An Epoxy‐Free Sample Preparation Approach to Enable Imaging of Ionomer and Carbon in Polymer Electrolyte Membrane Fuel Cells

Soleymani, Amir Peyman; Reid, Marcia; Janković, Jasna

doi:10.1002/adfm.202209733

Cited by 9 publications

(3 citation statements)

References 41 publications

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“…84 Ec-LPTEM offers a significant opportunity for studying the degradation pathways of these catalysts in real-time and under realistic conditions. 9 This technique has been utilized to study commercial and state-of-the-art materials, most often in conditions relevant to PEMFCs, 85 revealing mechanisms of metal dissolution, dealloying, coalescence and ripening, while also providing insights into corrosion of the catalyst support material. 12,21,61,86 General considerations for the study of ORR catalysts in ec-LPTEM involve the choice of liquid electrolyte and electrochemical conditions.…”

Section: Electrocatalytic Applicationsmentioning

confidence: 99%

Considerations of Liquid-Phase Transmission Electron Microscopy Applied to Heterogeneous Electrocatalysis

Shen

Girod

Vávra

et al. 2023

J. Electrochem. Soc.

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Liquid-phase transmission electron microscopy (LPTEM) is an essential tool for studying the dynamics of materials interactions at the nanoscale, in and/or with their operational environment. Microfabricated SiNx membrane cells further allow the integration of thin-film electrodes which opens the technique to studies of heterogeneous electrocatalysts under relevant electrochemical conditions. However, experiments remain challenging and the specificities of the dedicated electrochemical cells and of the interactions of the electron beam with the electrolyte demand careful interpretation of the results. Herein, we discuss important aspects of the implementation of ec-LPTEM. We first consider the range of information that can be accessible with the technique for electrocatalytic applications and we detail the influence of the thickness and flow of liquid electrolytes on the operation using membrane-based microcells. Further, we provide guidelines for electrochemical configuration of the substrate working, reference, and counter electrodes. We draw all considerations together by experimentally demonstrating the application of ec-LPTEM for the CO2 reduction reaction, the oxygen reduction reaction, and the oxygen evolution reaction. The probed effects in metallic and oxide catalysts are directly related to the applied electrochemical stimuli and corroborate the representativity of the processes under investigation.

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Section: Electrocatalytic Applicationsmentioning

confidence: 99%

Considerations of Liquid-Phase Transmission Electron Microscopy Applied to Heterogeneous Electrocatalysis

Shen

Girod

Vávra

et al. 2023

J. Electrochem. Soc.

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“…Another challenge of using ultramicrotome techniques is the process of embedding the sample into the epoxy matrix, which can introduce contamination (e.g., carbon-based species) to the sample during TEM imaging . Ultramicrotome can be applied to sectioning some samples without the use of epoxy embedding, but this may present a challenge for sectioning highly porous materials since the epoxy can help preserve the structure of the material during the cutting process . Cross sections of LIB materials that have been prepared by ultramicrotome techniques include core–shell particles, layered structures, and doped microparticles. ,− The use of ultramicrotome techniques to prepare cross sections has enabled a high-throughput investigation of multiple cross sections and the visualization of the outer layers of microscale cathode particles .…”

Section: Introductionmentioning

confidence: 99%

Atomic-Scale Characterization of Microscale Battery Particles Enabled by a High-Throughput Focused Ion Beam Milling Technique

Pauls,

Radford,

Taylor

et al. 2024

ACS Omega

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The cathode materials in lithium-ion batteries (LIBs) require improvements to address issues such as surface degradation, short-circuiting, and the formation of dendrites. One such method for addressing these issues is using surface coatings. Coatings can be sought to improve the durability of cathode materials, but the characterization of the uniformity and stability of the coating is important to assess the performance and lifetime of these materials. For microscale particles, there are, however, challenges associated with characterizing their surface modifications by transmission electron microscopy (TEM) techniques due to the size of these particles. Often, techniques such as focused ion beam (FIB)-assisted lift-out can be used to prepare thin cross sections to enable TEM analysis, but these techniques are very time-consuming and have a relatively low throughput. The work outlined herein demonstrates a FIB technique with direct support of microscale cathode materials on a TEM grid that increases sample throughput and reduces the processing time by 60–80% (i.e., from >5 to ∼1.5 h). The demonstrated workflow incorporates an air–liquid particle assembly followed by direct particle transfer to a TEM grid, FIB milling, and subsequent TEM analysis, which was illustrated with lithium nickel cobalt aluminum oxide particles and lithium manganese nickel oxide particles. These TEM analyses included mapping the elemental composition of cross sections of the microscale particles using energy-dispersive X-ray spectroscopy. The methods developed in this study can be extended to high-throughput characterization of additional LIB cathode materials (e.g., new compositions, coating, end-of-life studies), as well as to other microparticles and their coatings as prepared for a variety of applications.

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“…Associating polymers are smart, responsive materials that incorporate reversibly associative functional groups. They have been used in diverse technologies ranging from water purification [1,2] to desalination [3,4], fuel cells [5,6], biomedical sensors [7,8], flow batteries [9,10], enhanced oil recovery in petroleum industry [11,12], and self-healing [13,14] applications. Ionomers are an important subclass of associating polymers in which less than 20% of the backbone atoms are bonded to pendant groups that are ionic, with nonbonded counterions maintaining charge neutrality.…”

Section: Introductionmentioning

confidence: 99%

Bead–Spring Simulation of Ionomer Melts—Studying the Effects of Chain-Length and Associating Group Fraction on Equilibrium Structure and Extensional Flow Behavior

Mohottalalage,

Saab,

Maiti

2023

Polymers

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Ionomers are associative polymers with diverse applications ranging from selective membranes and high-performance adhesives to abrasion- and chemical-resistant coatings, insulation layers, vacuum packaging, and foamed sheets. Within equilibrium melt, the ionic or associating groups are known to form thermally reversible, associative clusters whose presence can significantly affect the system’s mechanical, viscoelastic, and transport properties. It is, thus, of great interest to understand how to control such clusters’ size distribution, shape, and stability through the designed choice of polymer architecture and the ionic groups’ fraction, arrangement, and interaction strength. In this work, we represent linear associating polymers using a Kremer–Grest type bead–spring model and perform large-scale MD simulations to explore the effect of polymer chain-length (l) and fraction (fs) of randomly placed associating groups on the size distribution and stability of formed clusters. We consider different chain-lengths (below and above entanglement), varying fractions of associating groups (represented by ‘sticky’ beads) between 5 and 20%, and a fixed sticky–sticky nonbond interaction strength of four times that between regular non-associating beads. For all melts containing associating groups the equilibrium structure factor S(q) displays a signature ionomer peak at low wave vector q whose intensity increases with increasing fs and l. The average cluster size Nc increases with fs. However, the effect of chain-length on Nc appears to be pronounced only at higher values of fs. Under extensional flows, the computed stress (and viscosity) is higher at higher fs and l regardless of strain rate. Beyond a critical strain rate, we observe fragmentation of the associative clusters, which has interesting effects on the stress/viscous response.

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An Epoxy‐Free Sample Preparation Approach to Enable Imaging of Ionomer and Carbon in Polymer Electrolyte Membrane Fuel Cells

Cited by 9 publications

References 41 publications

Considerations of Liquid-Phase Transmission Electron Microscopy Applied to Heterogeneous Electrocatalysis

Considerations of Liquid-Phase Transmission Electron Microscopy Applied to Heterogeneous Electrocatalysis

Atomic-Scale Characterization of Microscale Battery Particles Enabled by a High-Throughput Focused Ion Beam Milling Technique

Bead–Spring Simulation of Ionomer Melts—Studying the Effects of Chain-Length and Associating Group Fraction on Equilibrium Structure and Extensional Flow Behavior

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