Air Stability and Interfacial Compatibility of Sulfide Solid Electrolytes for Solid-State Lithium Batteries: Advances and Perspectives

Sulfide solid electrolytes (SSEs) possess higher ionic conductivity compared to commonly used oxide electrolytes, and are expected to enable high-safety, high-energy-density solid-state batteries. However, the air sensitivity and interface instability of SSEs greatly limit their applications. Herein, research on the stability of SSEs is reviewed. The mechanisms for the air and interface instability of the SSEs are revealed. In addition, methods to improve the stability of SSEs are discussed. The air stability of SSEs is closely related to their structures, which can be modified by chemical or physical interactions to tackle the problem. Interface instability induced by physical contact, interface side reactions, and other issues between SSEs and electrodes is another problem, hindering their commercialization. An in-depth understanding of SSEs is offered as well as the prospects of SSEs.