Selective Extraction of Lithium from Spent Ternary Cathode Materials via Graphitic Reduction

Spent ternary lithium-ion batteries contain abundant valuable lithium, and their recycling can alleviate environmental pollution pressure and reduce resource waste. This study adopts graphite reduction roasting of ternary cathode materials combined with a CO₂ leaching process to selectively recover lithium from ternary cathode materials (NCM523).Thermodynamic analysis of the cathode material reduction process was conducted using HSC Chemistry 9.0 software and TG-DTA to investigate the forms of reduction products at different roasting temperatures. The effects of factors including roasting temperature, time, and graphite content on metal phase transformation and leaching efficiency were systematically investigated. The phase composition and morphology of the reduction roasting products were characterized by X-ray diffraction and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). The results indicate that at a roasting temperature of 650 ℃, roasting time of 120 min, and graphite mass fraction of 15%, the cathode materials dissociate and are reduced to Li₂CO₃, NiO, CoO, MnO, Ni, and Co. Under the optimal leaching conditions (liquid-solid ratio of 15 mL/g, leaching duration of 210 min, and CO₂ flow rate of 100 mL/min), the lithium leaching rate reaches 94.17%, while other valuable metals (nickel, cobalt, manganese) are barely leached. This process achieves selective lithium extraction from spent ternary cathode materials and its efficient separation from nickel, cobalt, and manganese.