Effect of oxidant additive on enhancing activation property of NaCl-based electrolyte aluminum-air battery

Aluminum-air battery (AAB) with NaCl-based electrolyte exhibits great application potential owing to wide source, high safety, and low cost of the electrolyte. However, the passivation film generated on Al anode surface restricts its continuous dissolution during discharge process. Herein, oxidant additives (FeCl3 or KMnO4) are introduced into NaCl-based electrolyte to enhance activity of Al anode as well as the discharge performance of the battery. A significant increase in the discharge voltage is observed, reaching 1.18V with FeCl3 and 1.15V with KMnO4, considerably higher than the voltage of 0.56V observed in electrolytes without additives. The strong oxidizing properties of these additives promote the dissolution reaction of the Al anode through substitution reactions, resulting in the rupture of the passivation film. In addition, MnO2 is also generated in the case with KMnO4, and then gathers on the surface of Al anode to hinder the discharge reaction, especially for the case with excessive additive. This work explores the effect of oxidant additive on enhancing activation property of Al anode, and provides a guidance of additive choosing in near-neutral electrolyte for AAB.