Solid oxide fuel cell cathodes by infiltration of La0.6Sr0.4Co0.2Fe0.8O3−δ into Gd-Doped Ceria

Shah, Megna; Barnett, Scott A.

doi:10.1016/j.ssi.2008.07.002

Cited by 165 publications

(125 citation statements)

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“…In addition to providing more TPB sites, the use of composites is also advantageous for mechanical stability, since it alleviates the problem of thermal expansion coefficient mismatch between the electrolyte and electronic conductor. [13][14][15] Alternative perovskites with mixed ionic and electronic conductivity (MIEC), such as LSF (La 1Àx Sr x FeO 3 ) or LSCF (La 1Àx Sr x Co 1-y Fe y O 3 ) have also been proposed as cathode materials for SOFCs, especially for operation at lower temperatures, 873-1073 K. [16][17][18][19][20][21][22][23][24][25] The ionic conductivity of LSF is significantly higher than that of LSM (8.3 Â 10 À4 S/cm at 973 K), 26 so that oxygen adsorption and reduction do not have to be spatially confined to the TPB sites. 3,15,27 However, the ionic conductivity of MIECs is still much lower than that of the YSZ (1.8 Â 10 À2 S/cm at 973 K).…”

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Effect of the Ionic Conductivity of the Electrolyte in Composite SOFC Cathodes

Vohs

Gorte

2011

J. Electrochem. Soc.

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Solid oxide fuel cell (SOFC) cathodes were prepared by infiltration of 35 wt % La0.8Sr0.2FeO3 (LSF) into porous scaffolds of three, zirconia-based electrolytes in order to determine the effect of the ionic conductivity of the electrolyte material on cathode impedances. The electrolyte scaffolds were 10 mol % Sc2O3-stabilized zirconia (ScSZ), 8 mol % Y2O3-stabilized zirconia (YSZ), and 3 mol % Y2O3- 20 mol % Al2O3-doped zirconia (YAZ), prepared by tape casting with graphite pore formers. Each electrolyte scaffold was 65% porous, with identical pore structures as determined by scanning electron microscopy (SEM). Both symmetric cells and fuel cells were prepared and tested between 873 and 1073 K, using LSF composites that had been calcined to 1123 or 1373 K. Literature values for the electrolyte conductivities were confirmed using the ohmic losses from the impedance spectra. The electrode impedances decreased with increasing electrolyte conductivity, with the dependence being between to the power of 0.5 and 1.0, depending on the operating temperature and LSF calcination temperature.

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Effect of the Ionic Conductivity of the Electrolyte in Composite SOFC Cathodes

Vohs

Gorte

2011

J. Electrochem. Soc.

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“…The collision frequency of LSCFLSCF particles decreased from unity at 0 mass % GDC to 0.115 at 10 mass % GDC; i.e., the conduction paths between LSCF particles was blocked by GDC particles, resulting in the increased resistance. Shah et al 3) also reported that the charge transfer resistance in GDCLCSF cathodes gradually decreases as the amount of LSCF infiltrated into the GDC scaffold increases (from 0.76 to 12.5 vol %). The conductivity of the composite cathode is more sensitive to the infiltration process than to the dry process.…”

Section: ¹mentioning

confidence: 96%

“…A cathode composed of a mixture of GDC and LSCF is expected to exhibit enhanced electrocatalytic activity for the reaction of O 2 and electrons. Shah et al 3) measured the performance of a cathode fabricated by impregnating a porous GDC scaffold with a mixed nitrate solution of LSCF precursor. The formed nanometer-scale (50 nm) LSCF network reduced the charge transfer resistance at an operating temperature of 650°C over 300 h. Liu et al 4) prepared an LSCFGDC composite cathode by impregnating the porous GDC scaffold with a mixed nitrate solution of La, Sr, Co, and Fe and measured the degradation in the composite cathode performance at 750°C in air over 500 h. The GDC scaffold method was effective in expanding the triple-phase boundary (GDC electrolyteLSCF cathodeO 2 gas).…”

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Influence of cathode on electric power of solid oxide fuel cells

Furukawa

Sameshima

Hirata

et al. 2014

J. Ceram. Soc. Japan

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The electric power produced by a Ni/Gd-doped ceria (GDC) anode-supported solid oxide fuel cell with a GDC electrolyte (40¯m thick) and a (La 0.8 Sr 0.2 )(Co 0.8 Fe 0.2 )O 3 (LSCF) cathode using a 3 vol % H 2 O-containing H 2 fuel was measured. The addition of 10 or 50 mass % GDC powder (Ce 0.8 Gd 0.2 O 1.9 ) to the LSCF cathode reduced the power density from 320 mW/cm 2 in the case of no GDC to 137 or 122 mW/cm 2 , respectively. The added GDC particles blocked the conduction path between LSFC particles. The as-prepared LSCF powder was ball-milled using ¡-Al 2 O 3 balls. The milling decreased the charge transfer resistance at the cathode and increased the power density of the fuel cell.©2014 The Ceramic Society of Japan. All rights reserved.Key-words : Solid oxide fuel cell, Cathode, Power density, Overpotential, Gd-doped ceria [Received September 2, 2013; Accepted December 24, 2013] Solid oxide fuel cells (SOFCs) are attractive electric power generators because of their high energy conversion efficiency, their ability to utilize a variety of fuels, the possibility of utilizing their high-temperature exhaust gas, and their leakage-proof property because of the use of solid electrolytes. A conventional SOFC with a yttria-stabilized zirconia (YSZ) electrolyte is typically operated at approximately 800°C to enhance the diffusion of oxide ions formed at its cathode. Gd-doped ceria (GDC) and Sm-doped ceria are also candidate electrolytes for SOFCs because they exhibit greater oxide-ion conductivity than YSZ. Decreasing the charge transfer resistance of electrochemical reactions at the electrodes (especially the cathode) is another strategy to increase the electric power generated by SOFCs. At the cathode, the diffusing oxygen molecules adsorb onto the cathode material and dissociate into oxygen atoms. The oxygen atoms react with electrons to form oxide ions at the triple-phase boundary (TPB, the gascathodeelectrolyte interface). The cathode material is a mixed conductor of electrons and oxide ions. A cathode composed of a mixture of GDC and LSCF is expected to exhibit enhanced electrocatalytic activity for the reaction of O 2 and electrons. Shah et al.3) measured the performance of a cathode fabricated by impregnating a porous GDC scaffold with a mixed nitrate solution of LSCF precursor. The formed nanometer-scale (50 nm) LSCF network reduced the charge transfer resistance at an operating temperature of 650°C over 300 h. Liu et al. 4) prepared an LSCFGDC composite cathode by impregnating the porous GDC scaffold with a mixed nitrate solution of La, Sr, Co, and Fe and measured the degradation in the composite cathode performance at 750°C in air over 500 h. The GDC scaffold method was effective in expanding the triple-phase boundary (GDC electrolyteLSCF cathodeO 2 gas). However, the charge transfer resistance and ohmic resistance increased because of grain growth of the LSCF nanoparticles. The authors suppressed the grain growth of LSCF by adding MgO and LaNi 0.6 Fe 0.4 O 3 particles.In this study, a GDCLSCF mixed cat...

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“…One possible strategy is to mix LSCF with the electrolyte gadolinia-doped ceria (GDC). It is reported that after infiltration with ionic conductive GDC, the microstructure stability, the ionic conductivity, the oxygen reduction activity as well as the adhesion to electrolyte of LSCF cathode could be improved [25][26][27][28][29][30][31]. For instance, the polarization resistance of La0.8Sr0.2Co0.5Fe0.5O3−δ-GDC composite decreased to 1.6 Ω cm 2 at 650 °C [31], and that of La0.6Sr0.4Co0.2Fe0.8O3-δ-GDC, fabricated by impregnation, reached values as low as 0.24 Ω cm 2 at 600 °C.…”

Section: Introductionmentioning

confidence: 99%

“…For instance, the polarization resistance of La0.8Sr0.2Co0.5Fe0.5O3−δ-GDC composite decreased to 1.6 Ω cm 2 at 650 °C [31], and that of La0.6Sr0.4Co0.2Fe0.8O3-δ-GDC, fabricated by impregnation, reached values as low as 0.24 Ω cm 2 at 600 °C. Such improvement was mostly due to the formation of nano-scale (~50 nm) LSCF networks [25].…”

Section: Introductionmentioning

confidence: 99%

B-Site Metal (Pd, Pt, Ag, Cu, Zn, Ni) Promoted La1−xSrxCo1−yFeyO3–δ Perovskite Oxides as Cathodes for IT-SOFCs

Guo

Puleo

et al. 2015

Catalysts

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Perovskite oxides La1−xSrxCo1−yFeyO3-δ (LSCF) have been extensively investigated and developed as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs) due to mixed ionic-electronic conductivity and high electrooxygen reduction activity for oxygen reduction. Recent literature investigations show that cathode performances can be improved by metal surface modification or B-site substitution on LSCF. Although the specific reaction mechanism needs to be further investigated, the promoting effect of metal species in enhancing oxygen surface exchange and oxygen bulk diffusion is well recognized. To our knowledge, no previous reviews dealing with the effect of metal promotion on the cathodic performances of LSCF materials have been reported. In the present review, recent progresses on metal (Pd, Pt, Ag, Cu, Zn, Ni) promotion of LSCF are discussed focusing on two main aspects, the different synthesis approaches used (infiltration, deposition, solid state reaction, one pot citrate method) and the effects of metal promotion on structural properties, oxygen vacancies content and cathodic performances. The novelty of the work lies in the fact that the metal promotion at the B-site is discussed in detail, pointing at the effects produced by two different approaches, the LSCF surface modification by the metal or the metal ion substitution at the B-site of the perovskite. Moreover, for the first time in a review article, the importance of the combined effects of oxygen dissociation rate and interfacial oxygen transfer rate between the metal phase and the cathode phase is addressed for OPEN ACCESSCatalysts 2015, 5 367 metal-promoted LSCF and compared with the un-promoted oxides. Perspectives on new research directions are shortly given in the conclusion.

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Solid oxide fuel cell cathodes by infiltration of La0.6Sr0.4Co0.2Fe0.8O3−δ into Gd-Doped Ceria

Cited by 165 publications

References 10 publications

Effect of the Ionic Conductivity of the Electrolyte in Composite SOFC Cathodes

Effect of the Ionic Conductivity of the Electrolyte in Composite SOFC Cathodes

Influence of cathode on electric power of solid oxide fuel cells

B-Site Metal (Pd, Pt, Ag, Cu, Zn, Ni) Promoted La1−xSrxCo1−yFeyO3–δ Perovskite Oxides as Cathodes for IT-SOFCs

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