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

Abstract

An equivalent circuit is a combination of resistors, capacitors, inductors, Warburg impedance or constant phase elements which is widely measured and analyzed to understand 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 by 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 functionality judgement of an EC instrument. In this study, we conducted CV signal analyses on 5 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 judge the performance of a potentiostat quantitatively and automatically. This study enables researchers to calculate CV curves of resistors and capacitors formed EC equivalent circuits and provides a quantitative method to verify if an EC instrument is functioning well.