Characterisation of proton exchange membrane fuel cell (PEMFC) failures via electrochemical impedance spectroscopy

Two PEMFC failure modes (dehydration and flooding) were investigated using in situ electrochemical impedance spectroscopy (EIS) on a four-cell stack under load. The EIS measurements were made at different temperatures (70 and 80 °C), covering the current density range 0.1–1.0 A cm−2, and the frequency range 0.1–2 × 105 Hz. Dehydration and flooding effects were observed in the frequency ranges 0.5–105 and 0.5–102 Hz, respectively.We propose that impedance measurements at separate frequency ranges (or narrow bands thereof) can be used to distinguish between flooding and dehydration events. Similar approaches may be used to diagnose other important PEMFC failures.