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 (approximate to 1200 mA h g(-1) at 0.2 C), stable long-term cycling (approximate to 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.