Preparation and evaluation of doped ceria interlayer on supported stabilized zirconia electrolyte SOFCs by wet ceramic processes

Nguyen, Tuong Lan; Kobayashi, Ken-ichi; Honda, Toshio; Iimura, Youko; Kato, Ken; Neghisi, Akira; Nozaki, Ken; Tappero, Fabrizio; Sasaki, Kazuya; Shirahama, Hiroshi; Ota, Ken‐ichiro; Dokiya, Masayuki; Kato, Tohru

doi:10.1016/j.ssi.2004.06.017

Cited by 129 publications

(80 citation statements)

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“…This solid solution is an insulating layer that has a low ionic conductivity [7,10]. Nguyen et al studied a GDC interlayer between an LSCF cathode and a scandia-stabilized zirconia (ScSZ) electrolyte, which was deposited by screen-printing [17]. Similar to our results, the best electrochemical performance was obtained with a GDC sintering temperature of ∼1200℃, whereas sintering at ∼1300℃ resulted in poor electrochemical performance.…”

Section: Resultssupporting

confidence: 79%

“…The impedance data indicate that this performance improvement was mainly attributed to a decrease in the ohmic resistance (from ∼0.35 to ∼0.16 Ω·cm 2 ). In this case, the ohmic resistive factors, such as (Zr, Ce)O 2 -solid solution and the excess of cobalt GBs were minimized and removed because the GDC was sintered at the lower temperature (∼1100℃) without cobalt oxide [17]. Additionally, the degradation rate became less in the cobalt-free cells.…”

Section: Resultsmentioning

confidence: 99%

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The Effect of Fabrication Conditions for GDC Buffer Layer on Electrochemical Performance of Solid Oxide Fuel Cells

et al. 2013

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Abstract:A Gd-doped ceria (GDC) buffer layer is required between a conventional yttria-stabilized zirconia (YSZ) electrolyte and a La-Sr-Co-Fe-O3 (LSCF) cathode to prevent their chemical reaction. In this study, the effect of varying the conditions for fabricating the GDC buffer layer, such as sintering temperature and amount of sintering aid, on the solid oxide fuel cell (SOFC) performance was investigated. A finer GDC powder (i.e., ultra-high surface area), a higher sintering temperature (∼1290℃), and a larger amount of sintering aid (∼12%) resulted in improved densification of the buffer layer; however, the electrochemical performance of an anode-supported cell containing this GDC buffer layer was poor. These conflicting results are attributed to the formation of (Zr, Ce)O2 and/or excess cobalt grain boundaries (GBs) at higher sintering temperatures with a large amount of sintering aid (i.e., cobalt oxide). A cell comprising of a cobalt-free GDC buffer layer, which was fabricated using a low-temperature process, had lower cell resistance and higher stability. The results indicate that electrochemical performance and stability of SOFCs strongly depend on fabrication conditions for the GDC buffer layer.

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Section: Resultssupporting

confidence: 79%

Section: Resultsmentioning

confidence: 99%

The Effect of Fabrication Conditions for GDC Buffer Layer on Electrochemical Performance of Solid Oxide Fuel Cells

et al. 2013

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“…Interlayers fabricated by other methods such as screen printing, dip coating, tape casting, or spray coating usually contain a certain amount of porosity in the interlayer after subsequent high temperature sintering; the amount of porosity depends heavily on the fabrication conditions. [19][20][21][22] Sintering of the SDC interlayer is performed preferably at temperatures no higher than 1200…”

mentioning

confidence: 99%

SrZrO₃Formation at the Interlayer/Electrolyte Interface during (La_1-xSr_x)_1-δCo_1-yFe_yO₃Cathode Sintering

Darvish

Hardy

et al. 2017

J. Electrochem. Soc.

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This work probes the formation of SrZrO 3 at the SDC/YSZ interface (Sm doped ceria, SDC; Y stabilized zirconia, YSZ) during (La 1-x Sr x ) 1-δ Co 1-y Fe y O 3 (LSCF) cathode sintering. SEM/EDS and grazing incidence X-ray diffraction results of annealed LSCF and YSZ samples reveal that even without physical contact between LSCF and YSZ, SrZrO 3 was formed on the surface of YSZ, preferentially at the grain boundaries. It was suspected that the SrZrO 3 formation is due to the Sr-containing gas species diffused through the pores of the SDC layer and reacted with the YSZ electrolyte. Computational thermodynamics was adopted to predict the gas species formed in air during sintering by using the La-Sr-Co-Fe-O-H thermodynamic database. Sr(OH) 2 is identified as the dominant Sr-containing gas species under the experimental conditions. In addition, it was found that A-site deficiency in LSCF could effectively suppress the SrZrO 3 formation while a dense and pore-free SDC interlayer is required to totally block the SrZrO 3 formation. Cell performance was significantly improved for a cell with a dense SDC interlayer fabricated by pulsed laser deposition, due to elimination of SrZrO 3 formation and therefore reduced interfacial resistance. • C). LSCF materials exhibit electrochemical activity toward oxygen reduction that is superior to Sr-doped LaMnO 3 (LSM), an SOFC cathode material widely used at temperatures above 800• C. 1-8 However, LSCF materials also show higher chemical reactivity with the state-of-the-art electrolyte material, yttria stabilized zirconia (YSZ), than LSM. Reports have shown that LSCF reacts with YSZ to form an insulating La 2 Zr 2 O 7 (LZO) or SrZrO 3 (SZO) layer between the cathode and electrolyte at temperatures as low as 900• C, while LSM essentially does not react with YSZ until 1200• C. 9-16 Therefore, for LSCF to be used as a cathode, an interlayer is necessary between the cathode and electrolyte to prevent these detrimental reactions from occurring during cathode sintering and cell operation. Sm-or Gd-doped ceria (SDC or GDC) is usually used as the interlayer because it is chemically compatible with both the LSCF cathode and the YSZ electrolyte at high temperatures. 2,5,[9][10][11]14 An interlayer of high density is desirable to reduce the ohmic resistance in the interlayer. The sinterability of the SDC interlayer is influenced by several factors, such as the method of fabrication, initial particle size, sintering temperature, etc. Fuel cells with a dense doped ceria interlayer fabricated by either pulsed laser deposition or magnetron sputtering show a pronounced increase in power density. 17,18The significant increase in power density is attributed to decreased ohmic resistance, due to the improved density of the interlayer, better interfacial contact between the SDC and YSZ layers, and decreased insulating reaction products at this interface. Interlayers fabricated by other methods such as screen printing, dip coating, tape casting, or spray coating usually contain a certain amount of porosit...

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“…Figure 3 also exhibits no reaction phases, although Nguyen et al suggested the formation of a ZrO2-Sc2O3-CeO2-Gd2O3 solid solution during heattreatment of GDC/ScSZ laminates at higher temperature. 15) Formation of the (Zr,Ce)O2 phase is undesirable, because of its low ionic conductivity; however no peak shift of the GDC and ScSZ phases was detected after co-sintering these materials fabricated via the wet process. Figure 4 shows the open circuit voltage (OCV) of the LSMsupported microtubular SOFC at various operation temperatures.…”

Section: Jcs-japanmentioning

confidence: 99%

Wet preparation and characterization of ScSZ thin film electrolyte on micro-cathode supports

Yamaguchi¹

2009

J. Ceram. Soc. Japan

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Preparation and evaluation of doped ceria interlayer on supported stabilized zirconia electrolyte SOFCs by wet ceramic processes

Cited by 129 publications

References 14 publications

The Effect of Fabrication Conditions for GDC Buffer Layer on Electrochemical Performance of Solid Oxide Fuel Cells

The Effect of Fabrication Conditions for GDC Buffer Layer on Electrochemical Performance of Solid Oxide Fuel Cells

SrZrO₃Formation at the Interlayer/Electrolyte Interface during (La_1-xSr_x)_1-δCo_1-yFe_yO₃Cathode Sintering

Wet preparation and characterization of ScSZ thin film electrolyte on micro-cathode supports

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Preparation and evaluation of doped ceria interlayer on supported stabilized zirconia electrolyte SOFCs by wet ceramic processes

Cited by 129 publications

References 14 publications

The Effect of Fabrication Conditions for GDC Buffer Layer on Electrochemical Performance of Solid Oxide Fuel Cells

The Effect of Fabrication Conditions for GDC Buffer Layer on Electrochemical Performance of Solid Oxide Fuel Cells

SrZrO3Formation at the Interlayer/Electrolyte Interface during (La1-xSrx)1-δCo1-yFeyO3Cathode Sintering

Wet preparation and characterization of ScSZ thin film electrolyte on micro-cathode supports

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SrZrO₃Formation at the Interlayer/Electrolyte Interface during (La_1-xSr_x)_1-δCo_1-yFe_yO₃Cathode Sintering