Coupling reactions and collapsing model in the roasting process of recycling metals from LiCoO2 batteries

The wider application of lithium ion batteries brings more production of spent ones to be recovered. There is a pyrometallurgical treatment by getting negative and positive materials burning together. The paper provides theoretical analysis and support for the feasibility of the treatment. Positive material graphite's burning and pyrolysis of negative material lithium cobalt oxide can make up as a coupling reaction, decreasing the decomposition temperature of lithium cobalt oxide from 1426 K to 1173 K. From the point view of crystal structure, the stronger attraction of graphite to oxygen than lithium and cobalt make oxygen octahedrons insides lithium cobalt oxide unstable to break down. We definite the phenomenon as the oxygen octahedrons collapsing model. Coupling reaction theory and crystal structure analysis indicate that graphite does promote the pyrolysis of lithium cobalt oxide. The study can guide industrial application to recover lithium ion batteries whose structure is similar to oxygen octahedrons at a comparatively low temperature.