Atomic Economy Approach: Mutual Redox of Spent LiFePO4 and LiNi0.5Co0.2Mn0.3O2 in H2SO4 System

Abstract

With the swift advancement of the new-energy vehicle industry, the significant quantity of decommissioned lithium-ion batteries (LIBs) is increasing. Given the underlying environmental damages and significance of key metal supplies, the efficient recycling of spent lithium-ion batteries has attracted widespread concern. Traditional studies on recycling mainly focus on single LiMO₂ (NCM, M = Ni, Co, Mn) or LiFePO₄ (LFP) cathode materials, which often cause a lot of waste of reagents (reductant or oxidation), time, and energy. Herein, a method based on the energy-saving and emission-reduction treatment principle of "treating waste with waste" is introduced to leach mixed spent cathode materials of LiFePO₄ and LiNi_0.5Co_0.2Mn_0.3O₂ in sulfuric acid solution. LFP and NCM are used as redox couples. The former acts as a reducing agent when leaching LiNi_0.5Co_0.2Mn_0.3O₂ without an additional redox reagent. Finally, the leaching rates for Li, Co, Ni, and Mn are > 97%. By integrating the principles of green chemistry, especially the atom economy, this study proves that it is feasible to treat miscellaneous (NCM and LFP) discarded cathode materials in H₂SO₄ system, which may contribute to the sustainable development of the new-energy automotive industry.