Abstract: Lithium halide solid-state electrolytes (SSEs), as “rising stars” in the field of solid-state electrolyte materials, exhibit higher room-temperature ionic conductivity compared with widely studied oxide SSEs and solid polymer electrolytes. Moreover, they demonstrate a wide electrochemical stability window and excellent processability during practical applications. Nevertheless, their practical deployment remains hindered by the intrinsic compromise between ionic conductivity and chemical stability, interfacial instability phenomena, and inadequate inherent stability. This study investigates the mechanistic origins of the prevailing challenges in lithium halide SSEs, comprehensively analyzes the causative factors underlying impeded ion conduction, interfacial destabilization, and stability degradation, and synthesizes key optimization strategies aligned with these mechanisms. Furthermore, we outline prospective research trajectories, advanced characterization methodologies, and material modification approaches for lithium halide SSEs, with the objective of providing technical insights and innovative paradigms to surmount their performance limitations.

Key words: Lithium halide solid-state electrolytes, Intrinsic properties, Ionic conduction, Existing challenges, Modification strategies