An analysis is performed on the diffusion of oxygen through tubular porous cathode substrates having several different geometries. It is shown that the flux of oxygen as it diffuses through these different substrate geometries can be explicitly expressed by a general analytical form with a unique geometric factor for each type of substrate geometry. Experimental measurements of the geometry-independent term, oxygen diffusivity, were conducted for two representative geometries: cylindrical and triangular tubes. These measurements show good agreement between samples with similar porosities and thus favorably support the oxygen flux equations presented. Formulations for the limiting current density were also derived directly from the oxygen flux equations. These are similarly expressed by a general analytical form with the same unique geometric factor depending on the particular substrate. Finally, three representative geometries, cylindrical, triangular, and square tubes, are used to illustrate the influence of the various dimensional parameters on the limiting current density.
Published in Journal of The Electrochemical Society, Volume 158, Issue 2, 2010, pages B84-B90.
©Journal of The Electrochemical Society 2010, The Electrochemical Society.
© The Electrochemical Society, Inc. 2010. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in Journal of The Electrochemical Society.
Publisher’s Version: http://dx.doi.org/10.1149/1.3517456
Huang, K. & Shull, J. L. (2010). Geometry-Dependent Oxygen Diffusion Flux and Limiting Current Density of the Cathode in a Cathode-Supported Solid Oxide Fuel Cell. Journal of The Electrochemical Society, 158 (2), B84 - B90. http://dx.doi.org/10.1149/1.3517456
Comparison of limiting current density of porous cylindrical and triangular cathode tubes calculated from Eqs. 25, 29 for 950°C.