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

Lithium 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 (E-a) 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 E-a 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.

Automated summary

A study shows that the activation of lithium sulfide (Li2S) can be improved by using organochalcogenide-based redox mediators, such as phenyl ditelluride (PDTe), which reduces the activation energy barrier and enhances the charge-discharge performance of Li2S in batteries, making it more suitable for commercialization.