Green and Efficient Regeneration of Spent Lithium Batteries through Directional Leaching of Valuable Metals and Gradient Impurity Separation

Abstract

The recycling of spent lithium-ion batteries faces challenges of low metal leaching efficiency and complex impurity separation. To address these issues, this study developed a closed-loop recycling process integrating quality pretreatment, directional leaching, gradient impurity separation, and short-process regeneration. Key innovations include: CO₂-assisted carbothermal reduction (900 °C) combined with water leaching for selective lithium extraction (recovery 88.53%); alkaline leaching (14% NaOH) for aluminum removal (86.32%); reductive acid leaching (3.5 mol L⁻¹ H2SO4 + H2O2) achieving Ni/Co/Mn leaching rates of 98.54%, 97.37%, and 98.00%, respectively; and gradient solvent extraction using M5640 and P204 for deep impurity removal (>99%). The final high-purity Ni–Co–Mn solution was successfully used to synthesize LiNi0.8Co0.1Mn0.1O2 precursors. Compared to conventional hydrometallurgical routes, this integrated strategy reduces acid/alkali consumption by ~40%, shortens unit operations from seven to four, and achieves a total metal recovery rate of 95.2%. This work provides a low-carbon, short-process, and high-value recycling pathway for hybrid spent lithium-ion battery resources, contributing to the green circulation and carbon neutrality goals of the new energy industry.