Development of test protocols for solid oxide electrolysis cells operated under accelerated degradation conditions
Benjamin Königshofer, Gernot Pongratz, Gjorgji Nusev, Pavle Boškoski, Michael Höber, Đani Juričić, Mihails Kusnezoff, Nikolai Trofimenko, Hartmuth Schröttner, Christoph Hochenauer, Vanja Subotić
Abstract
In order to be a real competitor to other industrial-scale hydrogen production technologies, solid oxide electrolysis cells (SOEC) must present essential features such as high hydrogen production rates, load flexibility and high system efficiency. However, operating conditions necessary to achieve these objectives can induce undesired performance deterioration and microstructural degradation negatively influencing the long-term stability of SOECs. This work provides the results of experimental investigations on the performance of SOECs operated under different operating conditions. In order to induce and accelerate specific degradation phenomena high steam partial pressures, fast load changes, high voltages, high steam conversion rates and alternating mode were applied. Different kinds and degrees of impact on performance and microstructure were observed and analyzed in detail. Correlations between performance changes and their underlying processes were investigated and useful connections between them were discovered. The major findings are summarized in the form of a suggestion for accelerated stress test (AST) protocols for SOECs. The developed ASTs enable deeper understanding of several degradation phenomena induced by different operating conditions and present methods for identification thereof. Further, the ASTs were estimated to have potential to predict performance changes over long-term operating periods.