Cathode–Electrolyte Interfaces with CGO Barrier Layers in SOFC

Knibbe, Ruth; Hjelm, Johan; Menon, Mohan; Pryds, Nini; Søgaard, Martin; Wang, Hsiang Jen; Neufeld, Kai

doi:10.1111/j.1551-2916.2010.03763.x

Cited by 127 publications

(116 citation statements)

References 19 publications

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“…These findings correspond with earlier reports as grain boundary diffusion of Sr in Gd 0.2 Ce 0.8 O 1.9 has been found to be 10 5 times larger than the bulk diffusion and both calculations and experiments has shown grain boundaries as the dominant route for Sr diffusion. [24,27,28] figure 5b forming in the YSZ-CGO interface at the grain boundaries and spreading out along the interface. In figure 4 the density of these grains over the LSCF substrate is so high that when they elongate along the YSZ-CGO interface they come into contact and form a large continuous layer.…”

Section: Variation Of Cgo Barrier Thicknessmentioning

confidence: 99%

“…[21][22][23] An alternative way to fabricate CGO barriers are by physical vapor deposition techniques such as magnetron sputtering, pulsed laser ablation, and electron beam evaporation. [16,20,24] Studies comparing deposition techniques have provided evidence that CGO barrier layers fabricated by reactive magnetron sputtering show better performance. [16,25] This may be associated with higher density of such layers reached at lower temperatures than by wet ceramic deposition techniques.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Strontium Diffusion in Magnetron Sputtered Gadolinia‐Doped Ceria Thin Film Barrier Coatings for Solid Oxide Fuel Cells

Sønderby

Popa

et al. 2013

Advanced Energy Materials

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is prepared to simulate a solid oxide fuel cell. This setup allows observation of Sr diffusion by observing SrZrO 3 formation using X-ray diffraction while annealing. Subsequent electron microscopy confirms the results. This approach presents a simple method for assessing the quality of CGO barriers without the need for a complete fuel cell test setup. CGO films with thicknesses ranging from 250 nm to 1.2 µm are tested at temperatures from 850 °C to 950 °C which yields an in-depth understanding of Sr diffusion through CGO thin films that may be of high scientific and technical interest for implementation of novel fuel cell materials. Sr is found to diffuse along column/grain boundaries in the CGO films but by modifying the film thickness and microstructure the breaking temperature of the barrier can be increased.2 2

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Section: Variation Of Cgo Barrier Thicknessmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Strontium Diffusion in Magnetron Sputtered Gadolinia‐Doped Ceria Thin Film Barrier Coatings for Solid Oxide Fuel Cells

Sønderby

Popa

et al. 2013

Advanced Energy Materials

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“…Therefore, the interlayer cannot completely eliminate SrZrO 3 formation, and the SrZrO 3 is often formed near the ceria/zirconia interface. [5][6][7][8][9][10][11][12][13][14] The amount and distribution of SrZrO 3 formation depends on the heat-treatment temperature of the interlayer. Wankmüller et al reported the influence of the sintering temperature of GDC interlayer on the morphology of SrZrO 3 formation.…”

mentioning

confidence: 99%

“…12,13 Such dispersed SrZrO 3 formation in the GDC interlayer have also been observed by other researchers. [7][8][9][10][11][12][13][14] However, the formation mechanism of such morphology, i.e. why SrZrO 3 formed dispersedly while maintaining the ionic conduction path for oxygen ion, is not yet clear.…”

mentioning

confidence: 99%

Mechanism of SrZrO₃Formation at GDC/YSZ Interface of SOFC Cathode

Chou

Inoue

Kawabata

et al. 2018

J. Electrochem. Soc.

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SrZrO 3 formation at the interface of gadolinia-doped ceria (GDC) interlayer and yttria-stabilized zirconia (YSZ) electrolyte is analyzed using high-resolution electron microscopy. SrZrO 3 is dispersed in the inter-diffusion layer on the GDC side from the Ce/Zr border. Zr, which diffuses into the GDC grain, contributes to the formation of SrZrO 3 . The crystallographic relationship among the SrZrO 3 grains and its neighboring GDC grains reveals that SrZrO 3 is formed at the surface, at the grain boundary, and inside the grain, while maintaining a highly matched boundary with the adjacent GDC grain. The matching of the interface boundary is confirmed by the O-lattice theory, according to which the threshold Zr/Ce ratio is 13/34. If Zr/Ce ratio in the GDC grain is higher than the threshold, SrZrO 3 may significantly grow into the grain. The conduction path for the oxygen ion is retained because the GDC grain containing Zr is split into the SrZrO 3 grain and the less-Zr-containing GDC grain. If Zr/Ce ratio is lower than the threshold, SrZrO 3 may be formed but will be limited by the amount of Zr diffusing from the adjacent region. Thus, the morphology of SrZrO 3 is strongly affected by the state of GDC grains in the inter-diffusion layer. Solid oxide fuel cells (SOFCs) represent a promising technology for converting chemical energy of fuel to electricity with high efficiency, and should find many commercial applications. In the recent developments of SOFCs, lanthanum strontium cobaltite ferrite (La,Sr)(Co,Fe)O 3 (LSCF), with mixed ionic-electronic conductivity, is widely used as the cathode material because it offers high electrochemical performance at intermediate temperatures. Since the most common electrolyte material, i.e. yttria-stabilized zirconia (YSZ), tends to react with LSCF to form highly resistive SrZrO 3 , a thin interlayer consisting of doped ceria, such as gadolinia-doped ceria (GDC), is generally introduced between the LSCF cathode and the electrolyte to prevent solid-state reaction. 1-3 Some manufactures have fabricated an interlayer dense enough to suppress Sr diffusion toward the electrolyte side, which is accompanied by no SrZrO 3 formation. 4 In general, however, the interlayer formed on the YSZ electrolyte by printing and high-temperature sintering becomes porous. Therefore, the interlayer cannot completely eliminate SrZrO 3 formation, and the SrZrO 3 is often formed near the ceria/zirconia interface. [5][6][7][8][9][10][11][12][13][14] The amount and distribution of SrZrO 3 formation depends on the heat-treatment temperature of the interlayer. Wankmüller et al. reported the influence of the sintering temperature of GDC interlayer on the morphology of SrZrO 3 formation. 13 When the sintering temperature of GDC interlayer was 1200 • C, heat-treatment of LSCF cathode at 1080 • C produced a detrimental layer of SrZrO 3 entirely covering the YSZ electrolyte surface. When the sintering temperature of GDC interlayer was higher than 1300 • C, the amount of SrZrO 3 formed decreased and the distributio...

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“…However, it has been reported that in some cases Sr can move through ceriabased electrolyte barrier layer and thus influence noticeably SOFC performance. 27,30,31 Sr mobility inside SDC phase is not widely investigated and more detailed investigation is needed. * Electrochemical Society Member.…”

mentioning

confidence: 99%

Investigation of Time Stability of Sr-Doped Lanthanum Vanadium Oxide Anode and Sr-Doped Lanthanum Cobalt Oxide Cathode Based on Samaria Doped Ceria Electrolyte Using Electrochemical and TOF-SIMS Methods

Tamm

Möller

Nurk

et al. 2016

J. Electrochem. Soc.

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The time stability of solid oxide fuel cell (SOFC) was tested using all ceramic La 0.7 Sr 0.3 VO 3-δ -Ce 0.85 Sm 0.15 O 2-δ (SDC) perovskite material as an alternative anode and La 0.8 Sr 0.2 CoO 3−δ -SDC as a cathode. Both electrodes were prepared using infiltration method. The time stability measurements were carried out for 220 h under 0.6 V cell polarization in H 2 fuel and at working temperatures of 600 • C and 700 • C. At both temperatures, the total polarization resistance, R P , increased in time and the maximal power density values decreased nearly 7% during testing. At the working temperature of 600 • C the R P reached its constant value, 0.50 cm 2 , during the first 12 h of polarization at 0.6 V. At 700 • C noticeable increase in R P was seen within 100 h operation before the constant R P value, 0.50 cm 2 , was established. The microstructure and composition of the single cells, including the mobility of Sr within the cell components, before and after time stability measurements, were analyzed using secondary ion mass spectrometry method. No degradation of cell components and Sr mobility was observed after the cell preparation process and only minor mobility of elements was seen after 24 h of operation at 600 • C and 700 • C. However, noticeable Sr, V, Co and La mobility was observed after 220 h operation at 600 • C and 700 • Solid oxide fuel cells (SOFC) are promising energy conversion systems due to their high electrical efficiency (up to 60%), fuel flexibility and environmental friendliness.1,2 Traditional materials, like Ni-YSZ anode envisaged already four decades ago, continue to dominate as the anode material for SOFC due to the issues and problems associated with the newly discovered materials for SOFC systems, for instance lower electrochemical activity, relatively small thickness of the anode, and unknown degradation and time stability.3-12 However, the main disadvantage of Ni-YSZ anode is severe deactivation in hydrocarbon and hydrocarbon derived synthetic fuels due to the carbon formation/deposition on the Ni surfaces and sulfur poisoning from the impurities of the fuel. [13][14][15][16][17][18][19][20][21][22] In spite of that the carburization and sulfidation stability of the Ni-YSZ electrodes (if using hydrocarbons) have been improved in the recent years through maneuvering of operation conditions. , are considered to be promising alternatives to Ni-cermet anodes. [6][7][8][9][10][11][12]14,15,[22][23][24][25] It has been shown that because of the relatively low catalytic activity, ceramic anodes are much more tolerant toward the carbon deposition and sulfur poisoning than Ni-cermet anodes. 13,26 However, to achieve the reasonable electrochemical activity of the ceramic anodes, the additional catalytic centers, like CeO 2 and Pd, must be deposited into/onto the anode. [6][7][8][9][10]12,22,25 In spite of the active research conducted in the recent decade on the field of alternative ceramic anode materials with perovskite structure, only few studies can be found discussing the degradatio...

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Cathode–Electrolyte Interfaces with CGO Barrier Layers in SOFC

Cited by 127 publications

References 19 publications

Strontium Diffusion in Magnetron Sputtered Gadolinia‐Doped Ceria Thin Film Barrier Coatings for Solid Oxide Fuel Cells

Strontium Diffusion in Magnetron Sputtered Gadolinia‐Doped Ceria Thin Film Barrier Coatings for Solid Oxide Fuel Cells

Mechanism of SrZrO₃Formation at GDC/YSZ Interface of SOFC Cathode

Investigation of Time Stability of Sr-Doped Lanthanum Vanadium Oxide Anode and Sr-Doped Lanthanum Cobalt Oxide Cathode Based on Samaria Doped Ceria Electrolyte Using Electrochemical and TOF-SIMS Methods

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Cathode–Electrolyte Interfaces with CGO Barrier Layers in SOFC

Cited by 127 publications

References 19 publications

Strontium Diffusion in Magnetron Sputtered Gadolinia‐Doped Ceria Thin Film Barrier Coatings for Solid Oxide Fuel Cells

Strontium Diffusion in Magnetron Sputtered Gadolinia‐Doped Ceria Thin Film Barrier Coatings for Solid Oxide Fuel Cells

Mechanism of SrZrO3Formation at GDC/YSZ Interface of SOFC Cathode

Investigation of Time Stability of Sr-Doped Lanthanum Vanadium Oxide Anode and Sr-Doped Lanthanum Cobalt Oxide Cathode Based on Samaria Doped Ceria Electrolyte Using Electrochemical and TOF-SIMS Methods

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Mechanism of SrZrO₃Formation at GDC/YSZ Interface of SOFC Cathode