Strong intermolecular polarization to boost polysulfide conversion kinetics for high-performance lithium–sulfur batteries

Abstract

The sluggish kinetics of complex redox reactions in the lithium–sulfur (Li–S) battery still hinders the fulfillment of its promising potential for next-generation energy storage devices. Herein, we introduce CoIn₂S₄-nanostructured particles assembled with nanosheets as the catalyst to boost the polysulfide conversion kinetics in the Li–S battery. This strategy enables the Li–S battery to achieve a high rate capacity of 686 mA h g⁻¹ at 3C and allows it to be further applied in the pouch cell configuration with a total sulfur loading of 250 mg and E/S ratio of 5 μL mg_S⁻¹. The essential catalytic mechanism of the CoIn₂S₄ toward redox reactions is by targeting the rate-limiting process as concluded here from the electrochemical and in situ Raman studies, and as could be further evidenced by the theoretical analysis that indicated that the conversion barrier of short-chain polysulfides on the surface of CoIn₂S₄ is reduced and the charge transfer from CoIn₂S₄ to Li₂S₄ is enhanced due to the strong intermolecular polarization. The current work provides an insight into the catalytic mechanism focusing on the kinetics provided by in situ analysis, and demonstrates a new strategy for constructing highly practical Li–S batteries.