Graphene-Templated Growth of WS2 Nanoclusters for Catalytic Conversion of Polysulfides in Lithium-Sulfur Batteries

The practical application of lithium-sulfur (Li-S) batteries is hindered by poor cycling stability mainly derived from the shuttling of lithium polysulfides (LiPSs). Catalysis, which can promote the fast conversion of LiPSs, is a promising solution to the abovementioned problem. In this work, ultrasmall WS2 nanoclusters with the size around 2 nm are synthesized, with graphene as the growth template. The ultrasmall WS2 nanoclusters have abundant exposed edges and numerous unsaturated sulfur sites, which significantly enhance the adsorption ability toward LiPSs and render a high catalytic activity for their fast conversion. In addition, the three-dimensional structure assembled with graphene also provides a highly conductive network and large surface area for the fast conversion of LiPSs. As a result, the Li-S battery using the abovementioned hybrid as a catalytic sulfur host shows a low capacity fading of 0.067% per cycle within 250 cycles at 1 C. With the sulfur loading of 2.7 mg cm(-2), a high capacity retention of 74.7% after 500 cycles is achieved. Overall, this work proposes a promising catalyst design to improve the performance of Li-S batteries.