Direct and green repairing of degraded LiCoO 2 for reuse in lithium-ion batteries.

Traditional recycling processes of LiCoO 2 rely on destructive decomposition, requiring high-temperature roasting or acid leaching to extract valuable Li and Co, which have significant environmental and economic concerns. Herein, a direct repairing method for degraded LiCoO 2 using a LiCl-CH 4 N 2 O deep eutectic solvent (DES) was established. The DES is not used to dissolve LiCoO 2 but directly serves as a carrier for the selective replenishment of lithium and cobalt. Replenishment of lithium restores LiCoO 2 at different states of charge to a capacity of 130 mAh/g (at 0.1 C rate), while replenishing the cobalt increases the capacity retention rate of 90% after 100 cycles, which is comparable to pristine LiCoO 2 . The DES is collected and reused multiple times with a high repair efficiency. This process reduces energy consumption by 37.1% and greenhouse gas emissions by 34.8% compared with the current production process of LiCoO 2 , demonstrating excellent environmental and economic viability.