Microwave-assisted chlorination extraction of valuable metals from spent power ternary lithium-ion batteries

In the present study, a combined process of microwave-assisted chlorination roasting-water leaching was developed to efficiently extract metal ions from spent ternary lithium-ion batteries. Polyvinyl chloride (PVC) was used as chlorine source to generate HCl for chlorination reaction. Activated carbon was first selected as the optimal absorbing medium material. Subsequently, spent anode graphite was used to induce carbonisation reduction reaction with spent LiNixCoyMnzO2 (NCM) to promote recovery of valuable metals. The characterisations of X-Ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and thermodynamic analysis indicated that HCl derived from PVC pyrolysis could spontaneously react with carbonisation reduction products from spent NCM to form the corresponding water-soluble metal chloride for the effective recovery of valuable metals. Under the optimal conditions with reaction temperature at 450°C, material mass ratio PVC:NCM of 4:1, reaction time at 60 min and microwave power at 500 W, 96.43% of Li, 95.51% of Ni, 95.27% of Co and 95.43% of Mn can be recovered, respectively. The leaching kinetics can be described by the Avrami equation with surface chemical reaction controlled, and the leaching activation energies of Li, Ni, Co and Mn were 36.32, 42.31, 38.84 and 41.96 kJ∙mol−1, respectively. This microwave-assisted method might provide a new route for the effective recycling of spent lithium-ion batteries by chlorinated metallurgical processes.