Simulating High Current Discharges of Power Optimized Li-Ion Cells

Abstract

A full physics stack model combined with a detailed thermal model are applied to simulate voltage and temperature profiles of 26700 sized commercial Li-ion power cells. A wide range of currents (3A → 40A) and a wide range of temperatures ( − 20°C → 40°C) are considered. The conventional stack model is augmented to include pseudo-capacitance effects in order to get a reasonable agreement with the measured data. Least squares refinement of 21 data sets is used to determine a number of material properties and their temperature dependence. Practical guidelines are described for choosing input material properties and for using the least squares method. All 21 data sets are successfully simulated using one set of input parameters. Key features in the voltage and temperature profiles are explained by looking at the simulated state inside the stack.