Catalytic Boosting Bidirectional Polysulfide Redox using Co_0.85Se/C Hollow Structure for High-Performance Lithium-Sulfur Batteries

Achieving effective adsorption and fast conversion of soluble polysulfides confined in the sulfur cathode is critical yet challenging for building high-performance lithium-sulfur batteries. Herein, we construct a unique hollow-structured Co_0.85Se/C as a separator modifier (CSPP) to effectively suppress the polysulfide shuttle effect. The Co_0.85Se/C demonstrates strong anchoring with polysulfide species and smooth bidirectional electrocatalysis. The unique mesoporous hollow architecture affords sufficient catalytic sites and Li⁺ diffusion channels for promoting the reaction kinetics. Benefiting from the merits, the CSPP-cell could yield a superior electrochemical utilization of active sulfur, excellent rate capability (679 mAh g⁻¹ at 5 C), and stable cycling performance with an ultralow fading rate of 0.056 % per cycle over 500 cycles. The work highlights great promise of developing cobalt-based materials as kinetic regulators for highly stable lithium-sulfur batteries.