Comparative Study of the Thermal Stability of Electrode Materials for Li-Ion and Na-Ion Batteries

The thermal stability of the cathode and anode materials for Li-ion and Na-ion batteries─LiNi1/3Mn1/3Co1/3O2, LiFePO4, Li4Ti5O12, graphite, O3-NaNi1/3Fe1/3Mn1/3O2 (NFM), Na3V2(PO4)3 (NVP), β-NaVP2O7 (NVPO), Na3V2(PO4)2F3 (NVPF), and hard carbon─was studied by means of differential scanning calorimetry of the electrodes in the charged state and ex situ powder X-ray diffraction. The obtained results indicate that the thermal stability of the Na-ion cathode materials increases in the order NFM < NVPF < NVP < NVPO. The "heat on energy" term has been proposed and analyzed for all of the studied materials.