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MM: Fachverband Metall- und Materialphysik

MM 56: Materials for Storage and Conversion of Energy VI (joint session MM/KFM)

MM 56.4: Talk

Thursday, March 21, 2024, 12:30–12:45, C 264

Can Migrating Ions Block and Deactivate the Active Sites in Solid Oxide Cells? — •Patricia König, Hanna Türk, Thomas Götsch, Franz-Philipp Schmidt, Axel Knop-Gericke, Robert Schlögl, Thomas Lunkenbein, Karsten Reuter, and Christoph Scheurer — Fritz-Haber-Institut der MPG, Berlin

Degradation of the air electrode in electrolysis mode during the oxygen evolution reaction severely limits the commercial adoption of solid oxide cells. Up to now, the atomistic structure of this active catalyst region is essentially unknown, which prevents a detailed analysis of the actual degradation mechanisms.

In prior research, we identified a complexion at the solid/solid interface of the sintered anode [1], featuring partial amorphization and varying elemental distributions deviating from the confining bulk phases. Located around the complexion area, we propose deactivation mechanisms driven by strong cation inter-diffusion. To assess if these cation migrations impede active sites and cell functionality, we conduct a large-scale study on possible active site structural motifs. We sample structures with polarons near oxygen defects, altering ion dopant concentrations to simulate ion migration effects. By employing density-functional theory to compute EELS spectra, we link oxygen defects and their proximity to polarons to distinctive peaks in experimentally recorded EELS spectra. Ultimately, this approach aids in identifying active site structures and deactivation mechanisms, enhancing future cell design with improved efficiency and durability.

[1] H. Tuerk et al., Adv. Mater. Interfaces 8, 2100967 (2021).

Keywords: Solid Oxide Cells; Interface Modelling; DFT; EELS