Electrochemical Deposition and Dissolution of Aluminum in NaAlCl4 Melts: Influence of MnCl2 and Sulfide Addition

Qingfeng Li, H.A. Hjuler, Rolf W. Berg, Niels Bjerrum

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Effects of the additives MnCl2, sulfide, and their combined influence on aluminum deposition and dissolution inNaAlCl4 saturated with NaCl have been studied by polarization measurements, galvanostatic deposition, and current reversalchronopotentiometry (CRC). The solubility of MnCl2 was found to be 0.086 ± 0.006 m/o in the melt at 175°C. Aluminum-manganesealloys can be deposited in NaAlCl4 saturated with both NaCl and MnCl2, resulting in a slight increase incathodic overpotentials. The codeposition of the binary alloys at current densities below 4 mA/cm2 gave rise to formationof deposits so compact that their specific average volumes are of the theoretical value. The content of manganese in thealloy deposits was found to be between 8–11 a/o. It was found that the manganese content in the deposits did not dependon the current efficiency. The presence of sulfide in NaAlCl4 results in the formation of more spongy deposits at low currentdensities, and thus destroys the beneficial effects of MnCl2 when both additives are present, but prevents formation ofdendritic deposits at high current densities. Coulombic ratios of dissolution to deposition were found by CRC measurementsto be affected by the nature of the substrate.
Original languageEnglish
JournalJournal of The Electrochemical Society
Issue number9
Pages (from-to)2794-2798
Publication statusPublished - 1990

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Copyright The Electrochemical Society, Inc. [1990]. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS).

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