The Fischer‐lactonization‐driven mechanism for ultra‐efficient recycling of spent lithium‐ion batteries

Hydrometallurgy remains a major challenge to simplify its complex separation and precipitation processes for spent lithium-ion batteries (LIBs). Herein, we propose a Fischer-lactonization-driven mechanism for the cascade reaction of leaching and chelation of spent LIBs. Citric acid undergoes a two-step dissociation of the carboxylic acid (-COOH) and complexes with the leached metal ion, while the residual -COOH is attacked by H protons to form a protonated carboxyl ion (-COO -). Subsequently, the lone pair of electrons in the hydroxyl of the same molecule attack the carbon atom in -COO - to facilitate ester bonding, leading to the formation of a lactonized gel. The leaching rates of Li, Ni, Co and Mn are 99.3, 99.1, 99.5 and 99.2 %, respectively. The regenerated monocrystalline LiNi