The influence of external operating conditions on membrane drying faults of proton-exchange membrane fuel cells

Abstract

A study of the influence of water management failure can help improve water management strategies, relieve flooding or drying faults. To explore the influence of drying faults on proton-exchange membrane fuel cells (PEMFCs) under different operating conditions, this study adopted an experimental measurement method combining a cathode voltage drop, voltage signal and electrochemical impedance spectroscopy (EIS). First, multiple sets of drying experiments were performed under different operating conditions, cathodic pressure drop and voltage data were collected during the experiments, and dynamic EIS measurements were performed. Then, by analyzing the pressure drop and voltage trends, the influence of different operating conditions on drying faults was obtained. In addition, the EIS results were parametrically identified using an RL(RQ-RC) equivalent circuit model to obtain ohmic, charge transfer, and mass transfer impedance values. Finally, the evolution and influence of drying faults were verified by impedance variations. The experimental results showed that the ohmic and charge transfer impedance increased significantly with the degree of drying fault, while the mass transfer impedance showed only a small fluctuation or slight increase. Increasing the cathodic back-pressure relieved drying; a larger cathodic stoichiometric ratio increased the drying rate, and a higher cell temperature was more likely to cause severe drying.