Reconstruction of solid oxide fuel cell electrode microstructure and analysis of its effective conductivity

The effective conductivity (σeff) of solid oxide fuel cell (SOFC) electrode is an important parameter for predicting the ohmic loss in SOFC. This paper investigates the effective conductivity of SOFC electrodes reconstructed numerically by packing spherical particles in a computational domain, followed by a dilation process to simulate the sintering procedure. The effects of various parameters on the effective conductivity of the electrodes are investigated, including material composition, porosity, particle size and contact angle. Results show that the effective conductivity ratio (σeff/σ0) of the computed conducting phase is mainly affected by its total volume fraction (VF) in electrode (including the porosity). The effective conductivity can be improved by increasing the VF, electrode particle size or the contact angle between electrode particles. Based on the numerical results, the conventional percolation model for the calculation of σeff is improved by adjusting the Bruggeman factor from 1.5 to 2.7. The results are useful for understanding the microstructure properties of SOFC composite electrode and for subsequent electrode optimization.