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Chan, Siew Hwa; Chen, X.J.; Khor, K.A.

doi:10.1023/a:1012232301349

Cited by 70 publications

(47 citation statements)

References 9 publications

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“…As has been discussed in detail in several previous studies, proper alignment of the cathode and anode and positioning of the reference electrode are required in order to obtain accurate measurements of overpotentials using both current interruption and impedance spectroscopy [9][10][11][12][13]. For a cell with an ideal configuration the magnitude of the initial drop in the reference to cathode current interruption measurement should be equal to that in the reference to anode measurement at the same current density.…”

Section: Resultsmentioning

confidence: 99%

“…The overpotential, A In order to completely separate the anode and cathode processes a well-placed reference electrode is again required. Several recent experimental and theoretical studies have demonstrated the importance of well-designed cell geometry in order to obtain a reference electrode whose potential is pinned near the center of the electrolyte and independent of cell current [9][10][11][12][13]. These studies show that one needs to use a cell with a relatively thick electrolyte, symmetric coaxial placement of the cathode and anode, and placement of the reference electrode at least three electrolyte thicknesses from the edge of one of the electrodes.…”

Section: Cu-ceria-ysz Cermet Anodes For Solid Oxide Fuel Cells (Sofcsmentioning

confidence: 99%

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Measurement of electrode overpotentials for direct hydrocarbon conversion fuel cells

et al. 2004

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Cathodic and anodic overpotentials were measured using current interruption and AC impedance spectroscopy for two separate solid oxide fuel cells (SOFCs). The fuel cells used yttria-stabilized zirconia (YSZ) as the electrolyte, strontium-doped lanthanum manganite (LSM) as the cathode, and a porous YSZ layer impregnated with copper and ceria as the anode. The Cu/CeO 2 /YSZ anode is active for the direct conversion of hydrocarbon fuels. Overpotentials measured using both current interruption and impedance spectroscopy for the fuel cell operating at 700ºC on both hydrogen and n-butane fuels are reported. In addition to providing the first electrode overpotential measurements for direct conversion fuel cells with Cubased anodes the results demonstrate that there may be significant uncertainties in measurements of electrode overpotentials for systems where there is a large difference between the characteristic frequencies of the anode and cathode processes and/or complex electrode kinetics.

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Section: Resultsmentioning

confidence: 99%

Section: Cu-ceria-ysz Cermet Anodes For Solid Oxide Fuel Cells (Sofcsmentioning

confidence: 99%

Measurement of electrode overpotentials for direct hydrocarbon conversion fuel cells

et al. 2004

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“…However, effects due to changes to the design of the SOFCs can be complicated, requiring trial and error to improve the fuel cell. In particular, the specific effects of changing the thickness of the cathode for fuel cell performance can be difficult to determine [3].…”

Section: Introductionmentioning

confidence: 99%

Study of Influence of Electrode Geometry on Impedance Spectroscopy

Ahmed

Reifsnider

2010

ASME 2010 8th International Fuel Cell Science, Engineering and Technology Conference: Volume 2

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Electrochemical Impedance Spectroscopy (EIS) is a powerful and proven tool for analyzing AC impedance response. A conventional three electrode EIS method was used to perform the investigation in the present study. Saturated potassium chloride solution was used as the electrolyte and three different material rods were used as working electrodes. Different configurations of electrode area were exposed to the electrolyte as an active area to investigate electrode geometry effects. Counter to working electrode distance was also altered while keeping the working electrode effective area constant to explore the AC response dependence on the variation of ion travel distance. Some controlled experiments were done to validate the experimental setup and to provide a control condition for comparison with experimental results. A frequency range of 100 mHz to 1 MHz was used for all experiments. In our analysis, we have found a noteworthy influence of electrode geometry on AC impedance response. For all electrodes, impedance decreases with the increase of effective area of the electrolyte. High frequency impedance is not as dependent on geometry as low frequency response. The observed phase shift angle drops in the high frequency region with increased working electrode area, whereas at low frequency the reverse is true. Resistance and capacitive reactance both decrease with an increase of area, but resistance response is more pronounce than reactance. For lower frequencies, small changes in working area produce very distinctive EIS variations. Electrode material as well as geometry was systematically varied in the present study. From these and other studies, we hope to develop a fundamental foundation for understanding specific changes in local geometry in fuel cell (and other) electrodes as a method of designing local morphology for specific performance.

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“…A threeelectrode configuration in EIS allows the measurement of half-cell impedance (anode or cathode) to be carried out. Some studies [21,22] were carried out in a galvanostatic mode with a 5% AC amplitude of the DC current [8,24,25] to obtain a linear response from the system and at frequencies from 10 KHz to 0.3Hz. The high frequency in the EIS measurements was limited due to the bandwidth of the electronic load.…”

Section: Methodsmentioning

confidence: 99%

Study of current distribution and oxygen diffusion in the fuel cell cathode catalyst layer through electrochemical impedance spectroscopy

Cruz-Manzo

Chen

Rama

2013

International Journal of Hydrogen Energy

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In this study, an analysis of the current distribution and oxygen diffusion in the Polymer Electrolyte Fuel Cell (PEFC) Cathode Catalyst Layer (CCL) has been carried out using Electrochemical Impedance Spectroscopy (EIS) measurements. Cathode EIS measurements obtained through a three-electrode configuration in the measurement system are compared with simulated EIS data from a previously-validated numerical model, which subsequently allows the diagnostics of spatio-temporal electrochemical performance of the PEFC cathode. The results show that low frequency EIS measurements commonly related to mass transport limitations are attributed to the low oxygen equilibrium concentration in the CCL-Gas Diffusion Layer (GDL) interface and the low diffusivity of oxygen through the CCL.Once the electrochemical and diffusion mechanisms of the CCL are calculated from the EIS measurements, a further analysis of the current density and oxygen concentration distributions through the CCL thickness is carried out. The results show that high ionic resistance within the CCL electrolyte skews the current distribution towards the membrane interface. Therefore the same average current density has to be provided by few catalyst sites near the membrane. The increase in ionic resistance results in a poor catalyst utilization through the CCL thickness. The results also show that non-steady oxygen diffusion in the CCL allows equilibrium to be established between the equilibrium oxygen concentration supplied at the GDL boundary and the surface concentration of the oxygen within the CCL. Overall, the study newly demonstrates that the developed technique can be applied to estimate the factors that influence the nature of polarization curves and to reveal the effect of kinetic, ohmic and mass transport mechanisms on current distribution through the thickness of the CCL from experimental EIS measurements.

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Cited by 70 publications

References 9 publications

Measurement of electrode overpotentials for direct hydrocarbon conversion fuel cells

Measurement of electrode overpotentials for direct hydrocarbon conversion fuel cells

Study of Influence of Electrode Geometry on Impedance Spectroscopy

Study of current distribution and oxygen diffusion in the fuel cell cathode catalyst layer through electrochemical impedance spectroscopy

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