Analysis of representative elementary volume and through-plane regional characteristics of carbon-fiber papers: diffusivity, permeability and electrical/thermal conductivity

García-Salaberri, Pablo A.; Zenyuk, Iryna V.; Shum, Andrew D.; Hwang, Gisuk; Vera, Marcos; Weber, Adam Z.; Gostick, Jeff T.

doi:10.1016/j.ijheatmasstransfer.2018.07.030

Cited by 111 publications

(118 citation statements)

References 136 publications

(179 reference statements)

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“…In addition, the narrow PSDs for each pore population and the periodic microstructure ( Figure 2) may enable more uniform velocity distribution throughout the electrode while minimizing stagnation zones. Establishing quantitative design criteria for future electrodes based on the results described above requires a comprehensive treatment of the coupled reaction and transport processes within the specific three-dimensional electrode structures, 53,[95][96][97][98][99] which is beyond the scope of this initial work.…”

Section: Resultsmentioning

confidence: 99%

Exploring the Role of Electrode Microstructure on the Performance of Non-Aqueous Redox Flow Batteries

Forner‐Cuenca

Penn

Oliveira

et al. 2019

J. Electrochem. Soc.

132

259

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Redox flow batteries are an emerging technology for long-duration grid energy storage, but further cost reductions are needed to accelerate adoption. Improving electrode performance within the electrochemical stack offers a pathway to reduced system cost through decreased resistance and increased power density. To date, most research efforts have focused on modifying the surface chemistry of carbon electrodes to enhance reaction kinetics, electrochemically active surface area, and wettability. Less attention has been given to electrode microstructure, which has a significant impact on reactant distribution and pressure drop within the flow cell.Here, drawing from commonly used carbon-based diffusion media (paper, felt, cloth), we systematically investigate the influence of electrode microstructure on electrochemical performance. We employ a range of techniques to characterize the microstructure, pressure drop, and electrochemically active surface area in combination with in-operando diagnostics performed in a single electrolyte flow cell using a kinetically facile redox couple dissolved in a non-aqueous electrolyte. Of the materials tested, the cloth electrode shows the best performance; the highest current density at a set overpotential accompanied by the lowest hydraulic resistance. We hypothesize that the bimodal pore size distribution and periodic, well-defined microstructure of the cloth are key to lowering mass transport resistance.

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Section: Resultsmentioning

confidence: 99%

Exploring the Role of Electrode Microstructure on the Performance of Non-Aqueous Redox Flow Batteries

Forner‐Cuenca

Penn

Oliveira

et al. 2019

J. Electrochem. Soc.

132

259

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“…Secondary overlap exists between the microporous layer and carbon fibre GDL. At 40% compression, irrespective of the arrangement, the entire microporous layer invades 65% of the GDL phase under the land ( GDLs [19,38,55].…”

Section: Materials Fractionmentioning

confidence: 99%

The effect of non-uniform compression and flow-field arrangements on membrane electrode assemblies - X-ray computed tomography characterisation and effective parameter determination

Kulkarni

Kok

Jervis

et al. 2019

Journal of Power Sources

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The performance of the of polymer electrolyte membrane (PEM) fuel cell is governed by a complex interaction of the structure of the membrane electrode assembly (MEA), cell compression, and operating parameters. Adequate cell compression for improved current collection and gas sealing, can structurally deform MEA with adverse consequences. Nonuniform MEA compression exerted by the flow-field design and arrangement induces heterogeneous transport properties. Hence, understanding morphological evolution and effective transport properties as an effect of MEA compression is an important factor for improving fuel cell performance and durability. In this paper, an X-ray computed tomography study of the entire MEA compression is presented, comprising of gas diffusion and microporous layers, catalyst layers, and the electrolyte membrane, subjected to non-uniform compression under two distinct flow-field arrangements. This study presents a comprehensive dataset of the heterogeneous effective properties required for robust computational modelling; including porosity, permeability, tortuosity, and diffusivity, along with the extent of blocking of the flow channel due to cell compression and effect of compression on the structural properties of the membrane.

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“…16,17 Therefore, while the macroscopic models 79 can capture the aggregate behavior, their predictions may significantly 80 deviate from the local predictions by microscopic models. 16,18 This 81 result bears significance, as it points to the need for more elaborate 82 description of transport in the porous layers. Nevertheless, the exces-83 sively high cost of such simulations limits their application to very 84 few conditions and a limited material set.…”

mentioning

confidence: 99%

“…15 [16] where HOR/ORR is the Peltier coefficient for HOR/ORR, 30 E an rev = 0, 209 and E ca rev = 1.229 − 8.5 × 10 −4 × (T − 298.15)…”

mentioning

confidence: 99%

Through-the-Membrane Transient Phenomena in PEM Fuel Cells: A Modeling Study

Goshtasbi

García-Salaberri

Chen

et al. 2019

J. Electrochem. Soc.

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This paper presents a 2D, fully coupled and comprehensive transient model that accounts for micro-structural features of various cell layers. The model benefits from state of the art sub-models for reaction kinetics and incorporates the polymer relaxation dynamics. Furthermore, a mixed wettability model is utilized to simulate the transient two phase conditions in the porous layers. The model is validated with transient experimental data under various conditions. A comprehensive simulation study is presented to investigate the impact of operating temperature and relative humidity on the transient response. The effects of cathode Pt loading and operation mode, i.e., current control versus voltage control, are also studied. The cell response is found to be dominated by water transport through its thickness. Additionally, it is found that reducing the Pt loading can influence the performance by changing the water balance in the cell, which has rarely been highlighted in the literature. In particular, at low temperature more water is transported toward the anode when the cathode Pt loading is reduced, since the resistance to water back diffusion is lowered with reduced thickness of the cathode catalyst layer. This trend is reversed at a higher temperature due to increased volumetric heat generation with reduced thickness. The model can help in understanding various transport phenomena and is expected to be useful for inspecting spatio-temporal temperature, potential, and species distributions across the cell's thickness and optimizing the cell design and choice of materials.

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Analysis of representative elementary volume and through-plane regional characteristics of carbon-fiber papers: diffusivity, permeability and electrical/thermal conductivity

Cited by 111 publications

References 136 publications

Exploring the Role of Electrode Microstructure on the Performance of Non-Aqueous Redox Flow Batteries

Exploring the Role of Electrode Microstructure on the Performance of Non-Aqueous Redox Flow Batteries

The effect of non-uniform compression and flow-field arrangements on membrane electrode assemblies - X-ray computed tomography characterisation and effective parameter determination

Through-the-Membrane Transient Phenomena in PEM Fuel Cells: A Modeling Study

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