Bifunctional Catalytic Effect of CoSe<sub>2</sub> for Lithium–Sulfur Batteries: Single Doping versus Dual Doping
Liping Chen, Yunhua Xu, Guiqiang Cao, Hirbod Maleki Kheimeh Sari, Ruixian Duan, Jingjing Wang, Chong Xie, Wenbin Li, Xifei Li
Abstract
Abstract Designing catalysts to accelerate the conversion of soluble lithium polysulfides (LiPSs) is regarded as a promising strategy to inhibit the shuttle effect, improving cathode performance of lithium–sulfur batteries (LSBs). Herein, a bifunctional Ni/Zn dual‐doped CoSe 2 is designed to enhance the catalytic effect of CoSe 2 . Specifically, Ni functions better in catalyzing the conversion of LiPSs into Li 2 S with shorter CoS bond and longer SS bonds than Zn, while Zn demonstrates a better catalytic effect for Li 2 S decomposition with reduced Li 2 S decomposition barrier and elongated LiS bonds than Ni. Those endows Ni/Zn dual‐doped CoSe 2 with bifunction in catalyzing conversion reaction of LiPSs and Li 2 S precipitation as well as the decomposition of Li 2 S, originating from the modified molecular structure of LiPSs and Li 2 S. As a result, the sulfur cathode with Ni 0.1 Zn 0.1 Co 0.8 Se 2 achieves a rate capability of 681.74 mAh g –1 at 2C, and a cycling stability for 400 cycles with a decay rate of 0.065%. This work provides an effective way to improve catalytic effect of transition metal compounds for advanced LSBs by homogenous dual doping.