A High-capacity Benzoquinone Derivative Anode for All-organic Long-cycle Aqueous Proton Batteries

Quinone compounds, with the ability to uptake protons, are promising electrodes for aqueous batteries. However, their applications are limited by the mediocre working potential range and inferior rate performance. Herein, we examined quinones bearing different substituents, and for the first time introduce tetraamino-1,4-benzoquinone (TABQ) as anode material for proton batteries. The strong electron-donating amino groups can effectively narrow the band gap and lower the redox potentials of quinone materials. The protonation of amino groups and the amorphization of structure result in the formation of an intermolecular hydrogen-bond network, supporting Grotthuss-type proton conduction in the electrode with a low activation energy of 192.7 meV. The energy storage mechanism revealed by operando FT-IR and ex situ XPS features a reversible quinone-hydroquinone conversion during cycling. TABQ demonstrates a remarkable specific capacity of 307 mAh g^-1 at 1 A g^-1, which is one of the highest among organic proton electrodes. An all-organic proton battery of TABQ//TCBQ has also been developed, achieving exceptional stability of 3500 cycles at room temperature and excellent performance at sub-zero temperature.