Impeding polysulfide diffusion strategies in lithium-sulfur batteries using 3D porous carbon nanosheets integrated by cathode and functional separator

Abstract

Lithium-sulfur(Li-S) batteries show high theoretical capacity and energy density compared to lithium-ion batteries(LIBs), which are one of the candidates for next-generation energy storage systems. However, rapid capacity fading caused by polysulfide shuttling effects remains critical issue for the commercial development in the Li-S batteries. Therefore, we aimed to derive 3D porous carbon nanosheets(C900) through the simple carbonization of organic salts as base materials for application as both sulfur host and functional separator. C900 had 3D vertically aligned and hierarchical carbon nanosheet structure with a high specific surface area and large pore volume, which was benefits for sulfur hosts because of the efficient electrolyte diffusion pathways and high mass loading of sulfur. Furthermore, nitrogen doped C900(NC900) can be improved chemical reactions with lithium polysulfides. Subsequently, an integrated electrode composed of a cathode with C900 and functional separator with NC900, respectively, was found to be highly efficient in restraining the shuttle effect via multimodal capturing effects. Consequently, all-integrated electrode composed of S-C900 and NC900@PP delivered a high initial specific capacity of 1453mAh·g-1 at 0.1C and achieved cycle stability with 64% capacity retention after 300cycles at 0.5C. This work suggests a potential carbon material design for bi-functional materials in a high-performance Li-S batteries.