An Equivalent Circuit Model for Li-ion Batteries Considering Temperature Effect

Abstract

The State-of-Charge (SOC) estimation of Li-ion batteries is of great importance to the simulation of an electric vehicle (EV). A good model is needed to accurately estimate SOC. This paper gives an overview of state-of-art battery models. To the problem that the constant phase element (CPE) is a missing Laplace transformation, an equivalent circuit model (ECM) is introduced and the order of the model is identified using a numerical algorithm. This study uses electro-chemical impedance spectroscopy (EIS) to investigate the in-fluence of the cell temperature T on the battery in a wide fre-quency range. Results show that the double layer resistance increases as the cell temperature decreases. The consequences can amend the phenomenon that parameters of current models are constant, thus improve the adaptability to the battery tempera-ture change.