Hajime Tanida

Kanazawa University, Kanazawa, Ishikawa, Japan

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Publications (144)279.03 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The effect of molecular orientation on the miscibility and structure of the adsorbed film of the 1H,1H,10H,10H-perfluorodecane-1,10-diol (FC10diol) - 1H,1H,2H,2H-perfluorodecanol (FC10OH) mixture at the hexane/water interface were examined by interfacial tension and X-ray reflectivity measurements. The interfacial tension and X-ray reflectivity at the hexane solution/water interface were measured as a function of total molality m and composition of FC10OH in the mixture X_2 under atmospheric pressure at 298.15K. The interfacial pressure vs. mean area per molecule curves showed that two kinds of condensed monolayers (C1 and C2) and multilayer (M) states appeared depending on m and X_2. In the pure component systems, it was found that FC10OH forms condensed monolayer in which the molecules orient almost normally to the interface, and FC10diol orients parallel and is densely packed in the condensed monolayer and then piles spontaneously to form multilayer. In the mixed system, the phase diagram of adsorption indicated that FC10OH molecules are richer in C2 than in C1 state. The X-ray reflectivity measurements manifest that the condensed monolayer below X_2= 0.985 is heterogeneous in which the normal- and parallel-oriented domains coexist at the interface (C1 state), and that above X_2 = 0.985 seems to be homogeneous with normal molecular orientation (C2 state). The structure of M state depends on those of condensed monolayers, on which the molecules pile spontaneously. The heterogeneous structure in C1 state is compared to that previously observed in the mixed system of FC10diol - FC12OH (1H,1H,2H,2H- perfluorododecanol), where FC12OH has longer fluorocarbon chain length than FC10OH, and is discussed in terms of domain line tension.
    The journal of physical chemistry. B. 10/2014;
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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 09/2014; 262:66–69. · 2.05 Impact Factor
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    ABSTRACT: 1. Introduction It is well recognized that reaction distribution inside electrodes greatly affects battery characteristics while its detailed behavior remains unclear. The reaction distribution may trigger low utilization of the active material, accelerated deterioration of the rechargeable capacity, and safety issues caused by partially enhanced current density. The ex-situ analysis of the reaction distribution in cross-section of the composite electrode has been previously reported [1]. However, there has been no report on in-situ techniques for the reaction distribution measurement and therefore its dynamics during the charge-discharge processes has not yet been clarified. Based on these, we here report the development of the energy-scanning confocal XRD method that can capture the reaction distribution in cross-section of the composite electrode in operando during the charge-discharge process. 2. Experiment An aluminum pouch-type three electrode cell was used in which lithium metal foil was used as a counter electrode and a reference electrode. The working composite electrode consisted of LiNi1/3Co1/3Mn1/3O2, acetylene black as a conductive additive, and PVDF as a binder mixed in a 90 : 5 : 5 wt% ratio and was coated onto Al foil. The electrolyte was 1M LiPF6 / EC : EMC (3 : 7). The cell was assembled in an Ar-atmosphere glove box. The XRD measurement was performed at BL28XU at SPring-8 (Hyogo, Japan). The confocal area consisting of incident and diffraction beams was set in the cross-section of the electrode to give high spatial resolution XRD analysis while the energy of the incident monochromatic X-ray was continuously scanned to form a XRD spectrum. Observation points in the electrode were changed in turn by moving the height of the sample stage. 3. Result and discussion Figure 1 shows the change of diffraction 113 peaks during the discharge process of the Li0.5Ni1/3Co1/3Mn1/3O2 electrode at a rate of 139 mA/g. A shift of the 113 peak by Li insertion into the active material was observed all the three positions in the cross-section of the electrode, however the peak positions at the discharge end were different in each position. In a rest period, the 113 peaks value at the counter electrode side and the center were decreased, and that at the current collector side was increased. This suggests that the reaction distribution arose in the cross-section of the electrode during the discharge process, then was relaxed in the rest period. The converged 113 peak positions after relaxation matched well with that expected for the discharged capacity. It is revealed that the reaction proceeds at the counter electrode side faster than the current collector side and this newly developed method have a sufficient spatial resolution and time resolution for the measurement of the reaction distribution in cross-section of the electrode. Acknowledgement This work was supported by the “Research and Development Initiative for Science Innovation of New Generation Battery (Rising project)” of the New Energy and Industrial Technology Development Organization (NEDO), Japan. References [1] J. Liu, M. Kunz, K. Chen, N. Tamura and T. J. Richardson, J. Phys. Chem. Lett., 1, 2120 (2010).
    17th International Meeting on Lithium Batteries 2014; 06/2014
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    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: The newly installed BL28XU beamline at SPring-8 is dedicated to in situ structural and electronic analysis of rechargeable batteries. It supports the time range (1 ms to 100 s) and spatial range (1 µm to 1 mm) needed for battery analysis. Electrochemical apparatus for battery charging and discharging are available in experimental hutches and in a preparation room. Battery analysis can be carried out efficiently and effectively using X-ray diffraction, X-ray absorption fine-structure analysis and hard X-ray photoelectron spectroscopy. Here, the design and performance of the beamline are described, and preliminary results are presented.
    Journal of Synchrotron Radiation 01/2014; 21(Pt 1):268-72. · 2.19 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: 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: 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: We are currently constructing a new X-ray absorption fine structure (XAFS) beamline BL36XU at SPring-8 dedicated for the structural and electronic analysis of the dynamic events on polymer electrolyte fuel cell (PEFC) cathode catalysts for the development of next-generation PEFCs. To investigate the cathode catalyst nanoparticles in PEFCs under the operating conditions, the beamline is designed to provide time- and spatially resolved XAFS techniques having a time resolution of 100 μs, spatial resolution of 200 nm, and depth resolution of 1 μm. We report the outline and design of the new beamline.
    Journal of Physics Conference Series 04/2013; 430:012020.
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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: 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: An X-ray Raman spectrometer for studies of local structures in minerals is discussed. Contrary to widely adopted back-scattering spectrometers using ≤10 keV X-rays, a spectrometer utilizing ∼20 keV X-rays and a bent Laue analyzer is proposed. The 20 keV photons penetrate mineral samples much more deeply than 10 keV photons, so that high intensity is obtained owing to an enhancement of the scattering volume. Furthermore, a bent Laue analyzer provides a wide band-pass and a high reflectivity, leading to a much enhanced integrated intensity. A prototype spectrometer has been constructed and performance tests carried out. The oxygen K-edge in SiO(2) glass and crystal (α-quartz) has been measured with energy resolutions of 4 eV (EXAFS mode) and 1.3 eV (XANES mode). Unlike methods previously adopted, it is proposed to determine the pre-edge curve based on a theoretical Compton profile and a Monte Carlo multiple-scattering simulation before extracting EXAFS features. It is shown that the obtained EXAFS features are reproduced fairly well by a cluster model with a minimal set of fitting parameters. The spectrometer and the data processing proposed here are readily applicable to high-pressure studies.
    Journal of Synchrotron Radiation 03/2013; 20(Pt 2):266-71. · 2.19 Impact Factor
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    ABSTRACT: The redox reaction of Li1.16Ni0.15Co0.19Mn0.50O2 positive electrode material during the charging and discharging processes was investigated by using spectroscopic methods, i.e. in situ hard X-ray absorption near edge structure (XANES) at transition metal K-edges and ex situ soft XANES at oxygen K- and transition metal L-edges. The spectral changes of constituent elements during the initial charging to 4.5 V vs. Li/Li+ are quite similar to those of conventional layer-structured positive materials, such as LiNi1/3Mn1/3Co1/3O2. Ni2+ and Co3+ ions are fully oxidized to Ni4+ and Co4+, while Mn4+ remains unchanged. Ligand oxygen ions also take part in charge compensation. In the process of charging to 4.8 V via the plateau voltage region, no significant spectral change appears except partial reduction of Ni and Co ions in spite of lithium extraction. By discharging to 2.0 V the spectra of each element return to those of the pristine material.
    Journal of Power Sources 01/2013; 222:45–51. · 5.26 Impact Factor
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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: The total reflection X-ray absorption fine structure (TR-XAFS) technique was applied to adsorbed films at the surface of aqueous solutions of surfactant mixtures composed of dodecyltrimethylammonium bromide (DTAB) and dodecyltrimethylammonium tetrafluoroborate (DTABF(4)). The obtained XAFS spectra were expressed as linear combinations of two specific spectra corresponding to fully hydrated bromide ions (free-Br) and partially dehydrated bromide ions adsorbed to the hydrophilic groups of surfactant ions (bound-Br) at the surface. The ratio of free- and bound-Br ions was determined as a function of surface tension and surface composition of the surfactants. Taking also the results in our previous studies on the DTAB - dodecyltrimethylammonium chloride (DTAC) and 1-hexyl-3-methylimidazolium bromide (HMIMBr) - 1-hexyl-3-methylimidazolium tetrafluoroborate (HMIMBF(4)) mixed systems into consideration, the relation between counterion distribution and miscibility of counterions at the solution surface was deduced for the surfactant mixtures having common surfactant ions but different counterions.
    Journal of Colloid and Interface Science 08/2012; 388(1):219-24. · 3.55 Impact Factor

Publication Stats

468 Citations
279.03 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
  • 2002–2013
    • Japan Synchrotron Radiation Research Institute (JASRI)
      Tatsuno, Hyōgo, 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
  • 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