ABSTRACT We compare solid‐state relithiation (SSR), hydrothermal relithiation (Hydro), molten salt thermochemistry (MST), electrochemical (EC), and chemical (Chem) methods using harmonized techno‐economic (Group I), electrochemical (Group II), and environmental/toxicological (Group III) metrics. SSR/Hydro occupies a leading position in Group I. EC combines low energy (143. 0 kJ·g −1) with higher material cost (147. 7·kg −1) at the laboratory scale, yielding 71. 9 pts, while Chem remains competitive (77. 8 pts) despite elevated 201. 4·kg −1 and moderate energy consumption of 333. 7 kJ·g −1. In Group II, MST and SSR lead (64. 0 and 61. 1 pts), followed by Chem, Hydro, and EC. In Group II, Chem/MST shows the best rate capability recovery, EC—cycling stability recovery, MST—capacity recovery. Group III follows the energy consumption track. The CO 2 emission declines as follows: EC < Chem < MST < Hydro < SSR, with method toxicity near moderate hazard for SSR/MST/Hydro/EC and highly reactive / highly toxic for Chem. Integrated performance for Groups I–III is close for methods with energy control in the range of 60–65 points (SSR, Hydro, MST, EC), while Chem leads (72. 3 points). For Ni‐rich cathodes, transferable methods should include a brief high‐temperature step. EC/Chem can only be used for mild regeneration.
Beletskii et al. (Mon,) studied this question.