Fast and highly selective lithium leaching and regeneration of spent ternary cathode materials

Abstract

In this paper, a novel method for the rapid and highly selective leaching of lithium (Li) from LiNi_1/3Co_1/3Mn_1/3O₂ (NCM333) material using an oxalic acid solution is presented. The effects of the lithium leaching rate were investigated both before and after 1000 cycles of operation in power batteries utilizing this material. Additionally, the mechanism underlying the rapid selective leaching of lithium by oxalic acid from spent NCM333 was elucidated. Following the leaching process, the residual valuable metals (Ni, Co, and Mn) were regenerated through high-temperature calcination to yield NCM333. Subsequently, the electrochemical performance of the regenerated material was evaluated. At a temperature of 95 °C, lithium (Li) was rapidly and selectively leached from the cathode material using a 1 mol/L oxalic acid solution, achieving a leaching efficiency of 99.8% within 15 min. Concurrently, approximately 97% of nickel (Ni), 97% of cobalt (Co), and 83% of manganese (Mn) were converted into oxalate precipitates. After mixing the oxalate precipitate with a certain amount of Li₂CO₃ in proportion, the NCM333 cathode material is directly regenerated by high temperature calcination and exhibits excellent electrochemical performance. The highest initial discharge specific capacity reached 131.3 mAh g⁻¹ at a current density of 150 mA g⁻¹ (1 C). After 100 cycles, the initial discharge-specific capacity was recorded at 126.1 mAh g⁻¹, corresponding to a specific capacity retention rate of 96.48%. This method offers a straightforward approach and new insights for the recovery and regeneration of spent lithium-ion battery cathode materials.

Graphical Abstract