Improving the electrochemical property of Li-S batteries by using CoS2 as substrate materials

Metal sulfide CoS2 is prepared and used as host materials for Li-S batteries. The CoS2 particle could immobilize the polysulfide by catalyzing the redox reactions of soluble polysulfide to insoluble polysulfide. Besides, the employment of vapor growth carbon fiber (VGCF) interlayer between CoS2/S cathode and separator has a positive effect on physically adsorbing polysulfide. Consequently, the chemical and physical adsorption could exist in one Li-S battery system at the same time. As a result, the initial discharge capacity of CoS2/S composite cathode with VGCF interlayer is 1278 mAh g−1 at the rate of 0.1 C. After 200 cycles, the capacity still remains as high as 701 mAh g−1, which is better than the battery without CoS2, showing excellent electrochemical performance.