Analysis of Oxide Film on Aluminum Electrode in Aluminum-Air Battery

Abstract

In this research, aluminum air battery system was revisited to investigate key issues which have challenged its full application as a rechargeable battery. The Al-air battery had received intense attention once due to the excellent benefits such as low cost and high energy density, but due to the challenging issues such as hydrogen evolution, and inactive oxide film formed on the Al surface, it could not be fully applied. Recently, ionic liquid which is a salt in liquid form at room temperature started to be applied in the battery system to overcome the issues in aqueous electrolyte [1,2], but the inactive oxide film on Al surface is still dominant in decreasing cell performance and detailed research to understand how to control the oxide film was not conducted. In this study, 1-Ethyl 3-Methyl Imidazolium Chloride ([EmIm]Cl) and Aluminum Chloride (AlCl3) was applied in the Al-air battery, and its effect on oxide film on the surface aluminum electrode was analyzed through cell-base test, and SEM image analysis. It was found that the inert oxide film on aluminum, which is one of the most challenging issues, could be controlled and removed by using of proper ratio of [EmIm]Cl and AlCl3, and the growth/breakdown mechanism of the oxide film was theoretically considered. This research results are expected to suggest a new direction to control the surface of aluminum electrode to make it the most promising system.