An Electrochemical Effectiveness Model and Its Implication for Performance Loss Due to Electrode Microstructural Degradation in Solid Oxide Fuel Cells

Baek, Seung Man; Shin, Dong-Woo; Sohn, Seung Kook; Nam, Jin Hyun

doi:10.1002/fuce.201500204

Cited by 6 publications

(4 citation statements)

References 39 publications

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“…, ϕ T depends on the microstructural, dimensional, and property parameters, namely,

λ_{normalt normalp normalb}^{V}

, L , σ eff , and r tpb . Previous studies showed that ϕ T encountered during the operation of IT‐SOFCs generally falls in the range of 5–20 for the anode reaction layer (Ni/YSZ) and 0.5–2.5 for the cathode reaction layer (LSM/YSZ) . The distribution of

i_{normalt normalr}^{V} ((), η)

inside the active reaction layer is shown for various ϕ T values in Figure , by assuming the symmetric Butler–Volmer reaction kinetics (α = 0.5).…”

Section: Resultsmentioning

confidence: 99%

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Electrochemically Active Thickness of Solid Oxide Fuel Cell Electrodes: Effectiveness Model Prediction

Nam

2017

Bulletin Korean Chem Soc

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The three-phase boundaries (TPBs) in the electrodes of solid oxide fuel cells (SOFCs) have different activity because of the distributed nature of the electrochemical reactions. The electrochemically active thickness (EAT) is a good measure to evaluate the extension of the active reaction zone into the electrode and the effective utilization of TPBs. In this study, an electrochemical reaction/charge conduction problem is formulated based on the Butler-Volmer reaction kinetics and then numerically solved to determine the EATs for the active electrode layers of SOFCs with various microstructural, dimensional, and property parameters. Thus, the EAT data and correlations presented in this study are expected to provide useful information for designing efficient electrodes of SOFCs.

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“…, ϕ T depends on the microstructural, dimensional, and property parameters, namely,

λ_{normalt normalp normalb}^{V}

i_{normalt normalr}^{V} ((), η)

inside the active reaction layer is shown for various ϕ T values in Figure , by assuming the symmetric Butler–Volmer reaction kinetics (α = 0.5).…”

Section: Resultsmentioning

confidence: 99%

“…The accuracy of the modeling was validated by the good agreements between the results obtained by the effectiveness model and those by the microscale models which consider the detailed electrochemical reaction and electronic and ionic charge transport . This clearly indicates that Eqs.…”

Section: Theory and Calculationsmentioning

confidence: 99%

Electrochemically Active Thickness of Solid Oxide Fuel Cell Electrodes: Effectiveness Model Prediction

Nam

2017

Bulletin Korean Chem Soc

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“…14 Further studies on modeling agglomerates and effectiveness factors in room-temperature fuel cells have refined and extended modeling and experimental approaches. [15][16][17][18][19][20][21][22][23] In solid oxide fuel cells, Costagmagna et al modeled the active functional catalyst layer using an effectiveness factor approach, where the modified Thiele modulus compared the ratio between rates of reaction and ionic charge transport through the active layer; 24 subsequently, Shin and Nam incorporated Butler-Volmer kinetics into the rate expression, 25 Baek et al used this framework to hypothesize performance degradation, 26 and Nam investigated the influence of various charge transfer coefficients. 27 Recently, effectiveness factor analysis has also been utilized in gas diffusion electrodes for CO 2 reduction to model agglomerates 28 and as part of the development of an analytical model of the catalyst layer.…”

Section: List Of Symbolsmentioning

confidence: 99%

Methods—A Potential–Dependent Thiele Modulus to Quantify the Effectiveness of Porous Electrocatalysts

Brushett

Wan

Greco

et al. 2021

J. Electrochem. Soc.

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Electrochemical reactors often employ high surface area electrocatalysts to accelerate volumetric reaction rates and increase productivity. While electrocatalysts can alleviate kinetic overpotentials, diffusional resistances at the pore-scale often prevent full catalyst utilization. The effect of intraparticle diffusion on the overall reaction rate can be quantified through an effectiveness factor expression governed by the Thiele modulus parameter. This analytical approach is integral to the development of catalytic structures for thermochemical processes and has previously been extended to electrochemical processes by accounting for the relationship between reaction kinetics and electrode overpotential. In this paper, we illustrate the method by deriving the expression for the potential-dependent Thiele modulus and using it to quantify the effectiveness factor for porous electrocatalytic structures. Specifically, we demonstrate the application of this mathematical framework to spherical microparticles as a function of applied overpotential across catalyst properties and reactant characteristics. The relative effects of kinetics and mass transport are related to overall reaction rates, revealing markedly lower catalyst utilization at increasing overpotential. Subsequently, we generalize the analysis to different catalyst shapes and provide guidance on the design of porous catalytic materials for use in electrochemical reactors.

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“…In addition, a simple correlation equation was also proposed along with the correlation coefficients relevant to the symmetric Butler-Volmer reaction kinetics. Their model was successfully used for one-dimensional simulation of a single-cell SOFC [22] and the theoretical prediction of electrode microstructural effects [23,24].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Effectiveness Factors for Butler-Volmer Reaction Kinetics in Active Electrode Layers of Solid Oxide Fuel Cells

Nam¹

2017

J. Electrochem. Sci. Technol

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In this study, a numerical approach is adopted to investigate the effectiveness factors for distributed electrochemical reactions in thin active reaction layers of solid oxide fuel cells (SOFCs), taking into account the Butler-Volmer reaction kinetics. The mathematical equations for the electrochemical reaction and charge conduction process were formulated by assuming that the active reaction layer has a small thickness, homogeneous microstructure, and high effective electronic conductivity. The effectiveness factor is defined as the ratio of the actual reaction rate (or equivalently, current generation rate) in the active reaction layer to the nominal reaction rate. From extensive numerical calculations, the effectiveness factors were obtained for various charge transfer coefficients of 0.3-0.8. These effectiveness data were then fitted to simple correlation equations, and the resulting correlation coefficients are presented along with estimated magnitude of error.

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An Electrochemical Effectiveness Model and Its Implication for Performance Loss Due to Electrode Microstructural Degradation in Solid Oxide Fuel Cells

Cited by 6 publications

References 39 publications

Electrochemically Active Thickness of Solid Oxide Fuel Cell Electrodes: Effectiveness Model Prediction

Electrochemically Active Thickness of Solid Oxide Fuel Cell Electrodes: Effectiveness Model Prediction

Methods—A Potential–Dependent Thiele Modulus to Quantify the Effectiveness of Porous Electrocatalysts

Electrochemical Effectiveness Factors for Butler-Volmer Reaction Kinetics in Active Electrode Layers of Solid Oxide Fuel Cells

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