All issues
Volume 2003 (2003)
- Issue 210 Pages 199-
- Issue 209 Pages 159-
- Issue 208 Pages 109-
- Issue 207 Pages 65-
- Issue 206 Pages 2-
Volume 2003, Issue 210
Displaying 1-11 of 11 articles from this issue
- |<
- <
- 1
- >
- >|
-
Nobuyuki Nishimiya, Koichi Ishigaki, Takeo Ebina, Hirofumi Takikawa, Y ...2003 Volume 2003 Issue 210 Pages 199-204
Published: December 22, 2003
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSSWCNTs (Single-Walled Carbon Nanotubes) were fabricated by means of a torch arc method and a conventional arc method with graphite rods containing 4.2mol% of Ni and 1.0mol% of Y employed as anodes.
A necessary condition for SWCNTs to sorb significant amounts of hydrogen would be high G/D ratios, that is, the intensity ratios of Raman G band peaks to D band peaks must exceed 10. When this condition was satisfied, hydrogen capacities of most SWCNTs increased with specific surface areas. However, such SWCNTs that did not contain sufficient amounts of Y on surfaces tended to show lower capacities than expected from specific surface areas.
An arbitrary lot of SWCNTs that satisfied the high G/D ratio condition sorbed 6.6wt% of hydrogen at 295K under 3.1MPa, while their hydrogen capacity under 100kPa was as less as 0.12wt%.
Novel blue shifts of G band and breathing mode peaks were observed by in situ Raman spectrometry under hydrogen. These shifts were completely reversible and would be practically used to detect hydrogen sorption on SWCNTs. The intensity ratios of breathing mode peaks to G band also varied with hydrogen pressure probably owing to hydrogen sorption.View full abstractDownload PDF (928K) -
Double-layer Capacitance PerformancesYong-Jung Kim, Masato Kojima, Yohei Horie, Yoshimura Ohta, Morinobu En ...2003 Volume 2003 Issue 210 Pages 205-210
Published: December 22, 2003
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSMilled mesophase pitch-based carbon fiber (mMPCF) was applied as a polarizable electrode for electric double layer capacitors (EDLCs). The mMPCF showed quite different activation behavior between physical and chemical activation methods. The effect of the KOH mixing ratio was examined and the influence on the asymmetric lattice structure also was considered. Furthermore, hydrogenation effect on the capacitance behavior is also shown. The reduction reaction by hydrogen did not affect the pore structure which material has, but it was effective to remove only oxygen containing functional group which exists in the surface. Hydrogenation was effective to improve the most important characteristic in practical application, such as cycle stability, coulomb efficiency.View full abstractDownload PDF (1136K) -
Shinsaku Minoura, Sachie Nakatani, Tatsuya Morimoto, Hirokazu Oda2003 Volume 2003 Issue 210 Pages 211-216
Published: December 22, 2003
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe present study discussed the effects of electrolytes and pore surface area and/or oxygen functional groups of activated carbon fiber (ACF) electrodes on their electric capacity. The electric capacity was affected by the electro-conductivity of electrolytes and increased with increase in oxygen functional groups. It depended more on oxygen functional groups than on BET surface area. However, ACFs which have higher acidity exhibited more remarkable decrease in capacity with current density, due to the increase of internal resistance. At the greatest 30% of increase in electric capacity was obtained by using ACFs with different amount of oxygen functional groups between the positive electrode and the negative one.View full abstractDownload PDF (773K) -
Takayuki Doi, Kazuhisa Takeda, Tomokazu Fukutsuka, Yasutoshi Iriyama, ...2003 Volume 2003 Issue 210 Pages 217-220
Published: December 22, 2003
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSHighly graphitized carbonaceous thin films prepared by plasma-assisted chemical vapor deposition were surface-modified by electropolymerization of pyrrole. The electrochemical properties of the films were studied by cyclic voltammetry and AC impedance spectroscopy. Irreversible cathodic current above 0.6V vs. Li/Li+ was significantly decreased in the cyclic voltammograms, indicating that the surface modification of carbonaceous materials by electropolymerization should be effective for decrease in irreversible capacities in lithium-ion batteries.View full abstractDownload PDF (557K) -
Akinori Muto, Junichi Arima, Thallada Bhaskar, Yusaku Sakata2003 Volume 2003 Issue 210 Pages 221-224
Published: December 22, 2003
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSIn this paper, the method to find the optimal preparation condition of porous carbon material for capacitor electrode with considering carbon yield was proposed. Biomass (woodchips) and a strong cation exchange resin were used as carbon precursors. Porous carbon materials were prepared by carbonization in N2 stream and by CO2 activation. A new method was proposed for selection of promising process parameters, such as carbonization/activation temperature and period, by measuring specific surface area and capacitance of the carbon materials. The specific capacitances of the carbon prepared from both raw materials were almost the same. However, the cation exchange resin was favorable as a precursor for capacitor electrode in the viewpoint of carbon yield. The optimal preparation condition also was discussed in detail.View full abstractDownload PDF (637K) -
Masahiro Toyoda, Yasushi Soneda, Yuji Tani, Hideyuki Takagi, Michio In ...2003 Volume 2003 Issue 210 Pages 225-230
Published: December 22, 2003
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSElectric double layer capacitors (EDLC) using carbon materials electrodes is one of anticipated energy storage device because of its superior characteristics have been employed for the micro electronics, such as memory backup system. However, it is necessary to improve the various properties of EDLC for the future applications such as the energy storage for the small scale distributed energy system and the electric vehicle. The capacitance of electrode materials such as activated carbons in powder or fiber form is depending mainly on the surface area of its carbons, although it was often observed that the higher surface area carbons obtained from the same precursor did not show the larger capacitance per unit weight or surface area. In this study, the exfoliated carbon fibers (ExCFs) synthesized through the rapid heating of the intercalation compounds of carbon fibers were examined as capacitor electrodes. The measurements of EDLC behavior of its ExCFs were performed using standard three-electrode cell with 1mol/dm3 and 18mol/dm3 sulfuric acid electrolyte. The capacitance reached 160 and 555F/g in 1mol/dm3 and 18mol/dm3 H2SO4 electrolyte, respectively, even though ExCFs had relativity small surface area of about 300m2/g. Its capacitance slightly depends on specific surface area of ExCFs in 1mol/dm3 H2SO4 electrolyte. On the other hands, the capacitance of ExCFs obtained in 18mol/dm3 H2SO4 electrolyte was significantly large. The most provable chemical reaction in 18mol/dm3 H2SO4 to give large capacitance is intercalation of H2SO4 molecules into the ExCFs having developed carbon layers stacking. The intercalation reaction of acid molecules is known to possible only with well crystallized carbon materials. All ExCFs were found to be split into a number of thin filaments along the original fiber axis. From its TEM observation, these filaments were recognized to consist of thin sheets. In these sheets, hexagonal carbon layers were found to be oriented along the original fiber axis. This structural feature having well-oriented graphite layers after exfoliation might be important for giving a large capacitance for EDLC. The intercalation of H2SO4 molecules into ExCFs in concentrated electrolyte might be responsible for resultant large capacitance of EDLC.View full abstractDownload PDF (1300K) -
Zempachi Ogumi, Takeshi Abe, Minoru Inaba, Soon Ki Jeong2003 Volume 2003 Issue 210 Pages 231-235
Published: December 22, 2003
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSIn lithium ion batteries, graphite and graphitized carbonaceous materials have been mainly used as negative electrodes because of their acceptable high capacity, very flat potential as low as Li metal, etc. One of the problems for graphite negative electrode is the use of propylene carbonate (PC)-based electrolyte. In PC-based electrolyte, electrochemical lithium ion intercalation into graphite can not take place. PC-based electrolyte gives wider potential window and lower melting point compared with ethylene carbonate-based electrolyte. Therefore, many researchers have focused the use of PC-based electrolyte. Here we summarized the work on graphite electrode in PC-based electrolytes and discussed the use of PC-based electrolyte for lithium ion batteries.View full abstractDownload PDF (867K) -
Hiroshi Shioyame, Kazuaki Yasuda2003 Volume 2003 Issue 210 Pages 236-242
Published: December 22, 2003
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSThe polymer electrolyte fuel cell (PEFC) has recently received much attentions because of the several advantages it offers for transportation, stationary and portable applications. This paper reviews carbon materials used for electrocatalyst of PEFC. The effects of carbon support on the functions of electrocatalyst are shown, which govern the performance of PEFC. New carbons such as nanotubes are also discussed as a candidate for novel catalyst support.View full abstractDownload PDF (1290K) -
From the Carbon Science ViewpointMorinobu Endo, Takuya Ikeda, Masakazu Narita, Shinya Ozaki, Toru Nishi ...2003 Volume 2003 Issue 210 Pages 243-249
Published: December 22, 2003
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSEnergy devices, such as high performance secondary battery and fuel cell, are the most important technology as the base of the society in the 21st century, which are strongly related to information, energy and environment tech-nology. For example, recently developed mobile computational era has been largely contributed to the high performance Li ion battery (LIB), providing the light weight and small sized rechargeable battery. The typical energy devices are LIB, electric double layer capacitor, direct methanol and polymer electrolyte fuel cells, which are consisted of carbon elements as a major and key component. Namely, both of carbon science and technology can contribute enormously to the innovation of the new century technology. In the present paper, the recent development and future possibility of such carbon-based energy devices are demonstrated and discussed by comparing the performances with each energy devices.View full abstractDownload PDF (1639K) -
Isao Mochida, Sang-Ick Lee, Satoshi Mitani, Seong-Ho Yoon, Yozo Korai2003 Volume 2003 Issue 210 Pages 250-257
Published: December 22, 2003
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSCurrent performances and surface functions of active carbon as an electrode for super capacitor were surveyed to review the working mechanism on the electric double layers formed on the carbon surface. Future development of active carbons for higher performance is discussed based on their structural hierarchy of pore and pore wall.View full abstractDownload PDF (1677K) -
[in Japanese]2003 Volume 2003 Issue 210 Pages 262-266
Published: December 22, 2003
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSDownload PDF (852K)
- |<
- <
- 1
- >
- >|