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ECN publication
Title:
Constriction of current lines for a porous electrode and effect on electrolyte resistance
 
Author(s):
 
Published by: Publication date:
ECN 1998
 
ECN report number: Document type:
ECN-RX--98-010 Article (scientific)
 
Number of pages:
23  

Published in: Accepted for publication by the Journal of the Electrochemical Society (), , , Vol., p.-.

Abstract:
The electrodes generally considered for use in a Solid Oxide Fuel Cell(SOFC) consist of a porous structure on top of a dense electrolyte. The porous electrode may be viewed as a mesh of point contacts. Neglecting oxygen transport through the electrode material, the electrode reaction is confined to the three-phase boundary zone located at the perimeter of the point contacts. This results in a constriction of the current lines in the electrolyte. The associated increase of the apparent electrolyte resistance is referred to as the constriction resistance. In this study, the constriction resistance was calculated for a conducting ring-like geometry of the point contact using a finite element method. The ring mimics the actual three-phase-boundary (tpb) area. An empirical relation was derived for the constriction resistance. The width of the ring and the distance between nearest-neighbour rings were varied in the calculations. The numerical results are compared with those obtained for a circular contact and with experimental data for the constriction resistance of porous strontium-doped LaMnO3 electrodes on stabilised zirconia. 10 refs.


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