Measurements of Pore Size Distribution, Porosity, Effective Oxygen Diffusivity, and Tortuosity of PEM Fuel Cell Electrodes

Yu, Zhiqiang; Carter, R. N.; Zhang, J.

doi:10.1002/fuce.201200017

Cited by 73 publications

(59 citation statements)

References 18 publications

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“…Typically, carbon supports are categorized into two broad definitions: solid carbons that possess low surface area and low microporosity, namely low surface area carbons (LSAC), and high surface area carbons (HSAC), which have high surface areas and a large number of micropores within each particle. [ 64,69,71,324,351 ] Ketjenblack is a prime example of an HSACs with a surface are of 900 m 2 g −1 , mostly due to the presence of micropores through the carbon particles. [ 255 ] Vulcan carbon is a classic example of a solid carbon or graphitized carbon black (GCB), which possesses a lower surface area (220 m 2 g −1 ).…”

Section: Catalyst Layer Structurementioning

confidence: 99%

Engineering Catalyst Layers for Next‐Generation Polymer Electrolyte Fuel Cells: A Review of Design, Materials, and Methods

Suter

Smith

Hack

et al. 2021

Advanced Energy Materials

107

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Polymer electrolyte fuel cells (PEFCs) are a promising replacement for the fossil fuel–dependent automotive and energy sectors. They have become increasingly commercialized in the last decade; however, significant limitations on durability and performance limit their commercial uptake. Catalyst layer (CL) design is commonly reported to impact device power density and durability; although, a consensus is rarely reached due to differences in testing conditions, experimental design, and types of data reported. This is further exacerbated by aspects of CL design such as catalyst support, proton conduction, catalyst, fabrication, and morphology, being significantly interdependent; hence, a wider appreciation is required in order to optimize performance, improve durability, and reduce costs. Here, the cutting‐edge research within the field of PEFCs is reviewed, investigating the effect of different manufacturing techniques, electrolyte distribution, support materials, surface chemistries, and total porosity on power density and durability. These are critically appraised from an applied perspective to inform the most relevant and promising pathways to make and test commercially viable cells. This holistic view of the competing aspects of CL design and preparation will facilitate the development of optimized CLs, especially the incorporation of novel catalyst support materials.

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Section: Catalyst Layer Structurementioning

confidence: 99%

Engineering Catalyst Layers for Next‐Generation Polymer Electrolyte Fuel Cells: A Review of Design, Materials, and Methods

Suter

Smith

Hack

et al. 2021

Advanced Energy Materials

107

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“…· dx [21] In this study, the thickness of the precipitated Li 2 O 2 film is assumed identical in all pores that is larger than the critical pore size, d min , within the computing element. As a result, the PDF within each computing element changes to the following piece-wise function after a layer of Li 2 O 2 with the thickness of δ Li 2 O 2 deposits on the surface and decreases the diameter of a pore from x to d:…”

Section: Assumptions-mentioning

confidence: 99%

A Modeling Study of the Pore Size Evolution in Lithium-Oxygen Battery Electrodes

2015

J. Electrochem. Soc.

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This study develops a statistics model that investigates the microstructural evolution of porous electrodes and couples the micro structural changes with a computational fluid dynamics model to simulate the discharge performance of an 800-μm-thick electrode at 1 A/m 2 . This study considers the fact that pores that are too small to hold reactants, smaller than a critical pore size, do not contribute to the discharge of the battery. It is found that when the pore size of the electrode increases, the discharge capacity of the electrode first increases due to the improved mass transfer and then decreases due to the decrease of the effective surface area. For instance, when the critical pore size is set as 10 nm, the discharge capacity gradually increases from 86.6 to 214.8 mAh/g carbon when the mean pore size of the electrode increases from 10 to 50 nm, followed by a capacity decrease to 150.8 mAh/g carbon when the mean pore size further increases to 100 nm. This study also finds that alternating the discharge current between 0 (open circuit condition) and the setting current rate can increase the discharge capacity of the lithium-oxygen battery because the oxygen concentration in the electrode increases during the open circuit condition. The increasing energy demands from portable electronic devices and the target of 300 miles driving range of electric vehicles have placed tremendous pressure on current electrical storage systems. Electric storage technologies with very high specific energy are required in order to meet the ever increasing energy demand without significantly increase the weight of the energy storage system. The lithium-oxygen battery is considered as a promising energy storage technology for portable and transportation applications considering its exceptionally high specific energy. Within four types of lithiumoxygen batteries, 1 the battery using organic electrolyte has attracted the most attention.2 Although the active intermediates may react with non-aqueous electrolytes and produce lithium carbonate, lithium hydroxide, and lithium alkyl carbonate, 3-6 the main product is expected to be Li 2 O 2 2 . The overall reaction happens during charge and discharge of a lithium-oxygen battery using organic electrolyte is:The theoretical energy density of the lithium-oxygen battery is calculated to be 11,680 Wh (kg lithium) −1 or 2,790 Wh (kg lithium and oxygen) −1 . 7 The measured specific energy of lithium-oxygen batteries reported in literature, however, is less than 10% of the theoretical specific energy. 8,9 The power, capacity and efficiency of batteries are restricted by the cathode gas diffusion electrode (GDE), which is typically made from carbon material, considering the high energy density of lithium metal and fast reaction rate of lithium electrode. 6,[10][11][12][13][14] In particular, the low solubility and diffusivity of oxygen in nonaqueous electrolytes limit the current density and the capacity of the battery.9,15-19 Meanwhile, pores with different sizes in the electrode have different im...

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“…Porosity can be introduced into catalytic materials through several techniques, including solvent evaporation, polymerization, seed swelling, spray drying, synthesis, phase separation methods etc . Generally, many experimental results have shown that increased porosity facilitates the mass transport and ion diffusion processes, thus helping electrochemical reactions to occur …”

Section: Introductionmentioning

confidence: 99%

Tailoring Carbon Nanotube Microsphere Architectures with Controlled Porosity

Zhang

Sadeghi

Jervis

et al. 2019

Adv Funct Materials

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Nanomaterials are at the core of fuel cell electrodes, providing high-area catalytic, proton, and electron conducting surfaces, traditionally on carbon black supports. Other carbons, e.g., carbon nanotubes (CNTs) and graphene are less prone to oxidation; however, their handling is not trivial due to health risks associated with their size. Assembling them into microscale structures without jeopardizing their performance is ideal, but there are mass transfer limitations as thickness increases. In this work, a soluble acicular calcium carbonate (aragonite) is used as a porogen to create connected porosity in microspheres. Increasing macroporosity has a considerable positive impact on the mass transfer process. The experimental manipulation of porosity of the microspheres is combined with pore network modeling to better understand how pore distribution throughout the whole microsphere can optimize platinum utilization decorated onto the CNTs. Oxygen reduction reaction (ORR) activity is compared with the prepared composite materials and a commercial Pt/C catalyst for 4 weeks. The composite materials exhibit a highly interconnected network resulting in a 3.4 times higher ORR activity (at 0.9 V vs reversible hydrogen electrode) than that of the nanoporous spheres with no macroporosity.

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Measurements of Pore Size Distribution, Porosity, Effective Oxygen Diffusivity, and Tortuosity of PEM Fuel Cell Electrodes

Cited by 73 publications

References 18 publications

Engineering Catalyst Layers for Next‐Generation Polymer Electrolyte Fuel Cells: A Review of Design, Materials, and Methods

Engineering Catalyst Layers for Next‐Generation Polymer Electrolyte Fuel Cells: A Review of Design, Materials, and Methods

A Modeling Study of the Pore Size Evolution in Lithium-Oxygen Battery Electrodes

Tailoring Carbon Nanotube Microsphere Architectures with Controlled Porosity

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