Static Drainage H2/O2 PEM Fuel Cells Enabled by Water Transport Plates: Pore-Scale Design and Transport Mechanisms.

As the suitability of proton exchange membrane fuel cells (PEMFCs) for underwater and space applications gains broader recognition, dead-ended operation has attracted increasing attention. However, water management challenges are exacerbated in PEMFCs without high-rate purge flows. Flooding frequently occurs, and thus hinders long-term stable operation. In this study, water transport plates (WTPs) were specifically designed to concurrently satisfy the dual requirements of passive water removal and gas tightness for dead-ended cathode operation. A pore-network model was established to investigate the capillary behavior mechanism within the porous structure, predict the water flux and bubble pressure of the WTPs, and further optimize the design of key parameters including average pore diameter. The network topology is reconstructed from X-CT images, and pore-throat shape corrections together with throat tortuosity are incorporated. By taking water flux (≥27.9 µL·cm-2·min-1) and bubble pressure (≥40 kPa) as evaluation indicators, the average pore diameter range of 1.2 ∼ 4.2 µm was selected. The optimized WTP was fabricated and assembled into a fuel cell stack. The stack operated stably for over 30 h with 1.92% performance decrease under dead-ended cathode operation at 1A·cm-2. These findings offer insights for the design and performance enhancement of dead-end PEMFCs with static drainage mode.