Knowledge BaseElectrochemical Impedance Spectroscopy (EIS)

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Electrochemical Impedance Spectroscopy (EIS)

Electrochemical Impedance Spectroscopy (EIS) is an electrochemical techniques to measure the impedance of a system in dependence of the AC potentials frequency.

This is done by applying a sine-wave potential (AC potential) to the working electrode and read out the current, which should also be a sine wave. With the two sine waves (potential and current) the total impedance and phase shift for the corresponding frequency is calculated.

Figure 1 | Schematic representation of the potential excitation and current response in the measurement setup (left); potential and current waves over time (right)

The data points are either displayed in a Bode plot or used to determine the real and imaginary part of the impedance and presented in a Nyquist plot.

Figure 2 | EIS of a Randles circuit including a
Warburg element in a schematic Bode and Nyquist plot

By using equivalent circuit fitting the contribution of different effects to the impedance can be calculated. This allows to study changes of the interface in a very sensitive way. EIS is popular for coating research, label-free sensor research, or battery studies.

Figure 3 | EIS in PSTrace

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