Integrated Self-Supporting CoS ₂ /Na ₂ S@CNFs Cathode for Long-Cycle Room-Temperature Sodium-Sulfur Batteries

Room-temperature sodium-sulfur (RT Na-S) batteries have emerged as promising candidates for next-generation scalable energy storage systems with significant resource and cost advantages and high energy density potential. However, their practical application faces challenges such as polysulfide shuttling, electrode volume expansion, and slow kinetics. Herein, through electrospinning combined with in situ carbon thermal reduction technology, a self-supporting three-dimensional cathode CoS 2 /Na 2 S@CNFs was successfully designed and prepared. This design ingeniously integrates active Na 2 S, highly conductive carbon matrix, and catalytic active CoS 2, which can systematically address key challenges of poor conductivity, slow conversion kinetics, shuttle effect, and volume expansion in RT Na-S batteries. The incorporation of CoS 2 significantly enhances electronic conductivity while effectively refining Na 2 S grains and promoting their uniform dispersion. As a result, the battery exhibits outstanding electrochemical performance with significantly reduced activation overpotential, exceptionally high initial charge specific capacity of 1142.6 mAh g –1, excellent rate capability of 570 mAh g –1 maintained at 2 C, and outstanding long cycle life. Even at a high active material loading of 4.6 mg cm –2, the battery can maintain stable performance for 500 cycles, demonstrating promising practical application potential. This study provides an effective avenue for designing integrated cathodes for high-performance practical RT Na-S batteries.