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

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.