The Debye Layer as a Transmission Line in the 4 Hz-100 kHz Frequency Range

We report measurements on the electrical double layer at a gold electrode in several electrolytes. In the experiments, the Debye layer transmits a damped voltage wave along the electrode, which we use to probe the electrode-electrolyte interface. We compare the measurements with traditional impedance models, which schematize the Debye layer as a capacitance. We find good agreement not only for very dilute electrolytes but also for an ionic liquid. However, the same model fails for the concentrated electrolyte, as ion-solvent-ion interactions become important.