Rational Design of Dual-Functional Mo-Doped Co ₉ S ₈ Superstructures for Synergistic Sulfur Electrochemistry and Lithium Stabilization in Advanced Li–S Batteries

Lithium–sulfur (Li–S) batteries face significant challenges including polysulfide shuttling, sluggish redox kinetics, and Li dendrite growth. This work introduces molybdenum (Mo)-doped Co 9 S 8 superstructures as a dual-function separator modifier to synergistically address these challenges. Atomic Mo doping, achieved through solvothermal synthesis, induces charge redistribution via Mo/Co 9 S 8 electronic coupling, optimizing the d-band center to both enhance polysulfide adsorption and catalyze their conversion. The Li–S battery equipped with a Mo/Co 9 S 8 -modified polypropylene (PP) separator delivers a high reversible capacity of 1663.5 mA h g –1 at 0.1 C, an exceptional rate capability of 593.4 mA h g –1 at 5 C, and demonstrates long-term stability with 56.1% capacity retention after 1000 cycles at 1 C. Additionally, the Mo/Co 9 S 8 modification layer helps reduce the inhomogeneity of Li + flux distribution and enhance the stability of the metallic Li anode. Under strict operating conditions (0.5 mA cm –2 /1.0 mA h cm –2 ), the Li–S battery equipped with a Mo/Co 9 S 8 -modified PP separator can stably operate for 400 h during the Li plating and stripping processes. This work is expected to provide new insights and approaches for designing separators that synergistically optimize the anodes and cathodes in Li–S batteries.