A Hierarchical Porous Tungsten Oxynitride-Based Nanocomposite for High-Performance Lithium–Sulfur Batteries

Abstract

The inherent volume expansion of sulfur, the low conductivity of sulfur species, and the shuttle effects of lithium polysulfides (LiPSs) have limited the commercial deployment of lithium−sulfur (Li−S) batteries. Herein, a tungsten oxynitride skeleton featured with a three-dimensional ordered macroporous (3DOM) structure and embedded with ZIF-67-derived Co-NC nanoparticles (S/Co-NC/WNO) is developed as an effective sulfur host in Li−S batteries. The stable and unique 3DOM structure is conducive to electrolyte permeation and reduces the influence of the volume expansion. Nitrogen doping not only enhances the electrical conductivity of WO 3 but also favors LiPS trapping. Meanwhile, Co-NC nanoparticles act as catalytic centers, promoting LiPS adsorption and catalytic conversion, leading to quick and durable Li−S chemistry. Therefore, S/Co-NC/WNO exhibits outstanding electrochemical performance. The initial discharge capacity is 1028.5 mAh g −1 at 0.2 C, and after 100 cycles, a discharge capacity of 938.0 mAh g −1 is maintained. Even under a sulfur loading of 8 mg cm −2 , the Li−S battery was capable of reaching an areal capacity of 5.54 mAh cm −2 . In addition, the flexible pouch cell based on S/Co-NC/WNO cathode also achieved stable cycling performance, which demonstrates its promising potential in Li− S battery applications.