Designing a highly efficient polysulfide conversion catalyst with paramontroseite for high-performance and long-life lithium-sulfur batteries

Numerous efforts have been made to design the cathode of Li–S batteries to enhance reversible capacity and long-term cycling stability. However, challenges remain in achieving high electronic/ionic conductivity and suppressing the shuttle effect, especially for cathodes with high sulfur loading. Here we report a 3D free-standing hierarchical structure of VO₂(P) (paramontroseite VO₂) nanoparticles grown on nitrogen-doped carbon nanotube (NCNT) arrays as a catalytic host for high-performance sulfur cathodes. In this architecture, the VO₂(P) nanoparticles function as catalysts to oxidize the LiPS to produce thiosulfate due to the strong chemical interaction. Furthermore, thiosulfates act as a mediator to catenate long-chain LiPS together and convert short-chain Li₂S₂/Li₂S and surface-bound polythionate complexes. Accordingly, the VO₂(P)-NCNT/S cathode exhibits excellent performance with high discharge capacity output (≈1200 mA h g⁻¹ at 0.2 C), stable long-term cycling (≈67% retention at 2 C for 500 cycles), and high sulfur loading cycling (initial areal capacity of 10.2 mA h cm⁻² at 0.2 C for 200 cycles). This nanostructure catalytic cathode with high sulfur loadings, as well as stable cycling performances, is attractive for developing practically useable Li-S batteries.