Abstract:
A high-value recycling method was introduced for spent lithium iron phosphate (LFP) cathode materials. Fe, P, and Li elements were recovered in the forms of FeSO
4, FePO
4, and Li
3PO
4, respectively. The recycling yield of Li recovered in the form of Li
3PO
4 reached 93%. The recycling process was free of phosphoric acid and phosphate and involved five steps: ① dissolving the waste lithium iron phosphate cathode material with sulfuric acid; ② recrystallizing more than one-third of Fe
2+ ions as FeSO
4; ③ oxidizing the remaining Fe
2+ ions and adjusting the pH value of the solution to 2.0 ~ 3.0 to precipitate Fe
2+ ions of FePO
4, which can be used for solid-phase preparation of LiFePO
4; ④ adjusting the pH value of the filtrate after separating FePO
4 to 11.0, where the concentrations of Li
+ ions and PO
43- ions met the precipitation conditions to precipitate Li
3PO
4; ⑤ using the obtained ferrous salt and Li
3PO
4 to prepare LiFePO
4 by hydrothermal methods, with the resulting LiFePO
4 exhibiting good electrochemical performance.