Cobalt nitride nanoparticles embedded in porous carbon nanosheet arrays propelling polysulfides conversion for highly stable lithium–sulfur batteries

Abstract

Compared with currently mature lithium ion batteries, lithium-sulfur batteries (LSBs) show many remarkable advantages for next-generation electrical energy storage owing to high theoretical specific energy and low cost. However, the shuttle effect, low conductivity of sulfur cathode, and sluggish kinetics are remarkable barriers preventing their realistic application. Herein, we present a facile strategy in which cobalt nitride (Co4N) nanoparticles embedded leaf-like porous carbon nanosheet arrays are grown on flexible carbon cloth as a free-standing cathode for high-performance LSBs. Co4N not only adsorbs the intermediate lithium polysulfides (LiPSs) strongly, but also catalytically promotes the mutual transformation between sulfur and Li2S. Moreover, theoretical simulations reveal the strong interaction between Co4N and sulfur species. The created free-standing cathode exhibits a high capacity of 1121 mAh g-1 after 100 cycles at 0.5 C, a high rate performance (746 mAh g-1 at a high rate of 5 C relative to 1237 mAh g-1 at 0.2 C), and high stable cycle performance (598 mAh g-1 at 5 C over 500 cycles with ultralow 0.035% decay per cycle). Our method provides a new potential avenue for energy conversion and storage devices based on multi-electron redox reactions.