Unraveling the Catalytic Activity of Fe-Based Compounds toward Li2Sx in Li-S Chemical System from d-p Bands

Lithium-sulfur batteries have ultra-high energy density and are considered to be one of the most promising energy storage systems among all battery systems. However, due to various thorny problems, their commercial production has not yet been realized. The current experimental research normally lacks a systematic investigation into the conversion mechanism of the sulfur cathode from the electronic structure level. Actually, there is still a lack of powerful theoretical guidance for the design of high-performance Li-S batteries and the selection of modified materials still seems blind. In this article, with the chelated Fe-polyvinyl pyrrolidone as the precursor, a series of Fe-based materials (e.g., Fe3O4@C, FeS@C, Fe3N@C) are synthesized as modified layers for battery separators, and the performance differences between them are systematically studied. It is found that the d-p band center model developed based on the d band center can reasonably combine the reaction potential of Li2S4 and performance differences. Simultaneously, the interaction between Li2S6 and the adsorption interface is simulated by ab initio molecular dynamics. This current work sheds light on promising material design for superior Li-S batteries both from a theoretical and experimental perspective.