Microelectrode Array for Isolation of Electrode Polarization on Planar Solid Electrolytes

Dunyushkina, L. A.; Lu, Yunxiang; Adler, Stuart B.

doi:10.1149/1.1945729

Cited by 22 publications

(29 citation statements)

References 12 publications

(25 reference statements)

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“…This is likely related to the presence of small defects in the film, which exist even if the film is denser overall. We also observed a reaction between the mask and ceria, which becomes more serious at higher temperatures [7] .…”

Section: A-3 Development Of Insulating Maskmentioning

confidence: 61%

“…A-2(c), pattern B, and the mask and working electrode were assumed to have linear RC characteristics. These calculations showed that a mask resistance of >25 kOhm-cm 2 results in negligible error or distortion of the measured microelectrode impedance [7] .…”

Section: A-3 Development Of Insulating Maskmentioning

confidence: 84%

“…One potential drawback of pattern A is that in the absence of a current collector, we expect the electrical potential to vary along the length of the WE strip unless the electrode has an unusually high electrical conductivity (or is very thick) [7] . Applying an effective current collector to a narrow WE strip presents significant fabrication and measurement challenges.…”

Section: (D) (Left)mentioning

confidence: 99%

“…A common defect observed in single mask layers was an isolated region where the mask becomes too thin and porous, such that the electrode material is able to penetrate the pores of the mask, and make contact to the electrolyte [7] . In practice, we found that two mask layers (printed and fired separately), were required to achieve reproducible mask resistances resistance ≥ 25 kΩ-cm 2 (while a single layer often had much lower resistance, ~5 kΩ-cm 2 , with more manufacturing variability).…”

Section: A-3 Development Of Insulating Maskmentioning

confidence: 99%

“…One consequence is a thicker mask layer (>10 microns), which can interfere with the screenprinting of the electrode ink. Near the edge of the mask, the electrode printing can be wider than the screen pattern and thickened because the mask prevents the electrode screen from sitting flush with the electrolyte surface [7] . In addition, the requirement for two mask layers also requires that the registration (lateral position) of the second layer relative to the first be very accurate (microns), otherwise the second layer will occlude the WE and RE openings in the first layer.…”

Section: A-3 Development Of Insulating Maskmentioning

confidence: 99%

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Advanced Measurement and Modeling Techniques for Improved SOFC Cathodes

Adler¹,

Dunyushkina²,

Huff³

et al. 2006

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The goal of this project was to develop an improved understanding of factors governing performance and degradation of mixed-conducting SOFC cathodes. Two new diagnostic tools were developed to help achieve this goal: 1) microelectrode half-cells for improved isolation of cathode impedance on thin electrolytes, and 2) nonlinear electrochemical impedance spectroscopy (NLEIS), a variant of traditional impedance that allows workers to probe nonlinear rates as a function of frequency. After reporting on the development and efficacy of these tools, this document reports on the use of these and other tools to better understand performance and degradation of cathodes based on the mixed conductor La 1-x Sr x CoO 3-δ (LSC) on gadolinia or samaria-doped ceria (GDC or SDC). We describe the use of NLEIS to measure O 2 exchange on thin-film LSC electrodes, and show that O 2 exchange is most likely governed by dissociative adsorption. We also describe parametric studies of porous LSC electrodes using impedance and NLEIS. Our results suggest that O 2 exchange and ion transport co-limit performance under most relevant conditions, but it is O 2 exchange that is most sensitive to processing, and subject to the greatest degradation and sample-to-sample variation. We recommend further work that focuses on electrodes of well-defined or characterized geometry, and probes the details of surface structure, composition, and impurities. Parallel work on primarily electronic conductors (LSM) would also be of benefit to developers, and to improved understanding of surface vs. bulk diffusion.

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Section: A-3 Development Of Insulating Maskmentioning

confidence: 61%

Section: A-3 Development Of Insulating Maskmentioning

confidence: 84%

Section: (D) (Left)mentioning

confidence: 99%

Section: A-3 Development Of Insulating Maskmentioning

confidence: 99%

Section: A-3 Development Of Insulating Maskmentioning

confidence: 99%

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Advanced Measurement and Modeling Techniques for Improved SOFC Cathodes

Adler¹,

Dunyushkina²,

Huff³

et al. 2006

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Distortions in Electrochemical Impedance Spectroscopy Measurements Using 3‐Electrode Methods in SOFC. I – Effect of Cell Geometry

Cimenti

Birss

et al. 2007

Fuel Cells

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The use of a reference electrode (RE) is necessary to independently measure the overpotential of each electrode in solid oxide fuel cells (SOFC). This type of set‐up, known as the 3‐electrode (or 3‐terminal) configuration, can give erroneous results if the RE does not effectively separate the potential of the two active electrodes. In this work, calculations and experiments were performed to verify the effectiveness of the 3‐electrode configuration used in electrochemical impedance spectroscopy (EIS) measurements for studying the kinetics of anodes and cathodes in SOFC. Initially, a theoretical analysis of the impedance distortions in relation to the electrode geometry and configuration is presented and the main causes of distortions are elucidated. Then, this analysis is corroborated by experimental results obtained using two specially designed cells. Calculations and experiments reconfirm that configurations characterised by electrodes of equal area and symmetrical placement do not produce EIS distortions when the electrodes have similar area‐specific polarisation resistances and time constants. Moreover, distortions can be low even in considerably misaligned configurations when electrodes are small and relatively inactive.

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Distortions in Electrochemical Impedance Spectroscopy Measurements Using 3‐Electrode Methods in SOFC. II. Effect of Electrode Activity and Relaxation Times

2007

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The 3‐electrode configuration is commonly applied to quantify the overpotential of anodes or cathodes in solid‐oxide fuel cells (SOFC). In this type of set‐up, a reference electrode (RE) is used to isolate the potential loss of one electrode from that of the entire cell; however, erroneous results can be obtained whenever the RE does not precisely separate the potential drop between the two active electrodes. In this study, we present the results of a theoretical and experimental analysis focused on verifying the effectiveness of the 3‐electrode configuration in electrochemical impedance spectroscopy measurements for the kinetic characterisation of SOFC electrode reactions. The focus of this paper is on the distortion of impedance measurements caused by differences in the area‐specific polarisation resistance and impedance time constants of the working and counter electrodes. The results obtained numerically and experimentally, both for planar and tubular SOFC cell geometries, prove the reliability of the theoretical model used. From the systematic simulation presented here and in our previous work, it was possible to formulate general guidelines for the design of 3‐electrode experimental SOFC. The theoretical model used here can also be used to verify the consistency of EIS measurements obtained with thin planar cells.

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Microelectrode Array for Isolation of Electrode Polarization on Planar Solid Electrolytes

Cited by 22 publications

References 12 publications

Advanced Measurement and Modeling Techniques for Improved SOFC Cathodes

Advanced Measurement and Modeling Techniques for Improved SOFC Cathodes

Distortions in Electrochemical Impedance Spectroscopy Measurements Using 3‐Electrode Methods in SOFC. I – Effect of Cell Geometry

Distortions in Electrochemical Impedance Spectroscopy Measurements Using 3‐Electrode Methods in SOFC. II. Effect of Electrode Activity and Relaxation Times

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