| Characterization of a LSCF/GDC Cathode Composite in Solid Oxide Fuel Cells Using Impedance Spectroscopy |
| Jin-Ha Hwang, Byung-Kook Lee |
| Department of Materials Science and Engineering, Hongik University |
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| ABSTRACT |
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A composite cathode of LSCF$(La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_3);and;GDC; (Gd_2O_3-doped;CeO_2:Ce_{0.9}Gd_{0.1}O_{1.95_})$ was characterized in terms of an electrode response, using a point contact in an Yttria-Stabilized Zirconia (YSZ) electrolyte incorporated into AC two-point impedance spectroscopy. The point-contacted configuration amplifies the responses occurring near the YSZ/cathode interface through the aligned point contact on the planar LSCF/GDC electrode. The point contact interface increases the bulk resistance allowing the estimation of the point contact geometry and resolving the electrode-related responses. The resultant impedance spectra are analyzed through an equivalent circuit model constructed by resistors and constant phase elements. The bulk responses can be resolved from the electrode-related portions in terms of spreading resistance. The electrode-related polarizations are measured in terms of temperature and oxygen partial pressure. The modified impedance spectroscopy is discussed in terms of methodology and analytical aspects, toward resolving the electrode-polarization issues in solid oxide fuel cells. |
| Key words:
Electrolyte, Point contact, SOFe, Impedance spectroscopy, Spreading resistance |
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