全固态电池低压力界面阻抗降低策略

Stresses resulting from electrode material chemomechanics are strongly coupled to solid electrolyte-electrode interface failures. Such failures are significant barriers to realization of practical Li metal solid-state batteries (SSBs). Significant research efforts have been devoted to control anode chemomechanical stress. Here we show positive electrode (cathode) chemomechanical stress is also critical at commercially relevant low (e.g., <1 MPa) stack pressures. Using a series of model textured positive electrodes we provide the experimental evidence of the role of positive electrode lattice strain anisotropy during charge/discharge on positive electrode chemomechanics. Our model systems reveal that positive electrode chemomechanics significantly alter Li metal plating and stripping behavior at low stack pressure. We utilize these learnings to build long cycle-life SSBs with practical areal capacity (5 mAh/cm2) operating under a 1 MPa stack pressure and at room temperature. Our findings highlight the importance of controlling positive electrode chemomechanics to realize low stack pressure SSBs. Solid-state batteries typically require high pressure to operate reliably. Here, the authors show that tuning cathode chemomechanics enables stable lithium metal battery cycling at room temperature and low pressure, eliminating the need for interlayers or elevated temperatures.

All solid‐state lithium (Li) metal batteries (ASSLBs) using ceramic‐polymer hybrid solid electrolytes hold the promise for high‐performance energy storage application, but they still suffer from the interfacial deterioration and dendritic Li penetration issues, particularly under low stack pressures. Therefore, understanding and mastering the underlying chemo‐mechanical failure mechanisms become essential. Herein, the chemo‐mechanical evolutions by operando monitoring the amplitude and heterogeneity of interfacial stress through an embedded optical fiber sensor are revealed. It is found that the uneven stripping/deposition of Li metal induces rapid and non‐uniform stress growth at the interface, deteriorating interfacial contact with the Li‐filament growth. Based on these insights, Li metal is replaced with an architectural lithium‐tin anode, which demonstrates uniform stress and improved performance even under low stack pressure. This work not only offers a quantitative way to operando track the uniformity of interfacial stress but also provides critical insights into mastering the chemo‐mechanics of ASSLBs.

All‐solid‐state batteries (ASSBs) are promising next‐generation energy storage systems that can replace conventional lithium‐ion batteries. Further enhancement in battery performance requires the formation of a stable physical interfacial contact between the active material (AM) in the electrode and the solid electrolyte (SE). However, reducing the resistance at the AM–SE interface remains a key challenge. This study focuses on Li3PS4‐xLiBH4 (LPSBH), a sulfide‐based SE with an argyrodite structure, synthesized by mechanical milling. Although LPSBH is known for its high ionic conductivity, its mechanical properties are not thoroughly examined. Here, the deformability of LPSBH is evaluated by demonstrating that it can be formed at low pressures to achieve high relative density. A quantitative evaluation of the AM–SE interfacial contact using symmetric cells demonstrates the formation of a good AM–SE interfacial contact within the electrode layer. A 13 mAh‐class laminated cell with LPSBH stacked onto the negative electrode achieves 6C charging at 25 °C under a low stacked pressure of 5 MPa, along with significant cycle stability, which retains ≈70% capacity after 1000 cycles under 1C/1C conditions.

All-solid-state batteries (ASSBs) working at room and mild temperature have demonstrated inspiring performances over recent years. However, the kinetic attributes of the interface applicable to the subzero temperatures are still unidentified, restricting the low-temperature interface design and operation. Herein, a host of cathode interfaces are constructed and investigated to unlock the critical interface features required for cryogenic temperatures. The unstable interface between LiNi0.90Co0.05Mn0.05O2 (Ni90) and Li6PS5Cl (LPSC) sulfide solid electrolyte (SE) results in unfavorable cathode-electrolyte interphase (CEI) and sluggish lithium-ion transport across the CEI. After inserting a Li2ZrO3 (LZO) coating layer, the activation energy of the Ni90@LZO/sulfide SE interface can be reduced from 60.19 kJ mol-1 to 41.39 kJ mol-1 owing to the suppressed interfacial reactions. Through replacing the LPSC SE and LZO coating layer by the Li3InCl6 (LIC) halide SE, both a highly stable interface and low activation energy (25.79 kJ mol-1) can be achieved, thus realizing an improved capacity retention (26.9%) at -30 °C for the Ni90/LIC/LPSC/Li-In ASSB. Moreover, theoretical evaluation clarifies that cathode/SE interfaces with high ionic conductivity and low energy barrier are favorable to the Li+ conduction through the interphase and the Li+ transfer across the cathode/interphase interface. These critical understandings may provide guidance for low-temperature interface design in ASSBs.

No abstract available

The formation of interface voids, peculiar to the solid-solid contact between metal anodes and solid electrolytes (SEs), has become a fundamental obstacle for developing practical lithium metal solid-state batteries (SSBs). Addressing this issue requires the operando observation of void evolution with high spatio-temporal resolution and the direct linkage of voids to solid-state electrochemistry. Here, we present such an attempt by visualizing both the stripping and plating interfaces of a micron-sized SSB cycled in galvanostatic mode in a transmission electron microscope. Various voltage responses in the charge/discharge curves are well correlated to the nucleation, growth, and refilling of single voids. Notably, two distinct modes of Li stripping, namely, void-growth stripping and void-free stripping, are experimentally identified. We unveil the roles of stack pressure and current density on void evolutions, which suggests a mechanism of void suppression without involving plastic deformation of Li metal. Furthermore, Li|SE|Li symmetric SSBs enabling repeated void-free cycling without stack pressure are in situ demonstrated.

All‐solid‐state (ASS) Li‐metal batteries are regarded as promising energy‐storage devices due to their high energy density and improved safety. Recently, the interface thermal runaway issues between reactive Li‐metal and solid‐state electrolytes (SSEs) have attracted increasing attention, but it has been less studied. Here, using in situ high‐resolution thermal imaging, a significant stress‐release period before the interface catches fire and burns between Li metal and Li1.5Al0.5Ge1.5(PO4)3 (LAGP) SSE is found that can provide opportunities for early thermal runaway warning for the batteries. Further, a highly safe ASS Li‐metal battery without external pressure package is reported by constructing a stable heterogeneous interface layer (HIL) consisting of ALD‐coated aluminum oxide and PECVD‐deposited amorphous silicon (a‐Si), which significantly reduces the interface exothermic reaction and suppresses the interface thermal runaway both theoretically and experimentally. The ASS Li‐metal symmetric battery shows a long cycling stability both at RT and high temperature over 150 °C being at least 8‐times higher than that of the one without HIL. The assembled Li‐CO2 battery is capable of 100 stable cycles with <3.2 V low charge potential at 500 mAg−1 at 150 °C. This work paves a way for the development of the next‐generation safe and high‐energy lithium batteries.

The dry-process is a sustainable and promising fabrication method for all-solid-state batteries by eliminating solvents. However, a pragmatic fabrication design for thin and robust solid-state electrolyte (SSE) layers has not been established. Herein, we report a dry-process approach that enhances mechanical stability of SSE layers from film fabrication to cell operation. By co-rolling thick SSE and positive electrode feeds, a uniform, thin SSE layer (50 µm) and a high loading positive electrode layer (5 mAh cm−2) with high active material ratio (80 wt%) are simultaneously achieved. This SSE-positive electrode integrated film exhibits enhanced physical properties and cyclability (> 80% retention after 500 cycles) at low stack pressure (2 MPa) compared to the freestanding counterparts, attributed to reinforced and intimate SSE-positive electrode interface constructed during co-rolling process. Additionally, an all-solid-state pouch cell with high stack-level specific energy (310 Wh kg−1) and energy density (805 Wh L−1) operating at 30 °C and 5 MPa is demonstrated. All-solid-state batteries face practical challenges such as sustainable fabrication and low-stack pressure operation. Here, authors develop a modified dry-process technique to yield robust solid electrolyte-electrode interface for practical fabrication and operation of all-solid-state batteries.

Solid‐state lithium batteries may provide increased energy density and improved safety compared with Li‐ion technology. However, in a solid‐state composite cathode, mechanical degradation due to repeated cathode volume changes during cycling may occur, which may be partially mitigated by applying a significant, but often impractical, uniaxial stack pressure. Herein, we compare the behavior of composite electrodes based on Li4Ti5O12 (LTO) (negligible volume change) and Nb2O5 (+4% expansion) cycled at different stack pressures. The initial LTO capacity and retention are not affected by pressure but for Nb2O5, they are significantly lower when a stack pressure of <2 MPa is applied, due to inter‐particle cracking and solid‐solid contact loss because of cyclic volume changes. This work confirms the importance of cathode mechanical stability and the stack pressures for long‐term cyclability for solid‐state batteries. This suggests that low volume‐change cathode materials or a proper buffer layer are required for solid‐state batteries, especially at low stack pressures.

For preparing next‐generation sulfide all‐solid‐state batteries (ASSBs), the solvent‐free manufacturing process has huge potential for the advantages of economic, thick electrode, and avoidance of organic solvents. However, the dominating solvent‐free process is based on the fibrillation of polytetrafluoroethylene, suffering from poor mechanical property and electrochemical instability. Herein, a continuously solvent‐free paradigm of fusion bonding technique is developed. A percolation network of thermoplastic polyamide (TPA) binder with low viscosity in viscous state is constructed with Li6PS5Cl (LPSC) by thermocompression (≤5 MPa), facilitating the formation of ultrathin LPSC film (≤25 µm). This composite sulfide film (CSF) exhibits excellent mechanical properties, ionic conductivity (2.1 mS cm−1), and unique stress‐dissipation to promote interface stabilization. Thick LiNi0.83Co0.11Mn0.06O2 cathode can be prepared by this solvent‐free method and tightly adhered to CSF by interfacial fusion of TPA for integrated battery. This integrated ASSB shows high‐energy‐density feasibility (>2.5 mAh cm−2 after 1400 cycles of 9200 h and run for more than 10 000 h), and energy density of 390 Wh kg−1 and 1020 Wh L−1. More specially, high‐voltage bipolar cell (≥8.5 V) and bulk‐type pouch cell (326 Wh kg−1) are facilely assembled with good cycling performance. This work inspires commercialization of ASSBs by a solvent‐free method and provides beneficial guiding for stable batteries.

As solid‐state batteries (SSBs) emerge as leading contenders for next‐generation energy storage, chemo‐mechanical challenges and instabilities at solid‐solid interfaces remain a critical bottleneck. Ensuring sufficient interfacial contact within composite cathode architectures often requires the application of high stack pressures, posing a significant hurdle in the development of viable, large‐scale SSBs. In this work, the impact of stack pressure is investigated on the performance of solid‐state composite cathodes comprised of single‐crystal LiNi0.5Mn0.3Co0.2O2 (SC‐NMC532) active material particles and a Li6PS5Cl (LPSCl) solid electrolyte phase. By unraveling the complex interplay between stack pressure and microstructure‐dependent mechanisms, the profound influence on interfacial resistances, cathode utilization dynamics, current constriction effects, and lithiation heterogeneities are revealed. Through a comprehensive examination of coupled reaction kinetics and transport interactions at the electrode and particle length scales, the implications of stack pressure at different C‐rates and microstructural arrangements are elucidated, thereby delineating the limiting mechanisms that are prevalent at low stack pressures. This work underscores the critical role of optimizing the cathode microstructure to mitigate the chemo‐mechanical challenges associated with SSB operation at low stack pressures, offering valuable insights and design guidelines for the development of high‐performance SSBs.

Stable operation of all-solid-state lithium-sulfur batteries (ASSLSBs) under reduced external pressures necessitates overcoming critical interfacial challenges and managing substantial electrode volume changes during cycling. This study introduces a carbon primer coating applied to aluminum (Al) current collectors as an effective strategy to enhance interfacial adhesion and reduce delamination at low pressures. The carbon coating provides uniform current distribution across the interface and improves contact conformality, addressing a critical issue for practical pouch cell applications. The interface design was evaluated by laminating dry-processed Li2S composite cathodes onto carbon-coated Al current collectors with varying surface areas. Interfacial resistance and the mechanical robustness of electrode-current collector interfaces under different pressures were systematically characterized using direct current polarization measurements. Advanced imaging methods, including focused ion beam scanning electron microscopy (FIB-SEM) and X-ray computed tomography (CT), were employed to examine interfacial integrity and detect any morphological changes throughout cycling. Furthermore, to manage significant volume variations inherent in ASSLSBs—particularly the 79% volumetric shrinkage of Li2S cathodes and 280% expansion of silicon (Si) anodes during cycling—the research integrates Si anodes with Li2S cathodes. This combination ensures volumetric compensation, significantly enhancing structural stability and cycling performance at reduced pressures. Overall, this interface engineering strategy and electrode design optimization demonstrate significant improvements in both energy density and cycling stability for ASSLSBs. This research provides a scalable solution, highlighting the potential for high-performance, low-pressure-operating pouch cell configurations.

No abstract available

Developing promising substitutes of lithium (Li) metal anode that suffers from a serious interfacial instability against the solid electrolyte (SE) is a formidable challenge for the all‐solid‐state battery. Aluminum (Al), a highly potential candidate owing to its high specific capacity and relatively low working potential, however, cannot withstand stable cycling in all‐solid‐state battery due to the fast structural collapse caused by the solid/solid contact at the Al/SE interface. Herein, a Li spreading layer consisting of metallic nickel (Ni) particles at the Al surface is proposed to raise the performance of Al anode in all‐solid‐state battery. Owing to the immiscibility between Ni and Li solid phases, this Li spreading layer can enable a uniform distribution of Li atoms over the electrode surface followed by a stable Li–Al alloying/dealloying processes, suppressing the stress deformation at the Al/SE interface and significantly improving the cycling performance of Al anode in all‐solid‐state battery. The modified Al anode not only outperforms the bare Al significantly, but also exhibits superior cyclability and rate ability compared with the Li anode. This work provides an efficient strategy to promote the application of Al anode in all‐solid‐state battery, and is expected to be generalized for other alloy anodes.

: The practical application of all-solid-state batteries (ASSBs) requires reliable operation at low pressures, which remains a significant challenge. In this work, we examine the role of a cathode composite microstructure composed of solid-state electrolyte (SSE) with different particle sizes. A composite made of LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) and fine-particle Li 6 PS 5 Cl (LPSC) shows a more uniform distribution of SSE on the surface of NCM811 particles, ensuring intimate contact. Moreover, the composite features reduced tortuosity, which enhances Li ion conduction. These microstructural advantages result in significantly reduced charge transfer resistance, helping to suppress mechanical distortion and electrochemical degradation during cycling under low-pressure conditions. As a result, the fine-LPSC cathode composite exhibits enhanced cycling stability at a moderate stack pressure of 2 MPa, outperforming its coarse-LPSC counterpart. Our finding confirms the important role of microstructure design in enabling high-performance ASSBs operating under low-pressure conditions.

Sulfide-based solid electrolytes (SEs), such as lithium (Li) - argyrodites (e.g., Li 6 PS 5 X, where X = Cl, Br, I), have attracted significant attention among various ceramic SE materials due to their high ionic conductivity (> 10 -3 S/cm) and favorable mechanical properties that support scalable manufacturing of all solid-state Li batteries (SSLBs). Despite its high theoretical capacity and low electrochemical potential, the practical application of Li-metal anode faces significant challenges due to problems such as interfacial instability, including dendrite growth and large volumetric changes. To address these challenges, recent report demonstrated that adopting Li-M alloys (M = 1 to 5 at%) will be beneficial for stabilizing the Li/SE interfaces. In this work, we synthesized Li-Mg alloys with varying Mg content (0–15 at%) and investigated their electro-chemo-mechanical properties as the alloy anodes in SSLB cells. X-ray diffraction (XRD) data revealed a formation of pure body-centered cubic (BCC) phase without secondary phases, consistent with the Li-Mg phase diagram. From the SEM, the grain size of the Li-Mg alloys decreases as the Mg content increases due to the solid solution strengthen effect. Besides, the randomly orientated grains are confirmed by electron backscatter diffraction (EBSD) analysis. The impact of Li-Mg alloys on electrochemical performances was systematically investigated. Among the series of alloy compositions, highest critical current density (CCD) value of 2 mA/cm 2 could be obtained from 1 at% Mg-Li, which was significantly higher than the 1.2 mA/cm² observed from pure Li, indicating improved resistance to the dendrite growth. On further increasing the Mg content, the CCD value decreased due to low Li-ion diffusivity and high interfacial resistance. The 1 at% Mg-Li alloy anode demonstrated stable long-term cycles for over 500 h during repeated Li plating/stripping in symmetric cells under mild stack pressure (~3.5 MPa). In stark contrast, the pure Li anode exhibited aggressive void formations at the Li/SE interface and suffered from pre-mature cell failure within 200 h of repeated cycling. Further, the impact of Mg-Li alloy with various Mg contents on NMC/Li-Mg alloy full-cell performance was evaluated. The 1 at% Mg-Li alloy anode delivered a first discharge capacity of 183 mAh/g at C/10 and exhibited capacity retention of 93.73% after 150 cycles, compared to 89.76% for pure Li. However, Mg contents greater than 1 at% in Mg-Li alloys led to degradation in cell performances (e.g., capacity retention and C-rate tests). Electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT) analyses quantified various resistance contributions and performance degradation mechanisms. The full cell with 1 at% Mg–Li anodes exhibited lower total resistance than that with a pure Li anode, primarily due to reduced mechanical degradation and suppressed charge transfer resistance growth during cycling. This work demonstrates a promising strategy to enhance the electro-chemo-mechanical properties of alloy anodes by optimizing Mg content, enabling improved interfacial stability, reduced resistance, and extended cycling performance in solid-state batteries. We will further discuss strategies for designing alloy anodes to optimize their properties and performances.

Anode‐less all‐solid‐state batteries (ASSBs) are being targeted for next‐generation electric mobility owing to their superior energy density and safety as well as the affordability of their materials. However, because of the anode‐less configuration, it is nontrivial to simultaneously operate the cell at room temperature and low pressure as a result of the sluggish reaction kinetics of lithium (de)plating and the formation of interfacial voids. This study overcomes these intrinsic challenges of anode‐less ASSBs by introducing a dual thin film consisting of a magnesium upper layer with a Ti3C2Tx MXene buffer layer underneath. The Mg layer enables reversible Li plating and stripping at room temperature by reacting with Li via a (de)alloying reaction with a low reaction barrier. The MXene buffer layer maintains the electrolyte‐electrode interface by inhibiting the formation of voids even at low pressure of 2 MPa owing to the high ductility of MXene. This study highlights the importance of a combined chemical and mechanical approach when designing anode‐less electrodes for practical adaptation for anode‐less ASSBs.

Although a high stack pressure (≥50 MPa) enhances solid-solid contacts in solid-state batteries (SSBs), it poses impracticality for commercialization. This work proposes a self-pressure silicon (Si)-carbon composite anode that enables stable operation under reduced external pressure (≤2 MPa). The self-pressure anode features a prestress structure that can effectively alleviate the internal and external stress simultaneously, which is fabricated with ionic-conductive poly(ethylene oxide) (PEO)/lithium salt-coated carbon nanotubes (CNTs) being compressed by shrinking graphene hydrogel. The capillary-driven hydrogel shrinkage generates internal pressure, compensating for the volumetric expansion (up to 300%) of Si. This creates dynamic solid-solid interfaces between compressed CNTs/PEO and expanding Si, ensuring both mechanical stability and ion/electron transport. The SSBs with this self-pressure anode have a long cycle life of 700 cycles and a high capacity retention of 79.2% in an organic/inorganic composite electrolyte without external pressure (0 MPa). The half-cell using a sulfide solid-state electrolyte reached 700 cycles and was able to achieve a stable cycle life at the lowest 2 MPa stack pressure. This design resolves interfacial challenges by prestress in SSBs.

A configuration combining a low-strain 3D lithium-carbon anode with an in situ polymerized solid polymer electrolyte was proposed, which significantly enhances interface stability in solid-state lithium metal batteries under low pressure. This design accommodates lithium volume changes, reduces internal pressure fluctuation from 13.9% to 6.5%, and extends the cycle life over tenfold versus planar electrodes, offering a promising route toward practical solid-state batteries.

The commercialization of all‐solid‐state lithium‐sulfur batteries (ASSLSBs) depends on maintaining high performance under low stack pressure. However, conventional ASSLSBs experience significant performance degradation under low pressure due to contact losses and diffusion kinetics challenges at solid‐solid triphase interfaces. This study decouples electrochemical contact area (ECA) losses from diffusion kinetics losses for the first time through a series of pressure‐dependent electrochemical tests. Additionally, the cathode volume changes are investigated using an isolated real‐time displacement test. Findings reveal that contact losses primarily occur during charging, while diffusion kinetics are more sensitive to reduced stack pressure during discharging. To mitigate this issue, metallic indium (In) is incorporated into cathode composites to enhance the triphase interfaces. During cycling, In spheres transform in situ into In2S3/InS, significantly reducing volume fluctuations and improving ECA retention and diffusion kinetics under various pressures (0.5–7 MPa). As a result, ASSLSBs with In additive demonstrate markedly enhanced electrochemical performance under low stack pressure at room temperature, achieving 810 mAh g−1 at 1 MPa and 1198 mAh g−1 at 7 MPa, (0.1C, 28 °C). The work provides revolutionary insights for the development of high‐energy ASSLSBs and other systems suffering large volume changes.

Silicon (Si) anodes, free from the dendritic growth concerns found in lithium (Li) metal anodes, offer a promising alternative for high-energy all-solid-state batteries (ASSBs). However, most advancements in Si anodes have been achieved under impractical high operating pressures, which can mask detrimental electrochemo-mechanical issues. Herein, we effectively address the challenges related to the low-pressure operation of Si anodes in ASSBs by introducing an silver (Ag) interlayer between the solid electrolyte layer (Li6 PS5 Cl) and anode and prelithiating the anodes. The Si composite electrodes, consisting of Si/polyvinylidene fluoride/carbon nanotubes, are optimized for suitable mechanical properties and electrical connectivity. Although the impact of the Ag interlayer is insignificant at an exceedingly high operating pressure of 70 MPa, it substantially enhances the interfacial contacts under a practical low operating pressure of 15 MPa. Thus, Ag-coated Si anodes outperform bare Si anodes (discharge capacity: 2430 vs 1560 mA h g-1 ). The robust interfacial contact is attributed to the deformable, adhesive properties and protective role of the in situ lithiated Ag interlayer, as evidenced by comprehensive ex situ analyses. Operando electrochemical pressiometry is used effectively to probe the strong interface for Ag-coated Si anodes. Furthermore, prelithiation through the thermal evaporation deposition of Li metal significantly improves the cycling performance.

No abstract available

Applying high stack pressure (often up to tens of megapascals) to solid-state Li-ion batteries is primarily done to address the issues of internal voids formation and subsequent Li-ion transport blockage within the solid electrode due to volume changes. Whereas, redundant pressurizing devices lower the energy density of batteries and raise the cost. Herein, a mechanical optimization strategy involving elastic electrolyte is proposed for SSBs operating without external pressurizing, but relying solely on the built-in pressure of cells. We combine soft-rigid dual monomer copolymer with deep eutectic mixture to design an elastic solid electrolyte, which exhibits not only high stretchability and deformation recovery capability but also high room-temperature Li-ion conductivity of 2×10−3 S cm−1 and nonflammability. The micron-sized Si anode without additional stack pressure, paired with the elastic electrolyte, exhibits exceptional stability for 300 cycles with 90.8% capacity retention. Furthermore, the solid Li/elastic electrolyte/LiFePO4 battery delivers 143.3 mAh g−1 after 400 cycles. Finally, the micron-sized Si/elastic electrolyte/LiFePO4 full cell operates stably for 100 cycles in the absence of any additional pressure, maintaining a capacity retention rate of 98.3%. This significantly advances the practical applications of solid-state batteries. Applying high stack pressure is primarily done to address the mechanical failure issue of solid-state batteries. Here, the authors propose a mechanical optimization strategy involving elastic electrolyte to realize solid-state batteries operating without external pressurizing.

Abstract Among the challenges facing Li‐metal all‐solid‐state‐batteries (ASSBs), achieving stable low‐pressure operation remains a formidable task owing to limited interfacial contact and Li‐dendrite growth. In this study, a simple yet scalable approach is presented to address these issues via a dual‐functional additive strategy. Sulfide‐based solid electrolytes (SEs) are reformulated by incorporating mechanically robust and lithium‐scavenging Li4Ti5O12 (LTO) particles through powder mixing and cold pressing. Careful control of particle size localized smaller LTO particles at grain boundaries and pores without disrupting the bulk Li‐ion conduction network. The resulting LTO‐incorporated composite solid electrolyte (LTO‐CSE) simultaneously offers mechanical reinforcement and electrochemical scavenging/current homogenization via zero‐strain lithiation, without imposing mechanical stress within the SE matrix. The LTO‐CSE exhibits enhanced stability at high current densities even under low stack pressures, without requiring warm isostatic pressing, not in pouch cells but in custom‐built spring‐loaded cells. Notably, it raises the critical current density from 4.5 to 7.5 mA cm−2 at 10 MPa. Furthermore, full cells demonstrate over 900 stable cycles without short‐circuiting, delivering a high areal capacity of ≈3.5 mAh cm−2 under 10 MPa, and stable operation even at pressures as low as 2 MPa. This work establishes a generalizable design framework for next‐generation solid‐state batteries.

All‐solid‐state lithium–sulfur batteries (ASSLSBs) face challenges due to the need for high stack pressures to maintain interfacial contact. This study demonstrates that surface‐engineered current collectors coated with carbon‐based primer layers enable low stack‐pressure (10 MPa) operation of ASSLSBs. Dry‐processed lithium sulfide (Li2S)–composite cathodes, using carbon‐coated aluminum (Al) foil, show significantly reduced interfacial resistance, enhanced adhesion, and improved cycling stability. Interfacial resistance is reduced by 5–10 times compared to bare aluminum, and surface analyses confirmed improved mechanical interlocking between the composite cathode and current collector. Notably, carbon black‐coated Al collector leads to superior performance, with ≈800 mAh g−1 reversible capacity and 78% retention over 350 cycles at 10 MPa. Even at 1 C (1 C = 1166 mAh g−1), carbon‐coated cells maintained 96% of the capacity obtained at C/10. This practical strategy provides a scalable approach to enable low‐stack‐pressure operation and broaden ASSB implementation.

All-solid-state batteries (ASSBs) using an alkali metal anode and a solid-state electrolyte (SE) face several problems due to poor physical and electrical contact. Recent experiments have shown that applying a stack pressure can improve the interface contact and suppress void formation. The mechanical properties of Na metal are different from those of Li metal, leading to differences in the mechanisms of the pressure-dependent interface evolution. Herein, we report a three-dimensional time-dependent model for tracking the evolution of interfaces formed between Na metal and Na-β″-alumina SE. Our results show that Na metal contacts more conformally with the SE, providing a lower interfacial resistance, compared with Li metal, assuming equal resistance due to contamination. The differences due to contact elastoplasticity are larger than the differences in metal creep effects. In fact, we show that increased stack pressure can lead to lower creep because the contact is more conformal at high pressures. Our excellent agreement with recent experiments determines an effective hardness of Na in the Na-SE batteries to be 15 MPa. The results further reveal that the pressure dependence of void suppression is dominated by contact elastoplasticity.

Ensuring low‐pressure operability is imperative in the practical deployment of all‐solid‐state batteries (ASSBs) with sulfide solid electrolytes, highlighting the pivotal roles of functional binders. Herein, slurry‐applicable thiol‐ene click reaction‐derived modifications of styrene‐butadiene rubber (SBR) binders are introduced to enhance the electrochemo‐mechanical stabilities of composite cathodes under low operating pressures. Two key modifications are realized: the grafting of carboxylate functional groups to improve the adhesion and cross‐linking to enhance the modulus and elasticity. A key insight gained is that cross‐linking is considerably more critical in improving the low‐pressure performance than adhesion enhancement. Electrochemical evaluations using single‐crystalline LiNi0.8Co0.1Mn0.1O2|Li6PS5Cl|(Li‐In) half‐cells at 0.3 MPa indicate that LiNi0.8Co0.1Mn0.1O2 electrodes with the cross‐linked binder exhibit superior electrochemical performances, including higher initial discharge capacities and improved initial Coulombic efficiencies and capacity retentions compared to those of the unmodified‐SBR‐based electrodes (163 vs. 133 mA h g−1, 68% vs. 73%, and 67% vs. 75% at the 100th cycle, respectively). Comprehensive analyses, including operando electrochemical pressiometry, reveal that cross‐linking effectively maintains the electrode integrity, thereby stabilizing the interfacial resistance during cycling. These findings offer critical design guidelines for practical, high‐performance ASSB systems.

During charge–discharge cycling, irreversible volume changes in all‐solid‐state batteries (ASSBs) impair electrode–electrolyte contact and elevate interfacial resistance, necessitating several MPa of external pressure. However, such high‐pressure conditions hinder commercialization, underscoring the need for interfacial engineering strategies to ensure stable operation under low‐pressure conditions. This study shows that 3D microscale interfacial architectures significantly enhance the cycling stability of ASSBs. The structure is fabricated through sequential imprinting with polymer molds, a free‐standing sulfide electrolyte membrane, and the formation of mechanically stable interfaces. The symmetric cell with 3D interfaces maintains stable cycling up to 600 h, outperforming that with flat interfaces (400 h). The full cell exhibits improved electrochemical performance with enhanced capacity and retention. Microstructural analysis after long‐term cycling reveals continuous and rigid interfaces in 3D interfacial cell. A finite element model simulation demonstrates that out‐of‐plane stresses are relaxed to in‐plane directions, thereby accommodating electrode expansion/contraction. The impedance distribution of relaxation times quantitatively confirms that the resistance increases of the 3D interfacial cell during cycling are smaller than those observed for flat interfacial cell, both for the charge transfer resistance (from 1275.12 to 2679.81 Ω vs. from 2177.44 to 6486.42 Ω) and diffusion‐related resistance (from 28.46 to 104.21 Ω vs. from 33.02 to 153.79 Ω).

Silicon-based anodes show great potential in solid-state batteries due to their high theoretical density, low cost, and resistance to lithium dendrite formation. However, the severe interfacial degradation caused by the large volume expansion of silicon remains a critical challenge. To address these interfacial problems, this study innovatively employs mechanical blending to rapidly achieve solid-phase coating, encapsulating nanosilicon particles on the surface of sulfide electrolytes. The reliability of this coating method was verified through SEM and TEM characterization. The coated silicon anode demonstrated stable operation under ultralow stack pressure and showed significantly enhanced rate capability and long-term cycling performance. These improvements were attributed to the enlarged interfacial contact area, the formation of a more robust electrode structure, and the creation of fast ion/electron transport pathways. The proposed mechanical blending strategy significantly improves the efficiency of solid-state coating and facilitates the practical application of silicon-based anodes in ASSBs.

Sulfide‐based all‐solid‐state batteries (ASSBs) are emerging as promising alternatives to lithium‐ion batteries due to their high energy density and enhanced safety. However, sulfide solid electrolytes, such as Li6PS5Cl (LPSCl), face significant chemo‐mechanical challenges at the interface with layered oxide cathodes, including Li[Ni0.8Co0.1Mn0.1]O2 (NCM811). During cycling, oxidative decomposition of LPSCl leads to interfacial void formation and mechanical contact loss, which significantly degrade ionic conduction. Strategies such as coating stable passivation layers have been explored to suppress LPSCl decomposition, but these approaches often involve trade‐offs, including increased cost, complex synthesis, and elevated interfacial resistance. Herein, the concept of mechano‐electrochemical healing at the LPSCl–NCM811 interface is introduced to address these issues. During charging, voids form due to LPSCl decomposition; however, this mechanical contact loss can be reversed through a healing mechanism during discharge at ≈2.2 V (vs Li/Li+). This process, driven by the lithiation of elemental sulfur − a decomposition product of LPSCl − restores interfacial contact and enhances ionic conduction. Consequently, mechano‐electrochemical healing achieves stable capacity retention over 300 cycles and superior rate capability even under pressure‐free conditions. These findings underscore the potential of electrochemical formation cycling as a practical strategy for improving the mechano‐electrochemical performance of ASSBs.

The thermal behavior is pivotal to the performance and safety of battery cells. To date, several thermal modeling approaches for lithium-ion batteries with liquid electrolyte (LiB) exist for different cell formats, tab designs, and more [1,2]. However, for all-solid-state batteries (ASSBs), relatively few publications exist on this topic. This presentation deals with sulfide-based ASSB cells. Although lab-sized ASSB cells perform well, cycling conditions in the lab still differ from practical applications. On the one hand, high pressure of several tens of MPa is usually applied during cycling to achieve good electrochemical behavior. On the other hand, separator thicknesses are in the range of several hundred µm due to difficulties in production and processability [3]. This results in low energy densities and prevents real-world application [4]. Therefore, a direct comparison between lab-sized ASSB cells and existing LiB cells used in applications is neither reasonable nor possible. Today, it is still impossible to conclude whether ASSBs are truly superior to LiBs. To enable such a comparison, simulation techniques must be applied. Simulation-based upscaling of lab-sized ASSB cells to practical applications allows a fair comparison with LiBs. In this work, the thermal behavior of ASSB cells was investigated as a first step. A novel cell holder for calorimetric measurements of a lab-sized ASSB cell was developed. This cell holder allows for measurement of the heat generation of an ASSB cell in a commercial calorimeter (TAM IV, TA Instruments) while applying pressures of up to 30 MPa. By determining the thermal inertia of the cell holder and using a deconvolution algorithm [5], the original heat signal of the cell can be restored. After introducing the novel cell holder, measurement results of an ASSB cell (LiIn|LPSCl|LPSCl-NMC, 3.0 mAh) will be presented. This includes pressure-dependent results for 0.2 MPa, 10 MPa, 20 MPa, and 30 MPa, C-rates of 0.1C, 1C, and 4C, and temperatures of 25°C, 60°C, and 80°C. These data are crucial to determine the pressure-dependent interfacial resistances as well as the temperature-dependent ionic conductivity and electrochemical behavior of the cell. Furthermore, changes in stack pressure are tracked by a load cell. These results can later be used for mechanical simulations. The cell holder’s measurement results serve as input parameters for the thermal simulation. Different upscaled cell formats are investigated using parameters from the lab-sized cell. Thermal gradients and hotspots within the upscaled cells are identified and compared to LiBs. However, as the cell parameters are still unrealistic for practical applications - with a LiIn anode and a separator thickness of approximately 400 µm - these parameters are altered, starting from the validated lab-sized pouch cell. The thick separator dominates the averaged thermal parameters: heat capacity, thermal conductivity, and density of the cell. Assuming a thin separator of 20 µm leads to a 110% and 50% increase in thermal conductivity and density, respectively, but to a decrease in heat capacity of about 7%. This results in more heating of the cell but fewer thermal gradients. Furthermore, an electrochemical p2D model is parametrized and validated using the measured cycling data and the heat generation curve. Starting from the validated model, application-relevant separator thicknesses and a Li-metal anode are assumed. Lower overpotentials induced by the thinner separator lead to reduced heat generation. However, due to the reduced heat capacity, more cooling power is needed to minimize the heating of the cell. The p2D model is coupled with a thermal 3D model for different sizes and cell formats. Cooling strategies such as convective and tab cooling are compared in terms of effectiveness and electrochemical cell performance. Furthermore, the pressure-dependent measurement data are used to scale the performance for realistic pressure scenarios. Finally, an outlook is given on the thermal safety and runaway behavior of ASSBs. The simulation results enable a fair and realistic comparison of today’s LiBs with future sulfide-based ASSB technologies. Electrochemical behavior, the effort required for cooling strategies, and the resulting overall energy densities serve as indicators for the current progress in ASSBs and the further research necessary to transition ASSBs from laboratory research to real-world applications. Acknowledgment: This work was financially supported by the German Federal Ministry of Education and Research (BMBF) under grant number 03XP0597B (FB2-SAFE). The project is overseen by Project Management Juelich (PTJ). References: [1] Frank et al. ECS Adv. 1 (2022) 40502. [2] Sturm et al. J. Electrochem. Soc. 167 (2020) 130505. [3] Rosner et al. Adv. Energy Mater (2025) 2404790 [4] Schmaltz et al. Adv. Energy Mater (2023) 13, 2301886 [5] Kunz et al. J. Electrochem. Soc.169 (2022) 080513 Figure 1

All-solid-state batteries (ASSBs) are promising next-generation energy storage systems; however, their performance is often constrained by poorly understood interfacial phenomena within composite cathode (CC) layers. In this study, we systematically elucidate how the microenvironment of CC layers, controlled by the mixing sequence of cathode active material (CAM), solid electrolyte (SE), and conductive carbon, determines the electrochemical performance of ASSBs. By preparing three representative CC configurations, we demonstrate that uniform CAM|SE interfaces promote well-developed lithium-ion transport pathways, leading to enhanced rate capability and long-term cycling stability. In contrast, poor CAM|SE contact increases charge-transfer resistance and results in premature cell failure within tens of cycles. Multiscale synchrotron-based characterizations reveal the mechanistic origin of this performance disparity. Interfacial inhomogeneity induces particle-level state-of-charge heterogeneity, which leads to localized CAM overcharging and subsequent SE decomposition. The significance of uniform CAM|SE interfaces becomes even more pronounced under practical conditions. At 30 °C, where ionic transport is intrinsically limited, ASSB cells with uniform CAM|SE interfaces maintain stable cycling performance, whereas those with less-uniform interfaces fail at an early stage. Finally, pouch-type anodeless ASSB cells operated under low stack pressure reproduce the same performance trends, further underscoring the critical role of CC microstructure control. Overall, this work establishes a direct correlation between CAM|SE interfacial uniformity, SE stability, and ASSB performance, providing practical guidelines for engineering reproducible, high-performance CC layers that bridge laboratory-scale demonstrations with real-world applications.

The pursuit of safer, higher-energy-density batteries has driven significant research into all-solid-state batteries (ASSBs). Replacing conventional liquid electrolytes with solid-state alternatives promises enhanced safety and the potential for higher energy densities. However, realizing the full potential of ASSBs requires innovative manufacturing techniques that are both scalable and cost-effective for large-scale production. While dry-mixing of solid-state components is under development, slurry-based coating offers a compelling alternative due to its compatibility with established liquid electrolyte battery production infrastructure and its potential for precise material deposition. A significant hurdle in ASSB manufacturing is the fabrication of thin, free-standing sulfide separators, which typically requires temporary carriers like Mylar or Teflon, followed by complex and potentially damaging transfer processes to the electrode surfaces. These processes not only increase manufacturing complexity and cost but also pose challenges to maintaining the integrity of the delicate sulfide separator layer. To address these challenges and unlock the manufacturability of ASSBs, we propose a novel and simplified approach: coating sulfide slurry directly onto the electrode surfaces, followed by lamination to assemble the ASSB cell stack. This method offers a streamlined manufacturing process by eliminating the need for a separate separator film, thereby reducing material handling and processing steps. Furthermore, this approach has the potential to significantly reduce interfacial resistance between the electrodes and electrolyte, a critical factor limiting the performance of ASSBs. By ensuring intimate contact between the solid electrolyte and the electrode materials, we aim to enhance lithium-ion transport and improve overall battery performance. This presentation explores multi-step separator fabrication and integration processes to optimize the interfacial contact and mechanical stability of the ASSB structure. Strategies explored include coating sulfide slurry onto partially calendered electrodes to create a textured surface for improved adhesion, as well as laminating the assembled electrode-electrolyte layers together under controlled pressure and temperature to enhance densification and reduce porosity. We discuss the impact of separator integration methods on cell internal resistance and capacity retention during long-term cycling. Our findings identify the optimal combination of slurry coating, lamination, and densification techniques for achieving high-performance ASSBs with improved manufacturability, reduced interfacial resistance, and enhanced electrochemical stability. This research contributes to the advancement of scalable and cost-effective manufacturing methods for ASSBs, paving the way for their widespread adoption in future energy storage applications.

The demand for batteries with high gravimetric and volumetric energy density is driving research towards the development of new battery technologies. All-solid-state batteries (ASSBs) offer the potential to address current challenges faced by liquid electrolyte-based batteries, such as the implementation of Li-metal or fully utilized silicon as an anode material.1 To date, however, there are no commercially available ASSBs with an inorganic solid electrolyte on the market, because of new challenges when using solid electrolytes, such as interfacial stability, solid-solid contact problems, or the ability to operate at low pressures.2 Eckhardt et al.3 recently demonstrated that voids at the interface of a solid electrolyte based separator and a Li-metal anode cause an additional resistance called constriction resistance. This effect occurs when current lines are constricted by bottlenecks (voids) at the interface. In the absence of voids at the interface, the current lines are not constricted, and no additional resistance is observed.4 Due to its frequency-dependent nature, this additional resistance can generally only be detected by impedance spectroscopy. During Li stripping, voids may form at the interface, resulting in a higher current density at the remaining contact areas during plating.5 This ultimately leads to the formation of Li dendrites, making the constriction effect the primary driver of a critical failure mechanism of ASSBs. In the present study, we present experimental evidence of a constriction effect in composite cathodes, composed of either single or polycrystalline LiNi0.6Mn0.2Co0.2O2, solid electrolyte (Li6PS5Cl), conductive carbon additive, and a polymeric binder. Voids can be caused by a poor microstructure or by the incorporation of a non-conductive polymer binder, which exhibits properties analogous to those of voids. However, large-scale roll-to-roll production of sulfidic ASSB components requires polymeric binders.6 The constriction effect can be observed through impedance spectroscopy of cathodes in blocking conditions as a semicircle that overlaps with the 45° line of the transmission line model. We investigate fitting with different equivalent circuits that model the constriction effect, and show the dependence of the constriction effect on densification pressure, binder content, and active material loading. Using a µ-reference electrode in ASSB single-layer pouch cells,7 the change of the constriction effect in the cathode is monitored during cycling. Additionally, LiNi0.6Mn0.2Co0.2O2/Li6PS5Cl core-shell particles are explored to examine whether this can reduce the constriction effect in sheet-type cathodes. Overall, the constriction of current lines in the cathode is a solid-state-related geometric effect that increases the overall cell resistance and is not observed in liquid electrolyte-based batteries. Our findings provide an overview of the constriction effect in all-solid-state cathodes and its impact on cell performance. Acknowledgment The authors wish to thank C. Sedlmeier and F. Friedrich from BMW as the project initiator and for the scientific support. This work is part of the BMW project “IPCEI EuBatIn” (16BZF205), which is funded by the German Federal Ministry for Economic Affairs and Climate Action and the Bavarian Ministry of Economic Affairs, Regional Development and Energy. References J. Janek and W. G. Zeier, Nat Energy, 8(3), 230–240 (2023). T. Schmaltz, F. Hartmann, T. Wicke, L. Weymann, C. Neef and J. Janek, Advanced Energy Materials, 13(43), 2301886 (2023). J. K. Eckhardt, P. J. Klar, J. Janek and C. Heiliger, ACS Applied Materials & Interfaces, 14(31), 35545–35554 (2022). J. K. Eckhardt, T. Fuchs, S. Burkhardt, P. J. Klar, J. Janek and C. Heiliger, Adv Materials Inter, 10(8) (2023). P. Barai, T. Fuchs, E. Trevisanello, F. H. Richter, J. Janek and V. Srinivasan, Chem. Mater., 36(5), 2245–2258 (2024). J. Lee, T. Lee, K. Char, K. J. Kim and J. W. Choi, Accounts of chemical research, 54(17), 3390–3402 (2021). C. Sedlmeier, R. Schuster, C. Schramm and H. A. Gasteiger, J. Electrochem. Soc., 170(3), 30536 (2023).

All-solid-state batteries (ASSBs) provide the opportunity for substantially enhanced gravimetric and volumetric energy and power density and improved safety. However, these gains will not be realized without first overcoming substantial challenges, notably, the high interfacial resistance between electrodes and the solid-state electrolyte (SSE) which requires high stack pressures, on the order of 10,000 psi, to achieve high performance metrics.[1,2]. Already there is a large and growing body of research demonstrating the advantages of laser structuring of Li-ion battery materials for enhanced kinetics and shorter diffusion pathways [3,4]. This work extends these advantages to ASSBs through lowering the catholyte-SSE interfacial impedance by increasing its surface area and providing less torturous paths for ion diffusion. The work presented here uses a near-IR (1030 nm) femtosecond laser (pulse duration approx. 250 fs) to ablate microstructures into the surface of a slurry-cast LiNi0.8Mn0.1Co0.1O2 (NMC811):Li6PS5Cl catholyte. Micrometer-sized channel structures were ablated at various depths and pitch spacings to assess the effect of patterning on cell performance. X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) measurements were acquired on both pristine and patterned samples to ensure that the femtosecond laser pulses do not cause any residual compositional or phase changes, respectively. Critically, low interfacial resistance will require that an SSE layer be applied to the patterned catholyte such that the microstructure is preserved while maintaining intimate contact between the catholyte and SSE layer. SSE layers were both slurry cast and pellet-pressed onto both pristine and patterned electrodes. Cross-sectional SEM was used to investigate the degree of interfacial contact, and relate interface quality to parameters such as SSE application technique (e.g., pellet pressing vs. slurry casting) and slurry properties (i.e., viscosity). The improvement to interfacial ionic conductivity is assessed using electrochemical impedance spectroscopy (EIS). The effect of stack pressure is analyzed in order to assess the degree to which laser patterning can alleviate stack pressure requirements in ASSBs. References: [1] Chen, Xinzhi, et al. "Enhancing interfacial contact in all solid state batteries with a cathode-supported solid electrolyte membrane framework." Energy & Environmental Science3 (2019): 938-944. [2] Pervez, Syed Atif, et al. "Interface in solid-state lithium battery: challenges, progress, and outlook." ACS applied materials & interfaces25 (2019): 22029-22050. [3] Pfleging, Wilhelm. "A review of laser electrode processing for development and manufacturing of lithium-ion batteries." Nanophotonics3 (2018): 549-573. [4] Dunlap, Nathan, et al. "Laser ablation of Li-ion electrodes for fast charging: Material properties, rate capability, Li plating, and wetting." Journal of Power Sources 537 (2022): 231464. Figure 1

All solid-state batteries have long been considered the next leap forward in energy storage devices, owing to their improved safety and higher theoretical energy density than their liquid counterparts. However, even with these improvements, heavy metal positive electrode materials such as lithium nickel oxides (NMC) and lithium iron Phosphate (LFP) are not gravimetrically energy dense enough to meet the growing energy requirements of modern-day applications. One promising candidate is the lithium sulfur (Li-S) chemistry due to the high theoretical capacity and abundance of sulfur. However, designing positive electrodes with high sulfur content that is able to withstand the large sulfur morphology expansion, alongside minimizing the excess Li storage in the negative electrode has remained elusive. A solution to this is the development of “anode-free” or zero excess lithium (ZEL) cells which minimise inactive materials and mitigate the challenges of handling Li metal foils during fabrication. These offer a further enhanced energy density, additional safety improvements and more control of the negative electrode interface. However, the inefficiency of lithium plating and stripping leads to rapid capacity degradation due to the absence of an excess lithium inventory. Here we present, to our knowledge, the development of the first zero-excess (anode free) all solid state LiS battery, composed of an Li2S-based catholyte combined with an Li6PS5CL solid electrolyte and a Ni/In negative electrode. The cell displays good capacity retention, 350 mAh g-1 Li2S after 50 cycles, and good rate capability, up to 2C. Since zero-excess cell degradation is primarily afforded to Li losses at the negative electrode, our study focuses on understanding this degradation and its relationship with the interfacial resistance at the anode-electrolyte interface. In addition, we show the affect of replacing Indium with an ionically conductive amorphous thin film as a method to reduce interfacial resistance which improves the gravimetric energy density of the cell. Finally, using X-ray computer tomography, we investigate the formation of cracks and void shifts and their subsequent effect on cycling performance, alongside the importance of pressure to enable long cycling life. Figure 1

All-solid-state batteries (ASSBs) hold great promise as next-generation energy storage systems due to their enhanced stability and high energy density compared to traditional lithium-ion batteries. This improvement stems from the use of a solid electrolyte (SE) instead of a highly volatile liquid electrolyte and the incorporation of a lithium metal anode. In general, sulfide-based SSBs require adequate pressurization conditions to establish an intimate interface between the solid particles, ensuring a continuous electron/ion conduction path. At the cell level, maintaining external stack pressure during operation is crucial to preserve conformal solid-solid contact. Furthermore, when scaling up, fabrication pressure should be carefully considered to enhance electrode densification without causing damage. In particular, the fabrication of thin, robust, and scalable SE membranes faces practical challenges due to a limited amount of polymeric binder and the low intrinsic ductility of SEs after densification. Understanding the mechanical behavior of these SE membranes is essential to ensure their structural stability during manufacturing. In this study, we systematically examined the mechanical properties of SE and SE membranes. The deformability of various types of sulfide SEs was assessed using a powder compaction test, departing from the commonly used indentation method. The yield pressure, which indicates the deformability of the SE powder, is influenced by the composition and synthesis conditions of the SEs. The stress-strain behaviors of the SE membranes were obtained through tensile and flexural tests for both as-prepared and pressed samples, respectively. The tensile and bending behaviors of the SE membranes strongly depend on the combination of the SE and polymeric binder. The utilization of a ductile SE and a rubbery polymer binder can enhance the flexibility and ductility of the membrane, leading to increased densification degree and low interfacial resistance even under lower fabrication pressure. The details of cell configuration, fabrication procedure, and the resulting performances of the cell will be discussed in this talk.

Lithium-ion batteries (LIBs) are widely used in a variety of applications due to their high energy and power densities, and long cycle life. With the expanding use of LIBs in electric vehicles and energy storage systems, there is very active research into all-solid-state batteries (ASSBs), which offer greater energy density than traditional LIBs and eliminate the inherent fire hazards. Since most of the detailed reactions involved in the performance and degradation of a battery are temperature-sensitive, so-called thermal activation processes, it is very important to accurately assess whether a battery can have the high performance and low degradation characteristics required under different climatic conditions. To evaluate the electrochemical properties of electrode materials in LIBs, a half-cell is typically constructed with the electrode of interest as the working electrode (WE) and lithium metal as auxiliary electrode (AE). Here, lithium metal is close to an ideal non-polarizable material, has a large capacity, and maintains a constant potential during charge/discharge, so it is widely used as AE material in LIB research. However, several issues arise when lithium is used as AE in ASSBs: Lithium metal undergoes mechanical deformation due to the relatively high internal pressure required to ensure good contact between lithium and solid electrolyte; When in contact with sulfide-based solid electrolytes, which are currently of interest due to their high ionic conductivity, side reaction products can lead to an increase in interfacial resistance; the growth of lithium dendrites, often observed in conventional LIBs, is still unavoidable. These issues all affect the half-cell signal, potentially causing a distorted evaluation of the WE’s characteristics. Lithium-indium alloy is being utilized as AE for ASSB half-cells to replace lithium metal. It exhibits excellent mechanical ductility and maintains a constant reduction potential over a wide stoichiometric range, ensuring excellent contact property and voltage stability. Moreover, it is very easy to fabricate through simple compression at room temperature. Nevertheless, the limited study on its electrochemical properties leaves uncertainty regarding its full functionality as AE for accurate evaluation of WE, particularly in extreme operational conditions. For instance, lithium-indium alloy are primarily based on alloying/dealloying reactions involving solid-state diffusion of lithium, which is generally considered to be a relatively slow process kinetically, while lithium only involves a kinetically favorable plating/stripping process on the surface. Therefore, a comparative analysis of these different reaction mechanisms in terms of kinetics is necessary. This presentation presents a comparative analysis of the electrochemical properties of lithium metal and lithium-indium alloys used as AEs in ASSB half-cells. In particular, the electrochemical properties of lithium-indium alloys with different reaction mechanisms with lithium are investigated over a range of temperatures and current densities, and these differences are discussed from a kinetic point of view. For this purpose, first, using a three-electrode half-cell with lithium or lithium-indium alloy as AE, we compared the electrochemical properties of these two AEs during half-cell operation by interpreting their potential and over-potential changes, and quantifying their detailed resistances. Then, through dc experiments on lithium and lithium-indium symmetrical cells, we identified differences in overvoltage behavior due to differences in their reaction mechanism. In particular, we noted distinct differences in the overpotential behavior of these two electrodes at low temperatures and high current densities. Furthermore, based on the results of a combined dc/ac electrochemical analysis, we derived the overvoltage that dominates the overall overvoltage at each of the two electrodes. Based on these results, we analyzed how the kinetic differences between the two electrodes affect the cathode half-cell signal, in order to derive key considerations for reliable ASSB half-cell evaluation. In this presentation, the advantages and disadvantages of lithium-indium alloy compared to lithium metal as AE will be discussed from a kinetic perspective, focusing on interfacial and bulk resistance (overpotential). Furthermore, methods for utilizing AE to conduct accurate and reliable half-cell tests will be proposed.

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Anode‐free manufacturing of solid‐state batteries (SSBs) shows promise to maximize energy density by eliminating excess lithium (Li) and simplifying battery production. However, high reversibility during discharge (stripping of Li) is necessary for long‐lifetime SSBs with a limited Li reservoir. Further, the plastic flow of Li changes depending on the Li thickness, leading to possible differences in discharge performance under stack pressure. This work investigates the pressure‐dependent discharge performance of anode‐free manufactured SSBs with in situ plated Li and compares the performance to that of conventional thick Li foil cells. Distinct stripping behavior is observed at low pressures (0–1 MPa), where Li diffusivity and initial interfacial contact may control accessible capacity, compared to high pressures (3–10 MPa) where mechanical deformation of Li likely governs stripping behavior. Analysis of impedance spectra collected during stripping shows that additional stack pressure delays the formation of deep, as opposed to lateral, voids in the Li anode. These results provide insights to guide the transition from thick Li foil anodes to anode‐free manufactured SSBs.

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Among all the alternative battery systems beyond lithium-ion batteries (LIBs), all-solid-state fluoride ion batteries (ASSFIBs) are particularly promising due to their high theoretical energy density, thermal stability, and recent advancements...

The imperative for increased energy density in electric vehicles and aviation, coupled with recent occurrences involving lithium-ion battery thermal failures, has catalyzed extensive research attention on all-solid-state batteries (ASSBs). Precisely tuning cathode active material (CAM) and solid electrolyte (SE) particle sizes, along with their mixing ratio in cathode composite and external pressure, enables high electrochemical performance in ASSBs, potentially eliminating the need for electronically conductive additives and thereby enhancing energy density. This work investigates the complex interplay between external pressure and particle size combinations, with a specific focus on their combined impact on the electrochemical performance and thermal stability of ASSBs. Our results show that increasing stack pressure improves both initial cell capacity and long-term cycling stability, primarily due to enhanced CAM/SE interfacial contact and reduced transport limitations, which lowers ohmic and kinetic overpotentials. Additionally, higher CAM-to-SE particle size ratios to a certain limit correlate with improved capacity, attributed to reduced tortuosity and more favorable ion transport pathways. Importantly, thermal analysis demonstrates that optimized pressure and particle configurations contribute to improved thermal stability, suppressing hotspot formation and ultimately enabling safer, more reliable operation. These findings highlight the synergistic impacts of particle and pressure engineering in advancing high-performance, thermally stable ASSBs.

If all‐solid‐state fluoride‐ion batteries want to compete with existing battery technologies, significant improvements in terms of cyclic stability are necessary to fully access the high specific capacities, which this battery concept can provide in theory. Herein, the development of a high‐pressure, high‐temperature battery operation stand for battery cycling under inert conditions inside a glovebox is reported. This stand is then used to investigate the effect of stack pressure on the cell performance of conversion‐based as well as intercalation‐based electrode materials for fluoride‐ion batteries. It is found that cyclic stability as well as energy efficiency is strongly increased compared to nonpressure conditions, which is assigned to sustained interparticle contact. Thus, the cell design must be considered carefully to be able to distinguish intrinsic material properties from percolation‐ and interphase‐related impacts on the cell behavior. Further, the effect of pressure on the ionic conductivity of common solid fluoride‐ion conductors is investigated.

All‐solid‐state lithium‐metal batteries (ASSLMBs) with sulfide solid electrolytes have gained significant attention due to their potential for high energy density and enhanced safety. However, their development has been hindered by rapid lithium dendrite growth, low coulombic efficiency, poor battery rate performance, and poor cycling stability, posing a major obstacle to their commercialization. Herein, a multifunctional composite sulfide electrolyte (M‐CSE) is reported that is dynamically stable with lithium metal, promoting uniform Li+ deposition without dendrites. The resulting ASSLMBs exhibit an areal capacity of 10 mAh cm−2, an energy density of 219 Wh kg−¹, and a current density of 3.76 mA cm−2, with a capacity retention of 95.04% after 500 cycles at 0.5C. The assembled lithium swagelok cell and solid‐state lithium‐metal pouch cells have relatively low pressures, with the swagelok cell stack pressure ≈30 MPa and the pouch cell stack pressure also ≈2 MPa. More importantly, mass production of ultra‐low‐pressure pouch cells is realized by 3D printing technology, marking a crucial breakthrough for practical applications.

All-solid-state lithium-ion batteries (ASSLBs) are a promising next-generation energy storage technology for their enhanced safety and high energy density. In this study, we develop high-performance ASSLBs utilizing a Ni-rich single-crystalline NCM811 (SC-NCM811) cathode and a Li6PS5Br argyrodite solid electrolyte. By optimizing the cathode material and stack pressure, we demonstrate an exceptional areal capacity exceeding 4 mAh/cm2 with a high cathode loading of ∼21 mg/cm2. Electrochemical performance comparisons between SC-NCM811 and polycrystalline NCM811 (PC-NCM811) reveal the superior capacity retention and rate performance of SC-NCM811-based ASSLBs, particularly at an optimized stack pressure. Our findings underscore the potential of SC-NCM811 as a highly efficient cathode material for next-generation ASSLBs, offering both increased energy density and operational safety. This work highlights the importance of cathode engineering and pressure optimization in advancing the implementation of ASSLBs.

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Silicon (Si) anodes have attracted significant attention for all-solid-state batteries (ASSBs) due to their high theoretical capacity (~3500 mAh g⁻¹), which is nearly ten times that of conventional graphite (~370 mAh g⁻¹). Additionally, Si is earth-abundant and environmentally benign, making it a highly attractive candidate for sustainable energy storage. However, the practical deployment of Si anodes in ASSBs remains challenging, primarily due to severe volume expansion (>300%) during lithiation/de-lithiation, which leads to particle pulverization, interfacial degradation, and substantial irreversible capacity loss, especially under low stack pressure. In this work, we investigate a Si composite anode architecture that addresses these limitations by embedding Si particles within a Li x PS y Cl z (LPSCl) solid electrolyte (SE) matrix. The SE not only functions as an ion-conducting medium but also serves as a mechanical buffer to mitigate stress-induced degradation. Electrochemical analysis reveals that the Si–LPSCl composite delivers significantly enhanced performance, particularly under low operating pressure. Under high operating pressure (75 MPa), the composite achieves an initial Coulombic efficiency (ICE) of ~95% in a full cell with an NCM811 cathode, approaching the theoretical maximum and far surpassing the 80% ICE observed for a pure Si anode. Notably, the Si composite also retains high performance under low operating pressure (~5 MPa), with an ICE of 81%, compared to only 55% for the pure Si anode. Morphological characterization confirms that the Si–LPSCl anode maintains structural integrity during cycling, exhibiting minimal cracking and allowing for 3D ionic and electronic transport throughout the electrode layer. In contrast, the pure Si anode exhibits pronounced kinetic and mechanical degradation, particularly under low operating pressure, where lithium trapping and poor reversibility dominate. These findings highlight the critical role of kinetic–mechanical coupling in the design of solid-state electrodes and demonstrate that embedding a solid electrolyte matrix within silicon anodes effectively mitigates pressure-induced limitations. This approach enables stable and reversible electrochemical cycling, even under practical low-pressure conditions, thereby advancing the viability of ASSB systems for real-world applications. Figure 1

Lithium metal anodes are a promising pathway to achieving higher energy densities than current state-of-the-art Lithium-ion batteries. The highest theoretical energy densities can be obtained in an anode-free configuration, where the Lithium metal anode is formed on the current-collector (CC) in situ. However, the relative instability of the lithium metal anode poses challenges for liquid electrolytes due to the interface between CC and liquid electrolyte being unrestricted. Solid-state batteries (SSBs) are a promising alternative to Li-ion batteries due to the potential for higher energy and power densities as well as improved safety by eliminating the flammable liquid electrolyte . However, the initial Li nucleation, plating, and stripping processes on the CC surface in anode-free SSBs are influenced by both interfacial electro-chemistries and mechanical stresses [1]. For this reason, an external stack pressure is typically applied to ensure intimate contact between SSB interfaces. The majority of research on SSBs only reports nominal stack pressure as a static and singular variable, which is defined by the nominal applied force and surface area. However, stack pressure has been shown to be variable across cell surface area and throughout cycling. Therefore, there is increasing awareness that stack pressure must be treated as a spatially and temporally varying quantity, which can have a significant impact on the heterogeneity of the Li metal/solid electrolyte interface during cycling [2]. In this work, we utilize an operando thin-film pressure mapping sensor to analyze the spatial and temporal pressure distributions within anode-free SSBs during cycling. We examine the underlying the mechanisms of pressure evolution throughout Li plating and stripping with 200-µm spatial resolution. This system allows us to characterize evolving interfacial stress in situ and synchronize the pressure maps with electrochemical data. Consistent with our recent report, operando pressure mapping is used to show that elastomeric interlayers can be used to circumvent the inherent inhomogeneities in stack pressure throughout cycling [2]. We additionally show that the presence of alloying interlayers on the CC surface can promote improved wetting of Li metal across the anode-free interface. Leveraging the high spatial resolution of the sensor, we observe the evolution of pressure during plating and stripping at and around point contacts as Li metal creeps across the anode-free interface. The operando pressure evolutions are further correlated with ex situ plasma focused-ion beam (PFIB) imaging and optical microscopy to reveal the detailed microstructure and morphology of the interface. This work provides valuable insights into the dynamic pressure evolution within SSBs, which can inform future design decisions that promote pressure regulation.

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All‐solid‐state batteries (ASSBs) are emerging as promising candidates for next‐generation energy storage systems. However, their practical implementation faces significant challenges, particularly their requirement for an impractically high stack pressure. This issue is especially critical in high‐energy density systems with limited negative‐to‐positive electrode capacity ratios (N/P ratios), where uneven lithium (Li) stripping induces the formation of interfacial voids. This study addresses these challenges by introducing an anode with a novel structural design that operates effectively under practically viable conditions while significantly reducing the N/P ratio to less than one. The approach entails the integration of a lithiophilic magnesium (Mg) film beneath a thin layer of the silicon‐graphite (SiGr) active materials. This structure facilitates the deposition of excess Li beneath the SiGr layer during overcharging, which enables stable cycling even at room temperature and at a low stack pressure of 3 MPa. By mitigating the poor contact that is characteristic of ASSBs with a low stack pressure, and simultaneously increasing the energy density by lowering the N/P ratio, the design significantly advances the key electrochemical properties of ASSBs.

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Anode-less all-solid-state batteries (ALASSBs) offer unparalleled energy density and enhanced safety. ALASSB cells usually incorporate a protective layer on the anode current collector to stabilize lithium (Li) deposition, yet are...

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Solid-state batteries with Li metal anodes can offer increased energy density compared to Li-ion batteries. However, the performance of pure Li anodes has been limited by morphological instabilities at the interface between Li and the solid-state electrolyte (SSE). Composites of Li metal with other materials such as carbon and Li alloys have exhibited improved cycling stability, but the mechanisms associated with this enhanced performance are not clear, especially at the low stack pressures needed for practical viability. Here, we investigate the structural evolution and correlated electrochemical behavior of Li metal composites containing reduced graphene oxide (rGO) and Li–Ag alloy particles. The nanoscale carbon scaffold maintains homogeneous contact with the SSE during stripping and facilitates Li transport to the interface; these effects largely prevent interfacial disconnection even at low stack pressure. The Li–Ag is needed to ensure cyclic refilling of the rGO scaffold with Li during plating, and the solid-solution character of Li–Ag improves cycling stability compared to other materials that form intermetallic compounds. Full cells with sulfur cathodes were tested at relatively low stack pressure, achieving 100 stable cycles with 79% capacity retention.

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Lithium (Li) metal anodes are widely studied as replacements for current graphite anodes as they have projected higher energy density. However, Li-metal batteries face issues with dendrite propagation and the eventual formation of dead Li. Solid-state batteries (SSBs) are a promising pathway to realize Li-metal batteries, which is attributed to their ability to improve safety and stability through the use of solid-state electrolytes. In particular, “anode-free” SSBs can enable high energy densities by forming a Li metal anode in situ. The initial Li nucleation, plating, and stripping behaviors in anode-free SSBs is influenced not only by the interfacial electrochemistry, but also by the mechanical stresses present along the current collector interface. Mechanical stress also plays a key role in Li metal anode deformation, where creep is the dominant deformation mechanism. However, to date, stack pressure is typically reported as a singular value, rather than considering the temporal and spatial variations in interfacial stress as the battery cycles. This work investigates the role of inhomogeneous stack pressure on Li anode formation and dissolution against a sulfide solid electrolyte. To compensate for this inhomogeneous stack pressure, elastomeric interlayers are used to increase the uniformity of stress along the interface, and thus improve electrochemical cyclability. To analyze the impact of elastomeric interlayers on areal Li plating coverage, post-mortem optical microscopy images of the current collector are captured, showing an improvement in areal coverage from 49% to 70%. The reversible capacity also increases from 89% to 94% with inclusion of an elastomer layer. To confirm the trends in an elastomer layer on increasing stack pressure homogeneity, the mechanical stress at the anode-free interface is modeled using finite-element simulations under different stack pressure geometries. System-level simulations illustrate tradeoffs with respect to the uniformity of mechanical stress and energy density. This work demonstrates the importance of studying external auxiliary components and packaging in SSBs to optimize anode-free SSB performance.

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The development of solid-state batteries (SSBs) is hindered by degradation at solid-solid interfaces due to void formation and contact loss, resulting in increased impedance over time. Here, we systematically divide the metal electrode-solid electrolyte interface area into two categories: recoverable and unrecoverable interfacial contact areas, depending on how they are affected by stack pressure. Unrecoverable contact area is not affected by stack pressure due to the presence of large voids that do not close whereas recoverable contact area can be easily modulated by pressure. The real area of contact lies in the recoverable region, as shown in the figure. Using a steel/Li 6 PS 5 Cl and Li anode/Li 6 PS 5 Cl interface, we investigate the roles of different contact areas in driving the impedance rise. By controlling contact geometries and applied pressures, we identify their distinct contributions to the impedance and quantify their influence on the interfacial resistance and transport. Experiments reveal that interfacial resistance follows power law scaling, with exponents of -1 for recoverable contact area and -0.5 to -0.67 for pressure, respectively. Moreover, distributed contacts result in lower impedance due to smaller potential gradients and a more uniform electrical potential distribution. Simulations of the geometries with unrecoverable contact loss predict interfacial resistances in agreement with experiments. Our work highlights the influence of unrecoverable and recoverable contact losses on SSB impedance while quantifying the effectiveness of mitigation strategies. Figure 1

Sulfide‐based all‐solid‐state batteries (ASSBs) are next‐generation batteries, which resolve the safety issues of energy storage systems. Elaborated intimate contact by providing constant external pressure using a customized cell is a way to overcome chemo‐mechanical deterioration associated with interfacial issues; however, it is not a practical approach. Here, ASSBs are evaluated by adopting a typical coin‐type cell at low pressure (≈0.3 MPa) and it is confirmed that cathode deterioration is a more significant factor in lowering capacity retention than contact loss. Sulfide is infused surprisingly along the grain boundary of the cathode, causing gradual lithium deficiency in the cathode active materials by capturing the active lithium, which is revealed by time‐of‐flight secondary‐ion mass spectroscopy using a lithium isotope (6Li). This study sheds light on the urgency of resolving the depletion of lithium ingredients during cycling rather than surface modification, by investigating the factors that accelerate degradation of the cathode during low‐pressure operation of ASSBs.

The search for safe, reliable, and compact high-capacity energy storage devices has led to increased interest in all-solid-state battery research. The use of solid electrolytes provides enhanced safety and durability due to their reduced flammability and increased mechanical strength compared to organic liquid electrolytes. Still, the use of solid electrolytes remains challenging. A significant issue is their generally low Li-ion conductivity, which depends on the lattice diffusion of Li ions through the solid phase, as well as on the limited contact area between the electrolyte particles. While the lattice diffusion can be addressed through the chemistry of the solid electrolyte material, the contact area is a mechanical and structural problem of packing and compression of the electrolyte particles depending on their size and shape. This work studies the effect of pressurization on the electrolyte conductivity exploring cases of low as well as high grain boundary (GB) conductivity, compared to the bulk conductivity. Scaling dependence, σ ∼ Pη, of the conductivity σ with pressure P is revealed. For an idealized electrolyte represented as spheres in hexagonal closely packed configuration, η = 2/3 and η = 1/3 have been theoretically calculated for the two cases of low and high GB conductivity, respectively. For randomly packed spheres, the equivalent exponent values were numerically estimated to be approximately 3/4 and 1/2, respectively, which are higher than the closed packed values due to the additional decrease of porosity with the increase in pressure. As demonstrated in the study, experimental measurement of η can indicate which type of bulk or GB conductivity is dominant in a particular electrolyte powder and could be used in addition to electrochemical impedance spectroscopy measurements.

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In order to enable the market introduction of all-solid-state batteries (ASSBs), several anode concepts are under investigation to increase the energy density compared to graphite anodes, while maintaining long cycle-life. At the same time, the production costs must be the same or even reduced in comparison with classical lithium-ion batteries. Besides lithium metal as anode material, which still poses significant technical challenges, more and more interest is being directed toward materials that form lithium alloys. One of the most attractive candidates is silicon, which has a low delithiation potential of around 0.45 V vs. Li+/Li and an attractive theoretical gravimetric capacity of 3579 mAh/gSi, which in the fully lithiated state corresponds to a volumetric capacity of ≈2190 mAh/cm3, even higher than the one reachable by lithium metal. Silicon-containing anodes are already being introduced in classical lithium-ion batteries. For that system, the lithium-ion conduction across the anode electrode is mainly provided by the liquid electrolyte that fills the pores of the electrode, while the electrical conduction is enhanced by the addition of graphite and/or conductive carbon additives, because crystalline silicon is only a semiconductor. As is well known, the major issue with silicon anodes is the volume expansion of 300% upon lithiation of silicon, inducing severe cracking of µm-sized silicon particles as well as continuous solid electrolyte interphase (SEI) growth, both of which lead to a fast capacity fading. The intrinsic solid nature of all-solid-state batteries opens the possibility of a new electrode concept that has the potential to mitigate the above-mentioned drawbacks of silicon. Indeed, the silicon particles themselves could be used for the lithium-ion conduction across the electrode, so that anode electrodes can be prepared that are free of electrolyte, thereby largely restricting SEI formation to the anode/separator interface . In this work, anodes with >90% weight of silicon are prepared by coating a water-based slurry that contains microscale silicon particles (ca. 2-4 µm diameter) as active material, the rest being made up of LiPAA and NaCMC as binders as well as C65 carbon as conductive additive. The combination of the water-based process and the microscale dimension of the silicon particles make this electrode concept easily scalable and cost-effective. To reach a competitive areal silicon anode capacity of 3 mAh/cm2, with the full utilization of the silicon, only a thin layer is needed (pristine thickness of 8 µm when the anode porosity is 50%). The thickness variation and the anode morphology are being investigated by examining cross-sectional scanning electron microscopy (SEM) images at different states-of-charge (SOC). After the first complete lithiation, the anode consists of a fully dense and compact Li3.75Si alloy block of 15 µm thickness. Upon its complete delithiation, a peculiar porous columnar morphology is formed that on account of the void space between the columns and within the columns retains a thickness of 11 µm. This peculiar morphology was recently reported in the literature (Tan et al., Science 373 (2021), 1494–1499); and seems to be reversible during subsequent lithiation and delithiation processes. For example, our half-cells utilizing an InLi counter electrode and operating at 70 MPa have more than 80% capacity retention after 350 cycles at a rate of C/5, with an average coulombic efficiency higher than 99.9%. The reason for this promising stability could be attributed to the minimal loss of lithium into the SEI, which is limited to the geometrical contact area between the silicon and the solid electrolyte separator. To better understand the electrochemical and mechanical characteristics of these silicon anodes, they are investigated in full-cells, utilizing an NCM composite cathode, while the anode potential is monitored by using a gold wire micro reference electrode (µ-RE) which was recently developed in our group (Sedlmeier et al., J. Electrochem. Soc. 170 (2023) 030536). This specific µ-RE, which has a defined and stable potential, allows to precisely deconvolute the potential curves of cathode and anode, and also to measure and separate the impedance contributions of the two electrodes. Therefore, the impedance of the silicon anode is measured at different SOC to understand how the contact resistances, the charge-transfer resistance, and the solid-state diffusion affect its overall impedance. In particular, the low impedance at high SOC enables to reach a good fast charging rate capability up to 1C without lithium metal plating and dendrite formation, as reported in Figure 1. However, in order to explore whether the fast charging goal of 4C (80% of the capacity in 15 minutes) can be reached, the influence of the carbon additive, operating temperature and applied pressure are being investigated. Figure 1

The solid‐state batteries (SSBs) with Li anode present one of the most promising energy storage systems due to their enhanced energy density and safety. However, interfacial problems between Li anode and solid‐state electrolyte hinder the advancement of SSBs. Among them, insufficient solid‐solid interfacial contact is the main issue, which causes large resistance and hinders Li+ diffusion, leading to current distribution unevenness and lithium dendrites growth. To meet these challenges, a silver/carbon interlayer composed of ultrafine Ag nanoparticles (≈5 nm) grown on COOH‐CNTs (nano‐Ag@COOH‐CNTs) is constructed. In which, nano‐Ag is designed to guide homogeneous Li deposition, while CNTs substrate bonds with Li6.5La3Zr1.5Ta0.5O12 (LLZTO) electrolyte by reactions between ─COOH groups and LLZTO alkaline surface, thus transforming loose physical solid‐solid contact to chemical bonding contact. In addition, nano‐Ag is immobilized by CNTs, avoiding the migration of Li+ implanted nano‐Ag during cycling. Therefore, nano‐Ag@COOH‐CNTs interlayer can boost Li+ transport at LLZTO/Li interface and inhibit Li dendrites, achieving an ultra‐low interfacial resistance of 0.25 Ω cm2, a high critical current density of 1.7 mA cm−2 and a long cycling over 2155 h at 0.5 mA cm−2. The modified SSBs with LiNi0.83Co0.12Mn0.05O2 cathode cycles stably over 500 cycles. Moreover, high‐loading SSBs operate stably for 85 cycles.

All‐solid‐state lithium metal batteries (ASSLMBs) with solid electrolytes (SEs) have emerged as a promising alternative to liquid electrolyte‐based Li‐ion batteries due to their higher energy density and safety. However, since ASSLMBs lack the wetting properties of liquid electrolytes, they require stacking pressure to prevent contact loss between electrodes and SEs. Though previous studies showed that stacking pressure could impact certain performance aspects, a comprehensive investigation into the effects of stacking pressure has not been conducted. To address this gap, we utilized the Li6PS5Cl solid electrolyte as a reference and investigated the effects of stacking pressures on the performance of SEs and ASSLMBs. We also developed models to explain the underlying origin of these effects and predict battery performance, such as ionic conductivity and critical current density. Our results demonstrated that an appropriate stacking pressure is necessary to achieve optimal performance, and each step of applying pressure requires a specific pressure value. These findings can help explain discrepancies in the literature and provide guidance to establish standardized testing conditions and reporting benchmarks for ASSLMBs. Overall, this study contributes to the understanding of the impact of stacking pressure on the performance of ASSLMBs and highlights the importance of careful pressure optimization for optimal battery performance.

Solid-state Li-metal batteries have the potential to achieve both high safety and high energy densities. Among various solid-state fast-ion conductors, the garnet-type Li7La3Zr2O12 (LLZO) is one of the few that are stable to Li metal. However, the large interfacial resistance between LLZO and cathode materials severely limits the practical application of LLZO. Here a LiCoO2 (LCO) film was deposited onto an Al-doped LLZO substrate at room temperature by aerosol deposition, and a low interfacial resistance was achieved. The LCO particles were precoated by Li3BO3 (LBO), which melted to join the LCO particles to the LLZO substrate at heating. All-solid-state Li/LLZO/LBO-LCO cells could deliver an initial discharge capacity of 128 mAh g–1 at 0.2 C and 60 °C and demonstrated relatively high capacity retention of 87% after 30 cycles. The cell degradation mechanism was studied by electrochemical impedance spectroscopy (EIS) and was found to be mainly related to the increase of the interfacial resistance between LBO and LCO. In-situ SEM analysis verified the hypothesis that the increase of the interfacial resistance was caused primarily by interfacial cracking upon cycling. This study demonstrated the capability of EIS as a powerful nondestructive in-situ technique to investigate the failure mechanisms of all-solid-state batteries.

Na3Zr2Si2PO12 (NZSP) electrolyte with excellent air stability and acceptable ionic conductivity demonstrates a significant potential for application in solid‐state Na metal batteries. However, the poor interfacial contact between NZSP and Na anode has severely hindered its practical application. Herein, a BiCl3/polytetrafluoroethylene flexible interface layer is constructed between NZSP and Na metal anode. BiCl3 can react with Na metal to form a multifunctional NaxBi/NaCl‐rich flexible interface layer during the cycling process, which can effectively enhance the interfacial contact, avoid the formation of voids and reduce the interfacial resistance. NaxBi with low energy barrier can provide fast Na+ diffusion path, and NaCl with a wide band gap can inhibit electron injection and suppress Na dendrite growth. Owing to the multifunctional NaxBi/NaCl flexible interface layer, the Na/BiCl3@NZSP/Na symmetric cell exhibits a reduced interfacial resistance from 1252.1 to 67.6 Ω and achieves a high critical current density of 2 mA cm⁻2 at 25 °C. At 0.1 mA cm⁻2/0.1 mAh cm⁻2 and 0.3 mA cm⁻2/0.3 mAh cm⁻2, the symmetric cell can stably cycle for 3000 and 1100 h. Additionally, the Na3V2(PO4)3/BiCl3@NZSP/Na full cell can retain 96.7% of initial capacity (≈111 mAh g−1) after 300 cycles at 0.5 C and excellent rate capability.

All-solid-state lithium metal batteries (ASSLMBs) hold great promise for next-generation energy storage, offering high safety and energy density. However, their practical realization remains limited by limited lithium reversibility, insufficient battery loading, and the need for high temperature and pressure during operation. These challenges stem from both interfacial instabilities and intrinsic issues within bulk of solid-state electrolytes (SSEs). Fundamentally, solid-state systems face two key limitations compared to liquid systems: restricted chemical tunability and mechanical inability to accommodate uneven stress. Unlike organic liquid electrolytes, inorganic SSEs lack compositional flexibility, making it difficult to tailor favorable interphases. Meanwhile, intrinsic defects and grain boundaries in SSEs provide pathways for dendrite propagation. Futhermore, SSEs are unable to naturally accommodate the volume changes or stress concentrations associated with large volume changes of electrodes, further compromising stability. To address these challenges, we introduced a molecular-level strategy that leverages the versatility of organic chemistry to engineer the surface of inorganic SSEs. We discovered a family of reductive electrophiles that spontaneously form a lithiophobic, electron-insulating interphase on SSE particle surfaces. This uncovered interphase chemistry not only stabilizes both the Li/SSE and cathode/SSE interfaces, but also suppresses dendrite growth within the bulk. As a result, the modified SSEs achieve a high lithium Coulombic efficiency of 99.7%, and the resulting ASSLMBs demonstrate long-term cycling at room temperature (30 ℃) and low stack pressure (2.5 MPa) under high-loading conditions. This approach offers a universal, composition-independent route to interface engineering and is broadly applicable across diverse battery materials. Looking ahead, we will also discuss strategies to address the mechanical challenges in ASSLMBs, aiming to further enhance lithium reversibility and enable thin-Li and anode-free architectures.

Silicon-based all-solid-state batteries offer high energy density and safety but face significant application challenges due to the requirement of high external pressure. In this study, a Li21Si5/Si–Li21Si5 double-layered anode is developed for all-solid-state batteries operating free from external pressure. Under the cold-pressed sintering of Li21Si5 alloys, the anode forms a top layer (Li21Si5 layer) with mixed ionic/electronic conduction and a bottom layer (Si–Li21Si5 layer) containing a three-dimensional continuous conductive network. The resultant uniform electric field at the anode|SSE interface eliminates the need for high external pressure and simultaneously enables a twofold enhancement of the lithium-ion flux at the anode interface. Such an efficient ionic/electronic transport system also facilitates the uniform release of cycling expansion stresses from the Si particles and stabilizes bulk-phase and interfacial structure of anode. Consequently, the Li21Si5/Si–Li21Si5 anode exhibited a critical current density of 10 mA cm−2 at 45 °C with a capacity of 10 mAh cm−2. And the Li21Si5/Si–Li21Si5|Li6PS5Cl|Li3InCl6|LCO cell achieve an high initial Coulombic efficiency of (97 ± 0.7)% with areal capacity of 2.8 mAh cm−2 at 0.25 mA cm−2, as well as a low expansion rate of 14.5% after 1000 cycles at 2.5 mA cm−2. Si-based all-solid-state batteries face application challenges due to the requirement of high external pressure. Here, authors prepare a double-layered Si-based electrode by cold-pressing and electrochemical sintering that enables all-solid-state batteries operating free from external pressure.

Solid-state lithium metal batteries with garnet-type electrolyte provide several advantages over conventional lithium-ion batteries, especially for safety and energy density. However, a few grand challenges such as the propagation of Li dendrites, poor interfacial contact between the solid electrolyte and the electrodes, and formation of lithium carbonate during ambient exposure over the solid-state electrolyte prevent the viability of such batteries. Herein, an ultrathin sub-nanometer porous carbon nanomembrane (CNM) is employed on the surface of solid-state electrolyte (SSE) that increases the adhesion of SSE with electrodes, prevents lithium carbonate formation over the surface, regulates the flow of Li-ions, and blocks any electronic leakage. The sub-nanometer scale pores in CNM allow rapid permeation of Li-ions across the electrode-electrolyte interface without the presence of any liquid medium. Additionally, CNM suppresses the propagation of Li dendrites by over sevenfold up to a current density of 0.7 mA cm-2 and enables the cycling of all-solid-state batteries at low stack pressure of 2 MPa using LiFePO4 cathode and Li metal anode. The CNM provides chemical stability to the solid electrolyte for over 4 weeks of ambient exposure with less than a 4% increase in surface impurities.

All-solid-state lithium metal batteries are highly attractive because of their high energy density and inherent safety. However, it is still a great challenge to design the solid electrolytes with high ionic conductivity at room temperature and good electrode/electrolyte interfacial compatibility simultaneously in a facile and scalable way. In this work, for the first time, the combination of salt affluent PEO with Li6.75La3Zr1.75Ta0.25O12 nanofibers was designed and intensively evaluated. The synergistic effect of each component in the electrolyte enhances the ionic conductivity to 2.13 × 10-4 S cm-1 at 25 °C and exhibits a high transference number of 0.57. The composite electrolyte possesses superior interfacial stability against Li metal for over 680 h in Li symmetric cells even at a relatively high current density of 2 mA cm-2. The all-solid-state batteries employing the solid electrolytes exhibit excellent cycling stability at room temperature and superior safety performance. This work proposes a brand-new strategy to design and fabricate solid electrolyte in a versatile way for room temperature all-solid-state batteries.

Polymer-inorganic composite electrolytes (PICE) have attracted tremendous attention in all-solid-state lithium batteries (ASSLBs) due to facile processability. However, the poor Li+ conductivity at room temperature (RT) and interfacial instability severely hamper the practical application. Herein, we propose a concept of competitive coordination induction effects (CCIE) and reveal the essential correlation between the local coordination structure and the interfacial chemistry in PEO-based PICE. CCIE introduction greatly enhances the ionic conductivity and electrochemical performances of ASSLBs at 30°C. Owing to the competitive coordination (Cs+…TFSI-…Li+, Cs+…C-O-C…Li+ and 2,4,6-TFA…Li…TFSI-) from the competitive cation (Cs+ from CsPF6) and molecule (2,4,6-TFA: 2,4,6-trifluoroaniline), a multimodal weak coordination environment of Li+ is constructed enabling a high efficient Li+ migration at 30oC (Li+ conductivity: 6.25×10-4 S cm-1; tLi+ = 0.61). Since Cs+ tends to be enriched at the interface, TFSI- and PF6-in-situ form LiF-Li3N-Li2O-Li2S enriched solid electrolyte interface with electrostatic shielding effects. The assembled ASSLBs without adding interfacial wetting agent exhibit outstanding rate capability (LiFePO4: 147.44mAh g-1@1C and 107.41mAhg-1@2C) and cycling stability at 30oC (LiFePO4:94.65%@200cycles@0.5C; LiNi0.5Co0.2Mn0.3O2: 94.31%@200cycles@0.3C). This work proposes a concept of CCIE and reveals its mechanism in designing PICE with high ionic conductivity as well as high interfacial compatibility at near RT for high-performance ASSLBs.

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The interlaboratory comparability and reproducibility of all-solid-state battery cell cycling performance are poorly understood due to the lack of standardized set-ups and assembly parameters. This study quantifies the extent of this variability by providing commercially sourced battery materials—LiNi0.6Mn0.2Co0.2O2 for the positive electrode, Li6PS5Cl as the solid electrolyte and indium for the negative electrode—to 21 research groups. Each group was asked to use their own cell assembly protocol but follow a specific electrochemical protocol. The results show large variability in assembly and electrochemical performance, including differences in processing pressures, pressing durations and In-to-Li ratios. Despite this, an initial open circuit voltage of 2.5 and 2.7 V vs Li+/Li is a good predictor of successful cycling for cells using these electroactive materials. We suggest a set of parameters for reporting all-solid-state battery cycling results and advocate for reporting data in triplicate. More transparent protocol reporting and comprehensive battery cell data are needed. Twenty-one research groups joined forces to assess solid-state battery performance and found considerable differences in assembly protocols that cause variable results.

Composite solid electrolytes (CSEs), which combine the advantages of solid polymer electrolytes and inorganic solid electrolytes, are considered to be promising electrolytes for all-solid-state lithium metal batteries. However, the current CSEs suffer from defects such as poor inorganic/organic interface compatibility, lithium dendrite growth, and easy damage of electrolyte membrane, which hinder the practical application of CSEs. Herein, a CSE (PBHL@LLZTO@DDB) with polyurethane (PBHL) as the polymer matrix and Li6.4La3Zr1.4Ta0.6O12 (LLZTO) modified by silane coupling agent (DDB) as inorganic fillers (LLZTO@DDB) has been prepared. Disulfide bond exchange reactions between PBHL and LLZTO@DDB enable PBHL@LLZTO@DDB to form a dynamic three-dimensional (3D) inorganic/organic hybrid network, which promotes the uniform dispersion of LLZTO in PBHL@LLZTO@DDB, improves the Li+ conductivity (1.24 ± 0.08 × 10-4 S cm-1 at 30 ℃), and broadens the electrochemical stability window (5.16 V vs. Li+/Li). Moreover, a combination of hydrogen bonds and disulfide bonds endows PBHL@LLZTO@DDB with excellent self-healing properties. As such, both all-solid-state symmetric and full cells exhibit excellent cycle performance at ambient temperature. More importantly, the healed PBHL@LLZTO@DDB can almost completely restore its original electrochemical properties, indicating its application potential in flexible electronic products.

Thermally stable catholyte buffer layer was fabricated via incorporating a multi-functional flame-retardant triphenyl phosphate additive into poly(ethylene oxide). The optimized catholyte buffer layer enabled thermal and electrochemical stability at interface level, delivering comparable cycling stability of garnet-based all solid-state lithium battery, i.e., capacity retention of 98.5% after 100 cycles at 60 °C, and 89.6% after 50 cycles at 80 °C. Exceptional safety performances were demonstrated, i.e., safely cycling behavior at temperature up to 100 °C and spontaneous fire-extinguishing ability. Thermally stable catholyte buffer layer was fabricated via incorporating a multi-functional flame-retardant triphenyl phosphate additive into poly(ethylene oxide). The optimized catholyte buffer layer enabled thermal and electrochemical stability at interface level, delivering comparable cycling stability of garnet-based all solid-state lithium battery, i.e., capacity retention of 98.5% after 100 cycles at 60 °C, and 89.6% after 50 cycles at 80 °C. Exceptional safety performances were demonstrated, i.e., safely cycling behavior at temperature up to 100 °C and spontaneous fire-extinguishing ability. The pursuit of safer and high-performance lithium-ion batteries (LIBs) has triggered extensive research activities on solid-state batteries, while challenges related to the unstable electrode–electrolyte interface hinder their practical implementation. Polymer has been used extensively to improve the cathode-electrolyte interface in garnet-based all-solid-state LIBs (ASSLBs), while it introduces new concerns about thermal stability. In this study, we propose the incorporation of a multi-functional flame-retardant triphenyl phosphate additive into poly(ethylene oxide), acting as a thin buffer layer between LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode and garnet electrolyte. Through electrochemical stability tests, cycling performance evaluations, interfacial thermal stability analysis and flammability tests, improved thermal stability (capacity retention of 98.5% after 100 cycles at 60 °C, and 89.6% after 50 cycles at 80 °C) and safety characteristics (safe and stable cycling up to 100 °C) are demonstrated. Based on various materials characterizations, the mechanism for the improved thermal stability of the interface is proposed. The results highlight the potential of multi-functional flame-retardant additives to address the challenges associated with the electrode–electrolyte interface in ASSLBs at high temperature. Efficient thermal modification in ASSLBs operating at elevated temperatures is also essential for enabling large-scale energy storage with safety being the primary concern.

All‐solid‐state batteries are emerging as potential successors in energy storage technologies due to their increased safety, stemming from replacing organic liquid electrolytes in conventional Li‐ion batteries with less flammable solid‐state electrolytes. However, all‐solid‐state batteries require precise control over cycling pressure to maintain effective interfacial contacts between materials. Traditional uniaxial cell holders, often used in battery research, face challenges in accommodating electrode volume changes, providing uniform pressure distribution, and maintaining consistent pressure over time. This study introduces isostatic pouch cell holders utilizing air as pressurizing media to achieve uniform and accurately regulated cycling pressure. LiNi0.8Co0.1Mn0.1O2 | Li6PS5Cl | Si pouch cells are fabricated and tested under 1 to 5 MPa pressures, revealing improved electrochemical performance with higher cycling pressures, with 2 MPa as the minimum for optimal operation. A bilayer pouch cell with a theoretical capacity of 100 mAh, cycled with an isostatic pouch cell holder, demonstrated a first‐cycle Coulombic efficiency of 76.9% and a discharge capacity of 173.6 mAh g−1 (88.1 mAh), maintaining 83.6% capacity after 100 cycles. These findings underscore the effectiveness of isostatic pouch cell holders in enhancing the performance and practical application of all‐solid‐state batteries.

All-solid-state sodium batteries (ASSSBs) are promising candidates for grid-scale energy storage. However, there are no commercialized ASSSBs yet, in part due to the lack of a low-cost, simple-to-fabricate solid electrolyte (SE) with electrochemical stability towards Na metal. In this work, we report a family of oxysulfide glass SEs (Na3PS4−xOx, where 0 < x ≤ 0.60) that not only exhibit the highest critical current density among all Na-ion conducting sulfide-based SEs, but also enable high-performance ambient-temperature sodium-sulfur batteries. By forming bridging oxygen units, the Na3PS4−xOx SEs undergo pressure-induced sintering at room temperature, resulting in a fully homogeneous glass structure with robust mechanical properties. Furthermore, the self-passivating solid electrolyte interphase at the Na|SE interface is critical for interface stabilization and reversible Na plating and stripping. The new structural and compositional design strategies presented here provide a new paradigm in the development of safe, low-cost, energy-dense, and long-lifetime ASSSBs. Single sodium-ion solid electrolyte that meets the requirements of practical applications is difficult to design. Here, the authors show how kinetic stability via the creation of a self-passivating solid electrolyte interphase allows a homogenous glass solid electrolyte to exhibit remarkable electrochemical stability with sodium metal.

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Understanding the electrochemical reactions at the interface between a Si anode and a solid sulfide electrolyte is essential in improving the cycle stabilities of Si anodes in all-solid-state batteries (ASSBs). Highly dense Si films with very low roughnesses of <1 nm were fabricated at room temperature via cathodic arc plasma deposition, which led to the formation of a Si/sulfide electrolyte model interface. Li (de)alloying through the model interface hardly occurred during the first cycle, whereas it proceeded stably in subsequent cycles. Hard X-ray photoelectron spectroscopy and neutron reflectometry directly revealed that the reduction or oxidation of the interfacial component or Li3PS4 electrolyte occurred during the first cycle. Consequently, an interfacial layer with a thickness of 13 nm and primarily composed of Li2S, SiS2, and P2S5 glasses was formed during the first cycle. The interfacial layer acted as a Li-conductive, electron-insulating solid electrolyte interphase (SEI) that provided reversible (de)lithiation. Our model interface directly demonstrates the electrochemical reaction processes at the Si/Li3PS4 interface and provides insights into the structures and electrochemical properties of SEIs to activate the (de)lithiation of Si anodes using a sulfide electrolyte.

Composite electrolytes have received widespread attention due to their potential to simultaneously integrate the advantages of different types of electrolytes. However, composite electrolytes based on sulfides and polymers electrolyte still face issues such as instability toward lithium metal, low ion transference number, and instability between polymers and sulfides. Based on this, a composite electrolyte based on a continuous conductive Li5.4PS4.4Cl1.6(LPSC) framework with polytetrafluoroethylene (PTFE) is prepared as a binder (LPSC@PTFE) and gel electrolyte containing high concentration lithium salt. The gel electrolyte fills the pores in the LPSC@PTFE membrane and protects the interface between the sulfide electrolyte and lithium metal. In addition, high‐concentration electrolytes exhibit better stability compared to low‐concentration electrolytes, whether for lithium metal or sulfides. The improvement has been demonstrated in stability through analysis of in‐situ electrochemical impedance spectroscopy (EIS) combined with relaxation time distribution (DRT), as well as characterization by X‐ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The mechanism behind the performance enhancement through theoretical calculations and simulations has also been speculated on. The optimized composite electrolyte membrane has an electrochemical window of 4.98 V, an increased ion transference number of 0.74, a critical current density of 1.8 mA cm−2@0.1 mAh cm−2, and can cycle for more than 4000 h at a current density of 0.1 mA cm−2@0.1 mAh cm−2. After matching with LiFePO4 (LFP) cathode, the capacity retention rate is 94.1% after 150 cycles at a rate of 1C and 89.7% after 150 cycles at a rate of 2C.

All‐solid‐state lithium batteries (ASSLBs) are considered a promising technology for next‐generation energy storage systems due to their inherent safety. However, the conventional laboratory‐scale ASSLBs reported to date are based on pellet‐type structures with thick solid electrolyte layers, leading to challenges related to low energy densities and poor electrochemical performance. In this study, porous adhesive poly(ethylene vinyl acetate) (PEVA) scaffolds and polytetrafluoroethylene (PTFE) binders are utilized to interweave sulfide solid electrolytes into freestanding films with an ultra‐low thickness of 40 µm, high ionic conductivity of 1.1 mS cm−1, and a high tensile strength of 74 MPa. To mitigate the reduction reaction between the PTFE binder and the lithium metal anode, a Li3N‐rich solid electrolyte interphase (SEI) in situ on lithium metal is formed, and the assembled symmetric cell shows excellent cycling stability within 800 h at the current density of 0.2 mA cm−2 and room temperature. Additionally, the ASSLBs using oxidatively stable Li2ZrCl5F in the composite cathode and the prepared solid electrolyte film demonstrate exceptional cycling performance and fast‐charging capability, with a high cell‐level energy density of 354.4 Wh kg−1. The ASSLBs prepared by coupling E‐LPSCl film and stable interface design exhibit excellent electrochemical performance and a high cell‐level energy density.

All-solid-state lithium batteries, including sulfide electrolytes and nickel-rich layered oxide cathode materials, promise safer electrochemical energy storage with high gravimetric and volumetric densities. However, the poor electrical conductivity of the active material results in the requirement for additional conducive additives, which tend to react negatively with the sulfide electrolyte. The fundamental scientific principle uncovered through this work is simple and suggests that the electrical network benefits associated with the introduction of short-length carbons will eventually be overpowered by the increase in bulk resistance associated with their instability in the sulfide electrolyte. However, applying just the right amount of short carbon fibres minimizes degradation of the sulfide solid electrolyte and maximizes the electron movement. Therefore, we propose the application of a low-weight-percent carbon nanotubes (CNTs) coating on the nickel-rich cathode LiNi0.8Co0.1Mn0.1O2 (NCM811) along with large-aspect-ratio carbon nanofibers (CNFs) as the primary conductive additive. When only 0.3 wt % CNTs was utilized with 4.7 wt % CNFs, an initial Coulombic efficiency of 83.55% at 0.05C and a notably excellent capacity retention of 90.1% over 50 cycles at 0.5C were achieved along with a low ionic resistance. This work helps to confirm the validity of applying short carbon pathways in sulfide-electrolyte-based cathode composites and proposes their combination with a larger primary carbon additive as a solution to the ongoing all-solid-state battery rate and instability issues.

Metal fluorides are conversion‐type cathodes that have the potential to boost the energy densities of next generation lithium‐ion batteries (LIBs). However, the study of non‐transitional metal fluorides (NTMFs) such as bismuth trifluoride (BiF3) is limited due to the challenges on the construction of a stable electrochemical reaction interfaces with liquid electrolyte, although it shows advantages on high electrochemical potential, moderately high theoretical capacity and low voltage hysteresis. Moreover, the performance of BiF3 in all solid state batteries (ASSBs) has not been explored. In this contribution, the micro‐sized commercial BiF3 is successfully coated with a cyclic polyacrylonitrile (cPAN) and refined its size to nanoscale. The refined nano‐sized BiF3@cPAN uniformly disperses in the solid electrode and delivers an initial discharge capacity of 330 and 200 mAh g−1 after 250 cycles in sulfide electrolyte based ASSBs. Furthermore, the voltage hysteresis of the ASSBs reaches a record low value of 180 mV. Postmortem analysis shows that the elastic coating hindered the undesirable interface side reaction and rendered the BiF3 with excellent cycle reversibility. This work demonstrates the crucial role of stable interfaces for BiF3 in preventing electrolyte decomposition, which promotes the practical adoption of BiF3 cathode with higher specific energy for LIBs.

FeS2 cathode is promising for all‐solid‐state lithium batteries due to its ultra‐high capacity, low cost, and environmental friendliness. However, the poor performances, induced by limited electrode‐electrolyte interface, severe volume expansion, and polysulfide shuttle, hinder the application of FeS2 in all‐solid‐state lithium batteries. Herein, an integrated 3D FeS2 electrode with full infiltration of Li6PS5Cl sulfide electrolytes is designed to address these challenges. Such a 3D integrated design not only achieves intimate and maximized interfacial contact between electrode and sulfide electrolytes, but also effectively buffers the inner volume change of FeS2 and completely eliminates the polysulfide shuttle through direct solid–solid conversion of Li2S/S. Besides, the vertical 3D arrays guarantee direct electron transport channels and horizontally shortened ion diffusion paths, endowing the integrated electrode with a remarkably reduced interfacial impedance and enhanced reaction kinetics. Benefiting from these synergies, the integrated all‐solid‐state lithium battery exhibits the largest reversible capacity (667 mAh g−1), best rate performance, and highest capacity retention of 82% over 500 cycles at 0.1 C compared to both a liquid battery and non‐integrated all‐solid‐state lithium battery. The cycling performance is among the best reported for FeS2‐based all‐solid‐state lithium batteries. This work presents an innovative synergistic strategy for designing long‐cycling high‐energy all‐solid‐state lithium batteries, which can be readily applied to other battery systems, such as lithium‐sulfur batteries.

The quality of Li–solid electrolyte interface is crucial for the performance of solid-state lithium metal batteries, particularly at low stack pressure, but its dynamics during cell operation remain poorly understood due to a lack of reliable operando characterization techniques. Here, we report the evolution of Li–electrolyte interface with high spatial resolution using operando scanning electron microscopy under realistic operating conditions. By tracking the stripping process of both Li and Li-rich Li-Mg alloy anodes, we show that multiple voids coalesce into a single gap and eventually delaminate the interface in Li, whereas the voids split and collapse to partially recover interfacial contact in Li-Mg. Density functional theory calculations show that the stronger Mg-S interaction at the metal–electrolyte interface attracts Mg toward the interface and repels Li-vacancies into the bulk, resulting in a reduced number of voids. The pressure-dependent voltage profiles of Li and Li-Mg stripping suggest that loss of contact due to void formation, rather than Mg accumulation at the interface, is the origin of high overpotential that limits the utilization of metal anodes. Improved interfacial contact enables stable cycling of all-solid-state lithium full cell at low stack pressure (1 MPa) and moderate rate (2 mA cm−2) simultaneously. The real-time visualization of Li–electrolyte interface dynamics provides critical insights into the rational design of solid-state battery interfaces. The quality of the Li–electrolyte interface is key to solid-state battery performance, especially at low pressure. Here, authors use operando electron microscopy to reveal how Li-Mg alloy anodes improve interfacial contact and low-pressure cycling stability by suppressing void formation.

A critical challenge facing silicon-based anodes in all-solid-state lithium-ion batteries (ASSLBs) is the need for high stack pressure to maintain good interfacial contact (often up to tens of megapascals). However, bulky pressurization systems degrade the energy density and increase the cost of ASSLBs. Herein, a modified silicon anode is proposed to achieve stable operation of sulfide ASSLBs without extra external pressure. LiBO2 and LiF phases are in situ constructed on the surface of nano silicon by a simple solid phase reaction. Chemical analysis, theoretical calculations, and simulations all demonstrate that the uniformly distributed LiBO2 improves lithium storage kinetics, while LiF acts as a mechanical buffer phase. Its high Young's modulus not only restrains the large volume expansion of silicon but also preserves the structural integrity of the electrode-electrolyte interface by dispersing lithiation stress. This ingenious interface architecture eliminates bulky external pressurization and enables high energy density ASSLBs.

Solid-state batteries are expected to provide holistic solutions to overcome major growth barriers in the EV market, with its higher energy density, faster charging rate, intrinsic safety, and potentially better affordability. Sulfide-based electrolyte is attracting extensive interest among other solid electrolyte chemistries, owing to its outstanding conductivity and processibility at ambient temperature. According to multiple announcements from battery manufacturers and OEMs, the sulfide-based all-solid-state batteries are believed to be only a few years away from its start of production for EV applications. As demonstrated in literature, the sulfide solid electrolyte is not stable with lithium metal. To be competitive with other technologies, the sulfide solid electrolyte could be combined with lithium metal, and the obtained all-solid-state batteries demonstrate comparable performances at high c-rate. But the dendrite formation or cracks are observed, even if high pressure is applied. This presentation will address the remaining challenges of sulfide-electrolyte film and interfaces with lithium metal. The development of new “binders” for sulfide film electrolyte will be presented with the demonstration of relationship of solid electrolyte ceramic film composition, binder, density, flexibility to offer high conductivity and easily manipulation. With stabilized lithium metal interface and specific properties of solid electrolyte film by binder development, more than 700 cycles under industry-relevant pressure conditions at moderate temperature under pouch-cell configuration were obtained. The complementarity between binder properties, mixing, preparation and electrochemical measurements will be explained with technical and economical issues to bring the technology closer to the market.

Achieving chemical and electrochemical stability of sulfide‐based solid electrolytes is crucial for enabling practical slurry fabrication and reliable operation of all‐solid‐state batteries (ASSBs). Herein, a fluorocarbon‐terminated self‐assembled monolayer (SAM) strategy is reported that forms a conformal and chemically inert surface on Li6PS5Cl (LPSCl), yielding a stabilized catholyte (─CF3@LPSCl) compatible with polar solvent‐based processing. The SAM layer effectively suppresses nucleophilic degradation induced by ester solvents and moisture while maintaining the crystalline bulk structure and high ionic conductivity of LPSCl. The surface fluorination simultaneously enhances both chemical and electrochemical stability, characterized by X‐ray absorption near‐edge structure measurements, enabling high‐rate capability and stable cycling under 1.0 C conditions. Under low stack pressure (≈0.3 MPa), the ─CF3@LPSCl catholyte suppresses not only the catholyte degradation but also alleviates mechanical contact loss within the cathode, achieving superior cycling stability without reliance on binder reinforcement. Notably, full cells assembled with thin Li metal and a low N/P ratio exhibit 90.5% capacity retention over 300 cycles. This work demonstrates that a simple but straightforward fabrication of surface‐stable catholyte—beyond binder and electrode engineering—can play a decisive role in achieving scalable and pressure‐tolerant ASSBs platforms.

Introduction The all-solid-state Li-ion battery is expected to be a next-generation battery owing to its enhanced safety and high rate-capability ascribed to sulfide solid electrolytes (SEs) having incombustibility and high ionic conductivity. However, low cyclability hinders their practical application. Since the oxidative decomposition of the sulfide SE in the positive electrode is known as one of the main degradation modes, bilayer SE cells are promising to suppress the degradation where the chloride SE having relatively high stability against oxidation is placed on the positive electrode side and the reduction-resistive sulfide SE is placed on the negative electrode side. [1]. While it is reported that the interface between the sulfide and chloride SEs is not chemically stable and interphases are formed between the SEs [1], the effect of the interphase on the Li-ion transport between the sulfide and chloride SEs has not been investigated. As a way to analyze the resistance between two SEs, we have recently established an all-solid-state electrochemical four-electrode cell using a partially reduced lithium titanate (R-LTO) reference electrode (RE) [2,3]. Experimental In this study, we apply the electrochemical four-electrode cell to the sulfide SE | chloride SE interfaces to analyze the Li-ion transport resistance. The glass-ceramic Li2S-P2S5-LiI (LPSI) was synthesized by the method reported by X. Feng et al. [4]. The chloride SEs, Li3InCl6 (LIC), Li3SrCl6 (LSC), and Li3YCl6 (LYC) were synthesized following the previous report [1]. The ionic conductivities and activation energies of the LPSI, LIC, LSC, and LYC were measured to be 2.1, 0.36, 0.5 and 0.28 mS cm–1 at 25 °C, and 29.8, 33.5, 38.5 and 38.6 kJ mol–1, respectively. The R-LTO REs were fabricated by the previously reported method [2]. All-solid-state four-electrode cells (Fig. 1(a)) were fabricated in the following way. First, the LPSI pellet incorporating the R-LTO was fabricated by hand pressing in a mold. Then, the chloride SE powder was sandwiched with the LPSI layers followed by cold pressing at ca. 290 MPa. Finally, Li-In foil synthesized with a chemical lithiation of the In foil was put on the outer sides of the stacked pellet as the counter electrodes (CEs) [2]. Electrochemical impedance spectroscopy (EIS) was conducted between 50 mHz and 7 MHz with an AC amplitude of 10 mV at OCV using an electrochemical measurement system (VSP-300, BioLogic). Results and Discussion Fig. 1(b) shows the impedance spectrum obtained by EIS using a pristine LIC | LPSI cell at 25 °C. Two semicircles P 1 and P 2 are found in higher and lower frequency regions and assigned as bulk and interfacial Li-ion transfer from the frequency response [2]. The interfacial resistance of the LPSI | LIC | LPSI cell shows a continuous increase at 25 °C, though it does not change significantly at –5 °C. This result indicates that the resistive interphase is formed by a chemical reaction. The growth ratios of the interfacial resistances of the LPSI | LIC | LPSI, LPSI | LYC | LPSI, and LPSI | LSC | LPSI cells for 50 h are 2.2,1.6 and 1.4 respectively. References 1) M. Chandrappa et al., J. Am. Chem. Soc., 144, 18009 (2022). 2) K. Yoshida et al., submitted to Electrochim. Acta (2024). 3) A. Ikezawa et al., Electrochem. Commun., 116, 1067433 (2020). 4) X. Feng et al., Energy Storage Mater., 22, 397 (2019). Acknowledgment This work was supported by JSPS KAKENHI Grant Number JP22H04608. Figure 1

Developing solid-state batteries (SSB) with a lithium metal electrode (LME) using only one type of solid electrolyte (SE) is a significant challenge since no SE fits all the requirements imposed by both electrodes. A possible solution is using multilayer SSBs with an LME where the drawbacks of each SE are overcome by using layers of different SEs. However, research on inorganic SE1|SE2 heteroionic interfaces is still quite preliminary, especially regarding oxide|sulfide heteroionic interfaces. This work reports the electrochemical investigation of the heteroionic interface between Li6.25Al0.25La3Zr2O12 (Al-LLZO) and two representative materials for sulfide-based SEs: argyrodite-based Li6PS5Cl (LPSCl) and glass-like Li7P3S11 (LPS711). Through in-depth temperature- and pressure-dependent impedance analyses of multilayer symmetric cells at equilibrium (i.e., no current load), the electrical properties of the heteroionic interfaces are assessed. The pressure-dependent kinetic of the Al-LLZO|LPSCl pair is interpreted with the concept of geometric constriction resistance and show that its resistance is lower than for the Al-LLZO|LPS711 pair. Furthermore, the effect of Al-LLZO surface treatment on the electrical properties of the Al-LLZO|LPSCl heteroionic interface is evaluated. Such investigation shows that the value of the interface activation energy decreases when the Al-LLZO surface is heat treated, revealing a significant influence of the carbonate/hydroxide passivation layer on the heteroionic interface. Additionally, by cycling the symmetric cell for 900 h at 1.0 mAh·cm-2, it is revealed that the Al-LLZO|LPSCl interface has a lower impedance increase than the Al-LLZO|LPS711 interface, especially if the Al-LLZO is heat treated. With this work, we highlight that the oxide|argyrodite combination can be a promising candidate for multilayer SSBs with an LME. However, we show that an optimized LLZO surface treatment and chemical analysis of the interface are recommended for future research.

Sulfide solid state electrolytes (SSE) are among the most promising materials in the effort to replace liquid electrolytes, largely due to their comparable ionic conductivities. Among the sulfide SSEs, Argyrodites (Li6PS5X, X=Cl, Br, I) further stand out due to their high theoretical ionic conductivity (~1×10-2 S cm-1) and interfacial stability against reactive metal anodes such as lithium. Generally, solid state electrolyte pellets are pressed from powder feedstock at room temperature, however, pellets fabricated by cold pressing consistently result in low bulk density and high porosity, facilitating interfacial degradation reactions and allowing dendrites to propagate through the pores and grain boundaries. Here, we demonstrate the mechanical and electrochemical implications of hot-pressing standalone LPSCl SSE pellets with near-theoretical ionic conductivity, superior cycling performance, and enhanced mechanical stability. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and x-ray diffraction spectroscopy (XRD) analysis reveal no chemical changes to the Argyrodite surface after hot pressing up to 250 °C. Moreover, we use electrochemical impedance spectroscopy (EIS) to understand mechanical stability of Argyrodite SSE pellets as a function of externally applied pressure, demonstrating for the first time pressed standalone Argyrodite pellets with near-theoretical conductivities at external pressures below 14 MPa.

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The high interfacial resistance between an electrode and a solid electrolyte remains a critical problem needed to be addressed for the practical application of all-solid-state batteries (ASSBs). While introducing an interlayer is a promising strategy to mitigate this resistance, the unclear action mechanism of the interlayer on the interfacial Li+ transport impedes further development. Herein, employing a first-principles-informed thermodynamic model, we demonstrate an effective approach for modulating the space–charge layers and electrostatic barriers for Li+ transport at the β-Li3PS4/LixCoO2 interfaces by incorporating a LiAlO2 interlayer in Li/β-Li3PS4/LixCoO2 ASSBs. The potential profile calculations reveal a high discharge barrier for Li-ion migration at the β-Li3PS4/LiCoO2 cathode interface, hindering the discharge process. By contrast, at the β-Li3PS4/LiAlO2/LiCoO2 interface, a lower interface potential drop is achieved to assist Li+ transport for fast discharging. Further analysis of the charge transfer and the band alignment reveals that the reduced interface potential drop stems from the synergistic effects of LiAlO2's Fermi level, chemical potential, and ionization potential. This work enhances the understanding of the interlayer's impact on interfacial Li+ transport and provides design principles for interlayer materials in ASSBs.

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We present the first-ever fabrication of the anode-free all-solid-state battery (AFASSB) structure using a MoS2 sacrificial layer. The addition of an MoS2 sacrificial layer to AFASSBs could decrease the nucleation overpotential of Li and enable favorable Li formation at the interface owing to the formation of an interlayer comprising Li2S and Mo metal. The AFASSB full cell assembled with LiNi0.6Co0.2Mn0.2O2 cathodes operated successfully, demonstrating superior cycling stability and enhanced capacity relative to the cells with SUS. We present the first-ever fabrication of the anode-free all-solid-state battery (AFASSB) structure using a MoS2 sacrificial layer. The addition of an MoS2 sacrificial layer to AFASSBs could decrease the nucleation overpotential of Li and enable favorable Li formation at the interface owing to the formation of an interlayer comprising Li2S and Mo metal. The AFASSB full cell assembled with LiNi0.6Co0.2Mn0.2O2 cathodes operated successfully, demonstrating superior cycling stability and enhanced capacity relative to the cells with SUS. Anode-free all-solid-state batteries (AFASSBs) are potential candidates for next-generation electric mobility devices that offer superior energy density and stability by eliminating Li from the anode. However, despite its potential to stabilize the interface between sulfide solid electrolytes (SEs) and anode-free current collectors (CCs) efficiently, a controllable approach to incorporating MoS2 into AFASSBs has not yet been found. Herein, we propose a strategy for stabilizing the interface of Li-free all-solid-state batteries using controllable MoS2 sacrificial thin films. MoS2 was controllably grown on CCs by metal–organic chemical vapor deposition, and the MoS2 sacrificial layer in contact with the SEs formed an interlayer composed of Mo metal and Li2S through a conversion reaction. In the AFASSBs with MoS2, Mo significantly reduces the nucleation overpotential of Li, which results in uniform Li plating. In addition, MoS2-based Li2S facilitates the formation of a uniform and robust SE interface, thereby enhancing the stability of AFASSBs. Based on these advantages, cells fabricated with MoS2 exhibited better performance as both asymmetrical and full cells with LiNi0.6Co0.2Mn0.2O2 cathodes than did cells without MoS2. Moreover, the cell performance was affected by the MoS2 size, and full cells having an optimal MoS2 thickness demonstrated a 1.18-fold increase in the initial discharge capacity and a sevenfold improvement in capacity retention relative to SUS CCs. This study offers a promising path for exploiting the full potential of MoS2 for interface stabilization and efficient AFASSB applications.

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An adaptive polymer electrolyte is demonstrated through the incorporation of conducting polymer particles, which cause the film to expand under an electric field with potential for application as an interlayer in lithium metal solid-state batteries.

Lithium metal anode batteries have attracted significant attention as a promising energy storage technology, offering a high theoretical specific capacity and a low electrochemical potential. Utilizing lithium metal as the anode material can substantially increase energy density compared with conventional lithium-ion batteries. However, the practical application of lithium metal anodes has encountered notable challenges, primarily due to the formation of dendritic structures during cycling. These dendrites pose safety risks and degrade battery performance. Addressing these challenges necessitates the development of a reliable and effective protection layer for lithium metal. This study presents a cost-effective and convenient method to spontaneously produce lithium metal protective layers by creating polymeric layers by using acrylonitrile (AN). This method remarkably extends 6× of the lifetime of lithium metal anodes under high current density (1 mA/cm2) cycling conditions. While the cycle life of bare lithium metal is approximately 150 h under high current cycling conditions, AN-treated lithium metal anodes exhibit an impressive longevity of over 900 h. The AN-treated lithium metal anodes are further integrated and tested with sulfide-based Li10GeP2S12 (LGPS) solid-state electrolytes to evaluate its interfacial stability at a solid-solid interface. The formation of the polyacrylonitrile (PAN)-rich ASEI, due to AN-treatment, effectively reduces and stabilizes the cell overpotential to only one-tenth of that with the interface without treatment. This strategy paves a route to enable a highly efficient and highly stable Li/LGPS solid-state battery interface.

Anode‐free solid‐state sodium batteries (AFSSBs) emerge as a highly promising next‐generation energy storage technology, offering exceptional energy density and significant cost advantages. However, their practical deployment remains challenging, primarily due to an insufficient understanding of Na dendrite formation and the absence of effective strategies to address the rigid multiphases interface, mitigate volume expansion, and reactivate inactive sodium. In this study, we systematically investigate the morphologies evolution of sodium at the interface between the Cu current collector and Na5SmSi4O12 (NSSO) solid electrolyte. Building upon these findings, we design an iodinated polymeric elastic artificial interphase layer (I‐PIL) with dual functionality. This layer not only ensures conformal interfacial contact through photoinitiated polymerization and atomic bonding, but also reactivates dead sodium via spontaneous reaction with the incorporated I3− species. Consequently, Na|Cu half‐cells achieve remarkable cycling stability, remaining a Coulombic efficiency of 99.7% for over 1000 h at 1.5 mA cm−2. When paired with Na3V2(PO4)3 cathode, the AFSSBs retain 85.8% capacity after 2000 cycles at 1.0 mA cm−2 and preserve 92.8% capacity over three months under high mass loading of 28 mg cm−2. This work provides fundamental insights into sodium deposition and establishes a versatile and scalable interfacial design strategy for high‐performance, durable anode‐free solid‐state batteries.

All Solid-State Batteries (ASSB) have emerged as a promising technology for electric vehicles and portable devices, offering multiple advantages over traditional liquid electrolyte batteries, such as improved safety, longer lifespan and higher energy density (Alabdali et al., 2022, Current Opinion in Electrochemistry , 36 , p.101127). However, as the battery manufacturing industry seeks to make these technologies more affordable, efficient and sustainable, there is an increasing pressure to optimize the use of costly materials like lithium. Battery performance is highly sensitive to design parameters such as electrolyte-domain and cathode thickness, and optimizing these parameters is crucial to both reducing material costs and improving battery performance. Traditionally, finding the optimal values for these design parameters has relied on an experimental trial-and-error approach, which can be both time-consuming and expensive. Therefore, more refined, data-driven methods (Zou et al., 2024, Energy and AI , 18 , p.100451) are needed to achieve cost-effective and high-performance solid-state batteries. In a battery, various physical phenomena govern its performance, particularly the movement of ionic species and charge transfer processes. The Nernst-Planck equation describes the diffusion and migration of ions in the electrolyte, while the diffusion of intercalated atoms within the electrode is governed by the diffusion equation. The Butler-Volmer equation models the charge transfer kinetics at the electrode-electrolyte interface. These processes are also associated with various sources of internal resistances within the battery. For instance, the charge-transfer overpotential arises from resistance to electron movement at the electrode-electrolyte interface. The mass transfer resistance refers to resistance encountered by ions as they move between the electrolyte and the electrode, while the diffusion resistance is the resistance due to the limited speed of ion diffusion in the cathodes (Danilov et al., 2010, Journal of the Electrochemical Society , 158 (3), p.A215). For efficient functioning of the battery the internal resistances should be minimal. In order to investigate the influence of various design parameters on the battery performance, we develop a machine learning (ML) based classifier model trained on the battery simulation data, obtained from the cell-level physics based model. The features considered in the ML model include design parameters such as the electrolyte thickness, cathode thickness and area of cross-section etc. The output of the model is the class into which the battery can be categorized. The battery class is determined by the number of system-level performance attributes (such as energy density, discharge time, various resistances occurring within the battery, etc.) that outperform their predefined expected cut-off values. This metric, therefore, captures the system-level performance attributes of the battery relative the expected values. Batteries part of the highest class correspond to batteries having the optimized range of the design parameters. Using this approach, we can estimate the range of design parameters that would place the battery within that class (inverse design approach). From our hybrid model, we found that a thinner electrolyte thickness, an optimal range of cathode thickness and a larger contact area of solid electrolyte-cathode gives the most efficient batteries. Using this model, one can even predict the class of a battery (based on its system-level performance) from its design parameters. Data-driven approaches like these combine both cell-level physics and machine learning models to train the model using data obtained from cell-level model while incorporating the underlying physical processes occurring within the cell. Our approach helps in new predictions by coupling both models, reducing computation time and providing more reliable, accurate solutions.

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Anode‐free lithium metal batteries (AF‐LMBs) promise ultrahigh gravimetric/volumetric energy densities (> 400 Wh kg−1/1000 Wh L−1) and simplified anode manufacturing as compared to conventional alkali‐ion batteries that rely on intercalation chemistry. However, their practical implementation remains plagued by dendritic protrusion from the substrate and rapid lithium inventory depletion, which further exacerbate in Ah‐scale pouch cells. Here, this study innovates a paradigm shift through a multiscale interfacial strategy addressing the core limitations of AF‐LMBs. Scalable cation‐exchange and mechanical exfoliation firstly produce few‐layer lithium montmorillonite nanosheets that integrated with polyacrylamide gel, which are functionalized onto the polyethylene separator (FMT‐Li/PAM‐PE). The composite separator thus reconciles high mechanical strength (204.4 MPa), thermal stability (< 2.5% shrinkage at 180°C), anion screening capability (t+ = 0.78), and pressure‐activated adhesion to the substrate (peel strength > 3.4 N m−1 via hydrogen bonding). Upon the formation cycle at stack pressure of 0.5 MPa, more crucially, the composite separator intimately attaches onto the Cu substrate modified with the recycled spent graphite rich in lithiophilic defects (SGR‐Cu), establishing the solid‐state Li+ diffusion pathway at the separator‐anode interface and mitigating solvated Li+ interaction. As assembled with a densely‐packed LiNi0.8Co0.1Mn0.1O2 (3.6 mAh cm−2) cathode, the 1.0 Ah pouch cell achieves 81.1% capacity retention over 200 cycles, gravimetric/volumetric energy densities of 453.3 Wh kg−1/ 1183.2 Wh L−1 and extreme power output of 1045.0 W kg−1. Beyond insights into multiscale ion regulation, this interfacial strategy also unlocks viability across diverse cell configurations (e.g., LiFePO4/Ni92||Cu), enabling the high‐rate cation diffusion for the commercial AF‐LMB prototyping.

Addressing the limitations of the liquid-based Li-ion batteries (LIBs) for the application of electric vehicles (EVs), solid-state batteries (SSBs) are claimed to be a solution, despite their own limitations under study. Though LIB is commercialised, the day-to-day run has many drawbacks, which render low consumer interest towards EVs than conventional vehicles, and SSB emerges as an alternative and efficient source of power, which can only be assured by testing. Hardware analysis of the SSB in the laboratory takes up time, space and expense. Computational modelling and artificial intelligence have reduced the need for those by bridging theoretical and practical establishment, providing insights into the challenges being faced and also directing towards future improvement. This study comprises SSB's compatibility with EV in comparison to LIB. Performance of five solid state electrolytes (SSEs) such as Li 7 La 3 Zr 2 O 12 (lithium lanthanum zirconium oxide), Li 10 GeP 2 S 12 (lithium germanium phosphorus sulphide), Li 6 PS 5 Cl – lithium argyrodite (lithium phosphorus sulphide chloride), Li 3 InCl 6 – lithium indium chloride and PEO–LiTFSI – poly(ethylene oxide) – lithium bis(trifluoromethanesulfonyl) imide are analysed at varying temperature, thickness, ionic conductivity, resistance and interaction with cathode particle size using electrochemical computation. A multi-criteria decision-making algorithm is used, and a feedforward neural network is employed. The results are interpreted with a commercial liquid state LIB to estimate its compatibility with EV. The novelty of this study lies in addressing the selection of a suitable SSE by splitting the cell on three computational bases and incorporating one of them, and establishing the pathway from computation to a neural network.

Recent studies presented the advantages of incorporating solid-polymer-electrolyte (SPE) interlayers in all-solid-state batteries (ASSB). Still, drawbacks regarding cell performance are expected due to additional polymer-related overpotentials. The pseudo-two-dimensional (p2D) physicochemical model is extended to account for Li-ion transport in the SPE interlayer and in the ceramic LLZO solid electrolyte (SE), as well as for the charge transfer at the SPE|LLZO interface using Butler-Volmer type kinetics. The overpotential analysis for a reference parameterization disclosed a dominant overpotential contribution from the SPE|LLZO charge transfer and a facilitation with increasing discharge C-rate. Variance-based global sensitivity analyses demonstrate that as the exchange current density between SPE and LLZO increases, polarization losses exhibit an exponential-like reduction. Additionally, the radius of the active material particles within the composite cathode exerts a significant and dominant influence on cell performance. With an optimization of the SPE|LLZO exchange current density, the accessible capacity could be increased compared to the reference parameterization from 41% to 61% for a 2C discharge.

No abstract available

Silicon has attracted extensive research attention in lithium-ion battery (LIB) field due to its high theoretical specific capacity (~3600 mAh/g) and cost-effectiveness. In recent years, silicon has emerged as a viable candidate for anode material for solid-state battery (SSB) technology. Similar to its application in LIBs, silicon utilizing in SSBs encounters challenges, such as significant volume variation (~300%) during cycling and poor cycling performance. In addition, the utilization of silicon in SSB faces another critical bottleneck in ionic conductivity due to the absence of liquid electrolyte. To address these challenges, various pioneering studies have explored potential solutions, including controlling the thickness of silicon anode to be below 150 nm,(1) fabricating electrodes with a combination of silicon and solid-state electrolyte (e.g, Garnet-type electrolyte(2) and sulfide electrolyte(3)), subjecting SSBs to a high pressure (10-50 MPa)(4). Here, we introduced an alternative approach to mitigate these challenges by designing anodes through incorporating silicon with mixed electronic-ionic conductive (MEIC) hierarchically ordered structure (HOS) polymer binders. These multifunctional HOS polymer binders effectively preserve the structural integrity of electrode materials, even when silicon materials experiences significant volume expansion and shrinkage during the charging-discharging process. Owing to establishments of covalent bonds between silicon surface and the polymer binders, the resulting SSBs exhibited excellent resilience and only required hand-tightening force (<1 ton) for operation. These polymer binders effectively maintained continuous electronic and ionic pathways within silicon-based anodes without the need of additional additives, such as carbon material and solid-state electrolytes. Utilizing these versatile polymer binders, the resultant SSBs featured an outstanding cycling performance over 100 cycles in full cells, with an average Coulombic efficiency exceeding 97%. Reference A. Song, W. Zhang, H. Guo, L. Dong, T. Jin, C. Shen and K. Xie, Advanced Energy Materials, 13, 2301464 (2023). W. Ping, C. Yang, Y. Bao, C. Wang, H. Xie, E. Hitz, J. Cheng, T. Li and L. Hu, Energy Storage Materials, 21, 246 (2019). M. Rana, Y. Rudel, P. Heuer, E. Schlautmann, C. Rosenbach, M. Y. Ali, H. Wiggers, A. Bielefeld and W. G. Zeier, ACS Energy Letters, 8, 3196 (2023). D. H. Tan, Y.-T. Chen, H. Yang, W. Bao, B. Sreenarayanan, J.-M. Doux, W. Li, B. Lu, S.-Y. Ham and B. Sayahpour, Science, 373, 1494 (2021).

Coupling with high‐voltage oxide cathode is the key to achieve high‐energy density sulfide‐based all‐solid‐state lithium batteries. However, the complex interfacial issues including the space charge layer effect and undesirable side reaction between sulfide solid‐state electrolytes and oxide cathode materials are the main constraints on the development of high‐performance all‐solid‐state lithium batteries, which lead to the continuous decay of electrochemical performance. Herein, different from the complicated coating procedure, a LiPO2F2 additive engineering was proposed to achieve high‐performance all‐solid‐state lithium batteries. With the introduction of LiPO2F2 additive, a protective cathode–electrolyte interphase consisting of LiPxOyFz, LiF, and Li3PO4 could be in situ formed to improve the interfacial stability between LiNi0.8Co0.1Mn0.1O2 (NCM811) and Li5.5PS4.5Cl1.5 (LPSC). Benefiting from this, the NCM811/LPSC/Li all‐solid‐state lithium battery exhibited impressive cyclic stability with a capacity retention of 85.5% after 600 cycles (at 0.5 C). Diverse and comprehensive characterization, combined with finite element simulation and density functional theory calculation fully demonstrated the effective component, interfacial stabilization function and enhanced kinetic of LiPO2F2‐derived cathode–electrolyte interphase. This work provides not only a feasible and effective method to stabilize the cathodic interface but also worthy insight into interfacial design for high‐performance all‐solid‐state lithium batteries.

Anode‐free all solid‐state batteries (AF‐ASSBs) employ “empty” current collector with three active interfaces that determine electrochemical stability; lithium metal – Solid electrolyte (SE) interphase (SEI‐1), lithium – current collector interface, and collector – SE interphase (SEI‐2). Argyrodite Li6PS5Cl (LPSCl) solid electrolyte (SE) displays SEI‐2 containing copper sulfides, formed even at open circuit. Bilayer of 140 nm magnesium/30 nm tungsten (Mg/W‐Cu) controls the three interfaces and allows for state‐of‐the‐art electrochemical performance in half‐cells and fullcells. AF‐ASSB with NMC811 cathode achieves 150 cycles with Coulombic efficiency (CE) above 99.8%. With high mass‐loading cathode (8.6 mAh cm−2), AF‐ASSB retains 86.5% capacity after 45 cycles at 0.2C. During electrodeposition of Li, gradient Li‐Mg solid solution is formed, which reverses upon electrodissolution. This promotes conformal wetting/dewetting by Li and stabilizes SEI‐1 by lowering thermodynamic driving force for SE reduction. Inert refractory W underlayer is required to prevent ongoing formation of SEI‐2 that also drives electrochemical degradation. Inert Mo and Nb layers likewise protect Cu from corroding, while Li‐alloying layers (Mg, Sn) are less effective due to ongoing volume changes and associated pulverization. Mechanistic explanation for observed Li segregation within alloying LixMg layer is provided through mesoscale modelling, considering opposing roles of diffusivity differences and interfacial stresses.

No abstract available

Characterizing the microstructure of all-solid-state batteries (ASSBs) during fabrication and operation is vital for their advancement, particularly as scaling to pouch cell levels introduces challenges in probing large-scale microstructural evolution. This work highlights the potential of synchrotron X-ray micro-computed tomography (sXCT) as a nondestructive, rapid (<30 min), and high-resolution technique for visualizing and quantifying key microstructural features, including overhang, porosity, contact loss, active surface area, and tortuosity, in all-solid-state pouch cells. The large field of view (up to millimeters) of sXCT enables detailed analysis at an industry-relevant scale, bridging the gap between laboratory research and commercial applications. Furthermore, integrating realistic sXCT-derived 3D models into multiphysics simulations could provide insights into chemo-mechanical degradation, particularly at the edges of the pouch cells, offering a pathway for designing robust, high-performance ASSBs. This perspective establishes sXCT as an indispensable tool for advancing both the understanding and the engineering of next-generation energy storage systems.

The rapid growth of lithium dendrites has seriously hindered the development and practical application of high‐energy‐density all‐solid‐state lithium metal batteries (ASSLMBs). Herein, a soft carbon (SC)‐nano Li6.4La3Zr1.4Ta0.6O12 (LLZTO) (with high ionic conductivity and diffusion coefficient) mixed ionic and electronic conducting interface layer is designed to promote the rapid migration of Li+ at the interfacial layer, induce the uniform deposition of lithium metal on nanoscale (nano) LLZTO ion‐conducting network inside the interface layer, effectively suppress the growth of lithium dendrites, and significantly improve the electrochemical performance of ASSLMBs. LiZrO2@LiCoO2(LZO@LCO)/Li6PS5Cl(LPSCl)‐nano LLZTO/Li ASSLMB achieves high current density (12.5 mA cm−2), ultra‐high areal capacity (15 mAh cm−2, corresponding to LZO@LCO mass loadings of 111.11 mg cm−2), and ultra‐long cycle life (20 000 cycles). Therefore, the introduction of SC‐nano LLZTO mixed conducting interface layer can greatly improve the interfacial stability between solid‐state electrolyte (SSE) and lithium metal anode to enable dendrite‐free ASSLMBs.

The utilization of sulfide-based solid electrolytes represents an attractive avenue for high safety and energy density all-solid-state batteries. However, the potential has been impeded by electrochemical and mechanical stability at the interface of oxide cathodes. Plastic crystals, a class of organic materials exhibiting remarkable elasticity, chemical stability, and ionic conductivity, have previously been underutilized due to their susceptibility to dissolution in liquid electrolytes. Nevertheless, their application in all-solid-state batteries presents a paradigm that could potentially overcome longstanding interface-related obstacles. This study presents a facile approach to enhancing the performance of sulfide-based solid-state batteries by utilizing nickel-rich oxide cathodes coated with ionically conductive plastic crystals. For employing plastically deformed succinonitrile as a metal ion ligand, it simultaneously supports mechanical stability and interfacial conduction, while LiDFOB establishes moderate ionic conductivity and a stable cathode electrolyte interphase (CEI). The synergistic effects of these mechanisms culminate in remarkable long-term performance metrics, with the capacity retaining 80% after 1529 cycles. Furthermore, this stability is maintained even when the areal capacity density is increased to a substantial 3.53 mA h cm-2. By combining electrochemical stability with mechanical plasticity, this approach opens possibilities for the development of long-lasting solid-state batteries suitable for practical applications.

All-solid-state batteries (ASSBs) with silicon anodes offer high energy density and mitigate issues such as continuous solid–electrolyte interphase (SEI) formation in lithium-ion batteries with liquid electrolytes. However, the evolution of the mechanical contact interface between silicon (Si) and the rigid solid electrolyte during cycling remains poorly understood. This study utilized operando synchrotron X-ray micro-computed tomography (micro-CT) and nano-computed tomography (nano-CT) to achieve high-resolution, 3D visualization of the silicon–electrolyte interface during lithiation and delithiation. Micro-CT revealed that silicon particles retain partial contact with the solid electrolyte as they delithiate and shrink to form shell voids, preserving ionic conduction pathways. High-resolution nano-CT further revealed a thin, previously undetectable solid electrolyte layer that adheres to the surfaces of the silicon particles and helps maintain these contact points. Additionally, interfacial delamination of the silicon was found to be highly anisotropic, initiating from sides that were laterally unconstrained due to uneven mechanical pressure and reaction inhomogeneity. Meanwhile, the vertically compressed interface remained largely intact. These findings elucidate the morphological evolution of the Si/electrolyte interface in ASSBs and demonstrate that continuous ion transport can be partially maintained despite significant volume changes.

Morphological degradation at the Li/solid‐state electrolyte (SSE) interface is a prevalent issue causing performance fading of all‐solid‐state batteries (ASSBs). To maintain the interfacial integrity, most ASSBs are operated under low current density with considerable stack pressure, which significantly limits their widespread usage. Herein, a novel 3D‐micropatterned SSE (3D‐SSE) that can stabilize the morphology of the Li/SSE interface even under relatively high current density and limited stack pressure is reported. Under the pressure of 1.0 MPa, the Li symmetric cell using a garnet‐type 3D‐SSE fabricated by laser machining shows a high critical current density of 0.7 mA cm–2 and stable cycling over 500 h under 0.5 mA cm–2. This excellent performance is attributed to the reduced local current density and amplified mechanical stress at the Li/3D‐SSE interface. These two effects can benefit the flux balance between Li stripping and creep at the interface, thereby preventing interfacial degradation such as void formation and dendrite growth.