Influence of an imidazole-based ionic liquid as electrolyte additive on the performance of alkaline Al-air battery

Al-air battery is a kind of chemical battery exhibiting high theoretical energy density. However, the hydrogen evolution corrosion is the primary barrier to its widespread application. Herein, an imidazole-based ionic liquid, i.e., 1-(2-hydroxyethyl)-3-methylimidazolium chloride (HMIC), was examined as a corrosion inhibitor for Al-5052 alloy in 4 M NaOH electrolyte by electrochemical means, hydrogen evolution test and surface characterization. Electrochemical results showed that the inhibition efficiency was 58.2% when the concentration of HMIC was 7 mM, and the anode utilization increased to 82.9%. The findings of X-ray photoelectron spectroscopy (XPS) and molecular dynamics simulation demonstrated that HMIC can adsorb on the surface of Al-5052 to form a protective barrier and prevent the self-corrosion of Al anode. Moreover, the addition of HMIC significantly improved the discharge performance of the Al-air battery, with a nominal specific capacity (2469 mAh g−1) and energy density (3313 Wh kg−1). This electrolyte regulation strategy offers a way to enhance the Al-air battery's performance in alkaline medium.