Скачать или смотреть CALPHAD Modelling of Oxide Materials for Energy Conversion and Storage -Ming Chen

Speaker: Ming Chen, Technical University of Denmark at GTT Users' Meeting 2025, held on 4-6 June 2025 in Aachen, Germany
Abstract: CALPHAD modelling of oxide materials for energy conversion and storage
Weiwei Zhang and Ming Chen (Department of Energy Conversion and Storage, Technical University of Denmark)

Solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) are promising technologies for efficient energy conversion and storage, utilizing high-temperature electrochemical reactions. Strontium and iron co-doped lanthanum cobaltites (La1-xSrxCo1-yFeyO3-δ, LSCF) show good oxygen ion and electronic conductivity and fast oxygen surface exchange kinetics at temperatures between 600 and 800 °C, and are considered one of the most promising classes of cathode materials for intermediate-temperature solid oxide fuel cells (SOFCs). Despite its technological importance, the phase stability of the LSCF perovskite has not yet been fully mapped out and may be critical for the long-term operation of these materials. For cells with LSCF or LSCF/CGO (CGO: gadolinia-doped ceria) cathodes, partial decomposition of the perovskite phase has been reported as a potential cause of high degradation rates. Additionally, the LSCF perovskite is susceptible to reactions with gas species such as CO2 and water vapor, present in atmospheric air, or species evaporated from stack components (e.g., chromium- or boron-containing gases), which may compromise stability.

In this work, we present a comprehensive thermodynamic database for the multicomponent La-Sr-Co-Fe-O system, established using the CALPHAD (CALculation of PHAse Diagrams) methodology. The modeling integrates experimental data and theoretical calculations to evaluate the phase stability of LSCF as a function of composition, temperature, and oxygen partial pressure. Special attention is given to the influence of Sr and Co content, as well as reduced oxygen partial pressure, on phase decomposition. The database also facilitates the analysis of LSCF reactivity towards gas impurities, particularly under realistic SOFC operating conditions. Our results show that the stability of the LSCF perovskite phase decreases significantly with high Sr or Co content, elevated temperature, or reduced oxygen partial pressure. The insights obtained from the CALPHAD modeling contribute to a better understanding of the stability limits of LSCF and support the optimization of cathode materials for durable and efficient SOFC applications.