Time-dependent performance changes in LSCF-infiltrated SOFC cathodes: The role of nano-particle coarsening

Shah, Megna; Voorhees, Peter W.; Barnett, Scott A.

doi:10.1016/j.ssi.2011.02.003

Cited by 149 publications

(119 citation statements)

References 20 publications

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“…6a), a remarkable R p increase (from 0.8 · cm 2 to 1.03 · cm 2 ) is visible already in the first 72 hours of working time, showing a 29% performance degradation, in accordance with that reported in literature. 12,14,16,88,89 Conversely, the polarization resistance related to the LSM-infiltrated LSCF electrode decreases over time from 0.7 · cm 2 to 0.515 · cm 2 (26% decrease) in 220 hours (continuous spectra in Fig. 6a), confirming a positive effect of the LSM infiltration on the long-term stability of the LSCF electrode.…”

Section: Tga and Tpr Results-inmentioning

confidence: 78%

Infiltration, Overpotential and Ageing Effects on Cathodes for Solid Oxide Fuel Cells: La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δversus Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ

Giuliano

Carpanese

Clematis

et al. 2017

J. Electrochem. Soc.

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The two half-cell systems were compared to evaluate the influence of infiltration, overpotential and ageing on their performance and stability. Structure, microstructure and chemical composition were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with Energy Dispersive X-ray spectroscopy (EDX), whereas redox behavior was evaluated through temperature programmed reduction (TPR) and thermal gravimetric analysis (TGA) in combination with electrochemical impedance spectroscopy (EIS), which was also used to test the electrochemical performance. A decrease of polarization resistance for both infiltrated electrodes, compared to the reference ones, was highlighted at open circuit voltage (OCV), although the BSCF-based cathode was more benefitted more from infiltration than the LSCF-based one. Moreover, the application of cathodic overpotentials (−0.1 to −0.3 V) resulted in opposite effects on the LSCF-and BSCF-based cathodes, highlighting a different response of the oxygen vacancies to the applied voltage for the two perovskite compositions. The positive effect of the LSM layer was further confirmed by the observed improvement in long-term stability of both infiltrated perovskite-type systems. 1 They exhibit mixed ionic and electronic conductivity, with excellent charge and mass transfer properties 2 and high oxygen exchange surface coefficients. 3 Their excellent activity for oxygen reduction has been proved widely. [4][5][6][7][8][9][10] Although the structure and electrochemical processes of LSCF and BSCF are quite different, both of them have long-term stability and redox behavior issues to be clarified, in order to be used as cathode materials in commercial devices. Indeed, when used as cathodes in intermediate-temperatures solid oxide fuel cells (IT-SOFCs), they suffer from chemical and structural instability, which causes degradation during operation time. Moreover, the correlation between their redox behavior under electrochemical operating conditions is still unclear. Many studies have been devoted to investigating LSCF degradation and several causes have been reported, among them: i) mutual cations diffusion between interfaces with consequent atoms depletion and phase separation, [11][12][13][14][15][16] ii) LSCF grain coarsening, 17 iii) reactivity with YSZ-based electrolytes, even with ceria-based barrier layer, 18 iv) impurity contamination, namely Cr from metal interconnects and B from sealing when the cell is inside a stack.19-21 Some recent work performed on an LSCF/CGO (Ce 0.9 Gd 0.1 O 2-δ ) composite cathode on a YSZ electrolyte with a CGO barrier layer 11 affirms that Sr depletion, phase separation and cations inter-diffusion occur mainly during the fabrication process, with negligible contributions during long-term * Electrochemical Society Member.e Present Address: R&D Manufacturing Support Dept., Ansaldo Energia, Via Nicola Lorenzi 8, I-16152 Genoa. z E-mail: carpanese@unige.it operation (973 K). On the other hand, some previous works conversely found that LS...

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Section: Tga and Tpr Results-inmentioning

confidence: 78%

Infiltration, Overpotential and Ageing Effects on Cathodes for Solid Oxide Fuel Cells: La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δversus Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ

Giuliano

Carpanese

Clematis

et al. 2017

J. Electrochem. Soc.

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“…The most commonly used cathode material, lanthanum manganite; LaMnO 3 (LMO) for HT-SOFCs is not practically possible due to its poor catalytic activity and lower ionic conductivity at low temperatures [6]. La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3 (LSCF) perovskite has been reported as cathode material in LTSOFCs but with a low cell performance [7]. Ba x Sr 1-x Co y Fe 1-y O 3-d (BSCF), in particular Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-d has also attracted much attention due to its high conductivity as well as a good catalytic activity and oxygen ions transportation [5].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Ba 0.3 Ca 0.7 Co 0.8 Fe 0.2 O 3-δ composite material as novel catalytic cathode for ceria-carbonate electrolyte fuel cells

Afzal

Raza

et al. 2015

Electrochimica Acta

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Keywords:Composite cathode perovskite oxide BCCF37 low temperature SOFC A B S T R A C T This work reports a new composite Ba x Ca 1-x Co y Fe 1-y O 3-d (BCCF) cathode material for advanced and low temperature solid oxide fuel cells (SOFCs). The BCCF-based composite material was synthesized by sol gel method and investigated as a catalytic cathode for low temperature (LT) SOFCs. XRD analysis of the asprepared material revealed the dominating BCCF perovskite structure as the main phase accompanied with cobalt and calcium oxides as the secondary phases resulting into an overall composite structure. Structure and morphology of the sample was observed by Field Emission Scanning Electron Microscope (FE-SEM). In particular, the Ba 0.3 Ca 0.7 Co 0.8 Fe 0.2 O 3-d (BCCF37) showed a maximum conductivity of 143 S cm À1 in air at 550 C measured by DC 4 probe method. The BCCF at the optimized composition exhibited much higher electrical conductivities than the commercial Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-d (BSCF) perovskite cathode material. A maximum power density of 325 mW cm À2 at 550 C is achieved for the ceria-carbonate electrolyte fuel cell with BCCF37 as the cathode material.

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“…A different approach is the use of composite cathodes where an electrolyte phase is mixed with the cathode material [9,10]. Others have used infiltration techniques to again enhance the oxygen reduction reaction kinetics in the cathode [11,12]. Regardless of the approach used, chemical compatibility and long-term performance need to be better understood to ensure that SOFC systems can compete with existing technologies.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Solid Oxide Fuel Cells with LSCF-SDC Composite Cathodes

DiGiuseppe

Boddapati

2018

Journal of Energy

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This paper reports the study of an anode-supported SOFC cell containing an LSCF-SDC composite cathode. The SOFC cell was tested at different temperatures and reactant flow rates. After testing, the cell was sectioned and characterized using SEM/EDS. Such analysis indicated that no structural damage and no significant interdiffusion of elements among the layers occurred. The measured electrochemical performance data at different temperatures indicate an Arrhenius behavior or temperature activated processes. The low-porosity anode functional layer appears to be very sensitive to low hydrogen contents. The electrochemical performance is also affected by changing air flow rates.

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Time-dependent performance changes in LSCF-infiltrated SOFC cathodes: The role of nano-particle coarsening

Cited by 149 publications

References 20 publications

Infiltration, Overpotential and Ageing Effects on Cathodes for Solid Oxide Fuel Cells: La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δversus Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ

Infiltration, Overpotential and Ageing Effects on Cathodes for Solid Oxide Fuel Cells: La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δversus Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ

Synthesis of Ba 0.3 Ca 0.7 Co 0.8 Fe 0.2 O 3-δ composite material as novel catalytic cathode for ceria-carbonate electrolyte fuel cells

Characterization of Solid Oxide Fuel Cells with LSCF-SDC Composite Cathodes

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Time-dependent performance changes in LSCF-infiltrated SOFC cathodes: The role of nano-particle coarsening

Cited by 149 publications

References 20 publications

Infiltration, Overpotential and Ageing Effects on Cathodes for Solid Oxide Fuel Cells: La0.6Sr0.4Co0.2Fe0.8O3-δversus Ba0.5Sr0.5Co0.8Fe0.2O3-δ

Infiltration, Overpotential and Ageing Effects on Cathodes for Solid Oxide Fuel Cells: La0.6Sr0.4Co0.2Fe0.8O3-δversus Ba0.5Sr0.5Co0.8Fe0.2O3-δ

Synthesis of Ba 0.3 Ca 0.7 Co 0.8 Fe 0.2 O 3-δ composite material as novel catalytic cathode for ceria-carbonate electrolyte fuel cells

Characterization of Solid Oxide Fuel Cells with LSCF-SDC Composite Cathodes

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Infiltration, Overpotential and Ageing Effects on Cathodes for Solid Oxide Fuel Cells: La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δversus Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ

Infiltration, Overpotential and Ageing Effects on Cathodes for Solid Oxide Fuel Cells: La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δversus Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ