Synergistic imine-thiophene coordination in covalent organic framework enables a highly reversible Zn anode

A benzothiophene-based COF (BDT-COF) is designed and grown in situ on a glass fiber (GF) separator. Leveraging the imine-thiophene bidentate coordination toward Zn2+, BDT-COF achieves a uniform Zn2+ flux, improved ion migration kinetics, and efficient desolvation of hydrated Zn2+, thus boosting the reversibility of the Zn anode in aqueous zinc-ion rechargeable batteries. Consequently, the symmetric cell with the BDT-COF@GF separator achieves a stable stripping/plating process over 1000 h at 3 mA cm-2 and the asymmetric cell can cycle stably for more than 1100 cycles at 10 mA cm-2. The Zn|BDT-COF@GF|MnO2 cell exhibits impressive cycling performance with a capacity retention of 89.2% after 1000 cycles.