Self-derived dual-carbon-constrained CoSe nanocatalyst for accelerated polysulfide conversion in lithium-sulfur batteries.

Lithium-sulfur (LiS) batteries offer high theoretical energy density and low material cost, yet their practical application is limited by poor conductivity, sluggish redox kinetics, and the polysulfide shuttle effect. A promising strategy to overcome these challenges involves the rational design of carbon-supported metal catalysts with high conductivity, strong polysulfide adsorption, and abundant accessible active sites to enhance reaction kinetics. Herein, we report a dual‑carbon-constrained cobalt selenide (CoSe) nanocatalyst, derived from a metal-organic framework, as an efficient sulfur host. The hierarchical three-dimensional conductive network-comprising ultrathin carbon nanosheets and in-situ grown carbon nanotubes-facilitates rapid electron and ion transport while providing numerous active sites. Uniformly dispersed CoSe nanoparticles act as bifunctional adsorption-catalysis centers, promoting polysulfide conversion and effectively suppressing the shuttle effect. As a result, the cathode achieves a high specific capacity of 1385.7 mAh g at 0.2 A g, maintains 728.5 mAh g at 5 A g, and demonstrates excellent long-term cycling stability. This study presents a viable design approach for carbon-supported metal catalysts, offering a pathway toward the advancement of LiS battery technology.