Nitrogen-Doped Graphene-Supported Tungsten Oxynitride Nanoparticles as an Efficient Bidirectional Polysulfide Convertor for Advanced Lithium-Sulfur Batteries.

Abstract

Catalytic materials are considered pivotal in addressing the sluggish kinetics and shuttle effect in lithium-sulfur batteries (LSBs). However, effectively harnessing the utilization rate of active sites within catalytic materials remains a pivotal challenge. In this study, a novel conductive nitrogen-doped graphene-loaded tungsten oxynitride nanoparticle (WNO/NG) with abundant active sites is prepared through a polymer-assisted templating method for serving as a sulfur host. Electrochemical analysis coupled with <i>in situ</i> XRD confirm the dual-directional electrocatalytic behavior of WNO/NG for accelerating the conversion of lithium polysulfide (LiPSs). Theoretical calculations demonstrate that the intrinsic mechanism underlying the performance enhancement is attributed to the high inherent conductivity of WNO/NG and the efficient interface charge transfer with LiPSs. The assembled 500 mAh pouch cell delivers a 97% capacity retention after 25 cycles. This strategy provides valuable insights for designing catalytic materials with abundant activity sites and sheds light on the mechanisms of catalytic enhancement in Li-S chemistry.