Cyclic voltammetry signal analyses for equivalent electric circuits consisting of multiple resistors and capacitors

Abstract

Abstract An equivalent circuit is a combination of resistors, capacitors, inductors, Warburg impedance, and constant phase elements, which are widely measured and analyzed to understand the electrochemical (EC) properties of materials such as batteries, thin films, or corrosion. An equivalent electric circuit is also built as different dummy cells to evaluate the measurement accuracy of EC instruments with key detection modes, including electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Dummy cell signals for EIS can be easily understood and simulated by existing EIS signal analysis software, while dummy cell signals for CV curves have no simulation formula so far. When using dummy cells for CV tests, users can only observe if the CV curves obtained seem to be correct, which impairs the accuracy and efficiency of quality as well as the ability to confirm the functionality of an EC instrument. In this study, we conducted CV signal analyses on five cases of equivalent circuits consisting of multiple resistors and capacitors, with their correctness verified by dummy cell experiments using two different potentiostats. Based on the measured CV signals, we further demonstrated a data process method to evaluate the performance of a potentiostat quantitatively and automatically. This study enables researchers to calculate CV curves of resistors and capacitors formed by EC equivalent circuits, and provides a quantitative method to verify whether an EC instrument is functioning well.