%0 Journal Article
%A Endler, C
%A Leonide, A.
%A Weber, A.
%A Tietz, F.
%A Ivers-Tiffée, E.
%T Time-dependent electrode performance changes in intermediate temperature solid oxide fuel cells
%J Journal of the Electrochemical Society
%V 157
%@ 0013-4651
%C Pennington, NJ
%I Electrochemical Society
%M PreJuSER-10068
%P B292 - B298
%D 2010
%Z Record converted from VDB: 12.11.2012
%X This study gives evidence that the time-dependent performance changes in anode supported cells for intermediate-temperature solid oxide fuel cells is essentially influenced by the mixed ionic-electronic conducting (MIEC) cathode. The impedance spectra recorded during 700 h of operation at 750 degrees C were interpreted using an appropriate equivalent circuit model by (i) a distribution of relaxation time analysis followed by (ii) a complex nonlinear least squares fit. Four electrode polarization processes were separated by selective experimental parameters. The cathodic part, initially the smallest, is only discovered among the anodic contributions by a change in fuel gas composition from H-2-H2O to CO-CO2 and increases by 310% (15 m cm(2) at 11 h, 62 m cm(2) at 700 h). A Sr (and Co) depletion of the MIEC cathode composition La0.58Sr0.4Co0.2Fe0.8O3-delta possibly caused this degradation. The anodic polarization has a proportion of 92% at the start and decreases to 73% (168 m cm(2) at 11 h, 173 m cm(2) at 700 h). The anode charge-transfer reaction initially causes 60% of the total polarization losses and 50% after 700 h. This is assigned to a change in the triple phase boundary and/or a degradation in ionic conductivity in the anode functional layer. The gas diffusion polarization remains constant at 58 m cm(2).
%K J (WoSType)
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000273222700036
%R 10.1149/1.3270047
%U https://juser.fz-juelich.de/record/10068