Silicon (Si) anodes are promising candidates for Li-ion batteries due to their high specific capacity and low operating potential. Implementation has been challenged by the significant Si volume changes during (de)lithiation and associated growth/regrowth of the solid electrolyte interphase (SEI). In this report, fluorinated local high concentration electrolytes (FLHCEs) were designed such that each component of the electrolyte (solvent, salt, diluent) is fluorinated to modify the chemistry and stabilize the SEI of high (30%) silicon content anodes. FLHCEs were formulated to probe the electrolyte salt concentration and ratio of the fluorinated carbonate solvents to a hydrofluoroether diluent. Higher salt concentrations led to higher viscosities, conductivities, and contact angles on polyethylene separators. Electrochemical cycling of Si-graphite/NMC622 pouch cells using the FLHCEs delivered up to 67% capacity retention after 100 cycles at a C/3 rate. Post-cycling X-ray photoelectron spectroscopy (XPS) analyses of the Si-graphite anodes indicated the FLHCEs formed a LiF rich solid electrolyte interphase (SEI). The findings show that the fluorinated local high concentration electrolytes contribute to stabilizing the Si-graphite electrode over extended cycling.

Silicon (Si) is a promising high-capacity material for lithium-ion batteries; however, its limited reversibility hinders commercial adoption. Approaches such as particle and crystallite size reduction, introduction of conductive carbon, and use of different electrolyte solvents have been explored to overcome these electrochemical limitations. Herein, operando isothermal microcalorimetry (IMC) is used to probe the influence of silicon particle size, electrode composition, and electrolyte additives fluoroethylene carbonate and vinylene carbonate on the heat flow during silicon lithiation. The IMC data are complemented by X- ray photoelectron and Raman spectroscopies to elucidate differences in solid electrolyte interphase (SEI) composition. Nanosized (similar to 50 nm, n-Si) and micrometer-sized (similar to 4 mu m, mu-Si) silicon electrodes are formulated with and without amorphous carbon and electrochemically lithiated in ethylene carbonate (EC), fluoroethylene carbonate (FEC), or vinylene carbonate (VC) based electrolytes. Notably, n-Si electrodes generate 53-61% more normalized heat relative to their mu-Si counterparts, consistent with increased surface area and electrode/electrolyte reactivity. Introduction of amorphous carbon significantly alters the heat flow profile where multiple exothermic peaks and increased normalized heat dissipation are observed for all electrolyte types. Notably, the VC-containing electrolyte demonstrates the greatest normalized heat dissipation of the electrode compositions tested showing as much as a 50% increase compared to the EC or FEC counterparts. The results are relevant to the understanding of silicon negative electrode function in the presence of electrolyte additives and provide insight relative to silicon containing cell reactivity and safety.

In times of crisis, including the current COVID-19 pandemic, the supply chain of filtering facepiece respirators, such as N95 respirators, are disrupted. To combat shortages of N95 respirators, many institutions were forced to decontaminate and reuse respirators. While several reports have evaluated the impact on filtration as a measurement of preservation of respirator function after decontamination, the equally important fact of maintaining proper fit to the users' face has been understudied. In the current study, we demonstrate the complete inactivation of SARS-CoV-2 and preservation of fit test performance of N95 respirators following treatment with dry heat. We apply scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS), X-ray diffraction (XRD) measurements, Raman spectroscopy, and contact angle measurements to analyze filter material changes as a consequence of different decontamination treatments. We further compared the integrity of the respirator after autoclaving versus dry heat treatment via quantitative fit testing and found that autoclaving, but not dry heat, causes the fit of the respirator onto the users face to fail, thereby rendering the decontaminated respirator unusable. Our findings highlight the importance to account for both efficacy of disinfection and mask fit when reprocessing respirators to for clinical redeployment.

Modulation of electron/ion transport in electrodes through the appropriate mesoscale electrode structural design is essential to achieving effective utilization of nanoscale electroactive materials. Herein, nanosheet MoS2+x/carbon [one-dimensional (1D) carbon nanotube (CNT) or twodimensional (2D) graphene nanoplatelet (GNP)] heterostructures are prepared via a simple, one-step hydrothermal method, resulting in highelectrodes. In lithium-based batteries, an anionic S22--S2- redox system is demonstrated based on combined structural characterization using X-ray photoelectron spectroscopy, Raman spectroscopy, and in situ synchrotronbased X-ray absorption spectroscopy to elucidate the electrochemical behavior of the Mo and S centers. MoS2+x-GNP electrodes delivered 177 mAh/g (2.9 mAh/cm2) in the first cycle and 78 mAh/ g (1.3 mAh/cm2) after 100 cycles at a current of 3.2 mA/cm2, representing high capacities despite such a high material loading for a sulfur-equivalent system, with 44% capacity retention and good rate capability. Conversely, the MoS2+x-CNT heterostructure displayed lower capacity and more capacity fade at all rates, attributed to aggregation of the active and carbonaceous materials in these electrodes and poor access to MoS2+x edge sites, as visualized via 3D Raman mapping and electron microscopy. The significantly improved capacity retention of the MoS2+x-GNP system is attributed to the (i) morphology because the arrangement of the 2D MoS2+x nanosheets on the GNP substrate allows for edge sites with excess sulfur to be exposed, (ii) increased stability of the structure during cycling, and (iii) homogeneous dispersion of the active and carbonaceous materials, resulting in good electrical contact.

The mechanical degradation experienced by Si electrodes during Li (de)alloying reactions can potentially be mitigated by using Si‐based materials with layered 2D geometries. Such materials are expected to exhibit favorable mechanical properties and be capable of buffering the volume change associated with (de)lithitation. In this work, 2D siloxene nanosheets are synthesized using a facile topotactic reaction followed by ultrasonication as an exfoliation step. Detailed structural and chemical characterization via electron microscopy, X‐ray photoelectron spectroscopy (XPS), and Raman spectroscopy is conducted, revealing a low‐oxidized siloxene nanosheet material with only 15% surface Si‐oxide. The obtained siloxene nanosheets are tested as Li‐ion negative electrodes in lithium‐based electrochemical cells. The cells exhibit high rate capability with a capacity of 935 mAh g –1 at 3200 mA g –1 and ≈99.5% coulombic efficiency. The inclusion of fluoroethylene carbonate (FEC) in the electrolyte improves capacity retention over 200 cycles from 13% to 77% at 1000 mA g –1 . This behavior is attributed to the FEC decomposition forming a solid electrolyte interphase (SEI) with higher ion conductivity and robust LiF/Li x PO y F z content, as characterized via XPS Raman spectroscopy.

Use of masks is a primary tool to prevent the spread of the novel COVID-19 virus resulting from unintentional close contact with infected individuals. However, detailed characterization of the chemical properties and physical structure of common mask materials is lacking in the current literature. In this study, a series of commercial masks and potential mask materials, including 3M Particulate Respirator 8210 N95, a material provided by Oak Ridge National Laboratory Carbon Fiber Technology Facility (ORNL/CFTF), and a Filti Face Mask Material, were characterized by a suite of techniques, including scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. Wetting properties of the mask materials were quantified by measurements of contact angle with a saliva substitute. Mask pass-through experiments were performed using a dispersed metal oxide nanoparticle suspension to model the SARS-CoV-2 virus, with quantification via spatially resolved X-ray fluorescence mapping. Notably, all mask materials tested provided a strong barrier against respiratory droplet breakthrough. The comparisons and characterizations provided in this study provide useful information when evaluating mask materials for respiratory protection.

The COVID-19 pandemic resulted in imminent shortages of personal protective equipment such as face masks. To address the shortage, new sterilization or decontamination procedures for masks are quickly being developed and employed. Dry heat and steam sterilization processes are easily scalable and allow treatment of large sample sizes, thus potentially presenting fast and efficient decontamination routes, which could significantly ease the rapidly increasing need for protective masks globally during a pandemic like COVID-19. In this study, a suite of structural and chemical characterization techniques, including scanning electron microscopy (SEM), contact angle, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman were utilized to probe the heat treatment impact on commercially available 3M 8210 N95 Particulate Respirator and VWR Advanced Protection surgical mask. Unique to this study is the use of the synchrotron-based In situ and Operando Soft X-ray Spectroscopy (IOS) beamline (23-ID-2) housed at the National Synchrotron Light Source II at Brookhaven National Laboratory for near-edge X-ray absorption spectroscopy (NEXAFS).

Solid state electrolytes are receiving significant interest due to the prospect of improved safety, however, addressing the incidence and consequence of internal short circuits remains an important issue. Herein, a battery based on a LiI-LiI(HPN)2 solid state electrolyte demonstrated self-healing after internal shorting where the cells recovered and continued to cycle effectively. The functional rechargeable electrochemistry of the self-forming Li/I2-based battery was investigated through interfacial modification by inclusion of Li metal (at the negative interface), and/or fabricated carbon nanotube substrates at the positive interface. A cell design with lithium metal at the negative and a carbon substrate at the positive interface produced Coulombic efficiencies > 90% over 60 cycles. Finally, the beneficial effects of moderately elevated temperature were established where a 10°C temperature increase led to ~5X lower resistance.

We introduce a novel chemical preintercalation based synthesis technique based on hydrogen peroxide induced sol-gel process to obtain alkali ion containing ternary layered titanates (MTO, where M = Li, Na, K). Synthesis parameters leading to the formation of single-phase materials with homogeneous elemental distribution are reported for each of the preintercalated ion. Our analyses indicate that the interlayer spacing in the structure of the layered titanates increases with the increase of the radius of the hydrated preintercalated ion. Scanning and transmission electron microscopy imaging revealed morphological diversity: the LTO phase crystallized as nanoplates assembled in "peony-like" spherical agglomerates while NTO and KTO particles exhibited one-dimensional nanobelt or wire-like morphology, with the KTO nanobelts being shorter and more aggregated than the NTO nanobelts. Structural refinement corroborated by electron diffraction and high-resolution transmission electron microscopy revealed that the structure of the LTO phase is built by stacking Ti-O layers containing a single straight layer of connected TiO6 octahedra. The layers in NTO and KTO structures form differently and consist of double Ti-O layers with ragged arrangement of units built by TiO6 octahedra with two titanium rows. The NTO electrodes exhibited the highest electrochemical performance in cells with aqueous 1 M Na2SO4 electrolyte, followed by the KTO electrodes and then LTO electrodes, and this trend is maintained at various scan rates. The established relationships between the structure and electrochemical performance reveal that, in addition to interlayer distance and chemistry of the interlayer region, the structure of the layers can play an important role in charge storage properties of layered oxide electrodes. The double Ti-O layers in the structure of NTO and KTO phases provide a larger number of redox centers which could contribute to the superior electrochemical performance as compared to the LTO electrodes. Our findings indicate that layered materials containing double transition metal oxide layers are promising candidates for exfoliation and assembly with electronically conductive layers with the aim to create 2D heterostructures with high electrochemical performance.

This perspective article describes the use of energy dispersive X-ray diffraction (EDXRD) to study the evolution of electrochemical energy storage materials. Using a synchrotron light source, EDXRD allows crystallographic changes in materials to be tracked from deep within large specimens, due to the use of highly penetrating X-rays and the ability to define a well-controlled diffraction gauge volume in space. Herein we provide an overview of battery work performed using the EDXRD technique, as developed at beamline X17B1 at the National Synchrotron Light Source (NSLS), and continued at beamline 6BM-A at the Advanced Photon Source (APS), beamline I12 at the Diamond Light Source, and beamline 7T-MPW-EDDI at the Berlin Electron Storage Ring Society for Synchrotron Radiation (BESSY II). The High Energy Engineering X-Ray Scattering (HEX) beamline currently under construction at the National Synchrotron Light Source II (NSLS-II) by Brookhaven National Lab and the State of New York will further expand capability for and access to this technique. The article begins with a general introduction to the technique of EDXRD, including a description of the photon energy and d-spacing relationship and a discussion of the gauge volume. The primary topic of the review, battery characterization by EDXRD, includes discussion of batteries of differing materials chemistries (lithium-based batteries and aqueous batteries) which store energy by different mechanisms (insertion and conversion materials). A discussion of high temperature batteries is also included.

A microporous hydrogen-bonded organic framework (HOF) was successfully prepared by a cyclen-based octacarboxylate ligand H(8)tacnip-Zn. The obtained three-dimensional structure presents a periodic double-layer unit that stacks to form a one-dimensional channel that buttresses discrete cavities (similar to 5.6 x 5.6 angstrom(2)). From the single crystal structure, the macrocycle-bound metal ion was proven to greatly enhance the rigidity of the cyclen-based ligand while adjusting the direction of the carboxyl groups. The indelible porosity of degassed HOF was elucidated by CO2 sorption and selective gas adsorption. This work provides facile access to construct more porous HOFs based on a cyclen unit.

Lithium solid-state composite electrolytes (LiSCEs) provide the opportunity for long life spans, low self-discharge, high reliability, high energy density, and safety. Additionally, this class of electrolytes can be used in electrolytically formed solid-state batteries (EFBs), which may promote reductions in cell manufacturing costs due to their simplicity of design and permit the formation of batteries with diverse architectures. Herein, we provide a discussion of LiSCEs, highlight some of the recent progress in EFB development, and present a forward outlook.

Polyazamacrocycles and its functionalized derivatives have been employed recently as organic building blocks in the construction of extended metal–organic frameworks (MOFs). Incorporating azamacrocycles into the MOF architectures not only merges the chemistry of MOFs with supramolecular chemistry of the macrocycles, but also brings out novel properties from the hybrid frameworks produced. In this review, we describe recent advances of the fabrication of azamacrocycles into MOF structures along with the most prominent applications based upon azamacrocycle-containing MOFs, which include molecular recognition and separation, template synthesis, gas adsorption, and heterogenous catalysis.

Recent advances in the design and applications of azamacrocyclic-based MOFs have been summarized and reviewed.

Abstract The lanthanum-based metal macrocyclic framework, MMCF-3, where the ligand is 1,4,7,10-tetraazacyclododecane-N,N′,N″,N′″-tetra-p-methylbenzoic acid, has been synthesized and characterized by powder X-ray diffraction, single crystal X-ray diffraction, and thermogravimetric analysis. MMCF-3 forms in closely packed 2-D sheets. In MMCF-3, the azamacrocyclic-based ligand coordinates tetradentate to four separate lanthanum ions via its carboxylate groups, leaving the macrocycle site unoccupied. The lanthanum ions are 10-coordinate with a distorted bi-capped square anti-prism coordination environment. The vacancy of the macrocycle site within the framework encourages the utilization of the framework as a cation receptor. The availability of these sites allows for the possibility to coordinate to newly introduced metals to produce heterometallic frameworks, which could exhibit intriguing properties.

A series of prototypal metal-organic frameworks (MOFs) consisting of polyhedral cages with accessible Lewis-acid sites, have been systematically investigated for Friedländer annulation reaction, a straightforward approach to synthesizing quinoline and its derivatives. Amongst them MMCF-2 demonstrates significantly enhanced catalytic activity compared with the benchmark MOFs, HKUST-1 and MOF-505, as a result of a high-density of accessible Cu(II) Lewis acid sites and large window size in the cuboctahedral cage-based nanoreactor of MMCF-2.

AbstractThe reaction of Co3O4 in a Sr(OH)2/KOH reactive flux yields high quality commensurate single crystals of Sr5Co4O12 (Ag crucible, 750 °C, 5 h, 80% yield) and Sr6Co5O15 (Ag crucible, 500 °C, 5 h, 80% yield).

The reaction of Co3O4 in a Sr(OH)2/KOH reactive flux yields high quality commensurate single crystals of Sr5Co4O12 (Ag crucible, 750 °C, 5 h, 80% yield) and Sr6Co5O15 (Ag crucible, 500 °C, 5 h, 80% yield).

Single crystals of the NaLnTiO4 (Ln = La, Pr, Nd) phases were grown out of reactive sodium hydroxide melts. These layered materials crystallize in space group P4/nmm of the tetragonal system, with unit cell dimensions of a = 3.7998(5) Å and c = 13.273(3) Å (La), a = 3.7686(5) Å and c = 12.940(3) Å (Pr), and a = 3.7551(5) Å and c = 12.848(3) Å (Nd). These compounds possess a layered structure that is a variant of K2NiF4 with ordering of the Na and Ln ions.