A Multiscale Pore Analysis Method for Polymer Electrolyte Membrane Fuel Cell Catalyst Layers Validated and Exemplified by Correlating Microstructure with Production Process Parameters

This study introduces a comprehensive multiscale framework for analyzing and optimizing the microstructural properties of catalyst‐coated membranes (CCMs) in polymer electrolyte membrane fuel cells. The approach integrates mercury intrusion porosimetry, multiple microscopy techniques, and nondestructive focused ion beam scanning electron microscopy (FIB‐SEM), enabling detailed characterization across microstructural scales, from tens of nanometers to hundreds of micrometers. A custom MATLAB‐based image‐processing algorithm is developed to extract pore attributes—including size, porosity, and geometry—from FIB‐SEM cross‐sections, providing unprecedented insights into microstructural variations under varying fabrication conditions. This multiscale strategy enables robust analysis of catalyst layer features, from micrometer‐scale defects to nanoscale secondary pores. By employing this approach, the study reveals significant correlations between process parameters (such as hot‐pressing) and dispersion formulations with the resulting microstructural properties and electrochemical performance. Previously hidden dependencies were uncovered, demonstrating that catalyst layers produced from different dispersions exhibit distinct responses to hot‐pressing. For instance, the catalyst layers produced from dispersions containing higher alcohol and ionomer contents appear more susceptible to microstructural change under compression. This scalable, cost‐effective approach lays the foundation for rational, data‐driven design of CCMs and related electrochemical systems.