Editors: | F. Kongoli, F. Marquis, N. Chikhradze, T. Prikhna, M. De Campos, S. Lewis, S. Miller, S. Thomas. |
Publisher: | Flogen Star OUTREACH |
Publication Year: | 2022 |
Pages: | 290 pages |
ISBN: | 978-1-989820-68-1(CD) |
ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
The demand for high-purity lithium for lithium-ion batteries will continue to grow rapidly. It is necessary to establish a technology to recover lithium from spent lithium-ion batteries with low cost and environmental impact. Electrodialysis using lithium-ion solid electrolytes is a promising candidate technology. However, the recovery rate and energy efficiency are still small, although it has been reported that lithium can be recovered in high purity [1-3]. In the electrodialysis technology, it is generally predicted that the lithium recovery rate will increase according with the applied voltage according to Ohm's law. However, in electrodialysis using La0.57Li0.29TiO3 (LLTO) as an electrolyte, the increase in lithium recovery rate due to increase applied voltage exceeded this prediction. The purpose of this study is to determine the cause of this phenomenon.
An anode (primary solution side) and a cathode (secondary solution side) were formed on both front and back surfaces of LLTO. Reference electrodes were also formed on both surfaces. DC voltage of different magnitude was applied between the anode and the cathode, and the dependence of the applied voltage on the electrolyte resistance was investigated by two-probe AC impedance spectroscopy. The applied voltage dependence on the electrode reaction resistances of the anode and the cathode was investigated by three-probe AC impedance spectroscopy using a reference electrode. Lithium recovery was measured by inductively coupled plasma optical emission spectroscopy.
The electrolyte resistance of LLTO and the anode electrode reaction resistance were constant at all applied voltages. On the other hand, as the applied voltage increased, the cathode electrode reaction resistance decreased in a quadratic manner. The increase in lithium recovery rate, contrary to Ohm's law, is attributed to this decrease in the cathode reaction resistance.
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[2] T. Hoshino, Desalination 317 (2013) 11-16.
[3] T. Hoshino, Desalination 359 (2015) 59-63.