Development of Synergistically Efficient Ni–Co Pair Catalytic Sites for Enhanced Polysulfide Conversion in Lithium–Sulfur Batteries

Abstract

AbstractThe performance of Lithium–sulfur (Li–S) batteries is constrained by the migration of lithium polysulfide (LiPS), the slow conversion of LiPS, and the significant reaction barrier encountered during the precipitation/dissolution of Li2S throughout the discharge/charge cycle. In this contribution, the study presents Ni–Co dual‐atom catalytic sites on hollow nitrogen‐doped carbon (NiCoNC). Theoretical calculations and experimental data reveal that the dual‐atom catalysts (DACs) accelerate the kinetic conversion of LiPSs and facilitate the formation/decomposition of Li2S during discharging and charging, which minimizes LiPS migration. Consequently, the utilization of S/NiCoNC cathodes manifests a substantial initial capacity of 1348.5 mAh g−1 at 0.1 C, exceptional cycling stability with an average capacity degradation rate of 0.028% per cycle over 900 cycles at 0.5 C, and noteworthy rate capability with a capacity of 626 mAh g−1 at 2 C. Electrodes with a higher sulfur loading of 4.5 mg cm−2 and a low electrolyte/sulfur ratio of 8 µL mg−1 exhibit exceptional specific capacities of up to 1236 mAh g−1 at 0.1 C, as well as noteworthy capacity retention of 494.2 mAh g−1 after 200 cycles at 0.2 C. This study effectively showcases the potential of DACs as catalysts for sulfur cathodes, thereby enhancing the overall performance of Li–S batteries.