Anion Diffusion Coefficients Research Articles

Ion jelly conductive properties using dicyanamide-based ionic liquids.

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-Goldstein process. Besides the relevant information on the more fundamental nature providing physicochemical details on ILs behavior, new doorways are opened for practical applications by using IJ as a strategy to produce novel and stable electrolytes for different electrochemical devices.

Determining diffusion coefficients of ionic liquids by means of field cycling nuclear magnetic resonance relaxometry.

Field Cycling Nuclear Magnetic Resonance (FC NMR) relaxation studies are reported for three ionic liquids: 1-ethyl-3- methylimidazolium thiocyanate (EMIM-SCN, 220-258 K), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4, 243-318 K), and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6, 258-323 K). The dispersion of (1)H spin-lattice relaxation rate R1(ω) is measured in the frequency range of 10 kHz-20 MHz, and the studies are complemented by (19)F spin-lattice relaxation measurements on BMIM-PF6 in the corresponding frequency range. From the (1)H relaxation results self-diffusion coefficients for the cation in EMIM-SCN, BMIM-BF4, and BMIM-PF6 are determined. This is done by performing an analysis considering all relevant intra- and intermolecular relaxation contributions to the (1)H spin-lattice relaxation as well as by benefiting from the universal low-frequency dispersion law characteristic of Fickian diffusion which yields, at low frequencies, a linear dependence of R1 on square root of frequency. From the (19)F relaxation both anion and cation diffusion coefficients are determined for BMIM-PF6. The diffusion coefficients obtained from FC NMR relaxometry are in good agreement with results reported from pulsed- field-gradient NMR. This shows that NMR relaxometry can be considered as an alternative route of determining diffusion coefficients of both cations and anions in ionic liquids.

Influence of Zn2+and Water on the Transport Properties of a Pyrrolidinium Dicyanamide Ionic Liquid

In order to expand our understanding of a potential zinc-based battery electrolyte, we have characterized the physical and transport properties of the ionic liquid (IL) 1-butyl-1-methylpyrrolidinium dicyanamide ([C4mpyr][dca]) containing various levels of both Zn(2+) and H2O. Detailed measurements of density, viscosity, conductivity, and individual anion and cation diffusion coefficients using pulsed-field-gradient (PFG) NMR combined with NMR chemical shifts and spin-lattice relaxation (T1) NMR experiments provide insights into the motion and chemical environment of all molecular species. We find that the various techniques for probing ion transport and dynamics form a coherent picture as a function of electrolyte composition. Zn(2+) addition causes a moderate reduction in the self-diffusion of the IL anion and cation, whereas the addition of H2O increases ion mobility by increasing the liquid's overall fluidity. Temperature-dependent (13)C T1 experiments of the dca carbon analyzed using Bloembergen-Purcell-Pound fits show monotonic slowing of anion dynamics with Zn(2+) addition, suggesting increased Zn(2+)/dca(-) association. T1 experiments show minimal change in the spin-lattice relaxation of cation or anion upon H2O addition, suggesting that H2O is playing no significant role in Zn(2+) speciation. Finally, we employ a novel electrophoretic NMR technique to directly determine the electrophoretic mobility of the C4mpyr cation, which we discuss in the context of impedance-based conductivity measurements.

Negative Capacitance of an Electrolytic Cell in the Absence of Bias Potential

We extend the Poisson–Nernst–Planck model to the case of an electrolytic cell limited by ohmic electrodes that are partially polarizable with different affinities for anions and cations. We show that the finite conductivity of the electrodes in combination with the different ionic diffusion coefficients for anions and cations may give rise to negative capacitance behavior of the cell impedance in the absence of any bias. The range where the negative capacitance character of the electrolytic cell appears is localized. When ambipolar diffusion and electrode polarization effects are simultaneously present, the real part of the electrical impedance shows up to three plateaux.

Lithium Polymer Gel Electrolytes Designed to Control Ionic Mobility

We prepared new lithium polymer gel electrolytes with Lewis acid ionic groups on the PVB polymer chain (ionic PVB gel) with the goal of attracting anions to restrict their mobility. The cation and anion diffusion coefficients (Dcation and Danion), dissociation degree of the salt (x), interactive forces between the ion and polar groups on the polymer (βcation and βanion), and interactive forces between the cation and anion (α) were estimated based on measurements of the diffusion coefficients (DLi, DF, and DH) and ionic conductivity (σ). The Dcation and Danion of the ionic PVB gel increased and decreased, respectively, compared to the values in the original PVB gel that did not contain an ionic group, which led to the enhanced cation transport number. The interactions between the mobile ions and polar groups depended on the solvation structure of the lithium cation, Li(EC)n+, which is associated with the polarity of the gel solvent. The solvating EC species around Li+ is the barrier for weakening Li+/OH– a...

Cation and Anion Transport in a Dicationic Imidazolium-Based Plastic Crystal Ion Conductor

Here we investigate the organic ionic plastic crystal 1,2-bis[N-(N'-hexylimidazolium-d2(4,5))]ethane 2PF6(-) in one of its solid plastic crystal phases by means of multinuclear solid-state (SS) NMR and pulsed-field-gradient NMR diffusometry. We quantify distinct cation and anion diffusion coefficients as well as the Arrhenius diffusion activation energies (Ea) in this dicationic imidazolium-based plastic crystal. Our studies suggest a change in transport mechanism for the cation upon varying thermal and magnetic treatment (9.4 T), evidenced by differences in cation and anion Ea. Moreover, variable temperature (2)H SSNMR line shapes support a change in local molecular environment upon slow cooling in B0. We quantify the percentage of mobile anions as a function of temperature with (19)F SSNMR, wherein two distinct spectral features are present. We also comment on the Arrhenius pre-exponential factor for diffusion (D0), giving insight into the number of degrees of freedom for transport for both cation and anion as a function of thermal treatment. Given the breadth and depth of our measurements, we propose that bulk ion transport is dominated by anion diffusion in ionic-liquid-like domain boundaries separating crystallites. This study elucidates fundamental properties of this plastic crystal, and allows for a more general and deeper understanding of ion transport within such materials.

Coupled study of water-stable isotopes and anions in porewater for characterizing aqueous transport through the Mesozoic sedimentary series in the eastern Paris Basin

This study presents data on chloride and bromide concentrations in porewater, water and anion diffusion coefficients, and their accessible porosities based on radial diffusion experiments on rock samples collected from a 2000 m-deep borehole (EST433) drilled by Andra in the eastern Paris Basin. The distributions of water stable isotope and chloride concentrations in porewater along this column reveal transient flows of water and solutes between the aquitard layers and the surrounding aquifers. These distributions confirm the occurrence of two separate aquitard/aquifer systems: “Oxfordian/Callovo–Oxfordian/Dogger” and “Dogger/Liassic/Rhaetian”. This separation is confirmed by Cl−/Br− ratios, which are low in Liassic and Dogger porewater, suggesting the influence of primary brines, and which are close to the marine ratio in the Dogger groundwater. Based on these results, transport simulations in the two systems were carried out according to different scenarios. The simulation results confirm that transport properties obtained in the laboratory at sample scale may be extrapolated to the formation scale. It is highly probable that diffusion is the main transport process in the Callovo–Oxfordian formation. This may also be the case in the Dogger/Liassic layer, although a limited contribution from advection cannot be totally excluded. By testing different scenarios of boundary conditions in diffusive models, it is proposed that the Dogger aquifer was first activated in the Early Miocene.

Composite PEOn:NaTFSI polymer electrolyte: Preparation, thermal and electrochemical characterization

Membranes of sodium bis(trifluoromethanesulfonate) imide (NaTFSI) complexed with poly(ethylene oxide) (PEO) salt have been prepared by a solvent-free hot-pressing technique with different EO:Na molar ratio. All membranes show good ionic conductivities in the range of 10−3 S cm−1 above 70 °C. However, the more NaTFSI-concentrated samples are sticky gums due to the plasticizing nature of the anion. The PEO20:NaTFSI sample exhibits the compromise of conductivity, thermal and mechanical properties. The addition of nanometric SiO2 to the PEO20:NaTFSI membranes further enhances their mechanical properties. Moreover, the PEO20:NaTFSI + 5 wt.% SiO2 membranes show similar ionic conductivity and similar anodic electrochemical stability in comparison to the ceramic free PEO20:NaTFSI sample. In a Na(s)/polymer electrolyte/Na(s) symmetrical cell followed up to 30 days, the presence of the ceramic filler slightly increased the interface resistance in comparison to the ceramic-free membrane. Nuclear magnetic resonance determinations of anion diffusion coefficients and Na+ mobility suggest that presence of filler may have a positive affect on the cation transference number that is in accordance with the tNa+ transference number measurement.

Structure and mass transport characteristics of the surface of gadolinium-doped ceria nanocrystals: Molecular dynamics study

Surface of CGO nanocrystals in a vacuum was investigated by MD method in a wide temperature range with five different potentials. Temperature dependences of distances between cations in near-surface layers in the direction along the surface and to the nanocrystal center were studied in detail. Surface area ratio S(100)/S(111) for equilibrium shape of truncated octahedron has maximum for nanocrystals of 6000–12,000 ions.Surface ion displacement was decomposed on the path along the surface and into the bulk of nanocrystal. The diffusion of surface ions in the entire temperature range has predominantly two-dimensional character, regardless of potentials and the dopant concentration X. Anion diffusion coefficients on the surface and in the bulk were compared, they coincide at T<1200K for X≥0.05. For a system with X=0.01 anion migration energies of 0.82eV and 0.77eV, and anti-Frenkel pair formation energies of 3.01eV and 4.04eV on the surface and in the bulk, respectively, were obtained.

Proton Conductor of Propylene Carbonate–Plasticized Carboxyl Methylcellulose–Based Solid Polymer Electrolyte

Carboxyl methylcellulose (CMC) solid polymer electrolytes were prepared by utilizing oleic acid (OA) and different wt.% of propylene carbonate (PC) by using the solution casting technique. An ionic conductivity study of the films was done by using impedance spectroscopy. The highest ionic conductivity gained is 2.52 × 10−7 S cm−1 at ambient temperature for sample CMC-OA-PC 10 wt.%. From transference number measurement (TNM), the value of cation diffusion coefficient, D+, and ionic mobility, μ+, was higher than the value of anion diffusion coefficient, D−, and ionic mobility, μ−. Thus, the results prove that the present samples were proton conductors.

Influence of impurity-vacancy disorder on characteristics of gadolinium-doped ceria oxide: Molecular dynamics study

Abstract By high-speed MD method using GPU the CGO nanocrystals of about 40,000 particles during about 0.1 μs, in the temperature range (2500–700) K, were simulated. The influence of different dopant distributions on the nanocrystal characteristics, for two potentials sets, was investigated. For a given potentials set Gd distribution does not affect the lattice parameter and the anion diffusion coefficients. Five types of impurity vacancies were defined, by the Gd number in the nearest neighborhood, and temperature dependences were built. The formation energies of vacancies of all types were obtained. Calculated by the MD conductivity activation energy of 0.6 eV acceptable coincides with the experimental 0.7 eV, just as the absolute conductivity values. The supposition that helium in CGO ceramics dissolve in vacancies, surrounded only by cerium ions, was discussed. Analysis of the MD, conductivity measurements and helium defectoscopy shows that up to the melting temperature the vacancies are mainly associated with impurity ions.

On the extraction of ion association data and transference numbers from ionic diffusivity and conductivity data in polymer electrolytes

The degree of ion association in polymer electrolytes is often characterized by the Nernst–Einstein deviation parameter Δ, which quantifies the relative difference between the true ionic conductivity directly measured by electrical methods and the hypothetical maximum conductivity calculated from the individual ionic self-diffusion coefficients. Despite its unambiguous definition, the parameter Δ is a global quantity with limited explanatory power. Similar is true for the cation transport number tcat*, which relies on the same ionic diffusion coefficients usually measured by nuclear magnetic resonance or radiotracer methods. Particularly in cases when neutral ion pairs dominate over higher-order aggregates, more specific information can be extracted from the same body of experimental data that is used for the calculation of Δ and tcat*. This information concerns the pair contributions to the diffusion coefficient of cations and anions. Also the true cation transference number based on charged species only can be deduced. We present the basic theoretical framework and some pertinent examples dealing with ion pairing in polymer electrolytes.

Molecular dynamics simulation of diffusion of nitrobenzene in 3-methylimidazolium hexafluorophosphate ionic liquids

The diffusions of nitrobenzene (PhNO2) in the three kinds of ionic liquids (ILs), i.e. 1-ethyl-3-methylimidazolium hexafluorophosphate ([Emim][PF6]), 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]), and 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF6]) were examined by molecular dynamics (MD) simulation. Diffusion coefficients of PhNO2, imidazole (Mim) cation and PF6 anion were calculated based on the Einstein equation. The influence of the different ionic liquids on the diffusion of PhNO2 was discussed. The results showed that at the same simulation concentration, the diffusion coefficients of all the species decrease with an increase of the side chain of 3-methylimidazolium hexafluorophosphate ionic liquids in the model system. These simulation results are in good agreement with the electrochemical experiment reported by Chen et al. Analyses of the pair correlation functions (PCFs) of the simulation systems showed that the non-bond and hydrogen bond interactions are formed between PhNO2–ionic liquid systems. The Coulomb and van der Waals (vdW) interactions are helpful for the diffusion of PhNO2 in 3-methylimidazolium hexafluorophosphate ionic liquids and the contribution from the vdW interaction is significantly greater than that from the Coulomb interaction in the system. From the related coefficient (R) of mean square displacement (MSD) curve and PCFs, the diffusion of PhNO2 in [Hmim][PF6] ionic liquids is weaker than the other two ionic liquids. This study has provided a theoretical direction for the experiments on the mass transfer of PhNO2 in ionic liquids.

Ion Transport Effects in a Solid Polymer Electrolyte Due to Salt Substitution and Addition Using an Ionic Liquid

We investigated mass and charge transport in amorphous salt-in-poly(ethylene oxide) (PEO) electrolytes with NaI and/or the ionic liquid (IL) EMImTFSI (1-ethyl-3-methylimizadolium bis(trifluoromethylsulfonyl)imide) as salt component. Combining the results of ion conductivity, pulsed field gradient nuclear magnetic resonance, and radiotracer diffusion measurements, it is found that over wide temperature ranges both the cation and anion diffusion coefficients and the charge diffusivity are distinctly larger in PEO(20)EMImTFSI than in PEO(20)NaI complexes, where the monomer-to-salt mole ratio equals 20. In the mixed-salt complexes PEO(20)NaI(1)EMImTFSI(1) and PEO(20)NaI(0.5)EMImTFSI(0.5), we observe a slowing down of the IL ions EMIm and TFSI along with a diffusivity enhancement of the I anion compared to the single-salt base complexes. For the cation Na, a diffusivity increase is only effected by IL substitution, but because of the concomitant decrease of the Na concentration, it does not predict more effective charge transfer in a battery cell configuration.

Electrochemical impedance of ion-exchange systems with weakly charged membranes

The aim of this work was to investigate the effect of the membrane fixed-charge concentration on the electrochemical impedance of ion-exchange membrane systems and the specific properties of the impedance of ion-exchange systems with weakly charged membranes. The systems under study are constituted by a membrane with a homogeneous distribution of negative fixed-charge and two diffusion boundary layers on both sides of the membrane. The ionic transport processes of a binary electrolyte are theoretically described by the Nernst–Planck and Poisson equations not only in the ion-exchange membrane but also in the two diffusion boundary layers. The electrochemical impedance for different values of the anion diffusion coefficients and the direct component of the applied electric current has been obtained by using the network simulation method as a function of the membrane fixed-charge concentration. New results are presented in relation with the evolution of the characteristic frequency of the diffusion impedance and the dc resistance of the system with the uniform concentration of the fixed-charge inside the membrane.

Effects of Water Concentration on the Structural and Diffusion Properties of Imidazolium-Based Ionic Liquid–Water Mixtures

We have used molecular dynamics simulations to study the properties of three ionic liquid (IL)-water systems: 1-butyl-3-methylimidazolium chloride ([bmim]Cl), 1-ethyl-3-methylimidazolium acetate ([emim][Ac]), and 1,3-dimethylimidazolium dimethylphosphate ([dmim][DMP]). We observe the transition of those mixtures from pure IL to aqueous solution by analyzing the changes in important bulk properties (density) and structural and bonding properties (radial distribution functions, water clustering, hydrogen bonding, and cationic stacking) as well as dynamical properties (diffusion coefficients) at 12 different concentration samplings of each mixture, ranging from 0.0 to 99.95 mol % water. Our simulations revealed across all of the different structural, bonding, and dynamical properties major structural changes consistent with a transition from IL-water mixture to aqueous solution in all three ILs at water concentrations around 75 mol %. Among the structural changes observed were rapid increase in the frequency of hydrogen bonds, both water-water and water-anion. Similarly, at these critical concentrations, the water clusters formed begin to span the entire simulation box, rather than existing as isolated networks of molecules. At the same time, there is a sudden decrease in cationic stacking at the transition point, followed by a rapid increase near 90 mol % water. Finally, the diffusion coefficients of individual cations and anions show a rapid transition from rates consistent with diffusion in IL's to rates consistent with diffusion in water beginning at 75 mol % water. The location of this transition is consistent, for [bmim]Cl and [dmim][DMP], with the water concentration limit above which the ILs are unable to dissolve cellulose.

Role of cation choice in the radiation tolerance of pyrochlores

We have used atomistic computer simulations to study anion diffusion coefficients and the response to swift heavy ion irradiation of Gd2TixZr2−xO7 pyrochlore for x values of 0, 0.5, 1, 1.5 and 2. In Gd2Ti2O7, a thermal energy deposition per unit length of 12 keV nm−1 results in a cylindrical amorphous track of radius 2 nm in good agreement with experiment. The volume swelling of the track is 4%, which suggests that it is partially amorphous. Gd vacancies and Ti interstitials along with cation exchange play a role in damage accumulation in the titanate. In sharp contrast, Gd2Zr2O7 does not swell and merely transforms from pyrochlore to fluorite under the same conditions. The activation energy barrier for oxygen hopping by the vacancy mechanism in these pyrochlores is 0.26–0.44 eV. The radiation tolerance of gadolinium zirconate pyrochlore is related to the efficient annihilation of cation Frenkel pairs, the low energy cost and negligible volume expansion associated with the resulting cation exchange, and efficient annealing of anion sublattice damage.

Anomalous solubility of oxygen in acetonitrile/water mixture containing tetra-n-butylammonium perchlorate supporting electrolyte; the solubility and diffusion coefficient of oxygen in anhydrous acetonitrile and aqueous mixtures

We report the oxygen electro-reduction in air-saturated acetonitrile (MeCN) solution supported by 0.1M tetra-n-butylammonium perchlorate salt under two experimental conditions: (1) anhydrous MeCN at elevated temperatures from 298.5 to 313.0K on platinum electrodes; (2) water-mixed MeCN solution (mole fraction of MeCN: 0.72<χMeCN<1) at 298.5K on glassy carbon electrodes. The measurements of diffusion coefficients and concentrations were determined via single and double potential step chronoamperometry at microdisc electrodes. The experimental results are analysed by Shoup and Szabo equation, or where necessary via simulation. Under the first experimental condition, the diffusion coefficients of oxygen, D(O2), and superoxide radical anion, D(O2-), at 298.5K are determined to be (9.20±0.36)×10−9m2s−1 and (2.73±0.35)×10−9m2s−1 respectively. Over the studied temperature range, the diffusional activation energies of oxygen (Ea,O2) and superoxide (Ea,O2−) are reported for the first time to be (2.07±0.05)kJmol−1 and (8.01±2.24)kJmol−1. The significant small value of Ea,O2 suggests the diffusional behaviour of molecular oxygen cannot be described by the Stokes–Einstein relationship; whereas that of the radical anion can be. This further confirms that the importance of the size of diffusional species must be at least comparable in size to that of the solvent molecules in order for this macroscopic theory to apply. Further, the concentration of dissolved oxygen, c(O2), is obtained as (1.26±0.05)mM, and the oxygen dissolution is quantitatively shown to be an endothermic process. The standard Gibbs energy of solvation (ΔGSolve) and the standard entropy change of solvation (ΔGSolve) are experimentally calculated to be +19.9 (error: +0.12/−0.11)kJmol−1 and −65.5 (error: +15.25/−12.62)Jmol−1K−1 respectively at 298.5K. Although the ΔGSolve for oxygen in water is much more positive than that in MeCN solution, an anomalous increase in oxygen solubility after the initial water-mixing with MeCN (0.94<χMeCN<1), under experimental condition (2), was observed. Over the same range of χMeCN, the D(O2) is found to drop in significant amount compared with its predicted value. Such behaviour can be tentatively explained by the preferential solvation of molecular oxygen by water molecules via hydrogen bonding at lower water content. Consequently, the thermodynamic terms of mixing may be altered, and therefore favour the dissolution of oxygen.

Ion Transport with Charge-Protected and Non-Charge-Protected Cations Using the Compensated Arrhenius Formalism. Part 2. Relationship Between Ionic Conductivity and Diffusion

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.

Effect of Anion Size on the Conductivity Behaviour of Hexanoyl Chitosan-Based Polymer Electrolytes

Films of hexanoyl chitosan containing lithium perchlorate (LiClO4) or lithium triflouromethanesulfonate (LiCF3SO3) were prepared by solution casting technique. The effect of anion size on the conductivity behaviour of hexanoyl chitosan has been investigated. The conductivity of 4.15 × 10-7S/cm and 4.07 × 10-6S/cm were achieved for the hexanoyl chitosan-LiClO4and hexanoyl chitosan-LiCF3SO3electrolyte system at 50wt.% of salt concentration, respectively. The Rice and Roth model was used to analysis quantitatively the obtained conductivity trends for the prepared electrolyte systems. The diffusion coefficients of cations and anions were calculated from the conductivity and transference number measurements. This is followed by the discussion on the diffusion coefficients of ClO4-and CF3SO3-anion.