Urchin-like NiCo2S4 infused sulfur as cathode for lithium–sulfur battery

Abstract

A shuttle effect caused by soluble intermediates is one of the most crucial issues in lithium sulfur batteries, which results in a short cycle life and low coulombic efficiency. Recently, binary metal sulfides as electrode materials have been used for miscellaneous application accounting for their larger redox reaction sites and higher electrical conductivity. Herein, a novel urchin-like NiCo2S4 was synthesized via two steps of hydrothermal process and then firstly used as a conductive and polar host for sulfur in lithium sulfur batteries. The obtained NiCo2S4/S composite demonstrates a capacity of 1028 mAh g−1 for the first discharge and maintains 421 mAh g−1 after 100 cycles at 0.1 C. Furthermore, the composite still shows a remarkable cycling stability at a higher rate, a low capacity fade rate of 0.18% per cycle can be achieved and a reversible capacity of 329 mAh g−1 can be obtained after 300 cycles at 1 C. This excellent performance results from a weakened polysulfide shuttle caused by a strong affinity between NiCo2S4 and polysulfides.