Dendrite Free Electrochemical Deposition of Aluminum from Al Scrap Using Ionic Liquids

Abstract:

Electrorefining process for dendrite-free aluminum deposition on copper cathodes was investigated by using low temperature AlCl3-1-Ethyl-3-methyl-imidazolium chloride (EMIC) ionic liquid electrolyte. The bulk electrodeposition of aluminum was carried out using aluminum Al scrap as an anode. Experiments were conducted at fixed voltage of 1.5 V, electrolyte concentration (molar ratio AlCl3: EMIC = 1.65) and electrode surface modification (modified/unmodified). The effect of electrode surface modification and deposition time on deposit morphology, cathode current density and their role in production of dendrite-free aluminum deposit was investigated. The deposits were characterized using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results showed that the modified cathode electrodes showed lower over potentials compared to unmodified. The maximum over potentials obtained with unmodified and modified electrode is -0.339 V and -0.653 V, respectively. The average current densities for unmodified and modified copper cathode are 195 A/m2 and 204 A/m2, respectively. The results suggest that electrode surface modification and cathode overpotential play an important role in producing dendrite-free deposit. The critical over potential ( ) for dendrite free deposit for the experimental conditions was calculated. The cathode overpotential of -0.53 V or lower is recommended for dendrite-free deposit of aluminum using copper cathodes in electrorefining of aluminum from aluminum scrap.

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