Study On Preparation Technology Of Battery Grade Lithium Carbonate

Battery-grade lithium carbonate is an important raw material in preparation process of cathode materials of lithium ion batteries such as lithium iron phosphate, lithium manganese oxide and so on. It could also be used as electrolyte additive of lithium ion, improving their safety performance and using life. It is the key raw material for lithium-ion batteries.In this paper, the applications and resource distribution of lithium carbonate were firstly presented. Then the categories, properties and preparations of lithium carbonate were ntroduced. Battery-grade thium carbonate was prepared by carbonation-decomposition method using the industrial-grade lithium carbonate. The processes of carbonation reaction conditions, cycle decomposition and lithium phosphate removing calciums were studied.In the carbonation process, The effect of carbonation conditions, such as carbonation temperature, CO2 flow rate, carbonation time and the ratio of solid phase and liquid phase (S/L), on the purification was further investigated. The optimal carbonation conditions, the carbonation conditions being 25 ℃, the CO2 flow rate being 4L/min, the carbonation time being 30 min, the ratio of solid phase and liquid phase (S/L) being 1:30 were determined. The purity and the productivity of product were relatively high under above carbonation conditions.The effects of cycles of the mother liquor, dry product, wet product, dry product with mother liquor and wet product with mother liquor on purity, productivity and removal of Na, K, Ca, Mg of Li2CO3 were mainly investigated. Results showed that mother liquor cycles of three times, dry product cycle of one time, wet product cycles of three times and dry product with mother liquor cycles of five times and wet product with mother liquor cycles of four times could improve the purity and control the contents of Na, K, Ca, Mg containing in product under the standard of battery-grade Li2CO3 with low productivity losing.For the Ca to removal problem, Using carbonation-decomposition method combined with the experiments about removal process of Ca by Li3PO were studied emphatically, The effects of addition quantity of Li3PO4, reaction temperature and reaction time on removal of Ca and the productivity of products were intergrated in this research. On this basis, the experimental studies about removing Ca by combining Li3PO4 and cycles of carbonation-decomposition method were also researched. The effects of combining Li3PO4 and four types cycles of carbonation-decomposition (containing dry product, wet product, dry product with mother liquor and wet product with mother liquor) and on removal of Ca and the productivity of products were investigated. Experimental results show that the reaction conditions impact the removal of Ca and the productivity of products at different levels. The best reaction condition is obtained as follow:addition quantities of Li3PO4 of 1g, the reaction time of 2h, the reaction temperature of 50℃. Under the best conditions, the removal rate of Ca could reach above 60%. The content of Ca could raech to 0.0039% in the lowest by combing Li3PO4 and cycle of wet product with mother liquor, which basically meet the requirements standard of battery grade Li2CO3.