Direct recovery of degraded LiCoO_2 cathode material from spent lithium-ion batteries: Efficient impurity removal toward practical applications

摘要

Regenerating cathode material from spent lithium-ion batteries (LIBs) permits an effective approach to resolve resource shortage and environmental pollution in the increasing battery industry. Directly renovating the spent cathode materials is a promising way, but it is still challenging to efficiently remove all of the complex impurities (such as binder, carbon black, graphite and current collectors) without destroying the material structure in the electrode. Herein, a facile strategy to directly remove these impurities and simultaneously repair the degraded LiCoO_2 by a target healing method is reported. Specifically, by using an optimized molten salt system of LiOH-KOH (molar ratio of 3:7) where LiNO_3 and O_2 both serve as oxi-dants, the impurities can be completely removed, while the structure, composition and morphology of degraded LiCoO_2 can be successfully repaired to commercial level based on a two-stage heating process (300 °C for 8 h and 500 °C for 16 h, respectively), resulting in a high recovery rate of approximately 100% for cathode material. More importantly, the regenerated LiCoO_2 exhibits a high reversible capacity, good cycling stability and excellent rate capability, which are comparable with commercial LiCoO_2. This work demonstrates an efficient approach to recycle and reuse advanced energy materials.