Cobalt single atoms supported on N-doped carbon as an active and resilient sulfur host for lithium-sulfur batteries

Lithium-sulfur chemistry is currently being explored as a mechanism for electricity storage because it promises high energy capacities and low costs. However, practical applications of lithium-sulfur batteries (LSBs) are severely limited by the short cycle life caused by the polysulfide shuttling (PSS) effect. Herein, we report on a PSS-resistant yet redox-active sulfur host containing N-doped carbon dodecahedra supported cobalt single atoms (denoted as Co-SAs@NC) derived from a binary Co-Zn MOF-precursor. The results show that the sulfur cathode built on the Co-SAs@NC is electrocatalytically active towards soluble-polysulfides-to- insoluble-Li2S conversion, thus mitigating the detrimental PSS effect. The LSB using this new sulfur host exhibits a 600-cycle stable operation with a capacity of 737 mAh g(-1) at 1C and 2.0 mg cm(-2) S-loading. At a higher sulfur loading of 5.0 mg cm(-2), it can still deliver a high initial discharge capacity of 1069 mAh g(-1) at 0.1C and maintain 400 mAh g(-1) at 1C for 150 cycles. Theoretical analysis suggests that the Co-N-4 moiety in the Co-SAs@NC is fundamentally responsible for the observed activity and stability.