In this work, we present a case where electrochemical impedance spectroscopy (EIS) on stack level enabled the identification of degradation and failure mechanisms in a 75-cell solid oxide electrolysis cell (SOEC) stack from Topsoe. In a blind test, a defective stack (stack not passing the quality control specifications) prone to degradation was investigated with EIS. The type of stack defects was not known a priori. The purpose of the stack EIS experiment was hence to serve as a proof-of-concept of using EIS on the stack level for identifying degradation mechanisms. An appropriate equivalent circuit model was applied and fitted to the experimentally obtained EIS data, which enabled the quantification of the different electrochemical contributions. We hereby identified which electrochemical contribution(s) to the overall stack resistance caused the stack to degrade. Furthermore, the data was plotted in a degradation space format, which further strengthened the identification of the cause of degradation. In this work, we are exploring and utilizing the potential of advanced EIS characterization and analysis; thereby successfully identifying some of the degradation and failure mechanisms taking place in the SOEC stack. This detailed type of degradation analysis has, to the best of my knowledge, not previously reported on the commercial stack level.

中文翻译：

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探索电化学阻抗谱来识别和量化商业固体氧化物电解堆的降解

在这项工作中，我们提出了一个案例，其中堆级电化学阻抗谱 (EIS) 能够识别托普索 75 节固体氧化物电解槽 (SOEC) 堆中的退化和故障机制。在盲测中，使用 EIS 对易于退化的有缺陷的电池堆（未通过质量控制规范的电池堆）进行了调查。堆栈缺陷的类型事先未知。因此，堆栈 EIS 实验的目的是作为在堆栈级别使用 EIS 来识别退化机制的概念验证。应用适当的等效电路模型并将其拟合到实验获得的 EIS 数据，从而能够量化不同的电化学贡献。我们据此确定了对整体电池堆电阻的电化学影响导致电池堆退化。此外，数据以退化空间格式绘制，进一步加强了对退化原因的识别。在这项工作中，我们正在探索和利用先进 EIS 表征和分析的潜力；从而成功识别 SOEC 堆栈中发生的一些退化和故障机制。据我所知，这种详细类型的退化分析以前没有在商业堆栈级别上报告过。