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-N3S-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. (C) 2022 Published by Elsevier B.V.

Automated summary

In this study, a thiourea-assisted pyrolysis combined with hard template method was proposed to synthesize cobalt single atoms co-coordinated by N and S atoms embedded hollow carbon spheres as a novel sulfur host for Li-S batteries. The synthesized material exhibited improved electrocatalytic properties and cycle stability, with higher activity and better dynamic regulation for sulfur electrochemistry. It showed superior rate performance and long cycle stability in sulfur cathodes, demonstrating its potential for practical battery applications.