Electrochemical Measurement Techniques
As the core component of the overall solid oxide cell (SOC) system, the performance and stability of the SOC stacks are of the most importance. With common DC techniques, it’s possible to record the performance variation of the total stack or each repeating unit inside. However, determination of the reaction and degradation mechanisms during operation (online) are nearly impossible. With techniques based on alternating current excitation and frequency- and phase-sensitive measurement procedures, the in-situ separation of the different contribution to the total resistance of each repeating unit and stack becomes possible. One focus of the research is the electrochemical characterization and analysis of SOC stacks, inter alia by means of electrochemical impedance spectroscopy (EIS). The DRT deconvolution (Distribution of Relaxation Times) improves the relatively poor frequency resolution of Nyquist and Bode plots and greatly supports their interpretation as well as the development of equivalent circuit models.
Besides the electrochemical performance of the stacks, the thermo-mechanical stability and threshold are studied to further improve the stack design, and to optimize the operating parameters and strategies of SOC stacks/systems. Stack diagnoses are the main task, including detection of any mechanical failures during operation by combination of physical sensing techniques and electrochemical analysis. All findings are used to further improve the stack design and for validation in the development of computational models.
Based on the long-standing experience on endurance and cycling tests of stacks, as well as the established comprehensive know-how on degradation mechanisms of stacks, a methodology of accelerated stress test (AST) should be developed.
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Last Modified: 11.02.2025