Selective Recovery of Li and Fe from Spent Lithium-Ion Batteries by an Environmentally Friendly Mechanochemical Approach

Recycling of spent LiFePO₄ batteries has drawn recent attention relating to recovering their high contents of rare elements and negating potential negative environmental effects of their disposal. However, the stable crystal structure of LiFePO₄ materials has prevented the development of a recycling process with high selectivity and extraction efficiency. We report the selective extraction of Fe and Li from spent LiFePO₄ batteries via an environmentally friendly mechanochemical process with oxalic acid. With the use of a mechanochemical treatment and water leaching, the Li extraction efficiency can be improved to 99%. Furthermore, 94% of Fe can be simultaneously recovered as FeC₂O₄·2H₂O. To understand the reaction mechanism and determine the optimum reaction conditions, we investigated various parameters, including the LiFePO₄ to oxalic acid mass ratio, rotation speed, milling time, and ball-to-powder mass ratio. Moreover, metal ions from the water leaching process were recovered by chemical precipitation. This study provides an efficient and selective process for recovery of valuable metals from spent LiFePO₄ materials.