# What is EIS testing?

## What is EIS testing?

Electrochemical Impedance Spectroscopy (EIS) is a well-established quantitative method for the accelerated evaluation of the anti-corrosion performance of protective coatings. Within short testing times, EIS measurements provide reliable data, allowing for the prediction of the long-term performance of the coatings.

### How do you perform electrochemical impedance spectroscopy?

Electrochemical impedance is usually measured by applying an AC potential to an electrochemical cell and then measuring the current through the cell. Assume that we apply a sinusoidal potential excitation. The response to this potential is an AC current signal.

#### How do you read EIS?

To interpret EIS data, it is common to make an analogy between the experimental data and an equivalent circuit made of capacitor, resistor, inductance and element that mimic diffusion processes, which depends on the electrode reactions. The elements used to build the equivalent circuit have to have a physical meaning.

**How do you do EIS experiment?**

Electrochemical impedance spectroscopy (EIS) is a powerful technique that utilizes a small amplitude, alternating current (AC) signal to probe the impedance characteristics of a cell. The AC signal is scanned over a wide range of frequencies to generate an impedance spectrum for the electrochemical cell under test.

**When to use phase angle Bode plot for CPE?**

As a result, the phase angle Bode plot is widely used in identifying the CPE exponent [18]. In this scenario the challenge is that an accurate determination of Ohmic resistance is needed. To do this, one usually plots the real part of the impedance versus frequency, and takes the high-frequency asymptote as the Ohmic resistance.

## How to visualize Electrochemical Impedance Spectroscopy measurements?

There are two ways to visualize electrochemical impedance spectroscopy measurements. One is a classic log-log plot, which will show the impedance at different frequencies. The other is a Nyquist plot, which compares the real and imaginary parts of electrochemical impedance.

### What does a Nyquist plot for an electrochemical impedance spectroscopy look like?

A typical Nyquist plot for an electrochemical impedance spectroscopy plot may not look anything like the above example, depending on the physical processes that dominate the cell’s electrochemical behavior.

#### How to plot the impedance spectrum of an electrochemical cell?

A log-log plot of the impedance spectrum for an electrochemical cell is one way to visualize the transition between different dominant physical processes in an electrochemical cell. This is among the simplest plots to construct using electrochemical impedance spectroscopy data.