Anodic Dissolution Behavior of Al Alloys Containing Al 6 Fe or β-AlFeSi in EmImCl–AlCl 3 Electrolyte During Electrorefining

• Published in: Journal of the Electrochemical Society 2023-12, Vol.170 (12), p.122501
• Main Authors: Nunomura, Junji, Matsushima, Hisayoshi, Kyo, Yoshihiko, Kojima, Yoichi, Ueda, Mikito
• Format: Article
• Language: English
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1945-7111/ad0ea3

To produce over 99.9% of high-purity Al from Al alloys containing Al 6 Fe or β -AlFeSi through electrorefining, their anodic dissolution and cathodic electrodeposition characteristics should be clarified. In this study, the anodic dissolution and cathodic electrodeposition behavior of Al–Fe binary and Al–Fe–Si ternary alloys were investigated in an EmImCl–AlCl 3 ionic liquid electrolyte at 323 K. Anodic polarization measurements, constant potential electrolysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), field-emission SEM (FE-SEM), and energy dispersive spectroscopy (EDS) were used to study the anode and electrodeposits on the cathode. Constant potential electrolysis showed that Fe dissolved from Al 6 Fe in the Al–Fe anode at 0.7 V vs Al/Al(III) and from β -AlFeSi in the Al–Fe–Si anode at 1.4 V and was co-deposited with Al on the cathode. Notably, Si did not dissolve from β -AlFeSi at either potential. A combination of controlled anodic dissolution potential and the use of the Al alloy containing β -AlFeSi further suppressed the dissolution and cathodic co-deposition of Fe, affording high-purity Al on the cathode. This suggests that Al alloys with intermetallic compounds that are less likely to dissolve Fe at the anode are optimal for obtaining over 99.9% of high-purity Al from Al alloys containing Fe in the electrorefining method.