Rational design of well-dispersed ultrafine CoS2 nanocrystals in micro-mesoporous carbon spheres with a synergistic effect for high-performance lithium-sulfur batteries

The physical confinement and chemical catalysis of lithium polysulfides (LiPSs) are effective approaches to improve the performance of lithium-sulfur (Li-S) batteries. How to effectively combine physical confinement and chemical catalysis has become the focus of research. Herein, micro-mesoporous carbon (MMC) embedded with well-dispersed ultrafine CoS2 (uCoS(2)) nanocrystals as an efficient sulfur host is presented. As expected, the obtained S/uCoS(2)@MMC cathode can achieve a synergistic effect of physical confinement and chemical catalysis of LiPSs through micro-mesoporous structures and well-dispersed uCoS(2) nanocrystals. Furthermore, the MMC with a high conductive specific surface area, uniform pore size and micro-mesoporous structure can realize homogeneous loading of sulfur and physical adsorption of LiPSs. Owing to these excellent qualities, the S/uCoS(2)@MMC cathode delivers outstanding initial capacities up to 1227 mA h g(-1) at 0.1C. More significantly, a capacity of 606 mA h g(-1) is maintained after 1000 cycles at 1C (a very low capacity decay rate of only 0.032% per cycle). It can be seen that the MMC embedded with well-dispersed uCoS(2) nanocrystals as the sulfur host has great application prospects in Li-S batteries.