Enhancing the quality of the tomography of nanoporous materials for better understanding of polymer electrolyte fuel cell materials

Vierrath, Severin; Güder, Firat; Menzel, Andreas M.; Hagner, Matthias; Zengerle, Roland; Zacharias, Margit; Thiele, Simon

doi:10.1016/j.jpowsour.2015.03.110

Cited by 46 publications

(43 citation statements)

References 23 publications

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“…Discrepancies between bulk estimations of porosity and FIB tomography can result from the random selection of the ROI in a material where the pore distribution varies in different regions, or from the invalidity of the assumptions used in the bulk estimation methods. Pore filling techniques may be a promising way to conquer the segmentation issue where inclusion of a heavy metal, which has a high contrast in BSE imaging, would greatly improve the image processing and hence the segmentation without requiring complex algorithms [79,80].…”

Section: Further Discussionmentioning

confidence: 99%

Nano-Tomography of Porous Geological Materials Using Focused Ion Beam-Scanning Electron Microscopy

Liu

Huis

et al. 2016

Minerals

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Tomographic analysis using focused ion beam-scanning electron microscopy (FIB-SEM) provides three-dimensional information about solid materials with a resolution of a few nanometres and thus bridges the gap between X-ray and transmission electron microscopic tomography techniques. This contribution serves as an introduction and overview of FIB-SEM tomography applied to porous materials. Using two different porous Earth materials, a diatomite specimen, and an experimentally produced amorphous silica layer on olivine, we discuss the experimental setup of FIB-SEM tomography. We then focus on image processing procedures, including image alignment, correction, and segmentation to finally result in a three-dimensional, quantified pore network representation of the two example materials. To each image processing step we consider potential issues, such as imaging the back of pore walls, and the generation of image artefacts through the application of processing algorithms. We conclude that there is no single image processing recipe; processing steps need to be decided on a case-by-case study.

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Section: Further Discussionmentioning

confidence: 99%

Nano-Tomography of Porous Geological Materials Using Focused Ion Beam-Scanning Electron Microscopy

Liu

Huis

et al. 2016

Minerals

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“…A correct segmentation is vital for the quantification of morphology and transport parameters, which can then be used to better understand the studied material, and to develop improved materials. 18 Tomographic data sets can be segmented automatically, but when there is a lack of sufficient gray level contrast a tedious manual segmentation is needed which can be done using specialized software such as Avizo (FEI, Bordeaux, France). 19 Manual segmentation is time consuming and depends on the skill and experience of the operator.…”

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confidence: 99%

“…21 Another recent approach to fill the pores of the catalyst layer with ZnO via atomic layer deposition (ALD) prior to tomography was reported recently. 18 By using ALD, even the nanometer sized pores could be filled with ZnO, which exhibits a good contrast to the catalyst layer in SEM images. 18 Of these approaches, epoxy impregnation offers the simplest approach to improve image contrast, and does not require sophisticated techniques.…”

mentioning

confidence: 99%

“…18 By using ALD, even the nanometer sized pores could be filled with ZnO, which exhibits a good contrast to the catalyst layer in SEM images. 18 Of these approaches, epoxy impregnation offers the simplest approach to improve image contrast, and does not require sophisticated techniques. 18,22 Hence this was the approach used in this work.…”

mentioning

confidence: 99%

“…18 Of these approaches, epoxy impregnation offers the simplest approach to improve image contrast, and does not require sophisticated techniques. 18,22 Hence this was the approach used in this work.…”

mentioning

confidence: 99%

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Enhanced Imaging of Lithium Ion Battery Electrode Materials

Biton

Yufit

Tariq

et al. 2016

J. Electrochem. Soc.

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In this study we present a novel method of lithium ion battery electrode sample preparation with a new type of epoxy impregnation, brominated (Br) epoxy, which is introduced here for the first time for this purpose and found suitable for focused ion beam scanning electron microscope (FIB-SEM) tomography. The Br epoxy improves image contrast, which enables higher FIB-SEM resolution (3D imaging), which is amongst the highest ever reported for composite LFP cathodes using FIB-SEM. In turn it means that the particles are well defined and the size distribution of each phase can be analyzed accurately from the complex 3D electrode microstructure using advanced quantification algorithms. The authors present for the first time a new methodology of contrast enhancement for 3D imaging, including novel advanced quantification, on a commercial Lithium Iron Phosphate (LFP) LiFePO 4 cathode. The aim of this work is to improve the quality of the 3D imaging of challenging battery materials by developing methods to increase contrast between otherwise previously poorly differentiated phases. This is necessary to enable capture of the real geometry of electrode microstructures, which allows measurement of a wide range of microstructural properties such as pore/particle size distributions, surface area, tortuosity and porosity. These properties play vital roles in determining the performance of battery electrodes. In order to improve battery performance it is important to characterize and quantify real electrode microstructures in three dimensions, and understand how these structures affect performance and cycle life.1 X-ray and FIB-SEM techniques have been attracting a lot of interest in the field of batteries and fuel cells due to their ability to characterize electrode structure at the length scales relevant for their operation.2-5 Porous carbon electrodes play an important role in both battery and fuel cell operation, where parameters such as porosity, tortuosity and pore-size distribution determine the transport properties of the electrode, as well as the kinetics of the electrochemical reactions.6 Therefore, a thorough quantitative microstructural characterization of porous-carbon electrodes is a pre-requisite for a complete understanding of the electrode behavior. However, the quantitative 3D microstructural characterization of the porous-carbon electrodes commonly used in battery and fuel cell devices is challenging. One of the biggest difficulties in the 3D imaging of battery materials in the characterization of carbon due to (i) the low X-ray attenuation coefficient when using X-ray imaging and (ii) the non-uniform interaction with the ion beam when using FIB-SEM imaging. Lithium Iron Phosphate (LFP) LiFePO 4 is a commercially available electrode material for Li-ion batteries for electric vehicles and energy storage applications, 7,8 and was used as the basis for this study. This interest is motivated by the many advantages of this material, which include excellent cycle life and a high intrinsic safety.9 It is, however, ...

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Stability of Platinum‐Group‐Metal‐Based Electrocatalysts in Proton Exchange Membrane Fuel Cells

Zhu

et al. 2022

Adv Funct Materials

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Proton exchange membrane fuel cells (PEMFCs) have attracted significant interest as a promising alternative technology to the combustion engine to power next-generation vehicles with zero emission. Among the various technological targets, system cost and durability are currently identified as the main obstacles toward large-scale implementation of PEMFCs. Platinumgroup-metal-based (PGM-based) catalysts are the most efficient catalyst for the rate-limiting cathodic oxygen reduction reaction in PEMFCs and take the highest share in the cost breakdown. Therefore, the stability of PGM-based electrocatalysts plays a significant role in the development of PEMFCs. This review will summarize the recent progress made on the understanding of both the fundamental chemical and structural stability of PGM-based catalysts, and their durability in operational PEMFC devices. It calls for systematic studies on the chemical, structural, and operational durability of the PGMbased catalyst and the need to coin practical descriptors for catalyst design with both superior activity and durability for cost-effective and high-performance PEMFCs.

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Enhancing the quality of the tomography of nanoporous materials for better understanding of polymer electrolyte fuel cell materials

Cited by 46 publications

References 23 publications

Nano-Tomography of Porous Geological Materials Using Focused Ion Beam-Scanning Electron Microscopy

Nano-Tomography of Porous Geological Materials Using Focused Ion Beam-Scanning Electron Microscopy

Enhanced Imaging of Lithium Ion Battery Electrode Materials

Stability of Platinum‐Group‐Metal‐Based Electrocatalysts in Proton Exchange Membrane Fuel Cells

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