Novel approach to recycling of valuable metals from spent lithium-ion batteries using hydrometallurgy, focused on preferential extraction of lithium

Traditional recycling technology for spent lithium-ion batteries faces the issue of low Li recovery due to the considerable Li loss during leaching and further purification operations. To improve the Li recovery, high-pressure acid leaching using H₂SO₄ for Li preferential liberation and the subsequent purification were systematically investigated. Experimental results showed that 97.6% of Li was preferentially leached with about 2% of Ni, Co, and Mn co-leached, and a leaching solution with a Li⁺ concentration of 21.46 g/L was obtained. Further characterization indicated that most of Li was first liberated and exchanged by the proton (H⁺), then the high reaction temperature induced the hydrolysis of the co-leached Ni²⁺, Co²⁺, and Mn²⁺ and generated extra H⁺ prompted a deeper liberation of Li from the undissolved NCM structures. Additionally, the high-purity Li₂CO₃ was achieved via a synergistic extraction by D2EHPA and 4PC for the deep removal and recovery of co-leached Ni/Co/Mn followed by carbonation. Compared with the traditional end-Li-recovery method, the proposed method possesses the advantages of a short Li extraction process, high recovery, and low cost. Moreover, the preferential leaching of Li provided an opportunity for a novel hydrometallurgical process to recover spent lithium-ion batteries that consists of Li preliminary leaching, Ni–Co–Mn material leaching, precipitation of Fe/Al, and selective extraction of F, Ni, Co, and Mn was not separated that shorten the flowsheet in this process, dramatically reduced reagent consumption and wastewater generation.