研究者業績
Profile Information
- Affiliation
- Professor (Doctor of Science), Graduate School, of Engineering, Division of Electronic Materials and Devices, University of Hyogo
- Degree
- (BLANK)(Hiroshima University)
- J-GLOBAL ID
- 200901055102483640
- researchmap Member ID
- 1000357821
Research Interests
6Research Areas
3Research History
5-
Apr, 2008 - Present
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Apr, 2007 - Mar, 2008
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Apr, 2004 - Mar, 2007
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Apr, 2001 - Mar, 2004
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Apr, 1984 - Mar, 2001
Education
5Committee Memberships
1-
Mar, 2022 - Present
Papers
72-
Electrochemistry, 90(3) 037006-037006, Mar 16, 2022 Peer-reviewed
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Solid State Ionics, 374 115820-115820, Dec 4, 2021 Peer-reviewed
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The Journal of Physical Chemistry C, 124(31) 16758-16762, Aug 6, 2020The research and development of secondary batteries, such as the lithium-ion batteries, have been widely conducted. Most electrodes are of composite type and comprise an active material, a conductive additive, and a binder. To achieve a precise analysis of electrochemical properties for only an active material, electrochemical measurement of a single particle of an active material was carried out using an ultramicroelectrode in an Ar-filled glovebox under an inert atmosphere. Although detection of cyclic voltammetry and resistance values of LiCoO2 (LCO) secondary particles has been reported using a single-particle electrode, we succeeded in achieving the first detailed analysis of capacity and resistance components of a single active material particle by charge-discharge and alternating current impedance measurements using LCO primary particles to elucidate the battery reaction process. The capacity values of LCO single particles were detected in units of mA h g-1, whose values were close to the theoretical capacity values of LCO single particles based on their mass and size. The resistance components of an LCO single particle were detected by alternating current impedance spectroscopy, which cannot be measured in conventional electrode systems, such as applied sheet materials. A resistance model for the active material is proposed.
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BUNSEKI KAGAKU, 68(10) 793-800, Oct, 2019An electrochemical cell with a specifically designed X-ray window was fabricated in order to evaluate the structural evolution of the cathode material under the operating condition. It enabled us to obtain strong signals from a positive electrode material without a significant loss of the battery function. With use of this system, the structure evolution during the charge-discharge process of a layered cathode material Li[Ni1/3Co1/3Mn1/3]O-2 and a high voltage spinel cathode LiMn1.5Ni0.5O4 was studied. It was found from the experimental results that the Li [Ni1/3Co1/3Mn1/3]O-2 cathode exhibited a single-phase reaction, where the lattice parameters continuously changed. In the case of LiMn1.5Ni0.5O4 cathode, the charge-discharge reaction proceeded in two continuous two-phase reactions. Especially for the latter, the phase evolution was reversible in the low- current density reaction. On the other hand, in the high current density charge-discharge reaction, asymmetric behavior was observed. This means that the kinetic limitation of the battery reaction is observable even in this laboratory X-ray diffraction system.
Misc.
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Reports of Graduate School of Engineering, University of Hyogo, 57 22-27, Feb 28, 2005Lithium-nickel layered oxides were prepared by the solid-state reaction at temperature range of 700-850℃ in O_2 atmosphere. The structural refinement with the help of Rietveld analysis showed that the crystal structure of these compounds were identified as α-NaFeO_2 type layered rock-salt, where some extra Ni ions were present in Li-layers. As the Ni content in the Li-layer increased, the lattice parameter a increased and the ratio of C/a decreased. From the magnetic susceptibility measurement, it was found that both the asymptotic Curie temperature and the spontaneous magnetization at low temperature are sensitive to the presence of extra Ni ions in Li-layers. The asymptotic Curie temperature, which was always positive, shifted toward higher temperature with an increase in the non-stoichiometry degree. It was seen that the spontaneous magnetization 4.2K is also enhanced with the non-stoichiometry. Considering these magnetic variation with the non-stoichiometry enabled us to propose the following model; Ni-Ni magnetic coupling within the transition metal layer was weak and ferromagnetic, whereas the inter-layer Ni-Ni coupling is relatively strong and antiferromagnetic. The increase in the asymptotic Curie temperature may be attributed to the development of magnetic correlation from two to three dimension, and the enhancement of the spontaneous magnetization is described by ferromagnetic cluster formation.
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Transaction of the Material Research Society of Japan, 29 1663-1666, 2004
Major Books and Other Publications
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Oct, 2018 (ISBN: 9784861047282)
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Science and Technology corporation, Jan, 2014 (ISBN: 9784864280891)
Presentations
5-
International Meeting on Lithium Batteries 2022, Jun 28, 2022
Teaching Experience
12-
Apr, 2019 - PresentSemiconductor and the related materials (Kansai University)
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Apr, 2008 - Present学生実験（電気工学知識探求型実験） (兵庫県立大学)
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Apr, 2008 - PresentOscillation and wave mechanics (University of Hyogo)
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Apr, 2004 - PresentMagnetism and magnetic materials (University of Hyogo)
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Apr, 2004 - PresentQuantum mechanics (University of Hyogo)