Patents by Inventor Takahisa Ohsaki
Takahisa Ohsaki has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 6423447Abstract: There is proposed a non-aqueous electrolyte secondary battery having an electrode assembly which is impregnated with a non-aqueous electrolyte solution, wherein the battery can be made thin while maintaining improved capacity, large-current characteristics and cycle life. The non-aqueous electrolyte secondary battery comprises a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte solution. The production process of the battery comprises steps of preparing an electrode assembly by interposing a separator between a positive electrode and a negative electrode, impregnating the electrode assembly with an organic solvent which can dissolve the binder of the positive- and/or negative electrodes, bonding the positive electrode and the separator together and bonding the negative electrode and the separator together by drying the electrode assembly, and impregnating the electrode assembly with a non-aqueous electrolyte solution.Type: GrantFiled: March 14, 2000Date of Patent: July 23, 2002Assignee: Kabushiki Kaisha ToshibaInventors: Takahisa Ohsaki, Norio Takami, Hiroyuki Hasebe, Motoya Kanda, Asako Sato, Takashi Kuboki, Shuji Yamada
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Patent number: 6413679Abstract: Disclosed is a battery which has means which, upon the occurrence of an abnormal phenomenon, such as an overcharge or an external short circuit, rapidly operates a safety mechanism, such as a current breaking valve, to ensure the safety of the battery and which, particularly upon the occurrence of an abnormal phenomenon, can surely and stably increase the pressure within the battery. The battery comprises a positive electrode, a negative electrode, a separator, an electrolysis solution, and a hermetically sealed container, the hermetically sealed container containing in its interior a compound represented by formula (1): X—O—CO—R (1) wherein X represents a group which, upon decomposition of the compound caused by a rise in temperature, is eliminated to evolve a gas insoluble or slightly soluble in the electrolysis solution; and R represents a group which controls the decomposition temperature of the compound.Type: GrantFiled: March 14, 2000Date of Patent: July 2, 2002Assignee: Kabushiki Kaisha ToshibaInventors: Takashi Kuboki, Takahisa Ohsaki
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Patent number: 6350544Abstract: This invention provides a lithium secondary battery comprising a positive electrode, a negative electrode comprising a carbonaceous material which is capable of absorbing and desorbing lithium ions, and a nonaqueous electrolyte, wherein the carbonaceous material has a region of amorphous carbon structure and a region of graphite structure, and the carbonaceous material has a true density of 1.8 g/cm3 or more and a peak in powder X-ray diffraction which corresponds to not more than 0.340 nm in an interplanar spacing d002 derived from (002) reflection.Type: GrantFiled: March 18, 1998Date of Patent: February 26, 2002Assignee: Kabushiki Kaisha ToshibaInventors: Norio Takami, Asako Satoh, Takahisa Ohsaki
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Patent number: 6342319Abstract: This invention provides a nonaqueous electrolyte secondary battery including a negative electrode containing a carbonaceous material aggregate having a structure in which carbonaceous material plates are three-dimensionally distributed, the carbonaceous material plates being capable of absorbing and desorbing lithium ions and having a molar ratio of hydrogen to carbon of 0.2 to 0.4.Type: GrantFiled: March 12, 1998Date of Patent: January 29, 2002Assignee: Kabushiki Kaisha ToshibaInventors: Takashi Kuboki, Norio Takami, Takahisa Ohsaki
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Publication number: 20010018150Abstract: The present invention provides a nonaqueous electrolyte secondary battery, comprising a positive electrode, a negative electrode containing a carbon material having an immersion heat ratio (&Dgr;Hin/&Dgr;Hih) defined by formula (1), and a nonaqueous electrolyte:Type: ApplicationFiled: December 20, 2000Publication date: August 30, 2001Inventors: Tomokazu Morita, Takahisa Ohsaki, Norio Takami
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Patent number: 5795678Abstract: A negative electrode for use in a secondary battery which comprises milled graphite fibers derived from mesophase pitch each having circumferential, upper end and lower end faces, the milled graphite fibers each being composed of graphite layers having therebetween voids as inlets and outlets for lithium ions, all of the circumferential, upper end and lower end faces having openings of the voids between the graphite layers, which serve as inlets or outlets for lithium ions. This negative electrode for use in a secondary battery can be utilized to provide a lithium secondary battery of nonaqueous electrolyte which has large charge and discharge capacities and which permits setting the current density at charge or discharge high.Type: GrantFiled: March 31, 1995Date of Patent: August 18, 1998Assignees: Kabushiki Kaisha Toshiba, Petoca, Ltd.Inventors: Norio Takami, Takahisa Ohsaki, Toshio Tamaki, Hideyuki Nakajima, Yasushi Katsuta
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Patent number: 5753387Abstract: This invention provides a lithium secondary battery comprising a positive electrode, a negative electrode comprising a carbonaceous material which is capable of absorbing and desorbing lithium ions, and a nonaqueous electrolyte, wherein the carbonaceous material has a region of amorphous carbon structure and a region of graphite structure, and the carbonaceous material has a true density of 1.8 g/cm.sup.3 or more and a peak in powder X-ray diffraction which corresponds to not more than 0.340 nm in an interplanar spacing d.sub.002 derived from (002) reflection.Type: GrantFiled: November 22, 1996Date of Patent: May 19, 1998Assignee: Kabushiki Kaisha ToshibaInventors: Norio Takami, Asako Satoh, Takahisa Ohsaki
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Patent number: 5612155Abstract: A lithium ion secondary battery improved in large-current discharge characteristics, discharge capacity, and cycle life is disclosed. This lithium ion secondary battery includes a positive electrode, a negative electrode comprising a collector and carbon fibers held to the collector for absorbing and desorbing lithium ions, a separator arranged between the positive electrode and the negative electrode, and a nonaqueous electrolyte. The carbon fibers have a radial orientation from an axis of the fibers, and 50 vol % or more of all carbon fibers are arranged such that an angle between an axis of each carbon fiber and a surface of the collector is 45.degree. or less.Type: GrantFiled: June 13, 1995Date of Patent: March 18, 1997Assignees: Kabushiki Kaisha Toshiba, Toshiba Battery Co, Ltd.Inventors: Norio Takami, Takahisa Ohsaki, Yoshiaki Asami
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Patent number: 5556723Abstract: A negative electrode for use in a secondary battery is disclosed, comprising milled carbon fibers derived from mesophase pitch wherein the milled carbon fibers each has a fiber cut surface and a fiber axis intersecting with each other at cross angles, the smaller one thereof being at least 65.degree. on the average. This negative electrode does not suffer from property deterioration, irrespective of multiple repetitions of charge and discharge, from which a nonaqueous-electrolyte-loaded lithic secondary battery having excellent cycle characteristics can be fabricated.Type: GrantFiled: September 15, 1994Date of Patent: September 17, 1996Assignees: Kabushiki Kaisha Toshiba, Petoca, Ltd.Inventors: Takahisa Ohsaki, Norio Takami, Yoshiyuki Nishimura, Toshio Tamaki
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Patent number: 5498492Abstract: A lithium secondary battery with a large capacity and a long cycle life is disclosed. This lithium secondary battery includes a case, a negative electrode accommodated in the case and containing a polymeric material which has been formed by heat-treating a polymer having a perynaphthalene structure as a main repeating unit in a non-oxidizing atmosphere at 500.degree. to 1000.degree. C. and which absorbs and desorbs lithium ions, a positive electrode accommodated in the case and so arranged as to oppose the negative electrode with a separator sandwiched between them, and a nonaqueous electrolyte contained in the case.Type: GrantFiled: September 15, 1994Date of Patent: March 12, 1996Assignee: Kabushiki Kaisha ToshibaInventors: Michikazu Hara, Asako Satoh, Norio Takami, Takahisa Ohsaki
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Patent number: 5340670Abstract: A lithium secondary battery having a high capacity and excellent in charge-discharge efficiency, cycle life, flatness of a discharge voltage, and rapid charge-discharge cycle characteristics is disclosed. This lithium secondary battery includes a positive electrode housed in a case, a negative electrode housed in the case and containing a carbonaceous material which has an exothermic peak at 700.degree. C. or more when measured by a differential thermal analysis and an intensity ratio P.sub.101 /P.sub.100 of a (101) diffraction peak P.sub.101 to a (100) diffraction peak P100 of a graphite structure, obtained by X-ray diffraction analysis, of 0.7 to 2.2, and absorbs and desorbs lithium ions, a separator housed in the case so as to be arranged between the positive and negative electrodes, and a nonaqueous electrolyte contained in the case.Type: GrantFiled: June 1, 1993Date of Patent: August 23, 1994Assignee: Kabushiki Kaisha ToshibaInventors: Norio Takami, Asako Satoh, Takahisa Ohsaki
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Patent number: 5312611Abstract: A lithium secondary battery which comprises a vessel, a positive electrode, a negative electrode and an electrolyte. Both of the electrodes are placed in the vessel and the vessel is filled with the electrolyte. The negative electrode includes carbonaceous material spherical particles or carbonaceous fibers which absorb and discharge lithium ions. The carbonaceous material has a graphite-like layered structure part and a turbulence-layered structure part. Fine structures of the carbonaceous material spherical particles are arranged in point-orientation.Type: GrantFiled: June 16, 1993Date of Patent: May 17, 1994Assignee: Kabushiki Kaisha ToshibaInventors: Norio Takami, Takahisa Ohsaki
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Patent number: 5272022Abstract: A nonaqueous electrolyte secondary battery having an enhanced capacity and a long charge/discharge cycle life is disclosed. The nonaqueous electrolyte secondary battery comprises a positive electrode housed in a case and containing a chalcogen compound as an active material, a negative electrode arranged in the case such that a separator is sandwiched between the positive and negative electrodes and containing a carbonaceous material as an active material that absorbs and discharges lithium ions and a nonaqueous electrolyte contained in the case and prepared by dissolving 0.5 mol/l to 1.5 mol/l of electrolytic salt selected from the group consisting of LiPF.sub.6, LiBF.sub.4, LiAsF.sub.6 and LiCF.sub.3 SO.sub.3 in a solvent mixture comprising at least one first nonaqueous solvent selected from the group consisting of noncyclic carbonate, cyclic carbonate, .gamma.Type: GrantFiled: September 27, 1991Date of Patent: December 21, 1993Assignees: Kabushiki Kaisha Toshiba, Toshiba Battery Co., Ltd.Inventors: Norio Takami, Takahisa Ohsaki, Norihito Kurisu, Kuniaki Inada
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Patent number: 5079109Abstract: A nonaqueous electrolyte secondary battery comprising a positive electrode housed in a case a negative electrode arranged in the case so that a separator is sandwiched between the positive and negative electrodes consisting of lithium or lithium-containing material, and a nonaqueous electrolyte contained in the case and prepared by dissolving an electrolytic salt consisting of lithium phosphate hexafluoride (LiPF.sub.6) or lithium borofluoride (LiBF.sub.4) in a solvent mixture consisting of ethylene carbonate, 2-methyltetrahydrofuran, and at least one ester-based nonaqueous solvent selected from the group consisting of butylene carbonate, dimethyl carbonate, .gamma.-butyrolactone, and sulfolane.Type: GrantFiled: May 15, 1990Date of Patent: January 7, 1992Assignees: Kabushiki Kaisha Toshiba, Toshiba Battery Co., Ltd.Inventors: Norio Takami, Takahisa Ohsaki, Kuniaki Inada, Norihito Kurisu, Shuji Yamada, Junichi Takabayashi
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Patent number: 4767683Abstract: A non-aqueous electrochemical cell has an anode consisting of an element selected from the group consisting of lithium, sodium and aluminum; a cathode consisting of a porous carbon body and a current collector; and an electrolyte containing an oxyhalide, wherein the porous carbon body contains a carbon black having a structure wherein a thin layer of graphite crystals is formed on a surface of each of chain-like carbon black particles. The cell has a high discharge capacity and an excellent discharge efficiency in high rate discharge.Type: GrantFiled: December 7, 1987Date of Patent: August 30, 1988Assignees: Tokyo Shibaura Denki Kabushiki Kaisha, Toshiba Battery Co., Ltd.Inventors: Shuji Yamada, Takahisa Ohsaki, Kiyoshi Mitsuyasu, Yuichi Sato, Yoshiyasu Aoki, Kazuya Hiratsuka