Tetsuya Tsuda

A highly conductive room temperature molten fluoride: EMIF.2.3HF

Reaction of 1-ethyl-3-methylimidazolium chloride (EMICl) and anhydrous hydrogen fluoride gives a nonvolatile, room temperature molten salt. EMIF.2.3HF. The elemental analysis, vibrational, and nuclear magnetic resonance spectroscopy suggests the presence of oligomeric anions. (HF) n F - , in the salt The liquid is stable in air and able to he handled in a Pyrex glass vessel. The specific conductivity is 100 mS cm -1 at 298 K. which is extremely high compared with other salts of this kind. The high conductivity is realized by its low viscosity(4.85cP at 298 K) The liquid temperature ranges from 180 to 350 K, and electro-chemical window is about 3.2 V when a vitreous carbon is used for the electrode material.

Physicochemical Properties of 1,3-Dialkylimidazolium Fluorohydrogenate Room-Temperature Molten Salts

Reaction of some N-alkylimidazolium chlorides with anhydrous hydrogen fluoride (HF) gave nonvolatile room temperature molten salts (room temperature ionic liquids), RMImF.2.3HF where RMIm = 1,3-dimethylimidazolium (DMIm), 1-ethyl-3-methylimidazolium (EMIm), 1-methyl-3-propylimidazolium, 1-butyl-3-methylimidazolium, 1-methyl-3-pentylimidazolium, and 1-hexyl-3-methylimidazolium. Vacuum stable salts at room temperature exhibited similar stoichiometry regardless of the type of cation. In the differential scanning calorimetry (DSC) curve, DMImF.2.3HF exhibited both the freezing and melting on the cooling and heating process, respectively, while EMImF.2.3HF showed the glass transition on the cooling process and devitrification and melting on the heating process. The other salts show only the glass transition on the DSC curves. High specific conductivities, 110 and 100 mS cm -1 , were observed at 298 K for DMImF.2.3HF and EMImF.2.3HF, respectively. Introduction of the longer alkyl side chains to the imidazolium cation increased the viscosity and decreased the conductivity. These salts were stable in air and did not etch a Pyrex glass container at ambient conditions. The dissociation pressures of HF from the salts were negligibly small at ambient condition. The electrochemical windows of these salts was about 3 V.

A highly conductive composite electrolyte consisting of polymer and room temperature molten fluorohydrogenates

A highly conductive composite electrolyte consisting of poly-2-hydroxyethyl methacrylate and a room temperature molten fluorohydrogenates, EtMeIm(HF)nF (EtMeIm: 1-ethyl-3-methylimidazolium, the averaged number n of the oligomeric anions in the vacuum stable salt is 2.3), has been obtained by a radical reaction method. A transparent gel composite electrolyte is formed when the molar fraction of EtMeIm(HF)nF, N, is in the range of 0.20–0.60. The conductivity of the electrolyte increases as the N increases. The maximum conductivity of 2.310 2 Sc m 1 is obtained for N=0.60 at 300 K. Like the original salt, this composite electrolyte exhibits an excellent stability in air and does not etch the Pyrex glass. The electrochemical window of the neat salt, f3.2 V, is extended to f3.5 V for the composite electrolyte. D 2002 Elsevier Science B.V. All rights reserved.

Nucleation and surface morphology of aluminum–lanthanum alloy electrodepsited in a LaCl3-saturated AlCl3–EtMeImCl room temperature molten salt

Abstract The cathodic polarization curve on a tungsten disk electrode was measured in a LaCl 3 -saturated AlCl 3 –EtMeImCl [1-ethyl-3-methylimidazolium chloride] melt ( N =0.667: N is molar fraction of AlCl 3 ) at 298 K. The deposition overpotential of aluminum increases compared with the curve obtained before adding LaCl 3 . It was found that the nucleation/growth process is instantaneous nucleation from chronoamperometric data. When galvanostatic electrolysis was performed in the LaCl 3 -saturated melt, the strong orientation of (200) for the electrodeposits is observed at low current densities (≤7.5 mA cm −2 ). On the other hand, the normalized integrated intensity of XRD for (200) and (220) reflections has similar strength at high current densities (≥10.0 mA cm −2 ). The electodeposits become denser than those obtained in the original melt. In particular, very smooth surface is obtained in the case of 15.0 mA cm −2 with stirring the bath.

Electrodeposition of lanthanum in lanthanum chloride saturated AlCl3-1-ethyl-3-methylimidazolium chloride molten salts

The solubility of LaCl3 in acidic AlCl3–1-ethyl-3-methylimidazolium chloride (AlCl3–EMICl) ambient temperature melts at 298 K increases as the acidity of the melts increases. When LaCl3 was dissolved in the melt (molar fraction of AlCl3, N=0.667), Raman spectra of AlCl4− and Al2Cl7− anion were observed. From these results, the dissolution reaction in the acidic melts is thought to be: 3Al2Cl7−+LaCl3⇄La(III)+6AlCl4−. Electrochemical measurements and potentiostatic electrolysis were performed in various LaCl3 saturated AlCl3–EMICl melts. The electrodeposits obtained at more negative potential than −0.18 V versus Al(III)/Al in a LaCl3 saturated acidic melt (N=0.667) were pure aluminum metal. It was suggested that lanthanum metal electrodeposits at around −1.95 V in the LaCl3 saturated melt (N=0.667) after addition of excessive LiCl and 50 mmol kg−1 of SOCl2.

The structures of alkylimidazolium fluorohydrogenate molten salts studied by high-energy X-ray diffraction

Abstract The structures of a series of XF·2.3HF (X=1-methylimidazolium, 1-ethyl-3-methylimidazolium (EMI), 1-butyl-3-methylimidazolium, 1-hexyl-3-methyl-imidazolium (HMI)) room temperature molten salts have been investigated by the high-energy synchrotron X-ray diffraction technique. The correlation peaks appearing in the total correlation function are mainly ascribed to an intra-molecular correlation of alkylimidazolium cations. However, it is suggested that the peak near 3.6 A is ascribed not only to intra-molecular but also inter-molecular correlations of the cation. The contribution of the latter is also supported by the first sharp diffraction peak of the total structure factor found at almost the same position as that of a Bragg peak in the simulated X-ray diffraction pattern of solid EMIF·HF with a layered structure, corresponding to the layer separation.

Tris(1-ethyl-3-methyl­imidazolium) hexa­chloro­lanthanate

In the title complex, (C(6)H(11)N(2))(3)[LaCl(6)], centrosymmetric octahedral hexachlorolanthanate anions are located at the corners and face-centers of the monoclinic unit cell. The ring H atoms of the cations interact with the Cl atoms of the anions via hydrogen bonding, and bifurcation of the hydrogen bonding is observed. Cation-cation interactions via hydrogen bonding between the ring H atoms and pi-electrons of aromatic rings are also observed as in other imidazolium salts.