A closed-loop process for recycling LiNi1/3Co1/3Mn1/3O2 from the cathode scraps of lithium-ion batteries: Process optimization and kinetics analysis

A closed-loop process for recycling LiNi1/3Co1/3Mn1/3O2 from the cathode scraps for lithium-ion batteries (LIBs) is preliminarily established in this research. Biodegradable trichloroacetic acid (TCA) with hydrogen peroxide (H2O2) is innovatively developed to dissolve LiNi1/3Co1/3Mn1/3O2 from the cathode scraps. Operational parameters are optimized to obtain a lower Al dissolution rate, but not at the expense of sacrificing other metals. Under the optimal leaching condition of 3.0 M TCA, 4 vol.% H2O2, a solid to liquid (S/L) ratio of 50 g/L at 60 °C for 30 min, the leaching rates of Ni, Co, Mn and Li are 93.0%, 91.8%, 89.8% and 99.7%, respectively. In this optimum condition, only 7.0% of Al is leached, and this could be further controlled according to the subsequent utilization of the leachate. Avrami equation is introduced to describe the leaching kinetics of LiNi1/3Co1/3Mn1/3O2 from the cathode scraps. The apparent activation energies for leaching of Ni, Co, Mn and Li are determined as 44.51, 44.79, 43.81 and 28.00 kJ/mol, respectively, indicating that the surface chemical reaction is the rate-controlling step during this leaching process.