Quinone Electrodes for Alkali–Acid Hybrid Batteries

Aqueous batteries are promising candidates for large-scale energy storage but face either limited energy density (lead-acid batteries), cost/resource concerns (Ni-MH batteries), or safety issues due to metal dendrite growth at high current densities (zinc batteries). We report that through designing electrochemical redox couples, quinones as intrinsic dendrite-free and sustainable anode materials demonstrate the theoretical energy density of 374 W h kg-1 coupling with affordable Mn2+/MnO2 redox reactions on the cathode side. Due to the fast K-ion diffusion in the electrolyte, low K-ion desolvation energy at the interface, and fast quinone/phenol reaction, the optimized poly(1,4-anthraquinone) in the KOH electrolyte shows specific capacities of 295 mA h g-1 at 300 C-rate and 225 mA h g-1 at 240 mA cm-2. Further constructed practical aqueous batteries exhibit an output voltage of 2 V in alkali-acid hybrid electrolyte systems with exceptional electrochemical kinetics, which can release/store over 95% of the theoretical capacity in less than 40 s (25 000 mA g-1). The scaled Ah level aqueous battery with the upgradation of interfacial chemistry on the electrode current collector exhibits an overall energy density of 92 W h kg-1, exceeding commercial aqueous lead-acid and Ni-MH batteries. The rapid response, intrinsic dendrite-free existence, and cost efficiency of quinone electrodes provide promising application interests for regulating the output of the electricity grid generated by intermittent solar and wind energy.