Thermal simulation is effective to estimate safety of lithium-ion batteries.  For obtain reliable results by simulation, precise values are necessary for thermophysical properties such as specific heat capacity and thermal conductivity of the component materials of the batteries in wide temperature range.  For the active electrode materials, since the lithium content varies during charge and discharge, dependency on state of charge (SOC) should also be considered.  In this study, specific heat capacities and thermal conductivities of some positive electrode materials such as Li_xNi_0.85Co_0.05Al_0.10 (NCA), Li_xNi_1/3Mn_1/3Co_1/3O₂ (NMC) and so on are studied as functions of temperature and lithium content.  In addition, influence of electrode structure such as porosity is discussed for the thermal conductivity of the positive electrode.

The sample electrodes were prepared by coating the mixture of the active electrode material with carbon black and PVDF binder on both side of Al current collector of which thickness was 0.020 mm.  The porosity and the thickness of the electrode were controlled by pressing. 

The specific heat capacities of the samples were measured by the scanning method using differential scanning calorimeter.  The thermal diffusivities of the electrode sheet were measured by the distance-variation method with a fixed modulation frequency in the periodic heating technique which is adequate for film-like samples.  Then, the thermal conductivities were evaluated from the products of the specific heat capacities, the thermal diffusivities, and the bulk densities.

Additivity was confirmed for the specific heat capacity of the electrode sheet.  The sample containing more lithium showed larger specific heat capacity except for crystal phase transition region.  For the thermal conductivities, higher value was obtained from denser samples if the mixing ratio of active material, carbon black and PVDF was unity.