Two‐Dimensional Mesoporous Tungsten Oxynitride/Carbon Nanosheets: Enabling High‐Performance Lithium‐Sulfur Batteries

Abstract

ABSTRACT Lithium‐sulfur batteries (LSBs) hold great promise as next‐generation energy storage devices, owing to their ultrahigh theoretical energy density (2600 Wh kg −1 ). However, their real‐world implementation is limited by the polysulfide shuttle effect and the poor electrical conductivity of sulfur species. To address these problems and achieve high‐performance LSBs, it is crucial to develop multifunctional catalysts featuring abundant active sites, short and accessible ion transport channels, and lightweight architectures. Herein, a novel two‐dimensional mesoporous tungsten oxynitride/carbon nanosheet (WNO‐MCS) material is successfully fabricated via a self‐template‐guided interfacial assembly strategy. The resulting WNO‐MCS exhibits a uniform two‐dimensional nanosheet morphology, featuring vertically aligned mesoporous channels across the sheets with a pore size of 3.9 nm, a high surface area of 588.7 m 2 g −1 , and well‐confined WNO nanoclusters (∼2.9 nm) embedded in the mesopores. This unique 2D mesoporous structure provides short, open pathways for ion transport and highly exposed active sites; thus, LSBs with a WNO‐MCS‐modified separator deliver a remarkable areal capacity of 7.7 mAh cm −2 under a high sulfur loading of 8.0 mg cm −2 . Moreover, the pouch cell achieves an initial discharge capacity of 0.62 Ah with a high energy density of 360 Wh kg −1 .