Electrochemical Performance of a Solid Oxide Fuel Cell with an LSCF Cathode under Different Oxygen Concentrations

Document Type

Article

Publication Date

4-2011

Publication Title

International Journal of Hydrogen Energy

Abstract

A new performance study has been performed on a commercially available anode supported planar SOFC containing an LSCF cathode. The SOFC cell is tested at different temperatures and different cathode gas compositions. The temperature and cathode gas dependence on the electrochemical performance is studied using voltage–current density curves and impedance spectroscopy at different cell voltages. The cell tested shows excellent performance at all temperatures and is not limited by diffusion losses for the tested conditions. This new study indicates that the cell impedance spectroscopy is comprised of at least four semicircles of which two are partially dependent on the cathode gas conditions. It was found that historical effects play a role in the impedance spectra, showing some scatter in the ohmic resistance as a function of applied voltage. The cell ohmic resistance decreases as the temperature increases and as the cathode gas conditions are switched from air to O2–He mixture. However, the cell ohmic resistance under pure O2 was found to be higher than the O2–He mixture. In virtually all IS data, the cell ohmic resistance showed a maximum value around 0.8 V. The cell ohmic ASR shows that interfacial resistances are a significant portion of the total ohmic resistance. The total electrode polarization decreases as the temperature increases and as the cathode gas conditions are switched from air to O2–He mixture and to pure O2. Finally, the peak frequency of the largest semicircle observed at high frequency shows a linear dependence on the applied voltage in most cases. This behavior is related to the charge transfer that occurs in the high frequency range and indicates that the electrochemical reactions are occurring at faster rates as more current flows through the cell.

Volume

36

Issue

8

First Page

5076

Last Page

5087

DOI

https://doi.org/10.1016/j.ijhydene.2011.01.017

ISSN

0360-3199

Rights

© 2011 Elsevier B.V.

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