Atomically dispersed Co anchored on N,S-riched carbon as efficient electrocatalysts for advanced Li-S batteries

Lithium-sulfur (Li-S) battery possess the advantage of high specific energy but suffer from unstable cyclic performance due to the sluggish liquid-solid conversion kinetics causing severe lithium polysulfides (LiPS) shuttling. Designing multifunctional electrocatalysts with improved activity and abundant active sites to regulate the dynamics for sulfur electrochemistry is still a significant challenge. Herein, we proposed a thiourea assisted pyrolysis combined with hard template method to synthesize cobalt single atoms co-coordinated by N and S atoms embedded hollow carbon spheres (Co-NS-HCS) as a novel sulfur host. The Co-NS-HCS mainly consists of well-dispersed Co-N 3 S-C center sites where Co is co-bonded by N and S atoms. Systematical characterizations revealed that the Co-NS-HCS exhibit improved SRR electrocatalytic properties with higher exchange current density and larger electron transfer number than that of Co-N-HCS. When equipped in sulfur cathodes, the S@Co-NS-HCS exhibits superior rate performance (925 mAh g −1 at 2 C), long cycle stability (69.1% of capacity retention after 500 cycles at 1 C). Moreover, the assembled Li-S pouch type cell also exhibits competitive cyclic performance that work stably for 100 cycles at 0.1 C with a high capacity retention of 84.7%. This work furnishes a feasible scheme for the rational design of single atoms catalysts with improved electrocatalytic activity for sulfur cathodes based on the coordination environment regulation strategy.