Simulation of Electrochemical Impedance Spectroscopy (EIS)

Why is it Useful to Simulate Electrochemical Impedance Spectroscopy?

In order to facilitate the knowledge transfer between physics-based simulations and experimental measurements, EIS is also supported in our battery simulation software BEST, for both BESTmicro and BESTmeso. This enables a bidirectional exchange of information:

• On the one hand, EIS measurements can be used for parameter identification of the battery models.
• On the other hand, the fully parameterized physical models can provide insights into the cause and effect relationship between the experimentally observed impedance and the underlying internal transport of the cell.

Simulation of Electrochemical Impedance Spectroscopy (EIS)

To simulate the impedance, a virtual Li-ion battery is excited with a small voltage step and the resulting current relaxation is simulated within BEST. The double-layer capacity of the cell is taken into account. After a small post-processing step, we determine the impedance results numerically or present them in the form of the commonly used Bode or Nyquist diagrams.

The simulations are not limited to the classic full or half-cell configurations, but also support symmetrical and three-electrode cells, which are often used in EIS experiments to carry out a separate analysis of the individual electrodes. The simulation enables the consideration of so-called blocking conditions, i.e. the electrodes are in a state in which there is little or no charge exchange with the electrolyte.