Efficient Upcycling of Spent LiNi_1/3Co_1/3Mn_1/3O₂ Cathode to Single-Crystal Ni-Rich Cathode Materials by Rapid Diffusion of Nickel Ions

With the rapid expansion of the lithium-ion battery (LIB) market, recycling LIBs has gained significant attention to alleviate pressures on the battery raw material supply chain and minimize the environmental impact of discarded LIBs. The direct recycling method, which restores a used failed cathode to its original performance without altering its structure, is considered highly effective. However, this approach merely repairs the cathode without upgrading it, resulting in potential obsolescence due to the swift advancement of cathode materials. In this study, we report for the first time an efficient upcycling process that leverages the rapid diffusion of nickel ions through the dissolution of NiO in molten Li2CO3, which successfully converts waste polycrystalline LiNi1/3Co1/3Mn1/3O2 (NCM111) into single-crystalline LiNi0.6Co0.2Mn0.2O2 (NCM622) in a relatively short reaction time. The upcycled NCM622 cathode material exhibits both high phase purity and homogeneous composition, delivering the capacity and stability comparable to those of commercial ones. This straightforward and efficient method offers new insight into upcycling the spent NCM and contributes to the advancement of effective recycling and reuse strategies.