Why is electrochemical impedance spectroscopy interesting for battery testing and battery studies? The most frequent use of impedance is to determine the State of Charge (SoC) of the battery as well as the degradation of its performance with cycling. Such studies are of interest for Battery Management System development and quality testing.
Two different approaches can be used to analyze the impedance measured on batteries:
- Search for correlations between one or several components values from equivalent circuits (ECs) and the SoC/SoH (state of health). This can then lead to the implementation of a testing procedure of batteries and can be used in the optimization of charge and discharge procedures. This approach is simpler but cannot be used as such if an understanding of the phenomena occurring at the electrodes is required;
- Analyze the impedance graph in order to understand electrode reactions, how to optimize them, and understand the phenomena involved in aging. This approach requires modelling of the electrochemical reactions occurring at the electrodes as well as the development of techniques that can help in assigning the impedance arcs to one or the other electrode.
