Volume 182, 2015

Calcium manganite as oxygen electrode materials for reversible solid oxide fuel cell

Abstract

For an efficient high-temperature reversible solid oxide fuel cell (RSOFC), the oxygen electrode should be highly active for the conversion between oxygen anions and oxygen gas. CaMnO3−δ (CM) is a perovskite that can be readily reduced with the formation of Mn3+ giving rise to oxygen defective phases. CM is examined here as the oxygen electrode for a RSOFC. CaMn0.9Nb0.1O3−δ (CMN) with Nb doping shows superior electric conductivity (125 S cm−1 at 700 °C) compared with CM (1–5 S cm−1 at 700 °C) in air which is also examined for comparison. X-ray diffraction (XRD) data show that CM and CMN are compatible with the widely used yttria-stabilized zirconia (YSZ) electrolyte up to 950 °C. Both materials show a thermal expansion coefficient (TEC) close to 10.8–10.9 ppm K−1 in the temperature range between 100–750 °C, compatible with that of YSZ. Polarization curves and electrochemical impedance spectra for both fuel cell and steam electrolysis modes were investigated at 700 °C, showing that CM presented a polarization resistance of 0.059 Ω cm2 under a cathodic bias of −0.4 V while CMN gave a polarization resistance of 0.081 Ω cm2 under an anodic bias of 0.4 V. The phase stability up to 900 °C of these materials was investigated with thermogravimetric analysis (TGA) and variable temperature XRD.

Associated articles

Article information

Article type
Paper
Submitted
18 Feb 2015
Accepted
07 Apr 2015
First published
08 Apr 2015
This article is Open Access
Creative Commons BY license

Faraday Discuss., 2015,182, 289-305

Calcium manganite as oxygen electrode materials for reversible solid oxide fuel cell

C. Ni and J. T. S. Irvine, Faraday Discuss., 2015, 182, 289 DOI: 10.1039/C5FD00026B

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