A team from Central South University in China has developed a new type of deep eutectic solvent (DES) that can efficiently leach metal elements from spent Ni-Co-Mn lithium-ion batteries (LNCM). The leaching rates of Ni, Co, Mn, and Li can all reach 99% under the conditions of T=140°C, t=10 min and no reductant. Deep eutectic solvents are a new class of green electrolyte materials with properties analogous to that of ionic liquids (ILs).

An open-access paper on the work is published in the RSC journal Green Chemistry.

DESs, first proposed by Abbott in 2003, are a class of low eutectic mixtures comprising a combination of a hydrogen-bond acceptor (HBA) and a hydrogen-bond donor (HBD) through intermolecular hydrogen bonding, which have a melting point lower than that of either constituent. DESs, as green extraction media of metal oxides, were first used to leach LIBs in 2019.

…To date, most research on DES has focused only on the recycling of LCO batteries, which limits the broad application of DESs in the field of LIB recycling. In reality, the production of nickel–cobalt–manganese (NCM) lithium-ion (LNCM) batteries is much larger than that of LCO batteries. Thus, a new DES that can leach and recover valuable metals from LNCM is urgent to develop.

In the present paper, a novel hydrometallurgical process relying on the applications of a betaine hydrochloride (BCl)-EG DES (hereafter denoted as B-DES) is proposed to leach Ni, Co, Mn, Li from LNCM. BCl is an efficient, high quality, and economical nutritional additive that is extensively used in the field of livestock, poultry, and aquaculture. With environment-friendly and degradable characteristics, B-DES is a green leaching agent.

—Luo et al.

Flow chart of recycling spent LIB cathode material. Luo et al.

Resources

• Yi Luo, Chengzhe Yin, Leming Ou and Chenyang Zhang (2022) “Highly efficient dissolution of the cathode materials of spent Ni-Co-Mn lithium batteries by using deep eutectic solvents” Green Chem. doi: 10.1039/D2GC01431A