Researchers at Michigan Technological University (MTU) have developed a method for separating lithium-ion cathode materials using a revised form of froth flotation.
The technique, used in the mining industry, separates materials in a flotation tank based on whether they repel water and float, or absorb water and sink.
Generally cathode materials sink— especially lithium nickel manganese cobalt oxide (NMC111) and lithium manganese oxide (LMO)— which makes them difficult to separate from each other.
However, the researchers found that separation could be achieved by making NMC111 cathode materials float via the introduction of a chemical that makes the material repel water.
Once the cathode materials were separated, the researchers found the process had a negligible impact on the electrochemical performance of the materials— with both showing purity levels of 95% or above.
MTU’s team are part of the battery recycling research and development center ReCell headquartered at the Department of Energy’s (DOE) Argonne National Laboratory
The research was published in the peer-reviewed scientific journal Energy Technology.
Previously a recycler had to take a mixture of lithium metal oxides — lithium cobalt oxide, lithium nickel manganese cobalt oxide, lithium nickel cobalt, aluminum oxide, lithium iron phosphate— and separate out each in order for them to be reused.
Jessica Durham, materials scientist at Argonne and co-author of the study, said: “Whatever method is used to do this recycling, the recycler has to be able to profit from it. We’re putting the steps together knowing that, in the end, the total process is going to have to be profitable.”
Additional study co-authors at Argonne include: Albert Lipson, principal materials scientist and Haruka Pinegar, postdoctoral researcher.
This research and the ReCell Center are funded by DOE’s Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office.