Experimental and theoretical investigation on calcium oxide and L-aspartic as an effective hybrid inhibitor for aluminum-air batteries

In this study, experimental method containing hydrogen evolution test, electrochemical measurement, galvanostatic discharge test and morphology analysis combining with theoretical method containing quantum chemical calculation and Monte Carlo simulation are used to study the inhibition performance of a new hybrid calcium oxide (CaO)/L-aspartic (Asp) inhibitor for AA5052 aluminum alloy anode of alkaline aluminum air batteries. The results show that the hybrid inhibitor has strong inhibitory effect on the self-corrosion and little impact on the discharge performance of AA5052 anode, so the discharge stability and efficiency, safety and storage time of aluminum air batteries are greatly improved. The optimal concentration is 10mM CaO and 4mM Asp. The hybrid inhibitor mainly retards anodic process of self-corrosion reaction, so it is more suitable in the case where discharge current density is not very large. According to the morphology simulation, the (1 (1) over bar0) face of calcium hydroxide (Ca(OH)(2)) is suitable as the adsorption substrate, given that it provides more adsorption active sites. Combining experimental research with theoretical studies, the inhibition mechanism of the hybrid inhibitor is: calcium hydroxide formed from calcium oxide in alkaline electrolyte adheres to the surface of aluminum by geometric coverage effect, and promotes the adsorption of L-aspartic, which active sites are located on the oxygen atom of two hydroxyl groups and the nitrogen atom of amino group, thereby forming Ca(OH)(2)-Asp and Al-Asp monolayer composite films, they effectively block the dissolution of AA5052 alloy. (C) 2018 Elsevier B.V. All rights reserved.