Pressure Fluctuations in Dead-End PEMFCs: Current Density Dynamics Mechanism, Quantitative Response, and Asymmetric Pressure Optimization

Pressure fluctuations are unavoidable in vehicle-mounted proton exchange membrane fuel cells (PEMFCs), with anode and cathode pressure varying within ±30 kPa at 0.1–10 Hz. This study diagnoses the impact of pressure fluctuations on cell output performance by analyzing the uniformity of current density distribution, and accordingly proposes targeted mitigation strategies. Meanwhile, a visualized cathode cooling flow field was constructed with two transparent acrylic plates, enabling real-time observation of water distribution. Results show pressure fluctuations exert negligible impacts on cell voltage and current uniformity under low loads, with variation below 3%. At high loads, abrupt cathode pressure drops severely degrade cell stability. When cathode pressure drops from 80 to 60 kPa, current uniformity declines by 21.22%, output voltage falls by 10.23%, and local reversal area rises by 51.72%. The proposed anode pressure reduction strategy effectively alleviates local reverse current deterioration, boosting current uniformity by 14.73% and slightly restoring post-fluctuation voltage. This study establishes a quantitative correlation between pressure fluctuations and current density distribution uniformity in PEMFCs through a combined approach of segmented printed circuit board (PCB)-based diagnostics and cathode water visualization. Based on the revealed mechanism, an asymmetric regulation strategy via transient anode pressure reduction is proposed, which effectively suppresses cathode pressure fluctuation-induced degradation and improves cell performance.