Freestanding Phosphonium Covalent Organic Frameworks with Efficient Hydroxide Conduction for Zinc–Air Batteries

, and stable operation over 2,300 min. Overall, in addition to investigating a novel cationic functional group, we demonstrated a freestanding film formation method of COF-based materials. The findings can provide a solid foundation for advancing the field of iCOFs to ion transport and promoting electrochemical applications.