Galvanostatic OptiEIS Purpose

The Galvanostatic EIS technique is used to characterize an electrochemical interface which is held at a fixed current. 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.

EIS is a particularly powerful tool for the study of coated-metal corrosion. It is also useful in almost every other area 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:

• Polarization resistance
• Double-layer capacitance
• Solution resistance
• Coating-defect parameters
• Mechanistic and kinetic information

The Galvanostatic OptiEIS technique applies the same principle as a galvanostatic EIS scan, but the signal is a combination of multiple frequencies into a unified signal. The complex response pattern can be deconstructed via FFT to resolve the impedance spectra. The technique’s major advantage is a large reduction in experimentation time for experiments that reach into the millihertz and below frequency range.