LA-GEIS measurements are conducted by applying a large-amplitude sinusoidal current perturbation about the equilibrium voltage of the cell. To measure Rct as a function of current, it is vital to use a current excitation instead of a voltage excitation, otherwise the effective current excitation would become frequency dependent . When the current excitation amplitude (𝐼 * ) is high enough to enter the non-linear region of the kinetics (i.e., 𝐼 * ≈ 𝐼 0 ), a non-linear voltage response to the sinusoidal current perturbation is generated, which manifests in two ways .