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The sluggish redox kinetics of polysulfides and difficult oxidation process of Li₂S severely hinder practical application of Li–S batteries under high sulfur loading and a low electrolyte dosage. To address these issues, we develop a bifunctional catalyst by manipulation of anion N doping in CoSe₂ (N-CoSe₂). Theoretical simulation results uncover that an introduced N element into CoSe₂ could form a shorter Co–N bond, create a higher charge number of the Co central atom, bring new defect levels, and induce the Co 3d band closer to Fermi level. Further atomic level analysis revealed that N-CoSe₂ could form shorter Co–S bonds with sulfur species and simultaneously weaken the S–S bridged bond of Li₂S₄ and Li–S bond of Li₂S, which eventually facilitate the polysulfide conversion reaction in the discharge process and the Li₂S oxidation in the charge process. With N-CoSe₂ as a bifunctional catalyst, the battery …