Sensitivity Study of Battery Thermal Response to Cell Thermophysical Parameters 2021-01-0751

Lithium-ion batteries (LiBs) have been widely used in electrified vehicles, and the battery thermal management (BTM) system is needed to maintain the temperature that is critical to battery performance, safety, and health. Conventionally, three-dimensional battery thermal models are developed at the early stage to guide the design of the BTM system, in which battery thermophysical parameters (radial thermal conductivity, axial thermal conductivity, and specific heat capacity) are required. However, in most literature, those parameters were estimated with greatly different values (up to one order of magnitude). In this paper, an investigation is carried out to evaluate the magnitude of the influence of those parameters on the battery simulation results. The study will determine if accurate measurements of battery thermophysical parameters are necessary. A unified method based on the understanding of the sensitivity of the key battery thermophysical parameters is proposed to identify the impact of measurement accuracy of thermophysical parameter measurements in battery thermal modeling. Thermal simulations of battery thermal models at the cell level (cylindrical 18650) and module level are developed with COMSOL Multiphysics® to perform the sensitivity analysis. The simulation results indicate that the specific heat capacity is the most remarkable thermophysical parameter affecting the temperature rise, temperature difference between cells, and heat dissipation rate of the battery model. The temperature difference between cells in a module exhibits a high sensitivity to axial conductivity, up to 1.05. Therefore, the specific heat capacity of the battery and axial thermal conductivity needs to be accurately measured for battery thermal modeling, while the radial thermal conductivity can be measured with lower accuracies.