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

• Published in: Journal of alloys and compounds 2022-07, Vol.910, p.164799, Article 164799
• Main Authors: Zhang, Shijun, Shao, Qinjun, Su, Yan, Xu, Lei, Jiang, Qike, Chen, Jian
• Format: Article
• Language: English
• Subjects: Carbon; Cathodes; Cobalt single atoms; Dispersion; Electrocatalysts; Electrochemistry; Electron transfer; Li-S batteries; Lithium sulfur batteries; Multifunctional electrocatalysts; Pyrolysis; Regulated coordination environment; Specific energy; Sulfur
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2022.164799

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. Cobalt single atoms co-coordinated by N and S atoms embedded hollow carbon spheres is synthesized as a highly efficient sulfur electrocatalyst to boost both the sulfur reduction and Li2S oxidation for advanced Li-S batteries with improved cyclic performance. [Display omitted] •Co single atoms coordinated by N/S are designed as efficient electrocatalysts.•The redox reaction kinetics of LiPS are boosted through S modulation.•The shuttle effect of LiPS is efficiently suppressed.•A high capacity retention of 84.7% is obtained in Li-S pouch cell.