Unfortunately, for EIS measurements, the combined effects of non-linear kinetics and a large-amplitude excitation can result in harmonic distortions of the impedance signal, which complicate data analysis . Specifically, modern potentiostats use a frequency response analyzer (FRA) to measure the impedance, which essentially works by taking a Fourier transform of the DC data to calculate the magnitude and phase shift of the impedance signal . The FRA can separate the response at the fundamental frequency (i.e., the linear response) from the responses at other frequencies. When the LA-GEIS current excitation amplitude is sufficiently large to reach the non-linear region of the kinetics, a series of voltage responses with decreasing amplitudes are also generated at integer multiples of fundamental frequency; these voltage responses are referred to as the harmonics . Although the FRA can separate the linear response from the harmonics, the magnitude of the linear response is still distorted by the harmonics, causing an overestimation of the measured linear impedance . Qualitatively, these harmonic distortions manifest as a visible elongation of the semicircle at low frequency (Fig. ).