Electrochemical impedance spectroscopy EIS is a modern method to investigate the electrical and electrochemical properties of electrolysis cells.

Electrochemical impedance spectroscopy allows the investigation and evaluation of the cells including their components such as catalysts, membrane (MEA) or the bipolar plates.

The entire electrolysis stack can be examined during operation under different operating conditions, load conditions or currents, as well as individual cells or cell groups during operation.

The electrolysis cells usually have very low impedances. Due to the continuous increase of the active area of the electrolytic cells, during the further development, the electrochemical impedances become lower and lower (the electrochemical impedance is inversely proportional to the active area).

For the impedance spectrum, the electrolytic cell is excited (modulated) with a sinusoidal current. The modulation current is up to ±50A. The resulting voltage is measured with amplitude and phase over a larger frequency range.

The impedance is calculated from the modulation current and the resulting modulation voltage.

The impedance spectrum is created by the different measuring frequencies.

Other Applications