Nickel-based metal–organic framework-derived Ni/NC/KB as a separator coating for high capacity lithium–sulfur batteries

Abstract

Lithium–sulfur (Li–S) batteries have recently caught increasing attention as next-generation energy storage systems on account of their outstanding theoretical energy density, environmental friendliness and economical nature. However, due to the drawback of soluble Li₂S_n (4 ≤ n ≤ 8) intermediates, the generated poor electrochemical reversibility and low coulombic efficiency limit the commercial applications of these batteries. Herein, we have proposed a prospective approach to promote the comprehensive electrochemical property of Li–S batteries utilizing a Ni nanoparticles/nitrogen doped carbon/Ketjen Black (Ni/NC/KB) composite derived from Ni-based MOFs as a separator coating. When current density is at 1C, the Ni/NC/KB separator exhibited a high capacity of 653.7 mA h g⁻¹ with an inappreciable capacity fading of around 0.07% per cycle over 500 cycles. The performance improvement is attributed to the nature, morphology and structure of the as-prepared porous composite material, which restricted the polysulfides in the cathode area and catalyzed the long-chain polysulfides to the short-chain polysulfides. These results bring out the possibility of utilizing composite materials such as Ni/NC/KB as separator coating for high-performance Li–S batteries, hence addressing the limitations on further development into these battery systems.