Unveiling the Role and Mechanism of Mechanochemical Activation on Lithium Cobalt Oxide Powders from Spent Lithium-Ion Batteries

This research presented the impacts of mechanochemical activation (MCA) on the physiochemical properties of lithium cobalt oxide (LiCoO₂) powders of cathode materials from spent lithium-ion batteries, and analyzed the relevant effects of these changes on the leaching efficiency of lithium and cobalt and the leaching kinetics of LiCoO₂ powders. The results revealed the superiority of MCA in the following levels of changes in the LiCoO₂ powders: first, the physical properties included a decrease in the average particle size, an increase in the specific surface area, and the appearance of a mesoporous structure change; second, changes in crystal-phase structures were reflected in the grain refinement of LiCoO₂ powders, lattice distortions, lattice dislocations, and storage and increment of internal energy; third, the surface characteristics included a chemical shift of lithium element electrons, a reduction in Co³⁺ concentration, and an increment in the surface hydroxyl oxygen concentration. These changes in physiochemical properties and structures enhanced the hydrophilicity and interface reactivity of the activated LiCoO₂ powders and significantly improved the leaching efficiencies of Li and Co in organic acid solutions. The rate-limiting step of metal leaching was also altered from a surface chemical reaction-controlled one before MCA to an ash layer diffusion-controlled one after MCA.