Utility of Lissajous plots for electrochemical impedance spectroscopy measurements: detection of non-linearity and non-stationarity

Abstract

Correct interpretation of Electrochemical Impedance Spectroscopy (EIS) data is bound to the linearity and stationarity of the measurement. Current-Potential traces, also known as Lissajous figures for EIS measurements, contain valuable information regarding the linearity and the stationarity of the obtained data. Here, the behavior of the Lissajous figures is analyzed for various scenarios. The Lissajous analysis is shown to be helpful in the determination of the linearity and the stationarity of the data, especially for situations where Kramers-Kronig compatibility tests fail. The averaging of the Lissajous plots is shown to change the EIS results for non-linear and non-stationary systems. Further, the analysis of the Lissajous figures in the frequency domain by means of Fourier transforms is found to be very useful in differentiating between the non-linear and the non-stationary behaviors in the obtained data. The effect of averaging the Lissajous figures is also shown to make a difference when the system is non-stationary.