Thermal Modeling of a LiFePO4/Graphite Battery and Research on the Influence of Battery Temperature Rise on EV Driving Range Estimation

Operating temperature of lithium-ion battery is an important factor strongly influencing the performance of electric vehicles. The battery temperature variation affects the remaining energy capacity, which in addition influences the remaining driving range of EV. An accurate range estimation method must take battery temperature rise into account, since the charge and discharge process leads to internal heat generation. In order to determine the battery temperature rise, we built a three-dimensional electrochemical-thermal model for a prismatic lithium-iron-phosphate/graphite cell, and calibrated its heat-transferring parameters. The accuracy of the 3-D model was verified by a series of discharge experiment, with the estimation error less than 1°C. Then a driving range estimation model was design for this battery on a pure electric vehicle. When considering or not-considering the battery temperature increase, a significant driving range estimation difference was found in Matlab/Simulink simulation, showing the importance of battery temperature prediction.