Coupling Mechanochemistry with Advanced Oxidation and Chelation for Sustainable Recovery of Spent Ternary Lithium-Ion Batteries

The surge in spent lithium-ion batteries poses significant environmental risks, yet conventional recycling methods suffer from high energy consumption, equipment corrosion, and secondary pollution. Here, we develop a sustainable approach integrating mechanochemistry with advanced oxidation for recovering valuable metals from spent ternary lithium-ion batteries. Under optimized conditions, exceptional leaching efficiencies of 98.89%, 98.90%, 97.42%, and 98.99% were achieved for Li, Ni, Co, and Mn, respectively. The free radical capture experiments demonstrated that the mechanochemical process activates ammonium persulfate, generating hydroxyl and sulfate radicals, which was further confirmed through selective radical quenching experiments. The synergistic effect of these radicals induces the collapse of the layered structure of cathode material, as evidenced by X-ray diffraction analysis. X-ray photoelectron spectroscopy demonstrated that citric acid facilitates the reduction of high-valence metal ions to their soluble states while maintaining an acidic environment conducive to metal leaching. This innovative approach eliminates the conventional separate leaching step by employing a wet ball-milling process where citric acid simultaneously chelates and reduces metal ions, resulting in a significantly homogeneous precursor that directly enhances the final calcination product. The regenerated ternary cathode material exhibited excellent electrochemical performance with a discharge capacity of 125 mAh·g^–1 and 94.64% capacity retention after 100 cycles. Life cycle assessment indicated significantly reduced environmental impact compared to traditional hydrometallurgical processes. This study provides new insights into the mechanistic role of free radicals in solid-phase mechanochemical systems and establishes a sustainable strategy for battery recycling.