Designing Quinone-Based Anodes with Rapid Kinetics for Rechargeable Proton Batteries.

Quinone compounds, which are capable of accommodating proton (H + ), are emerging electrodes in aqueous batteries. However, the storage mechanism of proton in quinone compounds is less known and the energy/power density of quinone-based proton battery is still limited. Here we design a series of quinone anodes and study their electrochemical properties in acidic electrolyte, in which tetramethylquinone (TMBQ) delivers a high capacity of 300 mAh g -1 with an extremely low polarization of 20 mV at 1 C, and maintains over 50 % theoretical capacity in less than 16 seconds. The fast kinetics of TMBQ is attributed to the continuous H + migration channel, high H + diffusion coefficient (10 -6  cm 2  s -1 ), and low H + migration energy barrier (0.26 eV). When coupling with MnO 2 cathode, the battery shows a long lifespan of 4000 cycles with a capacity retention of 77 % at 5 C. This study reveals the proton transport in quinone-electrodes and offers new insights to design advanced aqueous batteries.