Surface-limited oxygen transport and electrode properties of La(2)Ni(0.8)Cu(0.2)O(4+delta)
authors Kharton, VV; Tsipis, EV; Yaremchenko, AA; Frade, JR
nationality International
journal SOLID STATE IONICS
author keywords lanthanum nickelate; IT SOFC cathode; oxygen permeation; cathodic overpotential; polarization resistance
keywords OXIDE FUEL-CELLS; MG-DOPED LAGAO3; ELECTROCHEMICAL PROPERTIES; STABILIZED ZIRCONIA; ION TRANSPORT; PERMEABILITY; CERAMICS; KINETICS; CATHODE; CONDUCTIVITY
abstract The submicron powder of La(2)Ni(0.8)Cu(0.2)O(4+delta) with K(2)NiF(4)-type structure, having grain size of 30-60 nm, was synthesized via glycine-nitrate process (GNP) and used for the preparation of porous cathode layers applied onto (La(0.9)Sr(0.1))(0.98)Ga(0.8)Mg(0.2)O(3-delta) (LSGM) solid electrolyte. In air, dense ceramics of LaNi(0.8)Cu(0.2)O(4+delta) possess thermal expansion coefficient of 13.3 x 10(-6) K(-1) at 400-1240 K, p-type electronic conductivity of 50-85 S/cm at 800-1300 K and relatively high oxygen permeability limited by the surface exchange. These properties provide a substantially high performance of porous electrodes, exhibiting cathodic overpotential lower than 50 mV at 1073 K and current density of 200 mA/cm(2). As for the oxygen transport through dense membranes, the results on electrode behavior, including the overpotential-microstructure relationships and the p(O(2)) dependence of polarization resistance, suggest that the cathodic reaction rate is affected by surface-related processes. Due to this, electrode performance can be considerably enhanced by surface activation, particularly via impregnation with Pr-containing solutions, and also by decreasing fabrication temperature. At 873 K, the surface modification with praseodymium oxide decreases overpotential of La(2)Ni(0.8)Cu(0.2)O(4+delta) cathode, screen-printed onto LSGM and annealed at 1473 K, from 330 down to approximately 175 mV at 50 mA/cm(2). (C) 2003 Elsevier B.V. All rights reserved.
publisher ELSEVIER SCIENCE BV
issn 0167-2738
year published 2004
volume 166
issue 3-4
beginning page 327
ending page 337
digital object identifier (doi) 10.1016/j.ssi.2003.11.020
web of science category Chemistry, Physical; Physics, Condensed Matter
subject category Chemistry; Physics
unique article identifier WOS:000220611500010
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