Combined Defect and Heterojunction Engineering in ZnTe/CoTe₂@NC Sulfur Hosts Toward Robust Lithium-Sulfur Batteries

Lithium-sulfur batteries (LSBs) are feasible candidates for the next generation of energy storage devices, but the shuttle effect of lithium polysulfides (LiPSs) and the poor electrical conductivity of sulfur and lithium sulfides limit their application. Herein, a sulfur host based on nitrogen-doped carbon (NC) coated with small amount of a transition metal telluride (TMT) catalyst is proposed to overcome these limitations. The properties of the sulfur redox catalyst are tuned by adjusting the anion vacancy concentration and engineering a ZnTe/CoTe2 heterostructures. Theoretical calculations and experimental data demonstrate that tellurium vacancies enhance the adsorption of LiPSs, while the formed TMT/TMT and TMT/C heterostructures as well as the overall architecture of the composite simultaneously provide high Li+ diffusion and fast electron transport. As a result, v-ZnTe/CoTe2@NC/S sulfur cathodes show excellent initial capacities up to 1608 mA h g(-1) at 0.1C and stable cycling with an average capacity decay rate of 0.022% per cycle at 1C during 500 cycles. Even at a high sulfur loading of 5.4 mg cm(-2), a high capacity of 1273 mA h g(-1) at 0.1C is retained, and when reducing the electrolyte to 7.5 mu L mg(-1), v-ZnTe/CoTe2@NC/S still maintains a capacity of 890.8 mA h g(-1) after 100 cycles at 0.1C.