Two birds, one stone: lithium extraction and halogens fixation via CaCl2-assisted co-pyrolysis of spent LiNixCoyMnzO2 cathode material and fluorinated organic wastes

Lithium-selective extraction from waste lithium-ion batteries (LIBs) has attracted wide attention. Among various recycling methods, pyrolysis reduction-water leaching has been viewed as the most promising one, because parts of reductants can be replaced by the battery’s own organic matters, such as the binders (polyvinylidene fluoride (PVDF)). However, the existence of fluorinated organics results in a significant decrease in Li leaching efficiency as well as the generation of hazardous gas containing F. In this study, a novel dual-function approach is proposed by adding CaCl 2 into the co-pyrolysis process of waste NCM powders and fluorinated organic wastes, which effectively improves the Li recovery together with achieving the fixation of halogens. The PVDF was selected as the main example to demonstrate the feasibility of the new method, which was further confirmed by two other fluorinated organics (electrolyte and Teflon). Thermodynamic calculation, XRD, XPS, and SEM-EDS are used to investigate reaction mechanisms for enhancing lithium recovery and halogen fixation. During the co-pyrolysis, the Li in the NCM is transformed into LiCl instead of forming insoluble LiF; meanwhile, the F in the PVDF is converted into CaF 2 , which is fixed in the residue rather than releasing in the air. The Cl in the CaCl 2 is also converted into the valuable product of LiCl. Under the optimal conditions, the Li water-leaching rate reached 98.88 %, and the fixation rates of F and Cl were 92.54 % and 98.71 %, respectively. This strategy also extends to the synergistic treatment of various fluorinated organic wastes with the spent LIBs. Therefore, the proposed method is more economically effective and environmentally friendly.