INVESTIGADORES
CANEIRO Alberto
congresos y reuniones científicas
Título:
Study of electrodes and electrodes/electrolyte interfaces of SOFC by electrochemical impedance spectroscopy and electron microscopy
Autor/es:
A. CANEIRO; A. SOLDATI; L. BAQUE; A. MONTENEGRO HERNANDEZ; L. MOGNI; A. SERQUIS; H. TROIANI; A. SCHREIBER; F. SOLDERA; K. YAKAL-KREMSKI; S. BARNETT
Lugar:
Dresden
Reunión:
Congreso; 3rd Dresden Conference "Energy in Future"; 2015
Institución organizadora:
Fraunhofer IWS
Resumen:
"Study of electrodes and electrodes/electrolyte interfaces of Solid Oxide Fuel Cell (SOFC) by using electrochemical impedance spectroscopy and electron microscopy?The most important loss of efficiency of a SOFC and IT-SOFC occurs at the cathode where the reduction of the molecular O2 takes place.Electrochemical Impedance Spectroscopy (EIS) is the usual technique to characterize the electrode reaction and is very sensitive to interfacial phenomena. On the other hand, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), High Resolution TEM (HRTEM) and Focused Ion Beam (FIB) are powerful techniques to characterize the microstructure of electrodes.In this talk we will show three examples of relevant information that can be obtained by using EIS and electron microscopy applied to the study of electrodes and electrode/electrolyte interfaces.-The combination of microstructural data obtained through 3D electron tomography by using FIB together with information obtained by fitting the impedance spectra [1] allows determining relevant properties of the porous Nd2NiO4+ electrode material such as oxygen ion diffusion coefficient Dδ, molar surface exchange rate Ro and surface exchange coefficient k [2].-TEM and HRTEM images at the La0.4Sr0.6Co0.8Fe0.2O3-(LSCF)/Ce0.8Gd0.2O1.85 (CGO) interface obtained with thin lamellas prepared by Focused Ion Beam (FIB)/lift-out technique provide useful information such as the grade of coverage of the interface and the presence of clean and semi-coherent electrode/electrolyte interfaces [3].The presence of this type of interface explains the good performance and high stability of these electrodes. - Despite the good bulk properties of the La2NiO4+ (LNO) materials such as mixed conductivity and Thermal Expansion Coefficient (TEC) similar to that of YSZ, EIS on symmetrical LNO/CGO/LNO and LNO/YSZ/LNO cells shows a drift of the polarization resistance with time, which suggests irreversible phenomena at the electrode/electrolyte interface. TEM images, HAADF and EDS analysis confirm the presence of reactivity at the LNO/YSZ/ and LNO/CGO interfaces whose extension depends on the electrode and electrolyte materials [4]. [1] S. B. Adler, J. A. Lane, and B. C. H. Steele, Journal of the Electrochemical Society, 
143 (1996) 3554. [2]Kyle Yakal-Kremski, L.V. Mogni, A .Montenegro-Hernández, A. Caneiro, S. A. Barnett, Journal of The Electrochemical Society, 161 (14) F1366-F1374 (2014).[3]A Soldati, L. Baque, H. Troiani, C. Cotaro, A. Schreiber, A. Caneiro, A. Serquis Int. J. Hydrogen Energy 36 (2011) 9180.[4] A. Montenegro-Hernández, A. Soldati, L. Mogni, H. Troiani , A. Schreiber, F. Soldera, A. Caneiro, Journal of Power Sources 265 (2014) 6.