as the "holy grail" of next-generation energy storage systems due to their potential for high energy density. However, uncontrolled lithium dendrite growth on lithium metal anodes leads to poor cycling stability and serious safety risks, hindering their practical deployment. Herein, we design an in situ polymerized POSS-based gel polymer electrolyte (POSS-GPE) that exhibits high ionic conductivity (3.04 mS cm-1 at room temperature), excellent oxidative stability (>4.9 V vs Li+/Li), broad compatibility with diverse electrode materials, and intrinsic flame retardancy. The POSS-GPE establishes an anion-rich solvation environment that promotes the formation of robust, anion-derived electrode-electrolyte interphase on both the cathode and anode, thus mitigating interfacial degradation. As a result, LiNi0.8Co0.1Mn0.1O2|POSS-GPE|Li (50 μm) full cell delivers long-term cycling stability of 500 cycles with 87.3% capacity retention. Furthermore, a 6.08 Ah pouch cell with lean electrolyte (1.40 g Ah-1) achieves a remarkable energy density of 511.2 Wh kg-1 and cycles stably for 70 cycles at 4.6 V, representing the best balance between cycling performance and energy density for polymer-electrolyte-based LMBs. The high-energy-density pouch cells also demonstrate superior safety in nail-penetration tests. This work presents a promising strategy for developing practical high-energy-density and high-safety LMBs.

Lithium metal batteries (LMBs) employing high-voltage cathode present a promising pathway toward high-energy-density energy storage systems. However, critical challenges have hindered their practical application, including lithium dendrite proliferation, unstable solid-electrolyte interphase (SEI), and limited oxidative stability of conventional 1,2-dimethoxyethane (DME)-based electrolytes. Herein, we rationally design a siloxane-based electrolyte system featuring enhanced oxidative stability through solvent molecular engineering. The Si-O bonding in siloxanes demonstrates superior bond energy compared to conventional C-O bonds in DME, which enables remarkable oxidative stability and the compatibility of high-voltage LMBs. Through in-operando Raman spectroscopy and molecular dynamics simulations, we reveal that more FSI- anion coordinates with Li+ to construct the solvation sheath in siloxane-based electrolyte. This unique coordination environment facilitates anion-derived SEI formation dominated by LiF/Li3N inorganic components, effectively suppressing dendrite growth and enhancing interfacial stability. The optimized electrolyte (DMS-3) enables exceptional electrochemical performance: Li||Cu cells achieve a high Coulombic efficiency of 99.4 % for 1000 cycles (0.5 mA cm-2) and 98.8 % for 800 cycles (1.0 mA cm-2). Li||LiNi0.8Co0.1Mn0.1O2 full cell with 89.82 % capacity retention after 500 cycles at 1.0 C. The practical validation using 1.2 Ah Li||LiNi0.8Co0.1Mn0.1O2 pouch cell demonstrated 92.26 % capacity retention after 110 cycles (0.3/0.5 C). This work establishes a molecular design paradigm for electrolyte engineering, providing critical insights for developing high-voltage LMBs.

Composite quasi‐solid‐state electrolytes are pivotal for enabling high‐energy‐density lithium metal batteries (LMBs), yet their practical application is hindered by discontinuous ion transport, poor interfacial stability, and limited high‐voltage endurance. Here, a universal in situ growth strategy is developed to construct a metal‐organic framework (MOF)/polymer composite electrolyte (ZCPSE) with hierarchically ordered ion‐conducting networks. The ultra‐uniform MOF nanoparticles (e.g., ZIF‐8) are anchored onto polymer nanofibers, creating abundant nanopores and Lewis acid sites that synergistically enhance Li⁺ transport and oxidative stability. The resulting ZCPSE exhibits unprecedented ionic conductivity (0.46 mS cm−1 at 25°C), a wide electrochemical window (5.15 V vs. Li/Li+), and exceptional mechanical strength (151.2 MPa, 4× higher than pristine polymer membrane). Theoretical simulations reveal that the 3D continuous MOF/polymer interface facilitates rapid Li+ dissociation and uniform flux distribution, endowing ZCPSE with a high Li+ transference number (0.74) and dendrite‐free Li plating/stripping (2000 h in Li|Li symmetric cells). Practical applicability is demonstrated in Li|LiFePO4 cells (stable cycling at 25°C–100°C) and high‐voltage Li|LiNi0.8Co0.1Mn0.1O2 full cells (4.5 V, 100 cycles with 99.2% capacity retention). This study provides a paradigm for designing MOF‐based hybrid electrolytes with simultaneous ionic, mechanical, and interfacial optimization, paving the way for safe and high‐energy LMBs.

Halide superionic conductors have garnered considerable attention due to their high ionic conductivity, mechanical deformability, and excellent oxidative stability. However, their incompatibility with lithium metal results in a thermodynamically unstable interface that increases interfacial impedance, thereby limiting the performance of halide-based all-solid-state lithium-metal batteries (ASSLBs). In this study, we report the synthesis of a series of iodide-chloride solid electrolytes, Li2ZrCl6-xIx (x = 0-3), designed to enhance the reduction stability of the electrolyte through the high polarizability of I-. The substitution of I- promotes covalent bonding with the central cation, thereby reducing its reduction tendency. The Li/Li2ZrCl4I2/Li symmetric cell exhibits stable cycling for over 6000 h at 0.2 mA cm-2 and withstands high critical current densities up to 6 mA cm-2. Full cells incorporating Li2ZrCl4I2 as the solid electrolyte exhibit enhanced cycling stability and capacity retention. Furthermore, the characterization by XPS and ToF-SIMS revealed the formation of an interfacial passivation layer composed of LiI and LiCl, which effectively stabilized the lithium-metal electrode and inhibited further electrolyte decomposition. These findings highlight the potential of iodide-substituted halide electrolytes in addressing interfacial challenges associated with lithium metal anodes, providing a promising pathway for the practical implementation of high-energy-density ASSLBs.

Carbonate-based electrolytes possess high oxidative stability and solvation ability to Li+ in Li metal batteries (LMBs). However, they face significant challenges under cryogenic temperatures, including the sluggish reaction kinetics, uneven Li deposition, and severe interfacial side reactions, especially under the elevated cutoff voltages. Carboxylates usually have lower viscosity and freezing points. However, they still face low oxidative stability and poor film-forming ability. Herein, we designed an ultralow-temperature electrolyte by using a gamma-butyrolactone (GBL) and isobutyronitrile (iBN) mixed electrolyte to be used in high-voltage LMBs. The result demonstrated that the participation of iBN in the Li+ solvation structure could greatly improve the ion transfer kinetics and oxidation stability of the electrolyte through the interaction of C≡N with transition metal on the cathode. Combined with the lithium nitrate (LiNO3) additive, the tame electrolyte exhibits high interfacial stability at a temperature range of -60 to -20 °C by forming dense and highly ionic conductive interfacial films. The assembled Li||LiNi0.8Co0.1Mn0.1O2 cell delivered a capacity of 88.8 mAh g-1 and retained a 77.2% capacity retention after 450 cycles under -40 °C and a 4.5 V cutoff voltage. Even if the temperature decreased to -50 °C, it could still express a capacity of 89.7 mAh g-1 with a 99% capacity retention for 50 cycles, surpassing most of the works involving carbonate-based electrolytes. Therefore, combining the superiorities of carboxylate and nitrile solvents provides a promising electrolyte design insight for the ultralow-temperature LMBs.

No abstract available

Polymer electrolytes are crucial for advancing safe, high-energy-density lithium batteries. Therefore, such electrolytes must possess stability with high-voltage cathodes and lithium metal, ensuring efficient interfacial contact and high room-temperature ionic conductivity. In this study, we present a novel main-chain fluorinated polymer electrolyte, FEOP, synthesized through cationic ring-opening polymerization. FEOP integrates high oxidative resistance of polytetrafluoroethylene with lithium metal compatibility of polyether, achieving an oxidation potential of up to 5.6 V and an anion-involved solvation structure. The exceptional stability enables NCM811 cells to deliver an impressive cycling life of 2000 cycles at 1 C up to 4.5 V. Furthermore, at ultra-high cut-off voltages of 4.7 and 4.9 V, both NCM811 and LNMO cells demonstrate stable cycling over 700 cycles, marking the longest lifespan for polymer-based batteries under these challenging conditions. Moreover, 4.7 V solid-state lithium metal pouch cells incorporating FEOP exhibit an energy density of 405.3 Wh kg-1 and maintain stable cycling over 70 cycles, while successfully passing industry-standard nail penetration tests. Moreover, FEOP demonstrate excellent compatibility with ultra-high-loading electrode (70 mg cm-2), achieving an exceptional areal capacity of 16.2 mAh cm-2. These results provide a solid foundation for designing practical electrolytes that enable next-generation high-energy-density and high-safety solid-state batteries.

In situ polymerized polyether electrolytes are promising for solid‐state Li metal batteries due to their high ionic conductivity and excellent interfacial contact. However, their practical application is hindered by Li dendrite formation, interfacial degradation, and limited oxidative stability. Herein, we propose an in situ polymerized polyfluorinated crosslinked polyether electrolyte (PDOL‐OFHDBO), synthesized by copolymerizing 1,3‐dioxolane (DOL) with 2,2′‐(2,2,3,3,4,4,5,5‐octafluorohexane‐1,6‐diyl)bis(oxirane) (OFHDBO) as a polyfluorinated crosslinker. The electron‐withdrawing polyfluorinated groups endow PDOL‐OFHDBO with enhanced oxidative stability and interfacial compatibility, while reducing the solvation power of the polymer matrix to promote an anion‐derived inorganic‐rich solid electrolyte interphase for uniform Li deposition. Consequently, PDOL‐OFHDBO exhibits a wide electrochemical stability window (>5.6 V) and enables long‐term stable Li plating/stripping for over 1100 h. Furthermore, Li||LiNi0.8Co0.1Mn0.1O2 (NCM811) full cells utilizing PDOL‐OFHDBO demonstrate outstanding cycling stability with high‐loading cathodes (≈3.8 mAh cm−2) and thin Li anodes (50 µm), achieving capacity retention of 95.5% and 89.1% over 100 cycles at cut‐off voltages of 4.3 and 4.5 V, respectively. Remarkably, Ah‐level Li||NCM811 pouch cells deliver an impressive specific energy of 401.8 Wh kg−1, highlighting their potential for practical solid‐state Li metal batteries.

Heterogeneous multilayered solid-state electrolyte (HMSSE) has been widely explored for their broadened working voltage range and compatibility with electrodes. However, due to the limitations of traditional manufacturing methods such as casting, the interface between electrolyte layers in HMSSE can decrease the ionic conductivity severely. Here, a novel combinatory aerosol jet printing (CAJP) is introduced to fabricate functionally graded solid-state electrolyte (FGSSE) without sharp interface. Owing to the unique ability of CAJP (in-situ mixing and instantaneous tuning of the mixing ratio), FGSSE with smooth microscale compositional gradation is achieved. Electrochemical tests show that FGSSE has excellent oxidative stability exceeding 5.5 V and improved conductivity (>7 times of an analogous HMSSE). By decoupling the total resistance, we show that the resistance from the electrolyte/electrolyte interface of HMSSE is 5.7 times of the total resistance of FGSSE. The Li/FGSSE/NCM622 cell can be stably run for more than 200 cycles along with improved rate performance.

Lithium metal batteries (LMBs), featuring lithium metal anodes (LMAs) paired with high‐voltage cathodes, are promising candidates for achieving energy densities exceeding 500 Wh kg−1. However, their commercialization is hindered by unstable interphases and insufficient Li+ transport kinetics, especially under high‐rate conditions. Here, a hybrid diluent strategy is reported for diluted high‐concentration electrolytes (DHCEs) that decouples Li+ solvation from interfacial stabilization by combining fluorinated aromatics with fluorinated ethers. Fluorinated aromatics promote efficient Li+ desolvation and fast transport, while fluorinated ethers provide high oxidative stability and robust interphase formation. Their combination produces a synergistic solvation environment, simultaneously enhancing ion transport, extending voltage tolerance, and stabilizing electrode–electrolyte interfaces. The tailored electrolyte enables 0.78 Ah Li‐NCM622 pouch cells to achieve over 300 cycles at 0.33C charge/0.66C discharge under practical conditions (Li: 50 µm; NCM622: 20 mg cm−2; electrolyte: 3 g Ah−1). Furthermore, a 2.95 Ah Li‐NCM811 pouch cell demonstrates an energy density of 518 Wh kg−1/985 Wh L−1 and retains over 92% of its initial capacity after 107 cycles at 0.2C charge/1C discharge. This work establishes a scalable and cost‐effective electrolyte design strategy that directly addresses the key failure mechanisms of LMBs, offering a viable pathway toward practical high‐energy and high‐rate applications.

Fluorinated ethers have become promising electrolyte solvent candidates for lithium metal batteries (LMBs) because they are endowed with high oxidative stability and high Coulombic efficiencies of lithium metal stripping/plating. Up to now, most reported fluorinated ether electrolytes are -CF3-based, and the influence of ion solvation in modifying degree of fluorination has not been well-elucidated. In this work, we synthesize a hexacyclic coordinated ether (1-methoxy-3-ethoxypropane, EMP) and its fluorinated ether counterparts with -CH2F (F1EMP), -CHF2 (F2EMP), or -CF3 (F3EMP) as terminal group. With lithium bis(fluorosulfonyl)imide as single salt, the solvation structure, Li-ion transport behavior, lithium deposition kinetics, and high-voltage stability of the electrolytes were systematically studied. Theoretical calculations and spectra reveal the gradually reduced solvating power from nonfluorinated EMP to fully fluorinated F3EMP, which leads to decreased ionic conductivity. In contrast, the weakly solvating fluorinated ethers possess higher Li+ transference number and exchange current density. Overall, partially fluorinated -CHF2 is demonstrated as the desired group. Further full cell testing using high-voltage (4.4 V) and high-loading (3.885 mAh cm-2) LiNi0.8Co0.1Mn0.1O2 cathode demonstrates that F2EMP electrolyte enables 80% capacity retention after 168 cycles under limited Li (50 μm) and lean electrolyte (5 mL Ah-1) conditions and 129 cycles under extremely lean electrolyte (1.8 mL Ah-1) and the anode-free conditions. This work deepens the fundamental understanding on the ion transport and interphase dynamics under various degrees of fluorination and provides a feasible approach toward the design of fluorinated ether electrolytes for practical high-voltage LMBs.

Quasi-solid polymer electrolytes (QSPEs) are considered a promising alternative to liquid electrolytes for high-voltage lithium metal batteries. Herein, we present their properties and performance supported on polyolefin microporous separators. These QSPEs consist of a poly(vinylidene-fluoride-co-hexafluoropropylene) polymer matrix, ethylene carbonate as a plasticizer, and various lithium salt mixtures, including lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(oxalate)borate (LiBOB), and LiNO3 as a solid electrolyte interface-forming additive. They exhibit an ionic conductivity of ca. 1 mS cm-1 at room temperature and excellent resistance against lithium dendrites, attributed to the presence of the tough polyolefin separator. The effect of the lithium salt mixture composition on lithium plating/stripping performance and electrooxidation stability was studied in detail, showing that LiNO3, while having a clear positive effect on the plating/stripping performance, may also adversely affect the oxidative stability of the electrolyte, accelerating the degradation of the cathode/electrolyte interface. QSPEs with binary LiFSI/LiBOB salt mixtures were tested at room temperature in a LiNi0.8Mn0.1Co0.1O2||Li monolayer pouch cell with a cathode area capacity of ca. 2.5 mAh cm-2. This cell delivered an initial capacity close to 200 mAh g-1 at C/20, 150 mAh g-1 at C/1, and 80% capacity retention after 100 cycles at 25 °C. The results demonstrate the viability of supported QSPEs, based on poly(vinylidene-fluoride-co-hexafluoropropylene), ethylene carbonate, LiFSI and LiBOB, for application in high-voltage quasi solid-state lithium metal batteries.

Electrolytes engineering plays a crucial role in determining electrode/electrolyte interfacial chemistry for developing high‐voltage lithium metal batteries (HV‐LMBs). Although great progress has been made on electrolytes for lithium metal anodes, the realization of HV‐LMBs has been severely hindered due to the lack of advanced electrolytes that can simultaneously support a stable Li metal anode and high‐voltage cathode (> 4.6 V vs Li+/Li). Herein, through molecular engineering via strategic monofluorination design, two terminal monofluorinated siloxanes including (2‐fluoroethoxy)trimethylsilane (MFS) and bis(2‐fluoroethoxy)dimethylsilane (F2DEO) are designed and synthesized. Compared with the nonfluorinated counterparts, the monofluorinated siloxane‐based electrolytes not only exhibit higher dielectric constant and higher oxidative stability but also allow weaker solvation ability and better interfacial compatibility. With the “4S” (single salt and single solvent) electrolytes at standard concentration, 1.0 M LiFSI/F2DEO electrolyte endows the stable operation of 590 h in Li||Li symmetric cells and high coulombic efficiency of 99.3% in Li||Cu half cells. Moreover, 4.6 V Li||LiCoO2 full cells achieve a high‐capacity retention of 85.9% after 200 cycles, which may be attributed to the higher oxidative stability of F2DEO and the synergistic effect of FSI− and F2DEO for regulating electrode/electrolyte interphase. This design strategy provides a promising approach for future exploration of advanced electrolytes for HV‐LMBs.

The development of electrolytes that synergistically integrate moderate weak solvation, high oxidation stability, and low molecular weight remains a formidable challenge for lithium (Li) metal batteries (LMBs), as conventional chain-extension strategies often exacerbate ionic conductivity loss or fail to suppress α-hydrogen (α-H) oxidation. Herein, a terminal isomerization strategy is proposed to engineer 1,2-diisopropoxyethane (DIPE), an ether electrolyte featuring isopropyl termini that synergistically regulate steric-electronic effects. The branched isopropoxy groups 1) induce tailored steric hindrance to weaken Li⁺-solvent interaction (38.7% reduction vs DME), promoting anion-dominated inorganic-rich interphases; 2) reduce α-H exposure by 67% compared to linear analogs, elevating oxidative stability; and 3) maintain optimal molecular weight (MW = 136 g mol-1) to ensure favorable ionic conductivity. When formulated into a locally high-concentration electrolyte, DIPE enables Li||Cu half-cells with 99.5% Coulombic efficiency and extends Li||NCM811 cycle life to 500 cycles (77% capacity retention), outperforming both linear (e.g., DBE) and over-branched (DtBE) counterparts. This work establishes terminal-group isomerization as a universal molecular design paradigm to reconcile interfacial stability with ionic transport in high-performance LMBs.

Solvated ionic liquids (SILs) are promising candidates for lithium metal battery (LMB) electrolytes owing to their facile synthesis and high safety. However, the high-voltage stability and ionic conductivity of ether-based SILs are compromised by their chaotic coordination structure, characterized by bulky solvation shells and poor oxidation stability. Here, optimizing electrolyte performance is proposed by incorporating weakly coordinating fluoroethylene carbonate (FEC) and a hydrogen-bond (H-bond)-rich polymer into SILs. FEC occupies the second solvation shell, suppressing large-volume solvation structures and improving ion transfer kinetics, while H-bonds anchor TFSI-, reducing its competitive coordination and suppressing its diffusion. This dual approach inhibits the formation of chaotic structures, leading to the development of a SIL-FEC (SILF) based H-bond gel electrolyte (SFHE) for LMBs, which exhibits high Li+ conductivity and superior oxidative stability. The resulting electrolyte exhibits a high Li+ transference number of 0.65. Furthermore, Li/SFHE/LiNi0.6Co0.2Mn0.2O2 (NCM622) battery can operate stably at a high cut-off voltage of 4.5 V, achieving an impressive capacity retention of ≈80% after 400 cycles at 1C. Additionally, the Li/SFHE/LiFePO4 (LFP) retains 81.8% capacity after 450 cycles at a high rate of 3C at 60 °C. This work provides a strategy for achieving high-voltage LMBs by ordering electrolyte micro-solvation structures.

Electrolytes in Li metal batteries (LMBs) are employed primarily with ether‐ or carbonate‐based, each offering distinct interfacial advantages yet facing critical compatibility challenges. Ether‐based electrolytes exhibit high reductive stability toward Li metal but suffer from oxidative decomposition at high‐voltage cathodes. Conversely, carbonate‐based electrolytes maintain stability at the cathode but promote uneven SEI formation and dendritic lithium growth. Here, a regionally localized electrolyte (RLE) concept—an interface‐specific electrolyte design that spatially separates electrolyte functions is introduced. An ether‐rich electrolyte layer is locally immobilized on the lithium surface via a UV‐curable trimethylolpropane ethoxylate triacrylate (ETPTA) polymer matrix, while the bulk electrolyte remains carbonate‐based, enabling each to perform optimally at its respective interface. By tuning the ETPTA content, a balance between mechanical robustness and ionic mobility was achieved. Both experimental and theoretical analysis confirm that the optimized RLE anode promotes Li + ‐selective transport, effectively suppresses parasitic side reactions, and lowers interfacial overpotential. This leads to a more uniform Li deposition, and markedly improved cycling performance. Moreover, RLE facilitates sustained ion‐transfer stability and the formation of a homogeneous, LiF‐rich SEI layer. Overall, the RLE approach offers a practical electrolyte design framework to harmonize electrode interfaces and enhance the interfacial stability of high‐energy LMBs.

The development of poly(dioxolane) quasi-solid-state electrolytes (PDEs) via in situ polymerization has emerged as a promising strategy for the advancement of high-performance lithium-metal batteries. However, the practical application of linear PDEs in high-voltage lithium metal batteries is currently limited by their electrolyte and electrolyte/electrode interface instability and poor thermal stability. Herein, we present a novel in situ hybrid crosslinked PDOL quasi-solid-state electrolyte (HCPDE), which involves a 3D crosslinked polymer network and a unique high-voltage-resistance electrolyte within the framework. Benefiting from the synergistic effect of the crosslinked network structure and high-voltage-resistance electrolyte, the HCPDE exhibits significantly enhanced oxidative stability while maintaining high ion-conducting properties. The HCPDE exhibits an ionic conductivity of 1.95 × 10-4 S cm-1 at 30 °C, a Li+ transference number of 0.74, and an extended electrochemical stability window of over 4.7 V. Furthermore, the designed HCPDE stabilises the electrolyte/electrode interphase. Exceptional cyclability is demonstrated in both the Li∥Li symmetric cell, with over 1800 hours of operation, and the Li∥LiNi0.83Co0.12Mn0.05O2 (NCM83) cell, which achieves a capacity retention of 91.7% after 200 cycles at 0.5C. The corresponding pouch cell also performs impressively, maintaining 85.7% capacity retention over 150 cycles. This study provides new insights into the development of ether-based quasi-solid-state lithium metal batteries.

In situ polymerized polyether electrolytes offer superior interfacial contact in lithium metal batteries (LMBs) but suffer from insufficient oxidative stability and uncontrollable interfacial reactions at high voltages. Herein, these limitations are addressed through microenvironment regulation, synergistically integrating chain topology control and weakly coordinating chemistry. A novel poly(ester‐alt‐ether) copolymer electrolyte (PMDGE) is synthesized through in situ copolymerization of 4‐methyl‐1, 3‐dioxane and glutaric anhydride. The extended methyl‐branched alkyl chains and weakly coordinating ester groups intrinsically lower the highest occupied molecular orbital (HOMO) energy of the polymer and weaken Li + ‐polymer interactions, significantly promoting anion participation in the Li + solvation sheath. Crucially, this molecular engineering drives the formation of dual inorganic‐rich interphases: a LiF/Li x BO y F z ‐enriched solid electrolyte interphase effectively suppresses dendrites, while a LiF‐dominant cathode electrolyte interphase mitigates oxidative decomposition. Consequently, PMDGE exhibits an expanded electrochemical window (5.2 V), a high lithium‐ion transference number (0.58), and enables ultra‐stable Li plating/stripping (>1200 h). Remarkably, Li|PMDGE|LiFePO 4 cell demonstrates unprecedented cycling stability, retaining 96.3% capacity after 10000 cycles at 2 C. Furthermore, Li|PMDGE|LiCoO 2 cell maintains 80.2% capacity after 1200 cycles at a cut‐off voltage of 4.45 V. This work demonstrates molecular solvation engineering through polymer structure design as a powerful paradigm for designing high‐performance polymer electrolytes in high‐voltage LMBs.

The fluorine‐rich electrode electrolyte interphase, chemically sourced from fluorinated anions and solvents, plays a pivotal role in improving the cycling stability of lithium metal batteries (LMBs) equipped with Ni‐rich cathodes. To prestore fluorine source on cations, here a novel monofluorinated cationic skeleton has been designed and synthesized. Its role is first investigated in the regulation of solvation structure and evolution in both bulk and interface regions. The monofluorinated cation can compete with lithium ions for coordinating electrolyte molecules, which improves the oxidative stability of solvents on the cathode surface and prevents the undesirable transition from the anion‐rich to anion‐deficient structure at the anode interface induced by the interfacial electric field. By leveraging this ionic liquid architecture carrying fluorine in both cation and anion, A localized moderate‐concentration ionic liquid electrolyte (LMCILE) is developed that exhibits exceptional compatibility with lithium metal anodes and superior safety characteristics. LiNi0.8Co0.1Mn0.1O2|LMCILE|Li (4.5 V) cells display excellent cycle stability with a good capacity retention of 82.9% over 950 cycles. The Ni‐rich LiNi0.9Co0.05Mn0.05O2|LMCILE|Li (4.5 V) system also delivers good electrochemical performance with high capacity retention of 91.4% after 300 cycles and 90.3% after 200 cycles, even at 60 °C.

Ether-based electrolytes have been regarded as promising candidates for high-energy-density lithium metal batteries, yet they face significant challenges in maintaining stable cycling under high voltage (>4.3 V) and adapting to extreme environmental conditions. This study proposes an innovative solvent immobilization strategy to enhance the oxidative stability of ether electrolytes and stabilize interfaces with both lithium metal anodes and high-voltage cathodes. A unique "bead string" structure was formed by self-assembly of nitrate anion (NO3-) and long-chain ether solvent, effectively immobilizing solvent molecules in the bulk electrolyte. This structure facilitates the formation of an anion-rich electric double layer (EDL) at a medium electrolyte concentration (1.5 M), leading to the formation of a highly stable, inorganic-dominated passivation layer on the surfaces of both the lithium metal anode and high-voltage cathodes. The optimized electrolyte enables Li || LiCoO2 and Li || NCM811 batteries to achieve exceptional cycling stability (81.8% capacity retention after 1400 cycles at 4.3 V and 73.4% capacity retention after 600 cycles at 4.45 V for Li || LiCoO2; 79.8% capacity retention after 1500 cycles at 4.3 V for Li || NCM811). Moreover, the battery can operate across an ultrawide temperature range of -60 to 70 °C.

Solid-state batteries (SSBs) are gaining considerable attention as the next-generation energy storage technology due to their potential for high energy density, enhanced safety, and long cycle life compared to conventional liquid electrolyte-based batteries1, 2. Among the various types of SSBs, solid polymer-based electrolytes (SPEs) stand out due to their flexibility and processability, which facilitate better electrode-electrolyte contact and enable safer, compact designs3. Notably, polyethylene oxide (PEO)-based electrolytes have emerged as promising candidates due to their ease of fabrication, low cost, and environmental friendliness4. However, the poor high-voltage compatibility of PEO-based SPEs leads to the compromise of the energy density of SSBs5. The primary challenge lies in their intrinsically poor oxidative stability, especially at voltages exceeding 4.2 V6, 7. Additionally, the strong interactions between the ether oxygen (EO) chains in PEO and the high-voltage cathode active materials (e.g. LiNixMnyCo(1-x-y)O2) lead to electrochemical side reactions at the cathode/electrolyte interface, which hampers the capacity of the battery and shortens its cycle life8-11. Overcoming these challenges is crucial to unlocking the potential of PEO-based electrolytes in high-voltage batteries, and consequently, high-energy applications.

Development of solid-state electrolytes (SSEs) with high ionic conductivity, wide electrochemical window and high mechanical strength is the key to realize high-energy-dense solid-state lithium metal batteries. Covalent organic frameworks (COFs) have recently attracted considerable interests as promising SSEs mainly due to their highly tunable molecular structures and ideally well-ordered ion migration channels. Herein, we design and synthesize flexible high-voltage tolerant COF SSE films with holistically oriented channel structure to enable solid-state lithium metal batteries with nickel-rich cathodes (NMC811) for the first time. By rationally introducing lithium-philic groups and electrochemical stable quinolyl aromatic ring linkage, the as-prepared COFs demonstrated large bandgap with ultralow HOMO value (-6.2 eV under vacuum) and the highest oxidative stability up to 5.6 V (versus Li + /Li) among all the COF SSEs. Upon convenient mechanical assembly under pre-heat treatment, the obtained flexible COF SSE thin films showed holistically oriented arrangement along the (001) facet with remarkable ionic conductivity up to 1.5 × 10 -4 S cm -1 at 60 °C, and excellent mechanical strength with a high Young's modulus of 10.5 GPa. The lithium ions transmission in this COF SSE was revealed to exhibit directional hopping paths and fast drift velocity by molecular dynamic simulations. With such multiple features, we employed this COF SSE film to assemble all-solid-state lithium-metal batteries with NMC811 cathode, which demonstrated stable cycling performance over 400 cycles, high Coulombic efficiencies (>99%) and could also withstand abuse test such as folding.