The Galvanostatic EIS technique is used to characterize an electrochemical interface. It is especially useful when the potential of the interface is changing with time. A small-signal AC-current excitation is applied to an electrochemical cell. The phase-sensitive AC voltage response of the interface is measured as the frequency of the excitation signal is varied.
Galvanostatic EIS can be useful in many areas of electrochemistry, including research in batteries, electrode kinetics, and industrial electrolysis. It can be used to measure the EIS spectrum of a battery while the battery is being discharged.
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: