In-depth study of the Ruddlesden-Popper LaxSr2−xMnO4±δ family as possible electrode materials for symmetrical SOFC. (24th August 2017)

• Record Type: Journal Article
• Authors: Sandoval, Mónica V.; Pirovano, Caroline; Capoen, Edouard; Jooris, Romain; Porcher, Florence; Roussel, Pascal; Gauthier, Gilles H.
• Is Part Of: International journal of hydrogen energy. Volume 42:Number 34(2017)
• Page Start: 21930
• Page End: 21943
• Publication Date: 2017-08-24
• Subjects: Symmetrical SOFC -- Ruddlesden-Popper -- Maganite -- Neutron powder diffraction -- Electrical conductivity -- Electrochemical impedance spectroscopy; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2017.07.062
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: The Ruddlesden Popper (RP) manganites Lax Sr2−x MnO4±δ with compositions 0.25 ≤ x ≤ 0.6 have been successfully synthesized as single phases by solid-state reaction in air. All those materials are not only stable in reducing atmosphere but they also maintain the K2 NiF4 -type structure with I 4/ mmm symmetry under redox cycling conditions with limited volume changes. The x = 0.5 phase was analyzed by in situ high temperature neutron powder diffraction (HTNPD), under flowing hydrogen, showing the formation of oxide-ion vacancies on the equatorial sites of the perovskite planes, during reduction process. The total electrical conductivity was optimized and found maximum for x = 0.5 with values of 35.6 S cm −1 and 1.9 S cm −1 at 800 °C in air and 3% H2 /Ar, respectively, what is judged to be sufficient for an active layer of symmetrical SOFC electrode. First Electrochemical Impedance Spectroscopy (EIS) measurements in both oxidizing and reducing conditions, using an YSZ electrolyte and a GDC buffer layer, are presented giving rise to promising values. Highlights: Ruddlesden Popper Lax Sr2−x MnO4±δ are stable as SSOFC electrode for 0.25 ≤ x ≤ 0.6. In H2, oxygen vacancies form in the equatorial sites of [AMnO3 ] perovskite block. For x = 0.5, σ = 35.6 S cm −1 and 1.9 S cm −1 at 800 °C in air and 3% H2 /Ar, respectively. EIS measurements give promising ASR values as SOFC cathode and anode.