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Graphitized needle cokes and natural graphites for lithium intercalation

Description: This paper examined effects of heat treatment and milling (before or after heat treatment) on the (electrochemical) intercalating ability of needle petroleum coke; natural graphite particles are included for comparison. 1 tab, 4 figs, 7 refs.
Date: May 10, 1996
Creator: Tran, T.D.; Spellman, L.M.; Pekala, R.W.; Goldberger, W.M. & Kinoshita, K.
Partner: UNT Libraries Government Documents Department

Fluorogermanium(IV) Salts of Graphite -- a System in Equilibrium With Elemental Fluorine

Description: Pyrolytic graphite is not intercalated by GeF{sub 4} alone but is intercalated by GeF{sub 4}/F{sub 2} mixtures to yield, at the intercalation limit, at 20{sup o}, a first-stage material, C{sub 12}GeF{sub 5-6}, which is in equilibrium with gaseous fluorine. GERMANIUM tetrafluoride is a superior fluoride ion acceptor since it can stabilize the O{sub 2}{sup +} ion and the NF{sub 4}{sup +} ion in salts. It is this superior fluoride-ion acceptor capability which must account for our observation that pyrolytic graphite readily intercalates GeF{sub 4} in the presence of fluorine, but does not do so, even with high pressures of GeF{sub 4}, if fluorine is absent, Similar experiments, in which SiF{sub 4} was substituted for GeF{sub 4}, failed to bring about any silicon fluoride intercalation. It has long been known that GeF{sub 4} is a superior fluoride ion acceptor to SiF{sub 4} since, with SF{sub 4}, the former yields the salt (SF{sub 3}{sup +}){sub 2}GeF{sub 6}{sup 2-}, whereas the silicon analogue is not stable at ordinary temperatures and pressures (in spite of the lattice energy of the silicon analogue being slightly more favorable by virtue of the smaller size of SiF{sub 6}{sup 2-}).
Date: February 1, 1980
Creator: McCarron, E. M.; Grannec, Y. J. & Bartlett, N.
Partner: UNT Libraries Government Documents Department

A theoretical study of a carbon lattice system for lithium intercalated carbon anodes

Description: A theoretical study was performed using computational chemistry to describe the intermolecular forces between graphite layers as well as spacing and conformation. It was found that electron correlation and a diffuse basis set were important for this calculation. In addition, the high reactivity of edge sites in lithium intercalated carbon anodes was also investigated. In this case, the reactive sites appear to strongly correlate with the relative distribution of the total atomic spin densities as well as total atomic charges. The spacing of graphite layers and lithium ion separation within an {open_quotes}approximated{close_quotes} lithium intercalated carbon anode was also investigated. The spacing of the carbon layers used in this investigation agrees most closely for that found in disordered carbon lattices.
Date: September 1, 1997
Creator: Scanlon, L.G.; Storch, D.M.; Newton, J.H. & Sandi, G.
Partner: UNT Libraries Government Documents Department

Glass-Like Heat Conduction in Crystalline Semiconductors

Description: The thermal conductivity and structural properties of polycrystalline and single crystal semiconductor type-1 germanium clathrates are reported. Germanium clathrates exhibit thermal conductivities that are typical of amorphous materials. This behavior occurs in spite of their well-defined crystalline structure. The authors employ temperature dependent neutron diffraction data in investigating the displacements of the caged strontium atoms in Sr{sub 8}Ga{sub 16}Ge{sub 30} and their interaction with the polyhedral cages that entrap them. Their aim is to investigate the correlation between the structural properties and the low, glass-like thermal conductivity observed in this compound.
Date: June 13, 1999
Creator: Nolas, G.S.; Cohn, J.L.; Chakoumakos, B.C. & Slack, G.A.
Partner: UNT Libraries Government Documents Department

Electrochemical characterization of orthorhombic Na{sub x}MnO{sub 2} for alkali metal polymer batteries

Description: Electrochemical potential spectroscopy (ECPS) has been used successfully to observe and explain ordering transitions in orthorhombic Na{sub x}MnO{sub 2} as it is discharged in a sodium/polymer cell. Features can be assigned on the basis of sequential filling of sites in the small and then the large tunnels of the structure as the reduction progresses. Intercalation of lithium into Na{sub x}MnO{sub 2} may be less straightforward than that of sodium, and is worthy of investigation by ECPS. Li/Na{sub x}MnO{sub 2} cells have a greater discharge capacity than Na/Na{sub x}MnO{sub 2} cells, suggesting that more than four lithiums per large tunnel can be inserted. (It is also possible, but less likely that more than one lithium can be placed inside the small tunnels.) This implies that the sites for lithium occupancy might be somewhat different than that for sodium. Further investigation into the properties of orthorhombic Na{sub x}MnO{sub 2} and its utility as a positive electrode for rechargeable sodium and lithium cells is presently underway in this laboratory.
Date: April 1, 1995
Creator: Doeff, M.M.; Ding, Lie & DeJonghe, L.C.
Partner: UNT Libraries Government Documents Department

{Beta}-FeOOH, a new positive electrode material for lithium secondary batteries.

Description: Beta-iron oxy-hydroxide, which exhibits a (2x2) tunnel-type structure-similar to that of {alpha}-MnO{sub 2}, was found to intercalate reversibly lithium in the tunnels. This material exhibits a potential slightly higher than 2 V with a capacity of 275 mAh/g and very good cyclic reversibility. X-ray Photoelectron Spectroscopy (XPS) investigation of discharged material showed that iron is reduced to the divalent state, and the lithium incorporated in the tunnels was purely ionic. This explains the good reversibility of this electrode material.
Date: September 11, 1998
Creator: Amine, K.
Partner: UNT Libraries Government Documents Department

Characterization of the passivation layer on disordered carbons in lithium-ion cells

Description: Intercalation anodes of graphite or disordered carbon in rechargeable Li-ion batteries (based on aprotic organic solvents) develop a passivating film during the first intercalation of Li{sup +}. The formation of this film reduces the cycling efficiency and results in excessive consumption of Li{sup +}. The exact nature of this film is not well defined, although there are many similarities in properties to the films that form on Li anodes under similar cycling conditions. In this study we report on characterization studies of films formed during galvanostatic cycling of disordered carbons derived from polymethylacryolintrile (PMAN) in a 1M LiPF{sub 6} solution in ethylene carbonateldimethyl carbonate solution (1:1 by vol.). Complementary tests were also conducted with glass carbon, where intercalation cannot occur. Complex-impedance spectroscopy was the primary measurement technique, supplemented by cyclic voltammetry.
Date: December 1, 1995
Creator: Guidotti, R. & Johnson, B.
Partner: UNT Libraries Government Documents Department

Carbonaceous materials as lithium intercalation anodes

Description: Commercial and polymer-derived carbonaceous materials were examined as lithium intercalation anodes in propylene carbonate (pyrolysis < 1350C, carbons) and ethylene carbonate/dimethyl carbonate (graphites) electrolytes. The reversible capacity (180--355 mAh/g) and the irreversible capacity loss (15--200 % based on reversible capacity) depend on the type of binder, carbon type, morphology, and phosphorus doping concentration. A carbon-based binder was chosen for electrode fabrication, producing mechanically and chemically stable electrodes and reproducible results. Several types of graphites had capacity approaching LiC{sub 6}. Petroleum fuel green cokes doped with phosphorous gave more than a 20 % increase in capacity compared to undoped samples. Electrochemical characteristics are related to SEM, TEM, XRD and BET measurements.
Date: October 1, 1994
Creator: Tran, T.D.; Feikert, J.H.; Mayer, S.T.; Song, X. & Kinoshita, K.
Partner: UNT Libraries Government Documents Department

Organic or organometallic template mediated clay synthesis

Description: A method is given for incorporating diverse varieties of intercalants or templates directly during hydrothermal synthesis of clays such as hectorite or montmorillonite-type layer-silicate clays. For a hectorite layer-silicate clay, refluxing a gel of silica sol, magnesium hydroxide sol and LiF for 2 days with an organic or organometallic intercalant or template results in crystalline products containing either (a) organic dye molecules such as ethyl violet and methyl green, (b) dye molecules such as alcian blue based on a Cu(II)-phthalocyannine complex, or (c) transition metal complexes such as Ru(II)phenanthroline and Co(III)sepulchrate or (d) water-soluble porphyrins and metalloporphyrins. Montmorillonite-type clays are made by the method taught by US patent No. 3,887,454 issued to Hickson, June 13, 1975; however, a variety of intercalants or templates may be introduced. The intercalants or templates should have water-solubility, positive charge, and thermal stability under moderately basic (pH 9-10) aqueous reflux conditions or hydrothermal pressurized conditions for the montmorillonite-type clays.
Date: December 31, 1992
Creator: Gregar, K.C.; Winans, R.E. & Botto, R.E.
Partner: UNT Libraries Government Documents Department

Plasma Synthesis of Lithium Based Intercalation Powders for Solid Polymer Electrolyte Batteries

Description: The invention relates to a process for preparing lithium intercalation compounds by plasma reaction comprising the steps of: forming a feed solution by mixing lithium nitrate or lithium hydroxide or lithium oxide and the required metal nitrate or metal hydroxide or metal oxide and between 10-50% alcohol by weight; mixing the feed solution with O2 gas wherein the O2 gas atomizes the feed solution into fine reactant droplets, inserting the atomized feed solution into a plasma reactor to form an intercalation powder; and if desired, heating the resulting powder to form a very pure single phase product.
Date: January 4, 2005
Creator: Kong, Peter C.; Pink, Robert J. & Nelson, Lee O.
Partner: UNT Libraries Government Documents Department

A new family of superconducting fullerides, Na{sub 3}(NH{sub 3}){sub x}C{sub 60}(x = 2--8)

Description: A series of A{sub 3}C{sub 60} fulleride superconductors (A is an alkali metal) with superconducting transition temperatures ({Tc}s) between 2.5 and 33 K has been reported. The {Tc}s of these materials are closely correlated to their f.c.c. lattice parameters, with the higher {Tc} materials having larger unit cell lengths. Recently, the {Tc} of the superconducting Na{sub 2}CsC{sub 60} has been raised from 10.5 K to 29.6 K by ammonia intercalation. The resulting intercalated compound, NaCs[Na(NH{sub 3}){sub 4}]C{sub 60} has an expanded unit cell compared to the starting material, with a larger cation Na(NH{sub 3}){sub 4+}, occupying the octahedral site. The sodium-doped C{sub 60} with nominal composition Na{sub 3}C{sub 60} however, does not show superconductivity and was reported to undergo a disproportionation reaction into two f.c.c. phases, Na{sub 2}C{sub 60} and Na{sub 6}C{sub 60} below 250 K. Here we report on the ammonia intercalation of Na{sub 3}C{sub 60}. Up to four superconducting phases with {Tc}s occurring near 6.7, 11.5, 13.5 and 16.5 K were observed in the compounds Na{sub 3}(NH{sub 3}){sub x}C{sub 60} (x {approx}2 = 8). All these phases gave significant superconducting shielding fractions (between 15 and 80% at 5 K). These compounds were characterized by use of AC susceptibility and SQUID measurements, TGA and x-ray powder diffraction.
Date: May 1, 1994
Creator: Schlueter, J. A.; Smart, J. L. & Wang, H. H.
Partner: UNT Libraries Government Documents Department

Quantum lattice fluctuations in a 1-dimensional charge-density-wave material: Luminescence and resonance Raman studies of an MX solid

Description: Luminescence spectra, both emission and excitation, and the excitation dependence of the resonance Raman (RR) spectra were measured for a 1-dimensional charge-density-wave solid, [Pt(L){sub 2}Cl{sub 2}][Pt(L){sub 2}](ClO{sub 4}){sub 4} ; L=1, 2-diaminoethane. The luminescence experiments support the existence of tail states in the band gap region, which indicate the presence of disorder. In contrast, the RR measurements conclusively demonstrated that the effects of static structural disorder on the vibrational spectroscopy can be neglected. This apparently paradoxical result can be explained by considering the zero-point motion of the lattice. The experimental results are compared to recent theoretical models.
Date: February 1, 1993
Creator: Long, F. H.; Love, S. P. & Swanson, B. I.
Partner: UNT Libraries Government Documents Department

Is K{sub 3}C{sub 60} a line phase?

Description: We present x-ray diffraction evidence that K{sub I}C{sub 60} with x as low as 1.6 exhibits phase-pure fcc structures over some temperature range. These results have implications for the equilibrium binary phase diagram, and for the possibility of testing the hypothesis that fullerene superconductors are doped Mott-Hubbard insulators.
Date: July 1, 1993
Creator: Zhu, Q.; Fischer, J. E. & Cox, D. E.
Partner: UNT Libraries Government Documents Department

Feasibility of Large-Scale Ocean CO2 Sequestration

Description: Scientific knowledge of natural clathrate hydrates has grown enormously over the past decade, with spectacular new findings of large exposures of complex hydrates on the sea floor, the development of new tools for examining the solid phase in situ, significant progress in modeling natural hydrate systems, and the discovery of exotic hydrates associated with sea floor venting of liquid CO{sub 2}. Major unresolved questions remain about the role of hydrates in response to climate change today, and correlations between the hydrate reservoir of Earth and the stable isotopic evidence of massive hydrate dissociation in the geologic past. The examination of hydrates as a possible energy resource is proceeding apace for the subpermafrost accumulations in the Arctic, but serious questions remain about the viability of marine hydrates as an economic resource. New and energetic explorations by nations such as India and China are quickly uncovering large hydrate findings on their continental shelves. In this report we detail research carried out in the period October 1, 2007 through September 30, 2008. The primary body of work is contained in a formal publication attached as Appendix 1 to this report. In brief we have surveyed the recent literature with respect to the natural occurrence of clathrate hydrates (with a special emphasis on methane hydrates), the tools used to investigate them and their potential as a new source of natural gas for energy production.
Date: August 31, 2008
Creator: Brewer, Peter
Partner: UNT Libraries Government Documents Department

Gas Hydrate Research Database and Web Dissemination Channel

Description: To facilitate advances in application of technologies pertaining to gas hydrates, a United States database containing experimentally-derived information about those materials was developed. The Clathrate Hydrate Physical Property Database (NIST Standard Reference Database {number_sign} 156) was developed by the TRC Group at NIST in Boulder, Colorado paralleling a highly-successful database of thermodynamic properties of molecular pure compounds and their mixtures and in association with an international effort on the part of CODATA to aid in international data sharing. Development and population of this database relied on the development of three components of information-processing infrastructure: (1) guided data capture (GDC) software designed to convert data and metadata into a well-organized, electronic format, (2) a relational data storage facility to accommodate all types of numerical and metadata within the scope of the project, and (3) a gas hydrate markup language (GHML) developed to standardize data communications between 'data producers' and 'data users'. Having developed the appropriate data storage and communication technologies, a web-based interface for both the new Clathrate Hydrate Physical Property Database, as well as Scientific Results from the Mallik 2002 Gas Hydrate Production Research Well Program was developed and deployed at http://gashydrates.nist.gov.
Date: September 30, 2009
Creator: Frenkel, Micheal; Kroenlein, Kenneth; Diky, V; Chirico, R.D.; Kazakow, A.; Muzny, C.D. et al.
Partner: UNT Libraries Government Documents Department

Novel Graphite Salts and Their Electrical Conductivities

Description: A set of novel first stage graphite salts of general formula C{sub 8}{sup +}MF{sub 6}{sup -} has been prepared (M = Os, Ir, As). Single crystal X-ray diffraction studies indicate that these salts are hexagonal with a {approx} 4.9 and c {approx} 8.1 {angstrom}. The unit cell volume indicates that the anions are closely packed in the galleries. Platinum hexafluoride, which is the most powerful oxidizer of the third transition series, forms a first stage compound, which analytical, structural, and magnetic studies establish as C{sub 12}{sup 2+}PtF{sub 6}{sup 2-}. In this salt the anions are not close packed, but the electron withdrawal from the graphite planes is greater than for the C{sub 8}{sup +}MF{sub 6}{sup -} series. The variation in the electrical conductivity (in the a-b plane), as a function of composition, has been investigated with the OsF{sub 6}, IrF{sub 6}, PtF{sub 6} and AsF{sub 5} intercalates. For OsF{sub 6} and IrF{sub 6}, the conductance per plane of graphite is found to be a maximum at approximately C{sub 24}MF{sub 6} (second stage); the conductivity being an order of magnitude greater than that of the parent material. Intercalation beyond C{sub 24}MF{sub 6} leads to a marked decrease in conductivity. C{sub 8}MF{sub 6} is comparable in conductivity with the parent graphite. This behavior contrasts with the graphite/AsF{sub 5} system in which a steady increase in conductance per graphite plane with increasing AsF{sub 5} content is observed. For the PtF{sub 6} system, the second as well as the first stage materials are poorly conducting.
Date: February 1, 1980
Creator: Bartlett, N.; McCarron, E. M.; McQuillan, B. W. & Thompson, T. E.
Partner: UNT Libraries Government Documents Department

Development of a high-power lithium-ion battery.

Description: Safety is a key concern for a high-power energy storage system such as will be required in a hybrid vehicle. Present lithium-ion technology, which uses a carbon/graphite negative electrode, lacks inherent safety for two main reasons: (1) carbon/graphite intercalates lithium at near lithium potential, and (2) there is no end-of-charge indicator in the voltage profile that can signal the onset of catastrophic oxygen evolution from the cathode (LiCoO{sub 2}). Our approach to solving these safety/life problems is to replace the graphite/carbon negative electrode with an electrode that exhibits stronger two-phase behavior further away from lithium potential, such as Li{sub 4}Ti{sub 5}O{sub 12}. Cycle-life and pulse-power capability data are presented in accordance with the Partnership for a New Generation of Vehicles (PNGV) test procedures, as well as a full-scale design based on a spreadsheet model.
Date: September 2, 1998
Creator: Jansen, A. N.
Partner: UNT Libraries Government Documents Department

Li ion conductors based on laponite/poly(ethylene oxide) composites

Description: Synthesis and characterization of single ion conducting poly(ethylene oxide) (PEO)/Li-laponite nanocomposites are reported. The amount of PEO that can be intercalated into laponite, a synthetic hectorite with high surface area, ranges from about 0.7g/g Li-laponite when the polymer average molecular weight is 1,000 or above, to about 1 g/g for oligomers of average molecular weight 500. The interlayer spacing increases from about 10 {angstrom} in the dry clay to 20--24 {angstrom} in the nanocomposites, depending upon polymer molecular weight, and the average particle size increases proportionally, but is still in the sub-micron range. AC impedance measurements on the clear, slightly brittle, self-supporting films indicate that the nanocomposite conductivity is greatly enhanced over that of the dry clay. A maximum of about 10{sup {minus}6} S/cm at 80 C is obtained for materials containing a slight excess of polymer, and conductivities of nanocomposites containing PEO were generally higher than that of those containing oxymethylene linked polyethylene glycol (amorphous PEOs). Suggestions for further improving conductivity and mechanical properties of these novel materials are presented.
Date: November 1, 1997
Creator: Doeff, M. M. & Reed, J. S.
Partner: UNT Libraries Government Documents Department

First-principles study of Se-intercalated graphite

Description: Se-intercalated graphite compounds (Se-GICs) are considered as promising candidates for room-temperature thermoelectric cooling devices. Here the authors analyze the crystallographic structure and electronic properties of these materials within the framework of density-functional theory. First, the Adaptive-Coordinate Real-space Electronic Structure (ACRES) code is used to determine the stable structure of a representative stage-2 Se-GIC by relaxing atomic positions. The stable configuration is found to be a pendant-type structure, in which each selenium is bonded covalently to two atoms within the same carbon layer, causing a local distortion of the in-plane conjugation of the graphite. Then, they use the full potential linearized augmented plane wave (FP-LAPW) method to calculate the electronic band structure of the material and discuss its properties. Near the Fermi energy E{sub F}, there are wide bands originating from the host graphitic electronic structure and a few very narrow bands mainly of Se 4p character. The latter bands contribute to high peaks in the density of states close to E{sub F}. They show that this feature, although typical of many good thermoelectrics, does not necessarily imply high thermopower in the case of Se-GICs.
Date: May 11, 2000
Partner: UNT Libraries Government Documents Department


Description: The subject of catalytic syngas conversions to fuels and chemicals is well studied (1--3). But globally, the recent focus is on development of technologies that offer an economical route to desired products (4). Economical transport of natural gas from remote locations and within clathrate hydrates is of continuing interest at Brookhaven National Laboratory (BNL). Under this project, a Liquid Phase Low Temperature (LPLT) concept is being applied to attain highly efficient transformations of natural-gas derived syngas to specific products. Furthermore, a more precise term ``Atom Economy'' has been recently introduced by Trost to describe development of highly efficient homogeneously catalyzed synthesis of organic molecules (5). Taken from reference 5, the term ``Atom Economy'' is defined as maximizing the number of atoms of all raw materials that end up in the product with any other reactant required on in catalytic amount. For application to methane transformations that may involve one or more steps, atom economy of each of these steps is critical. The authors, therefore, consider atom-economy synonymous with overall energy efficiency of a process. This paper describes potential liquid products from catalytic syngas conversions, i.e. gas to liquids (GTL) technologies and process considerations that are necessary for economical transport of natural gas. As such, the present study defines an atom-economical standard to directly compare competing GTL technologies.
Date: March 1, 1999
Partner: UNT Libraries Government Documents Department

Molecular models for the intercalation of hydrogen molecules into modified graphites

Description: Carbonized aerogels have been proposed as a medium for the storage of H{sub 2} gas. Quantum chemical calculations were performed on a series of substituted polyaromatic ring compounds. Parallel ``sandwiches`` of these compounds were used as a model of graphite. Hydrogen was introduced between the compounds as a model of H{sub 2} intercalated into graphite. It was found that it required work to insert the H{sub 2} into most of the compounds, except when the presence of the hydrogen allowed the compound to find a new configuration with a lower energy.
Date: December 1, 1995
Creator: Calef, D. F.
Partner: UNT Libraries Government Documents Department

Potential Modulated Intercalation Of Alkali Cations Into Metal Hexacyanoferrate Coated Electrodes

Description: Nickel hexacyanoferrate is a polynuclear inorganic ion intercalation material that loads (intercalates) and elutes (deintercalates) alkali cations from its structure when electrochemically reduced and oxidized, respectively. Nickel hexacyanoferrate (NiHCF) is known to preferentially intercalate cesium over all other alkali cations, thus providing a basis for a separation scheme that can tackle DOE's radiocesium contamination problem. This program studied fundamental issues in alkali cation intercalation and deintercalation in nickel hexacyanoferrate compounds, with the goal of (1) quantifying the ion exchange selectivity properties for cation mixtures, (2) enhancing ion exchange capacities, and (3) and understanding the electrochemically-switched ion exchange process (ESIX).
Date: June 1, 2001
Creator: Schwartz, Daniel T.
Partner: UNT Libraries Government Documents Department

Homogeneous Precipitation of Nickel Hydroxide Powders

Description: Precipitation and characterization of nickel hydroxide powders were investigated. A comprehensive precipitation model incorporating the metal ion hydrolysis, complexation and precipitation reactions was developed for the production of the powders with urea precipitation method. Model predictions on Ni{sup 2+} precipitation rate were confirmed with precipitation experiments carried out at 90 C. Experimental data and model predictions were in remarkable agreement. Uncertainty in the solubility product data of nickel hydroxides was found to be the large contributor to the error. There were demonstrable compositional variations across the particle cross-sections and the growth mechanism was determined to be the aggregation of primary crystallites. This implied that there is a change in the intercalate chemistry of the primary crystallites with digestion time. Predicted changes in the concentrations of simple and complex ions in the solution support the proposed mechanism. The comprehensive set of hydrolysis reactions used in the model described above allows the investigation of other systems provided that accurate reaction constants are available. the fact that transition metal ions like Ni{sup 2+} form strong complexes with ammonia presents a challenge in the full recovery of the Ni{sup 2+}. On the other hand, presence of Al{sup 3+} facilitates the complete precipitation of Ni{sup 2+} in about 3 hours of digestion. A challenge in their predictive modeling studies had been the fact that simultaneous incorporation of more than one metal ion necessitates a different approach than just using the equilibrium constants of hydrolysis, complexation and precipitation reactions. Another limitation of using equilibrium constants is that the nucleation stage of digestion, which is controlled mainly by kinetics, is not fully justified. A new program released by IBM Almaden Research Center (Chemical Kinetics Simulator{trademark}, Version 1.01) lets the user change the order of kinetic components of a reaction which was set to stoichiometric constant with which ...
Date: December 12, 2003
Creator: Mavis, Bora
Partner: UNT Libraries Government Documents Department