Effect of Ambient Temperature and Discharge Current on Thermo-Electrochemical Behaviour of Lithium-Ion Cells Using Surrogate Modelling and Analysis

Abstract

The thermal behaviour of lithium-ion cells plays a critical role in their overall performance and safety. The cell temperature fluctuates during operation due to varying operating conditions, particularly discharge current and ambient temperature. Thus, a precise thermo-electrochemical characterization is imperative for comprehending the behaviour of these cells under a wide range of operating conditions. Through experimental measurements, this study endeavours to determine the dependence of the thermo-electrochemical response of commercial lithium-ion cells as a function of discharge rates and ambient temperatures. High-fidelity reduced-order models are established using surrogate-based techniques to formulate response surfaces for the relevant output parameters, which enables the estimation of these parameters in cases where experiments were not performed. The study reaffirms that an increase in the discharge current rate results in an increase in the temperature difference between the core and surface of the cell. Also, a low ambient temperature has a relatively higher adverse impact on the battery performance, given the same discharge current. Furthermore, sensitivity analysis reveals that cell temperature, discharge capacity, and average discharge energy are more sensitive to ambient temperature than discharge current. On the other hand, the average discharge power is insensitive to ambient temperature and primarily dependent on the discharge current.