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

Abstract

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.