Local optimization of PEMFC and DMFC catalyst layers components for improved durability

Both proton exchange membrane (PEMFC) and direct methanol fuel cells (DMFC) technologies are limited in durability by a severe performance degradation determining a strongly localized heterogeneous components fading. Avoiding such localized early aging in critical areas could lead to improved durability for the overall device. A custom macro-Segmented fuel cell hardware, provided with local reference electrodes, has been developed to perform a detailed local investigation of performance and durability. The analysis revealed uneven current distribution during operation, most likely due to uneven reactants and products distribution, particularly related to components localized flooding or dehydration. Inhomogeneous performance distribution showed a strong impact on MEA heterogeneous fading, revealing analogies between the two technologies. Local optimization of catalyst layers formulation and operating protocol have been developed, assisted by modeling simulations, aiming to an homogeneous operation. Important improvements have been obtained on durability, demonstrated by local degradation testing and by post-mortem analysis of samples, confirming the validity of the methodology and the large scope for improvements still available.