Engineering zwitterionic barrier by squaraine-based porous organic framework fiber for superior lithium-sulfur batteries

Highlights: • A POF-based strategy is proposed to construct zwitterionic barrier for separator. • The zwitterionic nature of POF fosters a selective ion transfer environment. • The high areal capacity of Li-S batteries based on POF separator is realized. -- Abstract: The lithium sulfur (Li-S) battery holds great promise in next-generation energy storage technologies. However, the lithium polysulfide (LiPS) shuttle and slow reaction kinetics still limit its commercial development. Here, a squaraine-based porous organic framework (POF) with sulfophilic and lithiophilic moieties was developed as the separator modifications for the first time. The POF coating layer on the common separator builds a strong barrier against the LiPS shuttling, resulting in a robust inhibition on the shuttle effect as well as boosted sulfur reaction kinetics. Therefore, the POF-PP separator demonstrates stable cycling performance with a low capacity attenuation rate of 0.04% over 500 cycles and high areal discharge capacity of 4.67 mAh cm⁻² with a sulfur loading of 5 mg cm⁻², which show high potential for high loading and practical Li-S battery.