Electrodeposition behavior of aluminum from urea-acetamide-lithium halide low-temperature molten salts

Abstract

Urea-acetamide-lithium halide (LiBr, LiCl, LiF) low-temperature molten salts were used as the electrolytes to study the electrodeposition of aluminum on a tungsten electrode. Al(III) was introduced into the salts by the addition of AlCl3. The reduction potential of Al(III) is dependent on the molar ratio of AlCl3/(urea+acetamide). The nucleation mechanism of aluminum on the tungsten electrode was determined to be three-dimensional instantaneous nucleation with diffusion-controlled growth at 333K. Aluminum coatings were prepared at different cathodic potentials (from −0.10V to −0.25V) and different temperatures (from 313K to 343K) in urea-acetamide-LiBr molten salt. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to characterize the surface of the deposits. The SEM images indicate that the morphologies of the aluminum deposits are dependent on the deposition potential and temperature. The XRD analysis confirms that the obtained deposits are pure aluminum.