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Sample records for ionic conductivity

  1. Super ionic conductive glass

    DOEpatents

    Susman, S.; Volin, K.J.

    Described is an ionically conducting glass for use as a solid electrolyte in a power or secondary cell containing an alkali metal-containing anode and a cathode separated by an alkali metal ion conducting glass having an ionic transference number of unity and the general formula: A/sub 1 + x/D/sub 2-x/3/Si/sub x/P/sub 3 - x/O/sub 12 - 2x/3/, wherein A is a network modifier for the glass and is an alkali metal of the anode, D is an intermediate for the glass and is selected from the class consisting of Zr, Ti, Ge, Al, Sb, Be, and Zn and X is in the range of from 2.25 to 3.0. Of the alkali metals, Na and Li are preferred and of the intermediate, Zr, Ti and Ge are preferred.

  2. Super ionic conductive glass

    DOEpatents

    Susman, Sherman; Volin, Kenneth J.

    1984-01-01

    An ionically conducting glass for use as a solid electrolyte in a power or secondary cell containing an alkali metal-containing anode and a cathode separated by an alkali metal ion conducting glass having an ionic transference number of unity and the general formula: A.sub.1+x D.sub.2-x/3 Si.sub.x P.sub.3-x O.sub.12-2x/3, wherein A is a network modifier for the glass and is an alkali metal of the anode, D is an intermediate for the glass and is selected from the class consisting of Zr, Ti, Ge, Al, Sb, Be, and Zn and X is in the range of from 2.25 to 3.0. Of the alkali metals, Na and Li are preferred and of the intermediate, Zr, Ti and Ge are preferred.

  3. Lithium ion conducting ionic electrolytes

    DOEpatents

    Angell, C.A.; Xu, K.; Liu, C.

    1996-01-16

    A liquid, predominantly lithium-conducting, ionic electrolyte is described which has exceptionally high conductivity at temperatures of 100 C or lower, including room temperature. It comprises molten lithium salts or salt mixtures in which a small amount of an anionic polymer lithium salt is dissolved to stabilize the liquid against recrystallization. Further, a liquid ionic electrolyte which has been rubberized by addition of an extra proportion of anionic polymer, and which has good chemical and electrochemical stability, is described. This presents an attractive alternative to conventional salt-in-polymer electrolytes which are not cationic conductors. 4 figs.

  4. Lithium ion conducting ionic electrolytes

    DOEpatents

    Angell, C. Austen; Xu, Kang; Liu, Changle

    1996-01-01

    A liquid, predominantly lithium-conducting, ionic electrolyte is described which has exceptionally high conductivity at temperatures of 100.degree. C. or lower, including room temperature. It comprises molten lithium salts or salt mixtures in which a small amount of an anionic polymer lithium salt is dissolved to stabilize the liquid against recrystallization. Further, a liquid ionic electrolyte which has been rubberized by addition of an extra proportion of anionic polymer, and which has good chemical and electrochemical stability, is described. This presents an attractive alternative to conventional salt-in-polymer electrolytes which are not cationic conductors.

  5. Quantized ionic conductance in nanopores

    SciTech Connect

    Zwolak, Michael; Lagerqvist, Johan; Di Ventra, Massimilliano

    2009-01-01

    Ionic transport in nanopores is a fundamentally and technologically important problem in view of its ubiquitous occurrence in biological processes and its impact on DNA sequencing applications. Using microscopic calculations, we show that ion transport may exhibit strong non-liDearities as a function of the pore radius reminiscent of the conductance quantization steps as a function of the transverse cross section of quantum point contacts. In the present case, however, conductance steps originate from the break up of the hydration layers that form around ions in aqueous solution. Once in the pore, the water molecules form wavelike structures due to multiple scattering at the surface of the pore walls and interference with the radial waves around the ion. We discuss these effects as well as the conditions under which the step-like features in the ionic conductance should be experimentally observable.

  6. Ionic Conduction in Nanocrystalline Materials

    DTIC Science & Technology

    2000-02-10

    photo- largely due to oxygen desorption from particle voltaic cells and as the photocatalyst in water surfaces. The latter interpretation...and Tuller [22] prepared dense (-95%) temperature, where bulk reduction was observed. At compacts of TiO2 with the anatase phase. The lower... TiO2 , evidence preparation. is mixed. Nanocrystalline rutile appears to exhibit higher ionic conductivity than single crystal rutile while

  7. Counterion condensation and ionic conductivity

    NASA Astrophysics Data System (ADS)

    Penafiel, L. Miguel; Litovitz, Theodore A.

    1992-02-01

    The occurrence of counterion condensation is demonstrated through measurements of the incremental ionic conductivity of pH buffered Na polyacrylate solutions. pH values were selected to allow variation of the charge density parameter ξ in the range between 0.4 and 2.8, that is, across ξ=1, the theoretical critical level for counterion condensation. The results show two regions where the incremental conductivity, ΔσP, varies differently with ξ. For ξ<1.3, ΔσP remains relatively constant. A sharp drop in ΔσP is observed between ξ=1.3 and ξ=1.7 corresponding to the onset of counterion condensation. It is suggested that this discontinuity reflects a drastic change in the polyion mobility caused by a structural rearrangement of the macromolecule. For ξ≳1.7, ΔσP decreases with approximately constant slope. This latter behavior agrees qualitatively but not quantitatively with the prediction of the counterion condensation model.

  8. Ionic Conductivity of Nanostructured Block Copolymer and Ionic Liquid Membranes

    NASA Astrophysics Data System (ADS)

    Hoarfrost, Megan L.; Virgili, Justin M.; Segalman, Rachel A.

    2010-03-01

    Block copolymer and ionic liquid mixtures are of interest for creating ionically conductive, thermally stable, and nanostructured membranes. For mixtures of poly(styrene-b-2-vinylpyridine) (S2VP) and the ionic liquid bis(trifluoromethanesulfonyl)imide ([Im][TFSI]), nanostructured ion-conducting domains are formed due to [Im][TFSI] selectively residing in the P2VP domains of the block copolymer. The dependence of ionic conductivity on temperature, ionic liquid loading, and volume fraction of PS in the neat block copolymer was investigated for membranes with the matrix phase being P2VP/[Im][TFSI]. It was determined that the temperature dependence of conductivity follows the Vogel-Tamman-Fulcher equation, with the activation energy determined by the ratio of [Im][TFSI] to 2VP monomers. The overall weight fraction of [Im][TFSI] in the mixtures, however, is the dominating factor determining conductivity, regardless of PS volume fraction. The insight gained from this work will be important for further investigation into the effect on the ion transport properties of ionic liquids when confined to minority nanostructured domains.

  9. Low frequency ionic conduction across liquid interfaces

    NASA Astrophysics Data System (ADS)

    Solis, Francisco J.; Guerrero, Guillermo Ivan; Olvera de La Cruz, Monica

    Ionic conduction in liquid media is a central component of many recently proposed technologies. As in the case of solid state systems, the presence of heterogeneous media gives rise to interesting nonlinear phenomena. We present simulations and theoretical analysis of the low frequency ionic conduction in a two-liquid system. In the case analyzed, the conduction is driven by an electric field perpendicular to the liquid-liquid interface. We show that the dielectric contrast between the liquids produces non-linear effects in the effective conductivity of the system and discuss the effects of the ion solubility in the media.

  10. High H- ionic conductivity in barium hydride

    NASA Astrophysics Data System (ADS)

    Verbraeken, Maarten C.; Cheung, Chaksum; Suard, Emmanuelle; Irvine, John T. S.

    2015-01-01

    With hydrogen being seen as a key renewable energy vector, the search for materials exhibiting fast hydrogen transport becomes ever more important. Not only do hydrogen storage materials require high mobility of hydrogen in the solid state, but the efficiency of electrochemical devices is also largely determined by fast ionic transport. Although the heavy alkaline-earth hydrides are of limited interest for their hydrogen storage potential, owing to low gravimetric densities, their ionic nature may prove useful in new electrochemical applications, especially as an ionically conducting electrolyte material. Here we show that barium hydride shows fast pure ionic transport of hydride ions (H-) in the high-temperature, high-symmetry phase. Although some conductivity studies have been reported on related materials previously, the nature of the charge carriers has not been determined. BaH2 gives rise to hydride ion conductivity of 0.2 S cm-1 at 630 °C. This is an order of magnitude larger than that of state-of-the-art proton-conducting perovskites or oxide ion conductors at this temperature. These results suggest that the alkaline-earth hydrides form an important new family of materials, with potential use in a number of applications, such as separation membranes, electrochemical reactors and so on.

  11. Optimization of ionic conductivity in doped ceria

    PubMed Central

    Andersson, David A.; Simak, Sergei I.; Skorodumova, Natalia V.; Abrikosov, Igor A.; Johansson, Börje

    2006-01-01

    Oxides with the cubic fluorite structure, e.g., ceria (CeO2), are known to be good solid electrolytes when they are doped with cations of lower valence than the host cations. The high ionic conductivity of doped ceria makes it an attractive electrolyte for solid oxide fuel cells, whose prospects as an environmentally friendly power source are very promising. In these electrolytes, the current is carried by oxygen ions that are transported by oxygen vacancies, present to compensate for the lower charge of the dopant cations. Ionic conductivity in ceria is closely related to oxygen-vacancy formation and migration properties. A clear physical picture of the connection between the choice of a dopant and the improvement of ionic conductivity in ceria is still lacking. Here we present a quantum-mechanical first-principles study of the influence of different trivalent impurities on these properties. Our results reveal a remarkable correspondence between vacancy properties at the atomic level and the macroscopic ionic conductivity. The key parameters comprise migration barriers for bulk diffusion and vacancy–dopant interactions, represented by association (binding) energies of vacancy–dopant clusters. The interactions can be divided into repulsive elastic and attractive electronic parts. In the optimal electrolyte, these parts should balance. This finding offers a simple and clear way to narrow the search for superior dopants and combinations of dopants. The ideal dopant should have an effective atomic number between 61 (Pm) and 62 (Sm), and we elaborate that combinations of Nd/Sm and Pr/Gd show enhanced ionic conductivity, as compared with that for each element separately. PMID:16478802

  12. Structure, ionic conductivity and mobile carrier density in fast ionic conducting chalcogenide glasses

    SciTech Connect

    Yao, Wenlong

    2006-01-01

    This thesis consists of six sections. The first section gives the basic research background on the ionic conduction mechanism in glass, polarization in the glass, and the method of determining the mobile carrier density in glass. The proposed work is also included in this section. The second section is a paper that characterizes the structure of MI + M2S + (0.1 Ga2S3 + 0.9 GeS2) (M = Li, Na, K and Cs) glasses using Raman and IR spectroscopy. Since the ionic radius plays an important role in determining the ionic conductivity in glasses, the glass forming range for the addition of different alkalis into the basic glass forming system 0.1 Ga2S3 + 0.9 GeS2 was studied. The study found that the change of the alkali radius for the same nominal composition causes significant structure change to the glasses. The third section is a paper that investigates the ionic conductivity of MI + M2S + (0.1Ga2S3 + 0.9 GeS2) (M = Li, Na, K and Cs) glasses system. Corresponding to the compositional changes in these fast ionic conducting glasses, the ionic conductivity shows changes due to the induced structural changes. The ionic radius effect on the ionic conductivity in these glasses was investigated. The fourth section is a paper that examines the mobile carrier density based upon the measurements of space charge polarization. For the first time, the charge carrier number density in fast ionic conducting chalcogenide glasses was determined. The experimental impedance data were fitted using equivalent circuits and the obtained parameters were used to determine the mobile carrier density. The influence of mobile carrier density and mobility on the ionic conductivity was separated. The fifth section is a paper that studies the structures of low-alkali-content Na2S + B2S3 (x ≤ 0.2) glasses by neutron and synchrotron x-ray diffraction

  13. Acetonitrile boosts conductivity of imidazolium ionic liquids.

    PubMed

    Chaban, Vitaly V; Voroshylova, Iuliia V; Kalugin, Oleg N; Prezhdo, Oleg V

    2012-07-05

    We apply a new methodology in the force field generation (Phys. Chem. Chem. Phys.2011, 13, 7910) to study binary mixtures of five imidazolium-based room-temperature ionic liquids (RTILs) with acetonitrile (ACN). Each RTIL is composed of tetrafluoroborate (BF(4)) anion and dialkylimidazolium (MMIM) cations. The first alkyl group of MIM is methyl, and the other group is ethyl (EMIM), butyl (BMIM), hexyl (HMIM), octyl (OMIM), and decyl (DMIM). Upon addition of ACN, the ionic conductivity of RTILs increases by more than 50 times. It significantly exceeds an impact of most known solvents. Unexpectedly, long-tailed imidazolium cations demonstrate the sharpest conductivity boost. This finding motivates us to revisit an application of RTIL/ACN binary systems as advanced electrolyte solutions. The conductivity correlates with a composition of ion aggregates simplifying its predictability. Addition of ACN exponentially increases diffusion and decreases viscosity of the RTIL/ACN mixtures. Large amounts of ACN stabilize ion pairs, although they ruin greater ion aggregates.

  14. Anisotropic ionic conductivities in lyotropic supramolecular liquid crystals.

    PubMed

    Huang, Youju; Cong, Yuanhua; Li, Junjun; Wang, Daoliang; Zhang, Jingtuo; Xu, Lu; Li, Weili; Li, Liangbin; Pan, Guoqiang; Yang, Chuanlu

    2009-12-28

    The designed aromatic amide discotic molecule with sulfonic acid groups at its periphery exhibits a hexagonal supramolecular columnar liquid crystalline phase, which leads to the achievement of anisotropic ionic conductivity through macroscopically aligning the ionic channels.

  15. Ionic conductivity in crystalline polymer electrolytes.

    PubMed

    Gadjourova, Z; Andreev, Y G; Tunstall, D P; Bruce, P G

    2001-08-02

    Polymer electrolytes are the subject of intensive study, in part because of their potential use as the electrolyte in all-solid-state rechargeable lithium batteries. These materials are formed by dissolving a salt (for example LiI) in a solid host polymer such as poly(ethylene oxide) (refs 2, 3, 4, 5, 6), and may be prepared as both crystalline and amorphous phases. Conductivity in polymer electrolytes has long been viewed as confined to the amorphous phase above the glass transition temperature, Tg, where polymer chain motion creates a dynamic, disordered environment that plays a critical role in facilitating ion transport. Here we show that, in contrast to this prevailing view, ionic conductivity in the static, ordered environment of the crystalline phase can be greater than that in the equivalent amorphous material above Tg. Moreover, we demonstrate that ion transport in crystalline polymer electrolytes can be dominated by the cations, whereas both ions are generally mobile in the amorphous phase. Restriction of mobility to the lithium cation is advantageous for battery applications. The realization that order can promote ion transport in polymers is interesting in the context of electronically conducting polymers, where crystallinity favours electron transport.

  16. Voltage charging enhances ionic conductivity in gold nanotube membranes.

    PubMed

    Gao, Peng; Martin, Charles R

    2014-08-26

    Ionically conductive membranes are used in many electrochemical processes and devices, including batteries, fuel cells, and electrolyzers. In all such applications, it is advantageous to use membranes with high ionic conductivity because membrane resistance causes a voltage loss suffered by the cell. We describe here a method for enhancing ionic conductivity in membranes containing small diameter (4 nm) gold nanotubes. This entails making the gold nanotube membrane the working electrode in an electrochemical cell and applying a voltage to the membrane. We show here that voltage charging in this way can increase membrane ionic conductivity by over an order of magnitude. When expressed in terms of the ionic conductivity of the electrolyte, κ, within an individual voltage-charged tube, the most negative applied voltage yielded a κ comparable to that of 1 M aqueous KCl, over 2 orders of magnitude higher than κ of the 0.01 M KCl solution contacting the membrane.

  17. Electrical Conduction and Dielectric Relaxation in Ionically Conducting Glasses.

    NASA Astrophysics Data System (ADS)

    Syed, Rahmathullah

    An experimental study was conducted to address a number of important topics relevant to the analysis and basic understanding of ionic transport in glass. Very precise electrical conductivity and relaxation measurements were carried out over the frequency range 10('-2) to 10('5) Hz and the temperature range -11 to 300(DEGREES)C for a series of glasses of molar composition 25{XNa(,2)O+(1 -X)K(,2)O}-5Al(,2)O(,3)-70SiO(,2) with 0.95 (LESSTHEQ) X (LESSTHEQ) 1. Sodium ion tracer diffusion data, obtained on these glasses in another laboratory, are also reported. Important results of the study are as follows: (1) The experimental plot of complex resistivity (rho)* was found not to be an arc of a circle with its center below the real axis, as suggested in the literature. Rather, it was found experimentally and shown theoretically that the (rho)* plot must approach the origin at high frequencies and intersect the real axis at low frequencies, in both cases at a 90(DEGREES) angle. (2) The functional form of the Arrhenius equation for temperature dependence of electrical conductivity of glass was investigated. The data analysis suggested that the pre-exponential term in the Arrhenius conductivity equation is temperature independent. (3) A critical test of Jonscher's so called "universal" law for the high frequency dielectric response was carried out. The curves predicted by the Jonscher's law for the frequency dependence of dielectric constant (epsilon)' and real part of complex conductivity (sigma)(DEGREES) did not fit the experimental data. (4) Tracer diffusion data have been compared with the electrical conductivity data to characterize the correlation effects on the Na('+) ion diffusion mechanism. (5) When one alkali in a glass is progressively replaced by another alkali, keeping the total alkali content constant, a pronounced minimum is obtained in the electrical conductivity as a function of composition. This phenomenon is known as the "mixed-alkali (MA) effect". The

  18. Morphology and Ionic Conductivity of Block Copolymer--Ionic Liquid Systems

    NASA Astrophysics Data System (ADS)

    Hoarfrost, M. L.; Virgili, J. M.; Kerr, J. B.; Segalman, R. A.

    2009-03-01

    Block copolymer--ionic liquid systems are of interest for ion exchange membranes due to the ionic conductivity and thermal stability of the ionic liquid combined with the thermal stability and morphological control arising from a structural component in a block copolymer. It is anticipated that the morphology and connectivity of the resulting structural and ionic liquid-containing nanodomains will affect conduction properties. This relationship was investigated for poly(styrene-b-2-vinylpyridine) (S2VP) in ionic liquids composed of varying molar ratios of imidazole and bis(trifluoromethanesulfonyl)imide (Im:TFSI). A stoichiometrically balanced ionic liquid (1:1 Im:TFSI) swells the 2VP lamellar domains for copolymer concentrations as low as 60wt%. With 9:1 Im:TFSI the lamellar structure tolerates more swelling, forming lamellar structures with as little as 30wt% copolymer. Ionic conductivities were derived from AC impedance measurements. The S2VP-Im:TFSI systems, characterized by microphase separated domains, demonstrate ionic conductivities comparable to those of P2VP--ionic liquid systems when normalized by 2VP (monomer) to Im:TFSI ratio.

  19. Morphology-enhanced conductivity in dry ionic liquids.

    PubMed

    Erbaş, Aykut; de la Cruz, Monica Olvera

    2016-03-07

    Ionic liquids exhibit fascinating nanoscale morphological phases and are promising materials for energy storage applications. Liquid crystalline order emerges in ionic liquids with specific chemical structures. Here, we investigate the phase behaviour and related ionic conductivities of dry ionic liquids, using extensive molecular dynamics simulations. Temperature dependence, properties of polymeric tail and excluded volume symmetry of the amphiphilic ionic liquid molecules are investigated in large scale systems with both short and long-range Coulomb interactions. Our results suggest that by adjusting stiffness and steric interactions of the amphiphilic molecules, lamellar or 3D continuous phases result in these molecular salts. The resulting phases are composed of ion rich and ion pure domains. In 3D phases, ion rich clusters form ionic channels and have significant effects on the conductive properties of the observed nano-phases. If there is no excluded-volume asymmetry along the molecules, mostly lamellar phases with anisotropic conductivities emerge. If the steric interactions become asymmetric, lamellar phases are replaced by complex 3D continuous phases. Within the temperature ranges for which morphological phases are observed, conductivities exhibit low-temperature maxima in accord with experiments on ionic liquid crystals. Stiffer molecules increase the high-conductivity interval and strengthen temperature-resistance of morphological phases. Increasing the steric interactions of cation leads to higher conductivities. Moreover, at low monomeric volume fractions and at low temperatures, cavities are observed in the nano-phases of flexible ionic liquids. We also demonstrate that, in the absence of electrostatic interactions, the morphology is distorted. Our findings inspire new design principles for room temperature ionic liquids and help explain previously-reported experimental data.

  20. Morphology-induced low temperature conductivity in ionic liquids

    NASA Astrophysics Data System (ADS)

    Erbas, Aykut; Olvera de La Cruz, Monica; Olvera de la Cruz Team

    Ionic liquids exhibit nano-scale liquid crystalline order depending on the polymeric details of salt molecules. The resulting morphology and temperature behavior are key factors in determining the room temperature conductivity of ionic liquids. Here we discuss the phase behavior and related ionic conductivities of dry ionic liquids with volume fractions close to unity by using extensive molecular dynamics simulations. Temperature dependence, effective persistence length of tails, and excluded volume symmetry of amphiphilic ionic liquid molecules are investigated in large scale systems with short and long-range electrostatics. Our results suggest that by adjusting stiffness of the amphiphilic molecules and excluded volume interactions, lamellar or interconnected 3D phases can be obtained. Resulting phases have significant effects on the conductive properties. If there is no excluded volume asymmetry along the molecules, mostly lamellar phases with anisotropic conductivities emerge. If the excluded volume interactions become asymmetric, lamellar phases are replaced by interconnected phases consist of charged groups. Within temperature ranges that morphological phases are observed, conductivities exhibit low-temperature maxima in accord with experiments of ionic liquid-based liquid Center of Bio-inspried Energy Center (CBES).

  1. Structure, morphology and ionic conductivity of solid polymer electrolyte

    SciTech Connect

    Dey, Arup; Karan, S.; Dey, Ashis; De, S.K.

    2011-11-15

    Graphical abstract: Two-dimensional atomic force image of pure polyethylene oxide presents a crystallized network of regular spherulites developing spirals and branches of well distributed surface contours. Highlights: {yields} The incorporation of ceria significantly modifies the morphology of polyethylene oxide (PEO)-KI complex. {yields} The ionic conductivity increases by about two orders of magnitude by the addition of ceria nanoparticles. {yields} Ionic conductivity as a function of ceria concentration reveals two maxima. {yields} Grain boundary effect of nanofiller, strong Lewis acid-base interaction between PEO and nanosized ceria, change of conformation of PEO molecule and epitaxial effect of ceria nanoparticles control the ionic conductivity of composite polymer electrolyte. -- Abstract: Polyethylene oxide (PEO) complexed with potassium iodide (KI) is synthesized to investigate the ionic conductivity of alkaline based polymer electrolytes. The structural and morphological characterizations of the nanocomposite polymer electrolytes are performed by X-ray diffractometry (XRD), atomic force microscopy (AFM), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) measurements. The ionic conductivity increases with the increase of KI concentration up to about 20 wt.%. The effect of nanosized ceria (CeO{sub 2} {approx} 10 nm) fillers on ionic conductivity in PEO-KI polymer electrolyte is also carried out, keeping PEO to KI wt.% ratio 80:20 and 85:15. The result reveals that the addition of ceria nanoparticles enhances the conductivity by two orders of magnitude. The presence of ceria at the highest concentration induces the same molecular environment within PEO chain as that of undoped PEO. Temperature dependence of ionic conductivity follows Arrhenius mechanism.

  2. Observation of highly decoupled conductivity in protic ionic conductors.

    PubMed

    Wojnarowska, Zaneta; Wang, Yangyang; Paluch, Krzysztof J; Sokolov, Alexei P; Paluch, Marian

    2014-05-21

    Ionic liquids (ILs) are key materials for the development of a wide range of emerging technologies. Protic ionic liquids, an important class of ILs, have long been envisioned as promising anhydrous electrolytes for fuel cells. It is well known that in comparison to all other cations, protons exhibit abnormally high conductivity in water. Such superprotonic dynamics was expected in protic ionic conductors as well. However, many years of extensive studies led to the disappointing conclusion that this is not the case and most protic ionic liquids display subionic behavior. Therefore, the relatively low conductivity seems to be the main obstacle for the application of protic ionic liquids in fuel cells. Using dielectric spectroscopy, herein we report the observation of highly decoupled conductivity in a newly synthesized protic ionic conductor. We show that its proton transport is strongly decoupled from the structural relaxation, in terms of both temperature dependence and characteristic rates. This finding offers a fresh look on the charge transport mechanism in PILs and also provides new ideas for design of anhydrous materials with exceptionally high proton conductivity.

  3. Ionic conduction in polymer composite electrolytes

    NASA Astrophysics Data System (ADS)

    Dam, Tapabrata; Tripathy, Satya N.; Paluch, M.; Jena, S.; Pradhan, D. K.

    2016-05-01

    Conductivity and structural relaxation has been explored from modulus and dielectric loss formalisms respectively for a series of polymer composite electrolytes with zirconia as filler. The temperature dependence of conductivity followed Vogel-Tamman-Fulcher (VTF) behavior, which suggested a close correlation between conductivity and the segmental relaxation process in polymer electrolytes. Vogel temperature (T0) plays significant role in ion conduction process in these kind of materials.

  4. Ionic conductivity enhancement of polymer electrolytes with ceramic nanowire fillers.

    PubMed

    Liu, Wei; Liu, Nian; Sun, Jie; Hsu, Po-Chun; Li, Yuzhang; Lee, Hyun-Wook; Cui, Yi

    2015-04-08

    Solid-state electrolytes provide substantial improvements to safety and electrochemical stability in lithium-ion batteries when compared with conventional liquid electrolytes, which makes them a promising alternative technology for next-generation high-energy batteries. Currently, the low mobility of lithium ions in solid electrolytes limits their practical application. The ongoing research over the past few decades on dispersing of ceramic nanoparticles into polymer matrix has been proved effective to enhance ionic conductivity although it is challenging to form the efficiency networks of ionic conduction with nanoparticles. In this work, we first report that ceramic nanowire fillers can facilitate formation of such ionic conduction networks in polymer-based solid electrolyte to enhance its ionic conductivity by three orders of magnitude. Polyacrylonitrile-LiClO4 incorporated with 15 wt % Li0.33La0.557TiO3 nanowire composite electrolyte exhibits an unprecedented ionic conductivity of 2.4 × 10(-4) S cm(-1) at room temperature, which is attributed to the fast ion transport on the surfaces of ceramic nanowires acting as conductive network in the polymer matrix. In addition, the ceramic-nanowire filled composite polymer electrolyte shows an enlarged electrochemical stability window in comparison to the one without fillers. The discovery in the present work paves the way for the design of solid ion electrolytes with superior performance.

  5. Ionic Conductivity and Gas Permeability of Polymerized Ionic Liquid Block Copolymer Membranes

    NASA Astrophysics Data System (ADS)

    Evans, Christopher; Sanoja, Gabriel; Schneider, Yanika; Modestino, Miguel; Segalman, Rachel; Joint CenterArtificial Photosynthesis Team

    2014-03-01

    Polymer membranes for many energy applications, such as solar-to-hydrogen fuel production, require ionic conductivity while acting as gas diffusion barriers. We have synthesized a diblock copolymer consisting of poly(styrene-block-(4-(2-methacrylamidoethyl)-imidazolium trifluoroacetate) by treating poly(styrene-block-histamine methacrylamide) (PS- b-PHMA) with trifluoroacetic acid. The PS block serves as the structural support while the imidazolium derivative is an ion conducting polymerized ionic liquid (PIL). Small angle X-ray scattering and transmission electron microscopy demonstrate that the block copolymer self-assembles into well-ordered nanostructures, with lamellae and hexagonally packed cylindrical morphologies. The ionic conductivities of the PS-b-PHMA materials were as high as 2 x 10-4 S/cm while an order of magnitude increase in conductivity was observed upon conversion to PS-b-PIL. The ionic conductivity of the PS-b-PIL increased by a factor of ~ 4 up to 1.2 x 10-3 S/cm as the PIL domain size increased from 20 to 40 nm. These insights allow for the rational design of high performance ion conducting membranes with even greater conductivities via precise morphological control. Additionally, the role of thermal annealing on the ionic conductivity and gas permeability of copolymer membranes was investigated.

  6. Conductivities of the ionic complexes of two cyclic polyethers

    NASA Technical Reports Server (NTRS)

    Fielder, W. L.; Odonnell, P. M.

    1975-01-01

    The conductivities of the solid potassium thiocyanate complex of both dicyclohexyl-18-crown-6 and dibenzo-18-crown-6 were measured at 300K (27 C). Saturated aqueous potassium thiocyanate and graphite were used as ion-transporting and ion-blocking electrodes, respectively. The ionic conductivity predominated for both samples, but it was many orders of magnitude smaller than the value previously reported. The ionic conductivity of the dicyclohexyl complex (the better conductor) was 0.000003 ohm/cm. Crown complexes, in general, do not appear promising as potassium ion solid electrolytes contrary to claims in the patent literature.

  7. Correlating morphology to dc conductivity in polymerized ionic liquids

    NASA Astrophysics Data System (ADS)

    Iacob, Ciprian; Matusmoto, Atsushi; Inoue, Tadashi; Runt, James

    Polymerized ionic liquids (PILs) combine the attractive mechanical characteristics of polymers and unique physico-chemical properties of low molecular weight ionic liquids in the same material. PILs have shown remarkable advantages when employed in electrochemical devices such as dye-sensitized solar cells and lithium batteries, among others. Understanding their ionic transport mechanism is the key for designing highly conductive PILs. In the current study, the correlation between morphology and charge transport in two homologous series of PILs with systematic variation of the alkyl chain length and anions is investigated using broadband dielectric spectroscopy, rheology, differential scanning calorimetry and X-ray scattering. As the alkyl chain length increases, the backbone-to-backbone separation increases, and dc-conductivity consequently decreases. The cations dominate structural dynamics since they are attached to the polymer chains, while the anions are smaller and more mobile ionic species thereby controlling the ionic conductivity. Further interpretation of decoupling of dc conductivity from the segmental relaxation enabled the correlation between polymer morphology and dc conductivity. Supported by the National Science Foundation, Polymers Program.

  8. Ionic conductivity on a wetting surface.

    PubMed

    Skinner, Brian; Loth, M S; Shklovksii, B I

    2009-10-01

    Recent experiments measuring the electrical conductivity of DNA molecules highlight the need for a theoretical model of ion transport along a charged surface. Here we present a simple theory based on the idea of unbinding of ion pairs. The strong humidity dependence of conductivity is explained by the decrease in the electrostatic self-energy of a separated pair when a layer of water (with high dielectric constant) is adsorbed to the surface. We compare our prediction for conductivity to experiment and discuss the limits of its applicability.

  9. Density, viscosity and electrical conductivity of protic alkanolammonium ionic liquids.

    PubMed

    Pinkert, André; Ang, Keng L; Marsh, Kenneth N; Pang, Shusheng

    2011-03-21

    Ionic liquids are molten salts with melting temperatures below the boiling point of water, and their qualification for applications in potential industrial processes does depend on their fundamental physical properties such as density, viscosity and electrical conductivity. This study aims to investigate the structure-property relationship of 15 ILs that are primarily composed of alkanolammonium cations and organic acid anions. The influence of both the nature and number of alkanol substituents on the cation and the nature of the anion on the densities, viscosities and electrical conductivities at ambient and elevated temperatures are discussed. Walden rule plots are used to estimate the ionic nature of these ionic liquids, and comparison with other studies reveals that most of the investigated ionic liquids show Walden rule values similar to many non-protic ionic liquids containing imidazolium, pyrrolidinium, tetraalkylammonium, or tetraalkylphosphonium cations. Comparison of literature data reveals major disagreements in the reported properties for the investigated ionic liquids. A detailed analysis of the reported experimental procedures suggests that inappropriate drying methods can account for some of the discrepancies. Furthermore, an example for the improved presentation of experimental data in scientific literature is presented.

  10. Tuning the ionic conductivity in protic polymerized ionic liquid homo, random, and block copolymers

    NASA Astrophysics Data System (ADS)

    Evans, Christopher; Segalman, Rachel; UCSB Team

    2015-03-01

    Proton conducting membranes are of interest for a number of energy applications including use in fuel cells and artificial photosynthesis systems. We have synthesized a new class of protic polymerized ionic liquids (PILs) based on imidazolium cations which exhibit high conductivities in the solid state. In contrast to previous imidazolium based PILs, the ionic liquid moiety is attached via a carbon on the imidazole thus leaving the two nitrogens available to act as a proton donor/acceptor. The conductivies of these protic PILs, measured by dielectric spectroscopy, are orders of magnitude higher than the analogous non-protic PILs at a given distance above (Tg). These high conductivities are the result of a strong contribution from proton motion. A series of random and block copolymers containing the polymerized ionic liquid monomer and a non-ionic comonomer were also investigated to determine the role of comonomer on the conductivity of these materials. It was found that methyl acrylate, which has a low glass transition temperature and high dielectric constant, can result in improvements of ionic conductivity. Studies using solid state NMR are underway to understand the role of protons and mobile anions in controlling the overall conductivity of these materials.

  11. Morphology and Ionic Conductivity of Humidity-Responsive Polymerized Ionic Liquid Block Copolymers

    NASA Astrophysics Data System (ADS)

    Sharick, Sharon; Meek, Kelly; Ye, Yuesheng; Elabd, Yossef A.; Winey, Karen I.

    2014-03-01

    We present the ionic conductivity and morphology of humidity-responsive polymerized ionic liquid block copolymers (PIL BCPs), poly(methyl methacrylate- b-1-[2-(methacryloyloxy)ethyl]-3-butylimidazolium-X), where X is a bromide (Br) or hydroxide (OH) anion, as a function of relative humidity (RH), temperature, and PIL composition (ϕPIL) . PIL BCPs were characterized by in situ small-angle X-ray scattering and electrochemical impedance spectroscopy. These PIL BCPs have microphase separated morphologies and long-range order increases as ϕPIL increases. Notably, ionic conductivity increases 3 to 4 orders of magnitude when RH increases from 30 to 90 percent. When ϕPIL is greater than 0.37, BCP ionic conductivity approaches or exceeds that of the homopolymer, suggesting that the dynamics in PIL microdomains mimic the homopolymer and long-range order aids ion transport. Moreover, over 60 percent of the BCP is nonconductive without a penalty in ion transport. When ϕPIL is less than 0.37, BCP conductivity is 1 to 2 orders of magnitude less than the homopolymer and non-conductive PMMA segments dominate ion transport, as expected. Ionic conductivities at 80 °C, 90 percent RH, are 7.6 mS/cm for the Br-containing BCP with ϕPIL = 0.53 and 25.0 mS/cm for the OH-containing BCP with ϕPIL = 0.50.

  12. Variation of ionic conductivity in a plastic-crystalline mixture.

    PubMed

    Reuter, D; Geiß, C; Lunkenheimer, P; Loidl, A

    2017-09-14

    Ionically conducting plastic crystals (PCs) are possible candidates for solid-state electrolytes in energy-storage devices. Interestingly, the admixture of larger molecules to the most prominent molecular PC electrolyte, succinonitrile, was shown to drastically enhance its ionic conductivity. Therefore, binary mixtures seem to be a promising way to tune the conductivity of such solid-state electrolytes. However, to elucidate the general mechanisms of ionic charge transport in plastic crystals and the influence of mixing, a much broader database is needed. In the present work, we investigate mixtures of two well-known plastic-crystalline systems, cyclohexanol and cyclooctanol, to which 1 mol. % of Li ions were added. Applying differential scanning calorimetry and dielectric spectroscopy, we present a thorough investigation of the phase behavior and the ionic and dipolar dynamics of this system. All mixtures reveal plastic-crystalline phases with corresponding orientational glass-transitions. Moreover, their conductivity seems to be dominated by the "revolving-door" mechanism, implying a close coupling between the ionic translational and the molecular reorientational dynamics of the surrounding plastic-crystalline matrix. In contrast to succinonitrile-based mixtures, there is no strong variation of this coupling with the mixing ratio.

  13. Variation of ionic conductivity in a plastic-crystalline mixture

    NASA Astrophysics Data System (ADS)

    Reuter, D.; Geiß, C.; Lunkenheimer, P.; Loidl, A.

    2017-09-01

    Ionically conducting plastic crystals (PCs) are possible candidates for solid-state electrolytes in energy-storage devices. Interestingly, the admixture of larger molecules to the most prominent molecular PC electrolyte, succinonitrile, was shown to drastically enhance its ionic conductivity. Therefore, binary mixtures seem to be a promising way to tune the conductivity of such solid-state electrolytes. However, to elucidate the general mechanisms of ionic charge transport in plastic crystals and the influence of mixing, a much broader database is needed. In the present work, we investigate mixtures of two well-known plastic-crystalline systems, cyclohexanol and cyclooctanol, to which 1 mol. % of Li ions were added. Applying differential scanning calorimetry and dielectric spectroscopy, we present a thorough investigation of the phase behavior and the ionic and dipolar dynamics of this system. All mixtures reveal plastic-crystalline phases with corresponding orientational glass-transitions. Moreover, their conductivity seems to be dominated by the "revolving-door" mechanism, implying a close coupling between the ionic translational and the molecular reorientational dynamics of the surrounding plastic-crystalline matrix. In contrast to succinonitrile-based mixtures, there is no strong variation of this coupling with the mixing ratio.

  14. Ion Conduction in Polymerized Ionic Liquids with Different Pendant Groups

    SciTech Connect

    Fan, Fei; Wang, Yangyang; Hong, Tao; Heres, Maximilian F.; Saito, Tomonori; Sokolov, Alexei P.

    2015-07-17

    Polymerized ionic liquids (PolyILs) are promising candidates for energy storage and electrochemical devices applications. Understanding their ionic transport mechanism is the key for designing highly conductive PolyILs. By using broadband dielectric spectroscopy (BDS), rheology, and differential scanning calorimetry (DSC), a systematic study has been carried out to provide a better understanding of the ionic transport mechanism in PolyILs with different pendant groups. The variation of pendant groups results in different dielectric, mechanical, and thermal properties of these PolyILs. The Walden plot analysis shows that the data points for all these PolyILs fall above the ideal Walden line, and the deviation from the ideal line increases upon approaching the glass transition temperature (Tg). Moreover, the conductivity for these PolyILs at their Tgs are much higher than the usually reported value 10 15 S/cm for polymer electrolytes, in which the ionic transport is closely coupled to the segmental dynamics. These results indicate a decoupling of ionic conductivity from the segmental relaxation in these materials. The degree of decoupling increases with the increase of the fragility of polymer segmental relaxation. Finally, we relate this observation to a decrease in polymer packing efficiency with an increase in fragility.

  15. Thermal boundary conductance of hydrophilic and hydrophobic ionic liquids

    NASA Astrophysics Data System (ADS)

    Oyake, Takafumi; Sakata, Masanori; Yada, Susumu; Shiomi, Junichiro

    2015-03-01

    A solid/liquid interface plays a critical role for understanding mechanisms of biological and physical science. Moreover, carrier density of the surface is dramatically enhanced by electric double layer with ionic liquid, salt in the liquid state. Here, we have measured the thermal boundary conductance (TBC) across an interface of gold thin film and ionic liquid by using time-domain thermoreflectance technique. Following the prior researches, we have identified the TBC of two interfaces. One is gold and hydrophilic ionic liquid, N,N-Diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate (DEME-BF4), which is a hydrophilic ionic liquid, and the other is N,N-Diethyl-N-methyl-N-(2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) imide (DEME-TFSI), which is a hydrophobic ionic liquid. We found that the TBC between gold and DEME-TFIS (19 MWm-2K-1) is surprisingly lower than the interface between gold and DEME-BF4 (45 MWm-2K-1). With these data, the importance of the wetting angle and ion concentration for the thermal transport at the solid/ionic liquid interface is discussed. Part of this work is financially supported by Japan Society for the Promotion of Science (JSPS) and Japan Science and Technology Agency. The author is financially supported by JSPS Fellowship.

  16. Defect association mediated ionic conductivity of rare earth doped nanoceria: Dependency on ionic radius

    NASA Astrophysics Data System (ADS)

    Anirban, Sk.; Sinha, A.; Bandyopadhyay, S.; Dutta, A.

    2016-05-01

    Rare earth doped nanoceria Ce0.9RE0.1O1.95 (RE = Pr, Nd, Eu and Gd) were prepared through citrate auto-ignition method. The single phase cubic fluorite structure with space group Fm3 ¯m of the compositions were confirmed from Rietveld analysis of XRD data. The particle size of the compositions were in the range 49.77 nm to 66.20 nm. An ionic radius dependent lattice parameter variation was found. The DC conductivity of each composition was evaluated using Random Barrier Model. The conductivity decreased and activation energy increased with increasing ionic radius from Gd to Pr doping due to the size mismatch with host ions and formation of stable defect associate. The formation of different defect associates and their correlation with ionic conductivity has been discussed.

  17. Intercalation of ionically conductive polymers into Lithium Hectorite

    NASA Astrophysics Data System (ADS)

    Saada, Iskandar

    Renewable energy sources such as wind and solar have become appealing sources of energy with low environmental impact. However, the challenge with using these energy sources is their intermittent and unpredictable power generation. In order to overcome this challenge, energy storage mechanisms such as lithium-ion batteries are dependable systems for such applications. The purpose of this project is intended to synthesize environmentally benign and safe materials which can be used as electrolytes in lithium-ion batteries. The ionically conductive polymers POEGO, POMOE, and MEEP were successfully intercalated into the two-dimensional layered structure Lithium Hectorite. The goal of the project was to synthesize a series of nanocomposites with increasing polymer molar ratios to Lithium Hectorite, and investigate the thermal and ionic conductivity properties of the synthesized nanocomposites. A second series of nanocomposites using the same polymer molar ratio to Lithium Hectorite were synthesized after the polymers were complexed with lithium triflate. The salt-complexed nanocomposites were compared to the pristine nanocomposites based on thermal stability, polymer flexibility, as well as their ionic conductivity. The synthesized polymers, nanocomposites, and salt-complexed materials were characterized using powder X-ray diffraction, attenuated total reflectance spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. Ionic conductivity data was investigated using AC impedance spectroscopy.

  18. Electrolytic Conductivity of Four Imidazolium-Based Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Calado, Marta S.; Diogo, João C. F.; Correia da Mata, José L.; Caetano, Fernando J. P.; Visak, Zoran P.; Fareleira, João M. N. A.

    2013-07-01

    In this article, electrolytic (ionic) conductivity measurements of four ionic liquids (ILs), namely, 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide ([Cmim][NTf]), 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([Cmim][OTf]), 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([Cmim][NTf]), and 1-ethyl-3-methylimidazolium ethyl sulfate ([Cmim][EtSO]) (ECOENG212), were performed in a temperature range of (288.15 to 333.15) K. [Cmim][NTf] was chosen to be a reference ionic liquid for several properties, including the electrolytic conductivity by the IUPAC Project 2002-005-1-100. For that reason, the measurements performed with that ionic liquid primarily serve the purpose to validate the instrumentation and the experimental procedure used in this work. The measurements were carried out using a complex impedance method, applying a novel electronic device designed and constructed for this purpose. The complete setup includes a Schott Instruments LF 913 T, used as a four-electrode conductivity cell, and a lock-in amplifier. The cell was calibrated using standard reference KCl aqueous solutions. The measurements of the impedance of the conductivity cell were carried out along a range of frequencies from (0.2 to 30) kHz, and the results were extrapolated to infinite frequency, in order to determine the electrolytic conductivity of the liquid samples. The results obtained for the ionic liquid [Cmim][NTf] were compared to reference data, and it was estimated that the overall uncertainty of the present results is better than 2 %. All the data obtained were compared with available literature data, and were analyzed and discussed in respect to the effect of temperature, cation alkyl chain length, and anion.

  19. Pink noise of ionic conductance through single artificial nanopores revisited.

    PubMed

    Tasserit, C; Koutsioubas, A; Lairez, D; Zalczer, G; Clochard, M-C

    2010-12-31

    We report voltage-clamp measurements through single conical nanopore obtained by chemical etching of a single ion track in polyimide film. Special attention is paid to the pink noise of the ionic current (i.e., 1/f noise) measured with different filling liquids. The relative pink-noise amplitude is almost independent of concentration and pH for KCl solutions, but varies strongly using ionic liquids. In particular, we show that depending on the ionic liquid, the transport of charge carriers is strongly facilitated (low noise and higher conductivity than in the bulk) or jammed. These results show that the origin of the pink noise can be ascribed neither to fluctuations of the pore geometry nor to the pore wall charges, but rather to a cooperative effect on ions motion in confined geometry.

  20. Pink Noise of Ionic Conductance through Single Artificial Nanopores Revisited

    NASA Astrophysics Data System (ADS)

    Tasserit, C.; Koutsioubas, A.; Lairez, D.; Zalczer, G.; Clochard, M.-C.

    2010-12-01

    We report voltage-clamp measurements through single conical nanopore obtained by chemical etching of a single ion track in polyimide film. Special attention is paid to the pink noise of the ionic current (i.e., 1/f noise) measured with different filling liquids. The relative pink-noise amplitude is almost independent of concentration and pH for KCl solutions, but varies strongly using ionic liquids. In particular, we show that depending on the ionic liquid, the transport of charge carriers is strongly facilitated (low noise and higher conductivity than in the bulk) or jammed. These results show that the origin of the pink noise can be ascribed neither to fluctuations of the pore geometry nor to the pore wall charges, but rather to a cooperative effect on ions motion in confined geometry.

  1. Thermal properties and ionic conductivity of imidazolium bis(trifluoromethanesulfonyl)imide dicationic ionic liquids.

    PubMed

    Pitawala, Jagath; Matic, Aleksandar; Martinelli, Anna; Jacobsson, Per; Koch, Victor; Croce, Fausto

    2009-08-06

    We report on the thermal and transport properties of new dicationic ionic liquids. The new ionic liquids are based on the bis(trifluoromethanesulfonyl)imide [NTf(2)](-) anion and a cation that contains two imidazolium rings, connected by either a pentane or a decane hydrocarbon chain and different side groups. We have investigated the conductivity and the thermal properties by dielectric spectroscopy and differential scanning calorimetry, respectively. Our results show that the length of the alkyl chain on the cation has no, or weak, influence on the glass transition temperature, T(g), whereas the presence of rigid aromatic side groups has a strong influence increase T(g). The highest ionic conductivity is 5.9 x 10(-4) S cm(-1) at 298 K for an ionic liquid with a decane chain and one methyl group on each imidazolium ring. The conductivity results correlate well with the glass transition temperatures. This shows that the flexibility of the geminal cations is very important for the conductivity. However, the presence of nonflexible aromatic side groups on the imidazolium ring decreases the flexibility and hence the mobility.

  2. Ordered and Disordered Polymerized Ionic Liquid Block Copolymers: Morphology and Ionic Conductivity

    NASA Astrophysics Data System (ADS)

    Wang, Sharon; Ye, Yuesheng; Elabd, Yossef; Winey, Karen

    2013-03-01

    We systematically studied the influence of temperature and relative humidity on morphology and ionic conductivity in polymerized ionic liquid block copolymers (PIL BCP). Poly(methyl methacrylate- b-1-[2-(methacryloyloxy)ethyl]-3-butylimidazolium-X-) block copolymers (X- = OH-, Br-) were characterized by SAXS, dynamical mechanical analysis, and electrochemical impedance spectroscopy. At 25 °C, weak microphase separation was observed for the PIL BCP with ϕPIL = 0.38 and X- = OH-. Upon increasing the relative humidity to 90%, this polymer exhibited an order-disorder transition (ODT). The ODT was further studied in the PIL BCPs with X- = OH- and 0.11 <ϕPIL <0.38 over a range of temperatures and %RH. In contrast, the PIL BCP with ϕPIL = 0.38 and X- = Br- formed strongly microphase separated lamellae at all investigated T and %RH. At elevated temperature and 90 %RH, ionic conductivities of 30 and 6 mS/cm were observed for ϕPIL = 0.38 and X- = OH- and Br-, respectively, surpassing the conductivities of the corresponding PIL homopolymer. By selecting the counterion and relative humidity, we significantly impact the morphology and ionic conductivity of these PIL block copolymers.

  3. High ionic conductivity in confined bismuth oxide-based heterostructures

    NASA Astrophysics Data System (ADS)

    Sanna, Simone; Esposito, Vincenzo; Christensen, Mogens; Pryds, Nini

    2016-12-01

    Bismuth trioxide in the cubic fluorite phase ( δ - Bi 2 O 3 ) exhibits the highest oxygen ionic conductivity. In this study, we were able to stabilize the pure δ - Bi 2 O 3 at low temperature with no addition of stabilizer but only by engineering the interface, using highly coherent heterostructures made of alternative layers of δ - Bi 2 O 3 and Yttria Stabilized Zirconia (YSZ), deposited by pulsed laser deposition. The resulting [ δ - Bi 2 O 3 / YSZ ] heterostructures are found to be stable over a wide temperature range (500-750 °C) and exhibits stable high ionic conductivity over a long time comparable to the value of the pure δ - Bi 2 O 3 , which is approximately two orders of magnitude higher than the conductivity of YSZ bulk.

  4. Electronic and ionic conductivities in superionic Li4C60

    NASA Astrophysics Data System (ADS)

    Quintavalle, D.; Márkus, B. G.; Jánossy, A.; Simon, F.; Klupp, G.; Győri, M. A.; Kamarás, K.; Magnani, G.; Pontiroli, D.; Riccò, M.

    2016-05-01

    The 10 GHz microwave conductivity, σ (T ) and high field, 222 GHz electron spin resonance (HF-ESR) of Li4C60 fulleride is measured in a wide temperature range. We suggest that the majority of ESR active sites and at least some of the charge carriers for σ (T ) are electrons bound to a small concentration of surplus or vacancy ions in the polymer phase. Both σ (T ) and the ESR line shape depend on ionic motion. A change of the activation energy of σ (T ) at 125 K coincides with the onset of the ionic DC conductivity. The ESR line shape is determined mainly by Li ionic motion within octahedral voids below 150 K. At higher temperatures, fluctuations due to ionic diffusion change the environment of defects from axial to effectively isotropic on the ESR time scale. σ (T ) data up to 700 K through the depolymerization transition confirm that the monomeric phase of Li4C60 is a metal.

  5. Intrinsic low thermal conductivity in weakly ionic rocksalt structures

    DOE PAGES

    Zhang, Yi; Dong, Jianjun; Kent, Paul R. C.; ...

    2015-07-06

    A fundamental challenge in thermoelectric (TE) material research is meeting the simultaneous requirements of high carrier mobility and low thermal conductivity. Simple crystal structures are ideal for maintaining high carrier mobility, but they usually have high thermal conductivity. In this paper, we show by first-principles lattice dynamics and Boltzmann transport calculations that weakly ionic rocksalt structures exhibit strong lattice anharmonicity and low acoustic-phonon group velocity, which combine to produce intrinsic low thermal conductivity. Finally, we unveil microscopic mechanisms that explain experimental observations and provide insights for TE material design and discovery.

  6. Mixed ionic and electronic conducting ceramic membranes for hydrocarbon processing

    DOEpatents

    Van Calcar, Pamela; Mackay, Richard; Sammells, Anthony F.

    2002-01-01

    The invention relates to mixed phase materials for the preparation of catalytic membranes which exhibit ionic and electronic conduction and which exhibit improved mechanical strength compared to single phase ionic and electronic conducting materials. The mixed phase materials are useful for forming gas impermeable membranes either as dense ceramic membranes or as dense thin films coated onto porous substrates. The membranes and materials of this invention are useful in catalytic membrane reactors in a variety of applications including synthesis gas production. One or more crystalline second phases are present in the mixed phase material at a level sufficient to enhance the mechanical strength of the mixture to provide membranes for practical application in CMRs.

  7. Enhancement in ionic conductivity on solid polymer electrolytes containing large conducting species

    SciTech Connect

    Praveen, D.; Damle, Ramakrishna

    2016-05-23

    Solid Polymer Electrolytes (SPEs) lack better conducting properties at ambient temperatures. Various methods to enhance their ionic conductivity like irradiation with swift heavy ions, γ-rays, swift electrons and quenching at low temperature etc., have been explored in the literature. Among these, one of the oldest methods is incorporation of different conducting species into the polymer matrix and/or addition of nano-sized inert particles into SPEs. Various new salts like LiBr, Mg(ClO{sub 4}){sub 2}, NH{sub 4}I etc., have already been tried in the past with some success. Also various nanoparticles like Al{sub 2}O{sub 3}, TiO{sub 2} etc., have been tried in the past. In this article, we have investigated an SPE containing Rubidium as a conducting species. Rubidium has a larger ionic size compared to lithium and sodium ions which have been investigated in the recent past. In the present article, we have investigated the conductivity of large sized conducting species and shown the enhancement in the ionic conductivity by addition of nano-sized inert particles.

  8. Morphology and Ionic Conductivity of Oriented Block Copolymer/Ionic Liquid Mixtures

    NASA Astrophysics Data System (ADS)

    Sharick, Sharon; Winey, Karen I.

    2015-03-01

    Ion-containing block copolymers with increased continuity and long-range order of ion-containing microdomains were prepared to probe the impact of grain boundaries and microdomain orientation on ion transport. We studied poly(styrene- b-methyl methacrylate) diblock copolymers swollen with 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonylimide) (SbMMA/IL), and characterized the thermal transitions, morphologies, and ionic conductivities by differential scanning calorimetry, small-angle X-ray scattering, and electrochemical impedance spectroscopy over a range of compositions. Two glass transition temperatures (Tgs) are observed, corresponding to PS and PMMA/IL microdomains, and Tg,PMMA/IL is modeled well by the Gordon-Taylor expression. SbMMA/IL films prepared by solvent evaporation exhibit strongly microphase-separated lamellar morphology with long-range order. Slower rates of solvent evaporation produce films with lamellae preferentially oriented to be in the plane. In-plane conductivities increase with both increasing ionic liquid content and with better parallel alignment of lamellae. The Sax and Ottino model will be used to compare the conductivity of SbMMA/IL with the homopolymer/IL mixture, PMMA/IL, and to discuss the ion transport mechanism.

  9. Imidazolium-Based Poly(ionic liquid)/Ionic Liquid Ion-Gels with High Ionic Conductivity Prepared from a Curable Poly(ionic liquid).

    PubMed

    Cowan, Matthew G; Lopez, Alexander M; Masuda, Miyuki; Kohno, Yuki; McDanel, William M; Noble, Richard D; Gin, Douglas L

    2016-07-01

    Ionic liquid (IL)-based ion-gel membranes were prepared from a curable poly(IL)-based materials platform with the free ILs 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]), bis(fluorosulfonyl)imide ([EMIM][FSI]), 1-butylimidazolium bis(trifluoromethylsulfonyl)imide ([C4 IMH][TFSI]), and ethylmethylammonium nitrate [EAN][NO3 ] and evaluated for their ionic conductivity performance at ambient and elevated temperatures. The resulting cross-linked, free-standing ion-gel membranes were found to have less than 1 wt% water (with the exception of [EAN][NO3 ] which contained ≈20 wt% water). Increasing free IL content from 50 to 80 wt% produces materials with ionic conductivity values ≥10(-2) S cm(-1) at 25 °C and ≈10(-1) S cm(-1) at 110 °C. Additionally, ion-gels containing 70 wt% of the protic ILs [C4 IMH][TFSI] and [EMIM][FSI] display ionic conductivity values of ≈10(-3) to 10(-2) S cm(-1) over the temperature range of 25-110 °C.

  10. On the dielectric conductivity of molecular ionic liquids.

    PubMed

    Schröder, Christian; Steinhauser, Othmar

    2009-09-21

    The contribution of the conductivity to the spectrum of the generalized dielectric constant or susceptibility of molecular ionic liquids is analyzed, both in theoretical terms and computationally by means of molecular dynamics simulation of the concrete system 1-ethyl-3-methyl-imidazolium dicyanoamide at 300 K. As a central quantity the simulated current autocorrelation function is modeled by a carefully designed fit function. This not only gives a satisfactory numerical representation but yields the correct conductivity upon integration. In addition the fit function can be Fourier-Laplace transformed analytically. Both, the real and imaginary parts of the transform show expected behavior, in particular, the right limits for zero frequency. This altogether demonstrates that the components of the fit function are of physical relevance.

  11. Improved Lithium Ionic Conductivity in Composite Polymer Electrolytes with Oxide-Ion Conducting Nanowires.

    PubMed

    Liu, Wei; Lin, Dingchang; Sun, Jie; Zhou, Guangmin; Cui, Yi

    2016-12-27

    Solid Li-ion electrolytes used in all-solid-state lithium-ion batteries (LIBs) are being considered to replace conventional liquid electrolytes that have leakage, flammability, and poor chemical stability issues, which represents one major challenge and opportunity for next-generation high-energy-density batteries. However, the low mobility of lithium ions in solid electrolytes limits their practical applications. Here, we report a solid composite polymer electrolyte with Y2O3-doped ZrO2 (YSZ) nanowires that are enriched with positive-charged oxygen vacancies. The morphologies and ionic conductivities have been studied systemically according to concentration of Y2O3 dopant in the nanowires. In comparison to the conventional filler-free electrolyte with a conductivity of 3.62 × 10(-7) S cm(-1), the composite polymer electrolytes with the YSZ nanowires show much higher ionic conductivity. It indicates that incorporation of 7 mol % of Y2O3-doped ZrO2 nanowires results in the highest ionic conductivity of 1.07 × 10(-5) S cm(-1) at 30 °C. This conductivity enhancement originates from the positive-charged oxygen vacancies on the surfaces of the nanowires that could associate with anions and then release more Li ions. Our work demonstrates a composite polymer electrolyte with oxygen-ion conductive nanowires that could address the challenges of all-solid-state LIBs.

  12. Nanostructure-thermal conductivity relationships in protic ionic liquids.

    PubMed

    Murphy, Thomas; Varela, Luis M; Webber, Grant B; Warr, Gregory G; Atkin, Rob

    2014-10-16

    The thermal conductivities of nine protic ionic liquids (ILs) have been investigated between 293 and 340 K. Within this range, the thermal conductivities are between 0.18 and 0.30 W · m(-1) · K(-1). These values are higher than those typically associated with oils and aprotic ILs, but lower than those of strongly hydrogen bonding solvents like water. Weak linear decreases in thermal conductivity with temperature are noted, with the exception of ethanolammonium nitrate (EtAN) where the thermal conductivity increases with temperature. The dependence of thermal conductivity on IL type is analyzed with use of the Bahe-Varela pseudolattice theory. This theory treats the bulk IL as an array of ordered domains with intervening domains of uncorrelated structure which enable and provide barriers to heat propagation (respectively) via allowed vibrational modes. For the protic ILs investigated, thermal conductivity depends strongly on the IL cation alkyl chain length. This is because the cation alkyl chain controls the dimensions of the IL bulk nanostructure, which consists of charged (ordered domains) and uncharged regions (disordered domains). As the cation alkyl chain controls the dimensions of the disordered domains, it thus limits the thermal conductivity. To test the generality of this interpretation, the thermal conductivities of propylammonium nitrate (PAN) and PAN-octanol mixtures were examined; water selectively swells the PAN charged domain, while octanol swells the uncharged regions. Up to a certain concentration, adding water increases thermal conduction and octanol decreases it, as expected. However, at high solute concentrations the IL nanostructure is broken. When additional solvent is added above this concentration the rate of change in thermal conductivity is greatly reduced. This is because, in the absence of nanostructure, the added solvent only serves to dilute the salt solution.

  13. Anisotropic Ionic Conductivity of Lithium-Doped Sulfonated PBI.

    NASA Astrophysics Data System (ADS)

    Spry, R. J.; Arnold, F. E.; Dean, D. R.; Alexander, M. D., Jr.; Bai, S. J.; Dang, T. D.; Price, G. E.; Solomon, J. S.

    1997-03-01

    We report the conductivity study results of lithium-doped sulfonated PBI, a conjugated rigid rod polymer, poly[(1,7-dihydrobenzo[1,2-d:4,5-d']dimidazole-2,6-diyl)-2-(2-sulfo)-p- phenylene], derivatized with pendants of propane sulfonate Li^+ ionomer. The DC four-probe conductivity parallel to the surface of cast films was as large as 8.3× 10-3 S/cm. Similar measurements in an eight-probe configuration showed no difference between bulk and surface conductivity. The ionic nature of the conductivity was indicated by constant voltage depletion experiments and by secondary ion mass spectroscopy measurements of the residues near the electrodes. Both the AC and DC two-probe conductivities measured transverse to the sample surface were ~ 10-8 S/cm. Electron microscopy indicated that the films has a layered structure parallel to the surfaces. This structural anisotropy was confirmed by refractive index values obtained from wave-guide experiments. The polymer morphology was also investigated by X-ray scattering.

  14. Anion and Cation Ionic Conductivity of Dragon Fruit

    NASA Astrophysics Data System (ADS)

    Hajar, Nadya; Asiah, M. N.; Abdullah, S.; Rusop, M.

    2010-07-01

    The separation of all ions in a synthetic solution was achieved with an anion eluent containing 0.3392 g Na2CO3 and 0.084 g NaHCO2 and the run around 20 min. Cation eluent containing 0.60 g Tartaric acid and 0.125 g Dipicolinic acid and the run around 16 min. This method was applied to dragon fruit juice with success and has shown sensitivity. Moreover, sample preparation was a simple 1:1, 1:10, 1:100 and 1:1000 ppm with 0.20 mm filtration and direct injection without prior sample clean-up. Due to the use of eluent generator, very low conductance background conductivity can be obtained and sensitivity of dragon fruit has been greatly improved. Under the experimental condition, several inorganic anions, such as F-, NO3-, NO2-, Br- and PO43- obtained from dragon fruit. For cation, inorganic ions that occurred during the experiment were NH3+, Ca+, and Mg+. Conductivity for anion of F-, NO3-, NO2-, Br- and PO43- were approximately 20, 17, 16, 16 and 20 μS/cm, respectively. Concentration for F- is 1.57 mg/l, NO3- is 1.92 mg/l, NO2- is 0.30 mg/l, Br- is 0.45 mg/l and PO43- is 4.45 mg/l. Conductivity for cation of NH3+, Ca+, and Mg+ were approximately 537, 538 and 531 μS/cm, respectively. Concentration for cation of NH3+ is 0.93 mg/l, Ca+ is 1.15 mg/l, and Mg+ 7.285 is mg/l. The method has successfully applied to the determination of inorganic ions in dragon fruit. An ion chromatography method is described for the simultaneous determination of ionic conductivity for dragon fruit juice using a selected anion and cation eluent. The detection of ionic conductivity in dragon fruit juice has been studied.

  15. Ionic Conductivity and its Role in Oxidation Reactions

    NASA Astrophysics Data System (ADS)

    Tamimi, Mazin Abdulla

    In the field of solid oxide fuel cells (SOFCs), a substantial portion of research is focused on the ability of some oxide materials to conduct oxygen anions through their structure. For electrolytes, the benefits of improving bulk transport of ions are obvious: decrease the resistive losses of the electrolyte, and device efficiency goes up and higher power densities are possible. Even for cathode materials, better bulk ion transport leads to an increase in the oxygen exchange rate at the cathode surface, and the oxygen reduction reaction at the cathode surface is the rate limiting step for SOFC operation at intermediate temperatures (500-700ºC). As operation in this regime is a key step towards lowering the manufacturing cost and increasing the lifetime of devices, much effort is spent searching for new, more conductive materials, and analyzing existing materials to discover the structure-activity relationships that influence ionic conductivity. In the first part of this work, an overview is given of the neutron powder diffraction (NPD) techniques that are used to probe the structure of the materials in later parts. In the second part, NPD was used to analyze the structures of perovskite-type cathode materials, and show that increases in bulk conductivity led to increases in the surface oxygen exchange rate of these materials. In the final part, the methods used for SOFC cathode design were applied towards the design of oxide catalysts used for certain hydrocarbon partial oxidation reactions. The reactions studied follow the Mars van Krevelen mechanism, where oxygen atoms in the catalyst are consumed as part of the reaction and are subsequently replenished by oxygen in the gas phase. Similar to SOFC cathode operation, these processes include an oxygen reduction step, so it was hypothesized that increasing the ionic conductivity of the catalysts would improve their performance, just as it does for SOFC cathode materials. While the results are preliminary, the

  16. Thermal Conductivity of Ionic Liquids: Measurement and Prediction

    NASA Astrophysics Data System (ADS)

    Fröba, A. P.; Rausch, M. H.; Krzeminski, K.; Assenbaum, D.; Wasserscheid, P.; Leipertz, A.

    2010-12-01

    This study reports thermal-conductivity data for a series of [EMIM] (1-ethyl-3-methylimidazolium)-based ionic liquids (ILs) having the anions [NTf2] (bis(trifluoromethylsulfonyl)imide), [OAc] (acetate), [N(CN)2] (dicyanimide), [C(CN)3] (tricyanomethide), [MeOHPO2] (methylphosphonate), [EtSO4] (ethylsulfate), or [OcSO4] (octylsulfate), and in addition for ILs with the [NTf2]-anion having the cations [HMIM] (1-hexyl-3-methylimidazolium), [OMA] (methyltrioctylammonium), or [BBIM] (1,3-dibutylimidazolium). Measurements were performed in the temperature range between (273.15 and 333.15) K by a stationary guarded parallel-plate instrument with a total measurement uncertainty of 3 % ( k = 2). For all ILs, the temperature dependence of the thermal conductivity can well be represented by a linear equation. While for the [NTf2]-based ILs, a slight increase of the thermal conductivity with increasing molar mass of the cation is found at a given temperature, the [EMIM]-based ILs show a pronounced, approximately linear decrease with increasing molar mass of the different probed anions. Based on the experimental data obtained in this study, a simple relationship between the thermal conductivity, molar mass, and density is proposed for the prediction of the thermal-conductivity data of ILs. For this, also densities were measured for [EMIM][OAc], [EMIM][C(CN)3], and [HMIM][NTf2]. The mean absolute percentage deviation of all thermal-conductivity data for ILs found in the literature from the proposed prediction is about 7 %. This result represents a convenient simplification in the acquisition of thermal conductivity information for the enormous amount of structurally different IL cation/anion combinations available.

  17. Frequency dependence of ionic conductivity of electrolyte solutions

    NASA Astrophysics Data System (ADS)

    Chandra, Amalendu; Bagchi, Biman

    2000-01-01

    A theory for the frequency dependence of ionic conductivity of an electrolyte solution is presented. In this theory contributions to the conductivity from both the ion atmosphere relaxation and the electrophoretic effects are included in a self-consistent fashion. Mode coupling theory, combined with time-dependent density functional theory of ion atmosphere fluctuations, leads to expressions for these two contributions at finite frequencies. These expressions need to be solved self-consistently for the frequency dependence of the electrolyte friction and the ion conductivity at varying ion concentrations. In the limit of low concentration, the present theory reduces exactly to the well-known Debye-Falkenhagen (DF) expression of the frequency-dependent electrolyte friction when the non-Markovian effects in the ion atmosphere relaxation are ignored and in addition the ions are considered to be pointlike. The present theory also reproduces the expressions of the frequency-dependent conductivity derived by Chandra, Wei, and Patey when appropriate limiting situations are considered. We have carried out detailed numerical solutions of the self-consistent equations for concentrated solutions of a 1:1 electrolyte by using the expressions of pair correlation functions given by Attard. Numerical results reveal that the frequency dependence of the electrolyte friction at finite concentration can be quite different from that given by the DF expression. With the increase of ion concentration, the dispersion of the friction is found to occur at a higher frequency because of faster relaxation of the ion atmosphere. At low frequency, the real part of the conductivity shows a small increase with frequency which can be attributed to the well-known Debye-Falkenhagen effect. At high frequency, the conductivity decreases as expected. The extensions of the present theory to treat frequency-dependent diffusivities of charged colloid suspensions and conductivity of a dilute

  18. Ionic conductances of membranes in ciliated and deciliated Paramecium.

    PubMed Central

    Machemer, H; Ogura, A

    1979-01-01

    1. Paramecium caudatum was deciliated with ethanol. The ionic conductance of the membrane was investigated with constant current, voltage clamp and mechanical stimuli. 2. The resting potential was not modified by the removal of the cilia. The dependence of the resting potential on the extracellular concentrations of Ca and K was the same in deciliated and control cells. 3. The input resistance in deciliated and ciliated cells increased after the ethanol treatment. 4. The membrane capacitance decreased to 48% after deciliation, suggesting that the ciliary surface area is equal to the somatic surface area. 5. Deciliation completely removed the regenerative response (graded action potential) elicited by depolarizing current pulses or mechanical stimuli. 6. Deciliated cells retained the depolarizing and hyperpolarizing mechanoreceptor responses. 7. Voltage-clamp experiments demonstrated the loss of the early inward current in deciliated cells; it was restored during ciliary regeneration. Steady-state current-voltage relationships were unchanged by deciliation. 8. The time courses of the recovery of the membrane capacitance and of the early inward current were similar, suggesting that the number of voltage-sensitive Ca channels is proportional to the ciliary membrane area. 9. We conclude that the voltage-sensitive Ca channels reside in the ciliary membrane (in confirmation of Dunlap, 1976; Ogura & Takahashi, 1976), while mechanoreceptor channels, rectifier channels and resting conductances are localized in the somatic membrane. PMID:529122

  19. Interconnected ionic domains enhance conductivity in microphase separated block copolymer electrolytes

    SciTech Connect

    Arges, Christopher G.; Kambe, Yu; Dolejsi, Moshe; Wu, Guang-Peng; Segal-Pertz, Tamar; Ren, Jiaxing; Cao, Chi; Craig, Gordon S. W.; Nealey, Paul F.

    2017-01-01

    Block copolymer electrolytes (BCEs) represent an attractive choice as solid-state ionic conductors for electrochemical technologies used in energy storage and conversion, water treatment, sensors, and data storage and processing. Unlocking the maximum ionic conductivity of BCEs requires an intimate understanding as to how the microphase separated structure influences transport properties. However, elucidating such knowledge remains elusive due to the challenging task of precisely engineering BCEs with a defined structure in bulk materials. In this work, we examined BCEs in a thin film format because it was amenable to attaining BCEs with a desired nanostructure. Specifically, we systematically investigated anion-conducting BCEs with different degrees of connectivity of the ionic domains. For the first time, we demonstrate that increasing terminal defects in the ionic domain from 1 terminal defect per mu m(2) to 20 terminal defects per mu m(2) ( a relatively small amount of defects) decreased ionic conductivity by 67% compared to the maximum value attained. Conversely, maximizing ionic domain connectivity increased the ionic conductivity by two-fold over a non-ordered BCE film. These experiments highlight that microphase separation alone was insufficient for ameliorating ionic conductivity in BCEs. Rather, microphase separation coupled with complete ionic domain connectivity realized BCEs with significantly enhanced ionic conductivity.

  20. Phase Behavior and Ionic Conductivity of Concentrated Solutions of Polystyrene-Poly(ethylene oxide) Diblock Copolymers in an Ionic Liquid

    SciTech Connect

    Simone, Peter M.; Lodge, Timothy P.

    2010-03-16

    Concentrated solutions of poly(styrene-b-ethylene oxide) (PS-PEO) diblock copolymers were prepared using the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [EMI][TFSI] as the solvent. The self-assembled microstructures adopted by the copolymer solutions have been characterized using small-angle X-ray scattering. Lyotropic mesophase transitions were observed, with a progression from hexagonally packed cylinders of PEO, to lamellae, to hexagonally packed cylinders of PS upon increasing [EMI][TFSI] content. The change in lamellar domain spacing with ionic liquid concentration was found to be comparable to that reported for other block copolymers in strongly selective solvents. The ionic conductivity of the concentrated PS-PEO/[EMI][TFSI] solutions was measured via impedance spectroscopy, and ranged from 1 x 10{sup -7} to 1 x 10{sup -3} S/cm at temperatures from 25-100 C. Additionally, the ionic conductivity of the solutions was found to increase with both ionic liquid concentration and molecular weight of the PEO blocks. The ionic conductivity of PEO homopolymer/[EMI][TFSI] solutions was also measured in order to compare the conductivity of the PS-PEO solutions to the expected limit for a lamellar sample with randomly oriented microstructure grains.

  1. Ionic conductances regulating the excitability of colonic smooth muscles.

    PubMed

    Koh, Sang Don; Ward, S M; Sanders, K M

    2012-08-01

    The tunica muscularis of the gastrointestinal (GI) tract contains two layers of smooth muscle cells (SMC) oriented perpendicular to each other. SMC express a variety of voltage-dependent and voltage-independent ionic conductance(s) that develop membrane potential and control excitability. Resting membrane potentials (RMP) vary through the GI tract but generally are within the range of -80 to -40 mV. RMP sets the 'gain' of smooth muscle and regulates openings of voltage-dependent Ca(2+) channels. A variety of K(+) channels contribute to setting RMP of SMC. In most regions, RMP is considerably less negative than the K(+) equilibrium potential, due to a finely tuned balance between background K(+) channels and non-selective cation channels (NSCC). Variations in expression patterns and openings of K(+) channels and NSCC account for differences of the RMP in different regions of the GI tract. Smooth muscle excitability is also regulated by interstitial cells (interstitial cells of Cajal (ICC) and PDGFRα(+) cells) that express additional conductances and are electrically coupled to SMC. Thus, 'myogenic' activity results from the integrated behavior of the SMC/ICC/PDGFRα(+) cell (SIP) syncytium. Inputs from excitatory and inhibitory motor neurons are required to produce the complex motor patterns of the gut. Motor neurons innervate three cell types in the SIP, and receptors, second messenger pathways, and ion channels in these cells mediate postjunctional responses. Studies of isolated SIP cells have begun to unravel the mechanisms responsible for neural responses. This review discusses ion channels that set and regulate RMP of SIP cells and how neurotransmitters regulate membrane potential.

  2. Behavior of ionic conducting IPN actuators in simulated space conditions

    NASA Astrophysics Data System (ADS)

    Fannir, Adelyne; Plesse, Cédric; Nguyen, Giao T. M.; Laurent, Elisabeth; Cadiergues, Laurent; Vidal, Frédéric

    2016-04-01

    The presentation focuses on the performances of flexible all-polymer electroactive actuators under space-hazardous environmental factors in laboratory conditions. These bending actuators are based on high molecular weight nitrile butadiene rubber (NBR), poly(ethylene oxide) (PEO) derivative and poly(3,4-ethylenedioxithiophene) (PEDOT). The electroactive PEDOT is embedded within the PEO/NBR membrane which is subsequently swollen with an ionic liquid as electrolyte. Actuators have been submitted to thermal cycling test between -25 to 60°C under vacuum (2.4 10-8 mbar) and to ionizing Gamma radiations at a level of 210 rad/h during 100 h. Actuators have been characterized before and after space environmental condition ageing. In particular, the viscoelasticity properties and mechanical resistance of the materials have been determined by dynamic mechanical analysis and tensile tests. The evolution of the actuation properties as the strain and the output force have been characterized as well. The long-term vacuuming, the freezing temperature and the Gamma radiations do not affect significantly the thermomechanical properties of conducting IPNs actuators. Only a slight decrease on actuation performances has been observed.

  3. Multilayered semiconductor membranes for nanopore ionic conductance modulation.

    PubMed

    Gracheva, Maria E; Melnikov, Dmitriy V; Leburton, Jean-Pierre

    2008-11-25

    We explore the possibility of using thin layered semiconductor membranes for electrical control of the ion current flow through a nanopore, thereby operating like tunable ionic transistors. While single layer semiconductor membranes can be voltage tuned to operate as ionic filters or "switches", double layered membranes can rectify the ion current flowing through the nanopore in addition to ion filtering. Triple layer membranes exhibit enhanced functionality with characteristics similar to those of the single and double layer membranes in addition to bidirectional current blocking and switching, thereby operating similar to tunable ionic transistors.

  4. Facile synthesis of supramolecular ionic polymers that combine unique rheological, ionic conductivity, and self-healing properties.

    PubMed

    Aboudzadeh, M Ali; Muñoz, M Eugenia; Santamaría, Antxon; Marcilla, Rebeca; Mecerreyes, David

    2012-02-27

    A new family of supramolecular ionic polymers is synthesized by a simple method using (di-/tri-)carboxylic acids and (di-/tri-)alkyl amines. These polymers are formed by carboxylate and ammonium molecules that are weakly bonded together by a combination of ionic and hydrogen bonds, becoming solid at room temperature. The supramolecular ionic polymers show a sharp rheological transition from a viscoelastic gel to a viscous liquid between 30 and 80 °C. This sharp viscosity decrease is responsible for an unprecedented jump in ionic conductivity of four orders of magnitude in that temperature range. As a potential application, this chemistry can be used to develop polymeric materials with self-healing properties, since it combines properties from supramolecular polymers and ionomers into the same material. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Lithium ion conductive behavior of TiO2 nanotube/ionic liquid matrices

    PubMed Central

    2014-01-01

    A series of TiO2 nanotube (TNT)/ionic liquid matrices were prepared, and their lithium ion conductive properties were studied. SEM images implied that ionic liquid was dispersed on the whole surface of TNT. Addition of TNT to ionic liquid (1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide (BMImTFSA)) resulted in significant increase of ionic conductivity. Furthermore, lithium transference number was also largely enhanced due to the interaction of anion with TNT. Vogel-Fulcher-Tammann parameter showed higher carrier ion number for TNT/BMImTFSA in comparison with BMImTFSA. PMID:25313300

  6. Correlating Humidity-Dependent Ionically Conductive Surface Area with Transport Phenomena in Proton-Exchange Membranes

    SciTech Connect

    He, Qinggang; Kusoglu, Ahmet; Lucas, Ivan T.; Clark, Kyle; Weber, Adam Z.; Kostecki, Robert

    2011-08-01

    The objective of this effort was to correlate the local surface ionic conductance of a Nafion? 212 proton-exchange membrane with its bulk and interfacial transport properties as a function of water content. Both macroscopic and microscopic proton conductivities were investigated at different relative humidity levels, using electrochemical impedance spectroscopy and current-sensing atomic force microscopy (CSAFM). We were able to identify small ion-conducting domains that grew with humidity at the surface of the membrane. Numerical analysis of the surface ionic conductance images recorded at various relative humidity levels helped determine the fractional area of ion-conducting active sites. A simple square-root relationship between the fractional conducting area and observed interfacial mass-transport resistance was established. Furthermore, the relationship between the bulk ionic conductivity and surface ionic conductance pattern of the Nafion? membrane was examined.

  7. Ion jelly conductive properties using dicyanamide-based ionic liquids.

    PubMed

    Carvalho, Tânia; Augusto, Vera; Rocha, Ângelo; Lourenço, Nuno M T; Correia, Natália T; Barreiros, Susana; Vidinha, Pedro; Cabrita, Eurico J; Dionísio, Madalena

    2014-08-07

    The thermal behavior and transport properties of several ion jellys (IJs), a composite that results from the combination of gelatin with an ionic liquid (IL), were investigated by dielectric relaxation spectroscopy (DRS), differential scanning calorimetry (DSC), and pulsed field gradient nuclear magnetic resonance spectroscopy (PFG NMR). Four different ILs containing the dicyanamide anion were used: 1-butyl-3-methylimidazolium dicyanamide (BMIMDCA), 1-ethyl-3-methylimidazolium dicyanamide (EMIMDCA), 1-butyl-1-methylpyrrolidinium dicyanamide (BMPyrDCA), and 1-butylpyridinium dicyanamide (BPyDCA); the bulk ILs were also investigated for comparison. A glass transition was detected by DSC for all materials, ILs and IJs, allowing them to be classified as glass formers. Additionally, an increase in the glass transition temperature upon dehydration was observed with a greater extent for IJs, attributed to a greater hindrance imposed by the gelatin matrix after water removal, rendering the IL less mobile. While crystallization is observed for some ILs with negligible water content, it was never detected for any IJ upon thermal cycling, which persist always as fully amorphous materials. From DRS measurements, conductivity and diffusion coefficients for both cations (D+) and anions (D-) were extracted. D+ values obtained by DRS reveal excellent agreement with those obtained from PFG NMR direct measurements, obeying the same VFTH equation over a large temperature range (ΔT ≈ 150 K) within which D+ varies around 10 decades. At temperatures close to room temperature, the IJs exhibit D values comparable to the most hydrated (9%) ILs. The IJ derived from EMIMDCA possesses the highest conductivity and diffusion coefficient, respectively, ∼10(-2) S·cm(-1) and ∼10(-10) m(2)·s(-1). For BMPyrDCA the relaxational behavior was analyzed through the complex permittivity and modulus formalism allowing the assignment of the detected secondary relaxation to a Johari

  8. Programmable ionic conductance in a pH-regulated gated nanochannel.

    PubMed

    Ma, Yu; Xue, Song; Hsu, Shih-Chieh; Yeh, Li-Hsien; Qian, Shizhi; Tan, Heping

    2014-10-07

    An analytical model for the ionic conductance in a pH-regulated nanochannel gated by a field effect transistor is derived for the first time. In contrast to the existing studies, the developed model takes into account the practical effects of multiple ionic species, surface chemistry reactions, the Stern layer, and electroosmotic flow. The model is validated by the experimental data of ionic conductance available in the literature. Results show that the performance of the field effect control of the ionic conductance in the gated silica nanochannel is remarkable when the solution pH and salt concentration are low. In addition, the Stern layer effect on the ionic conductance is significant when the salt concentration is low.

  9. Ternary mixtures of ionic liquids for better salt solubility, conductivity and cation transference number improvement

    PubMed Central

    Karpierz, E.; Niedzicki, L.; Trzeciak, T.; Zawadzki, M.; Dranka, M.; Zachara, J.; Żukowska, G. Z.; Bitner-Michalska, A.; Wieczorek, W.

    2016-01-01

    We hereby present the new class of ionic liquid systems in which lithium salt is introduced into the solution as a lithium cation−glyme solvate. This modification leads to the reorganisation of solution structure, which entails release of free mobile lithium cation solvate and hence leads to the significant enhancement of ionic conductivity and lithium cation transference numbers. This new approach in composing electrolytes also enables even three-fold increase of salt concentration in ionic liquids. PMID:27767069

  10. Enhanced low-temperature ionic conductivity via different Li(+) solvated clusters in organic solvent/ionic liquid mixed electrolytes.

    PubMed

    Aguilera, Luis; Scheers, Johan; Matic, Aleksandar

    2016-09-14

    We investigate Li(+) coordination in mixed electrolytes based on ionic liquids (ILs) and organic solvents and its relation with the macroscopic properties such as phase behaviour and ionic conductivity. Using Raman spectroscopy we determine the solvation shell around Li(+) in mixtures formed by the IL N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, the organic solvents ethylene carbonate and dimethyl carbonate (EC : DMC 1 : 1), and the salt LiTFSI. We find that the organic solvent molecules preferentially solvate Li(+) as long as there are enough of them. Our results are consistent with a model where Li(EC)3(DMC)1 and Li(EC)2(DMC)2 are the main complexes formed by the organic solvent molecules and where TFSI(-) mainly participates in Li(TFSI)2(-) clusters. As the amount of organic solvent is increased, the number of TFSI(-) around Li(+) rapidly decreases showing a higher affinity of the organic solvents to solvate Li(+). The changes in the local configurations are also reflected in the ionic conductivity and the phase behaviour. The formation of larger clusters leads to a decrease in the conductivity, whereas the presence of several different clusters at intermediate compositions effectively hinders crystallization at low temperatures. The result is an enhanced low-temperature ionic conductivity in comparison with the pure IL or organic solvent electrolytes.

  11. Conductivity-Relaxation Relations in Nanocomposite Polymer Electrolytes Containing Ionic Liquid.

    PubMed

    Shojaatalhosseini, Mansoureh; Elamin, Khalid; Swenson, Jan

    2017-10-04

    In this study, we have used nanocomposite polymer electrolytes, consisting of poly(ethylene oxide) (PEO), δ-Al2O3 nanoparticles, and lithium bis(trifluoromethanesolfonyl)imide (LiTFSI) salt (with 4 wt % δ-Al2O3 and PEO:Li ratios of 16:1 and 8:1), and added different amounts of the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesolfonyl)imide (BMITFSI). The aim was to elucidate whether the ionic liquid is able to dissociate the Li-ions from the ether oxygens and thereby decouple the ionic conductivity from the segmental polymer dynamics. The results from DSC and dielectric spectroscopy show that the ionic liquid speeds up both the segmental polymer dynamics and the motion of the Li(+) ions. However, a close comparison between the structural (α) relaxation process, given by the segmental polymer dynamics, and the ionic conductivity shows that the motion of the Li(+) ions decouples from the segmental polymer dynamics at higher concentrations of the ionic liquid (≥20 wt %) and instead becomes more related to the viscosity of the ionic liquid. This decoupling increases with decreasing temperature. In addition to the structural α-relaxation, two more local relaxation processes, denoted β and γ, are observed. The β-relaxation becomes slightly faster at the highest concentration of the ionic liquid (at least for the lower salt concentration), whereas the γ-relaxation is unaffected by the ionic liquid, over the whole concentration range 0-40 wt %.

  12. Fundamental Studies on Confinement Effects in Ionic Conduction and Inversion Layers in 2-D Single Crystal Free Standing Oxide Membranes

    DTIC Science & Technology

    2014-02-14

    terminal field effect device geometry using ionic liquid gate dielectric. Here, we investigate electrolyte gating with ionic liquid on the electrical...treatments. Ionic liquids are molten salts with high ionic conductivity but negligible electronic conductivity and have been used to modify carrier...gate bias as long as the ambient temperature does not approach the melting temperature. The ionic liquid used in the electrolyte gating experiments

  13. Photochemical switching of ionic conductivity in composite films containing a crowned spirobenzopyran

    SciTech Connect

    Kimura, Keiichi; Yamashita, Takashi; Yokoyama, Masaaki

    1992-06-25

    Photochemical switching of ionic conductivity in vinyl chloride films with LiClO{sub 4} and a crowned spirobenzopyran revealed isomerization of the crowned spirobenzopyran to its merocyanine form proceeding under UV-irradiated or dark conditions to decrease the the film`s Li{sup +} ionic conductivity in this paper. Visible-light irradiation caused isomerization back to the spiropyran form and restoration of ionic conductivity to its original value; switching the visible light on and off caused 20-fold changes. 10 refs., 7 figs.

  14. Ionic Conduction in Lithium Ion Battery Composite Electrode Governs Cross-sectional Reaction Distribution

    PubMed Central

    Orikasa, Yuki; Gogyo, Yuma; Yamashige, Hisao; Katayama, Misaki; Chen, Kezheng; Mori, Takuya; Yamamoto, Kentaro; Masese, Titus; Inada, Yasuhiro; Ohta, Toshiaki; Siroma, Zyun; Kato, Shiro; Kinoshita, Hajime; Arai, Hajime; Ogumi, Zempachi; Uchimoto, Yoshiharu

    2016-01-01

    Composite electrodes containing active materials, carbon and binder are widely used in lithium-ion batteries. Since the electrode reaction occurs preferentially in regions with lower resistance, reaction distribution can be happened within composite electrodes. We investigate the relationship between the reaction distribution with depth direction and electronic/ionic conductivity in composite electrodes with changing electrode porosities. Two dimensional X-ray absorption spectroscopy shows that the reaction distribution is happened in lower porosity electrodes. Our developed 6-probe method can measure electronic/ionic conductivity in composite electrodes. The ionic conductivity is decreased for lower porosity electrodes, which governs the reaction distribution of composite electrodes and their performances. PMID:27193448

  15. Ionic Conduction in Lithium Ion Battery Composite Electrode Governs Cross-sectional Reaction Distribution

    NASA Astrophysics Data System (ADS)

    Orikasa, Yuki; Gogyo, Yuma; Yamashige, Hisao; Katayama, Misaki; Chen, Kezheng; Mori, Takuya; Yamamoto, Kentaro; Masese, Titus; Inada, Yasuhiro; Ohta, Toshiaki; Siroma, Zyun; Kato, Shiro; Kinoshita, Hajime; Arai, Hajime; Ogumi, Zempachi; Uchimoto, Yoshiharu

    2016-05-01

    Composite electrodes containing active materials, carbon and binder are widely used in lithium-ion batteries. Since the electrode reaction occurs preferentially in regions with lower resistance, reaction distribution can be happened within composite electrodes. We investigate the relationship between the reaction distribution with depth direction and electronic/ionic conductivity in composite electrodes with changing electrode porosities. Two dimensional X-ray absorption spectroscopy shows that the reaction distribution is happened in lower porosity electrodes. Our developed 6-probe method can measure electronic/ionic conductivity in composite electrodes. The ionic conductivity is decreased for lower porosity electrodes, which governs the reaction distribution of composite electrodes and their performances.

  16. The Effect of Long Range Order on Ionic Conductivity in a Solid Block Copolymer Electrolyte

    NASA Astrophysics Data System (ADS)

    Chintapalli, Mahati; Thelen, Jacob; Teran, Alexander; Balsara, Nitash

    2014-03-01

    Poly(styrene)-block-poly(ethylene oxide) (SEO) mixed with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt is a promising material for battery electrolytes due to its high ionic conductivity and ability to suppress lithium dendrite growth. Ion conduction has been found to depend on many aspects of the electrolyte microstructure, including the morphology and degree of ordering. The effect of long range order on ionic conductivity was investigated in a lamellar SEO/LiTFSI mixture by in situ small angle x-ray scattering and ac impedance spectroscopy during polymer annealing. The observation that increasing long range order decreases ionic conductivity indicates that disorder, due to small grain size or defects, enhances the ionic conductivity of the electrolyte.

  17. Li Ion Conducting Polymer Gel Electrolytes Based on Ionic Liquid/PVDF-HFP Blends

    PubMed Central

    Ye, Hui; Huang, Jian; Xu, Jun John; Khalfan, Amish; Greenbaum, Steve G.

    2009-01-01

    Ionic liquids thermodynamically compatible with Li metal are very promising for applications to rechargeable lithium batteries. 1-methyl-3-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P13TFSI) is screened out as a particularly promising ionic liquid in this study. Dimensionally stable, elastic, flexible, nonvolatile polymer gel electrolytes (PGEs) with high electrochemical stabilities, high ionic conductivities and other desirable properties have been synthesized by dissolving Li imide salt (LiTFSI) in P13TFSI ionic liquid and then mixing the electrolyte solution with poly(vinylidene-co-hexafluoropropylene) (PVDF-HFP) copolymer. Adding small amounts of ethylene carbonate to the polymer gel electrolytes dramatically improves the ionic conductivity, net Li ion transport concentration, and Li ion transport kinetics of these electrolytes. They are thus favorable and offer good prospects in the application to rechargeable Li batteries including open systems like Li/air batteries, as well as more “conventional” rechargeable lithium and lithium ion batteries. PMID:20354587

  18. Engineered Ionic Gates for Ion Conduction Based on Sodium and Potassium Activated Nanochannels.

    PubMed

    Liu, Qian; Xiao, Kai; Wen, Liping; Lu, Heng; Liu, Yahui; Kong, Xiang-Yu; Xie, Ganhua; Zhang, Zhen; Bo, Zhishan; Jiang, Lei

    2015-09-23

    In living systems, ion conduction plays a major role in numerous cellular processes and can be controlled by biological ion channels in response to specific environmental stimuli. This article describes biomimetic ionic gates for ion conduction based on sodium and potassium activated nanochannels. The Na(+) activated ionic gate and K(+) activated ionic gate were developed by immobilizing the alkali metal cation-responsive functional molecules, 4'-aminobenzo-15-crown-5 and 4'-aminobenzo-18-crown-6, respectively, onto the conical polyimide nanochannels. When the ionic gate was in the presence of the specific alkali metal cation, positively charged complexes formed between the crown ether and the alkali metal cation. On the basis of the resulting changes in surface charge, wettability and effective pore size, the nanochannel can achieve reversible switching. The switching behaviors of the two complexes differed due to the differences in binding strength between the two complexes. The Na(+) activated ionic gate is able to open and close to control the ion conduction through the nanochannel, and the K(+) activated ionic gate enables selective cation and anion conduction through the nanochannel. The Na(+) and K(+) activated ionic gates show great promise for use in clinical medicine, biosensors and drug delivery based on their high sensitivity and selectivity of being activated, and good stability.

  19. Study on Ion-Conducting Properties of Ionic Liquid Containing Carbonate Electrolytes Against Carbon Electrode.

    PubMed

    Choi, Bo-Ra; Park, Soo-Jin; Kim, Seok

    2016-03-01

    The ionic performances for the mixture of ethylene carbonate (EC) and dimethylcarbonate (DMC) were investigated for supercapacitor electrolyte. The usage of ethylene carbonate (EC) and dimethylcarbonate (DMC) as organic solvent could solve some problems of acetonitrile (AN). The general aim of present paper is compare to properties of electrochemical properties based on two mixed organic electrolytes. The ionic conductivity, viscosity, and electrochemical performances of EC/DMC+0.1 M TEABF4 mixtures were determined. The ionic conductivity of the electrolytes was measured by AC impedance, and the capacitative performances of the electrolytes were evaluated by using cyclic voltammetry.

  20. Defect Physics and Ionic conduction in Solid Electrolyte Interphase for Lithium Ion Batteries

    NASA Astrophysics Data System (ADS)

    Pan, Jie; Cheng, Yang-Tse; Qi, Yue

    The ionic conduction through the solid electrolyte interphase (SEI) is important to the rate capability of the battery. The origin of ionic conduction in the SEI is defect formation and transport. In this study, we developed a theoretical method based on density functional theory to calculate the ionic conductivity in LiF, an important SEI component, in contact with electrode materials. Seventeen native defects with their relevant charge states were investigated to determine the dominant defects on various electrodes. The contacted electrode serves as a Li reservoir with adjustable Li chemical potential (μLi) for defect formation. The formation energy and diffusion barrier of defects were mapped to ionic conductivity by the Nernst-Einstein relationship. The main defect is Schottky pair in the intrinsic region and Li ion vacancy in the p-type region. The ionic conductivity is calculated to be approximately 10-31 S/cm when LiF is in contact with an anode but it can increase to 10-12 S/cm on a cathode. Comparing with other SEI components, the ionic conductivity is very low in LiF if it is coated on an anode surface. However, due to the low concentration of electronic carriers, LiF can act as a good passivation layer on the electrode and prevent further electrolyte decomposition. This work is supported by Department of Energy and National Science Foundation.

  1. High Pressure as a Key Factor to Identify the Conductivity Mechanism in Protic Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Wojnarowska, Z.; Wang, Y.; Pionteck, J.; Grzybowska, K.; Sokolov, A. P.; Paluch, M.

    2013-11-01

    In this Letter we report the relation between ionic conductivity and structural relaxation in supercooled protic ionic liquids (PILs) under high pressure. The results of high-pressure dielectric and volumetric measurements, combined with rheological and temperature-modulated differential scanning calorimetry experiments, have revealed a fundamental difference between the conducting properties under isothermal and isobaric conditions for three PILs with different charge transport mechanisms (Grotthuss vs vehicle). Our findings indicate a breakdown of the fractional Stokes-Einstein relation and Walden rule when the ionic transport is controlled by fast proton hopping. Consequently, we demonstrate that the studied PILs exhibit significantly higher conductivity than one would expect taking into account that they are in fact a mixture of ionic and neutral species. Thus, the examined herein samples represent a new class of “superionic” materials desired for many advanced applications.

  2. UV cross-linked, lithium-conducting ternary polymer electrolytes containing ionic liquids

    NASA Astrophysics Data System (ADS)

    Kim, G. T.; Appetecchi, G. B.; Carewska, M.; Joost, M.; Balducci, A.; Winter, M.; Passerini, S.

    In this manuscript is reported an attempt to prepare high ionic conductivity lithium polymer electrolytes by UV cross-linking the poly(ethyleneoxide) (briefly called PEO) polymer matrix in presence of the plasticizing lithium salt, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and an ionic liquid of the pyrrolidinium family (N-alkyl- N-methylpyrrolidinium TFSI) having a common anion with the lithium salt. It is demonstrated that polymer electrolytes with room temperature ionic conductivities of nearly 10 -3 S cm -1 could be obtained as a result of the reduced crystallinity of the ternary electrolytes. The results clearly indicate that the cross-linked ternary electrolyte shows superior mechanical properties with respect to the non-cross-linked electrolytes and higher conductivities with respect to polymer electrolytes containing none or less ionic liquid.

  3. Fast dynamic holographic recording based on conductive ionic metal-alkanoate liquid crystals and smectic glasses.

    PubMed

    Klimusheva, G; Bugaychuk, S; Garbovskiy, Yu; Kolesnyk, O; Mirnaya, T; Ishchenko, A

    2006-01-15

    Recordings of dynamic holograms with microsecond relaxation times under the action of nanosecond laser pulses are obtained in composites on the base of a novel class of liquid crystals (LCs) in ionic metal-alkanoates. Holographic parameters and relaxation characteristics are measured for doped lyotropic ionic LC, for sandwichlike cells (consisting of a dye layer and a layer of the lyotropic ionic LC), and for colored ionic smectic glasses. The structure of the materials is investigated by use of the small-angle x-ray technique. The mechanism of resonance nonlinearity in photosensitive centers and mechanisms of the grating erasure connected with a charge transport in the ionic conductive LC matrix are discussed.

  4. Influence of Electrical and Ionic Conductivities of Organic Electronic Ion Pump on Acetylcholine Exchange Performance

    PubMed Central

    Abdullayeva, Nazrin; Sankir, Mehmet

    2017-01-01

    By using an easy and effective method of depositing conjugated polymers (PEDOT:PSS) on flexible substrates, a new design for organic bioelectronic devices has been developed. The purpose was to build up a system that mimics the motion of neurotransmitters in the synaptic cleft by obtaining an electrical to chemical signal transport. Fourier transform infrared (FTIR) spectroscopy and Raman measurements have demonstrated that electrochemical overoxidation region which separates the pristine PEDOT:PSS electrodes and allows ionic conduction has been achieved successfully. The influence of both electrical and ionic conductivities on organic electronic ion pump (OEIP) performances has been studied. The ultimate goal was to achieve the highest equilibrium current density at the lowest applied voltage via enhancing the electrical conductivity of PEDOT:PSS and ionic conductivity of electrochemically overoxidized region. The highest equilibrium current density, which corresponds to 4.81 × 1017 number of ions of acetylcholine was about 41 μA cm−2 observed for the OEIP with the electrical conductivities of 54 S cm−1. This was a threshold electrical conductivity beyond which the OEIP performances were not changed much. Once Nafion™ has been applied for enhancing the ionic conductivity, the equilibrium current density increased about ten times and reached up to 408 μA cm−2. Therefore, it has been demonstrated that the OEIP performance mainly scales with the ionic conductivity. A straightforward method of producing organic bioelectronics is proposed here may provide a clue for their effortless mass production in the near future. PMID:28772946

  5. Highly Hydroxide-Conductive Nanostructured Solid Electrolyte via Predesigned Ionic Nanoaggregates.

    PubMed

    He, Guangwei; Xu, Mingzhao; Li, Zongyu; Wang, Shaofei; Jiang, Shentao; He, Xueyi; Zhao, Jing; Li, Zhen; Wu, Xingyu; Huang, Tong; Chang, Chaoyi; Yang, Xinlin; Wu, Hong; Jiang, Zhongyi

    2017-08-30

    The creation of interconnected ionic nanoaggregates within solid electrolytes is a crucial yet challenging task for fabricating high-performance alkaline fuel cells. Herein, we present a facile and generic approach to embedding ionic nanoaggregates via predesigned hybrid core-shell nanoarchitecture within nonionic polymer membranes as follows: (i) synthesizing core-shell nanoparticles composed of SiO2/densely quaternary ammonium-functionalized polystyrene. Because of the spatial confinement effect of the SiO2 "core", the abundant hydroxide-conducting groups are locally aggregated in the functionalized polystyrene "shell", forming ionic nanoaggregates bearing intrinsic continuous ion channels; (ii) embedding these ionic nanoaggregates (20-70 wt %) into the polysulfone matrix to construct interconnected hydroxide-conducting channels. The chemical composition, physical morphology, amount, and distribution of the ionic nanoaggregates are facilely regulated, leading to highly connected ion channels with high effective ion mobility comparable to that of the state-of-the-art Nafion. The resulting membranes display strikingly high hydroxide conductivity (188.1 mS cm(-1) at 80 °C), which is one of the highest results to date. The membranes also exhibit good mechanical properties. The independent manipulation of the conduction function and nonconduction function by the ionic nanoaggregates and nonionic polymer matrix, respectively, opens a new avenue, free of microphase separation, for designing high-performance solid electrolytes for diverse application realms.

  6. Solid electrolytes for fluoride ion batteries: ionic conductivity in polycrystalline tysonite-type fluorides.

    PubMed

    Rongeat, Carine; Reddy, M Anji; Witter, Raiker; Fichtner, Maximilian

    2014-02-12

    Batteries based on a fluoride shuttle (fluoride ion battery, FIB) can theoretically provide high energy densities and can thus be considered as an interesting alternative to Li-ion batteries. Large improvements are still needed regarding their actual performance, in particular for the ionic conductivity of the solid electrolyte. At the current state of the art, two types of fluoride families can be considered for electrolyte applications: alkaline-earth fluorides having a fluorite-type structure and rare-earth fluorides having a tysonite-type structure. As regard to the latter, high ionic conductivities have been reported for doped LaF3 single crystals. However, polycrystalline materials would be easier to implement in a FIB due to practical reasons in the cell manufacturing. Hence, we have analyzed in detail the ionic conductivity of La(1-y)Ba(y)F(3-y) (0 ≤ y ≤ 0.15) solid solutions prepared by ball milling. The combination of DC and AC conductivity analyses provides a better understanding of the conduction mechanism in tysonite-type fluorides with a blocking effect of the grain boundaries. Heat treatment of the electrolyte material was performed and leads to an improvement of the ionic conductivity. This confirms the detrimental effect of grain boundaries and opens new route for the development of solid electrolytes for FIB with high ionic conductivities.

  7. Nanoscale mapping of electromechanical response in ionic conductive ceramics with piezoelectric inclusions

    SciTech Connect

    Seol, Daehee; Seo, Hosung; Jesse, Stephen; Kim, Yunseok

    2015-08-19

    Electromechanical (EM) response in ion conductive ceramics with piezoelectric inclusions was spatially explored using strain-based atomic force microscopy. Since the sample is composed of two dominant phases of ionic and piezoelectric phases, it allows us to explore two different EM responses of electrically induced ionic response and piezoresponse over the same surface. Furthermore, EM response of the ionic phase, i.e., electrochemical strain, was quantitatively investigated from the comparison with that of the piezoelectric phase, i.e., piezoresponse. Finally, these results could provide additional information on the EM properties, including the electrochemical strain at nanoscale.

  8. Nanoscale mapping of electromechanical response in ionic conductive ceramics with piezoelectric inclusions

    DOE PAGES

    Seol, Daehee; Seo, Hosung; Jesse, Stephen; ...

    2015-08-19

    Electromechanical (EM) response in ion conductive ceramics with piezoelectric inclusions was spatially explored using strain-based atomic force microscopy. Since the sample is composed of two dominant phases of ionic and piezoelectric phases, it allows us to explore two different EM responses of electrically induced ionic response and piezoresponse over the same surface. Furthermore, EM response of the ionic phase, i.e., electrochemical strain, was quantitatively investigated from the comparison with that of the piezoelectric phase, i.e., piezoresponse. Finally, these results could provide additional information on the EM properties, including the electrochemical strain at nanoscale.

  9. Nanoscale mapping of electromechanical response in ionic conductive ceramics with piezoelectric inclusions

    SciTech Connect

    Seol, Daehee; Seo, Hosung; Kim, Yunseok; Jesse, Stephen

    2015-08-21

    Electromechanical (EM) response in ion conductive ceramics with piezoelectric inclusions was spatially explored using strain-based atomic force microscopy. Since the sample is composed of two dominant phases of ionic and piezoelectric phases, it allows us to explore two different EM responses of electrically induced ionic response and piezoresponse over the same surface. Furthermore, EM response of the ionic phase, i.e., electrochemical strain, was quantitatively investigated from the comparison with that of the piezoelectric phase, i.e., piezoresponse. These results could provide additional information on the EM properties, including the electrochemical strain at nanoscale.

  10. TOPICAL REVIEW Ionic conductivity in oxide heterostructures: the role of interfaces

    NASA Astrophysics Data System (ADS)

    Fabbri, Emiliana; Pergolesi, Daniele; Traversa, Enrico

    2010-10-01

    Rapidly growing attention is being directed to the investigation of ionic conductivity in oxide film heterostructures. The main reason for this interest arises from interfacial phenomena in these heterostructures and their applications. Recent results revealed that heterophase interfaces have faster ionic conduction pathways than the bulk or homophase interfaces. This finding can open attractive opportunities in the field of micro-ionic devices. The influence of the interfaces on the conduction properties of heterostructures is becoming increasingly important with the miniaturization of solid-state devices, which leads to an enhanced interface density at the expense of the bulk. This review aims to describe the main evidence of interfacial phenomena in ion-conducting film heterostructures, highlighting the fundamental and technological relevance and offering guidelines to understanding the interface conduction mechanisms in these structures.

  11. Ionic conductivity and thermoelectric power of pure and Al2O3-dispersed AgI

    NASA Technical Reports Server (NTRS)

    Shahi, K.; Wagner, J. B., Jr.

    1981-01-01

    Ionic and electronic conductivities, and thermoelectric power have been measured for AgI and AgI containing a dispersion of submicron size Al2O3 particles. While the dispersion of Al2O3 enhances the ionic conductivity significantly, it does not affect the electronic properties of the matrix. The enhancement is a strong function of the size and concentration of the dispersoid. Various models have been tested to account for the enhanced conduction. However, the complex behavior of the present results points out the need for more sophisticated theoretical models. Ionic conduction and thermoelectric power data suggest that the dispersed Al2O3 generates an excess of cation vacancies and thereby enhances the conductivity and suppresses the thermoelectric power of the matrix. The individual heats of transport of cation interstitials and vacancies have been estimated and compared to their respective migration energies.

  12. Structure and Ionic Conductivity Evolution of a Block Copolymer Electrolyte during Thermal Annealing

    NASA Astrophysics Data System (ADS)

    Chintapalli, Mahati; Balsara, Nitash

    2015-03-01

    Mixtures of block copolymers (BCPs) and lithium salts are promising materials for battery electrolytes because they exhibit high ionic conductivity and high modulus. However, since most polymer electrolytes show high conductivities only at temperatures above ambient, it is important to understand how the structure and ionic conductivity of BCP electrolytes evolve during thermal annealing. In situ small angle X-ray scattering and ac impedance spectroscopy were used to characterize a BCP electrolyte, lamellar polystyrene-block-poly(ethylene oxide) mixed with lithium bis(trifluoromethanesulfonylimide) (LiTFSI), during thermal annealing. As annealing progressed, long range lamellar order and domain spacing increased, and scattering contrast between the two BCP phases decreased. A concomitant decrease in ionic conductivity was observed.

  13. Solvent effects on polysulfide redox kinetics and ionic conductivity in lithium-sulfur batteries

    SciTech Connect

    Fan, Frank Y.; Pan, Menghsuan Sam; Lau, Kah Chun; Assary, Rajeev S.; Woodford, William H.; Curtiss, Larry A.; Carter, W. Craig; Chiang, Yet -Ming

    2016-11-25

    Lithium-sulfur (Li-S) batteries have high theoretical energy density and low raw materials cost compared to present lithium-ion batteries and are thus promising for use in electric transportation and other applications. A major obstacle for Li-S batteries is low rate capability, especially at the low electrolyte/sulfur (E/S) ratios required for high energy density. Herein, we investigate several potentially rate-limiting factors for Li-S batteries. We study the ionic conductivity of lithium polysulfide solutions of varying concentration and in different ether-based solvents and their exchange current density on glassy carbon working electrodes. We believe this is the first such investigation of exchange current density for lithium polysulfide in solution. Exchange current densities are measured using both electrochemical impedance spectroscopy and steady-state galvanostatic polarization. In the range of interest (1-8 M [S]), the ionic conductivity monotonically decreases with increasing sulfur concentration while exchange current density shows a more complicated relationship to sulfur concentration. The electrolyte solvent dramatically affects ionic conductivity and exchange current density. Finally, the measured ionic conductivities and exchange current densities are also used to interpret the overpotential and rate capability of polysulfide-nanocarbon suspensions; this analysis demonstrates that ionic conductivity is the rate-limiting property in the solution regime (i.e. between Li2S8 and Li2S4).

  14. Solvent effects on polysulfide redox kinetics and ionic conductivity in lithium-sulfur batteries

    DOE PAGES

    Fan, Frank Y.; Pan, Menghsuan Sam; Lau, Kah Chun; ...

    2016-11-25

    Lithium-sulfur (Li-S) batteries have high theoretical energy density and low raw materials cost compared to present lithium-ion batteries and are thus promising for use in electric transportation and other applications. A major obstacle for Li-S batteries is low rate capability, especially at the low electrolyte/sulfur (E/S) ratios required for high energy density. Herein, we investigate several potentially rate-limiting factors for Li-S batteries. We study the ionic conductivity of lithium polysulfide solutions of varying concentration and in different ether-based solvents and their exchange current density on glassy carbon working electrodes. We believe this is the first such investigation of exchange currentmore » density for lithium polysulfide in solution. Exchange current densities are measured using both electrochemical impedance spectroscopy and steady-state galvanostatic polarization. In the range of interest (1-8 M [S]), the ionic conductivity monotonically decreases with increasing sulfur concentration while exchange current density shows a more complicated relationship to sulfur concentration. The electrolyte solvent dramatically affects ionic conductivity and exchange current density. Finally, the measured ionic conductivities and exchange current densities are also used to interpret the overpotential and rate capability of polysulfide-nanocarbon suspensions; this analysis demonstrates that ionic conductivity is the rate-limiting property in the solution regime (i.e. between Li2S8 and Li2S4).« less

  15. Effects of plasticization on ionic conductivity enhancement of crosslinked polymer electrolyte membrane

    NASA Astrophysics Data System (ADS)

    He, Ruixuan; Kyu, Thein; Kyu's Team, Dr.

    Glass transition temperatures (Tg) of solid polymer electrolyte membranes (PEM), comprised of polyethylene glycol diacrylate (PEGDA) prepolymer, lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt, and succinonitrile (SCN) plasticizer, were systematically examined before and after crosslinking in the isotropic region guided by their ternary phase diagram. With increasing LiTFSI concentration, the Tg of uncured binary PEGDA/LiTFSI mixture increases drastically due to molecular complexation between lithium cation and ether oxygen, but ionic conductivity is very low (<10-6 S cm-1). Upon curing, this Tg increases and further reduces ionic conductivity. Upon adding SCN plasticizer, the Tg of PEM has significantly decreased to -60 oC and ionic conductivity also increased to the superionic conductor level of 10-3 S cm-1. The analysis of ionic conductivity vs. Tg behavior by Vogel-Tamman-Fulcher(VTF) equation revealed that this ionic conductivity enhancement is due to SCN plasticization resulting in lowering the network Tg as well as lowering the activation energy. Supported by NSF-DMR 1161070.

  16. Enhancement of the ionic conductivity of olivine by the water incorporation based on the Mg diffusivity

    NASA Astrophysics Data System (ADS)

    Katsura, T.; Fei, H.; Koizumi, S.; Sakamoto, N.; Yurimoto, H.

    2016-12-01

    Although the water corporation has been considered to enhance the electrical conductivity of olivine by the proton conduction, the magnitude of the proton conduction is relatively small at asthenospheric temperatures because of its smaller activation energy than those of the small polaron and ionic conductions. However, the water incorporation could enhance the ionic conduction, because it should increase the defect density in the Mg sites. Since the ionic conductivity is proportional to the diffusivity, we have measured the self-diffusion coefficients of Mg in forsterite as a function of pressure, temperature and water content. We annealed fine-grained polycrystalline aggregates of forsterite with water contents up to 300 ppm, on whose polished plane a 25Mg-enriched Mg2SiO4 thin film was made, at pressures of 1 to 13 GPa and temperatures of 1100 to 1300 K. The lattice and grain-boundary diffusion coefficients were calculated simultaneously using profiles obtained by the depth analysis of SIMS. Experimental results gave the activation energy of 280 ± 30 and 360 ± 30 kJ/mol, activation volumes of 4.3 ± 0.3 and 3.9 ± 0.7 cm3/mol, and water content exponents of 1.2 ± 0.2 and 1.0 ± 0.1 for the lattice and grain-boundary diffusions, respectively. Using the ionic conduction data by Constable [2006] and Yoshino et al. [2009], and the water and pressure effects on Mg diffusivity in this study, the ionic conduction is found by 2 orders of magnitude higher than the small polaron and proton conductions under oceanic-asthenosphere conditions. Thus, the high conductivity of the oceanic asthenosphere will be governed by the water-enhanced ionic conduction. The negative pressure dependence of the Mg diffusivity and the gradual temperature increase in the asthenosphere will produce a conductivity maximum at the top of the asthenosphere. The high-conductivity layer at the top of the asthenosphere observed under very young oceanic plates can be attributed to this ionic

  17. Morphology and Ionic Conductivity of Block Copolymer Electrolytes Containing Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Park, Moon Jeong

    2015-03-01

    The global energy crisis and an increase in environmental pollution in the recent years have drawn the attention of the scientific community towards the development of efficient electrochemical devices. Polymers containing charged species have the potential to serve as electrolytes in next-generation devices and achieving high ion transport properties in these electrolytes is the key to improving their efficiency. Although the synthesis and characterization of a wide variety of ion-containing polymers have been extensively reported over the last decade, quantitative understanding of the factors governing the ion transport properties of these materials is in its infancy. In this talk, I will present the current understanding of the diverse factors affecting the thermodynamics, morphologies and ion transport of ion-containing polymers by focusing on the use of ionic liquids (ILs). Various strategies for accessing improved transport properties of IL-containing polymers are elucidated by focusing on the role of IL-polymer interactions. The major accomplishment of obtaining well-defined morphologies for these IL-containing polymers by the use of block copolymer is particularly emphasized as a novel means of controlling the transport properties. The application of IL-incorporated polymer electrolytes in high temperature fuel cells and electro-active actuators is also enclosed.

  18. Communication: Dimensionality of the ionic conduction pathways in glass and the mixed-alkali effect.

    PubMed

    Novy, Melissa; Avila-Paredes, Hugo; Kim, Sangtae; Sen, Sabyasachi

    2015-12-28

    A revised empirical relationship between the power law exponent of ac conductivity dispersion and the dimensionality of the ionic conduction pathway is established on the basis of electrical impedance spectroscopic (EIS) measurements on crystalline ionic conductors. These results imply that the "universal" ac conductivity dispersion observed in glassy solids is associated with ionic transport along fractal pathways. EIS measurements on single-alkali glasses indicate that the dimensionality of this pathway D is ∼2.5, while in mixed-alkali glasses, D is lower and goes through a minimum value of ∼2.2 when the concentrations of the two alkalis become equal. D and σ display similar variation with alkali composition, thus suggesting a topological origin of the mixed-alkali effect.

  19. Suppressed phase transition and giant ionic conductivity in La2Mo2O9 nanowires

    PubMed Central

    Liu, Wei; Pan, Wei; Luo, Jian; Godfrey, Andy; Ou, Gang; Wu, Hui; Zhang, Wei

    2015-01-01

    Improving the ionic conductivity of solid electrolytes at low temperatures represents a major challenge and an opportunity for enabling a variety of solid-state ionic devices for energy conversion and storage, as well as for environmental protection. Here we report a giant ionic conductivity of 0.20 Scm−1, achieved at 500 °C, in the La2Mo2O9 nanowires with a bamboo-wire morphology, corresponding to a 1000-fold enhancement in conductivity over conventional bulk material. Stabilization of the high-temperature phase is observed to account for about a 10-fold increase in the conductivity. We further demonstrate that fast surface conduction in ∼3 nm thick, partially ordered, surface ‘amorphous' films, under strain on the curved surfaces of the nanowires (as a non-autonomous surface phase or complexion), contributes to an enhancement of the conductivity by another two orders of magnitude. Exemplified here by the study of the La2Mo2O9 nanowires, new possibilities for improvement of conductivity and for miniaturization of solid-state ionic devices by the careful use of one-dimensional nanomaterials can be envisioned. PMID:26380943

  20. Suppressed phase transition and giant ionic conductivity in La2Mo2O9 nanowires.

    PubMed

    Liu, Wei; Pan, Wei; Luo, Jian; Godfrey, Andy; Ou, Gang; Wu, Hui; Zhang, Wei

    2015-09-18

    Improving the ionic conductivity of solid electrolytes at low temperatures represents a major challenge and an opportunity for enabling a variety of solid-state ionic devices for energy conversion and storage, as well as for environmental protection. Here we report a giant ionic conductivity of 0.20 Scm(-1), achieved at 500 °C, in the La2Mo2O9 nanowires with a bamboo-wire morphology, corresponding to a 1000-fold enhancement in conductivity over conventional bulk material. Stabilization of the high-temperature phase is observed to account for about a 10-fold increase in the conductivity. We further demonstrate that fast surface conduction in ∼3 nm thick, partially ordered, surface 'amorphous' films, under strain on the curved surfaces of the nanowires (as a non-autonomous surface phase or complexion), contributes to an enhancement of the conductivity by another two orders of magnitude. Exemplified here by the study of the La2Mo2O9 nanowires, new possibilities for improvement of conductivity and for miniaturization of solid-state ionic devices by the careful use of one-dimensional nanomaterials can be envisioned.

  1. Conductivity and electrophoretic mobility of dilute ionic solutions.

    PubMed

    Allison, Stuart; Wu, Hengfu; Twahir, Umar; Pei, Hongxia

    2010-12-01

    Two complementary continuum theories of electrokinetic transport are examined with particular emphasis on the equivalent conductance of binary electrolytes. The "small ion" model [R.M. Fuoss, L. Onsager, J. Phys. Chem. 61 (1957) 668] and "large ion" model [R.W. O'Brien, L.R. White, J. Chem. Soc. Faraday Trans. 2 (74) (1978) 1607] are both discussed and the "large ion" model is generalized to include an ion exclusion distance and to account in a simple but approximate way for the Brownian motion of all ions present. In addition, the "large ion" model is modified to treat "slip" hydrodynamic boundary conditions in addition to the standard "stick" boundary condition. Both models are applied to the equivalent conductance of dilute KCl, MgCl(2), and LaCl(3) solutions and both are able to reproduce experimental conductances to within an accuracy of several tenths of a percent. Despite fundamental differences in the "small ion" and "large ion" theories, they both work equally well in this application. In addition, both "stick-large ion" and "slip-large ion" models are equally capable of accounting for the equivalent conductances of the three electrolyte solutions.

  2. Ionic conductivity and dielectric permittivity of polymer electrolyte plasticized with polyethylene glycol

    NASA Astrophysics Data System (ADS)

    Das, S.; Ghosh, A.

    2016-05-01

    We have studied ionic conductivity and dielectric permittivity of PEO-LiClO4 solid polymer electrolyte plasticized with polyethylene glycol (PEG). The temperature dependence of the ionic conductivity has been well interpreted using Vogel-Tamman-Fulcher equation. The maximum dielectric constant is observed for 30 wt. % of PEG content. To get further insights into the ion dynamics, the complex dielectric permittivity has been studied with Havriliak-Negami function. The variation of relaxation time with inverse temperature obtained from HN formalism follows VTF nature.

  3. Preparation and characterization of nonaqueous proton-conducting membranes with protic ionic liquids.

    PubMed

    Lu, Fei; Gao, Xinpei; Yan, Xiaojun; Gao, Hejun; Shi, Lijuan; Jia, Han; Zheng, Liqiang

    2013-08-14

    Hybrid Nafion membranes were successfully fabricated by incorporating with protic imidazolium ionic liquids 1-(2-aminoethyl)-3-methylimidazolium chloride ([MimAE]Cl), 1-(2-hydroxylethyl)-3-methylimidazolium chloride ([MimHE]Cl), and 1-carboxylmethyl-3-methylimidazolium chloride ([MimCM]Cl) for high-temperature fuel cells. The composite membranes were characterized by impedance spectroscopy, small-angle X-ray scattering (SAXS), scanning electronic microscopy (SEM), and thermogravimetric analysis (TGA). The incorporated protic ionic liquids enhance the doping of phosphoric acid (PA) and result in a relatively high ionic conductivity. The Nafion/10 wt % [MimAE]Cl/PA composite membrane exhibits an ionic conductivity of 6.0 mS/cm at 130 °C without humidification. [MimAE]Cl can swell the Nafion matrix more homogeneously than [MimHE]Cl or [MimCM]Cl, which results in a better ionic conductivity. It is notable that the composite Nafion/IL/PA membranes have a better thermal stability than the pristine Nafion membranes.

  4. Ion beam irradiation as a tool to improve the ionic conductivity in solid polymer electrolyte systems

    SciTech Connect

    Manjunatha, H. Kumaraswamy, G. N.; Damle, R.

    2016-05-06

    Solid polymer electrolytes (SPEs) have potential applications in solid state electronic and energy devices. The optimum conductivity of SPEs required for such applications is about 10{sup −1} – 10{sup −3} Scm{sup −1}, which is hard to achieve in these systems. It is observed that ionic conductivity of SPEs continuously increase with increasing concentration of inorganic salt in the host polymer. However, there is a critical concentration of the salt beyond which the conductivity of SPEs decreases due to the formation of ion pairs. In the present study, solid polymer thin films based on poly (ethylene oxide) (PEO) complexed with NaBr salt with different concentrations have been prepared and the concentration at which ion pair formation occurs in PEO{sub x}NaBr is identified. The microstructure of the SPE with highest ionic conductivity is modified by irradiating it with low energy O{sup +1} ion (100 keV) of different fluencies. It is observed that the ionic conductivity of irradiated SPEs increases by one order in magnitude. The increase in ionic conductivity may be attributed to the enhanced segmental motion of the polymer chains due to radiation induced micro structural modification.

  5. Ion beam irradiation as a tool to improve the ionic conductivity in solid polymer electrolyte systems

    NASA Astrophysics Data System (ADS)

    Manjunatha, H.; Damle, R.; Kumaraswamy, G. N.

    2016-05-01

    Solid polymer electrolytes (SPEs) have potential applications in solid state electronic and energy devices. The optimum conductivity of SPEs required for such applications is about 10-1 - 10-3 Scm-1, which is hard to achieve in these systems. It is observed that ionic conductivity of SPEs continuously increase with increasing concentration of inorganic salt in the host polymer. However, there is a critical concentration of the salt beyond which the conductivity of SPEs decreases due to the formation of ion pairs. In the present study, solid polymer thin films based on poly (ethylene oxide) (PEO) complexed with NaBr salt with different concentrations have been prepared and the concentration at which ion pair formation occurs in PEOxNaBr is identified. The microstructure of the SPE with highest ionic conductivity is modified by irradiating it with low energy O+1 ion (100 keV) of different fluencies. It is observed that the ionic conductivity of irradiated SPEs increases by one order in magnitude. The increase in ionic conductivity may be attributed to the enhanced segmental motion of the polymer chains due to radiation induced micro structural modification.

  6. Control of ionic conductivity of ionic liquid/photoresponsive poly(amide acid) gels by photoirradiation.

    PubMed

    Tamada, Masahiro; Watanabe, Toshiyuki; Horie, Kazuyuki; Ohno, Hiroyuki

    2007-10-21

    1,3-Dibutylimidazolium bromide was soaked into a polymer network prepared by condensation of 4-4'-diaminoazobenzene, pyromellitic dianhydride and 1,3,5-tri(4-aminophenyl)benzene to form photoresponsive ion conductive gels.

  7. Ionic Conductivity And Structural Relaxation Studies on Lithium Niobophosphate Glass

    SciTech Connect

    Dabas, Prashant; Hariharan, K.

    2011-07-15

    Niobium pentoxide (Nb{sub 2}O{sub 5}) increases the chemical and thermal stability of otherwise hygroscopic alkali phosphate glasses and also enhances the conduction characteristics. Ion dynamics and structural relaxation have been investigated for mol%50Li{sub 2}0-45P{sub 2}0{sub 5}-5Nb{sub 2}O{sub 5}. The non-linearity parameter 'x' in the Tool-Narayanaswamy model is evaluated using the dependence of fictive and glass transition temperatures on the cooling and heating rates.

  8. Thermomorphic phase separation in ionic liquid-organic liquid systems--conductivity and spectroscopic characterization.

    PubMed

    Riisager, Anders; Fehrmann, Rasmus; Berg, Rolf W; van Hal, Roy; Wasserscheid, Peter

    2005-08-21

    Electrical conductivity, FT-Raman and NMR measurements are demonstrated as useful tools to probe and determine phase behavior of thermomorphic ionic liquid-organic liquid systems. To illustrate the methods, consecutive conductivity measurements of a thermomorphic methoxyethoxyethyl-imidazolium ionic liquid/1-hexanol system are performed in the temperature interval 25-80 degrees C using a specially constructed double-electrode cell. In addition, FT-Raman and 1H-NMR spectroscopic studies performed on the phase-separable system in the same temperature interval confirm the mutual solubility of the components in the system, the liquid-liquid equilibrium phase diagram of the binary mixture, and signify the importance of hydrogen bonding between the ionic liquid and the hydroxyl group of the alcohol.

  9. Electronically and ionically conductive porous material and method for manufacture of resin wafers therefrom

    SciTech Connect

    Lin, YuPo J; Henry, Michael P; Snyder, Seth W

    2011-07-12

    An electrically and ionically conductive porous material including a thermoplastic binder and one or more of anion exchange moieties or cation exchange moieties or mixtures thereof and/or one or more of a protein capture resin and an electrically conductive material. The thermoplastic binder immobilizes the moieties with respect to each other but does not substantially coat the moieties and forms the electrically conductive porous material. A wafer of the material and a method of making the material and wafer are disclosed.

  10. Electronically and ionically conductive porous material and method for manufacture of resin wafers therefrom

    SciTech Connect

    Lin, YuPo J; Henry, Michael P; Snyder, Seth W

    2008-11-18

    An electrically and ionically conductive porous material including a thermoplastic binder and one or more of anion exchange moieties or cation exchange moieties or mixtures thereof and/or one or more of a protein capture resin and an electrically conductive material. The thermoplastic binder immobilizes the moieties with respect to each other but does not substantially coat the moieties and forms the electrically conductive porous material. A wafer of the material and a method of making the material and wafer are disclosed.

  11. Glass capable of ionic conduction and method of preparation

    DOEpatents

    Susman, S.; Boehm, L.; Volin, K.J.; Delbecq, C.J.

    1982-05-06

    Sulfide glasses capable of conducting alkali metal ions are prepared from a nonmetal glass former such as GeS/sub 2/, B/sub 2/S/sub 2/ and SiS/sub 2/ in mixture with a glass modifier such as Na/sub 2/S or another alkali metal sulfide. A molten mixture of the constituents is rapidly quenched to below the glass transition temperature by contact with a metal mold. The rapid quench is sufficient to prevent crystallization and permit solidification as an amorphous solid mixture. An oxygen-free atmosphere is maintained over the mixture to prevent oxidation. A new glass system of (1 - X) Na/sub 2/O:XB/sub 2/S/sub 3/ is disclosed.

  12. Glass capable of ionic conduction and method of preparation

    DOEpatents

    Susman, S.; Delbecq, C.J.; Volin, K.J.; Boehm, L.

    1984-02-21

    Sulfide glasses capable of conducting alkali metal ions are prepared from a nonmetal glass former such as GeS[sub 2], B[sub 2]S[sub 3] and SiS[sub 2] in mixture with a glass modifier such as Na[sub 2]S or another alkali metal sulfide. A molten mixture of the constituents is rapidly quenched to below the glass transition temperature by contact with a metal mold. The rapid quench is sufficient to prevent crystallization and permit solidification as an amorphous solid mixture. An oxygen-free atmosphere is maintained over the mixture to prevent oxidation. A new glass system of (1-X) Na[sub 2]O:XB[sub 2]S[sub 3] is disclosed. 4 figs.

  13. Glass capable of ionic conduction and method of preparation

    DOEpatents

    Susman, Sherman; Boehm, Leah; Volin, Kenneth J.; Delbacq, Charles J.

    1985-01-01

    Sulfide glasses capable of conducting alkali metal ions are prepared from a nonmetal glass former such as GeS.sub.2, B.sub.2 S.sub.3 and SiS.sub.2 in mixture with a glass modifier such as Na.sub.2 S or another alkali metal sulfide. A molten mixture of the constituents is rapidly quenched to below the glass transition temperature by contact with a metal mold. The rapid quench is sufficient to prevent crystallization and permit solidification as an amorphous solid mixture. An oxygen-free atmosphere is maintained over the mixture to prevent oxidation. A new glass system of (1-X) Na.sub.2 O:XB.sub.2 S.sub.3 is disclosed.

  14. Glass capable of ionic conduction and method of preparation

    DOEpatents

    Susman, Sherman; Delbecq, Charles J.; Volin, Kenneth J.; Boehm, Leah

    1984-01-01

    Sulfide glasses capable of conducting alkali metal ions are prepared from a nonmetal glass former such as GeS.sub.2, B.sub.2 S.sub.3 and SiS.sub.2 in mixture with a glass modifier such as Na.sub.2 S or another alkali metal sulfide. A molten mixture of the constituents is rapidly quenched to below the glass transition temperature by contact with a metal mold. The rapid quench is sufficient to prevent crystallization and permit solidification as an amorphous solid mixture. An oxygen-free atmosphere is maintained over the mixture to prevent oxidation. A new glass system of (1-X) Na.sub.2 O:XB.sub.2 S.sub.3 is disclosed.

  15. Morphology and Proton Conductivity of Ionic Liquid Containing Sulfonated Block Copolymers

    NASA Astrophysics Data System (ADS)

    Kim, Sung Yeon; Park, Moon Jeong

    2011-03-01

    Proton exchange membrane fuel cells (PEMFC) offer the prospect of supplying clean electrical power for a wide variety of systems such as portable electronic devices and vehicles. Although, significant effort has been devoted to improvement of the transport properties of PEMs which is operated relatively lower temperature below 80circ; C, it suffers from a CO poisoning at Pt catalysis, complexity of water and heat management in the system. Herein, we report unique block copolymer electrolyte membrane systems containing ionic liquid. Due to the nonvolatile property of ionic liquid the systems exhibit effective proton transport above 100circ; C without humidification. In present study, sulfonated block copolymers, i.e., poly(styrenesulfonate-b-methylbuthylene) (SnMBm), are utilized for matrix materials by varying the ion contents and molecular weight. Imidazolium based ionic liquids are selectively incorporated into polystyrenesulfonate phases, which results in various morphological transitions as a function of the amount of the ionic liquid. The effect of counter ions on the observed morphologies is significant yielding concurrently different values of conductivity. Small angle x-ray scattering and transmission electron microscopy have been employed to determine various morphologies of the ionic liquid containing sulfonated block copolymer membranes and impedance spectroscopy is used for the conductivity measurements.

  16. High ionic conductivity P(VDF-TrFE)/PEO blended polymer electrolytes for solid electrochromic devices.

    PubMed

    Nguyen, Chien A; Xiong, Shanxin; Ma, Jan; Lu, Xuehong; Lee, Pooi See

    2011-08-07

    Solid polymer electrolytes with excellent ionic conductivity (above 10(-4) S cm(-1)), which result in high optical modulation for solid electrochromic (EC) devices are presented. The combination of a polar host matrix poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) and a solid plasticized of a low molecular weight poly(ethylene oxide) (PEO) (M(w)≤ 20,000) blended polymer electrolyte serves to enhance both the dissolution of lithium salt and the ionic transport. Calorimetric measurement shows a reduced crystallization due to a better intermixing of the polymers with small molecular weight PEO. Vibrational spectroscopy identifies the presence of free ions and ion pairs in the electrolytes with PEO of M(w)≤ 8000. The ionic dissolution is improved using PEO as a plasticizer when compared to liquid propylene carbonate, evidently shown in the transference number analysis. Ionic transport follows the Arrhenius equation with a low activation energy (0.16-0.2 eV), leading to high ionic conductivities. Solid electrochromic devices fabricated with the blended P(VDF-TrFE)/PEO electrolytes and polyaniline show good spectroelectrochemical performance in the visible (300-800 nm) and near-infrared (0.9-2.4 μm) regions with a modulation up to 60% and fast switching speed of below 20 seconds. The successful introduction of the solid polymer electrolytes with its best harnessed qualities helps to expedite the application of various electrochemical devices. This journal is © the Owner Societies 2011

  17. Molecular modeling of diffusion coefficient and ionic conductivity of CO2 in aqueous ionic solutions.

    PubMed

    Garcia-Ratés, Miquel; de Hemptinne, Jean-Charles; Bonet Avalos, Josep; Nieto-Draghi, Carlos

    2012-03-08

    Mass diffusion coefficients of CO(2)/brine mixtures under thermodynamic conditions of deep saline aquifers have been investigated by molecular simulation. The objective of this work is to provide estimates of the diffusion coefficient of CO(2) in salty water to compensate the lack of experimental data on this property. We analyzed the influence of temperature, CO(2) concentration,and salinity on the diffusion coefficient, the rotational diffusion, as well as the electrical conductivity. We observe an increase of the mass diffusion coefficient with the temperature, but no clear dependence is identified with the salinity or with the CO(2) mole fraction, if the system is overall dilute. In this case, we notice an important dispersion on the values of the diffusion coefficient which impairs any conclusive statement about the effect of the gas concentration on the mobility of CO(2) molecules. Rotational relaxation times for water and CO(2) increase by decreasing temperature or increasing the salt concentration. We propose a correlation for the self-diffusion coefficient of CO(2) in terms of the rotational relaxation time which can ultimately be used to estimate the mutual diffusion coefficient of CO(2) in brine. The electrical conductivity of the CO(2)-brine mixtures was also calculated under different thermodynamic conditions. Electrical conductivity tends to increase with the temperature and salt concentration. However, we do not observe any influence of this property with the CO(2) concentration at the studied regimes. Our results give a first evaluation of the variation of the CO(2)-brine mass diffusion coefficient, rotational relaxation times, and electrical conductivity under the thermodynamic conditions typically encountered in deep saline aquifers.

  18. Improved ionic conductivity of lithium-zinc-tellurite glass-ceramic electrolytes

    NASA Astrophysics Data System (ADS)

    Widanarto, W.; Ramdhan, A. M.; Ghoshal, S. K.; Effendi, M.; Cahyanto, W. T.; Warsito

    An enhancement in the secondary battery safety demands the optimum synthesis of glass-ceramics electrolytes with modified ionic conductivity. To achieve improved ionic conductivity and safer operation of the battery, we synthesized Li2O included zinc-tellurite glass-ceramics based electrolytes of chemical composition (85-x)TeO2·xLi2O·15ZnO, where x = 0, 5, 10, 15 mol%. Samples were prepared using the melt quenching method at 800 °C followed by thermal annealing at 320 °C for 3 h and characterized. The effects of varying temperature, alternating current (AC) frequency and Li2O concentration on the structure and ionic conductivity of such glass-ceramics were determined. The SEM images of the annealed glass-ceramic electrolytes displayed rough surface with a uniform distribution of nucleated crystal flakes with sizes less than 1 μm. X-ray diffraction analysis confirmed the well crystalline nature of achieved electrolytes. Incorporation of Li2O in the electrolytes was found to generate some new crystalline phases including hexagonal Li6(TeO6), monoclinic Zn2Te3O8 and monoclinic Li2Te2O5. The estimated crystallite size of the electrolyte was ranged from ≈40 to 80 nm. AC impedance measurement revealed that the variation in the temperatures, Li2O contents, and high AC frequencies have a significant influence on the ionic conductivity of the electrolytes. Furthermore, electrolyte doped with 15 mol% of Li2O exhibited the optimum performance with an ionic conductivity ≈2.4 × 10-7 S cm-1 at the frequency of 54 Hz and in the temperature range of 323-473 K. This enhancement in the conductivity was attributed to the sizable alteration in the ions vibration and ruptures of covalent bonds in the electrolytes network structures.

  19. Structure and ionic conductivity of block copolymer electrolytes over a wide salt concentration range

    NASA Astrophysics Data System (ADS)

    Chintapalli, Mahati; Le, Thao; Venkatesan, Naveen; Thelen, Jacob; Rojas, Adriana; Balsara, Nitash

    Block copolymer electrolytes are promising materials for safe, long-lasting lithium batteries because of their favorable mechanical and ion transport properties. The morphology, phase behavior, and ionic conductivity of a block copolymer electrolyte, SEO mixed with LiTFSI was studied over a wide, previously unexplored salt concentration range using small angle X-ray scattering, differential scanning calorimetry and ac impedance spectroscopy, respectively. SEO exhibits a maximum in ionic conductivity at twice the salt concentration that PEO, the homopolymer analog of the ion-containing block, does. This finding is contrary to prior studies that examined a more limited range of salt concentrations. In SEO, the phase behavior of the PEO block and LiTFSI closely resembles the phase behavior of homopolymer PEO and LiTFSI. The grain size of the block copolymer morphology was found to decrease with increasing salt concentration, and the ionic conductivity of SEO correlates with decreasing grain size. Structural effects impact the ionic conductivity-salt concentration relationship in block copolymer electrolytes. SEO: polystyrene-block-poly(ethylene oxide); also PS-PEO LiTFSI: lithium bis(trifluoromethanesulfonyl imide

  20. Conductivity Scaling Relationships in Nanostructured Membranes based on Protic Polymerized Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Sanoja, Gabriel; Lynd, Nathaniel; Segalman, Rachel

    2015-03-01

    Nanostructured membranes based on protic polymerized ionic liquids are of great interest for a variety of electrochemical applications. Understanding the relationship between composition, structure, and ionic conductivity for these materials is essential for designing novel membranes with improved properties. In this work, we explore the effect of volume fraction of ionic liquid on conductivity, σ using a model system composed of poly[isoprene-block-(ethylene oxide-stat-histamine glycidyl ether) diblock copolymers [PI- b - P(EO-stat-HGE)] and the resulting [PI- b - P(EO-stat-IL)] obtained after treatment with trifluoroacetic acid. These materials self-assemble into lamellar structures with volume fractions of ionic liquid ranging from 0.50 to 0.90 as demonstrated by SAXS. PI- b - P(EO-stat-IL) membranes exhibit conductivities up to 4 x 10-3 S/cm at room temperature. In addition, PI- b - P(EO-stat-IL) based membranes have lower water uptake (λ = 8-10) in comparison with most proton conducting membranes reported elsewhere. The low λ in these membranes might translate into a stronger effect of morphology on transport properties. Joint Center for Artificial Photosynthesis.

  1. Enhancing ionic conductivity of bulk single-crystal yttria-stabilized zirconia by tailoring dopant distribution

    SciTech Connect

    Lee, E.; Prinz, F. B.; Cai, W.

    2011-02-11

    We present an ab initio–based kinetic Monte Carlo model for ionic conductivity in single-crystal yttria-stabilized zirconia. Ionic interactions are taken into account by combining density functional theory calculations and the cluster expansion method and are found to be essential in reproducing the effective activation energy observed in experiments. The model predicts that the effective energy barrier can be reduced by 0.15–0.25 eV by arranging the dopant ions into a superlattice.

  2. Ionic conductivity and battery characteristic studies of a new PAN-based Na+ ion conducting gel polymer electrolyte system

    NASA Astrophysics Data System (ADS)

    Krishna Jyothi, N.; Vijaya Kumar, K.; Sunita Sundari, G.; Narayana Murthy, P.

    2016-03-01

    Sodium ion conducting gel polymer electrolytes based on polyacrylonitrile (PAN) with ethylene carbonate and dimethyl formamide as plasticizing solvents are prepared by the solution cast technique. These electrolyte films are free standing, transparent and dimensionally stable. Na+ ions are derived from NaI. The structural properties of pure and complex formations have been examined by X-ray diffraction, Fourier transform infrared spectroscopic studies and differential scanning calorimetric studies. The variation of the conductivity with salt concentration ranging from 10 to 40 wt% is studied. The sample containing 30 wt% of NaI exhibits the highest conductivity of 2.35 × 10-4 S cm-1 at room temperature (303 K) and 1 × 10-3 S cm-1 at 373 K. The conductivity-temperature dependence of polymer electrolyte films obeys Arrhenius behavior with activation energy in the range of 0.25-0.46 eV. The transport numbers both electronic ( t e) and ionic ( t i) are evaluated using Wagner's polarization technique. It is revealed that the conducting species are predominantly due to ions. The ionic transport number of highest conducting film is found to be 0.991. Solid-state battery with configuration Na/(PAN + NaI)/(I2 + C + electrolyte) is developed using the highest conducting gel polymer electrolyte system and the discharge characteristics of the cell are evaluated over the load of 100 KΩ.

  3. The Effect of Structural Modifications on Ionic Conductivity in Newly-Designed Polyester Electrolytes

    NASA Astrophysics Data System (ADS)

    Pesko, Danielle; Jung, Yuki; Coates, Geoff; Balsara, Nitash

    2015-03-01

    Gaining a fundamental understanding of the relationship between molecular structure and ionic conductivity of polymer electrolytes is an essential step toward designing next generation materials for battery applications. In this study, we use a systematic set of newly-designed polyesters with varying side-chain lengths and oxygen functional groups to elucidate the effects of structural modifications on the conductive properties of the corresponding electrolytes. Mixtures of polyesters and lithium bis(trifluromethanesulfonyl)imide (LiTFSI) were characterized using ac impedance spectroscopy to measure the ionic conductivity at various temperatures and salt concentrations. The relative conductivities of these electrolytes in the dilute limit are directly comparable to results of molecular dynamics simulations performed using the same polymers. The simulations correspond well with the experimental results, and provide molecular level insight about the solvation environment of the lithium ions and how the ions transport through these polyesters.

  4. Proton Conducting Polymer Membrane Using The Ionic Liquid 2-Hydroxyethylammonium Lactate For Ethanol Fuel Cells

    NASA Astrophysics Data System (ADS)

    Oliveira, L.; José, N. M.; Boaventura, J.; Iglesias, M.; Mattedi, S.

    2011-12-01

    In this work, there were developed a proton conducting polymer membrane using an ammonium based protic ionic liquid: 2-hydroxyethylamominum lactate for use in proton exchange fuel cells (PEMFC). This kind of ionic liquid has been proven to be biodegradable and they have potentially low toxicity besides low cost of preparation, simple synthesis and purification. The prepared membranes are hybrid organic-inorganic materials. The polymeric matrix is prepared with polydimethylsiloxane (PDMS) mixed with tetraethoxysilane (TEOS) in a ratio of 70/30% in weight. Then, the eletrolytical mixture containing sodium monododecylsulfate (SDS) and the ionic liquid was introduced in the lattice near the gel point, there were used different proportions of the eletrolyte from 5 to 30% in weight. The prepared membranes were characterized using infrared spectroscopy (FTIR), X-ray diffraction (DRX), termogravimetric analysis (TGA), scanning electronic microscopy (SEM) and conductivity and impedance measurements. The prepared materials are flexible, with good thermal and mechanical stability and with a great potential to be used as conducting membranes of fuel cells. The used mixture minimizes the lixiviation lost of the ionic liquid from the polymeric membrane and enhances the cell efficiency if compared with traditional synthetic membranes.

  5. Covalent Incorporation of Ionic Liquid into Ion-Conductive Networks via Thiol-Ene Photopolymerization.

    PubMed

    Tibbits, Andrew C; Yan, Yushan S; Kloxin, Christopher J

    2017-07-01

    Ene-functionalized ionic liquids with a range of different cationic groups and counteranions react stoichiometrically within a tetrathiol-divinyl ether formulation within 20 minutes to form thiol-ene polymers with measurable ionic conductivities via a photoinitiated polymerization and crosslinking reaction. Dynamic mechanical analysis indicates that these networks are more spatially heterogeneous and possess higher glass transition temperatures (Tg ) compared with thiol-ene formulations without charge. While tuning the molar content of ionic liquid monomer is one method for adjusting the crosslink and charge densities of the thiol-ene polymeric ionic liquid networks, the presence of cation-anion interactions also plays a critical role in dictating the thermomechanical and conductive properties. Particularly, while cationic structure effects are not significant on the polymer properties, the use of a weakly coordinating hydrophobic anion (bistriflimide) instead of bromide-based networks results in an apparent decrease in hydrated ion conductivity (7.4 to 1.5 mS cm(-1) ) and Tg (-9.6 to -17.8 °C). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Li+ ionic conductivities and diffusion mechanisms in Li-based imides and lithium amide.

    PubMed

    Li, Wen; Wu, Guotao; Xiong, Zhitao; Feng, Yuan Ping; Chen, Ping

    2012-02-07

    In this study, both experimental ionic conductivity measurements and the first-principles simulations are employed to investigate the Li(+) ionic diffusion properties in lithium-based imides (Li(2)NH, Li(2)Mg(NH)(2) and Li(2)Ca(NH)(2)) and lithium amide (LiNH(2)). The experimental results show that Li(+) ions present superionic conductivity in Li(2)NH (2.54 × 10(-4) S cm(-1)) and moderate ionic conductivity in Li(2)Ca(NH)(2) (6.40 × 10(-6) S cm(-1)) at room temperature; while conduction of Li(+) ions is hardly detectable in Li(2)Mg(NH)(2) and LiNH(2) at room temperature. The simulation results indicate that Li(+) ion diffusion in Li(2)NH may be mediated by Frenkel pair defects or charged vacancies, and the diffusion pathway is more likely via a series of intermediate jumps between octahedral and tetrahedral sites along the [001] direction. The calculated activation energy and pre-exponential factor for Li(+) ion conduction in Li(2)NH are well comparable with the experimentally determined values, showing the consistency of experimental and theoretical investigations. The calculation of the defect formation energy in LiNH(2) reveals that Li defects are difficult to create to mediate the Li(+) ion diffusion, resulting in the poor Li(+) ion conduction in LiNH(2) at room temperature.

  7. Is Geometric Frustration-Induced Disorder a Recipe for High Ionic Conductivity?

    PubMed

    Düvel, Andre; Heitjans, Paul; Fedorov, Pavel; Scholz, Gudrun; Cibin, Giannantonio; Chadwick, Alan V; Pickup, David M; Ramos, Silvia; Sayle, Lewis W L; Sayle, Emma K L; Sayle, Thi X T; Sayle, Dean C

    2017-04-26

    Ionic conductivity is ubiquitous to many industrially important applications such as fuel cells, batteries, sensors, and catalysis. Tunable conductivity in these systems is therefore key to their commercial viability. Here, we show that geometric frustration can be exploited as a vehicle for conductivity tuning. In particular, we imposed geometric frustration upon a prototypical system, CaF2, by ball milling it with BaF2, to create nanostructured Ba1-xCaxF2 solid solutions and increased its ionic conductivity by over 5 orders of magnitude. By mirroring each experiment with MD simulation, including "simulating synthesis", we reveal that geometric frustration confers, on a system at ambient temperature, structural and dynamical attributes that are typically associated with heating a material above its superionic transition temperature. These include structural disorder, excess volume, pseudovacancy arrays, and collective transport mechanisms; we show that the excess volume correlates with ionic conductivity for the Ba1-xCaxF2 system. We also present evidence that geometric frustration-induced conductivity is a general phenomenon, which may help explain the high ionic conductivity in doped fluorite-structured oxides such as ceria and zirconia, with application for solid oxide fuel cells. A review on geometric frustration [ Nature 2015 , 521 , 303 ] remarks that classical crystallography is inadequate to describe systems with correlated disorder, but that correlated disorder has clear crystallographic signatures. Here, we identify two possible crystallographic signatures of geometric frustration: excess volume and correlated "snake-like" ionic transport; the latter infers correlated disorder. In particular, as one ion in the chain moves, all the other (correlated) ions in the chain move simultaneously. Critically, our simulations reveal snake-like chains, over 40 Å in length, which indicates long-range correlation in our disordered systems. Similarly, collective

  8. Effect of pressure on decoupling of ionic conductivity from structural relaxation in hydrated protic ionic liquid, lidocaine HCl

    NASA Astrophysics Data System (ADS)

    Swiety-Pospiech, A.; Wojnarowska, Z.; Hensel-Bielowka, S.; Pionteck, J.; Paluch, M.

    2013-05-01

    Broadband dielectric spectroscopy and pressure-temperature-volume methods are employed to investigate the effect of hydrostatic pressure on the conductivity relaxation time (τσ), both in the supercooled and glassy states of protic ionic liquid lidocaine hydrochloride monohydrate. Due to the decoupling between the ion conductivity and structural dynamics, the characteristic change in behavior of τσ(T) dependence, i.e., from Vogel-Fulcher-Tammann-like to Arrhenius-like behavior, is observed. This crossover is a manifestation of the liquid-glass transition of lidocaine HCl. The similar pattern of behavior was also found for pressure dependent isothermal measurements. However, in this case the transition from one simple volume activated law to another was noticed. Additionally, by analyzing the changes of conductivity relaxation times during isothermal densification of the sample, it was found that compression enhances the decoupling of electrical conductivity from the structural relaxation. Herein, we propose a new parameter, dlogRτ/dP, to quantify the pressure sensitivity of the decoupling phenomenon. Finally, the temperature and volume dependence of τσ is discussed in terms of thermodynamic scaling concept.

  9. Water uptake, ionic conductivity and swelling properties of anion-exchange membrane

    NASA Astrophysics Data System (ADS)

    Duan, Qiongjuan; Ge, Shanhai; Wang, Chao-Yang

    2013-12-01

    Water uptake, ionic conductivity and dimensional change of the anion-exchange membrane made by Tokuyama Corporation (A201 membrane) are investigated at different temperatures and water activities. Specifically, the amount of water taken up by membranes exposed to water vapor and membranes soaked in liquid water is determined. The water uptake of the A201 membrane increases with water content as well as temperature. In addition, water sorption data shows Schroeder's paradox for the AEMs investigated. The swelling properties of the A201 membrane exhibit improved dimensional stability compared with Nafion membrane. Water sorption of the A201 membrane occurs with a substantial negative excess volume of mixing. The threshold value of hydrophilic fraction in the A201 membrane for ionic conductivity is around 0.34, above which, the conductivity begins to rise quickly. This indicates that a change in the connectivity of the hydrophilic domains occurs when hydrophilic fraction approaches 0.34.

  10. Electrochemical deposition of conducting polymer coatings on magnesium surfaces in ionic liquid

    PubMed Central

    Luo, Xiliang; Cui, Xinyan Tracy

    2012-01-01

    A conducting polymer based smart coating for magnesium (Mg) implants that can both improve the corrosion resistance of Mg and release drug in a controllable way is reported. As the ionic liquid is a highly conductive and stable solvent with a very wide electrochemical window, the conducting polymer coatings can be directly electrodeposited on the active metal Mg in ionic liquid at mild conditions, and Mg is considerably stable during the electrodeposition. The electrodeposited Poly(3,4-ethylenedioxythiophene) (PEDOT) coatings on Mg are uniform and can significantly improve the corrosion resistance of Mg. In addition, the PEDOT coatings can load the anti-inflammatory drug dexamethasone during the electrodeposition which can be subsequently released upon electric stimulation. PMID:20832505

  11. Lithium-Ion-Conducting Electrolytes: From an Ionic Liquid to the Polymer Membrane

    PubMed Central

    Fernicola, A.; Weise, F. C.; Greenbaum, S. G.; Kagimoto, J.; Scrosati, B.; Soleto, A.

    2009-01-01

    This work concerns the design, the synthesis, and the characterization of the N-butyl-N-ethylpiperidinium N,N-bis(trifluoromethane)sulfonimide (PP24TFSI) ionic liquid (IL). To impart Li-ion transport, a suitable amount of lithium N,N-bis-(trifluoromethane)sulfonimide (LiTFSI) is added to the IL. The Li–IL mixture displays ionic conductivity values on the order of 10−4 S cm−1 and an electrochemical stability window in the range of 1.8–4.5 V vs Li+/Li. The voltammetric analysis demonstrates that the cathodic decomposition gives rise to a passivating layer on the surface of the working electrode, which kinetically extends the stability of the Li/IL interface as confirmed by electrochemical impedance spectroscopy measurements. The LiTFSI–PP24TFSI mixture is incorporated in a poly(vinylidene fluoride-co-hexafluoropropylene) matrix to form various electrolyte membranes with different LiTFSI–PP24TFSI contents. The ionic conductivity of all the membranes resembles that of the LiTFSI–IL mixture, suggesting an ionic transport mechanism similar to that of the liquid component. NMR measurements demonstrate a reduction in the mobility of all ions following the addition of LiTFSI to the PP24TFSI IL and when incorporating the mixture into the membrane. Finally, an unexpected but potentially significant enhancement in Li transference number is observed in passing from the liquid to the membrane electrolyte system. PMID:20354582

  12. Lithium-Ion-Conducting Electrolytes: From an Ionic Liquid to the Polymer Membrane.

    PubMed

    Fernicola, A; Weise, F C; Greenbaum, S G; Kagimoto, J; Scrosati, B; Soleto, A

    2009-05-05

    This work concerns the design, the synthesis, and the characterization of the N-butyl-N-ethylpiperidinium N,N-bis(trifluoromethane)sulfonimide (PP(24)TFSI) ionic liquid (IL). To impart Li-ion transport, a suitable amount of lithium N,N-bis-(trifluoromethane)sulfonimide (LiTFSI) is added to the IL. The Li-IL mixture displays ionic conductivity values on the order of 10(-4) S cm(-1) and an electrochemical stability window in the range of 1.8-4.5 V vs Li(+)/Li. The voltammetric analysis demonstrates that the cathodic decomposition gives rise to a passivating layer on the surface of the working electrode, which kinetically extends the stability of the Li/IL interface as confirmed by electrochemical impedance spectroscopy measurements. The LiTFSI-PP(24)TFSI mixture is incorporated in a poly(vinylidene fluoride-co-hexafluoropropylene) matrix to form various electrolyte membranes with different LiTFSI-PP(24)TFSI contents. The ionic conductivity of all the membranes resembles that of the LiTFSI-IL mixture, suggesting an ionic transport mechanism similar to that of the liquid component. NMR measurements demonstrate a reduction in the mobility of all ions following the addition of LiTFSI to the PP(24)TFSI IL and when incorporating the mixture into the membrane. Finally, an unexpected but potentially significant enhancement in Li transference number is observed in passing from the liquid to the membrane electrolyte system.

  13. Use of Ionic Liquids in Rod-Coil Block Copolyimides for Improved Lithium Ion Conduction

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B.; Tigelaar, Dean M.; Chapin, Kara; Bennett, William R.

    2007-01-01

    Solvent-free, solid polymer electrolytes (SPE) have the potential to improve safety, increase design flexibility and enhance performance of rechargeable lithium batteries. Solution based electrolytes are flammable and typically incompatible with lithium metal anodes, limiting energy density. We have previously demonstrated use of polyimide rod coil block copolymers doped with lithium salts as electrolytes for lithium polymer batteries. The polyimide rod blocks provide dimensional stability while the polyethylene oxide (PEO) coil portions conduct ions. Phase separation of the rods and coils in these highly branched polymers provide channels with an order of magnitude improvement in lithium conduction over polyethylene oxide itself at room temperature. In addition, the polymers have been demonstrated in coin cells to be compatible with lithium metal. For practical use at room temperature and below, however, at least an order of magnitude improvement in ion conduction is still required. The addition of nonvolatile, room temperature ionic liquids has been shown to improve the ionic conductivity of high molecular weight PEO. Herein we describe use of these molten salts to improve ionic conductivity in the rod-coil block copolymers.

  14. Advanced two-photon photolithography for patterning of transparent, electrically conductive ionic liquid-polymer nanostructures

    NASA Astrophysics Data System (ADS)

    Bakhtina, Natalia A.; MacKinnon, Neil; Korvink, Jan G.

    2016-04-01

    A key challenge in micro- and nanotechnology is the direct patterning of functional structures. For example, it is highly desirable to possess the ability to create three-dimensional (3D), conductive, and optically transparent structures. Efforts in this direction have, to date, yielded less than optimal results since the polymer composites had low optical transparency over the visible range, were only slightly conductive, or incompatible with high resolution structuring. We have previously presented the novel cross-linkable, conductive, highly transparent composite material based on a photoresist (IP-L 780, OrmoComp, or SU-8) and the ionic liquid 1-butyl-3-methylimidazolium dicyanamide. Material patterning by conventional and two-photon photolithography has been demonstrated as proof-of-concept. Aiming to increase the resolution and to extend the spectrum of exciting applications we continued our research into identifying new ionic liquid - polymer composites. In this paper, we report the precise 3D single-step structuring of optically transparent and electrically conductive ionic liquid - polymer nanostructures with the highest spatial resolution (down to 150 nm) achieved to date. This was achieved via the development of novel cross-linkable composite based on the photoresist IP-G 780 and the ionic liquid 1-butyl-3-methylimidazolium dicyanamide. The successful combination of the developed material with the advanced direct laser writing technique enabled the time- and cost-saving direct manufacturing of transparent, electrically conductive components. We believe that the excellent characteristics of the structured material will open a wider range of exciting applications.

  15. A mixed ionic and electronic conducting dual-phase membrane with high oxygen permeability.

    PubMed

    Fang, Wei; Liang, Fangyi; Cao, Zhengwen; Steinbach, Frank; Feldhoff, Armin

    2015-04-13

    To combine good chemical stability and high oxygen permeability, a mixed ionic-electronic conducting (MIEC) 75 wt% Ce(0.85)Gd(0.1)Cu(0.05)O(2-δ)-25 wt% La(0.6)Ca(0.4)FeO(3-δ)(CGCO-LCF) dual-phase membrane based on a MIEC-MIEC composite has been developed. Copper doping into Ce(0.9)Gd(0.1)O(2-δ) (CGO) oxide enhances both ionic and electronic conductivity, which then leads to a change from ionic conduction to mixed conduction at elevated temperatures. For the first time we demonstrate that an intergranular film with 2-10 nm thickness containing Ce, Ca, Gd, La, and Fe has been formed between the CGCO grains in the CGCO-LCF one-pot dual-phase membrane. A high oxygen permeation flux of 0.70 mL min(-1) cm(-2) is obtained by the CGCO-LCF one-pot dual-phase membrane with 0.5 mm thickness at 950 °C using pure CO2 as the sweep gas, and the membrane shows excellent stability in the presence of CO2 even at lower temperatures (800 °C) during long-term operation.

  16. Structural control of mixed ionic and electronic transport in conducting polymers

    SciTech Connect

    Rivnay, Jonathan; Inal, Sahika; Collins, Brian A.; Sessolo, Michele; Stavrinidou, Eleni; Strakosas, Xenofon; Tassone, Christopher; Delongchamp, Dean M.; Malliaras, George G.

    2016-04-19

    Poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate), PEDOT:PSS, has been utilized for over two decades as a stable, solution-processable hole conductor. While its hole transport properties have been the subject of intense investigation, recent work has turned to PEDOT:PSS as a mixed ionic/electronic conductor in applications including bioelectronics, energy storage and management, and soft robotics. Conducting polymers can efficiently transport both holes and ions when sufficiently hydrated, however, little is known about the role of morphology on mixed conduction. Here, we show that bulk ionic and electronic mobilities are simultaneously affected by processing-induced changes in nano- and meso-scale structure in PEDOT:PSS films. We quantify domain composition, and find that domain purification on addition of dispersion co-solvents limits ion mobility, even while electronic conductivity improves. We show that an optimal morphology allows for the balanced ionic and electronic transport that is critical for prototypical mixed conductor devices. As a result, these findings may pave the way for the rational design of polymeric materials and processing routes to enhance devices reliant on mixed conduction.

  17. First-principles investigations of ionic conduction in Li and Na borohydrides

    NASA Astrophysics Data System (ADS)

    Varley, Joel; Heo, Tae-Wook; Ray, Keith; Bonev, Stanimir; Wood, Brandon

    Recent experimental studies have identified a family of alkali borohydride materials that exhibit superionic transition temperatures approaching room temperature and ionic conductivities exceeding 0.1 S/cm-1, making them highly promising solid electrolytes for next-generation batteries. Despite the rapid advances in improving the superionic conductivity in these materials, an understanding of the exact mechanisms driving the transport remains unknown. Here we use ab initio molecular dynamics calculations to address this issue by characterizing the diffusivity of the Li and Na species in a representative set of closoborane ionic conductors. We investigate both the Na and Li-containing borohydrides with icosahedral (B12H12) and double-capped square antiprism (B10H10) anion species and discuss the trends in ionic conductivity as a function of stoichiometry and the incorporation of various dopants. Our results support the borohydrides as a subset of a larger family of very promising solid electrolytes and identify strategies to improving the conductivity in these materials. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  18. Structural control of mixed ionic and electronic transport in conducting polymers

    NASA Astrophysics Data System (ADS)

    Rivnay, Jonathan; Inal, Sahika; Collins, Brian A.; Sessolo, Michele; Stavrinidou, Eleni; Strakosas, Xenofon; Tassone, Christopher; Delongchamp, Dean M.; Malliaras, George G.

    2016-04-01

    Poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate), PEDOT:PSS, has been utilized for over two decades as a stable, solution-processable hole conductor. While its hole transport properties have been the subject of intense investigation, recent work has turned to PEDOT:PSS as a mixed ionic/electronic conductor in applications including bioelectronics, energy storage and management, and soft robotics. Conducting polymers can efficiently transport both holes and ions when sufficiently hydrated, however, little is known about the role of morphology on mixed conduction. Here, we show that bulk ionic and electronic mobilities are simultaneously affected by processing-induced changes in nano- and meso-scale structure in PEDOT:PSS films. We quantify domain composition, and find that domain purification on addition of dispersion co-solvents limits ion mobility, even while electronic conductivity improves. We show that an optimal morphology allows for the balanced ionic and electronic transport that is critical for prototypical mixed conductor devices. These findings may pave the way for the rational design of polymeric materials and processing routes to enhance devices reliant on mixed conduction.

  19. Structural control of mixed ionic and electronic transport in conducting polymers.

    PubMed

    Rivnay, Jonathan; Inal, Sahika; Collins, Brian A; Sessolo, Michele; Stavrinidou, Eleni; Strakosas, Xenofon; Tassone, Christopher; Delongchamp, Dean M; Malliaras, George G

    2016-04-19

    Poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate), PSS, has been utilized for over two decades as a stable, solution-processable hole conductor. While its hole transport properties have been the subject of intense investigation, recent work has turned to PSS as a mixed ionic/electronic conductor in applications including bioelectronics, energy storage and management, and soft robotics. Conducting polymers can efficiently transport both holes and ions when sufficiently hydrated, however, little is known about the role of morphology on mixed conduction. Here, we show that bulk ionic and electronic mobilities are simultaneously affected by processing-induced changes in nano- and meso-scale structure in PSS films. We quantify domain composition, and find that domain purification on addition of dispersion co-solvents limits ion mobility, even while electronic conductivity improves. We show that an optimal morphology allows for the balanced ionic and electronic transport that is critical for prototypical mixed conductor devices. These findings may pave the way for the rational design of polymeric materials and processing routes to enhance devices reliant on mixed conduction.

  20. Structural control of mixed ionic and electronic transport in conducting polymers

    PubMed Central

    Rivnay, Jonathan; Inal, Sahika; Collins, Brian A.; Sessolo, Michele; Stavrinidou, Eleni; Strakosas, Xenofon; Tassone, Christopher; Delongchamp, Dean M.; Malliaras, George G.

    2016-01-01

    Poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate), PEDOT:PSS, has been utilized for over two decades as a stable, solution-processable hole conductor. While its hole transport properties have been the subject of intense investigation, recent work has turned to PEDOT:PSS as a mixed ionic/electronic conductor in applications including bioelectronics, energy storage and management, and soft robotics. Conducting polymers can efficiently transport both holes and ions when sufficiently hydrated, however, little is known about the role of morphology on mixed conduction. Here, we show that bulk ionic and electronic mobilities are simultaneously affected by processing-induced changes in nano- and meso-scale structure in PEDOT:PSS films. We quantify domain composition, and find that domain purification on addition of dispersion co-solvents limits ion mobility, even while electronic conductivity improves. We show that an optimal morphology allows for the balanced ionic and electronic transport that is critical for prototypical mixed conductor devices. These findings may pave the way for the rational design of polymeric materials and processing routes to enhance devices reliant on mixed conduction. PMID:27090156

  1. Structural control of mixed ionic and electronic transport in conducting polymers

    DOE PAGES

    Rivnay, Jonathan; Inal, Sahika; Collins, Brian A.; ...

    2016-04-19

    Poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate), PEDOT:PSS, has been utilized for over two decades as a stable, solution-processable hole conductor. While its hole transport properties have been the subject of intense investigation, recent work has turned to PEDOT:PSS as a mixed ionic/electronic conductor in applications including bioelectronics, energy storage and management, and soft robotics. Conducting polymers can efficiently transport both holes and ions when sufficiently hydrated, however, little is known about the role of morphology on mixed conduction. Here, we show that bulk ionic and electronic mobilities are simultaneously affected by processing-induced changes in nano- and meso-scale structure in PEDOT:PSS films. Wemore » quantify domain composition, and find that domain purification on addition of dispersion co-solvents limits ion mobility, even while electronic conductivity improves. We show that an optimal morphology allows for the balanced ionic and electronic transport that is critical for prototypical mixed conductor devices. As a result, these findings may pave the way for the rational design of polymeric materials and processing routes to enhance devices reliant on mixed conduction.« less

  2. Block copolymers exhibiting simultaneous electronic and ionic conduction for use in lithium battery electrodes

    NASA Astrophysics Data System (ADS)

    Javier, Anna; Patel, Shrayesh; Hallinan, Daniel; Balsara, Nitash

    2011-03-01

    A block copolymer system that can demonstrate both electronic and ionic conductivity is analyzed for its performance in rechargeable lithium batteries. Here, the electrically active polymer is poly(3-hexylthiophene), while poly(ethylene oxide) is used as the lithium ion conductor. This block copolymer is then mixed with LiFe PO4 and used as the cathode material. Other components in the battery include a lithium metal anode and poly(styrene)-block-poly(ethylene oxide) (SEO) as the solid electrolyte. Lithium bis(trifluoromethane)sulfonimide (LiTFSI) is utilized to facilitate ionic conductivity in both the electrolyte and the cathode. The synthesis of the block copolymer and its device performance in rechargeable lithium metal batteries will be presented.

  3. Connection between NMR and electrical conductivity in glassy chalcogenide fast ionic conductors

    SciTech Connect

    Kim, Kyung -Han

    1995-07-07

    The work documented in this thesis follows the traditional order. In this chapter a general discussion of ionic conduction and of glassy materials are followed by a brief outline of the experimental techniques for the investigation of fast ionic conduction in glassy materials, including NMR and impedance spectroscopy techniques. A summary of the previous and present studies is presented in the last section of this introductory chapter. The details of the background theory and models are found in the Chapter II, followed by the description of the experimental details in Chapter III. Chapter IV of the thesis describes the experimental results and the analysis of the experimental observations followed by the conclusions in chapter V.

  4. Correlating crystallization and ionic conductivity of PEO/graphene oxide nanocomposite

    NASA Astrophysics Data System (ADS)

    Cheng, Shan; Smith, Derrick; Hsuan, Grace; Li, Christopher

    2012-02-01

    Polyethylene oxide (PEO) is one of the best candidates for solid state electrolyte due to its chemical stability and strong ability to form complex with lithium salts. Crystallization behavior of PEO directly affects the lithium ion transport, and in turn the ionic conductivity of the electrolyte. By adding two dimensional graphene oxide nanosheets into PEO matrix, mechanical property of the latter is significantly strengthened, while the crystallization behavior of PEO is also altered by the graphene oxide sheets. The crystallization of PEO/graphene oxide nanocomposites was studied by differential scanning calorimetry (DSC) and the orientations of graphene oxide and PEO crystal were studied by small angle X-ray scattering and wide angle X-ray diffraction. PEO/graphene oxide nanocomposite doped with lithium salt was further fabricated and characterized by electrochemical impedance spectroscopy. Anisotropic ionic conductivity was observed for the nanocomposite electrolyte due to the orientation of graphene oxide and directional growth of PEO crystals.

  5. Li-rich anti-perovskite Li3OCl films with enhanced ionic conductivity

    SciTech Connect

    Lu, XJ; Wu, G; Howard, JW; Chen, AP; Zhao, YS; Daemen, LL; Jia, QX

    2014-08-13

    Anti-perovskite solid electrolyte films were prepared by pulsed laser deposition, and their room-temperature ionic conductivity can be improved by more than an order of magnitude in comparison with its bulk counterpart. The cyclability of Li3OCl films in contact with lithium was evaluated using a Li/Li3OCl/Li symmetric cell, showing self-stabilization during cycling test.

  6. Simultaneous electronic and ionic conduction in a block copolymer: application in lithium battery electrodes.

    PubMed

    Javier, Anna E; Patel, Shrayesh N; Hallinan, Daniel T; Srinivasan, Venkat; Balsara, Nitash P

    2011-10-10

    Charging ahead: separate values for the simultaneous electronic and ionic conductivity of a conjugated polymer containing poly(3-hexylthiophene) and poly(ethylene oxide) (P3HT-PEO) were determined by using ac impedance and dc techniques. P3HT-PEO was used as binder, and transporter of electronic charge and Li(+) ions in a LiFePO(4) cathode, which was incorporated into solid-state lithium batteries.

  7. Ionic conductivity of binary fluorides of potassium and rare earth elements

    SciTech Connect

    Sorokin, N. I.

    2016-01-15

    The ionic conductivity s of KYF{sub 4} and K{sub 2}RF{sub 5} single crystals (R = Gd, Ho, Er) and KNdF{sub 4} and K{sub 2}RF{sub 5} ceramic samples (R = Dy, Er) has been studied in the temperature range of 340–500°C. A comparative analysis of the σ values for these objects has been performed. Binary fluorides of potassium and rare earth elements were synthesized by the hydrothermal method (temperature 480°C, pressure 100–150 MPa) in the R{sub 2}O{sub 3}–KF–H{sub 2}O systems. The σ values of tetraf luorides are 3 × 10{sup –5} S/cm (KYF{sub 4} single crystal) and 3 × 10{sup –6} S/cm (KNdF{sub 4} ceramics) at 435°C. A K{sub 2}ErF{sub 5} single crystal with σ = 1.2 × 10{sup –4} S/cm at 435°C has the maximum value of ionic conductivity among pentafluorides. The anisotropy of ionic transport was found in K{sub 2}HoF{sub 5} single crystals, σ{sub ∥c}/σ{sub ⊥c} = 2.5, where σ{sub ∥c} and σ{sub ⊥c} are, respectively, the conductivities along the crystallographic c axis and in the perpendicular direction.

  8. Copper and silver selenide crystal growth rate measurements as a method for determination of ionic conductivity

    NASA Astrophysics Data System (ADS)

    Vučić, Zlatko; Lovrić, Davorin; Gladić, Jadranko; Etlinger, Božidar

    2004-03-01

    The motivation behind this work is the discrepancy between the measured and calculated growth rates of copper selenide spherical single crystals between 740 and 800 K. The growth of cylindrical polycrystalline samples of copper selenide at high temperatures was monitored in experiments that enabled full control of the geometry of growth. Together with the calculations based on Yokota's transport equation, these measurements eliminated ionic conductivity data as a possible reason behind too high values of the calculated growth rates. The equivalent growth experiments on polycrystalline silver selenide samples were performed as a test of the method, yielding excellent agreement with the results obtained by extrapolation of existing data. On the basis of these measurements and associated analysis, this method is proposed as a method for determination of ionic conductivity of mixed superionic conductors on temperatures up to the temperatures of melting, i.e. in the range in which other methods of ionic conductivity measurements either do not work or are not accurate enough.

  9. Structural manipulation approaches towards enhanced sodium ionic conductivity in Na-rich antiperovskites

    SciTech Connect

    Wang, Yonggang; Wang, Qingfei; Liu, Zhenpu; Zhou, Zhengyang; Li, Shuai; Zhu, Jinlong; Zou, Ruqiang; Wang, Yingxia; Lin, Jianhua; Zhao, Yusheng

    2015-06-10

    High-performance solid electrolytes are critical for realizing all-solid-state batteries with enhance safety and cycling efficiency. However, currently available candidates (sulfides and the NASICON-typ ceramics) still suffer from drawbacks such as inflammability, high-cost and unfavorable machinability Here we present the structural manipulation approaches to improve the sodium ionic conductivity in series of affordable Na-rich antiperovskites. Experimentally, the whole solid solutions of Na3OX (X ¼ Cl Br, I) are synthesized via a facile and timesaving route from the cheapest raw materials (Na, NaOH an NaX). The materials are nonflammable, suitable for thermoplastic processing due to low melting temperature (<300° C) without decomposing. Notably, owing to the flexibility of perovskite-type structure it's feasible to control the local structure features by means of size-mismatch substitution an unequivalent-doping for a favorable sodium ionic diffusion pathway. Enhancement of sodium ioni conductivity by 2 magnitudes is demonstrated by these chemical tuning methods. The optimized sodiu ionic conductivity in Na2.9Sr0.05OBr0.6I0.4 bulk samples reaches 1.9 10- 3 S/cm at 200° C and even highe at elevated temperature. Here, we believe further chemical tuning efforts on Na-rich antiperovskites wil promote their performance greatly for practical all-solid state battery applications.

  10. Nonaqueous CE using contactless conductivity detection and ionic liquids as BGEs in ACN.

    PubMed

    Borissova, Maria; Gorbatsova, Jelena; Ebber, Arkadi; Kaljurand, Mihkel; Koel, Mihkel; Vaher, Merike

    2007-10-01

    N,N'-Alkylmethylimidazolium cations have been separated in NACE when one of the N,N'-dialkylimidazolium salts (ionic liquids (ILs)) was used as an electrolyte additive to the organic solvent separation medium. The separated species were 1-methyl-, 1-ethyl-, 1-butyl-, 1-octyl-, 1-decyl-3-methylimidazolium and N-butyl-3-methylpyridinium cations and BGE composed of 1-ethyl-3-methylimidazolium ethylsulfate or 1-butyl-3-methylimidazolium trifluoroacetate [BMIm][FAcO] (A6; B2) diluted in ACN. It was demonstrated that contactless conductivity detection (CCD) may be applied to monitoring the separation process in nonaqueous separation media, allowing to use the UV light-absorbing imidazolium-based electrolyte additives. There could be marked three concentration regions of added ILs; at first ionic strength of BGE below 1-2 mM, and then the actual electrophoretic mobility of analytes rises from 0. At concentrations above 1-2 mM, the added IL facilitated separation. In concentration region of 1-20 mM, the actual electrophoretic mobility of analyzed imidazolium cations was increasing with decrease in separation medium ionic strength. At higher concentrations of BGE (above 30 mM), the conductivity of the separation media became too high for this detector. Some organic dyes were also successfully separated and detected by contactless conductivity detector in a 20 mM A6 separation electrolyte in ACN.

  11. Ionic conductivity of binary fluorides of potassium and rare earth elements

    NASA Astrophysics Data System (ADS)

    Sorokin, N. I.

    2016-01-01

    The ionic conductivity s of KYF4 and K2 RF5 single crystals ( R = Gd, Ho, Er) and KNdF4 and K2 RF5 ceramic samples ( R = Dy, Er) has been studied in the temperature range of 340-500°C. A comparative analysis of the σ values for these objects has been performed. Binary fluorides of potassium and rare earth elements were synthesized by the hydrothermal method (temperature 480°C, pressure 100-150 MPa) in the R 2O3-KF-H2O systems. The σ values of tetraf luorides are 3 × 10-5 S/cm (KYF4 single crystal) and 3 × 10-6 S/cm (KNdF4 ceramics) at 435°C. A K2ErF5 single crystal with σ = 1.2 × 10-4 S/cm at 435°C has the maximum value of ionic conductivity among pentafluorides. The anisotropy of ionic transport was found in K2HoF5 single crystals, σ∥ c /σ⊥ c = 2.5, where σ∥ c and σ⊥ c are, respectively, the conductivities along the crystallographic c axis and in the perpendicular direction.

  12. Electroosmotic flow and ionic conductance in a pH-regulated rectangular nanochannel

    NASA Astrophysics Data System (ADS)

    Sadeghi, Morteza; Saidi, Mohammad Hassan; Sadeghi, Arman

    2017-06-01

    Infinite series solutions are obtained for electrical potential, electroosmotic velocity, ionic conductance, and surface physicochemical properties of long pH-regulated rectangular nanochannels of low surface potential utilizing the double finite Fourier transform method. Closed form expressions are also obtained for channels of large height to width ratio for which the depthwise variations vanish. Neglecting the Stern layer impact, the effects of EDL (Electric Double Layer) overlap, multiple ionic species, and association/dissociation reactions on the surface are all taken into account. Moreover, finite-element-based numerical simulations are conducted to account for the end effects as well as to validate the analytical solutions. We show that, with the exception of the migratory ionic conductivity, all the physicochemical parameters are strong functions of the channel aspect ratio. Accordingly, a slit geometry is not a good representative of a rectangular channel when the width is comparable to the height. It is also observed that the distribution of the electrical potential is not uniform over the surface of a charge-regulated channel. In addition, unlike ordinary channels for which an increase in the background salt concentration is always accompanied by higher flow rates, quite the opposite may be true for a pH-regulated duct at higher salt concentrations.

  13. Structural manipulation approaches towards enhanced sodium ionic conductivity in Na-rich antiperovskites

    DOE PAGES

    Wang, Yonggang; Wang, Qingfei; Liu, Zhenpu; ...

    2015-06-10

    High-performance solid electrolytes are critical for realizing all-solid-state batteries with enhance safety and cycling efficiency. However, currently available candidates (sulfides and the NASICON-typ ceramics) still suffer from drawbacks such as inflammability, high-cost and unfavorable machinability Here we present the structural manipulation approaches to improve the sodium ionic conductivity in series of affordable Na-rich antiperovskites. Experimentally, the whole solid solutions of Na3OX (X ¼ Cl Br, I) are synthesized via a facile and timesaving route from the cheapest raw materials (Na, NaOH an NaX). The materials are nonflammable, suitable for thermoplastic processing due to low melting temperature (<300° C) without decomposing.more » Notably, owing to the flexibility of perovskite-type structure it's feasible to control the local structure features by means of size-mismatch substitution an unequivalent-doping for a favorable sodium ionic diffusion pathway. Enhancement of sodium ioni conductivity by 2 magnitudes is demonstrated by these chemical tuning methods. The optimized sodiu ionic conductivity in Na2.9Sr0.05OBr0.6I0.4 bulk samples reaches 1.9 10- 3 S/cm at 200° C and even highe at elevated temperature. Here, we believe further chemical tuning efforts on Na-rich antiperovskites wil promote their performance greatly for practical all-solid state battery applications.« less

  14. Non-Arrhenius ionic conductivities in glasses due to a distribution of activation energies.

    PubMed

    Bischoff, C; Schuller, K; Beckman, S P; Martin, S W

    2012-08-17

    Previously observed non-Arrhenius behavior in fast ion conducting glasses [J. Kincs and S. W. Martin, Phys. Rev. Lett. 76, 70 (1996)] occurs at temperatures near the glass transition temperature, T(g), and is attributed to changes in the ion mobility due to ion trapping mechanisms that diminish the conductivity and result in a decreasing conductivity with increasing temperature. It is intuitive that disorder in glass will also result in a distribution of the activation energies (DAE) for ion conduction, which should increase the conductivity with increasing temperature, yet this has not been identified in the literature. In this Letter, a series of high precision ionic conductivity measurements are reported for 0.5Na(2)S + 0.5[xGeS(2) + (1-x)PS(5/2)] glasses with compositions ranging from 0 ≤ x ≤ 1. The impact of the cation site disorder on the activation energy is identified and explained using a DAE model. The absence of the non-Arrhenius behavior in other glasses is explained and it is predicted which glasses are expected to accentuate the DAE effect on the ionic conductivity.

  15. Interfacial interactions in aprotic ionic liquid based protonic membrane and its correlation with high temperature conductivity and thermal properties.

    PubMed

    Mistry, Mayur K; Subianto, Surya; Choudhury, Namita Roy; Dutta, Naba K

    2009-08-18

    Novel supported liquid membranes (SLMs) have been developed by impregnating Nafion and Hyflon membranes with ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMI-BTSI). These supported liquid membranes were characterized in terms of their ionic liquid uptake behavior, leaching of ionic liquid by water, thermal stability, mechanical properties, glass transition temperature, ion exchange capacity, and proton conductivity. In general, modified membranes are more flexible than unmodified samples due to the plasticization effects of the ionic liquid. However, these supported liquid membranes exhibit a significant increase in their operational stability and proton conductivity over unmodified membranes. We also demonstrate that proton conductivity of these supported liquid membranes allows conduction of protons in anhydrous conditions with conductivity increasing with temperature. Conductivity of up to 3.58 mS cm(-1) has been achieved at 160 degrees C in dry conditions, making these materials promising for various electrochemical applications.

  16. Ionic conductivity, structural deformation, and programmable anisotropy of DNA origami in electric field.

    PubMed

    Li, Chen-Yu; Hemmig, Elisa A; Kong, Jinglin; Yoo, Jejoong; Hernández-Ainsa, Silvia; Keyser, Ulrich F; Aksimentiev, Aleksei

    2015-02-24

    The DNA origami technique can enable functionalization of inorganic structures for single-molecule electric current recordings. Experiments have shown that several layers of DNA molecules, a DNA origami plate, placed on top of a solid-state nanopore is permeable to ions. Here, we report a comprehensive characterization of the ionic conductivity of DNA origami plates by means of all-atom molecular dynamics (MD) simulations and nanocapillary electric current recordings. Using the MD method, we characterize the ionic conductivity of several origami constructs, revealing the local distribution of ions, the distribution of the electrostatic potential and contribution of different molecular species to the current. The simulations determine the dependence of the ionic conductivity on the applied voltage, the number of DNA layers, the nucleotide content and the lattice type of the plates. We demonstrate that increasing the concentration of Mg(2+) ions makes the origami plates more compact, reducing their conductivity. The conductance of a DNA origami plate on top of a solid-state nanopore is determined by the two competing effects: bending of the DNA origami plate that reduces the current and separation of the DNA origami layers that increases the current. The latter is produced by the electro-osmotic flow and is reversible at the time scale of a hundred nanoseconds. The conductance of a DNA origami object is found to depend on its orientation, reaching maximum when the electric field aligns with the direction of the DNA helices. Our work demonstrates feasibility of programming the electrical properties of a self-assembled nanoscale object using DNA.

  17. Ionic Conductivity, Structural Deformation and Programmable Anisotropy of DNA Origami in Electric Field

    PubMed Central

    Li, Chen-Yu; Hemmig, Elisa A.; Kong, Jinglin; Yoo, Jejoong; Hernández-Ainsa, Silvia

    2015-01-01

    The DNA origami technique can enable functionalization of inorganic structures for single-molecule electric current recordings. Experiments have shown that several layers of DNA molecules—a DNA origami plate— placed on top of a solid-state nanopore is permeable to ions. Here, we report a comprehensive characterization of the ionic conductivity of DNA origami plates by means of all-atom molecular dynamics (MD) simulations and nanocapillary electric current recordings. Using the MD method, we characterize the ionic conductivity of several origami constructs, revealing the local distribution of ions, the distribution of the electrostatic potential and contribution of different molecular species to the current. The simulations determine the dependence of the ionic conductivity on the applied voltage, the number of DNA layers, the nucleotide content and the lattice type of the plates. We demonstrate that increasing the concentration of Mg2+ ions makes the origami plates more compact, reducing their conductivity. The conductance of a DNA origami plate on top of a solid-state nanopore is determined by the two competing effects: bending of the DNA origami plate that reduces the current and separation of the DNA origami layers that increases the current. The latter is produced by the electro-osmotic flow and is reversible at the time scale of a hundred nanoseconds. The conductance of a DNA origami object is found to depend on its orientation, reaching maximum when the electric field aligns with the direction of the DNA helices. Our work demonstrates feasibility of programming the electrical properties of a self-assembled nanoscale object using DNA. PMID:25623807

  18. Enhancing grain boundary ionic conductivity in mixed ionic–electronic conductors

    PubMed Central

    Lin, Ye; Fang, Shumin; Su, Dong; Brinkman, Kyle S; Chen, Fanglin

    2015-01-01

    Mixed ionic–electronic conductors are widely used in devices for energy conversion and storage. Grain boundaries in these materials have nanoscale spatial dimensions, which can generate substantial resistance to ionic transport due to dopant segregation. Here, we report the concept of targeted phase formation in a Ce0.8Gd0.2O2−δ–CoFe2O4 composite that serves to enhance the grain boundary ionic conductivity. Using transmission electron microscopy and spectroscopy approaches, we probe the grain boundary charge distribution and chemical environments altered by the phase reaction between the two constituents. The formation of an emergent phase successfully avoids segregation of the Gd dopant and depletion of oxygen vacancies at the Ce0.8Gd0.2O2−δ–Ce0.8Gd0.2O2−δ grain boundary. This results in superior grain boundary ionic conductivity as demonstrated by the enhanced oxygen permeation flux. This work illustrates the control of mesoscale level transport properties in mixed ionic–electronic conductor composites through processing induced modifications of the grain boundary defect distribution. PMID:25857355

  19. Enhancing grain boundary ionic conductivity in mixed ionic–electronic conductors

    SciTech Connect

    Lin, Ye; Fang, Shumin; Su, Dong; Brinkman, Kyle S.; Chen, Fanglin

    2015-04-10

    Mixed ionic–electronic conductors are widely used in devices for energy conversion and storage. Grain boundaries in these materials have nanoscale spatial dimensions, which can generate substantial resistance to ionic transport due to dopant segregation. Here, we report the concept of targeted phase formation in a Ce0.8Gd0.2O2₋δ–CoFe2O4 composite that serves to enhance the grain boundary ionic conductivity. Using transmission electron microscopy and spectroscopy approaches, we probe the grain boundary charge distribution and chemical environments altered by the phase reaction between the two constituents. The formation of an emergent phase successfully avoids segregation of the Gd dopant and depletion of oxygen vacancies at the Ce0.8Gd0.2O2₋δ–Ce0.8Gd0.2O2₋δ grain boundary. This results in superior grain boundary ionic conductivity as demonstrated by the enhanced oxygen permeation flux. Lastly, this work illustrates the control of mesoscale level transport properties in mixed ionic–electronic conductor composites through processing induced modifications of the grain boundary defect distribution.

  20. Enhancing grain boundary ionic conductivity in mixed ionic–electronic conductors

    DOE PAGES

    Lin, Ye; Fang, Shumin; Su, Dong; ...

    2015-04-10

    Mixed ionic–electronic conductors are widely used in devices for energy conversion and storage. Grain boundaries in these materials have nanoscale spatial dimensions, which can generate substantial resistance to ionic transport due to dopant segregation. Here, we report the concept of targeted phase formation in a Ce0.8Gd0.2O2₋δ–CoFe2O4 composite that serves to enhance the grain boundary ionic conductivity. Using transmission electron microscopy and spectroscopy approaches, we probe the grain boundary charge distribution and chemical environments altered by the phase reaction between the two constituents. The formation of an emergent phase successfully avoids segregation of the Gd dopant and depletion of oxygen vacanciesmore » at the Ce0.8Gd0.2O2₋δ–Ce0.8Gd0.2O2₋δ grain boundary. This results in superior grain boundary ionic conductivity as demonstrated by the enhanced oxygen permeation flux. Lastly, this work illustrates the control of mesoscale level transport properties in mixed ionic–electronic conductor composites through processing induced modifications of the grain boundary defect distribution.« less

  1. Sensitive and Fast Humidity Sensor Based on A Redox Conducting Supramolecular Ionic Material for Respiration Monitoring.

    PubMed

    Yan, Hailong; Zhang, Li; Yu, Ping; Mao, Lanqun

    2017-01-03

    Real-time monitoring of respiratory rate (RR) is highly important for human health, clinical diagnosis, and fundamental scientific research. Exhaled humidity-based RR monitoring has recently attracted increased attention because of its accuracy and portability. Here, we report a new design of an exhaled humidity sensor for the real-time monitoring of the RR based on a synthetic redox conducting supramolecular ionic material (SIM). The humidity-dependent conducting SIM is prepared by ionic self-assembly in aqueous solutions of electroactive 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,10-bis(3-methylimidazolium-1-yl) decane (C10(mim)2). By taking full advantage of the high hygroscopicity and water stability arising from the ionic and hydrophobic interactions between two building blocks (i.e., ABTS and C10(mim)2), the SIM-based humidity sensor exhibits both high sensitivity (less than 0.1% relative humidity) and fast response time (∼37 ms). These excellent properties allow this humidity sensor to noninvasively monitor the RRs of not only humans but also rats that have a much faster RR and much smaller tidal volume than humans. Moreover, this sensor could also be efficiently used for the real-time monitoring of the recovery process of rats from anesthesia.

  2. Altered ion channel conductance and ionic selectivity induced by large imposed membrane potential pulse.

    PubMed Central

    Chen, W; Lee, R C

    1994-01-01

    The effects of large magnitude transmembrane potential pulses on voltage-gated Na and K channel behavior in frog skeletal muscle membrane were studied using a modified double vaseline-gap voltage clamp. The effects of electroconformational damage to ionic channels were separated from damage to lipid bilayer (electroporation). A 4 ms transmembrane potential pulse of -600 mV resulted in a reduction of both Na and K channel conductivities. The supraphysiologic pulses also reduced ionic selectivity of the K channels against Na+ ions, resulting in a depolarization of the membrane resting potential. However, TTX and TEA binding effects were unaltered. The kinetics of spontaneous reversal of the electroconformational damage of channel proteins was found to be dependent on the magnitude of imposed membrane potential pulse. These results suggest that muscle and nerve dysfunction after electrical shock may be in part caused by electroconformational damage to voltage-gated ion channels. PMID:7948676

  3. Correlation between the glass-rubber transition and ionic conductivity in poly(3-hexylthiophene)

    NASA Astrophysics Data System (ADS)

    Lada, M.

    2008-10-01

    Using impedance spectroscopy and metal-insulator-semiconductor structures, the small-signal bulk conductivity of annealed poly(3-hexylthiophene) (P3HT) has been extracted in the temperature range of 150-420K. A faster-than-Arrhenius increase in the conductivity of P3HT observed near and above room temperature is shown to be a result of the glass-rubber transition and is closely related to the amorphous phase of the polymer. The super-Arrhenius conductivity can be modeled and interpreted as ionic, arising from the thermal motion of the polymer segments. In addition, a percolative conduction mechanism induced by the glass transition can phenomenologically model the conductivity increase.

  4. Effect of ionic conductivity of zirconia electrolytes on polarization properties of various electrodes in SOFC

    SciTech Connect

    Watanabe, Masahiro; Uchida, Hiroyuki; Yoshida, Manabu

    1996-12-31

    Solid oxide fuel cells (SOFCs) have been intensively investigated because, in principle, their energy conversion efficiency is fairly high. Lowering the operating temperature of SOFCs from 1000{degrees}C to around 800{degrees}C is desirable for reducing serious problems such as physical and chemical degradation of the constructing materials. The object of a series of the studies is to find a clue for achieving higher electrode performances at a low operating temperature than those of the present level. Although the polarization loss at electrodes can be reduced by using mixed-conducting ceria electrolytes, or introducing the mixed-conducting (reduced zirconia or ceria) laver on the conventional zirconia electrolyte surface, no reports are available on the effect of such an ionic conductivity of electrolytes on electrode polarizations. High ionic conductivity of the electrolyte, of course, reduces the ohmic loss. However, we have found that the IR-free polarization of a platinum anode attached to zirconia electrolytes is greatly influenced by the ionic conductivity, {sigma}{sub ion}, of the electrolytes used. The higher the {sigma}{sub ion}, the higher the exchange current density, j{sub 0}, for the Pt anode in H{sub 2} at 800 {approximately} 1000{degrees}C. It was indicated that the H{sub 2} oxidation reaction rate was controlled by the supply rate of oxide ions through the Pt/zirconia interface which is proportional to the {sigma}{sub ion}. Recently, we have proposed a new concept of the catalyzed-reaction layers which realizes both high-performances of anodes and cathodes for medium-temperature operating SOFCs. We present the interesting dependence of the polarization properties of various electrodes (the SDC anodes with and without Ru microcatalysts, Pt cathode, La(Sr)MnO{sub 3} cathodes with and without Pt microcatalysts) on the {sigma}{sub ion} of various zirconia electrolytes at 800 {approximately} 1000{degrees}C.

  5. Enhancing ionic conductivity in composite polymer electrolytes with well-aligned ceramic nanowires

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Lee, Seok Woo; Lin, Dingchang; Shi, Feifei; Wang, Shuang; Sendek, Austin D.; Cui, Yi

    2017-04-01

    In contrast to conventional organic liquid electrolytes that have leakage, flammability and chemical stability issues, solid electrolytes are widely considered as a promising candidate for the development of next-generation safe lithium-ion batteries. In solid polymer electrolytes that contain polymers and lithium salts, inorganic nanoparticles are often used as fillers to improve electrochemical performance, structure stability, and mechanical strength. However, such composite polymer electrolytes generally have low ionic conductivity. Here we report that a composite polymer electrolyte with well-aligned inorganic Li+-conductive nanowires exhibits an ionic conductivity of 6.05 × 10-5 S cm-1 at 30 ∘C, which is one order of magnitude higher than previous polymer electrolytes with randomly aligned nanowires. The large conductivity enhancement is ascribed to a fast ion-conducting pathway without crossing junctions on the surfaces of the aligned nanowires. Moreover, the long-term structural stability of the polymer electrolyte is also improved by the use of nanowires.

  6. Conductivity dispersion in supercooled calcium potassium nitrate: caged ionic motion viewed as part of standard behaviour.

    PubMed

    Funke, Klaus; Singh, Prabhakar; Banhatti, Radha Dilip

    2007-11-07

    Conductivity spectra of ionic materials with disordered structures are usually thought to consist of several parts, i.e., the DC conductivity, a power-law component, a nearly-constant-loss feature (if identified) and the (far-)infrared conductivity caused by vibrational motion. Such a decomposition may, however, easily lead to a misinterpretation of the underlying dynamics. Here, we discuss broad-band conductivity data of the supercooled glass-forming melt calcium potassium nitrate, of composition 0.4 Ca(NO(3))(2).0.6 KNO(3), often abbreviated as CKN. Data have been taken at frequencies up to the far infrared. We show that the frequency-dependent conductivity is very well reproduced by a superposition of only two components. One of them is due to vibrations, the other is caused by displacements of the mobile ions. The latter component, which does not follow a power law, is described in terms of a physical model called the MIGRATION concept. This model treatment has been found to apply in many solid electrolytes as well and is, therefore, considered to provide a "standard" formulation of the ion dynamics. The gradual transition from a correlated forward-backward ("caged") ionic motion to a stepwise translational motion may be regarded as the main feature of the MIGRATION concept.

  7. Enhanced ionic conductivity of AgI nanowires/AAO composites fabricated by a simple approach

    NASA Astrophysics Data System (ADS)

    Liu, Li-Feng; Lee, Seung-Woo; Li, Jing-Bo; Alexe, Marin; Rao, Guang-Hui; Zhou, Wei-Ya; Lee, Jae-Jong; Lee, Woo; Gösele, Ulrich

    2008-12-01

    AgI nanowires/anodic aluminum oxide (AgI NWs/AAO) composites have been fabricated by a simple approach, which involves the thermal melting of AgI powders on the surface of the AAO membrane, followed by the infiltration of the molten AgI inside the nanochannels. As-prepared AgI nanowires have corrugated outer surfaces and are polycrystalline according to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. X-ray diffraction (XRD) shows that a considerable amount of 7H polytype AgI exists in the composites, which is supposed to arise from the interfacial interactions between the embedded AgI and the alumina. AC conductivity measurements for the AgI nanowires/AAO composites exhibit a notable conductivity enhancement by three orders of magnitude at room temperature compared with that of pristine bulk AgI. Furthermore, a large conductivity hysteresis and abnormal conductivity transitions were observed in the temperature-dependent conductivity measurements, from which an ionic conductivity as high as 8.0 × 102 Ω-1 cm-1 was obtained at around 70 °C upon cooling. The differential scanning calorimetry (DSC) result demonstrates a similar phase transition behavior as that found in the AC conductivity measurements. The enhanced ionic conductivity, as well as the abnormal phase transitions, can be explained in terms of the existence of the highly conducting 7H polytype AgI and the formation of well-defined conduction paths in the composites.

  8. Noncovalent approach to one-dimensional ion conductors: enhancement of ionic conductivities in nanostructured columnar liquid crystals.

    PubMed

    Shimura, Harutoki; Yoshio, Masafumi; Hoshino, Koji; Mukai, Tomohiro; Ohno, Hiroyuki; Kato, Takashi

    2008-02-06

    Noncovalent design of new liquid-crystalline (LC) columnar assemblies based on an ionic liquid has shown to be useful to achieve anisotropic high ionic conductivities. An equimolar mixture of an ionic liquid, 1-butyl-3-methylimidazolium bromide, and 3-[3,4,5-tri(octyloxy)benzoyloxy]propane-1,2-diol, which is partially miscible with the ionic liquid, exhibits an LC hexagonal columnar phase from -4 to 63 degrees C. This columnar supramolecular assembly forming the nanostructures shows the one-dimensional (1D) ionic conductivity of 3.9 x 10(-3) S cm(-1) at 50 degrees C along the column, which is more than 700 times higher than that of the corresponding covalent-type columnar ionic liquid, 1-methyl-3-[3,4,5-tri(octyloxy)benzyl]imidazolium bromide, which is 5.3 x 10(-6) S cm(-1) at 50 degrees C. This significant enhancement of the ionic conductivity is attributed to the increase of the mobility of the ionic part.

  9. Liquid crystal self-assembly of halloysite nanotubes in ionic liquids: a novel soft nanocomposite ionogel electrolyte with high anisotropic ionic conductivity and thermal stability

    NASA Astrophysics Data System (ADS)

    Zhao, Ningning; Liu, Yulin; Zhao, Xiaomeng; Song, Hongzan

    2016-01-01

    We report a novel class of liquid crystalline (LC) nanohybrid ionogels fabricated via self-assembly of natural halloysite nanotubes (HNTs) in ionic liquids (ILs). The obtained ionogels are very stable and nonvolatile and show LC phases over a wide temperature range. Remarkably, the nanocomposite ionogels exhibit high anisotropic ionic conductivity after shear, and their room temperature ionic conductivity can reach 3.8 × 10-3 S cm-1 for aligned nanotubes perpendicular to the electrode even when the HNTs content increases to 40 wt%, which is 380 times higher than that obtained for aligned nanotubes parallel to the electrode, which is 1.0 × 10-5 S cm-1. Crucially, the obtained LC nanocomposite ionogels have very high thermal stability, which can sustain 400 °C thermal treatment. The findings will promote the development of novel nanocomposite ionogel electrolytes with faster ion transport and larger anisotropic conductivity.We report a novel class of liquid crystalline (LC) nanohybrid ionogels fabricated via self-assembly of natural halloysite nanotubes (HNTs) in ionic liquids (ILs). The obtained ionogels are very stable and nonvolatile and show LC phases over a wide temperature range. Remarkably, the nanocomposite ionogels exhibit high anisotropic ionic conductivity after shear, and their room temperature ionic conductivity can reach 3.8 × 10-3 S cm-1 for aligned nanotubes perpendicular to the electrode even when the HNTs content increases to 40 wt%, which is 380 times higher than that obtained for aligned nanotubes parallel to the electrode, which is 1.0 × 10-5 S cm-1. Crucially, the obtained LC nanocomposite ionogels have very high thermal stability, which can sustain 400 °C thermal treatment. The findings will promote the development of novel nanocomposite ionogel electrolytes with faster ion transport and larger anisotropic conductivity. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06888f

  10. Ionic conductivity measurement in magnesium aluminate spinel and solid state galvanic cell with magnesium aluminate electrolyte

    NASA Astrophysics Data System (ADS)

    Lee, Myongjai

    This thesis work is about the experimental measurement of electronic and ionic conductivities in the MgAl2O4 spinel at 500˜600°C range and exploring the fundamental origin of solid-state galvanic cell behavior in the cell of Al|MgAl2O4|Mg, Al|MgAl2O 4|C, and Mg|MgAl2O4|C, in which at least one metal electrode in common with the composition of the electrolyte. For the electronic conductivity measurement, we have used the ion-blocking Gold and Carbon electrodes which are inert with both Mg and Al ions to suppress the ionic conduction from the total conduction. DC polarization method was used to measure the conduction through Au|MgAl2O4|Au and C|MgAl2O4|C specimens. The measured electrical conductivity using Au|MgAl2O4|Au and C|MgAl2O4|C specimens showed 10-9.3 ˜ 10-8.4 (O·cm) -1 at 600˜720°C range following the Arrhenius-type relation. These conductivity data are in agreement with reported data obtained from Pt and Ag ion-blocking electrodes deposited on MgAl2O4 specimens. For the ionic conductivity measurement, we have used the non-blocking Al and Mg electrodes for Al and Mg ionic conductivities, respectively. Ionic conductivity measurement of Al and Mg in separate manner has not been reported yet. In both Al|MgAl2O4|Al and Mg|MgAl2O 4|Mg specimens, gradual increase of conduction was observed once at the initial period before it reaches the steady state conduction. By DC method on the range of 580˜650°C, steady state Al ionic conductivity was measured from Al|MgAl2O4|Al specimen showing 10 -7.7 ˜ 10-6.8 (O·cm)-1 with the activation energy of 1.9eV in sigma = sigma0 exp-QRT formula. There was no difference in the conductivity by the change of the atmosphere from 5%H2 + 95%N2 mixed gas to pure Ar gas. So it was confirmed that the oxygen defect chemistry did not play a role. For Mg ionic conductivity Mg|MgAl2O4|Mg specimen was used and the measured conductivity shows 10-6.7 ˜ 10-4.4 (O·cm)-1 at 400˜550°C with the activation energy of 1.44eV at Ar gas

  11. Influence of anionic vacancies on the ionic conductivity of silicated rare earth apatites

    SciTech Connect

    Panteix, P.J. Bechade, E.; Julien, I.; Abelard, P.; Bernache-Assollant, D.

    2008-05-06

    Oxyapatites are very promising materials in terms of ionic conductivity. They can be considered as a potential electrolyte for Solid Oxide Fuel Cells (SOFC). Doped silicated rare earth apatites with formula La{sub 9.33-x}Ca{sub x}(SiO{sub 4}){sub 6}O{sub 2-x/2} (0 {<=} x {<=} 1) have been prepared by solid state reaction at high temperature in order to determine the influence of anionic vacancies on the electrical properties of the material. The incorporation of calcium in the structure has been checked by characterizations of the powders (X-ray diffraction, helium pycnometry). The cell parameters of the hexagonal apatite were refined. Samples were sintered at 1550 deg. C. Electrical properties of each composition have been studied between 280 and 620 deg. C by the complex impedance method. The evolution of the bulk conductivity and of the activation energy with the substituting ratio gives information on the conductivity mechanism in these materials. An improvement of ionic conductivity about one order of magnitude has been observed for low calcium substitution ratios.

  12. A computational model with ionic conductances for the fusiform cell of the dorsal cochlear nucleus.

    PubMed

    Kim, D O; Ghoshal, S; Khant, S L; Parham, K

    1994-09-01

    A computational model of a fusiform cell of the dorsal cochlear nucleus was developed. The results of model simulations are compared with the results of in vitro experimental observations obtained by other investigators. The structure of the present model is similar to that of Hodgkin-Huxley [J. Physiol. 117, 500-544 (1952)]. The model incorporates five nonlinear voltage-dependent conductances (three potassium and two sodium types) and their associated equilibrium-potential batteries, a leakage conductance, the membrane capacitance, and a current source. Model responses were obtained under both current- and voltage-clamp conditions. When a hyper- and depolarizing current sequence was applied [Manis, J. Neurosci. 10, 2338-2351 (1990)], the cell model was able to reproduce builduplike and pauserlike discharge patterns closely resembling Manis' observations. A transient "A"-type potassium conductance in the model played a major role in generating this phenomenon. The model predicts that blocking the "A" conductance should convert a builduplike or pauserlike pattern into a sustained regular pattern. A persistent sodium conductance in the model played the main role in reproducing: Spontaneous regular discharge; a discharge after a long latency under a long small (+0.025 nA) current; and nonlinear voltage-current characteristics with positive currents. Usefulness of the model can be seen as follows: (1) Several sets of experimental observations can be integrated into a common framework; (2) possible roles of different ionic conductances postulated to be present in the cell can be inferred by observing the model behavior with the conductances intact or blocked; and (3) time courses of ionic currents and conductance values obtained from the model under current- and voltage-clamp conditions can serve as predictions to be tested in future experimental studies.

  13. Molar conductivity behavior of ionic liquid compare to inorganic salt in electrolyte solution at ambien temperature

    NASA Astrophysics Data System (ADS)

    Hanibah, H.; Hashim, N. Z. Nor; Shamsudin, I. J.

    2017-09-01

    Molar Conductivity (Λ) behaviour of 1-butyl-3-methylimidazolium (Bmin) acetate and Bmin chloride (Bmin Cl) ionic liquids compared to lithium perchlorate (LiClO4) has been studied in aqueous and acetonitrile (ACN) solution at ambient temperature. The limiting molar conductivity (Λ0) was obtained using the Kohlrausch's and Ostwald's equation for the investigated systems. The results show that the Λ0 value for LiClO4 in both aqueous or acetonitrile (ACN) electrolyte system with a highest value as compare to ionic liquid electrolyte systems. This might as a result of ions association of LiClO4 in aqueous medium as the concentration of the solute increases in the solvent. In addition, the partial dissociation behaviour of LiClO4 in less polar solvent such as ACN also significantly affects the Λ0 value for this electrolyte system. However, for Bmin acetate and Bmin Cl in the aqueous or ACN medium show a much lower Λ0 value as compare to LiClO4 electrolyte system, 45.64, 74.63 and 107.32 S cm2 mol-1 respectively. This as a result of the nature behaviour of ionic liquid itself that present as free moving ions at room temperature before any dissolution into the solvent. In addition, a vice versa trend of Λ0 value is noted for Bmin acetate and Bmin Cl, 21.34 and 14.56 S cm2 mol-1 respectively in ACN electrolyte system. This indicated the solvent and the size of the anion play an important role in the estimation of limiting molar conductivity values which significantly affect the present of total free moving ions in an electrolyte system.

  14. Self-Assembled Polymeric Ionic Liquid-Functionalized Cellulose Nano-crystals: Constructing 3D Ion-conducting Channels Within Ionic Liquid-based Composite Polymer Electrolytes.

    PubMed

    Shi, Qing Xuan; Xia, Qing; Xiang, Xiao; Ye, Yun Sheng; Peng, Hai Yan; Xue, Zhi Gang; Xie, Xiao Lin; Mai, Yiu-Wing

    2017-09-04

    Composite polymeric and ionic liquid (IL) electrolytes are some of the most promising electrolyte systems for safer battery technology. Although much effort has been directed towards enhancing the transport properties of polymer electrolytes (PEs) through nanoscopic modification by incorporating nano-fillers, it is still difficult to construct ideal ion conducting networks. Here, a novel class of three-dimensional self-assembled polymeric ionic liquid (PIL)-functionalized cellulose nano-crystals (CNC) confining ILs in surface-grafted PIL polymer chains, able to form colloidal crystal polymer electrolytes (CCPE), is reported. The high-strength CNC nano-fibers, decorated with PIL polymer chains, can spontaneously form three-dimensional interpenetrating nano-network scaffolds capable of supporting electrolytes with continuously connected ion conducting networks with IL being concentrated in conducting domains. These new CCPE have exceptional ionic conductivities, low activation energies (close to bulk IL electrolyte with dissolved Li salt), high Li(+) transport numbers, low interface resistances and improved interface compatibilities. Furthermore, the CCPE displays good electrochemical properties and a good battery performance. This approach offers a route to leak-free, non-flammable and high ionic conductivity solid-state PE in energy conversion devices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Ionic charge transport between blockages: Sodium cation conduction in freshly excised bulk brain tissue

    SciTech Connect

    Emin, David; Akhtari, Massoud; Ellingson, B. M.; Mathern, G. W.

    2015-08-15

    We analyze the transient-dc and frequency-dependent electrical conductivities between blocking electrodes. We extend this analysis to measurements of ions’ transport in freshly excised bulk samples of human brain tissue whose complex cellular structure produces blockages. The associated ionic charge-carrier density and diffusivity are consistent with local values for sodium cations determined non-invasively in brain tissue by MRI (NMR) and diffusion-MRI (spin-echo NMR). The characteristic separation between blockages, about 450 microns, is very much shorter than that found for sodium-doped gel proxies for brain tissue, >1 cm.

  16. Ionic conductivity and dielectric permittivity of PEO-LiClO{sub 4} solid polymer electrolyte plasticized with propylene carbonate

    SciTech Connect

    Das, S.; Ghosh, A.

    2015-02-15

    We have studied ionic conductivity and dielectric permittivity of PEO-LiClO{sub 4} solid polymer electrolyte plasticized with propylene carbonate. Differential scanning calorimetry and X-ray diffraction studies confirm minimum volume fraction of crystalline phase for the polymer electrolyte with 40 wt. % propylene carbonate. The ionic conductivity exhibits a maximum for the same composition. The temperature dependence of the ionic conductivity has been well interpreted using Vogel-Tamman-Fulcher equation. Ion-ion interactions in the polymer electrolytes have been studied using Raman spectra and the concentrations of free ions, ion-pairs and ion-aggregates have been determined. The ionic conductivity increases due to the increase of free ions with the increase of propylene carbonate content. But for higher content of propylene carbonate, the ionic conductivity decreases due to the increase of concentrations of ion-pairs and ion-aggregates. To get further insights into the ion dynamics, the experimental data for the complex dielectric permittivity have been studied using Havriliak–Negami function. The variation of relaxation time with temperature obtained from this formalism follows Vogel-Tamman-Fulcher equation similar to the ionic conductivity.

  17. Water uptake, ionic conductivity and swelling properties of anion-exchange membrane

    SciTech Connect

    Duan, QJ; Ge, SH; Wang, CY

    2013-12-01

    Water uptake, ionic conductivity and dimensional change of the anion-exchange membrane made by Tokuyama Corporation (A201 membrane) are investigated at different temperatures and water activities. Specifically, the amount of water taken up by membranes exposed to water vapor and membranes soaked in liquid water is determined. The water uptake of the A201 membrane increases with water content as well as temperature. In addition, water sorption data shows Schroeder's paradox for the AEMs investigated. The swelling properties of the A201 membrane exhibit improved dimensional stability compared with Nafion membrane. Water sorption of the A201 membrane occurs with a substantial negative excess volume of mixing. The threshold value of hydrophilic fraction in the A201 membrane for ionic conductivity is around 0.34, above which, the conductivity begins to rise quickly. This indicates that a change in the connectivity of the hydrophilic domains occurs when hydrophilic fraction approaches 0.34. (C) 2013 Elsevier B.V. All rights reserved.

  18. Characterization of conducting cellulose acetate based polymer electrolytes doped with "green" ionic mixture.

    PubMed

    Ramesh, S; Shanti, R; Morris, Ezra

    2013-01-02

    Polymer electrolytes were developed by solution casting technique utilizing the materials of cellulose acetate (CA), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and deep eutectic solvent (DES). The DES is synthesized from the mixture of choline chloride and urea of 1:2 ratios. The increasing DES content well plasticizes the CA:LiTFSI:DES matrix and gradually improves the ionic conductivity and chemical integrity. The highest conducting sample was identified for the composition of CA:LiTFSI:DES (28 wt.%:12 wt.%:60 wt.%), which has the greatest ability to retain the room temperature ionic conductivity over the entire 30 days of storage time. The changes in FTIR cage peaks upon varying the DES content in CA:LiTFSI:DES prove the complexation. This complexation results in the collapse of CA matrix crystallinity, observed from the reduced intensity of XRD diffraction peaks. The DES-plasticized sample is found to be more heat-stable compared to pure CA. Nevertheless, the addition of DES diminishes the CA:LiTFSI matrix's heat-resistivity but at the minimum addition the thermal stability is enhanced.

  19. Ionic conductivity of nanocrystalline yttria-stabilized zirconia: Grain boundary and size effects

    NASA Astrophysics Data System (ADS)

    Durá, O. J.; López de La Torre, M. A.; Vázquez, L.; Chaboy, J.; Boada, R.; Rivera-Calzada, A.; Santamaria, J.; Leon, C.

    2010-05-01

    We report on the effect of grain size on the ionic conductivity of yttria-stabilized zirconia samples synthesized by ball milling. Complex impedance measurements, as a function of temperature and frequency are performed on 10mol% yttria-stabilized zirconia nanocrystalline samples with grain sizes ranging from 900 to 17 nm. Bulk ionic conductivity decreases dramatically for grain sizes below 100 nm, although its activation energy is essentially independent of grain size. The results are interpreted in terms of a space-charge layer resulting from segregation of mobile oxygen vacancies to the grain-boundary core. The thickness of this space-charge layer formed at the grain boundaries is on the order of 1 nm for large micron-sized grains but extends up to 7 nm when decreasing the grain size down to 17 nm. This gives rise to oxygen vacancies depletion over a large volume fraction of the grain and consequently to a significant decrease in oxide-ion conductivity.

  20. Ionic Conductance Changes in Lobster Axon Membrane When Lanthanum Is Substituted for Calcium

    PubMed Central

    Takata, M.; Pickard, W. F.; Lettvin, J. Y.; Moore, J. W.

    1966-01-01

    The trivalent rare earth lanthanum was substituted for calcium in the sea water bathing the exterior of an "artificial node" of a lobster axon in a sucrose gap. It caused a progressive rise in threshold, and a decrease in the height of the action potential as well as in its rates of rise and fall. Prolonged application produced an excitation block. Voltage-clamp studies of the ionic currents showed that the time courses of the ionic conductance changes for both sodium and potassium were increased. Concurrently, the potentials at which the conductance increases occurred were shifted to more positive inside values for the La+++ sea water. These effects resemble changes resulting from a high external calcium concentration. Over and above this, La+++ also causes a marked reduction in the maximum amount of conductance increase following a depolarizing potential step. Membrane action potentials similar to those observed experimentally in the La+++ solution have been computed with appropriate parameter changes in the Hodgkin-Huxley equations. PMID:11526840

  1. Electrical conductivity study on micelle formation of long-chain imidazolium ionic liquids in aqueous solution.

    PubMed

    Inoue, Tohru; Ebina, Hayato; Dong, Bin; Zheng, Liqiang

    2007-10-01

    Electrical conductivity was measured for aqueous solutions of long-chain imidazolium ionic liquids (IL), 1-alkyl-3-methylimidazolium bromides with C(12)-C(16) alkyl chains. The break points appeared in specific conductivity (kappa) vs concentration (c) plot indicates that the molecular aggregates, i.e., micelles, are formed in aqueous solutions of these IL species. The critical micelle concentration (cmc) determined from the kappa vs c plot is somewhat lower than those for typical cationic surfactants, alkyltrimethylammonium bromides with the same hydrocarbon chain length. The electrical conductivity data were analyzed according to the mixed electrolyte model of micellar solution, and the aggregation number, n, and the degree of counter ion binding, beta, were estimated. The n values of the present ILs are somewhat smaller than those reported for alkyltrimethylammonium bromides, which may be attributed to bulkiness of the cationic head group of the IL species. The thermodynamic parameters for micelle formation of the present ILs were estimated using the values of cmc and beta as a function of temperature. The contribution of entropy term to the micelle formation is superior to that of enthalpy term below about 30 degrees C, and it becomes opposite at higher temperature. This coincides with the picture drawn for the micelle formation of conventional ionic surfactants.

  2. Ionic conductance changes in lobster axon membrane when lanthanum is substituted for calcium.

    PubMed

    Takata, M; Pickard, W F; Lettvin, J Y; Moore, J W

    1966-11-01

    The trivalent rare earth lanthanum was substituted for calcium in the sea water bathing the exterior of an "artificial node" of a lobster axon in a sucrose gap. It caused a progressive rise in threshold, and a decrease in the height of the action potential as well as in its rates of rise and fall. Prolonged application produced an excitation block. Voltage-clamp studies of the ionic currents showed that the time courses of the ionic conductance changes for both sodium and potassium were increased. Concurrently, the potentials at which the conductance increases occurred were shifted to more positive inside values for the La+++ sea water. These effects resemble changes resulting from a high external calcium concentration. Over and above this, La+++ also causes a marked reduction in the maximum amount of conductance increase following a depolarizing potential step. Membrane action potentials similar to those observed experimentally in the La+++ solution have been computed with appropriate parameter changes in the Hodgkin-Huxley equations.

  3. Influence of Ionic Conductances on Spike Timing Reliability of Cortical Neurons for Suprathreshold Rhythmic Inputs

    PubMed Central

    Schreiber, Susanne; Fellous, Jean-Marc; Tiesinga, Paul; Sejnowski, Terrence J.

    2010-01-01

    Spike timing reliability of neuronal responses depends on the frequency content of the input. We investigate how intrinsic properties of cortical neurons affect spike timing reliability in response to rhythmic inputs of suprathreshold mean. Analyzing reliability of conductance-based cortical model neurons on the basis of a correlation measure, we show two aspects of how ionic conductances influence spike timing reliability. First, they set the preferred frequency for spike timing reliability, which in accordance with the resonance effect of spike timing reliability is well approximated by the firing rate of a neuron in response to the DC component in the input. We demonstrate that a slow potassium current can modulate the spike timing frequency preference over a broad range of frequencies. This result is confirmed experimentally by dynamic-clamp recordings from rat prefrontal cortical neurons in vitro. Second, we provide evidence that ionic conductances also influence spike timing beyond changes in preferred frequency. Cells with the same DC firing rate exhibit more reliable spike timing at the preferred frequency and its harmonics if the slow potassium current is larger and its kinetics are faster, whereas a larger persistent sodium current impairs reliability. We predict that potassium channels are an efficient target for neuromodulators that can tune spike timing reliability to a given rhythmic input. PMID:14507985

  4. Ionic conductivities of lithium phosphorus oxynitride glasses, polycrystals, and thin films

    SciTech Connect

    Wang, B.; Bates, J.B.; Chakoumakos, B.C.; Sales, B.C.; Kwak, B.S.; Zuhr, R.A.; Robertson, J.D.

    1994-11-01

    Various lithium phosphorus oxynitrides have been prepared in the form of glasses, polycrystals, and thin films. The structures of these compounds were investigated by X-ray and neutron diffraction, X-ray photoelectron spectroscopy (XPS), and high-performance liquid chromatography (HPLC). The ac impedance measurements indicate a significant improvement of ionic conductivity as the result of incorporation of nitrogen into the structure. In the case of polycrystalline Li{sub 2.88}PO{sub 3.73}N{sub 0.14} with the {gamma}-Li{sub 3}PO{sub 4} structure, the conductivity increased by several orders of magnitude on small addition of nitrogen. The highest conductivities in the bulk glasses and thin films were found to be 3.0 {times} 10{sup -7} and 8.9 {times} 10{sup -7} S{center_dot}cm{sup -1} at 25{degrees}C, respectively.

  5. Phase behavior and ionic conductivity in lithium bis(trifluoromethanesulfonyl)imide-doped ionic liquids of the pyrrolidinium cation and Bis(trifluoromethanesulfonyl)imide anion.

    PubMed

    Martinelli, Anna; Matic, Aleksandar; Jacobsson, Per; Börjesson, Lars; Fernicola, Alessandra; Scrosati, Bruno

    2009-08-13

    The phase behavior and the ionic conductivity of ionic liquids (ILs) of the N-alkyl-N-alkylpyrrolidinium (PYR(xy)) cation and the bis(trifluoromethanesulfonyl)imide (TFSI) anion are investigated upon addition of LiTFSI salt. We compare the case of two new ILs of the PYR(2y) cation (where 2 is ethyl and y is butyl or propyl) with that of the PYR(14) (where 1 is methyl and 4 is butyl). We find that the addition of LiTFSI increases the glass transition temperature, decreases the melting temperature and the heat of fusion and, in the ILs of the PYR(2y) family, suppresses crystallization. In the solid state, significant ionic conductivities are found, being as high as 10(-5) S cm(-1), strongly increasing with Li(+) concentration. The opposite trend is found in the liquid state, where the conductivity is on the order of 10(-3)-10(-2) S cm(-1) at room temperature. A T(g)-scaled Arrhenius plot shows that the liquid-state ionic conductivity in these systems is mainly governed by viscosity and that the fragility of the liquids is slightly influenced by the structural modifications on the cation.

  6. Oxygen flux and dielectric response study of Mixed Ionic-Electronic Conducting (MIEC) heterogeneous functional materials

    NASA Astrophysics Data System (ADS)

    Rabbi, Fazle

    Dense mixed ionic-electronic conducting (MIEC) membranes consisting of ionic conductive perovskite-type and/or fluorite-type oxides and high electronic conductive spinel type oxides, at elevated temperature can play a useful role in a number of energy conversion related systems including the solid oxide fuel cell (SOFC), oxygen separation and permeation membranes, partial oxidization membrane reactors for natural gas processing, high temperature electrolysis cells, and others. This study will investigate the impact of different heterogeneous characteristics of dual phase ionic and electronic conductive oxygen separation membranes on their transport mechanisms, in an attempt to develop a foundation for the rational design of such membranes. The dielectric behavior of a material can be an indicator for MIEC performance and can be incorporated into computational models of MIEC membranes in order to optimize the composition, microstructure, and ultimately predict long term membrane performance. The dielectric behavior of the MIECs can also be an indicator of the transport mechanisms and the parameters they are dependent upon. For this study we chose a dual phase MIEC oxygen separation membrane consisting of an ionic conducting phase: gadolinium doped ceria-Ce0.8 Gd0.2O2 (GDC) and an electronic conductive phase: cobalt ferrite-CoFe2O4 (CFO). The membranes were fabricated from mixtures of Nano-powder of each of the phases for different volume percentages, sintered with various temperatures and sintering time to form systematic micro-structural variations, and characterized by structural analysis (XRD), and micro-structural analysis (SEM-EDS). Performance of the membranes was tested for variable partial pressures of oxygen across the membrane at temperatures from 850°C-1060°C using a Gas Chromatography (GC) system. Permeated oxygen did not directly correlate with change in percent mixture. An intermediate mixture 60%GDC-40%CFO had the highest flux compared to the 50%GDC

  7. Interface proximity effects on ionic conductivity in nanoscale oxide-ion conducting yttria stabilized zirconia: an atomistic simulation study.

    PubMed

    Sankaranarayanan, Subramanian K R S; Ramanathan, Shriram

    2011-02-14

    We present an atomistic simulation study on the size dependence of dopant distribution and the influence of nanoscale film thickness on carrier transport properties of the model oxide-ion conductor yttria stabilized zirconia (YSZ). Simulated amorphization and recrystallization approach was utilized to generate YSZ films with varying thicknesses (3-9 nm) on insulating MgO substrates. The atomic trajectories generated in the molecular dynamics simulations are used to study the structural evolution of the YSZ thin films and correlate the resulting microstructure with ionic transport properties at the nanoscale. The interfacial conductivity increases by 2 orders of magnitude as the YSZ film size decreases from 9 to 3 nm owing to a decrease in activation energy barrier from 0.54 to 0.35 eV in the 1200-2000 K temperature range. Analysis of dopant distribution indicates surface enrichment, the extent of which depends on the film thickness. The mechanisms of oxygen conductivity for the various film thicknesses at the nanoscale are discussed in detail and comparisons with experimental and other modeling studies are presented where possible. The study offers insights into mesoscopic ion conduction mechanisms in low-dimensional solid oxide electrolytes.

  8. Enhancement of ionic conductivity of PEO based polymer electrolyte by the addition of nanosize ceramic powders.

    PubMed

    Wang, G X; Yang, L; Wang, J Z; Liu, H K; Dou, S X

    2005-07-01

    The ionic conductivity of polyethylene oxide (PEO) based solid polymer electrolytes (SPEs) has been improved by the addition of nanosize ceramic powders (TiO2 and AL2O3). The PEO based solid polymer electrolytes were prepared by the solution-casting method. Electrochemical measurement shows that the 10 wt% TiO2 PEO-LiClO4 polymer electrolyte has the best ionic conductivity (about 10(-4) S cm(-1) at 40-60 degrees C). The lithium transference number of the 10 wt% TiO2 PEO-LiClO4 polymer electrolyte was measured to be 0.47, which is much higher than that of bare PEO polymer electrolyte. Ac impedance testing shows that the interface resistance of ceramic-added PEO polymer electrolyte is stable. Linear sweep voltammetry measurement shows that the PEO polymer electrolytes are electrochemically stable in the voltage range of 2.0-5.0 V versus a Li/Li+ reference electrode.

  9. Ionic conductivity in a quantum lattice gas model with three-particle interactions

    NASA Astrophysics Data System (ADS)

    Barry, J. H.; Muttalib, K. A.; Tanaka, T.

    2012-12-01

    A system of mesoscopic ions with dominant three-particle interactions is modeled by a quantum lattice liquid on the planar kagomé lattice. The two-parameter Hamiltonian contains localized attractive triplet interactions as potential energy and nearest neighbor hopping-type terms as kinetic energy. The dynamic ionic conductivity σ(ω) is theoretically investigated for ‘weak hopping’ via a quantum many-body perturbation expansion of the thermal (Matsubara) Green function (current-current correlation). A simple analytic continuation and mapping of the thermal Green function provide the temporal Fourier transform of the physical retarded Green function in the Kubo formula. Substituting pertinent exact solutions for static multi-particle correlations known from previous work, Arrhenius relations are revealed in zeroth-order approximation for the dc ionic conductivity σdc along special trajectories in density-temperature space. The Arrhenius plots directly yield static activation energies along the latter loci. Experimental possibilities relating to σdc are discussed in the presence of equilibrium aggregation. This article is part of ‘Lattice models and integrability’, a special issue of Journal of Physics A: Mathematical and Theoretical in honour of F Y Wu's 80th birthday.

  10. Bombardment induced ion transport - part IV: ionic conductivity of ultra-thin polyelectrolyte multilayer films.

    PubMed

    Wesp, Veronika; Hermann, Matthias; Schäfer, Martin; Hühn, Jonas; Parak, Wolfgang J; Weitzel, Karl-Michael

    2016-02-14

    The dependence of the ionic conductance of ultra-thin polyelectrolyte multilayer (PEM) films on the temperature and the number of bilayers has been investigated by the recently developed low energy bombardment induced ion transport (BIIT) method. To this end multilayers of alternating poly(sodium 4-styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) layers were deposited on a metal electrode and subsequently bombarded by a low energy potassium ion beam. Ions are transported through the film according to the laws of electro-diffusion towards a grounded backside electrode. They are neutralized at the interface between the polymer film and the metal electrode. The detected neutralization current scales linearly with the acceleration potential of the ion beam indicating Ohmic behavior for the (PAH/PSS)x multilayer, where x denotes the number of bilayers. The conductance exhibits a non-monotonic dependence on the number of bilayers, x. For 2 ≤ x ≤ 8 the conductance increases non-linearly with the number of bilayers. For x ≥ 8 the conductance decreases with increasing number of bilayers. The variation of the conductance is rationalized by a model accounting for the structure dependence of the conductivity. The thinnest sample for which the conductance has been measured is the single bilayer reflecting properties dominated by the interface. The activation energy for the ion transport is 0.49 eV.

  11. Fundamentals of ionic conductivity relaxation gained from study of procaine hydrochloride and procainamide hydrochloride at ambient and elevated pressure

    NASA Astrophysics Data System (ADS)

    Wojnarowska, Z.; Swiety-Pospiech, A.; Grzybowska, K.; Hawelek, L.; Paluch, M.; Ngai, K. L.

    2012-04-01

    The pharmaceuticals, procaine hydrochloride and procainamide hydrochloride, are glass-forming as well as ionically conducting materials. We have made dielectric measurements at ambient and elevated pressures to characterize the dynamics of the ion conductivity relaxation in these pharmaceuticals, and calorimetric measurements for the structural relaxation. Perhaps due to their special chemical and physical structures, novel features are found in the ionic conductivity relaxation of these pharmaceuticals. Data of conductivity relaxation in most ionic conductors when represented by the electric loss modulus usually show a single resolved peak in the electric modulus loss M″(f ) spectra. However, in procaine hydrochloride and procainamide hydrochloride we find in addition another resolved loss peak at higher frequencies over a temperature range spanning across Tg. The situation is analogous to many non-ionic glass-formers showing the presence of the structural α-relaxation together with the Johari-Goldstein (JG) β-relaxation. Naturally the analogy leads us to name the slower and faster processes resolved in procaine hydrochloride and procainamide hydrochloride as the primary α-conductivity relaxation and the secondary β-conductivity relaxation, respectively. The analogy of the β-conductivity relaxation in procaine HCl and procainamide HCl with JG β-relaxation in non-ionic glass-formers goes further by the finding that the β-conductivity is strongly related to the α-conductivity relaxation at temperatures above and below Tg. At elevated pressure but compensated by raising temperature to maintain α-conductivity relaxation time constant, the data show invariance of the ratio between the β- and the α-conductivity relaxation times to changes of thermodynamic condition. This property indicates that the β-conductivity relaxation has fundamental importance and is indispensable as the precursor of the α-conductivity relaxation, analogous to the relation found

  12. Local Structural Investigations, Defect Formation, and Ionic Conductivity of the Lithium Ionic Conductor Li 4 P 2 S 6

    SciTech Connect

    Dietrich, Christian; Sadowski, Marcel; Sicolo, Sabrina; Weber, Dominik A.; Sedlmaier, Stefan J.; Weldert, Kai S.; Indris, Sylvio; Albe, Karsten; Janek, Jürgen; Zeier, Wolfgang G.

    2016-12-13

    Glassy, glass–ceramic, and crystalline lithium thiophosphates have attracted interest in their use as solid electrolytes in all-solid-state batteries. Despite similar structural motifs, including PS43–, P2S64–, and P2S74– polyhedra, these materials exhibit a wide range of possible compositions, crystal structures, and ionic conductivities. Here, we present a combined approach of Bragg diffraction, pair distribution function analysis, Raman spectroscopy, and 31P magic angle spinning nuclear magnetic resonance spectroscopy to study the underlying crystal structure of Li4P2S6. In this work, we show that the material crystallizes in a planar structural arrangement as a glass ceramic composite, explaining the observed relatively low ionic conductivity, depending on the fraction of glass content. Calculations based on density functional theory provide an understanding of occurring diffusion pathways and ionic conductivity of this Li+ ionic conductor.

  13. Enhanced ionic conduction and disproportionation in pure CuCl at high pressure

    NASA Astrophysics Data System (ADS)

    Batlogg, B.; Remeika, J. P.; Maines, R. G.

    1981-04-01

    The optical and electrical properties of pure cuprous chloride (CuCl) single crystals have been studied under pressure up to 12 GPa. The transition pressures for the three crystallographic phases have been determined as 5.1 ± 0.1 GPa (ZnS → tetragonal) and 8.8 ± 0.4 GPa (tetrag.-NaCl). During the transition at 5.1 GPa, where the coordination number changes, the formation of cupric ions is observed. This is interpreted as a result of a partial, transient, and reversible disproportionation. In the ZnS and NaCl phase, an enhanced ionic conductivity is found following the first transformation into the tetragonal structure. The concentration of the mobile ions is typically 10 18 cm -3 and their diffusivity is ˜ 4×10 -7 cm 2s -1. An applied voltage in excess of 0.7 V causes anodic oxidation of Cu + which mimics much higher conductivity.

  14. Screening for High Conductivity/Low Viscosity Ionic Liquids Using Product Descriptors

    DOE PAGES

    Martin, Shawn; Pratt, III, Harry D.; Anderson, Travis M.

    2017-02-21

    We seek to optimize Ionic liquids (ILs) for application to redox flow batteries. As part of this effort, we have developed a computational method for suggesting ILs with high conductivity and low viscosity. Since ILs consist of cation-anion pairs, we consider a method for treating ILs as pairs using product descriptors for QSPRs, a concept borrowed from the prediction of protein-protein interactions in bioinformatics. We demonstrate the method by predicting electrical conductivity, viscosity, and melting point on a dataset taken from the ILThermo database on June 18th, 2014. The dataset consists of 4,329 measurements taken from 165 ILs made upmore » of 72 cations and 34 anions. In conclusion, we benchmark our QSPRs on the known values in the dataset then extend our predictions to screen all 2,448 possible cation-anion pairs in the dataset.« less

  15. Investigation of ionic conductivity of lanthanum cerium oxide nano crystalline powder synthesized by co precipitation method

    NASA Astrophysics Data System (ADS)

    Tinwala, Hozefa; Shah, Patij; Siddhapara, Kirit; Shah, Dimple; Menghani, Jyoti

    2016-10-01

    Lanthanum (La) doped Ceria (CeO2) electrolyte has attracted considerable interest, as a candidate material for solid oxide fuel cells (SOFCs). The ionic conductivity of La doped CeO2 system (La2Ce2O7) nano-particles synthesized by the co-precipitation method has been investigated. The cubic fluorite structure was observed from the structural analysis of the material. Morphology of the sintered pellets are observed by scanning electron microscope (SEM), respectively. From the results of impedance spectroscopy from temperature range of room temperature to 400 °C, the oxide ion conductivity due to proton charge carrier was observed. Thermogravimetric analysis (TGA) was performed on the material to check stability of phase at high temperature.

  16. Protein Kinase C Regulates Ionic Conductance in Hippocampal Pyramidal Neurons: Electrophysiological Effects of Phorbol Esters

    NASA Astrophysics Data System (ADS)

    Baraban, Jay M.; Snyder, Solomon H.; Alger, Bradley E.

    1985-04-01

    The vertebrate central nervous system contains very high concentrations of protein kinase C, a calcium-and phospholipid-stimulated phosphorylating enzyme. Phorbol esters, compounds with inflammatory and tumor-promoting properties, bind to and activate this enzyme. To clarify the role of protein kinase C in neuronal function, we have localized phorbol ester receptors in the rat hippocampus by autoradiography and examined the electrophysiological effects of phorbol esters on hippocampal pyramidal neurons in vitro. Phorbol esters blocked a calcium-dependent potassium conductance. In addition, phorbol esters blocked the late hyperpolarization elicited by synaptic stimulation even though other synaptic potentials were not affected. The potencies of several phorbol esters in exerting these actions paralleled their affinities for protein kinase C, suggesting that protein kinase C regulates membrane ionic conductance.

  17. Ionic limiting molar conductivity calculation of Li-ion battery electrolyte based on mode coupling theory.

    PubMed

    He, Xiangming; Pu, Weihua; Han, Jingli; Chen, Jian; Lu, Jiufang; Jiang, Changyin; Wan, Chunrong

    2005-12-15

    A method is proposed based on mode coupling theory in which the ion transference number is introduced into the theory. The ionic limiting molar conductivities of LiPF6, LiClO4, LiBF4, LiCF3SO3, Li(CF3SO3)2N, LiC4F9SO3, and LiAsF6 in PC(propylene carbonate), GBL(gamma-butyrolactone), PC(propylene carbonate)/EMC(ethylmethyl carbonate), and PC(propylene carbonate)/DME(dimethoxyethane) are calculated based on this method, which does not involve any adjustable parameter. The results fit well to the literature data which are calculated by an empirically adjusted formula. This presents a potential way to calculate the conductivities of Li-ion battery electrolytes.

  18. Anomalous Electrical Conductivity Behavior at Elevated Pressure in the Protic Ionic Liquid Procainamide Hydrochloride

    NASA Astrophysics Data System (ADS)

    Wojnarowska, Z.; Roland, C. M.; Swiety-Pospiech, A.; Grzybowska, K.; Paluch, M.

    2012-01-01

    Using broadband dielectric spectroscopy, we investigated the effect of hydrostatic pressure on the conductivity relaxation time τσ of the supercooled protic ionic liquid, procainamide hydrochloride, a common pharmaceutical. The pressure dependence of τσ exhibited anomalous behavior in the vicinity of the glass transition Tg, manifested by abrupt changes in activation volume. This peculiar behavior, paralleling the change in temperature dependence of τσ near Tg, is a manifestation of the decoupling between electrical conductivity and structural relaxation. Although the latter effectively ceases in the glassy state, free ions retain their mobility but with a reduced sensitivity to thermodynamic changes. This is the first observation of decoupling of ion migration from structural relaxation in a glassy conductor by isothermal densification.

  19. Electrochemically oxidized electronic and ionic conducting nanostructured block copolymers for lithium battery electrodes.

    PubMed

    Patel, Shrayesh N; Javier, Anna E; Balsara, Nitash P

    2013-07-23

    Block copolymers that can simultaneously conduct electronic and ionic charges on the nanometer length scale can serve as innovative conductive binder material for solid-state battery electrodes. The purpose of this work is to study the electronic charge transport of poly(3-hexylthiophene)-b-poly(ethylene oxide) (P3HT-PEO) copolymers electrochemically oxidized with lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt in the context of a lithium battery charge/discharge cycle. We use a solid-state three-terminal electrochemical cell that enables simultaneous conductivity measurements and control over electrochemical doping of P3HT. At low oxidation levels (ratio of moles of electrons removed to moles of 3-hexylthiophene moieties in the electrode), the electronic conductivity (σe,ox) increases from 10(-7) S/cm to 10(-4) S/cm. At high oxidation levels, σe,ox approaches 10(-2) S/cm. When P3HT-PEO is used as a conductive binder in a positive electrode with LiFePO4 active material, P3HT is electrochemically active within the voltage window of a charge/discharge cycle. The electronic conductivity of the P3HT-PEO binder is in the 10(-4) to 10(-2) S/cm range over most of the potential window of the charge/discharge cycle. This allows for efficient electronic conduction, and observed charge/discharge capacities approach the theoretical limit of LiFePO4. However, at the end of the discharge cycle, the electronic conductivity decreases sharply to 10(-7) S/cm, which means the "conductive" binder is now electronically insulating. The ability of our conductive binder to switch between electronically conducting and insulating states in the positive electrode provides an unprecedented route for automatic overdischarge protection in rechargeable batteries.

  20. Parasitic Currents Caused by Different Ionic and Electronic Conductivities in Fuel Cell Anodes.

    PubMed

    Schalenbach, Maximilian; Zillgitt, Marcel; Maier, Wiebke; Stolten, Detlef

    2015-07-29

    The electrodes in fuel cells simultaneously realize electric and ionic conductivity. In the case of acidic polymer electrolytes, the electrodes are typically made of composites of carbon-supported catalyst and Nafion polymer electrolyte binder. In this study, the interaction of the proton conduction, the electron conduction, and the electrochemical hydrogen conversion in such composite electrode materials was examined. Exposed to a hydrogen atmosphere, these composites displayed up to 10-fold smaller resistivities for the proton conduction than that of Nafion membranes. This effect was ascribed to the simultaneously occurring electrochemical hydrogen oxidation and evolution inside the composite samples, which are driven by different proton and electron resistivities. The parasitic electrochemical currents resulting were postulated to occur in the anode of fuel cells with polymer, solid oxide, or liquid alkaline electrolytes, when the ohmic drop of the ion conduction in the anode is higher with the anodic kinetic overvoltage (as illustrated in the graphical abstract). In this case, the parasitic electrochemical currents increase the anodic kinetic overpotential and the ohmic drop in the anode. Thinner fuel cell anodes with smaller ohmic drops for the ion conduction may reduce the parasitic electrochemical currents.

  1. Ionic Conductivity of Nanostructured Block Copolymer Electrolytes in the Low Molecular Weight Limit

    NASA Astrophysics Data System (ADS)

    Teran, Alexander; Yuan, Rodger; Gurevitch, Inna; Balsara, Nitash

    2013-03-01

    Nanostructured block copolymer electrolytes containing an ion-conducting block and a modulus-strengthening block are of interest for applications in solid-state lithium metal batteries. Previous work using symmetric polystyrene-block-poly(ethylene oxide) mixed with a lithium salt has demonstrated that the ionic conductivity increases with increasing molecular weight of the poly(ethylene oxide) block in the high molecular weight regime due to an increase in the width of the conducting channel. Our current study extends the previous work to the low molecular weight limit. Small angle X-ray scattering, differential scanning calorimetry, and ac impedance spectroscopy experiments help identify the opposing forces influencing the conductivity in these materials. We also examine the annealing process for these materials, whose ion transport characteristics are well known to be influenced by sample preparation and thermal history. The conductivity appears to be influenced by the conductive channel width as well as the glass transition temperature of the insulating block, which also plays an important role in the annealing process.

  2. Syntheses, structures, and ionic conductivities of perovskite-structured lithium–strontium–aluminum/gallium–tantalum-oxides

    SciTech Connect

    Phraewphiphat, Thanya; Iqbal, Muhammad; Suzuki, Kota; Matsuda, Yasuaki; Yonemura, Masao; Hirayama, Masaaki; Kanno, Ryoji

    2015-05-15

    The ionic conductivities of new perovskite-structured lithium–strontium–aluminum/gallium–tantalum oxides were investigated. Solid solutions of the new perovskite oxides, (Li{sub x}Sr{sub 1−x})(Al{sub (1−x)/2}Ta{sub (1+x)/2})O{sub 3} and (Li{sub x}Sr{sub 1−x})(Ga{sub (1−x)/2}Ta{sub (1+x)/2})O{sub 3}, were synthesized using a ball-milled-assisted solid-state method. The partial substitution of the smaller Ga{sup +3} for Ta{sup +5} resulted in new compositions, the structures of which were determined by neutron diffraction measurements using a cubic perovskite structural model with the Pm−3m space group. Vacancies were introduced into the Sr(Li) sites by the formation of solid solutions with compositions (Li{sub x}Sr{sub 1−x−y}☐{sub y})(Ga{sub [(1−x)/2]−y}Ta{sub [(1+x)/2]+y})O{sub 3}, where the composition range of 0≤y≤0.20 was examined for x=0.2 and 0.25. The highest conductivity, 1.85×10{sup −3} S cm{sup −1} at 250 °C, was obtained for (Li{sub 0.25}Sr{sub 0.625}☐{sub 0.125})(Ga{sub 0.25}Ta{sub 0.75})O{sub 3} (x=0.25, y=0.125). Enhanced ionic conductivities were achieved by the introduction of vacancies at the A-sites. - Graphical abstract: Novel lithium-conducting oxides with the cubic perovskite structure (Li{sub x}Sr{sub 1−x−y}☐{sub y})(Ga{sub [(1−x)/2]−y}Ta{sub [(1+x)/2]+y})O{sub 3} provide a specific solid-solution region with various x and y values, exhibiting the highest ionic conductivity (1.85 S cm{sup −1} at 250 °C) for (Li{sub 0.25}Sr{sub 0.625}☐{sub 0.125})(Ga{sub 0.25}Ta{sub 0.75})O{sub 3} (x=0.25, y=0.125 in (Li{sub x}Sr{sub 1−x−y}☐{sub y})(Ga{sub [(1−x)/2]−y}Ta{sub [(1+x)/2]+y})O{sub 3}). The vacancies (☐) introduced into the A-sites contribute to the enhancement of lithium diffusion in the perovskite structure because of the enlargement of the bottleneck size and suppression of the interaction between lithium and oxygen. - Highlights: • The perovskite-structured novel Li

  3. Phase Behavior and Conductivity of Phosphonated Block Copolymers Containing Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Jung, Ha Young; Kim, Sung Yeon; Park, Moon Jeong

    2015-03-01

    As the focus on proton exchange fuel cells continues to escalate in the era of alternative energy systems, the rational design of sulfonated polymers has emerged as a key technique for enhancing device efficiency. While the sulfonic acid group guarantees high proton conductivity of membranes under humidified conditions, the growing need for high temperature operation has discouraged their practical uses in fuel cells. In this respect, phosphonated polymers have drawn intensive attention in recent years owing to their self-dissociation ability. In this study, we have synthesized a set of phosphonated block copolymers, poly(styrenephosphonate-methylbutylene) (PSP- b - PMB), by varying phosphonation level (PL). A wide variety of self-assembled morphologies, i.e., disordered, lamellar, hexagonally perforated lamellae and hexagonally packed cylindrical phases, were observed with PL. Remarkably, upon comparing the morphology of PSP- b-PMB and that of sulfonated analog, we found distinctly dissimilar domain sizes at the same molecular weight and composition. A range of ionic liquids (ILs) were incorporated into the PSP- b-PMB block copolymers and their ion transport properties were examined. It has been revealed that the degree of confinement of ionic phases (domain size) impacts the ion mobility and proton dissociation efficiency of IL-containing polymers.

  4. Mechanical strength and ionic conductivity of polymer electrolyte membranes prepared from cellulose acetate-lithium perchlorate

    NASA Astrophysics Data System (ADS)

    Sudiarti, T.; Wahyuningrum, D.; Bundjali, B.; Made Arcana, I.

    2017-07-01

    The need for secondary batteries is increasing every year. The secondary battery using a liquid electrolyte has some weaknesses. A solid polymer electrolyte is the alternative electrolytes developed to replace the liquid electrolyte type. This study was conducted to determine the effect of lithium perchlorate content on the polymer electrolyte membranes of cellulose acetate-LiClO4. The cellulose acetate-LiClO4 membranes were prepared by mixing cellulose acetate and LiClO4 in various compositions using tetrahydrofurane (THF) as solvent. The effect of LiClO4 ratios on the polymer electrolyte membranes was studied by analysis of the functional groups using FTIR (Fourier Transform Infrared) spectroscopy measurement, the ionic conductivity by EIS (Electrochemical Impedance Spectroscopy) method, and mechanical properties by tensile tester measurements. The ionic conductivity of the membranes increased with the increasing in the ratios of lithium perchlorate content in the membranes and reached the optimum value at 1.79×10-4 S cm-1 corresponded to the cellulose acetate doped with 25% (w/w) LiClO4 membrane. The presence of 10% (w/w) LiClO4 content within cellulose acetate membranes can increase the mechanical properties of the membranes from 19.89 to 43.29 MPa for tensile strength, and from 2.55 to 4.53% for elongation at break. However, when the cellulose acetate membranes containing ratio of LiClO4 more than 10% (w/w), consequently the tensile strength tended to decrease and the elongation at break was increased.

  5. AC and DC conductivity of ionic liquid containing polyvinylidene fluoride thin films

    NASA Astrophysics Data System (ADS)

    Frübing, Peter; Wang, Feipeng; Kühle, Till-Friedrich; Gerhard, Reimund

    2016-01-01

    Polarisation processes and charge transport in polyvinylidene fluoride (PVDF) with a small amount (0.01-10 wt%) of the ionic liquid (IL) 1-ethyl-3-methylimidazolium nitrate ({[EMIM]}^+[{NO}_3]^-) are investigated by means of dielectric spectroscopy. The response of PVDF that contains more than 0.01 wt% IL is dominated by a low-frequency relaxation which shows typical signatures of electrode polarisation. Furthermore, the α a relaxation, related to the glass transition, disappears for IL contents of more than 1 wt%, which indicates that the amorphous phase loses its glass-forming properties and undergoes structural changes. The DC conductivity is determined from the low-frequency limit of the AC conductivity and from the dielectric loss peak related to the electrode polarisation. DC conductivities of 10^{-10} to 10^{-2} {S}/{m} are obtained—increasing with IL content and temperature. The dependence of the DC conductivity on the IL content follows a power law with an exponent greater than one, indicating an increase in the ion mobility. The temperature dependence of the DC conductivity shows Vogel-Fulcher-Tammann behaviour, which implies that charge transport is coupled to polymer chain motion. Mobile ion densities and ion mobilities are calculated from the DC conductivity and the dielectric loss related to electrode polarisation, with the results that less than one per cent of the total ion concentration contributes to the conductivity and that the strong increase in conductivity with temperature is mainly caused by a strong increase in ion mobility. This leads to the conclusion that in particular the ion mobility must be reduced in order to decrease the DC conductivity.

  6. Tunable ionic-conductivity of collapsed Sandia octahedral molecular sieves (SOMS).

    SciTech Connect

    Pless, Jason; Nenoff, Tina Maria; Garino, Terry J.; Axness, Marlene

    2006-11-01

    This proposal focuses on the synthesis and characterization of ''tunable'' perovskite ceramics with resulting controlled strength and temperature of dielectric constants and/or with ionic conductivity. Traditional methods of synthesis involve high temperature oxide mixing and baking. We developed a new methodology of synthesis involving the (1) low temperature hydrothermal synthesis of metastable porous phases with ''tuned'' stoichiometry, and element types, and then (2) low temperature heat treatment to build exact stoichiometry perovskites, with the desired vacancy concentrations. This flexible pathway can lead to compositions and structures not attainable by conventional methods. During the course of this program, a series of Na-Nb perovskites were synthesized by calcining and collapsing microporous Sandia Octahedral Molecular Sieve (SOMS) phases. These materials were studied by various characterization techniques and conductivity measurements to better delineate stability and stoichiometry/bulk conductivity relationships. The conductivity can be altered by changing the concentration and type of the substituting framework cation(s) or by ion exchange of sodium. To date, the Na{sub 0.9}Mg{sub 0.1}Nb{sub 0.8}Ti{sub 0.2}O{sub 3-{delta}} shows the best conductivity.

  7. Engineering Biodegradable and Biocompatible Bio-ionic Liquid Conjugated Hydrogels with Tunable Conductivity and Mechanical Properties.

    PubMed

    Noshadi, Iman; Walker, Brian W; Portillo-Lara, Roberto; Shirzaei Sani, Ehsan; Gomes, Nayara; Aziziyan, Mohammad Reza; Annabi, Nasim

    2017-06-28

    Conventional methods to engineer electroconductive hydrogels (ECHs) through the incorporation of conductive nanomaterials and polymers exhibit major technical limitations. These are mainly associated with the cytotoxicity, as well as poor solubility, processability, and biodegradability of their components. Here, we describe the engineering of a new class of ECHs through the functionalization of non-conductive polymers with a conductive choline-based bio-ionic liquid (Bio-IL). Bio-IL conjugated hydrogels exhibited a wide range of highly tunable physical properties, remarkable in vitro and in vivo biocompatibility, and high electrical conductivity without the need for additional conductive components. The engineered hydrogels could support the growth and function of primary cardiomyocytes in both two dimentinal (2D) and three dimensional (3D) cultures in vitro. Furthermore, they were shown to be efficiently biodegraded and possess low immunogenicity when implanted subcutaneously in rats. Taken together, our results suggest that Bio-IL conjugated hydrogels could be implemented and readily tailored to different biomedical and tissue engineering applications.

  8. Ceramic membranes for catalytic membrane reactors with high ionic conductivities and low expansion properties

    DOEpatents

    Mackay, Richard; Sammells, Anthony F.

    2000-01-01

    Ceramics of the composition: Ln.sub.x Sr.sub.2-x-y Ca.sub.y B.sub.z M.sub.2-z O.sub.5+.delta. where Ln is an element selected from the fblock lanthanide elements and yttrium or mixtures thereof; B is an element selected from Al, Ga, In or mixtures thereof; M is a d-block transition element of mixtures thereof; 0.01.ltoreq.x.ltoreq.1.0; 0.01.ltoreq.y.ltoreq.0.7; 0.01.ltoreq.z.ltoreq.1.0 and .delta. is a number that varies to maintain charge neutrality are provided. These ceramics are useful in ceramic membranes and exhibit high ionic conductivity, high chemical stability under catalytic membrane reactor conditions and low coefficients of expansion. The materials of the invention are particularly useful in producing synthesis gas.

  9. Block copolymer with simultaneous electric and ionic conduction for use in lithium ion batteries

    DOEpatents

    Javier, Anna Esmeralda K; Balsara, Nitash Pervez; Patel, Shrayesh Naran; Hallinan, Jr., Daniel T

    2013-10-08

    Redox reactions that occur at the electrodes of batteries require transport of both ions and electrons to the active centers. Reported is the synthesis of a block copolymer that exhibits simultaneous electronic and ionic conduction. A combination of Grignard metathesis polymerization and click reaction was used successively to synthesize the block copolymer containing regioregular poly(3-hexylthiophene) (P3HT) and poly(ethylene oxide) (PEO) segments. The P3HT-PEO/LiTFSI mixture was then used to make a lithium battery cathode with LiFePO.sub.4 as the only other component. All-solid lithium batteries of the cathode described above, a solid electrolyte and a lithium foil as the anode showed capacities within experimental error of the theoretical capacity of the battery. The ability of P3HT-PEO to serve all of the transport and binding functions required in a lithium battery electrode is thus demonstrated.

  10. Ionic Conductivities of Molten CuI and AgI-CuI Mixtures

    NASA Astrophysics Data System (ADS)

    Tahara, Shuta; Shimakura, Hironori; Ohno, Satoru; Fukami, Takanori

    2017-08-01

    Ionic conductivities σ for molten CuI and AgI-CuI mixtures were measured in the temperature ranges of approximately 580-800 and 500-850 °C, respectively. The value of σ for molten CuI in the range is smaller than that for molten CuBr and CuCl. σ for molten AgI-CuI mixtures decreases with increasing CuI-concentration. The activation energies Ea for molten AgI-CuI system were determined from the analysis of temperature dependence of σ by using the by Arrhenius type equation. Ea for molten AgI-CuI gradually increase with increasing CuIconcentration.

  11. Conductive Hybrid Crystal Composed from Polyoxomolybdate and Deprotonatable Ionic-Liquid Surfactant

    PubMed Central

    Kobayashi, Jun; Kawahara, Ryosuke; Uchida, Sayaka; Koguchi, Shinichi; Ito, Takeru

    2016-01-01

    A polyoxomolybdate inorganic-organic hybrid crystal was synthesized with deprotonatable ionic-liquid surfactant. 1-dodecylimidazolium cation was employed for its synthesis. The hybrid crystal contained δ-type octamolybdate (Mo8) isomer, and possessed alternate stacking of Mo8 monolayers and interdigitated surfactant bilayers. The crystal structure was compared with polyoxomolybdate hybrid crystals comprising 1-dodecyl-3-methylimidazolium surfactant, which preferred β-type Mo8 isomer. The less bulky hydrophilic moiety of the 1-dodecylimidazolium interacted with the δ-Mo8 anion by N–H···O hydrogen bonds, which presumably induced the formation of the δ-Mo8 anion. Anhydrous conductivity of the hybrid crystal was estimated to be 5.5 × 10−6 S·cm−1 at 443 K by alternating current (AC) impedance spectroscopy. PMID:27347926

  12. Conductive Hybrid Crystal Composed from Polyoxomolybdate and Deprotonatable Ionic-Liquid Surfactant.

    PubMed

    Kobayashi, Jun; Kawahara, Ryosuke; Uchida, Sayaka; Koguchi, Shinichi; Ito, Takeru

    2016-06-23

    A polyoxomolybdate inorganic-organic hybrid crystal was synthesized with deprotonatable ionic-liquid surfactant. 1-dodecylimidazolium cation was employed for its synthesis. The hybrid crystal contained δ-type octamolybdate (Mo₈) isomer, and possessed alternate stacking of Mo₈ monolayers and interdigitated surfactant bilayers. The crystal structure was compared with polyoxomolybdate hybrid crystals comprising 1-dodecyl-3-methylimidazolium surfactant, which preferred β-type Mo₈ isomer. The less bulky hydrophilic moiety of the 1-dodecylimidazolium interacted with the δ-Mo₈ anion by N-H···O hydrogen bonds, which presumably induced the formation of the δ-Mo₈ anion. Anhydrous conductivity of the hybrid crystal was estimated to be 5.5 × 10(-6) S·cm(-1) at 443 K by alternating current (AC) impedance spectroscopy.

  13. Conductivity-viscosity-structure: unpicking the relationship in an ionic liquid.

    PubMed

    Salanne, Mathieu; Simon, Christian; Turq, Pierre; Madden, Paul A

    2007-05-10

    The relationships between the ionic mobility, the viscosity, and the atomic-scale structure are investigated in computer simulations of mixtures of LiF and the network glass-forming material BeF(2). The simulations span a wide range of compositions, across which the fluidity of the system changes greatly due to the break-up of the Be-F network by the addition of the LiF. The relationship between the conductivity and viscosity passes from that expected for independently diffusing ions in the dilute mixtures to strongly decoupled Li+ migration through a viscous network at higher concentrations. The transition between these régimes is linked to the changing local and intermediate-scale structure in the melts. The decoupling phenomenon is associated with the appearance of migration channels in the network which leads to cooperative effects in the Li+ migration.

  14. Three-dimensional ionic conduction in the strained electrolytes of solid oxide fuel cells

    SciTech Connect

    Han, Yupei; Zou, Minda; Lv, Weiqiang; He, Weidong; Mao, Yiwu; Wang, Wei

    2016-05-07

    Flexible power sources including fuel cells and batteries are the key to realizing flexible electronic devices with pronounced foldability. To understand the bending effects in these devices, theoretical analysis on three-dimensional (3-D) lattice bending is necessary. In this report, we derive a 3-D analytical model to analyze the effects of electrolyte crystal bending on ionic conductivity in flexible solid-state batteries/fuel cells. By employing solid oxide fuel cells as a materials' platform, the intrinsic parameters of bent electrolyte materials, including lattice constant, Young's modulus, and Poisson ratio, are evaluated. Our work facilitates the rational design of highly efficient flexible electrolytes for high-performance flexible device applications.

  15. Three-dimensional ionic conduction in the strained electrolytes of solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Han, Yupei; Zou, Minda; Lv, Weiqiang; Mao, Yiwu; Wang, Wei; He, Weidong

    2016-05-01

    Flexible power sources including fuel cells and batteries are the key to realizing flexible electronic devices with pronounced foldability. To understand the bending effects in these devices, theoretical analysis on three-dimensional (3-D) lattice bending is necessary. In this report, we derive a 3-D analytical model to analyze the effects of electrolyte crystal bending on ionic conductivity in flexible solid-state batteries/fuel cells. By employing solid oxide fuel cells as a materials' platform, the intrinsic parameters of bent electrolyte materials, including lattice constant, Young's modulus, and Poisson ratio, are evaluated. Our work facilitates the rational design of highly efficient flexible electrolytes for high-performance flexible device applications.

  16. Thermally conductive of nanofluid from surfactant doped polyaniline nanoparticle and deep eutectic ionic liquid

    NASA Astrophysics Data System (ADS)

    Siong, Chew Tze; Daik, Rusli; Hamid, Muhammad Azmi Abdul

    2014-09-01

    Nanofluid is a colloidal suspension of nano-size particles in a fluid. Spherical shape dodecylbenzenesulfonic acid doped polyaniline (DBSA-PANI) nanoparticles were synthesized via reverse micellar polymerization in isooctane with average size of 50 nm- 60 nm. The aim of study is to explore the possibility of using deep eutectic ionic liquid (DES) as a new base fluid in heat transfer application. DES was prepared by heating up choline chloride and urea with stirring. DES based nanofluids containing DBSA-PANI nanoparticles were prepared using two-step method. Thermal conductivity of nanofluids was measured using KD2 Pro Thermal Properties Analyzer. When incorporated with DBSA-PANI nanoparticles, DES with water was found to exhibit a bigger increase in thermal conductivity compared to that of the pure DES. The thermal conductivity of DES with water was increased by 4.67% when incorporated with 0.2 wt% of DBSA-PANI nanoparticles at 50°C. The enhancement in thermal conductivity of DES based nanofluids is possibly related to Brownian motion of nanoparticles as well as micro-convection of base fluids and also interaction between dopants and DES ions.

  17. Ammonium based ionic liquids immobilized in large pore zeolites: Encapsulation procedures and proton conduction performance

    NASA Astrophysics Data System (ADS)

    Eguizábal, A.; Lemus, J.; Urbiztondo, M.; Moschovi, A. M.; Ntais, S.; Soler, J.; Pina, M. P.

    Ammonium based ionic liquids immobilized in Y (FAU framework code) and beta (BEA framework code) type zeolites by different solution methods have been comprehensively characterized for their potential applications as hydrophilic-conducting fillers for PEM. In particular (2-hydroxymethyl) trimethylammonium dimethyl phosphate (IL1) and N,N-dimethyl-N-(2-hydroxyethyl) ammonium bis(trifluoromethanesulfonyl) imide (IL2) encapsulated into commercial NaY (Si/Al = 1.5) and NH 4-BEA (Si/Al = 12.5) type zeolites have been investigated. X-ray diffraction, N 2 physisorption, TGA analysis, ATR-FTIR and Raman spectroscopy techniques have been used to assess about the goodness of the encapsulation procedures. Finally, A.C. impedance spectroscopy measurements of tablets prepared from PVDF/composite (1:9 wt. ratio) were performed in order to evaluate their conduction properties. The conduction properties of the composites as a function of temperature and water partial pressure have been finally chosen as analytical tool to define the best encapsulation procedure and IL/Z composite for PEMFCs applications. A possible conduction mechanism, where synergic-inhibition effects between ILs and H 2O molecules coupled to IL dragging by water desorption take place, is also presented.

  18. Three-dimensional numerical analysis of mixed ionic and electronic conducting cathode reconstructed by focused ion beam scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Matsuzaki, Katsuhisa; Shikazono, Naoki; Kasagi, Nobuhide

    2011-03-01

    Three-dimensional microstructure of mixed ionic and electronic conducting cathode, La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF6428), is obtained by a dual-beam focused ion beam-scanning electron microscope, and its overpotential is predicted by the lattice Boltzmann method. Gaseous, ionic and electronic transport equations coupled with electrochemical reaction at the gas/solid interface in the three-dimensional microstructure are solved with an assumption of local equilibrium in the solid oxide. The gas transport is modeled by the dusty gas model. The numerical simulation is conducted under the current density conditions of 0.01, 0.05, 0.1 and 0.2 A/cm2. Predicted cathode overpotentials agreed well with the experimental results. However, predicted overpotential was very large at O2 = 20%, T = 973 K and i = 0.2 A/cm2 case due to the decline of ionic conductivity at low oxygen partial pressure. Three-dimensional chemical potential and current vector distributions inside LSCF microstructure are presented. Ionic and electronic current stream lines are uniform and smooth, which indicates good ionic and electronic conductions as well as wide electrochemically active areas inside the LSCF microstructure. Present method will be an effective tool for investigating local oxygen potential field which affects local reactions, diffusions and physical properties of the MIEC cathodes.

  19. Relationships between resting conductances, excitability, and t-system ionic homeostasis in skeletal muscle.

    PubMed

    Fraser, James A; Huang, Christopher L-H; Pedersen, Thomas H

    2011-07-01

    Activation of skeletal muscle fibers requires rapid sarcolemmal action potential (AP) conduction to ensure uniform excitation along the fiber length, as well as successful tubular excitation to initiate excitation-contraction coupling. In our companion paper in this issue, Pedersen et al. (2011. J. Gen. Physiol. doi:10.1085/jgp.201010510) quantify, for subthreshold stimuli, the influence upon both surface conduction velocity and tubular (t)-system excitation of the large changes in resting membrane conductance (G(M)) that occur during repetitive AP firing. The present work extends the analysis by developing a multi-compartment modification of the charge-difference model of Fraser and Huang to provide a quantitative description of the conduction velocity of actively propagated APs; the influence of voltage-gated ion channels within the t-system; the influence of t-system APs on ionic homeostasis within the t-system; the influence of t-system ion concentration changes on membrane potentials; and the influence of Phase I and Phase II G(M) changes on these relationships. Passive conduction properties of the novel model agreed with established linear circuit analysis and previous experimental results, while key simulations of AP firing were tested against focused experimental microelectrode measurements of membrane potential. This study thereby first quantified the effects of the t-system luminal resistance and voltage-gated Na(+) channel density on surface AP propagation and the resultant electrical response of the t-system. Second, it demonstrated the influence of G(M) changes during repetitive AP firing upon surface and t-system excitability. Third, it showed that significant K(+) accumulation occurs within the t-system during repetitive AP firing and produces a baseline depolarization of the surface membrane potential. Finally, it indicated that G(M) changes during repetitive AP firing significantly influence both t-system K(+) accumulation and its influence on the

  20. Enhancing oxygen transport through Mixed-Ionic-and-Electronic-Conducting ceramic membranes

    NASA Astrophysics Data System (ADS)

    Yu, Anthony S.

    Ceramic membranes based on Mixed-Ionic-and-Electronic-Conducting (MIEC) oxides are capable of separating oxygen from air in the presence of an oxygen partial-pressure gradient. These MIEC membranes show great promise for oxygen consuming industrial processes, such as the production of syngas from steam reforming of natural gas (SRM), as well as for electricity generation in Solid Oxide Fuel Cells (SOFC). For both applications, the overall performance is dictated by the rate of oxygen transport across the membrane. Oxygen transport across MIEC membranes is composed of a bulk oxygen-ion diffusion process and surface processes, such as surface reactions and adsorption/desorption of gaseous reactants/products. The main goal of this thesis was to determine which process is rate-limiting in order to significantly enhance the overall rate of oxygen transport in MIEC membrane systems. The rate-limiting step was determined by evaluating the total resistance to oxygen transfer, Rtot. Rtot is the sum of a bulk diffusion resistance in the membrane itself, Rb, and interfacial loss components, Rs. Rb is a function of the membrane's ionic conductivity and thickness, while Rs arises primarily from slow surface-exchange kinetics that cause the P(O2) at the surfaces of the membrane to differ from the P(O 2) in the adjacent gas phases. Rtot can be calculated from the Nernst potential across the membrane and the measured oxygen flux. The rate-limiting process can be determined by evaluating the relative contributions of the various losses, Rs and Rb, to Rtot. Using this method, this thesis demonstrates that for most membrane systems, Rs is the dominating factor. In the development of membrane systems with high oxygen transport rates, thin membranes with high ionic conductivities are required to achieve fast bulk oxygen-ion diffusion. However, as membrane thickness is decreased, surface reaction kinetics become more important in determining the overall transport rate. The two

  1. Tunable Mixed Ionic/Electronic Conductivity and Permittivity of Graphene Oxide Paper for Electrochemical Energy Conversion.

    PubMed

    Bayer, Thomas; Bishop, Sean R; Perry, Nicola H; Sasaki, Kazunari; Lyth, Stephen M

    2016-05-11

    Graphene oxide (GO) is a two-dimensional graphitic carbon material functionalized with oxygen-containing surface functional groups. The material is of interest in energy conversion, sensing, chemical processing, gas barrier, and electronics applications. Multilayer GO paper has recently been applied as a new proton conducting membrane in low temperature fuel cells. However, a detailed understanding of the electrical/dielectric properties, including separation of the ionic vs electronic contributions under relevant operating conditions, has so far been lacking. Here, the electrical conductivity and dielectric permittivity of GO paper are investigated in situ from 30 to 120 °C, and from 0 to 100% relative humidity (RH) using impedance spectroscopy. These are related to the water content, measured by thermogravimetric analysis. With the aid of electron blocking measurements, GO is demonstrated to be a mixed electronic-protonic conductor, and the ion transference number is derived for the first time. For RH > 40%, conductivity is dominated by proton transport (with a maximum of 0.5 mS/cm at 90 °C and 100% RH). For RH < 40%, electronic conductivity dominates (with a maximum of 7.4 mS/cm at ∼80 °C and 0% RH). The relative permittivity of GO paper increases with decreasing humidity, from ∼10 at 100% RH to several 1000 at 10% RH. These results underline the potential of GO for application not only as a proton conducting electrolyte but also as a mixed conducting electrode material under appropriate conditions. Such materials are highly applicable in electrochemical energy conversion and storage devices such as fuel cells and electrolyzers.

  2. Electrospinning of Ceramic Solid Electrolyte Nanowires for Lithium-Ion Batteries with Enhanced Ionic Conductivity

    NASA Astrophysics Data System (ADS)

    Yang, Ting

    Solid electrolytes have great potential to address the safety issues of Li-ion batteries, but better synthesis methods are still required for ceramics electrolytes such as lithium lanthanum titanate (LLTO) and lithium lanthanum zirconate (LLZO). Pellets made from ceramic nanopowders using conventional sintering can be porous due to the agglomeration of nanoparticles (NPs). Electrospinning is a simple and versatile technique for preparing oxide ceramic nanowires (NWs) and was used to prepare electrospun LLTO and LLZO NWs. Pellets prepared from the electrospun LLTO NWs had higher density, less void space, and higher Li+ conductivity compared to those comprised of LLTO prepared with conventional sol-gel methods, which demonstrated the potential that electrospinning can provide towards improving the properties of sol-gel derived ceramics. Cubic phase LLZO was stabilized at room temperature in the form of electrospun NWs without extrinsic dopants. Bulk LLZO with tetragonal structure was transformed to the cubic phase using particle size reduction via ball milling. Heating conditions that promoted particle coalescence and grain growth induced a transformation from the cubic to tetragonal phase in both types of nanostructured LLZO. Composite polymer solid electrolyte was fabricated using LLZO NWs as the filler and showed an improved ionic conductivity at room temperature. Nuclear magnetic resonance studies show that LLZO NWs partially modify the polymer matrix and create preferential pathways for Li+ conduction through the modified polymer regions. Doping did not have significant effect on improving the overall conductivity as the interfaces played a predominant role. By comparing fillers with different morphologies and intrinsic conductivities, it was found that both NW morphology and high intrinsic conductivity are desired.

  3. Characterization of electrical conduction and nature of charge carriers in mixed and ionic conductors

    NASA Astrophysics Data System (ADS)

    Geffroy, Pierre-Marie; Pons, Aénor; Béchade, Emilie; Masson, Olivier; Fouletier, Jacques

    2017-08-01

    The characterization of proton conduction leads to controversial data, often resulting from misinterpretation of the experimental measurements. All methods require the detection of minute variations in the hydrogen concentration in a flowing gas. Such analysis in a gas containing water vapor is a challenge. We propose a new setup allowing the measurement of P(O2), P(H2) and P(H2O). Two methods for determination of the transport numbers are used, i.e., the permeation and Faradaic efficiency methods. Two cases are considered in this study, i.e., a mixed conductor (mostly electronic conductor), i.e., palladium, and a purely ionic conductor, i.e., La9.6(SiO4)6O2.4 oxyapatite, which is an anionic conductor, though protonic conduction has been assumed in recent studies. This study clearly shows that La9.6(SiO4)6O2.4 oxyapatite is a pure anionic conductor, without contribution from protonic conduction, under usual conditions (1 atm., 475-615 °C).

  4. Ionic Conductivity of Poly(ethylene oxide)-Containing Block Copolymers at Order-Disorder and Order-Order Transitions

    NASA Astrophysics Data System (ADS)

    Wanakule, Nisita; Panday, Ashoutosh; Mullin, Scott; Balsara, Nitash

    2009-03-01

    The order-disorder transition (ODT) and order-order transition (OOT) of block copolymers with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salts are measured with a combination of small-angle x-ray scattering (SAXS) and birefringence. The block copolymers comprise of polyethylene oxide (PEO), a polymer with a higher dielectric constant that dissolves LiTFSI, and polystyrene (PS), a polymer with a lower dielectric constant that does not dissolve LiTFSI. Ionic conductivity of the block copolymers are measured through the observed ODT and OOT. The effect of morphology on the ionic conductivity will be presented and compared with literature results.

  5. Vibrational spectroscopy and ionic conductivity of polyethylene oxide-NaClO 4-CuO nanocomposite

    NASA Astrophysics Data System (ADS)

    Dey, Arup; Das, Kajari; Karan, S.; De, S. K.

    2011-12-01

    Structure, morphology and thermal properties of polyethylene oxide (PEO) with sodium perchlorate (NaClO 4) as electrolytic salt have been investigated by incorporating cupric monoxide (CuO) nanoparticles. Monoclinic CuO affects melting and glass transition temperatures of PEO-NaClO 4. Crystallinity and free ion concentration change with the variation of CuO concentration. The maximum ionic conductivity is observed for 10 wt.% CuO. Ionic conductivity follows Arrhenius type behavior as a function of temperature.

  6. Ionic conductivity of dual-phase polymer electrolytes comprised of NBR/SBR latex films swollen with lithium salt solutions

    SciTech Connect

    Matsumoto, Morihiko; Ichino, Toshihiro; Rutt, J.S.; Nishi, Shiro . NTT Interdisciplinary Research Lab.)

    1994-08-01

    Dual-phase polymer electrolytes (DPE) with high ionic conductivity and good mechanical strength were prepared by swelling poly(acrylonitrile-co-butadiene) rubber (NBR) and poly(styrene-co-butadiene) rubber (SBR) mixed latex films with lithium salt solutions (e.g., 1M LiClO[sub 4]/[gamma]-butyrolactone). The latex films retain particle morphology in the solid state. The NBR phase (formed from fused NBR latex particles) is polar and is impregnated selectively with polar lithium salt solutions, yielding ion-conductive channels, whereas the SBR phase (formed from fused SBR latex particles) is nonpolar and is not impregnated, providing a mechanically supportive matrix. The ionic conductivity of the DPE increased dramatically with increasing content of lithium salt solution, and higher amounts of solution were imbibed with increasing content of NBR relative to SBR. Several factors which affect the ionic conductivity of this system were examined, and the highest ionic conductivity (>10[sup [minus]3] S/cm) was obtained when either an NBR/SBR 70/30 (w/w) or a 50/50 (w/w) latex film was saturated with 1M LiClO[sub 4]/[gamma]-BL solution or 1M LiClO[sub 4]/[gamma]-BL/DME solution. Ion-conductive behavior changed critically with increasing lithium salt solution uptake. At low levels of lithium salt solution uptake, evidence suggested that ionic conductivity of the absorbed lithium salt solution was strongly influenced by the presence of the NBR in the ion-conductive channel, but at higher levels, the effects of the NBR were reduced and free'' lithium salt solution was present.

  7. Structure and ionic conductivity of well-aligned polycrystalline sodium titanogallate grown by reactive diffusion

    SciTech Connect

    Hasegawa, Ryo; Okabe, Momoko; Asaka, Toru; Ishizawa, Nobuo; Fukuda, Koichiro

    2015-09-15

    We prepared the b-axis-oriented polycrystalline Na{sub 0.85}Ti{sub 0.51}Ga{sub 4.37}O{sub 8} (NTGO) embedded in Ga{sub 2}O{sub 3}-doped Na{sub 2}Ti{sub 4}O{sub 9} matrix using the reactive diffusion technique. When the sandwich-type Ga{sub 2}TiO{sub 5}/NaGaO{sub 2}/Ga{sub 2}TiO{sub 5} diffusion couple was heated at 1323 K for 24 h, the NTGO polycrystal was readily formed in the presence of a liquid phase. The resulting polycrystalline material was characterized by X-ray diffractometry, electron microscopy and impedance spectroscopy. We mechanically processed the annealed diffusion couple and obtained the thin-plate electrolyte consisting mostly of the grain-aligned NTGO polycrystal. The ionic conductivity (σ) of the electrolyte along the common b-axis direction steadily increased from 1.3×10{sup −4} to 7.3×10{sup −3} S/cm as the temperature increased from 573 to 1073 K. There was a slope change at ca. 792 K for the Arrhenius plot of σ; the activation energies were 0.39 eV above this temperature and 0.57 eV below it. The NTGO showed the crystal structure (space group C2/m) with substantial positional disordering of one of the two Ga sites. The Na{sup +} ions occupied ca. 43% of the Wyckoff position 4i site, the deficiency of which would contribute to the relatively high ionic conductivity along the b-axis. The reactive diffusion could be widely applicable as the novel technique to the preparation of grain-aligned ceramics of multi-component systems. - Graphical abstract: We have prepared the b-axis-oriented Na{sub 0.85}Ti{sub 0.51}Ga{sub 4.37}O{sub 8} polycrystal embedded in Ga{sub 2}O{sub 3}-doped Na{sub 2}Ti{sub 4}O{sub 9} matrix by the heat treatment of sandwich-type diffusion couple of Ga{sub 2}TiO{sub 5}/NaGaO{sub 2}/Ga{sub 2}TiO{sub 5}. The resulting Na{sub 0.85}Ti{sub 0.51}Ga{sub 4.37}O{sub 8} electrolyte showed the ionic conductivity ranging from 1.3×10{sup −4} S/cm at 573 K to 7.3×10{sup −3} S/cm at 1073 K. - Highlights: • The b

  8. Mixed-Salt Effects on the Ionic Conductivity of Lithium-Doped PEO-Containing Block Copolymers

    SciTech Connect

    Young, Wen-Shiue; Albert, Julie N.L.; Schantz, A. Benjamin; Epps, III, Thomas H.

    2012-10-10

    We demonstrate a simple, yet effective, mixed-salt method to increase the room temperature ionic conductivity of lithium-doped block copolymer electrolyte membranes by suppressing the crystalline phases in the conducting block. We examined a mixed-salt system of LiClO{sub 4} and LiN(SO{sub 2}CF{sub 3}){sub 2} (LiTFSI) doped into a lamellae-forming poly(styrene-b-ethylene oxide) (PS-PEO) diblock copolymer. The domain spacings, morphologies, thermal behavior, and crystalline phases of salt-doped PS-PEO samples were characterized, and the ionic conductivities of block copolymer electrolytes were obtained through ac impedance measurements. Comparing the ionic conductivity profiles of salt-doped PS-PEO samples at different mixed-salt ratios and total salt concentrations, we found that the ionic conductivity at room temperature can be improved by more than an order of magnitude when coinhibition of crystallite growth is promoted by the concerted behavior of the PEO:LiClO{sub 4} and PEO:LiTFSI phases. Additionally, we examined the influence of mixed-salt ratio and total salt concentration on copolymer energetics, and we found that the slope of the effective interaction parameter ({chi}{sub eff}) vs salt concentration in our lamellae-forming PS-PEO system was lower than that reported for a cylinder-forming PS-PEO system due to the balance between chain stretching and salt segregation in the PEO domains.

  9. Mixed-salt Effects on the Ionic Conductivity of Lithium-doped PEO-containing Block Copolymers

    SciTech Connect

    W Young; J Albert; A Schantz; T Epps

    2011-12-31

    We demonstrate a simple, yet effective, mixed-salt method to increase the room temperature ionic conductivity of lithium-doped block copolymer electrolyte membranes by suppressing the crystalline phases in the conducting block. We examined a mixed-salt system of LiClO{sub 4} and LiN(SO{sub 2}CF{sub 3}){sub 2} (LiTFSI) doped into a lamellae-forming poly(styrene-b-ethylene oxide) (PS-PEO) diblock copolymer. The domain spacings, morphologies, thermal behavior, and crystalline phases of salt-doped PS-PEO samples were characterized, and the ionic conductivities of block copolymer electrolytes were obtained through ac impedance measurements. Comparing the ionic conductivity profiles of salt-doped PS-PEO samples at different mixed-salt ratios and total salt concentrations, we found that the ionic conductivity at room temperature can be improved by more than an order of magnitude when coinhibition of crystallite growth is promoted by the concerted behavior of the PEO:LiClO{sub 4} and PEO:LiTFSI phases. Additionally, we examined the influence of mixed-salt ratio and total salt concentration on copolymer energetics, and we found that the slope of the effective interaction parameter (x{sub eff}) vs salt concentration in our lamellae-forming PS-PEO system was lower than that reported for a cylinder-forming PS-PEO system due to the balance between chain stretching and salt segregation in the PEO domains.

  10. Effects of Sm doping content on the ionic conduction of CeO2 in SOFCs from first principles

    NASA Astrophysics Data System (ADS)

    Fu, Zhaoming; Sun, Qian; Ma, Dongwei; Zhang, Na; An, Yipeng; Yang, Zongxian

    2017-07-01

    Sm-doping effects on ionic conduction of the CeO2 electrolyte in solid oxide fuel cells (SOFCs) are investigated using the first-principles calculations. We focus on the influence of the Sm content on ionic conductivity in Sm-doped ceria (SDC). In previous studies, the Sm-doping effects are attributed to the increase in the oxygen vacancies induced by Sm3+. However, our investigations reveal that Sm doping contents play multiple roles in affecting the ionic conductivity. First, the activity of oxygen migration can be controlled by the Sm concentration. Second, the association energy between the dopant and oxygen vacancies, which is very important for O conductivity in SDC, can also be tuned by changing the dopant content. In addition, oxygen-rich and oxygen-poor conditions will significantly modify the band structures of SDC. Our work is helpful to understand the mechanism of high ionic conductivity in the electrolyte of Sm-doped ceria in SOFCs.

  11. Ionic Conductivity of Water-Soluble Fully Conjugated Heterocyclic Aromatic Polyelectrolytes

    NASA Astrophysics Data System (ADS)

    Bai, S. J.; Chen, Y. S.; Sun, J. P.; Dang, T. D.; Arnold, F. E.

    2002-03-01

    Fully conjugated poly[(1,7-dihydrobenzo[1,2-d:4,5-d']diimidazole-2,6-diyl)- 2-(2-sulfo)-p-phenylene], sPBI, has a para-catenated backbone. This rod-like polymer displays superior thermal and solvent stabilities. The stabilities hamper its processing for critical applications. Chemical derivative of the sPBI was achieved using pendants of propane-sulfonated Li^+ ionomer for a water-soluble polyelectrolyte, sPBI-PS(Li^+). sPBI-PS(Li^+) aqueous solutions were cast into freestanding films. Room-temperature direct current conductivity parallel to the film surface σ _|| was as high as 9.7 x 10-5 S/cm. Constant-voltage measurements indicated that σ _|| was mainly ionic. sPBI-PS(Li^+) doped with Li salts showed a σ _|| of 3 ~8 mS/cm. X-ray scattering revealed that the cast films were in-plane isotropic but out-of-the plane anisotropic with the rigid-rod backbone lying in the plane of the films. The anisotropic structure caused the conductivity transverse to the film surface was 10-3 ~ 10-4 to that of σ _||. Benzene-1,3,5-tricarboxylic acid with functional groups was added in the polycondensation reaction leading to heteroaromatic copolymer with fully conjugated but acticulated backbone. Cast films of the articulated copolymer had three-dimensionally isotropic σ as high as 3 mS/cm.

  12. Highly conductive ionic liquids toward high-performance space-lubricating greases.

    PubMed

    Fan, Xiaoqiang; Wang, Liping

    2014-08-27

    Although ionic liquids (ILs) as a class of promising materials have a wide range of applications due to the excellent properties, their potential as space lubricants has been not systematically explored. Here two kinds of conductive alkyl imidazolium ILs greases were prepared using 1-hexyl-3-methylimidazolium tetrafluoroborate (LB106) and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl) amide (L-F106) as base oil and the polytetrafluoroethylene (PTFE) as thickener, with multiple-alkylated cyclopentane grease (MACs) as a comparison. Their chemical composition and tribological properties were investigated in detail under simulated space environment which is composed of high vacuum, high temperature and irradiation. Results show that the high conductive ILs greases not only possess good adaptive abilities to space environment and thermal stability but also provide excellent friction reducing and antiwear behaviors as well as high load carrying capacities. The unique physicochemical properties are attributed to a combination of special anions and cations, the excellent tribological properties are strongly dependent on a boundary protective film on the rubbing surfaces.

  13. Enhanced ionic conductivity of apatite-type lanthanum silicate electrolyte for IT-SOFCs through copper doping

    NASA Astrophysics Data System (ADS)

    Ding, Xifeng; Hua, Guixiang; Ding, Dong; Zhu, Wenliang; Wang, Hongjin

    2016-02-01

    Apatite-type Lanthanum silicate (LSO) is among the most promising electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs) owing to the high conductivity and low activation energy at lower temperature than traditional doped-zirconia electrolyte. The ionic conductivity as well as the sintering density of lanthanum silicate oxy-apatite, La10Si6-xCuxO27-δ (LSCO, 0 ≤ x ≤ 2), was effectively enhanced through a small amount of doped copper. The phase composition, relative density, ionic conductivity and thermal expansion behavior of La10Si6-xCuxO27-δ was systematically investigated by X-ray diffraction (XRD), Archimedes' drainage method, scanning electron microscope (SEM), electrochemical impedance spectra (EIS) and thermal dilatometer techniques. With increasing copper doping content, the ionic conductivity of La10Si6-xCuxO27-δincreased, reaching a maximum of 4.8 × 10-2 S cm-1 at 800 °C for x = 1.5. The improved ionic conductivity could be primarily associated with the enhanced grain conductivity. The power output performance of NiO-LSCO/LSCO/LSCF single cell was superior to that obtained on NiO-LSO/LSO/LSCF at different temperatures using hydrogen as fuel and oxygen as oxidant, which could be attributed to the enhanced oxygen ionic conductivity as well as the sintering density for the copped doped lanthanum silicate. In conclusion, the apatite La10Si4.5Cu1.5O25.5 is a promising candidate electrolyte for IT-SOFCs.

  14. Defect Physics, Delithiation Mechanism, and Electronic and Ionic Conduction in Layered Lithium Manganese Oxide Cathode Materials

    NASA Astrophysics Data System (ADS)

    Hoang, Khang

    2015-02-01

    Layered Li Mn O2 and Li2Mn O3 are of great interest for lithium-ion battery cathodes because of their high theoretical capacities. The practical application of these materials is, however, limited due to poor electrochemical performance. We herein report a comprehensive first-principles study of defect physics in Li Mn O2 and Li2Mn O3 using hybrid density-functional calculations. We find that manganese antisites have low formation energies in Li Mn O2 and may act as nucleation sites for the formation of impurity phases. The antisites can also occur with high concentrations in Li2Mn O3 ; however, unlike in Li Mn O2 , they can be eliminated by tuning the experimental conditions during preparation. Other intrinsic point defects may also occur and have an impact on the materials' properties and functioning. An analysis of the formation of lithium vacancies indicates that lithium extraction from Li Mn O2 is associated with oxidation at the manganese site, resulting in the formation of manganese small hole polarons; whereas in Li2Mn O3 the intrinsic delithiation mechanism involves oxidation at the oxygen site, leading to the formation of bound oxygen hole polarons ηO+ . The layered oxides are found to have no or negligible bandlike carriers, and they cannot be doped n or p type. The electronic conduction proceeds through hopping of hole and/or electron polarons; the ionic conduction occurs through lithium monovacancy and/or divacancy migration mechanisms. Since ηO+ is not stable in the absence of negatively charged lithium vacancies in bulk Li2Mn O3 , the electronic conduction near the start of delithiation is likely to be poor. We suggest that the electronic conduction associated with ηO+ and, hence, the electrochemical performance of Li2Mn O3 can be improved through nanostructuring and/or ion substitution.

  15. Ionic-liquid-based proton conducting membranes for anhydrous H2/Cl2 fuel-cell applications.

    PubMed

    Liu, Sa; Zhou, Li; Wang, Pengjie; Zhang, Fangfang; Yu, Shuchun; Shao, Zhigang; Yi, Baolian

    2014-03-12

    An ionic-liquid-doped poly(benzimidazole) (PBI) proton-conducting membrane for an anhydrous H2/Cl2 fuel cell has been proposed. Compared with other ionic liquids, such as imidazole-type ionic liquids, diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]) showed better electrode reaction kinetics (H2 oxidation and Cl2 reduction reaction at platinum) and was more suitable for a H2/Cl2 fuel cell. PBI polymer and [dema][TfO] were compatible with each other, and the hybrid membranes exhibited high stability and good ionic conductivity, reaching 20.73 mS cm(-1) at 160 °C. We also analyzed the proton-transfer mechanism in this ionic-liquid-based membrane and considered that both proton-hopping and diffusion mechanisms existed. In addition, this composite electrolyte worked well in a H2/Cl2 fuel cell under non-water conditions. This work would give a good path to study the novel membranes for anhydrous H2/Cl2 fuel-cell application.

  16. A novel conductance glucose biosensor in ultra-low ionic strength solution triggered by the oxidation of Ag nanoparticles.

    PubMed

    Song, Yonghai; Chen, Jingyi; Liu, Hongyu; Li, Ping; Li, Hongbo; Wang, Li

    2015-09-03

    A simple, sensitive and effective method to detect glucose in ultra-low ionic strength solution containing citrate-capped silver nanoparticles (CCAgNPs) was developed by monitoring the change of solution conductance. Glucose was catalyzed into gluconic acid firstly by glucose oxidase in an O2-saturated solution accompanied by the reduction of O2 into hydrogen peroxide (H2O2). Then, CCAgNPs was oxidized by H2O2 into Ag(+) and the capping regent of citrate was released at the same time. All these resulted Ag(+), gluconic acid and the released citrate would contribute to the increase of solution ionic strength together, leading to a detectable increase of solution conductance. And a novel conductance glucose biosensor was developed with a routine linear range of 0.06-4.0 mM and a suitable detection limit of 18.0 μM. The novel glucose biosensor was further applied in energy drink sample and proven to be suitable for practical system with low ionic strength. The proposed conductance biosensor achieved a significant breakthrough of glucose detection in ultra-low ionic strength media.

  17. Low Temperature Synthesis of Cubic-phase Fast-ionic Conducting Bi-doped Garnet Solid State Electrolytes

    NASA Astrophysics Data System (ADS)

    Schwanz, Derek K.; Marinero, Ernesto

    We report on the synthesis of cubic-phase fast ionic conducting garnet solid state electrolytes based on LiLaZrO (LLZO) at unprecedented low synthesis temperatures. Ionic conductivities around 1.2 x 10-4 S/cm are readily achieved. Bismuth aliovalent substitution into LLZO utilizing the Pechini processing method is successfully employed to synthesize LiLaZrBiO compounds. Cubic phase LiLaZrBiO powders are generated in the temperature range 650C to 900C in air. In contrast, in the absence of Bi and under identical synthesis conditions, the cubic phase of LiLaZrO is not formed below 750C and a transformation to the poor ionically conducting tetragonal phase is observed at 800C for the undoped compound. The critical role of Bi in lowering the formation temperature of the garnet cubic phase and the improvements in ionic conductivity are elucidated in this work through microstructural and electrochemical studies.

  18. Mixed ionic and electronic conducting electrode studies for an alkali metal thermal to electric converter

    NASA Astrophysics Data System (ADS)

    Guo, Yuyan

    This research focuses on preparation, kinetics, and performance studies of mixed ionic and electronic conducting electrodes (MIEE) applied in an alkali metal thermal to electric converter (AMTEC). Two types of MIEE, metal/sodium titanate and metal/beta″-alumina were investigated, using Ni, Cu, Co and W as the metal components. Pure metal electrodes (PME) were also studied, including Ta, Ni, Nb, Ir, W and MoRe electrodes. The stability of MIEE/beta″-alumina solid electrolyte (BASE) interface was studied in terms of the chemical potential of Na-Al-Ti-O system at 1100K (typical AMTEC operating temperature). Ni metal was compatible with sodium titanate and BASE and displayed the best initial performance among all tested PMEs. Ni/sodium titanate electrodes with 4/1 mass ratios of metal/ceramic performed best among all tested electrodes. Scanning Electron Microscope (SEM) observations showed that grain agglomeration, which is the main mechanism for electrode degradation, occurred in all tested electrodes. Ceramic components were able to effectively limit the growth of metal grains and resulted in a long lifetime for MIEEs. Ni particles in the MIEE formed a network microstructure that was close to the theoretical morphology of the ideal electrode. A model based on percolation theory was constructed to interpret and predict the performance of MIEEs. The electrode kinetics was studied and a theoretical expression for the interface impedance was derived for both PME and MIEE, using electrochemical impedance spectroscopy (EIS). The conductivity of the Na2Ti 3O7 and Na2Ti6O13 mixture was measured. The average activation energy for the bulk conductivity was 0.87ev. Finally, theoretical analysis clarified that the transfer coefficient alpha value change would cause at most a few percent change in the electrode performance parameter B.

  19. Elucidating Interactions and Conductivity of Newly Synthesised Low Bandgap Polymer with Protic and Aprotic Ionic Liquids

    PubMed Central

    Attri, Pankaj; Lee, Seung-Hyun; Hwang, Sun Woo; Kim, Joong I. L.; Lee, Sang Woo; Kwon, Gi-Chung; Choi, Eun Ha; Kim, In Tae

    2013-01-01

    In this paper, we have examined the conductivity and interaction studies of ammonium and imidazolium based ionic liquids (ILs) with the newly synthesised low bandgap polymer (Poly(2-heptadecyl-4-vinylthieno[3,4-d]thiazole) (PHVTT)). Use of low bandgap polymers is the most suitable way to harvest a broader spectrum of solar radiations for solar cells. But, still there is lack of most efficient low bandgap polymer. In order to solve this problem, we have synthesised a new low bandgap polymer and investigated its interaction with the ILs to enhance its conductivity. ILs may undergo almost unlimited structural variations; these structural variations have attracted extensive attention in polymer studies. The aim of present work is to illustrate the state of art progress of implementing the interaction of ILs (protic and aprotic ILs) with newly synthesised low bandgap polymer. In addition to this, our UV-Vis spectroscopy, confocal Raman spectroscopy and FT-IR spectroscopy results have revealed that all studied ILs (tributylmethylammonium methyl sulfate ([N1444][MeSO4] from ammonium family) and 1-methylimidazolium chloride ([Mim]Cl, and 1-butyl-3-methylimidazolium chloride ([Bmim]Cl from imidazolium family) have potential to interact with polymer. Our semi empirical calculation with help of Hyperchem 7 shows that protic IL ([Mim]Cl) interacts strongly with the low bandgap polymer through the H-bonding. Further, protic ILs shows enhanced conductivity than aprotic ILs in association with low bandgap polymer. This study provides the combined effect of low bandgap polymer and ILs that may generate many theoretical and experimental opportunities. PMID:23874829

  20. Elucidating interactions and conductivity of newly synthesised low bandgap polymer with protic and aprotic ionic liquids.

    PubMed

    Attri, Pankaj; Lee, Seung-Hyun; Hwang, Sun Woo; Kim, Joong I L; Lee, Sang Woo; Kwon, Gi-Chung; Choi, Eun Ha; Kim, In Tae

    2013-01-01

    In this paper, we have examined the conductivity and interaction studies of ammonium and imidazolium based ionic liquids (ILs) with the newly synthesised low bandgap polymer (Poly(2-heptadecyl-4-vinylthieno[3,4-d]thiazole) (PHVTT)). Use of low bandgap polymers is the most suitable way to harvest a broader spectrum of solar radiations for solar cells. But, still there is lack of most efficient low bandgap polymer. In order to solve this problem, we have synthesised a new low bandgap polymer and investigated its interaction with the ILs to enhance its conductivity. ILs may undergo almost unlimited structural variations; these structural variations have attracted extensive attention in polymer studies. The aim of present work is to illustrate the state of art progress of implementing the interaction of ILs (protic and aprotic ILs) with newly synthesised low bandgap polymer. In addition to this, our UV-Vis spectroscopy, confocal Raman spectroscopy and FT-IR spectroscopy results have revealed that all studied ILs (tributylmethylammonium methyl sulfate ([N1444][MeSO4] from ammonium family) and 1-methylimidazolium chloride ([Mim]Cl, and 1-butyl-3-methylimidazolium chloride ([Bmim]Cl from imidazolium family) have potential to interact with polymer. Our semi empirical calculation with help of Hyperchem 7 shows that protic IL ([Mim]Cl) interacts strongly with the low bandgap polymer through the H-bonding. Further, protic ILs shows enhanced conductivity than aprotic ILs in association with low bandgap polymer. This study provides the combined effect of low bandgap polymer and ILs that may generate many theoretical and experimental opportunities.

  1. Improvement of switching endurance of conducting-bridge random access memory by addition of metal-ion-containing ionic liquid

    NASA Astrophysics Data System (ADS)

    Kinoshita, Kentaro; Sakaguchi, Atsushi; Harada, Akinori; Yamaoka, Hiroki; Kishida, Satoru; Fukaya, Yukinobu; Nokami, Toshiki; Itoh, Toshiyuki

    2017-04-01

    A remarkable improvement of cycling endurance was achieved by the addition of a trace amount of an ionic liquid ([bmim][Tf2N]) containing Cu(Tf2N)2 to the HfO2 layer of a conducting-bridge random access memory (CBRAM) with a Cu/HfO2/Pt structure. The improvement was brought about by the significant improvement of the dispersion of a set voltage and the suppression of the generation and migration of oxygen vacancies owing to the smooth diffusion of Cu ions in ionic liquids.

  2. Ionic conductivity of KMgCr(MoO4)3 molybdate

    NASA Astrophysics Data System (ADS)

    Sorokin, N. I.

    2017-05-01

    The ionic conductivity σ of KMgCr(MoO4)3 crystal has been investigated in a temperature range of 575-932 K by impedance spectroscopy in the frequency range of (5-5) × 105 Hz. Ternary molybdate was obtained from the initial MgMoO4 and KCr(MoO4)2 reagents by solid-phase technique in air at 923-973 K for 200 h. The temperature dependence σ( T) of a ceramic sample exhibits a jump of σ by a factor of about 4 at 833 ± 5 K, which is caused by the first-order phase transition. The σ value above the phase-transition temperature reaches 6 × 10-4 S/cm (932 K) at an ion-transport activation enthalpy of 0.84 ± 0.05 eV. The most likely carriers in KMgCr(MoO4)3 are K+ cations.

  3. Conductive polymeric ionic liquids for electroanalysis and solid-phase microextraction.

    PubMed

    Young, Joshua A; Zhang, Cheng; Devasurendra, Amila M; Tillekeratne, L M Viranga; Anderson, Jared L; Kirchhoff, Jon R

    2016-03-03

    Three novel electropolymerizable thiophene-based ionic liquids (ILs) were synthesized and characterized as potential candidates for developing selective extraction media for chemical analysis. Electropolymerization of the bis[(trifluoromethyl)sulfonyl]imide ([NTf2](-)) analogs successfully produced uniform polymeric thin-films on macro- and microelectrode substrates from both vinyl and methylimidazolium IL monomer derivatives. The resultant conducting polymer IL (CPIL) films were characterized by electrochemical methods and found to exhibit attractive behavior towards anionic species while simultaneously providing an exclusion barrier toward cationic species. Thermogravimetric analysis of the thiophene-based IL monomers established a high thermal stability, particularly for the methylimidazolium IL, which was stable until temperatures above 350 °C. Subsequently, the methylimidazolium IL was polymerized on 125 μm platinum wires and utilized for the first time as a sorbent coating for headspace solid-phase microextraction (HS-SPME). The sorbent coating was easily prepared in a reproducible manner, provided high thermal stability, and allowed for the gas chromatographic analysis of polar analytes. The normalized response of the poly[thioph-C6MIm][NTf2]-based sorbent coating exhibited higher extraction efficiency compared to an 85 μm polyacrylate fiber and excellent fiber-to-fiber reproducibility. Therefore, the electropolymerizable thiophene-based ILs were found to be viable new materials for the preparation of sorbent coatings for HS-SPME. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Cesium-Induced Ionic Conduction through a Single Nanofluidic Pore Modified with Calixcrown Moieties.

    PubMed

    Ali, Mubarak; Ahmed, Ishtiaq; Ramirez, Patricio; Nasir, Saima; Cervera, Javier; Mafe, Salvador; Niemeyer, Christof M; Ensinger, Wolfgang

    2017-09-12

    We demonstrate experimentally and theoretically a nanofluidic device for the selective recognition of the cesium ion by exploiting host-guest interactions inside confined geometry. For this purpose, a host molecule, i.e., the amine-terminated p-tert-butylcalix[4]arene-crown (t-BuC[4]C-NH2), is successfully synthesized and functionalized on the surface of a single conical nanopore fabricated in a poly(ethylene terephthalate) (PET) membrane through carbodiimide coupling chemistry. On exposure to the cesium cation, the t-BuC[4]C-Cs(+) complex is formed through host-guest interaction, leading to the generation of positive fixed charges on the pore surface. The asymmetrical distribution of these groups along the conical nanopore leads to the electrical rectification observed in the current-voltage (I-V) curve. On the contrary, other alkali cations are not able to induce any significant change in the rectification characteristics of the nanopore. The success of the chemical modification is monitored from the changes in the electrical readout of the nanopore. Theoretical results based on the Nernst-Planck and Poisson equations further demonstrate the validity of the experimental approach to the cesium-induced ionic conduction of the nanopore.

  5. Electrochemical fields within 3D reconstructed microstructures of mixed ionic and electronic conducting devices

    NASA Astrophysics Data System (ADS)

    Zhang, Yanxiang; Chen, Yu; Lin, Ye; Yan, Mufu; Harris, William M.; Chiu, Wilson K. S.; Ni, Meng; Chen, Fanglin

    2016-11-01

    The performance and stability of the mixed ionic and electronic conducting (MIEC) membrane devices, such as solid oxide cells (SOCs) and oxygen separation membranes (OSMs) interplay tightly with the transport properties and the three-dimensional (3D) microstructure of the membrane. However, development of the MIEC devices is hindered by the limited knowledge about the distribution of electrochemical fields within the 3D local microstructures, especially at surface and interface. In this work, a generic model conforming to local thermodynamic equilibrium is developed to calculate the electrochemical fields, such as electric potential and oxygen chemical potential, within the 3D microstructure of the MIEC membrane. Stability of the MIEC membrane is evaluated by the distribution of oxygen partial pressure. The cell-level performance such as polarization resistance and voltage vs. current curve can be further calculated. Case studies are performed to demonstrate the capability of the framework by using X-ray computed tomography reconstructed 3D microstructures of a SOC and an OSM. The calculation method demonstrates high computational efficiency for large size 3D tomographic microstructures, and permits parallel calculation. The framework can serve as a powerful tool for correlating the transport properties and the 3D microstructure to the performance and the stability of MIEC devices.

  6. Microscopic derivation of the Hubbard-Onsager-Zwanzig expression of limiting ionic conductivity

    NASA Astrophysics Data System (ADS)

    Bagchi, Biman

    1998-09-01

    An outstanding problem in the theory of ionic conductivity is a derivation of the well-known Hubbard-Onsager-Zwanzig expression for the dielectric friction on an ion from first principles. In fact, microscopic theories have repeatedly failed to reproduce the Hubbard-Onsager-Zwanzig expression under any limiting conditions. We show in this article that the existing molecular theories and the continuum model treatments calculate two entirely different contributions to the friction on the ion. While the former calculates the contribution from the solvent density mode alone, the latter includes only the contribution from the current mode. Thus the existing molecular theories can never be reduced to the Hubbard-Onsager (H-O) theory. In addition, we show that the existing molecular theories become inconsistent for larger ions where the H-O theory is accurate. The reverse is true for smaller ions. An expression is derived here which is valid at both the limits and for all ion sizes and its consequences discussed.

  7. Guar gum as biosourced building block to generate highly conductive and elastic ionogels with poly(ionic liquid) and ionic liquid.

    PubMed

    Zhang, Biao; Sudre, Guillaume; Quintard, Guilhem; Serghei, Anatoli; David, Laurent; Bernard, Julien; Fleury, Etienne; Charlot, Aurélia

    2017-02-10

    In this study, we report on the simple and straightforward preparation of ionogels arising from the addition of guar gum (a plant-based polysaccharide) in a solution of precisely-defined poly(ionic liquid) chains (PIL) in imidazolium-based ionic liquid (IL). The development of intermolecular polar interactions (mainly hydrogen bonds) and topologic chain entanglements induces the formation of physical biohybrid ionogels, whose elastic properties can be easily tuned by varying the composition (up to 30000Pa). The combined presence of guar gum and PIL confers excellent dimensional stability to the ionogels with no IL exudation combined with high thermal properties (up to 310°C). The resulting materials are shown to exhibit gel scattering profiles and high conductivities (> 10(-4)S/cm at 30°C). The benefit linked to the formation of guar/PIL associations in IL medium enables to find a good compromise between the mechanical cohesion and the mobility ensuring the ionic transport.

  8. Structural and Ionic Transport Properties of Protonic Conducting Solid Biopolymer Electrolytes Based on Carboxymethyl Cellulose Doped with Ammonium Fluoride.

    PubMed

    Ramlli, M A; Isa, M I N

    2016-11-10

    Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and transference number measurement (TNM) techniques were applied to investigate the complexation, structural, and ionic transport properties of and the dominant charge-carrier species in a solid biopolymer electrolyte (SBE) system based on carboxymethyl cellulose (CMC) doped with ammonium fluoride (NH4F), which was prepared via a solution casting technique. The SBEs were partially opaque in appearance, with no phase separation. The presence of interactions between the host polymer (CMC) and the ionic dopant (NH4F) was proven by FT-IR analysis at the C-O band. XRD spectra analyzed using Origin 8 software disclose that the degree of crystallinity (χc%) of the SBEs decreased with the addition of NH4F, indicating an increase in the amorphous nature of the SBEs. Analysis of the ionic transport properties reveals that the ionic conductivity of the SBEs is dependent on the ionic mobility (μ) and diffusion of ions (D). TNM analysis confirms that the SBEs are proton conductors.

  9. Mixed ionic and electronic conducting membranes for hydrogen generation and separation

    NASA Astrophysics Data System (ADS)

    Cui, Hengdong

    Dense mixed ionic and electronic conducting (MIEC) membranes are receiving increasing attention due to their potential for application as gas separation membranes to separate oxygen from air. The objective of this work is to study a novel, chemically-assisted separation process that utilizes oxygen-ion and electron-conducting MIECs for generating and separating hydrogen from steam. This research aims at exploring new routes and materials for high-purity hydrogen production for use in fuel cells and hydrogen-based internal combustion (IC) engines. In this approach, hydrocarbon fuel such as methane is fed to one side of the membrane, while steam is fed to the other side. The MIEC membrane separation process involves steam dissociation and oxidation of the fuel. The oxygen ions formed as a result of steam dissociation are transported across the membrane in a coupled transport process with electrons being transported in the opposite direction. Upon reaching the fuel side of the membrane, the oxygen ions oxidize the hydrocarbon. This process results in hydrogen production on the steam side of the membrane. The oxygen partial pressure gradient across the membrane is the driving force for this process. In this work, a novel, dual-phase composite MIEC membrane system comprising of rare-earth doped ceria with high oxygen ion conductivity and donor-doped strontium titanate with high electronic conductivity were investigated. The chemical diffusion coefficient and surface exchange coefficient have been measured using the electrical conductivity relaxation (ECR) technique. These two parameters control the rate of oxygen permeation across the membrane. The permeation data have been fit with a kinetic model that incorporates oxygen surface exchange on two sides of the membrane and bulk transport of oxygen through the membrane. This material has higher bulk diffusion coefficient and surface exchange reaction rate compared to other known MIEC conductors under the process

  10. Imaging alpha-hemolysin with molecular dynamics: ionic conductance, osmotic permeability, and the electrostatic potential map.

    PubMed

    Aksimentiev, Aleksij; Schulten, Klaus

    2005-06-01

    alpha-Hemolysin of Staphylococcus aureus is a self-assembling toxin that forms a water-filled transmembrane channel upon oligomerization in a lipid membrane. Apart from being one of the best-studied toxins of bacterial origin, alpha-hemolysin is the principal component in several biotechnological applications, including systems for controlled delivery of small solutes across lipid membranes, stochastic sensors for small solutes, and an alternative to conventional technology for DNA sequencing. Through large-scale molecular dynamics simulations, we studied the permeability of the alpha-hemolysin/lipid bilayer complex for water and ions. The studied system, composed of approximately 300,000 atoms, included one copy of the protein, a patch of a DPPC lipid bilayer, and a 1 M water solution of KCl. Monitoring the fluctuations of the pore structure revealed an asymmetric, on average, cross section of the alpha-hemolysin stem. Applying external electrostatic fields produced a transmembrane ionic current; repeating simulations at several voltage biases yielded a current/voltage curve of alpha-hemolysin and a set of electrostatic potential maps. The selectivity of alpha-hemolysin to Cl(-) was found to depend on the direction and the magnitude of the applied voltage bias. The results of our simulations are in excellent quantitative agreement with available experimental data. Analyzing trajectories of all water molecule, we computed the alpha-hemolysin's osmotic permeability for water as well as its electroosmotic effect, and characterized the permeability of its seven side channels. The side channels were found to connect seven His-144 residues surrounding the stem of the protein to the bulk solution; the protonation of these residues was observed to affect the ion conductance, suggesting the seven His-144 to comprise the pH sensor that gates conductance of the alpha-hemolysin channel.

  11. Gold-ionic liquid nanofluids with preferably tribological properties and thermal conductivity.

    PubMed

    Wang, Baogang; Wang, Xiaobo; Lou, Wenjing; Hao, Jingcheng

    2011-03-28

    Gold/1-butyl-3-methylimidazolium hexafluorophosphate (Au/[Bmim][PF6]) nanofluids containing different stabilizing agents were fabricated by a facile one-step chemical reduction method, of which the nanofluids stabilized by cetyltrimethylammonium bromide (CTABr) exhibited ultrahighly thermodynamic stability. The transmission electron microscopy, UV-visible absorption, Fourier transform infrared, and X-ray photoelectron characterizations were conducted to reveal the stable mechanism. Then, the tribological properties of these ionic liquid (IL)-based gold nanofluids were first investigated in more detail. In comparison with pure [Bmim][PF6] and the nanofluids possessing poor stability, the nanofluids with high stability exhibited much better friction-reduction and anti-wear properties. For instance, the friction coefficient and wear volume lubricated by the nanofluid with rather low volumetric concentration (1.02 × 10-3%) stabilized by CTABr under 800 N are 13.8 and 45.4% lower than that of pure [Bmim][PF6], confirming that soft Au nanoparticles (Au NPs) also can be excellent additives for high performance lubricants especially under high loads. Moreover, the thermal conductivity (TC) of the stable nanofluids with three volumetric fraction (2.55 × 10-4, 5.1 × 10-4, and 1.02 × 10-3%) was also measured by a transient hot wire method as a function of temperature (33 to 81°C). The results indicate that the TC of the nanofluid (1.02 × 10-3%) is 13.1% higher than that of [Bmim][PF6] at 81°C but no obvious variation at 33°C. The conspicuously temperature-dependent and greatly enhanced TC of Au/[Bmim][PF6] nanofluids stabilized by CTABr could be attributed to micro-convection caused by the Brownian motion of Au NPs. Our results should open new avenues to utilize Au NPs and ILs in tribology and the high-temperature heat transfer field.

  12. Gold-ionic liquid nanofluids with preferably tribological properties and thermal conductivity

    NASA Astrophysics Data System (ADS)

    Wang, Baogang; Wang, Xiaobo; Lou, Wenjing; Hao, Jingcheng

    2011-12-01

    Gold/1-butyl-3-methylimidazolium hexafluorophosphate (Au/[Bmim][PF6]) nanofluids containing different stabilizing agents were fabricated by a facile one-step chemical reduction method, of which the nanofluids stabilized by cetyltrimethylammonium bromide (CTABr) exhibited ultrahighly thermodynamic stability. The transmission electron microscopy, UV-visible absorption, Fourier transform infrared, and X-ray photoelectron characterizations were conducted to reveal the stable mechanism. Then, the tribological properties of these ionic liquid (IL)-based gold nanofluids were first investigated in more detail. In comparison with pure [Bmim][PF6] and the nanofluids possessing poor stability, the nanofluids with high stability exhibited much better friction-reduction and anti-wear properties. For instance, the friction coefficient and wear volume lubricated by the nanofluid with rather low volumetric concentration (1.02 × 10-3%) stabilized by CTABr under 800 N are 13.8 and 45.4% lower than that of pure [Bmim][PF6], confirming that soft Au nanoparticles (Au NPs) also can be excellent additives for high performance lubricants especially under high loads. Moreover, the thermal conductivity (TC) of the stable nanofluids with three volumetric fraction (2.55 × 10-4, 5.1 × 10-4, and 1.02 × 10-3%) was also measured by a transient hot wire method as a function of temperature (33 to 81°C). The results indicate that the TC of the nanofluid (1.02 × 10-3%) is 13.1% higher than that of [Bmim][PF6] at 81°C but no obvious variation at 33°C. The conspicuously temperature-dependent and greatly enhanced TC of Au/[Bmim][PF6] nanofluids stabilized by CTABr could be attributed to micro-convection caused by the Brownian motion of Au NPs. Our results should open new avenues to utilize Au NPs and ILs in tribology and the high-temperature heat transfer field.

  13. Simultaneous improvement in ionic conductivity and flexibility of solid polymer electrolytes for thin film lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Ji, Jianying

    Solid polymer electrolytes (SPEs) provide advantages over liquid electrolytes in terms of safety, reliability, less temperature sensitive, and simplicity of design. With the use of a SPE in lithium batteries, high specific energy and specific power, safe operation, flexibility in packaging, and low cost of fabrication can be expected. However, after 30 years, SPEs have rarely found commercial success due to the low ionic conductivity and/or insufficient mechanical properties, both of which are related to the movement of the polymer chains. Many physical/chemical methods have been exploited to simultaneously create enhancement in ionic conductivity and mechanical properties, and some suggested ways have shown promise. However, the complex strategies have always introduced other challenge issues and incurred extra costs for manufacturing. In such a context, the development of dry solid state electrolytes is the central challenge to be faced worldwide. This thesis deals with the approaches to improving ionic conductivity and mechanical properties simultaneously. The method is to apply two kinds of controllable organic fillers: copolymer and protein. Our work revealed that the commercial available copolymer, poly (ethylene oxide)- block-polyethylene (PEO-b-PE), possesses a capability for enhancing the multiple performances of poly(ethylene oxide)(PEO)-based polymer electrolyte. And the effects of composition and molecular weight of the copolymers on performance of the resulting SPEs were examined. It was found that increasing the PE block percentage in the copolymer resulted in a significant increase in both ionic conductivity and mechanical properties, while increasing the molecular weight of the copolymer resulted in better mechanical properties, and an identical ionic conductivity. A rubber-like, soy protein-based SPE (s-SPE)was obtained by employing soy protein isolate (SPI), a soy product usually used as rigid fillers for enhancing mechanical properties of

  14. Electronic and ionic co-conductive coating on the separator towards high-performance lithium-sulfur batteries

    NASA Astrophysics Data System (ADS)

    Wang, Qingsong; Wen, Zhaoyin; Yang, Jianhua; Jin, Jun; Huang, Xiao; Wu, Xiangwei; Han, Jinduo

    2016-02-01

    A thin coating layer composed of the mixture of the electronic conductive carbon and lithium ionic conductive inorganic solid electrolyte was introduced on one side of the routine Celgard separator. This functional coated separator is designed to localize the polysulfides on the cathode side and act as an upper current collector for further utilization of sulfur while alleviating the ion conductivity decrease induced by the dissolved polysulfides in the discharge and charge process. Moreover, catalytic conversion of polysulfides by the solid state highly ionic conductor is observed. This brings significant improvement in battery specific capacity and cycling stability, with an initial discharge capacity of 1247 mA h g-1 and a reversible capacity of 830 mA h g-1 after 150 extended cycles at 0.5 C rate. Rest-testing proves a low self-discharge and excellent capacity retention of the modified cells.

  15. Electropolymerized Pyrrole-Based Conductive Polymeric Ionic Liquids and Their Application for Solid-Phase Microextraction.

    PubMed

    Devasurendra, Amila M; Zhang, Cheng; Young, Joshua A; Tillekeratne, L M Viranga; Anderson, Jared L; Kirchhoff, Jon R

    2017-07-26

    Pyrrole was covalently bonded to 1-methyl and 1-benzylimidazolium ionic liquids (ILs) via an N-substituted alkyl linkage to prepare electropolymerizable IL monomers with excellent thermal stability. The methylimidazolium IL, [pyrrole-C6MIm](+), was then electropolymerized on macro- and microelectrode materials to form conductive polymeric IL (CPIL)-modified surfaces. Electrochemical characterization of a 1.6 mm diameter Pt disk electrode modified with poly[pyrrole-C6MIm](+) demonstrated a selective uptake for an anionic redox probe while rejecting a cationic redox probe. Furthermore, electropolymerization of [pyrrole-C6MIm](+) doped with single-walled carbon nanotubes (SWNT) on 125 μm platinum wires produced 42 μm thick poly[pyrrole-C6MIm](+)/SWNT films compared to 17 μm in the absence of SWNT and 5 μm for the previously reported poly[thiophene-C6MIm](+) coatings. The poly[pyrrole-C6MIm](+)/SWNT films were prepared with reproducible thicknesses as well as thermal properties sufficient for high-temperature applications, such as solid-phase microextraction (SPME) with gas chromatographic analysis. The utilization of the CPIL sorbent materials in SPME experiments provided excellent extraction efficiencies and selectivity toward organic aromatic analytes. The CPIL sorbent coatings also yielded outstanding fiber-to-fiber reproducibility on the basis of extraction efficiencies and improved response for a range of analytes relative to commercial 100 μm poly(dimethylsiloxane) fibers when normalized for differences in film thickness. Poly[pyrrole-C6MIm](+) CPIL coatings doped with SWNT are therefore promising new sorbent materials for SPME analyses.

  16. Molecular mechanics of DNA bricks: in situ structure, mechanical properties and ionic conductivity

    NASA Astrophysics Data System (ADS)

    Slone, Scott Michael; Li, Chen-Yu; Yoo, Jejoong; Aksimentiev, Aleksei

    2016-05-01

    The DNA bricks method exploits self-assembly of short DNA fragments to produce custom three-dimensional objects with subnanometer precision. In contrast to DNA origami, the DNA brick method permits a variety of different structures to be realized using the same library of DNA strands. As a consequence of their design, however, assembled DNA brick structures have fewer interhelical connections in comparison to equivalent DNA origami structures. Although the overall shape of the DNA brick objects has been characterized and found to conform to the features of the target designs, the microscopic properties of DNA brick objects remain yet to be determined. Here, we use the all-atom molecular dynamics method to directly compare the structure, mechanical properties and ionic conductivity of DNA brick and DNA origami structures different only by internal connectivity of their consistituent DNA strands. In comparison to equivalent DNA origami structures, the DNA brick structures are found to be less rigid and less dense and have a larger cross-section area normal to the DNA helix direction. At the microscopic level, the junction in the DNA brick structures are found to be right-handed, similar to the structure of individual Holliday junctions (HJ) in solution, which contrasts with the left-handed structure of HJ in DNA origami. Subject to external electric field, a DNA brick plate is more leaky to ions than an equivalent DNA origami plate because of its lower density and larger cross-section area. Overall, our results indicate that the structures produced by the DNA brick method are fairly similar in their overall appearance to those created by the DNA origami method but are more compliant when subject to external forces, which likely is a consequence of their single crossover design.

  17. Reusable electrochemical sensor for bisphenol A based on ionic liquid functionalized conducting polymer platform.

    PubMed

    Wang, Jhe-Yi; Su, Ya-Ling; Wu, Bo-Hao; Cheng, Shu-Hua

    2016-01-15

    The toxicity of bisphenol A (BPA) has attracted considerable attention, and the reported electrochemical sensors for BPA need further improvement in reusability due to serious surface fouling. In this study, a composite film is designed aiming to provide both an accurate and repeatable platform for BPA determination. The conducting poly(3,4-ethylenedioxythiophene) film (PEDOT) and ionic liquid 1-butyl-3-methylimidazolium bromide (BMIMBr) were modified onto screen-printed carbon electrodes (SPCE) by electropolymerization and drop/spin methods, respectively. The surface characteristics of the composite film were characterized by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and surface water contact angle experiments. The composite film-modified electrodes exhibited a linear response to BPA in the range of 0.1-500µM in pH 7.0 phosphate buffer solution (PBS) under optimized flow-injection amperometry. The method sensitivity and detection limit (S/N=3) were 0.2661μA μM(-1) (2.419μA μM(-1)cm(-2)) and 0.02µM, respectively. A relative standard deviation of 1.95% was obtained for 77 successive measurements of 10µM BPA, and the repeatability outperformed previously reported work. The proposed method was applied to detect BPA released from plastic water bottles using the standard addition method, and satisfactory recoveries were obtained. The electrochemical assay was validated by comparison with the chromatographic method, and the results showed good agreement between the two methods.

  18. Structure and ionic conductivity of the solid electrolyte interphase layer on tin anodes in Na-ion batteries

    NASA Astrophysics Data System (ADS)

    Kuo, Liang-Yin; Moradabadi, Ashkan; Huang, Hsin-Fu; Hwang, Bing-Joe; Kaghazchi, Payam

    2017-02-01

    Structure, stability, and ionic conductivity of the SEI layer on Sn anodes in Na-ion batteries (NIBs) are studied using experimental and theoretical methods. Raman spectra show that the SEI layer consists of Na2O and Na2CO3, the latter becoming more dominant close to the discharged state (at 0.3 V). According to our theoretical phase diagrams, Na2O can be stable in the whole voltage range of charge/discharge (from 0.0 V to 1.90 V), but Na2CO3 can decompose under carbon and/or oxygen poor conditions, leading to the formation of Na2O. These findings are in agreement with our experimental cyclic voltammetry and Raman spectra as function of voltage. Both compounds of the SEI layer have very low ionic conductivity close to the discharge state (0.2-0.3 V), but the ionic conductivity of Na2O is much larger than that of Na2CO3 for a wide range of voltages from 0.4 V to the charge state (∼1.5 V). This work suggests that engineered artificial SEI with Na2O or naturally formed SEI in a carbon and/or oxygen poor environment can improve the conductivity of the SEI layer in NIBs.

  19. Gold-ionic liquid nanofluids with preferably tribological properties and thermal conductivity

    PubMed Central

    2011-01-01

    Gold/1-butyl-3-methylimidazolium hexafluorophosphate (Au/[Bmim][PF6]) nanofluids containing different stabilizing agents were fabricated by a facile one-step chemical reduction method, of which the nanofluids stabilized by cetyltrimethylammonium bromide (CTABr) exhibited ultrahighly thermodynamic stability. The transmission electron microscopy, UV-visible absorption, Fourier transform infrared, and X-ray photoelectron characterizations were conducted to reveal the stable mechanism. Then, the tribological properties of these ionic liquid (IL)-based gold nanofluids were first investigated in more detail. In comparison with pure [Bmim][PF6] and the nanofluids possessing poor stability, the nanofluids with high stability exhibited much better friction-reduction and anti-wear properties. For instance, the friction coefficient and wear volume lubricated by the nanofluid with rather low volumetric concentration (1.02 × 10-3%) stabilized by CTABr under 800 N are 13.8 and 45.4% lower than that of pure [Bmim][PF6], confirming that soft Au nanoparticles (Au NPs) also can be excellent additives for high performance lubricants especially under high loads. Moreover, the thermal conductivity (TC) of the stable nanofluids with three volumetric fraction (2.55 × 10-4, 5.1 × 10-4, and 1.02 × 10-3%) was also measured by a transient hot wire method as a function of temperature (33 to 81°C). The results indicate that the TC of the nanofluid (1.02 × 10-3%) is 13.1% higher than that of [Bmim][PF6] at 81°C but no obvious variation at 33°C. The conspicuously temperature-dependent and greatly enhanced TC of Au/[Bmim][PF6] nanofluids stabilized by CTABr could be attributed to micro-convection caused by the Brownian motion of Au NPs. Our results should open new avenues to utilize Au NPs and ILs in tribology and the high-temperature heat transfer field. PMID:21711789

  20. MIEC (mixed-ionic-electronic-conduction)-based access devices for non-volatile crossbar memory arrays

    NASA Astrophysics Data System (ADS)

    Shenoy, Rohit S.; Burr, Geoffrey W.; Virwani, Kumar; Jackson, Bryan; Padilla, Alvaro; Narayanan, Pritish; Rettner, Charles T.; Shelby, Robert M.; Bethune, Donald S.; Raman, Karthik V.; BrightSky, Matthew; Joseph, Eric; Rice, Philip M.; Topuria, Teya; Kellock, Andrew J.; Kurdi, Bülent; Gopalakrishnan, Kailash

    2014-10-01

    Several attractive applications call for the organization of memristive devices (or other resistive non-volatile memory (NVM)) into large, densely-packed crossbar arrays. While resistive-NVM devices frequently possess some degree of inherent nonlinearity (typically 3-30× contrast), the operation of large (\\gt 1000×1000 device) arrays at low power tends to require quite large (\\gt 1e7) ON-to-OFF ratios (between the currents passed at high and at low voltages). One path to such large nonlinearities is the inclusion of a distinct access device (AD) together with each of the state-bearing resistive-NVM elements. While such an AD need not store data, its list of requirements is almost as challenging as the specifications demanded of the memory device. Several candidate ADs have been proposed, but obtaining high performance without requiring single-crystal silicon and/or the high processing temperatures of the front-end-of-the-line—which would eliminate any opportunity for 3D stacking—has been difficult. We review our work at IBM Research—Almaden on high-performance ADs based on Cu-containing mixed-ionic-electronic conduction (MIEC) materials [1-7]. These devices require only the low processing temperatures of the back-end-of-the-line, making them highly suitable for implementing multi-layer cross-bar arrays. MIEC-based ADs offer large ON/OFF ratios (\\gt 1e7), a significant voltage margin {{V}m} (over which current \\lt 10 nA), and ultra-low leakage (\\lt 10 pA), while also offering the high current densities needed for phase-change memory and the fully bipolar operation needed for high-performance RRAM. Scalability to critical lateral dimensions \\lt 30 nm and thicknesses \\lt 15 nm, tight distributions and 100% yield in large (512 kBit) arrays, long-term stability of the ultra-low leakage states, and sub-50 ns turn-ON times have all been demonstrated. Numerical modeling of these MIEC-based ADs shows that their operation depends on C{{u}+} mediated hole

  1. Effects of ionic conduction on hydrothermal hydrolysis of corn starch and crystalline cellulose induced by microwave irradiation.

    PubMed

    Tsubaki, Shuntaro; Oono, Kiriyo; Onda, Ayumu; Yanagisawa, Kazumichi; Mitani, Tomohiko; Azuma, Jun-ichi

    2016-02-10

    This study investigated the effects of ionic conduction of electrolytes under microwave field to facilitate hydrothermal hydrolysis of corn starch and crystalline cellulose (Avicel), typical model biomass substrates. Addition of 0.1M NaCl was effective to improve reducing sugar yield by 1.61-fold at unit energy (kJ) level. Although Avicel cellulose was highly recalcitrant to hydrothermal hydrolysis, addition of 0.1M MgCl2 improved reducing sugar yield by 6.94-fold at unit energy (kJ). Dielectric measurement of the mixture of corn starch/water/electrolyte revealed that ionic conduction of electrolytes were strongly involved in facilitating hydrothermal hydrolysis of polysaccharides.

  2. Ionic Conductivity of Block Copolymer Electrolytes in the Vicinity of Order−Disorder and Order−Order Transitions

    SciTech Connect

    Wanakule, Nisita S.; Panday, Ashoutosh; Mullin, Scott A.; Gann, Eliot; Hexemer, Alex; Balsara, Nitash P.

    2009-09-15

    Order-order and order-disorder phase transitions in mixtures of poly(styrene-block-ethylene oxide) (SEO) copolymers and lithium bis(trifluoromethylsulfonimide) (LiTFSI), a common lithium salt used in polymer electrolytes, were studied using a combination of small-angle X-ray scattering (SAXS), birefringence, and ac impedance spectroscopy. The SEO/LiTFSI mixtures exhibit lamellar, hexagonally packed cylinders, and gyroid microphases. The molecular weight of the blocks and the salt concentration was adjusted to obtain order-order and order-disorder transition temperatures within the available experimental window. The ionic conductivities of the mixtures, normalized by the ionic conductivity of a 20 kg/mol homopolymer PEO sample at the salt concentration and temperature of interest, were independent of temperature, in spite of the presence of the above-mentioned phase transitions.

  3. Ionic conductivity of single crystals of sodium aluminium germanate Na8Al6Ge6O24(OH)2

    NASA Astrophysics Data System (ADS)

    Sorokin, N. I.

    2015-09-01

    The electrical conductivity of single crystals of sodium aluminium germanate Na8Al6Ge6O24(OH)2 (cubic system, sp. gr. ), which is a germanium analog of sodalite, has been studied in the temperature range of 468‒758 K. Na8Al6Ge6O24(OH)2 crystals are obtained by hydrothermal synthesis (temperature in the dissolution zone 573‒673 K, temperature gradient ~1.5 K/cm). NaAlO2 and GeO2В oxides are used as starting reagents; NaOH hydroxide serves as a solvent. The ionic conductivity of Na8Al6Ge6O24(OH)2 crystals is 2 × 10-4 S/cm (at 758 K); the activation energy of ionic transfer is 0.46 ± 0.03 eV.

  4. AC ionic conductivity and DC polarization method of lithium ion transport in PMMA-LiBF4 gel polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Osman, Z.; Mohd Ghazali, M. I.; Othman, L.; Md Isa, K. B.

    2012-01-01

    Polymethylmethacrylate (PMMA)-based gel polymer electrolytes comprising ethylene carbonate-propylene carbonate (EC/PC) mixed solvent plasticizer and various concentrations of lithium tetrafluoroborate (LiBF4) salt are prepared using a solvent casting technique. Electrical conductivity and transference number measurements were carried out to investigate conductivity and charge transport in the gel polymer electrolytes. The conductivity results show that the ionic conductivity of the samples increases when the amount of salt is increased, however decreases after reaching the optimum value. This result is consistent with the transference number measurements. The conductivity-frequency dependence plots show two distinct regions; i.e. at lower frequencies the conductivity increases with increasing frequency and the frequency independent plateau region at higher frequencies. The temperature-dependence conductivity of the films seems to obey the Arrhenius rule.

  5. Multilayered YSZ/GZO films with greatly enhanced ionic conduction for low temperature solid oxide fuel cells.

    PubMed

    Li, Bin; Zhang, Jiaming; Kaspar, Tiffany; Shutthanandan, Vaithiyalingam; Ewing, Rodney C; Lian, Jie

    2013-01-28

    Strain confinement in heterostructured films significantly affects ionic conductivity of the electrolytes for solid oxide fuel cells based on a multi-layered design strategy. Nearly ideal tensile strain can be achieved by a dedicated manipulation of the lattice mismatch between adjacent layers and fine control of the layer thicknesses to minimize the formation of dislocations and thus to achieve optimized ionic conduction. This strategy was demonstrated by a model system of multilayered 8 mol%Y(2)O(3) stabilized ZrO(2) (YSZ) with Gd(2)Zr(2)O(7) (GZO) films, which were epitaxially grown on Al(2)O(3) (0001) substrates by pulsed laser deposition (PLD) with the {111} planes of YSZ/GZO along the Al(2)O(3) [0 1 -1 0] direction. The tensile strain (3%) resulting from the lattice mismatch can be confined in individual YSZ layers with the formation of a coherent, dislocation-free interface upon the manipulation of the layer thickness below a critical value, e.g., down to 5 nm. The strained heterostructure displays a two order-of-magnitude increase in oxide-ion conductivity as compared with bulk YSZ, and a high ionic conductivity of 0.01 S cm(-1) at 475 °C can be achieved, five times greater than that of Gd-doped ceria/zirconia. The approach of strain confinement by fine control of lattice mismatch and layer thickness represents a promising strategy in developing advanced electrolytes enabling the miniaturization of solid-state ionic devices that can be operated at low temperatures below 500 °C.

  6. Size effect of cubic ZrO2 nanoparticles on ionic conductivity of polyethylene oxide-based composite

    NASA Astrophysics Data System (ADS)

    Dey, Arup; Ghoshal, Tandra; Karan, S.; De, S. K.

    2011-08-01

    A solvent free solid composite polymer electrolyte (SCPE) film consisting of high molecular mass polyethylene oxide (PEO) with sodium perchlorate (NaClO4) as electrolytic salt and cubic zirconium oxide (ZrO2) nanoparticles as the filler has been prepared by solution casting technique to influence the transport properties. X-ray diffraction and Fourier transform infrared spectroscopy confirm the formation of the SCPE film, whereas atomic force microscopy reveals the presence of a network of interconnected nanoparticles forming uniform surface feature of relatively low roughness. The highest ionic conductivity (σ = 6.96 × 10-5 S-cm-1) for PEO25 - NaClO4 with 5 wt. % ZrO2 nanoparticles of the smallest size 4.5 nm is an order of magnitude higher than the pure PEO25 - NaClO4 at room temperature. The conductivity enhancement is due to the creation of additional sites and favorable conduction pathways for ionic transport through Lewis acid-base type interactions between the polar surface groups of the ceramic filler and the electrolyte ionic species.

  7. Recent Advances in Fast Ion Conducting Materials and Devices - Proceedings of the 2nd Asian Conference on Solid State Ionics

    NASA Astrophysics Data System (ADS)

    Chowdari, B. V. R.; Liu, Qingguo; Chen, Liquan

    The Table of Contents for the book is as follows: * Preface * Invited Papers * Recent Trends in Solid State Ionics * Theoretical Aspects of Fast Ion Conduction in Solids * Chemical Bonding and Intercalation Processes in Framework Structures * Extra-Large Near-Electrode Regions and Diffusion Length on the Solid Electrolyte-Electrode Interface as Studied by Photo-EMF Method * Frequency Response of Glasses * XPS Studies on Ion Conducting Glasses * Characterization of New Ambient Temperature Lithium Polymer-Electrolyte * Recent Development of Polymer Electrolytes: Solid State Voltammetry in Polymer Electrolytes * Secondary Solid State Batteries: From Material Properties to Commercial Development * Silver Vanadium Oxide Bronze and its Applications for Electrochemical Devices * Study on β''-Alumina Solid Electrolyte and β Battery in SIC * Materials for Solid Oxide Fuel Cells * Processing for Super Superionic Ceramics * Hydrogen Production Using Oxide Ionic or Protonic Conductor * Ionically Conductive Sulfide-Based Lithium Glasses * Relation of Conductivity to Structure and Structural Relaxation in Ion-Conducting Glasses * The Mechanism of Ionic Conductivity in Glass * The Role of Synthesis and Structure in Solid State Ionics - Electrodes to Superconductors * Electrochromism in Spin-Coated Thin Films from Peroxo-Poly tungstate Solutions * Electrochemical Studies on High Tc Superconductors * Multivalence Fast Ionic Conductors - Montmorillonites * Contributed Papers * Volt-Ampere Characteristics and Interface Charge Transport in Solid Electrolytes * Internal Friction of Silver Chalcogenides * Thermal Expansion of Ionic and Superionic Solids * Improvement of PEO-LiCF3SO3 Complex Electrolytes Using Additives * Ionic Conductivity of Modified Poly (Methoxy Polyethylene Glycol Methacrylate) s-Lithium Salt Complexes * Solid Polymer Electrolytes of Crosslinked Polyethylene Glycol and Lithium Salts * Single Ionic Conductors Prepared by in Situ Polymerization of Methacrylic Acid

  8. Influence of ionic strength and polyelectrolyte concentration on the electrical conductivity of suspensions of soft colloidal polysaccharides.

    PubMed

    Sagou, Jean-Pierre S; Ahualli, Silvia; Thomas, Fabien; Duval, Jérôme

    2015-12-01

    The electrokinetic properties of carboxymethyldextran, a soft and anionic polysaccharide, were analysed in aqueous NaNO3 solutions through measurements of the electrical conductivity of the suspensions. The results, which furnish new experimental support for the structure of soft polysaccharides in electrolyte solution show that the polyion concentration governs the conductance behavior of the suspension as the ionic strength decreases. This is particularly evident for large polymer concentrations, for which electrical double layer overlap is more likely. In contrast, the electrical conductivity of the suspension at high ionic strength reduces to the contribution of the ions in solution, as screening of the polyion charges is more efficient in such conditions. The applicability of Ohshima's general conductivity expression to these electrical conductivity measurements was examined, and a major discrepancy against the theory was observed. The calculated values of the electrical conductivity deduced on the basis of this theory were found to be lower than the experimental ones. Possible reasons for this discrepancy are discussed and a numerical model, based on the use of a cell approach to account for hydrodynamic and electrical interactions between particles, has shown to be a good description of the experimental electrokinetic data. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Elastic strain at interfaces and its influence on ionic conductivity in nanoscaled solid electrolyte thin films--theoretical considerations and experimental studies.

    PubMed

    Schichtel, N; Korte, C; Hesse, D; Janek, J

    2009-05-07

    Ionic transport in solids parallel to grain or phase boundaries is usually strongly enhanced compared to the bulk. Transport perpendicular to an interface (across an interface) is often much slower. Therefore in modern micro- and nanoscaled devices, a severe influence on the ionic/atomic transport properties can be expected due to the high density of interfaces.Transport processes in boundaries of ionic materials are still not understood on an atomic scale. In most of the studies on ionic materials the interfacial transport properties are explained by the influence of space charge regions. Here we discuss the influence of interfacial strain at semicoherent or coherent heterophase boundaries on ionic transport along these interfaces in ionic materials. A qualitative model is introduced for (untilted and untwisted) hetero phase boundaries. For experimental verification, the interfacial oxygen ionic conductivity of different multilayer systems consisting of cubic ZrO(2) stabilised by aliovalent dopands (YSZ, CSZ) and an insulating oxide is investigated as a function of structural mismatch. Recent results on extremely fast ionic conduction in YSZ/SrTiO(3) thin film systems ("colossal ionic concuctivity at interfaces") is discussed from the viewpoint of strain effects.

  10. Application of the compensated Arrhenius formalism to self-diffusion: implications for ionic conductivity and dielectric relaxation.

    PubMed

    Petrowsky, Matt; Frech, Roger

    2010-07-08

    Self-diffusion coefficients are measured from -5 to 80 degrees C in a series of linear alcohols using pulsed field gradient NMR. The temperature dependence of these data is studied using a compensated Arrhenius formalism that assumes an Arrhenius-like expression for the diffusion coefficient; however, this expression includes a dielectric constant dependence in the exponential prefactor. Scaling temperature-dependent diffusion coefficients to isothermal diffusion coefficients so that the exponential prefactors cancel results in calculated energies of activation E(a). The exponential prefactor is determined by dividing the temperature-dependent diffusion coefficients by the Boltzmann term exp(-E(a)/RT). Plotting the prefactors versus the dielectric constant places the data on a single master curve. This procedure is identical to that previously used to study the temperature dependence of ionic conductivities and dielectric relaxation rate constants. The energies of activation determined from self-diffusion coefficients in the series of alcohols are strikingly similar to those calculated for the same series of alcohols from both dielectric relaxation rate constants and ionic conductivities of dilute electrolytes. The experimental results are described in terms of an activated transport mechanism that is mediated by relaxation of the solution molecules. This microscopic picture of transport is postulated to be common to diffusion, dielectric relaxation, and ionic transport.

  11. FTIR Spectroscopic and DC Ionic conductivity Studies of PVDF-HFP: LiBF4: EC Plasticized Polymer Electrolyte Membrane

    NASA Astrophysics Data System (ADS)

    Sangeetha, M.; Mallikarjun, A.; Jaipal Reddy, M.; Siva Kumar, J.

    2017-08-01

    In the present paper; the FTIR and Temperature dependent DC Ionic conductivity studies of polymer (80 Wt% PVDF-HFP) with inorganic lithium tetra fluoroborate salt (20 Wt% LiBF4) as ionic charge carrier and plasticized with various weight ratios of Ethylene carbonate plasticizer (10 Wt% to 70 Wt% EC) as gel polymer electrolytes. Solution casting method is used for the preparation of plasticized polymer-salt electrolyte films. FTIR analysis shows the good complexation between PVDF-HFP: LiBF4 and the presence of functional groups in the plasticized polymer-salt electrolyte membrane. Also the analysis and results show that the highest DC ionic conductivity of 1.66 × 10‑3 SCm ‑1 was found at 373 K for a particular concentration of 80 Wt% PVDF-HFP: 20 Wt% LiBF4: 40 Wt% EC porous gel type polymer-salt plasticized porous membrane. Increase of temperature results expansion and segmental motion of polymer chain that generates free volume in turn promotes hopping of the lithium ions satisfying Vogel-Tammann-Fulcher equation.

  12. Ionic conductivity of mesoporous block copolymer membranes in liquid electrolyte as a function of copolymer and homopolymer molecular weight

    NASA Astrophysics Data System (ADS)

    Wong, David; Mullin, Scott; Stone, Greg; Battaglia, Vincent; Balsara, Nitash

    2011-03-01

    Mesoporous block copolymer membranes have been synthesized using poly(styrene-block-ethylene-block-polystyrene) (SES). A series of symmetric SES copolymers and PS homopolymers have been studied at different blending fractions. Ionic conductivities of the porous films in a liquid electrolyte, 1.0 M Li PF6 in ethylene carbonate/diethyl carbonate, compare favorably to conventional battery separators and generally increase with internal surface area, as measured by nitrogen adsorption. Characterization of the effects of pore structure and SES morphology on conductivity will be presented. Support from the U.S. Department of Energy Office of Vehicles Technologies (FCVT) under the Batteries for Advanced Transportation Technologies (BATT) Program.

  13. Ionic conductivity and dielectric studies of LiClO4 doped poly(vinylalcohol)(PVA)/chitosan(CS) composites

    NASA Astrophysics Data System (ADS)

    Rathod, Sunil G.; Bhajantri, R. F.; Ravindrachary, V.; Pujari, P. K.; Sheela, T.

    2014-12-01

    This paper focuses on the dielectric constant (ɛ‧), dielectric loss factor (ɛ″) and frequency dependent conductivity (σac) properties of newly prepared poly(vinylalcohol) (PVA) chitosan (CS) composite films incorporated with different concentrations of LiClO4. The composite films were prepared using solution casting technique. The complexation between salt and polymer host is confirmed by FT Raman and UV-Vis studies. The sample containing 20 wt.% LiClO4 exhibits a highest ionic conductivity of 3 × 10-6 S/cm at room temperature. The dielectric properties of the composites follow non-Debye behavior.

  14. Cellulose acetate-lithium bis(trifluoromethanesulfonyl)imide solid polymer electrolyte: ATR-FTIR and ionic conductivity behavior

    NASA Astrophysics Data System (ADS)

    Mohd Razalli, Siti Masyitah; Sheikh Mohd Saaid, Siti Irma Yuana; Marwan Ali, Ab Malik; Hassan, Oskar Hasdinor; Yahya, Muhd Zu Azhan

    2015-05-01

    Solid polymer electrolytes (SPEs) based on cellulose acetate (CA) doped with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt are prepared by solution cast technique. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy of the polymer salt complexes are recorded in the frequency range between 400 cm-1 and 4000 cm-1. The shifting of carbonyl band (C=O) at 1737 cm-1 to a lower wavenumber confirms the occurrence of complexation between the polymer and the salt. The electrochemical impedance spectroscopy (EIS) analysis discovered that the film with 25 wt.% of salt shows the highest ionic conductivity at room temperature. The change in real dielectric permittivity (ɛr) as a function of frequency at different salt concentrations which exhibits a dispersive behavior at low frequencies and decays at higher frequencies, shows the electrode polarization and space charge effect. The real modulus formalism (Mr) analysis shows that the polymer electrolytes in this work are ionic conductors.

  15. Effect of epoxidation level on thermal properties and ionic conductivity of epoxidized natural rubber solid polymer nanocomposite electrolytes

    SciTech Connect

    Harun, Fatin; Chan, Chin Han; Winie, Tan; Sim, Lai Har; Zainal, Nurul Fatahah Asyqin

    2015-08-28

    Effect of epoxide content on the thermal and conductivity properties of epoxidized natural rubber (ENR) solid polymer nanocomposite electrolytes was investigated. Commercial available epoxidized natural rubber having 25 (ENR25) and 50 mole% (ENR50) epoxide, respectively were incorporated with lithium perchlorate (LiClO{sub 4}) salt and titanium dioxide (TiO{sub 2}) nanofiller via solution casting method. The solid polymer nanocomposite electrolytes were characterized by differential scanning calorimetry (DSC) and impedance spectroscopy (IS) for their thermal properties and conductivity, respectively. It was evident that introduction of LiClO{sub 4} causes a greater increase in glass transition temperature (T{sub g}) and ionic conductivity of ENR50 as compared to ENR25. Upon addition of TiO{sub 2} in ENR/LiClO{sub 4} system, a remarkable T{sub g} elevation was observed for both ENRs where ENR50 reveals a more pronounced changes. It is interesting to note that they exhibit different phenomenon in ionic conductivity with TiO{sub 2} loading where ENR25 shows enhancement of conductivity while ENR50 shows declination.

  16. Effect of Adding Plasticizer on Ionic Conductivity and Glass Transition Temperature of PMMA+Lithium Iodide Complexes

    NASA Astrophysics Data System (ADS)

    Zulkepely, N. R.; Majid, S. R.; Osman, Z.

    2010-07-01

    Polymer electrolyte films based on poly-methylmethacrylate (PMMA) have been prepared using the solution casting technique. Ethylene carbonate (EC) was used as a plasticizer and lithium iodide (LiI) as a doping salt. The ionic conductivity of the films was analyzed using ac impedance spectroscopy. It can be observed that the ionic conductivity of PMMA+LiI film increased when the plasticizer was added. The conductivity-temperature dependence studies were carried out in the temperature range between 303 and 393 K. The results indicate that the conductivity is increased when the temperature is increased. The glass transition temperature, Tg of the polymer electrolyte films was measured using Differential Scanning Calorimetry (DSC). The Tg of the pure PMMA film is ˜125 °C. On addition of plasticizer, it can be observed that the Tg of PMMA+LiI film is decreased. This reveals that the plasticizer, EC has reduced the Tg of the polymer electrolyte film by increasing segmental motion of the polymer resulting in conductivity enhancement.

  17. Effect of epoxidation level on thermal properties and ionic conductivity of epoxidized natural rubber solid polymer nanocomposite electrolytes

    NASA Astrophysics Data System (ADS)

    Harun, Fatin; Chan, Chin Han; Sim, Lai Har; Winie, Tan; Zainal, Nurul Fatahah Asyqin

    2015-08-01

    Effect of epoxide content on the thermal and conductivity properties of epoxidized natural rubber (ENR) solid polymer nanocomposite electrolytes was investigated. Commercial available epoxidized natural rubber having 25 (ENR25) and 50 mole% (ENR50) epoxide, respectively were incorporated with lithium perchlorate (LiClO4) salt and titanium dioxide (TiO2) nanofiller via solution casting method. The solid polymer nanocomposite electrolytes were characterized by differential scanning calorimetry (DSC) and impedance spectroscopy (IS) for their thermal properties and conductivity, respectively. It was evident that introduction of LiClO4 causes a greater increase in glass transition temperature (Tg) and ionic conductivity of ENR50 as compared to ENR25. Upon addition of TiO2 in ENR/LiClO4 system, a remarkable Tg elevation was observed for both ENRs where ENR50 reveals a more pronounced changes. It is interesting to note that they exhibit different phenomenon in ionic conductivity with TiO2 loading where ENR25 shows enhancement of conductivity while ENR50 shows declination.

  18. An experimental study of perovskite-structured mixed ionic- electronic conducting oxides and membranes

    NASA Astrophysics Data System (ADS)

    Zeng, Pingying

    In recent decades, ceramic membranes based on mixed ionic and electronic conducting (MIEC) perovskite-structured oxides have received many attentions for their applications for air separation, or as a membrane reactor for methane oxidation. While numerous perovskite oxide materials have been explored over the past two decades; there are hardly any materials with sufficient practical economic value and performance for large scale applications, which justifies continuing the search for new materials. The main purposes of this thesis study are: (1) develop several novel SrCoO3-delta based MIEC oxides, SrCoCo1-xMxO3-delta, based on which membranes exhibit excellent oxygen permeability; (2) investigate the significant effects of the species and concentration of the dopants M (metal ions with fixed valences) on the various properties of these membranes; (3) investigate the significant effects of sintering temperature on the microstructures and performance of oxygen permeation membranes; and (4) study the performance of oxygen permeation membranes as a membrane reactor for methane combustion. To stabilize the cubic phase structure of the SrCoO3-delta oxide, various amounts of scandium was doped into the B-site of SrCoO 3-delta to form a series of new perovskite oxides, SrScxCoCo 1-xO3-delta (SSCx, x = 0-0.7). The significant effects of scandium-doping concentration on the phase structure, electrical conductivity, sintering performance, thermal and structural stability, cathode performance, and oxygen permeation performance of the SSCx membranes, were systematically studied. Also for a more in-depth understanding, the rate determination steps for the oxygen transport process through the membranes were clarified by theoretical and experimental investigation. It was found that only a minor amount of scandium (5 mol%) doping into the B-site of SrCoO3-delta can effectively stabilize the cubic phase structure, and thus significantly improve the electrical conductivity and

  19. Monitoring the ionic content of exhaled breath condensate in various respiratory diseases by capillary electrophoresis with contactless conductivity detection.

    PubMed

    Greguš, Michal; Foret, František; Kindlová, Dagmar; Pokojová, Eva; Plutinský, Marek; Doubková, Martina; Merta, Zdeněk; Binková, Ilona; Skřičková, Jana; Kubáň, Petr

    2015-05-06

    The analysis of an ionic profile of exhaled breath condensate (EBC) by capillary electrophoresis with contactless conductivity detection and double opposite end injection, is demonstrated. A miniature sampler made from a 2 ml syringe and an aluminium cooling cylinder was used for the fast collection of EBC (under one minute). Analysis of the collected EBC was performed in a 60 mM 2-(N-morpholino)ethanesulfonic acid, 60 mM L-histidine background electrolyte with 30 µM cetyltrimethylammonium bromide and 2 mM 18-crown-6 at pH 6, and excellent repeatability of migration times (RSD  <1.3% (n = 7)) and peak areas (RSD  <  7% (n = 7)) of 14 ions (inorganic anions, cations and organic acids) was obtained. It is demonstrated that the analysis of EBC samples obtained from patients with various respiratory diseases (chronic obstructive pulmonary disease, asthma, pulmonary fibrosis, sarcoidosis, cystic fibrosis) is possible in less than five minutes and the ionic profile can be compared with the group of healthy individuals. The analysis of the ionic profile of EBC samples provides a set of data in which statistically significant differences among the groups of patients could be observed for several clinically relevant anions (nitrite, nitrate, acetate, lactate). The developed collection system and method provides a highly reproducible and fast way of collecting and analyzing EBC, with future applicability in point-of-care diagnostics.

  20. Anisotropy of ionic conduction in single-crystal Li x La(1- x )/3NbO3 solid electrolyte grown by directional solidification

    NASA Astrophysics Data System (ADS)

    Fujiwara, Yasuyuki; Taishi, Toshinori; Hoshikawa, Keigo; Kohama, Keiichi; Iba, Hideki

    2016-09-01

    The anisotropy of ionic conduction in a solid electrolyte (Li x La(1- x )/3NbO3) was experimentally confirmed for the first time. Ionic conduction measurements were carried out on the (100), (010), (001), (110), (111), and (112) planes of single-crystal ingots of Li x La(1- x )/3NbO3 grown by directional solidification. We found that the ionic conductivity in Li x La(1- x )/3NbO3 with x = 0.08 was 3.6 × 10-4 S cm-1 in the [100] and [010] directions, approximately 10 times higher than that in the [001] direction. Such anisotropy of the ionic conduction is discussed with respect to the characteristic layered structure of Li x La(1- x )/3NbO3.

  1. Ionic Conductivity and Air Stability of Al-Doped Li₇La₃Zr₂O₁₂ Sintered in Alumina and Pt Crucibles.

    PubMed

    Xia, Wenhao; Xu, Biyi; Duan, Huanan; Guo, Yiping; Kang, Hongmei; Li, Hua; Liu, Hezhou

    2016-03-02

    Li7La3Zr2O12 (LLZO) is a promising electrolyte material for all-solid-state battery due to its high ionic conductivity and good stability with metallic lithium. In this article, we studied the effect of crucibles on the ionic conductivity and air stability by synthesizing 0.25Al doped LLZO pellets in Pt crucibles and alumina crucibles, respectively. The results show that the composition and microstructure of the pellets play important roles influencing the ionic conductivity, relative density, and air stability. Specifically, the 0.25Al-LLZO pellets sintered in Pt crucibles exhibit a high relative density (∼96%) and high ionic conductivity (4.48 × 10(-4) S cm(-1)). The ionic conductivity maintains 3.6 × 10(-4) S cm(-1) after 3-month air exposure. In contrast, the ionic conductivity of the pellets from alumina crucibles is about 1.81 × 10(-4) S cm(-1) and drops to 2.39 × 10(-5) S cm(-1) 3 months later. The large grains and the reduced grain boundaries in the pellets sintered in Pt crucibles are favorable to obtain high ionic conductivity and good air stability. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy results suggest that the formation of Li2CO3 on the pellet surface is probably another main reason, which is also closely related to the relative density and the amount of grain boundary within the pellets. This work stresses the importance of synthesis parameters, crucibles included, to obtain the LLZO electrolyte with high ionic conductivity and good air stability.

  2. Electrochemical activity and high ionic conductivity of lithium copper pyroborate Li6CuB4O10.

    PubMed

    Strauss, Florian; Rousse, Gwenaëlle; Alves Dalla Corte, Daniel; Ben Hassine, Mohamed; Saubanère, Matthieu; Tang, Mingxue; Vezin, Hervé; Courty, Matthieu; Dominko, Robert; Tarascon, Jean-Marie

    2016-06-01

    In the search for new cathode materials for Li-ion batteries, borate (BO3(3-)) based compounds have gained much interest during the last two decades due to the low molecular weight of the borate polyanions which leads to active materials with increased theoretical capacities. In this context we herein report the electrochemical activity versus lithium and the ionic conductivity of a diborate or pyroborate B2O5(4-) based compound, Li6CuB4O10. By combining various electrochemical techniques with in situ X-ray diffraction, we show that this material can reversibly insert/deinsert limited amounts of lithium (∼0.3 Li(+)) in a potential window ranging from 2.5 to 4.5 V vs. Li(+)/Li(0). We demonstrate, via electron paramagnetic resonance (EPR), that such an electrochemical activity centered near 4.25 V vs. Li(+)/Li(0) is associated with the Cu(3+)/Cu(2+) redox couple, confirmed by density functional theory (DFT) calculations. Another specificity of this compound lies in its different electrochemical behavior when cycled down to 1 V vs. Li(+)/Li(0) which leads to the extrusion of elemental copper via a conversion type reaction as deduced by transmission electron microscopy (TEM). Lastly, we probe the ionic conductivity by means of AC and DC impedance measurements as a function of temperature and show that Li6CuB4O10 undergoes a reversible structural transition around 350 °C, leading to a surprisingly high ionic conductivity of ∼1.4 mS cm(-1) at 500 °C.

  3. A correlation between the ionic conductivities and the formation enthalpies of trivalent-doped ceria at relatively low temperatures.

    PubMed

    Avila-Paredes, Hugo J; Shvareva, Tatiana; Chen, Weiqun; Navrotsky, Alexandra; Kim, Sangtae

    2009-10-14

    We report a correlation between oxygen ionic conductivity and the enthalpy of formation of trivalent-doped ceria from the component binary oxides observed at relatively low temperatures (150-275 degrees C). The bulk conductivities of La-doped ceria samples identical to those previously examined by thermochemical studies were measured as a function of La content for a direct comparison. The conductivity showed a maximum at a La concentration of 5 mol%, implying that the number of freely mobile oxygen vacancies reaches a maximum near that doping level in the temperature range of interest. The formation enthalpies previously reported by Chen and Navrotsky also show a maximum, indicating destabilization near that composition. Additional measurements show that this maximum is very pronounced and sharply peaked near that composition. These enthalpies suggest that the energetically favorable long-range interactions between the charged defects that trap the oxygen vacancies become dominant above 5 mol% doping in the CeO2-LaO1.5 solid solution. In addition, the conductivities measured from independently prepared Gd-doped ceria samples show a maximum at around 10 mol% doping below 450 degrees C as anticipated from a pronounced maximum in the formation enthalpies of the CeO2-GdO1.5 solid solution. These empirical findings confirm that the ionic conductivity of trivalent-doped ceria is strongly enough correlated with its formation enthalpy at relatively low temperatures so that information about the critical dopant concentration associated with the conductivity maximum may be gained from the formation enthalpies of the solid solutions, and vice versa. We have no direct information about this correlation at higher temperatures; both thermodynamics and conductivity maximum might change if the defect clusters dissociate to any significant extent.

  4. Crystal structure and ionic conductivity of the new cobalt polyphosphate NaCo(PO3)3

    NASA Astrophysics Data System (ADS)

    Ben Smida, Youssef; Guesmi, Abderrahmen; Georges, Samuel; Avdeev, Maxim; Zid, Mohamed Faouzi

    2016-02-01

    Polycrystalline sample of sodium cobalt triphosphate NaCo(PO3)3 was obtained by solid-state reaction and characterized by X-ray powder diffraction. The title compound is isostructural to NaZn(PO3)3 and its structure was refined by the Rietveld refinement in the cubic system, space group Pa 3 ̅, with a=14.2484(4) Å. The obtained structural model is supported by bond valence sum (BVS) and charge distribution (CD) methods. The structure is described as a three-dimensional open-anionic framework built up of corner-sharing CoO6 and PO4 polyhedra with interconnecting channels along the 3-axis, in which the Na+ cations are located. The ionic conductivity measurements are performed on pellets with relative density of 84%. The electrical conductivity is 1.01×10-5 S cm-1 at 480 °C and the activation energy deduced from the slope is 1.1 eV. The correlation between crystal structure and ionic conductivity was studied by the means of the bond-valence-site-energy (BVSE) model. The main result is that sodium transport is made mainly via Na2 and Na3 sites.

  5. Consistent prediction of streaming potential in non-Newtonian fluids: the effect of solvent rheology and confinement on ionic conductivity.

    PubMed

    Bandopadhyay, Aditya; Chakraborty, Suman

    2015-03-21

    By considering an ion moving inside an imaginary sphere filled with a power-law fluid, we bring out the implications of the fluid rheology and the influence of the proximity of the other ions towards evaluating the conduction current in an ionic solution. We show that the variation of the conductivity as a function of the ionic concentration is both qualitatively and quantitatively similar to that predicted by the Kohlrausch law. We then utilize this consideration for estimating streaming potentials developed across narrow fluidic confinements as a consequence of the transport of ions in a convective medium constituting a power-law fluid. These estimates turn out to be in sharp contrast to the classical estimates of streaming potential for non-Newtonian fluids, in which the effect of rheology of the solvent is merely considered to affect the advection current, disregarding its contributions to the conduction current. Our results have potential implications of devising a new paradigm of consistent estimation of streaming potentials for non-Newtonian fluids, with combined considerations of the confinement effect and fluid rheology in the theoretical calculations.

  6. Ionic channels and conductance-based models for hypothalamic neuronal thermosensitivity.

    PubMed

    Wechselberger, Martin; Wright, Chadwick L; Bishop, Georgia A; Boulant, Jack A

    2006-09-01

    Thermoregulatory responses are partially controlled by the preoptic area and anterior hypothalamus (PO/AH), which contains a mixed population of temperature-sensitive and insensitive neurons. Immunohistochemical procedures identified the extent of various ionic channels in rat PO/AH neurons. These included pacemaker current channels [i.e., hyperpolarization-activated cyclic nucleotide-gated channels (HCN)], background potassium leak channels (TASK-1 and TRAAK), and transient receptor potential channel (TRP) TRPV4. PO/AH neurons showed dense TASK-1 and HCN-2 immunoreactivity and moderate TRAAK and HCN-4 immunoreactivity. In contrast, the neuronal cell bodies did not label for TRPV4, but instead, punctate labeling was observed in traversing axons or their terminal endings. On the basis of these results and previous electrophysiological studies, Hodgkin-Huxley-like models were constructed. These models suggest that most PO/AH neurons have the same types of ionic channels, but different levels of channel expression can explain the inherent properties of the various types of temperature-sensitive and insensitive neurons.

  7. Electro-osmotic pumping and ionic conductance measurements in porous membranes

    NASA Astrophysics Data System (ADS)

    Vajandar, Saumitra K.

    fabricated out of heavily doped silicon wafers using microfabrication techniques. The pores have a 15 mum x 40 mum cross sectional area with a thin layer of SiNx coated conformally over the pores by low-pressure chemical vapor deposition (LPCVD). The range of gate voltages applied was from -45 V to + 40 V. For Vg < 0, current leakage through the SiNx film was observed whereas negligible leaking current was detected for Vg > 0. This current rectification effect is known as electrolytic rectification, as a result of which a greater EO flow control, nearly 70% reduction in flow velocity, was observed for positive gate bias and 15% flow velocity enhancement under negative gate bias of similar magnitude. Ionic current is closely related to EO flow and the last part of the dissertation is devoted to ionic current measurements through commercially made nanoporous glass membranes (4 nm average pore diameter). This study was motivated by a molecular dynamics (MD) simulation highlighting an unusual ionic current trend in a 3 nm diameter pore having high surface charge density at high electrolyte concentrations. The ionic current was measured with two kinds of electrolytes---NaCl and KCl. The experimental results, however, indicated an expected linear trend of ionic current for electrolyte concentrations beyond 1 M, contrary to the results of the MD simulation study, which was attributed to a low surface charge density measured for the porous glass membranes.

  8. Influence of Al2O3 on the ionic conductivity of plasticized PVC-PEG blend polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Ravindran, D.; Vickraman, P.

    2016-05-01

    Polymer electrolytes with PVC-PEG blend as host matrix and LiClO4 as dopant salt was prepared through conventional solution casting method. To enhance the conductivity propylene carbonate (PC) was used as plasticizer. The influence of ceramic filler Al2O3 on the conductivity of the electrolyte films were studied by varying the (PVC: Al2O3) ratio. The films were subjected to XRD, complex impedance analysis and SEM analysis. The XRD studies reveal a marginal increase in the amorphous phase of the electrolyte films due to the incorporation of filler. The AC impedance analysis shows the dependency of ionic conductivity on the content (wt %) of filler and exhibit a maximum at 4 wt% filler. The SEM analysis depicts the occurrence of phase separation in electrolyte which is attributed to the poor solubility of polymer PVC in the liquid electrolyte.

  9. Investigation of Ionic Conductivity of Nanocomposite Polymer Electrolytes Based On PVDF-HFP/PVC Blend, LiClO4 and TiO2 Nanofiller

    NASA Astrophysics Data System (ADS)

    Basri, N. H.; Mohamed, N. S.

    2010-07-01

    The effects of nanosized TiO2 on the conductivity of PVDF-HFP/PVC-LiClO4 was studied by means of impedance spectroscopy and x-ray diffraction (XRD). The addition of TiO2 nanofiller increases the crystalline phase fraction but slightly increases the conductivity of the PVDF-HFP/PVC-LiClO4 complex. The increase in conductivity is attributed to the formation of highly conducting layer at the electrolyte/filler interface. The temperature dependence of conductivity obeys the VTF type behaviour while the transference number confirms that the electrolyte containing 6 wt.% TiO2 is an ionic conductor are ionic conductors.

  10. Influence of Lattice Polarizability on the Ionic Conductivity in the Lithium Superionic Argyrodites Li6PS5X (X = Cl, Br, I).

    PubMed

    Kraft, Marvin A; Culver, Sean P; Calderon, Mario; Böcher, Felix; Krauskopf, Thorben; Senyshyn, Anatoliy; Dietrich, Christian; Zevalkink, Alexandra; Janek, Jürgen; Zeier, Wolfgang G

    2017-08-09

    In the search for novel solid electrolytes for solid-state batteries, thiophosphate ionic conductors have been in recent focus owing to their high ionic conductivities, which are believed to stem from a softer, more polarizable anion framework. Inspired by the oft-cited connection between a soft anion lattice and ionic transport, this work aims to provide evidence on how changing the polarizability of the anion sublattice in one structure affects ionic transport. Here, we systematically alter the anion framework polarizability of the superionic argyrodites Li6PS5X by controlling the fractional occupancy of the halide anions (X = Cl, Br, I). Ultrasonic speed of sound measurements are used to quantify the variation in the lattice stiffness and Debye frequencies. In combination with electrochemical impedance spectroscopy and neutron diffraction, these results show that the lattice softness has a striking influence on the ionic transport: the softer bonds lower the activation barrier and simultaneously decrease the prefactor of the moving ion. Due to the contradicting influence of these parameters on ionic conductivity, we find that it is necessary to tailor the lattice stiffness of materials in order to obtain an optimum ionic conductivity.

  11. Lithium ionic conduction and relaxation dynamics of spark plasma sintered Li5La3Ta2O12 garnet nanoceramics.

    PubMed

    Ahmad, Mohamad M

    2015-01-01

    In the present work, nanoceramics of Li5La3Ta2O12 (LLT) lithium ion conductors with the garnet-like structure are fabricated by spark plasma sintering (SPS) technique at different temperatures of 850°C, 875°C, and 900°C (SPS-850, SPS-875, and SPS-900). The grain size of the SPS nanoceramics is in the 50 to 100 nm range, indicating minimal grain growth during the SPS experiments. The ionic conduction and relaxation properties of the current garnets are studied by impedance spectroscopy (IS) measurements. The SPS-875 garnets exhibit the highest total Li ionic conductivity of 1.25 × 10(-6) S/cm at RT, which is in the same range as the LLT garnets prepared by conventional sintering technique. The high conductivity of SPS-875 sample is due to the enhanced mobility of Li ions by one order of magnitude compared to SPS-850 and SPS-900 ceramics. The concentration of mobile Li(+) ions, n c, and their mobility are estimated from the analysis of the conductivity spectra at different temperatures. n c is found to be independent of temperature for the SPS nanoceramics, which implies that the conduction process is controlled by the Li(+) mobility. Interestingly, we found that only a small fraction of lithium ions of 3.9% out of the total lithium content are mobile and contribute to the conduction process. Moreover, the relaxation dynamics in the investigated materials have been studied through the electric modulus formalism.

  12. Monte Carlo simulation of diffusion and ionic conductivity in a simple cubic random alloy via the interstitialcy mechanism

    NASA Astrophysics Data System (ADS)

    Wilangowski, F.; Stolwijk, N. A.

    2015-12-01

    This Monte Carlo study deals with mass and charge transport in binary ionic alloys governed by interstitialcy defects acting as diffusion vehicles. In particular, we calculate tracer correlation factors {{f}\\text{A}} and {{f}\\text{B}} in a simple cubic random alloy AB for diffusion via the collinear interstitialcy mechanism as a function of composition and jump frequency ratio {{w}\\text{A}}\\ll {{w}\\text{B}} . Interstitialcy correlation factors {{f}\\text{I}} , which play a crucial role in the interpretation of ion-conductivity data, are also determined. The evaluation of partial correlation factors provides insight into the types of jumps that mostly contribute to the different transport processes under consideration. Examination of the percolation behaviour yields the site-percolation threshold of the mobile component B for {{w}\\text{A}}=0 . Surprisingly, a unique second-order threshold composition is found, which relates to the abundance of different interstitialcy jump types when {{w}\\text{A}}/{{w}\\text{B}} . Both numerically obtained threshold values are accurately reproduced by estimated analytical expressions based on simple arguments. Practical implications of the simulation results are explored by calculating tracer diffusivity ratios D\\text{A}*/D\\text{B}* and by comparing self-diffusion with ionic conductivity using the Nernst-Einstein equation.

  13. Surfactant-free ionic liquid-based nanofluids with remarkable thermal conductivity enhancement at very low loading of graphene

    PubMed Central

    2012-01-01

    We report for the first time the preparation of highly stable graphene (GE)-based nanofluids with ionic liquid as base fluids (ionic liquid-based nanofluids (Ionanofluids)) without any surfactant and the subsequent investigations on their thermal conductivity, specific heat, and viscosity. The microstructure of the GE and MWCNTs are observed by transmission electron microscope. Thermal conductivity (TC), specific heat, and viscosity of these Ionanofluids were measured for different weight fractions and at varying temperatures, demonstrating that the Ionanofluids exhibit considerably higher TC and lower viscosity than that of their base fluids without significant specific heat decrease. An enhancement in TC by about 15.5% and 18.6% has been achieved at 25 °C and 65 °C respectively for the GE-based nanofluid at mass fraction of as low as 0.06%, which is larger than that of the MWCNT-dispersed nanofluid at the same loading. When the temperature rises, the TC and specific heat of the Ionanofluid increase clearly, while the viscosity decreases sharply. Moreover, the viscosity of the prepared Ionanofluids is lower than that of the base fluid. All these advantages of this new kind of Ionanofluid make it an ideal fluid for heat transfer and thermal storage. PMID:22713249

  14. Polyethylene separator activated by hybrid coating improving Li+ ion transference number and ionic conductivity for Li-metal battery

    NASA Astrophysics Data System (ADS)

    Mao, Xufeng; Shi, Liyi; Zhang, Haijiao; Wang, Zhuyi; Zhu, Jiefang; Qiu, Zhengfu; Zhao, Yin; Zhang, Meihong; Yuan, Shuai

    2017-02-01

    Low Li+ ion transference number is one fatal defect of the liquid LiPF6 electrolyte for Li-metal anode based batteries. This work aims to improve Li+ ion transference number and ionic conductivity polyethylene (PE) separators. By a simple dip-coating method, the water-borne nanosized molecular sieve with 3D porous structure (ZSM-5) can be coated on PE separators. Especially, the Li+ ion transference number is greatly enhanced from 0.28 to 0.44, which should be attributed to the specific pore structure and channel environment of ZSM-5 as well as the interaction between ZSM-5 and electrolyte. Compared with the pristine PE separator, the ionic conductivity of modified separators is remarkably improved from 0.30 to 0.54 mS cm-1. As results, the C-rate capability and cycling stability are both improved. The Li-metal battery using the ZSM-5-modified PE separator keeps 94.2% capacity after 100 cycles. In contrast, the discharge capacity retention of the battery using pristine PE is only 74.7%.

  15. Irreversible change of electric conduction in ionic-liquid-gated (La,Sr)MnO3 thin films

    NASA Astrophysics Data System (ADS)

    Lee, Tae Kwon; Jung, Jong Hoon

    2016-10-01

    We have investigated the ionic-liquid-gating effect on electric conduction in (La0.8Sr0.2)MnO3(LSMO) thin films. The gating effect is significant for the LSMO thin films grown at low oxygen partial pressures. We observed that the channel resistance of LSMO was altered only for a positive gating voltage, not for a negative one, mainly through the changes of mobility rather than the carrier density. The increased sheet resistance at positive voltage does not return to the original value even after the removal of gating voltage as well as the application of a negative voltage. Through the Mn 2 p X-ray absorption, the increased resistance of LSMO after a positive voltage is found to be associated with the increase of the Mn3+ ions over Mn4+ ones. We proposed that oxygen vacancy and electrochemical reactions should play a role for the irreversible electric conduction in ionic-liquid-gated (La,Sr)MnO3 thin films.

  16. Monte Carlo simulation of diffusion and ionic conductivity in a simple cubic random alloy via the interstitialcy mechanism.

    PubMed

    Wilangowski, F; Stolwijk, N A

    2015-12-23

    This Monte Carlo study deals with mass and charge transport in binary ionic alloys governed by interstitialcy defects acting as diffusion vehicles. In particular, we calculate tracer correlation factors f(A) and f(B) in a simple cubic random alloy AB for diffusion via the collinear interstitialcy mechanism as a function of composition and jump frequency ratio wA/wB. [corrected]. Interstitialcy correlation factors f(I), which play a crucial role in the interpretation of ion-conductivity data, are also determined. The evaluation of partial correlation factors provides insight into the types of jumps that mostly contribute to the different transport processes under consideration. Examination of the percolation behaviour yields the site-percolation threshold of the mobile component B for w(A) = 0. Surprisingly, a unique second-order threshold composition is found, which relates to the abundance of different interstitialcy jump types when wA < wB [corrected]. Both numerically obtained threshold values are accurately reproduced by estimated analytical expressions based on simple arguments. Practical implications of the simulation results are explored by calculating tracer diffusivity ratios D*(A)/D*(B) and by comparing self-diffusion with ionic conductivity using the Nernst-Einstein equation.

  17. Enhanced ionic conductivity with Li7O2Br3 phase in Li3OBr anti-perovskite solid electrolyte

    NASA Astrophysics Data System (ADS)

    Zhu, Jinlong; Li, Shuai; Zhang, Yi; Howard, John W.; Lü, Xujie; Li, Yutao; Wang, Yonggang; Kumar, Ravhi S.; Wang, Liping; Zhao, Yusheng

    2016-09-01

    Cubic anti-perovskites with general formula Li3OX (X = Cl, Br, I) were recently reported as superionic conductors with the potential for use as solid electrolytes in all-solid-state lithium ion batteries. These electrolytes are nonflammable, low-cost, and suitable for thermoplastic processing. However, the primary obstacle of its practical implementation is the relatively low ionic conductivity at room temperature. In this work, we synthesized a composite material consisting of two anti-perovskite phases, namely, cubic Li3OBr and layered Li7O2Br3, by solid state reaction routes. The results indicate that with the phase fraction of Li7O2Br3 increasing to 44 wt. %, the ionic conductivity increased by more than one order of magnitude compared with pure phase Li3OBr. Formation energy calculations revealed the meta-stable nature of Li7O2Br3, which supports the great difficulty in producing phase-pure Li7O2Br3 at ambient pressure. Methods of obtaining phase-pure Li7O2Br3 will continue to be explored, including both high pressure and metathesis techniques.

  18. Enhanced ionic conductivity with Li7O2Br3 phase in Li3OBr anti-perovskite solid electrolyte

    DOE PAGES

    Zhu, Jinlong; Li, Shuai; Zhang, Yi; ...

    2016-09-07

    Cubic anti-perovskites with general formula Li3OX (X = Cl, Br, I) were recently reported as superionic conductors with the potential for use as solid electrolytes in all-solid-state lithium ion batteries. These electrolytes are nonflammable, low-cost, and suitable for thermoplastic processing. However, the primary obstacle of its practical implementation is the relatively low ionic conductivity at room temperature. In this work, we synthesized a composite material consisting of two anti-perovskite phases, namely, cubic Li3OBr and layered Li7O2Br3, by solid state reaction routes. The results indicate that with the phase fraction of Li7O2Br3 increasing to 44 wt. %, the ionic conductivity increasedmore » by more than one order of magnitude compared with pure phase Li3OBr. Formation energy calculations revealed the meta-stable nature of Li7O2Br3, which supports the great difficulty in producing phase-pure Li7O2Br3 at ambient pressure. Here, methods of obtaining phase-pure Li7O2Br3 will continue to be explored, including both high pressure and metathesis techniques.« less

  19. Fast ionic conduction in tetravalent metal pyrophosphate-alkali carbonate composites: New potential electrolytes for intermediate-temperature fuel cells

    NASA Astrophysics Data System (ADS)

    Singh, Bhupendra; Bhardwaj, Aman; Gautam, Sandeep K.; Kumar, Devendra; Parkash, Om; Kim, In-Ho; Song, Sun-Ju

    2017-03-01

    Here we present a report on synthesis and characterization of tetravalent metal pyrophosphate (TMP) and alkali carbonate (A2CO3; A = Li and/or Na) composites. The TMP-carbonate composites are prepared by mixing indium-doped tin pyrophosphate or yttrium-doped zirconium pyrophosphate with Li2CO3 or an eutectic mixture of Li2CO3-Na2CO3 in different wt.% ratios. The phase composition, microstructure and electrical conductivity of the sintered specimen are analyzed. In addition, the effect of different TMP and A2CO3 phases is investigated. A maximum ionic conductivity of 5.5 × 10-2 S cm-1 at 630 °C is observed in this study with a Sn0.9In0.1P2O7-Li2CO3 composite. Based on the literature data, TMP-carbonate composites can be considered to be primarily a proton and oxygen-ion co-ionic conductor and, therefore, have strong potential as electrolytes in fuel cells in 500-700 °C range.

  20. Investigation into the impact of grain boundaries, film interface, and crystallographic orientation on the ionic conductivity of thin film gadolinium-doped ceria

    NASA Astrophysics Data System (ADS)

    Swanson, Matthew M.

    The research reported in this dissertation investigates the impact of grain boundaries, film interface, and crystallographic orientation on the ionic conductivity of thin film Gd-doped CeO2 (GDC). Chapter 2 of this work addresses claims in the literature that sub-micron grain boundaries have the potential to dramatically increase the ionic conductivity of GDC films. Unambiguous testing of this claim requires directly comparing the ionic conductivity of single-crystal GDC films to films that are identical except for the presence of sub-micron grain boundaries. In this work techniques have been developed to grow GDC films by RF magnetron sputtering from a GDC target on single crystal r-plane sapphire substrates. These techniques allow the growth of films that are single crystals or polycrystalline with 80 nm diameter grains. The ionic conductivities of these films have been measured and the data shows that the ionic conductivity of single crystal GDC is greater than that of the polycrystalline films by more than a factor of 4 over the 400-700°C temperature range. Chapter 3 of this work investigates the ionic conductivity of surface and interface regions of thin film Gd-doped CeO2. In this study, single crystal GDC films have been grown to thicknesses varying from 20 to 500 nm and their conductivities have been measured in the 500-700°C temperature range. Decreasing conductivity with decreasing film thickness was observed. Analysis of the conductivity data is consistent with the presence of an approximately 50 nm layer of less conductive material in every film. This study concludes that the surface and interface regions of thin film GDC are less conductive than the bulk single crystal regions, rather than being highly conductive paths. Chapter 4 of this work investigates the ionic conductivity of thin film Gd-doped CeO2 (GDC) as a function of crystallographic orientation. A theoretical expression has been developed for the ionic conductivity of the [100] and [110

  1. Analysis of cationic structure in some room-temperature molten fluorides and dependence of their ionic conductivity and viscosity on hydrofluoric acid concentration.

    PubMed

    Isogai, Tomohiro; Nakai, Takaaki; Inoue, Hidemi; Nakanishi, Kenta; Kohara, Shinji; Saito, Morihiro; Inaba, Minoru; Tasaka, Akimasa

    2011-08-11

    To understand the ionic and nonionic species in (CH(3))(4)NF·mHF, (CH(3))(3)N·mHF, (C(2)H(5))(4)NF·mHF, and (C(2)H(5))(3)N·mHF melts, the structures of these melts were investigated by infrared spectroscopy, NMR, and high-energy X-ray diffraction. Infrared spectra revealed that three kinds of fluorohydrogenate anions, (FH)(n)F(-) (n = 1, 2, and 3), and molecular hydrofluoric acid (HF) are present in every melt. Ionic conductivity and viscosity of these melts were measured and correlated with their cationic structure. The ionic conductivity of the R(4)N(+)-systems was higher than that of corresponding R(3)NH(+)-systems because a strong N-H···F(HF)(n) interaction prevents the motion of R(3)NH(+) cations in the R(3)N·mHF melts. (CH(3))(4)N(+) and (CH(3))(3)NH(+) cations gave higher ionic conductivity than (C(2)H(5))(4)N(+) and (C(2)H(5))(3)NH(+) cations, respectively, because the ionic radii of former cations were smaller than those of latter. It was concluded that these effects on ionic conductivity can be explained by the cationic structure and the concentration of molecular HF in the melts.

  2. Investigation of the Ionic conductivity and dielectric measurements of poly (N-vinyl pyrrolidone)-sulfamic acid polymer complexes

    NASA Astrophysics Data System (ADS)

    Daries Bella, R. S.; Karthickprabhu, S.; Maheswaran, A.; Amibika, C.; Hirankumar, G.; Devaraj, Premanand

    2015-02-01

    Polymer electrolyte complexes of poly (N-vinyl pyrrolidone) (PVP)-sulfamic acid (NH2SO3H) were prepared by a familiar solution casting method with different molar concentrations of PVP and sulfamic acid. The interaction between PVP and NH2SO3H was confirmed by Fourier transform infrared spectroscopy analysis. Laser microscopy analysis was used to study the surface morphology of the polymer complexes. The glass transition temperature (Tg) and the melting temperature (Tm) of polymer complexes were computed from Differential scanning calorimetric studies. AC impedance spectroscopic measurements revealed that the polymer complex, 97 mol% PVP-3 mol% NH2SO3H shows higher ionic conductivity with two different activation energies above and below the glass transition temperature (Tg). Dielectric studies confirmed that the dc conduction mechanism has dominated in the polymer complexes. The value of power law exponent (n) confirmed the translational motion of ions from one site to another vacant site in these complexes.

  3. Enhanced ionic conductivity of co-doped ceria-carbonate nano composite electrolyte material for LT-SOFCs

    NASA Astrophysics Data System (ADS)

    Venkataramana, Kasarapu; Madhuri, Chittimadula; Reddy, C. Vishnuvardhan

    2017-05-01

    Co-doped ceria Ce0.8Sm0.1Y0.12-δ and co-doped ceria-carbonate nano composite Ce0.8Sm0.1Y0.1O2-δ - (Na-K)2CO3 used as electrolytes in low temperature solid oxide fuel cells (LT-SOFCs) were synthesized. Structural and morphological studies were characterized by XRD and SEM. Electrical conductivity measurements were carried out by using Impedance Spectroscopy in the temperature range of 100 to 500°C. It was observed that the co-doped ceria-carbonate Nano composite material exhibited high ionic conductivity than that of co-doped ceria making it useful as promising electrolyte material for LT-SOFCs.

  4. Phase stability and ionic conductivity in substituted La{sub 2}W{sub 2}O{sub 9}

    SciTech Connect

    Marrero-Lopez, D.

    2008-02-15

    Different substitutions, i.e. Sr{sup 2+}, Ba{sup 2+}, K{sup +}, Nb{sup 5+} and V{sup 5+}, have been performed in the triclinic {alpha}-La{sub 2}W{sub 2}O{sub 9} structure in order to stabilise the high temperature and better ionic conductor cubic {beta}-phase. This approach has been used to try to obtain a new series of ionic conductors with LAMOX-type structure without molybdenum and presumably better redox stability compared to {beta}-La{sub 2}Mo{sub 2}O{sub 9}. Nanocrystalline materials obtained by a freeze-drying precursor method at 600 deg. C exhibit mainly the {beta}-La{sub 2}W{sub 2}O{sub 9} structure, however, the triclinic {alpha}-form is stabilised as the firing temperature increases and the crystallite size grows. Only high levels of Ba{sup 2+} and V{sup 5+} substitutions retained the cubic form at room temperature after firing above 1100 deg. C. However, these phases are metastable above 700 deg. C, exhibiting an irreversible transformation to the low temperature triclinic {alpha}-phase. The synthesis, structure, phase stability, kinetic of phase transformation and electrical conductivity of these materials have been studied in the present report. - Graphical abstract: Several substitutions have been tested in order to investigate the stabilisation of the high temperature cubic {beta}-La{sub 2}W{sub 2}O{sub 9} and to obtain new ionic conductors with LAMOX structure without molybdenum composition.

  5. Pair distribution function analysis of sulfide glassy electrolytes for all-solid-state batteries: Understanding the improvement of ionic conductivity under annealing condition.

    PubMed

    Shiotani, Shinya; Ohara, Koji; Tsukasaki, Hirofumi; Mori, Shigeo; Kanno, Ryoji

    2017-08-01

    In general, the ionic conductivity of sulfide glasses decreases with their crystallization, although it increases for a few sulphide glasses owing to the crystallization of a highly conductive new phase (e.g., Li7P3S11: 70Li2S-30P2S5). We found that the ionic conductivity of 75Li2S-25P2S5 sulfide glass, which consists of glassy and crystalline phases, is improved by optimizing the conditions of the heat treatment, i.e., annealing. A different mechanism of high ionic conductivity from the conventional mechanism is expected in the glassy phase. Here, we report the glassy structure of 75Li2S-25P2S5 immediately before the crystallization by using the differential pair distribution function (d-PDF) analysis of high-energy X-ray diffraction. Even though the ionic conductivity increases during the optimum annealing, the d-PDF analysis indicated that the glassy structure undergoes no structural change in the sulfide glass-ceramic electrolyte at a crystallinity of 33.1%. We observed the formation of a nanocrystalline phase in the X-ray and electron diffraction patterns before the crystallization, which means that Bragg peaks were deformed. Thus, the ionic conductivity in the mixture of glassy and crystalline phases is improved by the coexistence of the nanocrystalline phase.

  6. DEVELOPMENT AND SELECTION OF IONIC LIQUID ELECTROLYTES FOR HYDROXIDE CONDUCTING POLYBENZIMIDAZOLE MEMBRANES IN ALKALINE FUEL CELLS

    SciTech Connect

    Fox, E.

    2012-05-01

    Alkaline fuel cell (AFC) operation is currently limited to specialty applications such as low temperatures and pure HO due to the corrosive nature of the electrolyte and formation of carbonates. AFCs are the cheapest and potentially most efficient (approaching 70%) fuel cells. The fact that non-Pt catalysts can be used, makes them an ideal low cost alternative for power production. The anode and cathode are separated by and solid electrolyte or alkaline porous media saturated with KOH. However, CO from the atmosphere or fuel feed severely poisons the electrolyte by forming insoluble carbonates. The corrosivity of KOH (electrolyte) limits operating temperatures to no more than 80°C. This chapter examines the development of ionic liquids electrolytes that are less corrosive, have higher operating temperatures, do not chemically bond to CO and enable alternative fuels. Work is detailed on the IL selection and characterization as well as casting methods within the polybenzimidazole based solid membrane. This approach is novel as it targets the root of the problem (the electrolyte) unlike other current work in alkaline fuel cells which focus on making the fuel cell components more durable.

  7. Installation of a reactive site for covalent wiring onto an intrinsically conductive poly(ionic liquid)

    SciTech Connect

    Brombosz, Scott M.; Lee, Sungwon; Firestone, Millicent A.

    2014-12-01

    Post-polymerization radical bromination of a nanostructured poly(ionic liquid) that selectively introduces a reactive bromo-group onto the polyalkylthiophene backbone is described. Raman and FTIR spectroscopy proves that the bromine is successfully introduced at the 3-methyl position of the thiophene and that the molecular structure of the polymer remains largely intact with only minimal chain scission detected. FT-IR and Vis-NIR spectroscopy indicates that incorporation of the bromine induces twisting (loss of co-planarity) of the polythiophene backbone. WAXS confirms retention of an ordered lamellar structure with minor lattice spacing contraction. Cyclic voltammetry confirms spectroscopic findings that the bromination reaction yields a stable p-doped polymer. The installed bromine is susceptible to nucleophilic displacement permitting the covalent attachment of other functional molecules, such as a dialkylphosphonate. Elemental analysis of such a transformation established that 100% functionalization can be achieved. These results collectively demonstrate that post-modification of a pconjugated polymer can be used to both tune electronic and photonic properties, as well as install a chemoselective attachment point for the covalent wiring of other molecules.

  8. Installation of a reactive site for covalent wiring onto an intrinsically conductive poly(ionic liquid)

    SciTech Connect

    Brombosz, Scott M.; Lee, Sungwon; Firestone, Millicent A.

    2014-11-04

    We describe post-polymerization radical bromination of a nanostructured poly(ionic liquid) that selectively introduces a reactive bromo-group onto the polyalkylthiophene backbone. Raman and FT-IR spectroscopy proves that the bromine is successfully introduced at the 3-methyl position of the thiophene and that the molecular structure of the polymer remains largely intact with only minimal chain scission detected. FT-IR and Vis-NIR spectroscopy indicates that incorporation of the bromine induces twisting (loss of co-planarity) of the polythiophene backbone. WAXS confirms retention of an ordered lamellar structure with minor lattice spacing contraction. Cyclic voltammetry confirms spectroscopic findings that the bromination reaction yields a stable p-doped polymer. The installed bromine is susceptible to nucleophilic displacement permitting the covalent attachment of other functional molecules, such as a dialkylphosphonate. Elemental analysis of such a transformation established that 100 % functionalization can be achieved. These results collectively demonstrate that post-modification of a π-conjugated polymer can be used to both tune electronic and photonic properties, as well as install a chemoselective attachment point for the covalent wiring of other molecules.

  9. Installation of a reactive site for covalent wiring onto an intrinsically conductive poly(ionic liquid)

    DOE PAGES

    Brombosz, Scott M.; Lee, Sungwon; Firestone, Millicent A.

    2014-11-04

    We describe post-polymerization radical bromination of a nanostructured poly(ionic liquid) that selectively introduces a reactive bromo-group onto the polyalkylthiophene backbone. Raman and FT-IR spectroscopy proves that the bromine is successfully introduced at the 3-methyl position of the thiophene and that the molecular structure of the polymer remains largely intact with only minimal chain scission detected. FT-IR and Vis-NIR spectroscopy indicates that incorporation of the bromine induces twisting (loss of co-planarity) of the polythiophene backbone. WAXS confirms retention of an ordered lamellar structure with minor lattice spacing contraction. Cyclic voltammetry confirms spectroscopic findings that the bromination reaction yields a stable p-dopedmore » polymer. The installed bromine is susceptible to nucleophilic displacement permitting the covalent attachment of other functional molecules, such as a dialkylphosphonate. Elemental analysis of such a transformation established that 100 % functionalization can be achieved. These results collectively demonstrate that post-modification of a π-conjugated polymer can be used to both tune electronic and photonic properties, as well as install a chemoselective attachment point for the covalent wiring of other molecules.« less

  10. Ultrahigh Ionic Conduction in Water-Stable Close-Packed Metal-Carbonate Frameworks.

    PubMed

    Manna, Biplab; Desai, Aamod V; Illathvalappil, Rajith; Gupta, Kriti; Sen, Arunabha; Kurungot, Sreekumar; Ghosh, Sujit K

    2017-08-21

    Utilization of the robust metal-carbonate backbone in a series of water-stable, anionic frameworks has been harnessed for the function of highly efficient solid-state ion-conduction. The compact organization of hydrophilic guest ions facilitates water-assisted ion-conduction in all the compounds. The dense packing of the compounds imparts high ion-conducting ability and minimizes the possibility of fuel crossover, making this approach promising for design and development of compounds as potential components of energy devices. This work presents the first report of evaluating ion-conduction in a purely metal-carbonate framework, which exhibits high ion-conductivity on the order of 10(-2) S cm(-1) along with very low activation energy, which is comparable to highly conducting well-known crystalline coordination polymers or commercialized organic polymers like Nafion.

  11. High conductivity carbon nanotube wires from radial densification and ionic doping

    NASA Astrophysics Data System (ADS)

    Alvarenga, Jack; Jarosz, Paul R.; Schauerman, Chris M.; Moses, Brian T.; Landi, Brian J.; Cress, Cory D.; Raffaelle, Ryne P.

    2010-11-01

    Application of drawing dies to radially densify sheets of carbon nanotubes (CNTs) into bulk wires has shown the ability to control electrical conductivity and wire density. Simultaneous use of KAuBr4 doping solution, during wire drawing, has led to an electrical conductivity in the CNT wire of 1.3×106 S/m. Temperature-dependent electrical measurements show that conduction is dominated by fluctuation-assisted tunneling, and introduction of KAuBr4 significantly reduces the tunneling barrier between individual nanotubes. Ultimately, the concomitant doping and densification process leads to closer packed CNTs and a reduced charge transfer barrier, resulting in enhanced bulk electrical conductivity.

  12. Specific conductance and ionic characteristics of farm canals in the everglades agricultural area.

    PubMed

    Chen, Ming; Daroub, Samira H; Lang, Timothy A; Diaz, Orlando A

    2006-01-01

    Specific conductance in farm canals of the Everglades Agricultural Area (EAA) in south Florida is an important water quality parameter that was categorized as a parameter of concern according to an observed frequency of >5% excursions over the Class III water quality criterion and needed to be addressed as a part of the Everglades Regulatory Program. This study was conducted to evaluate specific conductance in farm canals of the EAA. Specific conductance was monitored at 10 representative farms (a total of 12 pump stations) in the EAA using multi-parameter water quality data loggers, for periods ranging from 24 to 83 mo. Cation and anion concentrations were also determined. Nonparametric Mann-Kendall trend analyses and Sen's slope analysis of specific conductance were conducted to determine specific conductance trends. Mean specific conductance ranged from 0.74 to 1.68 dS m(-1) and only 2 of the 10 farms were above the State Class III water quality criterion of 1.275 dS m(-1). Statistically significant downward trends were observed at 3 of the 10 farms. Determination of ion compositions in grab samples at 8 of the 10 farms indicated that the major ions contributing to the increase in specific conductance in the EAA were Cl-, HCO3-, and Na+. Mean Na/Cl ratios in most of the EAA canals ranged from 0.57 to 0.78, whereas those of SO4/Cl ranged from 0.46 to 0.98. Investigation of historical data and literature indicates that elevated specific conductance in parts of the EAA is a natural phenomenon due to entrapment of connate seawater in the Everglades formation. Sulfur contributes minor increases in specific conductance in the EAA with probable sources from organic soil mineralization, ground water, Lake Okeechobee, and S fertilizers.

  13. Effect of ion structure on conductivity in lithium-doped ionic liquid electrolytes: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Liu, Hongjun; Maginn, Edward

    2013-09-01

    Molecular dynamics simulations were performed to examine the role cation and anion structure have on the performance of ionic liquid (IL) electrolytes for lithium conduction over the temperature range of 320-450 K. Two model ionic liquids were studied: 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([bmim][Tf2N]) and 1-butyl-4-methylpyridinium pyrrolide ([bmpyr][pyl]) doped with Li[Tf2N] and Li[pyl], respectively. The results have demonstrated that the Li+ doped IL containing the planar [bmpyr] cation paired with the planar [pyl] anion significantly outperformed the [bmim][Tf2N] IL. The different coordination of Li+ with the [Tf2N]- or [pyl]- anions produces a remarkable change in IL structure with a concomitant effect on the transport of all ions. For the doped [bmim][Tf2N], each Li+ is coordinated by four oxygen atoms from [Tf2N]- anions. Formation of a rigid structure between Li+ and [Tf2N]- induces a decrease in the mobility of all ions. In contrast, for the doped [bmpyr][pyl], each Li+ is coordinated by two nitrogen atoms from [pyl]- anions. The original alternating structure cation|anion|cation in the neat [bmpyr][pyl] is replaced by another alternating structure cation|anion|Li+|anion|cation in the doped [bmpyr][pyl]. Increases of Li+ mole fraction in doped [bmpyr][pyl] affects the dynamics to a much lesser extent compared with [bmim][Tf2N] and leads to reduced diffusivities of cations and anions, but little change in the dynamics of Li+. More importantly, the calculations predict that the Li+ ion conductivity of doped [bmpyr][pyl] is comparable to that observed in organic liquid electrolytes and is about an order of magnitude higher than that of doped [bmim][Tf2N]. Such Li+ conductivity improvement suggests that this and related ILs may be promising candidates for use as electrolytes in lithium ion batteries and capacitors.

  14. Effect of Temperature and Pressure on Ionic Conductivity of PAN-Based Polymer Electrolytes Containing Inorganic Salts

    NASA Astrophysics Data System (ADS)

    Ahmad, A.; Isa, K. B. Md.; Osman, Z.

    2010-07-01

    The conducting polymer electrolyte films consisting polyacrylonitrile (PAN) as the host polymer, ethylene carbonate (EC) as a plasticizer, lithium triflate (LiCF3SO3) and sodium triflate (NaCF3SO3) as inorganic salts were prepared by the solution cast technique. The pure PAN film was prepared as a reference. The ionic conductivity for the films is characterized using impedance spectroscopy. The room temperature conductivity for the PAN+24 wt.%EC film, PAN+26 wt.%LiCF3SO3 film, the PAN+24 wt.%NaCF3SO3 film is 3.43×10-11 S cm-1, 3.04×10-4 S cm-1, and 7.13×10-4 S cm-1, respectively. On addition of plasticizer, the room temperature of PAN+LiCF3SO3 and PAN+NaCF3SO3 films increases by one order of magnitude. The conductivity-temperature and conductivity-pressure dependence studies are then performed on the highest conducting film from the unplasticized and plasticized systems in the temperature and pressure range between 303 K and 373 K and 0.01 MPa and 0.09 MPa, respectively. The conductivity-temperature studies indicate the activation energy, Ea for all system decrease with the increase of the conductivity. The activation volume, ΔV* for each system can be determined from the plot of ln σ versus pressure. It can be observed that the ΔV* is decreased as the conductivity increased. This result can be explained in term of free volume.

  15. Conductive polymer as a controlled microenvironment for the potentiometric high-throughput evaluation of ionic liquid cell toxicity.

    PubMed

    Qiu, Weilian; Zeng, Xiangqun

    2008-09-01

    This paper presents both biological and potentiometric evaluations of the cell toxicity of a widely used ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF(4)), to Chinese hamster lung fibroblast cells (V79 cell line). The innovative potentiometric study takes advantage of the unique properties of conductive polymer polypyrrole (PPY) for the potentiometric evaluation of cell toxicity of [bmim]BF(4) to the V79 cells in a real-time, noninvasive and high-throughput manner. The conductive polymer PPY provides a controlled microenvironment that allows the quantitative release of the anions of the ionic liquids into the cells being monitored in real time and noninvasively. Parallel biological assay results showed that V79 cells exposed to [bmim]BF(4) usually grew in clusters, and that many small vacuoles could be seen in the cytoplasm. At the 24th hour after the V79 cells had been exposed to the ionic liquid (IL), the half inhibition concentration (EC(50)) of [bmim]BF(4) was around 5 mM. From a cell cycle study performed using a FACScan flow cytometer, it was found that the V79 cells could be partially locked to the G(1) phase by [bmim]BF(4), which extended the doubling time for cell growth. Comparing with the EC(50) values of cadmium chloride and mercury chloride, [bmim]BF(4) is not very toxic, but it may have a long-term toxic effect on mammalian cells. Compared to traditional biological in vitro assays, the use of a conductive polymer substrate in combination with a potentiometric sensor array is much more sensitive, faster, and enables a simpler evaluation of chemical cell toxicity. Additionally, it simplifies the study of the reversibility of cell toxicity, i.e., cell recovery, because there is no need to refresh the culture medium since a finite amount of chemicals can be doped and released. We found that the cytotoxicity of [bmim]BF(4) at a concentration of less than 6 mM was reversible for the V79 cell line, because cell morphology and

  16. Ionic mechanisms underlying history-dependence of conduction delay in an unmyelinated axon.

    PubMed

    Zhang, Yang; Bucher, Dirk; Nadim, Farzan

    2017-07-10

    Axonal conduction velocity can change substantially during ongoing activity, thus modifying spike interval structures and, potentially, temporal coding. We used a biophysical model to unmask mechanisms underlying the history-dependence of conduction. The model replicates activity in the unmyelinated axon of the crustacean stomatogastric pyloric dilator neuron. At the timescale of a single burst, conduction delay has a non-monotonic relationship with instantaneous frequency, which depends on the gating rates of the fast voltage-gated Na(+) current. At the slower timescale of minutes, the mean value and variability of conduction delay increase. These effects are because of hyperpolarization of the baseline membrane potential by the Na(+)/K(+) pump, balanced by an h-current, both of which affect the gating of the Na(+) current. We explore the mechanisms of history-dependence of conduction delay in axons and develop an empirical equation that accurately predicts this history-dependence, both in the model and in experimental measurements.

  17. Response surface method (RSM) for optimization of ionic conductivity of membranes polymer electrolyte poly (vinylidene fluoride) (PVDF) with polyvinyl pyrrolidone (PVP) as pore forming agent

    NASA Astrophysics Data System (ADS)

    Dyartanti, E. R.; Susanto, H.; Widiasa, I. N.; Purwanto, A.

    2017-06-01

    The Membranes Polymer Gel Electrolyte (MPGEs) based poly (vinylidene fluoride) (PVDF) was prepared by a phase inversion method using polyvinyl pyrrolidone (PVP) as a pore-forming agent and N, N-dimethyl acetamide (DMAc) as a solvent and water as non solvet. The membranes were then soaked in 1 M lithium hexafluorophosphate (LiPF6) in ethylene carbonate (EC) / dimethyl carbonate (DMC) / Diethyl carbonate (DEC) (4:2:4 %vol) solution in order to prepare polymer electrolyte membranes. The MPEGs PVDF/PVP/Nanoclay was applied using central composite design (CCD) experimental design to obtain a quantitative relationship between selected membranes prepared parameters namely (PVDF, PVP as pore forming agent and nanoclay filler concentration) and Ionic conductivity MPEGs. The model was used to find the optimum ionic conductivity from polymer electrolyte membranes. The polymer electrolyte membranes show good ionic conductivity on the order of 6.3 - 8.7 x 10-3 S cm-1 at the ambient temperatures. The ionic conductivity tended to increase with PVP and nanoclay concentration and decrease with PVDF composition. The model predicted the maximum ionic conductivity of 8.47 x 10-3 S cm-1 when the PVDF, PVP and nanoclay concentration were set at 8.01 %, 8.04 % and 10.12%, respectively. The first section in your paper.

  18. One-dimensional ion-conductive polymer films: alignment and fixation of ionic channels formed by self-organization of polymerizable columnar liquid crystals.

    PubMed

    Yoshio, Masafumi; Kagata, Takayoshi; Hoshino, Koji; Mukai, Tomohiro; Ohno, Hiroyuki; Kato, Takashi

    2006-04-26

    We have prepared two types of one-dimensional ion-conductive polymer films containing ion nanochannels that are both perpendicular and parallel to the film surface. These films have been obtained by photopolymerization of aligned columnar liquid crystals of a fan-shaped imidazolium salt having acrylate groups at the periphery. In the columnar structure, the ionic part self-assembles into the inner part of the column. The column is oriented macroscopically in two directions by different methods: orientation perpendicular to the modified surfaces of glass and indium tin oxide with 3-(aminopropyl)triethoxysilane and orientation parallel to a glass surface by mechanical shearing. Ionic conductivities have been measured for the films with columnar orientation vertical and parallel to the surface. Anisotropic ionic conductivities are observed for the oriented films fixed by photopolymerization. The ionic conductivities parallel to the columnar axis are higher than those perpendicular to the columnar axis because the lipophilic part functions as an ion-insulating part. The film with the columns oriented vertically to the surface shows an anisotropy of ionic conductivities higher than that of the film with the columns aligned parallel to the surface.

  19. High Ionic Conductivity of Composite Solid Polymer Electrolyte via In Situ Synthesis of Monodispersed SiO2 Nanospheres in Poly(ethylene oxide).

    PubMed

    Lin, Dingchang; Liu, Wei; Liu, Yayuan; Lee, Hye Ryoung; Hsu, Po-Chun; Liu, Kai; Cui, Yi

    2016-01-13

    High ionic conductivity solid polymer electrolyte (SPE) has long been desired for the next generation high energy and safe rechargeable lithium batteries. Among all of the SPEs, composite polymer electrolyte (CPE) with ceramic fillers has garnered great interest due to the enhancement of ionic conductivity. However, the high degree of polymer crystallinity, agglomeration of ceramic fillers, and weak polymer-ceramic interaction limit the further improvement of ionic conductivity. Different from the existing methods of blending preformed ceramic particles with polymers, here we introduce an in situ synthesis of ceramic filler particles in polymer electrolyte. Much stronger chemical/mechanical interactions between monodispersed 12 nm diameter SiO2 nanospheres and poly(ethylene oxide) (PEO) chains were produced by in situ hydrolysis, which significantly suppresses the crystallization of PEO and thus facilitates polymer segmental motion for ionic conduction. In addition, an improved degree of LiClO4 dissociation can also be achieved. All of these lead to good ionic conductivity (1.2 × 10(-3) S cm(-1) at 60 °C, 4.4 × 10(-5) S cm(-1) at 30 °C). At the same time, largely extended electrochemical stability window up to 5.5 V can be observed. We further demonstrated all-solid-state lithium batteries showing excellent rate capability as well as good cycling performance.

  20. Effect of Structure on Transport Properties (Viscosity, Ionic Conductivity, and Self-Diffusion Coefficient) of Aprotic Heterocyclic Anion (AHA) Room Temperature Ionic Liquids. 2. Variation of Alkyl Chain Length in the Phosphonium Cation.

    PubMed

    Sun, Liyuan; Morales-Collazo, Oscar; Xia, Han; Brennecke, Joan F

    2016-06-30

    A series of room-temperature ionic liquids (ILs) composed of triethyl(alkyl)phosphonium cations paired with three different aprotic heterocyclic anions (AHAs) (alkyl = butyl ([P2224](+)) and octyl ([P2228](+))) were prepared to investigate the effect of cationic alkyl chain length on transport properties. The transport properties and density of these ILs were measured from 283.15 to 343.15 K at ambient pressure. The dependence of the transport properties (viscosity, ionic conductivity, diffusivity, and molar conductivity) on temperature can be described by the Vogel-Fulcher-Tamman (VFT) equation. The ratio of the molar conductivity obtained from the molar concentration and ionic conductivity measurements to that calculated from self-diffusion coefficients (measured by pulsed gradient spin-echo nuclear magnetic resonance spectroscopy) using the Nernst-Einstein equation was used to quantify the ionicity of these ILs. The molar conductivity ratio decreases with increasing number of carbon atoms in the alkyl chain, indicating that the reduced Coulombic interactions resulting from lower density are more than balanced by the increased van der Waals interactions between the alkyl chains. The results of this study may provide insight into the design of ILs with enhanced dynamics that may be suitable as electrolytes in lithium ion batteries and other electrochemical applications.

  1. Effect of Structure on Transport Properties (Viscosity, Ionic Conductivity, and Self-Diffusion Coefficient) of Aprotic Heterocyclic Anion (AHA) Room-Temperature Ionic Liquids. 1. Variation of Anionic Species.

    PubMed

    Sun, Liyuan; Morales-Collazo, Oscar; Xia, Han; Brennecke, Joan F

    2015-12-03

    A series of room temperature ionic liquids (RTILs) based on 1-ethyl-3-methylimidazolium ([emim](+)) with different aprotic heterocyclic anions (AHAs) were synthesized and characterized as potential electrolyte candidates for lithium ion batteries. The density and transport properties of these ILs were measured over the temperature range between 283.15 and 343.15 K at ambient pressure. The temperature dependence of the transport properties (viscosity, ionic conductivity, self-diffusion coefficient, and molar conductivity) is fit well by the Vogel-Fulcher-Tamman (VFT) equation. The best-fit VFT parameters, as well as linear fits to the density, are reported. The ionicity of these ILs was quantified by the ratio of the molar conductivity obtained from the ionic conductivity and molar concentration to that calculated from the self-diffusion coefficients using the Nernst-Einstein equation. The results of this study, which is based on ILs composed of both a planar cation and planar anions, show that many of the [emim][AHA] ILs exhibit very good conductivity for their viscosities and provide insight into the design of ILs with enhanced dynamics that may be suitable for electrolyte applications.

  2. Correlation between ionic radii of metal azodye complexes and electrical conductivity.

    PubMed

    El-Ghamaz, N A; El-Sonbati, A Z; Diab, M A; El-Bindary, A A; Mohamed, G G; Morgan, Sh M

    2015-08-05

    5-(2,3-Dimethyl-1-phenylpyrazol-5-one azo)-2-thioxo-4-thiazolidinone (HL) and its metal complexes with copper(II) (1), cobalt(II) (2) and nickel(II) (3) are synthesized and characterized by physico-chemical techniques. The thermal properties of the ligand (HL) and its metal complexes (1-3) are discussed. The thermal activation energies of decomposition (Ea) of HL and its metal complexes with Cu(II), Co(II) and Ni(II) are found to be 48.76, 36.83, 30.59 and 40.45 kJ/mol, respectively. The frequency and temperature dependence of ac conductivity, dielectric constants for HL and its complexes (1-3) are investigated in the temperature range 300-356 K and frequency range 0.1-100 kHz. Both of the ac conductivity and the values of the thermal activation energy for conduction, as well as the dielectric properties of the complexes of HL are found to depend on the nature of the metallic ions. The values of the thermal activation energies of electrical conductivity decrease with increasing the value of test frequency. The small polarons tunneling (SPT) is the dominant conduction mechanism for the ligand (HL), while for complex (2) the overlapping large tunneling model (OLPT) is the dominant conduction mechanism. The correlated barrier hopping (CBH) is the dominant conduction mechanism for both of the complexes (1) and (3).

  3. Ionic conductivity in poly(propylene glycol) complexed with lithium and sodium triflate

    NASA Astrophysics Data System (ADS)

    Albinsson, I.; Mellander, B.-E.; Stevens, J. R.

    1992-01-01

    Conductivity and viscosity measurements have been made for poly(propylene glycol)-MCF3SO3 (M=Li, Na) complexes in order to examine more closely the Vogel-Tammann-Fulcher (VTF) empirical relationship which has been found in previous reports to provide a good fit to the experimental data. Further, a dynamic bond percolation model of ion conduction in polymer electrolytes has predicted VTF behavior and an inverse relationship between molar conductivity and viscosity or Walden ``rule'' behavior. We find that deviations occur from both the VTF and Walden empirical relationships and propose a modest alteration in the form of the dynamic percolation model for ions moving in polyether systems.

  4. Impact of segregation energetics on oxygen conductivity at ionic grain boundaries

    SciTech Connect

    Aidhy, Dilpuneet S; Zhang, Yanwen; Weber, William J

    2014-01-01

    In pursuit of whether nanocrystallinity could lead to higher anion conductivity, research has revealed contradicting results exposing the limited understanding of point defect energetics at grain boundaries (GBs)/interfaces. By disentangling and addressing key GB energetics issues, i.e., segregation, migration and binding energies of oxygen vacancies in the presence and absence of dopants at the GBs, and the segregation energetics of dopants, we elucidate, using atomic simulations of doped ceria, that dopant segregation is the key factor leading to degradation of oxygen conductivity in nanocrystalline materials. A framework for designing enhanced conducting nanocrystalline materials is proposed where the focus of doping strategies shifts from bulk to segregation at GBs.

  5. AC conductivity scaling behavior in grain and grain boundary response regime of fast lithium ionic conductors

    NASA Astrophysics Data System (ADS)

    Mariappan, C. R.

    2014-05-01

    AC conductivity spectra of Li-analogues NASICON-type Li1.5Al0.5Ge1.5P3O12 (LAGP), Li-Al-Ti-P-O (LATP) glass-ceramics and garnet-type Li7La2Ta2O13 (LLTO) ceramic are analyzed by universal power law and Summerfield scaling approaches. The activation energies and pre-exponential factors of total and grain conductivities are following the Meyer-Neldel (M-N) rule for NASICON-type materials. However, the garnet-type LLTO material deviates from the M-N rule line of NASICON-type materials. The frequency- and temperature-dependent conductivity spectra of LAGP and LLTO are superimposed by Summerfield scaling. The scaled conductivity curves of LATP are not superimposed at the grain boundary response region. The superimposed conductivity curves are observed at cross-over frequencies of grain boundary response region for LATP by incorporating the exp ( {{{ - (EAt - EAg )} {{{ - (EAt - EAg )} {kT}}} ) factor along with Summerfield scaling factors on the frequency axis, where EAt and EAg are the activation energies of total and grain conductivities, respectively.

  6. Ionically conducting PVA-LiClO4 gel electrolyte for high performance flexible solid state supercapacitors.

    PubMed

    Chodankar, Nilesh R; Dubal, Deepak P; Lokhande, Abhishek C; Lokhande, Chandrakant D

    2015-12-15

    The synthesis of polymer gel electrolyte having high ionic conductivity, excellent compatibility with active electrode material, mechanical tractability and long life is crucial to obtain majestic electrochemical performance for flexible solid state supercapacitors (FSS-SCs). Our present work describes effect of different polymers gel electrolytes on electrochemical properties of MnO2 based FSS-SCs device. It is revealed that, MnO2-FSS-SCs with polyvinyl alcohol (PVA)-Lithium perchlorate (LiClO4) gel electrolyte demonstrate excellent electrochemical features such as maximum operating potential window (1.2V), specific capacitance of 112Fg(-1) and energy density of 15Whkg(-1) with extended cycling stability up to 2500CV cycles. Moreover, the calendar life suggests negligible decrease in the electrochemical performance of MnO2-FSS-SCs after 20days. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Sparse Cyclic Excitations Explain the Low Ionic Conductivity of Stoichiometric Li_{7}La_{3}Zr_{2}O_{12}.

    PubMed

    Burbano, Mario; Carlier, Dany; Boucher, Florent; Morgan, Benjamin J; Salanne, Mathieu

    2016-04-01

    We have performed long time scale molecular dynamics simulations of the cubic and tetragonal phases of the solid lithium-ion electrolyte Li_{7}La_{3}Zr_{2}O_{12} (LLZO), using a first-principles parametrized interatomic potential. Collective lithium transport was analyzed by identifying dynamical excitations: persistent ion displacements over distances comparable to the separation between lithium sites, and stringlike clusters of ions that undergo cooperative motion. We find that dynamical excitations in c-LLZO (cubic) are frequent, with participating lithium numbers following an exponential distribution, mirroring the dynamics of fragile glasses. In contrast, excitations in t-LLZO (tetragonal) are both temporally and spatially sparse, consisting preferentially of highly concerted lithium motion around closed loops. This qualitative difference is explained as a consequence of lithium ordering in t-LLZO and provides a mechanistic basis for the much lower ionic conductivity of t-LLZO compared to c-LLZO.

  8. Sparse Cyclic Excitations Explain the Low Ionic Conductivity of Stoichiometric Li7La3Zr2O12

    NASA Astrophysics Data System (ADS)

    Burbano, Mario; Carlier, Dany; Boucher, Florent; Morgan, Benjamin J.; Salanne, Mathieu

    2016-04-01

    We have performed long time scale molecular dynamics simulations of the cubic and tetragonal phases of the solid lithium-ion electrolyte Li7La3Zr2O12 (LLZO), using a first-principles parametrized interatomic potential. Collective lithium transport was analyzed by identifying dynamical excitations: persistent ion displacements over distances comparable to the separation between lithium sites, and stringlike clusters of ions that undergo cooperative motion. We find that dynamical excitations in c-LLZO (cubic) are frequent, with participating lithium numbers following an exponential distribution, mirroring the dynamics of fragile glasses. In contrast, excitations in t-LLZO (tetragonal) are both temporally and spatially sparse, consisting preferentially of highly concerted lithium motion around closed loops. This qualitative difference is explained as a consequence of lithium ordering in t-LLZO and provides a mechanistic basis for the much lower ionic conductivity of t-LLZO compared to c-LLZO.

  9. Effect of Al concentration on the holographic grating efficiency and ionic conductivity in sodium magnesium aluminosilicate glasses

    NASA Astrophysics Data System (ADS)

    Hamad, Abdulatif Y.; Wicksted, James P.; Hogsed, Michael R.; Martin, Joel J.; Hunt, Charles A.; Dixon, George S.

    2002-02-01

    A systematic study of grating formation, erasure, and decay in 15Na2O.12MgO.xAl2O3.(73-x)SiO2 glasses doped with 1.26 mol% Eu2O3 is reported as a function of Al2O3 concentration for x=0 to 15. The permanent change in the index of refraction was a linearly increasing function of Al2O3 concentration. The grating buildup and erasure rates also increased with Al2O3 concentrations. This is attributed to the reduced activation energy for forced diffusion of small modifiers bound to AlO-4 clusters rather than to nonbridging oxygens. Ionic conductivities were also measured to confirm the reduction of the activation energies. The results of this study support the model for grating kinetics in rare-earth sensitized glasses proposed recently by Dixon, Hamad, and Wicksted.

  10. Ionic conductor with high conductivity as single-component electrolyte for efficient solid-state dye-sensitized solar cells.

    PubMed

    Wang, Hong; Li, Juan; Gong, Feng; Zhou, Gang; Wang, Zhong-Sheng

    2013-08-28

    Imidazolium iodide is an often used component in iodine-based dye-sensitized solar cells (DSSCs), but it cannot operate an efficient DSSC in the absence of iodine due to its low conductivity. For this study, lamellar solid iodide salts of imidazolium or piperidinium with an N-substituted propargyl group have been prepared and applied in solid-state DSSCs. Owing to the high conductivity arising from the lamellar structure, these solid-state ionic conductors can be used as single-component solid electrolytes to operate solid-state DSSCs efficiently without any additives in the electrolyte and post-treatments on the dye-loaded TiO2 films. With a propargyl group attached to the imidazolium ring, the conductivity is enhanced by about 4 × 10(4)-fold as compared to the alkyl-substituted imidazolium iodide. Solid-state DSSC with the 1-propargyl-3-methylimidazolium iodide as the single-component solid-state electrolyte has achieved a light-to-electricity power conversion efficiency of 6.3% under illumination of simulated AM1.5G solar light (100 mW cm(-2)), which also exhibits good long-term stability under continuous 1 sun soaking for 1500 h. This finding paves the way for development of high-conductivity single-component solid electrolytes for use in efficient solid-state DSSCs.

  11. Structure and properties of Li-ion conducting polymer gel electrolytes based on ionic liquids of the pyrrolidinium cation and the bis(trifluoromethanesulfonyl)imide anion

    NASA Astrophysics Data System (ADS)

    Pitawala, Jagath; Navarra, Maria Assunta; Scrosati, Bruno; Jacobsson, Per; Matic, Aleksandar

    2014-01-01

    We have investigated the structure and physical properties of Li-ion conducting polymer gel electrolytes functionalized with ionic liquid/lithium salt mixtures. The membranes are based on poly(vinylidene fluoride-co-hexafluoropropylene) copolymer, PVdF-HFP, and two ionic liquids: pyrrolidinium cations, N-butyl-N-methylpyrrolidinium (PyR14+), N-butyl-N-ethylpyrrolidinium (PyR24+), and bis(trifluoromethanesulfonyl)imide anion (TFSI). The ionic liquids where doped with 0.2 mol kg-1 LiTFSI. The resulting membranes are freestanding, flexible, and nonvolatile. The structure of the polymer and the interactions between the polymer and the ionic liquid electrolyte have been studied using Raman spectroscopy. The ionic conductivity of the membranes has been studied using dielectric spectroscopy whereas the thermal properties were investigated using differential scanning caloriometry (DSC). These results show that there is a weak, but noticeable, influence on the physical properties of the ionic liquid by the confinement in the membrane. We observe a change in the Li-ion coordination, conformation of the anion, the fragility and a slight increase of the glass transition temperatures for IL/LiTFSI mixtures in the membranes compared to the neat mixtures. The effect can be related to the confinement of the liquid in the membrane and/or to interactions with the PVdF-HFP polymer matrix where the crystallinity is decreased compared to the starting polymer powder.

  12. Local structure and ionic conductivity in the Zr2Y2O7-Y3NbO7 system

    NASA Astrophysics Data System (ADS)

    Norberg, Stefan T.; Ahmed, Istaq; Hull, Stephen; Marrocchelli, Dario; Madden, Paul A.

    2009-05-01

    The Zr0.5-0.5xY0.5+0.25xNb0.25xO1.75 solid solution possesses an anion-deficient fluorite structure across the entire 0<=x<=1 range. The relationship between the disorder within the crystalline lattice and the preferred anion diffusion mechanism has been studied as a function of x, using impedance spectroscopy measurements of the ionic conductivity (σ), powder neutron diffraction studies, including analysis of the 'total' scattering to probe the nature of the short-range correlations between ions using reverse Monte Carlo (RMC) modelling, and molecular dynamics (MD) simulations using potentials derived with a strong ab initio basis. The highest total ionic conductivity (σ = 2.66 × 10-2 Ω-1 cm-1 at 1473 K) is measured for the Zr2Y2O7 (x = 0) end member, with a decrease in σ with increasing x, whilst the neutron diffraction studies show an increase in lattice disorder with x. This apparent contradiction can be understood by considering the local structural distortions around the various cation species, as determined from the RMC modelling and MD simulations. The addition of Nb5+ and its stronger Coulomb interaction generates a more disordered local structure and enhances the mobility of some anions. However, the influence of these pentavalent cations is outweighed by the effect of the additional Y3+ cations introduced as x increases, which effectively trap many anions and reduce the overall concentration of the mobile O2- species.

  13. AC impedance analysis of ionic and electronic conductivities in electrode mixture layers for an all-solid-state lithium-ion battery

    NASA Astrophysics Data System (ADS)

    Siroma, Zyun; Sato, Tomohiro; Takeuchi, Tomonari; Nagai, Ryo; Ota, Akira; Ioroi, Tsutomu

    2016-06-01

    The ionic and electronic effective conductivities of an electrode mixture layers for all-solid-state lithium-ion batteries containing Li2Ssbnd P2S5 as a solid electrolyte were investigated by AC impedance measurements and analysis using a transmission-line model (TLM). Samples containing graphite (graphite electrodes) or LiNi0.5Co0.2Mn0.3O2 (NCM electrodes) as the active material were measured under a "substrate | sample | bulk electrolyte | sample | substrate" configuration (ion-electron connection) and a "substrate | sample | substrate" configuration (electron-electron connection). Theoretically, if the electronic resistance is negligibly small, which is the case with our graphite electrodes, measurement with the ion-electron connection should be effective for evaluating ionic conductivity. However, if the electronic resistance is comparable to the ionic resistance, which is the case with our NCM electrodes, the results with the ion-electron connection may contain some inherent inaccuracy. In this report, we theoretically and practically demonstrate the advantage of analyzing the results with the electron-electron connection, which gives both the ionic and electronic conductivities. The similarity of the behavior of ionic conductivity with the graphite and NCM electrodes confirms the reliability of this analysis.

  14. Diketonylpyridinium Cations as a Support of New Ionic Liquid Crystals and Ion-Conductive Materials: Analysis of Counter-Ion Effects.

    PubMed

    Pastor, María Jesús; Cuerva, Cristián; Campo, José A; Schmidt, Rainer; Torres, María Rosario; Cano, Mercedes

    2016-05-12

    Ionic liquid crystals (ILCs) allow the combination of the high ionic conductivity of ionic liquids (ILs) with the supramolecular organization of liquid crystals (LCs). ILCs salts were obtained by the assembly of long-chained diketonylpyridinium cations of the type [HOO(R(n)pyH)]⁺ and BF₄(-), ReO₄(-), NO₃(-), CF₃SO₃(-), CuCl₄(2-) counter-ions. We have studied the thermal behavior of five series of compounds by differential scanning calorimetry (DSC) and hot stage polarized light optical microscopy (POM). All materials show thermotropic mesomorphism as well as crystalline polymorphism. X-ray diffraction of the [HOO(R(12)pyH)][ReO₄] crystal reveals a layered structure with alternating polar and apolar sublayers. The mesophases also exhibit a lamellar arrangement detected by variable temperature powder X-ray diffraction. The CuCl₄(2-) salts exhibit the best LC properties followed by the ReO₄(-) ones due to low melting temperature and wide range of existence. The conductivity was probed for the mesophases in one species each from the ReO₄(-), and CuCl₄(2-) families, and for the solid phase in one of the non-mesomorphic Cl(-) salts. The highest ionic conductivity was found for the smectic mesophase of the ReO₄(-) containing salt, whereas the solid phases of all salts were dominated by electronic contributions. The ionic conductivity may be favored by the mesophase lamellar structure.

  15. Ionic mechanisms underlying history-dependence of conduction delay in an unmyelinated axon

    PubMed Central

    Zhang, Yang; Bucher, Dirk; Nadim, Farzan

    2017-01-01

    Axonal conduction velocity can change substantially during ongoing activity, thus modifying spike interval structures and, potentially, temporal coding. We used a biophysical model to unmask mechanisms underlying the history-dependence of conduction. The model replicates activity in the unmyelinated axon of the crustacean stomatogastric pyloric dilator neuron. At the timescale of a single burst, conduction delay has a non-monotonic relationship with instantaneous frequency, which depends on the gating rates of the fast voltage-gated Na+ current. At the slower timescale of minutes, the mean value and variability of conduction delay increase. These effects are because of hyperpolarization of the baseline membrane potential by the Na+/K+ pump, balanced by an h-current, both of which affect the gating of the Na+ current. We explore the mechanisms of history-dependence of conduction delay in axons and develop an empirical equation that accurately predicts this history-dependence, both in the model and in experimental measurements. DOI: http://dx.doi.org/10.7554/eLife.25382.001 PMID:28691900

  16. Effect of pressure on the ionic conductivity of Li+ and Cl- ions in water

    NASA Astrophysics Data System (ADS)

    Varanasi, Srinivasa R.; Kumar, Parveen; Subramanian, Yashonath

    2012-10-01

    A molecular dynamics simulation study of aqueous solution of LiCl is reported as a function of pressure. Experimental measurements of conductivity of Li+ ion as a function of pressure shows an increase in conductivity with pressure. Our simulations are able to reproduce the observed trend in conductivity. A number of relevant properties have been computed in order to understand the reasons for the increase in conductivity with pressure. These include radial distribution function, void and neck distributions, hydration or coordination numbers, diffusivity, velocity autocorrelation functions, angles between ion-oxygen and dipole of water as well as OH vector, mean residence time for water in the hydration shell, etc. These show that the increase in pressure acts as a structure breaker. The decay of the self part of the intermediate scattering function at small wave number k shows a bi-exponential decay at 1 bar which changes to single exponential decay at higher pressures. The k dependence of the ratio of the self part of the full width at half maximum of the dynamic structure factor to 2Dk2 exhibits trends which suggest that the void structure of water is playing a role. These support the view that the changes in void and neck distributions in water can account for changes in conductivity or diffusivity of Li+ with pressure. These results can be understood in terms of the levitation effect.

  17. Study on phase stability and ionic conductivity in TiIV-substituted bismuth vanadate

    NASA Astrophysics Data System (ADS)

    Beg, Saba; Haneef, Sadaf

    2014-09-01

    The solid solutions Bi4TixV2-xO11-(x/2)-δ in the composition range 0.05 ≤ x ≤ 0.30 were obtained by solid state reaction according to the substitution equation: ? The sample characterization and the study of phase transition were performed by using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), alternating current (AC) impedance and electrical conductivity measurements. The solid solutions with composition 0.05 ≤ x ≤ 0.17 are isostructural with the orthorhombic β-phase, and those with x ≥ 0.20 represent tetragonal γ‧-phase as confirmed by the XRD and DSC results. Arrhenius plots of conductivity show that with increase in Ti concentration, the conductivity of solid solutions increase and reaches a maximum value of 4.38 × 10-5 Scm-1 for x = 0.17 at 340 °C. It is seen that the highly conducting tetragonal γ‧-phase is effectively stabilized to room temperature for the composition x ≥ 0.20. AC impedance plots show that the conductivity is mainly due to the grain and the grain boundary contribution which is confirmed by the existence of two semicircles along with an inclined spike.

  18. Electrical and ionic conductivity effects on magic-angle spinning nuclear magnetic resonance parameters of CuI.

    PubMed

    Yesinowski, James P; Ladouceur, Harold D; Purdy, Andrew P; Miller, Joel B

    2010-12-21

    We investigate experimentally and theoretically the effects of two different types of conductivity, electrical and ionic, upon magic-angle spinning NMR spectra. The experimental demonstration of these effects involves (63)Cu, (65)Cu, and (127)I variable temperature MAS-NMR experiments on samples of γ-CuI, a Cu(+)-ion conductor at elevated temperatures as well as a wide bandgap semiconductor. We extend previous observations that the chemical shifts depend very strongly upon the square of the spinning-speed as well as the particular sample studied and the magnetic field strength. By using the (207)Pb resonance of lead nitrate mixed with the γ-CuI as an internal chemical shift thermometer we show that frictional heating effects of the rotor do not account for the observations. Instead, we find that spinning bulk CuI, a p-type semiconductor due to Cu(+) vacancies in nonstoichiometric samples, in a magnetic field generates induced AC electric currents from the Lorentz force that can resistively heat the sample by over 200 °C. These induced currents oscillate along the rotor spinning axis at the spinning speed. Their associated heating effects are disrupted in samples containing inert filler material, indicating the existence of macroscopic current pathways between micron-sized crystallites. Accurate measurements of the temperature-dependence of the (63)Cu and (127)I chemical shifts in such diluted samples reveal that they are of similar magnitude (ca. 0.27 ppm/K) but opposite sign (being negative for (63)Cu), and appear to depend slightly upon the particular sample. This relationship is identical to the corresponding slopes of the chemical shifts versus square of the spinning speed, again consistent with sample heating as the source of the observed large shift changes. Higher drive-gas pressures are required to spin samples that have higher effective electrical conductivities, indicating the presence of a braking effect arising from the induced currents produced by

  19. Electrical and ionic conductivity effects on magic-angle spinning nuclear magnetic resonance parameters of CuI

    NASA Astrophysics Data System (ADS)

    Yesinowski, James P.; Ladouceur, Harold D.; Purdy, Andrew P.; Miller, Joel B.

    2010-12-01

    We investigate experimentally and theoretically the effects of two different types of conductivity, electrical and ionic, upon magic-angle spinning NMR spectra. The experimental demonstration of these effects involves 63Cu, 65Cu, and 127I variable temperature MAS-NMR experiments on samples of γ-CuI, a Cu+-ion conductor at elevated temperatures as well as a wide bandgap semiconductor. We extend previous observations that the chemical shifts depend very strongly upon the square of the spinning-speed as well as the particular sample studied and the magnetic field strength. By using the 207Pb resonance of lead nitrate mixed with the γ-CuI as an internal chemical shift thermometer we show that frictional heating effects of the rotor do not account for the observations. Instead, we find that spinning bulk CuI, a p-type semiconductor due to Cu+ vacancies in nonstoichiometric samples, in a magnetic field generates induced AC electric currents from the Lorentz force that can resistively heat the sample by over 200 °C. These induced currents oscillate along the rotor spinning axis at the spinning speed. Their associated heating effects are disrupted in samples containing inert filler material, indicating the existence of macroscopic current pathways between micron-sized crystallites. Accurate measurements of the temperature-dependence of the 63Cu and 127I chemical shifts in such diluted samples reveal that they are of similar magnitude (ca. 0.27 ppm/K) but opposite sign (being negative for 63Cu), and appear to depend slightly upon the particular sample. This relationship is identical to the corresponding slopes of the chemical shifts versus square of the spinning speed, again consistent with sample heating as the source of the observed large shift changes. Higher drive-gas pressures are required to spin samples that have higher effective electrical conductivities, indicating the presence of a braking effect arising from the induced currents produced by rotating a

  20. Ionic Conductivity Trends with Molecular Weight in PEO and PEO-Based Solid Polymer Electrolytes

    NASA Astrophysics Data System (ADS)

    Teran, Alexander; Mullin, Scott; Wanakule, Nisita; Panday, Ashoutosh; Balsara, Nitash

    2010-03-01

    Poly(ethylene oxide) based polymer electrolytes with lithium bis(trifluoromethane)sulfonamide (LiTFSI) salt remain one of the most promising class of solid polymer electrolyte for rechargeable lithium metal batteries. Among those, poly(styrene-b-ethyleneoxide) (SEO) doped with LiTFSI has been shown to exhibit acceptable levels of conductivity while possessing a sufficiently high modulus to suppress the growth of dendrites. The purpose of this study is to explore the molecular weight dependence on conductivity for the PEO/LiTFSI system to which previous studies have alluded, but never quantified, and contrast this with the observed molecular weight dependence of SEO reported in previous work. Conductivities were measured using AC impedance spectroscopy over a broad range of temperatures and molecular weights beyond those reported in the literature.

  1. Ion diffusion coefficients model and molar conductivities of ionic salts in aprotic solvents.

    PubMed

    Garrido, Leoncio; Mejía, Alberto; García, Nuria; Tiemblo, Pilar; Guzmán, Julio

    2015-02-19

    In the study of the electric properties of electrolytes, the determination of the diffusion coefficients of the species that intervene in the charge transport process is of great importance, particularly that of the free ions (D(+) and D(-)), the only species that contribute to the conductivity. In this work we propose a model that allows, with reasonable assumptions, determination of D(+) and D(-), and the degree of dissociation of the salt, α, at different concentrations, using the diffusion coefficients experimentally obtained with NMR. Also, it is shown that the NMR data suffice to estimate the conductivity of the electrolytes. The model was checked by means of experimental results of conductivity and NMR diffusion coefficients obtained with solutions of lithium triflate in ethylene and propylene carbonates, as well as with other results taken from the literature.

  2. Estimation of Synaptic Conductances in Presence of Nonlinear Effects Caused by Subthreshold Ionic Currents.

    PubMed

    Vich, Catalina; Berg, Rune W; Guillamon, Antoni; Ditlevsen, Susanne

    2017-01-01

    Subthreshold fluctuations in neuronal membrane potential traces contain nonlinear components, and employing nonlinear models might improve the statistical inference. We propose a new strategy to estimate synaptic conductances, which has been tested using in silico data and applied to in vivo recordings. The model is constructed to capture the nonlinearities caused by subthreshold activated currents, and the estimation procedure can discern between excitatory and inhibitory conductances using only one membrane potential trace. More precisely, we perform second order approximations of biophysical models to capture the subthreshold nonlinearities, resulting in quadratic integrate-and-fire models, and apply approximate maximum likelihood estimation where we only suppose that conductances are stationary in a 50-100 ms time window. The results show an improvement compared to existent procedures for the models tested here.

  3. Toward Higher Energy Conversion Efficiency for Solid Polymer Electrolyte Dye-Sensitized Solar Cells: Ionic Conductivity and TiO2 Pore-Filling.

    PubMed

    Song, Donghoon; Cho, Woohyung; Lee, Jung Hyun; Kang, Yong Soo

    2014-04-03

    Even though the solid polymer electrolyte has many intrinsic advantages over the liquid electrolyte, its ionic conductivity and mesopore-filling are much poorer than those of the liquid electrolyte, limiting its practical application to electrochemical devices such as dye-sensitized solar cells (DSCs). Two major shortcomings associated with utilizing solid polymer electrolytes in DSCs are first discussed, low ionic conductivity and poor pore-filling in mesoporous photoanodes for DSCs. In addition, future directions for the successful utilization of solid polymer electrolytes toward improving the performance of DSCs are proposed. For instance, the facilitated mass-transport concept could be applied to increase the ionic conductivity. Modified biphasic and triple-phasic structures for the photoanode are suggested to take advantage of both the liquid- and solid-state properties of electrolytes.

  4. Conductivity Modulation of Gold Thin Film at Room Temperature via All-Solid-State Electric-Double-Layer Gating Accelerated by Nonlinear Ionic Transport.

    PubMed

    Asano, Tetsuya; Kaneko, Yukihiro; Omote, Atsushi; Adachi, Hideaki; Fujii, Eiji

    2017-02-15

    We demonstrated the field-effect conductivity modulation of a gold thin film by all-solid-state electric-double-layer (EDL) gating at room temperature using an epitaxially grown oxide fast lithium conductor, La2/3-xLi3xTiO3 (LLT), as a solid electrolyte. The linearly increasing gold conductivity with increasing gate bias demonstrates that the conductivity modulation is indeed due to carrier injection by EDL gating. The response time becomes exponentially faster with increasing gate bias, a result of the onset of nonlinear ionic transportation. This nonlinear dynamic response indicates that the ionic motion-driven device can be much faster than would be estimated from a linear ionic transport model.

  5. Mixed Ionic/Electronic Conducting Surface Layers Adsorbed on Colloidal Silica for Flow Battery Applications.

    PubMed

    Richards, Jeffrey J; Scherbarth, Austin D; Wagner, Norman J; Butler, Paul D

    2016-09-14

    Slurry based electrodes have shown promise as an energy dense and scalable storage technology for electrochemical flow batteries. Key to their efficient operation is the use of a conductive additive which allows for volumetric charging and discharging of the electrochemically active species contained within the electrodes. Carbon black is commonly used for this purpose due to the relatively low concentrations needed to maintain electrical percolation. While carbon black supplies the desirable electrical properties for the application, it contributes detrimentally to the rheology characteristics of these concentrated suspensions. In this work, we develop a synthesis protocol to produce inorganic oxide particles with electrostatically adsorbed poly(3,4-ethylenedioxithiophene):polystyrenesulfonate ( PSS). Using a combination of small angle neutron scattering (SANS), electron microscopy, and thin-film conductivity, we show that the synthesis scheme provides a flexible platform to form conductive PSS-SiO2 nanoparticle dispersions. Based on these measurements, we demonstrate that these particles are stable when dispersed in propylene carbonate. Using a combination of rheology and dielectric spectroscopy, we show that these stable dispersions facilitate electrical percolation at concentrations below their mechanical percolation threshold, and this percolation is maintained under flow. These results demonstrate the potential for strategies which seek to decouple mechanical and electrical percolation to allow for the development of higher performance conductive additives for slurry based flow batteries.

  6. Pressure dependence of ionic conductivity of hydrated and dehydrated zeolites A

    NASA Astrophysics Data System (ADS)

    Goryainov, S. V.; Secco, R. A.; Huang, Y.; Liu, H.

    2007-03-01

    Hydrated and dehydrated zeolites MA (where M=Li, Na and K) with LTA structure have been studied by impedance spectroscopy with scanning frequency from 1 Hz to 1 MHz at high pressure up to 4.5 GPa and high temperature up to 250 °C. Anomalous increase in electrical AC conductivity at about 1.5-2 GPa observed in hydrated zeolites is associated with changes in crystalline structure leading to the formation of high-diffusion state of cation and water stuffing of the channels. In dehydrated zeolites, electrical conductivity is controlled by diffusion of cations (Li +, Na + and K +), which is determined by cation sites and aluminosilicate ring windows. LiA and NaA zeolites show normal decrease of conductivity with pressure, whereas KA zeolite exhibits the anomalous dependence with considerable increase and then fast decrease of conductivity. The behaviour of KA zeolite is associated with nearly central location of cation site in 8-membered ring, different from that in LiA and NaA zeolites.

  7. Structural origin of the enhanced ionic conductivity upon Nb doping in Sr11Mo4O23 defective double perovskite.

    PubMed

    Miranda, C D; López, C A; Pedregosa, J C; Alonso, J A

    2017-03-21

    We report a substantial enhancement of the oxide-ion conductivity in Sr11Mo4O23 achieved by Nb doping the Mo sites. This series responds to the formula: Sr11Mo4-xNbxO23-δ (with x = 0.0, 0.5 and 1.0). The original structure can be related to the conventional double perovskite; however, it presents a broken corner sharing connectivity of the octahedral framework, hence leading to a complex and highly defective network. The samples were prepared via citrate precursor method, followed by thermal treatments at 1300 °C for 12 hours in air. The crystal structures were refined from X-ray and neutron powder diffraction (NPD) data. A phase transition from tetragonal to cubic symmetry is identified in a temperature-dependent NPD study, driven by an oxygen delocalization effect. The ionic conductivity measured by impedance spectroscopy is enhanced upon Nb-doping; the x = 1 doped phase exhibits a threefold increase compared to the pristine Sr11Mo4O23 oxide, with conductivity values of 7.6 × 10(-3) and 2.7 × 10(-2) S·cm(-1) at 650 and 800 °C, which are even greater than for YSZ in the 650-800 °C temperature range, and close to those reported for other state-of-the art solid-oxide electrolytes.

  8. Microscopic signature of insulator-to-metal transition in highly doped semicrystalline conducting polymers in ionic-liquid-gated transistors

    SciTech Connect

    Tanaka, Hisaaki Nishio, Satoshi; Ito, Hiroshi; Kuroda, Shin-ichi

    2015-12-14

    Electronic state of charge carriers, in particular, in highly doped regions, in thin-film transistors of a semicrystalline conducting polymer poly(2,5-bis(3-alkylthiophene-2-yl)thieno[3,2-b]thiophene), has been studied by using field-induced electron spin resonance (ESR) spectroscopy. By adopting an ionic-liquid gate insulator, a gate-controlled reversible electrochemical hole-doping of the polymer backbone is achieved, as confirmed from the change of the optical absorption spectra. The edge-on molecular orientation in the pristine film is maintained even after the electrochemical doping, which is clarified from the angular dependence of the g value. As the doping level increases, spin 1/2 polarons transform into spinless bipolarons, which is demonstrated from the spin-charge relation showing a spin concentration peak around 1%, contrasting to the monotonic increase in the charge concentration. At high doping levels, a drastic change in the linewidth anisotropy due to the generation of conduction electrons is observed, indicating the onset of metallic state, which is also supported by the temperature dependence of the spin susceptibility and the ESR linewidth. Our results suggest that semicrystalline conducting polymers become metallic with retaining their molecular orientational order, when appropriate doping methods are chosen.

  9. Computational modeling of the structure and the ionic conductivity of the solid electrolyte materials Li3AsS4 and its Ge substitutions

    NASA Astrophysics Data System (ADS)

    Al-Qawasmeh, Ahmad; Holzwarth, N. A. W.

    Oak Ridge National Laboratory (G. Sahu et al.) reported that the substitution of Ge into Li3AsS4 leads to the composition Li3.334Ge0.334As0.666S4 with impressively high ionic conductivity . We use ab initio calculations to examine the structural relationships and the ionic conductivity mechanisms for pure Li3AsS4, Li3.334Ge0.334As0.666S4, and other compositions of these electrolytes. Supported by NSF Grant DMR-1105485 and 1507942 and WFU's DEAC cluster.

  10. Design and synthesis of guest-host nanostructures to enhance ionic conductivity across nanocomposite membranes

    DOEpatents

    Hu, Michael Z [Knoxville, TN; Kosacki, Igor [Oak Ridge, TN

    2010-01-05

    An ion conducting membrane has a matrix including an ordered array of hollow channels and a nanocrystalline electrolyte contained within at least some or all of the channels. The channels have opposed open ends, and a channel width of 1000 nanometers or less, preferably 60 nanometers or less, and most preferably 10 nanometers or less. The channels may be aligned perpendicular to the matrix surface, and the length of the channels may be 10 nanometers to 1000 micrometers. The electrolyte has grain sizes of 100 nanometers or less, and preferably grain sizes of 1 to 50 nanometers. The electrolyte may include grains with a part of the grain boundaries aligned with inner walls of the channels to form a straight oriented grain-wall interface or the electrolyte may be a single crystal. In one form, the electrolyte conducts oxygen ions, the matrix is silica, and the electrolyte is yttrium doped zirconia.

  11. Application for continuation of mixed ionic and electronic conductivity in polymers

    SciTech Connect

    Shiver, D.F.; Ratner, M.A.

    1990-01-01

    The aim in this portion of the research is to prepare new electroactive films with high ion mobility, and to characterize the transport properties of these materials. The classic conducting polymers, polyacetylene, polythiophene, and polypyrrole have dense structures that prevent rapid redox switching because of the low diffusivity of ions. The objective is to modify the last two polymers with pendant polyethers, which should greatly improve ion transport.

  12. Universal dielectric response of variously doped CeO{sub 2} ionically conducting ceramics

    SciTech Connect

    Nowick, A.S.; Vaysleyb, A.V.; Kuskovsky, I.

    1998-10-01

    The Jonscher power law, or {open_quotes}universal dielectric response{close_quotes} (UDR) behavior was studied for a range of CeO{sub 2} solid solutions with Y{sup 3+} and Gd{sup 3+} dopants, with particular emphasis on dilute systems which possess relatively simple defect structures. The results show power-law frequency dependence of the ac conductivity, with exponent s=0.61{plus_minus}0.03, independent of temperature and concentration. The conductivity data also show scaling behavior in terms of a time constant {tau}, whose activation energy is very close to that of the dc conductivity. For 1{percent} Y and 1{percent} Gd samples, an additional Debye-type relaxation is observed due to dopant{endash}oxygen-vacancy pairs. Such samples are clearly in the association range (stage III). These results contradict the assumption by Almond and West that {tau}{sup {minus}1} is the hopping frequency of the carrier defects. At very low concentrations ({approximately}0.01{percent}), UDR behavior virtually disappears. The present results are then compared to the principal theories that describe UDR behavior. It is found that, while each theory suffers from some drawbacks, the more phenomenological theories fare better. {copyright} {ital 1998} {ital The American Physical Society}

  13. Ionic conductivity in PEO-KOH polymer electrolytes and electrochemical cell performance

    NASA Astrophysics Data System (ADS)

    Hassan, M. F.; Arof, A. K.

    2005-10-01

    Polyethylene oxide (PEO) and potassium hydroxide (KOH) alkaline solid polymer electrolytes were prepared by the solution cast technique. The PEO:KOH wt% ratio in the alkaline solid polymer electrolyte system which exhibits the highest room temperature conductivity is 60:40. The conductivity was 3.10 × 10-5 S cm-1. X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS) were used to study the characteristics of the PEO polymer electrolyte films. The Rice and Roth model was used to evaluate the number density of charge carriers. Knowing the number density of charge carriers enabled the mobility and diffusion coefficient to be calculated. An all solid-state Ni(OH)2/MH rechargeable metal hydride cell has been fabricated using the highest conducting PEO-KOH alkaline solid polymer electrolyte. The cell was charged at a constant current of 2 mA and discharged at 0.5 mA. The discharge characteristics improved upon cycling and the plateau voltage maintained above 1.3 V for more than 2 hours during the 16th cycle.

  14. Studies on structural, thermal and AC conductivity scaling of PEO-LiPF6 polymer electrolyte with added ionic liquid [BMIMPF6

    NASA Astrophysics Data System (ADS)

    Chaurasia, S. K.; Saroj, A. L.; Shalu, Singh, V. K.; Tripathi, A. K.; Gupta, A. K.; Verma, Y. L.; Singh, R. K.

    2015-07-01

    Preparation and characterization of polymer electrolyte films of PEO+10wt.% LiPF6 + xwt.% BMIMPF6 (1-butyl-3-methylimidazolium hexafluorophosphate) containing dopant salt lithium hexafluorophosphate (LiPF6) and ionic liquid (BMIMPF6) having common anion PF6 - are reported. The ionic conductivity of the polymer electrolyte films has been found to increase with increasing concentration of BMIMPF6 in PEO+10 wt.% LiPF6 due to the plasticization effect of ionic liquid. DSC and XRD results show that the crystallinity of polymer electrolyte decreases with BMIMPF6 concentration which, in turn, is responsible for the increase in ionic conductivity. FTIR spectroscopic study shows the complexation of salt and/or ionic liquid cations with the polymer backbone. Ion dynamics behavior of PEO+LiPF6 as well as PEO+LiPF6 + BMIMPF6 polymer electrolytes was studied by frequency dependent conductivity, σ(f) measurements. The values σ(f) at various temperatures have been analyzed in terms of Jonscher power law (JPL) and scaled with respect to frequency which shows universal power law characteristics at all temperatures.

  15. Filler effect of ionic liquid attached titanium oxide on conducting property of poly(ethylene oxide)/poly(methyl methacrylate) composite electrolytes.

    PubMed

    Lee, Lyungyu; Kim, Ick-Jun; Yang, Sunhye; Kim, Seok

    2014-10-01

    Composite polymer electrolytes (CPEs) were prepared by containing blend of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) as a host polymer, propylene carbonate as a plasticizer, and LiClO4 as a salt. By an addition of a various content of ionic liquid attached TiO2 (IL-TiO2) to above electrolytes, the effects were studied. As a result, by increasing the IL-TiO2 content, the crystallinity of PEO was decreased and the ionic conductivity was increased. The ionic conductivity of CPEs was dependent on the content of IL-TiO2 and showed the highest value of 1.05 x 10(-4) S/cm at 9 wt.%. However, when IL-TiO2 content exceeds 9 wt.%, the ionic conductivity was decreased due to the slow ionic transport due to immiscibility or aggregation of the IL-TiO2 filler within the polymer film matrix.

  16. Slopes, nearly constant loss, universality, and hopping rates for dispersive ionic conduction

    NASA Astrophysics Data System (ADS)

    Macdonald, J. Ross; Ahmad, Mohamad M.

    2007-01-01

    The title topics are investigated, discussed, and new insights provided by considering isothermal frequency response data for seven different materials having quite different conductivity spans and involving different electrode polarization effects and temperatures. These data sets were fitted using several different models, including the Kohlrausch-related K0 and K1 ones derived from stretched-exponential response in the temporal domain. The quasi-universal UN model, the K1 with its shape parameter, β1, fixed at 1/3, fitted most of the data very well, and its fits of such data were used to compare its predictions for hopping rate with those derived from fitting with the conventional 'universal dynamic response' Almond-West real-part-of-conductivity model. The K1-model theoretical hopping rate, involving the mean waiting time for a hop and derived from microscopic stochastic analysis, was roughly twice as large as the empirical Almond-West rate for most of the materials considered and should be used in place of it. Its use in a generalized Nernst-Einstein equation led to comparison of estimates of the concentration of fully dissociated mobile charge carriers in superionic PbSnF4 with earlier estimates of Ahmad using an Almond-West hopping rate value. Agreement with an independent structure-derived value was relatively poor. Fitting results obtained using the K0 model, for Na2SO4 data sets for two different polycrystalline material phases, and involving severely limited conductivity variation, were far superior to those obtained using the K1 model. The estimated values of the K0 shape parameter, β0, were close to 1/3 for both phases, strongly suggesting that the charge motion was one dimensional for each phase, even though they involved different crystalline structures.

  17. Enhanced ionic conductivity and optical studies of plasticized (PEO-KCl) solid polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Chapi, Sharanappa; H, Devendrappa

    2015-06-01

    Solid polymer electrolytes (SPEs) based on Polyethylene oxide (PEO) doped with potassium chloride (KCl) were prepared by the solution cast technique. The conductivity increases from 10-10 to 10-6 Scm-1 at 303K with dopant. Optical absorption study shows that the direct & indirect optical band gaps were found decreased from 5.45-4.46eV and 4.96-3.86eV respectively with increasing the KCl. The XRD patterns reveal increasing the amorphous with increasing the dopent. The obtained results suggest that, these polymer systems are suitable candidates for solid state battery, electro chromic devices & optoelectronics display etc.

  18. Pressure-induced increase of ionic conduction of water-treated NaA zeolite

    NASA Astrophysics Data System (ADS)

    Secco, Richard A.; Goryainov, Sergei V.; Huang, Yining

    2005-07-01

    Dehydrated, hydrated and superhydrated NaA zeolites have been studied by impedance spectroscopy with scanning frequency from 1 Hz to 1 MHz at high pressure up to 4.5 GPa. A considerable anomalous increase in electrical conductivity in the range of 0.5-1.1 GPa was observed in superhydrated NaA zeolite containing additional water in the channels. A very high mobility of ions in superhydrated zeolite may be associated with the liquid-like state of the water-cation stuffing of zeolite channels.

  19. Electrical current dependence of the ionic conduction in Zn4Sb3

    NASA Astrophysics Data System (ADS)

    Kunioka, Haruno; Yamamoto, Atsushi; Iida, Tsutomu; Obara, Haruhiko

    2017-09-01

    The ion conduction in Zn4Sb3 was investigated to determine the potential of Zn4Sb3 as a thermoelectric element. Various temperature differences and electrical currents were applied and the resulting voltages were monitored for 1 h. The thermoelectric elements were analyzed after the tests by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX), resistance scanning, and Seebeck coefficient mapping. Zn ions migrated in the current direction and formed a ZnSb layer; the thickness was proportional to the current density and strongly dependent on the temperature.

  20. Charged local anesthetics block ionic conduction in the sheep cardiac sarcoplasmic reticulum calcium release channel.

    PubMed Central

    Tinker, A; Williams, A J

    1993-01-01

    We have examined the effect of the charged local anesthetics QX314, QX222, and Procaine on monovalent cation conduction in the Ca2+ release channel of the sheep cardiac sarcoplasmic reticulum. All three blockers only affect cation conductance when present at the cytoplasmic face of the channel. QX222 and Procaine act as voltage-dependent blockers. With 500 Hz filtering, this is manifest as a relatively smooth reduction in single-channel current amplitude most prominent at positive holding potentials. Quantitative analysis gives an effective valence of approximately 0.9 for both ions and Kb(0)s of 9.2 and 15.8 mM for QX222 and Procaine, respectively. Analysis of the concentration dependence of block suggests that QX222 is binding to a single site with a Km of 491 microM at a holding potential of 60 mV. The use of amplitude distribution analysis, with the data filtered at 1 to 2 kHz, reveals that the voltage and concentration dependence of QX222 block occurs largely because of changes in the blocker on rate. The addition of QX314 has a different effect, leading to the production of a substate with an amplitude of approximately one-third that of the control. The substate's occurrence is dependent on holding potential and QX314 concentration. Quantitative analysis reveals that the effect is highly voltage dependent, with a valence of approximately 1.5 caused by approximately equal changes in the on and off rates. Kinetic analysis of the concentration dependence of the substate occurrence reveals positive cooperativity with at least two QX314s binding to the conduction pathway, and this is largely accounted for by changes in the on rate. A paradoxical increase in the off rate at high positive holding potentials and with increasing QX314 concentration at 80 mV suggests the existence of a further QX314-dependent reaction that is both voltage and concentration dependent. The substate block is interpreted physically as a form of partial occlusion in the vestibule of the

  1. Ionic ac and dc conductivities of NaCrP2O7 compound

    NASA Astrophysics Data System (ADS)

    Sassi, M.; Oueslati, A.; Gargouri, M.

    2015-05-01

    The NaCrP2O7 compound was prepared by the solid-state reaction method. The formation of a single-phase material was confirmed by the X-ray diffraction studies and found to be a monoclinic system. The electrical properties of this compound have been measured in the temperature range from 523 to 673 K and the frequency range from 209 Hz to 5 MHz. The Nyquist plots are well fitted to an equivalent circuit consisting of a series of combination of grains and grain boundary elements. The ac conductivity of NaCrP2O7 has been analyzed as a function of temperature and frequency. The scaling behavior of the imaginary part of the complex modulus suggests that the relaxation describes the same mechanism at various temperatures. The conductivity and modulus formalisms provide nearly the same activation energies for electrical relaxation of mobile ions suggesting that the ion transport is probably due to a hopping mechanism dominated by the motion of the monovalent ions Na+ along tunnels presented in the structure of the investigated material.

  2. Porous polymer electrolytes with high ionic conductivity and good mechanical property for rechargeable batteries

    NASA Astrophysics Data System (ADS)

    Liang, Bo; Jiang, Qingbai; Tang, Siqi; Li, Shengliang; Chen, Xu

    2016-03-01

    Porous polymer electrolytes (PPEs) are attractive for developing lithium-ion batteries because of the combined advantages of liquid and solid polymer electrolytes. In the present study, a new porous polymer membrane doped with phytic acid (PA) is prepared, which is used as a crosslinker in polymer electrolyte matrix and can also plasticize porous polymer electrolyte membranes, changing them into soft tough flexible materials. A PEO-PMMA-LiClO4-x wt.% PA (x = weight of PA/weight of polymer, PEO: poly(ethylene oxide); PMMA: poly(methyl methacrylate)) polymer membrane is prepared by a simple evaporation method. The effects of the ratio of PA to PEO-PMMA on the properties of the porous membrane, including morphology, porous structure, and mechanical property, are systematically studied. PA improves the porous structure and mechanical properties of polymer membrane. The maximum tensile strength and elongation of the porous polymer membranes are 20.71 MPa and 45.7% at 15 wt.% PA, respectively. Moreover, the PPEs with 15 wt.% PA has a conductivity of 1.59 × 10-5 S/cm at 20 °C, a good electrochemical window (>5 V), and a low interfacial resistance. The results demonstrate the compatibility of the mechanical properties and conductivity of the PPEs, indicating that PPEs have good application prospects for lithium-ion batteries.

  3. Lead titanate/cyclic carbonate dependence on ionic conductivity of ferro/acrylate blend polymer composites

    NASA Astrophysics Data System (ADS)

    Jayaraman, R.; Vickraman, P.; Subramanian, N. M. V.; Justin, A. Simon

    2016-05-01

    Impedance, XRD, DSC and FTIR studies had been carried out for PVdF-co-HFP/LIBETI based system for three plasticizer (EC/DMC) - filler (PbTiO3) weight ratios. The enhanced conductivity 4.18 × 10-5 Scm-1 was noted for 57.5 wt% -7.5 wt% plasticizer - filler. while blending PEMA to PVdF-co-HFP respectively 7.5: 22.5 wt % (3/7), 15 wt%: 15 wt % (5/5) and 22.5wt %: 7.5 wt % (7/3), the improved conductivity was noted for 3/7 ratio 1.22 × 10-5 S cm-1 and its temperature dependence abide Arrhenius behavior. The intensity of peaks in XRD diffractogram registered dominance of lead titanate, from 2θ = 10° to 80° and absence of VdF crystallites (α+β phase) was noted. In DSC studies, the presence of the exotherm events, filler effect was distinctively seen exhibiting recrystallization of VdF crystallites. In blending PEMA, however, no trace of exotherms was found suggestive of PEMA better inhibiting recrystallization. FTIR study confirmed molecular interactions of various constituents in the vibrational band 500 - 1000 cm-1 both in pristine PVdF-co-HFP and PEMA blended composites with reference to C-F stretching, C-H stretching and C=O carbonyl bands.

  4. Lead titanate/cyclic carbonate dependence on ionic conductivity of ferro/acrylate blend polymer composites

    SciTech Connect

    Jayaraman, R.; Vickraman, P. Subramanian, N. M. V.; Justin, A. Simon

    2016-05-23

    Impedance, XRD, DSC and FTIR studies had been carried out for PVdF-co-HFP/LIBETI based system for three plasticizer (EC/DMC) – filler (PbTiO3) weight ratios. The enhanced conductivity 4.18 × 10{sup −5} Scm{sup −1} was noted for 57.5 wt% −7.5 wt% plasticizer – filler. while blending PEMA to PVdF-co-HFP respectively 7.5: 22.5 wt % (3/7), 15 wt%: 15 wt % (5/5) and 22.5wt %: 7.5 wt % (7/3), the improved conductivity was noted for 3/7 ratio 1.22 × 10{sup −5} S cm{sup −1} and its temperature dependence abide Arrhenius behavior. The intensity of peaks in XRD diffractogram registered dominance of lead titanate, from 2θ = 10° to 80° and absence of VdF crystallites (α+β phase) was noted. In DSC studies, the presence of the exotherm events, filler effect was distinctively seen exhibiting recrystallization of VdF crystallites. In blending PEMA, however, no trace of exotherms was found suggestive of PEMA better inhibiting recrystallization. FTIR study confirmed molecular interactions of various constituents in the vibrational band 500 – 1000 cm{sup −1} both in pristine PVdF-co-HFP and PEMA blended composites with reference to C-F stretching, C-H stretching and C=O carbonyl bands.

  5. Effect of matrix crystallinity on the ionic conductivity in microstructured block copolymer solid electrolytes

    NASA Astrophysics Data System (ADS)

    Young, Nicholas; Balsara, Nitash

    2012-02-01

    Polyethylene oxide (PEO)-based block copolymers have been studied extensively for use as solid electrolytes for rechargeable lithium metal batteries. Previous work has concentrated on block copolymers containing an amorphous second block, such as polystyrene, for which the modulus is sufficiently high to resist growth of dendrites that would lead to short circuiting. In this work, we instead focus on using semicrystalline polyethylene as the mechanically robust component. Polyethylene-polyethylene oxide (EEO) block copolymers doped with lithium bis(trifluoromethanesulfone) imide (LiTFSI) were characterized using AC impedance spectroscopy over a range of temperature, molecular weight, and composition values in order to determine the effect of crystallinity in the structural microphase on the conductivity of this material.

  6. Atomistic simulations of ammonium-based protic ionic liquids: steric effects on structure, low frequency vibrational modes and electrical conductivity.

    PubMed

    Sunda, Anurag Prakash; Mondal, Anirban; Balasubramanian, Sundaram

    2015-02-14

    Protic ionic liquids (PILs) are of great interest as electrolytes in various energy applications. Molecular dynamics simulations of trialkylammonium (with varying alkyl group such as methyl, ethyl, and n-propyl) triflate PILs are performed to characterize the influence of the alkyl group on the acidic site (N-H) of the ammonium cation. Spatial distribution function of anions over this site on the cation reveals significant influence of the length of alkyl tail on intermolecular structure. Vibrational density of states and normal modes are calculated for bulk liquids to probe atomic displacements in the far infrared region. The observed N-H···O hydrogen bond stretching vibration in 155-165 cm(-1) frequency region agrees well with experiments. Trends in electrical conductivity calculated using Nernst-Einstein and Green-Kubo relation are in qualitative agreement with experiments. The self-diffusion coefficient and the electrical conductivity is highest for N,N-dimethyl-N-ethylammonium triflate ([N112][TfO]) and is lowest for N,N-di-n-propyl-N-methylammonium triflate ([N133][TfO]) IL.

  7. Conductance, a contrivance to explore ion association and solvation behavior of an ionic liquid (tetrabutylphosphonium tetrafluoroborate) in acetonitrile, tetrahydrofuran, 1,3-dioxolane, and their binaries.

    PubMed

    Ekka, Deepak; Roy, Mahendra Nath

    2012-09-27

    Precise measurements on electrical conductance (Λ) of solutions of an ionic liquid (IL) tetrabutylphosphonium tetrafluoroborate in acetonitrile (ACN), tetrahydrofuran (THF), and 1,3-dioxolane (1,3-DO) and their binary mixtures have been reported at 298.15 K. The conductance data have been analyzed by the Fuoss conductance equation (1978) in terms of the limiting molar conductance (Λ(o)), the association constant (K(A)), and the association diameter (R) for ion-pair formation. The Walden product is obtained and discussed. However, the deviation of the conductometric curves (Λ versus √c) from linearity for the electrolyte in THF and 1,3-DO and their binary mixtures indicated triple-ion formation and therefore the corresponding conductance data have been analyzed by the Fuoss–Kraus theory of triple ions. The limiting ionic conductances (λ(o)(±)) have been estimated from the appropriate division of the limiting molar conductivity value of tetrabutylammonium tetraphenylborate [Bu(4)NBPh(4)] as the “reference electrolyte” method along with a numerical evaluation of ion-pair and triple-ion formation constants (K(P) ≈ K(A) and K(T)). The results have been discussed in terms of solvent properties and configurational theory. Ionic association in the limiting molar conductances as well as the single-ion conductivity values have been determined for the electrolyte in the solvent media.

  8. Ionic Conductivity and Potential Application for Fuel Cell of a Modified Imine-Based Covalent Organic Framework.

    PubMed

    Montoro, Carmen; Rodríguez-San-Miguel, David; Polo, Eduardo; Escudero-Cid, Ricardo; Ruiz-González, Maria Luisa; Navarro, Jorge A R; Ocón, Pilar; Zamora, Félix

    2017-07-26

    We present the novel potential application of imine-based covalent organic frameworks (COFs), formed by the direct Schiff reaction between 1,3,5-tris(4-aminophenyl)benzene and 1,3,5-benzenetricarbaldehyde building blocks in m-cresol or acetic acid, named RT-COF-1 or RT-COF-1Ac/RT-COF-1AcB. The post-synthetic treatment of RT-COF-1 with LiCl leads to the formation of LiCl@RT-COF-1. The ionic conductivity of this series of polyimine COFs has been characterized at variable temperature and humidity, using electrochemical impedance spectroscopy. LiCl@RT-COF-1 exhibits a conductivity value of 6.45 × 10(-3) S cm(-1) (at 313 K and 100% relative humidity) which is among the highest values so far reported in proton conduction for COFs. The mechanism of conduction has been determined using (1)H and (7)Li solid-state nuclear magnetic resonance spectroscopy. Interestingly, these materials, in the presence of controlled amounts of acetic acid and under pressure, show a remarkable processability that gives rise to quasi-transparent and flexible films showing in-plane structural order as confirmed by X-ray crystallography. Finally, we prove that these films are useful for the construction of proton exchange membrane fuel cells (PEMFC) reaching values up to 12.95 mW cm(-2) and 53.1 mA cm(-2) for maximum power and current density at 323 K, respectively.

  9. Study of Mast Cells and Granules from Primo Nodes Using Scanning Ionic Conductance Microscopy.

    PubMed

    Yoo, Yeong-Yung; Jung, Goo-Eun; Kwon, Hee-Min; Bae, Kyoung-Hee; Cho, Sang-Joon; Soh, Kwang-Sup

    2015-12-01

    Acupuncture points have a notable characteristic in that they have a higher density of mast cells (MCs) compared with nonacupoints in the skin, which is consistent with the augmentation of the immune function by acupuncture treatment. The primo vascular system, which was proposed as the anatomical structure of the acupuncture points and meridians, also has a high density of MCs. We isolated the primo nodes from the surfaces of internal abdominal organs, and the harvested primo nodes were stained with toluidine blue. The MCs were easily recognized by their stained color and their characteristic granules. The MCs were classified into four stages according to the degranulation of histamine granules in the MCs. Using conventional optical microscopes details of the degranulation state of MCs in each stage were not observable. However, we were able to investigate the distribution of the granules on the surfaces of the MCs in each stage, and to demonstrate the height profiles and three-dimensional structures of the MCs without disturbance of the cell membrane by using the scanning ion conductance microscopy.

  10. Tissue acidosis induces neuronal necroptosis via ASIC1a channel independent of its ionic conduction.

    PubMed

    Wang, Yi-Zhi; Wang, Jing-Jing; Huang, Yu; Liu, Fan; Zeng, Wei-Zheng; Li, Ying; Xiong, Zhi-Gang; Zhu, Michael X; Xu, Tian-Le

    2015-11-02

    Acidotoxicity is common among neurological disorders, such as ischemic stroke. Traditionally, Ca(2+) influx via homomeric acid-sensing ion channel 1a (ASIC1a) was considered to be the leading cause of ischemic acidotoxicity. Here we show that extracellular protons trigger a novel form of neuronal necroptosis via ASIC1a, but independent of its ion-conducting function. We identified serine/threonine kinase receptor interaction protein 1 (RIP1) as a critical component of this form of neuronal necroptosis. Acid stimulation recruits RIP1 to the ASIC1a C-terminus, causing RIP1 phosphorylation and subsequent neuronal death. In a mouse model of focal ischemia, middle cerebral artery occlusion causes ASIC1a-RIP1 association and RIP1 phosphorylation in affected brain areas. Deletion of the Asic1a gene significantly prevents RIP1 phosphorylation and brain damage, suggesting ASIC1a-mediated RIP1 activation has an important role in ischemic neuronal injury. Our findings indicate that extracellular protons function as a novel endogenous ligand that triggers neuronal necroptosis during ischemia via ASIC1a independent of its channel function.

  11. A Comparison of the Activation Enthalpies for Ionic Conduction in Animal and Plant Tissue

    NASA Astrophysics Data System (ADS)

    Hart, Francis X.

    1997-11-01

    The electrical properties of biological materials are determined by the transport of ions. There are two stages in the transport of an ion along a surface, such as a cell membrane: ``detrapping'' of the ion from a binding site and (2) ``hopping'' of the freed ion from site to site. An activation enthalpy can be determined for each stage by measuring the impedance spectrum of the tissue over a range of temperatures. A Hewlett Packard 4192A Low Frequency Impedance Analyzer was used to measure the impedance spectra of apples and of crayfish tail muscle over a range of temperatures from about 15^oC to 35^oC. At each temperature a complex-valued, non-linear, least-squares fit of the impedance data was made to a three-component circuit model. From the fitted model values the low frequency tissue conductivity and the high frequency power-law exponent and prefactor were obtained. Arrhenius plots yielded separate activation enthalpies for the detrapping (Hf) and hopping (Hm). For both apples and crayfish Hf is on the order of kT (0.025 eV) whereas Hm is on the order of 0.15 eV.

  12. Changes in Ionic Conductance Signature of Nociceptive Neurons Underlying Fabry Disease Phenotype

    PubMed Central

    Namer, Barbara; Ørstavik, Kirstin; Schmidt, Roland; Mair, Norbert; Kleggetveit, Inge Petter; Zeidler, Maximillian; Martha, Theresa; Jorum, Ellen; Schmelz, Martin; Kalpachidou, Theodora; Kress, Michaela; Langeslag, Michiel

    2017-01-01

    The first symptom arising in many Fabry patients is neuropathic pain due to changes in small myelinated and unmyelinated fibers in the periphery, which is subsequently followed by a loss of sensory perception. Here we studied changes in the peripheral nervous system of Fabry patients and a Fabry mouse model induced by deletion of α-galactosidase A (Gla−/0). The skin innervation of Gla−/0 mice resembles that of the human Fabry patients. In Fabry diseased humans and Gla−/0 mice, we observed similar sensory abnormalities, which were also observed in nerve fiber recordings in both patients and mice. Electrophysiological recordings of cultured Gla−/0 nociceptors revealed that the conductance of voltage-gated Na+ and Ca2+ currents was decreased in Gla−/0 nociceptors, whereas the activation of voltage-gated K+ currents was at more depolarized potentials. Conclusively, we have observed that reduced sensory perception due to small-fiber degeneration coincides with altered electrophysiological properties of sensory neurons. PMID:28769867

  13. Tissue acidosis induces neuronal necroptosis via ASIC1a channel independent of its ionic conduction

    PubMed Central

    Wang, Yi-Zhi; Wang, Jing-Jing; Huang, Yu; Liu, Fan; Zeng, Wei-Zheng; Li, Ying; Xiong, Zhi-Gang; Zhu, Michael X; Xu, Tian-Le

    2015-01-01

    Acidotoxicity is common among neurological disorders, such as ischemic stroke. Traditionally, Ca2+ influx via homomeric acid-sensing ion channel 1a (ASIC1a) was considered to be the leading cause of ischemic acidotoxicity. Here we show that extracellular protons trigger a novel form of neuronal necroptosis via ASIC1a, but independent of its ion-conducting function. We identified serine/threonine kinase receptor interaction protein 1 (RIP1) as a critical component of this form of neuronal necroptosis. Acid stimulation recruits RIP1 to the ASIC1a C-terminus, causing RIP1 phosphorylation and subsequent neuronal death. In a mouse model of focal ischemia, middle cerebral artery occlusion causes ASIC1a-RIP1 association and RIP1 phosphorylation in affected brain areas. Deletion of the Asic1a gene significantly prevents RIP1 phosphorylation and brain damage, suggesting ASIC1a-mediated RIP1 activation has an important role in ischemic neuronal injury. Our findings indicate that extracellular protons function as a novel endogenous ligand that triggers neuronal necroptosis during ischemia via ASIC1a independent of its channel function. DOI: http://dx.doi.org/10.7554/eLife.05682.001 PMID:26523449

  14. Preparation, characterization and single cell testing of new ionic conducting polymers for fuel cell applications

    NASA Astrophysics Data System (ADS)

    Escribano, P. G.; del Río y, C.; Acosta, J. L.

    In this work, heterogeneous sulfonation and both, structural and electrical characterization of a mixture composed on block copolymer ionomers (HSBS and EPDM) and commercial silica, are studied. The incorporation of sulfonic groups was checked by infrared spectroscopy (FTIR-ATR). Microstructure was studied by means of dynamic mechanical analysis (DMA). Also, water uptake and methanol crossover were determined, and the results were compared with those of Nafion ® 117. Electrical behavior was recorded by means of electrochemical impedance spectroscopy (EIS) at different hydration times. Results show that sulfonation of the styrene rings has effectively occurred. Conductivity values are similar to Nafion and they improve with hydration time. Methanol crossover is lower than in Nafion. Finally, a single complete proton exchange membrane fuel cell (PEMFC) as a whole was tested obtaining the polarization and power curves at different temperatures and pressures, and modeling it by an electrical equivalent circuit (EC) in the symmetrical mode (SM) configuration using the EIS technique. This study offers a physical interpretation relating physical parameters to several processes occurring in the system. Power density values are higher than in Nafion.

  15. Thermal, mechanical and ionic conductive behaviour of gamma-radiation induced PEO/PVDF(SIN)-LiClO 4 polymer electrolyte system

    NASA Astrophysics Data System (ADS)

    Song, Yongxian; Wu, Shuyun; Jing, Xiabing; Sun, Jiazhen; Chen, Donglin

    1997-05-01

    An effort has been made to modify the mechanical behaviour of our previously reported gel-type gamma-radiation crosslinked polyethylene oxide (PEO)-LiClO 4 polymer electrolyte. A highly polar and gamma-radiation crosslinkable crystalline polymer, polyvinylidene fluoride (PVDF), was selected to blend with PEO and then subjected to gamma-irradiation in order to make an simultaneous interpenetrating network (SIN), which was used as a polymer host to impart stiffness to the plasticized system. Experimental results have shown that the presence of PVDF in the system, through gamma-radiation induced SIN formation, could not only give a rather high mechanical modulus of 10 7 Pa at ambient temperature, but also maintain the room temperature ionic conductivity at a high level (greater than 10 -4 S/cm). DSC, DMA and conductivity measurement techniques were used to examine the effects of blending, gamma-irradiation and plasticization on the variations of glass transition and melting endotherm, on the appearance of high elastic plateau and on the temperature dependence of ionic conductivity. In addition, it was found that, in contrast with the unplasticized system, the ionic conductivity mechanism of this gel-type electrolyte seems to conform to the Arrhenius model, suggesting that, as a result of the high degree of plasticization, the polymer chains act mainly as the skeleton of the networks or polymer cages to immobilize the liquid electrolyte solution, whereas the ionic species migrate as if they were in a liquid medium.

  16. Enhanced Ionic Conductivity and Power Generation Using Ion-Exchange Resin Beads in a Reverse-Electrodialysis Stack.

    PubMed

    Zhang, Bopeng; Gao, Haiping; Chen, Yongsheng

    2015-12-15

    Reverse electrodialysis (RED) is a promising technique for harvesting energy by mixing seawater with river water. The energy production is usually limited by ionic conductivity in dilute compartments of a RED system. Novel tests were conducted in this research, which used ion-exchange resin beads (IERB) to replace nonconductive spacer fabrics in RED compartments with dilute NaCl solution in a modified stack containing Fumasep FKS and Fumasep FAS membranes. We compared the conductivity of an IERB packed bed with that of an inert glass-beads-packed bed as a control to confirm IERB's effectiveness. When applied in a RED system, IERB decreased the stack resistance by up to 40%. The maximum gross power density improved by 83% in the RED stack compared to that in a regular RED stack at 1.3 cm/s average linear flow velocity. IERB-filled stack resistance was modeled. The model results fit well with experimental data, thereby confirming the effectiveness of the new approach presented here. The net power density is also estimated based on the measured pressure drop and pumping energy model. Both gross and net power density was improved by over 75% at higher flow rate. A net power density of 0.44 W/m(2) was achieved at a cell thickness of 500 μm. To the best of our knowledge, this research is the first to study the impact of IERB on power generation and establishes a new approach to improving the power performance of a RED system.

  17. Ionic conduction in Sn 1- xSc xP 2O 7 for intermediate temperature fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Hongtao; Zhang, Hongmin; Xiao, Guoxian; Zhang, Feng; Yu, Tian; Xiao, Jia; Ma, Guilin

    A novel series of mixed ion conductors, Sn 1- xSc xP 2O 7 (x = 0.03, 0.06, 0.09, 0.12), were synthesized by a solid-state reaction method. The conduction behaviors of the ion conductors in wet hydrogen atmosphere were investigated by some electrochemical methods including AC impedance spectroscopy, gas concentration cells in the temperature range of 323-523 K. It was found that the doping limit of Sc 3+ in SnP 2O 7 was between 9 mol% and 12 mol%. The highest conductivity was observed to be 2.76 × 10 -2 S cm -1 for the sample of x = 0.06 under wet H 2 atmosphere at 473 K. The ionic conduction was contributed mainly to proton and partially to oxide ion in wet hydrogen atmosphere from 373 K to 523 K. The H 2/air fuel cells using Sn 1- xSc xP 2O 7 (x = 0.03, 0.06, 0.09) as electrolytes (1.7 mm in thickness) generated the maximum power densities of 11.16 mW cm -2 for x = 0.03, 25.02 mW cm -2 for x = 0.06 and 14.34 mW cm -2 for x = 0.09 at 423 K, respectively. The results indicated that Sn 1- xSc xP 2O 7 is a promising solid electrolyte system for intermediate temperature fuel cells.

  18. Dielectric α-relaxation and ionic conductivity in propylene glycol and its oligomers measured at elevated pressure

    NASA Astrophysics Data System (ADS)

    Casalini, Riccardo; Roland, C. Michael

    2003-12-01

    Structural dynamics and volume were measured as a function of both temperature and pressure for a propylene glycol and its oligomers (PPG), and the results compared with previous data on higher molecular weight polypropylene glycols. PPG is of special interest because the terminal groups form hydrogen bonds; thus, by studying different molecular weights, the manner in which hydrogen bonding influences the dynamics in the supercooled regime can be systematically investigated. The fragility (Tg-normalized temperature dependence) of the dimer and trimer of PPG increases with pressure, similar to results for other H-bonded liquids, but different from van der Waals glass formers. This behavior is believed to be due to the effect of pressure in decreasing the extent of hydrogen bonding. From the combined temperature and volume dependences of the relaxation times, the relative degree to which thermal energy and volume govern the dynamics was quantified. With decreasing molecular weight, the relative contribution of thermal energy to the dynamics was found to strongly increase, reflecting the role of hydrogen bonding. By comparing the ionic conductivity and the dielectric relaxation times, a decoupling between rotational and translational motions was observed. Interestingly, this decoupling was independent of both pressure and molecular weight, indicating that hydrogen bonds have a negligible effect on the phenomenon.

  19. Ionic conductivity studies of solid oxide fuel cell electrolytes and theoretical modeling of an entire solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Pornprasertsuk, Rojana

    Because of the steep increase in oil prices, the global warming effect and the drive for energy independence, alternative energy research has been encouraged worldwide. The sustainable fuels such as hydrogen, biofuel, natural gas, and solar energy have attracted the attention of researchers. To convert these fuels into a useful energy source, an energy conversion device is required. Fuel cells are one of the energy conversion devices which convert chemical potentials into electricity. Due to their high efficiency, the ease to scale from 1 W range to megawatts range, no recharging requirement and the lack of CO2 and NOx emission (if H2 and air/O 2 are used), fuel cells have become a potential candidate for both stationary power generators and portable applications. This thesis has been focused primarily on solid oxide fuel cell (SOFC) studies due to its high efficiency, varieties of fuel choices, and no water management problem. At the present, however, practical applications of SOFCs are limited by high operating temperatures that are needed to create the necessary oxide-ion vacancy mobility in the electrolyte and to create sufficient electrode reactivities. This thesis introduces several experimental and theoretical approaches to lower losses both in the electrolyte and the electrodes. Yttria stabilized zirconia (YSZ) is commonly used as a solid electrolyte for SOFCs due to its high oxygen-ion conductivity. To improve the ionic conductivity for low temperature applications, an approach that involves dilating the structure by irradiation and introducing edge dislocations into the electrolyte was studied. Secondly, to understand the activation loss in SOFC, the kinetic Monte Carlo (KMC) technique was implemented to model the SOFC operation to determining the rate-limiting step due to the electrodes on different sizes of Pt catalysts. The isotope exchange depth profiling technique was employed to investigate the irradiation effect on the ionic transport in different

  20. Effect of the structural evolution on the ionic conductivity of Li-N-H system during the dehydrogenation

    NASA Astrophysics Data System (ADS)

    Paik, Biswajit; Matsuo, Motoaki; Sato, Toyoto; Qu, Liyuan; Wolczyk, Anna Roza; Orimo, Shin-ichi

    2016-05-01

    On the way to transform lithium amide (LiNH2) into lithium imide (Li2NH) by releasing H2, the 1:1 molar mixture of LiNH2-LiH forms cubic ( F m 3 ¯ m ) non-stoichiometric complex hydride phases (Li1+xNH2-x; 0 < x < 1) that co-exist with the tetragonal ( I 4 ¯ ) LiNH2 and with the cubic ( F d 3 ¯ m ) Li2NH, respectively, at the early and at the advanced stage of the dehydrogenation. The change in LiNH2 → Li2NH may be viewed as a mechanism which continuously fills up the vacant Li sites of the tetragonal structure and, in a parallel process, transforms the anions [NH2]- → [NH]2-. The Li-N-H system, thus formed, by releasing >6 wt. % H2 can offer high Li-ionic conductivity (>10-4 S.cm-1 at room temperature) having an electrochemical stability window >5 V. The study suggests that the Li-N-H system may be a prospective electrolyte in the all-solid-state Li-ion battery, in addition to its use as a reversible hydrogen storage material.

  1. Ionic Conductivity Increased by Two Orders of Magnitude in Micrometer-Thick Vertical Yttria-Stabilized ZrO 2 Nanocomposite Films

    DOE PAGES

    Lee, Shinbuhm; Zhang, Wenrui; Khatkhatay, Fauzia; ...

    2015-09-03

    We design and create a unique cell geometry of templated micrometer-thick epitaxial nanocomposite films which contain ~20 nm diameter yttria-stabilized ZrO2 (YSZ) nanocolumns, strain coupled to a SrTiO3 matrix. We also enhanced the ionic conductivity of these nanocolumnsby over 2 orders of magnitude compared to plain YSZ films. Concomitant with the higher ionic conduction is the finding that the YSZ nanocolumns in the films have much higher crystallinity and orientation, compared to plain YSZ films. Hence, “oxygen migration highways” are formed in the desired out-of-plane direction. This improved structure is shown to originate from the epitaxial coupling of the YSZmore » nanocolumns to the SrTiO3 film matrix and from nucleation of the YSZ nanocolumns on an intermediate nanocomposite base layer of highly aligned Sm-doped CeO2 nanocolumns within the SrTiO3 matrix. Furthermore, this intermediate layer reduces the lattice mismatch between the YSZ nanocolumns and the substrate. Vertical ionic conduction values as high as 10–2 Ω–1 cm–1 were demonstrated at 360 °C (300 °C lower than plain YSZ films), showing the strong practical potential of these nanostructured films for use in much lower operation temperature ionic devices.« less

  2. Ionic Conductivity Increased by Two Orders of Magnitude in Micrometer-Thick Vertical Yttria-Stabilized ZrO 2 Nanocomposite Films

    SciTech Connect

    Lee, Shinbuhm; Zhang, Wenrui; Khatkhatay, Fauzia; Wang, Haiyan; Jia, Quanxi; MacManus-Driscoll, Judith L.

    2015-09-03

    We design and create a unique cell geometry of templated micrometer-thick epitaxial nanocomposite films which contain ~20 nm diameter yttria-stabilized ZrO2 (YSZ) nanocolumns, strain coupled to a SrTiO3 matrix. We also enhanced the ionic conductivity of these nanocolumnsby over 2 orders of magnitude compared to plain YSZ films. Concomitant with the higher ionic conduction is the finding that the YSZ nanocolumns in the films have much higher crystallinity and orientation, compared to plain YSZ films. Hence, “oxygen migration highways” are formed in the desired out-of-plane direction. This improved structure is shown to originate from the epitaxial coupling of the YSZ nanocolumns to the SrTiO3 film matrix and from nucleation of the YSZ nanocolumns on an intermediate nanocomposite base layer of highly aligned Sm-doped CeO2 nanocolumns within the SrTiO3 matrix. Furthermore, this intermediate layer reduces the lattice mismatch between the YSZ nanocolumns and the substrate. Vertical ionic conduction values as high as 10–2 Ω–1 cm–1 were demonstrated at 360 °C (300 °C lower than plain YSZ films), showing the strong practical potential of these nanostructured films for use in much lower operation temperature ionic devices.

  3. Diketonylpyridinium Cations as a Support of New Ionic Liquid Crystals and Ion-Conductive Materials: Analysis of Counter-Ion Effects

    PubMed Central

    Pastor, María Jesús; Cuerva, Cristián; Campo, José A.; Schmidt, Rainer; Torres, María Rosario; Cano, Mercedes

    2016-01-01

    Ionic liquid crystals (ILCs) allow the combination of the high ionic conductivity of ionic liquids (ILs) with the supramolecular organization of liquid crystals (LCs). ILCs salts were obtained by the assembly of long-chained diketonylpyridinium cations of the type [HOOR(n)pyH]+ and BF4−, ReO4−, NO3−, CF3SO3−, CuCl42− counter-ions. We have studied the thermal behavior of five series of compounds by differential scanning calorimetry (DSC) and hot stage polarized light optical microscopy (POM). All materials show thermotropic mesomorphism as well as crystalline polymorphism. X-ray diffraction of the [HOOR(12)pyH][ReO4] crystal reveals a layered structure with alternating polar and apolar sublayers. The mesophases also exhibit a lamellar arrangement detected by variable temperature powder X-ray diffraction. The CuCl42− salts exhibit the best LC properties followed by the ReO4− ones due to low melting temperature and wide range of existence. The conductivity was probed for the mesophases in one species each from the ReO4−, and CuCl42− families, and for the solid phase in one of the non-mesomorphic Cl− salts. The highest ionic conductivity was found for the smectic mesophase of the ReO4− containing salt, whereas the solid phases of all salts were dominated by electronic contributions. The ionic conductivity may be favored by the mesophase lamellar structure. PMID:28773485

  4. Phase behavior of 1-dodecyl-3-methylimidazolium fluorohydrogenate salts (C12MIm(FH)(n)F, n = 1.0-2.3) and their anisotropic ionic conductivity as ionic liquid crystal electrolytes.

    PubMed

    Xu, Fei; Matsumoto, Kazuhiko; Hagiwara, Rika

    2012-08-23

    The effects of the HF composition, n, in 1-dodecyl-3-methylimidazolium fluorohydrogenate salts (C(12)MIm(FH)(n)F, n = 1.0-2.3) on their physicochemical and structural properties have been investigated using infrared spectroscopy, thermal analysis, polarized optical microscopy, X-ray diffraction, and anisotropic ionic conductivity measurements. The phase diagram of C(12)MIm(FH)(n)F (n vs transition temperature) suggests that C(12)MIm(FH)(n)F is a mixed crystal system that has a boundary around n = 1.9. For all compositions, a liquid crystalline mesophase with a smectic A interdigitated bilayer structure is observed. The temperature range of the mesophase decreases with increasing n value (from 61.8 °C for C(12)MIm(FH)(1.0)F to 37.0 °C for C(12)MIm(FH)(2.3)F). The layer spacing of the smectic structure decreases with increasing n value or increasing temperature. Two structural types with different layer spacings are observed in the crystalline phase (type I, 1.0 ≤ n ≤ 1.9, and type II, 1.9 ≤ n ≤ 2.3). Ionic conductivities parallel and perpendicular to the smectic layers (σ(||) and σ([perpendicular])) increase with increasing n value, whereas the anisotropy of the ionic conductivities (σ(||)/σ([perpendicular])) is independent of the n value, since the thickness of the insulating sheet formed by the dodecyl group remains nearly unchanged.

  5. Deciphering Physical Versus Chemical Contributions to the Ionic Conductivity of Functionalized Poly(methacrylate)-Based Ionogel Electrolytes. Supporting Information

    DTIC Science & Technology

    2015-11-03

    25-39 mol%). S4 Supplementary Discussion on ‘Apparent’ vs. ‘Effective’ vs. ‘True’ Diffusivity Values and Ionicity vs. Degree of Ionic...Dissociation As noted in several previous PGSE NMR spectroscopy-enabled diffusion studies of ILs or polymer/IL blends,1-4 the rate of exchange between...essential to recognize that the apparent diffusivity values obtained for cations (!!"#, from the 1H signal) and anions (!!"#, from the 19F signal

  6. A Metal-Organic Framework Impregnated with a Binary Ionic Liquid for Safe Proton Conduction above 100 °C.

    PubMed

    Sun, Xiao-Li; Deng, Wei-Hua; Chen, Hui; Han, Hong-Liang; Taylor, Jared M; Wan, Chong-Qing; Xu, Gang

    2017-01-26

    To develop proton-conducting materials under low-humidity conditions and at moderate working temperature still remains challenging for fuel-cell technology. Here, a new type of proton-conducting material, EIMS-HTFSA@MIL, which was prepared by impregnating the binary ionic liquid, EIMS-HTFSA (EIMS=1-(1-ethyl-3-imidazolium)propane-3-sulfonate; HTFSA=N,N-bis(trifluoromethanesulfonyl)amide), into a mesoporous metal-organic framework, MIL-101 ([Cr3 F(H2 O)2 O(BDC)3 ⋅n H2 O] (n≈0.25, BDC=1,4-benzenedicarboxylate)) is reported. By taking advantage of the ionic-liquid properties, such as high thermal stability, non-volatility, non-flammability, and low corrosivity, EIMS-HTFSA@MIL shows potential application as a safe electrolyte in proton conduction above 100 °C.

  7. Lithium ion conducting PVdF-HFP composite gel electrolytes based on N-methoxyethyl- N-methylpyrrolidinium bis(trifluoromethanesulfonyl)-imide ionic liquid

    NASA Astrophysics Data System (ADS)

    Ferrari, S.; Quartarone, E.; Mustarelli, P.; Magistris, A.; Fagnoni, M.; Protti, S.; Gerbaldi, C.; Spinella, A.

    Blends of PVdF-HFP and ionic liquids (ILs) are interesting for application as electrolytes in plastic Li batteries. They combine the advantages of the gel polymer electrolytes (GPEs) swollen by conventional organic liquid electrolytes with the nonflammability, and high thermal and electrochemical stability of ILs. In this work we prepared and characterized PVdF-HFP composite membranes swollen with a solution of LiTFSI in ether-functionalized pyrrolidinium-imide ionic liquid (PYRA 12O1TFSI). The membranes were filled in with two different types of silica: (i) mesoporous SiO 2 (SBA-15) and (ii) a commercial nano-size one (HiSil™ T700). The ionic conductivity and the electrochemical properties of the gel electrolytes were studied in terms of the nature of the filler. The thermal and the transport properties of the composite membranes are similar. In particular, room temperature ionic conductivities higher than 0.25 mS cm -1 are easily obtained at defined filler contents. However, the mesoporous filler guarantees higher lithium transference numbers, a more stable electrochemical interface and better cycling performances. Contrary to the HiSil™-based membrane, the Li/LiFePO 4 cells with PVdF-HFP/PYRA 12O1TFSI-LiTFSI films containing 10 wt% of SBA-15 show good charge/discharge capacity, columbic efficiency close to unity, and low capacity losses at medium C-rates during 180 cycles.

  8. Crystal Structure and Ionic Conductivity of Three Polymorphic Phases of Rubidium Trefluoromethyl Sulfonate, RbSO3CF3

    SciTech Connect

    Hildebrandt,L.; Dinnebier, R.; Jansen, M.

    2006-01-01

    The crystal structures of three polymorphic phases of rubidium trifluoromethyl sulfonate (RbSO{sub 3}CF{sub 3}, rubidium 'triflate') were solved from X-ray powder diffraction data. At room temperature, rubidium triflate crystallizes in the monoclinic space group Cm with lattice parameters of a = 19.9611(5) Angstroms, b = 23.4913(7) Angstroms, c = 5.1514(2) Angstroms, = 102.758(2); Z = 16. At T = 321 K, a first-order phase transition occurs toward a monoclinic phase in space group P2{sub 1} with lattice parameters at T = 344 K of a = 10.3434(5) Angstroms, b = 5.8283(3) Angstroms, c = 5.1982(3) Angstroms, = 104.278(6); Z = (2). At T = 461 K, another phase transition, this time of second order, occurs toward an orthorhombic phase in space group Cmcm with lattice parameters at T = 510 K of a = 5.3069(2) Angstroms, b = 20.2423(10) Angstroms, c = 5.9479(2) Angstroms; Z = 4. As a common feature within all three crystal structures of rubidium triflate, the triflate anions are arranged in double layers with the lipophilic CF{sub 3} groups facing each other. The rubidium ions are located between the SO{sub 3} groups. The general packing is similar to the packing in cesium triflate. Rubidium triflate can be classified as a solid electrolyte with a specific ionic conductivity of = 9.89 x 10{sup -9} S/cm at T = 384 K and = 3.84 x 10{sup -6} S/cm at T = 481 K.

  9. Rational design of mixed ionic and electronic conducting perovskite oxides for solid oxide fuel cell anode materials: A case study for doped SrTiO3

    SciTech Connect

    Suthirakun, Suwit; Xiao, Guoliang; Ammal, Salai Cheettu; Chen, Fanglin; zur Loye, Hans-Conrad; Heyden, Andreas

    2014-01-01

    The effect of p- and n-type dopants on ionic and electronic conductivity of SrTiO3 based perovskites were investigated both computationally and experimentally. Specifically, we performed density functional theory (DFT) calculations of Na- and La-doped SrTiO3 and Na- and Nb-doped SrTiO3 systems. Constrained ab initio thermodynamic calculations were used to evaluate the phase stability and reducibility of doped SrTiO3 under both oxidizing and reducing synthesis conditions, as well as under anodic solid oxide fuel cell (SOFC) conditions. The density of states (DOS) of these materials was analyzed to study the effects of p- and n-doping on the electronic conductivity. Furthermore, Na- and La-doped SrTiO3 and Na- and Nb-doped SrTiO3 samples were experimentally prepared and the conductivity was measured to confirm our computational predictions. The experimental observations are in very good agreement with the theoretical predictions that doping n-doped SrTiO3 with small amounts of p-type dopants promotes both the ionic and electronic conductivity of the material. This doping strategy is valid independent of p- and n-doping site and permits the synthesis of perovskite based mixed ionic/electronic conductors.

  10. Interactions of 1-butyl-3-methylimidazolium carboxylate ionic liquids with glucose in water: a study of volumetric properties, viscosity, conductivity and NMR.

    PubMed

    Zhuo, Kelei; Chen, Yujuan; Chen, Jing; Bai, Guangyue; Wang, Jianji

    2011-08-28

    Extensive applications of ionic liquids (ILs) may result in their accumulation in the ecological environment and organisms. Although ILs are popularly called "green solvents", their toxicity, in fact, has been exhibited. Therefore the interaction of ILs with biomolecules is a cutting-edge research subject. Herein, the interactions of 1-butyl-3-methylimidazolium carboxylate ionic liquids ([C(4)mim][HCOO], [C(4)mim][CH(3)COO] and [C(4)mim][CH(3)CH(2)COO]) with glucose in water were studied for their volumetric properties, viscosity, conductivity and NMR spectra. Limiting apparent molar volumes (V(Φ, IL)(0)), viscosity B-coefficients, limiting molar conductivities (Λ(0)) and Walden products (Λ(0)η(0)) were evaluated for the ILs in glucose + water solutions. Volumetric interaction parameters were also obtained from the transfer volumes of the ionic liquids. The contributions of the solvent properties (B(1)) and the ionic liquid-solvent interactions (B(2)) to the B-coefficient were extracted, together with molar activation energies (Δμ(IL)(0≠)) of the ionic liquids for viscous flow of the aqueous glucose + IL solution. In addition, the (13)C and (1)H NMR spectra of methyl β-D-glucopyranoside and ILs in β-D-glucopyranoside + IL + D(2)O were studied. The NMR results show that no special and strong interactions were observed between glucopyranoside and the ILs. However, it was confirmed that the H2 on the imidazolium ring has more activity (acidity) than atoms H4 and H5. The macro-properties and their changes were also discussed in terms of the size, structure and solvation of the ILs and glucose.

  11. Ionic conductivity of Bi12(V,Bi)O20 + δ single crystal (δ = 0.27) with a sillenite-type structure

    NASA Astrophysics Data System (ADS)

    Sorokin, N. I.

    2012-11-01

    The ionic conductivity of nonstoichiometric Bi12(V0.89Bi0.03)O20.27 single crystal with a sillenite-type structure has been investigated by impedance spectroscopy; its conductivity at 673 K is 2 × 10-3 S/cm, which is about two orders of magnitude higher than the conductivity of oxide superionic conductor single crystal Zr0.88Y0.12O1.94. As follows from crystallochemical analysis, ion transport in Bi12(V0.89Bi0.03)O20.27 is due to additional O2- ions, which arise due to oxygen nonstoichiometry.

  12. EFFECT OF (Bi2O3)0.75(Y2O3)0.25 ADDITION ON MICROSTRUCTURES AND IONIC CONDUCTIVITIES OF CODOPED ZIRCONIA

    NASA Astrophysics Data System (ADS)

    Chou, Chen Chia; Huang, Chun Feng; Yeh, Tsung Her

    2012-09-01

    Variation of microstructures and ionic conductivities in (Bi2O3)0.75(Y2O3)0.25 (YSB) modified electrolyte of 8 mol% Y2O3 stabilized zirconia (8YSZ) and YSB modified codoped zirconia (ZrO2)0.92(Y2O3)0.075(MgO)0.005 (YSZM) is investigated in this work. The results demonstrated that a small amount of δ-YSB addition is effective in reducing the sintering temperature of 8YSZ from 1500 to 1200°C and promoting the densification rate of ceramics. Compared to 8YSZ electrolyte, it is interesting that a very limited amount of monoclinic ZrO2 was observed due to the MgO stabilizer in YSB modified codoped zirconia electrolyte. Besides, enhancement of ionic conductivity in δ-YSB modified codoped zirconia is evidently increased by 67% in comparison to the specimen of 8YSZ electrolyte.

  13. A Monte-Carlo simulation of ionic conductivity and viscosity of highly concentrated electrolytes based on a pseudo-lattice model

    NASA Astrophysics Data System (ADS)

    Ozaki, Hiroyuki; Kuratani, Kentaro; Sano, Hikaru; Kiyobayashi, Tetsu

    2017-07-01

    Simulating three transport phenomena—ionic conductivity, viscosity, and self-diffusion coefficient—in a common Monte-Carlo framework, we discuss their relationship to the intermolecular interactions of electrolyte solutions at high concentrations (C /mol l-1 ˜ 1 ). The simulation is predicated on a pseudolattice model of the solution. The ions and solvents (collectively termed "molecules") are considered dimensionless points occupying the lattice sites. The molecular transport is realized by a repetition of swapping two adjacent molecules by the stochastic Gibbs sampling process based on simple intermolecular interactions. The framework has been validated by the fact that the simulated ionic conductivity and dynamic viscosity of 1:1- and 2:1-salts qualitatively well represent the experimental data. The magnitude of the Coulombic interaction itself is not reflected in the ionic conductivity, but the extent to which the Coulombic interaction is shielded by the dielectric constant has a significant influence. On the other hand, the dielectric constant barely influences the viscosity, while the magnitude of the Coulombic interaction is directly reflected in the viscosity.

  14. Glass transition dynamics and conductivity scaling in ionic deep eutectic solvents: The case of (acetamide + lithium nitrate/sodium thiocyanate) melts

    NASA Astrophysics Data System (ADS)

    Tripathy, Satya N.; Wojnarowska, Zaneta; Knapik, Justyna; Shirota, Hideaki; Biswas, Ranjit; Paluch, Marian

    2015-05-01

    A detailed investigation on the molecular dynamics of ionic deep eutectic solvents (acetamide + lithium nitrate/sodium thiocyanate) is reported. The study was carried out employing dielectric relaxation spectroscopy covering seven decades in frequency (10-1-106 Hz) and in a wide temperature range from 373 K down to 173 K, accessing the dynamic observables both in liquid and glassy state. The dielectric response of the ionic system has been presented in the dynamic window of modulus formalism to understand the conductivity relaxation and its possible connection to the origin of localized motion. Two secondary relaxation processes appear below glass transition temperature. Our findings provide suitable interpretation on the nature of secondary Johari-Goldstein process describing the ion translation and orientation of dipoles in a combined approach using Ngai's coupling model. A nearly constant loss feature is witnessed at shorter times/lower temperatures. We also discuss the ac conductivity scaling behavior using Summerfield approach and random free energy barrier model which establish the time-temperature superposition principle. These experimental observations have fundamental importance on theoretical elucidation of the conductivity relaxation and glass transition phenomena in molten ionic conductors.

  15. Preparation and electrochemical characterization of ionic-conducting lithium lanthanum titanate oxide/polyacrylonitrile submicron composite fiber-based lithium-ion battery separators

    NASA Astrophysics Data System (ADS)

    Liang, Yinzheng; Ji, Liwen; Guo, Bingkun; Lin, Zhan; Yao, Yingfang; Li, Ying; Alcoutlabi, Mataz; Qiu, Yiping; Zhang, Xiangwu

    Lithium lanthanum titanate oxide (LLTO)/polyacrylonitrile (PAN) submicron composite fiber-based membranes were prepared by electrospinning dispersions of LLTO ceramic particles in PAN solutions. These ionic-conducting LLTO/PAN composite fiber-based membranes can be directly used as lithium-ion battery separators due to their unique porous structure. Ionic conductivities were evaluated after soaking the electrospun LLTO/PAN composite fiber-based membranes in a liquid electrolyte, 1 M lithium hexafluorophosphate (LiPF 6) in ethylene carbonate (EC)/ethyl methyl carbonate (EMC) (1:1 vol). It was found that, among membranes with various LLTO contents, 15 wt.% LLTO/PAN composite fiber-based membranes provided the highest ionic conductivity, 1.95 × 10 -3 S cm -1. Compared with pure PAN fiber membranes, LLTO/PAN composite fiber-based membranes had greater liquid electrolyte uptake, higher electrochemical stability window, and lower interfacial resistance with lithium. In addition, lithium//1 M LiPF 6/EC/EMC//lithium iron phosphate cells containing LLTO/PAN composite fiber-based membranes as the separator exhibited high discharge specific capacity of 162 mAh g -1 and good cycling performance at 0.2 C rate at room temperature.

  16. Strain tuning and strong enhancement of ionic conductivity in SrZrO3-RE2O3 (RE = Sm, Eu, Gd, Dy, and Er) nanocomposite films

    DOE PAGES

    Lee, Shinbuhm; Zhang, Wenrui; Khatkhatay, Fauzia; ...

    2015-06-05

    Fast ion transport channels at interfaces in thin films have attracted great attention due to a range of potential applications for energy materials and devices, for, solid oxide fuel cells, sensors, and memories. Here, it is shown that in vertical nanocomposite heteroepitaxial films of SrZrO3–RE2O3 (RE = Sm, Eu, Gd, Dy, and Er) the ionic conductivity of the composite can be tuned and strongly enhanced using embedded, stiff, and vertical nanopillars of RE2O3. With increasing lattice constant of RE2O3 from Er2O3 to Sm2O3, it is found that the tensile strain in the SrZrO3 increases proportionately, and the ionic conductivity ofmore » the composite increases accordingly, by an order of magnitude. Lastly, the results here conclusively show, for the first time, that strain in films can be effectively used to tune the ionic conductivity of the materials.« less

  17. Glass transition dynamics and conductivity scaling in ionic deep eutectic solvents: The case of (acetamide + lithium nitrate/sodium thiocyanate) melts

    SciTech Connect

    Tripathy, Satya N. Wojnarowska, Zaneta; Knapik, Justyna; Paluch, Marian; Shirota, Hideaki; Biswas, Ranjit

    2015-05-14

    A detailed investigation on the molecular dynamics of ionic deep eutectic solvents (acetamide + lithium nitrate/sodium thiocyanate) is reported. The study was carried out employing dielectric relaxation spectroscopy covering seven decades in frequency (10{sup −1}-10{sup 6} Hz) and in a wide temperature range from 373 K down to 173 K, accessing the dynamic observables both in liquid and glassy state. The dielectric response of the ionic system has been presented in the dynamic window of modulus formalism to understand the conductivity relaxation and its possible connection to the origin of localized motion. Two secondary relaxation processes appear below glass transition temperature. Our findings provide suitable interpretation on the nature of secondary Johari-Goldstein process describing the ion translation and orientation of dipoles in a combined approach using Ngai’s coupling model. A nearly constant loss feature is witnessed at shorter times/lower temperatures. We also discuss the ac conductivity scaling behavior using Summerfield approach and random free energy barrier model which establish the time-temperature superposition principle. These experimental observations have fundamental importance on theoretical elucidation of the conductivity relaxation and glass transition phenomena in molten ionic conductors.

  18. Coherency strain and its effect on ionic conductivity and diffusion in solid electrolytes--an improved model for nanocrystalline thin films and a review of experimental data.

    PubMed

    Korte, C; Keppner, J; Peters, A; Schichtel, N; Aydin, H; Janek, J

    2014-11-28

    A phenomenological and analytical model for the influence of strain effects on atomic transport in columnar thin films is presented. A model system consisting of two types of crystalline thin films with coherent interfaces is assumed. Biaxial mechanical strain ε0 is caused by lattice misfit of the two phases. The conjoined films consist of columnar crystallites with a small diameter l. Strain relaxation by local elastic deformation, parallel to the hetero-interface, is possible along the columnar grain boundaries. The spatial extent δ0 of the strained hetero-interface regions can be calculated, assuming an exponential decay of the deformation-forces. The effect of the strain field on the local ionic transport in a thin film is then calculated by using the thermodynamic relation between (isostatic) pressure and free activation enthalpy ΔG(#). An expression describing the total ionic transport relative to bulk transport of a thin film or a multilayer as a function of the layer thickness is obtained as an integral average over strained and unstrained regions. The expression depends only on known material constants such as Young modulus Y, Poisson ratio ν and activation volume ΔV(#), which can be combined as dimensionless parameters. The model is successfully used to describe own experimental data from conductivity and diffusion studies. In the second part of the paper a comprehensive literature overview of experimental studies on (fast) ion transport in thin films and multilayers along solid-solid hetero-interfaces is presented. By comparing and reviewing the data the observed interface effects can be classified into three groups: (i) transport along interfaces between extrinsic ionic conductors (and insulator), (ii) transport along an open surface of an extrinsic ionic conductor and (iii) transport along interfaces between intrinsic ionic conductors. The observed effects in these groups differ by about five orders of magnitude in a very consistent way. The

  19. The role of electronic and ionic conductivities in the rate performance of tunnel structured manganese oxides in Li-ion batteries

    DOE PAGES

    Byles, B. W.; Palapati, N. K. R.; Subramanian, A.; ...

    2016-04-29

    Single nanowires of two manganese oxide polymorphs (α-MnO2 and todorokite manganese oxide), which display a controlled size variation in terms of their square structural tunnels, were isolated onto nanofabricated platforms using dielectrophoresis. This platform allowed for the measurement of the electronic conductivity of these manganese oxides, which was found to be higher in α-MnO2 as compared to that of the todorokite phase by a factor of similar to 46. Despite this observation of substantially higher electronic conductivity in α-MnO2, the todorokite manganese oxide exhibited better electrochemical rate performance as a Li-ion battery cathode. The relationship between this electrochemical performance, themore » electronic conductivities of the manganese oxides, and their reported ionic conductivities is discussed for the first time, clearly revealing that the rate performance of these materials is limited by their Li+ diffusivity, and not by their electronic conductivity. This result reveals important new insights relevant for improving the power density of manganese oxides, which have shown promise as a low-cost, abundant, and safe alternative for next-generation cathode materials. Moreover, the presented experimental approach is suitable for assessing a broader family of one-dimensional electrode active materials (in terms of their electronic and ionic conductivities) for both Li-ion batteries and for electrochemical systems utilizing charge-carrying ions beyond Li+.« less

  20. The role of electronic and ionic conductivities in the rate performance of tunnel structured manganese oxides in Li-ion batteries

    SciTech Connect

    Byles, B. W.; Palapati, N. K. R.; Subramanian, A.; Pomerantseva, E.

    2016-04-29

    Single nanowires of two manganese oxide polymorphs (α-MnO2 and todorokite manganese oxide), which display a controlled size variation in terms of their square structural tunnels, were isolated onto nanofabricated platforms using dielectrophoresis. This platform allowed for the measurement of the electronic conductivity of these manganese oxides, which was found to be higher in α-MnO2 as compared to that of the todorokite phase by a factor of similar to 46. Despite this observation of substantially higher electronic conductivity in α-MnO2, the todorokite manganese oxide exhibited better electrochemical rate performance as a Li-ion battery cathode. The relationship between this electrochemical performance, the electronic conductivities of the manganese oxides, and their reported ionic conductivities is discussed for the first time, clearly revealing that the rate performance of these materials is limited by their Li+ diffusivity, and not by their electronic conductivity. This result reveals important new insights relevant for improving the power density of manganese oxides, which have shown promise as a low-cost, abundant, and safe alternative for next-generation cathode materials. Moreover, the presented experimental approach is suitable for assessing a broader family of one-dimensional electrode active materials (in terms of their electronic and ionic conductivities) for both Li-ion batteries and for electrochemical systems utilizing charge-carrying ions beyond Li+.

  1. Ion transport with charge-protected and non-charge-protected cations using the compensated Arrhenius formalism. Part 2. Relationship between ionic conductivity and diffusion.

    PubMed

    Petrowsky, Matt; Fleshman, Allison; Bopege, Dharshani N; Frech, Roger

    2012-08-09

    Temperature-dependent ionic conductivities and cation/anion self-diffusion coefficients are measured for four electrolyte families: TbaTf-linear primary alcohols, LiTf-linear primary alcohols, TbaTf-n-alkyl acetates, and LiTf-n-alkyl acetates. The Nernst-Einstein equation does not adequately describe the data. Instead, the compensated Arrhenius formalism is applied to both conductivity and diffusion data. General trends based on temperature and alkyl chain length are observed when conductivity is plotted against cation or anion diffusion coefficient, but there is no clear pattern to the data. However, plotting conductivity exponential prefactors against those for diffusion results in four distinct curves, one each for the alcohol and acetate families described above. Furthermore, the TbaTf-alcohol and TbaTf-acetate data are "in line" with each other. The conductivity prefactors for the LiTf-alcohol data are smaller than those for the TbaTf data. The LiTf-acetate data have the lowest conductivity prefactors. This trend in prefactors mirrors the observed trend in degree of ionic association for these electrolytes.

  2. (Bi,Sr) (Fe1-x,Mx)O3-δ (M = Co, Ni and Mn) Cathode Materials with Mixed Electro-Ionic Conductivity.

    PubMed

    Wei, Wen-Cheng J; Huang, Der-Rong; Wang, Dan

    2016-11-14

    (Bi,Sr)FeO3-δ (BSF) cathode materials doped with either Co, Ni or Mn are synthesized by an ethylene diamine tetra-acetic acid (EDTA)-citrate complexing method, and the effects of the doping level on the mixed electronic-ionic conductivity at various temperatures are studied up to 800 °C. The phase purity and solid solution limit are investigated by X-ray diffraction (XRD). The ionic conductivity is measured by the four-probe direct current (DC) method, the valence state of Fe and Mn by X-ray photoelectron spectroscopy (XPS), and the oxygen non-stoichiometry by differential thermo-gravimetric analysis (TGA). The doped ferrites show interesting electronic conductivity dependent on the testing temperature, implying two conductive mechanisms, either controlled by double exchange at lower temperatures or small polaron (electron-oxygen vacancy) conduction at temperatures greater than 400 °C. The results of Co-doped BSF (S50C20) show the best mixed conductivity among the ferrites, and this is used to assemble cells. The cell with a S50C20 cathode in the region of 600-800 °C is improved by 15% in maximum power density greater than the cell with La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) due to the balanced contribution from oxygen ions, vacancies and electrons.

  3. (Bi,Sr) (Fe1−x,Mx)O3−δ (M = Co, Ni and Mn) Cathode Materials with Mixed Electro-Ionic Conductivity

    PubMed Central

    Wei, Wen-Cheng J.; Huang, Der-Rong; Wang, Dan

    2016-01-01

    (Bi,Sr)FeO3−δ (BSF) cathode materials doped with either Co, Ni or Mn are synthesized by an ethylene diamine tetra-acetic acid (EDTA)-citrate complexing method, and the effects of the doping level on the mixed electronic-ionic conductivity at various temperatures are studied up to 800 °C. The phase purity and solid solution limit are investigated by X-ray diffraction (XRD). The ionic conductivity is measured by the four-probe direct current (DC) method, the valence state of Fe and Mn by X-ray photoelectron spectroscopy (XPS), and the oxygen non-stoichiometry by differential thermo-gravimetric analysis (TGA). The doped ferrites show interesting electronic conductivity dependent on the testing temperature, implying two conductive mechanisms, either controlled by double exchange at lower temperatures or small polaron (electron-oxygen vacancy) conduction at temperatures greater than 400 °C. The results of Co-doped BSF (S50C20) show the best mixed conductivity among the ferrites, and this is used to assemble cells. The cell with a S50C20 cathode in the region of 600–800 °C is improved by 15% in maximum power density greater than the cell with La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) due to the balanced contribution from oxygen ions, vacancies and electrons. PMID:28774043

  4. Rigid-flexible coupling high ionic conductivity polymer electrolyte for an enhanced performance of LiMn2O4/graphite battery at elevated temperature.

    PubMed

    Hu, Pu; Duan, Yulong; Hu, Deping; Qin, Bingsheng; Zhang, Jianjun; Wang, Qingfu; Liu, Zhihong; Cui, Guanglei; Chen, Liquan

    2015-03-04

    LiMn2O4-based batteries exhibit severe capacity fading during cycling or storage in LiPF6-based liquid electrolytes, especially at elevated temperatures. Herein, a novel rigid-flexible gel polymer electrolyte is introduced to enhance the cyclability of LiMn2O4/graphite battery at elevated temperature. The polymer electrolyte consists of a robust natural cellulose skeletal incorporated with soft segment poly(ethyl α-cyanoacrylate). The introduction of the cellulose effectively overcomes the drawback of poor mechanical integrity of the gel polymer electrolyte. Density functional theory (DFT) calculation demonstrates that the poly(ethyl α-cyanoacrylate) matrices effectively dissociate the lithium salt to facilitate ionic transport and thus has a higher ionic conductivity at room temperature. Ionic conductivity of the gel polymer electrolyte is 3.3 × 10(-3) S cm(-1) at room temperature. The gel polymer electrolyte remarkably improves the cycling performance of LiMn2O4-based batteries, especially at elevated temperatures. The capacity retention after the 100th cycle is 82% at 55 °C, which is much higher than that of liquid electrolyte (1 M LiPF6 in carbonate solvents). The polymer electrolyte can significantly suppress the dissolution of Mn(2+) from surface of LiMn2O4 because of strong interaction energy of Mn(2+) with PECA, which was investigated by DFT calculation.

  5. Ionic conduction in poly(vinyl chloride)/poly(ethyl methacrylate)-based polymer blend electrolytes complexed with different lithium salts

    NASA Astrophysics Data System (ADS)

    Rajendran, S.; Prabhu, M. Ramesh; Rani, M. Usha

    Poly(vinyl chloride)/poly(ethyl methacrylate)-based polymer blend electrolytes comprising propylene carbonate as a plasticizer and a lithium salt LiX (X = BF 4 -, ClO 4 -, CF 3SO 3 -) are prepared by a solvent casting technique. The electrolytes are subjected to characterization by ionic conductivity, X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetic/differential thermal analysis. The electrolytes that contain LiBF 4 exhibit maximum conductivity and are thermally stable up to 254 °C.

  6. Graphene with Electrochemical Ionic-Liquid Assistance Synthesis to Explore the Metal Adsorption Ability and the High Electrical Conductivity in Graphene/Epoxy Composite

    NASA Astrophysics Data System (ADS)

    Chang, Chia-Feng; Chiang, Yi-Fang; Chen, Jiann-Ruey

    2012-10-01

    A simple and one-step method of producing graphenes was investigated in this work. We have modified the Hummer electrolysis method and combined it with ionic liquid for productions. The results showed that the graphenes could absorb Cu2+ at 202.2 mg/g. Additionally, the mechanism of how graphenes absorb metal and the effects of acidity are described. We have proved that the synthesized graphenes successfully based on transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray powder diffraction (XRD), Raman spectroscopy (Raman), and Fourier transform infrared (FTIR) analysis. This investigation also showed that the graphenes' highest adsorption of Cu(II) at pH 8 mainly resulted from the ionic-like charge and no-defect surface. We found that the highest conductivity of 10-2 S/m was achieved as the binary graphene/epoxy composite (0.3%).

  7. NMR, surface tension and conductance study to investigate host-guest inclusion complexes of three sequential ionic liquids with β-cyclodextrin in aqueous media

    NASA Astrophysics Data System (ADS)

    Barman, Siti; Ekka, Deepak; Saha, Subhadeep; Roy, Mahendra Nath

    2016-08-01

    Host-guest inclusion complexes of three sequential cationic room temperature surface active ionic liquids, benzyltrialkylammonium chloride [(C6H5CH2)N(CnH2n+1)3Cl; where n = 1, 2, 4] with β-cyclodextrin in aqueous media have been studied using surface tension, conductance and NMR spectroscopy. All the studies have suggested that the hydrophobic benzyl group of ionic liquids is encapsulated inside into the cavity of β-cyclodextrin and played a crucial role in supporting the formation of inclusion complexes. The variation of the thermodynamic parameters with guest size, shape is used to draw inferences about contributions to the overall binding by means of the driving forces, viz., hydrophobic effect, steric hindrance, van der Waal force, and electrostatic force.

  8. Viscoelastic Properties, Ionic Conductivity, and Materials Design Considerations for Poly(styrene-b-ethylene oxide-b-styrene)-Based Ion Gel Electrolytes

    SciTech Connect

    Zhang, Sipei; Lee, Keun Hyung; Sun, Jingru; Frisbie, C. Daniel; Lodge, Timothy P.

    2013-03-07

    The viscoelastic properties and ionic conductivity of ion gels based on the self-assembly of a poly(styrene-b-ethylene oxide-b-styrene) (SOS) triblock copolymer (M{sub n,S} = 3 kDa, M{sub n,O} = 35 kDa) in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMI][TFSA]) were investigated over the composition range of 10-50 wt % SOS and the temperature range of 25-160 C. The poly(styrene) (PS) end-blocks associate into micelles, whereas the poly(ethylene oxide) (PEO) midblocks are well-solvated by this ionic liquid. The ion gel with 10 wt % SOS melts at 54 C, with the longest relaxation time exhibiting a similar temperature dependence to that of the viscosity of bulk PS. However, the actual values of the gel relaxation time are more than 4 orders of magnitude larger than the relaxation time of bulk PS. This is attributed to the thermodynamic penalty of pulling PS end-blocks through the PEO/[EMI][TFSA] matrix. Ion gels with 20-50 wt % SOS do not melt and show two plateaus in the storage modulus over the temperature and frequency ranges measured. The one at higher frequencies is that of an entangled network of PEO strands with PS cross-links; the modulus displays a quadratic dependence on polymer weight fraction and agrees with the prediction of linear viscoelastic theory assuming half of the PEO chains are elastically effective. The frequency that separates the two plateaus, {omega}{sub c}, reflects the time scale of PS end-block pull-out. The other plateau at lower frequencies is that of a congested micelle solution with PS cores and PEO coronas, which has a power law dependence on domain spacing similar to diblock melts. The ionic conductivity of the ion gels is compared to PEO homopolymer solutions at similar polymer concentrations; the conductivity is reduced by a factor of 2.1 or less, decreases with increasing PS volume fraction, and follows predictions based on a simple obstruction model. Our collective results allow the formulation

  9. Obtaining Mixed Ionic/Electronic Conductivity in Perovskite Oxides in a Reducing Environment: A Computational Prediction for Doped SrTiO3

    SciTech Connect

    Suthirakun, Suwit; Ammal, Salai Cheettu; Xiao, Guoliang; Chen, Fanglin; Huang, Kevin; zur Loye, Hans-Conrad; Heyden, Andreas

    2012-11-30

    The electronic conductivity and thermodynamic stability of mixed p- and n-doped SrTiO3 perovskites have been investigated under anodic solid oxide fuel cell conditions using density functional theory (DFT). In particular, constrained ab initio thermodynamic calculations have been performed to evaluate the phase stability of various Ga- and La-doped SrTiO3 at synthesized and anodic SOFC conditions. The density of states (DOS) of these materials was analyzed to determine the number of charge carriers and the degree of electronic conductivity. We find that a mixed ionic/electronic conductor can be obtained when doping SrTiO3 perovskite oxide with both p-type and n-type dopants. Calculations show that 10% Ga- and 20% La-doped SrTiO3 exhibit mixed ionic/electronic conductivity at high temperature and low oxygen partial pressure whereas doping with higher concentrations of Ga, e.g., 20%, diminishes the electronic conductivity of the material. Furthermore, changing the n-dopant from La (A-site) to Nb (B-site) does not significantly affect the reducibility and number of charge carriers in p- and n-doped SrTiO3. However, a higher degree of oxygen vacancy clustering is observed for the La-doped material which reduces the oxygen ion diffusion rate and traps electrons. Nevertheless, our findings suggest that independent of doping site, mixed ionic/ electronic conductivity can be obtained in SrTiO3 perovskite oxides under reducing conditions and high temperatures when using a mixed p- and n-type doping strategy that uses a p-dopant concentration smaller than the n-dopant concentration.

  10. Thick-films of garnet-type lithium ion conductor prepared by the Aerosol Deposition Method: The role of morphology and annealing treatment on the ionic conductivity

    NASA Astrophysics Data System (ADS)

    Hanft, Dominik; Exner, Jörg; Moos, Ralf

    2017-09-01

    We fabricated thick films of cubic garnet solid electrolyte AlyLi7-3y-zLa3Zr2-zTazO12 (ALLZTO) by the Aerosol Deposition Method (ADM). Due to the room temperature impact consolidation (RTIC) mechanism, the films become dense. A thermal post-treatment of the film revealed the morphological and process-related impact on the ionic conductivity. As-deposited films show a reduced conductivity around 2·10-7 S/cm. Using electrochemical impedance spectroscopy and high-temperature X-ray diffraction, we found the lattice distortion and nano-crystallinity of the films to be the decisive effect for the conductivity reduction. In our case, post-deposition annealing at 400 °C lead to an increase of the ionic conductivity to 2·10-5 S/cm. With a beginning of sintering at 600 °C, the conductivity successively increased further, reaching values of 7·10-5 S/cm.

  11. Acidic Ionic Liquids.

    PubMed

    Amarasekara, Ananda S

    2016-05-25

    Ionic liquid with acidic properties is an important branch in the wide ionic liquid field and the aim of this article is to cover all aspects of these acidic ionic liquids, especially focusing on the developments in the last four years. The structural diversity and synthesis of acidic ionic liquids are discussed in the introduction sections of this review. In addition, an unambiguous classification system for various types of acidic ionic liquids is presented in the introduction. The physical properties including acidity, thermo-physical properties, ionic conductivity, spectroscopy, and computational studies on acidic ionic liquids are covered in the next sections. The final section provides a comprehensive review on applications of acidic ionic liquids in a wide array of fields including catalysis, CO2 fixation, ionogel, electrolyte, fuel-cell, membrane, biomass processing, biodiesel synthesis, desulfurization of gasoline/diesel, metal processing, and metal electrodeposition.

  12. Ionic liquid containing microemulsions: probe by conductance, dynamic light scattering, diffusion-ordered spectroscopy NMR measurements, and study of solvent relaxation dynamics.

    PubMed

    Pramanik, Rajib; Sarkar, Souravi; Ghatak, Chiranjib; Rao, Vishal Govind; Sarkar, Nilmoni

    2011-03-17

    Room-temperature ionic liquid (RTIL), N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide ([P(13)][Tf(2)N]), was substituted for polar water and formed nonaqueous microemulsions with benzene by the aid of nonionic surfactant TX-100. The phase behavior of the ternary system was investigated, and microregions of [P(13)][Tf(2)N]-in-benzene (IL/O), bicontinuous, and benzene-in-[P(13)][Tf(2)N] (O/IL) were identified by traditional electrical conductivity measurements. Dynamic light scattering (DLS) revealed the formation of these IL microemulsions because with gradual increase of RTIL contents the droplet sizes of the microemulsions are also gradually increasing. Pulsed-field gradient spin-echo NMR have been studied to measure the diffusion coefficients of neat [P(13)][Tf(2)N] and [P(13)][Tf(2)N] in microemulsions which indicate ionic liquid containing microemulsions is formed. Moreover, the dynamics of solvent relaxation have been investigated in [P(13)][Tf(2)N]/TX100/benzene microemulsions using steady-state and time-resolved fluorescence spectroscopy using coumarin 153 (C-153) and coumarin 480 (C-480) fluorescence probe with variation of RTIL contents in microemulsions. For both of the probes with increasing amount of ionic liquids in microemulsions the relative contribution of the fast components increases and the slow components contribution decreases; therefore the average solvation time decreases. © 2011 American Chemical Society

  13. Study of reversible electrode reaction and mixed ionic and electronic conduction of lithium phosphate electrolyte for an electrochemical CO2 gas sensor

    NASA Astrophysics Data System (ADS)

    Lee, Chong-Hoon

    An electrochemical CO2 gas sensor with lithium ion conductor was developed and characterized in order to examine the potential for real-life applications and understand its sensing mechanism. Li2CO3 and Li2TiO3 + TiO2 mixture were used as a sensing and a reference auxiliary phase, respectively. This electrochemical cell with a solid state Li3PO4 electrolyte has shown good selectivity, sensitivity and linear response in laboratory and automobile exhaust tests. However, the sensor response to CO2 gas showed a systematic deviation from the Nernst equation. Measured EMF did not agree with that calculated from the Nernst equation, even though it followed logarithmic behavior. Moreover, high sensitivity was observed for high CO2 concentrations (5˜50%), compared to that for concentrations (500˜5000 ppm). Two possible reasons for this deviation are: (1) reversibility of electrode reaction and (2) mixed ionic and electronic conduction of the electrolyte. Unless electrode reaction is fast enough, electrode polarization can easily induce overpotential. Pure ionic conduction of electrolyte is also necessary to avoid EMF loss during open circuit potential measurement. EIS (Electrochemical Impedance Spectroscopy) was used to study electrode kinetics. We found that Li2TiO3 + TiO2 mixture reference electrode reaction is sluggish showing large electrode impedance. This impedance, however, was not affected by gas concentration change. On the other hand, that at the Li2CO3 sensing electrode is relatively small and it increased with decreased CO2 and O 2 concentration. It was also observed that these electrode impedances induced the overpotential when the current flowed through the sensor. This electrode overpotential problem was minimized by mixing gold powder or porous sputtered gold electrode increasing effective reaction sites of the electrode. New electrode design improved the sensor EMF closer to the Nernstian values, however, the discrepancy still remained. Moreover, at

  14. Effect of water on the transport properties of protic and aprotic imidazolium ionic liquids - an analysis of self-diffusivity, conductivity, and proton exchange mechanism.

    PubMed

    Yaghini, N; Nordstierna, L; Martinelli, A

    2014-05-28

    In this paper we report on the transport properties of protic and aprotic ionic liquids of the imidazolium cation (C2C1Im(+) or C2HIm(+)) and the TFSI(-) or TfO(-) anion as a function of added water. We observe that the self-diffusion coefficient of the ionic species increases upon addition of water, and that the cation diffuses faster than the anion in the entire water concentration range investigated. We also observe that the overall increase of anionic and cationic diffusion coefficients is significant for C2HImTfO while it is rather weak for C2C1ImTFSI, the former being more hydrophilic. Moreover, the difference between cationic and anionic self-diffusivity specifically depends on the structure of the ionic liquid's ions. The degree of ion-ion association has been investigated by comparing the molar conductivity obtained by impedance measurements with the molar conductivity calculated from NMR data using the Nernst-Einstein equation. Our data indicate that the ions are partly dissociated (Λimp/ΛNMR in the range 0.45-0.75) but also that the degree of association decreases in the order C2HImTfO > C2HImTFSI ≈ C2C1ImTfO > C2C1ImTFSI. From these results, it seems that water finds different sites of interaction in the protic and aprotic ionic liquids, with a strong preference for hydrogen bonding to the -NH group (when available) and a stronger affinity to the TfO anion as compared to the TFSI. For the protic ionic liquids, the analysis of (1)H NMR chemical shifts (upon addition of H2O and D2O, respectively) indicates a water-cation interaction of hydrogen bonding nature. In addition, we could probe proton exchange between the -NH group and deuterated water for the protic cation, which occurs at a significantly faster rate if associated with the TfO anion as compared to the TFSI.

  15. Enhanced ionic conductivity in Gd-doped ceria and (Li/Na)2SO4 composite electrolytes for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Yao, Chuangang; Meng, Junling; Liu, Xiaojuan; Zhang, Xiong; Liu, Xiliang; Meng, Fanzhi; Wu, Xiaojie; Meng, Jian

    2015-11-01

    A series of novel composite electrolytes based on 20 mol% Gd doped CeO2 with varying amounts of (Li/Na)2SO4 have been synthesized. X-ray diffraction, thermogravimetry and differential scanning calorimetry, scanning electron microscope and transmission electron microscope were applied to characterize the phase components and microstructures of the composite electrolytes. Their ionic conductivities were determined by AC impedance spectroscopy. It has been found that the optimum sintering temperature and sulphate content for the composite electrolyte is 870 °C and 20 wt% (Li/Na)2SO4, respectively. Above 550 °C, a sharp increase in conductivity occurred, which can be interpreted as superionic phase transitions in the interface phases between GDC and sulphates. Both the high ionic conductivities above the transition temperature, 0.191, 0.298 and 0.372 S cm-1 at 550, 650 and 750 °C respectively, and low activation energy (0.303 eV) highlight composite GDC-20 wt% (Li/Na)2SO4 a promising electrolyte candidate for application in intermediate temperature solid oxide fuel cells.

  16. Lithium-modulated conduction band edge shifts and charge-transfer dynamics in dye-sensitized solar cells based on a dicyanamide ionic liquid.

    PubMed

    Bai, Yu; Zhang, Jing; Wang, Yinghui; Zhang, Min; Wang, Peng

    2011-04-19

    Lithium ions are known for their potent function in modulating the energy alignment at the oxide semiconductor/dye/electrolyte interface in dye-sensitized solar cells (DSCs), offering the opportunity to control the associated multichannel charge-transfer dynamics. Herein, by optimizing the lithium iodide content in 1-ethyl-3-methylimidazolium dicyanamide-based ionic liquid electrolytes, we present a solvent-free DSC displaying an impressive 8.4% efficiency at 100 mW cm(-2) AM1.5G conditions. We further scrutinize the origins of evident impacts of lithium ions upon current density-voltage characteristics as well as photocurrent action spectra of DSCs based thereon. It is found that, along with a gradual increase of the lithium content in ionic liquid electrolytes, a consecutive diminishment of the open-circuit photovoltage arises, primarily owing to a noticeable downward movement of the titania conduction band edge. The conduction band edge displacement away from vacuum also assists the formation of a more favorable energy offset at the titania/dye interface, and thereby leads to a faster electron injection rate and a higher exciton dissociation yield as implied by transient emission measurements. We also notice that the adverse influence of the titania conduction band edge downward shift arising from lithium addition upon photovoltage is partly compensated by a concomitant suppression of the triiodide involving interfacial charge recombination. © 2011 American Chemical Society

  17. Electrical conductivity of seven binary systems containing 1-ethyl-3-methyl imidazolium alkyl sulfate ionic liquids with water or ethanol at four temperatures.

    PubMed

    Rilo, E; Vila, J; García-Garabal, S; Varela, L M; Cabeza, O

    2013-02-07

    We present experimental measurements of specific electrical (or ionic) conductivity of seven binary systems of 1-ethyl-3-methyl imidazolium alkyl sulfate (EMIM-C(n)S) with water or ethanol. Electrical conductivity was measured at 298.15 K in all ranges of concentrations and selected mixtures also at 288.15, 308.15, and 318.15 K. The alkyl chains of the anions used are ethyl (EMIM-ES), butyl (EMIM-BS), hexyl (EMIM-HS), and, only for mixtures with ethanol, octyl (EMIM-OS). Let us note that the four ionic liquids (ILs) measured are miscible in water and ethanol at those temperatures and atmospheric pressure in all ranges of concentrations, but EMIM-OS jellifies for a given range of concentration with water. We compare the measured data in terms of the alkyl chain length and solvent nature. Data are compared with previously scarce results for these same systems and also for other aqueous and ethanol mixtures with ILs. In addition, we verify that our data fit the universal theoretical expression with no fitting parameters given by the pseudolattice-based Bahe-Varela model, except for IL concentrated mixtures. To fit well all ranges of concentrations, we add to the original equation two phenomenological terms with one fitting parameter each. Finally, we calculate the molar conductivity and fit it successfully with an expression derived from Onsager theory.

  18. Grain boundary stability and influence on ionic conductivity in a disordered perovskite -- a first-principles investigation of lithium lanthanum titanate

    SciTech Connect

    Alexander, Kathleen C.; Ganesh, P.; Chi, Miaofang; Kent, Paul; Sumpter, Bobby G.

    2016-12-01

    The origin of ionic conductivity in bulk lithium lanthanum titanate, a promising solid electrolyte for Li-ion batteries, has long been under debate, with experiments showing lower conductivity than predictions. Recent microscopy images show Type I and Type II grain boundaries. Using first-principles based calculations we find that experimentally observed Type I boundaries are more stable compared to the Type II grain boundaries, consistent with their observed relative abundance. Grain boundary stability appears to strongly anti-correlate with the field strength as well as the spatial extent of the space charge region. Ion migration is faster along Type II grain boundaries than across, consistent with recent experiments of increased conductivity when Type II densities were increased.

  19. Grain boundary stability and influence on ionic conductivity in a disordered perovskite -- a first-principles investigation of lithium lanthanum titanate

    DOE PAGES

    Alexander, Kathleen C.; Ganesh, P.; Chi, Miaofang; ...

    2016-12-01

    The origin of ionic conductivity in bulk lithium lanthanum titanate, a promising solid electrolyte for Li-ion batteries, has long been under debate, with experiments showing lower conductivity than predictions. Recent microscopy images show Type I and Type II grain boundaries. Using first-principles based calculations we find that experimentally observed Type I boundaries are more stable compared to the Type II grain boundaries, consistent with their observed relative abundance. Grain boundary stability appears to strongly anti-correlate with the field strength as well as the spatial extent of the space charge region. Ion migration is faster along Type II grain boundaries thanmore » across, consistent with recent experiments of increased conductivity when Type II densities were increased.« less

  20. Conductivity and spectroscopic investigation of bis(trifluoromethanesulfonyl)imide solution in ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

    PubMed

    Yu, Lei; Pizio, Benjamin S; Vaden, Timothy D

    2012-06-07

    Protic ionic liquids (PILs) are promising alternatives to water for swelling Nafion as a fuel cell proton exchange membrane (PEM). PILs can significantly improve the high-temperature performance of a PEM. The proton dissociation and solvation mechanisms in a PIL, which are keys to understanding the proton transportation and conductivity, have not been fully explored. In this paper, we used FTIR, Raman, and electronic spectroscopy with computational simulation techniques to explore the spectroscopic properties of bis(trifluoromethanesulfonyl)imide (HTFSI) solutions in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMITFSI) ionic liquid at concentrations from ∼0.1 to as high as ∼1.0 M. Solution conductivities were measured at room temperature and elevated temperatures up to ∼65 °C. The solution structure and properties depend on the concentration of HTFSI. At lower concentration, around 0.1 M, the HTFSI solution has higher conductivity than pure BMITFSI. However, the conductivity decreases when the concentration increases from 0.1 to 1.0 M. Temperature-dependent conductivities followed the Vogel-Fulcher-Tamman equation at all concentrations. Conductivity and spectroscopy results elucidate the complicated ionization and solvation mechanism of HTFSI in BMITFSI solutions. Raman spectroscopy and density functional theory (DFT) calculations are consistent with the complete ionization of HTFSI to generate solvated H(+) at low concentrations. FTIR, Raman, and electronic spectroscopic results as well as DFT computational simulation indicated that when the concentration is as high as 1.0 M, a significant amount of TFSI(-) is protonated, most likely at the imide nitrogen.

  1. Effective Energy Transfer via Plasmon-Activated High-Energy Water Promotes Its Fundamental Activities of Solubility, Ionic Conductivity, and Extraction at Room Temperature

    PubMed Central

    Yang, Chih-Ping; Chen, Hsiao-Chien; Wang, Ching-Chiung; Tsai, Po-Wei; Ho, Chia-Wen; Liu, Yu-Chuan

    2015-01-01

    Water is a ubiquitous solvent in biological, physical, and chemical processes. Unique properties of water result from water’s tetrahedral hydrogen-bonded (HB) network (THBN). The original THBN is destroyed when water is confined in a nanosized environment or localized at interfaces, resulting in corresponding changes in HB-dependent properties. In this work, we present an innovative idea to validate the reserve energy of high-energy water and applications of high-energy water to promote water’s fundamental activities of solubility, ionic conductivity, and extraction at room temperature. High-energy water with reduced HBs was created by utilizing hot electrons with energies from the decay of surface plasmon excited at gold (Au) nanoparticles (NPs). Compared to conventional deionized (DI) water, solubilities of alkali metal-chloride salts in high-energy water were significantly increased, especially for salts that release heat when dissolved. The ionic conductivity of NaCl in high-energy water was also markedly higher, especially when the electrolyte’s concentration was extremely low. In addition, antioxidative components, such as polyphenols and 2,3,5,4’-tetrahydroxystilbene-2-O-beta-d-glucoside (THSG) from teas, and Polygonum multiflorum (PM), could more effectively be extracted using high-energy water. These results demonstrate that high-energy water has emerged as a promising innovative solvent for promoting water’s fundamental activities via effective energy transfer. PMID:26658304

  2. Enhanced ionic conductivity with Li{sub 7}O{sub 2}Br{sub 3} phase in Li{sub 3}OBr anti-perovskite solid electrolyte

    SciTech Connect

    Zhu, Jinlong E-mail: yusheng.zhao@unlv.edu Li, Shuai; Zhang, Yi; Howard, John W.; Wang, Yonggang; Kumar, Ravhi S.; Wang, Liping; Lü, Xujie; Li, Yutao; Zhao, Yusheng E-mail: yusheng.zhao@unlv.edu

    2016-09-05

    Cubic anti-perovskites with general formula Li{sub 3}OX (X = Cl, Br, I) were recently reported as superionic conductors with the potential for use as solid electrolytes in all-solid-state lithium ion batteries. These electrolytes are nonflammable, low-cost, and suitable for thermoplastic processing. However, the primary obstacle of its practical implementation is the relatively low ionic conductivity at room temperature. In this work, we synthesized a composite material consisting of two anti-perovskite phases, namely, cubic Li{sub 3}OBr and layered Li{sub 7}O{sub 2}Br{sub 3,} by solid state reaction routes. The results indicate that with the phase fraction of Li{sub 7}O{sub 2}Br{sub 3} increasing to 44 wt. %, the ionic conductivity increased by more than one order of magnitude compared with pure phase Li{sub 3}OBr. Formation energy calculations revealed the meta-stable nature of Li{sub 7}O{sub 2}Br{sub 3}, which supports the great difficulty in producing phase-pure Li{sub 7}O{sub 2}Br{sub 3} at ambient pressure. Methods of obtaining phase-pure Li{sub 7}O{sub 2}Br{sub 3} will continue to be explored, including both high pressure and metathesis techniques.

  3. Scroll-wave dynamics in the presence of ionic and conduction inhomogeneities in an anatomically realistic mathematical model for the pig heart

    NASA Astrophysics Data System (ADS)

    Majumder, R.; Pandit, R.; Panfilov, A. V.

    2016-12-01

    Nonlinear waves of the reaction-diffusion (RD) type occur in many biophysical systems, including the heart, where they initiate cardiac contraction. Such waves can form vortices called scroll waves, which result in the onset of life-threatening cardiac arrhythmias. The dynamics of scroll waves is affected by the presence of inhomogeneities, which, in a very general way, can be of (i) ionic type; i.e., they affect the reaction part, or (ii) conduction type, i.e., they affect the diffusion part of an RD-equation. We demonstrate, for the first time, by using a state-of-the-art, anatomically realistic model of the pig heart, how differences in the geometrical and biophysical nature of such inhomogeneities can influence scroll-wave dynamics in different ways. Our study reveals that conduction-type inhomogeneities become increasingly important at small length scales, i.e., in the case of multiple, randomly distributed, obstacles in space at the cellular scale (0.2-0.4 mm). Such configurations can lead to scroll-wave break up. In contrast, ionic inhomogeneities affect scroll-wave dynamics significantly at large length scales, when these inhomogeneities are localized in space at the tissue level (5-10 mm). In such configurations, these inhomogeneities can attract scroll waves, by pinning them to the heterogeneity, or lead to scroll-wave breakup.

  4. Highly conformal and high-ionic conductivity thin-film electrolyte for 3D-structured micro batteries: Characterization of LiPON film deposited by MOCVD method

    NASA Astrophysics Data System (ADS)

    Fujibayashi, Takashi; Kubota, Yusuke; Iwabuchi, Katsuhiko; Yoshii, Naoki

    2017-08-01

    This paper reports a lithium phosphorus oxynitride (LiPON) thin-film electrolyte deposited using a metalorganic-chemical vapor deposition (MOCVD) method for 3D-structured micro batteries. It is shown that the MOCVD-LiPON film has both highly-conformal step coverage on a patterned substrate with line/space=2μm/2μm and aspect ratio=1 (51±3 nm) and high-ionic conductivity for very thin films deposited at 4.7 nm/min (5.9×10-6 S/cm for 190 nm and 5.3×10-6 S/cm for 95 nm). Detailed material characterization attributes the enhancement in ionic conductivity to a decrease in nanocrystallite size and improvement in chemical-composition uniformity in the film. In addition, electrochemical characterization of an all-solid-state thin-film battery fabricated with the 190 nm-thick LiPON film (Si substrate/Ti/Pt/LiCoO2/LiPON/a-Si:H/Cu) demonstrates that the LiPON film can successfully act as the electrolyte for lithium-ion batteries. Therefore, the MOCVD-LiPON film is a promising candidate material to realize 3D-structured micro batteries in the near future.

  5. Proton conducting sulfonated poly (imide-benzimidazole) with tunable density of covalent/ionic cross-linking for fuel cell membranes

    NASA Astrophysics Data System (ADS)

    Yue, Zhouying; Cai, Yang-Ben; Xu, Shiai

    2015-07-01

    Ionic cross-linked sulfonated polyimides containing bis-benzimidazole rings have been prepared from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 6,6‧-bis[2-(4-aminophenyl)benzimidazole] (BAPBI) and 3,3‧-bis(4-sulfophenoxy)- benzidine (BSPOB). A new cross-linker, 4,4‧-bibromomethenyl diphenyl ether, is used to induce covalent cross-linking between halogen and imidazole groups in SPIBI chains via a facile thermally activated reaction. The resulted covalent and ionic cross-linked membranes show an improved resistance to hydrolytic attack in deionized water at 80 °C (more than two months) and free radical attack in Fenton's solution (more than 690 min) as compared to non-cross-linked SPIBIs (less than two days and 270 min, respectively). Cross-linking also results in a reduction in proton conductivity due to the blockage of a hydrophilic channel. However, all the prepared CBr-ySPIBI-x membranes show a proton conductivity higher than 10-2 S cm-1 under hydrous condition. This could be attributed to the fact that more cross-linking sites are contained in each repeating unit, which ensures enough cross-linking degree at high sulfonation level. All these results suggest that CBr-ySPIBI-x membranes have a great potential for applications in the proton exchange membrane fuel cells.

  6. Effect of Ionic Conductivity on Response Speed of SrTiO3-Based All-Solid-State Electric-Double-Layer Transistor.

    PubMed

    Tsuchiya, Takashi; Ochi, Masanori; Higuchi, Tohru; Terabe, Kazuya; Aono, Masakazu

    2015-06-10

    An all-solid-state electric-double-layer transistor (EDLT) with a Y-stabilized ZrO₂ (YSZ) proton conductor/SrTiO₃ (STO) single crystal has been fabricated to investigate ionic conductivity effect on the response speed, which should be a key parameter for development of next-generation EDLTs. The drain current exhibited a 4-order-of-magnitude increment by electrostatic carrier doping at the YSZ/STO interface due to ion migration, and the behavior strongly depended on the operation temperature. An Arrhenius-type plot of the ionic conductivity (σ(i)) in the YSZ and t(c)⁻¹, which is a current-rise time needed for charge accumulation at the YSZ/STO interface, shows a synchronized variation, indicating a proportional relationship between the two parameters. Analysis of the σ(i)-t(c) diagram shows that, in contrast to conventional EDLTs, the response speed should reach picosecond order at room temperature by using extreme miniaturization and superionic conductors. Furthermore, the diagram indicates that plenty of solid electrolytes, which have not been used due to the lack of criteria for evaluation, can be a candidate for all-solid-state EDLTs exceeding the carrier density of conventional EDLTs, even though the response speed becomes comparably lower than those of FETs.

  7. Effective Energy Transfer via Plasmon-Activated High-Energy Water Promotes Its Fundamental Activities of Solubility, Ionic Conductivity, and Extraction at Room Temperature.

    PubMed

    Yang, Chih-Ping; Chen, Hsiao-Chien; Wang, Ching-Chiung; Tsai, Po-Wei; Ho, Chia-Wen; Liu, Yu-Chuan

    2015-12-10

    Water is a ubiquitous solvent in biological, physical, and chemical processes. Unique properties of water result from water's tetrahedral hydrogen-bonded (HB) network (THBN). The original THBN is destroyed when water is confined in a nanosized environment or localized at interfaces, resulting in corresponding changes in HB-dependent properties. In this work, we present an innovative idea to validate the reserve energy of high-energy water and applications of high-energy water to promote water's fundamental activities of solubility, ionic conductivity, and extraction at room temperature. High-energy water with reduced HBs was created by utilizing hot electrons with energies from the decay of surface plasmon excited at gold (Au) nanoparticles (NPs). Compared to conventional deionized (DI) water, solubilities of alkali metal-chloride salts in high-energy water were significantly increased, especially for salts that release heat when dissolved. The ionic conductivity of NaCl in high-energy water was also markedly higher, especially when the electrolyte's concentration was extremely low. In addition, antioxidative components, such as polyphenols and 2,3,5,4'-tetrahydroxystilbene-2-O-beta-d-glucoside (THSG) from teas, and Polygonum multiflorum (PM), could more effectively be extracted using high-energy water. These results demonstrate that high-energy water has emerged as a promising innovative solvent for promoting water's fundamental activities via effective energy transfer.

  8. Effective Energy Transfer via Plasmon-Activated High-Energy Water Promotes Its Fundamental Activities of Solubility, Ionic Conductivity, and Extraction at Room Temperature

    NASA Astrophysics Data System (ADS)

    Yang, Chih-Ping; Chen, Hsiao-Chien; Wang, Ching-Chiung; Tsai, Po-Wei; Ho, Chia-Wen; Liu, Yu-Chuan

    2015-12-01

    Water is a ubiquitous solvent in biological, physical, and chemical processes. Unique properties of water result from water’s tetrahedral hydrogen-bonded (HB) network (THBN). The original THBN is destroyed when water is confined in a nanosized environment or localized at interfaces, resulting in corresponding changes in HB-dependent properties. In this work, we present an innovative idea to validate the reserve energy of high-energy water and applications of high-energy water to promote water’s fundamental activities of solubility, ionic conductivity, and extraction at room temperature. High-energy water with reduced HBs was created by utilizing hot electrons with energies from the decay of surface plasmon excited at gold (Au) nanoparticles (NPs). Compared to conventional deionized (DI) water, solubilities of alkali metal-chloride salts in high-energy water were significantly increased, especially for salts that release heat when dissolved. The ionic conductivity of NaCl in high-energy water was also markedly higher, especially when the electrolyte’s concentration was extremely low. In addition, antioxidative components, such as polyphenols and 2,3,5,4’-tetrahydroxystilbene-2-O-beta-d-glucoside (THSG) from teas, and Polygonum multiflorum (PM), could more effectively be extracted using high-energy water. These results demonstrate that high-energy water has emerged as a promising innovative solvent for promoting water’s fundamental activities via effective energy transfer.

  9. Scroll-wave dynamics in the presence of ionic and conduction inhomogeneities in an anatomically realistic mathematical model for the pig heart

    NASA Astrophysics Data System (ADS)

    Majumder, R.; Pandit, R.; Panfilov, A. V.

    2016-12-01

    Nonlinear waves of the reaction-diffusion (RD) type occur in many biophysical systems, including the heart, where they initiate cardiac contraction. Such waves can form vortices called scroll waves, which result in the onset of life-threatening cardiac arrhythmias. The dynamics of scroll waves is affected by the presence of inhomogeneities, which, in a very general way, can be of ionic type, i.e., they affect the reaction part, or conduction type, i.e., they affect the diffusion part of an RD-equation. We demostrate, for the first time, by using a state-of-the-art, anatomically realistic model of the pig heart, how differences in the geometrical and biophysical nature of such inhomogeneities can influence scroll-wave dynamics in different ways. Our study reveals that conduction-type inhomogeneities become increasingly important at small length scales, i.e., in the case of multiple, randomly distributed, obstacles in space at the cellular scale (0.2-0.4mm). Such configurations can lead to scroll-wave break up. In contrast, ionic inhomogeneities, affect scroll-wave dynamics significantly at large length scales, when these inhomogeneities are localized in space at the tissue level (5-10mm). In such configurations, these inhomogeneities can attract scroll waves, by pinning them to the heterogeneity, or lead to scroll-wave breakup.

  10. Investigation of ionic conductivity and long-term stability of a LiI and KI coupled diphenylamine quasi-solid-state dye-sensitized solar cell.

    PubMed

    Agarwala, S; Peh, C K N; Ho, G W

    2011-07-01

    In this work, enhancement of ionic conductivity and long-term stability through the addition of diphenylamine (DPA) in poly(ethylene oxide) (PEO) is demonstrated. Potassium iodide (KI) is adopted as the crystal growth inhibitor, and DPA is used as a charge transport enhancer in the electrolyte. The modified electrolyte is used with titanium dioxide (TiO2) nanoparticles, which is systematically tuned to obtain high surface area. The dye-sensitized solar cell (DSSC) showed a photocurrent of 14 mAcm2 with a total conversion efficiency of 5.8% under one sun irradiation. DPA enhances the interaction of the TiO2 nanoparticle film and the I-/I3- electrolyte leading to high ionic conductivity (3.5 × 10-3 Scm-1), without compromising on the electrochemical and mechanical stability. Electrochemical impedance spectroscopy (EIS) studies show that electron transport and electron lifetime are enhanced in the DPA added electrolyte due to reduced sublimation of iodine. The most promising feature of the electrolyte is increased device stability with 89% of the overall efficiency preserved even after 40 days.

  11. Conductive porous sponge-like ionic liquid-graphene assembly decorated with nanosized polyaniline as active electrode material for supercapacitor

    NASA Astrophysics Data System (ADS)

    Halab Shaeli Iessa, K.; Zhang, Yan; Zhang, Guoan; Xiao, Fei; Wang, Shuai

    2016-01-01

    We report the development of three-dimensional (3D) porous sponge-like ionic liquid (IL)-graphene hybrid material by integrating IL molecules and graphene nanosheets via self-assembly process. The as-obtained IL-graphene architecture possesses high surface area, efficient electron transport network and fast charge transfer kinetics owing to its highly porous structure, and unique hydrophilic properties derived from the IL anion on its surface, which endows it with high desire for supercapacitor application. Redox-active polyaniline (PANI) nanorods are further decorated on IL-graphene scaffold by electropolymerization. When utilized as freestanding 3D electrode for supercapacitor, the resultant PANI modified IL-graphene (PANI-IL-graphene) electrode exhibits a specific capacitance up to 662 F g-1 at the current density of 1.0 A g-1, with a high capacitance retention of 73.7% as current densities increase from 1.0 to 20 A g-1, and the capacitance degradation is less than 7.0% after 5000 charge-discharge cycles at 10 A g-1.

  12. Thiophosphates Containing Ag(+) and Lone-Pair Cations with Interchiral Double Helix Show Both Ionic Conductivity and Phase Transition.

    PubMed

    Fan, Yu-Hang; Zeng, Hui-Yi; Jiang, Xiao-Ming; Zhang, Ming-Jian; Liu, Bin-Wen; Guo, Guo-Cong; Huang, Jin-Shun

    2017-01-17

    Quaternary metal thiophosphates containing second-order Jahn-Teller distorted d(10) Ag(+) and lone-pair cations, Ag3Bi(PS4)2 (1), Ag7Sn(PS4)3 (2), and Ag7Pb(PS4)3 (3), were obtained by solid-state synthesis. The structural frameworks of 2 and 3 feature an infinite 1-D interchiral double helix ∞(1)(Ag3P2S11), which is rare in inorganic compounds. Compound 3 undergoes a significant first-order structural phase transition from monoclinic to hexagonal at ∼204 °C. This can be ascribed to the significant mismatch in the expansion coefficients between Pb-S (Ag-S) and P-S bonds evaluated by bond valence theory. The three compounds are Ag(+) ionic conductors, and Ag(+) ion migration pathways are proposed by calculating maps of low bond valence mismatch. Moreover, the optical properties of the three compounds were studied, and electronic structure calculations were performed. The combination of second-order Jahn-Teller distorted d(10) cation and lone-pair cation provides a new strategy to explore new metal thiophosphates with interesting structures and promising properties.

  13. Ion distribution in quaternary-ammonium-functionalized aromatic polymers: effects on the ionic clustering and conductivity of anion-exchange membranes.

    PubMed

    Weiber, E Annika; Jannasch, Patric

    2014-09-01

    A series of copoly(arylene ether sulfone)s that have precisely two, three, or four quaternary ammonium (QA) groups clustered directly on single phenylene rings along the backbone are studied as anion-exchange membranes. The copolymers are synthesized by condensation polymerizations that involve either di-, tri-, or tetramethylhydroquinone followed by virtually complete benzylic bromination using N-bromosuccinimide and quaternization with trimethylamine. This synthetic strategy allows excellent control and systematic variation of the local density and distribution of QA groups along the backbone. Small-angle X-ray scattering of these copolymers shows extensive ionic clustering, promoted by an increasing density of QA on the single phenylene rings. At an ion-exchange capacity (IEC) of 2.1 meq g(-1), the water uptake decreases with the increasing local density of QA groups. Moreover, at moderate IECs at 20 °C, the Br(-) conductivity of the densely functionalized copolymers is higher than a corresponding randomly functionalized polymer, despite the significantly higher water uptake of the latter. Thus, the location of multiple cations on single aromatic rings in the polymers facilitates the formation of a distinct percolating hydrophilic phase domain with a high ionic concentration to promote efficient anion transport, despite probable limitations by reduced ion dissociation. These findings imply a viable strategy to improve the performance of alkaline membrane fuel cells.

  14. Study of microstructural characterization and ionic conductivity of a chemical-covalent polyether-siloxane hybrid doped with LiClO4.

    PubMed

    Liang, Wuu-Jyh; Chen, Ying-Pin; Wu, Chien-Pang; Kuo, Ping-Lin

    2005-12-29

    The chemical-covalent polyether-siloxane hybrids (EDS) doped with various amounts of LiClO4 salt were characterized by FT-IR, DSC, TGA, and solid-state NMR spectra as well as impedance measurements. These observations indicate that different types of complexes by the interactions of Li+ and ClO4- ions are formed within the hybrid host, and the formation of transient cross-links between Li+ ions and ether oxygens results in the increase in T(g) of polyether segments and the decrease in thermal stability of hybrid electrolyte. Initially a cation complexation dominated by the oxirane-cleaved cross-link site and PEO block is present, and after the salt-doped level of O/Li+ = 20, the complexation through the PPO block becomes more prominent. Moreover, a significant degree of ionic association is examined in the polymer-salt complexes at higher salt uptakes. A VTF-like temperature dependence of ionic conductivity is observed in all of the investigated salt concentrations, implying that the diffusion of charge carrier is assisted by the segmental motions of the polymer chains. The behavior of ion transport in these hybrid electrolytes is further correlated with the interactions between ions and polymer host.

  15. Exploration on effects of 15 nm SiO2 filler on miscibility, thermal stability and ionic conductivity of PMMA/ENR 50 electrolytes

    NASA Astrophysics Data System (ADS)

    Zamri, S. F. M.; Latif, F. A.; Ali, A. M. M.; Ibrahim, R.; Azuan, S. I. H. M.; Kamaluddin, N.; Hadip, F.

    2017-02-01

    The effects of silicon dioxide (SiO2) (15 nm) filler on miscibility, thermal stability and ionic conductivity of polymethyl methacrylate/50% epoxidized narural rubber (PMMA/ENR 50) electrolytes were successfully explored. Samples were prepared by solvent casting method with tetrahydrofuran (THF) as solvent and doped with lithium tetrafluoroborate (LiBF4). Fourier transform infrared spectroscopy (FTIR) confirmed the present of hydrogen bond between PMMA and ENR 50. However, the hydrogen bond was reduced when SiO2 was added. Differential scanning calorimeter (DSC) analysis shows that PMMA/ENR 50 blends exhibit two glass transition temperatures (Tgs) recorded at -35 and 89 °C corresponding to the Tg of ENR 50 rich phase (Tg1) and PMMA rich phase (Tg2), respectively. However, the two Tgs almost merging and reduced when SiO2 was added. Tg1 was found increases as SiO2 weight percent increased. Thermogravimetric analysis (TGA) revealed that thermal degradation temperatures (Tds) of SiO2 filled PMMA/ENR 50 was similar as PMMA/ENR 50. Interestingly, thermal degradation temperatures of the loss of impurities (Td1) and thermal degradation temperatures of PMMA side chain (Td2) were increased when SiO2 was added. Meanwhile thermal degradation temperatures of main PMMA and ENR 50 main chain (Td3) was decreased as SiO2 was added. There was no significant change in Td1, Td2 and Td3 as SiO2 weight percent was varied. Electrochemical impedence spectroscopy (EIS) analysis shows that room temperature ionic conductivity of SiO2 filled PMMA/ENR 50 electrolytes were higher compaed PMMA/ENR 50 electrolyte with two conductivity maxima.

  16. Ionic Intercalation in Two-Dimensional van der Waals Materials: In Situ Characterization and Electrochemical Control of the Anisotropic Thermal Conductivity of Black Phosphorus.

    PubMed

    Kang, Joon Sang; Ke, Ming; Hu, Yongjie

    2017-03-08

    Two-dimensional van der Waals materials have shown novel fundamental properties and promise for wide applications. Here, we report for the first time an experimental demonstration of the in situ characterization and highly reversible control of the anisotropic thermal conductivity of black phosphorus. We develop a novel platform based on lithium ion batteries that integrates ultrafast optical spectroscopy and electrochemical control to investigate the interactions between lithium ions and the lattices of the black phosphorus electrode. We discover a strong dependence of the thermal conductivity on battery charge states (lithium concentrations) during the discharge/charge process. The thermal conductivity of black phosphorus is reversibly tunable over a wide range of 2.45-3.86, 62.67-85.80, and 21.66-27.58 W·m(-1)·K(-1) in the cross-plan, zigzag, and armchair directions, respectively. The modulation in thermal conductivity is attributed to phonon scattering introduced by the ionic intercalation in between the interspacing layers and shows anisotropic phonon scattering mechanism based on semiclassical model. At the fully discharged state (x ∼ 3 in LixP), a dramatic reduction of thermal conductivity by up to 6 times from that of the pristine crystal has been observed. This study provides a unique approach to explore the fundamental energy transport involving lattices and ions in the layered structures and may open up new opportunities in controlling energy transport based on novel operation mechanisms and the rational design of nanostructures.

  17. An evaluation of in-situ measurements of water temperature, specific conductance, and pH in low ionic strength streams

    USGS Publications Warehouse

    Ranalli, A.J.

    1998-01-01

    Survey for continuous measurement of water temperature, specific conductance, and pH in four low ionic strength streams in the Catskill Mountains of New York was evaluated through a calculation of their bias, precision, and accuracy and by comparison with laboratory measurements of specific conductance and pH on samples collected concurrently. Results indicate that the mini-monitor measurements of specific conductance and pH in an acidic stream (acid-neutralizing capacity always less than 0) agreed with laboratory measurements well enough that the minimonitors can be used to supplement laboratory measurements (mean difference in pH was 0.02 pH unit and mean difference in specific conductance was 0.72 ??S cm-1. This mean difference was 0.32 ??S cm-1 if the minimonitor data were adjusted by the bias). In less acidic streams (two streams in which the acid-neutralizing capacity was always greater than 0 and one in which the acid-neutralizing capacity was greater than 0 except during high flows), there was poor agreement between laboratory and minimonitor measurements of specific conductance at high flows and pH at all flows. The water-temperature probes measured with sufficiently small bias (-0.1 ??C) and adequate precision (??0.70 ??C) for use with most applications.

  18. Chloride conductance across toad skin: effects of ionic acclimations and cyclic AMP and relationship to mitochondria-rich cell density.

    PubMed

    Rozman, A; Gabbay, S; Katz, U

    2000-07-01

    The anionic conductance across toad (Bufo viridis) skin was studied using the voltage-clamp technique following long-term (more than 10 days) acclimation to NaCl and KCl solutions. The non-specific baseline conductance was approximately 0.6 mS cm(-)(2) and was similar in skins from all acclimation conditions. The voltage-activated Cl(-) conductance (G(Cl)) was maximal in skins from distilled-water- and KCl-acclimated toads (>3 mS cm(-)(2)) and was greatly reduced following acclimation to NaCl solutions. Cyclic AMP (EC(50)=13 micromol l(-)(1)) and isobutylmethyl xanthine (IBMX) (EC(50)=69 micromol l(-)(1)) exerted different effects on the activated conductance. IBMX only sensitized the activated conductance, whereas cyclic AMP (CPTcAMP) at high concentrations induced an increase in anionic conductance that was insensitive to electrical potential. Furthermore, external Cl(-) was not required for the stimulatory effect of cyclic AMP, and the conductive pathway had low selectivity. The effects of the two agonists were reversible and depended on the acclimation conditions. Following electrical measurements, the skin of the toads was removed and stained with silver to measure mitochondria-rich cell density (D(mrc)). There was no correlation between D(mrc) and Cl(-) conductance in the present study.

  19. Effect of Li{sub 2}SO{sub 4} addition on structure and ionic conductivity of lithium borosilicotitanate glasses

    SciTech Connect

    Satpute, N. S.; Deshpande, A. V.

    2014-04-24

    Lithium borosilicotitanate glasses containing Li{sub 2}SO{sub 4} were prepared by melt quenching technique. Electrical conductivity, density, molar volume and glass transition temperature T{sub g} for all the glass samples were measured. IR spectroscopy was used for structural studies of these glasses in the range from 400 to 2000 cm{sub −1}. The conductivity of the Li{sub 2}SO{sub 4} containing glasses was found to be half an order higher than the base glass. The electrical conductivity was interpreted from the point of view of glass structure which suggests that an enhancement in conductivity is due to the incorporation of Li{sub 2}SO{sub 4} in the macromolecular network. The molar volume and glass transition temperature T{sub g} results are found to be in good correlation with conductivity results.

  20. A comparison of propagated action potentials from tropical and temperate squid axons: different durations and conduction velocities correlate with ionic conductance levels.

    PubMed

    Rosenthal, Joshua J C; Bezanilla, Francisco

    2002-06-01

    To determine which physiological properties contribute to temperature adaptation in the squid giant axon, action potentials were recorded from four species of squid whose habitats span a temperature range of 20 degrees C. The environments of these species can be ranked from coldest to warmest as follows: Loligo opalescens>Loligo pealei>Loligo plei>Sepioteuthis sepioidea. Action potential conduction velocities and rise times, recorded at many temperatures, were equivalent for all Loligo species, but significantly slower in S. sepioidea. By contrast, the action potential's fall time differed among species and correlated well with the thermal environment of the species ('warmer' species had slower decay times). The biophysical underpinnings of these differences were examined in voltage-clamped axons. Surprisingly, no differences were found between the activation kinetics or voltage-dependence of Na(+) and K(+) currents. Conductance levels, however, did vary. Maximum Na(+) conductance (g(Na)) in S. sepiodea was significantly less than in the Loligo species. K(+) conductance (gK) was highest in L. pealei, intermediate in L. plei and smallest in S. sepiodea. The time course and magnitude of g(K) and g(Na) were measured directly during membrane action potentials. These data reveal clear species-dependent differences in the amount of g(K) and g(Na) recruited during an action potential.

  1. Liquid-like ionic conduction in solid lithium and sodium monocarba-closo-decaborates near or at room temperature

    DOE PAGES

    Tang, Wan Si; Matsuo, Motoaki; Wu, Hui; ...

    2016-02-05

    Both LiCB9H10 and NaCB9H10 exhibit liquid-like cationic conductivities (≥0.03 S cm–1) in their disordered hexagonal phases near or at room temperature. Furthermore, these unprecedented conductivities and favorable stabilities enabled by the large pseudoaromatic polyhedral anions render these materials in their pristine or further modified forms as promising solid electrolytes in next-generation, power devices.

  2. A high performance flexible all solid state supercapacitor based on the MnO2 sphere coated macro/mesoporous Ni/C electrode and ionic conducting electrolyte

    NASA Astrophysics Data System (ADS)

    Zhi, Jian; Reiser, Oliver; Wang, Youfu; Hu, Aiguo

    2016-06-01

    A high contact resistance between the active materials and the current collector, a low ionic conductivity of the gel electrolyte, and an impenetrable electrode structure are the three major barriers which greatly limit the capacitance of MnO2 in solid state supercapacitors. As a potential solution to these problems, in this work we report a novel electrode for solid state supercapacitors, based on a ternary system composed of hierarchical MnO2 spheres as the active material, macroporous Ni foam as gel penetrable skeletons and an ordered mesoporous carbon (OMC) membrane as the charge-transport accelerating layer. By employing butyl-3-methylimidazolium chloride (BMIMCl) modified gels as the ionic conducting electrolyte, the utilization efficiency of MnO2 on the specific capacitance was enhanced up to 88% of the theoretical value, delivering a volumetric capacitance of 81 F cm-3, which is the highest value among MnO2 based solid state supercapacitors. Moreover, such a flexible device exhibits exceptional volumetric energy and power density (6.6 Wh L-1 and 549 W L-1, based on the whole device volume) combined with a small capacity loss of 8.5% after 6000 cycles under twisting. These encouraging findings unambiguously overcome the energy bottleneck of MnO2 in solid state supercapacitors, and open up a new application of macro/mesoporous materials in flexible devices.A high contact resistance between the active materials and the current collector, a low ionic conductivity of the gel electrolyte, and an impenetrable electrode structure are the three major barriers which greatly limit the capacitance of MnO2 in solid state supercapacitors. As a potential solution to these problems, in this work we report a novel electrode for solid state supercapacitors, based on a ternary system composed of hierarchical MnO2 spheres as the active material, macroporous Ni foam as gel penetrable skeletons and an ordered mesoporous carbon (OMC) membrane as the charge-transport accelerating

  3. Solid-state electrochromic devices composed of Prussian blue, WO/sub 3/, and poly(ethylene oxide)-polysiloxane hybrid-type ionic conducting membrane

    SciTech Connect

    Honda, K.; Ohgaki, K.; Fujito, M.; Ishida, H.; Yamamoto, R.

    1988-12-01

    The preparation of a new type of poly(ethylene oxide)-polysiloxane hybrid (PEOS) with its application to the construction of solid-state electrochromic devices was studied. The PEOS was given as a colorless and elastic membrane by condensation of a bis(silylpropyl) ether of oligo(ethylene oxide) and a polyalkoxysilane in the presence of LiClO/sub 4/ (2-5 mole percent). The ionic conductivity reached 10/sup -3/ S cm/sup -1/ when PEOS was swollen with propylene carbonate by 160% in weight. A transparent-type solid-state electrochromic device composed of Prussian blue- and WO/sub 3/-coated electrodes with PEOS was prepared, switching of which was slower by a factor of 1.5-2.0 as a function of half-time of coloration and bleaching compared with the corresponding liquid-type cell.

  4. Effect of poly(ethylene oxide) on ionic conductivity and electrochemical properties of poly(vinylidenefluoride) based polymer gel electrolytes prepared by electrospinning for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Prasanth, Raghavan; Shubha, Nageswaran; Hng, Huey Hoon; Srinivasan, Madhavi

    2014-01-01

    Effect of poly(ethylene oxide) on the electrochemical properties of polymer electrolyte based on electrospun, non-woven membrane of PVdF is demonstrated. Electrospinning process parameters are controlled to get a fibrous membrane consisting of bead-free, uniformly dispersed thin fibers with diameter in the range of 1.5-1.9 μm. The membrane with good mechanical strength and porosity exhibits high uptake when activated with the liquid electrolyte of lithium salt in a mixture of organic solvents. The polymer gel electrolyte shows ionic conductivity of 4.9 × 10-3 S cm-1 at room temperature. Electrochemical performance of the polymer gel electrolyte is evaluated in Li/polymer electrolyte/LiFePO4 coin cell. Good performance with low capacity fading on charge-discharge cycling is demonstrated.

  5. Ionic Conductivity of Mesostructured Yttria-Stabilized Zirconia Thin Films with Cubic Pore Symmetry—On the Influence of Water on the Surface Oxygen Ion Transport.

    PubMed

    Elm, Matthias T; Hofmann, Jonas D; Suchomski, Christian; Janek, Jürgen; Brezesinski, Torsten

    2015-06-10

    Thermally stable, ordered mesoporous thin films of 8 mol % yttria-stabilized zirconia (YSZ) were prepared by solution-phase coassembly of chloride salt precursors with an amphiphilic diblock copolymer using an evaporation-induced self-assembly process. The resulting material is of high quality and exhibits a well-defined three-dimensional network of pores averaging 24 nm in diameter after annealing at 600 °C for several hours. The wall structure is polycrystalline, with grains in the size range of 7 to 10 nm. Using impedance spectroscopy, the total electrical conductivity was measured between 200 and 500 °C under ambient atmosphere as well as in dry atmosphere for oxygen partial pressures ranging from 1 to 10(-4) bar. Similar to bulk YSZ, a constant ionic conductivity is observed over the whole oxygen partial pressure range investigated. In dry atmosphere, the sol-gel derived films have a much higher conductivity, with different activation energies for low and high temperatures. Overall, the results indicate a strong influence of the surface on the transport properties in cubic fluorite-type YSZ with high surface-to-volume ratio. A qualitative defect model which includes surface effects (annihilation of oxygen vacancies as a result of water adsorption) is proposed to explain the behavior and sensitivity of the conductivity to variations in the surrounding atmosphere.

  6. Ionic-to-electronic conductivity of glasses in the P2O5-V2O5-ZnO-Li2O system

    NASA Astrophysics Data System (ADS)

    Langar, A.; Sdiri, N.; Elhouichet, H.; Ferid, M.

    2016-12-01

    Glasses having a composition 15V2O5-5ZnO-(80- x P2O5- xLi2O ( x = 5 , 10, 15 mol%) were prepared by the conventional melt quenching. Conduction and relaxation mechanisms in these glasses were studied using impedance spectroscopy in a frequency range from 10 Hz to 10 MHz and in a temperature range from 513 K to 566 K. The structure of the amorphous synthetic product was corroborated by X-ray diffraction (disappearance of nacrite peaks). The DC conductivity follows the Arrhenius law and the activation energy determined by regression analysis varies with the content of Li2O. Frequency-dependent AC conductivity was analyzed by Jonscher's universal power law, which is varying as ωn, and the temperature-dependent power parameter supported by the Correlated Barrier Hopping (CBH) model. For x = 15 mol%, the values of n ≤ 0.5 confirm the dominance of ionic conductivity. The analysis of the modulus formalism with a distribution of relaxation times was carried out using the Kohlrausch-Williams-Watts (KWW) stretched exponential function. The stretching exponent, β, is dependent on temperature. The analysis of the temperature variation of the M" peak indicates that the relaxation process is thermally activated. Modulus study reveals the temperature-dependent non-Debye-type relaxation phenomenon.

  7. Garnet-Type Fast Li-Ion Conductors with High Ionic Conductivities for All-Solid-State Batteries.

    PubMed

    Wu, Jian-Fang; Pang, Wei Kong; Peterson, Vanessa K; Wei, Lu; Guo, Xin

    2017-04-12

    All-solid-state Li-ion batteries with metallic Li anodes and solid electrolytes could offer superior energy density and safety over conventional Li-ion batteries. However, compared with organic liquid electrolytes, the low conductivity of solid electrolytes and large electrolyte/electrode interfacial resistance impede their practical application. Garnet-type Li-ion conducting oxides are among the most promising electrolytes for all-solid-state Li-ion batteries. In this work, the large-radius Rb is doped at the La site of cubic Li6.10Ga0.30La3Zr2O12 to enhance the Li-ion conductivity for the first time. The Li6.20Ga0.30La2.95Rb0.05Zr2O12 electrolyte exhibits a Li-ion conductivity of 1.62 mS cm(-1) at room temperature, which is the highest conductivity reported until now. All-solid-state Li-ion batteries are constructed from the electrolyte, metallic Li anode, and LiFePO4 active cathode. The addition of Li(CF3SO2)2N electrolytic salt in the cathode effectively reduces the interfacial resistance, allowing for a high initial discharge capacity of 152 mAh g(-1) and good cycling stability with 110 mAh g(-1) retained after 20 cycles at a charge/discharge rate of 0.05 C at 60 °C.

  8. Ionic conductivity and dielectric relaxation in Y doped La2Mo2O9 oxide-ion conductors

    NASA Astrophysics Data System (ADS)

    Paul, T.; Ghosh, A.

    2014-10-01

    In this work, we have studied electrical conductivity and dielectric properties of polycrystalline La2-xYxMo2O9 (0.05 ≤ x ≤ 0.3) compounds in the temperature range from 358 K to 1088 K and the frequency range from 10 Hz to 3 GHz. The bulk and grain boundary contributions to the overall conductivity of these compounds show Arrhenius type behavior at low temperatures. The random free-energy barrier model has been used to analyze the frequency dependence of the conductivity. The charge carrier relaxation time and its activation energy have been determined from the analysis of the conductivity spectra using this model. The results obtained from the random free-energy barrier model satisfy Barton-Nakajima-Namikawa relation. The conduction mechanism has been also predicted using random free-energy barrier model and the scaling formalism. We have observed that the dielectric relaxation peaks arise from the diffusion of oxygen ions via vacancies.

  9. Ionic conductivity studies in crystalline PVA/NaAlg polymer blend electrolyte doped with alkali salt KCl

    NASA Astrophysics Data System (ADS)

    Sheela, T.; Bhajantri, R. F.; Ravindrachary, V.; Pujari, P. K.; Rathod, Sunil G.; Naik, Jagadish

    2014-04-01

    Potassium Chloride (KCl) doped poly(vinyl alcohol) (PVA)/sodium alginate (NaAlg) in 60:40 wt% polymer blend electrolytes were prepared by solution casting method. The complexation of KCl with host PVA/NaAlg blend is confirmed by FTIR and UV-Vis spectra. The XRD studies show that the crystallinity of the prepared blends increases with increase in doping. The dc conductivity increases with increase in dopant concentration. Temperature dependent dc conductivity shows an Arrhenius behavior. The dielectric properties show that both the dielectric constant and dielectric loss increases with increase in KCl doping concentration and decreases with frequency. The cole-cole plots show a decrease in bulk resistance, indicates the increase in ac conductivity, due to increase in charge carrier mobility. The doping of KCl enhances the mechanical properties of PVA/NaAlg, such as Young's modulus, tensile strength, stiffness.

  10. Ionic conduction in non-uniform nanopores and DNA translocation: a Nernst-Planck-Jacobs one-dimensional description

    NASA Astrophysics Data System (ADS)

    Marini Bettolo Marconi, Umberto; Melchionna, Simone

    2013-12-01

    The conduction of an electrolyte solution in the presence of a DNA intruder in a synthetic charged pore is studied by theoretical means. The pore conductivity is controlled by two competing mechanisms: the steric effect of the DNA decreases the current and the extra-surface charges determine an increase in the number of charge carriers that increase the current. By using a Nernst-Planck description of the electrolyte and a one-dimensional advection-diffusion equation similar to the Jacobs-Zwanzig method, we obtain the characteristic curve within the local electroneutrality approximation. Such an information allows predicting the variation of the conductance caused by the DNA intruder and determining the current blockage/enhancement phase diagram.

  11. Ionic conductivity of crystallization products of Ba1- x Yb x F2 + x melts ( x = 0.1, 0.2, 0.25)

    NASA Astrophysics Data System (ADS)

    Sorokin, N. I.; Sul'yanova, E. A.; Sobolev, B. P.

    2016-05-01

    The ionic conductivity σ of the crystallization products of Ba1 - x Yb x F2 + x melts with 10, 20 and 25 mol % YbF3 has been studied. A Ba0.9Yb0.1F2.1 sample is a solid solution with the CaF2 structure type, sp. gr. Fmoverline 3 m. A Ba0.8Yb0.2F2.2 sample contains two cubic forms with sp. gr. Fmoverline 3 m and Pmoverline 3 m. The σ values for Ba0.9Yb0.1F2.1 and Ba0.8Yb0.2F2.2 coincide and are equal to 3 × 10-5 S/cm at 500 K. A Ba0.75Yb0.25F2.25 sample is heterogeneous, despite its monolithic nature and transparency. A greater part of its volume has a cubic lattice with sp. gr. Pmoverline 3 m, while the smaller part is a phase crystallizing in the orthorhombic system. A change of composition from x = 0.2 to 0.25 leads to a change in the symmetry group and type of the cluster defects in the Ba1 - x Yb x F2 + x phase. The sp. gr. Fmoverline 3 m is replaced by the sp. gr. Pmoverline 3 m, and octahedral‒cubic {Ba8Yb6F69} clusters are transformed into "inverse" octahedral‒cubic {Yb8Ba6F71} clusters. These changes in the defect structure lead to an increase in conductivity by a factor of about 100. The fluorine-ionic conductivity of Ba0.75Yb0.25F2.25 is 2.5 × 10-3 S/cm at 500 K. This value exceeds the conductivity of Ba0.69La0.31F2.31 crystal by a factor of 15 (Ba0.69La0.31F2.31 has the best conducting properties among the fluorite phases of the Ba1 - x R x F2 + x family, for which σ was found to increase with a decrease in the atomic number of rare earth element (REE)).

  12. Ionic conductivity and electrical relaxation of nanocrystalline scandia-stabilized c-zirconia using complex impedance analysis

    NASA Astrophysics Data System (ADS)

    Kumar, Ashok; Manna, I.

    2008-07-01

    A solid solution of 8 mol% of scandia-stabilized cubic-zirconia (8ScSZ) has been prepared by co-precipitation technique. The synthesized powder has an average crystallite size ∼40 nm, surface area of 8.49 m 2/g, and agglomerated particle size of 150 nm. The activation energy of 8ScSZ has been calculated from impedance loss spectra; electrical modulus spectra are in the range of 0.90-1.30 eV. The frequency and temperature-dependent conductivities and impedance were measured in range of 50 Hz-1 MHz and 300-900 K, respectively. Complex impedance spectra, complex modulus formalism and complex conductivity spectra have been carefully analyzed in order to separate the grain, grain boundary and electrode-electrolyte effects. Analysis of ac impedance data using complex impedance indicates a typical negative temperature coefficient of resistance (NTCR) behavior of the materials. The intrinsic conductivity is mainly due to hopping of mobile ions among the available localized site. Relaxation time obtained from complex conductivity spectra are matched well with the impedance loss and modulus loss spectra. Impedance analysis suggests the presence of temperature-dependent electrical relaxation process in the material.

  13. Hierarchical Nanostructured WO3 with Biomimetic Proton Channels and Mixed Ionic-Electronic Conductivity for Electrochemical Energy Storage.

    PubMed

    Chen, Zheng; Peng, Yiting; Liu, Fang; Le, Zaiyuan; Zhu, Jian; Shen, Gurong; Zhang, Dieqing; Wen, Meicheng; Xiao, Shuning; Liu, Chi-Ping; Lu, Yunfeng; Li, Hexing

    2015-10-14

    Protein channels in biologic systems can effectively transport ions such as proton (H(+)), sodium (Na(+)), and calcium (Ca(+)) ions. However, none of such channels is able to conduct electrons. Inspired by the biologic proton channels, we report a novel hierarchical nanostructured hydrous hexagonal WO3 (h-WO3) which can conduct both protons and electrons. This mixed protonic-electronic conductor (MPEC) can be synthesized by a facile single-step hydrothermal reaction at low temperature, which results in a three-dimensional nanostructure self-assembled from h-WO3 nanorods. Such a unique h-WO3 contains biomimetic proton channels where single-file water chains embedded within the electron-conducting matrix, which is critical for fast electrokinetics. The mixed conductivities, high redox capacitance, and structural robustness afford the h-WO3 with unprecedented electrochemical performance, including high capacitance, fast charge/discharge capability, and very long cycling life (>50,000 cycles without capacitance decay), thus providing a new platform for a broad range of applications.

  14. Effects of prolactin on ionic membrane conductances in the human malignant astrocytoma cell line U87-MG.

    PubMed

    Ducret, Thomas; Vacher, Anne-Marie; Vacher, Pierre

    2004-03-01

    Prolactin (PRL) is involved in numerous biological processes in peripheral tissues and the brain. Although numerous studies have been conducted to elucidate the signal transduction pathways associated with the PRL receptor, very few have examined the role of ion conductances in PRL actions. We used the patch-clamp technique in "whole cell" configuration and microspectrofluorimetry to investigate the effects of PRL on membrane ion conductances in the U87-MG human malignant astrocytoma cell line, which naturally expresses the PRL receptor. We found that a physiological concentration (4 nM) of PRL exerted a biphasic action on membrane conductances. First, PRL activated a Ca(2+)-dependent K(+) current that was sensitive to CTX and TEA. This current depended on PRL-induced Ca(2+) mobilization, through a JAK2-dependent pathway from a thapsigargin- and 2-APB-sensitive Ca(2+) pool. Second, PRL also activated an inwardly directed current, mainly due to the stimulation of calcium influx via nickel- and 2-APB-sensitive calcium channels. Both phases resulted in membrane hyperpolarizations, mainly through the activation of Ca(2+)-dependent K(+) channels. As shown by combined experiments (electrophysiology and microspectrofluorimetry), the PRL-induced Ca(2+) influx increased with cell membrane hyperpolarization and conversely decreased with cell membrane depolarization. Thus PRL-induced membrane hyperpolarizations facilitated Ca(2+) influx through voltage-independent Ca(2+) channels. Finally, PRL also activated a DIDS-sensitive Cl(-) current, which may participate in the PRL-induced hyperpolarization. These PRL-induced conductance activations are probably related to the PRL proliferative effect we have already described in U87-MG cells.

  15. Ionic conductivity, structural and thermal properties of pure and Sr 2+ doped Y 2Ti 2O 7 pyrochlores for SOFC

    NASA Astrophysics Data System (ADS)

    Gill, Jasmeet Kaur; Pandey, O. P.; Singh, K.

    2011-11-01

    In the present study, SrO doped Yttrium titanate pyrochlore was synthesized using solid state reaction technique. The sintering characteristics, crystal structure, thermal and conductivity behavior of doped and undoped pyrochlores have been studied to find their suitability in solid oxide fuel cells (SOFC). The as-prepared samples were characterized using X-ray diffraction (XRD), Fourier-Transform-Infrared spectroscopy (FT-IR), thermal-gravimetric analysis (TGA) and ac conductivity up to 900 °C. The results are discussed in light of oxygen vacancy formation and structural disordering. Undoped and doped yttrium titanate with SrO ( x = 0.1) exhibits single Y 2Ti 2O 7 phase with relative density of 94%. It was observed that further doping of SrO ( x = 0.2-0.4) leads to formation of Y 2Ti 2O 7 phase along with SrTiO 3 phase. Excessive SrO ( x = 0.4) results in increase in ionic conductivity to 1.50 × 10 -1 S cm -1 whereas it impedes the densification process with relative density of 85%.

  16. Dielectric relaxation dynamics and AC conductivity scaling of metal-organic framework (MOF-5) based polymer electrolyte nanocomposites incorporated with ionic liquid

    NASA Astrophysics Data System (ADS)

    Dutta, Rituraj; Kumar, A.

    2017-10-01

    Dielectric relaxation dynamics and AC conductivity scaling of a metal-organic framework (MOF-5) based poly (vinylidene fluoride-co-hexafluoropropylene) (PVdf-HFP) incorporated with 1-Butyl-3-methylimidazolium hexafluorophosphate have been studied over a frequency range of 40 Hz–5 MHz and in the temperature range of 300 K–380 K. High values of dielectric permittivity (~{{\\varepsilon }\\prime} ) having strong dispersion are obtained at low frequency because of interfacial polarization. The real part of the dielectric modulus spectra (M‧) shows no prominent peak, whereas the imaginary part (M″) shows certain peaks, with a reduction in relaxation time (τ) that can be attributed to a non-Debye relaxation mechanism. The spectra also depict both concentration- and temperature-independent scaling behavior. The power law dependent variation of AC conductivity follows the jump relaxation model and reveals activated ion hopping over diffusion barriers. The value of the frequency exponent is observed to decrease with increasing concentration of ionic liquid, indicating the forward hopping of ions in the relaxation process. The AC conductivity scaling curves at different temperatures also depict the temperature-independent relaxation dynamics.

  17. Rietveld refinement, electronic structure and ionic conductivity of Sr4La6(SiO4)6F2 and Sr4La6(SiO4)6O ceramics

    NASA Astrophysics Data System (ADS)

    Boughzala, Khaled; Debbichi, Mourad; Njema, Hela; Bouzouita, Khaled

    2016-07-01

    In this paper, we report the effect of the tunnel anions on the ionic conductivity of Strontium-Lanthanum silicate apatites. The Sr4La6(SiO4)6F2 and Sr4La6(SiO4)6O ceramics were prepared by the solid state reaction method. X-ray diffraction, NMR spectroscopy and Raman measurements were performed to investigate the crystal structure and vibrational active modes. Moreover, the electronic structures of the crystals were evaluated by the first-principles quantum mechanical calculation based on the density functional theory. Finally, the ionic conductivity was studied according to the complex impedance method.

  18. Structural and ionic conductivity behavior in hydroxypropylmethylcellulose (HPMC) polymer films complexed with sodium iodide (NaI)

    NASA Astrophysics Data System (ADS)

    Rani, N. Sandhya; Sannappa, J.; Demappa, T.; Mahadevaiah

    2013-02-01

    Solid polymer electrolyte films based on Hydroxypropylmethylcellulose (HPMC) complexed with Sodium Iodide (NaI) were prepared using solution cast method. The dissolution of the salt into the polymer host and the micro structural properties of pure and NaI complexed HPMC polymer electrolyte films were confirmed by X - Ray diffraction (XRD) studies. The XRD results revealed that the amorphous domains of HPMC polymer matrix was increased with increase in the NaI salt concentration. The degree of crystallanity and crystallite size is high for pure HPMC samples. Direct current (dc) conductivity was measured in the temperature range of 313-383k. Temperature dependence of dc electrical conductivity and activation energy regions data indicated the dominance of ion type charge transport in these polymer electrolyte films.

  19. Effect of Zirconium Oxide Nanofiller and Dibutyl Phthalate Plasticizer on Ionic Conductivity and Optical Properties of Solid Polymer Electrolyte

    PubMed Central

    Yasin, Siti Mariah Mohd; Ibrahim, Suriani

    2014-01-01

    New solid polymer electrolytes (SPE) based on poly(ethylene oxide) (PEO) doped with lithium trifluoromethanesulfonate (LiCF3SO3), dibutyl phthalate (DBP) plasticizer, and zirconium oxide (ZrO2) nanoparticles were prepared by solution-casting technique. The conductivity was enhanced by addition of dibutyl phthalate (DBP) plasticizer and ZrO2 nanofiller with maximum conductivity (1.38 × 10−4 Scm−1). The absorption edge and band gap values showed decreases upon addition of LiSO3CF3, DBP, and ZrO2 due to the formation of localized states in the SPE and the degree of disorder in the films increased. PMID:25133244

  20. Strong tendency of homeotropic alignment and anisotropic lithium ion conductivity of sulfonate functionalized zwitterionic imidazolium ionic liquid crystals.

    PubMed

    Rondla, Rohini; Lin, Joseph C Y; Yang, C T; Lin, Ivan J B

    2013-09-17

    Here, we report the first attempt to investigate the liquid crystal (LC) behavior of SO3(-) functionalized imidazolium zwitterionic (SO3(-)ImZI) salts, which display homeotropic alignment on a glass slide without the aid of any aligning approach. Doping lithium salt to ImZI salts lowers the melting temperatures and raises the clearing temperatures substantially to form room temperature ImZILCs. Excellent anisotropic lithium ion conductivity is achieved; which is strengthened by their tendency for homeotropic alignment.

  1. Effects of TiO2 addition on ionic conductivity of PVC/PEMA blend based composite polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Subban, R. H. Y.; Sukri, Nursyazwani

    2015-08-01

    PVC/PEMA blend based polymer electrolytes with lithium bistrifluoromethane sulfonimide (LiN(CF3SO2)2) and PVC/PEMA/(LiN(CF3SO2)2-TiO2 films were prepared by solution cast technique. The sample containing 35 wt. % LiN(CF3SO2)2 exhibited the highest conductivity of 1.75 × 10-5 Scm-1. The conductivity of the sample increased to 2.12 × 10-5 Scm-1 and 4.61 × 10-5 Scm-1 when 4 wt. % and 10 wt. % of titanium dioxide (TiO2) was added to the sample at 65 wt. % PVC/PEMA-35 wt. % LiN(CF3SO2)2 composition respectively. The low increase in conductivity is attributed to two competing factors: increase in crystallinity as accounted by X-Ray diffraction (XRD) and decrease in glass transition temperature as accounted by differential scanning calorimetry (DSC).

  2. Effects of TiO{sub 2} addition on ionic conductivity of PVC/PEMA blend based composite polymer electrolyte

    SciTech Connect

    Subban, R. H. Y.; Sukri, Nursyazwani

    2015-08-28

    PVC/PEMA blend based polymer electrolytes with lithium bistrifluoromethane sulfonimide (LiN(CF{sub 3}SO{sub 2}){sub 2}) and PVC/PEMA/(LiN(CF{sub 3}SO{sub 2}){sub 2}-TiO{sub 2} films were prepared by solution cast technique. The sample containing 35 wt. % LiN(CF{sub 3}SO{sub 2}){sub 2} exhibited the highest conductivity of 1.75 × 10{sup −5} Scm{sup −1}. The conductivity of the sample increased to 2.12 × 10{sup −5} Scm{sup −1} and 4.61 × 10{sup −5} Scm{sup −1} when 4 wt. % and 10 wt. % of titanium dioxide (TiO{sub 2}) was added to the sample at 65 wt. % PVC/PEMA-35 wt. % LiN(CF{sub 3}SO{sub 2}){sub 2} composition respectively. The low increase in conductivity is attributed to two competing factors: increase in crystallinity as accounted by X-Ray diffraction (XRD) and decrease in glass transition temperature as accounted by differential scanning calorimetry (DSC)

  3. ARTICLE Ionic Conduction and Fuel Cell Performance of Ba0.98Ce0.8Tm0.2O3-α Ceramic

    NASA Astrophysics Data System (ADS)

    Qiu, Li-gan; Wang, Mao-yuan

    2010-12-01

    The perovskite-type oxide solid solution Ba0.98Ce0.8Tm0.2O3-α was prepared by high temperature solid-state reaction and its single phase character was confirmed by X-ray diffraction. The conduction property of the sample was investigated by alternating current impedance spectroscopy and gas concentration cell methods under different gases atmospheres in the temperature range of 500-900°C. The performance of the hydrogen-air fuel cell using the sample as solid electrolyte was measured. In wet hydrogen, the sample is a pure protonic conductor with the protonic transport number of 1 in the range of 500-600 °C, a mixed conductor of proton and electron with the protonic transport number of 0.945-0.933 above 600 °C. In wet air, the sample is a mixed conductor of proton, oxide ion, and electronic hole. The protonic transport numbers are 0.010-0.021, and the oxide ionic transport numbers are 0.471-0.382. In hydrogen-air fuel cell, the sample is a mixed conductor of proton, oxide ion and electron, the ionic transport numbers are 0.942-0.885. The fuel cell using Ba0.98Ce0.8Tm0.2O3-α as solid electrolyte can work stably. At 900 °C, the maximum power output density is 110.2 mW/cm2, which is higher than that of our previous cell using BaxCe0.8RE0.2O3-α (x<=1, RE=Y, Eu, Ho) as solid electrolyte.

  4. Correlation of the properties of ionic conductivity-structure for the RbGaO2 solid electrolyte

    NASA Astrophysics Data System (ADS)

    Proskurnina, N. V.; Voronin, V. I.; Berger, I. F.; Shekhtman, G. Sh.

    2016-12-01

    The crystal structure of rubidium gallate RbGaO2 in the temperature range of 300-853 K has been investigated using high-temperature neutron diffraction. The channels available for the motion of rubidium cations in the low-temperature and high-temperature modifications of RbGaO2 have been determined using the computer simulation with the TOPOS program. A correlation between the radius of the migration channel cross section and the rubidium cation conductivity has been established.

  5. Silver diffusion and ionic conduction in Ag/sub 6/I/sub 4/WO/sub 4/ solid electrolyte

    SciTech Connect

    Vlasov, Yu.G.; Ermolenko, Yu.E.; Glazunov, S.V.; Kolodnikov, V.V.

    1987-08-01

    This paper studies the diffusion of silver (Ag/sup 110m/) and the Haven ratio found for the first time at temperatures between 110 and 190/sup 0/C. A mixture of the salts AgI and Ag/sub 2/WO/sub 4/ (molar ratio) was obtained by joint precipitation with silver nitrate from solutions containing stoichiometric amounts of sodium iodide and tungstate. The conductivity and diffusion of the silver radiotracer Ag/sup 110m/ in solid electrolytes of the alpha-AgI type are measured. The activity distributions in the samples after homogenizing and the temperature dependence of the diffusion coefficients are shown.

  6. 12-crown-4 ether-assisted enhancement of ionic conductivity and interfacial kinetics in polyethylene oxide electrolytes

    NASA Technical Reports Server (NTRS)

    Nagasubramanian, G.; Di Stefano, S.

    1990-01-01

    The electrical and electrochemical properties of thin films of polyethylene oxide electrolytes with and without 12-crown-4 ether (12Cr4) are studied as a function of temperature and in the frequency regime from 100 kHz to 0.1 Hz. These measurements were made on electrolytes containing LiCF3SO3, LiBF4, or LiClO4 salts. At a given temperature, the bulk conductivity for a particular salt depends on the 12Cr4 concentration, reaching a maximum for a ratio of 12Cr4 to Li of 0.003.

  7. 12-crown-4 ether-assisted enhancement of ionic conductivity and interfacial kinetics in polyethylene oxide electrolytes

    NASA Technical Reports Server (NTRS)

    Nagasubramanian, G.; Di Stefano, S.

    1990-01-01

    The electrical and electrochemical properties of thin films of polyethylene oxide electrolytes with and without 12-crown-4 ether (12Cr4) are studied as a function of temperature and in the frequency regime from 100 kHz to 0.1 Hz. These measurements were made on electrolytes containing LiCF3SO3, LiBF4, or LiClO4 salts. At a given temperature, the bulk conductivity for a particular salt depends on the 12Cr4 concentration, reaching a maximum for a ratio of 12Cr4 to Li of 0.003.

  8. Effects of 12-Crown-4 ether on the ionic conductivity and electrode kinetics of electrolytes in polyethylene oxide

    NASA Technical Reports Server (NTRS)

    Nagasubramanian, G.; Di Stefano, S.

    1990-01-01

    Results are described of investigations of the electrical and electrochemical properties of thin films of polyethylene oxide (PEO) electrolytes with and without 12-Crown-4 ether (12Cr4) as a function of temperature and in the frequency regime 100 kHz-0.1 Hz. These measurements were made for LiCF3SO3, LiBF4, and LiClO4 salts. At a given temperature, the bulk conductivity, sigma, (S/cm), for a particular salt, depends on the 12Cr4 concentration with sigma reaching a maximum at about 3 mM 12Cr4. Of the three salts studied, the sigma is the highest for PEO/LiBF4 with 3 mM 12Cr4. The ac and dc measurements yield a lower charge transfer resistance for 12Cr4-incorporated samples than for samples without. Plating/stripping of Li occurs at a potential closer to Li(+)/Li for 12Cr4 samples than those without. The conductivities of a thin (about 100 microns) and a thick (400 microns) films are similar.

  9. Effects of 12-Crown-4 ether on the ionic conductivity and electrode kinetics of electrolytes in polyethylene oxide

    NASA Astrophysics Data System (ADS)

    Nagasubramanian, G.; di Stefano, S.

    Results are described of investigations of the electrical and electrochemical properties of thin films of polyethylene oxide (PEO) electrolytes with and without 12-Crown-4 ether (12Cr4) as a function of temperature and in the frequency regime 100 kHz-0.1 Hz. These measurements were made for LiCF3SO3, LiBF4, and LiClO4 salts. At a given temperature, the bulk conductivity, sigma, (S/cm), for a particular salt, depends on the 12Cr4 concentration with sigma reaching a maximum at about 3 mM 12Cr4. Of the three salts studied, the sigma is the highest for PEO/LiBF4 with 3 mM 12Cr4. The ac and dc measurements yield a lower charge transfer resistance for 12Cr4-incorporated samples than for samples without. Plating/stripping of Li occurs at a potential closer to Li(+)/Li for 12Cr4 samples than those without. The conductivities of a thin (about 100 microns) and a thick (400 microns) films are similar.

  10. Synthesis and characterization of cancrinite-type zeolite, and its ionic conductivity study by AC impedance analysis

    NASA Astrophysics Data System (ADS)

    Kriaa, A.; Ben Saad, K.; Hamzaoui, A. H.

    2012-12-01

    The synthesis of cancrinite in the system NaOH-SiO2-Al2O3-NaHCO3-H2O was performed, according to methods described in the literature, in an autoclave under hydrothermal conditions at T = 473 K. The electrical properties of cancrinite-type zeolite pellets were investigated by complex impedance spectroscopy in the temperature range 465-800°C. The effect of temperature on impedance parameters was studied using an impedance analyzer in a wide frequency range (1 Hz to 13 MHz). The real and imaginary parts of complex impedance trace semicircles in the complex plane are plotted. The bulk resistance of the material decreases with rise in temperature. This exhibits a typical negative temperature coefficient of resistance (NTCR) behavior of the material. The results of bulk electrical conductivity and its activation energy are presented. The modulus analysis suggests that the electrical transport processes in the material are very likely to be of electronic nature. Relaxation frequencies follow an Arrhenius behavior with activation energy values not comparable to those found for the electrical conductivity.

  11. Effects of 12-Crown-4 ether on the ionic conductivity and electrode kinetics of electrolytes in polyethylene oxide

    NASA Technical Reports Server (NTRS)

    Nagasubramanian, G.; Di Stefano, S.

    1990-01-01

    Results are described of investigations of the electrical and electrochemical properties of thin films of polyethylene oxide (PEO) electrolytes with and without 12-Crown-4 ether (12Cr4) as a function of temperature and in the frequency regime 100 kHz-0.1 Hz. These measurements were made for LiCF3SO3, LiBF4, and LiClO4 salts. At a given temperature, the bulk conductivity, sigma, (S/cm), for a particular salt, depends on the 12Cr4 concentration with sigma reaching a maximum at about 3 mM 12Cr4. Of the three salts studied, the sigma is the highest for PEO/LiBF4 with 3 mM 12Cr4. The ac and dc measurements yield a lower charge transfer resistance for 12Cr4-incorporated samples than for samples without. Plating/stripping of Li occurs at a potential closer to Li(+)/Li for 12Cr4 samples than those without. The conductivities of a thin (about 100 microns) and a thick (400 microns) films are similar.

  12. Insertion-release of guest species and ionic conduction in polyoxometalate solids with a layer-like Anderson structure

    SciTech Connect

    Naruke, Haruo; Kajitani, Naoyuki; Konya, Takayuki

    2011-04-15

    The precipitation of Na{sup +} and K{sup +} mixed salts of Anderson type [SbW{sub 6}O{sub 24}]{sup 7-} by addition of excess of NaNO{sub 3} and NaCl yielded polycrystalline powders of Na{sub 2.5}K{sub 5.3}[SbW{sub 6}O{sub 24}](NO{sub 3}){sub 0.8}.12H{sub 2}O (1) and Na{sub 2}K{sub 5.35}[SbW{sub 6}O{sub 24}]Cl{sub 0.35}.12H{sub 2}O (2), respectively. The two compounds are isomorphous and exhibit a layer-like Anderson (LLA) type structure, which consists of [SbW{sub 6}O{sub 24}]{sup 7-}-containing layers and interstitial Na{sup +}, K{sup +}, NO{sub 3}{sup -} or Cl{sup -}, and water O atoms. Recrystallization of 1 and 2 from hot water yielded Na{sub 2}K{sub 5.4}[SbW{sub 6}O{sub 24}](NO{sub 3}){sub 0.4}.12H{sub 2}O (1-recry) and Na{sub 2}K{sub 5.25}[SbW{sub 6}O{sub 24}]Cl{sub 0.25}.12H{sub 2}O (2-recry) as a result of partial release of NO{sub 3}{sup -} and Cl{sup -} (and Na{sup +} and K{sup +} for charge compensation). Dehydration of 1 and 2 at 400 and 500 {sup o}C (1-dehyd400 and 2-dehyd500) caused a shrinkage of lattice, but their the LLA structures retained. Simulation of X-ray diffraction (XRD) patterns for the dehydrated forms allowed to presume that the each [SbW{sub 6}O{sub 24}]{sup 7-} anion had been 30{sup o}-rotated within its molecular plane in order to avoid intermolecular repulsion. A compressed powder of 1-dehyd400 exhibited fast alkaline-ion conduction with a bulk conductivity of 1.2x10{sup -2} {Omega}{sup -1} cm{sup -1} at 400 {sup o}C. The hosting of a sufficient amount of NO{sub 3}{sup -} together with Na{sup +} for charge compensation into the lattice is crucial for high conduction. -- Graphical abstract: Two compounds Na{sub 2.5}K{sub 5.3}[SbW{sub 6}O{sub 24}](NO{sub 3}){sub 0.8}.12H{sub 2}O (1) and Na{sub 2}K{sub 5.35}[SbW{sub 6}O{sub 24}]Cl{sub 0.35}.12H{sub 2}O (2) possessing a layer-like Anderson (LLA) structure exhibited pseudo intercalation-deintercalation behavior. The dehydrated form of 1 is a high alkaline cation conductor with a

  13. Conductance simulation of the purinergic P2X2, P2X4, and P2X7 ionic channels using a combined Brownian dynamics and molecular dynamics approach.

    PubMed

    Turchenkov, Dmitry A; Bystrov, Vladimir S

    2014-08-07

    This paper investigates the application of an original combined approach of molecular and Brownian dynamic methods with quantum chemistry calculations for modeling the process of conductance of ion channels using purinergic P2X family receptors P2X2, P2X4, and P2X7 as a case study. A simplified model of the ionic channel in the lipid bilayer has been developed. A high level of conductance (30 pS) of P2X2 ionic channel together with the key role of Asp349 in forming the selectivity filter of P2X2 has been shown by using this approach. Calculated P2X2 permeability to monovalent cations Li(+), Na(+), and K(+) conforms to the free diffusion coefficient of these ions, which shows the low selectivity of P2X2 ionic channel.

  14. Influence of temperature and frequency on ionic conductivity of Li{sub 3}PO{sub 4}–Pb{sub 3}(PO{sub 4}){sub 2}–BiPO{sub 4} phosphate glasses

    SciTech Connect

    El Moudane, M.; El Maniani, M.; Sabbar, A.; Ghanimi, A.; Tabyaoui, M.; Bellaouchou, A.; Guenbour, A.

    2015-12-15

    Highlights: • Results of ionic conductivities of Li{sub 3}PO{sub 4}–Pb{sub 3}(PO{sub 4}){sub 2}–BiPO{sub 4} phosphate glasses. • Determination of glass transition temperature using DSC method. • Study of temperature and frequency on ionic conductivity of Li{sub 3}PO{sub 4}–Pb{sub 3}(PO{sub 4}){sub 2}–BiPO{sub 4} phosphate glasses. - Abstract: Lithium–Lead–Bismuth phosphates glasses having, a composition 30Li{sub 3}PO{sub 4}–(70 − x)Pb{sub 3}(PO{sub 4}){sub 2}–xBiPO{sub 4} (45 ≤ x ≤ 60 mol%) were prepared by using the melt quenching method 1000 °C. The thermal stability of theses glasses increases with the substitution of Bi{sub 2}O{sub 3} with PbO. The ionic conductivity of all compositions have been measured over a wide temperature (200–500 °C) and frequency range (1–106 Hz). The ionic conductivity data below and above T{sub g} follows Arrhenius and Vogel–Tamman–Fulcher (VTF) relationship, respectively. The activation energies are estimated and discussed. The dependence in frequency of AC conductivity is found to obey Jonscher’s relation.

  15. Integrated study of first principles calculations and experimental measurements for Li-ionic conductivity in Al-doped solid-state LiGe2(PO4)3 electrolyte

    NASA Astrophysics Data System (ADS)

    Kang, Joonhee; Chung, Habin; Doh, Chilhoon; Kang, Byoungwoo; Han, Byungchan

    2015-10-01

    Understanding of the fundamental mechanisms causing significant enhancement of Li-ionic conductivity by Al3+ doping to a solid LiGe2(PO4)3 (LGP) electrolyte is pursued using first principles density functional theory (DFT) calculations combined with experimental measurements. Our results indicate that partial substitution Al3+ for Ge4+ in LiGe2(PO4)3 (LGP) with aliovalent (Li1+xAlxGe2-x(PO4)3, LAGP) improves the Li-ionic conductivity about four-orders of the magnitude. To unveil the atomic origin we calculate plausible diffusion paths of Li in LGP and LAGP materials using DFT calculations and a nudged elastic band method, and discover that LAGP had additional transport paths for Li with activation barriers as low as only 34% of the LGP. Notably, these new atomic channels manifest subtle electrostatic environments facilitating cooperative motions of at least two Li atoms. Ab-initio molecular dynamics predict Li-ionic conductivity for the LAGP system, which is amazingly agreed experimental measurement on in-house made samples. Consequently, we suggest that the excess amounts of Li caused by the aliovalent Al3+ doping to LGP lead to not only enhancing Li concentration but also opening new conducting paths with substantially decreases activation energies and thus high ionic conductivity of LAGP solid-state electrolyte.

  16. What can we learn from ionic conductivity measurements in polymer electrolytes? A case study on poly(ethylene oxide) (PEO)-NaI and PEO-LiTFSI.

    PubMed

    Stolwijk, Nicolaas A; Wiencierz, Manfred; Heddier, Christian; Kösters, Johannes

    2012-03-15

    We explore in detail what information on ionic diffusivity and ion pairing can be exclusively gained from combining accurate direct-current conductivity data in polymer electrolytes with a novel evaluation model. The study was performed on two prototype systems based on poly(ethylene oxide) (PEO) with known disparate ion-association properties, which are due to the dissimilar salt components being either sodium iodide (NaI) or lithium bis(trifluoromethane-sulfonyl)imide (LiN(CF(3)SO(2))(2) or LiTFSI). The temperature dependence of the conductivity can be described by an extended Vogel-Tammann-Fulcher (VTF) equation, which involves a Boltzmann factor containing the pair-formation enthalpy ΔH(p). We find a distinct increase of the positive ΔH(p) values with decreasing salt concentration and similarly clear trends for the pertinent VTF parameters. The analysis further reveals that PEO-NaI combines a high pair fraction with a high diffusivity of the I(-) ion. By contrast, PEO-LiTFSI appears to be characterized by a low ion-pairing tendency and a relatively low mobility of the bulky TFSI(-) ion. The observed marked differences between PEO-NaI and PEO-LiTFSI complexes of homologous composition are most pronounced at high temperatures and low salt concentrations. © 2012 American Chemical Society

  17. Materials space of solid-state electrolytes: unraveling chemical composition-structure-ionic conductivity relationships in garnet-type metal oxides using cheminformatics virtual screening approaches.

    PubMed

    Kireeva, Natalia; Pervov, Vladislav S

    2017-08-09

    The organic electrolytes of most current commercial rechargeable Li-ion batteries (LiBs) are flammable, toxic, and have limited electrochemical energy windows. All-solid-state battery technology promises improved safety, cycling performance, electrochemical stability, and possibility of device miniaturization and enables a number of breakthrough technologies towards the development of new high power and energy density microbatteries for electronics with low processing cost, solid oxide fuel cells, electrochromic devices, etc. Currently, rational materials design is attracting significant attention, which has resulted in a strong demand for methodologies that can accelerate the design of materials with tailored properties; cheminformatics can be considered as an efficient tool in this respect. This study was focused on several aspects: (i) identification of the parameters responsible for high Li-ion conductivity in garnet structured oxides; (ii) development of quantitative models to elucidate composition-structure-Li ionic conductivity relationships, taking into account the experimental details of sample preparation; (iii) circumscription of the materials space of solid garnet-type electrolytes, which is attractive for virtual screening. Several candidate compounds have been recommended for synthesis as potential solid state electrolyte materials.

  18. Ionic conductivity measurements of H2O ice at high pressure and temperature and superionic ice in the mantle of ice giants

    NASA Astrophysics Data System (ADS)

    Sugimura, E.; Komabayashi, T.; Ohta, K.; Hirose, K.; Sata, N.; Ohishi, Y.; Shimizu, K.; Dubrovinsky, L. S.

    2011-12-01

    The experimental evidence for the superionic conduction in H2O ice at high pressure (P) and temperature (T) has been long-searched since its theoretical prediction. Melting experiments reported a steep rise of the melting curve at P-T range of 35-43 GP and 1000-1600 K, which could be due to a first-order phase transition in the solid phases, namely the presence of the triple point of water, ice VII, and a high-T phase which was assumed superionic. Nonetheless, there has still been no report on direct experimental evidence for superionic conduction (ca. 0.1 S/cm) in ice at high pressure. Here we examined ionic conductivity and isothermal molar volume of ice at high-P-T based on impedance spectroscopy (IS) and x-ray diffraction measurements in an externally-resistive heated diamond anvil cell. In situ IS measurements up to 62 GPa and 920 K demonstrated that ice exhibits superionic conduction (> 0.1 S/cm) above 580-720 K at 20-60 GPa. This suggests that superionic conduction occurs at sufficiently lower P-T than the triple point. Isothermal P-V data collected at P = 33-101 GPa and T = 873 K revealed that an anomalous volume reduction occurs at P = 50-53 GPa. This compression manner corresponds to the previously reported highly compressible regime at P = 40-60 GPa, T = 300 K, which were attributed to hydrogen bond symmetrization. There is no volume discontinuity in the isothermal compression, which contradicts the proposed first order P-T boundary between ice VII and superionic ice. Furthermore, all the conductivity data is expressed by a single Arrhenius equation so that the superionic conduction occurs regardless of the ongoing hydrogen bond symmetrization upon compression. We suggests that the previously reported steep rise of the melting temperature of ice above 35-43 GPa is independent of superionic transition, and is a consequence of the hydrogen bond symmetrization. Combining above results with the existing planetary isentropes, superionic conduction in H2O ice

  19. Three-dimensional stable lithium metal anode with nanoscale lithium islands embedded in ionically conductive solid matrix.

    PubMed

    Lin, Dingchang; Zhao, Jie; Sun, Jie; Yao, Hongbin; Liu, Yayuan; Yan, Kai; Cui, Yi

    2017-05-02

    Rechargeable batteries based on lithium (Li) metal chemistry are attractive for next-generation electrochemical energy storage. Nevertheless, excessive dendrite growth, infinite relative dimension change, severe side reactions, and limited power output severely impede their practical applications. Although exciting progress has been made to solve parts of the above issues, a versatile solution is still absent. Here, a Li-ion conductive framework was developed as a stable "host" and efficient surface protection to address the multifaceted problems, which is a significant step forward compared with previous host concepts. This was fulfilled by reacting overstoichiometry of Li with SiO. The as-formed LixSi-Li2O matrix would not only enable constant electrode-level volume, but also protect the embedded Li from direct exposure to electrolyte. Because uniform Li nucleation and deposition can be fulfilled owing to the high-density active Li domains, the as-obtained nanocomposite electrode exhibits low polarization, stable cycling, and high-power output (up to 10 mA/cm(2)) even in carbonate electrolytes. The Li-S prototype cells further exhibited highly improved capacity retention under high-power operation (∼600 mAh/g at 6.69 mA/cm(2)). The all-around improvement on electrochemical performance sheds light on the effectiveness of the design principle for developing safe and stable Li metal anodes.

  20. Concentration dependence of ionic conductance measured with ion-selective sub-micro pipette probes in aqueous sodium and potassium chloride solutions

    NASA Astrophysics Data System (ADS)

    Son, J. W.; Takami, T.; Lee, J.-K.; Kawai, T.; Park, B. H.

    2011-07-01

    Selective ionic currents in aqueous sodium and potassium chloride solutions with concentrations from 0.01 M to 1.0 M were measured using sub-micro pipette probes in which a poly(vinyl chloride) film containing crown ethers selectively filtered sodium or potassium ions. The selective ionic currents were monitored with a sub-picoampere current measurement system developed from the techniques of TΩ-gap impedance scanning tunneling microscopy. The ionic currents increased with the concentration of the corresponding solution, and thus these sub-micro pipette probes can be applied to detect local ionic concentration of a specific ion in living cells with ionic concentration higher than 0.1 M.

  1. Li4Ti5O12 composited with Li2ZrO3 revealing simultaneously meliorated ionic and electronic conductivities as high performance anode materials for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Han, Jian-Ping; Zhang, Bo; Bai, Xue; Wang, Li-Ying; Qi, Yong-Xin; Lun, Ning; Bai, Yu-Jun

    2017-06-01

    Li4Ti5O12 (LTO) is inherently a poor ionic and electronic conductor, and the modification methods available could solely meliorate either ionic or electronic conductivity. In order to simultaneously improve both the ionic and electronic conductivities, LTO was composited with Li2ZrO3 accompanying with superficial Zr4+ doping by the simple reaction between Zr(NO3)4·5H2O and LiNO3 on the LTO surface. From the comparative experiments, the as-modified LTO with a Li2ZrO3/LTO mass ratio of 0.009 and sintered at 750 °C exhibits the most excellent rate performance (achieving capacities of 155.3, 149.6, 145.4, 139.6, 130.2 and 153.2 mAh g-1 at 100, 200, 400, 800, 1600 and 100 mA g-1, respectively) and long-term cyclability (retaining a capacity of 102 mAh g-1 after the 2000th cycle at 500 mA g-1). By the detailed structural characterization and electrochemical impedance spectra analysis, the formation of the tetragonal Li2ZrO3 with good ionic conductivity and the superficial Zr4+ doping with improved electronic conductivity is responsible for the markedly enhanced cycling and rate performance of LTO.

  2. The use of 6Li{7Li}-REDOR NMR spectroscopy to compare the ionic conductivities of solid-state lithium ion electrolytes.

    PubMed

    Spencer, T L; Plagos, N W; Brouwer, D H; Goward, G R

    2014-02-14

    Garnet-like solid-state electrolyte materials for lithium ion batteries are promising replacements for the currently-used liquid electrolytes. This work compares the temperature dependent Li(+) ion hopping rate in Li6BaLa2M2O12 (M = Ta, Nb) using solid-state (6)Li{(7)Li}-REDOR NMR. The slope of the (6)Li{(7)Li}-REDOR curve is highly temperature dependent in these two phases, and a comparison of the changes of the REDOR slopes as a function of temperature has been used to evaluate the Li(+) ion dynamics. Our results indicate that the Nb phase has a higher overall ionic conductivity in the range of 247 K to 350 K, as well as a higher activation energy for lithium ion hopping than the Ta counterpart. For appropriate relative timescales of the dipolar couplings and ion transport processes, this is shown to be a facile method to compare ion dynamics among similar structures.

  3. Modeling of Ionic Conductivity Enhancement of LiClO4-PVA-C System by TiO2 Addition Using Complex Numerical Model of PDE

    NASA Astrophysics Data System (ADS)

    Shokrollahi, Mahvash; Semnani, Dariush; Morshed, Mohammad; Rezaei, Behzad; Mirsoofian, Mehdi

    2013-12-01

    PVA-TiO2 nanocomposite polymer electrolytes (PEs) were produced with different amounts of TiO2 (0, 5, 10, 15, and 20 wt.%) using the electrospinning process. Morphological studies of PVA-TiO2 nanofibers were accomplished with SEM. PVA-TiO2 membranes exhibited a high porosity of 79-91%. The impedance results showed that incorporation of TiO2 into the nanofiber membrane improved its ionic conductivity from 0.7 × 10-5 to 2.5 × 10-5 S/cm at room temperature. Nanofiber PEs showed very good reversibility and electrochemical stability up to 4.7 V. Diffusion coefficient of Li ion into PVA-TiO2 nanocomposite PEs was estimated by using a complex numerical model of partial differential equation for evaluation of ion transmission. Diffusion coefficient of PVA-TiO2 PEs containing different amounts of TiO2 (0, 5, 10, 15, and 20 wt.%) increased with increasing the nanoparticles content.

  4. Microemulsions with surfactant TX100, cyclohexane, and an ionic liquid investigated by conductance, DLS, FTIR measurements, and study of solvent and rotational relaxation within this microemulsion.

    PubMed

    Pramanik, Rajib; Sarkar, Souravi; Ghatak, Chiranjib; Rao, Vishal Govind; Setua, Palash; Sarkar, Nilmoni

    2010-06-10

    Room-temperature ionic liquids (RTILs), N,N,N-trimethyl-N-propyl ammonium bis(trifluoromethanesulfonyl) imide ([N(3111)][Tf(2)N]), were substituted for polar water and formed nonaqueous microemulsions with cyclohexane by the aid of nonionic surfactant TX-100. The phase behavior of the ternary system was investigated, and microregions of [N(3111)][Tf(2)N]-in-cyclohexane (IL/O), bicontinuous, and cyclohexane-in-[N(3111)][Tf(2)N] (O/IL) were identified by traditional electrical conductivity measurements. Dynamic light scattering (DLS) revealed the formation of the IL microemulsions. The FTIR study of O-H stretching band of TX100 also supports this finding. The dynamics of solvent and rotational relaxation have been investigated in [N(3111)][Tf(2)N]/TX100/cyclohexane microemulsions using steady-state and time-resolved fluorescence spectroscopy as a tool and coumarin 480 (C-480) as a fluorescence probe. The size of the microemulsions increases with gradual addition of [N(3111)][Tf(2)N], which revealed from DLS measurement. This leads to the faster collective motions of cation and anions of [N(3111)][Tf(2)N], which contributes to faster solvent relaxation in microemulsions.

  5. Conductive Polymeric Ionic Liquid/Fe3O4 Nanocomposite as an Efficient Catalyst for the Voltammetric Determination of Amlodipine Besylate.

    PubMed

    Fathirad, Fariba; Mostafavi, Ali; Afzali, Daryoush

    2017-03-01

    A novel conductive polymeric ionic liquid (IL)-Fe3O4 nanocomposite (represented as PIL-Fe3O4) based on inorganic-organic hybrid material was synthesized using two different methods. Nuclear magnetic resonance, Fourier transform infrared, X-ray diffraction, and field emission scanning electron microscopy characterized the structures of IL, Fe3O4 nanoparticles, and PIL-Fe3O4. The electrochemical sensors based on PIL-Fe3O4-modified glassy carbon electrode were fabricated, and each of these nanocomposites was examined for the ability to determine amlodipine besylate (AMD). The electrochemical study of the modified electrodes, as well as its efficiency for the electro-oxidation of AMD, was described in 0.1 M phosphate-buffered solution (pH 7.0) using voltammetric methods. The results exhibit a linear dynamic range from 1 to 500 nM and a detection limit of 0.36 nM. Finally, the modified electrode was used for the determination of AMD in pharmaceutical and biological samples.

  6. Synthesis of conductive polymeric ionic liquid/Ni nanocomposite and its application to construct a nanostructure based electrochemical sensor for determination of warfarin in the presence of tramadol.

    PubMed

    Molaakbari, Elaheh; Mostafavi, Ali; Beitollahi, Hadi; Tohidiyan, Zeinab

    2017-08-15

    In the current study, poly(MImEO8BS)-Ni nanocomposite was synthesized and applied to modify a glassy carbon electrode along with conductive polymeric ionic liquids. The electrochemical investigation of the modified electrode as well as its efficiency for voltammetric oxidation of warfarin is elucidated. The electrode was used to study the voltammetric oxidation of warfarin by employing cyclic voltammetry (CV), linear sw