Constructing ultra-stable, high-energy, and flexible aqueous zinc-ion batteries using environment-friendly organic cathodes.

Due to their sustainability, environmental friendliness, high specific capacity, and rapid reaction kinetics, quinone cathodes have broad application prospects in aqueous zinc-ion batteries (AZIBs). However, conventional small-molecule quinone cathodes usually suffer from unavoidable dissolution, resulting in terrible cycling stability. Herein, based on a strategy of molecular structure optimization, calix[8]quinone (C8Q) is for the first time used as a cathode in AZIBs. By extending the structure of the classical small-molecule quinone cathode calix[4]quinone (C4Q), C8Q further adds four p -benzoquinone structural units, which significantly suppresses the dissolution of its discharge products and greatly improves the cycle stability of the cathode. Specifically, the C8Q cathode displays a discharge specific capacity of 207.2 mA h g -1 at 1 A g -1 and a long-life cycle stability (93 mA h g -1 /10 A g -1 /10000 th ). Even with a high active material loading of 11 mg cm -2 , the Zn‖C8Q battery also exhibits high redox reversibility and remarkable electrochemical stability. Furthermore, the belt-shaped Zn‖C8Q battery has high stability and outstanding flexibility, indicating its promising application in flexible wearable electronic devices.