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@INPROCEEDINGS{Schnauer:827599,
author = {Schönauer, Kathrin and Fang, Qingping and Blum, Ludger and
Menzler, Norbert H.},
title = {{C}athode contacting in {SOFC} stacks},
reportid = {FZJ-2017-01718},
year = {2017},
abstract = {In SOFC stacks the electrical contact between the ceramic
cathode layer and the metallic interconnector (IC) has to be
adjusted carefully to minimize the contact resistance and
slow down degradation mechanisms. In JÜLICH, ICs made of
Crofer22APU or Crofer22H are coated with a MnCo1.9Fe0.1O2
spinel (MCF) applied by atmospheric plasma spraying (APS),
which prevents the diffusion of volatile Cr species from the
steel into the cell. Materials for the cathode contact layer
have to be sufficiently good electronic conductors, stable
in oxidizing atmosphere, chemically stable and compatible
with the adjacent layers, and show a thermal expansion
behavior similar to MCF and the cathode material, i. e.
La0.58Sr0.4Co0.2Fe0.8O3-x (LSCF).Perovskites of La and Co,
doped with Fe, Mn, or Cu on the B-site have been applied by
wet powder spraying (WPS) onto the pre-coated IC. These
compounds offer a good electrical conductivity and an
appropriate thermal expansion but, depending on the
composition, they may form several phases instead of a
stable single phase. [1] Alternatively, LSCF can also be
used for cathode contacting and first tests show promising
results with better stack performances than the previously
mentioned compounds. Although the thermal expansion
coefficient of LSCF is quite large compared to those of MCF
and the IC material, the ability for thermal cycles is
given. Furthermore, no problems arising from chemical
reactions or interdiffusion are expected when the contact
layer is made of the same material as the cathode.As an
alternative to WPS, the contact layer is screen printed onto
the cell. At present, the full cathode is being covered
although the contact layer is required only between the IC
ribs and the cell. Applying the contact layer as stripes
could reduce the amount of material needed and at the same
time improve the gas supply from the interconnect channels
to the active sites for reduction in the cathode since the
gas transport may be the performance limiting factor at the
cathode side. [2]A different possibility for contacting the
cathode is to use metal foam sheets that are very easy to
handle. Two metal foams (CoNi and CuMn, provided by Alantum,
Rep. of Korea) have been examined regarding their electrical
and mechanical properties at high temperatures to evaluate
the suitability for SOFC stacks.References:[1] Montero,
Fischer, Tietz, Stöver, Cassir and Villarreal, Solid State
Ionics 180, 731 (2009)[2] Geisler, Kromp, Weber and
Ivers-Tiffée, Journal of The Electrochemical Society 161,
F778 (2014)},
month = {Jan},
date = {2017-01-30},
organization = {7th International Conference on
”Fundamentals $\&$ Development of
Fuel Cells”, Stuttgart (Germany), 30
Jan 2017 - 3 Feb 2017},
subtyp = {After Call},
cin = {IEK-1 / IEK-3},
cid = {I:(DE-Juel1)IEK-1-20101013 / I:(DE-Juel1)IEK-3-20101013},
pnm = {135 - Fuel Cells (POF3-135) / SOFC - Solid Oxide Fuel Cell
(SOFC-20140602)},
pid = {G:(DE-HGF)POF3-135 / G:(DE-Juel1)SOFC-20140602},
typ = {PUB:(DE-HGF)6},
url = {https://juser.fz-juelich.de/record/827599},
}