Building a Better All-Solid-State Lithium-Ion Battery with Halide Solid-State Electrolyte

Since the electrochemical potential of lithium metal was systematically elaborated and measured in the early 19th century, lithium-ion batteries with liquid organic electrolyte have been a key energy storage device and successfully commercialized at the end of the 20th century. Although lithium-ion battery technology has progressed enormously in recent years, it still suffers from two core issues, intrinsic safety hazard and low energy density. Within approaches to address the core challenges, the development of all-solid-state lithium-ion batteries (ASSLBs) based on halide solid-state electrolytes (SSEs) has displayed potential for application in stationary energy storage devices and may eventually become an essential component of a future smart grid. In this Review, we categorize and summarize the current research status of halide SSEs based on different halogen anions from the perspective of halogen chemistry, upon which we summarize the different synthetic routes of halide SSEs possessing high room-temperature ionic conductivity, and compare in detail the performance of halide SSEs based on different halogen anions in terms of ionic conductivity, activation energy, electronic conductivity, interfacial contact stability, and electrochemical window and summarize the corresponding optimization strategies for each of the above-mentioned electrochemical indicators. Finally, we provide an outlook on the unresolved challenges and future opportunities of ASSLBs.