Ultrahigh sulfur loading in ZnS1-x/rGO through in situ oxidation-refilling route for high-performance Li-S batteries

Sulfides are one of the most fascinating cathodic candidates for lithium-sulfur batteries (LSBs). However, low sulfur contents, dissolution of lithium polysulfides (LiPSs) into the electrolyte and slow conversion kinetics are key challenges for commercialization of sulfided-based LSBs. Herein, massive active sites are fabricated by creating sulfur vacancies on zinc sulfide (ZnS) dispersed on reduced graphene oxide (rGO) (ZnS1-x/rGO) and subsequent in situ oxidation-refilling loading strategy, which allows for 90 wt% sulfur contents. X-ray photoelectron spectroscopy (XPS), electrocatalytical experiments and density functional theory (DFT) confirm that sulfur vacancies act as efficient adsorption and catalytic conversion sites for LiPSs. The S-ZnS1-x/rGO cathode exhibits 1168 mAh g(-1) capacity and similar to 100% Coulombic efficiency with a capacity decay rate of 0.02% per cycle only at 0.5C after 500 cycles, one of the best performance reported up to date. Remarkably, high performances are retained even at 4.5 mg cm(-2) areal sulfur loading.