| Project/Area Number |
15360510
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Energy engineering
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
YAO Takeshi KYOTO UNIVERSITY, Graduate School of Energy Science, Professor, エネルギー科学研究科, 教授 (50115953)
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| Co-Investigator(Kenkyū-buntansha) |
HIBINO Mitsuhiro KYOTO UNIVERSITY, Graduate School of Energy Science, Associate Professor, エネルギー科学研究科, 助教授 (20270910)
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| Project Period (FY) |
2003 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥15,500,000 (Direct Cost: ¥15,500,000)
Fiscal Year 2004: ¥6,100,000 (Direct Cost: ¥6,100,000)
Fiscal Year 2003: ¥9,400,000 (Direct Cost: ¥9,400,000)
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| Keywords | Lithium ion battery / Layered compound / Intercalated graphite / X-ray diffraction / Rietveld analysis / Stacking manner / Orientation state / In-plane structure / グラファイト / X線回析 / ヒジテリシス |
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| Research Abstract |
Lithium secondary batteries have been widely investigated due to their advantageous characteristics of light-weight, high energy density, high voltage and so on. For further progress such as reduction of cost and improvement of safety, development of materials of cathode and anode is crucial. For both cathode and anode, some of layered compounds are attractive in terms of specific capacity and cyclability. Graphite are commonly served as anode materials. Vanadium oxide gel and LiV_3O_8, which is one of so-called oxide bronze, employ layer structure and draw attentions as cathode materials. Their detail structure, however, is often difficult to be determined on the grounds that tendency of highly oriented state of their crystalline particles causes poor information of X-ray diffraction. As a result, structural control has been not enough so far. In this study, our purpose was to establish the structure of layered compounds suitable for high rate electrochemical reaction on the basis of detail structural analysis of them. That is ready to be applied to the electrode materials of lithium ion batteries. We prepared electrochemically a series of lithium intercalated graphite with various lithium content and analyzed structurally in the direction (c-direction) perpendicular to basal planes by X-ray diffraction using highly oriented sample. For the one-dimensional structural refinement, the highly oriented sample was adequate. Then we successfully determined the stacking manner of graphene layers using our originally developed one-dimensional Rietveld analysis system. We could discuss in-plane lithium distribution structure, as well as c-direction structure, depending on lithium intercalation level. Furthermore we found that the behavior of stage structure was hysteretic between in the process of electrochemical lithium insertion and extraction. The hysteresis was considered to be closely related to the structural variation of in-plane lithium arrangement.
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