Electrode Reconstruction by FIB/SEM and Microstructure Modeling

Polarization losses within solid oxide fuel cell electrodes are strongly related to microstructure characteristics and composition. High-resolution microstructure analysis is a sensible method to understand and improve electrode performance. This study presents the application of a dual-beam focused ion beam/scanning electron microscope (FIB/SEM) for the three-dimensional (3D) reconstruction of a high performance LSCF-cathode. Error sources arising from FIB slicing and SEM sequencing are identified and methods of correction are presented. The corrected reconstruction data representing altogether a volume of similar to 2800 mu m(3) are the basis for the calculation of the microstructure parameters (i) surface area, (ii) volume/porosity fraction and (iii) tortuosity. These parameters constitute the basis to calculate cathode performance via simplified microstructure models (1-3). Furthermore we present a detailed 3D finite element method (FEM) model to calculate the tortuosity from the accurately reconstructed 3D FIB/SEM data. This model has been extended to calculate electrode performance (ASR(cat)) from the 3D reconstruction.