Researchers from Chalmers University of Technology have proposed a new and efficient way to recycle metals from electric vehicle batteries. This method recovers 100% aluminum and 98% lithium from used EV batteries. This minimizes losses of valuable raw materials such as nickel, cobalt and manganese. The process does not require expensive or harmful chemicals because the researchers used oxalic acid, an acid also found in the plant kingdom.
So far, no one has been able to find suitable conditions for separating this amount of lithium using oxalic acid and removing all the aluminum. Leah Rouquette, a PhD student in the Department of Chemistry and Chemical Engineering at Chalmers University of Technology, said that since all batteries contain aluminum, we should be able to remove it without losing other metals.
At the Battery Recycling Laboratory at Chalmers University of Technology, Leah Rouquette and research leader Martina Petranikova demonstrated how the new method works. The laboratory contained used car batteries, and in a fume hood there was crushed material in the form of a finely ground black powder dissolved in a clear liquid – oxalic acid. Leah Rouquette uses what looks like a kitchen blender to mix liquids and powders. Although it looks simple as if she is making coffee, the particular method is unique and a recently published scientific breakthrough. By fine-tuning temperature, concentration and time, the researchers developed a new recipe that uses oxalic acid, an environmentally friendly ingredient also found in plants such as rhubarb and spinach.
Alternatives to today’s inorganic chemicals are needed. Additionally, one of the biggest bottlenecks in modern processes is the removal of residual materials such as aluminum. Martina Petranikova, Associate Professor in the Department of Chemistry and Chemical Engineering at Chalmers University of Technology, said it was an innovative approach that could provide new alternatives to the recycling industry and help solve problems holding back development.
Liquid-based processing methods are called hydrometallurgy. In traditional hydrometallurgy, “impurities” from materials such as aluminum and copper are first removed, and then valuable metals such as lithium, cobalt, nickel and manganese can be used. Although only a small amount of aluminum and copper remains, several stages of purification are required, and each stage of the process results in a leak. In the new method, the researchers changed the cut and first separated the lithium from the aluminum. In this way, they can reduce the waste of precious metals needed to make new batteries.
Even the second half of the process—filtering the dark mixture—is reminiscent of brewing coffee. While aluminum and lithium enter the liquid, other metals remain in the “sump.” The next step in this process is to separate the aluminum and lithium.
“Because these metals have very different properties, we believe that separating them will not be difficult. Our new method opens up a promising new avenue for battery recycling that we have every incentive to explore further,” says Leah Rouquette. “Since the method can also be used on a large scale, we hope that it will be useful in industry in the coming years,” says Martina Petranikova.
Martina Petranikova’s research group has been conducting leading research into metal recycling in lithium-ion batteries for many years. The group collaborates with companies involved in the recycling of electric vehicle batteries and is a partner in major R&D projects such as Volvo Cars and Northvolt’s Nybat project.
Additional information about the research: The scientific article “Fully selective recovery of lithium from lithium-ion electric vehicle batteries: modeling and optimization using oxalic acid as a lixiviant” was published in the journal Separation and Purification Technology. The study was carried out by Leah Rouquette, Martina Petranikova and Natalia Vieceli from the Department of Chemistry and Chemical Engineering at Chalmers University of Technology. The research was funded by the Swedish Energy Agency, the Swedish Battery Base and Vinnova, and the experiments were carried out using used Volvo Cars electric vehicle batteries processed by Stena Recycling and Akkuser Oy.
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