| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2016) | |
| Nanomaterials | Wednesday Sessions |
| Session NM-WeM |
| Session: | Nanocharacterization |
| Presenter: | Karren More, Oak Ridge National Laboratory, USA |
| Authors: | K.L. More, Oak Ridge National Laboratory, USA D.A. Cullen, Oak Ridge National Laboratory, USA B.T. Sneed, Oak Ridge National Laboratory, USA |
| Correspondent: | Click to Email |
Polymer electrolyte membrane (PEM) fuel cell performance and materials degradation, particularly associated with the cathode catalyst layer (CCL), can be directly attributed to the structure and chemistry of individual material components, as well as their uniformity/homogeneity within a CCL. The individual material constituents used to form the CCL within the membrane electrode assemblies (MEAs), e.g., the electrocatalyst (Pt or Pt-alloys), catalyst support (C-based), and ionomer films (proton conductor), and especially the critical interfaces that are formed between these various constituents, are critically importance in controlling fuel cell performance. Understanding the specific microstructural characteristics of the individual materials within the CCL, and how the materials interact during fuel cell operation/aging, is important for identifying materials optimization parameters that can significantly enhance performance and durability.
Research efforts at Oak Ridge National Laboratory are focused on the high-resolution microstructural and microchemical characterization of MEAs fabricated using different Pt-based electocatalysts and catalyst loadings, carbon-based support materials, and ionomer solutions, as well as the same MEAs subjected to accelerated stress tests (ASTs) designed to degrade specific MEA components and assess durability. High-resolution analytical microscopy methods are used to study the distribution and chemistry of materials and interfaces within CCLs, which are combined with high-resolution imaging and 3D electron tomography techniques to provide unprecedented insight into the structure and interfaces (ionomer/support, ionomer/catalyst, catalyst/support, ionomer/pore) in “real” MEAs before and after aging. This presentation will focus on understanding materials distributions within the CCL as a function of processing variables, e.g., initial ionomer and/or ink chemistry, electrocatalyst (type, loading, and dispersion), and the type of carbon support used. The stability of the ionomer films, electrocatalyst, and support structures in CCLs after ASTs will be evaluated.
________________________________________________________________________
Research sponsored by (1) the Fuel Cell Technologies Office, Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy and (2) Oak Ridge National Laboratory’s Center for Nanophase Materials Sciences (CNMS), which is a U.S. Department of Energy, Office of Science User Facility.