Real-Time Flooding Diagnosis for Dead-Ended PEMFCs Under Dynamic Loads Using Current Density Distribution

Water flooding severely degrades the performance and lifespan of proton-exchange membrane fuel cells (PEMFCs), impeding their large-scale application. A water flooding diagnostic approach is proposed based on the uniformity of current density distribution. This is achieved by employing a dead-ended PEMFC equipped with a 36-subarea current density detection plate for high-accuracy positioning. Experimental results demonstrate a positive correlation between the standard deviation (SD) of current density distribution and cell water content, following the linear equation y = 0.093x + 59.22 (R² = 0.955). Comparative tests show that constant voltage mode stabilizes water content at 78% ± 2% and SD at 380 ± 5 mA/cm² to suppress flooding, whereas constant current mode leads to excessive water accumulation (92.2%) and a sharp SD surge to 619.0 mA/cm², causing voltage collapse. Temperature tests (30–60 °C) confirm that elevated temperatures increase the visible water content inside the cell due to the condensation of water vapor, thereby enhancing current density inhomogeneity. This study establishes SD as a quantitative indicator for flooding severity, enabling precise localization of local flooding and providing critical guidance for PEMFC water management optimization.