Temperature Variations of A Lithium-ion Polymer Battery Cell During Electric Vehicle Driving Cycles

Abstract

The lithium-ion battery is the most widely-used onboard energy storage device for electric vehicle application thanks to its high energy-to-weight ratio, high energy-to-volume ratio, deep depth of discharge, and excellent cycle life. However, these appealing characteristics are heavily affected by the battery's operating temperature, which is the result of the ambient temperature augmented by the heat generated from the battery. To maintain the lithium-ion battery's operating temperature within the optimal range, an efficient battery thermal management system (TMS) is important and essential. Understanding the battery heat generation and battery temperature variation during its operations is required for designing the efficient battery TMS. In this paper, the temperature variations of a 20Ah lithium polymer battery cell during different driving cycles with different cooling media are studied. An electric vehicle model based on the 2018 Nissan Leaf is built in the GT-SUITE with experimental battery data. The temperature variation of the battery cell during different driving cycles is tested and simulated by using the terminal current generated by the GT-SUITE driving cycle simulations. Effects of air cooling and liquid cooling are also compared. With cooling air at 298K, the cell temperature increases between 2.3K to 5.1K to steady state from 298K, depending on the driving cycles. Cell temperature increase with cooling by liquid is only between 0.7K to 2.8K.