A Three-Dimensional Numerical Assessment of Heterogeneity Impact on a Solid Oxide Fuel Cell’s Anode Performance

Abstract

In this research, a fully three-dimensional, multiphase, microstructure-scale heterogeneous (non-continuous) electrode, Solid Oxide Fuel Cell (SOFC) stack model is implemented in order to assess the impact of homogeneity disturbance in an SOFC anode. The Butler–Volmer model is combined with recent empirical relations for conductivity and aspects of the Maxwell–Boltzmann kinetic theory describing the transport of mass within the porous medium. Methods for the localized quantification of electrode morphology parameters (such as triple phase boundary length) are implemented. The exchange current distribution in the electrode, the partial pressures and the electric potential fields for each phase are computed numerically. In order to simulate heterogeneity, transfer barriers of varying placement and size are added to an otherwise homogeneous, virtual microstructure based on data from FIB-SEM tomography. The results are compared to a model based on the continuous electrode theory, and the points of discrepancy are highlighted.