Thermal analysis of the cyclic reduction and oxidation behaviour of SOFC anodes

Waldbillig, D.; Wood, Anthony; Ivey, Douglas G.

doi:10.1016/j.ssi.2004.12.002

Cited by 189 publications

(165 citation statements)

References 19 publications

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“…As will be evident from an upcoming paper on thermal analysis and also as reported in Ref. 8, these times were possibly insufficient for full oxidation or reduction.…”

Section: Resultsmentioning

confidence: 91%

Dimensional Behavior of Ni–YSZ Composites during Redox Cycling

Pihlatie

Kaiser

Larsen

et al. 2009

J. Electrochem. Soc.

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The dimensional behavior of Ni–yttria-stabilized zirconia (YSZ) cermets during redox cycling was tested in dilatometry within the temperature range 600–1000°C . The effect of humidity on redox stability was investigated at intermediate and low temperatures. We show that both the sintering of nickel depending on temperature of the initial reduction and the operating conditions, and the temperature of reoxidation are very important for the size of the dimensional change. Cumulative redox strain (CRS) is shown to be correlated with temperature. Measured maximum CRS after three redox cycles varies within 0.25–3.2% dL/L in dry gas and respective temperature range of 600–1000°C . A high degree of redox reversibility was reached at low temperature, however, reversibility is lost at elevated temperatures. We found that at 850°C , 6% steam and a very high pnormalH2O∕pnormalH2 ratio is detrimental for redox stability, whereas at 600°C no negative effect was observed. Pre-reduction at 1100 instead of 800°C more than doubled redox strain on reoxidation at 800°C . For samples similarly pre-reduced at 1000°C , lowering the reoxidation temperature from 1000to750°C or below reduces the redox strain to less than half.

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“…As will be evident from an upcoming paper on thermal analysis and also as reported in Ref. 8, these times were possibly insufficient for full oxidation or reduction.…”

Section: Resultsmentioning

confidence: 91%

Dimensional Behavior of Ni–YSZ Composites during Redox Cycling

Pihlatie

Kaiser

Larsen

et al. 2009

J. Electrochem. Soc.

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“…On the other hand, it was 40:60 in Composite_2 (note that the common ratio of NiO and YSZ as anode is from 4:6 to 6:4). 18), 19) Thus, the composite modified by PVP has more optimal distribution in addition to nanoporous morphology for the anode material of LT-SOFC. It is supported by electrochemical characteristics of the symmetric cells with the synthesized composites.…”

Section: Resultsmentioning

confidence: 99%

High-electrochemical performance of a highly dispersed nanoporous nanocomposite Ni-YSZ

Park

Choa

Jung

et al. 2012

J. Ceram. Soc. Japan

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“…During this first reduction, the microstructure of the anode changes when nickel oxide is reduced to metallic nickel and the porosity increases. No contraction of the anode is observed for a fine structured anode [22]. If the reduced cell is exposed to an oxidative atmosphere, reoxidation and a small expansion (on the order or 1%) occur [22].…”

Section: Model For Anode Reoxidation Riskmentioning

confidence: 95%

“…No contraction of the anode is observed for a fine structured anode [22]. If the reduced cell is exposed to an oxidative atmosphere, reoxidation and a small expansion (on the order or 1%) occur [22]. This expansion can create cracks in the electrolyte, in the complete cell, and lead to cell failure [23,22].…”

Section: Model For Anode Reoxidation Riskmentioning

confidence: 99%

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Simulation of SOFC stack and repeat elements including interconnect degradation and anode reoxidation risk

Larrain

herle

Favrat

2006

Journal of Power Sources

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Reliability of SOFC stacks is a complex and key issue. This paper presents a simulation study including some degradation processes, namely interconnect degradation and the anode reoxidation potential. Quantification for these phenomena has been included in a repeat element model to simulate stack degradation and study the influence of design and operating parameters on the degradation.Interconnect degradation is based on Wagner's law for oxide scale growth, parameters applying to metallic interconnects used in planar SOFCs are used. Anode reoxidation is modeled by thermodynamic equilibrium which allows identification of the operating conditions where the anode is likely to be reoxidized.Simulations have been carried out for a large number of cases at different current density, fuel utilization and furnace temperature, for two different stack designs (base case and modified design). Using an appropriate criterion to express degradation, all these cases point to a clear trade-off between interconnect degradation and local temperature. The base case design is likely to be exposed to anode reoxidation.

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Thermal analysis of the cyclic reduction and oxidation behaviour of SOFC anodes

Cited by 189 publications

References 19 publications

Dimensional Behavior of Ni–YSZ Composites during Redox Cycling

Dimensional Behavior of Ni–YSZ Composites during Redox Cycling

High-electrochemical performance of a highly dispersed nanoporous nanocomposite Ni-YSZ

Simulation of SOFC stack and repeat elements including interconnect degradation and anode reoxidation risk

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