Vacuum-assisted drying of polymer electrolyte membrane fuel cell

Purging a polymer electrolyte membrane fuel cell (PEMFC) with dry N2 to remove water in the catalyst layer and the membrane during shutdown is necessary for ensuring successful startup and avoiding damages from the freeze/thaw cycling during cold-start. However, carrying N2 onboard may be impractical for mobile applications. Vacuum-assisted drying can accelerate and aid in water removal by reducing the boiling point of water, thus enhancing the evaporation and diffusion rate. This method is applied to a single cell PEMFC and compared to purging using dry N2. The drying process was monitored using electrochemical impedance spectroscopy (EIS), and the results were fitted to an equivalent circuit model. Our experimental results show the vacuum-assisted drying method may provide faster and more thorough water removal than N2 purging.