Stepwise mechanochemical ball milling induced lattice destruction‑oxygen vacancy regulation promotes large-scale lithium leaching from spent lithium-ion battery cathodes

The recovery of valuable metals from spent lithium-ion battery (LIB) cathode powders via mechanical ball milling has gained widespread attention. However, the presence of leaching agents in one-step recycling significantly hinders the efficient leaching and large-scale processing of valuable metal ions from these cathode powders. Herein, we develop a scalable and environmentally friendly recycling process through stepwise dry-ball milling (D-BM) activation and wet-ball milling (W-BM) leaching to selective extract lithium (Li) from spent Li(Ni 0.5 Co 0.2 Mn 0.3 )O 2 cathode powders (SNCM) using oxalic acid (OA) and ascorbic acid (AC) as the agents. The result show that, even under a high solid-liquid (S/L) ratio condition (50 g L −1 ), the Li leaching efficiency reached near-complete extraction (96.92 %) and a high selectivity of 95.72 % within just 10 min. These can be attributed to the D-BM activated the SNCM via disrupting of lattice of the structure and introducing oxygen defects, while the W-BM offer the internal energy to the reactants and enhance the mixture of the leaching process. Furthermore, the residue delivers outstanding activity after 400 °C treatment, requiring only 264 mV overpotential at 10 mA cm −2 and exhibiting a low Tafel slope (77.96 mV dec −1 ). This study proposes a rapid, scalable, and comprehensive recycling strategy for spent LIB cathode powders, with a specific focus on the sustainable recovery of cathode materials, offering critical guidance for industrial applications.