Advancing Fuel Cell Materials through Electron Microscopy

D.A. Cullen
Oak Ridge National Laboratory,
United States

Keywords: fuel cell, catalysis, transmission electron microscopy

Summary:

Electron microscopy continues to play an important role in the development of polymer electrolyte membrane fuel cells (PEMFCs). This presentation will highlight several of the key contributions that electron microscopy has made to the fuel cell field, and demonstrate new and upcoming capabilities that will further enhance our understanding of the durability, degradation, and performance of fuel cell components. The Materials Characterization Center (MCC) at Oak Ridge National Laboratory (ORNL) has long served as a key partner for fuel cell development by collaborating with industry, academia, and other national laboratories to correlate structure and performance. A multimodal and multidimensional characterization approach is used to span several length scales ranging from hundreds of microns to the sub-Ångstrom level, leading to a more complete materials view for establishing structure-property relationships. We will demonstrate how structural/chemical quantification at the atomic-to-micrometer scale can be correlated with bulk electrochemical measurements of activity and durability to further understand and optimize PEMFC electrodes. Specific examples will include mapping ionomer dispersions across cathodes to improve electrode design, visualizing hierarchal pore structures in thick cathodes based on non-platinum group (non-PGM) catalysts to explain performance gains, quantifying catalyst de-alloying across the lifetime of a fuel cell to understand degradation mechanisms, and directly imaging active iron-nitrogen complexes in non-PGM catalysts. Overall, the presentation will demonstrate how PEMFC development has been accelerated by closely coordinating microscopy efforts with fuel cell design and testing. This research is sponsored by the Fuel Cell Technologies Office, Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy and through user projects supported by ORNL’s Center for Nanophase Materials Sciences (CNMS), which is a DOE Office of Science User Facility.