Reconstruction of electric double layer via sodium persulfate additive for enhanced aluminium-air battery

The use of aluminium (Al) in Al-air batteries (AABs) is promising owing to its lightweight characteristics, accessibility, affordability, and high safety features. However, AABs’ main challenge lies in effectively suppressing hydrogen evolution on the anode in the alkaline electrolyte. Herein, we have used sodium persulfate (Na₂S₂O₈) as an electrolyte additive to construct a unique water barrier film, regulating the electrical double layer structure at the anode surfac to inhibit hydrogen precipitation effectively. Theoretical and experimental studies provide compelling proof for the role of Na₂S₂O₈ in inhibiting the self-corrosion of Al by establishing a thin shielding layer, efficiently regulating the hydrogen evolution kinetics, and improving battery performance. Compared to the pristine 4 M NaOH electrolyte, anode utilization of the Na₂S₂O₈-added electrolyte increased from 42.5 % to 75.5 %, capacity density improved from 1266.1 to 2247.8 mAh g⁻¹, and energy density rose from 1428.2 to 2567 Wh kg⁻¹. The significant outcome of this work could provide more insights into the development of efficient electrolytes for AABs.