This review highlights the importance of recovering valuable metals from spent Li-ion battery (LIB) cathodes through the resynthesis of cathode active materials (CAMs). The resynthesis process of CAMs, a promising recycling method that directly produces CAM precursors from LIB leachate, is explored. This process encompasses six key steps, including pretreatment, leaching, purification, adjustment of metal concentrations, precursor synthesis, and sintering. The review also investigates the potential introduction of impurity elements during CAM resynthesis and provides tolerance levels for these impurities based on thorough reference analysis. Additionally, it addresses challenges related to the commercialization of the resynthesis process. Notably, this review represents the first comprehensive assessment of CAM resynthesis, including the systematic evaluation of 12 impurity elements (Fe, Li, Al, Cu, C, P, F, Na, Cl, S, Mg, and Zn). Overall, this comprehensive review is poised to support the commercial development of resynthesized CAMs by offering valuable guidelines for managing impurities and streamlining the purification process. (c) 2024 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.