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@ARTICLE{Nenning:874699,
author = {Nenning, Andreas and Bischof, Cornelia and Fleig, Jürgen
and Bram, Martin and Opitz, Alexander K.},
title = {{T}he {R}elation of {M}icrostructure, {M}aterials
{P}roperties and {I}mpedance of {SOFC} {E}lectrodes: {A}
{C}ase {S}tudy of {N}i/{GDC} {A}nodes},
journal = {Energies},
volume = {13},
number = {4},
issn = {1996-1073},
address = {Basel},
publisher = {MDPI},
reportid = {FZJ-2020-01614},
pages = {987 -},
year = {2020},
abstract = {Detailed insight into electrochemical reaction mechanisms
and rate limiting steps is crucial for targeted optimization
of solid oxide fuel cell (SOFC) electrodes, especially for
new materials and processing techniques, such as Ni/Gd-doped
ceria (GDC) cermet anodes in metal-supported cells. Here, we
present a comprehensive model that describes the impedance
of porous cermet electrodes according to a transmission line
circuit. We exemplify the validity of the model on
electrolyte-supported symmetrical model cells with two equal
Ni/Ce0.9Gd0.1O1.95-δ anodes. These anodes exhibit a
remarkably low polarization resistance of less than 0.1
Ωcm2 at 750 °C and OCV, and metal-supported cells with
equally prepared anodes achieve excellent power density of
>2 W/cm2 at 700 °C. With the transmission line impedance
model, it is possible to separate and quantify the
individual contributions to the polarization resistance,
such as oxygen ion transport across the YSZ-GDC interface,
ionic conductivity within the porous anode, oxygen exchange
at the GDC surface and gas phase diffusion. Furthermore, we
show that the fitted parameters consistently scale with
variation of electrode geometry, temperature and atmosphere.
Since the fitted parameters are representative for materials
properties, we can also relate our results to model studies
on the ion conductivity, oxygen stoichiometry and surface
catalytic properties of Gd-doped ceria and obtain very good
quantitative agreement. With this detailed insight into
reaction mechanisms, we can explain the excellent
performance of the anode as a combination of materials
properties of GDC and the unusual microstructure that is a
consequence of the reductive sintering procedure, which is
required for anodes in metal-supported cells.},
cin = {IEK-1},
ddc = {620},
cid = {I:(DE-Juel1)IEK-1-20101013},
pnm = {135 - Fuel Cells (POF3-135)},
pid = {G:(DE-HGF)POF3-135},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000522492700215},
doi = {10.3390/en13040987},
url = {https://juser.fz-juelich.de/record/874699},
}