Recovery and regeneration of LiCoO2-based spent lithium-ion batteries by a carbothermic reduction vacuum pyrolysis approach: Controlling the recovery of CoO or Co

Abstract

An environmentally benign vacuum pyrolysis (VP) approach is employed to recover Li and Co from spent LiCoO₂-based lithium-ion batteries (LIBs). First, the electroactive materials were separated from the current collector by the VP method from 623 to 823 K with an attempt to choose an appropriate temperature. Then, the as-received cathode materials were mixed with different amounts of graphite from the anode to selectively convert LiCoO₂ to Co or CoO and Li₂CO₃ by carbothermic reduction under vacuum and at 873 to 1273 K. After carbothermic reduction, the pyrolyzed powder was leached in water to separate Li₂CO₃ from Co/CoO. By alternating the C/LiCoO₂ mass ratio and the pyrolysis temperature, a recovery rate reaches over 93% for Li and 99% for Co. Finally, the recovered CoO and Li₂CO₃ were used to regenerated LiCoO₂ that delivered a specific capacity of 145 mAh g^-1 at 1C and retaining 93% of the initial capacity after 100 cycles. Overall, a multi-vacuum-pyrolysis approach offers a closed-loop route for the management of spent LIBs without using any hazardous chemicals.

Keywords: LiCoO(2); Recovery; Regeneration; Spent lithium-ion batteries; Vacuum pyrolysis.