The influence of the molar ratio of AlCl3 to DMI and the electrochemical behavior of aluminum and magnesium in the 1,3-Dimethyl-2-imidazolidinone-AlCl3-MgCl2 system

The effect of the AlCl 3 content on the solubility, conductivity, ionic structure, and electrochemical behavior of Al in the 1,3-Dimethyl-2-imidazolidinone-aluminum chloride (DMI-AlCl 3 ) electrolyte system was studied. The results indicate that when the molar ratio of AlCl 3 to DMI is less than 1.0, there are anions [AlCl 4 ] − , cations [AlCl 2 (DMI) 4 ] + , and neutral molecules [AlCl 3 (DMI) 2 ] in the system. When the molar ratio is greater than 1.0, [AlCl 4 ] − will react with AlCl 3 and form [Al 2 Cl 7 ] − . As the molar ratio increases, the conductivity of the system gradually decreases, the concentration of [Al 2 Cl 7 ] − ion increases and under the same conditions, the electrodeposited products increase. After adding MgCl 2 in the DMI-AlCl 3 ( x  = 1.6) system, the structure of aluminum ions in the system will change, and magnesium exists in the form of [MgCl(DMI) 4 ] + . The cyclic voltammetry and square wave voltammetry results show that the electrochemical reduction of aluminum and magnesium is controlled by diffusion. The XRD and XPS results indicate that magnesium exists in the form of Al 12 Mg 17 in the deposits, with a content of approximately 6.4 wt%.