Application of Low-Viscosity Ionic Liquid to the Electrolyte of Double-Layer Capacitors

Ue, Makoto; Takeda, Masayuki; Toriumi, A.; Kominato, Asao; Hagiwara, Rika; Ito, Yasuhiko

doi:10.1149/1.1559069

Cited by 345 publications

(224 citation statements)

References 26 publications

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“…Recently, the so-called room temperature molten salts (RTMSs) have been increasingly employed as substitutes for organic solvents traditionally used as chemical reaction media [1][2][3][4][5][6][7][8][9] . The most common RTMSs are imidazolium 10 and pyridinium 11 derivatives, and in addition, phosphonium 12 or tetralkylammonium 13 1-ethyl-3-methylimidazolium (EMI), because of their low viscosity, high ionic conductivity and low melting point [14][15][16][17][18][19][20][21][22][23] . However, its low cathodic stability is the most critical obstacle for the application to their practical use as an electrolyte.…”

Section: Introductionmentioning

confidence: 99%

High Energy-Density Capacitor Based on Ammonium Salt Type Ionic Liquids and Their Mixing Effect by Propylene Carbonate

Kim

Matsuzawa

Ozaki

et al. 2005

J. Electrochem. Soc.

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Novel ionic liquids comprised of a quaternary ammonium salt type cation have been applied to an electrolyte for high performance electric double-layer capacitors (EDLCs). The novel ionic liquids (IL-B; N, N-diethyl-N-methyl(2-methoxyethyl) ammonium tetrafluoroborate (DEME-BF 4 ) and IL-T; N, N-diethyl-N-methyl(2-methoxyethyl) ammonium bis(trifluoromethylsulfonyl)imide (DEME-TFSI)) are promising candidates for EDLC electrolytes in terms of a high decomposition voltage (wide voltage window) non-flammability, easy handling, non-volatility and low production costs. Notably, the wide voltage windowindicates that IL-B and IL-T are more advantageous in energy density than a typical propylene carbonate-based electrolytes (i.e., TEA-BF 4 /PC) and a conventional imidazolium type ionic liquid (i.e., 1-ethyl-3-methylimidazolium tetrafluoroborate, EMI-BF 4 ). The effectiveness of IL-B and IL-T on the application to EDLC electrolytes has been confirmed by using KOH-activated mesophase pitch-based carbon fibers (MPCFs) as an electrode material. The combination of IL-T (IL-B) and KOH-activated MPCFs has provided 56 F/g (51 F/g) of high specific capacitance at a maximum (1 mA/cm 2 discharge current density, 3.5V charging voltage), which is equivalent to 224 F/g (204 F/g) in a conventional three-compartment measuring system.In addition, the specific capacitance of both ionic liquids has increased proportional to the increase in the applied voltage from 2.5 to 3.5 V, in contrast to the decline observed for TEA-BF 4 /PC at 3.5 V. Furthermore, the mixture of the IL-B exhibiting high viscosity with propylene carbonate (1 M of IL-B in PC) has been found to provide an excellent capacitance behavior comparable to that observed for the pure IL-B. This indicates that the mixture has a great potential for application to EDLC electrolytes, similar to pure IL-B and IL-T.2

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Section: Introductionmentioning

confidence: 99%

High Energy-Density Capacitor Based on Ammonium Salt Type Ionic Liquids and Their Mixing Effect by Propylene Carbonate

Kim

Matsuzawa

Ozaki

et al. 2005

J. Electrochem. Soc.

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“…[1][2][3][4][5][6][7][8][9][10][11] For example, the negligible vapor pressure of ILs enables these electroactive devices to operate at ambient atmosphere with long life cycles; the wide electrochemical window allows these devices to work at higher voltage; and the high ion mobility can lead to fast device response time. All of these properties are highly desirable for electroactive devices such as ionic polymer actuators, 1,[5][6][7][8] supercapacitors, 2 batteries, 10 fuel cells, 11 and dye-sensitized solar cells. 9 Figure 1 presents schematically a typical device configuration for such an electroactive device, which basically has a three-layer structure.…”

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confidence: 99%

Ion transport and storage of ionic liquids in ionic polymer conductor network composites

Liu

Lin

et al. 2010

Applied Physics Letters

101

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We investigate ion transport and storage of ionic liquids in ionic polymer conductor network composite electroactive devices. Specifically, we show that by combining the time domain electric and electromechanical responses, one can gain quantitative information on transport behavior of the two mobile ions in ionic liquids (i.e., cation and anion) in these electroactive devices. By employing a two carrier model, the total excess ions stored and strains generated by the cations and anions, and their transport times in the nanocomposites can be determined, which all depend critically on the morphologies of the conductor network nanocomposites.

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“…1,2 These ILs are expected to be applied as non-flammable ion conductive materials instead of volatile organic solvents. [3][4][5][6][7][8][9][10][11][12][13][14][15] Solidification of ILs is also important for light weight and small ionics devices. For example, thermally stable ion conductive gels have been prepared by mixing ILs (or IL derivatives) with polyelectrolytes containing fixed anionic sites and free cations such as lithium ions.…”

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confidence: 99%

Electrochemical and Spectroscopic Analyses of Lithium Ion Conductive Polymers Prepared by the Copolymerization of Ionic Liquid Monomer with Lithium Salt Monomer

Ogihara

Suzuki

Nakamura

et al. 2006

Polym J

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ABSTRACT:Lithium ion conductive polymer electrolytes have been prepared by copolymerization of an imidazolium salt type ionic liquid monomer; 1-(1-acryloyloxyhexyl)-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide with polyether-containing salt monomer with low glass transition temperature; methacryloyloxy octa(ethylene oxide)-2-sulfobenzoate lithium salt. The ampholytic copolymers were obtained as flexible and transparent films. Their ionic conductivity and glass transition temperature depended on monomer mixing ratio. Some copolymers containing higher lithium salt monomer fraction than that of ionic liquid monomer had lithium ion transference number exceeding 0.5. Against these, high ionic conductivity was found in the copolymers with high ionic liquid monomer fraction. Copolymerization of monomers containing either ionic liquid unit or lithium salt unit provided ion conductive polymers with a wide variety of conductive characteristics. [DOI 10.1295/polymj.38.117] KEY WORDS Ionic Liquid / Polymer Electrolyte / Lithium Ion Transference Number / Raman Spectroscopy / Ionic liquids (ILs) are usually realized as highly ion conductive, non-volatile and non-flammable media. 1,2These ILs are expected to be applied as non-flammable ion conductive materials instead of volatile organic solvents.3-15 Solidification of ILs is also important for light weight and small ionics devices. For example, thermally stable ion conductive gels have been prepared by mixing ILs (or IL derivatives) with polyelectrolytes containing fixed anionic sites and free cations such as lithium ions. 7,16 The gel based ILs often had a high ionic conductivity depending on the ILs content. The gel type polymers composed of poly-(methacryloyloxy octa(ethylene oxide)-2-sulfobenzoate lithium salt) and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([EMIm][TFSI]) had a lithium ion transference number (t Li+ ) below 0.1 in our preliminary experiments. This is comprehended as the competitive migration of lithium cation, TFSI anion, and component ions. Thus our goal is to increase the ion transference number of polymers without serious drop of the ionic conductivity.To make polyelectrolytes with high lithium ion conductivity, we must suppress the migration of component ions of ILs so that only the lithium cation in the IL matrix is transported. One method to realize this is the use of a zwitterion that is composed of an onium cation and an anion tethered with molecular spacer. [17][18][19] Another is the use of polymerized ILs, in which the IL component ions are fixed on the polymer chains. [20][21][22] The advantages of polymerized ILs are the structural diversity of the polymers and the tunability of conduction characteristics as well as mobile ion species by changing polymer structure. 22Therefore, lithium ion conductive polymers should be synthesized by copolymerization of two monomers with one having an IL structure and the other having a lithium salt structure. EXPERIMENTAL MaterialsThe sources of the chemicals were as follows. N...

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Application of Low-Viscosity Ionic Liquid to the Electrolyte of Double-Layer Capacitors

Cited by 345 publications

References 26 publications

High Energy-Density Capacitor Based on Ammonium Salt Type Ionic Liquids and Their Mixing Effect by Propylene Carbonate

High Energy-Density Capacitor Based on Ammonium Salt Type Ionic Liquids and Their Mixing Effect by Propylene Carbonate

Ion transport and storage of ionic liquids in ionic polymer conductor network composites

Electrochemical and Spectroscopic Analyses of Lithium Ion Conductive Polymers Prepared by the Copolymerization of Ionic Liquid Monomer with Lithium Salt Monomer

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