Building stable small molecule imide cathodes toward ultralong-life aqueous zinc-organic batteries

Organic carbonyl compounds as electrode materials have exhibited promising candidates for application in next-generation aqueous rechargeable batteries. However, a primary concern that is poor cycling performance are still remains due to high solubility of discharge products, which greatly limits their broader application. Herein, we developed a strategy to enhance the cyclability of aqueous zinc-organic batteries (AZOBs) by the terminal imidization and lateral π-system extension of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA). This strategy resulted in a perylene-based imide derivative with larger π-conjugated structure (2PDI), significantly inhibiting the solubility in an aqueous electrolyte. As expected, 2PDI as cathode offered a discharge capacity of 72.8 mA h g−1 at a current density of 100 mA g−1, and even retaining 99.4% capacity after ultralong 50 000 cycles at 3000 mA g−1. Its mechanism of reversible co-insertion Zn2+/H+ at the carbonyl site was verified via electrochemical tests and ex-suit characterizations. Moreover, density functional theory calculation (DFT) also revealed this co-insertion mechanism.