001050639 001__ 1050639
001050639 005__ 20260115203947.0
001050639 0247_ $$2doi$$a10.18154/RWTH-2025-01207
001050639 037__ $$aFZJ-2026-00391
001050639 041__ $$aEnglish
001050639 082__ $$a540
001050639 1001_ $$0P:(DE-Juel1)180863$$aWolf, Stephanie$$b0
001050639 245__ $$aInvestigation of solid oxide electrolysis cells’ degradation mechanisms with electrochemical impedance spectroscopy$$f - 2025-01-10
001050639 260__ $$bRWTH Aachen University$$c2025
001050639 300__ $$a130
001050639 3367_ $$2DataCite$$aOutput Types/Dissertation
001050639 3367_ $$2ORCID$$aDISSERTATION
001050639 3367_ $$2BibTeX$$aPHDTHESIS
001050639 3367_ $$02$$2EndNote$$aThesis
001050639 3367_ $$0PUB:(DE-HGF)11$$2PUB:(DE-HGF)$$aDissertation / PhD Thesis$$bphd$$mphd$$s1768468483_3990
001050639 3367_ $$2DRIVER$$adoctoralThesis
001050639 502__ $$aDissertation, RWTH Aachen, 2025$$bDissertation$$cRWTH Aachen$$d2025
001050639 520__ $$aThis work focuses on the analysis of the performance and degradation behavior of Ni-cermet and Ni-free perovskite materials for the fuel gas electrode under steam, CO$_2$, and co-electrolysis conditions. Degradation tests of commercial solid oxide cells with a Ni-8YSZ fuel electrode were carried under a constant current density of $-1$ A $\cdot$ cm$^{-2}$ for 1000 h. Subsequent microstructural analysis showed nickel particle migration and agglomeration at the interface between the active and support layer. These significant microstructural changes led to an increased cell potential during the degradation tests under steam electrolysis conditions. As the main degradation process of Ni-cermet electrodes was identified as Ni depletion, Ni-free Sr$_2$FeMoO$_{6-\delta}$ electrode materials were synthesized and tested. Electron microscopy measurements showed that nanoparticles are dissolved from the SFM perovskite matrix in a hydrogen atmosphere, forming a new perovskite-metal heterointerface that increases the reactive surface area. Conductivity studies showed that Sr$_2$FeMoO$_{6-\delta}$-based materials exhibit higher conductivities in reducing atmospheres than other perovskite materials considered as alternatives to Ni-cermet electrodes. The materials Sr$_2$FeMoO$_{6-\delta}$ (SFM) and Sr$_2$FeMoO$_{6-\delta}$-GDC (SFM-GDC) were electrochemically investigated and achieved higher current densities at 1.5 V than Ni-8YSZ in steam and co-electrolysis, but lower current densities than Ni-GDC. Long-term testing under steam electrolysis conditions showed significantly higher degradation for SFM compared to SFM-GDC, which was attributed to microstructural changes in the SFM electrode. The effect of doping was investigated by synthesizing the double perovskite Sr$_2$FeMo$_\mathrm{0.65}$M$_\mathrm{0.35}$O$_{6-\delta}$ with M = Ti, Co, Cu, Mn, and Ni. B-site doping showed an increased conductivity in oxidizing and reducing atmospheres up to 152 S $\cdot$ cm$^{-1}$ for Sr$_2$FeMo$_\mathrm{0.65}$Cu$_\mathrm{0.35}$O$_{6-\delta}$-GDC due to the exsolution of bimetallic Fe-Cu nanoparticles. The highest current density of all materials studied, compared to Ni-GDC and Ni-8YSZ, was found for Sr$_2$FeMo$_\mathrm{0.65}$Ni$_\mathrm{0.35}$O$_{6-\delta}$ (SFM-Ni). After 500~h under steam electrolysis conditions, however, the SFM-Ni microstructure showed particle agglomeration and electrode densification. To investigate the effect of the fuel gas, SFM-based electrode materials were tested for CO$_2$ electrolysis in an atmosphere of 80% CO$_2$ + 20% CO. The highest current density and very good long-term stability over 1000 h was shown by Sr$_2$FeMo$_\mathrm{0.65}$Ni$_\mathrm{0.35}$O$_{6-\delta}$.
001050639 536__ $$0G:(DE-HGF)POF4-1231$$a1231 - Electrochemistry for Hydrogen (POF4-123)$$cPOF4-123$$fPOF IV$$x0
001050639 536__ $$0G:(DE-Juel1)HITEC-20170406$$aHITEC - Helmholtz Interdisciplinary Doctoral Training in Energy and Climate Research (HITEC) (HITEC-20170406)$$cHITEC-20170406$$x1
001050639 588__ $$aDataset connected to DataCite
001050639 650_7 $$2Other$$aH2
001050639 650_7 $$2Other$$aSOEC
001050639 650_7 $$2Other$$aco-electrolysis
001050639 650_7 $$2Other$$ahydrogen
001050639 650_7 $$2Other$$aimpedance spectroscopy
001050639 650_7 $$2Other$$aperformance analysis
001050639 650_7 $$2Other$$asolid oxide electrolysis
001050639 773__ $$a10.18154/RWTH-2025-01207
001050639 909CO $$ooai:juser.fz-juelich.de:1050639$$pVDB
001050639 9101_ $$0I:(DE-588b)5008462-8$$6P:(DE-Juel1)180863$$aForschungszentrum Jülich$$b0$$kFZJ
001050639 9131_ $$0G:(DE-HGF)POF4-123$$1G:(DE-HGF)POF4-120$$2G:(DE-HGF)POF4-100$$3G:(DE-HGF)POF4$$4G:(DE-HGF)POF$$9G:(DE-HGF)POF4-1231$$aDE-HGF$$bForschungsbereich Energie$$lMaterialien und Technologien für die Energiewende (MTET)$$vChemische Energieträger$$x0
001050639 920__ $$lyes
001050639 9201_ $$0I:(DE-Juel1)IET-1-20110218$$kIET-1$$lGrundlagen der Elektrochemie$$x0
001050639 980__ $$aphd
001050639 980__ $$aVDB
001050639 980__ $$aI:(DE-Juel1)IET-1-20110218
001050639 980__ $$aUNRESTRICTED