MOF-derived NiCo2S4@C as a separator modification material for high-performance lithium-sulfur batteries

Functional separator, which serves as a barrier layer in lithium-sulfur (Li–S) battery, can effectively restrict the shuttle effect of polysulfide (PS). Herein, functional separators, modified with NiCo2S4@C which is derived from an annealing conversion of metal-organic framework (MOF) precursors, are prepared. For the modified separators, it is extremely advantageous to diffuse lithium ions and absorb PS. Owing to the presence of three-dimensional (3D) conductive network, moreover, the adsorbed PS can further be utilized during charging and discharging, resulting in high specific capacity and superior cycling life. When it is tested at a relatively high current density of 1.0 C, the Li–S battery assembled with a NiCo2S4@C-modified separator exhibits an initial capacity of 880 mA h g−1. After 200 testing cycles, furthermore, it can still provide a capacity of 700 mA h g−1, and its capacity decay rate is only 0.102% per cycle.