Impedance Analyses on Porous Electrodes Considering the Distribution of Time Constants

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This study has been carried out to contribute to analyses on electrode structures of energy devices by applying an electrochemical impedance spectroscopy (EIS) to them. This study consists of EIS analyses on porous electrodes and cell structure analyses by finite element method (FEM). In the application of EIS, impedance spectra of porous electrode was separated depending on the frequency ranges, and itwas found that characteristic locus appeared for the porous structure in the middle frequency range. Pore size and electrolyte nature in the pore were investigated on the basis of impedance spectra. The current distribution during impedance measurement was calculated by FEM. It was found that the current distribution was changed depending on the imposed frequency. The relation between the porous structure and the characteristic impedance locus was discussed comparing the impedance results with the calculated current distribution. The analytical method developed by this study can be contributed to the material developments and operation monitoring’s of various energy devices.