An efficient approach for preparation of battery-grade Li2CO3 from intermediate product Li2SiO3

The continuous development of lithium-ion batteries (LIBs) manufacturing industry calls for the mass production of Li 2 CO 3 , which serves as a pivotal raw material for LIBs. In our previous study, Li was successfully precipitated as intermediate product Li 2 SiO 3 from an alkaline solution containing Si by the hydrothermal precipitation method, realizing the preliminary separation of Li and impurities. In this research, H 2 SO 4 digestion-water leaching-Na 2 CO 3 precipitation process was proposed to manufacture Li 2 CO 3 from the intermediate product Li 2 SiO 3 . Firstly, the reaction feasibility of H 2 SO 4 digestion-water leaching and direct H 2 SO 4 leaching for Li 2 SiO 3 were comparatively evaluated through thermodynamic calculation and experimental research. Compared to direct H 2 SO 4 leaching, H 2 SO 4 digestion-water leaching process is preferred in view of its excellent filtration properties. Subsequently, systematic digestion and leaching experiments showed that up to 97.1 % of Li was extracted under the optimized conditions, and the concentration of Li in the leach liquor is as high as 29.33 g/L. After pH adjustment and Al removal, Na 2 CO 3 precipitation were adopted for Li 2 CO 3 production. The equilibrium relationship in Li 2 SO 4 -Na 2 CO 3 -H 2 O system was analyzed to predict the precipitation behavior of Li and select appropriate operation window for Li 2 CO 3 preparation. Finally, with an additional carbonation-decomposition process, a Li 2 CO 3 product with a purity of 99.51 % is produced. This process realizes efficient synthesis of battery-grade Li 2 CO 3 from the intermediate product Li 2 SiO 3 .