Fibsem Tomography: Connecting the Roles of Corrosion and Microstructure to Polymer Electrolyte Fuel Cell Performance and Durability

Abstract

Low-temperature proton exchange membrane fuel cells (PEMFC) may become essential energy conversion devices in the automotive sector and contribute to a future hydrogen economy. Corrosion of the cathode catalyst support is known to degrade performance but many specific details of the changes in performance are still poorly understood. A focused ion beam with scanning electron microscope (FIBSEM) method of nanotomography was developed for postmortem direct observation of corroded cathode microstructures. Unique to corroded cathodes, additional charge-reduction measures were taken to ensure high-fidelity imaging and low-error rate image processing. From three-dimensional reconstructed volumes, computational microstructural characterization methods were developed to extract pertinent transport parameters (e.g. porosity and tortuosity distributions) and characterize changes between pristine and corroded samples. FIBSEM and computational methods were coupled with traditional electrochemical techniques and carbon mass loss detection. Taken together, this work helps clarify and connect the roles of microstructure, corrosion, performance, and durability in PEMFCs. Figure 1