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Showing papers on "Ionic conductivity published in 2008"


Journal ArticleDOI
TL;DR: In the last 30 years, research efforts by the scientific community intensified significantly, stemming from the pioneering work of Takahashi and co-workers, with the initial development of mixed ionic-electronic conducting (MIEC) oxides.

1,037 citations


Journal ArticleDOI
01 Aug 2008-Science
TL;DR: It is proposed that the atomic reconstruction at the interface between highly dissimilar structures (such as fluorite and perovskite) provides both a large number of carriers and a high-mobility plane, yielding colossal values of the ionic conductivity.
Abstract: The search for electrolyte materials with high oxygen conductivities is a key step toward reducing the operation temperature of fuel cells, which is currently above 700 degrees C. We report a high lateral ionic conductivity, showing up to eight orders of magnitude enhancement near room temperature, in yttria-stabilized zirconia (YSZ)/strontium titanate epitaxial heterostructures. The enhancement of the conductivity is observed, along with a YSZ layer thickness-independent conductance, showing that it is an interface process. We propose that the atomic reconstruction at the interface between highly dissimilar structures (such as fluorite and perovskite) provides both a large number of carriers and a high-mobility plane, yielding colossal values of the ionic conductivity.

680 citations


Journal ArticleDOI
TL;DR: Ionic liquids (ILs) are ambient temperature molten salts and have attracted considerable attention because of their unique properties such as nonflammability, negligible volatility, high ionic conductivity, and thermal stability.
Abstract: Ionic liquids (ILs) are ambient temperature molten salts and have attracted considerable attention because of their unique properties such as nonflammability, negligible volatility, high ionic conductivity, and thermal stability. Here, we show that the combinations of macromolecules with ILs as solvents and additives could offer new progress, challenges, and opportunities in polymer materials science. Compatible binary systems, where ILs are solidified (gelled) by polymers, can be used as ion-conducting polymer electrolytes (ion gels). The ion transport in ion gels is found to be decoupled from the segmental motion of the polymers, leading to relatively high ionic conductivities even at their glass transition temperatures. The flexibility of the molecular design of ILs allows us to prepare many new ILs having electrochemical functionalities such as proton, electron, and lithium ion transport. The new ILs and their ion gels appear to be promising candidates as new materials for electrochemical applications...

565 citations


Journal ArticleDOI
TL;DR: In this article, the interfaces between LiCoO 2 and sulfide solid electrolytes were modified in order to enhance the high-rate capability of solid-state lithium batteries, and buffer layers of LiNbO 3 and LiTaO 3 can be formed at low temperature for the interfacial modification, because they show high ionic conduction in their amorphous states.

272 citations


Journal ArticleDOI
TL;DR: The survey highlights the problems with voltammetric studies in highly viscous room temperature protic ionic liquids and also suggests the way forward with respect to their possible industrial use.
Abstract: Eighteen protic ionic liquids containing different combinations of cations and anions, hydrophobicity, viscosity, and conductivity have been synthesized and their physicochemical properties determined. In one series, the diethanolammonium cations were combined with acetate, formate, hydrogen sulfate, chloride, sulfamate, and mesylate anions. In the second series, acetate and formate anions were combined with amine bases, triethylamine, diethylamine, triethanolamine, di-n-propylamine, and di-n-butylamine. The electrochemical characteristics of the eight protic ionic liquids that are liquid at room temperature (RTPILs) have been determined using cyclic, microelectrode, and rotating disk electrode voltammetries. Potential windows of the RTPILs have been compared at glassy carbon, platinum, gold, and boron-doped diamond electrodes and generally found to be the largest in the case of glassy carbon. The voltammetry of IUPAC recommended potential scale reference systems, ferrocene/ferrocenium and cobaltocenium/cobaltocene, have been evaluated and found to be ideal in the case of the less viscous RTPILs but involve adsorption in the highly viscous ones. Other properties such as diffusion coefficients, ionic conductivity, and double layer capacitance also have been measured. The influence of water on the potential windows, viscosity, and diffusion has been studied systematically by deliberate addition of water to the dried ionic liquids. The survey highlights the problems with voltammetric studies in highly viscous room temperature protic ionic liquids and also suggests the way forward with respect to their possible industrial use.

256 citations


Journal ArticleDOI
TL;DR: In this paper, a dielectric loss spectra showed the presence of one relaxation for all compositions, which is associated with the motions of the Li ion coordinated polymer segments, and the relaxation has been characterized by the empirical Havriliak-Negami (H-N) equation.

250 citations


Journal ArticleDOI
TL;DR: Ta doping in Li4Ti5O12 (Li4Ti4.95Ta0.05O12) as function of different heat-treat atmospheres (oxidizing/reducing) was investigated as mentioned in this paper.

224 citations


Journal ArticleDOI
TL;DR: In this paper, a polymer electrolyte based on PVA doped with different concentrations of NH 4 Br has been prepared by solution casting technique and the complexation of the prepared polymer electrolytes has been studied using X-ray diffraction (XRD) and Fourier transform infra red (FTIR) spectroscopy.
Abstract: Polymer electrolyte based on PVA doped with different concentrations of NH 4 Br has been prepared by solution casting technique. The complexation of the prepared polymer electrolytes has been studied using X-ray diffraction (XRD) and Fourier transform infra red (FTIR) spectroscopy. The maximum ionic conductivity (5.7×10 −4 S cm −1 ) has been obtained for 25 mol% NH 4 Br-doped PVA polymer electrolyte. The temperature dependence of ionic conductivity of the prepared polymer electrolytes obeys Arrhenius law. The ionic transference number of mobile ions has been estimated by dc polarization method and the results reveal that the conducting species are predominantly ions. The dielectric behavior of the polymer electrolytes has been analyzed using dielectric permittivity and electric modulus spectra.

218 citations


Journal ArticleDOI
TL;DR: Molecular dynamics simulations showed that the coordination of Li+ by oxygen atoms of TFSI anions changes with Li+ concentration producing a remarkable change of the RTIL structure with a concomitant reduction of diffusion coefficients of all species in the solutions.
Abstract: Lithium salt solutions of Li(CF3SO2)2N, LiTFSI, in a room-temperature ionic liquid (RTIL), 1-butyl-2,3-dimethyl-imidazolium cation, BMMI, and the (CF3SO2)2N(-), bis(trifluoromethanesulfonyl)imide anion, [BMMI][TFSI], were prepared in different concentrations. Thermal properties, density, viscosity, ionic conductivity, and self-diffusion coefficients were determined at different temperatures for pure [BMMI][TFSI] and the lithium solutions. Raman spectroscopy measurements and computer simulations were also carried out in order to understand the microscopic origin of the observed changes in transport coefficients. Slopes of Walden plots for conductivity and fluidity, and the ratio between the actual conductivity and the Nernst-Einstein estimate for conductivity, decrease with increasing LiTFSI content. All of these studies indicated the formation of aggregates of different chemical nature, as it is corroborated by the Raman spectra. In addition, molecular dynamics (MD) simulations showed that the coordination of Li+ by oxygen atoms of TFSI anions changes with Li+ concentration producing a remarkable change of the RTIL structure with a concomitant reduction of diffusion coefficients of all species in the solutions.

216 citations


Journal ArticleDOI
TL;DR: The Haven ratio is calculated from the bulk ionic conductivity and the individual diffusion coefficients of cations and anions and the maximal apparent lithium transference number is higher than found in other recent studies on ionic liquid electrolytes containing lithium ions.
Abstract: spectroscopy and pulsed field gradient NMR Molar ratios x ) nLi-TFSI/(nLi-TFSI + nBMP-TFSI) up to 0377 could be achieved without crystallization From the bulk ionic conductivity and the individual diffusion coefficients of cations and anions we calculate the Haven ratio and the apparent lithium transference number Although the Haven ratio exhibits typical values for ionic liquid electrolytes, the maximal apparent lithium transference number is higher than found in other recent studies on ionic liquid electrolytes containing lithium ions On the basis of these results we discuss strategies for further improving the lithium transference number of such electrolytes

198 citations


Journal ArticleDOI
TL;DR: For the aggregation mechanism in [C 2 mim][NTf(2], the reaction-limited cluster aggregation (RLCA) model was proposed by rheology and light scattering measurements, and exciting viscoelastic responses were found in all of the nanocomposite ion gels.
Abstract: The dispersion of silica nanoparticles made an ionic liquid, 1-ethyl-3-methyl imidazolium bis(trifluoromethanesulfonyl)amide ([C2mim][NTf2]), gelled even by the addition of 2−3 wt %, due to the formation of interconnected particulate silica networks in [C2mim][NTf2]. The ionic transport and viscoelastic properties of these nanocomposite ion gels were investigated in relation to the microstructure. Despite their solid-like behavior, the nanocomposite ion gels exhibited a high ionic conductivity of approximately 10−2 S cm−1 at 30 °C, which is comparable to that of neat [C2mim][NTf2]. Intriguing viscoelastic responses, such as shear-thinning and shear-induced sol−gel transitions, were found in all of the nanocomposite ion gels. By adjusting the silica concentration, the elastic modulus (G′) could be precisely controlled in a range of more than 3 orders of magnitude and reached approximately 106 Pa without a considerable decrease in the ionic conductivity; the characteristic viscoelastic response was also mai...

Journal ArticleDOI
TL;DR: HRTEM studies show that the YSZ/Y(2)O(3) interfaces are semicoherent, and the correlation between interface structure and ionic conduction is discussed.
Abstract: The oxygen ion conductivity of YSZ (ZrO2 + 9.5 mol% Y2O3)/Y2O3 multilayer systems is measured parallel to the interfaces as a function of temperature between 350 and 700 °C. The multilayer samples are prepared by pulsed laser deposition (PLD). The film thicknesses, the crystallinity, the texture and the microstructure are investigated by SEM, XRD, HRTEM and SAED. To separate the interface contribution of the total conductivity from the bulk contribution the thickness of the YSZ and Y2O3 layers is varied systematically. The total conductivity of the YSZ films increases when their thickness is decreased from 0.53 μm to 24 nm. It depends linearly on the reciprocal thickness of the individual layers, thus on the number of YSZ/Y2O3 interfaces. This behaviour results from the parallel connection between individual conduction paths in the bulk and the interfacial regions. The activation energy for the ionic conductivity decreases from 1.13 to 0.99 kJ mol−1 by decreasing the thicknesses of the individual YSZ layers. HRTEM studies show that the YSZ/Y2O3 interfaces are semicoherent. The correlation between interface structure and ionic conduction is discussed.

Journal ArticleDOI
TL;DR: In this paper, the ionic and electronic conductivities as well as chemical Li-diffusivity in single crystalline LiFePO 4 as a function of crystallographic orientation over an extended temperature range were investigated.

Journal ArticleDOI
TL;DR: In this article, a polymer electrolyte membrane based on poly(vinylidenefluoride-hexafluoropropylene) (PVDF-HFP) was prepared by a phase inversion method.

Journal ArticleDOI
TL;DR: In this article, a co-doping strategy was used to enhance the ionic conductivity of doped ceria, and the lattice parameters were estimated after the detailed analysis of X-ray diffraction data using least-squares extrapolation technique.

Journal ArticleDOI
TL;DR: In this article, ammonium thiocyanate (NH4SCN) based polymer films with different compositions have been prepared by solution casting technique and the amorphous nature of the polymer electrolytes has been confirmed by XRD analysis.
Abstract: Poly (N-vinyl pyrrolidone) (PVP) and ammonium thiocyanate (NH4SCN) based polymer films with different compositions have been prepared by solution casting technique. The amorphous nature of the polymer electrolytes has been confirmed by XRD analysis. The FTIR analysis confirms the complex formation of the polymer with the salt. The conductivity analysis shows that the 20 mol% ammonium thiocyanate doped polymer electrolyte has high ionic conductivity and it has been found to be 1.7 × 10−4 S cm−1, at room temperature. From the admittance plot, the activation energy has been found to be low for 20 mol% salt doped polymer electrolyte. The dielectric behavior has been analyzed using dielectric permittivity (e∗), dissipation factor (tan δ) and electric modulus (M∗) of the samples.

Journal ArticleDOI
TL;DR: In this article, LiCoO2 thin films with different orientations were prepared by radio frequency (RF) magnetron sputtering, and the Li-ion chemical diffusion coefficients, DLi, were measured using cyclic voltammetry (CV), galvanostatic intermittent titration technique (GITT), potentiostatic inertion technique (PITT), and electrochemical impedance spectroscopy.

Journal ArticleDOI
TL;DR: This columnar supramolecular assembly forming the nanostructures shows the one-dimensional 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.
Abstract: 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.

Journal ArticleDOI
TL;DR: In this paper, a series of nanocomposite polymer electrolytes (NCPEs) comprising nanoparticles of BaTiO3, Al2O3 or SiO2 were prepared by electrospinning technique.

Journal ArticleDOI
TL;DR: In this paper, the segmental and local chain dynamics as well as the transport of Na+ and Li+ cations in a series of model poly(ethylene oxide)-based polyurethane ionomers are investigated using dielectric relaxation spectroscopy.
Abstract: The segmental and local chain dynamics as well as the transport of Na+ and Li+ cations in a series of model poly(ethylene oxide)-based polyurethane ionomers is investigated using dielectric relaxation spectroscopy. A physical model of electrode polarization is employed to separately determine mobile ion concentration and ion mobility in these single-ion conductors. A model including unpaired ions, separated ion pairs, and contact ion pairs is used to reconcile the very small fraction of free ions obtained using the electrode polarization model with those of previous studies of ion association in polyether-based single-ion conducting and salt-containing systems.

Journal ArticleDOI
TL;DR: Two ionic liquids based upon N-alkyl-N-methylpyrrolidinium cations and the bis(fluorosulfonyl)imide (FSI(-)), N(SO2F)2(-), anion have been extensively characterized and the ionic conductivity and viscosity of these materials are found to be among the highest and lowest, respectively, reported for aprotic ions.
Abstract: Two ionic liquids based upon N-alkyl-N-methylpyrrolidinium cations (PY(1R)(+)) (R=3 for propyl or 4 for butyl) and the bis(fluorosulfonyl)imide (FSI(-)), N(SO2F)2(-), anion have been extensively characterized. The ionic conductivity and viscosity of these materials are found to be among the highest and lowest, respectively, reported for aprotic ionic liquids. Both ionic liquids crystallize readily on cooling and undergo several solid-solid phase transitions on heating prior to melting. PY13FSI and PY14FSI are found to melt at -9 and -18 degrees C, respectively. The thermal stability of PY13FSI and PY14FSI is notably lower than for the analogous salts with the bis(trifluoromethanesulfonyl)imide (TFSI(-)), N(SO2CF3)2(-), anion. Both ionic liquids have a relatively wide electrochemical stability window of approximately 5 V.

Journal ArticleDOI
TL;DR: Pyrrolidinium based PILs have a relatively low cost, a low toxicity and exhibit a large electrochemical window as compared to other protic ionic liquids (up 3 V), and are good or superionic liquids and shows extremely fragility.
Abstract: New pyrrolidinium-cation-based protic acid ionic liquids (PILs) were prepared through a simple and atom-economic neutralization reactions between pyrrolidine and Bronsted acids, HX, where X is NO 3 (-), HSO 4 (-), HCOO (-), CH 3COO (-) or CF 3COO (-) and CH 3(CH 2) 6COO (-). The thermal properties, densities, electrochemical windows, temperature dependency of dynamic viscosity and ionic conductivity were measured for these PILs. All protonated pyrrolidinium salts studied here were liquid at room temperature and possess a high ionic conductivity (up to 56 mS cm (-1)) at room temperature. Pyrrolidinium based PILs have a relatively low cost, a low toxicity and exhibit a large electrochemical window as compared to other protic ionic liquids (up 3 V). Obtained results allow us to classify them according to a classical Walden diagram and to determinate their "Fragility". Pyrrolidinium based PILs are good or superionic liquids and shows extremely fragility. They have wide applicable perspectives for fuel cell devices, thermal transfer fluids, and acid-catalyzed reaction media as replacements of conventional inorganic acids.

Journal ArticleDOI
TL;DR: In this paper, a tetrafunctional epoxy resins with tetraethylenepentamine (TEPA) was used to confine an ionic liquid in a networked polymer.
Abstract: Networked polymers confining an ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide (EMImTFSI), were prepared by curing a mixture of bisphenol A diglycidyl ether (BADGE) and tetrafunctional epoxy resins with tetraethylenepentamine (TEPA) in the presence of ionic liquid. It was found that addition of the tetrafunctional epoxy resins was inevitable for better ionic liquid confinement. The ionic liquid confinement, ionic conductivity, mechanical strength, and morphology of the materials strongly depended on the ionic liquid content. At a low ionic liquid content ( 40 wt %), it did not confine the ionic liquid showing higher ionic conductivity with a low Young’s modulus. At a high ionic liquid content (>40 wt %), microphase separation between the ionic liquid and the epoxy networked polymer was observed by scanning electron ...

Journal ArticleDOI
TL;DR: In this article, polymer/ionic liquid composites were investigated as solvent-free electrolytes for lithium batteries and they were UV crosslinked with benzophenone as the photoinitiator.

Journal ArticleDOI
TL;DR: In this paper, a new plasticized nanocomposite polymer electrolyte based on poly (ethylene oxide) (PEO)-LiTf dispersed with ceramic filler (Al2O3) and plasticized with propylene carbonate (PC), EC, and a mixture of EC and PC (EC+PC) have been studied for their ionic conductivity and thermal properties.
Abstract: A new plasticized nanocomposite polymer electrolyte based on poly (ethylene oxide) (PEO)-LiTf dispersed with ceramic filler (Al2O3) and plasticized with propylene carbonate (PC), ethylene carbonate (EC), and a mixture of EC and PC (EC+PC) have been studied for their ionic conductivity and thermal properties. The incorporation of plasticizers alone will yield polymer electrolytes with enhanced conductivity but with poor mechanical properties. However, mechanical properties can be improved by incorporating ceramic fillers to the plasticized system. Nanocomposite solid polymer electrolyte films (200-600 mu m) were prepared by common solvent-casting method. In present work, we have shown the ionic conductivity can be substantially enhanced by using the combined effect of the plasticizers as well as the inert filler. It was revealed that the incorporating 15 wt.% Al2O3 filler in to PEO: LiTf polymer electrolyte significantly enhanced the ionic conductivity [sigma(RT) (max)= 7.8 x 10(-6) S cm(-1)]. It was interesting to observe that the addition of PC, EC, and mixture of EC and PC to the PEO: LiTf: 15 wt.% Al2O3 CPE showed further conductivity enhancement. The conductivity enhancement with EC is higher than PC. However, mixture of plasticizer (EC+PC) showed maximum conductivity enhancement in the temperature range interest, giving the value [sigma(RT) (max)= 1.2 x 10(-4) S cm(-1)]. It is suggested that the addition of PC, EC, or a mixture of EC and PC leads to a lowering of glass transition temperature and increasing the amorphous phase of PEO and the fraction of PEO-Li+ complex, corresponding to conductivity enhancement. Al2O3 filler would contribute to conductivity enhancement by transient hydrogen bonding of migrating ionic species with O-OH groups at the filler grain surface. The differential scanning calorimetry thermograms points towards the decrease of T-g, crystallite melting temperature, and melting enthalpy of PEO: LiTf: Al2O3 CPE after introducing plasticizers. The reduction of crystallinity and the increase in the amorphous phase content of the electrolyte, caused by the filler, also contributes to the observed conductivity enhancement.

Journal ArticleDOI
TL;DR: In this paper, the effect of adding 5% toluene to LiCF 3 SO 3 in tetra(ethylene glycol) dimethyl ether (TEGDME) liquid electrolyte on the performance of Li/S cells at room temperature was studied.

Journal ArticleDOI
TL;DR: In this paper, the conductivity of lithium ions along three principal axis directions in single crystal LiFePO4 as a function of temperature was investigated using AC impedance spectroscopy.

Journal ArticleDOI
TL;DR: In this article, thermally induced phase separation (TIPS) process using sulfolane as the diluent was used for the preparation of polyvinylidene fluoride (PVDF) and polyethylene oxide (PEO) blend membranes.

Journal ArticleDOI
TL;DR: In this article, the authors developed easy-to-use methods to incorporate ionic liquids into a polymer matrix to synthesize gel polymer electrolytes (GPEs), which are used to fabricate solid-state ultracapacitors that demonstrate improved performance and cycle life.
Abstract: Electrolytes are an important component in determining the performance and cycle life of ultracapacitors. Good electrolytes should have high ionic conductivity, large electrochemical windows, and excellent thermal and chemical stability. Ionic liquids are possibly ideal electrolytes to satisfy these requirements. In the present work, we developed easy-to-use methods to incorporate ionic liquids into a polymer matrix to synthesize gel polymer electrolytes (GPEs). Combining the advantages of both the ionic liquids and the conventional GPEs, the resultant solid-state ionic liquid-incorporated gel polymer electrolytes (ILGPEs) possess better properties than these two components considered individually. Our synthesized ILGPE films are flexible and mechanically strong and have a wide electrochemical window of 4 V, a high ionic conductivity up to 3.5 mS/cm (at room temperature), and a high thermal stability up to 350°C. These ILGPEs have been used to fabricate solid-state ultracapacitors that demonstrate improved performance and cycle life.

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a host matrix for the preparation of polymer electrolytes (PEs) by activating with the nonvolatile and safe room temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonylimide) (BMITFSI).