Thermophysical properties of LiFePO4 cathodes with carbonized pitch coatings and organic binders: Experiments and first-principles modeling

Abstract

We report heat capacity, thermogravimetry and thermal diffusivity data for carbonized mesophase pitch coated LiFePO4 (LFP) cathodes. The results are compared with the thermophysical properties of a conventional LFP-based electrode having a poly (vinylene) difluoride (PVDF) binder and conductive carbon diluents. The measured heat capacity of LFP as a function of temperature is in good agreement with model calculations based on first-principles methods. Thermal diffusivity data indicate that the mesophase pitch coated LFP compositions have a factor of two higher thermal diffusivity than the conventional electrode composition, suggesting that the coatings improve heat transfer. In the presence of an electrolyte mixture (1.2 M lithium hexa-fluorophosphate), differential scanning calorimetry (DSC) analysis of the LFP–pitch composite and LFP–PVDF–carbon composites showed similar onset temperature and heat evolution.