Transient High-Temperature Oxygen Evolution Reaction

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Water (or steam) electrolysis, producing hydrogen gas as a chemical energy carrier, is a corner stone for the long-term storage of intermittent, renewably generated electricity. Hydrogen production is always accompanied by oxygen evolution at the counter- or air-electrode of the electrolysis cell. This electro-catalytic oxygen evolution reaction (OER) plays a decisive role for the efficiency of the hydrogen production due unfavorable overpotentials, causing severe overall losses. Among the known electrolysis processes, high-temperature solid oxide electrolysis cells (SOECs) constitute the most promising technology for the operation in a scenario with intermittent power supply, as elevated temperatures yield higher ionic conductivity in the electrolyte, faster electrode reaction kinetics, and the lowest OER overpotentials.In this project, the scope of applicability of high-temperature SOECs, which have been optimized for optimum performance under constant load in the past, will be extended to dynamic operating conditions. Problems of accelerated degradation of the air-electrode like delamination and chemical instability of the electro-catalyst materials will be addressed. The development of improved oxygen-conducting solid electrolytes and OER electro-catalyst coatings, as well as the optimization of transient operating conditions will result in the production of refined SOEC cells and stack setups. To meet these objectives, a fundamental understanding of the electrochemical and relevant atomic-scale processes in the bulk phases and at interfaces of the state-of-the-art materials LSM and LSCF, supported on YSZ will be developed. For this we take a holistic approach, linking ab initio theoretical and operando characterization techniques for real-time investigations at the microscopic scale.