The presented research shows that the long-term operation of a solid oxide fuel cell can lead to substantial anisotropic changes in anode material. The morphology of microstructure in the investigated stack was observed before and after the aging test using electron nanotomography. The microstructural parameters were estimated based on the obtained digital representation of the anode microstructure. Anisotropy was discovered in two of the three phases that constitute the anode, namely nickel and pores. The third component of the anode, which is yttrium-stabilized zirconia, remains isotropic. The changes appear at the microscale and significantly affect the transport phenomena of electrons and gasses. The obtained results indicate that the reference anode material that represents the microstructure before the aging test has isotropic properties which evolve toward strong anisotropy after 3800 h of constant operation. The presented findings are crucial for a credible numerical simulation of solid oxide fuel cells. They indicate that all homogeneous models must adequately account for the microstructure parameters that define the anisotropy of transport phenomena, especially if microstructural data is taken from a post-operational anode.

中文翻译：

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固体氧化物燃料电池阳极的各向异性微观结构演变。

提出的研究表明，固体氧化物燃料电池的长期运行会导致阳极材料发生实质性的各向异性变化。使用电子纳米断层扫描在老化测试之前和之后观察所研究的堆叠中的微观结构的形态。基于获得的阳极微结构的数字表示来估计微结构参数。在构成阳极的三个相中的两个相中发现了各向异性，即镍和孔。阳极的第三个成分是钇稳定的氧化锆，保持各向同性。这些变化出现在微观尺度上，并且显着影响电子和气体的传输现象。获得的结果表明，代表阳极材料在时效试验之前的微观结构，具有各向同性，这些特性在恒定运行3800 h后会向强各向异性方向发展。提出的发现对于可靠的固体氧化物燃料电池数值模拟至关重要。他们指出，所有均质模型都必须充分考虑定义输运现象各向异性的微观结构参数，特别是如果微观结构数据是从术后阳极获取的。