**Yeonchul Cho 1, Kihun Kim 1, Jaewoo Ahn 1,\* and Jaeheon Lee <sup>2</sup>**


Received: 26 May 2020; Accepted: 25 June 2020; Published: 28 June 2020

**Abstract:** In order to manufacture lithium carbonate to be used as a raw material for a secondary lithium battery, lithium sulfate solution is used as a precursor, and the concentration of lithium is required to be 10 g/L or more. Electrodialysis (ED) was used as a method of concentrating lithium in a low-concentration lithium sulfate solution, and multistage concentration (MSC) electrodialysis was used to increase the concentration ratio (%). When MSC was performed using a raw material solution containing a large amount of sodium sulfate, the process lead time was increased by 60 min. And the concentration ratio (%) of lithium decreased as the number of concentration stages increased. In order to remove sodium sulfate, methanol was added to the raw material solution to precipitate sodium sulfate, and when it was added in a volume ratio of 0.4, lithium was not lost. Using a solution in which sodium sulfate was partially removed, fourth-stage concentration ED was performed to obtain a lithium sulfate solution with a lithium concentration of 10 g/L.

**Keywords:** electrodialysis (ED); lithium; lithium-ion battery; lithium sulfate; multistage concentration (MSC)
