Quantitative analysis of proton exchange membrane fuel cell degradation during idling using distribution of relaxation times

This study focuses on the analysis of the different polarization losses in proton exchange membrane fuel cells (PEMFCs) during idling by using the distribution of relaxation times (DRT) method quantitatively. By varying operating parameters, cathodic mass transfer and oxygen reduction reactions were identified as the primary contributors to cathode mass transfer process (P1 peaks) and charge transfer process (P2 peaks) respectively. The resistance values for each polarization were obtained by fitting areas of the DRT peaks and compared with I–V steady-state values to validate the accuracy of the method. The effect of idling conditions on PEMFC attenuation at different current densities was analyzed. The result shows that during idle aging, cathode catalytic layer activation resistance growth accounts for 55% at 0.4 A cm⁻², cathode mass transfer resistance for 31.2%, and Ohmic resistance for 13.7%.The electrochemically active area decreased by 16.7% from 27.32 to 22.77 m² g⁻¹. DRT can quickly and accurately identify the main reason for PEMFC deterioration.