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

Abstract

In the recycling process of spent lithium-ion batteries (SLIBs), rapid and effective separation of 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, expensive and toxicity. In this study, we select oxalic acid (OA), a green and low-cost simple organic acid, as the separating agent. Within 10 minutes oxalic acid treatment, above 99% of the nickel-manganese-cobalt (NCM) cathode materials are separated from current collector Al foil. The mechanism analysis shows that the reaction of oxalic acid with the surface of Al foil can destroy the connection between Al foil and adhesive, while the oxalate protective layer formed on the surface of NCM cathode material prevent further corrosion of 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.