Improved Modeling of Lithium-Based Batteries using Temperature-Dependent Resistance and Overpotential

The temperature-dependent behavior of the resistance and overpotential of a lithium-iron-phosphate (LiFePO4) battery cell is explored in this paper. Offline experimental results from hybrid pulse power characterization (HPPC) tests and electrochemical impedance spectroscopy (EIS) methods for resistance and overpotential are explained using Arrhenius equations. Using a nonlinear regression technique, simulated drive cycle data are used to confirm the experimental findings and construct a generic cell model that explicitly takes temperature effects on the resistance and overpotential into account. The significance of the work lies in its confirmation of the inadequacy of the baseline linear-circuit model for lithium batteries at low temperatures and its presentation of a modeling approach that provides much better agreement with measured battery characteristics.