Ceria-based Cathodes for High Performance Electrolysis Cells

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Wider research context/theoretical framework: H2O and CO2 splitting in high temperature solid oxide electrolysis cells (SOECs) is a highly efficient and promising approach for producing green H2 and CO. Novel ceria-based cathodes have the potential to take SOEC technology a giant step further due to their high electro-catalytic activity, low degradation rates, and low coking susceptibility under CO2 electrolysis. Hence, detailed knowledge on the complex interrelations between electrochemical performance, 3D microstructure, and me-chanical behaviour of ceria-based cathodes is essential. Hypotheses/research questions/objectives: We propose two strategies to achieve the basic knowledge required for fabricating such highest per-forming and long-term stable ceria-based SOEC cathodes. First, we will elaborate a novel processing concept for Ni/Gd-doped CeO2 (GDC) electrodes by redox-induced self-modification, during which the ceria phase partly overgrows the Ni particles. This provides high coking tolerance, mechanical strength and large GDC surface area for high electro-catalytic activity. Second, we will use the mixed ionic/electronic conductivity of GDC in reducing conditions to develop novel SOEC cathodes with single-phase GDC active layer. We will tackle the issue of chemical expansion by doping variations, in-situ expansion measurements, and numerical simulations to gain in-depth understanding of the mechanical behaviour. Approach/methods: To reach our goals we will implement an interdisciplinary working plan with tight cooperation of specialised research groups, who already have noteworthy experience working together in joint pro-jects. The key to success is to understand ceria-based SOEC cathodes down to the atomistic level and to use this knowledge for a targeted design of novel processing routes. We will use model systems for basic material characterization and directly transfer the results to processing of 3D porous ceria cathodes as well as phase field simulations of operating electrodes. 3D microstructure analysis and in-situ electron microscopy will deliver detailed insights into the relevant processes and their interplay. Level of originality/innovation: The high degree of novelty of this proposal arises from the uncommonly large methodological breadth of the contributing groups, which will allow us to understand the behaviour of ceria-based 3D porous SOEC cathodes on the level of elementary properties and atomistic processes of the used materials. We will thus be able to provide the basic understanding for obtaining novel, highest per-forming, long-term stable, and coking resistant ceria-based fuel electrodes, which will push SOEC technology a large step forward.