Interfacial charge redistribution at a ZrO₂-CoSe₂ heterointerface for synergistic polysulfide anchoring and catalytic conversion in lithium-sulfur batteries.

Lithium‑sulfur batteries (LSBs) offer high theoretical specific capacity and energy density. However, their practical application is severely constrained by the electrical insulation between sulfur and Li₂S, as well as the shuttle effect caused by intermediate lithium polysulfides (LiPSs). Here, we designed ZrO2-CoSe2/NC heterostructures to enhance the adsorption and conversion of polysulfides. Through the experimental and first-principles calculations, the ZrO2-CoSe2/NC showed a significant ability to adsorb soluble LiPSs and enhance their conversion process. The electrochemical results demonstrated that batteries with ZrO₂-CoSe₂/NC-modified separators achieved a high initial discharge capacity of 1422.6 mAh g-1 at 0.5C. After 500 cycles at 2C, the capacity decay rate was only 0.056% per cycle. The density functional theory (DFT) calculations quantify a synergistic interfacial enhancement at the ZrO₂ (111)-CoSe₂ (120) heterointerface, which exhibits stronger adsorption for most sulfur species than the single-component surfaces, achieving binding energies of -3.75 eV for Li₂S and -2.28 eV for Li₂S₆. Furthermore, post-adsorption XPS and PDOS results reveal adsorption-associated charge redistribution and electronic coupling between LiPSs and the ZrO2-CoSe2 heterointerface, which, together with the electrochemical measurements, support strong LiPSs anchoring and enhanced conversion behavior. This study presents an innovative approach to developing enhanced separator materials that exhibit excellent cycling stability for lithium‑sulfur batteries.