High Performance Sulfide Solid-State Battery Electrolytes Regulation Mechanism: A Review

Sulfide solid electrolytes (SEs) exhibit excellent ionic conductivity and good mechanical properties, but their poor air stability and solid-solid contact performance seriously hinder the wide application of sulfide all-solid-state batteries (ASSBs). Herein, this paper reviews the history and the major breakthroughs in the development of sulfide SEs. The theories of hard-soft-acid-base theory and glass structure theory, as well as several strategies to improve the chemical stability of sulfide SEs, are discussed emphatically. In addition, this paper also explores its thermal runaway mechanism and reaction mechanism from the aspects of thermodynamics and reaction kinetics, providing a reference for the research on improving stability and electrical conductivity. Finally, we summarized the challenges that still need to be addressed at present, as well as the research directions and prospects of sulfide SEs for ASSBs in the future.