Atomically dispersed cobalt sites on nitrogen-doped hollow carbon spheres as efficient electrocatalysts for high performance lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) face substantial performance limitations, primarily due to the slow kinetics of conversion and the detrimental shuttling effect of lithium polysulfides (LiPSs). In this study, cobalt single-atom catalysts were synthesized on nitrogen-doped hollow carbon spheres through the impregnation adsorption method. The combination of atomically dispersed Co sites with hollow carbon spheres enables the formation of nitrogen-doped hollow carbon spheres loaded with cobalt single-atom catalysts (NHCS@CoSAs), which act as efficient sulfur hosts. While being employed as a bifunctional electrocatalyst, the Co-N₄ catalytic sites not only inhibit the detrimental shuttle effect by adsorbing LiPSs but also accelerate their interfacial redox conversion, promoting faster conversion kinetics. This results in LSBs achieving a stable cycling life exceeding 2000 cycles, with a capacity fade of just 0.026 % per cycle at 2C. In addition, Li-S pouch cells featuring NHCS@CoSAs exhibit a remarkable initial capacity of 972.2 mAh g⁻¹ at a rate of 0.1C, even under a high sulfur loading of 4.16 mg cm⁻². This study could offer fresh perspectives on developing high-performance sulfur-based cathodes for LSBs.