Appreciating the role of polysulfides in lithium-sulfur batteries and regulation strategies by electrolytes engineering

Abstract

Lithium-sulfur (Li-S) batteries are receiving a growing appreciation from the academic community and industry due to their relatively high theoretical energy density and low-cost raw materials. However, their commercialization strongly depends on overcoming the shuttle effect caused by Li polysulfide species (LiPSs), the low utilization efficiency of active S material, and the uncontrolled growth of Li dendrites. Electrolytes can be the key to these issues and promote the reaction kinetics of Li-S batteries through electrolyte engineering. In this review, after introducing the development history and working mechanism of Li-S battery, advanced in-situ characterization techniques that facilitate insight into the underlying mechanism of Li-S batteries are discussed. Subsequently, various strategies for suppressing the shuttle effect of LiPSs are simply summarized. The role of LiPSs is thoroughly discussed and a comprehensive overview is provided, and the electrolyte engineering strategies for eliminating the dissolution of LiPSs and inhibiting the growth of Li dendrites in Li-S battery systems are focused. In addition, the controversy over suppressing versus promoting the dissolution of LiPSs to the bulk electrolyte is deeply discussed, and techniques and theoretical calculations for characterizing the solvation structure of Li+ ions are presented. Finally, prospects and personal perspectives are provided on electrolyte engineering as the future research directions for Li-S batteries.