Efficient separation of the NCM cathode material and Al foil from spent lithium-ion batteries with oxalic acid under mild conditions

Abstract

In the recycling process of spent lithium-ion batteries (SLIBs), rapid and effective separation of the cathode material and current collector aluminium (Al) foil is a significant and difficult step. However, traditional separation methods have some drawbacks, including high energy consumption and cost and toxicity. In this study, we selected oxalic acid (OA), a green and low-cost simple organic acid, as the separating agent. Within 6 minutes of oxalic acid treatment, more than 99% of the nickel-manganese-cobalt (NCM) cathode materials are separated from the current collector Al foil. The mechanism analysis shows that the reaction of oxalic acid with the surface of the Al foil destroys the connection between the Al foil and the adhesive, while the oxalate protective layer formed on the surface of the NCM cathode material prevents further corrosion of the NCM cathode material, maintaining a good structural integrity. This green and efficient separation method provides an economical and viable solution for SLIB regeneration or upcycling.