D‐Band Center Modulation of Fe‐Doping CoSe₂ to Accelerate Polysulfide Conversion for High‐Performance Lithium–Sulfur Battery

Abstract As prospective energy storage devices surpass conventional lithium‐ion systems, lithium–sulfur batteries confront operational challenges, including polysulfide dissolution and slow redox dynamics. This work reports an iron doping methodology to engineer CoSe₂‐based electrocatalysts with optimized electronic configurations. The strategic introduction of iron dopants induces valence electron redistribution between metallic centers, systematically tuning the d‐orbital energy level alignment relative to the Fermi energy. Such electronic modification substantially enhances the phase transformation kinetics between soluble LiPS intermediates and insoluble Li₂S deposition. Hence, the batteries with the Fe(0.05)‐CoSe₂ catalyst display more excellent cyclic lifespan, rate performance, and specific capacities than those with the CoSe₂ catalyst. It delivers an initial discharge capacity of 1473 mAh g⁻¹, with 444 mAh g⁻¹ after 1000 cycles at 1.0C. This work provides an efficient strategy to accelerate the conversion kinetics of polysulfides on lithium–sulfur system.