Redox‐Mediated Aluminum–Air Fuel Cells With Suppressed Hydrogen Evolution for Durable Power Generation

ABSTRACT Aluminum (Al) is a promising anode material for metal–air systems owing to its exceptional theoretical capacity, earth abundance, and environmental compatibility. However, its practical development in alkaline media is hindered by parasitic corrosion and surface passivation arising from the thermodynamically favored hydrogen evolution reaction (HER), resulting in low Faradaic efficiency. Herein, we introduce a redox‐mediated aluminum–air fuel cell (RM‐AAFC) in which HER is kinetically suppressed by a soluble redox mediator, 7,8‐dihydroxy‐2‐phenazine sulfonic acid (DHPS), which forms a competitive electron transfer pathway at the Al–electrolyte interface, boosting Faradaic efficiency from 36.1% to 92.5% without compromising the reaction kinetics. When integrated with precipitation‐ and complexation‐ based aluminate extraction strategies, the system delivers a peak power density of 210 mW cm ⁻² and a volumetric capacity of 403.2 Ah L ⁻¹ during sustained operation. These findings highlight redox‐mediated chemistry as a general and scalable strategy for mitigating interfacial parasitic reactions in aqueous metal–air energy systems.