用于锂金属固态电池的聚合物电解质锂盐研究进展

固态电池由于具备高的理论能量密度和高安全性，被视为下一代储能技术重要发展方向。固态电解质是固态电池关键组成部分，其性能直接影响了固态电池的发展。离子液体基固态电解质具备高的离子电导率、高的化学稳定性和良好的机械性能，在固态电池领域具备巨大的潜力。本文重点论述了离子液体基固态电解质的研究进展，对离子液体基固态电解质的类型进行归纳总结，并详细介绍了其在固态锂电池、固态钠电池、固态超级电容器三种储能技术中的应用优势。最后，对离子液体基固态电解质的研究方向进行了展望。

固–固界面接触阻抗是固态电解质(含准固态体系)实用化进程中始终面临的严峻挑战。在此背景下，原位聚合技术制备凝胶聚合物电解质因其独特的“液态浸润–固态稳定”转化特性，成为突破界面技术瓶颈的有效手段。本研究采用原位聚合的方法，制备了聚乙二醇二甲基丙烯酸酯(PEGDMA)凝胶聚合物准固态电解质，通过系统调控聚合物单体含量(5~20 wt%)，构建了浓度梯度聚合物电解质，并深入揭示了组分–结构–性能的构效关系。实验结果表明，当聚合物单体含量为10 wt%时，电解质呈现出最优性质：热分解温度达215℃，拉伸强度提升至15.62 MPa，离子电导率高达1.28 × 10−3 S cm−1 (较液态体系提升15.3%)。同时，活化能降低至0.064 eV，锂离子迁移数提高至0.43，在Li||Li对称电池测试中展现出优异的界面稳定性(临界电流密度达2 mA cm−2)。基于该电解质构建的Li||LiFePO4全电池体系在0.5 C倍率下首圈放电比容量达160 mAh g−1，经300次循环后容量保持率高达96.8%。本研究通过原位聚合策略成功制备了具有高离子传导与机械稳定性的凝胶聚合物电解质，证实了其在高安全、高能量密度、长循环寿命准固态电池中的应用潜力。

钠超离子导体(NASICON)型Li1.3Al0.3Ti1.7(PO4)3 (LATP)由于其高的锂离子电导率、对空气的高稳定性和低成本而成为最有前途的固态电解质之一。然而，由于其与锂金属的高度不相容性，LATP的应用并不广泛。在此，提出了一种简单且方便的涂层方法在LATP上构建氧化锌聚合物电解质层(PEO-ZnO|LATP)，除了保护LATP外，该界面PEO-ZnO层还能够提高Li离子迁移数，降低Li|LATP界面阻抗，与PEO|LATP相比，引入1 wt.% ZnO的Li|PEO-1ZnO|LATP|PEO-1ZnO|Li对称电池在0.1 mA∙cm−2电流密度下能够稳定循环700 h，而Li|PEO|LATP|PEO|Li对称电池在0.1 mA∙cm−2电流密度下仅循环520 h。组装的全电池LiFePO4|LATP|PEO-1ZnO|Li固态电池在0.1 C倍率下提供154.3 mAh∙g−1的比容量，200圈循环后容量保持率为87%。本研究提供了一种简便的涂层策略来解决Li|LATP界面副反应问题，并开辟了在固态锂金属电池中应用的可能性。

固态锂离子电池以其高的理论比容量与宽的电化学窗口成为替代传统液态锂离子电池的主要研究方向。NASICON型的LATP作为固态电解质中研究较为广泛的种类，其与锂金属电极间的副反应问题制约着LATP未来的发展。本文通过掺杂LiTFSI的环氧树脂粘结剂表面渗透修复LATP固态电解质表面孔隙，环氧树脂的填充有效减少了Li|LATP界面间的接触面积，延缓了Li|LATP界面间的副反应，LiTFSI的掺杂使环氧树脂粘结剂具有一定的离子导电性，增强了电池的长循环性能。改性后的对称电池在0.1 mA cm−2电流密度下循环超过130 h。在Li|LATP界面间加入PEO凝胶缓冲层后，在0.1 mA cm−2电流密度下稳定循环超过1800 h，全电池稳定循环200次，容量保持率为89%，库伦效率约为100%。

复合固态电解质因其兼具一定的柔性与机械强度，能够发挥无机固态电解质与有机固态电解质各自的优点使得整体性能得到提升，且可以通过调节各组分的比例使其具备不同的性能。然而，仅靠调节各组分的比例得到的浓度单一的复合固态电解质难以同时满足复合电解质对于负极|电解质与正极|电解质界面的不同需求。因此，为克服单一浓度复合固态电解质存在的局限性，本文通过简单的堆叠与热压工艺，合成得到了无机填料具有浓度梯度分布的PEO-LLZTO-LATP复合固态电解质(GCSE-20LLZTO-50-70LATP)，使复合电解质两侧具备不同的电化学性能以分别满足与负极和正极的不同界面需求。梯度结构的设计使复合电解质实现了低无机填料含量的负极侧与Li金属良好的界面接触以及较高的离子电导率(1.01 × 10−4 S∙cm−1)，LLZTO在负极侧的采用确保了与Li负极良好的化学相容性，同时高无机填料含量的正极侧提供了良好的枝晶抑制能力，采用电化学稳定性相对更高的LATP作为正极侧的无机填料进一步有效地提升了复合电解质的电化学窗口(5.0 V vs. Li/Li )。GCSE-20LLZTO-50-70LATP能够在0.1 mA·cm−2和50℃下稳定锂剥/镀循环超过1900 h。组装的Li|GCSE-20LLZTO-50-70LATP|LFP全电池在0.1 C电流密度下的放电比容量为157.3 mAh∙g−1，进行70次循环后容量保持率为90.1%。

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The deployment of lithium metal anode in solid-state batteries with polymer electrolytes has been recognized as a promising approach to achieving high-energy-density technologies. However, the practical application of the polymer electrolytes is currently constrained by various challenges, including low ionic conductivity, inadequate electrochemical window, and poor interface stability. To address these issues, a novel eutectic-based polymer electrolyte consisting of succinonitrile (SN) and poly (ethylene glycol) methyl ether acrylate (PEGMEA) is developed. The research results demonstrate that the interactions between SN and PEGMEA promote the dissociation of the lithium difluoro(oxalato) borate (LiDFOB) salt and increase the concentration of free Li+. The well-designed eutectic-based PAN1.2-SPE (PEGMEA: SN=1: 1.2 mass ratio) exhibits high ionic conductivity of 1.30 mS cm-1 at 30 °C and superior interface stability with Li anode. The Li/Li symmetric cell based on PAN1.2-SPE enables long-term plating/stripping at 0.3 and 0.5 mA cm-2, and the Li/ LiFePO4 cell achieves superior long-term cycling stability (capacity retention of 80.3% after 1500 cycles). Moreover, Li/LiFePO4 and Li/LiNi0.6Co0.2Mn0.2O2 pouch cells employing PAN1.2-SPE demonstrate excellent cycling and safety characteristics. This study presents a new pathway for designing high-performance polymer electrolytes and promotes the practical application of high-stable lithium metal batteries.

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As a key component for the future high‐safety lithium batteries, solid polymer electrolyte (SPE) is gaining an attractive momentum toward large‐scale production due to their remarkable compatibility and processability with electrodes. Further, their excellent performance can be improved using the potential use of plasticizers. A deep eutectic solvent (DES) synthesized from choline chloride (ChCl) and citric acid monohydrate (CAM) demonstrates a promising plasticizer to design good SPE membranes along with poly (vinyl alcohol) (PVA). The changes in surface chemistry of PVA‐based membranes, as determined by FTIR spectroscopy, confirms the success of DES‐plasticizing effect, where detected by wavenumber shifting around main functional groups such as OH, CO, and COC. Following this, EIS characterization on electrical properties reveals the role of 30 wt‐% DES in improving the ionic conductivity with the highest ionic conductivity equivalent to 4.66 × 10−4 S cm−1 and the crystallinity index as high as 41.09%. The presence of LiClO4 and DES and significantly reduces mechanical performance, and glass transition of PVA‐based membranes, as characterized by tensile testing and differential thermal analysis/thermogravimetric analysis. Thus, the presence of DES in PVA and LiClO4 matrices could open another window for designing SPE with novel physicochemical properties.

Here, the time dependence of the interfacial resistance for Li/polyethylene oxide (PEO)-Li(CF3SO2)2N (LiTFSI)-LiPF6/LiCoO2 cells was measured to investigate the stabilization effect of LiPF6 on the interface between a solid polymer electrolyte (SPE) and a 4-volt class cathode, LiCoO2. Impedance measurements under the applied potentials between 4.1 V and 4.4 V vs. Li/Li+ indicated that the addition of LiPF6 to LiTFSI was effective in improving the stability at high potentials such as 4.4 V vs. Li/Li+. In contrast, the resistance of the non-doped PEO-LiTFSI/LiCoO2 interface increased with time under the lower potential of 4.1 V vs. Li/Li+. Fairly good cycle performance was obtained for the LiPF6-doped cell, even at a cut-off voltage of 4.5 V vs. Li/Li+.

Polymer electrolytes offer advantages of leak-proofing, excellent flexibility and high compatibility with lithium metal, enabling high safe operation of lithium metal batteries (LMBs). However, most of present polymer electrolytes do...

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Due to the unique safety qualities, solid composite polymer electrolyte (SCPE) has achieved considerable attentions to fabricate high energy density lithium metal batteries, but its overall performance still has to be improved. Herein, we develop a high lithium salt content poly(vinylidene fluoride) (PVDF) based SCPE enhanced by hexagonal boron nitride (h-BN) nanosheets, presenting perfect electrochemical performance, fast ion transport and efficient inhibition of lithium dendrite growth. The optimized SCPE (PVDF-L70-B5) could deliver high ionic conductivity (2.98 × 10-4 S cm-1), ultra-high Li+ ion transfer number (0.62), wide electrochemical stability window (5.24 V) and strong mechanical strength (3.45 MPa) at room temperature. Density functional theory (DFT) calculation further confirms that the presence of h-BN could promote the dissociation of LiTFSI and the rapid transfer of Li+ ions. As a result, the assembled symmetric Li/Li battery and asymmetric Li/LiFePO4 battery using PVDF-L70-B5 SCPEs both exhibit high reversible capacity, long-term cycle stability and high-rate performance when cycled at 60 oC or 30 oC. Our designed SCPEs will open up a new route to synthesize solid-state lithium batteries with high energy density and high safety.

The deployment of safe and high‐energy density lithium metal polymer batteries (LMPBs) still requires further advances in the quest for new solid polymer electrolytes (SPEs). In this regard, salt anions have a decisive role in the overall SPE performance. While lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was chosen earlier to have a highly flexible sulfonimide center and an extensively delocalized negative charge, it still suffers from several drawbacks ascribed to its poor interfacial compatibility with the lithium metal (LiM) anode and the fact that it is a PFAS. In this work, a novel lithium salt is cunningly designed, aiming to combine the advantages of previously reported lithium bis(fluorosulfonyl)imide (LiFSI) and lithium bis(difluoromethanesulfonyl)imide (LiDFSI) to overcome the limitations of the state‐of‐the‐art SPE based on LiTFSI/poly(ethylene oxide) (PEO). The SPE containing the developed (difluoromethanesulfonyl)(fluorosulfonyl)imide (LiDFFSI) salt presented reduced interfacial resistance and improved compatibility with the lithium metal (LiM) anode compared with LiTFSI/PEO, enabled by the formation of a stable, uniform, and ionically conductive solid–electrolyte interphase (SEI). In addition, LiDFFSI‐based SPEs demonstrated a prolonged cycling stability, achieving over 125 cycles at C/10 with minimal capacity fading in LiM||LiFePO4 cell configuration. These findings evidence how a rational design of the lithium salt chemistry allows tuning the formed SEI, directly impacting the overall SPE performance. Thus, LiDFFSI is presented as a promising alternative lithium salt to improve electrochemical performance and interfacial stability in next‐generation LiM batteries.

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The phase separation between solvents and polymers during the processing leads to the porous structure of PVDF electrolyte, resulting in uneven distribution of ion channels, accelerating the growth of lithium dendrites. Moreover, the various crystal structures of PVDF hinder the migration of Li+, setting obstacles for the improvement of ion conductivity. Here, an amorphous polymer system (BPE) with excellent lithium salt affinity is introduced into the PVDF electrolyte as a bridge to eliminate phase separation structures. The porous structure of PVDF electrolyte is densified by utilizing the amorphous properties of BPE and its affinity for PVDF and lithium salt, thus homogenizing the distribution of ion channels. Furthermore, BPE inhibited the crystallization of PVDF, improving the Li+ conductivity of the polymer electrolyte. The obtained polymer electrolyte system (BPLE) has high ionic conductivity (1.6 × 10−3 S cm−1) and Li+ transference number (0.66) at room temperature. The LiFePO4||Li cell assembled with BPLE‐1 achieved an initial capacity of 149 mAh g−1 and a capacity retention rate of 98% (1C, 500 cycles, RT). At a current density of 2C, the LiFePO4||Li battery achieved a specific capacity of 142 mAh g−1 and the capacity retention rate exceeds 84% after 800 cycles.

Constructing solid polymer electrolytes for fast‐charging solid‐state lithium batteries is essential but extremely challenging due to the poor ionic conductivity and large interfacial impedance. Herein, a coordinated Li+ transport network solid polymer electrolyte linked by weak bonding is designed and fabricated, featuring a high ionic conductivity of 1.14 × 10−3 S cm−1 at 30 °C and a broad electrochemical window of 4.82 V. The weak interaction of carboxyl‐functionalized ionic liquid and metal–organic framework with polymers constructs a fast ion migration path and facilitates the dissociation of lithium salt to obtain more free Li+ ions, which is beneficial for fast‐charging ability. Thus, remarkable rate capability and cycling performance are obtained with a specific capacity of 96.2 mAh g−1 at 6 C even after more than 500 cycles and capacity retention as high as 98.9% in solid‐state LiFePO4||Li cells. Such a fast‐charging capability outperforms many recent reports and can be attributed to the local inter‐radical interactions of weak bonding in electrolytes and the LiF‐rich solid electrolyte interphase. This work not only confirms the importance of inter‐radical interaction but also provides insights into designing solid‐state electrolytes capable of fast charging.

Lithium metal batteries with composite solid‐state electrolytes are considered a promising approach to breaking through the energy limit of current lithium‐ion batteries. However, the low ionic conductivity of polymer electrolytes at room temperature and the stability of the electrode/electrolyte interface have become the major obstacles to the practical application of solid‐state lithium metal batteries. Here, thermoplastic polyurethane is crosslinked with poly(vinylidene fluoride) via hydrogen bonding interactions and combined with Li1+xAlxGe2−x(PO4)3 (LAGP) to form a novel hybrid solid‐state electrolyte (denoted as TPLL). Experimental characterization and theoretical calculations have demonstrated that the rich 3D hydrogen bonding network in TPLL effectively increases the Li─O coordination number and promotes lithium salt dissociation, resulting in a high ionic conductivity of 0.182 mS cm−1 at 25 °C. Moreover, the abundant F groups effectively construct a stable electrode/electrolyte interface, enabling stable cycling of symmetric Li/Li cells for over 600 h at 0.1 mA cm−2 at room temperature. The Li/LiFePO4 full cell assembled with TPLL‐CPE achieves excellent long‐term cycling stability with a decay rate of only 0.016% per cycle at room temperature. This strategy of hydrogen‐bonded crosslinking for salt dissociation opens up a new path for improving the solid‐state electrolytes.

Low room temperature ionic conductivity and interfacial incompatibility are the key factors that hinder the practical application of solid polymer electrolyte (SPEs) in lithium metal batteries. Increasing the ability of the SPEs to dissolve and dissociate lithium salt is helpful to enhance ion transport capacity of the SPEs. Herein, ketone groups with high solubility and dissociation ability of lithium salt are introduced into the structural design of SPE, an aliphatic ketone solid polymer electrolyte (KT@SPE) with crosslinking structure is prepared by ultraviolet (UV) polymerization. The prepared KT@SPE shows excellent viscoelastic and possess room temperature ionic conductivity of 10−4 S cm−1 with 200 wt% lithium bis((trifluoromethyl)sulfonyl)azanide (LiTFSI). Thanks to the contribution of high ion transport capacity, construction of multi‐hydrogen bonds network structure of KT@SPE and a wettability of controlling residual dimethyl sulfoxide (DMSO) solvent to the interface, the assembled symmetrical Li cell realizes stable cycling for over 2000 h at 0.15 mA cm−2. Moreover, LiFePO4 cell achieves stable long cycle at 5C and enable Li/KT@SPE3/LiFe0.6Mn0.4PO4 cell operates at 4.4 V. This work not only provides a design strategy for preparing novel solid polymer electrolytes, but also exhibits the excellent application potential of aliphatic ketone‐based polymer electrolyte in solid‐state lithium batteries at high current density and high voltage.

Solid polymer electrolyte (SPE) nowadays becomes the key enablers in building structural framework of better electrolytes for all‐solid‐sate lithium‐ion batteries (ASS LIBs). A main question remains how to wisely improve the conductivity of polysaccharides, thus promoting today's transition from fossil fuels to green energy. Herein, development of conductive carboxymethyl chitosan (CMCh) complex involving the synergistic impact of lithium acetate (LiCH3COO) is proposed. Changes in the surface chemistry of CMCh appear, suggesting a successful functionalization to this chitosan derivative in the presence of LiCH3COO. Following this, SPE containing 20 wt% lithium acetate optimally demonstrates the highest ionic conductivity equivalent to 5.37 × 10−3 S. cm−1. However, salt‐added CMCh has a crystallinity index (Cr.I) of 64.57% and a tensile strength of 4.74 MPa, which is lower than the neat CMCh SPE membrane. The success loading of lithium acetate also results in a rougher surface of CMCh membrane than of its reference. Further, salt‐incorporated CMCh membrane exhibits a reduction in the thermal stability. In addition, eventually, these presented findings underpin potential application of this chitosan derivative for future ASS LIBs.

Polymer electrolyte is a crucial component of solid‐state‐lithium‐ion batteries that role both as separators and electrolytes. The host polymer and lithium salt selection are crucial for producing a solid polymer electrolyte with optimum characteristics. This research aims to study the effect of lithium acetate (LiCH3COO) salt on carboxymethyl cellulose (CMC)‐based solid polymer electrolytes. The LiCH3COO‐complexed CMC solid polymer electrolyte was prepared using the solution casting method with various weight percentages of LiCH3COO, that is, 0%wt, 10%wt, 20%wt, and 30%wt. The ionic conductivity analysis was conducted by using electrochemical impedance spectroscopy (EIS), infrared analysis by Fourier transform infra‐red (FTIR), mechanical analysis, crystallinity degree analysis with X‐ray diffraction (XRD), and thermogravimetry analysis (TGA), differential thermogravimetry (DTG), and differential scanning calorimetry (DSC). The interaction between Li+ ions and CMC enhanced ionic conductivity, decreased mechanical strength, reduced crystallinity degree, and lowered thermal properties. The CMC/LiCH3COO (70/30) SPE was selected as the optimum condition because it exhibited good ionic conductivity and sufficient thermal stability, while it needs a mechanical strength improvement. Molecular dynamics simulations were also performed at the density‐functional tight‐binding (DFTB) level to unravel the molecular mechanism of the Li‐ion hopping in CMC. The CMC/LiCH3COO (70/30) showed the highest electrochemical window as high as 3.5 V. Based on the results, CMC complexed with 30 (%wt) LiCH3COO salt showed high potential as a polymer electrolyte for lithium‐ion battery applications. Fabrication of solid polymer electrolyte based on carboxymethyl cellulose complexed with lithium acetate salt was conducted by simple casting solution method. The 30%wt LiCH3COO into carboxymethyl cellulose (CMC)‐polymer host showed the highest ionic conductivity of 2.47 × 10−5 S cm−1. The 30%wt LiCH3COO‐complexed CMC shows some degradation peaks, they are water evaporation, decomplexation, depolymerization, melting, and completely degraded. The density‐functional tight‐binding method suggests that the Li‐ions hop both in perpendicular and parallel directions of the cellulose layers. The CMC/LiCH3COO (70/30) showed the highest electrochemical window as high as 3.5 V.

Solid polymer electrolytes are promising candidates for solid-state Li metal batteries owing to their favorable rheological properties and interfacial compatibility with cathodes and Li anodes. However, their limited ionic conductivity and low modulus lead to inferior electrochemical performance and dendrite growth. Herein, we developed a composite solid-state electrolyte comprising vermiculite sheets and a poly(vinylidene fluoride) (PVDF) matrix with multivariate distribution and an anisotropic structure. Within this assembly, some vermiculite sheets were suspended in the PVDF matrix to facilitate Li salt dissociation and Li+ transport, while others were tiled on the electrolyte surface, generating a dense, high-modulus Li2SiO3-rich solid electrolyte interphase via in-situ electrochemical reduction, which further improved interfacial kinetics and suppresses dendrite growth. As a result, a high conductivity of 1.38 mS cm-1 was achieved at room temperature, and the solid-state Li||Li cells displayed robust stability over 3000 h. The all solid-state LiNi0.6Co0.2Mn0.2O2||Li full cells delivered a specific capacity of 172 mAh g-1 at 0.2 C and 86% capacity retention after 500 cycles at 0.5 C. Additionally, practical cycle performance at a high loading (4.4 mAh cm-2) was achieved in pouch cells. Overall, multivariate distribution and anisotropic structuring offers a novel perspective for the preparation of high-performance solid-state electrolytes.

Low room temperature ionic conductivity and interfacial incompatibility severely hinder the further application of polymer electrolytes in lithium metal batteries. Here, a novel shear‐oriented (SO) aliphatic ketone‐carbonyl‐based liquid crystal composite solid polymer electrolyte (FL7M3@CSPESO) is prepared by in situ thermal‐polymerization of liquid crystal monomer (FPZ‐LC, FL) and N, N'‐Methylenebisacrylamide (MBA, M) on cellulose nanofiber (CNF) in the presence of triethylene‐glycol‐dimethyl‐ether (G3) and lithium salt (lithium bis(trifluoromethanesulphonyl)imide, LiTFSI). The high polarity of keto‐carbonyl groups improves the dissociation ability of lithium salt. The highly oriented liquid crystals provide rapid ion transport channels. Thus, the FL7M3@CSPESO achieves ionic conductivity of 10−4 S cm−1 and a lithium‐ion transference number (tLi+) of 0.52 at 30 °C. Besides, in situ formed stable interface layer effectively inhibits the growth of lithium dendrites. The assembled Li/FL7M3@CSPESO/Li cells operate stably over 5500 h at 0.05 mA cm−2 (30 °C). Impressively, the assembled Li/FL7M3@CSPESO/NCM811 cells exhibits a long‐term cycle over 1200 h with a capacity retention of 92% under 0.05 C and 4.4 V (−5 °C). This work not only highlights the advantages of the aliphatic keto‐carbonyl groups and highly oriented liquid crystal in improving ion transport capacity, but also provides a design strategy for advanced polymer electrolytes suitable for lower temperature and high‐voltage solid‐state lithium batteries.

The advancement of quasi-solid lithium metal batteries strongly hinges on attaining fast Li+ transport, stable electrode/electrolyte interphases, and high safety. The present study reports a high-continuous Li+ coordination polymer electrolyte composed of a poly(1,3,5-trioxane) (PTXE) skeleton and mixed solvent of triethyl phosphate (TEP) and fluoroethylene carbonate (FEC). The continuous ether chains (-[C-O]n-) in PTXE coordinated with binary solvents and anions of dual lithium salt (TFSI- and DFOB-) optimize the solvent structure and establish rapid Li+ migration, achieving high Li+ conductivity (1.87 mS cm-1 at 25 °C) and Li+ transference number (0.64) prior to the liquid electrolyte. Simultaneously, via the synergistic induction and regulation exerted by polymer chain segments on the coordination of solvents and anions around Li+, phosphorus- and fluorine-rich cathodic and anodic electrolyte interphases are formed. Furthermore, flame-retardant TEP significantly improves the thermal stability at high temperature (60 °C) as well as under harsh mechanical testing. The assembly of a lithium metal battery with high loading mass of LiNi0.6Co0.2Mn0.2O2 (10 mg cm-2) and ultrathin Li (50 μm) exhibits a high capacity retention rate of 87.1% with 120 cycles. Furthermore, a large-capacity pouch cell (7 Ah) with Li||LiNi0.8Co0.1Mn0.1O2 (40 mg cm-2) achieves high reversible capacity (6.58 Ah) with a high energy density of 505 Wh kg-1.

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Solid-state polymer electrolytes (SPEs) are attracted significant attention for their potential to enhance safety and energy density in energy storage systems. However, two major challenges persist, namely low ionic conductivity and interface instability. A composite polymer electrolyte with superior ionic conductivity and interface stability is developed using PVDF-HFP/PAN as the polymer matrix and La2O3 fillers. La atoms on the surface of the La2O3 fillers act as adsorption sites to bind TFSI-, promoting lithium salt dissociation and increasing the concentration of free lithium ions. Simultaneously, the La2O3 fillers enable anchoring with N, N-dimethylformamide (DMF) and mitigate side reactions between DMF and lithium metal. Consequently, the composite polymer electrolyte achieves a high lithium transference number (0.64) and optimal ionic conductivity (0.31 mS cm-1). Besides, the LiFePO4||Li cell achieves excellent capacity retention of 90.92% after 300 cycles at 0.5C under ambient conditions. It also exhibits almost 100% capacity retention after 50 cycles (0.2C) across a temperature range of RT to -10 °C. Similarly, when coupled with LiNi0.8Co0.1Mn0.1O2 cathode, the batteries demonstrate stable cycling (capacity retention > 83% over 180 cycles, 0.5C, 25C). This work offers a promising approach for advancing the construction of high-performance composite polymer electrolytes.

Improving the room temperature ionic conductivity of solid-state polymer electrolytes for lithium batteries is a big challenge. Exploring new composite polymer electrolytes is one of the important solutions. Herein, a new inorganic two-dimensional layered metal boride nanomaterial (MBene) was first applied to the polymer electrolyte. The hyperbranched cross-linking composite polymer electrolyte is prepared by free radical polymerization of double bond modified MBene and hyperbranched ether with double bonds in the presence of PVDF-HFP and lithium salt. c provided by the two-dimensional layered material and the characteristics of adsorbing lithium salt anion. As a result, the room temperature ionic conductivity of DBMBene-DBHPG-PH CPEs reaches 9.35 × 10-4 S cm-1. Combination of ATR-FTIR spectra, XANES spectra, and DFT calculation reveals the influence of MBene on ion transport. Dendrite-free growth with high reversibility can be maintained for more than 2000 h by lithium plating/stripping in lithium symmetric batteries. The solid electrolyte can be adapted to LFP and LMFP, NCM523 high-voltage cathode materials. It is worth mentioning that the assembled pouch cell also can run stably for 150 cycles at 0.1 C, showing higher cycle capacity. This work not only demonstrates a novel MBene-based composite polymer electrolyte and provides an effective strategy to prevent the aggregation of inorganic fillers in polymer electrolyte but also exhibits excellent application prospects of two-dimensional layered MBene material in solid polymer electrolyte for high-energy density solid-state lithium batteries.

Solid polymer electrolytes (SPEs) have great potential to be used in high-safety lithium-ion batteries (LIBs). However, it is still a significant challenge for SPEs to develop high ionic conductivity, high mechanical strength, and good interior interfacial compatibility. In this work, a ketone-based all-solid-state electrolyte (PAD) resulting from allyl acetoacetate (AAA), diacetone acrylamide (DAAM), and poly(ethylene glycol) diacrylate (PEGDA) was prepared by UV-inducing photopolymerization. The abundant ketone groups endow the prepared PAD all-solid-state electrolyte with strong dissociation of lithium salts and weak coordination interactions between ketone groups and Li+. Depending on the unique properties of the ketone groups in the electrolyte system, the prepared polymer electrolytes show a high lithium-ion transference number of 0.87 and a wide electrochemical window of 4.95 V. Furthermore, the PAD electrolyte also exhibits superior viscoelasticity, which is beneficial for good contact with electrodes. As a result, the assembled LFP/PAD/Li cells with PAD electrolytes show good cycle performance and rate performance. Concretely, the all-solid-state symmetric lithium cells with the PAD electrolyte can achieve stable lithium plating and stripping at 0.05 mA cm-2 for over 1000 h at 60 °C. This work highlights the advantages of ketone-based electrolyte as a polymer electrolyte and provides a design method for advanced polymer electrolytes applied in high-performance solid lithium batteries.

Storing energy in rechargeable lithium-ion batteries is essential for a renewable energy supply. Replacing liquid with solid electrolytes in all-solid-state batteries minimizes safety concerns while increasing energy density. This study introduces a solid polymer electrolyte membrane that can be produced in a scalable, one-step process. The polymer blend consisting of the matrix-giving polyacrylonitrile (PAN) and the ion-conducting poly(ethylene oxide) (PEO) with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as the conducting salt is electrospun, ensuring mechanical flexibility and low crystallinity. Flexible, free-standing membranes exhibit fiber retention up to 100 °C, enabling a wide thermal application window above PEO’s melting point. Adjusting the plasticizer ratio, humidity, and drying conditions allows fine-tuning of the membrane’s morphology, porosity, and ionic conductivity, reaching 0.1 mS cm–1 at 328 K. A slight increase in cell pressure from 0.6 to 2.1 MPa decreases porosity and further increases ionic conductivity without affecting the fiber structure, enabling low-pressure utilization. Moreover, variable-temperature 7Li solid-state nuclear magnetic resonance spectroscopy studies of the dry membrane further demonstrated rapid local Li-ion exchange processes with very low activation energies. An electrochemical window between 0 and 4.5 V, and reversible lithium-ion transport, confirmed by galvanostatic cycling, imply the promising application of high-performance electrospun solid polymer electrolytes.

Solid polymer batteries (SPEs) are highly desirable for energy storage because of the urgent need for higher energy density and safer lithium ion batteries (LIBs). In this work, the single-ion lithium salt PAEK50-LiCPSI was synthesized by grafting 3-chloropropanesulfonyl trifluoromethanesulimide lithium (LiCPSI) onto poly(aryl ether ketone)50 (PAEK50). Nanocellulose (NCC), PAEK50-LiCPSI, and poly(vinylidene fluoride) (PVDF-HFP) were compounded to obtain NCC reinforced high-performance nanofiber composite polymer electrolytes (NCC/PAEK/PVDF) through electrospinning, which presented tensile strength of 15.35 MPa, ionic conductivity of 1.13 × 10-4 S cm-1, and Li+ transfer number as high as 0.80 at 25 °C. The assembled LIBs with NCC/PAEK/PVDF illustrated an initial discharge specific capacity of 155.2 mAh g-1 at 0.2C, and the capacity retention rate was close to 93 % after cycling 700 cycles at 25 °C. Furthermore, its initial specific discharge capacity at -20 °C was 103.4 mAh g-1, and can cycle over 300 cycles. The NCC with sulfonic acid group reinforced the mechanical performance, promoted the dissociation of Li+, and synergized with PAEK50-LiCPSI and PVDF-HFP to form a 3D nanofiber ionic bridge network through hydrogen bond, which promoted the more stable and faster Li+ transportation. This work suggested that the NCC/PAEK/PVDF can be a good choice of solid polymer electrolytes (SPE) for the next generation of LIBs, even working at low-temperatures.

Solid polymer electrolytes that combine both a high lithium-ion transference number and mechanical properties at high temperatures are searched for improving the performance of batteries. Here, we show a salt-free all-polymer nanocomposite solid electrolyte for lithium metal batteries that improves the mechanical properties and shows a high lithium-ion transference number. For this purpose, lithium sulfonamide-functionalized poly(methyl methacrylate) nanoparticles (LiNPs) of very small size (20–30 nm) were mixed with poly(ethylene oxide) (PEO). The morphology of all-polymer nanocomposites was first investigated by transmission electron microscopy (TEM), showing a good distribution of nanoparticles (NPs) even at high contents (50 LiNP wt %). The crystallinity of PEO was investigated in detail and decreased with the increasing concentration of LiNPs. The highest ionic conductivity value for the PEO 50 wt % LiNP nanocomposite at 80 °C is 1.1 × 10–5 S cm–1, showing a lithium-ion transference number of 0.68. Using dynamic mechanic thermal analysis (DMTA), it was shown that LiNPs strengthen PEO, and a modulus of ≈108 Pa was obtained at 80 °C for the polymer nanocomposite. The nanocomposite solid electrolyte was stable with respect to lithium in a Li||Li symmetrical cell for 1000 h. In addition, in a full solid-state battery using LiFePO4 as the cathode and lithium metal as the anode, a specific capacity of 150 mAhg–1 with a current density of 0.05 mA cm–2 was achieved.

Tuning the lithium salts’ chemistry is a promising approach to achieve a competitive solid polymer electrolyte (SPE). Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) has been extensively investigated due to its excellent thermal and electrochemical stability. On the other hand, poly(ethylene oxide) (PEO) remains one of the most studied polymer matrices owing to its high solvating power, which promotes lithium salt dissociation. However, the low lithium transference number (T Li+) of LiTFSI/PEO (ca. 0.2) system is a handicap for high-performance SPE, mainly attributed to the high anion diffusion. In this work, a series of five lithium salts were designed by replacing one -CF3 group of LiTFSI with a dialkylamine moiety bearing different alkyl chain lengths. Ion coordination environments between PEO, cations and anions, along with their transport properties, were systematically investigated through experimental and computational approaches. The results demonstrate that anion diffusion can be effectively suppressed by introducing bulky alkyl groups, with the improved T Li+ (ca. 0.5) primarily attributed to steric hindrance rather than long-range interactions between the anion and the PEO matrix.

In response to escalating global demands for sustainable technologies, the development of high-performance, safe, and eco-friendly separators of lithium-ion battery have become imperative. Herein, a novel nanocellulose composite aerogel separator (designated TOCN-LiP) was engineered through non-covalent crosslinking between TEMPO-oxidized cellulose nanofibers (TOCN) and a well-designed hyperbranched polymer lithium salt electrolyte (denoted LiP). The TOCN-LiP separator demonstrated enhanced interfacial compatibility with lithium metal anodes and exhibited comprehensive performance improvements compared with original TOCN separators. Notably, the TOCN-LiP-10 architecture displayed a homogeneous three-dimensional porous structure, coupled with exceptional cycling stability and a lithium-ion transference number of up to 0.71, achieving a discharge capacity of 125.1 mA h g-1 after 100 cycles at 0.5C, whereas Celgard2500 achieved only 75.2 mA h g-1. Furthermore, the TOCN-LiP-10 separator demonstrated excellent thermal stability, maintaining dimensional integrity at 200 °C, along with enhanced safety characteristics absent in commercial separators. By preparing aerogel separators through facile LiP molecular synthesis and its incorporation into TOCN matrix for optimized lithium-ion transport, this work provides an in-depth insight into developing sustainable, safe, and high-performance LIB separators.

All‐solid‐state lithium (Li) metal batteries incorporating solid polymer electrolytes (SPEs) have emerged as promising candidates for next‐generation energy storage technologies due to their theoretically superior energy density and inherent safety. However, due to the limited dissociation of Li salts in SPEs, the native solid electrolyte interphase (SEI) typically manifests insufficient inorganic constituents, leading to sluggish and heterogeneous Li‐ion transport kinetics. Herein, the dissociation of Li salts is significantly enhanced by deep eutectic interaction between 1,3‐dimethylurea (DMU) molecules and lithium bis(trifluoromethanesulphonyl)imide (LiTFSI), which constructs a Li2S and LiF‐rich SEI. The resultant SEI demonstrates remarkably enhanced Li‐ion transport kinetics and stability, enabling an impressive performance of 2900 h in symmetrical cells. Moreover, the all‐solid‐state LiFePO4 | Li cells benefiting from the Li2S and LiF‐rich SEI maintain 80% capacity retention over 700 cycles and demonstrate a high specific capacity of 91 mA h g−1 after 1000 cycles at a high rate of 1.0 C. This study provides a simple and accessible method to enhance the dissociation of Li salt by deep eutectic interactions, which assists in constructing an inorganic‐rich SEI and achieves performance improvement of all‐solid‐state Li metal batteries.

Solid‐state lithium metal batteries equipped with solid polymer electrolytes (SPEs) are recognized as promising energy storage devices due to their excellent safety and good interfacial contact. However, unstable solid electrolyte interphase (SEI) and sluggish Li+ transport kinetics inhibit their practical application. Herein, a bromine‐modified covalent organic framework (Br‐COF) with donor (D)‐acceptor (A) characteristics is designed and incorporated into PVDF‐HFP‐based SPEs to regulate electron density for promoting Li+ migration and high stability LiF‐rich SEI formation to solve these problems. The D and A units of Br‐COF are confined in particular locations to create independent electron‐hole transference channels, achieving rapid electron transfer dynamics, thereby promoting TFSI− decomposition to obtain high LiF content SEI. Meanwhile, the strong electron‐withdrawing Br‐group can adsorb the electron from tetra(p‐amino‐phenyl)porphyrin (TAPP) to create an electron‐rich environment, resulting in the regulation of the Li+ local coordination environment to facilitate Li+ transference. Consequently, Br‐COF@PVDF‐HFP exhibits high ionic conductivity (9.2 × 10−4 S cm−1) and Li+ transference number (0.78). Li|Br‐COF@PVDF‐HFP|Li cells achieve excellent cycling life (3000 h) at 0.1 mA cm−2, and LFP|Br‐COF@PVDF‐HFP|Li and NCM90|Br‐COF@PVDF‐HFP|Li cells can cycle steadily over 2000 cycles and 250 cycles, respectively. This study provides a reference basis for regulating the electron density of PVDF‐HFP‐based SPEs to enhance the performance of solid‐state LMBs.

Reducing the thickness of solid polymer electrolytes can help to enhance the energy density for solid‐state batteries. However, ultrathin electrolytes still face difficulties in preparation methods, mechanical properties, and interface instability. Herein, a free‐standing, scalable, and ultrathin solid polymer electrolyte with a thickness of 10 µm is reported. It is achieved through in situ thermal curing after filling a porous electrospun polyacrylonitrile fiber membrane with poly(ethylene glycol) diacrylate‐based electrolyte. Impressively, it contributes to a high ionic conductivity of 8.8 × 10−4 S cm−1 at room temperature. The membrane can not only provide good mechanical strength but also offer a Li3N‐enriched solid electrolyte interphase, thereby stabilizing the lithium metal anode. The pouch cell pairing the ultrathin electrolyte with Li foil and LiNi0.8Co0.1Mn0.1O2 cathode of high mass loading can realize a gravimetric/volumetric energy density of 380 Wh kg−1 and 936 Wh L−1. This investigation provides new insights into the potential of fiber‐reinforced membranes for high‐performance solid‐state batteries.

Lithium metal batteries (LMBs) with solid polymer electrolytes (SPEs) offer higher energy density and enhance safety compared to the Li‐ion batteries that use a graphite anode and organic electrolytes. However, achieving long cycle life for LMBs while enabling the use of high‐voltage cathodes required the compatibility between cathode‐SPE, rather than focusing solely on the individual components. This study presente a dual‐functional poly(ionic liquid) (PolyIL)‐based material that simultaneously serves as an SPE matrix and a cathode binder, constructing a cathode‐SPE interface with exceptional (electro)chemical compatibility owing to the high ionic conductivity and wide electrochemical stability window. Additionally, a modified cellulose acetate (CA)‐based PolyIL substrate, enriched with C═O and ─OH groups, is designed rationally and incorporated to assist the Li+ migration, leveraging their highly negative charge, and enhancing the mechanical strength of the SPE. Furthermore, an in situ polymerization approach is employed to assemble the cells, improving the physical compatibility at the cathode‐SPE interface. As a result, the Li||LFP cell demonstrate stable cycling beyond 1100 cycles, and the Li||NCM811 cell reliably operates at a high cut‐off voltage of up to 4.8 V.

Solid-state electrolytes based on in situ ring-opening polymerization of 1,3-dioxolane (DOL) have attracted widespread attention in Li metal batteries because of their high interface compatibility. However, its conventional cationic polymerization mechanism frequently results in the formation of long polymer chains during in situ polymerization, thereby impeding Li+ transport. Here, we regulate the ring opening polymerization of DOL by introducing N,N-dimethyltrifluoroacetamide (FDMA), thus avoiding the formation of long polymer chains. Meanwhile, FDMA can derive a stable SEI rich in LiF during electrochemical cycling, improving interface stability and suppressing dendritic Li growth. Therefore, the full battery with LiFePO4 as the cathode can achieve a high capacity retention rate of 83.9% after 400 cycles at a rate of 5.0 C. At -20 °C, the Li∥LiFePO4 full battery can provide a high capacity of 137 mAh g-1. The solvent-induced strategy provides a promising new avenue for designing a solid electrolyte with high temperature resistance.

Solid polymer electrolytes, known for their ease of processing and excellent interfacial contact, play a crucial role in developing high-energy-density lithium metal batteries. To address the limitations of single-function polymer electrolytes such as polyethylene oxide and polyacrylonitrile, it's imperative to develop polymer electrolytes with superior comprehensive performance by incorporating functional organic molecules. In this study, a quasi-solid polymer electrolyte named VAPE is prepared using a multivariate molecular synergistic strategy. This approach integrates vinyl acetate (VAC), acrylonitrile (AN), and trimethylolpropane ethoxylate triacylate (ETPTA) into a full-range, 3D cross-linked network via radical-initiated polymerization. The cross-linked structure and the synergistic effect of multiple functional units accelerate the lithium-ion transport kinetics of VAPE and induce the formation of dense and stable solid-electrolyte interphase and cathode-electrolyte interphase layers. As a result, the assembled Li/VAPE13/Li symmetric cell exhibits stable cycling for over 800 h. Furthermore, the terpolymer electrolyte VAPE13 demonstrates an electrochemical window up to 5.30 V. Therefore, the LiNi0.8Mn0.1Co0.1O2 (NCM811)/VAPE13/Li battery displays excellent cycling stability with 80% capacity retention after 350 cycles at 0.5C. Even at the ultra-high cut-off voltage of 4.7 V, the NCM811/VAPE13/Li battery achieves a capacity retention rate of 84.8% after 100 cycles at 0.2C.

Lithium‐metal batteries (LMBs) are considered one of the most promising next‐generation high‐energy‐density battery systems. However, the leakage problem and fire hazard of commercial liquid electrolytes hinder their practical applications. Herein, a flame‐retardant solid polymer electrolyte (FRSPE) is fabricated by in situ polymerization of methyl methacrylate (MMA), allyl diglycol carbonate (ADC), and flame‐retardant monomer, i.e., diethyl vinyl phosphonate (DEVP), in which the phosphorus is chemically bonded to the polymer matrix to avoid the parasitic reaction between flame‐retardant molecules with lithium (Li) anode. Compared with the previously reported solid polymer electrolytes (SPEs) possessing free phosphorus, significantly increased efficiency of flame‐retardant and improved electrochemical performance can be achieved. With a wide electrochemical window (≈4.4V), high ionic conductivity (1.8 × 10−4 S cm−1), and superior compatibility with Li anode, the assembled Li/FRSPE/LiFePO4 (LFP) cell exhibits stable cycling over a wide temperature range (capacity retention of 70.9%@1000 cycles and 69.1%@200 cycles at 25 and 80 °C, respectively). Furthermore, the high‐voltage full cells, e.g., Li/LiCoO2 (LCO) and Li/LiNi0.8Co0.1Mn0.1O2 (NCM811), with FRSPE also deliver excellent cycling performance. The current design principle with flame‐retardant chemically bonded in the polymer framework can provide a new pathway for developing practical, safe, and stable LMBs.

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.

All‐solid‐state lithium metal batteries (ASSLMBs) hold great promise for the development of next‐generation high‐safety, high‐energy‐density lithium batteries, but still face the challenges of lithium dendrite growth and thickness. Herein, the ultrathin PEO‐based composite solid polymer electrolyte (denoted as PAL) supported by a low‐density self‐supporting aramid nanofiber (ANF) aerogel framework is developed. The ANF aerogel obtained by a novel CO2‐assisted induced self‐assembly method has a well‐designed bilayer structure with double cross‐linking degree. Benefiting from the intermolecular interaction between ANFs and PEO, the PAL achieves an ultrathin thickness (20 µm) with excellent thermal stability and mechanical strength. Meanwhile, due to the modulation of ionic pathways by the functionalized ANF, the PAL achieves uniform lithium deposition without dendrites, resulting in stable long cycling (1400 h) for symmetric cells. Consequently, the Li|PAL|LiFePO4 (LFP) cell has excellent long‐term cycling stability (1 C, >700 cycles, Coulombic efficiency > 99.8%) and fast charge/discharge performance (rate, 10 C). More practically, the Li|PAL|LFP cell achieves an energy density of 180 Wh kg−1 due to the ability to match a high‐loading (8 mg cm−2) cathode. Furthermore, the double‐layer Li|PAL|LFP pouch cell demonstrates excellent flexibility and safety in cycling and abuse tests.

Li metal anodes have high specific capacity and low electrode potential, and have always been considered as one of the most promising anode materials. However, the growth of Li dendrites, unstable solid electrolyte interface layer (SEI), severe side reactions at the Li/electrolyte interface, and infinite volume expansion of the Li anode seriously hinder the practical application of solid-state Li metal batteries (LMBs). Herein, we report a polyurethane elastomer (TPU) material with high elasticity and interfacial stability as a solid polymer electrolyte (SPE) for LMBs. The synergistic effects of its designed soft chain forging (PEO) and hard chain segments (IPDI) can enhance Li ion conductivity, elastic modulus and flexibility of the SPE to settle the challenges of the Li metal anodes. Moreover, Li2S, as a solid-state electrolyte additive, is able to effectively inhibit the occurrence of side reactions at the interface between Li metal and SPE, promote the decomposition of N(CF3SO2)2- and in-situ generation of LiF with low Li+ diffusion barrier and excellent electronic insulation, achieving rapid Li ion transport and uniform Li deposition. As a result, stable cycle of up to 1400 h has been achieved for a Li||TPU-Li2S||Li battery at 0.1 mA/cm2 at 50 ℃, accompanied with a stable cycling performance of 350 h at a higher current density of 0.5 mA/cm2. Finally, the LiFePO4||TPU-Li2S||Li full battery exhibits an excellent cycling performance with a capacity retention rate of 80 % after 500 cycles at 1C. This simple and low-cost strategy provides novel design thoughts for practical application of high-performance SPEs in stable and long-life LMBs.

No abstract available

Flexible solid-state polymer electrolytes (SPEs) enable intimate contact with the electrode and reduce the interfacial impedance for all-solid-state lithium batteries (ASSLBs). However, the low ionic conductivity and poor mechanical strength restrict the development of SPEs. In this work, the chloride superionic conductor Li2ZrCl6 (LZC) is innovatively introduced into the poly(ethylene oxide) (PEO)-based SPE to address these issues since LZC is crucial for improving the ionic conductivity and enhancing the mechanical strength. The as-prepared electrolyte provides a high ionic conductivity of 5.98 × 10-4 S cm-1 at 60 °C and a high Li-ion transference number of 0.44. More importantly, the interaction between LZC and PEO is investigated using FT-IR and Raman spectroscopy, which is conducive to inhibiting the decomposition of PEO and beneficial to the uniform deposition of Li ions. Therefore, a minor polarization voltage of 30 mV is exhibited for the Li||Li cell after cycling for 1000 h. The LiFePO4||Li ASSLB with 1% LZC-added composite electrolyte (CPE-1% LZC) demonstrates excellent cycling performance with a capacity of 145.4 mA h g-1 after 400 cycles at 0.5 C. This work combines the advantages of chloride and polymer electrolytes, exhibiting great potential in the next generation of all-solid-state lithium metal batteries.

Achieving fast ion transport kinetics and high interfacial stability simultaneously is challenging for polymer electrolytes in solid‐state lithium batteries, as the coordination environment optimal for Li+ conduction struggles to generate desirable interphase chemistry. Herein, the adjustable property of organic ligands is exploited in metal–organic frameworks (MOFs) to develop a hierarchical composite electrolyte, incorporating heterogeneous and spatially confined MOF nanofillers into a poly‐1,3‐dioxolane matrix. The defect‐engineered University of Oslo‐66 MOFs (UiO‐66d) with tailored Lewis acidity can separate ion pairs and optimize Li+ migration through weakened solvation effects, thereby enhancing ion conductivity by over sixfold (0.85 mS cm−1@25 °C). At the lithium anode side, a densified University of Oslo‐67 MOFs (UiO‐67) layer with conjugated π electrons facilitates anion participation in the solvation sheath, promoting anion reduction and thereby forming LiF/Li3N‐dominated solid electrolyte interphase for isotropic Li deposition. The as‐assembled Li||LiFePO4 full cell delivers superior cycling stability with 92.7% of capacity retained over 2000 cycles at 2 C. Notably, the developed electrolyte demonstrates excellent compatibility with high‐voltage cathodes, achieving 80% capacity retention with LiNi0.5Co0.2Mn0.3O2 over 630 cycles. This work provides valuable insights into decoupling transport and interfacial challenges in solid‐state lithium batteries, paving the way for advanced battery technologies.

Polyethylene oxide (PEO)-based polymer electrolytes with good flexibility and viscoelasticity, low interfacial resistance, and fabricating cost have caught worldwide attention, but their practical application is still hampered by the instability at high voltages and the ionic conductivity (10-8 to 10-6 S cm-1). Herein, we rational designed defects-abundant Ga2O3 nanobricks as multifunctional filler constructed a PEO-based organic-inorganic electrolyte for lithium metal batteries. Due to the abundant O-defects feature of Ga2O3 filler, this PEO-based composite electrolyte not only broadens electrochemical stability window (over 5.3 V versus Li/Li+) but also in-situ forms a Li-Ga alloy and solid electrolyte interphase (SEI) film during the cycling process causing a rapid diffusion of Li+ ions. The as-prepared electrolyte achieves the effect of stabilizing interfacial with Li metal (without short-circuiting over 500 h at 0.2 mA cm-2) and possesses superior high ionic conductivity. The assembled all-solid-state LiFePO4//Li cells attained a superior cycling performance of 146 mAh g-1 over 100 cycles at 0.5 C. The XPS analysis reveals that Ga2O3 nanobricks can form a Li-Ga alloy layer in situ at the polymer/anode interface. This work shed a light on designing high ionic conductivity lithium alloys in the composite electrolyte to improve the electrochemical properties of PEO-based polymer electrolytes.

Solid‐state lithium‐metal batteries constructed by in‐situ solidification of cyclic ether are considered to be a critical strategy for the next generation of solid‐state batteries with high energy density and safety. However, the poor thermal/electrochemical stability of linear polyethers and severe interfacial reactions limit its further development. Herein, in‐situ ring‐opening hybrid crosslinked polymerization is proposed for organic/inorganic hybrid polymer electrolyte (HCPE) with superior ionic conductivity of 2.22 × 10−3 S cm−1 at 30 °C, ultrahigh Li+ transference number of 0.88, and wide electrochemical stability window of 5.2 V. These allow highly stable lithium stripping/plating cycling for over 1000 h at 1 mA cm−2, which also reveal a well‐defined interfacial stabilization mechanism. Thus, HCPE endows assembled solid‐state lithium‐metal batteries with excellent long‐cycle performance over 600 cycles at 2 C (25 °C) and superior capacity retention of 92.1%. More importantly, the proposed noncombustible HCPE opens up a new frontier to promote the practical application of high safety and high energy density solid‐state batteries via in‐situ solidification.

Ultrathin solid‐polymer‐electrolytes (SPEs) are the most promising alternative substituting for the conventional liquid electrolyte to enable high‐energy‐density, safe lithium‐metal‐batteries (LMBs). Nevertheless, developing ultrathin SPEs with both high ionic conductivity, and strong Li dendrite retardant is still a significant challenge. Here a scalable fabrication of high‐performance ultrathin (≈7.8 µm) polycarbonate‐based electrolyte (UPCE) is proposed via electrolyte structural engineering, phase separation‐derived poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVH) porous scaffold, without use of additional liquid additives. The rational electrolyte structural modulation with 1‐fluoro‐4‐(1‐methylethenyl)benzene (FMB) enables a weakened Li+‐polymer interaction due to weak Li+ solvation with fluorine, benzene ring, facilitates the formation of LiF‐rich solid‐electrolyte‐interphase on Li metal surface. As a result, the designed UPCE delivers a high ionic conductivity of 4.8 × 10−4 S cm−1, an ultrahigh critical current density of 11.5 mA cm−2 at 25 °C. The solid‐state Li symmetric cell attains unprecedented ultralong cycling over 6000 h at 0.5 mA cm−2. Furthermore, the Li|LiCoO2 cell cycles stably over 1500 cycles at a high operating voltage of 4.5 V, and the pouch cell can achieve a high energy density of 495 Wh kg−1 excluding the packaging. This work offers a new pathway inspiring efforts to commercialize ultrathin SPEs for high‐energy solid‐state LMBs.

All-solid-state batteries are appealing electrochemical energy storage devices because of their high energy content and safety. However, their practical development is hindered by inadequate cycling performances due to poor reaction reversibility, electrolyte thickening and electrode passivation. Here, to circumvent these issues, we propose a fluorination strategy for the positive electrode and solid polymeric electrolyte. We develop thin laminated all-solid-state Li||FeF3 lab-scale cells capable of delivering an initial specific discharge capacity of about 600 mAh/g at 700 mA/g and a final capacity of about 200 mAh/g after 900 cycles at 60 °C. We demonstrate that the polymer electrolyte containing AlF3 particles enables a Li-ion transference number of 0.67 at 60 °C. The fluorinated polymeric solid electrolyte favours the formation of ionically conductive components in the Li metal electrode’s solid electrolyte interphase, also hindering dendritic growth. Furthermore, the F-rich solid electrolyte facilitates the Li-ion storage reversibility of the FeF3-based positive electrode and decreases the interfacial resistances and polarizations at both electrodes.

Solid-state lithium (Li) metal batteries (SSLMBs) with high-energy density and high-security are promising for energy storage application and electronic device development. However, Li dendrite generation is still one of the most important factors hindering the application of SSLMBs since interface contact degradation, dead Li accumulation, and continuous solid-electrolyte interphase (SEI) growth are always caused by Li dendrite growth, making the performances of SSLMBs deteriorate rapidly. In this study, a poly(ether block amide) (PEBA) based polymer electrolyte with lithium bis-(trifluoromethanesulfonyl)imide (LiTFSI) as the Li salt is developed. It is found that the PEBA 2533-20% LiTFSI electrolyte possesses an ion conductivity of 3.0 × 10-5 S cm-1 at 25 °C. Especially, the Li dendrite suppression ability of SEI is greatly enhanced since it provides abundant amide groups to activate TFSI- anions and further enriches lithium fluoride (LiF) content in the SEI layer, which endows the full-cell with enhanced cyclability. As a result, the fabricated solid-state Li/PEBA 2533-20% LiTFSI/LiFePO4 (areal capacity: 0.15 mAh cm-2) battery remains 94% of its maximum capacity (127.5 mAh g-1) at a rate of 0.5C and 60 °C after 200 cycles. In particular, the full cell can cycle for almost 1000 times without short circuit. Therefore, the PEBA based electrolyte could promote the LiF enriched SEI layer into a platform to suppress the growth of Li dendrite toward SSLMBs with a long-life span.

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.

Solid polymer electrolyte (SPE) is quite an attractive candidate for constructing high-voltage Li metal batteries (LMBs) with high energy density and excellent safety. However, sim ultaneous achievement of high-voltage stability against the cathode and good compatibility with the Li anode remains challenging for the current SPE technology. Herein, a dual-layered solid electrolyte (DLSE) consisting of an oxidation-resistant poly(acrylonitrile) (PAN) layer facing a high-potential cathode and a reduction-compatible poly(vinylidene fluoride) (PVDF) layer incorporated by Li6.4La3Zr1.4Ta0.6O12 (LLZTO) nanoparticles and an ionic liquid plasticizer in contact with a Li anode was fabricated. The uniquely designed DLSE holds favorable overall properties in ionic conductivity, Li+ transference number, and mechanical strength. Moreover, the combined advantages of two polymer electrolyte layers greatly address the interface issues on both the cathode and anode. Consequently, the high-voltage LMBs employing the DLSE exhibit excellent room-temperature performances including high rate capacity and long cycle life.

A ternary-salt solid polymer electrolyte (TS-SPE) consisting of LiPF6-LiTFSI-LiFSI salts and poly(1,3-dioxolane) is created by in situ polymerization. The TS-SPE possesses high ionic conductivity, high Li+ ion transference number, and stable SEI with low interfacial impedance, thereby realizing excellent rate performance and long-life stability in Li metal batteries.

Lithium metal batteries are being explored in meeting ever-increasing energy density needs. Because of serious dendritic lithium issues in liquid-state electrolytes, it is generally thought that solid-state electrolytes are the potential alternatives for lithium metal batteries. Herein, we design a new single lithium-ion conducting lithium poly[(cyano)(4-styrenesulfonyl)imide] (LiPCSI) to replace the conventional dual-ion conducting salt in use of solid polymer electrolytes (SPEs) that successfully suppress the growth of lithium dendrites. Owing to highly delocalized anion moiety and oxidation-resistant cyano group, the tailored PEO8-LiPCSI SPE exhibits extremely high Li+ transference number (0.84) as well as oxidation potential (5.53 V vs Li+/Li). The symmetric Li/PEO8-LiPCSI/Li cell runs for 1000 h at 60 °C without short circuit. The rechargeable solid-state Li/PEO8-LiPCSI/LiFePO4 cell discharges a capacity of 141 mAh g-1 with the retention over 85% during 80 cycles. These merits enable the proposed PEO8-LiPCSI SPE very promising for solid-state lithium metal battery applications.

Low‐ionic conductivity within high‐loading cathode has greatly limited the application of solid polymer electrolytes in rechargeable batteries. Herein, solid polymer electrolyte with a three‐dimensionally conducting network is obtained by in situ polymerization of vinyl ethylene carbonate (VEC) with the aid of dipentaerythritol hexaacrylate (DPHA) crosslinker in the solid‐state lithium (Li) metal batteries (LMBs). The weak coordination of Li+ with C═O and C─O groups promotes the dissociation and transport of Li+. The obtained P(VEC–DPHA) electrolyte enables a fast and orderly Li+ transport path and hinders the transport of TFSI−, rendering a remarkable ionic conductivity (2.53 × 10−4 S cm−1), high Li+ transference number (0.47), and wide electrochemical window (5.1 V). A total of 87.38% capacity retention rate of LiNi0.8Co0.1Mn0.1O2||Li is achieved after 200 cycles at 0.2 C. P(VEC–DPHA) can also provide stable cycles under harsh conditions of high rate (1 C), high‐cathode loading (10.83 mg cm−2), and high‐energy‐density pouch cell (421.8 Wh kg−1, cathode loading of 25 mg cm−2). This work provides novel insights for the design of highly conductive polymer electrolytes and high‐energy‐density LMBs.

The development of high-performance solid-polymer electrolytes (SPEs) is a key to the practical application of lithium metal batteries (LMBs). The use of two-dimensional (2D) inorganic nanofiller is an efficient way to build poly(ethylene oxide) (PEO)-based SPEs with high ionic conductivity and stability. Herein, a series of 2D oxygen vacancy-rich Co3O4-y−x (x = 1, 2 and 3) with well-defined 2D nanostructures, a high surface area and controllable oxygen vacancy contents (Co3O4-y) was synthesized via a facile self-assembly method and NaBH4 reduction. When the 2D Co3O4-y−x (x = 1, 2 and 3) nanosheets are introduced as nanofillers in PEO-based SPEs, they can interact with the PEO to form a three-dimensional (3D) PEO/Co3O4-y film with uniform Li+ distribution and vertical diffusion channels, as well as strong adsorption of NO3− from LiNO3 electrolyte salt at the defective sites. As a result, the PEO/Co3O4-y−2 film reached a high ionic conductivity of 4.9 × 10−5 S cm−1, high Li+ a transference number of 0.51 and a wide electrochemical window over 4.6 V at 80 °C. The PEO/Co3O4-y−2 film enables the Li||PEO/Co3O4-y−2||LiFePO4 cell to deliver a high reversible capacity of 117.7 mAh g−1 at 2 C and to maintain 126.7 mAh g−1 at 1 C after 250 cycles with an initial capacity retention of 87.9%.

The integration of metal organic frameworks (MOFs) and electrospun polymer fibers offers the potential to achieve uniform dispersion and high loading of fillers, providing a unique perspective for advancing composite solid electrolytes in solid-state lithium metal batteries. In this work, a composite solid electrolyte is fabricated through a combination of electrospinning and chemical immersion, facilitating the in situ nucleation and growth of HKUST-1 on polyacrylonitrile (PAN) electrospun nanofibers. The in situ coordinated HKUST-1 particles not only modify the solvation structure of Li+ and the coordination environment of TFSI-, but also encapsulate PAN fibers to mitigate interfacial side reactions with lithium metal, thereby improving interfacial stability. Consequently, the solid-state electrolyte achieves a high Li ion transference number of 0.77 and an impressive critical current density of 4.5 mA cm-2. The assembled Li||Li symmetric cell exhibits stable operation for over 4000 h at 4.0 mA cm-2, while Li||LFP and Li||NCM811 cells demonstrate exceptional rate capability and cycling stability. This work provides valuable insights into the design and fabrication of MOF/polymer-based composite solid electrolytes.

Practical application of high energy density lithium–metal batteries (LMBs) has remained elusive over the last several decades due to their unstable and dendritic electrodeposition behavior. Solid polymer electrolytes (SPEs) with sufficient elastic modulus have been shown to attenuate dendrite growth and extend cycle life. Among different polymer architectures, network SPEs have demonstrated promising overall performance in cells using lithium metal anodes. However, fine-tuning network structures to attain adequate lithium electrode interfacial contact and stable electrodeposition behavior at extended cycling remains a challenge. In this work, we designed a series of comb-chain cross-linker-based network SPEs with tunable compliance by introducing free dangling chains into the SPE network. These dangling chains were used to tune the SPE ionic conductivity, ductility, and compliance. Our results demonstrate that increasing network compliance and ductility improves anode-electrolyte interfacial adhesion and reduces voltage hysteresis. SPEs with 56.3 wt % free dangling chain content showed a high Coulombic efficiency of 93.4% and a symmetric cell cycle life 1.9× that of SPEs without free chains. Additionally, the improved anode compliance of these SPEs led to reduced anode-electrolyte interfacial resistance growth and greater capacity retention at 92.8% when cycled at 1C in Li|SPE|LiFePO4 half cells for 275 cycles.

Lithium-metal batteries (LMB) are very attractive owing to their high theoretical energy density, but significant challenges such as low ionic conductivity and safety risks prevent their widespread application. Herein, we report a new design of high-safety all-solid-state LMB by using high-ionic-conductivity thermoresponsive solid-polymer electrolyte (TSPE), providing a smart and active approach to realize thermally induced autonomic shutdown of LMBs by efficiently inhibiting the ionic conduction between electrodes beyond an unsafe temperature. The as-obtained TSPE exhibits a high ionic conductivity (2 × 10-4 S cm-1 at 30 °C), which enables a significantly improved capacity of 160 mA h g-1 at 0.2 C and outstanding high rate capability up to 5 C as well as a super-long cycle life of over 400 cycles for the constructed all-solid-state Li||LiFePO4 batteries. The present study opens up a new avenue for the fabrication of self-protective all-solid-state batteries with inherent intelligent thermal management to ensure battery-series safety.

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Robust structures are essential for extending the application of shapeless soft polymer electrolytes and maintaining the self‐supporting of solid‐state all‐polymer electrolytes (SPEs) at elevated temperatures. Common strategies of introducing additional separators or cross‐linking can significantly increase the manufacturing complexity of SPEs, thus limiting their commercialization. Herein, inspired by the musculoskeletal structure, a “soft‐hard synergy” enhanced SPE (named PPH‐SPE) is successfully designed and manufactured by a simple one‐step in situ microphase separation strategy for high‐temperature lithium–metal batteries. In the bicontinuous PPH‐SPE, the “soft” polyphosphazene liquid polymer electrolyte (PPZ‐LPE) phase provides excellent electrochemical properties, interfacial compatibility, and high‐temperature stable Li3N/Li3PO4‐rich hybrid interfaces. PVDF‐HFP crystals are skillfully used to build a 3D continuous, high‐strength (0.32 ± 0.02 MPa at 90 °C), thermotolerant “hard” skeleton. In the synergy of two phases, Li//Li cell can maintain continuous electrodeposition over 4500 h of the plating/stripping process at 0.25 mA cm−2 and 0.25 mAh cm−2. Furthermore, LiFePO4//Li coin and pouch cells achieve an ultra‐long lifetime of over 1000 (1 C) and 1800 (0.5 C) cycles at 90 °C, respectively. This strategy provides new ideas for large‐scale fabrication and enhancement of solid all‐polymer electrolytes.

The narrow electrochemical stability window (ESW) and poor thermal stability of poly(1,3-dioxolane) (PDOL) solid polymer electrolyte severely restrict its application. In this study, poly(1,3-dioxolane) dimethacrylate (PDOL-DMA) is designed and synthesized to replace the unstable terminal hydroxyl groups with unsaturated C═C double bond. The cross-linked quasi-solid electrolyte (CPDOL-DMA QSE) demonstrates a wide ESW of 4.5 V versus Li+/Li and a high Li+ transference number of 0.64. This crosslinked network facilitates lithium salt dissociation, weakens Li+-polymer interactions, and achieves the reversibility of lithium metal anode disolution/deposition. For CPDOL-DMA QSE, capacity retention is 83% after the 400th cycle at 25 °C. Moreover, it can perform stable cycling with 82% retention after 200 cycles at an elevated temperature of 80 °C. Due to the high oxygen content of the repeating units in CPDOL-DMA, microcalorimetry and accelerated calorimetry results further confirm the high safety of the CPDOL-DMA QSE. This work provides insights into the design of polyether polymer electrolytes with high oxygen contents, realizing thermo-electrochemical stability in lithium metal batteries.

The development of solid electrolyte interfaces (SEI) using lithium and nitrate salts represents a promising approach to enhancing the performance of lithium metal batteries (LMBs). However, the inherent stability of lithium and nitrate salts often results in incomplete decomposition, leading to the formation of inhomogeneous SEI that degrade battery performance. In this study, a strong dipole moment and increased charge transfer strategy are used, which can effectively catalyze the decomposition of NO3 - and TFSI- and accelerate the migration of Li+, as well as the formation of Li3N-LiF-rich SEI. Li/CSEs/LFP batteries demonstrated excellent cycling stability over a wide temperature range (30-100 °C) and across various charge/discharge rates (1C-5C). Notably, pouch cells with high loading of Ni90Co5Mn5 and LFP exhibited remarkable electrochemical performance and safety. This work presents a strong dipole moment and increased charge transfer strategy for optimizing polymer electrolytes, providing new insights into optimizing the performance of LMBs.

Single-ion conducting polymer electrolytes (SICPEs) are designed by covalently bonding anions to the polymers, which is attractive for mitigating anion aggregation-derived polarization. However, one major challenge for developing SICPEs with higher ambient ionic conductivity comes at the expense of structural robustness. Here, boron ion-centered lithium salt (LiT4PAB) with symmetric cross structure and terminal functional C═C was proposed as a units, and then 3D coordination electrolyte (LiPHB) was constructed via chemical cross-linking of LiT4PAB with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). The boron ion-centered units catenated by single bonds show the abundant conformation transitions, enabling the deformable architecture of LiPHB with the aid of electrostatic interactions of diphenylsulfonimide. Therefore, LiPHB undergoes adaptive deformation when subjected to impact, achieving good ductility with elastic moduli of 1.4 GPa and a maximum elongation of 447.4%. Moreover, LiPHB demonstrates 3D single lithium-ion transport channels to guide the homogeneous lithium deposition. As a results, lithium symmetric cells exhibit stable plating/stripping cycle for over 1500 h at 0.1 mA cm-2 at 30 °C. Li/LiPHB SICPEs/NCM811 solid-state batteries deliver a capacity retention of 90.3% in 150 cycles at 30 °C and 0.2 C. Our study shed light on the design strategies of the dynamic single-ion conducting polymer electrolytes for solid-state batteries.

Single-ion conducting polymer blends (SICPBs) have demonstrated exceptional electrochemical performance as solid-state battery electrolytes; however, their nanoscale morphology and thermodynamic behavior remain unexplored. In this work, we investigate blends composed of deuterated poly(ethylene oxide) and poly[lithium sulfonyl(trifluoromethane sulfonyl)imide methacrylate], dPEO/P(LiMTFSI), and report the first experimental study of the nanostructures of charge-neutral polymer blends using small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS). Despite the macroscopic miscibility indicated by a single glass-transition temperature, SANS and SAXS results reveal disordered, charge-correlated nanostructures that are strongly influenced by blend composition and temperature. At low concentrations of charge polymer, the scattering is dominated by concentration fluctuations, and the random phase approximation is applied to extract values of the Flory–Huggins interaction parameter, χSC. At higher charged polymer content, concentration fluctuations are suppressed, and a correlation model is used to characterize the nanostructures of the charge correlations. We find that the structures of the charge correlations are highly dependent on blend compositionconsistent with predictions from Sing’s self-consistent field theory-liquid state models. Understanding these features is essential for uncovering the ion transport mechanism that leads to improved electrochemical performance previously reported in SICPB systems.

Lithium salts of anionic polymers comprising internal anionic, fully saturated boron atoms are presented as single-ion-conducting polymer electrolytes. The linear linkage of BH2+ units by linear, bidentate p-catecolate, benzene-1,4-bis(thiolate), and...

A schematic comparison between a single-ion-conducting polymer and its composite incorporating high-entropy Li-garnet, illustrating simultaneous enhancement in mechanical modulus and ion transport.

The all‐solid‐state single ion conducting polymer electrolyte has a bottleneck in ionic conductivity even though it can prevent concentration polarization. Here, lithium 3,3′‐(diallylammonio)bis(propane‐1‐sulfonyl(trifluoromethyl sulfonyl)imide) (LiDAA(PSI)2) with a symmetrical “one positive, two negative” structure and unsaturated double bonds for propagation, is synthesized. LiDAA(PSI)2 is copolymerized with 1,2‐ethanedithiol and poly(ethylene glycol) diacrylate via photoinitiated thiol‐ene click polymerization and forms a random copolymer, SPZ for short. For comparison, lithium 3‐(diallylamino)propane‐1‐sulfonyl(trifluoromethyl sulfonyl)imide) (LiDAAPSI) and corresponding copolymer SP are synthesized. The 7Li resonance peak position of LiDAA(PSI)2 shifts to a low‐field compared to that of LiDAAPSI, indicating a weaker electrostatic attraction. The symmetrical “one positive, two negative” structure is responsible for the low‐field shift, taking effect of charge conjugation. Unsurprisingly, the ionic conductivity of SPZ is 1.69e‐5 S cm−1 at 60 °C, which is 1.9 times that of SP. Lithium electroplating and stripping at 0.0125 mA cm−2@0.05 mAh cm−2 at 60 °C are performed. An all‐solid‐state single ion conducting lithium metal secondary battery is demonstrated. Zwitterion coupled LiDAA(PSI)2 possesses a symmetrical “one positive, two negative” structure, charge conjugation to weaken electrostatic interaction, and unsaturated double bonds for propagation, which inspires the design and synthesis of single ion conducting polymer electrolytes with zwitterion effect.

Single-ion conducting polymer electrolytes (SICPEs) hold great potential for the next-generation batteries due to their high safety, fast charging capability, and high energy density. However, their practical application is hindered by the low ionic conductivity (IC). The addition of plasticizers has been shown to effectively enhance IC, although the underlying molecular mechanisms remain unclear. In this study, we employed atomistic molecular dynamics simulations to examine the impact of ethylene carbonate (EC) on lithium-ionic conductivity in a modified polyethylene terephthalate (mPET)-based SICPE. Our simulations reproduced experimental IC values and revealed a similar IC trend with varying EC concentrations, including a notable transition at 50 wt % EC. This enhancement in IC appears to be associated with increased EC diffusion and the preferential coordination of the lithium ions with the oxygen atoms in EC. Analysis of the local oxygen coordination environment around lithium ions further explains the IC transition observed at 50 wt % EC. These findings provide insights into the molecular mechanisms by which EC enhances IC in mPET-based SICPEs, primarily through changes in the local oxygen environment surrounding lithium ions. This study contributes to the design of improved SICPEs with plasticizers, supporting advancements in lithium-ion battery technology.

Single-ion conducting (SIC) polymer electrolytes that form dense, ordered ionic domains have attracted considerable attention due to their structured morphology, well-defined lithium-ion conduction pathways, high transference numbers, and ability to suppress dendrite formation. These ionomers exhibit tunable self-assembly into one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) nanostructures, forming ordered ionic domains that facilitate efficient ion transport. Incorporating small amounts of dopants into these structured ionomers has been shown to enhance ionic conductivity. However, the detailed mechanisms by which doping influences nanoscale phase morphology, ionic transport, and electrochemical stability remain poorly understood. In this study, we systematically added controlled amount of poly(ethylene oxide) (PEO) as a dopant to our previously reported ionomer (LiPSC10TFSI), which contains delocalized tethered anions ((trifluoromethanesulfonyl)imide, –TFSI) and forms lamellar ionic domains with liquid crystalline behavior above its glass transition temperature (T g = 62°C). 1 By adding controlled amounts of PEO at various ethylene oxide-to-lithium ion (EO/Li) ratios, we aim to introduce additional lithium-ion solvation sites within these ionic domains. We specifically examined how small variations in the EO/Li ratio impact the nanoscale phase morphology, thermal transition (as probed by differential scanning calorimetry DSC), and consequently, the ion-transport pathways and ionic conductivity. Our results demonstrate that even small amounts of PEO significantly influence the phase behavior of the ionomer, as evident by DSC thermograms. Remarkably, the blended ionomers containing a low PEO content (EO/Li = 2:1) displayed a significantly reduced glass transition temperature (T g = 8°C). The T g further decrease in addition of higher amount of PEO content. This decrease in T g in these ionomer blends indicates increased polymer chain mobility and enhanced local segmental dynamics, facilitating improved lithium-ion transport. Correspondingly, enhanced ionic conductivity was observed in these blended ionomers consistent with the DSC results. Further studies will include morphological characterization using X-ray scattering to further elucidate nanoscale phase morphology and clarify structure-property relationships influencing ionic transport properties and electrochemical stability in these blended ionomer electrolytes. Figure 1

Solid electrolyte interface (SEI) underpins the performance of lithium metal batteries (LMBs). While SEI has been probed to enhance interfacial stability and kinetics, the fast‐charging capability of LMBs remains limited due to the growth of lithium dendrites and polarization at the interface. We have recently identified that ionic artificial SEI plays a crucial role in addressing these challenges, especially when integrating ionic fluoropolymers to optimize interfacial properties. Herein, we systematically studied the fundamental effect of ionic artificial SEI on interfacial kinetics by constructing a single‐ion conducting polymer (P‐SO 3 Li) layer using spin‐coating, and compared it with conventional linear polymers and bare lithium anodes. Molecular simulations revealed that the sulfonic acid groups (‐SO 3 – ) in the P‐SO 3 Li polymer could promote dissociation of Li + owing to electrostatic interactions. Meanwhile, electrochemical experimental results showed that the P‐SO 3 Li polymer coating exhibited a lower desolvation energy barrier than PEO and bare lithium, and it had better dendrite suppression ability, while achieving exchange current densities comparable to bare lithium anodes. Through XPS observation of the lithium anode, it was found that the structure of the P‐SO 3 Li polymer coating remained basically unchanged before and after cycling. Therefore, fast‐charging cycles up to 5 C were successfully achieved, with a Coulombic efficiency of 95.4% and a capacity retention rate of 86.5% after 100 charge‐discharge cycles. In contrast, electrically neutral PEO and bare lithium anodes could only attain Coulombic efficiencies of 93.7% and 90.4%, respectively, along with capacity retention rates of merely 77.9% and 60.6% after 100 cycles. This work informs the fundamental effect of charged interfacial structures underpinning the enhancement of fast‐charging performance in LMBs.

Herein, the synthesis and comprehensive characterization of a new, completely fluorine-free single-ion conducting polymer electrolyte (SIPE) for lithium-metal batteries is reported. For this new SIPE, lithium(4-styrenesulfonyl)(dicyanomethide) has been grafted onto...

Thermal properties, morphology, and ion transport properties of single-ion conducting polymer electrolyte blends based on a side-chain ionomer are investigated.

Composite polymer electrolyte (CPE)-based Li metal batteries have emerged as the most promising candidates for next-generation batteries. However, intrinsic incompatibility between composite phases severely compromises electrolyte performance. Herein, we propose...

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The thermodynamically unstable interface between metallic lithium and electrolyte poses a major problem for the massive commercialization of Li-metal batteries. In this study, we propose the use of a multicomponent protective coating based on cellulose modified with dimethylthexylsilyl group (TDMSC), single-ion conducting polymer P(LiMTFSI), and LiNO3 (TDMSC-P(LiMTFSI)-LiNO3, namely PTL). The coating shows its positive effect by increasing the Coulombic efficiency in Li || Cu cells from 95.9 and 98.6% for bare Li, to >99.3% for Li coated (Li@PTL), with 1 M LiFSI in FEC:DEC and 1 M LiFSI in DME electrolyte, respectively. Symmetrical Li || Li PTL-coated cells exhibit a much more prolonged and stable cycling with a slower increase in overpotential compared to bare Li cells. Li@PTL anodes enable improved cycling of Li@PTL/LFP cells compared to noncoated cells in liquid electrolytes. In this respect, inhibition of high surface area lithium growth is confirmed through postcycling scanning electron microscopy. Remarkably, dendrite-free galvanostatic cycling is demonstrated in laboratory-scale solid-state battery cells assembled with LFP composite cathode (catholyte configuration with PEO + LiTFSI as ionically conducting binder) and a cross-linked PEO-based solid polymer electrolyte. The PTL protective coating enables improved stability of Li metal batteries in combination with smooth transport of Li+ at the electrode–electrolyte interface and homogeneous lithium coating, highlighting its promising prospects in enhancing the performance and safety of lithium metal batteries by properly tuning the synergy between the coating components.

Single lithium-ion conducting polymer electrolytes are promising candidates for next generation safer lithium batteries. In this work, Li+-conducting Nafion membranes have been synthesized by using a novel single-step procedure. The Li-Nafion membranes were characterized by means of small-wide angle X-ray scattering, infrared spectroscopy and thermal analysis, for validating the proposed lithiation method. The obtained membranes were swollen in different organic aprotic solvent mixtures and characterized in terms of ionic conductivity, electrochemical stability window, lithium stripping-deposition ability and their interface properties versus lithium metal. The membrane swollen in ethylene carbonate:propylene carbonate (EC:PC, 1:1 w/w) displays good temperature-activated ionic conductivities (σ ≈ 5.5 × 10–4 S cm−1 at 60 °C) and a more stable Li-electrolyte interface with respect to the other samples. This Li-Nafion membrane was tested in a lithium-metal cell adopting LiFePO4 as cathode material. A specific capacity of 140 mAhg−1, after 50 cycles, was achieved at 30 °C, demonstrating the feasibility of the proposed Li-Nafion membrane.

Single-ion conducting polymer electrolytes are a very promising approach to achieve high-performance solid-state lithium-metal batteries. Herein, a highly conductive, solvent-free polymer electrolyte is designed and synthesized by a unique donor-acceptor...

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Solid polymer electrolytes have yet to achieve the desired ionic conductivity (>1 mS/cm) near room temperature required for many applications. This target implies the need to reduce the effective energy barriers for ion transport in polymer electrolytes to around 20 kJ/mol. In this work, we combine information extracted from existing experimental results with theoretical calculations to provide insights into ion transport in single-ion conductors (SICs) with a focus on lithium ion SICs. Through the analysis of temperature-dependent ionic conductivity data obtained from the literature, we evaluate different methods of extracting energy barriers for lithium transport. The traditional Arrhenius fit to the temperature-dependent ionic conductivity data indicates that the Meyer–Neldel rule holds for SICs. However, the values of the fitting parameters remain unphysical. Our modified approach based on recent work (Macromolecules2023,56, 15, 6051), which incorporates a fixed pre-exponential factor, reveals that the energy barriers exhibit temperature dependence over a wide range of temperatures. Using this approach, we identify anions leading to the energy barriers <30 kJ/mol, which include trifluoromethane sulfonimide (TFSI), fluoromethane sulfonimide (FSI), and boron-based organic anions. In our efforts to design the next generation of anions, which can exhibit the energy barriers <20 kJ/mol, we have performed density functional theory (DFT) based calculations to connect the chemical structures of boron-based anions via the binding energy of cation (lithium)-anion pairs with the experimentally derived effective energy barriers for ion hopping. Not only have we identified a correlation between the binding energy and the energy barriers, but we also propose a strategy to design new boron-based anions by using the correlation. This combined approach involving experiments and theoretical calculations is capable of facilitating the identification of promising new anions, which can exhibit ionic conductivity >1 mS/cm near room temperature, thereby expediting the development of novel superionic single-ion conducting polymer electrolytes.

A single-ion conducting solid polymer electrolyte with enhanced Li+ migration by controlling anion immobilization and solvation was developed, showcasing superior electrochemical performance and industrial compatibility.

Single-ion conducting polymer electrolytes (SIPEs) are among the most promising candidates for high-energy and high-safety lithium-metal batteries. Nevertheless, their commonly limited ionic conductivity and electrochemical stability hamper their practical application. Herein, three new SIPEs, i.e., poly (1,4-phenylene ether ether sulfone)-Li, polysulfone-Li, and hexafluoropolysulfone-Li, all comprising covalently tethered perfluorinated ionic side chains, were designed, synthesized, and comparatively investigated to unveil the influence of the backbone chemistry and the concentration of the ionic group on their electrochemical properties and the eventual cell performance. In particular, the trifluoromethyl group in the backbone and the concentration of the ionic group turn out to play an important role for the charge transport and electrochemical stability towards oxidation. As a result, the combination of both leads to the best-performing SIPE with a high ionic conductivity of ca. 2.5 × 10-4 S cm-1, an anodic stability of >4.8 V, and the best cycling stability in Li‖LiNi0.6Co0.2Mn0.2O2 cells.

In order to enhance the electrochemical performance and mechanical properties of poly(ethylene oxide) (PEO)-based solid polymer electrolytes, composite solid electrolytes (CSE) composed of single-ion conducting polymer-modified SiO2, PEO and lithium salt were prepared and used in lithium-ion batteries in this work. The pyridyl disulfide terminated polymer (py-ss-PLiSSPSI) is synthesized through RAFT polymerization, then grafted onto SiO2 via thiol-disulfide exchange reaction between SiO2-SH and py-ss-PLiSSPSI. The chemical structure, surface morphology and elemental distribution of the as-prepared polymer and the PLiSSPSI-g-SiO2 nanoparticles have been investigated. Moreover, CSEs containing 2, 6, and 10 wt% PLiSSPSI-g-SiO2 nanoparticles (PLi-g-SiCSEs) are fabricated and characterized. The compatibility of the PLiSSPSI-g-SiO2 nanoparticles and the PEO can be effectively improved owing to the excellent dispersibility of the functionalized nanoparticles in the polymer matrix, which promotes the comprehensive performances of PLi-g-SiCSEs. The PLi-g-SiCSE-6 exhibits the highest ionic conductivity (0.22 mS·cm−1) at 60 °C, a large tLi+ of 0.77, a wider electrochemical window of 5.6 V and a rather good lithium plating/stripping performance at 60 °C, as well as superior mechanical properties. Hence, the CSEs containing single-ion conducting polymer modified nanoparticles are promising candidates for all-solid-state lithium-ion batteries.

Among the many approaches to improve the performance of lithium-metal batteries, ternary polyethylene oxide/ionic liquid/lithium salt electrolytes offer several advantages such as low flammability, high conductivity (vs. polyethylene oxide/lithium salt electrolytes) and, to a large extent, limiting the growth of dendrites at moderate currents. However, they suffer from relatively low mechanical strength for lithium metal confinement. Besides, the lithium transport numbers are very low, which is conducive to lithium depletion during plating at high current densities at the lithium/electrolyte interface. Thus, we show here that the combination of a ternary solid polymer electrolyte with a single-ion polymer-based conducting interlayer allows for a significant improvement of the cyclability of the lithium metal anode. This results in a strong improvement of the electrochemical performance of lithium-metal batteries using solid polymer electrolytes at 80 °C, with an 85% capacity retention after 350 cycles (vs. 60% after 62 cycles for the uncoated anode). This is attributed, via focused ion beam-scanning electron microscopy and X-ray photoelectron spectroscopy, to a denser lithium deposit, better contact with the electrolyte and a reduced reactivity of electrolyte species with the interlayer.

Lithium metal batteries (LMBs) are emerging as a crucial breakthrough in energy storage systems due to their lowest electrochemical redox potential at -3.04V (vs. the standard hydrogen electrode) and highest theoretical capacity of 3860 mAh g-1. However, the irregular deposition on the lithium metal anode during the cycles may lead to the formation of lithium dendrites, adversely affecting the safety and performance of LMBs. Furthermore, concentration polarization can cause lithium depletion at the electrode-electrolyte interface, increasing overpotential and thereby accelerating dendrite growth. Single-ion conducting polymer electrolytes (SIPEs), in which the anion is immobilized, possess the ability to mitigate concentration polarization. Herein, we prepared a salt-in-SIPE (SiSIPE) by incorporating a salt additive (LiTFSI) into SIPEs. Spectroscopy analysis (FT-IR and Raman) and density functional theory (DFT) calculations indicated that NMA, a plasticizer that has crystallinity at 25 ℃, can form a solvation structure with LiTFSI. The intermolecular interactions inhibit the SiSIPE from crystallizing even at -80 ℃, ensure high ionic conductivity (7.0×10-4 S cm-1) at 25 ℃, and lead to a high tLi + (0.67) comparable to that of the SIPE (0.71, 2.2×10-4 S cm-1 at 25℃). Additionally, while NMA is easily decomposed above 4.0 V, the interactions ensure that the SiSIPE possesses a wide electrochemical stability window up to 4.4 V. To suppress the decomposition of the electrolyte and achieve stable cycle performance at high voltage, the electrolyte's HOMO level should be lower than that of the cathode. The DFT calculation results showed that the HOMO level of the solvation structure was found to be lower than when NMA forms hydrogen bonds with each other, which implies that it can suppress the decomposition of NMA at high voltages. Additionally, since the solvation structure has a lower LUMO level than NMA, it is preferentially used for forming the solid electrolyte interphase (SEI) layer. As a result, as shown in the X-ray photoelectron spectroscopy results, due to the salt additive, the SiSIPE forms a more stable SEI layer compared to the SIPE. This leads to improved cycle stability in both Li symmetric cell (0.1 mAh cm-2, 700 hours) and LiFePO4 full cell tests (1 C-rate, 400 cycles, 80% retention). The intermolecular design through the salt additive can not only effectively suppress lithium dendrites but also enhance stability at high voltages and improve the cycle performance of LMBs. These strategies could significantly provide a new perspective in achieving high stability and high-performance LMBs. Figure 1

Lithium (Li) metal is one of the most promising anodes for energy-dense batteries as we move towards an electrified economy because of its high theoretical specific capacity (3860 mAh/g). However, Li is highly reactive, leading to continuous consumption of Li and electrolytes and non-uniform Li stripping and plating, which raises safety concerns for traditional liquid electrolytes. Solid polymer electrolytes help to mitigate some of these safety concerns, such as flammability and leaking, as they do not contain flammable organic liquids.1,2 These electrolytes, however, experience concentration polarization, leading to low Li transference numbers (t+).3,4 Single-ion conducting (SIC) polymers are able to overcome this limitation and provide a Li t+ close to unity by immobilizing the anion. However, immobilizing the anion can decrease the ionic conductivity of the polymer. LiF has been shown to interface with other crystalline materials in the solid electrolyte interface (SEI), improving the ionic conductivity of other classes of electrolytes.5 This suggests fluorinating an SIC could improve its ionic conductivity and overall battery performance. In this work, the impact of fluorination on a previously developed SIC polymer membrane with a poly(ethylene oxide) (PEO) backbone was investigated. We compared the effects on the membrane of two different fluorinated ethers: Fluoroethylene carbonate (FEC) and 1,1,2,2-Tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE). This evaluation has thus far comprised a series of techniques, including electrochemical impedance measurements, chronoamperometry, and charge/discharge cycling tests. Preliminary results in Li symmetric cells have shown that although neither fluorinated ether significantly impacts the Li t+, the introduction of both decreases the overall resistance of the cell. Additionally, TTE increased the cycling duration for the cell (at 1 mA/cm2 @70°C), while FEC does not seem to affect cycling duration. References: 1 Liu, K. et al. Molecular Design of a Highly Stable Single-Ion Conducting Polymer Gel Electrolyte. ACS Applied Materials and Interfaces 12, 29162-29172, doi:10.1021/ACSAMI.0C03363/ASSET/IMAGES/MEDIUM/AM0C03363_M002.GIF (2020). 2 Owensby, K. D., Sahore, R., Tsai, W.-Y. & Chen, C. X. Understanding and controlling lithium morphology in solid polymer and gel polymer systems: mechanisms, strategies, and gaps. Material Advances 4, 5867-5881, doi:10.1039/D3MA00274H (2023). 3 Stolz, L. et al. Single-Ion versus Dual-Ion Conducting Electrolytes: The Relevance of Concentration Polarization in Solid-State Batteries. ACS Applied Materials and Interfaces 14, 11559-11566, doi:10.1021/ACSAMI.2C00084/ASSET/IMAGES/LARGE/AM2C00084_0009.JPEG (2022). 4 Gao, J., Wang, C., Han, D. W. & Shin, D. M. Single-ion conducting polymer electrolytes as a key jigsaw piece for next-generation battery applications. Chemical Science 12, 13248-13272, doi:10.1039/D1SC04023E (2021). 5 Wang, Y., Liang, J., Song, X. & Jin, Z. Recent progress in constructing halogenated interfaces for highly stable lithium metal anodes. Energy Storage Materials 54, 732-775, doi:10.1016/J.ENSM.2022.10.054 (2023).

No abstract available

Single-ion conducting polymer electrolytes (SICPEs) are considered as one of the most promising candidates for achieving lithium metal batteries (LMBs). However, the application of traditional SICPEs is hindered by their low ionic conductivity and poor mechanical stability. Herein, a self-standing and flexible polyurethane-based single-ion conductor membrane was prepared via covalent tethering of the trifluoromethanesulfonamide anion to polyurethane, which was synthesized using a facile reaction of diisocyanates with poly(ethylene oxide) and 3,5-diaminobenzoic acid (or 3,5-dihydroxybenzoic acid). The polymer electrolyte exhibited excellent ionic conductivity, mechanical properties, lithium-ion transference number, thermal stability, and a broad electrochemical window because of the bulky anions and unique two-phase structures with lithium-ion nanochannels in the hard domains. Consequently, the plasticized electrolyte membrane showed exceptional stability and reliability in a Li||Li symmetric battery. The assembled LiFePO4||Li battery exhibited an outstanding capacity (∼180 mA h g-1), Coulombic efficiency (>96%), and capacity retention. This research provides a promising polymer electrolyte for high-performance LMBs.

No abstract available

Poly(ethylene oxide) (PEO)-based polymer electrolytes exhibit great potential for application in all-solid-state batteries. However, the insufficient Li+ transport efficiency has hindered the large-scale development of PEO. To address these challenges, we introduced a dual supramolecular interaction strategy for the preparation of PEO-based electrolytes, where tetrafluoroterephthalonitrile (TFTPN) complexes with Li+ and phenylenediboronic acid (PBA) as anion capturer were engaged. Through the synergistic effects of Lewis acid-base interactions between TFTPN and Li+, and hydrogen bonding-derived anchoring for bis(trifluoromethylsulfonyl)imide (TFSI-) anion by boronic acid moieties in PBA, the Li+ transport efficiency was significantly enhanced with ionic conductivity of 6.14 × 10-4 S cm-1 and Li+ transference number of 0.6 at 50 °C (1.01 × 10-4 S cm-1 at 25 °C). PEO-TFTPN-PBA-based cell enabled a maximum discharge specific capacity of 130.7 mAh g-1 at 2 C, and a high retention rate of 81.7% after 200 cycles. This study will provide an effective approach and a synergistic material design strategy for leveraging dynamic supramolecular interactions within PEO-based solid polymer electrolytes.

No abstract available

Composite solid‐state electrolytes (CSEs) using Li1+xAlxTi2‐x(PO4)3 (LATP) as active fillers offer promising prospects for large‐scale lithium metal batteries (LMBs) applications due to their high environmental stability, cost‐effectiveness, and improved safety. However, the challenges persist owing to high interfacial resistance with electrodes and instability with lithium metal. Herein, self‐assembly nanofiber/polymers/LATP composite quasi‐solid electrolytes (SL‐CQSEs) are reported through in situ polymerization of precursor solution containing vinylene carbonate (VC), fluoroethylene carbonate (FEC), lithium bis(trifluoromethanesulfonic) imide (LiTFSI) in a porous and flexible self‐supporting skeleton (SSK) consisting of 2‐(3‐(6‐methyl‐4‐oxo‐1,4‐dihydropyrimidin‐2‐yl)ureido)ethyl methacrylate (UPyMA)’s self‐assembly nanofiber (SAF), poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) and LATP. Anion‐anchoring/hydrogen‐bonding competition and intercomponent multiscale‐coupling effects on SL‐CQSEs are found, which contribute to their incombustibility, excellent room‐temperature ionic conductivity (1.03 mS cm−1), wide electrochemical window (5.1 V), good interfacial compatibility, and lasting inhibition of lithium dendrites. LiFePO4/Li cells with SL‐CQSEs not only exhibit high‐rate performance and long‐term cycling stability, with a capacity retention of 90.4% at 1C and 87% even at 4C after 1000 cycles, but also can resist fire and mechanical abuse, highlighting the potential applications of SL‐CQSEs for high‐performance and safety LMBs.

Although many protocols have been developed to enhance the ionic conductivity and lithium-ion transference numbers of the solid polymer electrolyte, it is still challenging to improve them simultaneously. Herein, we design and prepare boron-doped graphene (BG) as an anion trapper and blend it within a poly(ethylene oxide) (PEO)-based electrolyte. The well-dispersed BG sheets can reduce the crystallinity of PEO and afford numerous Lewis acid sites to effectively accelerate the dissociation of the lithium salt and trap the anions. Thus, the PEO-based electrolytes containing BG sheets exhibit a high ionic conductivity of 9.27 × 10-5 S cm-1 and lithium-ion transference number of 0.57 at 25 °C, which ensure the stable Li stripping/plating over 1000 h. The all-solid-state lithium-ion batteries assembled with the as-prepared electrolyte show excellent rate performance and cycling stability at 25 °C.

The development of solid polymer electrolytes (SPEs) has been significantly impeded by two primary challenges: low ionic conductivity and the inhomogeneous deposition of lithium metal anode. Overcoming these limitations needs to reduce polymer crystallization and to design continuous, stable, fast ion transport pathways. In this study, the incorporation of covalent organic framework colloid (COF-C) as a multifunctional additive to SPEs is proposed, aiming to regulate lithium transport and construct stable electrolyte-electrode interphases. The interaction of COF-C with anions of poly(ionic liquid) (PIL) restricts the growth of PIL spherical crystals and reduces the crystallinity of the electrolyte. Acting as an anion receptor, COF-C promotes uniform Li+ distribution and enhances ion transport kinetics. Additionally, COF-C demonstrates to regulate the anions coordination and create stable solid-state electrolyte interphases between the lithium metal and SPEs. As a result, optimized SPE enables ionic conductivity of 2.70 × 10-4 S cm-1 at 25 °C. The solid-state Li/PIL-COF-C/LiFePO4/ batteries demonstrate exceptional cycle stability, evidenced by a notable discharge specific capacity of 142.4 mAh g-1 at 1 C, along with a commendable capacity retention of 93.1% following 500 cycles. In addition, the PIL-COF-C can be adapted to a higher mass loading of LiFePO4.

All‐solid‐state lithium metal batteries (ASSLMBs) have attracted significant attention due to their high energy density and improved safety performance. However, the application of ASSLMBs in energy storage fields is hindered by their low ionic conductivity, which arises from the limited availability of free Li+ in composite solid‐state electrolytes (CSEs). Herein, a unique nanowire with the 3D cation framework is employed as an inorganic filler to increase the availability of free Li+ with the anion exchange platform. The cation framework with active Cl− can serve as the exchange platform to attract the TFSI−, thereby promoting the dissociation of LiTFSI and the release of additional free Li+. Furthermore, cation framework nanowires exhibit the stable framework structure and highly ordered channels, which form the 1D continuous organic–inorganic interface, facilitating the practical pathways for directional Li+ conduction. As a result, the YBFPL electrolyte exhibits the high ionic conductivity (0.267 mS cm−1) at room temperature, the high Li+ transference number (0.63), and the more mobile Li+ ratio (40%). This study designs the 1D continuous cation framework nanostructure, which realizes the rapid Li+ transport through the anion exchange platform at the organic and inorganic interface.

Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) based electrolyte is a promising alternative to liquid electrolytes in lithium metal batteries. However, its commercial application is limited by high crystallinity and low Li+ ion conductivity. In this study, we synthesized a fluorinated Li-based metal-organic framework (Li-MOF-F) and used it as a filler to address these limitations. The strategy for the Li-MOF-F filler stands out in two main aspects: framework structure for rapid Li+ ion transport and F-functional group with electronegativity. The LiO4 with π-π conjugated dicarboxylate enables the reversible Li intercalation in the lattice structure. The fluorine atoms with electronegativity rearrange polymer matrix from non-polar to polar phase and immobilize TFSI- anions by electrostatic interaction. As a result, the PVDF-HFP electrolyte with Li-MOF-F (LMF-PE) achieves the highest polarity and Li transference number. In Li/Li symmetric cell tests, LMF-PE demonstrates stable Li plating/stripping behavior without dendrites. Additionally, we applied lithium nickel manganese cobalt oxide (NCM) with 94% Ni content as a cathode material for cell test. LMF-PE cell delivers a high initial discharge capacity of 226.9 mAh g-1 and 80% capacity retention after 150 cycles, highlighting its superior cycling performance. These enhancements are attributed to the structural and electrostatic benefits of Li-MOF-F.