1996 Fiscal Year Final Research Report Summary
PROPERTIES AND MANIFESTATION OF FUNCTIONALITY OF CARBON-pi ELECTRON SYSTEM.
| Project/Area Number |
07650986
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
工業物理化学
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| Research Institution | SHINSHU UNIVERSITY |
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Principal Investigator |
TOUHARA Hidekazu SHINSHU UNIVERSITY,FAC.TEXTILE SCIENCE AND TECHNOLOGY,PROFESSOR, 繊維学部, 教授 (40026141)
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| Co-Investigator(Kenkyū-buntansha) |
OKINO Fujio SHINSHU UNIVERSITY,ASSOCIATE PROFESSOR, 繊維学部, 助教授 (60214037)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Activated Carbon Fiber / Mesocarbon Microbeads / Fluorination / Electronic Structure / Carbon Negative Electrode / Secondary Lithium Battery / Perturbation of pi-electron Systems |
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| Research Abstract |
1.Electronic and Lattice Structure of Fluorine-Graphite Compounds
The changes in electronic and lattice structures of carbon-pi electron systems upon interactions with F_2 have been investigated by electron spectroscopies of NEXAFS and XPS,TEM and electrochemical methods. The controlled interactions give fluorine-carbon materials with diverse properties ranging from high electrical conductors to insulators. Based on these results, schematic band models of fluorine-carbon materials have been proposed.
2.Fluorination of Activated Carbon Fibers (ACF)-Fluorinated Micropores-
Interaction of elemental fluorine with ACF at 100ﾟC has given surface fluorinated ACF (F-ACF) with the composition C_<1.4>F.The C-F bonding nature in F-ACF is covalent, and the marked hydrophobic nature is given to the microporous ACF.
The pore width does not greatly change due to the fluorination, however, the micropore volume is significantly decreased from 0.65 ml/g (ACF) to 0.19 ml/g (F-ACF).
3.Fluorination of Mesocarbon Microbeads (MCMB_s) and Carbon Negative Electrode Materials for Secondary Lithium Batteries.
Mesocarbon microbeads heat treated at 1000 (MCMB-1000) and 2800ﾟC (MCMB-2800) react with elemental fluorine at rather lower temperatures ranging from 25 to 200ﾟC to produce C_xF (50<greater than or equal>x<greater than or
Fluorine rich materials (x<1) are covalent compounds but C-F bonds are semi-ionic in character for fluorine poor compounds (x>6). The X-ray diffraction lines of MCMB_s were unchanged by fluorination. These XRD data indicate that the bulk pi-electron systems are preserved in MCMB_s derived C_xF and that only the surface fluorination does occur.
It has become apparent that optimal fluorine treatments of MCMB_s increase the rechargeable capacities of MCMB electrodes for secondary lithium batteries.
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