Carbon fiber supported two-dimensional ZIF-7 interlayer for durable lithium-sulfur battery

Abstract The development of conductive and porous interlayer can effectively mitigate the shutting of lithium polysulfide (LiPs) for high efficiency lithium-sulfur (Li-S) batteries. In the present study, a flexible two-dimensional interlayer consists of ZIF-7 metal organic framework sheet rooted on carbon fiber (ZIF-7@CNF) was successfully fabricated. This ZIF-7@CNF interlayer not only works as a physical barrier for LiPs, the ZIF-7 flake also exposes a large number of active sites for LiPs adsorption. When stalked on the conductive CNF network, three dimensional channels for electron/ion transfer were formed, which also accelerates the transformation of LiPs. Due to these beneficial features, the Li-S batteries with this ZIF-7@CNF interlayer achieves an excellent discharge specific capacity (1226.9 mAh g−1) at 0.2 C with a high capacity retention rate of 89% after 100 cycles, a areal capacity of 3.92 mAh cm−2 under a sulfur loading of 6.37 mg cm−2. It also delivers good rate performance, showing a specific capacity of 560.7 mAh g−1 under the high rate of 5 C.