Glassy/Ceramic Li2TiO3/LixByOz Analogous “Solid Electrolyte Interphase” to Boost 4.5 V LiCoO2 in Sulfide‐Based All‐Solid‐State Batteries

Sulfide‐based all‐solid‐state lithium‐ion batteries (ASSLIBs) are the widely recognized approach toward high safety owing to excellent ionic conductivity and nonflammable nature of solid‐state electrolytes (SSEs). However, narrow potential window of SSEs brings about serious interfacial parasitic reactions, resulting in fast degradation of the battery. Herein, a glassy/ceramic analogous solid electrolyte interface (SEI) is constructed on LiCoO2 (LCO) to enhance interfacial stability between LCO and the Li10GeP2S12 (LGPS) SSEs. In which, ceramic Li2TiO3 guarantees good mechanical toughness of analogous SEI, while glassy LixByOz reinforces the coverage to avoid parasitic reactions. Analogous SEI endows ASSLIBs with excellent cycling and rate performance under an upper charge voltage of 4.3 V with 82.3% capacity retention after 300 cycles at 0.2 C. When pushing charge voltage to 4.5 V, analogous SEI also enables desirable performance with an initial capacity of 172.7 mAh g−1 and long lifespan of 200 cycles at 0.2 C. Both experiments and theoretical computation reveal excellent stability between analogous SEI and LGPS, which endows ASSLIBs with small polarization and improved performance. This work provides an insight on glassy/ceramic analogous SEI strategy to boost the interfacial stability of ASSLIBs. Inspiring by solid electrolyte interphase (SEI) in conventional Li‐ion batteries, an analogous SEI issuccessfully encapsulated on the LiCoO2 to overcome the instable interface between LiCoO2 and Li10GeP2S12 in all‐solid‐state lithium‐ion batteries (ASSLIBs). This analogous SEI with ceramic Li2TiO3 and glassy LixByOz enables a robust coating layer, endowing ASSLIBs with excellent durability under high charge voltage of 4.5 V.