Exploring the critical role of grinding modification on the flotation recovery of electrode materials from spent lithium ion batteries

The growing demand for high-quality batteries has promoted frequent upgrading of Lithium-Ion Batteries (LIBs), resulting in a large number of spent LIBs entering into the waste stream. Grinding flotation may be a promising physical recycling method to help dispose of this waste. This study provides theoretical support for this technology by exploring the physical and chemical changes in the grinding modification process. To study physical grinding behavior, an interaction model between LiCoO2 and graphite particles was proposed; it shows that a mixed grinding process successively undergoes peeling of the graphite lamellar structure, abrasion of the LiCoO2 particles, and bending fracture of the graphite sheets. This process effectively avoids excessive pulverization of feed particles and guarantees a good flotation environment. As for surface hydrophobic changes, the contact angle difference significantly increased, from 5° to 53.34°, after mixed grinding. Further chemical composition analysis suggests that the active lithium element robs the F element from the C–F bond to form LiF, which reduces about 25% surfactant organic impurities and ultimately increases the hydrophobicity differential in the electrode materials. It is the synergistic effect of a good feeding environment and great hydrophobicity differential that contributes most to excellent flotation separation (LiCoO2 94.38%).