Recovery of fluorine-containing resources from spent lithium-ion batteries as high-value products

Abstract

The fluorine-containing organics in the spent lithium-ion batteries (LIBs) cause environmental pollution during recycling. Recovery of fluorine-containing resources is critical for the recycling process of spent LIBs. This study elucidated the transformation mechanism of fluoride in cathode black mass (BM) during pyrolysis and proposed an integrated approach for fluoride reclamation. At 650 °C, 89.7 % of fluorine was primarily migrated to the gas phase, while 10.3 % was retained in the solid residue. The fluorine in the gas phase was absorbed using water and converted into HF solution and the absorption efficiency was 96.4 % under the optimal conditions. Acid leaching was used to dissolve the LiF in the BM pyrolysis residue. Subsequent acid leaching effectively dissolved residual LiF from the solid pyrolysis product. Fluidized-bed crystallization was then applied to recover fluorine from the leaching solution as large-sized CaF₂ particles. The total amount of fluorine recovered from BM through both pathways was 94.5 %.