Vanadium Sulfide@Sulfur Composites as High-Performance Cathode for Advanced Lithium-Sulfur Batteries

Lithium-sulfur batteries have attracted a lot of attention in recent years due to their high theoretical capacity of 1675 mAh g(-1) and low cost. However, the shuttle effect caused by the dissolution and migration of polysulfides and the destruction of cathode particles due to volume expansion during lithiation are key issues for their practical application. Herein, a one-pot hydrothermal preparation of a VS2@S composite as a cathode for lithium-sulfur batteries is reported. The VS2@S composite shows uniform and flowerlike aggregates of nanoparticles of sizes around 50-80 nm. The porous structure among VS2@S nanoparticles can accommodate the volumetric expansion occurring during sulfur lithiation. Adsorption capability testing proves a strong interaction between VS2 and polysulfides. Therefore, the as-prepared VS2@S composite exhibits good electrochemical performance, with a discharge capacity of 413 mAh g(-1) after 200 cycles at a 1 C rate. After various rate cyclings from 0.1 to 2 C, the VS2@S electrode delivers a reversible capacity of 884 mAh g(-1) when the current density switches to 0.1 C, demonstrating a notable improvement compared with pure sulfur electrodes.