Regeneration of LiFePO₄ from Spent Materials: Control and Influence of Al Impurity

Owing to the rapid increase of lithium iron phosphate (LiFePO₄) batteries, recycling and regeneration of LiFePO₄ enjoys significances for sustainable development and environmental protection. In this study, an effective regeneration method for spent LiFePO₄ materials and the influence of Al impurity on the electrochemical performance of regenerated LiFePO₄ were studied. Firstly, 99.26 % Fe, 99.52 % P, 99.58 % Li, 59.36 % Al and 20.24 % Cu in spent LiFePO₄ material were leached with 150 g ⋅ L^-1 H₂SO₄. Subsequently, Al removal and control were achieved by simply adjusting the pH value, and FePO₄ ⋅ 2H₂O precursors with different Al contents were prepared. Specially, the LiFePO₄ regenerated by FePO₄ ⋅ 2H₂O precursor containing 0.096 % Al exhibits excellent electrochemical performance with discharge capacity of 145 mAh ⋅ g^-1, 140.5 mAh ⋅ g^-1 and 130.9 mAh ⋅ g^-1 at the current density of 1 C, 2 C and 5 C, respectively.