Optimized Catalytic WS2-WO3 Heterostructure Design for Accelerated Polysulfide Conversion in Lithium-Sulfur Batteries

The lithium-sulfur (Li-S) battery is a next generation high energy density battery, but its practical application is hindered by the poor cycling stability derived from the severe shuttling of lithium polysulfides (LiPSs). Catalysis is a promising way to solve this problem, but the rational design of relevant catalysts is still hard to achieve. This paper reports the WS2-WO3 heterostructures prepared by in situ sulfurization of WO3, and by controlling the sulfurization degree, the structure is controlled, which balances the trapping ability (by WO3) and catalytic activity (by WS2) toward LiPSs. As a result, the WS2-WO3 heterostructures effectively accelerate LiPS conversion and improve sulfur utilization. The Li-S battery with 5 wt% WS2-WO3 heterostructures as additives in the cathode shows an excellent rate performance and good cycling stability, revealing a 0.06% capacity decay each cycle over 500 cycles at 0.5 C. By building an interlayer with such heterostructure-added graphenes, the battery with a high sulfur loading of 5 mg cm(-2) still shows a high capacity retention of 86.1% after 300 cycles at 0.5 C. This work provides a rational way to prepare the metal oxide-sulfide heterostructures with an optimized structure to enhance the performance of Li-S batteries.