The above equations reveal that 𝑅 𝑐𝑡 , 𝑅 𝑐𝑡 ′ , and 𝑅 𝑐𝑡 0 represent three distinct types of chargetransfer resistances, and each of these is a real physical quantity, which can be experimentally measured with the appropriate electrochemical techniques. As an example, Fig. shows the calculated current and voltage versus time data for: PEIS with a 10 mV excitation, LA-GEIS with a 100 mA cm -2 excitation, S3E-CP with a 100 mA cm -2 applied current, and O-GEIS with a 100 mA cm -2 applied current and a 10% (10 mA cm -2 ) excitation. The calculations assume symmetric BV kinetics with α = 0.5 and I0 = 1 mA cm -2 . Direct-current techniques like S3E-CP can be used to measure the value of Rct as a function of applied current. Rct can also be measured by LA-GEIS, but due to the periodic nature of impedance measurements, LA-GEIS technically measures the root-mean-square (RMS) value of the charge-transfer resistance during the sinusoidal excitation . 𝑅 𝑐𝑡 0 can be measured with EIS using a sufficiently low amplitude excitation (of either voltage or current) applied about the equilibrium voltage of the cell. 𝑅 𝑐𝑡 ′ can be measured with O-GEIS by calculating the impedance response to a small-amplitude sinusoidal excitation, which is superimposed on a large applied direct current bias.