Anodic dissolution of metals in ionic liquids

• Main Authors: Andrew P. Abbott, Gero Frisch, Jennifer Hartley, Wrya O. Karim, Karl S. Ryder
• Format: Article
• Language: English
• Published: Elsevier 2015-12-01
• Series: Progress in Natural Science: Materials International
• Subjects: Ionic liquid; Deep eutectic solvent; Speciation; Electropolishing; Passivation
• Online Access: http://www.sciencedirect.com/science/article/pii/S1002007115001239

The anodic dissolution of metals is an important topic for battery design, material finishing and metal digestion. Ionic liquids are being used in all of these areas but the research on the anodic dissolution is relatively few in these media. This study investigates the behaviour of 9 metals in an ionic liquid [C4mim][Cl] and a deep eutectic solvent, Ethaline, which is a 1:2 mol ratio mixture of choline chloride and ethylene glycol. It is shown that for the majority of metals studied a quasi-passivation of the metal surface occurs, primarily due to the formation of insoluble films on the electrode surface. The behaviour of most metals is different in [C4mim][Cl] to that in Ethaline due in part to the differences in viscosity. The formation of passivating salt films can be decreased with stirring or by increasing the electrolyte temperature, thereby increasing ligand transport to the electrode surface.