Fe-substituted SrTiO3−δ–Ce0.9Gd0.1O2 composite anodes for solid oxide fuel cells

Cho, Sungmee; Fowler, Daniel E.; Miller, Erin A.; Cronin, J. Scott; Poeppelmeier, Kenneth R.; Barnett, Scott A.

doi:10.1039/c3ee23791e

Cited by 87 publications

(84 citation statements)

References 33 publications

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“…The better performance for higher Fe content is in line with studies using STF as a cathode material 17 and studies using porous STF-GDC composite anodes. 11 Activation energies extracted from the Arrhenius plots in Figure 6c are below 1 eV in both cases (0.82 eV on STF73 and 0.92 eV on STF37). Such values are in the range of other mixed conducting hydrogen electrode materials, such as ceria, 49,50 but they are very low, compared to the activation energy of O 2 reduction reaction on STF (nearly 2 eV 17 ).…”

Section: Resultsmentioning

confidence: 99%

“…[1][2][3] Some of these materials are chemically stable and mixed conducting also in humidified hydrogen atmosphere, 4 which makes them applicable in SOFC anodes. Several mixed conductors, such as acceptor doped (La,Sr)(Cr,Mn)O 3 , [5][6][7][8] donor-doped SrTiO 3 9,10 and Sr(Ti,Fe)O 3-δ -Ce 0.9 Gd 0.1 O 2-δ (STF-GDC) composites 11 were investigated in form of porous SOFC anodes. Most of these studies revealed moderately low polarization resistances.…”

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confidence: 99%

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The Electrochemical Properties of Sr(Ti,Fe)O_3-δfor Anodes in Solid Oxide Fuel Cells

Nenning

Volgger

Miller

et al. 2017

J. Electrochem. Soc.

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Reduction-stable mixed ionic and electronic conductors such as Sr(Ti,Fe)O 3-δ (STF) are promising materials for application in anodes of solid oxide fuel cells. The defect chemistry of STF and its properties as solid oxide fuel cell (SOFC) cathode have been studied thoroughly, while mechanistic investigations of its electrochemical properties as SOFC anode material are still scarce. In this study, thin film model electrodes of STF with 30% and 70% Fe content were investigated in H 2 +H 2 O atmosphere by electrochemical impedance spectroscopy. Lithographically patterned thin film Pt current collectors were applied on top or beneath the STF thin films to compensate for the low electronic conductivity under reducing conditions. Oxygen exchange resistances, electronic and ionic conductivities and chemical capacitances were quantified and discussed in a defect chemical model. Increasing Fe content increases the electro-catalytic activity of the STF surface as well as the electronic and ionic conductivity. Current collectors on top also increase the electrochemical activity due to a highly active Pt-atmosphere-STF triple phase boundary. Furthermore, the electrochemical activity depends decisively on the H 2 :H 2 O mixing ratio and the polarization. Acceptor-doped mixed ionic and electronic conductors are a promising class of materials for application in solid oxide fuel cell (SOFC) electrodes and they are widely investigated as SOFC cathodes due to their low polarization resistance.1-3 Some of these materials are chemically stable and mixed conducting also in humidified hydrogen atmosphere, 4 which makes them applicable in SOFC anodes. Several mixed conductors, such as acceptor doped (La,Sr)(Cr,Mn)O 3 , [5][6][7][8] donor-doped SrTiO 3 9,10 and Sr(Ti,Fe)O 3-δ -Ce 0.9 Gd 0.1 O 2-δ (STF-GDC) composites 11 were investigated in form of porous SOFC anodes. Most of these studies revealed moderately low polarization resistances. In STF-GDC composites, for example, the anode polarization resistance was <0.2 cm 2 at 800• C, and the overall performance increased with increasing Fe content. However, the usually ill-defined geometry of porous electrodes makes the analysis of specific materials parameters such as electronic and ionic conductivity or oxygen exchange activity very challenging.Thin film model electrodes have well defined and controllable geometry and comparatively simple pathways of electron and oxygen ion migration. This strongly facilitates identification of reaction pathways and quantification of the oxygen exchange activity of the material's surface. [12][13][14][15][16][17][18] Mechanistic studies using thin film model electrodes have so far been performed mainly in oxidizing atmosphere. Thorough studies of the mechanisms of electrochemical oxygen exchange in reducing atmospheres are still largely missing, not only for STF, but for most reduction stable mixed conductors, except for (Gd or Sm) doped ceria [19][20][21][22][23][24] and a study on (La,Sr)FeO 3-δ. 25 The typically low electronic conductivity of accep...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

The Electrochemical Properties of Sr(Ti,Fe)O_3-δfor Anodes in Solid Oxide Fuel Cells

Nenning

Volgger

Miller

et al. 2017

J. Electrochem. Soc.

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“…12 and 27. For chemical capacitances being much larger than the ion blocking capacitor, the analytical expression of the impedance simplifies to (20) The first term in Eq. (20), R eon//ion , refers to the sample resistance relevant for high frequencies R hf and is a parallel connection of the electronic (R eon ) and ionic (R ion ) resistance: (21) The second term corresponds to the analytical expression of a Warburg impedance with resistance R W and fit element T W , i.e.…”

Section: The Role Of the Chemical Capacitance In Miecs With Ion Blockmentioning

confidence: 99%

“…Refs. [17][18][19][20], an additional electron conducting phase might thus be very helpful. A systematic study of the properties of model electrodes with metallic current collec- tors, based on Sr-doped LaFeO 3 and Fe-doped SrTiO 3 thin films under reducing conditions can be found in Refs.…”

Section: Defect Chemistry and Chemical Capacitances Of Polarized Fuelmentioning

confidence: 99%

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The Chemical Capacitance as a Fingerprint of Defect Chemistry in Mixed Conducting Oxides

Schmid¹,

Rupp

Slouka

et al. 2016

ACSi

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The oxygen stoichiometry of mixed conducting oxides depends on the oxygen chemical potential and thus on the oxygen partial pressure in the gas phase. Also voltages may change the local oxygen stoichiometry and the amount to which such changes take place is quantified by the chemical capacitance of the sample. Impedance spectroscopy can be used to probe this chemical capacitance. Impedance measurements on different oxides ((La,Sr)FeO 3-δ = LSF, Sr(Ti,Fe)O 3-δ = STF, and Pb(Zr,Ti)O 3 = PZT) are presented, and demonstrate how the chemical capacitance may affect impedance spectra in different types of electrochemical cells. A quantitative analysis of the spectra is based on generalized equivalent circuits developed for mixed conducting oxides by J. Jamnik and J. Maier. It is discussed how defect chemical information can be deduced from the chemical capacitance.

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Stabilizing Perovskite Structure by Interdiffusional Tailoring and Its Application in Composite Mixed Oxygen‐Ionic and Electronic Conductors

et al. 2017

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Perovskite oxides have been under intense investigation as promising candidates for devices in the field of energy conversion and storage.U nfortunately,t hese perovskites are probably subjected to af requent performance loss caused by phase transition. Aphase-stabilization approach via interdiffusional tailoring is identified in perovskite-based composites.A sa ne xample,aphase-stabilized perovskitefluorite composite material with both components possessing cubic symmetry was obtained by an appropriate one-pot strategy.T hese findings render possible to develop ah ighperformance and extremely stable dual-phase oxygen-transporting membrane for intermediate-temperature air separation as well as syngas production, which also opens up numerous opportunities to overcome the phase-transition-induced performance degradation in other systems.

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Fe-substituted SrTiO3−δ–Ce0.9Gd0.1O2 composite anodes for solid oxide fuel cells

Cited by 87 publications

References 33 publications

The Electrochemical Properties of Sr(Ti,Fe)O_3-δfor Anodes in Solid Oxide Fuel Cells

The Electrochemical Properties of Sr(Ti,Fe)O_3-δfor Anodes in Solid Oxide Fuel Cells

The Chemical Capacitance as a Fingerprint of Defect Chemistry in Mixed Conducting Oxides

Stabilizing Perovskite Structure by Interdiffusional Tailoring and Its Application in Composite Mixed Oxygen‐Ionic and Electronic Conductors

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Fe-substituted SrTiO3−δ–Ce0.9Gd0.1O2 composite anodes for solid oxide fuel cells

Cited by 87 publications

References 33 publications

The Electrochemical Properties of Sr(Ti,Fe)O3-δfor Anodes in Solid Oxide Fuel Cells

The Electrochemical Properties of Sr(Ti,Fe)O3-δfor Anodes in Solid Oxide Fuel Cells

The Chemical Capacitance as a Fingerprint of Defect Chemistry in Mixed Conducting Oxides

Stabilizing Perovskite Structure by Interdiffusional Tailoring and Its Application in Composite Mixed Oxygen‐Ionic and Electronic Conductors

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The Electrochemical Properties of Sr(Ti,Fe)O_3-δfor Anodes in Solid Oxide Fuel Cells

The Electrochemical Properties of Sr(Ti,Fe)O_3-δfor Anodes in Solid Oxide Fuel Cells