Bifunctional Catalytic Effect of CoSe₂ for Lithium–Sulfur Batteries: Single Doping versus Dual Doping

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 CoS bond and longer SS bonds than Zn, while Zn demonstrates a better catalytic effect for Li 2 S decomposition with reduced Li 2 S decomposition barrier and elongated LiS 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.