TANSO
Online ISSN : 1884-5495
Print ISSN : 0371-5345
ISSN-L : 0371-5345
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Volume 2009, Issue 240
Displaying 1-9 of 9 articles from this issue
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Research Papers
  • Lithium ion insertion/extraction performance of Si/C/O composites formed from polyimides containing silicone
    Shota Saito, Takashi Kasashima, Koji Fushimi, Hidetaka Konno
    Article type: Research Paper
    2009 Volume 2009 Issue 240 Pages 207-212
    Published: November 13, 2009
    Released on J-STAGE: December 15, 2010
    DOIhttps://doi.org/10.7209/tanso.2009.207
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    Si/C/O composites were formed by carbonization of Kapton type polyimide films containing 0–10 at% Si. About 24 mass% of Si was present in the composite derived from the polyimide containing 7 at% Si at 1350°C and, by 29Si MAS NMR, they were mainly Si(O)4 type components around −110 ppm with unidentifiable components in a range of −100 to −20 ppm. This composite showed the best performance of Li+ ion insertion/extraction: the coulomb efficiency was nearly 100% except for the 1st cycle and the extraction capacities were 648 mA h g−1 after 10 cycles at 50 mA g−1 and 393 mA h g−1 after 50 cycles at 500 mA g−1, and the latter was increased to ca. 470 mA h g−1 by preliminary cycles at low current densities. After 10 cycles at 50 mA g−1 the components around −110 ppm almost disappeared from the NMR spectrum and a broad and noisy band was observed in a range of −100 to −50 ppm. Since sub-micrometer fused silica particles did not react as the composites performed, the components around −110 ppm are not necessarily silica. The mechanism of reversible insertion/extraction of Li+ ion for the composites was not completely clarified, but the results by cyclic voltammetry and MAS NMR left room for doubt about an alloying/dealloying mechanism between Si and Li.
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  • Production and advantages of carbon-coated graphite for the anode of lithium ion rechargeable batteries
    Kazuhito Hoshi, Naoto Ohta, Katsuhide Nagaoka, Shingo Bitoh, Akio Yama ...
    Article type: Research Paper
    2009 Volume 2009 Issue 240 Pages 213-220
    Published: November 13, 2009
    Released on J-STAGE: December 15, 2010
    DOIhttps://doi.org/10.7209/tanso.2009.213
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    Carbon coating of substrate graphite powder was carried out by carbonizing the mixture with poly(vinyl alcohol) at 600~1500°C. From the measurement of anode performance on the carbon-coated graphite prepared from 21 graphite substrates, crystallite thickness with three-dimensional regular stacking and BET surface area of the substrate graphite were used as parameters for the selection of the substrate graphite. The production scale of carbon-coated graphite powders was successfully increased up to about 1000 kg. Carbon-coated graphite was shown to give a smaller irreversible capacity for the first charge/discharge cycle than graphite without a carbon coating and could be used in an electrolyte solution containing a small amount of propylene carbonate (PC), of which anode performance was almost comparable with those in the solutions without PC. With a high discharge rate of about 10 mA/cm2, carbon-coated graphite gave better anode performance, larger discharge and smaller irreversible capacities, than the graphite without a carbon coating.
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  • Formation of a solid electrolyte interface on single wall carbon nanotube electrodes in lithium ion batteries
    Hisatoshi Koshikawa, Hiroatsu Todoriki, Atsushi Kondo, Yoshiyuki Hatto ...
    Article type: Research Paper
    2009 Volume 2009 Issue 240 Pages 221-225
    Published: November 13, 2009
    Released on J-STAGE: December 15, 2010
    DOIhttps://doi.org/10.7209/tanso.2009.221
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    The formation of a solid electrolyte interface (SEI) at the surface of a SWNT electrode was investigated by SEM, TEM, XRD, and Raman spectroscopy. These analyses were carried out at different charge-discharge cycles, showing the cycle dependent character of the SEI formation. The changes in chemical species of SEI with increased number of cycles have been examined. This study shows by XRD, that inorganic species of SEI are LiF and Li2CO3, and that the SEI formation depends on the number of discharge-charge cycles.
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Notes
  • Influence of heating duration on high-voltage charging durability of an activated carbon electrode for electric double layer capacitors
    Soshi Shiraishi, Kaoru Sunaga, Takaaki Suganuma
    Article type: Note
    2009 Volume 2009 Issue 240 Pages 226-229
    Published: November 13, 2009
    Released on J-STAGE: December 15, 2010
    DOIhttps://doi.org/10.7209/tanso.2009.226
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    Phenolic-resin based steam-activated carbon fiber (ACF) for electric double layer capacitors was subjected to heattreatment at 1500°C in nitrogen. The dependence of the pore structure and the capacitance retention rate after high voltage charging (3 V, 100 h, 70°C) on the heating duration was investigated using a two-electrode cell with propylene carbonate electrolyte. The micropore-shrinkage and the removal of the oxygen-containing surface functionalities of the ACF were accomplished within a short time (5 seconds) by the heat-treatment, however a longer time (1 hour) was necessary to improve the capacitance retention rate. The Raman analysis revealed that the local ordering structure changed slowly by heat-treatment at 1500°C, suggesting the sufficiently long heat-treatment essential to the improvement of the capacitance retention rate.
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Integrated Paper
  • Contributions of micropores and mesopores in electrode carbon to electric double layer capacitance
    Lihong Wang, Michio Inagaki, Masahiro Toyoda
    Article type: Integrated Paper
    2009 Volume 2009 Issue 240 Pages 230-238
    Published: November 13, 2009
    Released on J-STAGE: December 15, 2010
    DOIhttps://doi.org/10.7209/tanso.2009.230
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    Performance of electric double layer capacitors (EDLCs) was studied by using different microporous and mesoporous carbons in positive and negative electrodes (symmetric and asymmetric EDLCs) in non-aqueous and aqueous electrolytes (1M TEMABF4/PC and 1M H2SO4, respectively). Microporous carbons were selected from commercially available activated carbons and mesoporous carbons from laboratory-made ones. Asymmetric EDLCs consisting of microporous carbon AC-5 and different mesoporous carbons XX in either the positive or negative electrode (AC-5/XX and XX/AC-5) showed a predominant contribution of the negative electrode, where cations of electrolyte are adsorbed, to capacitance and rate performance. Contributions of the surface due to micropores and that due to other large pores to the EDLC capacitance were separately evaluated as a function of current density for the charge/discharge cycle in two electrolytes. The contribution of microporous surface, Cmicro., is smaller than that of the surface of other large pores, Cext., depending more markedly on current density during the charge/discharge cycle. The values of Cext./Cmicro. are in the range 2.4~2.8 in H2SO4, but 4.3~7.2 in TEMABF4/PC. Cmicro. in TEMABF4/PC is smaller than that in H2SO4, suggesting a smaller contribution of micropores to capacitance in TEMABF4/PC.
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Review Papers
  • Electromechanical polymer actuators using nano-sized carbon
    Satoshi Mitani, Kinji Asaka
    Article type: Review Papers
    2009 Volume 2009 Issue 240 Pages 239-244
    Published: November 13, 2009
    Released on J-STAGE: December 15, 2010
    DOIhttps://doi.org/10.7209/tanso.2009.239
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    Electro-active polymer actuators are expected to have use in medical devices, prosthetic devices, the field of robotics, etc. This review introduces electro-active polymer actuators using carbon nanotubes, and explains configurations of the actuator and the drive principle. The authors studied the effect of various ionic liquids and adding an activated carbon nanofiber. It was found that the performance of the actuator depend on the properties of the ionic liquids and the carbon structure.
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  • Proton conductivity of fullerene derivatives and their composites
    Hiroshi Shioyama
    Article type: Review Papers
    2009 Volume 2009 Issue 240 Pages 245-249
    Published: November 13, 2009
    Released on J-STAGE: December 15, 2010
    DOIhttps://doi.org/10.7209/tanso.2009.245
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    Fullerene derivatives such as polyhydroxyfullerene C60(OH)n (n~12) show proton conductivity. This review introduces the properties of proton conducting fullerenes and their composite membranes with Nafion. These proton conductors have advantages under low humidity conditions. Their applications for the proton conducting membrane of a polymer electrolyte fuel cell (PEFC) and mass-flow controller are also discussed.
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  • Basic characterization of lithium ion capacitor
    Soshi Shiraishi
    Article type: Review Papers
    2009 Volume 2009 Issue 240 Pages 250-252
    Published: November 13, 2009
    Released on J-STAGE: December 15, 2010
    DOIhttps://doi.org/10.7209/tanso.2009.250
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    The author addresses the fabrication method and the Ragon plot measurement of lithium ion capacitor for basic characterization. The preparation of activated carbon electrode as positive electrode is the same as that for electric double layer capacitor. The Ragon plot can be obtained by the constant power mode using the two-electrode cell composed of activated carbon electrode (positive electrode) and Li+-doped graphite electrode (negative electrode). It is useful for laboratory-scale basic characterization to pre-dope Li+ ion to the graphite electrode using a different other two-electrode cell from that for the Ragon plot measurement.
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