Metal-organic framework derived yolk-shell NiS2/carbon spheres for lithium-sulfur batteries with enhanced polysulfide redox kinetics.

Yolk-shell NiS2/carbon spheres (yolk-shell NiS2/C) have been synthesized by one-step annealing of yolk-shell Ni-metal-organic framework spheres. In particular, both the inner yolk sphere and the outer shell of yolk-shell NiS2/C can provide catalytically active sites for the redox of polysulfide confined in the yolk-shell structure, providing enhanced redox kinetics. A yolk-shell NiS2/C-sulfur cathode exhibits a high rate capacity of 569 mA h g-1 at 2C and shows excellent cycling stability, demonstrating the superiority of the yolk-shell structure.