Three-in-One Self-Sacrifice Mechanism Driving Green and Universal Critical Metals Leaching from Spent Lithium-Ion Batteries

Developing green and efficient methods for critical metal recycling from spent lithium-ion batteries (LIBs) is crucial for a circular economy and a sustainable society. Traditional pyrometallurgy or hydrometallurgy techniques featuring high energy or hazardous chemical consumption hinder green and circular technology progress. Herein, an eco-friendly and commercially available green chemical reagent, peracetic acid (PAA), has been explored to leach the critical metals from the spent-battery cathodes, which shows high-efficiency leaching rates up to 99.69%, 99.15%, 99.88%, and 99.98% for Ni, Co, Mn, and Li, respectively, from a LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) cathode. A comprehensive mechanistic study revealed that a three-in-one synergistic self-sacrifice mechanism had been involved during the leaching process, as the PAA can simultaneously contribute the proton attacking, complexation, and oxidation-reduction driven forces to aid the self-sacrifice and critical element leaching for NCM622. This method's effectiveness was also validated across a range of spent LIB cathodes. Simultaneously, 52.64% acetic acid (HAc) could be recovered via the evaporation-condensation reflux approach, suggesting a closed-loop feature of this method that minimizes wastewater generation. This innovative approach integrated three different chemical driving forces in one chemical reagent for efficient critical metal recovery from diverse spent LIBs, paving the way for a green, low-carbon circular economy.