Recycling Lithium-ion Battery Cathode Materials using Brønsted Acidic Deep Eutectic Solvents

Background ^{1, 2}

To combat global climate change, the use of electric vehicles has become more and more important for reducing greenhouse gas emissions from the transportation sector. The rechargeable lithium-ion batteries (LIBs) have been intensively used in electronic products. A great demand for LIBs will inevitably lead to a great number of spent LIBs due to the limited life spans of LIBs and the upgrade of electronic products. The unsuitable disposition method (e.g., landfill) of the spent LIBs will cause serious environmental pollution such as soil and groundwater contamination by the leaked hazardous materials. In the meantime, the spent LIBs contain a variety of precious metals (such as lithium Li, cobalt Co, nickel Ni, manganese Mn), which are excellent secondary resources for manufacturing LIBs. Therefore, recycling these spent LIBs to recover precious metals is very necessary and urgent from the viewpoints of environmental protection and resource savings.

Recently, a new green recycling approach based on green solvents (deep eutectic solvents, DESs) has raised a lot of attention for it avoiding the use of aggressive aqueous media and good metal oxides leaching ability under mild conditions.² DES is a eutectic mixture typically formed with a hydrogen-bond acceptor (HBA), for example, a quaternary ammonium halide salt, and a hydrogen-bond donor (HBD).³ DESs are lower toxicity, biodegradable, easy to synthesise, and no waste is generated during their preparation and thus, DESs have been proposed as environmentally benign alternatives in different applications including metal processing. Several DESs have been studied in recycling LIB cathode materials. The acidity of DES and operating temperature play important roles during the leaching process. In addition, the high viscosity of DES greatly affects the leaching rate. Therefore, it is important to design low viscosity brønsted acidic DESs with a high leaching rate and leaching efficiency. In addition, the recovery of metals and DES from DES leaching liquor is quite important in order to develop a close loop battery recycling process.

The Project

In this project, several DESs will be synthesized and tested for leaching LIB cathode materials (NMC/LCO) to recycling high-value metals. Crystallization or precipitation process will be investigated to recover metals as valuable products. Thisproject contributes to the aim of green battery recycling. The project is funded by the Swedish Energy Agency and is performed in collaboration with Uppsala University. The industrial reference group in this project is from Northvolt AB.

Major activities:

• Literature overview and project goal setting
• Preparation of DESs and characterization
• Leaching NMC/LCO with DESs and investigating the leaching efficiency
• Laboratory experiments of metals recovery from DES leachate by crystallization or precipitation
• Data evaluation and processing
• Report writing

For questions or to express your interest, please contact:

Chunyan Ma (chunyan@kth.se), Kerstin Forsberg (kerstino@kth.se) or Michael Svärd (micsva@kth.se)

References

[1] G. Harper, R. Sommerville, E. Kendrick, L. Driscoll, P. Slater, R. Stolkin, A. Walton, P. Christensen, O. Heidrich, S. Lambert, A. Abbott, K. Ryder, L. Gaines, P. Anderson, Recycling lithium-ion batteries from electric vehicles, Nature, 575 (2019) 75-86.

[2] M.K. Tran, M.T.F. Rodrigues, K. Kato, G. Babu, P.M. Ajayan, Deep eutectic solvents for cathode recycling of Li-ion batteries, Nature Energy, 4 (2019) 339-345.

[3] E.L. Smith, A.P. Abbott, K.S. Ryder, Deep Eutectic Solvents (DESs) and Their Applications, Chemical Reviews, 114 (2014) 11060-11082.