Journal of Power Sources, Vol.412, 736-748, 2019
Microstructural correlations for specific surface area and triple phase boundary length for composite electrodes of solid oxide cells
The performances of Solid Oxide Cells (SOCs) are controlled by key microstructural properties such as the density of Triple Phase Boundary lengths (TPBI) and the interfacial specific surface areas (S-i/j). These electrode properties are dependent on basic morphological parameters defined by the phase volume fractions and the Particle Size Distributions (PSD) of the percolated solid phases. The understanding of these relationships is of central importance for designing an optimum electrode microstructure. In this study, semi-analytical expressions for the density of TPBI and the interfacial specific surface areas are investigated. For this purpose, a large number of synthetic microstructures are generated by using validated models based on the sphere packing and the truncated Gaussian random field methods. The coefficients of the parametric equations for both investigated properties (TPBI density and S-i/j) are fitted on the large database generated. The predictions of the micro structural correlations are in good agreement with the parameters directly computed on 3D reconstructions of typical LSCF-CGO and Ni-YSZ electrodes, thereby validating their reliability.