Metal recovery from end-of-life li-ion batteries

Today, lithium-ion batteries have emerged as a key solution for meeting the demand for sustainable energy sources due to ecological and economic reasons. As the production of electric vehicles increases, the recycling of lithium-ion batteries has become equally important. The environmental and economic pressures arising from the extraction of critical metals such as lithium, cobalt, manganese, and nickel underscore the importance of recycling processes. In this study, end-of-life lithium-ion batteries were mechanically separated into their components. The cathode active powder, separated from the aluminum current collector plate and subsequently homogenized, served as the raw material for experiments. The characterization of the cathode active powder was carried out using various analytical techniques such as inductively coupled plasma-optical emission spectrometry (ICP-OES), X-ray diffraction (XRD) analysis, thermogravimetric/differential thermal analysis (TG/DTA) and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM/EDS). The first part of the study applied the classical leaching method. Different molar ratios of sulfuric acid (H2SO4) solutions were used in classical leaching experiments. Additionally, hydrogen peroxide (H2O2) was added to the H2SO4 solutions as a reducing agent, and the leaching efficiencies of metals (Li, Co, Mn, Ni) from the cathode active powder were investigated based on the reducing agent addition, temperature, duration, and solution concentration. The leaching efficiencies of metals were determined using chemical analysis methods. Furthermore, XRD and TG/DTA analyses were conducted on the leach cakes, and the results were evaluated together. In the second part of the study, the solvometallurgical leaching method was applied. Deep eutectic solvents (DESs) classified into three different hydrogen bond acceptor groups were used as the leaching solution. DESs were characterized using Fourier transform-infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (1H-NMR), and viscosity analysis. The effect of the hydrogen bond acceptor (HBA):hydrogen bond donor (HBD) molar ratio, temperature, duration, solid/liquid ratio, ultrasonic power support, and microwave system assistance on the leaching efficiency of metals from the cathode active powder was investigated using ICP-OES chemical analysis method. XRD and TG/DTA analyses were performed on the leach cakes to support the results. Co-precipitation was carried out using different precipitating agents from different loaded solutions obtained during the leaching experiments. The precursor cathode active powder, obtained from the precipitation, was calcined with Li2CO3 additive to produce regenerated cathode active powder. The regenerated powders were characterized using SEM/EDS, TG/DTA, and XRD methods. Based on the experiments conducted, leaching conditions were optimized for all solutions, and powder with properties suitable for reuse as cathode active material was produced from all solutions subjected to co-precipitation.