Microstructure and connectivity quantification of complex composite solid oxide fuel cell electrode three-dimensional networks

Composite electrodes extend the electrochemically active region for solid oxide fuel cells. The complex microstructural and chemical composition of composite cathodes often make them difficult to fully characterize. The discrimination between the two oxide phases of the composite cathode as well as between them and the pore phase has been achieved using epoxy impregnation. The active regions of composite cathodes were analyzed at various length scales using focused ion beam/scanning electron microscope (FIB/SEM) and transmission electron microscope techniques. Dual beam FIB/SEM three-dimensional (3D) reconstructions provided information of various microstructural parameters. Over 5900 nodes were evaluated in these complex 3D networks. Topological connectivity of the composite LCM/ScSZ system was evaluated with the average connectivity ranging between 2.69 and 2.94 for the various phases. Topological length of the composite cathode network ranged between 1.5 and 2.7 μm, with average composite cathode particle sizes between 1 to 4 μm. Such connectivity quantification provides the opportunity for an advanced understanding of the transport processes in composite materials. © 2010 The American Ceramic Society.