Superharmonic proton motion in high-energy-density organic electrodes for aqueous zinc batteries

The limited proton transfer kinetics within organic positive electrodes restricts the proton storage capacity and hinders achieving high energy density in aqueous zinc-organic batteries. Herein, we obtain superharmonic motion of proton by crosslinking short hydrogen-bonds network within the positive electrode matrix to achieve fast proton transfer. Specifically, the pyrazino[2, 3-g]quinoxaline-5, 10-dione owing strong electrostatic and hydrogen-bond interactions with hydrogen ions is synthesized, which could attract concentrated hydronium and trigger local proton enrichment. Spatially confined water-hydronium domains are therefore formed to generate short hydrogen bonds around pyrazino[2, 3-g]quinoxaline-5, 10-dione molecules. Moreover, the 4,4'-diaminodiphenylamine and polytetrafluoroethylene binder exhibits a mutual affinity with pyrazino[2, 3-g]quinoxaline-5, 10-dione due to the strong hydrogen-bond interactions of them, which reduce the intermolecular distance within positive electrode and construct a highly interconnected state of water-hydronium domains, thereby establishing the short hydrogen bonds network throughout the electrode matrix. The rapid proton transport through short hydrogen bonds consequently reduces the polarization of aqueous zinc-organic batteries (1.47 × 10^-3 S cm^-1). As a result, the composite positive electrode delivers specific energy of 400 Wh kg^-1 at 0.1 A g^-1.