Utilization of CoSe2-loaded carbon nanofibers for enhancing separator performance in lithium-sulfur batteries: Polysulfide immobilization and redox conversion enhancement

Lithium‑sulfur batteries (LSBs) are recognized as promising candidates for the next generation of secondary batteries due to their high energy density, high theoretical capacity, and low environmental impact. However, the poor electrical conductivity of sulfur and Li 2 S, the “shuttle effect” of polysulfides, and the slow kinetics of redox reactions have significantly hindered the practical application of LSBs. In this work, CoSe 2 -loaded carbon nanofibers (CoSe 2 @CNF) derived from metal-organic frameworks were successfully prepared by electrospinning and used as a functional coating on the polypropylene separator. The three-dimensional network structure of CNFs not only improves the electrical conductivity of the material but also provides channels to facilitate ion and electron transport, while the CoSe 2 particles distributed on the surface effectively act as adsorption and catalytic active sites for lithium polysulfides. Under the synergistic effect, the CoSe 2 @CNF-modified separator suppressed the shuttle effect and significantly enhanced the kinetics of redox reactions. The LSBs assembled with CoSe 2 @CNF-modified separator exhibited excellent electrochemical performance, achieving an initial capacity of 1445.6 mAh g −1 at 0.5C and maintaining a discharge specific capacity of 849.5 mAh g −1 after 275 cycles.