Selective lithium extraction from spent LiNixCoyMn1-x-yO2 batteries by co-pyrolysis with waste polyvinyl chloride plastics

The selective extraction of lithium from spent lithium-ion batteries has attracted wide interest owing to its strategic value and scarcity of resources. Meanwhile, serious environmental issues have been generated by waste polyvinyl chloride (PVC) plastics around the world. In this study, a synergetic treatment method was investigated to achieve the selective extraction of lithium. Under optimal conditions, the lithium recovery efficiency was 90.60 %, while Co, Ni, and Mn from the spent lithium-ion batteries remained in the leaching residue. Thermodynamic calculations, XRD, XPS, and SEM-EDS revealed the reaction mechanisms that the Li in the spent batteries was converted to soluble LiCl and Li₂CO₃ during the co-pyrolysis process while the high oxidation states of Ni, Co, and Mn were reduced into water-insoluble substances such as metallic Ni, CoO, and (NiO)_0.75(MnO)_0.25. The formation of LiF was the main reason for the loss of lithium. Overall, it is a win-win strategy that waste polyvinyl chloride plastics are used for the Li extraction of the spent lithium-ion batteries, as it not only recovers the strategic metals but also controls the pollution of solid wastes.