Development of a model for the investigation of the role of mixed conduction in a solid oxide fuel cell anode to enable effectiveness of electrocatalyst infiltration
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Despite their potential for high efficiency energy production, the high temperature at which solid oxide fuel cells (SOFCs) must operate places significant restraints on materials selection which in turn limits the power density. Liquid infiltration of nickel nanoparticle catalysts into the anode can produce a higher density of reaction sites and has been shown to improve cell performance at significantly lower operating temperatures. Not all of these nanoparticles are connected to the Ni web network that provides a pathway for electron conduction to the external circuit, yet they improve the performance of the cell. Simulation provides an opportunity to gain an understanding of this physical phenomena where the scale of the regions in which the interaction between isolated Ni nanoparticle and connected Ni web take place makes direct experimental observation impossible. The purpose of this work is to develop a numerical model for charge transport in the electrolyte and around the Ni reaction sites. In Wolfram Mathematica 11.3 Student Edition, a 1-D model is established first, then built upon with increasing complexity to a 2-D model in which the Ni interfaces are scaled up to microns in size. Analytical solutions and dimensional analysis are used where possible to ensure the accuracy of the model results. Preliminary results from a micron-scale model indicate the existence of a favorable electric potential gradient between the isolated Ni particle and Ni web to drive current flow. The results also show a decrease in the magnitude of the electric potential measured on the isolated Ni particle as it is moved closer to the Ni web, and thus its position can be optimized. However, further work is needed to bring the scale of the Ni interfaces to their realistic dimensions in nanometers.