Lithium-sulfur (Li-S) battery are considered as the next generation energy storage system owing to their ultra-high theoretical specific capacity and energy density. However, the commercialization of Li-S battery is still hindered by the intrinsically low conductivity of sulfur, sluggish catalytic conversion and notorious shuttle effect of polysulfides. The implantation of defects in sulfur electrocatalyst can effectively increase its conductivity and catalytic efficiency of lithium polysulfides, but the current mainstream defective materials are limited and lack of in-depth research. Herein, a defective niobium selenide (NbSe