Water management and mass transport of a fractal metal foam flow-field based polymer electrolyte fuel cell using operando neutron imaging

Abstract

Metal foam flow-fields (MFFs) exhibit immense potential for enhancing the performance of polymer electrolyte fuel cells (PEFCs) owing to their advantageous pore connectivity and abundant gas pathways. Nevertheless, challenges remain with the conventional MFF concerning reactant homogeneity and water management. To address these concerns, this study incorporates a fractal manifold into the MFF design. By employing operando neutron imaging, device-level testing, and electrochemical impedance spectroscopy (EIS), a comprehensive understanding of mass transfer and water management characteristics across the fractal manifold MFF is obtained. This novel design delivers better cell performance and lower mass transport resistance compared to the conventional MFF under all experimental conditions investigated. Notably, neutron imaging reveals that the fractal manifold MFF consistently exhibits a reduced liquid water content and more uniformly distributed liquid water compared to the conventional MFF. These superior characteristics of the design contribute to a substantial ∼15% increase in maximum power density compared to the conventional MFF-based PEFC. The results indicate the potential for further performance improvement by optimizing manifold parameters.