A Hybrid Redox‐Mediated Zinc‐Air Fuel Cell for Scalable and Sustained Power Generation

A hybrid redox-mediated zinc-air fuel cell that liberates the zinc reaction from the electrode to a separate fuel tank was demonstrated, which enabled a facile zinc refueling in the tank and attained a record-high power density of 0.51 W/cm² and discharge capacity of 48.82 Ah by optimizing system kinetics. The zinc evolution mechanism during redox-mediated reaction was unveiled for the first time using various in situ characterization techniques.

Abstract

Zinc-air batteries (ZABs) have attracted considerable attention for their high energy density, safety, low noise, and eco-friendliness. However, the capacity of mechanically rechargeable ZABs was limited by the cumbersome procedure for replacing the zinc anode, while electrically rechargeable ZABs suffer from issues including low depth of discharge, zinc dendrite and dead zinc formation, and sluggish oxygen evolution reaction, etc. To address these issues, we report a hybrid redox-mediated zinc-air fuel cell (HRM-ZAFC) utilizing 7,8-dihydroxyphenazine-2-sulfonic acid (DHPS) as the anolyte redox mediator, which shifts the zinc oxidation reaction from the electrode surface to a separate fuel tank. This approach decouples fuel feeding and electricity generation, providing greater operation flexibility and scalability for large-scale power generation applications. The DHPS-mediated ZAFC exhibited a superior peak power density of 0.51 W/cm² and a continuous discharge capacity of 48.82 Ah with ZnO as the discharge product in the tank, highlighting its potential for power generation.

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