Double redox-active polyimide-based covalent organic framework induced by lithium ion for boosting high-performance aqueous Zn2+ storage

Abstract

Rechargeable aqueous zinc ion batteries (AZIBs) have the great potential as a safe, economical, sustainable, and environmentally friendly energy storage system. Despite being one of the most promising electrode materials for AZIBs, organic molecules are plagued by poor conductivity and structural instability due to their low molecular weight and short-range conjugated structure. Herein, a novel polyimide-based covalent organic framework (PI-COF) compound with affluent C=O and C=N electroactive groups is synthesized and employed as the cathode to achieve rapid aqueous Zn2+ storage. Results of electrochemical measurements and in-situ characterizations reveal a lithium ion-induced Zn2+ storage behavior and high reversibility of redox-active units in PI-COF electrode, which favor to extend the Zn2+ storage capability and ensure the cycle stability. As a result, the PI-COF delivers an ultrahigh and ultrafast Zn2+ storage properties in aqueous hybrid-ions electrolyte, in terms of remarkable charging/discharging capacity of 464.2 mA h g−1 at 1.0 A g−1 and high-rate capacity of 220.2 mA h g−1 at 10.0 A g−1 as well as superior cycling stability over 1000 cycles with a capacity retention of 85.3 %. This work lays the groundwork to develop the highly stable organic electrode materials for advanced AZIBs.