Corrosion behaviour improvement from the ultrafine-grained Al-Zn-In alloys in Al-air battery

Corrosion of aluminium anode in alkaline solution is a challenging matter for the development of a long-life aluminium anode in Al-air battery. This research focuses on grain size reduction by equal channel angular pressing (ECAP) of Al, Al-Zn, and Al-Zn-In samples. The average grain size of all samples after ECAP is lower than 1 mu m. Open circuit potential, potentiodynamic polarisation, electrochemical impedance spectroscopy, and self-corrosion test were carried out to study the effects of alloying elements (Zn, In) and grain size reduction by ECAP on the electrochemical behaviours of aluminium alloy anodes. The results show that alloying element, zinc, can improve the stability of ion dissolution by porous Al2ZnO4 film formation. Indium can activate ion dissolution that causes enhanced electrochemical activities for Al-Zn-In sample. Moreover, increasing grain boundaries through grain size reduction can enhance more negative potential and cause a uniformly corroded surface of Al-Zn-In sample, leading to a longer anode life in alkaline solution. (c) 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).