Dynamic Disulfide Bonds Contained Covalent Organic Framework Modified Separator as Efficient Inhibit Polysulfide Shuttling in Li–S Batteries

First, a new covalent organic framework (HUT9) with disulfide bonds have been synthesized, which can be grown in situ on carbon nanotubes (CNT) as separator modification material for Li–S batteries. Experiments and DFT showed that disulfide bond could effectively capture soluble polysulfides (LiPSs) during discharge process, while promoting the conversion of LiPSs to Li2S/Li2S2 and improve the utilization rate of sulfur. The polar groups of the covalent organic framework provide chemisorption, and an interwoven network of HUT9@CNT (physical constraints) cooperates to inhibit the transport of LiPSs. The modified battery has a capacity retention rate of 83% (decay rate of 0.032% per cycle) after 500 cycles at 1 C. Specifically, the battery with 2-HUT9@CNT modified separators (sulfur loading: 4 mg cm–2, sulfur content: 80%, electrolyte/sulfur ratio: 10 mL g–1) can reach 3.4 mAh cm–2 area capacity after 50 cycles. This work enriched the COF material system and provided guidance for the application of organic materials in an energy storage system.