Durability and Micro-structural Mitigation Strategies for PEMFC (DOE-EERE - PI Atanassov, Co-PI Artyushkova)

UNM had a role in a large DOE-funded program in fuel cell durability lard by Ballard, a leader in fuel cell technology. Durability of the catalyst layer (CL) is of vital importance in the large-scale deployment of PEMFCs. CL degradation is linked to catalyst dissolution and agglomeration, ionomer degradation, carbon support degradation, and the degradation of pore morphology and surface properties. It is essential to determine parameters representing composition, structure and properties of cathode components and catalysts layer for the optimization of performance and durability.

The structure, morphology and surface species of the catalyst powder will affect the ionomer and catalyst interaction and dispersion in the catalyst layers and therefore the catalyst layer morphology and chemistry. These, in turn, will affect the catalyst layer effective properties such as thickness, porosity, tortuosity, diffusivity, conductivity, etc. UNM has been responsible for providing characterization of components of CL: from carbons, to catalysts to MEAs. Surface characterization using XPS was used to study surface composition for components. Morphological information was obtained from SEM images of components. TEM/EELS was used to study carbon and catalysts. Statistical structure-to-property correlations were built by means of principal component analysis in which structural, morphological and performance parameters were combined in one data set. Catalysts powders were also subjected to ex-situ degradation protocol in which structural changes were correlated with performance changes. Correlations between composition, structure and properties of cathode components and the catalyst layer have been developed and linked to catalyst layer performance losses. The key interactions between materials properties and structure, catalyst layer effective properties, performance and durability, will provide design and optimization levers for designing MEAs for different operating regimes. The list below summarizes all data that have been acquired and analyzed.

20nm

TEM images of Low Surface Area FC catalyst at different stages of its degradation.

K. Artyushkova, S. Pylypenko, M. Dowlapalli and P. Atanassov, Structure-to-Property Relationships in Fuel Cells Catalysts Supports: Correlation of Surface Chemistry and Morphology with Oxidation Resistance of Carbon Blacks, J. Power Sources, 214 (2012) 303-313
K. Artyushkova, S. Pylypenko, M. Dowlapalli and P. Atanassov, Use of Digital Image Processing of Microscopic Images and Multivariate Analysis for Quantitative Correlation of Morphology, Activity and Durability of Electrocatalysts, RSC Advances, 2 (2012) 4304-4310 A. Patel, K. Artyushkova, P. Atanassov, V. Colbow, M. Dutta, D. Harvey, and S. Wessel, Investigating the Effects of PEMFC Conditions on Carbon Supported Platinum Electrocatalyst Composition and Performance, J. Vacuum Sci. Tech. A, 30 (2012) 04D107