The Behavior of Silver Cathodes in Solid Electrolyte Fuel Cells

Tannenberger, H.; Siegert, H.

doi:10.1021/ba-1969-0090.ch021

Cited by 18 publications

(26 citation statements)

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“…This also was noted earlier (2,14), and a similar behavior was found for CO2 (1). Yet the curves obtained do not show clear saturation as required by [11]. 9 demonstrate the opposite direction of the oxygen pressure dependencies in the high and low voltage regions by the presence of the cross-over of curves for different oxygen pressures at medium voltages, but Ja in the less pure nitrogen experiment is sufficiently large that correspondence to Eq.…”

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confidence: 77%

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Platinum Electrodes and Calcia-Stabilized Zirconia

Brook

Pelzmann

Kröger³

1971

J. Electrochem. Soc.

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Measurements of the direct current-voltage characteristics of calcia-stabilized zirconia using platinum electrodes of various types have been made to investigate possible electrode processes. Depending on the form of the electrode, the rate-limiting step in the electrical conduction sequence can be (a) ionic conduction by O = in the zirconia, (b) electronic conduction in the zirconia, (c) oxygen atom diffusion through the platinum cathode, (d) the transfer of oxygen from the gas phase into the zirconia at the zirconia-gas interface on the cathode side. The conditions, under which each of these situations exists, are explained in terms of the structure of the electrode.Earlier studies on cells Pt, 02[0.85 ZrO2 9 0.15 CaOIPt, 02 with platinum point electrodes (1), or porous platinum electrodes (2), showed the I-V characteristic to be markedly nonohmic. The rate-controlling step responsible for this behavior was found to be confined to the cathode. Two mechanisms of electrode operation appeared to be important (2). At low voltages (e.g., * Electrochemical Society Active Member.

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confidence: 77%

“…3 it is seen that a saturation plateau for the thickest foil electrode (120~) exists at 1.15 x 10-5A; this means that B has the value 2.57 x 10 -5. [11] plotted with the above values for Rb, pO2(g), and B. 4, the data for the thickest electrode are compared with Eq.…”

Section: B = 2fs-ki [12]mentioning

confidence: 99%

Platinum Electrodes and Calcia-Stabilized Zirconia

Brook

Pelzmann

Kröger³

1971

J. Electrochem. Soc.

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“…The increase in the electrolyte resistance can also be assigned to the reduction in 2-phase and 3-phase contact areas which would add a small constriction resistance to the overall electrolyte resistance [ 16,17].…”

Section: E T C H E D Samplesmentioning

confidence: 99%

Electrochemical behaviour of the surface treated composite-electrolyte/electrode interface

Badwal

1984

J Appl Electrochem

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The effect of surface treatment of the solid electrolyte 50 wt % (4.7 mol % Sc2Oa + 95.3 mo1% ZrO2) + 50 wt % A1203 (used in the SIRO2 low temperature oxygen sensor) on its electrochemical behaviour has been studied by complex impedance spectroscopy. Two techniques, namely, preferential etching of alumina from the surface by a suitable etchant and cosintering of a thin layer of an alumina free electrolyte composition were used. The electrode/electrolyte interfaces prepared by using surface treated electrolyte samples had much lower electrode resistance (by a factor of 3-6) compared with the untreated surfaces. The decrease in the interfacial impedance is attributed mainly to the absence of alumina at the interface (an insulator phase) at which no oxygen exchange reactions could take place.

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“…3,4 For porous electrodes, a discrepancy between the measured ohmic drop and the theoretical ohmic drop was reported for La 1Ϫx Sr x MnO 3 5 and Pt electrodes, 6 and attributed to a constriction of the current as a result of discrete contact points at the electrode/electrolyte interface. Simple and approximate analytical formulas were developed to relate the ohmic resistance to the geometry of the cell.…”

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confidence: 99%

“…ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 134.129.120 3. Downloaded on 2015-05-23 to IP…”

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confidence: 99%

Interpretation of Measured Polarization Resistance at a Solid Electrode/Electrolyte Interface

Svensson

Nisancioḡl̄ū

1999

J. Electrochem. Soc.

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The difficulties in the interpretation of electrochemical data caused by a nonuniform current distribution at the electrode is a well-known problem of electrochemistry, e.g., see Ref. 1 and 2 for reviews. The nonuniform reaction rate may result from the particular cell geometry, including the placement of the reference electrode, from reaction kinetics, mass-transfer limitations, or a combination. Measured quantities such as ohmic and polarization resistance, and other knietic parameters can deviate considerably from their true values based on material and interfacial properties of the cell components. A mathematical model can thus be a useful tool to relate measured quantities to the true properties.In the field of solid-state electrochemistry, a nonlinear dependence of the ohmic resistance on the electrolyte thickness was observed in experiments with Au electrodes partly covering the surface of an yttria-stabilized zirconia (YSZ) electrolyte. 3,4 For porous electrodes, a discrepancy between the measured ohmic drop and the theoretical ohmic drop was reported for La 1Ϫx Sr x MnO 3 5 and Pt electrodes, 6 and attributed to a constriction of the current as a result of discrete contact points at the electrode/electrolyte interface. Simple and approximate analytical formulas were developed to relate the ohmic resistance to the geometry of the cell. 4-6 Furthermore, it is well established that the ac impedance of multicrystalline YSZ electrolyte exhibits an additional semicircle on a Nyquist plot in comparison to a single-crystal electrolyte, 7,8 and this is attributed to constriction of current lines caused by grain boundaries or defects. A rigorous, theoretical treatment of this problem was presented by Fleig and Maier 9,10 for a rectangular element with an electrode much smaller than the dimensions of the cell, under ac conditions. Nagata et al. 11 performed an experimental study of the effect of cell configuration and the position of the reference electrode on the measured potential, using YSZ electrolyte and Pt electrodes. The results were interpreted in terms of intuitive equivalent circuits. Figueiredo et al. 12 investigated two different cell geometries experimentally, with emphasis on the effect of the electrolyte thickness on the measured overpotential at an La 0.9 MnO 3 electrode/YSZ electrolyte interface. The potential distribution in a thin YSZ electrolyte was calculated numerically for a specific cell geometry. 13 Winkler et al. 14 evaluated solid electrolyte cell geometries with respect to possible errors in the determination of the polarization resistance by means of numerical analysis.This study gives a theoretical treatment of current and potential distributions in simple two-dimensional cell geometries representative of typical solid-state cells commonly used in the laboratory for the evaluation of reaction kinetics and properties of cell components. Emphasis is given to problems related to the use of thin electrolytes and the kinetic properties of the counter electrode, relevant for studies of solid...

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The Behavior of Silver Cathodes in Solid Electrolyte Fuel Cells

Cited by 18 publications

References 0 publications

Platinum Electrodes and Calcia-Stabilized Zirconia

Platinum Electrodes and Calcia-Stabilized Zirconia

Electrochemical behaviour of the surface treated composite-electrolyte/electrode interface

Interpretation of Measured Polarization Resistance at a Solid Electrode/Electrolyte Interface

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