Published Papers - UI Koichi

Cathode Performance of Lithium Non-stoichiometric Li[Li_x(Ni_1/3Co_1/3Mn_1/3)_1-x]O₂ Material for Li-ion Batteries

Jung-Min Kim, Naoaki Kumagai*, Yoshihiro Kadoma, Koichi Ui, and Hitoshi Yashiro

ITE Letters on Batteries, New Technologies & Medicine   7 ( 5 ) 454 - 457   2006.10  [Refereed]

Academic Journal  Multiple authorship

Preparation of Pb-Zr-Ti-Nb-Si-O Ferroelectric Thick Film by Electrophoretic Deposition

Yasushi Idemoto*, Satoshi Yoshida, Koichi Ui, and Nobuyuki Koura

Electrochemistry   74 ( 11 ) 883 - 889   2006.11  [Refereed]

Academic Journal  Multiple authorship

A Local Structure Analysis of Molten Li₂CO₃ Using the Density Functional Theory

Hidetoshi Morita, Hideaki Ohata, Ken Takeuchi, Koichi Ui, Kozo Kozawa, and Nobuyuki Koura*

Electrochemistry   75 ( 6 ) 466 - 471   2007.06  [Refereed]

Academic Journal  Multiple authorship

Fabrication of Electrode for Capacitor Cell Prepared by Electrophoretic Deposition Method

Koichi Ui*, Kazuma Okura, Nobuyuki Koura, Satoru Tsumeda, and Kenji Tamamitsu

Electrochemistry   75 ( 8 ) 604 - 606   2007.08  [Refereed]

Academic Journal  Multiple authorship

Equilibrium Geometries and Structural Stability of the Al_mNa_n (m=2-4; n=1-8) Clusters

Hidenori Matsuzawa*, Kazuhiro Sato, Takuji Hirata, Koichi Ui, and Nobuyuki Koura

J. Chem. Theory Comput. ( American Chemical Society )  3 ( 5 ) 1818 - 1829   2007.09  [Refereed]

Academic Journal  Multiple authorship

The stable geometries and formation processes of the AlmNan (m = 2-4; n = 1-8) clusters were investigated using the density functional theory (DFT). The Alm (m = 2-4) structures are maintained in the clusters. The Na atoms are attached to the Al-Al bond or Al plane for less than n = 4 in the AlmNan (m = 2-4) clusters. The odd electron of the attached Na atom is transferred to the Alm part for n 4 or 5 in the AlmNan (m = 2-4) clusters since the Alm part becomes stable. The Na-Na bonding is formed by the attached Na atom after saturation of the Al-Al bonds or Al atoms. The Al2Na5, Al3Na5, Al3Na6, Al3Na7, and Al3Na8 clusters have a characteristic structure. The Na wing is formed in the Al3Nan (n = 5-8) clusters. The 2S shell containing the 3s orbital of the Na atom and the 3p orbital of the Al atom becomes stable before the occupation of the 1D shell because the electrons are delocalized on the Na plane for n 5 in the AlmNan (m = 2-4) clusters. The stability of the AlmNan (m = 2-4; n = 1-8) clusters was evaluated by comparison of the vertical ionization potential (IP), HOMO-LUMO gap, adsorption energy of the Na atom, and binding energy per atom.


DOI

Electrochemical Properties of Li_1+x(Ni_0.4Co_0.2Mn_0.4)_1-xO₂ (x = 0.00 and 0.05) for Lithium-ion Batteries

Jung-Min Kim, Yoshihiro Kadoma, Koichi Ui, and Naoaki Kumagai*

ITE Letters on Batteries, New Technologies & Medicine   8 ( 5 ) B12 - B16   2007.10  [Refereed]

Academic Journal  Multiple authorship

Development of novel anodic catalyst for solid oxide fuel cell operated at intermediate-temperature direct utilizing of dimethylether fuel

Ken Takeuchi*, Yousuke Ishida, Kenta Kasuya, Ryosuke Tai, Hideki Koyanaka, Koichi Ui, and Nobuyuki Koura

Electrochemistry   75 ( 10 ) 786 - 790   2007.10  [Refereed]

Academic Journal  Multiple authorship

Improvement of Electrochemical Characteristics of Natural Graphite Negative Electrode Coated with Polyacrylic Acid in Pure Propylene Carbonate Electrolyte

Koichi Ui, Shinei Kikuchi; Fuminobu Mikami; Yoshihiro, Kadoma, and Naoaki Kumagai*

J. Power Sources   173 ( 1 ) 518 - 521   2007.11  [Refereed]

Academic Journal  Multiple authorship

In order to improve the negative electrode characteristics of a graphite electrode in a propylene carbonate (PC)-containing electrolyte, we have prepared a graphite negative electrode coated with a water-soluble anionic polymer as a binder for composite graphite electrodes. The electrochemical characteristics of the coated graphite were evaluated by cyclic voltammetry and charge–discharge cycle tests. The coated graphite negative electrode showed a stable Li+ ion intercalation/deintercalation reaction without the exfoliation of the graphene layers caused by the co-intercalation of the PC solvent in the LiClO4/PC solution. The charge–discharge characteristic of the coated graphite negative electrode in a PC-containing electrolyte was almost the same as that in ethylene carbonate-based electrolyte.

DOI

Electrodeposition of Crack-Free Amorphous Zn-Ni Alloy from Ethylene Glycol Mixed ZnCl₂-NiCl₂-EMIC Ambient-Temperature Molten Salt Bath

Nobuyuki KOURA*, Naoko KAMIURA, Ken TAKEUCHI, Koichi UI, and Takashi YAMAZAKI

Journal of The Surface Finishing Society of Japan   58 ( 11 ) 682 - 688   2007.11  [Refereed]

Academic Journal  Multiple authorship

Synthesis of Hollandite-type Li_xMnO₂ by Li⁺ ion-exchange in molten salt and lithium insertion characteristics

Yoshihiro Kadoma, Satoru Oshitari, Koichi Ui, and Naoaki Kumagai*

Electrochim. Acta.   53 ( 4 ) 1697 - 1702   2007.12  [Refereed]

Academic Journal  Multiple authorship

Structural and Electrochemical Properties of Li⁺ Ion-exchanged Hollandite-type MnO₂ for Lithium-ion Batteries

Yoshihiro Kadoma, Naoaki Kumagai*, Satoru Oshitari, and Koichi Ui

ITE Letters on Batteries, New Technologies & Medicine   8 ( 6 ) 674 - 678   2007.12  [Refereed]

Academic Journal  Multiple authorship

Electroless Plating of Aluminum from a Room-Temperature Ionic Liquid Electrolyte

Nobuyuki Koura*, Hiroshi Nagase, Atsushi Sato, Shintaro Kumakura, Ken Takeuchi, Koichi Ui, Tetsuya Tsuda, and Chun K. Loong

J. Electrochem. Soc.   155 ( 2 ) D155- - D157   2008.02  [Refereed]

Academic Journal  Multiple authorship

Because aluminum is a less-noble metal which has the standard electrode potential of −1.676 V vs normal hydrogen electrode, it is impossible to obtain the electrodeposition of aluminum from an aqueous solution. No one has reported an electroless plating method of aluminum. We succeeded in demonstrating the electroless plating of aluminum from a room-temperature ionic liquid (RTIL). It was found from measurements of inductively coupled plasma, X-ray diffraction, scanning electron microscopy (SEM), SEM-energy-dispersive X-ray analysis, and glow discharge optical emission spectroscopy that dense, smooth, and pure aluminum plating was obtained from the RTIL by the electroless plating method. Moreover, the reaction mechanism of the electroless plating of aluminum from the RTIL electrolyte was electrochemically analyzed.

DOI

Structural Modification of Li[Li_0.27Co_0.20Mn_0.53]O₂ by Lithium Extraction and its Electrochemical Property as the Positive Electrode for Li-ion Batteries

Naoaki Kumagai*, Jung-Min Kim, Syo Tsuruta, Yoshihiro Kadoma, and Koichi Ui

Electrochim. Acta.   53 ( 16 ) 5287 - 5293   2008.06  [Refereed]

Academic Journal  Multiple authorship

DOI

Development of Non-flammable Lithium Secondary Battery with Room-temperature Ionic Liquid Electrolyte -Performance of Electroplated Al film negative electrode-

Koichi Ui*, Keigo Yamamoto, Kohei Ishikawa, T. Minami, Ken Takeuchi, Masayuki Itagaki, Kunihiro Watanabe, and Nobuyuki Koura

J. Power Sources   183 ( 1 ) 347 - 350   2008.08  [Refereed]

Academic Journal  Multiple authorship

DOI

A rechargeable lithium metal battery operating at intermediate temperatures using molten alkali bis(trifluoromethylsulfonyl)amide mixture as an electrolyte

Atsushi Watarai, Keigo Kubota, Masaki Yamagata, Takuya Goto, Toshiyuki Nohira, Rika Hagiwara, Koichi Ui, Naoaki Kumagai

J. Power Sources   183   724 - 729   2008.08  [Refereed]

Academic Journal  Multiple authorship

Characterization and electrochemical properties of Li⁺ ion-exchanged products of hollandite-type K_y(Mn_1-xCo_x)O₂ for rechargeable lithium battery electrodes

Yoshihiro Kadoma, Satoru Oshitari, Koichi Ui, and Naoaki Kumagai*

Solid State Ionics   179   1710 - 1713   2008.09  [Refereed]

Academic Journal  Multiple authorship

Development of the Fe-Ni Anodic Catalyst for Solid Oxide Fuel Cell Operated at　Intermediate- temperature Direct Utilizing of Dimethylether Fuel

Ryosuke Tai, Koichi Ui, Ken Takeuchi*, Kenjiro Fujimoto, and Shigeru Ito

Electrochemistry   77 ( 2 ) 149 - 151   2009.02  [Refereed]

Academic Journal  Multiple authorship

Development of the Fe Anodic Catalyst for Solid Oxide Fuel Cell Operated at Intermediate-temperature Direct Utilizing of Dimethylether Fuel

Yousuke ISHIDA, Ryosuke TAI, Koichi UI, Ken TAKEUCHI, Kenjiro FUJIMOTO, and Shigeru ITO

Electrochemistry   77 ( 3 ) 225 - 228   2009.03  [Refereed]

Academic Journal  Multiple authorship

Electrochemical Characteristics of Sn Film Prepared by Pulse Electrodeposition Method as Negative Electrode for Lithium Secondary Batteries

Koichi Ui*, Shinei Kikuchi, Yoshihiro Kadoma, Naoaki Kumagai, and Shigeru Ito

J. Power Sources   189   224 - 229   2009.04  [Refereed]

Academic Journal  Multiple authorship

DOI

Li⁺ Ion-exchanged Hollandite-type MnO₂ in Molten Salt at Several Temperatures and Electrochemical Properties for Lithium Battery Electrodes

Yoshihiro KADOMA, Ryo KIMURA, Koichi UI, and Naoaki KUMAGAI *

Electrochemistry   77 ( 8 ) 751 - 753   2009.08  [Refereed]

Academic Journal  Multiple authorship