abstract
Composite ionic conductors for fuel cells were produced by combination of one ceria-based ceramic electrolyte and various mixtures of Na and Li carbonates, using several processing routes. These materials were characterized by impedance spectroscopy, scanning electron microscopy with energy dispersive spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy with attenuated total reflectance. The chemical composition of the mixed carbonates and the processing route were influential in the development of impressive conductivity levels (close to 0.1 S/cm) at modest temperatures (below 600 degrees C), suggesting a complex role of chemical composition (Na/Li ratio), phase composition (solid/liquid ratio), processing route (mechanothermal history) and microstructure. Furthermore, exposure to humidity showed formation of OH groups. Such hydrogenated species are believed to increase the complexity of the global surface processes and charge transport mechanisms where several native and foreign species may play a significant role. Copyright (C) 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
keywords
LOW-TEMPERATURE SOFCS; GAS SHIFT REACTION; DOPED CERIA; NANOCRYSTALLINE CERIA; ELECTRICAL-PROPERTIES; ITSOFC APPLICATIONS; CONDUCTIVITY; MICROSTRUCTURE; CONDUCTORS; ATMOSPHERE
subject category
Chemistry; Electrochemistry; Energy & Fuels
authors
Ferreira, ASV; Soares, CMC; Figueiredo, FMHLR; Marques, FMB
our authors
Fernando Manuel Bico Marques
Full professor
Filipe Miguel H Lebre R Figueiredo
Principal Researcheracknowledgements
Financial support from Project NANOCELL (PTDC/CTW098486/2008), FCT/COMPETE/FEDER (Portugal), and Project NANOCOFC (NMP3-CT-2007-032308), CEC (Brussels) is greatly appreciated.