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

Abstract

<p>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.<br></p>