Galvanostatic Table EIS (GEIS)

Electrochemical Impedance Spectroscopy (EIS) is an electrochemical technique that measures the impedance of a system as a function of AC current frequency. EIS enables the separation of different component influences, including contributions from electron transfer resistance, double layer capacitance, and other electrochemical processes.

GEIS applies a galvanostatic sinusoidal excitation signal and analyzes the resulting potential response from the device under test (DUT). The density parameter determines the number of measurement points within a specified frequency range. Averaging multiple sine waves reduces noise and non-systematic interference, although this increases the total measurement time.

Galvanostatic EIS is ideal for devices under test (DUT) with low impedances, such as fuel cells, electrolysis cells, batteries, and supercapacitors. High capacitance devices exhibit very long relaxation times. A drifting open circuit voltage (OCV) can cause very high equalizing currents in low impedance devices.

It is recommended to start the frequency table EIS at around 1 kHz, as this allows the IM7 to identify the correct measuring range more quickly. Starting at a lower frequency can significantly increase the time required to acquire the first measurement point.

For easy table editing, you can import and export CSV files, or simply drag and drop them into the table. You can also copy and paste data directly between spreadsheet applications like Excel or LibreOffice and the table editor.

Parameter Description

Parameter	Name	Description	Unit
I dc bias	DC bias current	DC bias current for defining the operating point of the object set to zero for state of charge	A
I amplitude	amplitude	AC current peak amplitude sine wave stimulation is from bias-amplitude to bias+amplitude	A
f	frequency	frequency of the impedance point	Hz
t meas	minimum measurement time	minimum recording time for each frequency step allow more averages at higher frequencies	s
N waves	minimum averages	minimum number of sine waves for each frequency step more averages for higher SNR

A Start Phase Galvanostatic can be enabled or disabled before the method is executed.

Measurement Result

The measurement results can be displayed as either Nyquist or Bode plots. To evaluate the spectra, the measurement data is fitted to a representative equivalent circuit model of the DUT. This approach enables the determination of detailed individual parameters for each equivalent circuit element.

Custom Experiment Builder

This experiment is a combination of the following blocks:

• Ramp - Current Voltage Curve

• Electrochemical Impedance Spectroscopy Table