Recovery of Lithium, Iron, and Phosphorus from Spent LiFePO 4 Batteries Using Stoichiometric Sulfuric Acid Leaching System

A selective leaching process is proposed to recover Li, Fe, and P from the cathode materials of spent lithium iron phosphate (LiFePO 4 ) batteries. It was found that using stoichiometric H 2 SO 4 at a low concentration as a leachant and H 2 O 2 as an oxidant, Li could be selectively leached into solution while Fe and P could remain in leaching residue as FePO 4, which is different from the traditional process of using excess mineral acid to leach all the elements into solution. Under the optimized conditions (0.3 M H 2 SO 4, H 2 O 2 /Li molar ratio 2.07, H 2 SO 4 /Li molar ratio 0.57, 60 °C, and 120 min), the leaching rates of 96.85% for Li, 0.027% for Fe, and 1.95% for P were recorded. The Li contained in solution was then recovered by introducing Na 3 PO 4 as a precipitant. Around 95.56% Li was precipitated and recovered in the form of Li 3 PO 4 under the experimental conditions. In addition, the FePO 4 in the leaching residue was directly recovered by burning at 600 °C for 4 h to remove carbon slag. This study illustrates an effective process for the recycling of spent LiFePO 4 batteries in a simple, efficient, and cost-effective way, which give it potential to be industrially applied.