in situ engineered ultrafine NiS2-ZnS heterostructures in micro-mesoporous carbon spheres accelerating polysulfide redox kinetics for high-performance lithium-sulfur batteries.

Host materials that can physically confine and chemically adsorb/catalyze lithium polysulfides (LiPSs) are currently receiving intensive research interest for developing lithium-sulfur (Li-S) batteries. Herein, a novel host material made of micro-mesoporous carbon nanospheres (MMC NSs) with well-dispersed ultrafine NiS2-ZnS (uNiS2-ZnS) heterostructures is synthesized for the first time via a simple in situ sulfuration process. The uNiS2-ZnS/MMC materials achieve the synergistic effect of physical confinement and the efficient chemical adsorption/catalysis of LiPSs through a micro-mesoporous structure and well-dispersed uNiS2-ZnS heterostructures. In addition, compared with bulk heterostructured materials, the uNiS2-ZnS heterostructures greatly enhance the adsorption and catalytic ability toward LiPSs because the catalysis interface effect and naturally formed in-plane interfaces can be magnified by the ultrafine dispersed nanoparticles. As a result, the prepared uNiS2-ZnS/MMC-S cathodes exhibit outstanding rate capacity (675.5 mA h g-1 at 5.0C) and cyclic stability (710.5 mA h g-1 at 1.0C after 1000 cycles with a low capacity decay of 0.033% per cycle). This work provides a certain reference for the application of heterostructured materials in Li-S batteries.