Electrostatic Potential-Induced Co–N<sub>4</sub> Active Centers in a 2D Conductive Metal–Organic Framework for High-Performance Lithium–Sulfur Batteries
Shaonan Gu, Shuzheng Xu, Xiao‐Yi Song, Hongda Li, Yinan Wang, Guowei Zhou, Nianxing Wang, Haixin Chang
Abstract
The use of single-atom catalysts is a promising approach to solve the issues of polysulfide shuttle and sluggish conversion chemistry in lithium–sulfur (Li–S) batteries. However, a single-atom catalyst usually contains a low content of active centers because more metal ions lead to generation of aggregation or the formation of nonatomic catalysts. Herein, a 2D conductive metal–organic framework [Co3(HITP)2] with abundant and periodic Co–N4 centers was decorated on carbon fiber paper as a functional interlayer for advanced Li–S batteries. The Co3(HITP)2-decorated interlayer exhibits a chemical anchoring effect and facilitates conversion kinetics, thus effectively restraining the polysulfide shuttle effect. Density functional theory calculations demonstrate that the Co–N4 centers in Co3(HITP)2 feature more intense electron density and more negative electrostatic potential distribution than those in the carbon matrix as the single-atom catalyst, thereby promoting the electrochemical performance due to the lower reaction Gibbs free energies and decomposition energy barriers. As a result, the optimized batteries deliver a high rate capacity of over 400 mA h g–1 at 4 C current and a satisfying capacity decay rate of 0.028% per cycle over 1000 cycles at 1 C. The designed Co3(HITP)2-decorated interlayer was used to prepare one of the most advanced Li–S batteries with excellent performance (reversible capacity of 762 mA h g–1 and 79.6% capacity retention over 500 cycles) under high-temperature conditions, implying its great potential for practical applications.