Electrochemical impedance spectroscopy (EIS) is the most common methodology employed for characterisation of electrochemical energy systems. Typically, excitation includes (multi-) sine signals. As a result the characterisation process is often time consuming and lacks accuracy in the low frequency region. Using stochastic excitation, for instance discrete random binary sequence (DRBS), alleviates the aforementioned problems. Furthermore, including techniques for identification of fractional order system (FOS) in the time domain offers a complete solution for performing complete characterisation of electrochemical energy systems. This combination offers several advantages. The identification process is performed in the time domain thus improving the accuracy while in the same time reducing the required time. The result of the identification process is a fractional-order transfer function in a closed form and the distribution of relaxation times (DRT) can be obtained by using a simple transformation. The proposed combination was validated on a single cell solid-oxide fuel cell (SOFC) in comparison with the EIS characteristics obtained via sine-based excitation.
COBISS.SI-ID: 32104743