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Design of BaZr 0.8 Y 0.2 O 3–δ Protonic Conductor to Improve the Electrochemical Performance in Intermediate Temperature Solid Oxide Fuel Cells (IT‐SOFCs)
Author(s) -
D'Epifanio A.,
Fabbri E.,
Di Bartolomeo E.,
Licoccia S.,
Traversa E.
Publication year - 2008
Publication title -
fuel cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.485
H-Index - 69
eISSN - 1615-6854
pISSN - 1615-6846
DOI - 10.1002/fuce.200700045
Subject(s) - materials science , oxide , electrolyte , non blocking i/o , electrochemistry , chemical engineering , scanning electron microscope , stoichiometry , ethylene glycol , solid oxide fuel cell , analytical chemistry (journal) , inorganic chemistry , electrode , chemistry , catalysis , metallurgy , composite material , biochemistry , chromatography , engineering
BaZr 0.8 Y 0.2 O 3–δ , (BZY), a protonic conductor candidate as an electrolyte for intermediate temperature (500–700 °C) solid oxide fuel cells (IT‐SOFCs), was prepared using a sol–gel technique to control stoichiometry and microstructural properties. Several synthetic parameters were investigated: the metal cation precursors were dissolved in two solvents (water and ethylene glycol), and different molar ratios of citric acid with respect to the total metal content were used. A single phase was obtained at a temperature as low as 1,100 °C. The powders were sintered between 1,450 and 1,600 °C. The phase composition of the resulting specimens was investigated using X‐ray diffraction (XRD) analysis. Microstructural characterisation was performed using field emission scanning electron microscopy (FE‐SEM). Chemical stability of the BZY oxide was evaluated upon exposure to CO 2 for 3 h at 900 °C, and BZY showed no degradation in the testing conditions. Fuel cell polarisation curves on symmetric Pt/BZY/Pt cells of different thicknesses were measured at 500–700 °C. Improvements in the electrochemical performance were obtained using alternative materials for electrodes, such as NiO‐BZY cermet and LSCF (La 0.8 Sr 0.2 Co 0.8 Fe 0.2 O 3 ), and reducing the thickness of the BZY electrolyte, reaching a maximum value of power density of 7.0 mW cm –2 at 700 °C.