Speakers
Description
Solid oxide cells (SOCs) are highly efficient electrochemical devices that convert electrical energy into chemical fuels, offering a versatile solution for energy storage to mitigate the intermittency of renewable energy sources in modern power systems. Operating at elevated temperatures, typically above 600 °C, SOCs benefit from favorable thermodynamic and kinetic efficiencies. However, these high-temperature conditions often induce structural transformations, which can either enhance$^1$ or impair$^2$ the catalytic performance. In this work, we investigate the thermal stability and atomic-scale structure of a model system consisting of lanthanum-strontium manganite (LSM) thin films epitaxially grown on yttria-stabilized zirconia (YSZ) substrates, synthesized via pulsed laser deposition.
Utilizing a comprehensive multi-modal approach that combines advanced electron microscopy, X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and first-principles calculations, we observe that the LSM/YSZ interface, known for facilitating rapid oxide ion diffusion, is characterized by significant distortions in the oxygen and cation lattices. Additionally, the interface exhibits a localized accumulation of oxygen vacancies, which are closely associated with a reduced Mn²⁺ oxidation state to maintain charge balance.
Furthermore, we conducted operando X-ray spectroscopy analysis on a symmetrical SOC cell (LSM/YSZ/LSM) under high-temperature electrochemical conditions in an oxygen atmosphere. The O K-edge XAS spectra reveal distinct changes in O 2p—Mn 3d hybridization under varying oxidizing and reducing potentials. Simultaneously, in-depth operando XPS measurements of La, Sr, and Mn core levels located at the LSM surface, bulk, and interface with YSZ provide insights into elemental redistribution and segregation processes occurring within the film and at the interface.
These results offer an enhanced atomistic understanding of the structure-function relationships in SOCs, providing a foundation for the rational design of optimized interfaces to improve the efficiency and longevity of these systems.
- Türk, H., Schmidt F.-P., Götsch T. et al., Complexions at the Electrolyte/Electrode Interface in Solid Oxide Cells. Adv. Mater. Interfaces 8, 2100967 (2021).
- Türk, H., Götsch T., Schmidt F.-P. et al., Sr Surface Enrichment in Solid Oxide Cells–Approaching the Limits of EDX Analysis by Multivariate Statistical Analysis and Simulations. ChemCatChem 14, e202200300 (2022).
