In situ x-ray, electrochemical, and modeling investigation of the oxygen electrode activation.

Conference · Sun Jan 01 04:00:00 EST 2006

OSTI ID:982328

Yildiz, B; Chang, K -C; Meyers, D; Carter, J D; You, H

Oxygen electrodes of solid oxide electrochemical cells have been shown to improve under strong cathodic and anodic polarization. Our study investigates the mechanism causing such improvement, using in situ x-ray and electrochemical characterization and electrochemical impedance modeling of the oxygen electrodes. Several porous and dense thin-film model electrodes of La{sub 0.8}Sr{sub 0.2}MnO{sub 3} (LSM) and La{sub 0.8}Sr{sub 0.2}MnO{sub 3} (LCM) on single crystal yttria-stabilized zirconia (YSZ) electrolytes have been analyzed in situ at the Advanced Photon Source (APS) using x-ray reflectivity and x-ray absorption near edge spectroscopy (XANES) at the Mn K-edge and La LII-edge. In situ x-ray reflectivity analysis show that no clear correlation between the polarization of the electrode and any further changes in the roughness of the LSM/YSZ interface exist. XANES measurements illustrate that the cathodic or anodic dc polarization at high temperature induces no detectable changes in Mn chemical state either in the bulk or at the surface of the LCM and LSM electrodes on YSZ, while the La chemical state changes reversibly at the electrode surface. This field-induced chemical change of La at the surface of electrodes is assumed to be a cause of the electrochemical activation through enhanced surface exchange of oxygen on the doped lanthanum manganite electrodes.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 982328
• Report Number(s): ANL/NE/CP-57617
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

30 DIRECT ENERGY CONVERSION
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ABSORPTION
ADVANCED PHOTON SOURCE
CHEMICAL STATE
CORRELATIONS
ELECTROCHEMICAL CELLS
ELECTRODES
ELECTROLYTES
IMPEDANCE
INTERFACES
LANTHANUM
MONOCRYSTALS
OXIDES
OXYGEN
POLARIZATION
REFLECTIVITY
ROUGHNESS
SIMULATION
SOLID OXIDE FUEL CELLS
SOLIDS
SPECTROSCOPY
TEMPERATURE RANGE 0400-1000 K