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The Hybrid EIS technique is used to characterize an electrochemical interface. It is especially useful when the potential of the interface is changing with time and the interfacial impedance is strongly dependent on the measurement frequency. A small-signal AC-current excitation is applied to an electrochemical cell. The phase-sensitive AC response of the interface is measured as the frequency of the excitation signal is varied. The magnitude of the AC current is adjusted to obtain a nearly constant AC-potential level.
Hybrid EIS can be useful in many areas of electrochemistry, including research in batteries, electrode kinetics, and industrial electrolysis.
The output of an EIS experiment is a complex impedance spectrum. The term complex is used in its mathematical sense: containing both real and imaginary terms. An EIS spectrum is usually graphed as either a Bode plot (Impedance magnitude and phase plotted versus frequency) or a Nyquist plot (imaginary impedance plotted versus real impedance). Analysis of the impedance spectrum can give you the following information:
•Mechanistic and kinetic information