MOF-Derived MnS/N–C@CNT Composites as Separator Coating Materials for Long-Cycling Li–S Batteries

To address the issues of poor cycle properties and low Coulombic efficiency of Li–S batteries, which are caused by the insulation nature of sulfur as well as the shuttle effect of the reaction intermediate, a special metal organic framework-derived nitrogen-doped carbon/carbon nanotube (CNT) composite decorated with the MnS nanoparticle (MnS/N–C@CNT) structure is fabricated and used as a polysulfide shield. A ZIF-8/CNT composite is first prepared via a facile room-temperature water solution reaction and carbonized to obtain a nitrogen-doped carbon/CNT (N–C/CNT) structure. Then, the MnS/N–C@CNT composite is fabricated by a solvothermal method. By using the MnS/N–C@CNT as the coating layer of a Li–S coin battery, the shuttle effects of lithium polysulfides are greatly hindered. CNTs are supposed to be good Li+-ion conductors based on their large length–diameter ratio, and the ZIF-8-derived N–C nanocube grafted on the CNT has a strong lithium polysulfide adsorption ability because of its micropore structure. Furthermore, the MnS nanoparticles buried in the N–C/CNT matrix show chemical interactions with lithium polysulfides as well as the catalytic effect. Thanks to the above advantages, the use of a MnS/N–C@CNT-modified separator shows obvious progress in the specific capacity and cycle properties of the Li–S coin battery.