A green and effective room-temperature recycling process of LiFePO4 cathode materials for lithium-ion batteries

Nowadays LiFePO 4 cathode develops rapidly for its advantages of long life span, low cost and non-toxicity, especially in electrical vehicle markets. Because of its stable olivine structure, LiFePO 4 is difficult to be recycled by the conventional hydrometallurgical processes as for LiCoO 2 or LiNi x Co y Mn z O 2 . Pyrometallurgical processes consume much energy and release toxic gases. Herein, an effective room-temperature process based on the mechanochemical treatment is proposed to extract metals from LiFePO 4 . Spent LiFePO 4 is co-grinded with low-cost citric acid agent in a ball mill. After grinding, the mixture is dissolved in deionized water and filtrated. With addition of H 2 O 2 , the extraction efficiency of Li reaches as high as 99.35%. Conversely, Fe is hardly extracted with a low extraction efficiency of only 3.86%, indicating a selective recovery of valuable Li element. In addition, when H 2 O is used instead of H 2 O 2 , the mechanochemical reaction changes and the extraction efficiencies of Li and Fe at optimal conditions reach 97.82% and 95.62%, respectively. The Fe impurity is removed as Fe(OH) 3 precipitation by adding NaOH, and Li is recycled as Li 2 CO 3 after reaction with saturated Na 2 CO 3 at 95 °C. This simple and easily-operated process has little negative impact on the environment and has great potential in industrial applications.