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A cell-level distributed electrochemistry (DEC) modeling tool has been developed to enable predicting trends in solid oxide fuel cell performance by considering the coupled and spatially varying multi-physics that occur within the tri-layer. The approach calculates the distributed electrochemistry within the electrodes, which includes the charge transfer and electric potential fields, ion transport throughout the tri-layer, and gas distributions within the composite and porous electrodes. The thickness of the electrochemically active regions within the electrodes is calculated along with the distributions of charge transfer. The DEC modeling tool can examine the overall SOFC performance based on electrode microstructural parameters, such as particle size, pore size, porosity, electrolyte- and electrode-phase volume fractions, and triple-phase-boundary length. Recent developments in electrode fabrication methods have lead to increased interest in using graded and nano-structured electrodes to improve the electrochemical performance of SOFCs. This paper demonstrates how the DEC modeling tool can be used to help design novel electrode microstructures by optimizing a graded anode for high electrochemical performance.

A computer model for species mass transport within the cathode of a solid oxide fuel cell (SOFC) is being developed based on the smoothed particle hydrodynamics method. Smoothed particle hydrodynamics is a grid-free modeling technique which uses a Lagrangian framework to model fluid dynamics systems as a discrete system of particles using a smoothing approximation. The method is able to handle complex geometries and complex physical and chemical phenomena with relative ease compared to grid based methods. The model is being developed to investigate chromium poisoning in the cathode of solid oxide fuel cells by examining the transport and reactions of chromium species in the cathode. The model includes ordinary and Knudsen diffusion within the cathode, which have both been shown to be significant mass transport processes in solid oxide fuel cells, and the adsorption reactions on the surface of the cathode. Chromium is thought to adsorb to the surface of the cathode reducing the number of adsorption sites for oxygen. The pore scale nature of smoothed particle hydrodynamics eliminates the need for effective properties of the porous structure to be used in the diffusion model. Previous solid oxide fuel cell electrode models based on effective diffusion models such as the dusty gas model rely on the bulk properties of the porous medium such as porosity and tortuosity to describe the complex microstructure of the electrodes. Bulk properties add unwanted uncertainty and error into the model, by using the smoothed particle hydrodynamics method some of these uncertainties can be removed from the model. The paper reviews past work on chromium poisoning, discusses the applicability of smoothed particle hydrodynamics for modeling the solid oxide fuel cell cathode and describes the model in detail.Copyright © 2008 by ASME