Tg-C₃N₄-coated functional separator as polysulfide barrier of high-performance lithium-sulfur batteries

Lithium sulfur (Li-S) battery is considered as a promising alternative for the development of battery technologies. However, the shuttle effect seriously limits its practical use. Herein, hollow tubular graphene-like carbon nitride (Tg-C₃N₄) is synthesized and utilized as a functional interlayer to inhibit shuttling effect and promote catalytic kinetics. Both experiments and DFT calculations together suggest that N-doping enhances the electron transfers between Tg-C₃N₄and LiPSs, leading to improved chemical adsorptions and catalytic effects towards the redox conversions of the active sulfur species. Besides, Tg-C₃N₄delivers a unique hollow tubular architecture with massive ion transfer pathways and fully exposed active interfaces. In addition, the abundant C-N heteroatomic structures also impose strong chemical immobilization toward lithium polysulfides. Benefiting from these unique superiorities, the cell with the Tg-C₃N₄-modified separator exhibits a reversible capacity of 494 mAh g^-1after 500 cycles at 1 C with a negligible capacity decay of 0.085% per cycle, indicating an efficient strategy toward high-performance modified separators.