The synthetic mechanism of LiCoO₂ from CoO and Li₂CO₃ under electric field

Flash synthesis (FSyn) represents an innovative and energy-efficient approach for ceramic preparation. However, the limited understanding of the phase evolution mechanisms makes it challenging to optimize the synthesis parameters, hindering application development. Here, the FSyn of LiCoO₂ cathodes using CoO as the cobalt source is investigated, providing important insights into the mechanisms of phase evolution and the role of environmental factors. In situ thermal monitoring and phase analysis revealed that the thermodynamic regulation of sample temperature was crucial for the formation of intermediates, such as Li_xCo_1−xO. Concurrently, the exchange of oxygen with the surrounding environment controls the oxidation reaction processes and impacts the synthesis rate. In addition, the oxygen vacancies enhance the reaction kinetics by accelerating mass transfer. On the basis of these findings, three effective strategies have been developed to produce pure LiCoO₂: (1) reducing the current density to lower the sample temperature and limit intermediate formation, (2) increasing the oxygen partial pressure to accelerate CoO oxidation and facilitate intermediate transformation, and (3) extending the holding time to ensure reaction completion. This work not only clarifies the FSyn mechanism of LiCoO₂ but also offers a practical reference for optimizing the synthesis of other advanced ceramics.