Cation-disordered rocksalt (DRX) oxides are promising candidates as next-generation cathodes for lithium-ion batteries. Partial fluorination of the DRX oxides enhances their cyclability. However, the lattice position, concentration, and spatial distribution of fluorine within DRX lattices remain elusive. Here, we use atom location by channeling-enhanced microanalysis, energy-dispersive X-ray spectroscopy, electron energy loss spectroscopy, and integrated differential phase contrast imaging in a scanning transmission electron microscope to gain atomic-level insights into DRX with nominal composition of Li1.2Mn0.7Ti0.1O1.7F0.3 and Li1.15Ni0.45Ti0.3Mo0.1O1.85F0.15. We reveal that fluorine substitutes oxygen in the DRX lattices. The O/F ratio in terms of O+F = 2 is in the range from 1.92:0.08 to 1.82:0.18. Spatially, fluorine is distributed in the proximity of the Li-rich regions but distinct from lithium fluoride. Additionally, we observe that incorporation of fluorine in the DRX lattice induces a larger variation in cation-anion separation. These observations provide insight into the guided design of oxyfluoride DRX cathodes for high-performance batteries.

Journal Article History and Impact of the Annual Women in Microscopy Breakfast Get access Lee Pullan, Lee Pullan Thermo Fisher Scientific, Hillsboro, OR, United States Search for other works by this author on: Oxford Academic Google Scholar Trisha Rice Trisha Rice Thermo Fisher Scientific, Eindhoven, The Netherlands Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 29, Issue Supplement_1, 1 August 2023, Page 2047, https://doi.org/10.1093/micmic/ozad067.1057 Published: 22 July 2023

Journal Article Cryogenic Electron Microscopy Combined with Energy-Dispersive X-ray Spectroscopy Tomography for Materials Science Get access Lin Jiang, Lin Jiang Materials & Structural Analysis Division, Thermo Fisher Scientific, Hillsboro, OR, USA Corresponding author: lin.jiang@thermofisher.com; yanghe@ustb.edu.cn Search for other works by this author on: Oxford Academic Google Scholar Yang He, Yang He Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, China Corresponding author: lin.jiang@thermofisher.com; yanghe@ustb.edu.cn Search for other works by this author on: Oxford Academic Google Scholar Chongmin Wang, Chongmin Wang Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, USA Search for other works by this author on: Oxford Academic Google Scholar Cedric Bouchet-Marquis, Cedric Bouchet-Marquis Materials & Structural Analysis Division, Thermo Fisher Scientific, Hillsboro, OR, USA Search for other works by this author on: Oxford Academic Google Scholar Lee Pullan, Lee Pullan Materials & Structural Analysis Division, Thermo Fisher Scientific, Hillsboro, OR, USA Search for other works by this author on: Oxford Academic Google Scholar Brandon Van Leer, Brandon Van Leer Materials & Structural Analysis Division, Thermo Fisher Scientific, Hillsboro, OR, USA Search for other works by this author on: Oxford Academic Google Scholar Liu Zhao, Liu Zhao Materials & Structural Analysis Division, Thermo Fisher Scientific, Hillsboro, OR, USA Search for other works by this author on: Oxford Academic Google Scholar Yuri Rikers, Yuri Rikers Materials & Structural Analysis Division, Thermo Fisher Scientific, Hillsboro, OR, USA Search for other works by this author on: Oxford Academic Google Scholar Christian Maunders, Christian Maunders Materials & Structural Analysis Division, Thermo Fisher Scientific, Hillsboro, OR, USA Search for other works by this author on: Oxford Academic Google Scholar David Foord, David Foord Materials & Structural Analysis Division, Thermo Fisher Scientific, Hillsboro, OR, USA Search for other works by this author on: Oxford Academic Google Scholar ... Show more Richard G White Richard G White Materials & Structural Analysis Division, Thermo Fisher Scientific, Hillsboro, OR, USA Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 28, Issue S1, 1 August 2022, Pages 328–330, https://doi.org/10.1017/S1431927622002082 Published: 01 August 2022

The solid-electrolyte interphase (SEI), a layer formed on the electrode surface, is essential for electrochemical reactions in batteries and critically governs the battery stability. Active materials, especially those with extremely high energy density, such as silicon (Si), often inevitably undergo a large volume swing upon ion insertion and extraction, raising a critical question as to how the SEI interactively responds to and evolves with the material and consequently controls the cycling stability of the battery. Here, by integrating sensitive elemental tomography, an advanced algorithm and cryogenic scanning transmission electron microscopy, we unveil, in three dimensions, a correlated structural and chemical evolution of Si and SEI. Corroborated with a chemomechanical model, we demonstrate progressive electrolyte permeation and SEI growth along the percolation channel of the nanovoids due to vacancy injection and condensation during the delithiation process. Consequently, the Si-SEI spatial configuration evolves from the classic 'core-shell' structure in the first few cycles to a 'plum-pudding' structure following extended cycling, featuring the engulfing of Si domains by the SEI, which leads to the disruption of electron conduction pathways and formation of dead Si, contributing to capacity loss. The spatially coupled interactive evolution model of SEI and active materials, in principle, applies to a broad class of high-capacity electrode materials, leading to a critical insight for remedying the fading of high-capacity electrodes.

While fluorescence microscopy provides tools for highly specific labeling and sensitive detection, its resolution limit and lack of general contrast has hindered studies of cellular structure and protein localization. Recent advances in correlative light and electron microscopy (CLEM), including the fully integrated CLEM workflow instrument, the FEI CorrSight with MAPS, have allowed for a more reliable, reproducible, and quicker approach to correlate three-dimensional time-lapse confocal fluorescence data, with three-dimensional focused ion beam-scanning electron microscopy data. Here we demonstrate the entire integrated CLEM workflow using fluorescently tagged MCF7 breast cancer cells.

An in situ method for the preparation of nickel phosphide (Ni2P) on silica, alumina, and amorphous silica alumina (ASA) supports is described. The synthesis avoids the use of nickel and phosphorus salts by employing the reaction between nickel hydroxide (Ni(OH)(2)) and hypophosphorus acid (H3PO2), allowing the impregnation of nickel hypophosphite (Ni(H2PO2)(2)) onto the oxide supports in the absence of salt by-products. Temperature-programmed reduction (TPR) in flowing hydrogen at 573-773 K yields phase pure Ni2P on the supports with small average particle sizes (3-4 nm) as measured using transmission electron microscopy. The conversion of Ni(H2PO2)(2) to Ni2P and related reactions were probed using TPR with on-line mass spectral analysis of the gas effluent. Unsupported Ni(H2PO2)(2) reacts in flowing hydrogen to produce PH3 and H2O at 468 and 482 K, respectively; the reaction is shifted to increasingly higher temperatures for Ni(H2PO2)(2) supported on SiO2, Al2O3 and ASA. The hydrodenitrogenation (HDN) and hydrodesulfurization (HDS) properties of the Ni2P catalysts were probed using a mixed feed containing carbazole and benzothiophene. While Ni2P/SiO2 catalysts prepared by the different methods exhibited similar HDN and HDS activities, the in situ prepared Ni2P/Al2O3 and Ni2P/ASA catalysts were substantially more active than their ex situ counterparts prepared from hypophosphite- and phosphate-based precursors. (C) 2015 Elsevier Inc. All rights reserved.

Journal Article Reducing the Missing Wedge in TEM Tomography Get access A Genc, A Genc FEI Company, 5350 NE Dawson Creek Drive, Hillsboro, OR, USA Search for other works by this author on: Oxford Academic Google Scholar L Kovarik, L Kovarik Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA, USA Search for other works by this author on: Oxford Academic Google Scholar L Pullan, L Pullan FEI Company, 5350 NE Dawson Creek Drive, Hillsboro, OR, USA Search for other works by this author on: Oxford Academic Google Scholar J Ringnalda J Ringnalda FEI Company, 5350 NE Dawson Creek Drive, Hillsboro, OR, USA Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 22, Issue S3, 1 July 2016, Pages 26–27, https://doi.org/10.1017/S1431927616000982 Published: 25 July 2016

Correlative light and electron microscopy (CLEM) combines localization data from fluorescent microscopy (FM) with ultra-structural information from electron microscopy (EM). Recent improvements on fluorescent dyes and proteins enabled wider applications of this approach [1][2]. One of the main difficulties in CLEM is that often time, sample processing for EM imaging quenches the FM signal. Despite those difficulties, some newer labeling methods enable to perform CLEM experiments with a high level of success. The study of mouse hepatitis virus replication in murine cells described below demonstrates the most recent improvement made in this field.

Oxidation of alloy often involves chemical partition and injection of vacancies. Chemical partition is the consequence of selective oxidation, while injection of vacancies is associated with the differences of diffusivity of cations and anions. It is far from clear as how the injected vacancies behave during oxidation of metal. Using in-situ transmission electron microscopy, we captured unprecedented details on the collective behavior of injected vacancies during oxidation of metal, featuring an initial multi-site oxide nucleation, vacancy supersaturation, nucleation of a single cavity, sinking of vacancies into the cavity and accelerated oxidation of the particle. High sensitive energy dispersive x-ray spectroscopy mapping reveals that Cr is preferentially oxidized even at the initial oxidation, leading to a structure that Cr oxide is sandwiched near the inner wall of the hollow particle. The work provides a general guidance on tailoring of nanostructured materials involving multi-ion exchange such as core-shell structured composite nanoparticles.

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Lithium- and manganese-rich (LMR) layered-structure cathode materials deliver a much higher energy density than traditional cathode materials such as LiMn 2 O 4 spinel and LiCoO 2 . However, significant challenges, including voltage fade and limited cycle life in LMR cathodes still remain to be overcome prior to their large-scale market penetration. Here, we report on the direct correlation between voltage fade and atomic level spatial distribution of chemical species among LMR cathode materials (Li[Li 0.2 Ni 0.2 M 0.6 ]O 2 ) prepared by several methods, including co-precipitation (CP), sol-gel (SG) and hydrothermal assisted (HA) methods. Quantitative chemical composition analysis was performed on these materials using large-area X-ray energy dispersive spectroscopy (XEDS) mapping. Meanwhile, we used aberration-corrected scanning transmission electron microscopy (STEM) combined with electron energy loss spectroscopy (EELS) to acquire detailed crystallographic data on Li[Li 0.2 Ni 0.2 Mn 0.6 ]O 2 cathode prepared by different methods. The atomic contrast in high-angle annular dark field (HAADF) STEM imaging identified the details of stacking and ordering in the particles while EELS chemical analysis revealed important chemistry information. We found that the materials prepared by the CP and SG methods exhibit a relatively high propensity for Ni segregation, leading to fast voltage fade and poor cycling stability. However, material prepared by the HA method exhibits very uniform Ni distribution and greatly reduced voltage fade. To the best of our knowledge, this is the first direct atomic-scale evidence to correlate atomic level cation uniformities with the electrochemical performance of cathode materials. More importantly, the voltage fade and energy degradation of LMR cathode materials can be significantly mitigated by improving the uniformity of chemical species in atomic level that are strongly affected by the preparation methods and synthesis conditions. These results also shine the light on the current debate regarding to the average/local structure of LMR cathode materials. LMR cathodes prepared by co-precipitation and sol-gel methods exhibit significant Ni segregation and dominated by LiMO 2 R-3m phase, where the preferential segregation of Ni blocks lithium ion diffusion channels, weaken nickel-manganese interactions, lead to easy reduction of the manganese ions and fast voltage/capacity fade. In contrast, LMR cathodes prepared by the hydrothermal assisted method form a solid solution dominated by Li 2 MO 3 C2/m monoclinic symmetry with largely suppressed Ni segregation and are more stable against excessive lithium ion removal, enhance Ni-Mn interaction and stabilize crystal structure, leads to greatly reduced voltage fade and excellent cycling stability of LMR cathodes. Therefore, LMR cathodes with uniform distribution of chemical species (minimal Ni segregation) are very promising for use in high-energy Li-ion batteries for large-scale practical applications. The fundamental correlation between the atomic level spatial distribution of the chemical species and the functional stability of the materials found in this work also provides new perspective on the design and development of other functional materials with significantly enhanced stability. Acknowledgements This work is supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U. S. Department of Energy under Contract No. DE-AC02-05CH11231, Subcontract No. 18769, under the Batteries for Advanced Transportation Technologies program. The microscopic study described in this paper is supported by the Laboratory Directed Research and Development Program as part of the Chemical Imaging Initiative at Pacific Northwest National Laboratory (PNNL). The work was conducted in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by DOE’s Office of Biological and Environmental Research and located at PNNL. PNNL is operated by Battelle for the DOE under Contract DE-AC05-76RLO1830. The authors also would like to thank M. M. Thackeray for useful discussions.

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Surface modification of silicon nanoparticles via molecular layer deposition (MLD) has been recently proved to be an effective way for dramatically enhancing the cyclic performance in lithium ion batteries. However, the fundamental mechanism of how this thin layer of coating functions is not known, which is complicated by the inevitable presence of native oxide of several nanometers on the silicon nanoparticle. Using in situ TEM, we probed in detail the structural and chemical evolution of both uncoated and coated silicon particles upon cyclic lithiation/delithation. We discovered that upon initial lithiation, the native oxide layer converts to crystalline Li2O islands, which essentially increases the impedance on the particle, resulting in ineffective lithiation/delithiation and therefore low Coulombic efficiency. In contrast, the alucone MLD-coated particles show extremely fast, thorough, and highly reversible lithiation behaviors, which are clarified to be associated with the mechanical flexibility and fast Li(+)/e(-) conductivity of the alucone coating. Surprisingly, the alucone MLD coating process chemically changes the silicon surface, essentially removing the native oxide layer, and therefore mitigates side reactions and detrimental effects of the native oxide. This study provides a vivid picture of how the MLD coating works to enhance the Coulombic efficiency, preserves capacity, and clarifies the role of the native oxide on silicon nanoparticles during cyclic lithiation and delithiation. More broadly, this work also demonstrates that the effect of the subtle chemical modification of the surface during the coating process may be of equal importance to the coating layer itself.

Email of the presenting author: mert.kurttepeli@uantwerpen.be During the last decade, there has been an increasing demand on the 3D characterization of materials, which led to the development of different electron tomography techniques. BFTEM and HAADF-STEM based electron tomography are among those that are commonly performed in materials science. However, these techniques are mainly used to obtain the 3D morphologies of the nanostructures rather than the chemical information. Through the 3D composition mapping using STEM coupled with the X-ray energy dispersive spectrometry (XEDS) via symmetrically arranged XEDS detector design, it is now possible to resolve the 3D distribution of elements in nanoscale materials and to elucidate the 3D chemical information in a large field of view of the TEM sample [1]. We present the application of the XEDS-STEM tomography technique for 3D chemical imaging of nanoscale materials. We performed this technique to investigate the 3D chemical distribution of titanium dioxide (TiO2) and vanadium oxide (VOx) coated carbon nanotubes (CNT). Figure 1 and 2 show the results of 3D tomography applied to CNT-TiO2-VOx-TiO2 using both HAADF STEM and XEDS-STEM techniques. The comparison of simultaneously acquired HAADF-STEM and XEDS-STEM tomography results shows that XEDS-STEM tomography succeeds to provide 3D chemical information of the material in addition to the 3D morphology, in spite of the low, neighboring atomic numbers of Ti, V and C. As presented in Fig 2, XEDS-STEM tomography resolves the individual Ti, V and C containing layers and reveals that the coating of CNT by TiO2-VOx-TiO2 was uniform and conformal. One important advantage of XEDS-STEM tomography is the decreased electron beam induced damage in the TEM samples. With the improved XEDS detectors which give higher collection efficiencies, the specimen damage is minimized significantly [1]. This enabled the precise 3D nanoscale chemical characterization of fine structures as in our case without the shape and size changes of the object during acquisition. Through XEDS-STEM tomography technique it is therefore possible to resolve 3D compositional variations at nanoscale with high accuracy. [1] A. Genc, L. Kovarik, M. Gu, H. Cheng, P. Plachinda, L. Pullan, B. Freitag and C. Wang, Ultramicroscopy 131, 24 32 (2013).

We present a tomography technique which couples scanning transmission electron microscopy (STEM) and X-ray energy dispersive spectrometry (XEDS) to resolve 3D distribution of elements in nanoscale materials. STEM imaging when combined with XEDS mapping using a symmetrically arranged XEDS detector design around the specimen overcomes many of the obstacles in 3D chemical imaging of nanoscale materials and successfully elucidates the 3D chemical information in a large field of view of the transmission electron microscopy (TEM) sample. We employed this technique to investigate 3D distribution of Nickel (Ni), Manganese (Mn) and Oxygen (O) in a Li1.2Ni0.2Mn0.6O2 (LNMO) nanoparticle used as a cathode material in Lithium (Li) ion batteries. For this purpose, 2D elemental maps were acquired for a range of tilt angles and reconstructed to obtain 3D elemental distribution in an isolated LNMO nanoparticle. The results highlight the strength of this technique in 3D chemical analysis of nanoscale materials by successfully resolving Ni, Mn and O elemental distributions in 3D and discovering the new phenomenon of Ni surface segregation in this material. Furthermore, the comparison of simultaneously acquired high angle annular dark field (HAADF) STEM and XEDS STEM tomography results shows that XEDS STEM tomography provides additional 3D chemical information of the material especially when there is low atomic number (Z) contrast in the material of interest.

The use of mesoporous silicon particles for drug delivery has been widely explored thanks to their biodegradability and biocompatibility. The ability to tailor the physicochemical properties of porous silicon at the micro- and nanoscale confers versatility to this material. A method for the fabrication of highly reproducible, monodisperse, mesoporous silicon particles with controlled physical characteristics through electrochemical etching of patterned silicon trenches is presented. The particle size is tailored in the micrometer range and pore size in the nanometer range, the shape from tubular to discoidal to hemispherical, and the porosity from 46 to over 80%. In addition, the properties of the porous matrix are correlated with the loading of model nanoparticles (quantum dots) and their three-dimensional arrangement within the matrix is observed by transmission electron microscopy tomography. The methods developed in this study provide effective means to fabricate mesoporous silicon particles according to the principles of rational design for therapeutic vectors and to characterize the distribution of nanoparticles within the porous matrix.

The structure of the endosomal-associated protein, Hrs, has been determined with cryo-electron microscopy. Hrs interacts with a number of proteins, including SNAP-25 and STAM1, forming a complex that binds ubiquitin moieties. Analytical ultracentrifugation studies revealed that Hrs exists as a hexamer. The symmetry and the structure of the hexameric form of Hrs were determined with the single-particle reconstruction method. Hrs; comprises three antiparallel dimers with a central core and distinct caps on either end. Crystal structures of VHS and FYVE domains fit into the Hrs end caps in the EM density map. Thus, the location of domains that interact with the endosomal membrane, the VHS, FYVE, and C-terminal domains, facilitates the anchorage of Hrs to the membrane, initiating the functional processes of Hrs; on the endosome. Based on our model, the Hrs hexamer interacts with the membrane and acts as a "master molecule" that presents multiple sites for protein binding.

The Tat system mediates Sec-independent transport of folded precursor proteins across the bacterial plasma membrane or the chloroplast thylakoid membrane. Tat transport involves distinct high-molecular-weight TatA and TatBC complexes. Here we report the 3D architecture of the TatA complex from Escherichia coli obtained by single-particle electron microscopy and random conical tilt reconstruction. TatA forms ring-shaped structures of variable diameter in which the internal channels are large enough to accommodate known Tat substrate proteins. This morphology strongly supports the proposal that TatA forms the protein-conducting channel of the Tat system. One end of the channel is closed by a lid that might gate access to the channel. On the basis of previous protease accessibility measurements, the lid is likely to be located at the cytoplasmic side of the membrane. The observed variation in TatA diameter suggests a model for Tat transport in which the number of TatA protomers changes to match the size of the channel to the size of the substrate being transported. Such dynamic close packing would provide a mechanism to maintain the membrane permeability barrier during transport.

Proteasome-dependent proteolysis is essential for a number of key cellular processes and requires a sophisticated biogenesis pathway to function. Here, we have arrested the assembly process in its dynamic progression at the short-lived 16S state. Structural analysis of the 16S proteasome precursor intermediates by electron microscopy, and single particle analysis reveals major conformational changes in the structure of the beta-ring in comparison with one-half of the 20S proteasome. The individual beta-subunits in the 16S precursor complex rotate with respect to their positions in the x-ray crystallographic structure of the fully assembled 20S. This rearrangement results in a movement of the catalytic residue threonine-1 from the protected location in 16S precursor complexes to a more exposed position in the 20S structure. Thereby, our findings provide a molecular explanation for the structural rearrangements necessary for the dimerization of two 16S precursor complexes and the subsequent final maturation to active 20S proteasomes.