Halide Solid‐State Electrolytes: Stability and Application for High Voltage All‐Solid‐State Li Batteries

Abstract Over the past few years, halide solid‐state electrolytes (HSSEs) have attracted the attention of researchers, and many reports about HSSEs have been published. Their wide electrochemical window (ECW) and a quite good compatibility with the popular oxide cathode materials make them attractive for practical applications. As a result, HSSEs are exciting candidates for the future generation of all‐solid‐state Li batteries (ASSLBs). In recent years, noticeable efforts have been made to develop novel HSSEs and utilize them in ASSLBs. Herein, a comprehensive update on the progress of HSSEs development and their application in ASSLBs is provided. First, a brief summary of the conductivity of HSSEs and potential synthesis approaches is provided. Next, the moisture and phase stabilities of HSSEs are reviewed separately, and the techniques proposed in the recently published reports to achieve sufficient stabilities are summarized. In addition, the electrochemical stabilities of HSSEs with Li metal anode and oxide cathode materials, from experimental and theoretical points of view, are provided in parallel. Furthermore, the application and progress of HSSEs in high‐voltage ASSLBs are discussed. Finally, new research directions are suggested for the development of scalable HSSEs‐based ASSLBs.