(378b) Development of the Novel Manufacturing Process of High Purity LiOH?H2O from Li2CO3 Using Acetic Acid

Recently, lithium carbonate has been applied as a lithium compound in various fields. As the trend in the future, it is conceivable that the use opportunity of lithium hydroxide-derived positive electrode material increases more than lithium carbonate-derived positive electrode material because lithium is mainly used as a battery. However, the current process using calcium hydroxide requires a large amount of heat of the process because it involves heating and concentration, and a large amount of pure water is required to use a slurry or the like. In other words, it is a process that requires high energy consumption and a large amount of water. This is the source of current environmental problems and causes contradictions.

Therefore, this laboratory aims to develop a synthesis process of lithium hydroxide monohydrate of the quality required for batteries, save energy and save resources of the process. We aimed to develop a crystallization process at room temperature that does not require latent heat, and at the same time focus on the immobilization of carbon dioxide that is synthesized as a by-product, as well as the process by thermal concentration up to now.

In this study, we applied the crystallization process and developed the synthesis process to synthesize high purity LiOH · H₂O from crude Li₂CO₃. There are various methods of crystallization, but in this study, we aimed to apply a crystallization process at room temperature without temperature change, in order to aim at development of an alternative process to heat concentration. In addition, as the crystallization operation, the possibility of high purification was studied from the crystallization operation of both reactive crystallization and antisolvent addition crystallization.

In order to develop a high purity process of LiOH · H2O, it was examined whether the process could be developed using major acids and alkalis. At this time, it has been confirmed that the synthesis process using CH₃COOH is applicable to the above-mentioned crystallization operation. Furthermore, it was confirmed from the XRD analysis result when the reaction was examined that other impurities could be sufficiently removed by using KOH. The amount of poor solvent addition crystallization using CH₃COOH and KOH and the amount of crystallization of the reaction were studied from the crystallization operation. As the crystallization conditions, the temperature is high, the stirring speed is slow, and the shorter the dropping time, the higher the crystals. It has been confirmed that purification can be performed. Finally, we report that it has become possible to increase the crystal purity to 99.95 wt%.