Nitrogen Blanketing and Hydrogen Starvation in Dead-Ended-Anode Polymer Electrolyte Fuel Cells Revealed by Hydro-Electro-Thermal Analysis

• Hydro-electro-thermal analysis of air-cooled fuel cell with dead-ended anode.
• Nitrogen cross-over from cathode has blanketing effect on anode.
• Dehydration of electrode centre and high current at periphery of electrode.
• Gap at edge of electrode has a flow bypass effect.

Dead-ended anode operation has a number of practical advantages that simplify system complexity and lower cost for polymer electrolyte fuel cells. However, dead-ended mode leads to performance loss over time which can only be reversed by performing intermittent purge events. This work applies a combined hydro-electro-thermal analysis to an air-cooled open-cathode fuel cell, presenting experimental functional maps of water distribution, current density and temperature. This approach has allowed the identification of a ‘nitrogen blanketing’ effect due to nitrogen cross-over from the cathode and a ‘bypass’ effect where a peripheral gap between the gasket and the GDL offers a hydrogen flow ‘short circuit’ to the border of the electrode. A consequence of high local current density at the margin of the electrode, and resulting high temperatures, may impact the lifetime of the cell in dead-end mode.

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