Simultaneous Immobilization and Conversion of Polysulfides on Co₃O₄-CoN Heterostructured Mediators toward High-Performance Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries exhibit great potential as a next-generation rechargeable battery system due to their high energy density, natural abundance, and nontoxicity. Nevertheless, the insulated nature of S and Li₂S and the electrochemical instability of intermediate lithium polysulfides (LiPS) obstruct the commercialization of Li-S technologies. Herein, a heterophase Co₃O₄-CoN sulfur host combined with the merits of efficient polysulfide anchoring (Co₃O₄) and high conductivity (CoN) is reported to boost Li-S battery performance. Such porous Co₃O₄-CoN heterostructures endow the intermediate LiPS with the instantaneous immobilization-diffusion-conversion process, thus accelerating redox kinetics and alleviating the polysulfide shuttling. The assembled cathode based on the Co₃O₄-CoN/CC electrode exhibits a high initial capacity of 1225 mAh g^-1 at 0.5 C with excellent rate performance (887 mAh g^-1 at 3 C), and the specific capacity can be well maintained to 627 mAh g^-1 even after 500 cycles at 3 C. Our work provides an efficient strategy for the rational design of comprehensive host materials enabling simultaneous LiPS immobilization and conversion and will give further impetus to the practical use of Li-S batteries.