In-Situ through-Plane Measurements of Ionic Potential Distributions in Non-Precious Metal Catalyst Electrode for PEFC

Abstract

This manuscript presents micro-scale experimental diagnostics and nano-scale resolution X-ray imaging applied to the study of proton conduction in non-precious metal catalyst (NPMC) fuel cell cathodes. NPMC’s have the potential to reduce the cost of the fuel cell for multiple applications. However, NPMC electrodes are inherently thick compared to the convention Pt/C electrode due to the lower volumetric activity. Thus, the electric potential drop through the Nafion across the electrode thickness can yield significant performance loss. Ionomer distributions in the NPMC electrodes with different ionomer loading are extracted from morphological data using nanoscale X-ray computed tomography (nano-XCT) imaging of the cathode. Microstructured electrode scaffold (MES) diagnostics are used to measure the electrolyte potential at discrete points across the thickness of the catalyst layer. Using that apparatus, the electrolyte potential drop, the through-thickness reaction distribution, and the proton conductivity are measured and correlated with the corresponding Nafion morphology and cell performance.