Preparation of Battery Grade Li2CO3 from Defective Product by the Carbonation‐Decomposition Method

Abstract

AbstractBattery grade Li2CO3 is successfully synthesized by the carbonation‐decomposition method using defective crude Li2CO3 with the purity of 98.56 wt% containing 5873 ppm SO42− and other impurities such as Na, K, Ca, Fe, and Mg. Filter operation is found to be very important to improve quality of products. The purified Li2CO3 precipitation acquired by filtering the LiHCO3 solution possesses a higher purity of 99.65 wt% and greater whiteness with lower amounts of SO42− (222.0 ppm) and Fe (6.6 ppm). For further purification, ethylenediaminetetraacetic acid disodium salt is added into the LiHCO3 solution then Ca and Fe contents in purified Li2CO3 are reduced to 2.9 and 0.7 ppm, respectively. The removal efficiencies obtained for Ca, Fe, and SO42− are of 80.05%, 99.4%, and 97.5%, respectively. The research of reaction kinetics shows that the rate‐determining step of the carbonation process is diffusion control and the generated HCO3− ions can resist the further dissolution of CO2. The theoretical thermal decomposition temperature is 277.10 K by the thermodynamic calculation. SO42− impurity comes from absorbed Na2SO4 and doped Li2SO4. This work is of great significance to economically and simply treat defective product with high impurity content in the actual Li2CO3 production process.