We propose an effective method for selectively extracting the valuable metals from the spent LiNixCoyMn1-x-yO2 cathode material using an oxalic acid-based deep eutectic solvent. Through regulation of the coordination environment, NiO, Co3O4, and Mn3O4 are stepwise separated and further applied in the electrochemical conversion of raw PET bottles to high-purity formic acid.