Coupled electrochemical and thermal battery models for thermal management of prismatic automotive cells

Abstract

This study combines a two-dimensional Ohm’s law finite-volume approach determining the current distribution in prismatic battery cells with a simplified electrochemical model for the thermal state of automotive battery packs. The objective was to develop a simulation tool for assessing the effect of cooling effort applied to automotive battery packs under real-life usage conditions. The Ohm’s law model was enhanced by imparting a chemical and physical basis to source terms previously found empirically. This simulation was applied to 2D electrode sheets, determining thermal generation values that were mapped volumetrically into a thermal simulation, which in turn, updated the electrochemical simulation. Battery parameters, along with capacity fade kinetics were determined by fitting experimental data to simulated results. Dynamometer data from tests under reference drive cycles provided current demands on battery cells. Thermal profiles simulated for 30 A h prismatic cells at different cooling levels. Passive and forced air cooling simulations both gave endpoint temperatures upwards of 40 °C (313 K), considered excessive for preserving the battery life. A simulation scenario which reflected a liquid cooling system kept the temperature gain for a US06 drive cycle to about 2 K. With liquid cooling, an automotive battery is better protected against thermally driven degradation.