Design of experiment approach applied to reducing and oxidizing tolerance of anode supported solid oxide fuel cell. Part II: Electrical, electrochemical and microstructural characterization of tape-cast cells

Faes, Antonin; Wuillemin, Zacharie; Tanasini, Pietro; Accardo, Nicola; Modena, Stefano; Schindler, Hans-Jakob; Cantoni, Marco; Lübbe, H; Diethelm, Stefan; Hessler-Wyser, Aïcha; herle, Jan Van

doi:10.1016/j.jpowsour.2010.11.146

Cited by 27 publications

(15 citation statements)

References 20 publications

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“…The sample conductivity increased by ∼100 times from 23 to 800 °C. A similar phenomenon, in which an Ni size increase caused the electron conducting phase's percolation to increase and resulted in higher electrode conductivity, has been reported before . The cause for the Ni particle size increase was the formation of internal porosity during RedOx cycles.…”

Section: Resultssupporting

confidence: 77%

“…Each sample's initial effective conductivity reached to about 1 × 10 5 S/m. This is relatively higher than values of 1 × 10 4 or 10 to 1000, which has been reported in other literature. These values indicate that the Ni particles were connected and well‐percolating, and that they formed uninterrupted pathways for electronic conduction.…”

Section: Resultscontrasting

confidence: 60%

“…Observations 6 and 7 are more difficult to explain. Note that the intrinsic conductivity of Ni decreases with an increasing temperature; the electric conductivity of Ni at 800 °C is about 1/5 of that at 30 °C Therefore Ni‐YSZ composite's effective conductivity increase should be due to changes in the composite's Ni network microstructure. To explain observations 6 and 7, we propose the following.…”

Section: Resultsmentioning

confidence: 98%

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Evolution of electronic conductivity in a Ni/YSZ electrode fabricated by electrophoretic deposition

Amiri¹,

Hayes²,

Sarkar

2018

Can J Chem Eng

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The conductivity of a tubular micro solid oxide fuel cell (TmSOFC) anode is measured in-situ. The Ni/YSZ composite anode was fabricated using the electrophoretic deposition (EPD) technique. The four-probe method is used to measure the conductivity of several samples simultaneously under a reducing atmosphere during several cycles of heating, $100 h dwelling and cooling periods. Special attention is paid to maintaining similar fabrication and thermal histories among the samples. Despite all this, the measured conductivities show substantial variation and degradation from sample to sample and from one thermal cycle to the next. The most variations occur during the reduction of the cell, with significant oscillations in the measurements. Sample conductivities exhibit step-like changes during the cooling and heat-up cycles. A theory based on thermal expansion induced Ni particles connection formation and breakage within the YSZ backbone is proposed. Sample electron microscope micrographs are presented showing island-like segregated Ni particles within a continuous YSZ structure. Eliminating such effects not only will reduce the cell performance variability but will also increase the peak power by 60 %, according to our simulation results.

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Section: Resultssupporting

confidence: 77%

Section: Resultscontrasting

confidence: 60%

Section: Resultsmentioning

confidence: 98%

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Evolution of electronic conductivity in a Ni/YSZ electrode fabricated by electrophoretic deposition

Amiri¹,

Hayes²,

Sarkar

2018

Can J Chem Eng

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“…Activation by rearranging the Ni/YSZ interfaces can be accomplished by carefully leaving and returning to the thermodynamic stability regime of Ni and YSZ. Oxidizing the Ni to NiO, either by exposure to a high oxygen partial pressure (pO2) gas (such as air) or by high anodic polarisation, followed by reduction back to Ni, leads to a fresh 3PB and enhancement of electrochemical activity 56,57 . This "redox cycle" must be performed at the right conditions and with an appropriate porous electrode microstructure in order to avoid breaking the porous YSZ skeleton by the large Ni-NiO volume change 56 .…”

Section: Passivation and Activation Phenomenamentioning

confidence: 99%

Evolution of the electrochemical interface in high-temperature fuel cells and electrolysers

et al. 2016

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“…These modifications include the variation of Ni content and grain size, introduction of a buffering interlayer, using 3 mol% YSZ for improved mechanical strength and addition of dopants to the structure. 4,5,[12][13][14] Considering the fact that the degradation of Ni-YSZ cermet processed at temperatures above 1300 • C is caused by mechanical stresses associated with the Ni phase, low temperature processing techniques, such as infiltration into pre-sintered porous YSZ skeleton was proposed. 15,16 It was reported that the conductivity of the Ni-YSZ anode prepared by polymeric precursor infiltration method remained nearly unchanged.…”

mentioning

confidence: 99%

Redox Stable Solid Oxide Fuel Cells with Ni-YSZ Cermet Anodes Prepared by Polymeric Precursor Infiltration

Büyükaksoy

Petrovsky

Doğan

2011

J. Electrochem. Soc.

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Redox stable SOFCs with Ni-YSZ cermet anodes were developed for electrolyte supported design (electrolyte thickness: 170 μm). Redox stable Ni-YSZ anode was prepared by infiltrating polymeric NiO precursor into pre-sintered porous YSZ layer (∼10 μm thick) followed by reduction ex situ. Polymeric precursor infiltration technique yielded a Ni-YSZ cermet microstructure with nanosized Ni particles coating the surface of porous YSZ. Low temperature processing of nanostructured Ni-YSZ cermet resulted in the reduction of internal stresses between Ni/NiO coating and YSZ skeleton during the redox cycling process. Electrolyte supported SOFC prepared with Ni-infiltrated anode showed a power density of ∼0.315 Watt.cm −2 and a highly redox stable anode (reduction of power density less than 1% after 15 redox cycles) in humidified forming gas (10%H 2 -90%Ar).Solid oxide fuel cells (SOFCs) are promising energy conversion devices due their high efficiency and fuel flexibility. Typical SOFCs use Ni-YSZ cermet as anode and LSM-YSZ composite as cathode with YSZ (Yttria-Stabilized Zirconia) electrolyte. Ni-YSZ cermet is an attractive anode material due to the fact that it provides low ohmic and polarization resistances at operational temperatures (600-1000 • C). Commonly, Ni-YSZ cermet is prepared by co-sintering a mixture of NiO and YSZ powders at high temperatures (1300-1450 • C), followed by ex situ reduction in fuel (e.g. hydrogen) at 800 • C. 1 During long term operation, it is expected that the SOFC will go through several redox (reduction-oxidation) cycles due to intentional or erroneous interruption of fuel supply. 2 Therefore, it is of great importance that the Ni-YSZ cermet withstands several redox cycles in order for SOFCs to be viable for long term operation. However, the initial performance of the fuel cell is generally not recovered after redox cycling due to the mechanical failure of Ni-YSZ cermet. The internal stresses caused by the expansion of Ni upon oxidation crack the YSZ in the cermet structure. 3-5 This causes a severe degradation in performance and even destruction of the electrolyte in configurations with thin electrolytes. 6,7 One of the approaches to obtain redox stable anodes is replacing Ni with ceramic materials that are redox stable by nature and electronically conductive in reducing atmospheres. 7-11 On the other hand, significant effort was focused on the understanding of the redox behavior of Ni/NiO and the modification of the standard Ni-YSZ cermet accordingly. These modifications include the variation of Ni content and grain size, introduction of a buffering interlayer, using 3 mol% YSZ for improved mechanical strength and addition of dopants to the structure. 4,5,[12][13][14] Considering the fact that the degradation of Ni-YSZ cermet processed at temperatures above 1300 • C is caused by mechanical stresses associated with the Ni phase, low temperature processing techniques, such as infiltration into pre-sintered porous YSZ skeleton was proposed. 15,16 It was reported that the conductivity of the Ni...

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Design of experiment approach applied to reducing and oxidizing tolerance of anode supported solid oxide fuel cell. Part II: Electrical, electrochemical and microstructural characterization of tape-cast cells

Cited by 27 publications

References 20 publications

Evolution of electronic conductivity in a Ni/YSZ electrode fabricated by electrophoretic deposition

Evolution of electronic conductivity in a Ni/YSZ electrode fabricated by electrophoretic deposition

Evolution of the electrochemical interface in high-temperature fuel cells and electrolysers

Redox Stable Solid Oxide Fuel Cells with Ni-YSZ Cermet Anodes Prepared by Polymeric Precursor Infiltration

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