Isolated diatomic Zn-Co metal–nitrogen/oxygen sites with synergistic effect on fast catalytic kinetics of sulfur species in Li-S battery

Lithium-sulfur batteries are severely restricted by low electronic conductivity of sulfur and Li2S, shuttle effect, and slow conversion reaction of lithium polysulfides (LiPSs). Herein, we report a facile and high-yield strategy for synthesizing dual-core single-atom catalyst (ZnCoN4O2/CN) with atomically dispersed nitrogen/oxygen-coordinated Zn-Co sites on carbon nanosheets. Based on density functional theory (DFT) calculations and LiPSs conversion catalytic ability, ZnCoN4O2/CN provides dual-atom sites of Zn and Co, which could facilitate Li+ transport and Li2S diffusion, and catalyze LiPSs conversion more effectively than homonuclear bimetallic single-atom catalysts or their simple mixture and previously reported single-atom catalysts. Li-S cell with ZnCoN4O2/CN modified separator showed excellent rate performance (789.4 mA h g−1 at 5 C) and stable long cycle performance (0.05% capacity decay rate at 6C with 1000 cycles, outperforming currently reported single atomic catalysts for LiPSs conversion. This work highlights the important role of metal active centers and provides a strategy for producing multifunctional dual-core single atom catalysts for high-performance Li-S cells.