Hajime Tanida

Kanazawa University, Kanazawa, Ishikawa, Japan

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Publications (164)311.28 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: For the further development of lithium-ion batteries, improvement of their cyclic performance is crucial. However, the mechanism underlying the deterioration of the battery cyclic performance is not fully understood. We investigated the effects of the electronic structure at the electrode/electrolyte interface on the cyclic performance of the cathode materials via in situ total-reflection fluorescence X-ray absorption spectroscopy. In a LiCoO2 thin-film electrode that exhibits gradual deterioration upon subsequent Li ion extractions and insertions (cycling), the reduction of Co ions at the electrode/electrolyte interface was observed upon immersion in an organic electrolyte, with subsequent irreversible changes after cycling. In contrast, in a LiFePO4 thin-film electrode, the electronic structure at the electrode/electrolyte interface was stable and reversible upon electrolyte immersion with subsequent cycling. The increased stability of the electronic structure at the LiFePO4/electrolyte interface affects its cycling performance.
    The Journal of Physical Chemistry C. 04/2014; 118(18):9538–9543.
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    ABSTRACT: Total-reflection X-ray absorption fine structure (TR-XAFS) technique was applied for the first time to an interface between two immiscible electrolyte solutions under potentiostatic control. The hydration structure of bromide ions was investigated at polarized 2-octanone/water interfaces. TR-XAFS spectra at Br K-edge measured in the presence of hexyltrimethylammonium bromide (C6TAB) were slightly modified depending on the Galvani potential difference ([Formula: see text]). The extended X-ray absorption fine structure analysis exposed hydration structure changes of bromide ions at the polarized interface. The coordination structure of bromide ions at the interface could be analyzed as compared with bromide ions dissolved in aqueous solution and Br(-)-exchanged resin having quaternary ammonium groups. The results indicated that bromide ions were associated with C6TA(+) at the polarized interface. The relative contribution of ion association form of bromide ions with quaternary ammonium groups was enhanced at a potential close to the ion transfer of C6TA(+), where the interfacial concentration of C6TA(+) is increased as a function of [Formula: see text].
    The Journal of Chemical Physics 03/2014; 140(10):101101. · 3.12 Impact Factor
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    ABSTRACT: A novel spectro-electochemical cell for X-ray absorption spectroscopy in the tender X-ray region (TX-XAS) was designed and fabricated to investigate the electrochemical behavior of common battery materials with liquid electrolytes under in situ/operando conditions. The cell has several unique features, such as high X-ray transmittance, high signal to noise ratio, and high vacuum tightness. These features enable us quick and reliable XAS measurements. Operando P K-edge XAS measurements of an olivine-type LiFePO4 composite positive electrode were carried out to clarify its phosphorus environment during the electrochemical charging process. Results of spectral analysis show that there is no significant change in the oxidation state of phosphorus and in the coordination of the phosphate anions in the charging process, but a closer look of the consecutive XAS spectra suggests the shrinkage of the PO4 cage during the charging process, and the structural changes in a biphasic manner. These results demonstrate the usefulness of the cell for in situ/operando TX-XAS observations of light elements in practical batteries.
    Review of Scientific Instruments 01/2014; 85(8):084103-084103-6. · 1.60 Impact Factor
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    ABSTRACT: Reaction distribution in the composite electrode of LiCoO2, an acetylene black and an organic binder was evaluated by two-dimensional X-ray absorption spectroscopy (XAS). The valence change of Co ion in LiCoO2 due to the Li de-intercalation during charging was evaluated as the change of the absorption energy of Co K-edge. To demonstrate the reaction distribution due to ionic transportation in the composite cathode, a composite electrode laminated by an aluminum foil and a polyimide film was fabricated in this study. After charging, clear shifts of the absorption energy was observed. The reaction distribution was evaluated by evaluating the peak top energy of Co K-edge as a function of the distance from the edge of the laminated cathode. Two-dimensional mapping of the reaction distribution revealed that the electrochemically active area expands about 700 μm from the edge of the electrode under the charging condition of 0.2 C. This is consistent with a result of electrochemical charging test showing only 42% of the theoretical capacity with the current rate of 0.2 C.
    Solid State Ionics 01/2014; 262:66–69. · 2.05 Impact Factor
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    ABSTRACT: Surface coating on lithium-ion battery cathodes improves their durability at high potentials, which is a well-known practical application. However, the mechanism is still unclear because the coating influences the electrode/electrolyte interface at a few nanometer-scale and direct observation of the interface under real operating conditions of a battery is challenging. This study reveals the mechanism of the surface coating effect on lithium-ion battery cathodes by using in operando X-ray absorption spectroscopy (XAS) on well-defined MgO-coated LiCoO2 thin-film electrodes prepared via pulsed laser deposition. Total-reflection in operando XAS measurements reveal that LiCoO2 forms a reductive phase at the interface between the uncoated-LiCoO2 electrode and the electrolyte, while the MgO coating layer inhibits the redox process, leading to an improvement in the cycle performance of the battery. Depth-resolved in operando XAS measurements indicate that a solid solution of the magnesium phase forms at the LiCoO2 surface upon MgO coating. Magnesium ions function as pillars to stabilize the layered structure at the interface between the LiCoO2 electrode and the electrolyte for delithiated states upon cycling at potentials.
    Advanced Materials Interfaces 01/2014;
  • Electrochemistry -Tokyo- 01/2014; · 0.93 Impact Factor
  • Electrochemistry -Tokyo- 01/2014; · 0.93 Impact Factor
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    ABSTRACT: We investigated the magnetic properties of the antiferromagnetic (AFM) compound GdT2Al10 (T=Ru and Fe). Although GdRu2Al10 could be understood well as a simple AFM compound, the exchange interaction in GdFe2Al10 is found to be greatly varied with temperature. The magnitude of the AFM exchange interaction is reduced with decreasing temperature. We ascribed its origin to the exchange enhancement of the Fe ion with a decrease of temperature as was observed in YFe2Al10. The ordered moment is found to be along the [011] direction in the bc plane in both compounds from the anisotropic magnetic susceptibility. The origin of the magnetic anisotropy below TN could not be understood by the magnetic dipole interaction, which might come from the AFM order on the zigzag chain.
    Physical Review B 09/2013; 88(10). · 3.66 Impact Factor
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    ABSTRACT: We have examined the La substitution and its pressure effect on the Kondo semiconductor CeRu2Al10, which shows an unusual antiferromagnetic (AFM) order at T0=27 K with the AFM ordered moment (mAF) parallel to the orthorhombic c axis, not expected from the large anisotropy of the magnetic susceptibility (χ) of χa≫χc≫χb in the paramagnetic state. mAF could not be aligned along the a axis, but could only be in the bc plane. By only 10% La substitution corresponding to a negative chemical pressure effect, the direction of mAF in the AFM ordered phase is changed from the c to the b axis. However, by applying a small pressure of P∼0.3 GPa, this mAF∥b is easily changed to mAF∥c. Thus, the magnetic anisotropy could be easily controlled by tuning the pressure slightly. This indicates that the c-f hybridization dominates the magnetic anisotropy in the AFM ordered state and plays an essential role in the unusual AFM order in CeT2Al10 (T=Ru,Os).
    Physical Review B. 07/2013; 88(4).
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    ABSTRACT: In situ two-dimensional (2D) micro-imaging X-ray absorption fine structure (XAFS) measurements were performed in transmission mode using a charge coupled device (CCD) detector, phosphor screen, and magnifying lens. This method makes it possible to display a 2D image with a spatial resolution of around 2 μm at each energy point in a XAFS spectrum. The method was applied to in situ transmission micro-imaging XAFS measurement with a quick scanning technique.
    Journal of Physics Conference Series 04/2013; 430(1):2021-.
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    ABSTRACT: The tungsten (W) species in marine ferromanganese oxides were investigated by wavelength dispersive XAFS method. We found that the W species are in distorted Oh symmetry in natural ferromanganese oxides. The host phase of W is suggested to be Mn oxides by μ-XRF mapping. We also found that the W species forms inner-sphere complexes in hexavalent state and distorted Oh symmetry on synthetic ferrihydrite, goethite, hematite, and δ-MnO2. The molecular-scale information of W indicates that the negatively-charged WO42− ion mainly adsorbs on the negatively-charged Mn oxides phase in natural ferromanganese oxides due to the strong chemical interaction. In addition, preferential adsorption of lighter W isotopes is expected based on the molecular symmetry of the adsorbed species, implying the potential significance of the W isotope systems similar to Mo.Adsorption experiments of W on synthetic ferrihydrite and δ-MnO2 were also conducted. At higher equilibrium concentration, W exhibits behaviors similar to Mo on δ-MnO2 due to their formations of inner-sphere complexes. On the other hand, W shows a much larger adsorption on ferrihydrite than Mo. This is due to the formation of the inner- and outer-sphere complexes for W and Mo on ferrihydrite, respectively. Considering the lower equilibrium concentration such as in oxic seawater, however, the enrichment of W into natural ferromanganese oxides larger than Mo may be controlled by the different stabilities of their inner-sphere complexes on the Mn oxides. These two factors, (i) the stability of inner-sphere complexes on the Mn oxides and (ii) the mode of attachment on ferrihydrite (inner- or outer-sphere complex), are the causes of the different behaviors of W and Mo on the surface of the Fe/Mn (oxyhydr)oxides.
    Geochimica et Cosmochimica Acta 04/2013; 106:364–378. · 3.88 Impact Factor
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    ABSTRACT: The phase transition between LiFePO4 and FePO4 under nonequilibrium battery operation was tracked in real-time using time-resolved X-ray diffraction. A metastable crystal phase appears in conjunction with increasing current density, in addition to the thermodynamically stable LiFePO4 and FePO4 phases. The metastable phase gradually diminishes under open circuit conditions following electro-chemical cycling. We propose a phase transition path that passes through the metastable phase, and posit the new phase's role in decreasing nucleation energy, accounting for the excellent rate capability of LiFePO4. This study is the first to report the measurement of a metastable crystal phase during the electrochemical phase transition of LixFePO4.
    Journal of the American Chemical Society 04/2013; · 10.68 Impact Factor
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    ABSTRACT: Transient states of phase transition in LiFePO4/FePO4 for lithium ion battery positive electrodes are investigated by time-resolved measurements. To directly detect changes in electronic and crystal structures under battery operation, in situ time-resolved X-ray absorption and diffraction measurements are performed, respectively. The phase fraction change estimated by the iron valence change is similar to the electrochemically expected change. The transient change of lattice constant during two phase reaction is clearly observed by the time-resolved X-ray diffraction measurement. The nonequilibrium lithium extraction behavior deviates from the thermodynamic diagram of the two phase system, resulting in continuous phase transition during electrochemical reactions.
    Chemistry of Materials. 03/2013; 25(7):1032–1039.
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    ABSTRACT: We have investigated the magnetic properties in the well localized compound NdFe2Al10 and the Kondo semiconductor CeT2Al10 (T=Ru, Os) to clarify the origin of the unusual magnetic order in CeT2Al10. In NdFe2Al10, the experimental results of the magnetic properties could be reproduced very well by the mean-field calculation for the two-sublattice model. In CeT2Al10 we could reproduce the anisotropic magnetic susceptibility in the paramagnetic region above 60–100 K very well by the mean-field calculation for the two-sublattice model introducing an anisotropic exchange interaction and the recently determined crystalline electric field (CEF) level scheme from Strigari et al. [ Phys. Rev. B 86 081105 (2012)]. However, in the antiferromagnetic (AFM) ordered state, we could not reproduce the experimental results at all in the framework of the mean-field calculation for the two-sublattice model. We propose that although the magnetic properties in the paramagnetic region above 60–100 K could be understood well by a localized picture, the ordered state could not, and that the c-f hybridization, especially along the a axis, is associated with the unusual magnetic order in CeT2Al10.
    Physical review. B, Condensed matter 12/2012; 86(24). · 3.77 Impact Factor
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    ABSTRACT: Phonon spectra of LaRu2Al10 and CeRu2Al10 have been studied by Raman scattering from 3.4K to 300K. Polarization dependence at room temperature gives the precise mode assignment for the sake of first principles calculation results. The measured Raman spectra are well explained by the space group Cmcm and there is no remarkable difference between LaRu2Al10 and CeRu2Al10. Since we observed no anomaly at T0 = 27K in CeRu2Al10, the lattice distortion due to the structural transition has not been detected. From the temperature dependence of the vibrational frequency of Ce and La, their vibrational amplitude is not large in CeRu2Al10 and LaRu2Al10, that is, close to harmonic case.
    Journal of Physics Conference Series 12/2012; 391(1):2050-.
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    ABSTRACT: We have performed 27Al-NQR measurements in CeOs2Al10 which exhibits a novel phase transition at T0=29 K The NQR parameters determined for all the Al sites in ambient pressure were compared with those in CeRu2Al10 with T0=27 K and CeFe2Al10 with no phase transition. The distinct NQR splitting just below T0=32.5 K under pressure 0.66 GPa ensures an enhancement of T0 and a homogeneous transition. Despite the increase of T0, the nuclear spin-lattice relaxation rate 1/Tl is suppressed over whole range of temperature than in ambient pressure. The characteristic features of no critical slowing down at T0 and of the remarkable decrease of 1/T1T starting at T > T0 become prominent under pressure, suggesting an approach to Kondo semiconductor in a valence fluctuation regime.
    Journal of Physics Conference Series 12/2012; 400(3):2052-.
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    ABSTRACT: CeRu2Al10 causes a mysterious phase transition at T0~27 K In order to examine the feature of this transition, we have measured the magnetic susceptibility and electrical resistivity of Ce1-xRxRu2Al10 (R=La, La0.63Y0.37, Y) system in which Ce ions in CeRu2Al10 are replaced by non-magnetic rare earth ions with different ionic radii, where the relationship among the ionic radii is La3+ > (***La0.63Y0.37)3+ ~ Ce3+ > Y3+.*** The magnitude of the magnetic susceptibility becomes smaller with decreasing ionic radii, indicating Kondo temperature increases due to the chemical pressure effect. In the La- and La0.63Y0.37-substituted system, T0 decreases monotonically and disappears smoothly at x~0.7, while in the Y-substituted system, T0 decreases more slowly and disappears suddenly between x=0.4 and 0.5. These behaviors cannot be understood by a simple magnetic phase transition, suggesting that the change in valence of Ce ion plays an important role in the mysterious phase transition.
    Journal of Physics Conference Series 12/2012; 400(3):2073-.
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    ABSTRACT: Novel multilayer formation of fluorocarbon compounds at the hexane/water interface was investigated from the view point of intermolecular interaction and miscibility of molecules in the adsorbed film. The two kinds of mixed systems were employed; 1H,1H,2H,2H-perfluorododecanol (FC12OH) - 1H-perflurodecane (HFC10) (System A) and 1-icosanol (C20OH) - HFC10 (System B). The interfacial tension γ between the hexane solution and water was measured as a function of total concentration m and the composition of HFC10 in the mixture X(2) at 298.15K under atmospheric pressure. X-ray reflectivity (XR) measurement was performed at BL37XU in SPring-8 as a function of scattering vector Q(z). In both systems, the γ vs. m curves except for pure HFC10 system have a break at low concentrations, which corresponds to the gaseous - condensed monolayer transition for System A and the expanded - condensed monolayer for System B. Remarkable difference between the two systems was that the curves in a limited bulk composition range (0.45 ≤ X(2) ≤ 0.9) of System A shows another break at high concentrations close to the solubility limit. The total interfacial density above this break point was around 7 ~ 11 μmol m(-2), suggesting the spontaneous molecular piling to form multilayer. The phase diagrams of adsorption in the condensed monolayer indicated that the film composition of HFC10 is negative in the System B but definitely positive above X(2) ≥ 0.45 in the System A. This clearly shows that HFC10 molecules are miscible with FC12OH but immiscible with C20OH in the condensed monolayer. Thus, it is likely that the mixing of HFC10 with FC12OH in the condensed monolayer induces multilayer formation. The X-ray reflectivity normalized by Fresnel reflectivity R⁄R(F) vs. Q(z) plot in the condensed monolayer of system A was fitted by one-slab model with uniform electron density and thickness. The electron density profile was almost same as that of pure FC12OH system. The plot in the multilayer, on the other hand, was fitted well by two-slab model with different electron densities and thicknesses. The electron density profile showed that the multilayer consists of two layers; one of which has slightly higher electron density than bulk hexane phase and piles on the lower layer with almost same electron density as condensed FC12OH monolayer.
    The Journal of Physical Chemistry B 10/2012; · 3.61 Impact Factor
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    ABSTRACT: Surface analysis: In situ total-reflection fluorescence X-ray absorption spectroscopy showed that reduction of cobalt at the surface of a LiCoO(2) electrode occurs by contact with a liquid electrolyte. An irreversible behavior was observed at the surface of LiCoO(2) during a first charge/discharge process whereas the bulk material showed a reversible behavior. This Co reduction is an initial electrode deterioration.
    Angewandte Chemie International Edition 10/2012; · 11.34 Impact Factor
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    ABSTRACT: We performed the detailed studies of the pressure effect on the anisotropic electrical resistivity (ρ) of CeRu2Al10 in order to clarify if the pressure effect is also anisotropic or not. The results clearly showed the large anisotropic pressure effect on ρ. By applying the pressure, the large peak of ρ along the c axis below the antiferromagnetic transition temperature (T0) is rapidly suppressed, and becomes small and similar to the large peak along the a axis where the peak is already small at the ambient pressure. On the other hand, that along the b axis at the ambient pressure is enhanced up to 2 GPa. Also, in the temperature dependence of ρ between T0 and ∼50 K, the similar anisotropic pressure effect is observed. Along the a and c axes, the semiconducting behavior is suppressed, but that along the b axis is enhanced by pressure. From these results, we concluded that the two-dimensional electronic nature of CeRu2Al10 is reinforced by pressure and becomes close to that of CeOs2Al10. The pressure effect of the magnetization along the a axis and the thermal expansion of CeRu2Al10 along the three crystal axes were also investigated. These results and the pressure effect on ρ indicate that the anisotropic c-f hybridization effect is important to clarify the unusual long-range order in this system.
    Physical review. B, Condensed matter 08/2012; 86(8). · 3.77 Impact Factor

Publication Stats

599 Citations
311.28 Total Impact Points

Institutions

  • 2014
    • Kanazawa University
      • Graduate School of Natural Science and Technology
      Kanazawa, Ishikawa, Japan
  • 2011–2014
    • Kyoto University
      • • Graduate School of Human and Environmental Studies
      • • Department of Molecular Engineering
      Kioto, Kyōto, Japan
    • NEC Corporation
      Edo, Tōkyō, Japan
  • 2001–2013
    • Japan Synchrotron Radiation Research Institute (JASRI)
      Tatsuno, Hyōgo, Japan
  • 1996–2013
    • Hiroshima University
      • • Department of Quantum Matter
      • • Graduate School of Biosphere Sciences
      • • Faculty of Applied Biological Science
      Hirosima, Hiroshima, Japan
  • 2010
    • National Institute for Agro-Environmental Sciences in Japan
      Tsukuba, Ibaraki, Japan
    • National Institute of Advanced Industrial Science and Technology
      • Electronics and Photonics Research Institute
      Tsukuba, Ibaraki, Japan
  • 2009–2010
    • Ritsumeikan University
      • Research Organization of Science and Engineering
      Kioto, Kyōto, Japan
  • 2007–2010
    • Tohoku University
      • Department of Physics
      Sendai-shi, Miyagi-ken, Japan
  • 2005–2009
    • Kyushu University
      • • Faculty of Sciences
      • • Graduate School of Sciences
      Fukuoka-shi, Fukuoka-ken, Japan
    • Tokyo Institute of Technology
      • Graduate School of Interdisciplinary Science and Engineering
      Tokyo, Tokyo-to, Japan
  • 2006
    • Hyogo University of Teacher Education
      Yashiro, Hyōgo, Japan
  • 2004
    • Tottori University
      • Faculty of Engineering
      Tottori, Tottori-ken, Japan
  • 1995–1998
    • Osaka University
      • Department of Chemistry
      Ōsaka-shi, Osaka-fu, Japan
  • 1989–1997
    • Azabu University
      • • School of Veterinary Medicine
      • • Department of Veterinary Medicine
      Sagamihara, Kanagawa-ken, Japan
  • 1984–1988
    • Oregon State University
      • Department of Animal Sciences
      Corvallis, OR, United States