Recyclable deep eutectic solvents for recycling LiCoO2 from spent lithium-ion batteries with high selectivity

The use of green deep eutectic solvents (DESs) to recover valuable metals from spent lithium-ion batteries is both environmentally and economically beneficial. In this work, we proposed a novel method for recovering the cathode material, LiCoO2. LiCoO2 was selectively leached using a DES, comprised of chloroacetic acid and tetrabutylammonium chloride, with oxalic acid added. Cobalt was totally leached, and lithium was converted into Li2C2O4 and precipitated in the DES. After filtration, Li2C2O4 was obtained and the DES with dissolving Co was yielded. When water was added to the DES, cobalt precipitated as oxalate. Finally, after simply evaporating water in the DES, it could continue to be reused as a leaching agent. Importantly, LiCoO2 with a 100% yield could be recovered via the DES recycling process. The mechanism of LiCoO2 leaching with the DES was revealed. We have successfully created a recyclable method that is ecologically benign and acceptable for the lithium-ion battery recycling industry.