Electrochemistry
Online ISSN : 2186-2451
Print ISSN : 1344-3542
検索
OR
閲覧
検索
75 巻 , 8 号
選択された号の論文の28件中1~28を表示しています
    • |<
    • <
    • 1
    • >
    • >|
論文特集号 ますます広がるキャパシタの世界とその課題
展望
Headline
  • Makoto UE
    75 巻 (2007) 8 号 p. 565-572
    公開日: 2012/03/20
    ジャーナル オープンアクセス
    A capacitor is an electrical device that can store energy in an electric field between a pair of closely spaced conductors. Its application as an energy storage device —an alternative to rechargeable batteries— has been receiving considerable attention. There are chemical capacitors using liquid electrolytes such as aluminum electrolytic capacitors and double-layer capacitors, and they utilize quaternary ammonium salts in their nonaqueous electrolytes. After a brief explanation of the working principles of these chemical capacitors and their requirements for electrolytes, the practical applications of quaternary ammonium salts for aluminum electrolytic capacitors and double-layer capacitors are reviewed from the historical and technological viewpoints based on research conducted in our laboratory.
    抄録全体を表示
コミュニケーション
報文
  • Kaoru UENO, Larry DOMINEY, Robert S. ALWITT
    75 巻 (2007) 8 号 p. 622-627
    公開日: 2012/03/20
    ジャーナル オープンアクセス
    The capacitance recovery of Ta capacitor using poly(3,4-ethylenedioxythiophene) (PEDOT) was evaluated. Capacitance recovery is defined as the ratio of the capacitance of Ta/oxide/PEDOT/Ag to that of Ta/oxide measured in aqueous electrolyte solution. The capacitance recovery was strongly dependent on the oxide formation voltage. From the analysis of this dependence we found an additional capacitance in series with the oxide capacitance which was independent of oxide formation voltage, and was present at the oxide/PEDOT interface. This additional capacitance was postulated by the presence of a depletion layer and poor contact because of the presence of polymerization byproduct at the oxide/PEDOT interface. However, the phenomenon of the additional series capacitance did not match well with the depletion layer capacitance calculated from semiconductor theory assumption.
    抄録全体を表示
  • Tetsuya SUKIZAKI, Shuhei FUKUDA, Taishi YAMAGUCHI, Kenta FUJII, Ryo KA ...
    75 巻 (2007) 8 号 p. 628-634
    公開日: 2012/03/20
    ジャーナル オープンアクセス
    5-Azonia-spiro[4.4]nonane tetrafluoroborate [(CH2)4N(CH2)4]+BF4 is dissolved in dimethyl carbonate (DMC) to yield two liquid phases, DMC and salt-rich DMC solutions. The molecular structure of the [(CH2)4N(CH2)4]+ ion in the crystalline state and in the salt-rich DMC solution was studied by means of Raman spectroscopy at 298 K and theoretical DFT calculations. The [(CH2)4N(CH2)4]+ ion involves two pyrrolidinium (CH2)4N rings bridged through the N atom, and each pyrrolidinium ring involves various types of conformation. Theoretical DFT calculations for the [(CH2)4N(CH2)4]+ ion show that the distorted envelope-envelope conformers of the type E1-E1 and E1-E3 give relatively small energies. Observed Raman spectra of [(CH2)4N(CH2)4]+BF4 crystals and the salt-rich DMC solution were satisfactorily explained in terms of the favorable presence of the sole envelope-envelope conformer of the type E1-E1.
    抄録全体を表示
  • Sang-Wook WOO, Kaoru DOKKO, Hiroyuki NAKANO, Kiyoshi KANAMURA
    75 巻 (2007) 8 号 p. 635-640
    公開日: 2012/03/20
    ジャーナル オープンアクセス
    Bimodal porous carbons consisting of interconnected macropores and spherical mesopores, were prepared by colloidal crystal templating method. The template was prepared by evaporation process of suspensions containing monodisperse poly[styrene-(co-2-hydroxyethyl methacrylate)] (PSHEMA) latex and colloidal silica in water. The carbonization of PSHEMA at 1000°C under inert atmosphere provided very thin carbon layer on the colloidal silica in the template, and the macropore corresponding to the PSHEMA particle size were formed simultaneously. After this procedure, bimodal porous carbons were obtained by removing the silica particles with hydrofluoric acid. Three kinds of bimodal porous carbons were prepared using PSHEMA latex of 450 nm and colloidal silica with three different average diameters of 10∼20 nm, 40∼50 nm, and 70∼100 nm, respectively. Bimodal porous structure was observed with a field emission-scanning electron microscope. Nitrogen adsorption/desorption measurements revealed that the prepared samples involved macropore and mesopore with small amount of micropore. The bimodal porous carbons were electrochemically evaluated as a negative electrode of lithium-ion capacitor in ethylene carbonate and diethyl carbonate containing 1 mol dm−3 LiClO4. The bimodal porous carbon prepared using silica of 10∼20 nm showed a large capacitance of 360 F g−1 at a high current density of 7.4 A g−1.
    抄録全体を表示
  • Masayuki MORITA, Naoki OHSUMI, Nobuko YOSHIMOTO, Minato EGASHIRA
    75 巻 (2007) 8 号 p. 641-644
    公開日: 2012/03/20
    ジャーナル オープンアクセス
    Novel non-aqueous proton (H+)-conducting polymeric gel systems have bee proposed for utilization as quasi-solid electrolytes in electrochemical capacitors. The gel systems consist of poly(vinylidenedifluoride) (PVdF) or poly(vinylidenedifluoride-co-hexafluoropropylene) (PVdF-HFP) matrix polymer swollen with dimethylformamide (DMF) solutions containing phosphoric acid (H3PO4) or trifluoromethanesulfonic acid (CF3SO3H). High ionic conductivity of 4.5 mS cm−1 was obtained at 60°C for a PVdF-HFP-based polymeric gel containing 85 mass% of 0.5 M CF3SO3H/DMF with sufficient mechanical stability over the temperature range of 20–60°C. Redox process of hydrous ruthenium oxide, RuO2·xH2O, gave high pseudo-capacitance in the PVdF-HFP-based polymeric gel. The pseudo capacitance behavior was somewhat influenced by the composition of electrode/electrolyte interface. The discharge capacitance of ca. 350 F g−1 (with respect to the mass of the oxide) was obtained for PVdF-HFP-based gel using RuO2·xH2O electrode prepared by a “wet process”.
    抄録全体を表示
  • Wataru SUGIMOTO, Toshiaki OHTA, Katsunori YOKOSHIMA, Yoshio TAKASU
    75 巻 (2007) 8 号 p. 645-648
    公開日: 2012/03/20
    ジャーナル オープンアクセス
    The effect of the H2SO4 concentration and cell temperature towards the pseudocapacitive behavior of layered ruthenic acid hydrate, H0.2RuO2.1·nH2O, was examined. The increase in H2SO4 concentration resulted in a drastic decrease in the redox pair observed at 0.65 V vs. RHE, while the increase in cell temperature had little effect on this redox pair. The redox pair centered at ∼0.85 V vs. RHE was less dependent on the H2SO4 concentration and the charge associated with this peak increased with increasing cell temperature. It is suggested that the redox peak observed at ∼0.65 V vs. RHE is related to the adsorption of SO42− ions on the outer surface of the microsized particles. The redox pair observed at ∼0.85 V vs. RHE is attributed to the penetration of protons or hydrated protons. The effect of cell temperature was negligible for nanoparticulate RuO2·xH2O, which indicates the difference in the charge storage mechanism of layered H0.2RuO2.1·nH2O and nanoparticulate RuO2·xH2O.
    抄録全体を表示
  • Masayuki ITAGAKI, Satoshi SUZUKI, Isao SHITANDA, Kunihiro WATANABE
    75 巻 (2007) 8 号 p. 649-655
    公開日: 2012/03/20
    ジャーナル オープンアクセス
    The electrochemical impedance Z and complex capacitance C for typical equivalent circuits were summarized systematically in order to support the frequency domain analysis of electric double layer capacitance (EDLC). In the present paper, the impedance and the complex capacitance were calculated in the case that the electrochemical response of porous electrode was presented by a transmission line model (TLM). The loci of Z and C on the complex were divided into the lumped constant and distributed constant ranges in low and high frequency ranges, respectively. The complex capacitance plot was superior to obtain the capacitance of porous electrode than the impedance plot.
    抄録全体を表示
  • Noritoshi NANBU, Satoko ITO, Yukio SASAKI
    75 巻 (2007) 8 号 p. 656-663
    公開日: 2012/03/20
    ジャーナル オープンアクセス
    Tetraethylammonium bis(oxalato)borate (TEABOB), which is free from halogens, has the potential for use in electric double-layer capacitors (EDLCs). We have used a transmission-line network of finite length as the equivalent circuit of the average pore of an activated carbon electrode and derived the theoretical equation for a constant-current (CC) charge. We evaluated the performance of EDLCs by comparing the theoretical and the experimental charge curves. A 2025-type coin cell using TEABOB showed double-layer capacitance comparable to that obtained for tetraethylammonium tetrafluoroborate (TEABF4). A very small distance between activated carbon electrodes in the EDLC may compensate for low ionic mobility of TEABOB in the bulk of the solution. The degree of ionic dissociation of TEABOB in the pores of the activated carbon electrode may not be appreciably lower than predicted from the bulk properties of the solution.
    抄録全体を表示
技術報文
 
    • |<
    • <
    • 1
    • >
    • >|
feedback
Top