Design and Optimization of an Economically Viable and Highly Efficient Strategy for Li Recycling from Spent LiFePO4 Batteries

Lithium (Li) recycling from spent Li-ion batteries remains a challenge primarily due to the many inherent complexities associated with conventional recycling processes. Herein, a low-cost and highly selective Li recovery strategy was innovatively assembled by employing a stoichiometric H2SO4–H2O2 system for the highly efficient recovery of metal Li from spent lithium iron phosphate (LiFePO4, LFP) power batteries. The LFP cathode material was detached well from the aluminum plate under ambient conditions by using water as a stripping agent. Then, through a well-designed selective leaching process that consumed only very few amounts of acid, Li could be preferably extracted. At the same time, most iron (Fe) and phosphorus (P) were retained within the leaching residue in the form of FePO4. The leaching rates for Li, Fe, and P varied remarkably, accounting for approximately 99, 0.02, and 1.5%, respectively, indicating that a highly selective strategy was achieved. Li ions present within the leaching solution were successfully precipitated as Li2CO3 by introducing Na2CO3 as a precipitant. Simultaneously, the leaching residue was converted directly to FePO4 via calcination at 600 °C for 4 h to eliminate residual organic impurities. The novel stripping method, combined with the optimized H2SO4–H2O2 selective leaching system, demonstrates significant potential for industrial application. The efficacy of this recovery process for spent LiFePO4 ion batteries constitutes a significant advancement toward environmentally sustainable and economically feasible lithium recycling.