Monte Carlo Investigation of Particle Properties Affecting TPB Formation and Conductivity in Composite Solid Oxide Fuel Cell Electrode-Electrolyte Interfaces

Abstract

A previously developed microstructure model of a solid oxide fuel cell (SOFC) electrodeelectrolyte interface has been applied to study the impacts of particle properties on these interfaces through the use of a Monte Carlo simulation method. Previous findings that have demonstrated the need to account for gaseous phase percolation have been confirmed through the current investigation. In particular, the effects of three-phase percolation critically affect the dependence of TPB formation and electrode conductivity on (1) conducting phase particle size distributions, (2) electronic:ionic conduction phase contrast, and (3) the amount of mixed electronic-ionic conductor (MEIC) included in the electrode. In particular, the role of differing percolation effectiveness between electronic and ionic phases has been shown to counteract and influence the role of the phase contrast. Porosity, however, has been found to not be a significant factor for active TPB formation in the range studied, but does not obviate the need for modeling the gas phase. In addition, the current work has investigated the inconsistencies in experimental literature results concerning the optimal particle size distribution. It has been found that utilizing smaller particles with a narrow size distribution is the preferable situation for electrodeelectrolyte interface manufacturing. These findings stress the property-function relationships of fuel cell electrode materials.

Modeling and comparison to literature data of composite solid oxide fuel cell electrode–electrolyte interface conductivity

“…It is unclear from previous work whether or not the particle size and shape distributions are significant factors of percolation physics that affect overall cell performance [9][10][11]23].…”

“…(For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.) of the previous model and therefore included all of the capabilities described in the previous work [21,23]; additionally, the model in this work includes a process for analyzing the resulting conductivity network within the electrode-electrolyte interface and calculating the effective conductivity of this network.…”

“…In particular, porosity, volume fraction of electronic and ionic conducting materials, the addition of mixed conducting materials, surface exchange and transport phenomena, and current collector geometry have been previously investigated and characterized [21]. The model was also developed to allow investigations of the effects of particle size distributions in the different solid material phases as well as the pores [23]. Some characteristics that are pertinent to percolation physics and microstructure characterization, such as tortuosity, are not explicitly defined or evaluated in the model.…”