Sacrificial Template Method to Synthesize Atomically Dispersed Mn Atoms on S, N-Codoped Carbon as a Separator Modifier for Advanced Li–S Batteries

Efficient and durable electrocatalysts are important for polysulfide conversion in high-performance Li–S batteries. Herein, we report a sacrificial template strategy to synthesize a sulfur/nitrogen-codoped carbon-supported manganese (Mn) single-atom catalyst (Mn/SNC). The synthesis is enabled by fabricating a novel precursor, i.e., cadmium sulfide (CdS) wrapped with Mn ion-impregnated polyporrole (CdS@Mn-PPy), and subsequent pyrolysis. During pyrolysis, the CdS template is decomposed into Cd and S, PPy-derived carbon is doped with N and S, and Mn ions are reduced to Mn atoms, forming Mn–N active sites. The evaporation of Cd atoms/clusters creates abundant pores in the carbon substrate to expose the active sites and facilitate ion transport, and S atoms can form edge C–S–C bonds to improve the activity of Mn–N sites. Benefiting from the above advantages, the Mn/SNC catalyst markedly enhances the performance of Li–S batteries, delivering an initial capacity of 1563.7 mAh g–1 at 0.1C, a capacity decay of only 0.037% per cycle after 1600 cycles at 2C; a capacity of 1045.1 mAh g–1 at a high sulfur loading of 7.44 mg cm–2 at 0.2C, and a capacity retention of 73.1% after 180 cycles. This work provides a strategy that may benefit further the rational design and development of single-atom catalysts for application in renewable energy.