Electrochemical behaviour of Ni-cermet anodes containing a proton-conducting ceramic phase on YSZ substrate
authors Mather, GC; Figueiredo, FM; Jurado, JR; Frade, JR
nationality International
journal ELECTROCHIMICA ACTA
author keywords cermets; ceramic proton conductors; anode materials; combustion synthesis; SOFC
keywords OXIDE FUEL-CELLS; OXYGEN-ION CONDUCTION; COMBUSTION SYNTHESIS; H2-H2O ATMOSPHERES; ELECTRODES; PERFORMANCE; IMPEDANCE; HYDROGEN; SOFCS
abstract Solid oxide fuel cell cermet anodes with proton-conducting ceramic phases, Ni-Si-Zr0.95Y0.05O2.975 (Ni-SZY), Ni-CaZr0.95Y0.05O2.975 (Ni-CZY) and Ni-SrCe0.475Zr0.475Y0.05O2,975 (Ni-SCZY), have been analysed by electrochemical impedance spectroscopy. The anodes were sintered on opposing faces of yttria-stabilised zirconia (YSZ) electrolyte and the polarisation behaviour studied in the temperature range 600-900degreesC in various regimes of H-2 and H2O partial pressures. The ceramic component of the Ni-CZY and Ni-SCZY cermets form an insulating phase at the interface with YSZ. Impedance spectra are composed of two dominant rate-limiting contributions attributable to electrode processes with relaxation frequencies ca. 10(3) and 1 Hz at 800 degreesC. Both high- and low-frequency responses are sensitive to H2O partial pressure and temperature, with activation energies in the range 1.02-1.25 and 1.19-1.35 eV, respectively. Factors influencing the origin of the rate-limiting processes are discussed, including transport limitations (oxide-ion and electronic) in the solid phases and microstructure. Proton conductivity may assist in accelerating the kinetics of the anodic reaction by widening the effective reaction area in electrodes optimised in terms of Ni content, oxide-ion conductivity and microstructure. (C) 2004 Elsevier Ltd. All rights reserved.
publisher PERGAMON-ELSEVIER SCIENCE LTD
issn 0013-4686
year published 2004
volume 49
issue 16
beginning page 2601
ending page 2612
digital object identifier (doi) 10.1016/j.electacta.2004.02.011
web of science category Electrochemistry
subject category Electrochemistry
unique article identifier WOS:000221076700008
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