Towards Sustainable Direct Recycling: Unraveling Structural Degradation Induced by Thermal Pretreatment of Lithium-Ion Battery Electrodes.

As the demand for lithium-ion batteries (LIBs) continues to increase, there is a growing focus on recycling these battery wastes. Among the existing recycling methods, direct recycling is considered a promising approach, because it allows waste to be returned directly to production. One crucial step in this process is the pretreatment, which involves separating the active materials from the current collector. Thermal treatment provides a feasible and effective approach for achieving this separation. Nonetheless, concerns persist regarding the potential impacts of this process on the structure. This study aims to examine the effects of thermal treatment on the separation efficiency and crystal structure of fresh and cycled NMC (LiNiCoMnO) cathodes and graphitic anodes, under various atmospheres and temperatures. The results reveal that an air/oxygen atmosphere facilitates complete separation of cathode materials from aluminum with minimal structural degradation and at lower temperatures compared to other atmospheres. For graphite, thermal treatment under argon, nitrogen and hydrogen demonstrates good structural stability. However, for cycled anodes, the desired separation is not achieved due to the possible interface adhesion that occurs during cycling and heating. Additionally, compared to fresh materials, cycled materials experience more pronounced structural degradation during thermal treatment.