Gas Conversion Impedance: A Test Geometry Effect in Characterization of Solid Oxide Fuel Cell Anodes

Primdahl, S.; Mogensen, Mogens Bjerg

doi:10.1149/1.1838654

Cited by 311 publications

(288 citation statements)

References 3 publications

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“…The impedance response from the LSC/CGO oxygen electrode has been approximated by a Gerisher-type response in the CNLS fitting routine in line with the work by Hjelm et al [15]; having a characteristic frequency of 100 Hz. Furthermore; gas diffusion and gas conversion resistance contributions as described by Primdahl and Mogensen have been approximated by two RQ-circuits having characteristic frequencies around 40 Hz and 2 Hz, respectively [30,31]. "Estimated uncertainty for the resistance values obtain via equivalent circuit modeling of IS  ±4 mΩcm2.…”

Section: Electrochemical Impedance Spectroscopy (Eis)mentioning

confidence: 99%

Ni/YSZ electrodes structures optimized for increased electrolysis performance and durability

et al. 2016

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Cermet Ni/YSZ electrodes are the most commonly applied fuel electrode for solid oxide cells (SOC) both when targeting solid oxide fuel cell (SOFC) applications and when used as solid oxide electrolysis cell (SOEC). In this work we report on the correlation between initial Ni/YSZ microstructure and the resulting electrochemical performance both initially and during long-term electrolysis testing at high current density and high p(H2O) inlet. Especially, this work focuses on microstructure optimization to hinder Ni mobility and migration during long-term operation and illustrates the key-role of electrode over-potential on the degradation of the Ni/YSZ electrodes in SOEC. We find that for long-term stability for electrolysis at high current densities and high p(H2O) the as-produced NiO/YSZ precursor electrode should be: 1) As dense as possible, 2) as fine particle and pore sized as possible and 3) the three phases (Ni, YSZ and pore phase) shall be size-matched and welldispersed. Applying such microstructure optimized Ni/YSZ electrode we show SOEC test results with long-term degradation rate as low as 0.3-0.4 %/kh at 1 A/cm 2 , 800 C and inlet gas mixture of p(H2O)/p(H2):90/10. This enables SOEC operation of such cell for more than 5 years below thermo-neutral potential at these operating conditions.

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Section: Electrochemical Impedance Spectroscopy (Eis)mentioning

confidence: 99%

Ni/YSZ electrodes structures optimized for increased electrolysis performance and durability

et al. 2016

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“…The gas conversion resistance (change in Nernst potential) will approximately for fuel utilization lower than 10% and higher than 90% be highly nonlinear and increase drastically. [31][32][33] The consequence is that in particular the peak power density at 750…”

Section: Resultsmentioning

confidence: 99%

“…The tested condition with 20% humidified H 2 as fuel minimizes both the gas diffusion and gas conversion resistances and are at this condition relatively insensitive to small variations. [31][32][33] This is unlike the situations of gas mixtures with either low H 2 or H 2 O. This may explain why these processes seem relatively unaffected upon the microstructural changes.…”

Section: Overall Discussionmentioning

confidence: 98%

Towards High Power Density Metal Supported Solid Oxide Fuel Cell for Mobile Applications

et al. 2017

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For use of metal supported SOFC in mobile applications it is important to reduce the thermal mass to enable fast start up, increase stack power density in terms of weight and volume and reduce costs. In the present study, we report on the effect of reducing the support layer thickness of 313 µm in DTU SoA MS-SOFCs gradually to 108 µm. The support layer thickness decrease in the DTU co-sintering MS-SOFC fabrication route results in an increased densification of the support layer and a slight decrease in performance. To mitigate the performance loss, the introduction of gas channels by puncturing of the green tape casted support layer was explored. In summary, it was successfully demonstrated on stack relevant sized 12 cm x 12 cm MS-SOFCs that the support layer thickness could be significantly reduced and that the cell performance could be significantly increased by the introduction of gas channels.

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“…Kim et al 37 proposed that it could be initiated by the variation in the oxygen nonstoichiometry of the ceramic electrode indicating that the reaction takes place on the two phase boundary rather than at the three phase boundary regions. However, it could originate from the gas phase diffusion 38 or gas conversion 39 as well. In this study the low frequency semicircle only seemed to appear under 0.6 V cell potential and the dependence on the testing time could not be clarified (Figures 7e and 7f).…”

Section: Resultsmentioning

confidence: 99%

Investigation of Time Stability of Sr-Doped Lanthanum Vanadium Oxide Anode and Sr-Doped Lanthanum Cobalt Oxide Cathode Based on Samaria Doped Ceria Electrolyte Using Electrochemical and TOF-SIMS Methods

Tamm

Möller

Nurk

et al. 2016

J. Electrochem. Soc.

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The time stability of solid oxide fuel cell (SOFC) was tested using all ceramic La 0.7 Sr 0.3 VO 3-δ -Ce 0.85 Sm 0.15 O 2-δ (SDC) perovskite material as an alternative anode and La 0.8 Sr 0.2 CoO 3−δ -SDC as a cathode. Both electrodes were prepared using infiltration method. The time stability measurements were carried out for 220 h under 0.6 V cell polarization in H 2 fuel and at working temperatures of 600 • C and 700 • C. At both temperatures, the total polarization resistance, R P , increased in time and the maximal power density values decreased nearly 7% during testing. At the working temperature of 600 • C the R P reached its constant value, 0.50 cm 2 , during the first 12 h of polarization at 0.6 V. At 700 • C noticeable increase in R P was seen within 100 h operation before the constant R P value, 0.50 cm 2 , was established. The microstructure and composition of the single cells, including the mobility of Sr within the cell components, before and after time stability measurements, were analyzed using secondary ion mass spectrometry method. No degradation of cell components and Sr mobility was observed after the cell preparation process and only minor mobility of elements was seen after 24 h of operation at 600 • C and 700 • C. However, noticeable Sr, V, Co and La mobility was observed after 220 h operation at 600 • C and 700 • Solid oxide fuel cells (SOFC) are promising energy conversion systems due to their high electrical efficiency (up to 60%), fuel flexibility and environmental friendliness.1,2 Traditional materials, like Ni-YSZ anode envisaged already four decades ago, continue to dominate as the anode material for SOFC due to the issues and problems associated with the newly discovered materials for SOFC systems, for instance lower electrochemical activity, relatively small thickness of the anode, and unknown degradation and time stability.3-12 However, the main disadvantage of Ni-YSZ anode is severe deactivation in hydrocarbon and hydrocarbon derived synthetic fuels due to the carbon formation/deposition on the Ni surfaces and sulfur poisoning from the impurities of the fuel. [13][14][15][16][17][18][19][20][21][22] In spite of that the carburization and sulfidation stability of the Ni-YSZ electrodes (if using hydrocarbons) have been improved in the recent years through maneuvering of operation conditions. , are considered to be promising alternatives to Ni-cermet anodes. [6][7][8][9][10][11][12]14,15,[22][23][24][25] It has been shown that because of the relatively low catalytic activity, ceramic anodes are much more tolerant toward the carbon deposition and sulfur poisoning than Ni-cermet anodes. 13,26 However, to achieve the reasonable electrochemical activity of the ceramic anodes, the additional catalytic centers, like CeO 2 and Pd, must be deposited into/onto the anode. [6][7][8][9][10]12,22,25 In spite of the active research conducted in the recent decade on the field of alternative ceramic anode materials with perovskite structure, only few studies can be found discussing the degradatio...

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Gas Conversion Impedance: A Test Geometry Effect in Characterization of Solid Oxide Fuel Cell Anodes

Cited by 311 publications

References 3 publications

Ni/YSZ electrodes structures optimized for increased electrolysis performance and durability

Ni/YSZ electrodes structures optimized for increased electrolysis performance and durability

Towards High Power Density Metal Supported Solid Oxide Fuel Cell for Mobile Applications

Investigation of Time Stability of Sr-Doped Lanthanum Vanadium Oxide Anode and Sr-Doped Lanthanum Cobalt Oxide Cathode Based on Samaria Doped Ceria Electrolyte Using Electrochemical and TOF-SIMS Methods

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