Research progress on chloride solid electrolytes for all-solid-state batteries

All-solid-state lithium batteries (ASSLBs) are expected to be the next-generation energy storage technology to replace traditional organic liquid lithium-ion batteries because of their high energy density and high safety. Solid-state electrolytes (SSEs) as the most critical component in solid-state batteries largely lead the future battery development. Among different types of solid-state electrolytes, halide SSEs have received focused attention from researchers because of their high ionic conductivity, wide electrochemical window, and good compatibility with oxide cathodes. Chloride SSEs are the most comprehensive and detailed studies, which are considered one of the most promising and important solid-state electrolytes for batteries. In this review, we report on recent developments in chloride SSEs, synthesis strategies and modifications, stability of chloride SSEs/electrodes, crystal structure, degradation mechanisms and mitigations, and battery architectures and integration. Finally, the challenges of chloride SSEs are briefly summarized, enabling a foundation for a wide range of applications of solid-state chloride electrolyte-based batteries.