2006 Fiscal Year Final Research Report Summary
New ate-complex type of lithium salts and their application to wide temperature working secondary batteries
| Project/Area Number |
16350099
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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 |
Functional materials/Devices
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| Research Institution | Shizuoka University |
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Principal Investigator |
FUJINAMI Tatsuo Shizuoka University, Department of Materials Science and Chemical Engineering, Professor, 工学部, 教授 (80022010)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Lithium secondary battery / Lithium salt / Ionic liquid / Ionic conductivity / Electrolyte / Polymer electrolyte / Ate complex / Borate |
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| Research Abstract |
New liquid lithium ate-complex salts were synthesized as new ionic liquids and their ionic conductivity, lithium transference numbers, and electrochemical stability were investigated. Charge-discharge cycle performances of the lithium secondary battery were also tested using the liquid lithium salts. Lithium borates exhibited high ionic conductivity because highly dissociative properties of borates which was estimated by calculation results on partial charges. Enhanced conductivity was observed for mixing salts systems. Lithium secondary battery composed of novel ionic liquid, LiF_3BO(CH_2CH_2O)_nCH_3 LiCoO_2 or LiNi_<0.8>Co_<0.2>O_2 cathode, and lithium metal anode showed good charge-discharge cycle performance at r.t., 50 and 100 ℃. At lower temperatures, ionic conductivity of the salt was enhanced and battery performance at room temperature was improved by addition of plasticizer. Good polymer electrolytes were obtained by dissolving the liquid salt in PEO. In addition, new polymer electrolyte system was found by using composite of an insoluble ate complex lithium salt and PEO which formed new ionic conduction phase in interface region. This polymer electrolyte system exhibited a high lithium ion transference number, and a good battery performance was obtained by addition of plasticizer. These polymer electrolyte systems are expected as new electrolytes for the next generation of lithium polymer batteries.
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