Electrochemical and thermal modeling of lithium-ion cells for use in HEV or EV application

To build a lithium battery system from single cells for use in an electric drive system the coupled electrochemical and thermal characteristics of these cells have to be well-known. Otherwise it is not possible to find the best cell for a given application considering capacity, power, thermal and electric management, housing, monitoring, etc. In the presented work an easy to parameterize Simulink model regarding the electrochemical and thermal properties was developed to simulate different cell types for an electric drive system. The model is based on an equivalent circuit diagram which is parameterized by means of impedance spectroscopy as well as of current pulse techniques. Differences of these methods are discussed briefly. By comparing simulation results and measurements it is shown that the coupled electrochemical-thermal model can predict the current - voltage behaviour and the temperature development of the different cells very exactly for both constant current profiles and load profiles appropriate for an electric forklift application.