Application of Fourier-based transforms to impedance spectra of small-diameter tubular solid oxide fuel cells

To understand the limiting transient processes in these small-tube fuel designs, an analysis approach which requires no a priori equivalent circuit model assumptions was applied. This approach was applied to the electrochemical impedance spectroscopy (EIS) data measured from such cells in the temperature range from 585 to 888 C. The complex overlapping arc EIS details (seen in Cole-Cole plots) were transformed in a network-model- independent way into a spectrum of relaxation times. The deconvolution method was extended to allow peak fitting and integration to calculate the resistances of individual processes within the cathode polarisation, which becomes limiting in comparison to either anode or electrolyte at temperatures below 700 C. With the new results, the process with the highest apparent activation energy can be targeted to improve cathode development. 19 refs.