Redox cycling of Ni–YSZ anodes for solid oxide fuel cells: Influence of tortuosity, constriction and percolation factors on the effective transport properties

作者: L. Holzer , B. Iwanschitz , Th. Hocker , L. Keller , O. Pecho

DOI: 10.1016/J.JPOWSOUR.2013.05.047

关键词:

摘要: Abstract A methodology based on FIB-tomography and image analysis (IA) is proposed which allows quantification of all relevant morphological features that are necessary to predict effective transport properties in porous SOFC electrodes. These constrictivity, tortuosity, percolation factor phase volume fraction. An M-factor can then be calculated represents the ratio over intrinsic conductivities. The used describe effects microstructure degradation Ni–YSZ anodes caused by redox cycling at 950 °C. so M-factors because electronic conductivity nickel decreases from 3 1.2% mainly due changes constriction factors. Based these results electrical predicted 685 S/cm before 243 S/cm after 8 cycles. predictions fit well with experimental measurements reveal 600 S/cm 200 S/cm For YSZ obtained 3D-analysis causes a drop ionic 7 0.6%, change bottleneck dimensions. This finding contradicts frequent interpretation as ‘rigid backbone’ not affected degradation. Finally, bulk gas diffusivity increases 2 11% an increase porosity associated swelling anode.

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