Graded Microporous Layers for Enhanced Capillary‐Driven Liquid Water Removal in Polymer Electrolyte Membrane Fuel Cells

Shrestha, Pranay; Ouellette, David; Lee, Jongmin; Gao, Nan; Muirhead, Daniel; Liu, Hang; Banerjee, Rupak; Bazylak, Aimy

doi:10.1002/admi.201901157

Cited by 30 publications

(21 citation statements)

References 72 publications

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“…In a wide range of production methods, the structure development occurs rather randomly under uncontrolled conditions [40]. Secondly, the softer materials, such as felt or foam, are very often compressed inside the technical equipment, resulting in a gradient of pore sizes [41,42]. On the other hand, it is of interest to assess how controlled grading of the pore structure can influentially impact the improvement of the overall transport kinetics of porous materials.…”

Section: Introductionmentioning

confidence: 99%

Computational Optimization of Porous Structures for Electrochemical Processes

et al. 2020

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Porous structures are naturally involved in electrochemical processes. The specific architectures of the available porous materials, as well as their physical properties, crucially affect their applications, e.g., their use in fuel cells, batteries, or electrolysers. A key point is the correlation of transport properties (mass, heat, and charges) in the spatially—and in certain cases also temporally—distributed pore structure. In this paper, we use mathematical modeling to investigate the impact of the pore structure on the distribution of wetting and non-wetting phases in porous transport layers used in water electrolysis. We present and discuss the potential of pore network models and an upscaling strategy for the simulation of the saturation of the pore space with liquid and gas, as well as the computation of the relative permeabilities and oxygen dissolution and diffusion. It is studied how a change of structure, i.e., the spatial grading of the pore size distribution and porosity, change the transport properties. Several situations are investigated, including a vertical gradient ranging from small to large pore sizes and vice versa, as well as a dual-porosity network. The simulation results indicate that the specific porous structure has a significant impact on the spatial distribution of species and their respective relative permeabilities. In more detail, it is found that the continuous increase of pore sizes from the catalyst layer side towards the water inlet interface yields the best transport properties among the investigated pore networks. This outcome could be useful for the development of grading strategies, specifically for material optimization for improved transport kinetics in water electrolyser applications and for electrochemical processes in general.

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Section: Introductionmentioning

confidence: 99%

Computational Optimization of Porous Structures for Electrochemical Processes

et al. 2020

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“…[43] In another approach by Shrestha et al the wettability and porosity of the MPL was tuned by employing two consecutive layers with varying PTFE contents ranging from 20 wt% at the CL side and 10 wt% at the GDL side. [44] With this MPL design strategy the accumulation of liquid water within the GDL was significantly reduced, especially at high current densities (> 1A cm À 2 ). With respect to PGM-free bipolar interface based fuel cells, those results encourage novel catalyst layer manufacturing approaches, inspired by a different field of research.…”

Section: Catalyst Layersmentioning

confidence: 99%

Bipolar‐Interface Hydrogen Fuel Cells: A Review and Perspective on Future High‐Performance, Low Platinum‐Group Metal Content Designs

2021

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This Review elucidates the state-of-the-art, challenges, and future prospects for bipolar-interface-based fuel cells (BPIFCs), focusing on hydrogen-based systems. On the one side, it provides a summary of state-of-the-art design strategies for BPIFCs from different fields of application. On the other hand, it identifies the two most pivotal areas for a future understanding that particularly refer to the changed mass transport situations introduced by the bipolar fuel cell design, that is, the water management and the bipolar interface layer itself. All operation-relevant components such as the gas diffusion layers, catalyst layers, and membrane designs are discussed within the framework of these two main areas. As non-platinum-group metal (PGM) oxygen reduction is one of the key benefits of bipolar hydrogen fuel cells, a particular focus is put on this configuration. Several additional challenges that exclusively originate from non-PGM-based catalyst layers and possible mitigation approaches are discussed. One key insight is that these thick layers could take over the role of microporous layers in the future. Finally, we emphasize that there is a strong lack in both theoretical and experimental approaches that improve our understanding of the underlying processes in bipolar fuel cell designs.

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“…The importance of understanding the wetting state and predicting its impact extends beyond consideration of geological materials. It is central to capillary dominated technologies including filters, fuel cells, and fluid wicking and repellant fabrics 29,30 . The absence of spatially resolved wetting characterisation is inhibiting advances in pore scale model predictions of upscaled flow The maps are generated defining and computing a wetting index (Γ) on a pore-by-pore basis.…”

Section: Introductionmentioning

confidence: 99%

Determination of the spatial distribution of wetting in the pore networks of rocks

Garfi¹,

John²,

Rücker³

et al. 2022

Preprint

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The macroscopic movement of subsurface fluids involved in CO 2 storage, groundwater, and petroleum engineering applications is controlled by interfacial forces in the pores of rocks, micrometer to millimetre in length scale. Recent advances in physics based models of these systems has arisen from approaches simulating flow through a digital representation of the complex pore structure. However, further progress is limited by a lack of approaches to characterising the spatial distribution of the wetting state within the pore structure. In this work, we show how observations of the fluid coverage of mineral surfaces within the pores of rocks can be used as the basis for a quantitative 3D characterisation of heterogeneous wetting states throughout rock pore structures. We demonstrate the approach with water-oil fluid pairs on rocks with distinct lithologies (sandstone and carbonate) and wetting states (hydrophilic, intermediate wetting, or heterogeneously wetting). The resulting 3D maps can be used as a deterministic input to pore scale modelling workflows and applied to all multiphase flow problems in porous media ranging from soil science to fuel cells.

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Graded Microporous Layers for Enhanced Capillary‐Driven Liquid Water Removal in Polymer Electrolyte Membrane Fuel Cells

Cited by 30 publications

References 72 publications

Computational Optimization of Porous Structures for Electrochemical Processes

Computational Optimization of Porous Structures for Electrochemical Processes

Bipolar‐Interface Hydrogen Fuel Cells: A Review and Perspective on Future High‐Performance, Low Platinum‐Group Metal Content Designs

Determination of the spatial distribution of wetting in the pore networks of rocks

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