Converting spent lithium cobalt oxide battery cathode materials into high-value products via a mechanochemical...

This study innovatively combines mechanochemistry and high-temperature thermal reduction to achieve the recovery of valuable metals from spent LIBs. First, under the action of mechanical force, the crystal structure of lithium cobalt oxide (LiCoO₂) found in the cathode materials of spent LIBs was destroyed and converted into lithium carbonate (Li₂CO₃) and Li-free residue (C/Co₃O₄) using dry ice as a co-grinding reagent. The optimum Li₂CO₃ recovery conditions were determined to be as follows: a ratio of dry ice: LiCoO₂ powder mass of 20:1; a rotation speed of 700 rpm, and a reaction time of 1.5 h. With these conditions the maximum percentage of Li₂CO₃ recovered was 95.04 wt%. The Co₃O₄ in Li-free residue was reduced to a high-value Co⁰ product via a high-temperature (800 °C) heat treatment. Gibbs free energy analysis confirmed that the carbon in the Li-free residue could be used as a self-reducing reagent for the thermal reduction of Co₃O₄. The reactants and products of each step were characterized by XRD, FT-IR, XPS and SEM techniques. The green route for recycling spent LIBs that this study proposes realizes the green and cost-effective conversion of LiCoO₂ to high-value products, which may become an outstanding example of recycling spent LIBs.