Engineered Electrode Microstructure for Optimization of Solid Oxide Fuel Cells

Abstract

This paper presents a mathematical model for the description of transport and reaction phenomena in porous composite electrodes for solid oxide fuel cell (SOFC) applications. The model is based on charge and mass balances, describing transport of charged and gas species along with the electrochemical reaction occurring at the solid/gas phase interface. Effective properties of the porous media are evaluated on numerically reconstructed microstructures. The correlation between electrode microstructure and electrochemical performance is investigated. In particular, the study focuses on how a distribution of particle size within the thickness may improve the air-electrode efficiency. The results show that distributing smaller particles at the electrolyte interface reduces the sensitivity of the cathode efficiency to the electrode thickness, with clear advantages from the manufactory point of view. However, the conditions for which this advantage is relevant, that is, particle size smaller than 0.10 µm and porosity in the order of 15 %, are not technically achievable at the present.