Influence of the gas diffusion cathode structure on the performance of an air-breathing proton exchange membrane fuel cell

This study presents a comprehensive analysis regarding the relevance of the cathode electrode structure on the performance of an air-breathing proton exchange membrane fuel cell, for which water management is a critical issue. In the light of the obtained results, general guidelines for designing a high-performance cathode for air-breathing operation are provided. Selecting adequate characteristics for the gas diffusion electrode in the cathode is shown to be crucial for optimizing performance. Sufficiently thin catalytic layers increase impressively Pt utilization by favouring the access of oxygen and protons to the electroactive centres. The properties of the gas diffusion medium for air-breathing cathodes have been also observed to be critical. The study reveals that selection criteria for gas diffusion layers based on high air permeability and good hydrophobicity does not ensure optimal performance. The ability of the GDL macroporous structure to expel water from the cathode is decisive for improving oxygen access to the catalytic layer and obtaining high-performance air-breathing fuel cells.