With a small amplitude current excitation (i.e., 10% of the applied current), the impedance response is sufficiently linear even when the direct current bias is well within the non-linear region of the kinetics. O-GEIS can allow an independent measurement of the anodic and cathodic kinetics, since the applied current can be either positive or negative, however such measurements would require three-electrode cells. Unfortunately, it is challenging to maintain stationarity at both high current density and low frequency, which generally limits O-GEIS measurements to lower current densities than the other techniques.