Corrosion protection mechanism of maltoheptaose on aluminum anodes for enhanced performance in alkaline aluminum-air batteries

Abstract

Al-air batteries are considered a novel and promising energy source. However, the self-corrosion of the aluminum anode limits their commercial viability by reducing both battery life and capacity. In this study, we introduce maltoheptaose (ZK₅) as an inhibitor, added to the electrolyte of an alkaline Al-air battery. Electrochemical tests, surface analysis, computational calculations, and hydrogen evolution experiments were conducted to evaluate its inhibitory effects. The results demonstrate that the Al-air battery with the ZK₅ containing electrolyte exhibits significantly suppressed self-corrosion and enhanced electrochemical performance. Consequently, the presence of ZK₅ leads to a substantial increase in both capacity and energy density. Specifically, the capacity density of the Al-air battery with 10⁻³ M of ZK₅ in a 4 M NaOH electrolyte reaches 1000 mA.h.g⁻¹, which is 4.9 times higher than in the 4 M NaOH electrolyte alone. These experimental findings are further supported by Density Functional Theory (DFT) analysis, which confirms improved anode passivation and favorable molecular interactions, reducing corrosion of the aluminum anode.