論文 - 宇井　幸一

AlCl₃-BPC系溶融塩を電解液に用いる二次電池のAl負極構成材の検討

小浦延幸*, 津田英則, 宇井幸一

電気化学および工業物理化学 ( 公益社団法人　電気化学会 )  64 ( 11 ) 1195 - 1199   1996年11月  [査読有り]

学術誌  共著・分担

DOI

Positive Electrode Active Material for the Rocking Chair Type Lithium Secondary Battery with an Ambient Temperature Molten Salt as a Nonflammable Electrolyte

Koichi UI, Nobuyuki KOURA, Yasushi IDEMOTO*, and Kazutaka IIZUKA

Denki Kagaku (presently Electrochemistry)   65 ( 2 ) 161 - 162   1997年02月  [査読有り]

学術誌  共著・分担

1.381　2020 Journal Impact Factor (JIF)

DOI

K⁺ -β- ferrite as a new cathode active material for lithium secondary battery

S. Ito*, K. Ui, N. Hoshi, H. Kurosawa, N. Koura, and K. Akashi

J. Phys. IV France   7 ( C1 ) 161 - 162   1997年05月  [査読有り]

その他（含・紀要）  共著・分担

The possibility of K+-β-ferrite (Kl.33Fe11O17) as a cathode active material for lithium secondary battery was investigated. It was confirmed that lithium ions certainly inserted into K+-β-ferrite. Li content y in LiyK1,33Fe11O17 was increased up to 6.79. Most of lithium ions seem to enter into γ-Fe2O3 layers of K+-β-ferrite, because alkali layers could contain only 2 alkali ions for Fe11O17. According to the cyclic voltammogram, good reversibility was observed in insertion and extraction of lithium ions. The discharge potential decreased to 1.5V vs. Li/Li+ and the charge potential increased to 4.5V vs. Li/Li+. The capacity of K+-β-ferrite has reached 200Ah/kg.

DOI

不燃性常温型溶融塩電解液を用いるロッキングチェア型リチウム二次電池のLi-Al負極特性

小浦延幸, 宇井幸一

軽金属   47 ( 5 ) 267 - 272   1997年05月  [査読有り]

学術誌  共著・分担

The rocking chair type lithium secondary battery using an LiCl saturated AlCl3–1–ethyl–3–methylimidazolium chloride (EMIC) melt as a nonflammable electrolyte operated at room temperatures has been developed. LiCl was soluble in the acidic melts (50 mol%<AlCl3). In this study, Li metal was added to the melt in order to reduce Al2Cl7− remained in the melt to Al and AlCl4−. As a result, the potential window of the melt became about 4.4 V between the reduction potential of EMI+ and the oxidation potential of AlCl4−. Lithium was only deposited on an Al electrode from this melt. Cyclic voltammograms for an Al electrode in the melt showed reversible depositing and resolving behavior for lithium. From X-ray diffraction analysis, it was confirmed that Li–Al alloy was formed on the Al substrate at room temperature. Chronopotentiograms for an LixAl electrode in the melt showed ca. 280 Ah/kg of discharge capacity at the potential plateau range about −1.5 V vs. Al.

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不燃性常温型溶融塩電解液を用いるロッキングチェア型リチウム二次電池のV₂O₅正極特性

小浦延幸, 宇井幸一, 武石和之

軽金属   47 ( 5 ) 273 - 278   1997年05月  [査読有り]

学術誌  共著・分担

The rocking chair type lithium secondary battery using a nonflammable LiCl saturated AlCl3–1–ethyl–3–methylimidazolium chloride (EMIC) electrolyte operated at ambient temperatures has been developed. In this paper, the positive electrode (crystalline V2O5) characteristics and the discharge-charge cycle performance in this electrolyte were investigated. The content of the intercalated lithium in V2O5 and the structure of LixV2O5 were observed. As a result, the main reaction during the discharge-charge cycle was considered to be the intercalation and deintercalation reactions of lithium in the V2O5. When the discharge-charge cycle of the V2O5 electrode was performed, the life of the cycle ability was over more than 100. The nonflammable rocking chair type Li–Al¦LiCl saturated AlCl3–EMIC ¦ V2O5 secondary cell showed 3.2~2.0 V discharge voltage and 150 Ah/kg of discharge capacity.

DOI

Discharge-Charge Characteristic of K -β-ferrite as Electrode Active Material for Lithium Secondary Battery

S. Ito, K. Ui, M. Ito, N. Koura, and K. Akashi

Journal of the Magnetics Society of Japan   22 ( 5 ) 449 - 451   1998年05月  [査読有り]

学術誌  共著・分担

Lithium secondary battery using potassium -β- ferrite as a new cathode active material

S. Ito, K. Ui, N. Koura, and K. Akashi

Solid State Ionics   113-115   17 - 21   1998年11月  [査読有り]

学術誌  共著・分担

Lithium insertions into K+-β-ferrite (K1.4Fe11O17) were investigated by the ion exchange in the lithium salts and by the reduction of Fe3+ in a 1.6 M solution of n-butyl-lithium (BuLi) in hexane. Li0.4K0.9Fe11O17 with β-ferrite structure was obtained by soaking K+-β-ferrite powder in an LiCl n-hexyl alcohol solution at 150°C for 60 h. However, when the K+-β-ferrite powders were soaked in a molten salt of LiNO3 at 270 to 310°C for 20 h, the β-structures were destroyed. It is concluded that the lithium ions can be exchanged up to 0.4 with potassium ions in the alkali layers without destruction of the β-structure. Although the original K+-β-ferrite maintained β-structure at 1000°C, Li0.4K0.9Fe11O17 maintained β-structure up to 600°C. On the other hand, by soaking K1.4Fe11O17 in a BuLi at 25°C for 20 days, K1.2Li2.2Fe11O17 containing a large amount of lithium was obtained without destruction of the β-structure. This structure was not destroyed by heating the K1.2Li2.2Fe11O17 at 600°C. It is concluded that most of lithium ions are intercalated into the spinel blocks of β-ferrite. The results were compared to those of the electrochemical insertion.

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Li and Li-Al Negative Electrode Characteristics for the Lithium Secondary Battery with a Nonflammable SOCl₂, Li Added, LiCl Saturated AlCl₃-EMIC Molten Salt Electrolyte

Nobuyuki KOURA, Kazutaka IIZUKA, Yasushi IDEMOTO, Koichi UI

Electrochemistry ( The Electrochemical Society of Japan )  67 ( 6 ) 706 - 712   1999年06月  [査読有り]

学術誌  共著・分担

An AlCl3-1-ethyl-3-methylimidazolium chloride (EMIC) melt has a wide electrochemical window, and it is nonflammable with no ignition. We have developed the rocking chair type lithium secondary battery with an AlCl3-EMIC melt containing excess LiCl with a saturated solubility as the nonflammable electrolyte. In this paper, when LiCl was added in the acidic melt (AlCl3 > 50 mol %), the solubility of the LiCl and the changes in the physical properties were measured. Moreover, SOCl2 or Li metal was treated to completely remove any small amounts of Al2Cl7−, which was the ionic species for deposited Al, that remained in the melt. As a result, it was confirmed that Al2Cl7− was completely removed based on a cyclic voltammogram (C.V.) using a W electrode. The reversible deposition and dissolution behavior of lithium was indicated from the C.V. for a Li electrode in the SOCl2 containing melt, and it was found that a Li metal would perform as the negative electrode active material.

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泳動電着法を用いたバインダーフリー炭素材料膜の作製

小浦延幸, 對木洋文, 寺倉典宏, 井手本　康, 松本　太, 宇井幸一, 山田和夫, 見立武仁

表面技術 ( 一般社団法人　表面技術協会 )  52 ( 1 ) 143 - 144   2001年01月  [査読有り]

学術誌  共著・分担

DOI

泳動電着法を用いたリチウム二次電池用炭素負極の作製

小浦延幸, 府野真也, 對木洋文, 井手本　康, 宇井幸一, 松本　太

表面技術 ( 一般社団法人　表面技術協会 )  53 ( 10 ) 683 - 687   2002年10月  [査読有り]

学術誌  共著・分担

The electrophoretic deposition of the artificial graphite particle, KS-25, on Cu foil has been examined in an acetonitrile bath containing additives such as triethylamine (TEA), tetramethylguanidine (TMG), and pyridine (Py). The charge-discharge capability of carbon anode for the Li-ion secondary battery prepared by the electrophoretic deposition method was estimated. Graphite particles were deposited electrophoretically on the anode substrate. The amount of graphite particle on Cu foil increased with an increasing deposition voltage, deposition time, and TEA concentration and was controllable in the range from 0 to 10mg·cm-2. The carbon anode provided relatively flat charge and discharge potentials (0 to 0.3V vs. Li/Li+) and high current capability (310mAh·g-1). Compared with the carbon anode composed of artificial graphite particles having a smaller grain size (KS-6), improvement in charge-discharge efficiency of the carbon anode with KS-25 particles was able to be observed in several of the early cycles. Moreover, the relationship between the ζ-potential and additive concentration, as well as the relationship between the amount of graphite particles deposited on Cu substrate and pKa of additives, and the results of the XPS measurement of graphite particle surface suggested that the charging of the graphite particle surface was caused by the deprotonation of carboxyl and alcohol groups by additives such as TEA, TMG, and Py.

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Bi_1.76Pb_0.44Sr_1.86Ca_2.08-xY_xCu_2.86O_y超伝導酸化物におけるTc, JcのY置換量、酸素量依存

井手本　康, 津之地洋平, 宇井幸一, 小浦延幸

日本セラミックス協会学術論文誌 ( 社団法人　日本セラミックス協会 )  111 ( 10 ) 781 - 785   2003年10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 a Bi-2223 system by the replacement of Bi and Ca by Pb and Y, respectively, to form Bi1.76Pb0.44Sr1.86Ca2.08-xYxCu2.86Oy. The relation between lattice constant, average valences of Bi+Pb and Cu, excess oxygen content and superconducting characteristics has been studied as a function of Y substitution content, and anneal treatment. The highest Tc was obtained at x=0.05. Oxygen doped and overdoped regions and highest Tc(zero), which were obtained upon adjusting the optimum excess oxygen content, existed at each Y content, x=0-0.30. Furthermore, in order to elucidate the effect of metal substitution and oxygen content on Jc of a Bi-2223 system, films were prepared, which have the same metal composition of bulk, on a MgO(100) single crystal substrate by the spin coating-pyrolysis method. The measurements of Jc and Tc were carried out on highly oriented films of Bi-2223 phase with changing Y content. The highest Tc(zero) was obtained at Y content, x=0.05. Tc(zero) decreased with increasing x in the region of x>0.05. On the other hand, the highest Jc was obtained at x=0.10. The Y content for optimum Jc was different from that for optimum Tc. Jc increased with increasing excess oxygen content, Δy, and after that increase or constant in the oxygen overdoped region. Consequently, the metal and oxygen contents were very important for obtaining the highest Tc and Jc.

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Dependence of Li content on Crystal Structure during the Charge-Discharge Process of LiMn_1.5Ni_0.5O₄ as a Cathode Materials for 5V Class Lithium Secondary Battery

Yasushi IDEMOTO*, Hiroshi SEKINE, Koichi UI, and Nobuyuki KOURA

Electrochemistry ( The Electrochemical Society of Japan )  71 ( 12 ) 1142 - 1144   2003年12月  [査読有り]

学術誌  共著・分担

We investigated the crystal structure change during the charge-discharge process of LiMn1.5Ni0.5O4 as a 5 V class cathode active material, which was prepared by 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 constant and Ni valences. The each phase showed a different distortion of the Mn,Ni (12d)-O octahedral site and the Madelung energy.

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Electronic States of Li_yMn_2-xM_xO₄ (M=Mn, Mg, Ni, Co) as a cathode Active Material for Li Secondary Battery by First-Principles Calculation using DV-Xα Method

Yuka ITO, Yasushi IDEMOTO*, Koichi UI, Nobuyuki KOURA

Electrochemistry ( The Electrochemical Society of Japan )  71 ( 12 ) 1145 - 1147   2003年12月  [査読有り]

学術誌  共著・分担

e investigated the electronic states of LiyMn2−xMxO4 (M = Mn, Mg, Ni, Co) as cathode active materials for the 4 V class lithium secondary battery. We calculated the electronic states of LiyMn1.75M0.25O4 (M = Mn; y = 0, Mg, Ni; y = 0.5, Co; y = 0.25) using first-principles calculations by the DV-Xα method. The net charge of each atom, and the bond overlap populations of Mn-O and M-O were calculated. The strong covalency between Mn and O existed in the Li defect model and LiyMn1.75M0.25O4 (M = Mg, Ni, Co). The bonding change in Mn-O is small and maintained the spinel structure during the charge-discharge process by substitution of Mn with M (= Mg, Ni, Co).

DOI

Enhancement of electrochemical oxidation of glucose at Hg adatom-modified Au electrode in alkaline aqueous solution

Futoshi MATSUMOTO*, Masahiro HARADA, Nobuyuki KOURA, Yasushi IDEMOTO, Koichi UI

Electrochemistry ( The Electrochemical Society of Japan )  72 ( 2 ) 103 - 110   2004年02月  [査読有り]

学術誌  共著・分担

Origin of enhanced electrochemical oxidation of glucose observed around 0.3 V (vs. Ag/AgCl (KCl sat.)) on an Hg adatom-modified Au polycrystalline electrode in alkaline aqueous solutions was investigated by cyclic voltammetry in various potential regions and solution pH's. The enhanced oxidation current was stable under continuous cycling between - 0.55 and 0.35 V. Positive scanning of potentials to greater than 0.35 V caused the oxidation current to decrease with dissolution of the UPD adlayer of Hg from the Au electrode. The surface structure of the Hg adatom-modified Au electrode found to be highly important in glucose oxidation. Moreover, pH dependence of the enhancement of glucose oxidation was attributed to the amount of adsorbed OH- on the Hg adatom-modified Au electrode. The investigation revealed that the surface structure on the Hg adatom-modified Au electrode cased an increase in the amount of adsorbed OH- on the Hg adatom-modified Au electrode around 0.35 V. It was considered that OHad produced by partial discharge of OH- on the Hg adatoms and/or oxide layer (Au(OHad)) of Au surface catalyzed the oxidation of glucose on the Hg adatom-modified Au electrode.

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Photocatalytic Activity of Ag-TiO₂(anatase) Composite Film Prepared by Composite Coating

Fumio YAMAGUCHI, Tomohiro FUJITA, Yasuhiro KANEGA, Koichi UI, Yasushi IDEMOTO, Nobuyuki KOURA*

Electrochemistry ( The Electrochemical Society of Japan )  72 ( 3 ) 156 - 158   2004年03月  [査読有り]

学術誌  共著・分担

The photocatalytic reaction with TiO2 particle using sunlight which decomposes various environmental pollutants has been studied extensively. This study considered the immobilization of the TiO2(A) particle on a brass substrate by a composite coating method. It was found that photocatalytic activity changed with differences in the immobilization metal (Ag, Ni, Pd, Cu)-TiO2(A) and the Ag-TiO2(A) composite film was shown the most remarkable photocatalytic activity.

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AlCl₃-EMIC常温型溶融塩を用いたアルミニウム配向電析　－キシレン混合による配向性に及ぼす影響－

宇井幸一, 八代高士, 二村昌樹, 井手本　康, 小浦延幸

表面技術 ( 一般社団法人　表面技術協会 )  55 ( 6 ) 409 - 416   2004年06月  [査読有り]

学術誌  共著・分担

An aluminum deposit oriented to a specific face is obtained from Lewis acidic aluminum chloride (AlCl3) 1-ethyl-3-methylimidazolium chloride (EMIC) ambient-temperature molten salt. We tried to stably produce the oriented deposit with a flat and smooth surface from the AlCl3-EMIC melt with xylene isomers added. Study of aluminum deposition from the xylene-added bath made it possible to investigate the mechanism of the oriented deposition.
Aluminum oriented to (110) was electrodeposited from the acidic melt with o-, p-xylene added. On the other hand, aluminum oriented to (100), which has never been obtained, was deposited from the melt with 50mol% m-xylene added after being aged four hours from the bath preparation. Moreover, the deposit had metallic luster. Using SEM, tried to find out the relation between the orientation and the metallic luster. The deposit with metallic luster had a very flat surface. The deposit without metallic luster had a textural structure. Furthermore, we observed the initial state of the deposit by the AFM technique. Prior nucleation took place in the case of the metallic deposit oriented to (100). Prior crystal grain growth took place in the case of the nonmetallic deposit oriented to (110).

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5V級Li二次電池用正極活物質LiMn_1.5Ni_0.5O₄の合成条件による物性、結晶構造と電極特性の関係

井手本　康*, 関根　裕, 宇井幸一, 小浦延幸

Electrochemistry ( The Electrochemical Society of Japan )  72 ( 8 ) 564 - 568   2004年08月  [査読有り]

学術誌  共著・分担

We investigated the physical property, crystal structure and electrode performance of LiMn1.5Ni0.5O4 as a 5 V class cathode active material, which was prepared by changing the calcined temperature with the sol-gel method. Cycle performance is different from the calcined temperature. LiMn1.5Ni0.5O4, which calcined at 700°C, showed a good cycle performance with the maximum discharge capacity of 125.3 mAh/g, and the capacity after 100 cycles was 95.1% of the maximum capacity. The crystal structure was determined by Rietveld analysis using powder neutron diffraction. From a result, LiMn1.5Ni0.5O4, which calcined at 650°C, composed of mixing two space group P4332 phases. It is suggested that the oxidation states of Ni change in the sample, as these phases are different from each lattice parameter. Ni valence of sub-phase for LiMn1.5Ni0.5O4 calcined at 650°C, which was calculated from Bond Valence Sum, increase. Moreover, we investigated, the distortion and the stability of crystal structure by the bond length and the Madelung energy, nuclear and electron densities by MEM method with neutron diffraction and X-ray diffraction.

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Li二次電池正極材料Li_xMn_2-yM_yO₄(M=Mg, Al, Cr, Mn)の熱力学安定性および結晶構造のLi量依存

井手本　康*, 堀子和孝, 宇井幸一, 小浦延幸

Electrochemistry ( The Electrochemical Society of Japan )  72 ( 10 ) 680 - 687   2004年10月  [査読有り]

学術誌  共著・分担

We investigated the relation between the thermodynamic stability and crystal structure dependence of Li content for the substituted spinel, LixMn2-yMyO4 (M = Mg, Al, Cr, Mn). The enthalpy change per mole of atoms for the formation reaction, ΔHR, were calculated from the heat of dissolution. ΔHR increased with the decreasing Li content. ΔHR of the all amounts of Li content for LixMn2-yMyO4 (M = Mg, Al, Cr, Mn) decreased compared to that of LixMn2-yMyO4. The crystal structure analysis by powder neutron diffraction was examined for LixMn2-yMyO4 (M = Mg, Al, Cr, Mn). The Madelung energy increases with decreasing Li content for LixMn2O4, and it was associated with the thermodynamic data. From these results, the host structure is structurally and thermodynamically stable of the all amounts of Li content with the substitution of M for LixMn2-yMyO4.

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化学的に脱LiしたLi二次電池正極活物質Li_xMn_2-yM_yO₄(M=Mg, Al, Cr, Mn, Co, Zn, Ni)の結晶構造、電子構造のLi量依存

井手本　康*, 堀子和孝, 伊藤由賀, 小浦延幸, 宇井幸一

Electrochemistry ( The Electrochemical Society of Japan )  72 ( 11 ) 755 - 762   2004年11月  [査読有り]

学術誌  共著・分担

We investigated the crystal structure, electronic structure and nuclear state of chemical delithiated spinel LixMn2-yMyO4 (M = Mg, Al, Cr, Mn, Co, Zn, Ni) dependence Li content, x. We obtained the electronic and nuclear density distributions of the samples from XRD and neutron diffraction data using the maximum entropy method. Li content of LixMn2-yMyO4 was controlled by changing concentration of H2SO4-H2O aqueous solution. Mn valence increased and lattice parameter, a, decreased with decreasing Li content. The electron of Li0.095Mn2O4 was delcolization from the results of electronic density distribution. The amount of change of covalent bonding of (Mn, M)-O for LixMn2-yMyO4 (M = Mg, Al, Cr, Co, Zn, Ni) decreased in comparison with that of LixMn2O4 when Li content changed. From the results, the host structure is stable with the substitution of M for LixMn2-yMyO4.

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Bi_4-x+yLa_xTi₃O_12-d(x=0.5, y=0; x=0.75, y=0;x=0.75, y=0.15)強誘電体セラミックスの熱処理による強誘電特性への影響

井手本　康, 横山直人, 小浦延幸, 宇井幸一

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 )  112 ( 12 ) 669 - 673   2004年12月  [査読有り]

学術誌  共著・分担

We investigated the effect of ferroelectric property on heat treatment at high oxygen partial pressure or vacuum for Bi4-x+yLaxTi3O12-δ (x=0.75, y=0; x=0.50, y=0; x=0.75, y=0.15). The remnant polarization (Pr) increases with increasing oxygen partial pressure during heat treatment. The coercive electric field (Ec) showed the same tendency as Pr at x=0.75 and y=0. In x=0.5 and y=0, Ec decreased with increasing oxygen partial pressure during heat treatment. Tc decreased by heat treatment under high oxygen partial pressure.

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