Anodic dissolution of aluminum and anodic passivation in [EMIm]Cl-based ionic liquids

The anodic dissolution of aluminum in Lewis acidic ionic liquids consisting of AlCl3 and 1-ethyl-3-methylimidazolium chloride was studied using linear sweep and cyclic voltammetry, an electrochemical quartz crystal microbalance (EQCM) and chronopotentiometry at ambient temperature. Anodic passivation of the working electrode was observed in a 2:1 electrolyte while no passivation was found in a 1.5:1 electrolyte. Chronopotentiometry proves the passivation to be caused by local solidification of the electrolyte due to an increase in the aluminum concentration near the anode. EQCM data support these results.