The evolution and local characteristics study of water management faults in PEMFC based on multi-physics zonal measurements

Flooding and drying faults directly affect the performance and service life of proton exchange membrane fuel cell (PEMFC). This study develops an innovative in-situ monitoring system using a 25-zone printed circuit board (PCB) to replace the cathode current collector, enabling simultaneous measurement of zonal current density, temperature, and humidity. Flooding and drying experiments were performed with varying outlet back-pressures to investigate the performance degradation and local characteristics by simultaneous monitoring of voltage, localized multi-physics and electrochemical impedance spectroscopy (EIS). The experimental results showed that with flooding aggravation, ohmic impedance decreases slightly, while charge-transfer impedance increases mildly and mass-transfer impedance rises significantly. The current density becomes more uneven, with higher values in the middle and lower at the outlet. Humidity below the channel increases gradually, and the average temperature decreases. Conversely, under aggravated drying, both ohmic and charge-transfer impedances increase markedly, while mass-transfer impedance shows little change. The peak current density shifts toward the bottom of the channel, humidity presents a low-inlet to high-outlet gradient, and the temperature distribution becomes non-uniform, with the highest temperature gradually shifting downward. Additionally, with anode-only applied back pressure more likely to lead to severe flooding, and cathode-only applied back-pressure to alleviate drying.