ANALYSIS OF NONEXPONENTIAL TRANSIENT-RESPONSE DUE TO A CONSTANT-PHASEELEMENT

To characterize electrical losses of fuel cells or batteries, impedanc e spectroscopy (IS) or current interruption (CI) can be used. Analysis and parameter determination of impedance data is widely used. The sys tem under study is usually represented by an equivalent circuit from w hich the system parameters can be determined. However, the analysis of current-interruption data is often carried out with too simple circui ts, e.g., using pure exponential behavior, because analysis in the tim e domain (CI) is often much more awkward than analysis in the frequenc y domain (IS). A comparative study has been carried out on the analysi s of a relatively ideal electrical circuit, containing a pure capacito r, and a more realistic circuit where the capacitor is replaced by a c onstant-phase element. Equations describing the response in the freque ncy and time domain are presented. Emphasis is put upon the analysis o f circuits containing a constant phase element because impedance measu rements clearly indicate the presence of such an element in many types of experiments, and because there is only limited literature availabl e describing the behavior in the time domain.