Environmentally friendly recipe for EV battery recycling

Researchers at Chalmers University of Technology, Sweden, have presented an efficient way to recycle metals from spent electric car batteries. The method reportedly allows recovery of 100% of the aluminium and 98% of the lithium in electric car batteries. The loss of valuable raw materials such as nickel, cobalt and manganese is also reduced, with no harmful chemicals required in the process because the researchers used 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 aluminium. Since all batteries contain aluminium, we need to be able to remove it without losing the other metals,” said Léa Rouquette, a PhD student from Chalmers University of Technology.

Rouquette and the research leader Martina Petranikova showed how the new method works by using spent car battery cells and, in the fume cupboard, their pulverised contents. This takes the form of a finely ground black powder dissolved in oxalic acid. The exact procedure is unique and requires the fine-tuning of temperature, concentration and time. The researchers also developed a new recipe for using oxalic acid, which can be found in plants such as rhubarb and spinach.

“We need alternatives to inorganic chemicals. One of the biggest bottlenecks in today’s processes is removing residual materials like aluminium. This is an innovative method that can offer the recycling industry new alternatives and help solve problems that hinder development,” Petranikova said.

The aqueous-based recycling method is called hydrometallurgy. Traditional hydrometallurgy involves the metals in an EV battery being dissolved in an inorganic acid. Then, the ‘impurities’ (such as aluminium and copper) are removed, before the valuable metals such as cobalt, nickel, manganese and lithium are separately recovered. While the amount of residual aluminium and copper is small, it requires several purification steps, with each step likely to cause lithium loss. With the new method, the researchers reversed the order and recovered the lithium and aluminium first, to 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 similar to 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. Rouquette said that the new method is a promising route for battery recycling that warrants further exploration. “Since the metals have very different properties, we don’t think it’ll be hard to separate them,” Rouquette said.

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