Experimental Study of the Performance of a Li-Ion Battery Cell in a Highway Driving Cycle

Abstract

Li-ion batteries, as a secondary battery type, are currently the most viable option for poweringhybrid/electric vehicles. They have considerable advantages such as high specific energy and power,no memory effect, long cycling life, low maintenance requirement, and low self-discharge rate.However, their thermal performance can easily deteriorate at extreme ambient temperatures.Therefore, in this study, thermal and electrical behaviors of Li-ion batteries were investigated undervarious operating temperatures using a driving cycle that represents a highway driving condition. Abattery testing system was used to determine the performance of Li-ion batteries under simulatedloads. The results show that the measured temperature profiles, in broad strokes, follow the currentprofile. Because of the thermal capacitance of the battery, the changes in temperature variations areobserved to be the smoothened out version of the current profile. Moreover, the results show that theextreme ambient temperatures have adverse effects on thermal performance of Li-ion batteries. Thevolumetric energy density and the capacity of the cell significantly decrease at cold ambienttemperatures, especially for the sub-zero temperature applications possibly due to weak ionicconductivity within the cell. On the other hand, the difference between the ambient temperature andthe surface of the cell becomes more pronounced as the ambient temperature decreases.