| Project/Area Number |
10450333
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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 |
無機工業化学
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| Research Institution | SAGA UNIVERSITY |
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Principal Investigator |
YOSHIO Masaki SAGA UNIVERSITY, FACULTY OF SCIENCE & ENGINEERING, PROFESSOR, 理工学部, 教授 (60037885)
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| Co-Investigator(Kenkyū-buntansha) |
ISONO Ken-ichi SAGA UNIVERSITY, FACULTY OF SCIENCE & ENGINEERING, RESEARCH ASSOCIATE, 理工学部, 助手 (20232374)
NOGUCHI Hideyuki SAGA UNIVERSITY, FACULTY OF SCIENCE & ENGINEERING, PROFESSOR, 理工学部, 教授 (60093978)
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥11,000,000 (Direct Cost: ¥11,000,000)
Fiscal Year 2000: ¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1999: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1998: ¥6,600,000 (Direct Cost: ¥6,600,000)
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| Keywords | LITHIUM ION BATTERY / CATHODE MATERIAL / MANGANESE / SPINEL STRUCTURE / MELT-IMPREGNATION METHOD / CYCLABILITY / HIGH TEMPERATURE PERFORMANCE / LITHIUM-MANGANESE OXIDE / ニッケル酸リチウム / 正極 / 電池特性 / 結晶構造 / 金属イオンドープ / コバルト / マンガン置換 / 生成プロセス / 空気 |
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| Research Abstract |
It is found that Mn doping into layered LiNiO_2 give various benefits as follows ; (1) easiness in the preparation of electroactive material, (2) non-sensitive to Li/transition metal (Ni+Mn) in electrochemical properties, and (3) excellent cycling performance. The electroactive Mn doped LiNiO_2 can be prepared even in air when Mn/(Ni+Mn) in atomic ratio exceeds 0.2. The charge/discharge mechanism also changes, LiNi_<0.8>Mn_<0.2>O_2 does not form monoclinic phase and delithiation of it at final part of the charge (ca. 4.2-4.3V) proceeds single phase reaction. The presence of transition metal ion in lithium layer within ca. 7% pro The discharge capacity is improved by addition of Co, and the discharge capacities of LiCo_yMn_<0.2>Ni_<0.8-y> (y=0.05-0.3) prepared in air are more than 155 mAh/g. The valence of Mn in Mn doped LiNiO_2 is determined to be more than 3 by chemical analysis and finally it is confirmed to be 4 by high resolution fluorescence measurement with two crystal. This info
… More
rmation suggests the formation of solid-solution between LiNiO_2 and Li_2MnO_3. The formation of complex solid-solution LiNiO_2-Li_2MnO_3-LiMnO_2 phase is confirmed, therefore, the charge/discharge capacities of Li_<1+x>Ni_yMn_<1-y>O_2 do not depend on Li/(Ni+Mn). The well crystallized aluminum doped LiNiO_2 can be prepared by sol-gel method, and it shows excellent cycling performance at R.T.and 50 ℃ thought discharge capacity decreases with increase in Al content.
Li, Ni, and Mn forms electroactive LiNi_xMn_<2-x>O_4 (x<0.5) with spinel structure. The discharge voltage of it change from 4.58-4.59V to 4.65-4.73 V as the increase in x, and the valence of Ni in it also changes from 3 to 2 by high resolution fluorescence measurement. In the other word, discharge voltage depends on the kinds of redox couple as same as the structure. Therefore, Ni^<3+> ion is preferentially oxidized in LiCo_<1-x2>Ni_xO_2 as confirmed experimentally. This would also lead to the constant capacities of LiCo_yMn_<0.2>Ni_<0.8-y> (y=0.05-0.3). Less
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