Sadykov, V; Mezentseva, N; Usoltsev, V; Sadovskaya, E; Ishchenko, A; Pavlova, S; Bespalko, Y; Kharlamova, T; Zevak, E; Salanov, A; Krieger, T; Belyaev, V; Bobrenok, O; Uvarov, N; Okhlupin, Y; Smorygo, O; Smirnova, A; Singh, P; Vlasovh, A; Korobeynikov, M; Bryazgin, A; Kalinin, P; Arzhannikov, A
This work presents the results related to the functionally
graded fluorite (F)-perovskite (P) nanocomposite cathodes for IT SOFC. Nanocrystalline fluorites
(GDC, ScCeSZ) and perovskites (LSrMn, LSrFNi) were synthesized by Pechini method. Nanocomposites
were prepared by the ultrasonic dispersion of F and P powders in isopropanol with addition of
polyvinyl butyral. Different techniques for deposition and sintering of functionally graded
cathode materials were applied including traditional approaches as well as original methods, such
as radiation-thermal sintering under electron beam or microwave radiation. Morphology,
microstructure and elemental composition of nanocomposites was characterized by XRD and HRTEM/SEM
with EDX. Even for dense composites, the sizes of perovskite and fluorite domains remain in the
nanorange providing developed P-F interfaces. Oxygen isotope heteroexchange and
conductivity/weight relaxation studies demonstrated that these interfaces provide a path for fast
oxygen diffusion. The redistribution of the elements between P and F phases in nanocomposites
occurs without formation of insulating zirconate phases. Button-size fuel cells with
nanocomposite functionally graded cathodes, thin YSZ layers and anode Ni/YSZ cermet (either bulk
or supported on Ni-Al foam substrates) were manufactured. For optimized composition and
functionally graded design of P-F nanocomposite cathodes, a stable performance in the
intermediate temperature range with maximum power density up to 0.5 W cm(-2) at 700 degrees C in
wet H(2)/air feeds was demonstrated. (C) 2010 Elsevier B.V. All rights reserved.