Boosting the Recycling Efficiency of Spent Lithium-Ion Battery Cathodes Using a Green Reductant

One major bottleneck of today's industrial hydrometallurgical lithium-ion battery recycling processes is the limited operation efficiency, particularly for leaching Co, Li, and Ni elements. Boosting the leaching rate and solid to liquid (S/L) ratio can increase the productivity and yield of recycled materials, which can save chemicals and energy cost. Herein, the use of ethylene glycol (EG), a green and sustainable reducing agent, for the separation of spent cathode materials resulting in high leaching efficiencies for very high loadings is demonstrated. The dramatically improved leaching efficiency is attributed to the EG reducing moieties that enable better cathode reduction and dissolution. The separation process avoids the use of toxic organic solvents, making the overall leaching process greener. The leaching efficiency is shown to remain high despite the use of high loadings as compared to the state-of-the-art works. The cathode separation process is then modified to allow for a facile separation of a cathode and anode mixture. This mixture is demonstrated to attain high leaching efficiencies at comparable loadings for cathode-only process. This redox leaching-based recovery process holds a potential for industry adoption due to the elimination of energy-intensive pretreatment step and the high efficiencies obtained.