Aluminum Deposition from Lewis Acidic 1-Butyl-3-Methylimidazolium Chloroaluminate Ionic Liquid ([Bmim]Cl/AlCl3) Modified with Methyl Nicotinate

The electrodeposition of most of technologically important metals has been shown to be possible from a wide range of room temperature molten salts, more commonly known today as 'ionic liquids'. These liquids are currently under intense scrutiny for a wide variety of applications some of which have already been commercialized. Despite the fact that electrodeposition was the first application studied in these liquids no metal deposition processes have as yet been developed to an industrial scale. This review addresses the practical and theoretical aspects that need to be considered when choosing ionic liquids for metal deposition. It details the current understanding of the physical and chemical properties of these interesting fluids and highlights the areas that need to be considered to develop practical electroplating systems. The effect of composition and temperature on viscosity and conductivity are discussed together with the fundamental approaches required to synthesise new liquids.

In addition to their stability, the advantages of air- and water-stable ionic liquids over chloroaluminate ionic liquids, which were intensively investigated in the past, are that they are easy to dry, purify, and handle. Moreover, some of these ionic liquids have an extremely large electrochemical window of more than 5 V, and hence they give access to the electrodeposition of many metals and semiconductors, such as Ta, Ti, Si, and Ge. The results to date for the electrodeposition of metals and semiconductors in the most popular air- and water-stable ionic liquids are presented.