Implanting Single Zn Atoms Coupled with Metallic Co Nanoparticles into Porous Carbon Nanosheets Grafted with Carbon Nanotubes for High-Performance Lithium-Sulfur Batteries

The electrochemical performance of lithium-sulfur (Li-S) batteries is severely hindered by the sluggish sulfur redox kinetics and the shuttle effect of lithium polysulfides (LiPSs). Herein, an integrated composite catalyst consisting of Co nanoparticles and single-atom (SA) Zn co-implanted in nitrogen-doped porous carbon nanosheets grafted with carbon nanotubes (Co/SA-Zn@N-C/CNTs) is rationally developed toward this challenge. Experimental and theoretical investigations indicate that the synergistically dual active sites of Co and atomic Zn-N-4 moieties with an optimal charge redistribution not only strongly confine the LiPSs but also effectively catalyze its conversion reactions by lowering the energy barrier from Li2S2 to Li2S while the N-doped porous carbon-grafted CNTs enables a large surface area for more active site exposure and provides a fast electron/ion pathway. Benefiting from synergies, Li-S batteries equipped with the Co/SA-Zn@N-C/CNTs-based sulfur cathode exhibit a high reversible capacity of 1302 mAh g(-1) at 0.2 C and a low capacity fading rate of 0.033% per cycle over 800 cycles at 1 C. Moreover, a high areal capacity of 4.5 mAh cm(-2) at 0.2 C with the sulfur loading of 5.1 mg cm(-2) can be achieved. The present work may provide new insight into the design of high-performance sulfur-based cathodes for Li-S batteries.

Automated summary

In this study, an integrated composite catalyst was designed and prepared to effectively solve the problems caused by slow sulfur redox kinetics and the shuttle effect of lithium polysulfides in lithium-sulfur batteries. The catalyst exhibited synergistic catalytic effects and a large surface area, which could restrict the diffusion of lithium polysulfides and provide a fast electron/ion pathway, thereby improving the reversible capacity and cycling stability of lithium-sulfur batteries.