Cobalt-based zeolitic imidazolate frameworks modified separator as efficient polysulfide adsorbent for high performance lithium-sulfur batteries

In this study, we have developed a new strategy to modify the pristine polypropylene film by using cobalt-based zeolitic imidazolate framework-67. The structure and morphology of ZIF-67 were observed via powder X-ray diffraction and scanning electron microscopy. Results indicate that the as-prepared ZIF-67 exhibits cubic structure with diameter of 80–100 nm. N2 absorption–desorption test confirms the presence of mespores in the ZIF-67 cubes. The ZIF-67 was used to modify the polypropylene film that was tested in popular lithium-sulfur batteries. Electrochemical results indicate that the Li-S batteries used ZIF-67/PP films exhibit high initial specific capacity of 1365 mAh g−1 at 0.1C. Besides, it shows high capacity of 816 mAh g−1 after 300 cycles at 2C, displaying superior cycling stability. The excellent electrochemical performance is attributed the strong adsorption ability of ZIF-67/PP film between polysulfide and ZIF-67. Therefore, the proposed strategy could provide a promising approach to promoting the commercial applications of Li-S batteries.