Electrochemical characterization of high-power lithium ion batteries using triangular voltage and current excitation sources

We derive and implement analytic solutions for the description of batteries subject to cyclic voltage and current sources of varying amplitudes, consistent with vehicle drive events. An equivalent circuit comprising a resistor in series with a parallel resistor–capacitor combination is employed. The method we develop is applied to a high-power lithium ion cell, thereby allowing us to obtain parameters and overall characteristics useful for (1) representing the battery in system (e.g., vehicle) models and (2) providing a quantitative means of comparing and classifying battery systems. Closed-form analytic solutions derived using Fourier series are compared with experimental data.