Water Management Fault Diagnosis by Operando Distribution of Relaxation Times Analysis for Anion Exchange Membrane Fuel Cells.

Timely and effective fault diagnosis is essential to ensure the reliability and longevity of anion exchange membrane fuel cells (AEMFCs). This study employs operando electrochemical impedance spectroscopy (EIS) measurements and distribution of relaxation times (DRT) analysis to detect water management faults in both anode and cathode electrodes. EIS measurements are performed under diverse operating conditions, revealing three distinct frequency ranges associated with ion transport, charge transfer, and mass transport processes, and elucidating their contributions to voltage loss. Building on these findings, DRT analysis is further applied to explore the behavior and variation of polarization impedance under different water management fault conditions. Compared with the reference case, anode flooding reduces ion transport resistance by up to 37.1%, while increasing charge transfer and mass transport resistances by 61.8% and 219.2%, respectively. Conversely, cathode flooding results in a 33.5% increase in charge transfer resistance, with minimal impact on mass transport resistance. These quantitative insights provide a novel and effective diagnostic tool for distinguishing water management fault types (flooding or drying) and their location (anode or cathode), offering valuable data to support the implementation of water management control strategies that enhance performance and extend the lifespan of commercial AEMFC stacks.