Phase-selective recovery and regeneration of end-of-life electric vehicle blended cathodes via selective leaching and direct recycling

Abstract

Large-scale recycling and regeneration of lithium-ion cathode materials is hindered by the complex mixture of chemistries often present in the waste stream. We outline an efficient process for the separation and regeneration of phases within a blended cathode. We demonstrate the efficacy of this approach using cathode material from a Nissan Leaf end-of-life (40,000 miles) cell. Exploiting the different stabilities of transition metals in acidic media, we demonstrate that ascorbic acid selectively leaches low-value spinel electrode material (LiMn2O4) from mixed cathode electrode (LiMn2O4/layered Ni-rich oxide) in minutes, allowing both phases to be effectively recovered separately. This process facilitates upcycling of the Li/Mn content from the resultant leachate solution into higher-value LiNixMnyCozO2 (NMC) phases, whereas the remaining nickel-rich layered oxide can then be directly regenerated. The method has been extended to other mixtures, with preliminary results illustrating the successful selective leaching of a sodium-ion cathode from a mixture with NMC811.