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

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 m2 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.