A complete impedance analysis of electrochemical cells used as energy sources

Abstract

A comprehensive description of impedance of electrochemical systems has been presented, along with the assumptions of the method used. In this method, a multisinusoidal current excitation signal is used. The changes of potential of both the electrodes and the potential difference between these electrodes are all registered simultaneously as a function of time. The proposed method offers the possibility of separately determining the instantaneous value of impedance of each electrode as well as the impedance of a twoelectrode system. The short-time Fourier transform of time registers allow the determination of changes in the measured impedance values over time. The method has been successfully verified with an electrical equivalent circuit simulating a non-stationary two-electrode system. The values of the impedance of particular components during operation of the fuel cell under a changing load have been obtained.

Electrochemical Impedance Spectroscopy and its Applications

“…In practice, the signal is multiplied by the Gauss window and the product is Fourier transformed. Because of the leakage problem and lower power spectrum, the authors recently modified this technique [143]. They analyze a time period containing a whole number of periods of all functions, but because they do not acquire exactly 2 k points, they use the discrete Fourier transform (DFT).…”

Synthesis of hierarchical Co3O4@C composite and its lithium storage property as anode material for rechargeable lithium ion batteries

“…The Nyquist plots for the two samples are similar, displaying a typical characteristic shape with a circular arc in the high frequency range, which could be assigned to the R ct , and an inclined line in the low frequency range, which represents the W. In general, the smaller the diameter of a semicircle, the lower the charge-transfer resistance of an electrode. 39,40 It can be seen from Fig. 6 that the diameter of the semicircle in the high frequency region for the Co 3 O 4 @C electrode is much smaller than that of the Co 3 O 4 electrode.…”

Optimization of the Relative Humidity of Reactant Gases in Hydrogen Fuel Cells Using Dynamic Impedance Measurements

“…Due to the introduction of an additional variable component in the current signal, it is possible to simultaneously monitor the voltage and instantaneous impedance spectra during the variable load of the fuel cells. The DEIS method has been successfully used to identify malfunctioning cells in fuel cell stacks [39,40] and also for selecting the optimal conditions of the fuel cell operation [41,42].…”