論文 - 宇井 幸一
-
Yasushi Idemoto *, Hiroshi Sekine, Koichi Ui, Nobuyuki Koura
Solid State Ionics ( Elsevier ) 176 ( 3-4 ) 299 - 306 2005年01月 [査読有り]
学術誌 共著・分担
We investigated the relation between the cycle performance and crystal structural change during the charge–discharge process of LiMn1.5Ni0.5O4 as a 5 V class cathode active material, which was prepared by changing the calcination temperature using the sol–gel method. The lithium content of Li1−xMn1.5Ni0.5O4 (x=0.5, 0.7, 1.0) was controlled by electrochemical lithium extraction. The crystal structure was determined by Rietveld analysis using powder neutron diffraction. As a result, all samples consisted of three phases (space group: P4332) of different lattice constants and Ni valences. The main phase, which has the maximum percentage, was shifted to a phase with a lower lattice constant with the decreasing lithium content, and then finally Li1−xMn1.5Ni0.5O4 (x=1.0) was almost oxidized to Ni4+ by a charging process. Furthermore, LiMn1.5Ni0.5O4,, by changing the synthesis temperature, was different for a few oxidation processes; the structure of the phase at Ni3+ was not stable based on the distortion of each phase and the Madelung energy. It was suggested that these factors should provide an effective cycle performance.
-
Bi2.20-zPbzSr1.86Ca2.03Y0.05Cu2.86Oy超伝導酸化物におけるTc, JcのPb置換量及び酸素量依存
井手本 康*, 津之地洋平, 宮部 徹, 宇井幸一, 小浦延幸
日本セラミックス協会学術論文誌 ( 公益社団法人 日本セラミックス協会 ) 113 ( 2 ) 166 - 171 2005年02月 [査読有り]
学術誌 共著・分担
The purpose of this paper is to interpret the enhancement of Tc and Jc by the replacement of cations and changing the excess oxygen content for Bi-2223 system by the replacement of Bi and Ca by Pb and Y, respectively, that is Bi2.20-zPbzSr1.86Ca2.03Y0.05Cu2.86Oy. The relations between lattice constant, average valences of Bi+Pb and Cu, excess oxygen content and superconducting characteristics have been studied by changing Pb substitution content, and annealing treatment. Bulk samples were prepared by the coprecipitation method. Furthermore, in order to elucidate the effect of metal substitution and oxygen content on Jc of the Bi-2223 system, films which have the same metal composition of the bulk, were prepared on MgO (100) single crystal substrate by the spin coating-pyrolysis method. Measurements of Jc and Tc were carried out on highly oriented films of Bi-2223 phase with changing Pb content and oxygen content: Tc (zero) experienced a maximum at Pb content, z=0.50 (nominal composition), and Tc (zero) decreased with increasing z in the region z>0.50. On the other hand, Jc also showed a maximum at z=0.50, but it was constant with increasing z in the region z>0.50. Oxygen underdoped and overdoped regions, and the highest Tc (zero) and Jc were obtained upon adjusting the optimum excess oxygen content, by changing Pb content and annealing treatment.
-
Koichi UI*, Kohei ISHIKAWA, Takao FURUYA, Yasushi IDEMOTO, and Nobuyuki KOURA
Electrochemistry ( The Electrochemical Society of Japan ) 73 ( 2 ) 120 - 122 2005年02月 [査読有り]
学術誌 共著・分担
The positive electrode performance of the LiCoO2 electrode in the LiCl saturated AlCl3-1-ethyl-3-methylimizadolium chloride (EMIC) + SOCl2 melt as the electrolyte for nonflammable lithium secondary batteries was evaluated. In the cyclic voltammogram of the LiCoO2 electrode in the melt, the oxidation and reduction waves corresponding to the electrochemical intercalation / deintercalation reactions of Li+ were observed at 3.5~4.2 V vs. Li+/Li, and it suggested that the LiCoO2 electrode operated well in this melt. From charge and discharge evaluations, it was known that the discharge capacity was about 130 mAh g-1 and the coulomb efficiency was maintained of more than 93% during ten cycles. It became clear that the LiCoO2 electrode operates quite as a positive electrode in the melt.
-
鉛蓄電池用負極集電体に用いるPb合金の充電状態における腐食挙動
小浦延幸*, 粕谷健太, 宇井幸一, 滝口友輝, 井手本 康
Electrochemistry ( The Electrochemical Society of Japan ) 73 ( 2 ) 135 - 140 2005年02月 [査読有り]
学術誌 共著・分担
The corrosion behavior of the exposed part of the Pb alloy negative electrode from the electrolyte was analyzed upon charging, i.e., under the reduced state. Dissolved oxygen in the electrolyte affected the generation rate and the grain size of the PbSO4. From the potential measurements at the exposed part, it was found that the part not under reducing conditions and the generation reaction of PbSO4 progressed by the Jocal cell reaction. Furthermore, when the dissolved oxygen concentration in the electrolyte film on the exposed part increased, the potential at the exposed part became noble and the PbSO4 generation rate increased. On the other hand, the most anti-corrosive Pb alloy was the Pb-1.8% Sn-0.03% Se alloy. The reason was attributed to the dense corrosion layer formed on the surface, because the PbSO4 grain size became small by the synergistic effect of Sn and Se.
-
CuCl-1-ブチルピリジニウムクロリド常温型溶融塩中のCu(I)イオンからの高純度Cuの電析-Cu電析物への不純物の混入と溶融塩浴の精製-
小浦延幸，清木 賢，田邉尚敬，八代高士, 宇井幸一, 伊藤 滋
表面技術 ( 一般社団法人 表面技術協会 ) 56 ( 3 ) 151 - 157 2005年03月 [査読有り]
学術誌 共著・分担
High purity Cu electrodeposition from a CuCl-1-Butylpyridinium chloride (BPC) ambient-temperature molten salt electrolyte has been investigated. In this study, silver was examined as an impurity. Ag did not electrodeposit in the Cu deposit and the Cu purity was 99.9999%, if the Ag(I) ion concentration was controlled to be less than 10 ppm in the 66.7mol%CuCl-33.3mol%BPC melt and less than 12ppm in the 44.0mol%CuCl-56.0mol%BPC melt. In addition, a method removal of the Ag(I) ion from the melt was studied. The method of refining by galvanostatic electrolysis at a large current density (25mA·cm−2) was effective, and the Ag(I) ion concentration in the melt decreased to lower than 9ppm. Furthermore, the codeposit of Cu with the N included in the BPC, which was the main content in the bath was also examined. The electrodeposition of N was not recognized.
-
電気めっき法で作製したAlめっき膜のリチウム二次電池用負極への応用
宇井幸一*, 南 拓人, 石川恒平, 井手本 康, 小浦延幸
Electrochemistry ( The Electrochemical Society of Japan ) 73 ( 4 ) 279 - 283 2005年04月 [査読有り]
学術誌 共著・分担
The Al film prepared by the electroplating method was applied to the negative electrode for lithium secondary batteries. The electroplated Al film obtained from a 66.7 mol% AlCl3-33.3 mol% EMIC ambient-temperature molten salt melt was used. The discharge potential of the electroplated Al negative electrode showed the flat potential profile at 0.4 V vs. Li+/Li. The discharge capacity of 2nd to 5th cycle was 224-400 mAh g-1 and the charge-discharge efficiency maintained ca. 90%. It was found that the electroplated Al electrode as the negative electrode for lithium secondary batteries operates quite effectively.
-
Hidenori MATSUZAWA, Ryo NAKAI, Koichi UI, Nobuyuki KOURA*, and Guoping LING
Electrochemistry ( The Electrochemical Society of Japan ) 73 ( 8 ) 715 - 723 2005年08月 [査読有り]
学術誌 共著・分担
The structure of the ionic species in an SnCl2-1-ethyl-3-methylimidazolium chloride (EMIC) melt was examined using density functional theory (DFT) calculation and Raman spectroscopy. The Raman spectra of three different of SnCl2-EMIC melts, 33/67 (33 mol% SnCl2-67 mol% EMIC), 50/50, and 67/33 melts, were measured. The most stable structure of each SnCl2, SnCl3−, Sn2Cl4, Sn2Cl5−, EMI+, SnCl3− - EMI+ complex, or Sn2Cl5− - EMI+ complex was obtained using the B3LYP method with the LanL2DZ basis set. SnCl3− was found to be contained in all of the examined SnCl2-EMIC melts based on the assignment of the Raman spectra. Sn2Cl5− was contained in the acidic melts (SnCl2 > 50 mol%). The SnCl3− - EMI+ and Sn2Cl5− - EMI+ complexes as a microscopic structure in the SnCl2-EMIC melt were evaluated by a comparison between the harmonic frequencies and Raman spectra. In the SnCl3− - EMI+ complex, the SnCl3− was located on one side of EMI+ with a strong Coulombic force. Two possible structures of the Sn2Cl5− - EMI+ complex were obtained by a comparison between the calculated and experimental Raman spectra. Sn2Cl5− was also located on the same side of EMI+ as the SnCl3− - EMI+ complex.
-
Lithium Battery Having a Large Capacity Using Fe3O4 as a Cathode Material
S. Ito*, K. Nakaoka, M. Kawamura, K. Ui, K. Fujimoto, and N. Koura
J. Power Sources ( Elsevier ) 146 ( 43832 ) 319 - 322 2005年08月 [査読有り]
学術誌 共著・分担
The lithium battery using Fe3O4 fine particles has been constructed. The discharge characteristics were improved by the addition of India ink or polyvinyl alcohol (PVA). The discharge potential at 60 °C maintained 2.5 V versus Li/Li+ up to 500 mAh g−1 and was 1.8 V at a large capacity of 926 mAh g−1. The possibility of secondary battery was discussed from the result of cycling test with 926 mAh g−1. Similar potential curve was obtained in the second cycle. Although degradation was observed in the third cycle, cyclability was maintained. However, the test cell stopped in fourth discharge. It is concluded that a large capacity was achieved at 60 °C using fine particles of Fe3O4 with PVA additive. According to the cycling test, it is expected to be a secondary battery by further development in nanostructure of the cathode.
-
Koichi Ui*, Takuto Minami, Kohei Ishikawa, Yasushi Idemoto, Nobuyuki Koura
J. Power Sources ( Elsevier ) 146 ( 1-2 ) 698 - 702 2005年08月 [査読有り]
学術誌 共著・分担
performance of a binder-free carbon-negative electrode was investigated using the LiCl-saturated AlCl3–1-ethyl-3-methylimizadolium chloride (EMIC) + SOCl2 melt as the electrolyte for non-flammable lithium secondary batteries. Because the glass transition point of a LiCl-saturated 60.0 mol%AlCl3–40.0 mol%EMIC + 0.1 mol l−1 SOCl2 melt was −86.2 °C, the melt could be used as the electrolyte in a low-temperature domain. The binder-free carbon electrode made by the electrophoretic deposition method was used as the negative electrode. Four kinds of carbon materials, i.e., artificial graphite, natural graphite, soft carbon, and hard carbon were evaluated as the carbon electrode. For 30 cycles, the discharge capacities of these electrodes were 296–395 mAh g−1 and the charge–discharge efficiencies were more than 90%. The melt can be used as the electrolyte for non-flammable lithium secondary batteries and the binder-free carbon-negative electrode operates quite effectively.
-
Corrosion behavior of Fe-Cr alloy in Li2CO3-K2CO3 Molten Carbonate
K. Takeuchi, A. Nishijima, K. Ui, N. Koura*, and Chun -K. Loon
J. Electrochem. Soc. ( Electrochemical Society ) 152 ( 9 ) B364 - B368 2005年09月 [査読有り]
学術誌 共著・分担
-
Li二次電池正極活物質LixMn1-yMyO2(M=Mn,Al,Cu)の熱力学安定性および結晶構造に及ぼすLi組成比の影響
井手本 康*, 近野雄志, 宇井幸一, 小浦延幸
Electrochemistry 73 ( 9 ) 823 - 829 2005年09月 [査読有り]
学術誌 共著・分担
-
Y. Idemoto*, T. Mochizuki, K. Ui , and N. Koura
J. Electrochem. Soc. ( Electrochemical Society ) 153 ( 2 ) A418 - A424 2006年02月 [査読有り]
学術誌 共著・分担
-
Chun -K. Loong *, M. Ozawa, K. Takeuchi, K. Ui, and N. Koura
J. Alloys Compd. ( Elsevier ) 408-412 1065 - 1070 2006年02月 [査読有り]
学術誌 共著・分担
The techniques of neutron scattering were applied to characterize two rare-earth containing ceramic systems: oxide-based automotive three-way catalysts and proton-conducting cerate-perovskite-based hydrogen-separation membranes. High-surface-area zirconias are widely used as catalytic support of noble metals in automotive three-way catalytic converters for exhaust gas treatment. Doping these oxides with rare-earth elements provides an important means in tailoring their properties for better catalytic performance. We have carried out in situ small-to-wide angle neutron diffraction at high temperatures and under controlled atmospheres to study the sintering behavior and the Ce3+ ↔ Ce4+ redox process in CexZr1−xO2−δ solid solutions dispersed with Pt nanoparticles. We found substantial effects due to RE-doping on the nature of aggregation of nanoparticles, defect formation, crystal phase transformation, and metal-support interaction. Y-doped BaCeO3 exhibits significant proton conductivity under a hydrogen-containing atmosphere at high temperatures. This system has high potential for applications as fuel-cell electrolytes, gas sensors, and ceramic membranes for hydrogen separation. We have performed in situ neutron diffraction to obtain information regarding the crystal phase evolution that permits dissolution of hydrogen and proton migration through the lattice. Neutron quasielastic- and inelastic-scattering experiments were carried out to investigate the proton dynamics from local vibrations to long-range diffusion.
-
T. Yatsushiro, N. Koura*, S. Nakano, K. Ui, and K. Takeuchi
Electrochemistry 74 ( 3 ) 233 - 236 2006年03月 [査読有り]
学術誌 共著・分担
-
CuCl-1-ブチルピリジニウムクロリド系常温型溶融塩浴を用いたCu(Ⅰ)イオンからのCuの電析－有機溶媒混合浴
宇井幸一, 中矢清隆, 高橋康明, 田邊尚敬, 井手本 康, 小浦延幸
表面技術 57 ( 4 ) 300 - 301 2006年04月 [査読有り]
学術誌 共著・分担
-
有機溶媒添加ZnCl2-NiCl2-EMIC常温型溶融塩浴を用いたクラックフリー非晶質Zn-Ni合金の電析
宇井幸一, 上浦尚子, 井手本 康, 小浦延幸, 山崎貴司
表面技術 57 ( 5 ) 383 - 384 2006年05月 [査読有り]
学術誌 共著・分担
-
K. Ui, T. Fujita, N. Koura*, and F. Yamaguchi
J. Electrochem. Soc. ( Electrochemical Society ) 153 ( 6 ) C449 - C454 2006年06月 [査読有り]
学術誌 共著・分担
The application of TiO2 has been extensively studied, because the TiO2 produces a photocatalytic reaction that decomposes harmful materials using sunlight energy. In this study, the immobilization of the TiO2 particle on a brass substrate was examined using the composite coating method. As a result of evaluating the surface morphology using a scanning electron microscope, it was found that the co-deposited TiO2(anatase) (TiO2(A)) particles were exposed on the surface of the Ag or Cu-TiO2(A) particle composite coating films. The proportion of the TiO2(A) particle on the surface increased with increasing the co-deposit volume ratio of the TiO2(A) particle. The photocatalytic activity of the Ag-TiO2(A) composite film was significantly better than that of the Cu-TiO2(A) composite film. The cause for this difference was attributed to the effect of Ag itself (in the dark) and the synergistic effect of Ag and TiO2(A) (under UV irradiation).
-
泳動電着法を用いたLi イオン二次電池用バインダーフリー正極の作製
宇井幸一*, 府野信也, 長瀬 浩, 井手本 康, 小浦延幸
Electrochemistry 74 ( 6 ) 474 - 478 2006年06月 [査読有り]
学術誌 共著・分担
-
常温型溶融塩を電解液に用いるAl二次電池用正極活物質としてのポリパラフェニレンの応用
宇井幸一, 久間義文, 小浦延幸*
Electrochemistry 74 ( 7 ) 536 - 538 2006年07月 [査読有り]
学術誌 共著・分担
-
Growth model of Reversed Taper during Early Stage of D.C. Etching on Aluminum Oriented to (100),
K. Ui, T. Yamazaki, N. Koura*, Y. Idemoto, T. Makino, M. Furukawa, and H. Uchi
Electrochemistry 74 ( 9 ) 737 - 743 2006年09月 [査読有り]
学術誌 共著・分担