Researchers at Chalmers University of Technology in Sweden have presented a new and efficient way to recycle metals from spent electric vehicle (EV) batteries. The method allows recovery of 100% of the aluminum and 98% of the lithium in EV batteries.
Image: Chalmers University of Technology
What’s more: the loss of valuable raw materials such as nickel, cobalt, and manganese is minimized, and zero costly or harmful chemicals are required in the process because the researchers use oxalic acid — an organic acid that can be found in the plant kingdom.
“So far, no one has managed to find exactly the right conditions for separating this much lithium using oxalic acid, whilst also removing all the aluminum,” said Léa Rouquette, PhD student at Chalmers. “Since all batteries contain aluminum, we need to be able to remove it without losing the other metals.”
In the University laboratory, the pulverized contents of used EV battery cells — which take the form of a finely ground black powder — are dissolved in the acid. By fine-tuning the temperature, concentrations and time taken, the researchers say their new process has provided “remarkable” results.
The aqueous-based recycling method is called hydrometallurgy. In conventional hydrometallurgy, all the metals in an EV battery cell are dissolved in an inorganic acid. Next, the “impurities” such as aluminum and copper are removed. Lastly, it’s possible to separately recover valuable metals such as cobalt, nickel, manganese, and lithium.
Even though the amount of residual aluminum and copper is small, it requires several purification steps and each step in this process can cause lithium loss. With the new method, the researchers reverse the order and recover the lithium and aluminum first. Therefore, they can reduce the waste of valuable metals needed to make new batteries.
The latter part of the process, in which the black mixture is filtered, is also reminiscent of brewing coffee. While aluminium and lithium end up in the liquid, the other metals are left in the “solids.” The next step in the process is to separate aluminium and lithium.
“Since the metals have very different properties, we don’t think it’ll be hard to separate them. Our method is a promising new route for battery recycling — a route that definitely warrants further exploration,” says Rouquette.
“As the method can be scaled up, we hope it can be used in industry in future years,” added Martina Petranikova, Associate Professor at the Department of Chemistry and Chemical Engineering at Chalmers.
Petranikova’s research group has spent many years conducting cutting-edge research in the recycling of metals found in lithium-ion batteries. The group is involved in various collaborations with companies to develop electric car battery recycling and is a partner in major research and development projects, such as Volvo Cars’ and Northvolt’s Nybat project.
Read the full article from Chalmers University of Technology here.
More about the research:
The scientific article, Complete and selective recovery of lithium from EV lithium-ion batteries: Modeling and optimization using oxalic acid as a leaching agent was published in the journal Separation and Purification Technology. The study was conducted by Léa Rouquette, Martina Petranikova and Nathália Vieceli at the Department of Chemistry and Chemical Engineering at Chalmers University of Technology, Sweden.
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