Organic Inhibitors of the Anode Self-Corrosion in Aluminum-Air Batteries

Aluminum-air cells are very attractive systems due to their energy performance, namely their high energy density. Aluminum is a cheap and light material with a very high electropositive electrode potential, but a critical problem is its easy anodic oxidation in aqueous electrolytes complemented by hydrogen discharge. The purpose of this work was to study the electrochemical behavior of aluminum in strong alkaline medium in the presence of water-soluble organic compounds, such as carboxylic acids, amines, and amino acids in the perspective of self-corrosion control. The study was based on determinations of the amount of hydrogen released under potentiostatic polarization with separation of partial anodic and cathodic components. The effect of hydroxyl ion concentration and temperature on the electrochemical behavior of aluminum-water system was also analyzed. From the group of organic substances tested, the majority of them showed a significant inhibitory effect-given the high rate of self-corrosion of aluminum in these environments-especially the following: metacrylaminopropyl-trimethylammonium chloride (10.0 g/l) with an inhibitor efficiency of 69%; trimethylammonium chloride (10.0 g/l), with 67% efficiency; glycine (10.0 g/l) with 56% efficiency; alanine (10.9 g/l) with 40% efficiency; citric acid (10.0 g/l) with 38% efficiency; and tartaric acid (10.0 g/l) with 35% efficiency.