Effective transport properties of the porous electrodes in solid oxide fuel cells

Choi, Haechul; Berson, Arganthaël; Pharoah, Jon G.; Beale, Steven

doi:10.1177/2041296710394266

Cited by 37 publications

(56 citation statements)

References 78 publications

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“…The effective electric conductivity of backbone (σ b eff ) and infiltrated (σ i eff ) phase is evaluated with MicroFOAM, a finite volume method based on the open-source CFD toolkit OpenFOAM, developed and validated by Choi et al 52 for fuel cell applications. The electrode domain is discretized using body-fitted/cut-cell grids.…”

Section: Modelingmentioning

confidence: 99%

A Particle-Based Model for Effective Properties in Infiltrated Solid Oxide Fuel Cell Electrodes

Bertei

Pharoah

Gawel

et al. 2014

J. Electrochem. Soc.

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A modeling framework for the numerical reconstruction of the microstructure of infiltrated electrodes is presented in this study. A particle-based sedimentation algorithm is used to generate the backbone, while a novel packing algorithm is used to randomly infiltrate nanoparticles on the surface of backbone particles. The effective properties, such as the connected triple-phase boundary length, the effective conductivity, the effective diffusivity, are evaluated on the reconstructed electrodes by using geometric analysis, finite volume and random-walk methods, and reported in dimensionless form to provide generality to the results. A parametric study on the effect of the main model and operating parameters is performed. Simulations show that the critical loading (i.e., the percolation threshold) increases as the backbone porosity decreases and the nanoparticle diameter increases. Large triple-phase boundary length, specific surface area and good effective conductivity can be reached by infiltration, without detrimental effects on the effective transport properties in gas phase. Simulations reveal a significant sensitivity to the size and contact angle of infiltrated particles, suggesting that the preparation process of infiltrated electrodes should be properly tailored in order to obtain the optimized structures predicted by the model. In the last decade, much attention has been drawn toward nanostructured electrodes for solid oxide fuel cells (SOFCs) prepared via infiltration techniques.1-7 The main reason is reduced polarization resistance, with corresponding increased power density, in comparison with conventional electrodes prepared via traditional mixing and sintering processes. The improved performance of infiltrated electrodes holds even at intermediate temperatures (500-800• C), as demonstrated by a large number of experimental studies. [8][9][10][11][12][13] Other technological advantages are a wide choice of catalyst materials, a good adhesion and a reduced thermal expansion mismatch between the electrode and the electrolyte.3 On the other hand, the long-term stability and the fabrication cost of nanostructured electrodes still need to be properly addressed. 2,3The infiltration (or impregnation) technique involves the deposition of nanoparticles into a pre-sintered backbone of micrometer-size particles.1,3 The backbone is a skeletal structure typically composed of a single component, such as yttria-stabilized zirconia (YSZ) 5,8 or, in alternative, a mixed ionic-electronic conductor (e.g., lanthanum strontium cobalt ferrite LSCF).14 However, composite backbones, such as the usual lanthanum strontium manganite (LSM)/YSZ cathode, have also been used. 1,15 The sintering of the backbone is performed at high temperature in order to ensure structural stability of the electrode and good connection among backbone particles. 3 In the following step, nanoparticles are infiltrated in the backbone using different methods (such as metal salt precipitation, 2 nanoparticle dispersion, 16 molten salts) 1 and then sinte...

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Section: Modelingmentioning

confidence: 99%

A Particle-Based Model for Effective Properties in Infiltrated Solid Oxide Fuel Cell Electrodes

Bertei

Pharoah

Gawel

et al. 2014

J. Electrochem. Soc.

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“…In order to calculate the effective transport properties, one needs to solve the coupled Equations [1][2][3][4] where Butler-Volmer Equation [5] is used as the constraint of Equations [1][2][3][4]. Figure 2 demonstrates FVM simulation examples for the electron potential, ion potential, and gas phase concentration fields.…”

Section: Numerical Resultsmentioning

confidence: 99%

“…The reconstruction of microstructure is based on particle based a pseudo-random numerical model consists of overlapping Carbon, Pt, and Ionomer particles. This reconstructed microstructure was converted into a 3-D body-fitted/cut-cell based unstructured FV grid using MicroFOAM (3). Performing on the constructed sample computational domain, the effective transport properties were evaluated by using FVM through the open-source CFD toolbox, OpenFOAM ® .…”

Section: Resultsmentioning

confidence: 99%

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Effective Transport Properties Accounting for Electrochemical Reactions of Proton-Exchange Membrane Fuel Cell Catalyst Layers

Pharoah

Choi

Chueh³

et al. 2011

ECS Trans.

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There has been a rapidly growing interest in three-dimensional microstructural reconstruction of fuel cell electrodes so as to derive more accurate descriptors of the pertinent geometric and effective transport properties. Due to the limited accessibility of experiments based reconstruction techniques, such as dual-beam focused ion beamscanning electro microscopy or micro X-Ray computed tomography, within sample micro-structures of the catalyst layers in polymer electrolyte membrane fuel cells (PEMFCs), a particle based numerical model is used in this study to reconstruct sample microstructure of the catalyst layers in PEMFCs. Then the reconstructed sample structure is converted into the computational grid using body-fitted/cut-cell based unstructured meshing technique. Finally, finite volume methods (FVM) are applied to calculate effective properties on computational sample domains.

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“…They reported that, to obtain reliable TPBs density, if the representative sample is a cube with length L related to the diameter of the packing particles, D then L/D ≥ 7.5 to obtain representative results. Choi et al [26] worked on the finite volume method using different types of grids to compute the effective transport properties of SOFC anodes. Their results were compared to those calculated with random walk simulations for the case of a bodycentred cubic lattice of spheres, and showed that for reliable effective transport properties to be achieved, one needs to consider a domain size of at least ten times the mean particle diameter in each direction (i.e, L/D≥ 10).…”

Section: Representative Sample Size For Investigating the Effective Cmentioning

confidence: 99%

Towards the 3D Modelling of the Effective Conductivity of Solid Oxide Fuel Cell Electrodes – Validation against experimental measurements and prediction of electrochemical performance

Rhazaoui

Cai

Kishimoto

et al. 2015

Electrochimica Acta

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Effective transport properties of the porous electrodes in solid oxide fuel cells

Cited by 37 publications

References 78 publications

A Particle-Based Model for Effective Properties in Infiltrated Solid Oxide Fuel Cell Electrodes

A Particle-Based Model for Effective Properties in Infiltrated Solid Oxide Fuel Cell Electrodes

Effective Transport Properties Accounting for Electrochemical Reactions of Proton-Exchange Membrane Fuel Cell Catalyst Layers

Towards the 3D Modelling of the Effective Conductivity of Solid Oxide Fuel Cell Electrodes – Validation against experimental measurements and prediction of electrochemical performance

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