Development of porous cathode powders for SOFC and influence of cathode structure on the oxygen electroreduction kinetics

Kivi, Indrek; Möller, Priit; Kurig, Heisi; Kallip, Silvar; Nurk, Gunnar; Lust, Enn

doi:10.1016/j.elecom.2008.07.029

Cited by 40 publications

(84 citation statements)

References 9 publications

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“…It has been shown that pore former contents much beyond 2 wt% cause the collapse of the electrical conductivity of an electrode and poor electrochemical performance [36,39]. Also, the use of starting powders with BET specific surface area beyond 135 m 2 /g for preparing the anodes seems highly questionable on the industrial scale, because the long-term stability of the smallest grain powders can be influenced by the grain growth during exploitation (known as Ostwald ripening), associated with degradation of the three-phase-boundary and decrease of the total polarization resistance for the electrode process.…”

Section: Discussionmentioning

confidence: 99%

Statistical method to optimize the medium temperature solid oxide fuel cell electrode materials

Kivi

Lust

Nurk

et al. 2009

Journal of Electroanalytical Chemistry

125

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Section: Discussionmentioning

confidence: 99%

Statistical method to optimize the medium temperature solid oxide fuel cell electrode materials

Kivi

Lust

Nurk

et al. 2009

Journal of Electroanalytical Chemistry

125

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“…Cathode powder was prepared by nitrate solution thermal combustion method using La(N-O 3 ) 3 [41]. Finally the cathode paste was deposited onto a GDC electrolyte pellet by screen printing followed by 5 h sintering at 1110 C with heating and cooling rates of 2.5 K min À1 [42].…”

mentioning

confidence: 99%

Redox dynamics of sulphur with Ni/GDC anode during SOFC operation at mid- and low-range temperatures: An operando S K-edge XANES study

Nurk

Huthwelker

Braun

et al. 2013

Journal of Power Sources

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h i g h l i g h t s g r a p h i c a l a b s t r a c tAn operando SOFC anode S-poisoning XAS experiment at 550 C to 250 C was performed. S K-edge XANES spectral information at Ni/GDC outer surface was collected.Intermediates with different sulphur oxidation states (6þ, 4þ, 0, 2À) were observed. Proportion of oxidation states changed as a function of temperature. Differences between TD calculations and XAS information were observed and discussed. a r t i c l e i n f o a b s t r a c t Sulphur poisoning of nickelebased solid oxide fuel cell (SOFC) anode catalysts is a well-documented shortcoming, but not yet fully understood. Here, a novel experiment is demonstrated to obtain spectroscopic information at operando conditions, in particular the molecular structure of sulphur species in the sulphur K-shell X-ray absorption near edge structure (XANES) region for a SOFC anode under realistic operando conditions, thus, with the flux of O 2À from cathode to anode. Cooling from T ¼ 550 C stepwise down to 250 C, 5 ppm H 2 S/H 2 reacting with Ni-gadolinium doped ceria (GDC) anode resulted in several sulphur species in different oxidation states (6þ, 4þ, 0, À2) and in amounts being at a minimum at high temperature. According to sulphur speciation analysis, the species could either relate to eSO 4 2À or SO 3 (g), eSO 3 2À or SO 2 (g), S 2 (g) or surface-adsorbed S atoms, and, Ni or Ce sulphides, respectively. The coexistence of different sulphur oxidation states as a function of temperature was analysed in the context of thermodynamic equilibrium calculations. Deviations between experimental results and calculations are most likely due to limitations in the speed of some intermediate oxidation steps as well as due to differences between stoichiometric CeO 2 used in calculations and partially reduced Ce 0.9 Gd 0.1 O 2Àd .

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“…Platinum paste (MaTeck) was used to provide good ECS Transactions, 25 (2) 325-333 (2009) electronic conductivity for current collection. For more detailed analysis of the influence of the cathode structure, the three-electrode half cells with identical CGO electrolyte and porous Pt anode, but variable porosity and chemical composition of the cathode were prepared (2). To increase the macro-porosity of the cathode, the additional pore forming agent (PFA) was added into the raw cathode paste.…”

Section: Methodsmentioning

confidence: 99%

Medium Temperature Solid Oxide Fuel Cells Based on the Micro-Meso-Macro-Porous Cathodes and Anodes

et al. 2009

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A series of electrochemical impedance experiments have been carried out in order to investigate the effect of cell chemical composition on the determination of electrochemical characteristics of strontium-doped rare earth cobaltite cathodes. The impedance responses at different electrode potentials of the half-cell and symmetric single-cell setups are compared and analyzed by the equivalent circuit modeling method. The deconvolution of impedance spectra for single cells has been achieved by differential derivative of impedance real part versus ac frequency plot analysis method. The performance of electrolyte-supported Ni/Ce0.9Gd0.1O2-δ|Ce0.9Gd0.1O2-δ|Ln0.6Sr0.4CoO3-δ symmetric single-cells has been optimized for anode diffusion layer porosity, anode functional layer starting powder specific surface area (SBET,powder), and cobaltite-based cathode material composition in a single designed experiment according to the so-called response surface methodology. The combination of electrochemical impedance spectroscopy, equivalent circuit fitting, and mathematical statistics methods proved to be a powerful tool for interpreting solid oxide fuel cell data.

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Development of porous cathode powders for SOFC and influence of cathode structure on the oxygen electroreduction kinetics

Cited by 40 publications

References 9 publications

Statistical method to optimize the medium temperature solid oxide fuel cell electrode materials

Statistical method to optimize the medium temperature solid oxide fuel cell electrode materials

Redox dynamics of sulphur with Ni/GDC anode during SOFC operation at mid- and low-range temperatures: An operando S K-edge XANES study

Medium Temperature Solid Oxide Fuel Cells Based on the Micro-Meso-Macro-Porous Cathodes and Anodes

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