The electrodialysis of lithium sulphate to lithium hydroxide

Hollie Harrison

There is currently an increasing demand for lithium-ion batteries, and therefore a push within the industry to produce lithium hydroxide. Electrodialysis has been shown to be a promising new technology for producing lithium hydroxide. A three-compartment batch electrodialysis cell was constructed, utilising an anionic exchange membrane and a cationic exchange membrane. This cell was constructed in order to produce lithium hydroxide from lithium sulphate salt. The cell was run under multiple different conditions to observe the effect that they would have on the recovery of lithium within the lithium hydroxide of the catholyte compartment within the cell. The initial pH of the solution, the temperature of the system, the initial concentration of lithium sulphate and the residence time within the cell were all tested in separate experiments in order to observe how they would influence the system and the production of lithium hydroxide. The results of this study indicated that by decreasing the initial concentration of the lithium sulphate within the cell, the lithium recovery is dramatically increased, at 30 wt.% lithium sulphate, 18.3% of the lithium is recovered within 4 hours into the catholyte solution as lithium hydroxide. At 5 wt.% lithium sulphate, 81.2% of the lithium is recovered within 4 hours into the catholyte as lithium hydroxide. The results also suggest, the rate of production of lithium hydroxide is fastest when the residence time within the cell is reduced, however, a longer residence time within the cell will increase the lithium recovery. A 4-hour test at 30 wt.% of lithium sulphate yielded a 23.1% lithium recovery within the catholyte solution. When this residence time was doubled, the recovery was increased to 37% lithium within the catholyte as lithium hydroxide.

The electrodialysis of lithium sulphate to lithium hydroxide

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