Hollow ZnS microspheres loaded with WO₃ as a bidirectional catalyst for the redox of sulfur in Lithium-Sulfur batteries

The slow conversion kinetics of lithium polysulfides (LiPSs) during cycling in lithium-sulfur (Li-S) batteries is a major issue hindering their development. It often results in rapid capacity decay and low sulfur utilization. In this study, a novel sulfur host was fabricated through a simple two-step hydrothermal method. First, this work prepared uniformly sized hollow ZnS microspheres via hydrothermal synthesis, and then grew sheet-like WO₃ on the dispersed ZnS microspheres via hydrothermal treatment. The ZnS microspheres enable the rapid conversion of LiPSs, while WO₃ anchors the LiPSs. Due to the surface synergistic effect of ZnS and WO₃, the sulfur host based on a heterostructure interface improves electrical conductivity and accelerates the reaction kinetics of polysulfides, thereby increasing the utilization of sulfur as the active material. The lithium-sulfur batteries based on the WO₃/ZnS sulfur host demonstrate excellent capacity retention and outstanding rate performance. S@WO₃/ZnS batteries maintain a discharge capacity of 579 mAh g⁻¹ after 300 cycles at 0.5 C, with a capacity retention rate of 71.2% and a low decay rate of only 0.095% per cycle. This new sulfur host holds great potential for advancing the practical applications of Li-S batteries.