Exclusive Se-O Coordination and Fe-doping Complementation: A Catalytic Strategy for Enhanced Sulfur Redox in Li-S...

Developing efficient electrocatalysts to accelerate redox kinetics and suppress lithium polysulfides (LiPSs) shuttling remains a key challenge for lithium-sulfur batteries (LSBs). Although transition-metal-oxides exhibit strong adsorption for the LiPSs, their application is impeded by sluggish Li₂S conversion. Herein, a catalytic strategy is proposed for enhanced sulfur redox in LSBs by complementing exclusive Se-O coordination and Fe-doping in spinel Co₃O₄ (Fe_0.1Co_2.9O₄-Se) electrocatalyst. This engineered intersecting-porous nanoarchitecture, fabricated via an etching-carbonization method, facilitates electron/mass transport and exposes abundant electroactive sites. Fe³⁺ substitution at octahedral Co³⁺ sites synergizes with exclusive Se-O coordination, narrows Co₃O₄'s bandgap, and elevates the d-band center, thereby enhancing conductivity and strengthening the LiPSs' adsorption. Such a design promotes instantaneous nucleation of Li₂S and reduces the bidirectional catalytic energy barrier for achieving superior catalytic activity, outperforming Se-Fe_0.1Co_2.9O_4, where Se in oxygen-vacancies-sites coordinates with metal/oxygen ions. Consequently, the S/Fe_0.1Co_2.9O₄-Se cathode delivers exceptional cycling stability with an ultralow capacity decay rate of 0.1054% per cycle over 500 cycles at 0.5 C. In a pouch cell with a high sulfur loading (6.1 mg cm^-2) and lean electrolyte (E/S = 10 µL mg^-1), it retains a capacity of 4.8 mAh cm^-2 after 40 cycles. This work provides a new catalytic strategy for the design of high-performance LSBs electrocatalysts.