Applications

A typical electrochemical impedance spectroscopy (EIS) experimental setup consists of an electrochemical cell, a potentiostat/galvanostat, and a frequency response analyzer (FRA). This Application Note introduces common EIS experimental setups as well as details of the main experimental parameters.

Electrochemical impedance spectroscopy (EIS) is a widely used multidisciplinary technique for characterizing the behavior of complex electrochemical systems. EIS is employed in the study of a range of complex systems including batteries, catalysis, and corrosion processes. This Application Note focuses on the basic principles of EIS measurements.

In this application note, electrochemical impedance spectroscopy (EIS) is used to test a commercial battery connected in two different ways. In the first EIS measurement, the battery is connected in a two-terminal sensing configuration. In the second EIS measurement, the battery is connected in a four-terminal sensing (Kelvin sensing) configuration. The difference in how the leads are connected results in different measured impedance values for the battery.

DC techniques do not provide any information about the internal dynamics of the PV device. Therefore, additional information can be obtained using time-dependent and frequency-dependent measurements. Electrochemical impedance spectroscopy in particular, offers the possibility to investigate the behavior of the device in the frequency domain under operating conditions, at various light intensities.

The way low-impedance devices, like fuel cells and battery, are connected to a load influences their performances. In this document, a comparison of EIS results on a commercial Li-ion battery is shown. Different EIS measurements have been performed, changing the way the battery has been connected to the potentiostat.

In this application note, the advantage of recording the raw time domain data for each individual frequency during an electrochemical impedance measurement is described.

In the application note AN-EIS-004 on equivalent circuit models, an overview of the different circuit elements that are used to build an equivalent circuit model was given. After identifying a suitable model for the system under investigation, the next step in the data analysis is estimation of the model parameters. This is done by the non-linear regression of the model to the data. Most impedance systems come with a data-fitting program. In this application note, the way NOVA is uses to fit the data is shown.

In this application note, a combination of PGSTAT and electronic load is use to perform electrochemical impedance spectroscopy in a fuel cell operating at high currents.

The use of impedance measurements on fuel cells under load makes it possible to study the influence of the different fuel cell elements on the behavior and (if detectable) on the ageing of the fuel cell. To perform high current density measurements, the Autolab systems can be connected to a third party electronic load. This extends the measurable range of the instrument by several current decades.

Here, the most common circuit elements for EIS are introduced which may be assembled in different configurations to obtain equivalent circuits used for data analysis.