Thermal Stability of NCM622 Cathode Material for Li-ion Batteries: A Real-time Synchrotron X-ray Scattering Study

Abstract We have studied the thermal stability of NCM622 oxide cathode material for Li-ion batteries using a real-time synchrotron x-ray scattering in air and in vacuum. The amount of crystal NCM622 phase in air and in vacuum showed almost constant values below 600°C. This indicates that the NCM622 cathode material with layered structure was thermally stable in air and in vacuum. Considering the amount of crystal phase and the change of crystal domain sizes, the NCM622 cathode material in air was more thermally stable than that in vacuum. These are due to the presence of 21% oxygen in the air, which is not in the vacuum. Our study revealed the detailed thermal stability of NCM622 cathode material during real-time annealing below 600°C in air and in vacuum.