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