Selective Recovery of Lithium from Spent Lithium-Ion Batteries by Coupling Advanced Oxidation Processes and Chemical Leaching Processes

Traditional technologies for the recycling of spent lithium-ion batteries (LIBs) mainly focus on reductive leaching, which often leads to total leaching rather than selective leaching of metals. As a result, loss of valuable metal ions, particularly Li+, occurs in subsequent extraction processes, causing low recycling efficiency of valuable metals. Inspired by the oxide-delithiation process in materials science, here, advanced oxidation processes (AOPs) are first introduced to selectively recover Li from spent LIBs during hydrometallurgical leaching (oxidative leaching), and a high Li recovery rate is achieved with an extremely high slurry density. In AOPs, the sulfate radical (SO4•–) and hydroxyl radical (HO•), which have high oxidation potentials, are in situ generated by heat-activated persulfate to prevent the leaching of Co2+ and Mn2+ and, simultaneously, promote the leaching of Li. Besides, chemical leaching processes are coupled with AOPs to enhance the leaching of Li for the incomplete delithiation of AOPs. Through the selective recovery, the extraction process of Li is drastically shortened. A lithium-rich solution (18.2 g/L of Li+), which is available to directly prepare qualified lithium products, can be obtained in only two steps. The reaction mechanisms between AOPs and spent LIBs are also comprehensively investigated. In the end, the loss of Li is only 2.06% in the purification processes, leading to a high recycling efficiency of Li. Li2CO3 with a purity of 99.0% was obtained. Furthermore, the introduction of AOPs for selective extraction of metals will not only show its significant value in the waste recycling field but also in the mineral resource utilization.