Binder‐Free, Self‐Supporting, and Highly Conductive Sulfide Electrolytes Enabling Superior Anode Stability

Abstract All‐solid‐state batteries (ASSBs) are attracting interest as next‐generation rechargeable batteries, offering the promise of high energy density, high power capability, and superior safety. To practically realize these characteristics, it is essential to develop solid electrolytes (SEs) that exhibit both high ionic conductivity and robust physicochemical stability—an inherently challenging feat. In this paper, the fabrication of a sulfide‐based glass SE layer is reported using a warm isostatic pressing (WIP) technique that enables simultaneous densification and crystallization under elevated temperature and pressure. The results show that the elimination of binders from the SE layer significantly enhances the efficiency of the WIP process, while the incorporation of a glass‐based supporting layer imparts excellent mechanical strength and flexibility to the SE film. The resulting SE layers are compatible with standard ASSB fabrication protocols and can be integrated into 13 mAh‐class laminated cells using nickel‐cobalt‐manganese cathodes and graphite anodes. The assembled cells demonstrate outstanding cycling performance, retaining ≈80% of their initial capacity after 300 cycles at 25 °C under a moderate stack pressure of 20 MPa. This study offers a promising pathway toward the practical implementation of high‐performance ASSBs by addressing key challenges in electrolyte design and process integration.