The electrochemical deposition of a number of reactive metals such as Al, Ta and Nb from ionic liquids (ILs) generated high interest during the last decades. Their deposition from aqueous solutions is not possible since these metals have a rather negative Nernst potential. Non-aqueous media have a broader electrochemical window (> 3 V) and offer new possibilities for industrial applications by electrochemical plating of highly reactive metals.

Due to its excellent properties such as high conductivity and the formation of a dense oxide film, the possible applications of aluminum range from electronics and optics all the way to coatings for corrosion protection and decorative purposes. The negative standard potential of aluminum (-1.66 V vs. SHE) led to the development of non-aqueous electrolytes used in industrial processes (e.g. SIGAL process), which are often based on highly flammable and/or volatile chemicals, leading to high costs and risks for the operator. ILs are non-flammable, have a high solubility for metal salts and there is no hydrogen embrittlement due to their aprotic nature. Furthermore, continuously decreasing prices for ILs make them more interesting for industrial processes.

Aluminum was one of the first metals electrochemically deposited from ILs. There are a lot of reports about the pure metal and its alloys. However, there are some basic knowledge gaps about the electrochemical kinetics of the aluminum deposition from ILs.

This paper will discuss recent results from the authors’ lab on the electrochemical kinetics of the deposition of aluminium from 1-ethyl-3-methyl-imidazolium based ILs. A number of high and low amplitude step experiments completed by cyclic voltammetry and conductivity measurements were employed to shed light on the diffusion, nucleation and charge transfer mechanism of the aluminium deposition.