Anode Behaviour Under Transients Near Equilibrium

6 Anode Behaviour Under Transients Near Equilibrium 

At the high-frequency limit of the spectrum the intercept on the resistive axis specifies the serial ohmic component in the measured system, since this element does not introduce a phase shift. Similarly the low-frequency limit approaches the steady-state condition corresponding to the d.c. characteristics of the cell. Each spectral feature detected between these limits represents a dissipation process with the specific time dependence indicated by the inverse of the frequency at which it occurs. It should be noted, therefore that two processes with similar time constants in the anodic system will not be distinguishable by impedance spectroscopy. 

In the case of high-temperature fuel cell anodes, conflicting evidence has been presented on the number and significance of the dissipative mechanisms detected as contributing to polarisation losses by impedance spectroscopy. At least three features may be distinguishable, dependent on the particular anode structure and the experimental conditions [17,19], This variability of the impedance spectra is 

By detailed investigation of some experimental model anode systems, however, a consensus is emerging on the interpretation of anode impedance 

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