Rapidly Synthesized Single‐Ion Conductive Hydrogel Electrolyte for High‐Performance Quasi‐Solid‐State Zinc‐ion Batteries

Single‐ion conductive electrolytes can largely eliminate electrode polarization, reduce the proportion of anion migration and inhibit side reactions in batteries. However, they usually suffer from insufficient ion conductivity due to the strong interaction between cations and cationic receptors. Here we report an ultrafast light‐responsive covalent organic frameworks (COF) with sulfonic acid groups modification as the acrylamide polymerization initiator. Benefiting from the reduced electrostatic interaction between Zn 2+ and sulfonic acid groups through solvation effects, the as‐prepared COF‐based hydrogel electrolyte (TCOF‐S‐Gel) receives an ion conductivity of up to 27.2 mS/cm and Zn 2+ transference number of up to 0.89. In addition, sufficient hydrogen bonds endow the single‐ion conductive TCOF‐S‐Gel electrolyte to have good water retention and superb mechanical properties. The assembled Zn||TCOF‐S‐Gel||MnO 2 full zinc‐ion battery exhibits high discharge capacity (248 mAh/g at 1 C ), excellent rate capability (90 mAh/g at 10 C ) and superior cycling performance. These enviable results enlist the instantaneously photocured TCOF‐S‐Gel electrolyte to be qualified to large‐scaled flexible high‐performance quasi‐solid‐state zinc‐ion batteries.