Activation of Bulk Li2S as Cathode Material for Lithium‐Sulfur Batteries through Organochalcogenide‐Based Redox Mediation Chemistry

Abstract

AbstractLithium sulfide (Li2S) is considered as a promising cathode material for sulfur‐based batteries. However, its activation remains to be one of the key challenges against its commercialization. The extraction of Li+ from bulk Li2S has a high activation energy (Ea) barrier, which is fundamentally responsible for the initial large overpotential. Herein, a systematic investigation of accelerated bulk Li2S oxidation reaction kinetics was studied by using organochalcogenide‐based redox mediators, in which phenyl ditelluride (PDTe) can significantly reduce the Ea of Li2S and lower the initial charge potential. Simultaneously, it can alleviate the polysulfides shuttling effect by covalently anchoring the soluble polysulfides and converting them into insoluble lithium phenyl tellusulfides (PhTe‐SxLi, x>1). This alters the redox pathway and accelerates the reaction kinetics of Li2S cathode. Consequently, the Li||Li2S‐PDTe cell shows excellent rate capability and enhanced cycling stability. The Si||Li2S‐PDTe full cell delivers a considerable capacity of 953.5 mAh g−1 at 0.2 C.