2007 Fiscal Year Final Research Report Summary
Gas-phase Construction of Interface Enabling High-rateIonic Transfer and its Application to High-power Electrode
| Project/Area Number |
17350098
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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 |
IMANISHI Nobuyuki Mie University, Chemistry, Associate Professor (20223331)
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| Co-Investigator(Kenkyū-buntansha) |
HIRANO Atsushi Mie University, Chemistry, Assistant Professor (60324547)
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| Project Period (FY) |
2005 – 2007
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| Keywords | Lithium Battery / Solid Oxide Fuel Cell / Electrode Kinetics / Laser Ablation / Impedance Analysis / Intercalation / Air Electrode / Thin Film Electrode |
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| Research Abstract |
It is important to know the electrode reaction mechanisms and the speed in order to achieve a high power battery. A thin film electrode prepared by pulsed laser deposition (PLD) method was used for the purpose. The electrode was pore-free and crystalline-oriented due to epitaxial growth on a single crystal substrate. The PLD electrode was used in combination with impedance spectroscopy and TEM observation. (1) LiMn_2O_4 PLD film was prepared for lithium battery cathode. The charge transfer resistance of the lithium intercalation becomes smaller, if the crystallinity of the electrode or the (111) orientation becomes higher. When these conditions are satisfied, the electrode can achieve as high as several 100C to 1000C rate. The influence of electrolyte solvent is also important. The structure of double layer strongly depends on kind of the solvent. In the case of solvent with high solvation power, lithium ions are physically-adsorbed on the surface. On the other side, when solvent with low solvation power is used, lithium ions seem partially de-solvated and directly adsorbs on the surface by chemical bonds. In the case of latter, higher power was obtained. (2) The same technique was applied to the study of air electrode of solid oxide fuel cell (SOFC). Three perovskite materials, La_0.8Sr_0.2MnO_3(LSM), La_0.8Sr_0.2CoO_3(LSC), La_0.8Sr_0.2Co_0.2Fe_0.8O_3(LSCF) were compared as electrode. The magnitude of total resistance appears in the order of LSM>LSCF>LSC. The magnitude is also dependent on the orientation of the substrate, regardless of the material. The perovskites on YSZ (111) always show the lowest resistance. Our results suggest that oxygen reduction takes plane on the transition metals in the surface layer of the electrode. In conclusion, the kind and surface density of the transition metal controls the reaction speed.
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