A Comprehensive Physical-Based Sensitivity Analysis of the Electrochemical Impedance Response of Lithium-Ion Batteries

The electrochemical impedance spectroscopy (EIS) characterization technique, although widely adopted in electrochemistry for understanding operational issues and degradation, has a less consolidated physical interpretation in lithium-ion batteries (LIBs), often relying on circuital methods. Herein, the Doyle–Fuller–Newman model is adapted and experimentally validated for the physical simulation of electrochemical impedance; then, it is applied in a comprehensive one-factor-at-time sensitivity analysis on an impedance spectrum from 4 kHz to 0.005 Hz; 28 physical parameters, which represent the kinetic, resistive, diffusive, and geometric characteristics of the battery, are varied within broad literature-based ranges of values, for each of the 20 analyzed battery states, characterized by different state-of-charge and temperature values. The results show a miscellaneous sensitivity of parameters on impedance spectra, which ranges from highly sensitive to negligible, often resulting in a strong dependence on operating conditions and impedance frequency. Such results consolidate the understanding of LIB electrochemical impedance and demonstrate that 40% of the parameters, 12 out of 28, can be considered poorly sensitive or insensitive parameters; therefore, fitting the experimental EIS data, their value can be assumed from the literature without significantly losing accuracy.