Assessment of frequency response techniques in diagnosing polymer electrolyte membrane fuel cells.

In this study, we evaluated the effectiveness of various frequency response analysis (FRA) techniques for identifying fault states in the diagnosis of polymer electrolyte membrane fuel cells (PEMFCs). To this end, an identifiability analysis was conducted to determine the reliability of parameters obtained by fitting a previously validated PEMFC model to the spectra from different methods. Specifically, we focused on electrochemical impedance spectroscopy (EIS) and the newly introduced concentration frequency response analysis (CFRA). The identifiability analysis revealed that CFRA, when applied with water pressure as the input and voltage as the output, provides the most accurate parameters estimates related to mass transport in the cathode electrode and the Nafion electrolyte, yielding physically meaningful insights. Consequently, employing this input for PEMFC diagnosis emerges as a promising approach. Furthermore, our findings underscore the importance of meticulously evaluating the quality of parameter estimation, even when utilizing well-established techniques such as EIS.