Connecting microstructural coarsening processes to electrochemical performance in solid oxide fuel cells: An integrated modeling approach

Abdeljawad, Fadi F.; Völker, Benjamin; Davis, Ryan S.; McMeeking, Robert M.; Haataja, Mikko

doi:10.1016/j.jpowsour.2013.10.121

Cited by 60 publications

(61 citation statements)

References 56 publications

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“…Multiple order parameters can be employed to model the multiple phases of the cermet. Additionally, use of the phase-field method at the mesoscale affords the spatial resolution required to capture the heterogeneous nature of the anode while still accessing the time scales necessary to observe long-term degradation mechanisms [7]. Previous computational studies of SOFC anodes using the phase-field method have displayed results in accordance with experimental observations [17][18][19][20].…”

Section: Introductionmentioning

confidence: 59%

“…Abdeljawad et al [7] have shown using a polycrystalline model for the metallic phase that perturbations induced by thermal grooving assist in the growth of Rayleigh-type instabilities. This effect, along with excess grain boundary energy and a potential interface mobility at grain boundary "pinch-off" sites, may affect the ability of the system to retain contiguity.…”

Section: Discussionmentioning

confidence: 99%

“…As in standard Ginzburg-Landau formalism and utilizing the single-crystal formalism of our recently developed model for SOFC anode systems [7], the total chemical free energy functional is written as:…”

Section: Diffuse-interface Formalismmentioning

confidence: 99%

“…A specific degradation mechanism, which has been observed as a major contributor to performance loss, is the agglomeration and coarsening of Ni particles in the anode [5][6][7]. Due to the high operating temperatures of SOFCs (800-1000°C) required for sufficient ion diffusion through the YSZ electrolyte, the Ni phase coarsens, which reduces both the number of available reaction sites (triple-phase boundary lines) and contiguous paths for electron transport [8].…”

Section: Introductionmentioning

confidence: 99%

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Phase wettability and microstructural evolution in solid oxide fuel cell anode materials

et al. 2014

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Recent experimental and theoretical findings suggest that high-temperature solid oxide fuel cells (SOFCs) often suffer from performance degradation due to coarsening of the metallic-phase particles within the anode. In this study, we explore the feasibility of improving the microstructural stability of SOFC anode materials by tuning the contact angle between the metallic phase and electrolyte particles. To this end, a continuum diffuse-interface model is employed to capture the coarsening behavior of the metallic phase and simulate a range of equilibrium contact angles. The evolution of performance-critical, microstructural features is presented for varying degrees of phase wettability. It is found that both the density of electrochemically active triple-phase regions and contiguity of the electron-conducting phase display undesirable minima near the contact angle of conventional SOFC materials. Our results suggest that tailoring the interfacial properties of the constituent phases could lead to a significant increase in the performance and lifetime of SOFCs.

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Section: Introductionmentioning

confidence: 59%

Section: Discussionmentioning

confidence: 99%

Section: Diffuse-interface Formalismmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Phase wettability and microstructural evolution in solid oxide fuel cell anode materials

et al. 2014

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“…16 It is anticipated that a similar effect can be found in the LSM-YSZ cathode as well. However, such a study is still lacking.…”

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confidence: 79%

Linking Initial Microstructure to ORR Related Property Degradation in SOFC Cathode: A Phase Field Simulation

Lei

Cheng

Wen

2017

J. Electrochem. Soc.

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Microstructure evolution driven by thermal coarsening is an important factor for the loss of oxygen reduction reaction rates in SOFC cathode. In this work, the effect of an initial microstructure on the microstructure evolution in SOFC cathode is investigated using a recently developed phase field model. Specifically, we tune the phase fraction, the average grain size, the standard deviation of the grain size and the grain shape in the initial microstructure, and explore their effect on the evolution of the grain size, the density of triple phase boundary, the specific surface area and the effective conductivity in LSM-YSZ cathodes. It is found that the degradation rate of triple phase boundary density and specific surface area of LSM is lower with less LSM phase fraction (with constant porosity assumed) and greater average grain size, while the degradation rate of effective conductivity can also be tuned by adjusting the standard deviation of grain size distribution and grain aspect ratio. Solid oxide fuel cell (SOFC) is a promising candidate to achieve clean electricity generation with high efficiency.1-5 Using ionic conductor, e.g. yttria stabilized zirconia (YSZ), as electrolyte, and perovskite oxides, e.g. La 1-x Sr x MnO 3 (LSM) or (La, Sr)(Co, Fe)O 3 (LSCF), as cathode material, SOFC usually operates at relatively high temperature, i.e. between 600• C to 1000• C, 1 due to the large activation energy for oxygen ion diffusion 6 and oxygen reduction reaction (ORR).7 This high operating temperature makes SOFC free from noble metal catalyst and highly flexible to a wide range of fuels.8 However, it also makes SOFC vulnerable to degradations caused by, for example, coarsening, secondary phase formation and Cr poisoning, [9][10][11] which limit the long-term stability of SOFC.Coarsening has been found to be one of the degradation mode in LSM-based SOFC cathode above 850• C. 11 The increased polarization resistance after coarsening suggests its impact on the ORR in the cathode. There are two possible pathways for ORR on LSM, i.e. the electrode surface pathway and the bulk pathway. 7,12,13 Due to the small ionic conductivity of LSM, the electrode surface pathway is considered to be dominating in the conventional composite cathode of LSM and YSZ. In this pathway, the oxygen molecule is converted to oxygen intermediates on the LSM surface, diffuses to the triple phase boundary (TPB) through surface diffusion and incorporates into YSZ at TPB. The rate determining step is still under debate, and it might depend on the operational condition and the microstructure. But it is known that both the TPB density and specific surface area (SSA) of LSM can influence the rate of the electrode surface pathway in the SOFC cathode.7,13 Previous experiments and simulations have shown that the coarsening in SOFC electrode leads to the loss of both the TPB density and the SSA of electrode phase, 14-17 which increases the polarization resistance in cathode. In addition, coarsening is known to increase the ohmic resistance in SOFC elect...

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Addressing planar solid oxide cell degradation mechanisms: A critical review of selected components

McPhail

Frangini

Laurencin

et al. 2021

Electrochemical Science Adv

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In this review paper, a critical assessment of the main degradation processes in three key components of solid oxide fuel cells and electrolysers (negative and positive electrodes and the interconnect) is undertaken, attempting prioritization of respective degradation effects and recommendation of the best approaches in their experimental ascertainment and numerical modeling.Besides different approaches to quantifying the degradation rate of an operating solid oxide cell (SOC), the latest advancements in microstructural representation (3D imaging and reconstruction) of SOC electrodes are reviewed, applied to the quantification of triple-phase boundary (TPB) lengths and morphology evolution over time. The intrinsic degradation processes in the negative (fuel)This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

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Connecting microstructural coarsening processes to electrochemical performance in solid oxide fuel cells: An integrated modeling approach

Cited by 60 publications

References 56 publications

Phase wettability and microstructural evolution in solid oxide fuel cell anode materials

Phase wettability and microstructural evolution in solid oxide fuel cell anode materials

Linking Initial Microstructure to ORR Related Property Degradation in SOFC Cathode: A Phase Field Simulation

Addressing planar solid oxide cell degradation mechanisms: A critical review of selected components

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