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.