Evaluation of Alloy Anodes for Aluminum-Air Batteries: Corrosion Studies

Aluminum alloys containing small amounts of Zn, Bi, Te, ln, Ga, Pb, and TI, either individually or in various combinations, have been prepared and investigated as possible fuels for alkaline aluminum-air batteries. The binary alloys, containing generally <1% of the alloying elements, exhibit corrosion rates in 4 M KOH at 50 C that are higher than that for pure aluminum in the same medium. Addition of two or more alloying elements can result in a sharp reduction in the open circuit corrosion rate to well below that for aluminum, and several alloys containing Ga, ln, TI, and P that appear promising as high performance fuels were identified. Mechanical processing [cold working (CW)] was found to have little reproducible effect on the corrosion rate, except for Al-0.5% Ga in which case the corrosion rate was found to pass through a minimum at 50% CW. The corrosion rate data also demonstrate that very low concentrations of the alloying elements are sufficient to achieve inhibition and that little is gained by exceeding the critical levels.