Design of Sr0.7R0.3CoO3-δ (R = Tb and Er) Perovskites Performing as Cathode Materials in Solid Oxide Fuel Cells. Issue 10 (1st January 2017)

• Record Type: Journal Article
• Authors: Cascos, V.; Aguadero, A.; Harrington, G.; Fernández-Díaz, M. T.; Alonso, J. A.
• Is Part Of: Journal of the Electrochemical Society. Volume 164:Issue 10(2017)
• Page Start: F3019
• Page End: F3027
• Publication Date: 2017-01-01
• Subjects: cathode -- IT-SOFC -- neutron diffraction -- SrCoO3-; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0031710jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Sr0.7 R0.3 CoO3-δ (R = Tb and Er) tetragonal perovskites have been prepared and evaluated as mixed ionic-electronic cathodes for SOFC. Neutron powder diffraction (NPD) measurements evidenced that both compounds are oxygen hypo-stoichiometric with long-range order of oxygen vacancies that leads to a tetragonal perovskite-type superstructure (s.g. I4/mmm) stable within the whole temperature range under study. The oxygen vacancies located mainly in the equatorial oxygen positions exhibit large displacement factors. The high oxygen mobility in Sr0.7 Tb0.3 CoO3-δ was confirmed by 18 O oxygen labeling followed by Secondary Ion Mass Spectrometry (SIMS) with values of oxygen self-diffusion of 1.29 × 10 −10 cm 2 /s at 525°C. Polarization resistances with LSGM as electrolyte gave values as low as 0.011 Ω⋅cm 2 and maximum output powers of 570 mW/cm 2 at 850°C were obtained in test cells set in electrolyte-supported configuration. Electrical conductivity, thermal and chemical expansion and stability measurements confirm the potential of these materials as cathodes for SOFC.