Sulfur poisoning of Ni/Gadolinium-doped ceria anodes: A long-term study outlining stable solid oxide fuel cell operation

Riegraf, Matthias; Zekri, Atef; Knipper, Martin; Costa, Rémi; Schiller, Günter; Friedrich, K. Andreas

doi:10.1016/j.jpowsour.2018.01.067

Cited by 35 publications

(33 citation statements)

References 67 publications

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“…Different possible fuel oxidation mechanisms were extensively discussed in our previous work, and the possibility of competitive pathways at double phase and triple phase boundary was pointed out (12,18,19). Thus, it is possible that the change in hydrogen oxidation mechanism is the reason for the different slopes in Figure 4a.…”

Section: Resultsmentioning

confidence: 83%

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Electrochemical Impedance Analysis of Ni/CGO10-Based Electrolyte-Supported Cells

Riegraf¹,

Dierickx²,

Weber³

et al. 2019

ECS Trans.

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To obtain a better understanding of the behavior of Ni/CGO fuel electrodes, this work presents a comprehensive investigation of Ni/CGO10-based electrolyte-supported cells. Commercial Ni/CGO10|CGO10|3YSZ|CGO10|Ni/CGO10-based symmetrical cells were characterized between 550 -975 °C at pH 2 = 0.8 bar and pH 2 O = 0.2 bar and for different H 2 /H 2 O gas mixtures at 550 °C. Small electrode area, thin anodes and large gas flow rates were used to minimize mass transport contributions. The distribution of relaxation times (DRT) is calculated and based on the results, an equivalent circuit model is derived. Electrode process contributions on Ni/CGO were calculated by means of a complex non-linear square fit of the equivalent circuit model to experimental data. One low frequency and one middle frequency electrode process were identified and correlated to a surface and a bulk process, respectively. Apparent activation energy barriers for both processes were derived.

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Section: Resultsmentioning

confidence: 83%

“…Furthermore, the electrodes contain a current collector layer with increased Ni content. Full cells with the same fuel electrode were characterized in detail by means of current-voltage characteristics, electrochemical impedance spectroscopy and scanning electron microscopy (SEM) in our previous publications (12,18,19).…”

Section: Methodsmentioning

confidence: 99%

Electrochemical Impedance Analysis of Ni/CGO10-Based Electrolyte-Supported Cells

Riegraf¹,

Dierickx²,

Weber³

et al. 2019

ECS Trans.

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“…[7] Furthermore, Ni depletion at the fuel electrode/electrolyte interface has also been observed in solid oxide fuel cell operation, possibly driven by a similar mechanism. [6,14,15] Recently, this process was suggested to be driven by potential and humidity gradients. [10] However, the underlying mechanism is still not fully understood.…”

Section: Introductionmentioning

confidence: 99%

“…In the following, several possible mechanisms are discussed. OH) x formation [6,7,10,12,13,15]. According to this theory, a gradient in the activity of volatile Ni(OH) x must be the driving force of such a process.During SOEC operation, steam is reduced to hydrogen at the electrode and therefore conditions are increasingly reducing closer to the electrolyte.…”

mentioning

confidence: 99%

A parameter study of solid oxide electrolysis cell degradation: Microstructural changes of the fuel electrode

Hoerlein

Riegraf

Costa

et al. 2018

Electrochimica Acta

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103

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A parameter study of 20 solid oxide electrolysis cells was carried out to systematically investigate long-term degradation each over 1,000 h under variation of temperature, humidity and current density. The influence of operating temperature was investigated between 750 and 850 °C, the humidity ranged from 40 % to 80 % H 2 O, and the current density varied between open circuit voltage (OCV) and 1.5 A•cm-2. The progress of degradation was monitored insitu by electrochemical impedance spectroscopy. Five different contributions to the spectra were identified by calculating the distribution of relaxation times and separated via a complex non-linear square fitting routine. The present work focuses on the degradation of the fuel electrode. From SEM analysis, Ni depletion and an increased pore fraction close to the electrode/electrolyte interface was derived, which is correlated with an increased ohmic resistance of the cells. This unidirectional transport of Ni away from the fuel electrode/electrolyte interface leads to an effective electrolyte extension and is the main source of degradation. Ni depletion is shown to be driven by current density and its extent is shown to be dependent on the complex interplay between the operating parameters current density, anode overpotential, humidity and temperature. It is particularly pronounced for pH 2 O larger than 0.8 atm and temperatures above 800 °C. Furthermore, the fuel electrode electrochemistry also exhibits degradation in the high-frequency region around 10 4 Hz.

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“…Hybrid materials are interesting and technologically very significant group of materials. They find widespread use in fields such as electrochemical storage and conversion [1][2][3][4][5][6][7][8][9], mechanical [10][11], optical [12], thermal [13] applications. In electrochemical applications such batteries and fuel cells, hybrid materials are composed of one electronically conducting and one ionically conducting (typically Li + , H + or O 2-) component.…”

Section: Introductionmentioning

confidence: 99%

Hybrid MnO/Ni Li-ion Battery Anode Material with Enhanced Capacity Retention

Kunduraci¹

2018

International Journal of Electrochemical Science

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Intimately mixed MnO/Ni hybrid materials are synthesized using a two-step process; Pechini process followed by a high temperature reduction step. As-prepared materials were characterized by X-ray diffraction, transmission electron microscopy and electrochemical tests. (MnO) 1-x /(Ni) x hybrid materials with x=0, 0.2 and 0.5 mole ratios are electrochemically evaluated as anode materials for lithium-ion batteries. The battery tests conclusively show that the coulombic efficiency, capacity utilization factor, percentage capacity retention and high rate performance values of control MnO material are enhanced with the presence of nearby metallic Ni nanoparticles. Oxide/metal hybrid material could be a cheaper alternative to commonly known oxide/graphene system.

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Sulfur poisoning of Ni/Gadolinium-doped ceria anodes: A long-term study outlining stable solid oxide fuel cell operation

Cited by 35 publications

References 67 publications

Electrochemical Impedance Analysis of Ni/CGO10-Based Electrolyte-Supported Cells

Electrochemical Impedance Analysis of Ni/CGO10-Based Electrolyte-Supported Cells

A parameter study of solid oxide electrolysis cell degradation: Microstructural changes of the fuel electrode

Hybrid MnO/Ni Li-ion Battery Anode Material with Enhanced Capacity Retention

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