The Volcano Relationship between d<sub><i>z</i><sup>2</sup></sub> Electronic States and Sulfur Redox Reaction Kinetics in Lithium–Sulfur Batteries
Jiaming Tian, Yuan Rao, Sheng Xu, Xiangqun Xu, Yu Sun, Tianze Shi, Haoshen Zhou, Shaohua Guo
Abstract
The d orbital physics are closely related to the catalytic activity of transition-metal-based catalysts in Li–S batteries. However, challenges remain in understanding the optimal electronic configuration, causing a lack of guidance in the precise design of catalysts. Herein, by virtue of LaCoO 3 -based catalysts with different combinations of low-spin states and high-spin states of Co 3+, a volcano relationship between d z 2 filling number (from 0.95 to 1.29) and S/Li 2 S redox reaction kinetics is revealed. The best kinetics are provided at the d z 2 filling number of 1.12. As a result, the assembled Li–S battery shows a low decay rate of 0.026% per cycle in a 1500-cycle test and a high energy density of 460.7 Wh kg –1 in a practical pouch cell. This work reveals the critical influences of d z 2 electronic states on catalyzing the S/Li 2 S redox reaction and provides insights into finely regulating the electronic structures of high-performance catalysts for practical Li–S batteries.