Kyoto University · Materials Science
Professor Yukihiro Yoshida's research lab specializes in the design, synthesis, and characterization of functional ionic liquids and their hybrid materials, with a focus on tailoring molecular structures to achieve enhanced electrochemical and transport properties. The lab investigates structure-property relationships in ionic liquids, particularly those with paramagnetic, luminescent, or low-viscosity characteristics, and explores their integration into porous frameworks such as metal–organic frameworks (MOFs) to develop advanced solid-state electrolytes. Key research directions include optimizing ionic conductivity, understanding ion dynamics in confined nanospaces, and engineering materials for applications in energy storage and conversion devices.
Figures are computed from collected data and may differ slightly.
New 1-ethyl-3-methylimidazolium (EMI) salts [EMI][C(CN)3] and [EMI][Ag(CN)2] were prepared and characterized. The C(CN)3 salt has a melting point at -11 degrees C and shows a low viscosity (18 cP) and a high ionic conductivity (1.8 x 10(-2) S cm(-1)) at room temperature. This conductivity is less than that of [EMI][N(CN)2] salt (2.7 x 10(-2) S cm(-1)), possibly due to the larger molecular weight of the anion. The first EMI salt containing Ag(I) complexes [EMI][Ag(CN)2] has a higher melting point
A series of dicyanamide [N(CN)2]-based ionic liquids were prepared using 1-alkyl-3-methylimidazolium cations with different alkyl chain lengths and ethyl-containing heterocyclic cations with different ring structures, and the influence of such structural variations on their thermal property, density, electrochemical window, viscosity, ionic conductivity, and solvatochromic effects was investigated. We found that the 1,3-dimethylimidazolium salt shows the highest ionic conductivity among ionic li
A series of paramagnetic ionic liquids, which are comprised of 1-alkyl-3-methylimidazolium RMI+ cation (R = Et, n-Bu, n-hexyl and n-octyl) and tetrahalogenoferrate(III) FeX4− anion (X = Cl and Br), were prepared, and the influence of structural variations such as changing the alkyl chain (R) length in the cation and substituting the halides (X) in the anion on their thermal behavior, infrared and ultraviolet-visible absorption spectra, density, viscosity, ionic conductivity and magnetic suscepti
Encapsulation of ionic liquids (ILs) into porous materials can provide environmentally benign solid-state electrolytes for various electrochemical devices, in particular, porous metal–organic frameworks (MOFs) that enable us to tailor their framework and pore structures by varying central metals and organic linkers as well as the ILs with an unlimited number of possible cation–anion combinations. Therefore, rational materials design based on the accumulated knowledge about the relationship betwe
Some recent developments concerning the syntheses and physical properties of functional ionic liquids, especially those having paramagnetic and luminescent properties, are highlighted. The component ions used so far include both inorganic and organic types; and various strategies, namely not only the proper choice but also the synthesis of anions to impart the functionality, are presented.
Most molecules in confined spaces show markedly different behaviors from those in the bulk. Large pores are composed of two regions: an interface region in which liquids interact with the pore surface, and a core region in which liquids behave as bulk. The realization of a highly mobile ionic liquid (IL) in a mesoporous metal-organic framework (MOF) is now reported. The hybrid shows a high room-temperature conductivity (4.4×10<sup>-3</sup> S cm<sup>-1</sup> ) and low activation energy (0.20 eV);
Abstract An EMI-based room-temperature (RT) ionic liquid containing d5 trivalent iron(III) ions [EMI][FeIIICl4] was fully investigated, where EMI is 1-ethyl-3-methylimidazolium. The viscosity of the salt is 14 cP at 30 °C, and its ionic conductivity is as high as 1.8 × 10−2 S cm−1 at 20 °C. The high conductivity and fluidity can be attributed to the reduced interionic Coulomb attractions owing to the nephelauxetic effect. Magnetic susceptibility shows the Curie–Weiss behavior arising from S = 5/
Article An object code compression approach to embedded processors Share on Authors: Yukihiro Yoshida Dept. Information Systems Engineering, Osaka University Dept. Information Systems Engineering, Osaka UniversityView Profile , Bao-Yu Song Dept. Information Systems Engineering, Osaka University Dept. Information Systems Engineering, Osaka UniversityView Profile , Hiroyuki Okuhata Dept. Information Systems Engineering, Osaka University Dept. Information Systems Engineering, Osaka UniversityView P
Ionic liquids composed of dicyanamide anion and various imidazolium-based cations were prepared, and the influence of structural variations such as substituting a hydrogen at 2-position and changing the sort of alkyl group at 1-position of imidazolium cations on their thermal behavior, density, solvatochromic effects, viscosity, ionic conductivity, and surface tension was characterized. The substitution of the 2-hydrogen for methyl group or N-methylimidazole decreases the fluidity and ionic cond
Abstract A series of genuine organic paramagnetic ionic liquids were prepared utilizing 2,2,6,6-tetramethyl-1-piperidinyloxyl-4-sulfate (TEMPO-OSO3) anion with S=1⁄2 radical spin. Their static susceptibilities and EPR spectra can be explained in terms of the paramagnetic spins on the TEMPO radical moieties, although they have much low fluidities and ionic conductivities.
The elastocaloric properties of poly (vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) [P(VDF-TrFE-CTFE)] terpolymer were directly characterized using an infrared imaging camera. At a strain of 12%, a reversible adiabatic temperature variation of 2.15 °C was measured, corresponding to an isothermal entropy variation of 21.5 kJ m−3 K−1 or 11 J kg−1 K−1. In comparison with other elastocaloric materials, P(VDF-TrFE-CTFE) appears to represent a trade-off between the large required stre
36 kinds of donor(D)–acceptor(A) type charge transfer (CT) solids were prepared based on ethylenedioxyethylenedithiotetrathiafulvalene (EDOEDT-TTF or EOET), which is a hybrid molecule of bis(ethylenedioxy)-TTF (BEDO-TTF or BO) and bis(ethylenedithio)-TTF (BEDT-TTF or ET). A plot of the first CT absorption bands in solids against the difference in first redox potential between donor and acceptor molecules (ΔE) classified the complexes into five groups, A: highly conductive CT complexes with parti
A series of diethylmethyl(2-methoxyethyl)ammonium (DEME)-based ionic liquids were prepared using bis(perfluoroalkanesulfonyl)amide (C(n)F(2n+1)SO(2))(2)N anions with different perfluoroalkyl chain lengths (n = 0, 1, 2, 3, and 4), and the influence of the structural variation on their thermal, ion-diffusive (ionic conductivity and viscosity), ion-concentration (molar concentration and ion association), and solvatochromic (polarity and hydrogen-bond acceptor ability) properties was investigated. T
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