Corrosion inhibition of aromatic acids on Al-7075 anode for Al-air batteries with alkaline electrolyte

The severe hydrogen evolution corrosion is the major obstacle for the extensive application of the aluminium-air batteries. In this research, three aromatic acids, i.e. benzoic acid (BEA), iso-phthalic acid (IPA), and trimesic acid (TRA), are performed as corrosion inhibitors for Al-7075 alloy in 2 M KOH water-ethanol (volume ratio 8:2) solution. The results reveal that all of the three aromatic acids are excellent inhibitors for Al-7075 alloy in alkaline medium with the following inhibition efficiency order: BEA > IPA > TRA, and the peak value of inhibition efficiency is 43.7% when 5 mM BEA is added. The addition of aromatic acids significantly improves the discharge characteristics of the Al-air battery, which increases the capacity density (1357.47 mA cm(-2)) and anode utilization (45.6%) remarkably. The results of Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) demonstrate that the protective film, which is composed of Al salts of organic acid (RCOO-Al), is adsorbed on the Al-7075 alloy surface through chemical bonds between Al substrate and the O atoms on C=O groups, which enhances the corrosion and electrochemical characteristics of the Al-7075 anode for Al-air battery with alkaline electrolyte.

Automated summary

This study investigates the corrosion inhibition effect of three aromatic acids on aluminum-air batteries. The results show that all three aromatic acids have excellent inhibition efficiency. The addition of the aromatic acids not only improves the discharge characteristics of the battery, but also enhances the corrosion and electrochemical characteristics of the anode.