Co/CoSe Junctions Enable Efficient and Durable Electrocatalytic Conversion of Polysulfides for High-Performance Li-S Batteries

Lithium-sulfur (Li-S) batteries are regarded as promising candidates for next-generation energy storage systems. However, the slow kinetics and shuttle effects of polysulfides hinder their practical applications. Designing high-efficiency catalysts to enhance the kinetics and suppress shuttling is one major task for the building of durable Li-S batteries. Here, a Co/CoSe junction is reported to catalyzepolysulfide conversion efficiently because the junction has metallic electron mobility and field-enhanced catalytic activity. The mechanistic investigation reveals that the difference in the work functions of Co and CoSe rearranges the charge distribution in the junction and strengthens the interaction between polysulfides and CoSe, thereby yielding high catalytic activity. In addition, the relative stability of CoSe, as compared to Co, renders the junction durable upon cycling; therefore, demonstrating long-term catalytic activity. Such a junction makes full use of metal-like conductivity and field-enhanced catalysis and provides an alternative approach to enhancing the catalytic conversion of polysulfides.