Cation-deficient TiO2/polypyrrole heterojunctions: An efficient bidirectional electrocatalyst for enhanced lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) are poised to revolutionize next-generation energy storage due to their high energy density. However, the “polysulfide shuttle effect” poses a critical challenge to their cycling stability. Herein, we introduce a cation-deficient TiO₂/polypyrrole (Ti_1-xO₂/PPy) nanocomposite-modified polypropylene separator designed to mitigate this issue. This novel separator effectively captures and catalytically transforms polysulfides (LiPSs) during charge/discharge cycles, thereby enhancing LSB cycling stability. Notably, the modified separator enables an LSB to retain 708.8 mAh g⁻¹ after 300 cycles at 0.5C and an impressive 554.1 mAh g⁻¹ after 1000 cycles at 1C. Our findings not only present a promising approach to separator modification for LSBs but also offer critical insights into manipulating electrochemical reactions, potentially driving future improvements in LSB technology.