Self‐Limiting Reaction of Solid Electrolyte Empowering Ultralong Lifespan All‐Solid‐State Lithium Metal Batteries with Li ₆ PS ₅ Cl‐Based Electrolyte Membrane

Abstract Owing to their high energy density and inherent safety, sulfide solid electrolyte membranes (SSEMs) are considered ideal for use in all‐solid‐state lithium batteries (ASSLBs). However, interfacial reactions between lithium (Li) and the SSEMs significantly hinder the commercial viability of this application of SSEMs. In this study, an interfacial layer is formed in situ on Li surface via a self‐limiting reaction between Li and the Li ₆ PS ₅ Cl (LPSCl) electrolyte. The high interfacial energy and Young's modulus of the interfacial layer suppress the lithium dendrites. Meanwhile, the reduced migration barrier energy and enhanced interfacial compatibility of the interfacial layer with the sulfide electrolyte layer facilitate lithium‐ion transport across the interface. Consequently, the cycle life of the assembled symmetric cell surpasses 1000 h at 0.1 mA cm ⁻² . ASSLBs show high discharge capacity, superior cycling stability (76.3% capacity retention after 800 cycles at 2.0 C), and excellent rate performance (0.1–5.0 C). Furthermore, the pouch cell demonstrates outstanding electrochemical performance, signifying that assembled sulfide ASSLBs offer considerable potential for commercial application. By providing a simple and effective strategy to improve the interfacial stability between Li and the SSEMs, this research promotes the commercialization of sulfide‐based ASSLBs technology aimed at high specific energy and an efficient techno‐economic model.