Innovations in Li-ion Battery Recycling: Advanced Physical Separation, Characterization, and Industrial Process Integration

The exponential growth in the electric vehicle market and the rising demand for sustainable energy storage solutions have resulted in a significant increase in the production rates of lithium-ion batteries (LIBs). Consequently, the demand for critical raw materials needed for LIB manufacturing (e.g., Co, Ni, Cu, graphite, and Li) is projected to increase rapidly in the coming years.Current industrial-scale recycling technologies, namely pyrometallurgy and hydrometallurgy, face limitations in processing end-of-life LIBs and recovering valuables from their active component mixtures (a.k.a., black mass). To overcome these limitations, this Thesis investigated the potential of froth flotation as a separation process for direct recycling of LIBs, an approach aimed at preserving the structural and chemical integrity of the anode and cathode active minerals (CAMs).The research comprised multiple campaigns ranging from fundamental understanding of flotation mechanisms to the integration of flotation in industrial processes. Firstly, a novel tomographybased methodology was developed to characterize flotation froths, thus providing insights into the extraction mechanisms of solid particles. A previously overlooked phenomenon was uncovered, where binder-free lithium cobalt oxide (LCO) particles were observed to be hydrophobized by a common oily collector – indicating a lack of collector selectivity. Another campaign focused on flocculation of CAMs, specifically demonstrating the potential for selectively flocculating LCO particles in mixtures with graphite. Building on these insights, a combined approach of selective flocculation and froth flotation was studied, showing promise in improving the selectivity of graphite separation from black mass through a CAM-selective flocculation pretreatment .Lastly, the integration of LIB recycling into existing industrial slag cleaning processes was studied. It was demonstrated that, in the presence of binder polymers, flotation can effectively separate an industrial black mass into a froth concentrate rich in active minerals and an underflow concentrate comprising current collector metals. Furthermore, the refining of these concentrates was successfully integrated with industrial Ni slag cleaning and Cu slag cleaning processes, revealing synergistic benefits. The integrated processes were found to be chemically self-sustaining, requiring no additional reductants for refining valuable metals Cu, Co, Ni, and Fe, although loss of Li, Al, and Mn to the slag phase was observed. In summary, this thesis presents a comprehensive investigation into advanced characterization and physical separation techniques for LIB recycling, with perspectives on industrial process integration. The findings contribute to the development of more efficient, cost-effective, and environmentally sustainable recycling methods. The studied methods are expected to address existing concerns associated with the growing demand for critical battery materials.