Operando Studies of Redox Resilience in ALT Enhanced NiO-YSZ SOFC Anodes

Welander, Martha M.; Zachariasen, Marley S.; Hunt, Clay; Sofie, Stephen W.; Walker, Robert A.

doi:10.1149/2.0531803jes

Cited by 16 publications

(23 citation statements)

References 50 publications

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“…Therefore, care must be taken to ensure mild operation parameters. Dopants could also be added into Ni/YSZ cermet to suppress the Ni oxidation 60 . Third, we concluded that TPB-1 type has higher activity toward HOR than TPB-2 type.…”

Section: Discussionmentioning

confidence: 99%

Atomic structure observations and reaction dynamics simulations on triple phase boundaries in solid-oxide fuel cells

et al. 2019

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The triple phase boundary (TPB) of metal, oxide, and gas phases in the anode of solid oxide fuel cells plays an important role in determining their performance. Here we explore the TPB structures from two aspects: atomic-resolution microscopy observation and reaction dynamics simulation. Experimentally, two distinct structures are found with different contact angles of metal/oxide interfaces, metal surfaces, and pore opening sizes, which have not previously been adopted in simulations. Reaction dynamics simulations are performed using realistic models for the hydrogen oxidation reaction (HOR) at the TPB, based on extensive development of reactive force field parameters. As a result, the activity of different structures towards HOR is clarified, and a higher activity is obtained on the TPB with smaller pore opening size. Three HOR pathways are identified: two types of hydrogen diffusion processes, and one type of oxygen migration process which is a new pathway.

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Section: Discussionmentioning

confidence: 99%

Atomic structure observations and reaction dynamics simulations on triple phase boundaries in solid-oxide fuel cells

et al. 2019

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“…In addition to providing standard Ni-YSZ anodes with improved mechanical strength and electrochemical performance, 36,39 these secondary phases have also been shown to enhance anode resilience to repeated electrochemical redox cycling by a factor of 2 compared to conventional, undoped cermet anodes. 22 Experiments described below expand upon the previous findings by examining how ALT doping improves the anode resilience to environmental redox cycling from direct exposure to H 2 O and O 2 . Previous studies using Sn and Ba doped Ni-YSZ cermet anodes showed that environmental oxidation by steam was self-regulating with a measured OCV of approximately −0.73 V due to the Ni−H 2 O/NiO−H 2 equilibrium.…”

Section: ■ Introductionmentioning

confidence: 80%

“…These two sources of redox stress will impact Ni-YSZ cermet anodes in different ways: electrochemical oxidation from fuel starvation will first affect the electrode−electrolyte interface resulting in delamination and loss of electrocatalytic material. 22,23 Environmental redox cycling is expected to cause a more uniform degradation throughout the anode with the majority of damage visible on the surface of the electrode. These differences are shown schematically in Figure 1.…”

Section: ■ Introductionmentioning

confidence: 99%

Enhancing Ni-YSZ Anode Resilience to Environmental Redox Stress with Aluminum Titanate Secondary Phases

Welander

Zachariasen

Sofie

et al. 2018

ACS Appl. Energy Mater.

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Voltammetry, impedance spectroscopy, and operando vibrational Raman spectroscopy were used to examine the resilience of traditional and modified Ni-based SOFC anodes to environmental reduction/oxidation (redox) cycling. Traditional anodes were fabricated from Ni yttrium stabilized zirconia (YSZ) cermets while modified anodes consisted of the Ni-YSZ cermet containing 4 wt % Al 2 TiO 5 (ALT). Anodes were part of full membrane electrode assemblies that included a YSZ electrolyte support and a LSM cathode. Experiments were performed at 800 °C. To examine anode resilience to redox cycling, cells operated with hydrogen under galvanostatic conditions for 20 min prior to oxidation at OCV using either H 2 O or O 2 . While H 2 O only partially oxidized anodes, O 2 exposure fully oxidized anodes and rapidly accelerated degradation in undoped cells. Undoped cells typically suffered a 50% loss in conversion efficiency after approximately 15−20 redox cycles with O 2 . Under equivalent conditions, cells with ALT doped anodes degraded on average only 13 ± 3%. EIS modeling and ex situ FE-SEM measurements provide further insight into the mechanisms responsible for enhanced resilience shown by Ni-YSZ cermet anodes doped with ALT.

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“…The Ni-BZCY/SDC/ BSCF cell with an interfacial reaction that can be manipulated to form a secondary phase at anode Ni-BZCY and SDC with an electronic conductor to benefit cell performance and power output [35]. The secondary phases nickel aluminate spinel (NiAl 2 O 4 ) and zirconium titanite (Zr 5 Ti 7 O 24 ) formation by infiltrating a small amount of aluminum titanite (ALT, 4 wt%) into the Ni-YSZ anode scaffold were found to suppress Ni coarsening and expand the electrode's TPBs [36,37].…”

Section: Conventional Tpbs Extension In Electrodesmentioning

confidence: 99%

An Overview on the Novel Core-Shell Electrodes for Solid Oxide Fuel Cell (SOFC) Using Polymeric Methodology

2021

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Lowering the interface charge transfer, ohmic and diffusion impedances are the main considerations to achieve an intermediate temperature solid oxide fuel cell (ITSOFC). Those are determined by the electrode materials selection and manipulating the microstructures of electrodes. The composite electrodes are utilized by a variety of mixed and impregnation or infiltration methods to develop an efficient electrocatalytic anode and cathode. The progress of our proposed core-shell structure pre-formed during the preparation of electrode particles compared with functional layer and repeated impregnation by capillary action. The core-shell process possibly prevented the electrocatalysis decrease, hindering and even blocking the fuel gas path through the porous electrode structure due to the serious agglomeration of impregnated particles. A small amount of shell nanoparticles can form a continuous charge transport pathway and increase the electronic and ionic conductivity of the electrode. The triple-phase boundaries (TPBs) area and electrode electrocatalytic activity are then improved. The core-shell anode SLTN-LSBC and cathode BSF-LC configuration of the present report effectively improve the thermal stability by avoiding further sintering and thermomechanical stress due to the thermal expansion coefficient matching with the electrolyte. Only the half-cell consisting of 2.75 μm thickness thin electrolyte iLSBC with pseudo-core-shell anode LST could provide a peak power of 325 mW/cm2 at 700 °C, which is comparable to other reference full cells’ performance at 650 °C. Then, the core-shell electrodes preparation by simple chelating solution and cost-effective one process has a potential enhancement of full cell electrochemical performance. Additionally, it is expected to apply for double ions (H+ and O2−) conducting cells at low temperature.

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Operando Studies of Redox Resilience in ALT Enhanced NiO-YSZ SOFC Anodes

Cited by 16 publications

References 50 publications

Atomic structure observations and reaction dynamics simulations on triple phase boundaries in solid-oxide fuel cells

Atomic structure observations and reaction dynamics simulations on triple phase boundaries in solid-oxide fuel cells

Enhancing Ni-YSZ Anode Resilience to Environmental Redox Stress with Aluminum Titanate Secondary Phases

An Overview on the Novel Core-Shell Electrodes for Solid Oxide Fuel Cell (SOFC) Using Polymeric Methodology

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