Enhanced electrochemical performance of Al–0.9Mg–1Zn–0.1Mn–0.05Bi–0.02In fabricated from commercially pure aluminum for use as the anode of alkaline batteries

Abstract

In this study, the electrochemical performance of new fabricated Al–0.9Mg–1Zn–0.1Mn–0.05Bi–0.02In (wt%) from commercially pure aluminum has been determined by using open circuit potential–time measurement (OCP), galvanostatic discharge, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results of scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD) reveal that the main precipitates in Al–0.9Mg–0.1Mn–0.02In and Al–0.9Mg–1Zn–0.1Mn–0.05Bi–0.02In alloys are Mg₂Si and MgZn₂ phases, which act as corrosion centers. The corrosion potentials of mentioned phases are more negative than that of Al. It was found that simultaneous use of alloying elements with the ability to remove the oxide film and high hydrogen over-potential could lead to activation of the alloy with lower self-corrosion rate and improved galvanic efficiency. In order to reduce the harmful effects of iron in the composition of commercially pure aluminum, manganese has been used. The results show that Al–0.9Mg–1Zn–0.1Mn–0.05Bi–0.02In is more active than the Al and Al–0.9Mg–0.1Mn–0.02In anode, and in comparison, the alloy has a lower self-corrosion rate in 4 M NaOH electrolyte. It has been observed that the galvanostatic discharge based on Al–0.9Mg–1Zn–0.1Mn–0.05Bi–0.02In offers more negative voltage and higher anodic utilization than those with Al–0.9Mg–0.1Mn–0.02In and Al.