abstract
Developments of intermediate-temperature solid oxide fuel cells (IT SOFCs) require novel anode materials with a high electrochemical activity at 800-1070 K. The polarization of cermet anodes, made of nickel, ceria and yttria-stabilized zirconia (YSZ) and applied onto a YSZ solid electrolyte, can be significantly reduced by catalytically active ceria additions, the relative role of which increases with decreasing temperature. Further improvement is observed when using Ce0.8Gd0.2O2-delta (CGO) having a high oxygen ionic conductivity instead of undoped ceria, owing to enlargement of the electrochemical reaction zone. Nanocrystalline CGO powders with grain sizes of 8-35 nm were thus synthesized via the cellulose-precursor technique and introduced into Ni-CGO-YSZ cermets, and tested in contact with a (La0.9Sr0.1)(0.98)Ga0.8Mg0.2O3-delta (LSGM) electrolyte at 873-1073 K. The results showed that the anode performance can be enhanced by additional surface activation, in particular by impregnation with a Ce-containing solution, and also by incorporation of YSZ, which probably acts as a cermet-stabilizing component. The overpotential of the surface-modified Ni-CGO (25 wt%-75 wt%) anode in a 10% H-2/90% N-2 atmosphere was approximately 110 mV at 1073 K with a current density of 200 mA/cm(2).
keywords
OXIDE FUEL-CELLS; PR-DOPED CE(GD)O2-DELTA; ELECTROCHEMICAL PROPERTIES; CERAMIC MICROSTRUCTURE; IONIC-CONDUCTIVITY; CERIA; ELECTROLYTE; PERFORMANCE; CONDUCTORS; TRANSPORT
subject category
Electrochemistry
authors
Tsipis, EV; Kharton, VV; Bashmakov, IA; Naumovich, EN; Frade, JR
our authors
Jorge Ribeiro Frade
Retired Professor