| Project/Area Number |
15350118
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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 |
Inorganic industrial materials
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
WAKIHARA Masataka Tokyo Institute of Technology, Department of Applied Chemistry, Professor, 大学院・理工学研究科, 教授 (20016596)
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| Co-Investigator(Kenkyū-buntansha) |
UCHIMOTO Yoshiharu Kyoto University, Graduate School of Human and Environmental Studies, Associate Professor, 大学院・人間・環境学研究科, 助教授 (50193909)
IKUTA Hiromasa Fukushima University, Graduate School of Industrial System, Associate Professor, 共生システム理工学類, 助教授 (80242270)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥14,900,000 (Direct Cost: ¥14,900,000)
Fiscal Year 2005: ¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 2004: ¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 2003: ¥9,300,000 (Direct Cost: ¥9,300,000)
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| Keywords | spinel structure / lithium ion battery / high power performance / order-disorder structure / defect chemistry / 次世代リチウムイオン電池 / 高電位正極 / スピネル型酸化物 / 酸素分圧制御 / XANES / 分子動力学シミュレーション |
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| Research Abstract |
Development of the cathode materials for Li ion battery is vital to meet the demands of portable devices, future usages of electric vehicles and so on. Among the cathodes, LiMn_2O_4 and related oxides has gained much attention because of its low cost, low toxicity, and relatively high energy density. Especially, LiNi_<0.5>Mn_<1.5>O_4 has received much attention because of its high discharge capacity, good cyclability, and dominant plateau at around 4.7 V, whereas other materials showed two plateaus at 〜4 and 5 V. In this study, the improvement of rate performance was attempted by introducing defects into spinel oxides. In addition, it was aimed to reveal the factors affecting rate performance from the viewpoint of defect chemistry. Spinel type oxide, LiNi_<0.5>Mn_<1.5>O_4 was synthesized with various temperatures and investigated their stoichiometry, crystal structures and electrochemical properties. Under oxygen atmosphere, a sudden increase of nonstoichiometry occurred with endothermes at around 760℃. In addition, infrared spectroscopic study revealed that ordered arrangement of Ni and Mn in octahedral sites was partially collapsed by the increase of nonstoichiometry. The electrochemical performance for the samples quenched from above and below 760℃ in oxygen atmosphere were investigated, and the samples quenched above 760℃ showed better rate-performance than those quenched below 760℃ Accordingly, the synthesis temperature of LiNi_<0.5>Mn_<1.5>O_4 was the key factor for controlling the arrangement of Ni and Mn, nonstoichiometry and electrochemical properties.
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