To precisely understand the heat generation of Li-ion batteries during charging and discharging, it is important to have the best possible understanding of the various electrochemical and thermal processes in a battery. The classic way to examine the behavior of a battery under certain conditions has been to carry out various mechanical, electrical, or thermal tests. However, since this approach is often very time-consuming and cost-intensive, mathematical models are increasingly being used to simulate batteries to gain a deeper insight into the battery behavior.

In this work, a two-dimensional electrochemical-thermal model has been developed for a self-made lithium iron phosphate (LiFePO₄) coin cell battery using the COMSOL Multiphysics 6.0 software environment. In order to improve the accuracy of the battery model, self-measured experimental material data of the electrode sheets in the coin cell are implemented into the simulation. Therefore, material data such as the layer thicknesses and the particle size distribution, the lithium diffusion coefficients, as well as the entropic heat coefficients, the heat capacity and the thermal conductivity, which are especially used to calculate the heat flux in a battery, have been determined in the framework of our research group “Kems4Bats” in Mannheim.

The objectives of this work are to determine the heat flux as a material property and to compare the measured heat generation of a LiFePO₄ coin cell with our battery calorimeter (Netzsch MMC 274 Nexus) and the simulated and calculated heat generation by COMSOL Multiphysics based on the self-measured experimental materials data.