Influence of the cathode architecture in the frequency response of self-breathing proton exchange membrane fuel cells

• Conventional hardware elements have been adapted for the assembly of an AB-PEMFC.
• Electrochemical impedance spectroscopy has been used to analyze its behavior.
• Optimization of the cathode plate structure is crucial for enhanced performance.
• Minimized transverse deflection and slimness are the keys for cathode plate design.
• On-going work is expected to improve the specific energy density in new AB-PEMFCs.

Self-breathing proton exchange membrane fuel cells are apparently simple devices, but efficient water management is critical for their performance. The cathode configuration should guarantee balanced rates between O2 accessibility from the circumventing air and H2O removal, and a good electric contact between catalyst layers and current collectors at the same time. By applying progressive modifications to the initial concept of a conventional PEMFC, the effect of the cathode architecture on cell performance has been analyzed. Frequency response analyses of the cell during steady-state potentiostatic stepping have yielded relevant information regarding limitations originated by the cathode impedance under high current load conditions. The primitive cell design has been optimized for self-breathing operation by means of this diagnostic tool. The thickness of the perforated plate in the cathode has been found to be one of the main factors contributing to limit oxygen accessibility when a high current load is demanded. Adequate cathode architecture is critical for reducing mass transport limitations in the catalytic layer and enhancing performance under self-breathing conditions.