In Situ and Ex Situ NMR Studies of High-V Li Cathode Materials

2016 ◽  
Keyword(s):  
Cathode Materials ◽  
Ex Situ ◽  
Nmr Studies

Ultra-small MnCo2O4 nanocrystals decorated on nitrogen-enriched carbon nanofibers as oxygen cathode for Li-O2 batteries

2020 ◽  
Vol 13 (06) ◽  
pp. 2051035
Author(s):  
Xiaoping Jiang ◽  
Ronghua Wang ◽  
Ning Hu ◽  
Chaohe Xu
Keyword(s):  
Particle Size ◽  
Cathode Materials ◽  
Nitrogen Doping ◽  
Carbon Nanofiber ◽  
Nucleation And Growth ◽  
Ex Situ ◽  
Aprotic Electrolyte ◽  
High Level ◽  
Oxygen Cathode

Ultra-small MnCo2O4 nanocrystals/nitrogen enriched carbon nanofiber composites, with particle size as small as 2–4[Formula: see text]nm and nitrogen content as high as [Formula: see text][Formula: see text]at.%, were designed and used as oxygen cathode materials for Li-O2 batteries, with an aprotic electrolyte. Via an in-situ nucleation and growth, the morphology, size and distribution of MnCo2O4 nanocrystals were well controlled on surface of nanofibers, with strong interfacial interactions between the two components. Benefitting from the unique microstructure and high-level nitrogen doping, the MnCo2O4/NCF composite can deliver discharge and charge capacities of 4147.8 and 3842.8[Formula: see text]mAh/g as oxygen cathode materials, and columbic efficiencies are about 92.6%. More importantly, the discharge products can completely decompose in charging process as evidenced by an ex-situ FESEM investigation, while for pure NCF cathode, particle and plate-like Li2O2 were still observed on its surface, which confirmed that the MnCo2O4/NCF composite has a superior electrocatalytic activity that that of NCF.

scholarly journals Exploiting In-Situ NMR to Monitor the Formation of a Metal-Organic Framework

2019 ◽  
Author(s):  
Corey Jones ◽  
Colan Hughes ◽  
Hamish Yeung ◽  
Alison Paul ◽  
Kenneth D. M. Harris ◽  
...  
Keyword(s):  
Self Assembly ◽  
Metal Organic Framework ◽  
Quantitative Information ◽  
Ex Situ ◽  
Nmr Studies ◽  
In Situ Techniques ◽  
Liquid Phases ◽  
Nmr Study ◽  
Metal Organic

<p> </p><p>The formation processes of metal-organic frameworks are increasingly widely researched using in-situ techniques, although there remains a scarcity of NMR studies in the field. In this work, the synthesis of MFM-500(Ni) has been investigated using the Combined Liquid- And Solid-State In‑situ Crystallization NMR strategy, which provides information on the time-evolution of both solid and liquid phases during crystallization. In our NMR study, the liquid-phase NMR data recorded as a function of time at five fixed temperatures afford qualitative information on the solution-phase processes and quantitative information on the kinetic parameters of crystallization, allowing the activation energies for nucleation and growth to be determined. Ex-situ SAXS studies provide complementary nanoscale information on the rapid self-assembly prior to crystallisation, and in-situ PXRD confirms that the only crystalline phase present during the reaction is phase-pure MFM-500(Ni).<br></p>

scholarly journals In situ PDF and solid-state NMR studies of antimony anodes for Na-ion batteries

2014 ◽  
Vol 70 (a1) ◽  
pp. C354-C354
Author(s):  
Phoebe Allan ◽  
John Griffin ◽  
Olaf Borkiewicz ◽  
Kamila Wiaderek ◽  
Ali Darwiche ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Anode Materials ◽  
Large Scale ◽  
Lithium Ion ◽  
Sodium Ion ◽  
Ex Situ ◽  
Sodium Ion Batteries ◽  
Nmr Studies

Sodium-ion batteries have attracted attention in recent years because of the natural abundance of sodium compared to lithium, making them particularly attractive in applications such as large-scale grid storage where low cost and sustainability, rather than light weight is the key issue [1]. Several materials have been suggested as cathodes but far fewer studies have been done on anode materials and, because of the reluctance of sodium to intercalate into graphite, the anode material of choice in commercial lithium-ion batteries, the anode represents a significant challenge to this technology. Materials which form alloys with sodium, particularly tin and antimony, have been suggested as anode materials; their ability to react with multiple sodium ions per metal-atom give potential for high gravimetric capacities[2]. However, relatively little is known about the reaction mechanism in the battery, primarily due to drastic reduction in crystallinity during (dis)charging conditions, but also because the structures formed on electrochemical cycling may not be alloys known to exist under ambient conditions. In this study, we present a study of antimony as an anode in sodium-ion batteries, using in situ pair distribution function (PDF) analysis combined with ex situ solid-state nuclear magnetic resonance studies. PDF experiments were performed at 11-ID-B, APS using the AMPIX electrochemical cell [3], cycling against sodium metal. Inclusion of diffuse scattering in analysis is able to circumvent some of the issues of crystallinity loss, and gain information about the local structure in all regions, independent of the presence of long-range order in the material. This approach has been used to probe local correlations in previously uncharacterised regions of the electrochemical profile and analyse phase progression over the full charge cycle. This analysis has been linked with ex situ 23Na solid-state NMR experiments to examine the local environment of the sodium; these show evidence of known NaxSb phases but indicate additional metastable phases may be present at partial discharge.

scholarly journals Exploiting In-Situ NMR to Monitor the Formation of a Metal-Organic Framework

2020 ◽  
Author(s):  
Corey Jones ◽  
Colan Hughes ◽  
Hamish Yeung ◽  
Alison Paul ◽  
Kenneth D. M. Harris ◽  
...  
Keyword(s):  
Self Assembly ◽  
Metal Organic Framework ◽  
Quantitative Information ◽  
Ex Situ ◽  
Nmr Studies ◽  
In Situ Techniques ◽  
Nmr Study ◽  
Metal Organic ◽  
In Situ Nmr

The formation processes of metal-organic frameworks are becoming more widely researched using in-situ techniques, although there remains a scarcity of NMR studies in this field. In this work, the synthesis of framework MFM-500(Ni) has been investigated using an in‑situ NMR strategy that provides information on the time-evolution of the reaction and crystallization process. In our in‑situ NMR study of MFM-500(Ni) formation, liquid-phase 1H NMR data recorded as a function of time at 5 fixed temperatures afford qualitative information on the solution-phase processes and quantitative information on the kinetics of crystallization, allowing the activation energies for nucleation and growth to be determined. Ex-situ SAXS studies provide complementary nanoscale information on the rapid self-assembly prior to MOF crystallization and in-situ powder X-ray diffraction confirms that the only crystalline phase present during the reaction is phase-pure MFM-500(Ni).

scholarly journals Exploiting In-Situ NMR to Monitor the Formation of a Metal-Organic Framework

2020 ◽  
Author(s):  
Corey Jones ◽  
Colan Hughes ◽  
Hamish Yeung ◽  
Alison Paul ◽  
Kenneth D. M. Harris ◽  
...  
Keyword(s):  
Self Assembly ◽  
Metal Organic Framework ◽  
Quantitative Information ◽  
Ex Situ ◽  
Nmr Studies ◽  
In Situ Techniques ◽  
Nmr Study ◽  
Metal Organic ◽  
In Situ Nmr

The formation processes of metal-organic frameworks are becoming more widely researched using in-situ techniques, although there remains a scarcity of NMR studies in this field. In this work, the synthesis of framework MFM-500(Ni) has been investigated using an in‑situ NMR strategy that provides information on the time-evolution of the reaction and crystallization process. In our in‑situ NMR study of MFM-500(Ni) formation, liquid-phase 1H NMR data recorded as a function of time at 5 fixed temperatures afford qualitative information on the solution-phase processes and quantitative information on the kinetics of crystallization, allowing the activation energies for nucleation and growth to be determined. Ex-situ SAXS studies provide complementary nanoscale information on the rapid self-assembly prior to MOF crystallization and in-situ powder X-ray diffraction confirms that the only crystalline phase present during the reaction is phase-pure MFM-500(Ni).

An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface

1988 ◽  
Vol 46 ◽  
pp. 884-885
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove ◽  
R. T. Tung
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Defect Density ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Metal Base ◽  
In Situ Experiments ◽  
Potential Applications

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.

The use of transmission and analytical electron microscopy in studying reactions and phase transformations in thin film

1993 ◽  
Vol 51 ◽  
pp. 842-843
Author(s):  
K. Barmak
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Transformations ◽  
Analytical Electron Microscopy ◽  
Ex Situ ◽  
Multilayer Thin Films ◽  
Absolute Concentration ◽  
Analytical Electron ◽  
Deposition Step

Generally, processing of thin films involves several annealing steps in addition to the deposition step. During the annealing steps, diffusion, transformations and reactions take place. In this paper, examples of the use of TEM and AEM for ex situ and in situ studies of reactions and phase transformations in thin films will be presented.The ex situ studies were carried out on Nb/Al multilayer thin films annealed to different stages of reaction. Figure 1 shows a multilayer with dNb = 383 and dAl = 117 nm annealed at 750°C for 4 hours. As can be seen in the micrograph, there are four phases, Nb/Nb3-xAl/Nb2-xAl/NbAl3, present in the film at this stage of the reaction. The composition of each of the four regions marked 1-4 was obtained by EDX analysis. The absolute concentration in each region could not be determined due to the lack of thickness and geometry parameters that were required to make the necessary absorption and fluorescence corrections.

Transmission Electron Microscopy of Epitaxial silicides grown by ultra high vacuum deposition

1989 ◽  
Vol 47 ◽  
pp. 462-463
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
High Vacuum ◽  
High Energy ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Transmission Electron

The silicides CoSi2 and NiSi2 are both metallic with the fee flourite structure and lattice constants which are close to silicon (1.2% and 0.6% smaller at room temperature respectively) Consequently epitaxial cobalt and nickel disilicide can be grown on silicon. If these layers are formed by ultra high vacuum (UHV) deposition (also known as molecular beam epitaxy or MBE) their thickness can be controlled to within a few monolayers. Such ultrathin metal/silicon systems have many potential applications: for example electronic devices based on ballistic transport. They also provide a model system to study the properties of heterointerfaces. In this work we will discuss results obtained using in situ and ex situ transmission electron microscopy (TEM).In situ TEM is suited to the study of MBE growth for several reasons. It offers high spatial resolution and the ability to penetrate many monolayers of material. This is in contrast to the techniques which are usually employed for in situ measurements in MBE, for example low energy electron diffraction (LEED) and reflection high energy electron diffraction (RHEED), which are both sensitive to only a few monolayers at the surface.

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