Study on Phase Transformation in LiFePO4-Na2CO3 Roasting System and Recovery of Li and Fe
LiFePO4 is widely used as a positive electrode material in electric vehicle power batteries,and its recycling theory and process after scrapping are currently a hot research topic.This paper proposes a new recovery method for extracting Li and Fe from LiFePO4 using alkaline roasting combined with acidic leaching,and studies the phase transformation during the roasting process of the Na2CO3-LiFePO4 system.The results showed that the Na2CO3-LiFePO4 reaction system was mixed at a mass ratio of 1∶0.67 and calcined at 800～950 C.The process was a complex reaction involving compound chemical decomposition,oxidation reaction and compound formation reaction.The phase composition of the calcined product was Fe2O3,Fe3O4,NaLi2 PO4,LiNa5(PO4)2.Under the conditions of using phosphoric acid solution(pH=0),leaching temperature of 50 C,leaching time of 60 minutes,and liquid-solid ratio of 20 mL/g,and using phosphoric acid to control the leaching termination pH=1,the leaching rate of Li in the calcined products is greater than 98％,while the leaching rate of Fe is less than 9％.
spent lithium-ion power batteriesLiFePO4roastingmetal recoveryphase transformation
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