Thermal stability and kinetics of delithiated LiCoO2

The thermal stability of the materials that comprise the battery has been one of the important issues. By using temperature programmed desorption-mass spectrometry (TPD-MS) and XRD, the thermal decomposition reaction of delithiated LixCoO2 (x = 1, 0.81, 0.65) was quantitatively analyzed. Delithiated LixCoO2 samples were metastable and liberated oxygen at a temperature of above 250 °C. Liberated oxygen gas was quantified by TPD-MS. Structural changes of the samples were confirmed by XRD. We identified the stoichiometry of the thermal decomposition reaction of LixCoO2. Furthermore, to analyze the heating rate dependence of the oxygen generation, we calculated the activation energy (Ea) of the thermal decomposition reaction. The average Ea through the reaction of Li0.81CoO2 is 130 kJ mol−1, and that of Li0.65CoO2 is 97 kJ mol−1. The Li content decreased as the activation energy increased.