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

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 first generation 1 (Gen 1) 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. The remaining nickel-rich layered oxide can be directly regenerated through a hydrothermal hydroxide process, which also decomposes the PVDF binder, thereby avoiding fluorine contamination of the recovered layered oxide. We report electrochemical data for the regenerated layered oxide phase while also showing that the leachate can be upcycled to next generation materials. Furthermore, while literature recycling studies are commonly performed on model systems, we illustrate here the approach on a real end of life EV battery. This study therefore illustrates a process to recycle blended cathodes containing LiMn2O4 spinel and layered Ni-rich oxide phases efficiently, with the potential to be extended to other mixed electrode waste streams. The method has great potential not only for recycling EV battery waste, but also other Li/Na ion battery waste, such as mobile phone batteries, where batteries with different cell chemistries are often be mixed.