Tomographic Analysis of Polymer Electrolyte Fuel Cell Catalyst Layers: Methods, Validity and Challenges

Abstract

Tomographic analysis of catalyst layers is one of the key methods to evaluate morphological properties in polymer electrolyte fuel cell PEFC catalyst layers. The most important applications for tomographic reconstruction are process control during manufacturing and investigations of ageing phenomena. We discuss all methods for tomographic imaging that are applicable for PEFC catalyst layers with an emphasis on focused ion beam / scanning electron microscopy tomography (FIB-SEMt). For now, no single tomographic method suffices to image all morphological properties of interest. Multi-tomographic approaches are therefore necessary. Phase fractions and phase-distributions are the most important properties to calculate within a tomographic reconstruction. We review further parameters that may be extracted from tomographic reconstructions and discuss open issues in first modeling approaches. Finally we discuss the validity of analyses within tomographic representations.