Organics removal combined with in situ thermal-reduction for enhancing the liberation and metallurgy efficiency of LiCoO2 derived from spent lithium-ion batteries

• Published in: Waste management (Elmsford) 2020-09, Vol.115, p.113-120
• Main Authors: Zhang, Guangwen, Yuan, Xue, He, Yaqun, Wang, Haifeng, Xie, Weining, Zhang, Tao
• Format: Article
• Language: English
• Subjects: Liberation; Pyrolysis; Recycling; Spent lithium-ion battery; Thermal-reduction
• ISSN: 0956-053X; 1879-2456
• DOI: 10.1016/j.wasman.2020.05.030

[Display omitted] •Thermal reduction of transition metal is synchronized with the liberation of electrode materials.•Organic binder and carbon black play a role of reductant in thermal-reduction process.•Water leaching combined with reductant-free acid leaching can be used to recover Li and transition metals. Liberation and reduction of cathode material are the necessary procedures for improving the recycling efficiency of cathode material derived from spent lithium-ion batteries. In this research work, a pyrolysis technology was utilized to remove the organic binder and enhance liberation of electrode materials. At the same time, pyrolysis treatment can facilitate the thermal-reduction of Co3+ in LiCoO2 to Co2+ with surface organics, which lays a foundation for the subsequent reductant-free acid leaching. Results indicate that the crystal structure of pure LiCoO2 is not changed at a pyrolysis temperature of 600 °C, but LiCoO2 transforms to CoO, Li2CO3, LiF, and Li2O under the reduction action of HF, pyrolytic carbon, and additive carbon black. Water-impact crushing is synchronized with water-leaching to separate electrode materials from aluminum foil and recover Li element. Afterwards, reductant-free acid leaching technology can be utilized to recycle Li and Co from spent LiCoO2 batteries. Recovery efficiency of Li element in water-leaching process was up to 92.17% while the remaining 7.83% of Li and all Co elements were recovered during reductant-free acid leaching process. Based on the foundation analysis, the green chemical process for recovering valuable metals from spent lithium-ion batteries was proposed.