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

Abstract Lithium sulfide (Li 2 S) 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 Li 2 S has a high activation energy ( E a ) barrier, which is fundamentally responsible for the initial large overpotential. Herein, a systematic investigation of accelerated bulk Li 2 S oxidation reaction kinetics was studied by using organochalcogenide‐based redox mediators, in which phenyl ditelluride (PDTe) can significantly reduce the E a of Li 2 S 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‐S x Li, x >1). This alters the redox pathway and accelerates the reaction kinetics of Li 2 S cathode. Consequently, the Li||Li 2 S‐PDTe cell shows excellent rate capability and enhanced cycling stability. The Si||Li 2 S‐PDTe full cell delivers a considerable capacity of 953.5 mAh g −1 at 0.2 C.