Quantifying an acceptable open-circuit corrosion current for aluminum-air batteries

Abstract

Primary aluminum-air batteries achieve impressive specific-energy values but suffer from poor shelf life due to corrosion of the aluminum anode in aqueous electrolytes. To solve this problem, researchers investigate numerous corrosion-mitigation strategies. Few rigorously compare the performance of these strategies, and most fail to define a technologically acceptable open-circuit corrosion current. To compete with commercialized zinc-air batteries, aluminum-air batteries need open-circuit corrosion currents less than 0.01 mA cmgeo-2, which we derive by performing a sensitivity analysis on a corrosion model reported here. By conducting a meta-analysis using reported aluminum-air cells, we find that certain ionic-liquid electrolytes and oil-displacement systems enable corrosion currents that meet this metric. In contrast, values for commonly reported aluminum-air batteries using alkaline electrolytes are orders of magnitude too high. Once the aluminum-air community focuses on advancing appropriate corrosion-mitigation strategies, laboratory findings may become commercially relevant. This journal is