Equivalence of time and frequency domain modeling for lithium ion batteries

Lithium-ion batteries are common energy sources for electric vehicles, energy storage systems, and require characterization techniques to evaluate the states and performance. The low frequency dynamics of lithium-ion batteries are rarely described accurately in existing models, which leads to the inability to establish the equivalence relationship between the time-domain model and the frequency-domain model. In this study, the equivalence of time and frequency domain modeling of lithium-ion batteries is illustrated based on a comparison between the parameter values of the equivalent circuit model (ECM) obtained from the time domain and those of the same ECM from the frequency domain. The time-domain parameters are extracted from the Hybrid Pulse Power Characterization (HPPC), and the frequency-domain ECM is fitted by the Electrochemical impedance spectroscopy (EIS). The equivalence is verified by theoretical derivation and experiments.