2H-VS ₂ /V ₂ C Schottky Heterostructure Modified Separator Utilizes Built-In Electric Field to Synergistically Enhance Polysulfide Trapping and Kinetics of Catalytic Conversion

The practical application of lithium–sulfur (Li–S) batteries is severely hampered by the polysulfide shuttle effect and sluggish sulfur redox kinetics. To address these challenges, a Schottky heterostructure catalyst (2H-VS2/V2C) with a built-in electric field (BIEF) was constructed by epitaxially anchoring semiconducting 2H-VS2 nanoflowers onto metallic V2C MXene substrates via a two-step hydrothermal method. This effectively synergizes the strong adsorption capability of V2C with the catalytic activity of 2H-VS2. The BIEF at the heterointerface significantly enhances electron and ion transport as well as accelerates the conversion kinetics of sulfur species. Consequently, Li–S batteries equipped with 2H-VS2/V2C modified separators achieve a specific capacity of 804.2 mAh g–1 at 5 C, demonstrating an excellent rate capability. Moreover, they exhibit outstanding cycling stability, with a capacity decay rate of only 0.037% per cycle over 1000 cycles at 1 C. Notably, they maintain excellent electrochemical properties even at high sulfur loadings of 4 mg cm–2 and at 0 °C. This work provides an effective interfacial engineering strategy to improve Li–S battery performance and offers guidance for the design of advanced heterostructure catalysts.