Researchers in Sweden recycling electric vehicle (EV) batteries are claiming recovery rates of 98% for lithium and 100% by reversing the conventional hydrometallurgical process for separating the valuable material.
In hydrometallurgy, battery metals are usually dissolved in inorganic acids and less valuable metals such as aluminium and copper are removed before lithium, cobalt, manganese and nickel are extracted. This can require several purification steps resulting in lithium loss.
However, the team at Chalmers University of Technology, Sweden is using oxalyic acid – an organic acid found in the plant kingdom. The researchers say the new latter stage, in which the black mass is filtered, is 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 the aluminium and lithium.
‘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,’ says PhD student Léa Rouquette. ‘Since all batteries contain aluminium, we need to be able to remove it without losing the other metals.’
‘We need alternatives to inorganic chemicals,’ says Martina Petranikova, team at the Department of Chemistry and Chemical Engineering ‘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’s research 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.