Integrated process for separation and recovery of valuable metals from spent LiNi0.5Co0.2Mn0.3O2 cathode materials

Significance 

Lithium-ion batteries have been extensively used in various applications owing to their advantages and high-performance. Typically, they are made up of organic electrolytes, plastics, metals, among other materials. Owing to current stringent measures on sustainability and environmental protection, recycling of valuable metals has attracted significant research attention. Apart from being toxic and a great contributor to the rapid surge in the solid-waste related problems, these metals are valuable and naturally scarce, hence the need to recycle and reuse them. For instance, the cathode materials of ternary batteries contain non-ferrous materials such as nickel, cobalt, and manganese that can be recycled and reused in developing new batteries.

Among the techniques developed to recover valuable metals from lithium-ion batteries, solvent extraction has been identified as a promising technique for separating a mixture of cobalt, nickel, and manganese from LiNixCoyMnzO2 cathode materials. It makes use of the difference in the chemical properties of the metals. This method can also be used to obtain high-quality products through multistage separation. Unfortunately, most of the available extractants are not effective and do not improve the shortcomings of the process. To address the above challenges, Dr. Tianchi Liu, Professor Ji Chen, Hailian Li, and Kai Li from the Changchun Institute of Applied Chemistry, Chinese Academy of Sciences developed a novel integrated process for the separation and recovery of valuable metals from spent LiNi0.5Co0.2Mn0.3O2 cathode materials. Mainly, the separation process involved a combination of leaching, cascade extraction, and precipitation methods. Their research work is currently published in the journal, Separation and Purification Technology.

In their approach, a mixture of 2 mol/L sulfuric acid and 3 vol% hydrogen peroxide reagents were used as leaching agents for the leaching of different metals. Then, the cascade extraction was explicitly used to separate lithium, nickel, cobalt, and manganese using di-(2-ethylhexyl) phosphinic acid (P227) and di-(2-ethylhexyl) phosphoric acid (P204) extractants. Meanwhile, their high purity solid products such as MnO2, Li2CO3, NiO and Co3O4 were also obtained depending on the precipitation procedure. Finally, the overall recovery process of LiNi0.5Co0.2Mn0.3O2 was evaluated to establish the feasibility of the proposed approach.

The authors achieved a leaching rate above 99% for all the metals, which enabled them to obtain high-quality nickel, lithium, manganese and cobalt products. Consequently, they noted that the separation of different metals required different and specific optimal conditions. For instance, one-step extraction was used to separate lithium-nickel and cobalt-manganese by P227, four-stage extraction was used to separate cobalt-manganese by P204, while five-stage extraction was used to separate lithium-nickel by P227. Moreover, high purity solid products were obtained and the final yield for lithium, nickel, cobalt, and manganese was found to be 96.15/100%, 91.54/98%, 91.15/93% and 91.56/100%, respectively.

In summary, the authors reported the design of an integrated process to recover Li, Ni, Mn, and Co metals from LiNi0.5Co0.2Mn0.3O2 cathode materials using P227 and P204 extractants for the first time. Results showed a high recovery yield above 90% for all the solid products. In a statement to Advances in Engineering, Professor Ji Chen said their study provided important theoretical guidance for the development of more effective methods for the separation and recovery of valuable metals from waste lithium-ion batteries.

An integrated process for the separation and recovery of valuable metals from the spent LiNi0.5Co0.2Mn0.3O2 cathode materials - Advances in Engineering

About the author

Dr. Ji Chen is a Professor at the Changchun Institute of Applied Chemistry (CIAC), Chinese Academy of Science, Changchun, China. He received his PhD degree from Changchun Institute of Applied Chemistry, Chinese Academy of Science in 1999 and then moved to the Institute of Process Engineering as a Postdoctoral Fellow. In 2001, he went to Kanazawa University as an Assistant Professor. In 2002, he went to the University of Alabama as a Postdoctoral Research Associate. In 2004, he moved to the CIAC and was appointed as a Professor.

Prof. Chen’s current scientific interests are mainly focused on the separation, extraction and recycling of rare earth and other metal ions, including the preparation of new materials, the exploration of separation process mechanism and the development of novel clean separation technology. He has over 100 scientific journal articles and over 50 patents/patents applications. Some of his research results have been widely used in practice.

About the author

Tianchi Liu is currently a PhD candidate in Changchun Institute of Applied Chemistry, Chinese Academy of Sciences under the supervision of Prof. Ji Chen. She received a B.S. degree from Sichuan Agricultural University in 2017 and a M.S. degree from University of Science and Technology of China in 2019. Her current scientific interests are focused on batteries recovery and rare earths separation.

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Reference

Liu, T., Chen, J., Li, H., & Li, K. (2020). An integrated process for the separation and recovery of valuable metals from the spent LiNi0.5Co0.2Mn0.3O2 cathode materialsSeparation and Purification Technology, 245, 116869.

Go To Separation and Purification Technology

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