001050640 001__ 1050640
001050640 005__ 20260115203947.0
001050640 0247_ $$2doi$$a10.18154/RWTH-2025-06190
001050640 037__ $$aFZJ-2026-00392
001050640 041__ $$aEnglish
001050640 1001_ $$0P:(DE-Juel1)180285$$aUnachukwu, Ifeanyichukwu Daniel$$b0
001050640 245__ $$aFuel electrode degradation study for solid oxide electrolysis$$f - 2025-04-11
001050640 260__ $$bRWTH Aachen University$$c2025
001050640 300__ $$a123
001050640 3367_ $$2DataCite$$aOutput Types/Dissertation
001050640 3367_ $$2ORCID$$aDISSERTATION
001050640 3367_ $$2BibTeX$$aPHDTHESIS
001050640 3367_ $$02$$2EndNote$$aThesis
001050640 3367_ $$0PUB:(DE-HGF)11$$2PUB:(DE-HGF)$$aDissertation / PhD Thesis$$bphd$$mphd$$s1768465986_3991
001050640 3367_ $$2DRIVER$$adoctoralThesis
001050640 502__ $$aDissertation, RWTH Aachen, 2025$$bDissertation$$cRWTH Aachen$$d2025
001050640 520__ $$aThe conversion of electrical energy into a chemical energy carrier in the form of hydrogen, carbon monoxide and synthesis gas can be achieved with high efficiency by using the solid oxide electrolysis technology. However, long term degradation issues, especially of the fuel electrode remain a challenge that must be resolved. This thesis therefore investigates the electrochemical performance and degradation behaviour of three different fuel electrodes: gadolinium doped ceria (GDC), Nickel-GDC and Nickel with yttria-stabilized zirconia (Ni-YSZ) under three different electrolysis modes: steam, CO2 and co electrolysis. The fuel electrode material was fabricated on an 8YSZ electrolyte support while the air electrode is made of lanthanum strontium cobalt ferrite (LSCF) with a GDC barrier layer sandwich between the electrolyte and the LSCF. Thus, the cell configuration is represented as Fuel electrode//8YSZ//GDC//LSCF. Their performance and electrochemical processes were investigated by direct and alternating current measurements in the different electrolysis modes in the 750-900 °C temperature range. Distribution of relaxation times (DRT) analysis and non-linear least square method were employed to resolve frequency-dependent electrode processes. The analysis reveals that the GDC fuel electrode is dominated by low-frequency surface exchange processes originating from the double phase boundary sites (DPB), while the Ni-GDC electrodes are dominated by sub-surface mid-frequency processes. For the Ni-YSZ, the underlying processes are dominated by mid/high-frequency processes, mostly from the triple-phase boundary sites (TPB). With regard to the performance, the Ni-GDC single cells exhibited the highest current density across the three electrolysis modes while the GDC and Ni-YSZ showed similar current density in the different electrolysis modes. In the degradation analysis, Ni-YSZ exhibited the highest degradation rate in steam electrolysis followed by Ni-GDC while the GDC showed the least degradation. On the other hand, during CO2 electrolysis, the GDC electrodes showed the highest degradation rate, while Ni-YSZ exhibited a degradation rate slightly higher than those of Ni-GDC. The post-test analysis reveals that GDC particle coarsening and loss of GDC percolation was the major contributor to the degradation rates in the GDC and Ni-GDC single cells. Furthermore, GDC migration and covering of the Ni particles were also seen to contribute to the degradation rates in the Ni-GDC cells. For the Ni-containing cermet of Ni-YSZ and Ni-GDC, Ni migration and agglomeration remain significant contributors to the degradation rate. The degradation processes were observed to be facilitated by an increase in steam partial content.
001050640 536__ $$0G:(DE-HGF)POF4-1231$$a1231 - Electrochemistry for Hydrogen (POF4-123)$$cPOF4-123$$fPOF IV$$x0
001050640 536__ $$0G:(DE-Juel1)HITEC-20170406$$aHITEC - Helmholtz Interdisciplinary Doctoral Training in Energy and Climate Research (HITEC) (HITEC-20170406)$$cHITEC-20170406$$x1
001050640 588__ $$aDataset connected to DataCite
001050640 650_7 $$2Other$$aHochschulschrift
001050640 773__ $$a10.18154/RWTH-2025-06190
001050640 909CO $$ooai:juser.fz-juelich.de:1050640$$pVDB
001050640 9101_ $$0I:(DE-588b)5008462-8$$6P:(DE-Juel1)180285$$aForschungszentrum Jülich$$b0$$kFZJ
001050640 9101_ $$0I:(DE-588b)36225-6$$6P:(DE-Juel1)180285$$aRWTH Aachen$$b0$$kRWTH
001050640 9131_ $$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
001050640 920__ $$lyes
001050640 9201_ $$0I:(DE-Juel1)IET-1-20110218$$kIET-1$$lGrundlagen der Elektrochemie$$x0
001050640 980__ $$aphd
001050640 980__ $$aVDB
001050640 980__ $$aI:(DE-Juel1)IET-1-20110218
001050640 980__ $$aUNRESTRICTED