Achieving High Solid–Liquid Ratio through Competitive Coordination towards Efficient Recovery of Metals from Spent Batteries

The recycling of critical metals from spent lithium‐ion batteries represents a significant step towards meeting the enhancing resource requirements in the new energy industry. Nevertheless, achieving effective leaching of metals from the stable metal‐oxygen (MO6) structure of spent ternary cathodes and separation of metal products simultaneously still remained a huge challenge towards industrial applications. Herein, a competitive coordination strategy was proposed to design a novel deep eutectic solvent (DESs), which improved both leaching and selective metal recycling capacity even at high solid‐liquid ratio (1:10). The results demonstrated that the number of hydrogen bonds in designed ternary DESs was 16.5% higher compared to those in the binary DESs, resulting in efficient reaction kinetics to break the metals‐oxygen bond. More importantly, the competing‐ligand (p‐toluenesulfonic acid) could preferentially enter into the first nanostructure sheath and reduce the proportion of solvated oxalic acid (OxA) from 28.36% to 17.76% within the nanostructure, which enable OxA molecules to enhance the coordination interaction with metal for precipitating NiC2O4·2H2O product (~ 95.7% purity) from spent cathodes. This work achieved impressive profitability ($16.05 per kg feedstock) and effectively reduction of GHG emissions during the recycling process, making it applicable to critical sustainability initiatives.