Dual Electrolyte Aluminum-Air Flow Battery Using Methanol Anolyte

Abstract

Aluminum-air batteries have received considerable attention as a cost-effective energy storage system due to their high theoretical specific capacity of 2.98 Ah/g. However, corrosion of the aluminum anode in alkaline electrolyte limits their practical application. Herein, this issue was addressed by implementing dual electrolyte flow battery. The cell structure consists of aluminum anode | anolyte | anion exchange membrane | catholyte | air cathode. The anolyte is 3M KOH in methanol containing different percentages of deionized water (0, 5, 10 and 20) wt. %. The catholyte is a gel polymer electrolyte based on Carbopol 940. The results showed that the increase of water content in the anolyte reduces the overpotential of the cell but increases hydrogen evolution (anode corrosion). At 10 mA/cm2 current density, the anolyte without water showed the highest specific capacity of 2,328 mAh/g, which is 78% aluminum utilization. The specific capacity significantly decreases as the water content in the anolyte increases due to the higer rate of the anode self-corrosion.