Recovering Valuable Metals from Spent Lithium Ion Battery via a Combination of Reduction Thermal Treatment and Facile Acid Leaching

The traditional acid leaching process for releasing valuable metals from spent lithium-ion batteries (LIBs) is inefficient and inevitably consumes large amounts of reductants. In this study, a novel process, based on a reduction thermal treatment and reductant-free acid leaching, for recycling valuable metals from spent LIBs has been developed. First, a thermodynamics calculation was performed to judge whether the reducing reaction between LiCoO₂ and graphite can occur or not. Then, reduction thermal treatment experiments were conducted. The process was tested by a thermogravimetry/differential thermal analysis method, and reaction products were measured by X-ray powder diffraction and X-ray photoelectron spectroscopy. The experimental results agree well with thermodynamics analysis, and the desired CoO and Li₂CO₃ were obtained under the optimum processing conditions of 600 °C, 120 min, and molar ratio of LiCoO₂ to graphite of 2:1. Finally, almost 100% Li and Co were easily leached from the reaction product under the conditions of 2.25 M H₂SO₄, 80 °C, 30 min, and S/L = 100 g·L^–1, and Co and Li in the leaching liquor were further separated with 35% PC88 at the ratio of aqueous to organic (A:O) equaling 0.5, 25 °C, and pH = 5.5. The proposed approach can not only make full utilization of waste anode graphite, but also benefit leaching valuable metals in the absence of reductant, which significantly improves the economy and recovery performance of recycling spent LIBs