Short-process regeneration and utilization of transition metal elements from spent ternary cathode materials after lithium extraction

Abstract

The number of retired lithium-ion batteries has been rapidly increasing every year due to the expansion of electric vehicles (EVs) and consumer electronics, posing serious environmental and lithium resource challenges. Green recycling of these batteries is essential for the sustainable development of the new energy industry. However, conventional hydrometallurgical recovery processes are often lengthy, involve complex separation of valuable metals, cause substantial resource wastage, and yield low lithium recovery rates. To address these issues, this study proposes a short-process regeneration method for producing ultra-high-purity transition metal elements. This process combines H₂O₂-assisted acid leaching with metal displacement and neutralization using cationic polyacrylamide (CPAM). The synergistic oxidation-acid leaching treatment enhances the dissolution of transition metals, achieving simultaneous recovery of Ni, Co, and Mn, with their leaching rates exceeding 99%. The introduction of an appropriate amount of iron powder into the leachate precipitates Cu²⁺. The residual solution undergoes pre-oxidation, alkaline neutralization, and flocculation, simultaneously precipitating Al³⁺ and Fe³⁺. This yields a regenerated transition metal solution, with Cu, Al, and Fe concentrations below 5 ppm. The LiNi_0.5Mn_0.3Co_0.2O₂ (R-NCM@880 °C) cathode material synthesized from this regenerated solution exhibits a specific discharge capacity of 153.1 mAh g⁻¹ at 1C rate and retains 96.1% of its capacity after 100 cycles, matching the performance of cathode materials derived from battery-grade sulfates. This recycling strategy offers significant advantages in environmental protection, energy savings, and economic viability, providing technical support and industrialization pathways for the green and efficient recycling of end-of-life ternary lithium-ion batteries.