2007 Fiscal Year Final Research Report Summary
Novel composite anode materials for lithium secondary battery
| Project/Area Number |
18350106
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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 | Mie University |
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Principal Investigator |
TAKEDA Yasuo Mie University, Graduate School of Engineering, Professor (60093051)
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| Co-Investigator(Kenkyū-buntansha) |
IMANISHI Nobuyuki Mie University, Graduate School of Engineering, Associate Professor (20223331)
HIRAKO Atsusi Mie University, Graduate School of Engineering, Associate Professor (60324547)
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| Project Period (FY) |
2006 – 2007
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| Keywords | Power sources / Rechargeable lithium ion batteries / Negative electrode materials / Li reactive mechanisms / 複合負極 / 窒化物系負極 |
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| Research Abstract |
Lithium ion batteries are principle and promising power sources for a wide variety of electronics. Electrode material is a key for developing further lithium ion batteries, which are likely to require good reliability and high energy density. However, graphitic carbon that is currently used as negative electrode material in the commercial Li-ion batteries appears to be unsatisfied due to low theoretic capacity of 372 mAh g^-1 and poor thermal stability under lithiated state. Therefore, there is even-increasing research in the feasibility of the replacement of graphitic anodes. By this motivation, a series of novel negative electrode materials that demonstrate extremely high capacities and different Li reactive mechanisms have been proposed in this group.
1.Li-alloy based composites
The volume effects of silicon upon Li insertion and extraction can be effectively suppressed by designing a composite microstructure containing that ultrafine silicon are uniformly dispersed in a ductile condu
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cting carbonaceous matrix with electron/ion conductivity. By this way, several types of Si-based composites have been developed by means of pyrolyis process in accompany with high-energy mechanical milling step. The pyrolyzed carbon can mostly function as an elastic network with electron/ion conductivity that permits the silicon in the matrix to operate while maintaining .electrode integrity. The Si-based composites have large capacity of ca. 1000 mAh g^-1 and good cycling performance, as well as acceptable first cycle efficiency. We expect that further optimization of these Si-composite based anodes might lead to practical lithium-ion batteries with high energy density.
2.Lithium transition metal nitrides based composite electrode
We have developed a series of lithium mixed transition metal(co-doped)nitrides with high electrochemical capacity and good cyclability. For producing these compounds, a combination of a solid-state reaction under an appropriate temperature and a high-energy mechanical milling step was involved. Research reveals that the granular structure of the nitrides shows obvious effects upon the electrochemical behavior. The lithiated compounds can be used in several ways to form new composite electrodes which demonstrate high insertion capacity, 100 % first cycle efficiency and excellent capacity retention ability. Therefore, they are promising anode candidates for further Li-ion batteries. Less
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