Electrochemical impedance spectroscopy of PEM fuel cells at low hydrogen partial pressures: efficient cell tests for mass production

Quality testing costs hinder the large-scale production of PEM fuel cell systems due to long testing times and high safety measures for hydrogen. While eliminating both issues, electrochemical impedance spectroscopy at low hydrogen concentrations can provide valuable insights into fuel cell processes. However, the influence of high anode stream dilutions on PEM fuel cell performance is not yet completely understood. This study presents a new equivalent circuit model to analyze impedance spectra at low hydrogen partial pressures. The proposed model accurately describes the impedance response and explains the performance decrease at low hydrogen concentrations. First, the reduced availability of hydrogen at the anode leads to rising reaction losses from the hydrogen side. Further, the resulting losses lead to potential changes also influencing the cathode processes. The findings indicate that impedance spectroscopy at low hydrogen partial pressure might provide a reliable fuel cell quality control tool, simplifying production processes, reducing costs, and mitigating risks in fuel cell production.