Design Principles for Moisture-Tolerant Sulfide-Based Solid Electrolytes and Associated Effect on the Electrochemical Performance of All-Solid-State Battery

Abstract

The grave concern on the safety of Li-ion batteries adopted in commercial electrical vehicles pushes an urgent demand for developing safer all-solid-state batteries (ASSBs), where ion-conducting solid electrolytes play pivotal roles. Much higher conductivity and more ductile nature of sulfide-based electrolytes offers great advantages over conventional oxide materials in terms of manufacturing process difficulty and the battery performance. However, instability of sulfide materials towards atmospheric moisture results in the substantial degradation in the ionic conductivity and the release of hazardous gas. After over a decade of intensive research, various customized strategies based on the specific design rules were developed for each electrolyte to tackle this crucial issue. However, in most cases a moisture tolerance was endowed only after compromising its vital ionic conductivity to some extent. Nevertheless, the actual applications of sulfide electrolytes to ASSBs often lead to improved battery performance by virtue of the interfacial stabilization between oxide-based cathode materials and sulfide-based solid electrolytes. Therefore, it is essential to fully comprehend the critical factors of each atmospheric stabilization technology that potentially affects the eventual battery performance. Herein, we go over the current status of state-of-the-art moisture-stabilizing technologies for each sulfide-based solid electrolyte, summarizing the major effect of each technology on the various aspect of the electrochemical performance upon application. We believe that this review will contribute to achieving effective moisture-stabilization of sulfide-based solid electrolytes, catalyzing the successful commercialization of sulfide-based ASSBs.