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  • The Electrochemical Society  (25)
  • 2020-2024  (25)
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  • The Electrochemical Society  (25)
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  • 2020-2024  (25)
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  • 1
    Online Resource
    Online Resource
    Numerical Modeling for LSCF Electrodes with Nanocatalyst Infiltration
    The Electrochemical Society ; 2023
    In:  ECS Meeting Abstracts Vol. MA2023-01, No. 54 ( 2023-08-28), p. 118-118
    Details
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2023-01, No. 54 ( 2023-08-28), p. 118-118
    Abstract: As a mixed ionic-electronic conducting (MIEC) material, lanthanum strontium cobalt ferrite (LSCF) is widely used for solid oxide cells (SOCs) in both fuel cell mode and electrolysis mode. The performance and stability of LSCF electrodes can be further enhanced by nanocatalyst infiltration. In this study, a numerical model is developed to investigate the performance of LSCF electrodes modified with infiltrated nanocatalysts. The multiphysics model describes the chemical/electrochemical reactions, charge conservation, and species transport within a SOC button cell. The electrochemical reactions are represented by Butler-Volmer type expressions which couples the physical processes of the cell. The microstructural properties are estimated from experimental imaging to improve the accuracy of the study. The changes of microstructural properties and reaction mechanisms due to nanocatalyst infiltration are also implemented to investigate the effects of infiltrated lanthanum strontium cobaltate (LSC) nanoparticles. The numerical model is first calibrated by adjusting model parameters for good agreement between simulated performance and experimental datasets for a referenced cell. Then the calibrated model is utilized to predict the polarization curves and impedance behavior for backbones with different grain sizes and composition volume fractions. The simulated results for both baseline backbones and infiltrated backbones are also thoroughly analyzed to extract the changes of different physical processes due to the nanocatalyst infiltration. The comparison of performance changes among the backbones under this study provides guidance about the optimum backbone for nanoparticle infiltration technology.
    Type of Medium: Online Resource
    ISSN: 2151-2043
    URL: Article
    DOI: 10.1149/MA2023-0154118mtgabs
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2023
    detail.hit.zdb_id: 2438749-6
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  • 2
    Online Resource
    Online Resource
    Optimization of SOFC Electrode Microstructures with Long Term Performance Modeling and Machine Learning
    The Electrochemical Society ; 2021
    In:  ECS Meeting Abstracts Vol. MA2021-03, No. 1 ( 2021-07-23), p. 166-166
    Details
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2021-03, No. 1 ( 2021-07-23), p. 166-166
    Abstract: Performance degradation over time is a major barrier to the commercialization of solid oxide fuel cells (SOFCs). A major driver of this degradation is grain coarsening in the 3D microstructure of the porous, composite electrodes. The rate and extent of this microstructural degradation depends on the initial microstructure itself, raising the question of whether an optimal electrode microstructure can be determined for long-term performance. The high dimensionality of parameters that determine the initial microstructure makes parametric optimization challenging. In this work, we present a fully resolved 4D model for simulating microstructural and performance changes over 1,000 hours of cell operation by combining a phase-field coarsening model with spatially resolved microstructural analysis and continuum-level multiphysics performance modeling. The integrated model framework was run in a highly parallelized fashion to simulate the long-term performance of hundreds of LSM-YSZ cathodes and Ni-YSZ anodes. These electrode microstructures were synthetically generated to intentionally span 11 independent initial microstructural parameters. The results of the long-term performance model included electrochemical performance every 100 hours throughout the entire 1,000 hours of operation. Together with a novel figure of merit that accounts for both the initial and long-term performance, this high-dimensional bank of results was used to train a machine learning regression model. The machine learning model was trained to predict the long term performance based on the 11 independent initial microstructural parameters, allowing interpolation to values not included in the fully resolved models, as well as a more robust analysis of each parameter’s influence in this highly dimensional parameter space. A SHAP analysis [1] was performed on the trained machine learning model to determine the relative impact of each of the 11 independent initial microstructural parameters. This demonstrated that, for example, the LSM/YSZ ratio was the most impactful parameter in the cathode microstructure, with lower LSM/YSZ ratios generally leading to more energy produced over the cell’s lifetime. The fully trained model and SHAP analysis are also able to make specific recommendations for changes that would improve existing electrodes, providing a valuable tool for SOFC electrode developers and manufacturers. [1] S. M. Lundberg, S-I. Lee. A Unified Approach to Interpreting Model Predictions. NIPS 2017. Figure 1
    Type of Medium: Online Resource
    ISSN: 2151-2043
    URL: Article
    DOI: 10.1149/MA2021-031166mtgabs
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2021
    detail.hit.zdb_id: 2438749-6
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  • 3
    Online Resource
    Online Resource
    Multiphysics Simulation for the Performance of Tubular Solid Oxide Fuel Cells Operated on Coal Syngas
    The Electrochemical Society ; 2023
    In:  ECS Meeting Abstracts Vol. MA2023-01, No. 54 ( 2023-08-28), p. 178-178
    Details
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2023-01, No. 54 ( 2023-08-28), p. 178-178
    Abstract: Solid oxide fuel cells (SOFCs) can be operated directly on coal syngas, but the various contaminants in coal syngas affect the performance and durability of the device. In the present study, three-dimensional multiphysics simulations were developed to investigate the performance degradation of tubular SOFCs operated on coal syngas. The numerical model includes charge conservation, species transport within the electrodes and the channels, and heat transfer within the device. These physical processes are coupled by the chemical/electrochemical reactions, which are represented by a Butler-Volmer type formula. Based on the thermodynamic database about impurities interaction with the Ni-YSZ composite anode, the contaminants are assumed to be adsorbed on the anode surface and form secondary phases. These formed phases affect the microstructural properties, electrical conductivity, and the number of active sites available for electrochemical reactions (i.e., hydrogen and carbon monoxide oxidation). During the cell operation, the contaminants diffuse from the fuel channel/anode interface to the anode/electrolyte interface, causing further irreversible degradation. The in-house developed multiphysics simulation is designed to be robust for prediction of interaction between anode materials with different types of contaminants (e.g., PH 3 , H 2 S, H 2 Se, AsH 3 , and user-defined). With the model parameters calibrated in the previous study, the performance of the tubular SOFCs with different levels/types of contaminants is predicted. The tolerance limits of the SOFC cell on single and multiple contaminants are also predicted with the simulations. Furthermore, the degradation resulted from Ni coarsening and redistribution, are also implemented into the model to mimic the performance of realistic SOFCs operating on coal syngas. The performance degradation investigation in this study provides guidance for experimental testing with syngas exposure, which is eventually beneficial to the cost reduction of the coal syngas clean-up technology.
    Type of Medium: Online Resource
    ISSN: 2151-2043
    URL: Article
    DOI: 10.1149/MA2023-0154178mtgabs
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2023
    detail.hit.zdb_id: 2438749-6
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  • 4
    Online Resource
    Online Resource
    Modeling the Distribution of Oxygen Partial Pressure in the Electrolyte of Solid Oxide Cells and Its Implication on Microstructure Evolution in the Hydrogen Electrode
    The Electrochemical Society ; 2023
    In:  ECS Meeting Abstracts Vol. MA2023-01, No. 54 ( 2023-08-28), p. 148-148
    Details
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2023-01, No. 54 ( 2023-08-28), p. 148-148
    Abstract: The distribution of oxygen partial pressure in the electrolyte has an important effect on the stability of solid oxide cells (SOCs). It is well known that the high oxygen partial pressure at the oxygen electrode and electrolyte interface causes delamination, while its effect in the hydrogen electrode (HE) has received comparatively little attention. The only existing model for the distribution of oxygen partial pressure in the electrolyte of SOC is proposed by Virkar et al., which is a one-dimensional model that does not consider the Butler-Volmer equation at triple phase boundary (TPB) nor the microstructure’s effect. In this work, the Virkar’s model was extended to three dimensions and the Butler-Volmer equation was added at TPB to investigate the distribution of oxygen partial pressure in the actual electrode microstructure. The oxygen partial pressure in the YSZ phase of HE near the HE-electrolyte interface was found to be significantly greater than the oxygen partial pressure in the pore phase of HE, which may lead to Ni oxidation. Furthermore, a phase field model was employed to simulate the microstructural evolution of Ni particles on YSZ surfaces with the assumption that NiO forms at the Ni-YSZ interface. The NiO formation affects the microstructure evolution in HE by changing the shape of the Ni particles.
    Type of Medium: Online Resource
    ISSN: 2151-2043
    URL: Article
    DOI: 10.1149/MA2023-0154148mtgabs
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2023
    detail.hit.zdb_id: 2438749-6
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  • 5
    Online Resource
    Online Resource
    Optimization of Extrinsic Impact Factors for Improving Performance and Mitigating Performance Degradation of LSCF-SDC/YSZ/Ni-YSZ Cells Under Solid Oxide Electrolysis Operation
    The Electrochemical Society ; 2023
    In:  ECS Meeting Abstracts Vol. MA2023-01, No. 54 ( 2023-08-28), p. 331-331
    Details
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2023-01, No. 54 ( 2023-08-28), p. 331-331
    Abstract: Long-term solid oxide electrolysis operation (SOEC) testing was performed to study the performance and performance degradation of LSCF-SDC/YSZ/Ni-YSZ cells under temperatures of 750 o C, 800 o C, and 850 o C, current density of 0.5A/cm 2 and 1.0A/cm 2 , and H 2 /H 2 O ratio of 1:1, 1:3, and 2:1. Operational temperature, current density, and H 2 /H 2 O ratio played important roles in the cells’ performance and performance degradation. These factors were correlated and should be balanced and/or optimized to maximize overall lifetime performance. LSCF-SDC cells showed better performance and less performance degradation under higher temperature. Electrochemical impedance spectroscopy (EIS) data showed polarization resistance was significantly lower for the cell operated at higher temperature. Therefore, SOEC operation may need relatively higher temperature to be activated. Long-term SOEC testing under different current density showed better performance and less performance degradation at 0.5A/cm 2 , 850 o C, and 1:1 of H 2 /H 2 O ratio. H 2 /H 2 O ratio in the functional layer of the cell also played an important role. The cell showed best performance and less performance degradation under 1:1 of H 2 /H 2 O ratio. EIS data showed the polarization resistance was significantly lower under 1:1 of H 2 /H 2 O ratio. H 2 /H 2 O ratio needs to be optimized for different operational temperature and current density. Overdosed steam may react with Ni causing Ni movement in the H 2 electrode, adding to cell degradation. Transmission electron microscopy (TEM) studies identified the formation of the (CoFe)O x along the SDC grain boundaries, which could impact both the SDC conductivity and the LSCF catalytic activity due to the loss of the transition metals in the LSCF. TEM analysis of the H 2 electrode identified a large number of NiO clusters relocated into the original pore region, seemingly formed during Ni migration. This NiO formation in the H 2 electrode during SOEC operation is another cause of long-term performance degradation.
    Type of Medium: Online Resource
    ISSN: 2151-2043
    URL: Article
    DOI: 10.1149/MA2023-0154331mtgabs
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2023
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  • 6
    Online Resource
    Online Resource
    Quantitative Analysis of Multi-Scale Heterogeneities in Complex Electrode Microstructures
    The Electrochemical Society ; 2020
    In:  Journal of The Electrochemical Society Vol. 167, No. 5 ( 2020-01-01), p. 054506-
    Details
    In: Journal of The Electrochemical Society, The Electrochemical Society, Vol. 167, No. 5 ( 2020-01-01), p. 054506-
    Abstract: A semi-empirical model is developed to quantitatively characterize electrode heterogeneities over the micro- and mesoscales, specifically between the relationship of the mean-squared normalized variance in the volume fraction, ( σ Φ V Φ ¯ V ) 2 , and the mean particle size normalized linear dimension, L a ¯ N . The model was developed analyzing data from five large-volume physical reconstructions – collected using Xe-plasma focused ion beam with SEM (PFIB-SEM) – of several commercial cell electrodes and from unique sets of synthetic microstructures designed to have controlled distributions in particle size and local volume fractions. When comparing physical reconstructions from distinct regions of the same electrode, millimeter length scale heterogeneities are also observed, even in microstructures with limited mesoscale variability. While the model is developed using synthetic microstructures, it is used to quantify three different types of heterogeneities in the commercial cells. The potential origins are discussed with respect to variations in particle size distributions in feedstocks and to phase distributions related to fabrication processes; the potential performance impacts are discussed with respect to two effective medium theory models. The characterization and analytical methodologies and model presented can support the design and development of improved electrodes.
    Type of Medium: Online Resource
    ISSN: 0013-4651 , 1945-7111
    URL: Article
    DOI: 10.1149/2.0102005JES
    RVK:
    VA 4000
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2020
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  • 7
    Online Resource
    Online Resource
    A Simplified Model for Reversible Solid Oxide Fuel Cells
    The Electrochemical Society ; 2021
    In:  ECS Transactions Vol. 103, No. 1 ( 2021-07-09), p. 751-765
    Details
    In: ECS Transactions, The Electrochemical Society, Vol. 103, No. 1 ( 2021-07-09), p. 751-765
    Abstract: A simplified reversible steady-state solid oxide cell model is formulated and solved analytically with only a few calibration parameters to match experimental performance data. A Butler-Volmer type model is used for the hydrogen electrode while a two-step single pathway reduced-order oxygen reduction reaction model is applied in the oxygen electrode. It is shown that this simple model is capable of accurately predicting the trends of V-I data produced experimentally at various gas concentrations in both fuel cell and electrolysis modes.
    Type of Medium: Online Resource
    ISSN: 1938-5862 , 1938-6737
    URL: Article
    DOI: 10.1149/10301.0751ecst
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2021
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  • 8
    Online Resource
    Online Resource
    Leveling Transient and Spatial Gradients in Planar Solid Oxide Cells Using Spatially Varied Microstructures: A Numerical Study
    The Electrochemical Society ; 2021
    In:  ECS Transactions Vol. 103, No. 1 ( 2021-07-09), p. 981-995
    Details
    In: ECS Transactions, The Electrochemical Society, Vol. 103, No. 1 ( 2021-07-09), p. 981-995
    Abstract: Spatial and transient gradients of temperature, current density, and gas species concentrations are expected to occur within large area planar solid oxide cells. These gradients can be detrimental to cell performance and stability. Such gradients are inherent to the geometry of the flow fields and interconnects between cells, especially at high current densities and fuel/steam utilizations in fuel cell/electrolysis modes, respectively. To reduce the extent of these gradients, additive manufacturing techniques could be employed to level the electrochemical reaction rates in the electrodes by purposefully designing the electrode active layer to have engineered property distributions. The purpose of this study is to investigate the effects of applied microstructural property gradients on spatial and transient gradients under extreme operating conditions. Modeling results suggest that by strategically varying the volume fractions of composite electrode materials, it is possible to modulate temperature, species, and current density gradients in planar solid oxide cells.
    Type of Medium: Online Resource
    ISSN: 1938-5862 , 1938-6737
    URL: Article
    DOI: 10.1149/10301.0981ecst
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2021
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  • 9
    Online Resource
    Online Resource
    Multiphysics Simulation for the Performance of Tubular Solid Oxide Fuel Cells Operated on Coal Syngas
    The Electrochemical Society ; 2023
    In:  ECS Transactions Vol. 111, No. 6 ( 2023-05-19), p. 1169-1178
    Details
    In: ECS Transactions, The Electrochemical Society, Vol. 111, No. 6 ( 2023-05-19), p. 1169-1178
    Abstract: Solid oxide fuel cells (SOFCs) can be operated directly on coal syngas, but the various contaminants in coal syngas affect the performance and durability of the device. In the present study, three-dimensional multiphysics simulations were developed to investigate the performance degradation of tubular SOFCs operated on coal syngas. The numerical model includes charge conservation, species transport within the electrodes/channels, and heat transfer within the device. These physical processes are coupled by the chemical/electrochemical reactions, which are represented by a Butler-Volmer type formula. Based on the thermodynamic database of impurity interactions with the Ni-YSZ composite anode, the contaminants are assumed to be adsorbed on the anode surface and form secondary phases. These formed phases affect the microstructural properties, electrical conductivity, and the number of active sites for electrochemical reactions. During the operation, the contaminants diffuse from the channel/anode interface to the anode/electrolyte interface, causing further irreversible degradation. The in-house developed multiphysics simulation is robust for prediction of interaction between anode materials with different types of contaminants (e.g., PH 3 , H 2 S, AsH 3 , etc.). With the calibrated model parameters, the performance of the tubular SOFCs with different levels/types of contaminants is predicted. The tolerance limits of the cells are also predicted. Furthermore, the degradation resulted from Ni redistribution, are also implemented into the model to mimic the performance of realistic SOFCs operating on coal syngas. The performance degradation investigation in this study provides guidance for experimental testing with syngas exposure, which is eventually beneficial to the cost reduction of the coal syngas clean-up technology.
    Type of Medium: Online Resource
    ISSN: 1938-5862 , 1938-6737
    URL: Article
    DOI: 10.1149/11106.1169ecst
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2023
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  • 10
    Online Resource
    Online Resource
    Lightweight Solid Oxide Cell Design for Ammonia-Fed SOFC Systems
    The Electrochemical Society ; 2023
    In:  ECS Transactions Vol. 111, No. 6 ( 2023-05-19), p. 2057-2065
    Details
    In: ECS Transactions, The Electrochemical Society, Vol. 111, No. 6 ( 2023-05-19), p. 2057-2065
    Abstract: A lightweight solid oxide fuel cell (SOFC) was developed by OxEon Energy that demonstrates the potential for increased specific power (kW/g) suitable for the requirements of electric Vertical Take-off and Landing (eVTOL) applications. Fuel flexibility was demonstrated in button cells and stacks using both legacy electrolyte-supported SOFC structure and the lightweight structure. Button cell and stack performance was nearly identical among hydrogen, ammonia, and reformed natural gas. Durability testing shows similarly stable performance in each fuel. A button cell test in ammonia at 800 °C using the lightweight cell structure measured area specific resistance (ASR) of 0.25 Ω-cm 2 in H 2 /N 2 and NH 3 fuel feeds and showed a peak power density of 0.98 W/ cm 2 in NH 3 fuel. Short term hold at 0.7 V showed stable performance.
    Type of Medium: Online Resource
    ISSN: 1938-5862 , 1938-6737
    URL: Article
    DOI: 10.1149/11106.2057ecst
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2023
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