Quantitative evaluation of solid oxide fuel cell porous anode microstructure based on focused ion beam and scanning electron microscope technique and prediction of anode overpotentials

Abstract

A three-dimensional microstructure of a solid oxide fuel cell (SOFC) anode is directly observed by a focused ion beam and scanning electron microscope (FIB–SEM) technique. Microstructural parameters, which are closely related to transport phenomena and electrochemical reaction in a porous anode, are quantitatively evaluated, such as volume fraction, percolation probability, tortuosity factor, surface-to-volume ratio, and three-phase boundary density. A random-walk-based diffusion simulation is effectively used for quantification. As an application of the quantified parameters, 1D numerical simulation of a SOFC anode is conducted. The predicted anode overpotential agrees well with the experimental counterparts in the condition of 3.0% H2O–97% H2, 1273K, while it is overestimated at high humidified and low temperature conditions.