Preparation of FePO4 and LiH2PO4 from cathode mixture materials of scrapped LiFePO4 batteries

• Published in: Journal of materials science. Materials in electronics Vol. 31; no. 5; pp. 4083 - 4091
• Main Authors: Chen, Yongzhi, Wang, Lihua, He, Hao, Li, Jian, Li, Yimin, Liu, Rutie, Li, Dongyang, He, Zheyu
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.03.2020; Springer Nature B.V
• Subjects: Carbon; Cathodes; Characterization and Evaluation of Materials; Chemistry and Materials Science; Electric vehicles; Heat treatment; Hydrometallurgy; Leaching; Materials Science; Optical and Electronic Materials; Powder metallurgy; Reaction time; Recycled materials; Recycling; Separators; Sucrose
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-020-02955-1

Typically, LiFePO 4 batteries (LFPBs) contain a shell, cathode mixture materials, anode mixture materials, current collector, electrolyte, separator, and other components. Cathode mixture materials are composed of a binder, conductive additive, and LiFePO 4 /C. After LFPBs are scrapped, their appropriate disposal is necessary to avoid pollution. This study investigated the recovery of Li, Fe, and P by hydrometallurgy from scrapped LFPBs. To remove the binder, conductive additive, and carbon coating layer, recycled cathode mixture materials are oxidized to Li 3 Fe 2 (PO 4 ) 3 and Fe 2 O 3 at 600 °C. Using H 3 PO 4 as a leaching agent, the optimal leaching efficiencies, i.e., 99.2% and 97.68% for Li and Fe, respectively, can be achieved when the reaction time, temperature, Li in the Li 3 Fe 2 (PO 4 ) 3 and Fe 2 O 3 mixture materials to the H 3 PO 4 molar ratio (L/P ratio), and H 3 PO 4 concentration are 12 h, 95 °C, 1:5, and 0.5 mol/L, respectively. Moreover, Li can be leached into a solution efficiently and recovered as LiH 2 PO 4 , while Fe and P can be selectively precipitated as FePO 4 · x H 2 O. FePO 4 is prepared by a heat treatment. Furthermore, LiFePO 4 /C is re-synthesized by FePO 4 , LiH 2 PO 4 , Fe 2 O 3 , LiOH, and sucrose.