Using plant extracts to modify Al electrochemical behavior under corroding and functioning conditions in the air battery with alkaline-ethylene glycol electrolyte

Abstract

The electrochemical behavior of 5083 aluminum alloy in an alkaline solution in the absence and presence of two green additives extracted from Mentha piperita L ‘MP’ and Lawsonia inermis ‘LI’ was analyzed in this study. Corrosion-related investigations disclosed the mixed-type adsorptive function of the compounds, which reduced Al parasitic dissolutions and consequent H2 evolutions by about 80% at 800 ppm of each additive. The performance made the Al alkaline corrosion more uniform, probably by removing water molecules from the surface as approved by FE-SEM and EDS. Quantum calculations indicated the molecular adsorption type and the role of influencing functional groups, particularly =O and –COO(H,CH3) which were the most influencing. These results were also confirmed by FT-IR analysis. The effect of the additives on the dissolution of Al anode was investigated under different discharging rates, clarifying how the employed electrolyte containing the green extracts could improve Al anode capacity density by ~2.8 Ah/g and enhance the anode utilization efficiency by ~94% in an air battery. The results of this study can open the way for future investigations to replace the synthetic anti-corrosion additives of Al air-batteries with non-toxic and biodegradable organic ones having similar corrosion inhibition performance without restricting anode discharge currents.