Patents by Inventor Tetsuya Kajita

Tetsuya Kajita 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).

  • Patent number: 8956762
    Abstract: In a lithium ion secondary battery including a positive electrode, a separator, a negative electrode, and a package body, the negative electrode includes simple substance silicon as a negative electrode active material, and a negative electrode binder, and is doped with lithium, and the following formulas (1) and (2) are satisfied: 1.2?Ma/Mc?1.9??(1) 1.0<Ma/(Mc+MLi)<1.6??(2) wherein an amount of lithium inserted into the negative electrode until the negative electrode reaches a potential of 0.02 V with respect to metal lithium is Ma (a number of atoms), an amount of lithium released from the positive electrode until the positive electrode reaches a potential of 4.3 V with respect to metal lithium is Mc (a number of atoms), and an amount of lithium with which the negative electrode is doped is MLi (a number of atoms).
    Type: Grant
    Filed: July 29, 2011
    Date of Patent: February 17, 2015
    Assignees: NEC Corporation, NEC Energy Devices, Ltd.
    Inventors: Ryuichi Kasahara, Jiro Iriyama, Tetsuya Kajita, Hiroo Takahashi, Tatsuji Numata, Daisuke Kawasaki
  • Publication number: 20150037671
    Abstract: It is an object of the exemplary embodiment of the present invention to provide a method for manufacturing a negative electrode for a lithium secondary battery by which conductive metal particles can be uniformly and easily formed in a conductive intermediate layer. The exemplary embodiment of the present invention is a method for manufacturing a negative electrode for a lithium secondary battery comprising a current collector comprising a metal, an active material layer comprising an active material and a binding agent, and a conductive intermediate layer comprising conductive metal particles between the current collector and the active material layer, comprising steps of (1) placing a polyamic acid on the current collector; (2) causing the metal to move from the current collector into the polyamic acid by generating migration phenomenon; and (3) heating and curing the polyamic acid, in this order, wherein the metal that has moved into the polyamic acid forms the conductive metal particles.
    Type: Application
    Filed: October 16, 2012
    Publication date: February 5, 2015
    Inventors: Jiro Iriyama, Tetsuya Kajita
  • Patent number: 8766837
    Abstract: The disclosed device easily and precisely satisfies a requested output range, and is provided with: a ??-modulator (12) which converts a digital input signal to a pulse signal; an input comparison device (11) which compares an input value that corresponds to the digital input signal, and a pre-set threshold value; and a thinned output control unit (14) which, when the result of the comparison by the input comparison device (11) shows that the input value is less than the threshold value, reduces the output value corresponding to the input value in accordance with the size of the difference between the input value and the threshold value, and sets the output value to 0 when the input value is 0.
    Type: Grant
    Filed: September 30, 2010
    Date of Patent: July 1, 2014
    Assignee: Azbil Corporation
    Inventors: Tetsuya Kajita, Seita Nashimoto, Naoki Nagashima, Kouji Okuda
  • Publication number: 20140076729
    Abstract: The object of an exemplary embodiment of the invention is to provide a negative electrode having excellent cycle property. An exemplary embodiment of the invention a method for doping and dedoping lithium for the first time after a negative electrode for a lithium secondary battery comprising silicon oxide as an active material is produced, comprising doping the lithium within the following current value range (A) and within the following doped amount range (B); current value range (A): a range of a current value in which a doped amount in which only one peak appears at 1 V or less on the V-dQ/dV curve becomes maximum, wherein the V-dQ/dV curve represents a relationship between voltage V of the negative electrode with respect to a lithium reference electrode and dQ/dV that is a ratio of variation dQ of lithium dedoped amount Q in the negative electrode to variation dV of the voltage V, and doped amount range (B): a range of a doped amount in which only one peak appears at 1 V or less on the V-dQ/dV curve.
    Type: Application
    Filed: April 6, 2012
    Publication date: March 20, 2014
    Inventors: Jiro Iriyama, Tetsuya Kajita, Daisuke Kawasaki, Tatsuji Numata
  • Publication number: 20140045069
    Abstract: Provided is a lithium secondary cell in which elution of manganese from a manganese olivine compound into an electrolyte is suppressed, a high level of safety is obtained, the charge/discharge cycle efficiency and suppression of leakage of manganese during storage can be maintained over a long period, a long lifespan is obtained, a rapid decrease in cell voltage near the end of discharge is suppressed, and output characteristics are enhanced, when a manganese olivine compound having excellent stability during charge/discharge is used as the principal component in the positive electrode active material. The positive electrode contains a positive electrode active material containing an olivine compound represented by LiMm1-aXaPO4 (where X represents Mg and/or Fe, and a represents a value that satisfies 0?a?0.3) and a lithium nickel oxide represented by LiNi1-bZbO2 (where Z represents one or more selected from Co, Mn, Al, Mg, and V; and b represents a value that satisfies 0?b?0.
    Type: Application
    Filed: April 27, 2012
    Publication date: February 13, 2014
    Inventors: Tatsuji Numata, Tetsuya Kajita, Hiroo Takahashi, Daisuke Kawasaki
  • Publication number: 20140045063
    Abstract: Provided is a negative electrode active material for a lithium secondary cell, the material having the function of a binder for the active material, and being capable of stable reversible reactions with lithium. Also, provided are an extended-life lithium secondary cell having improved energy density and stable charge/discharge, and a method for producing the same. The negative electrode active material for a lithium secondary cell is polyimide represented by formula (1) (wherein R1 and R2 independently denote an alkyl, alkoxy, acyl, phenyl, or phenoxy group).
    Type: Application
    Filed: April 27, 2012
    Publication date: February 13, 2014
    Inventors: Jiro Iriyama, Tetsuya Kajita, Daisuke Kawasaki, Tatsuji Numata, Kazuhiko Inoue
  • Publication number: 20130280594
    Abstract: In a nonaqueous electrolyte secondary battery using silicon and silicon oxide as a negative electrode active material, the charge and discharge cycle characteristics are improved. A nonaqueous electrolyte secondary battery in the exemplary embodiment comprises a sheet-shaped negative electrode comprising a negative electrode active material layer comprising a composite of silicon and silicon oxide formed on a negative electrode current collector, and a sheet-shaped positive electrode comprising a positive electrode active material layer formed on a positive electrode current collector, wherein the negative electrode is disposed opposed to the positive electrode via a separator, a peripheral edge portion of the negative electrode active material layer is disposed within a peripheral edge portion of the positive electrode active material layer, and a relationship of 1.00<c is satisfied when a charge capacity of the positive electrode is a, a charge capacity of the negative electrode is b, and b/a=c is set.
    Type: Application
    Filed: January 18, 2011
    Publication date: October 24, 2013
    Applicant: NEC ENERGY DEVICES, LTD.
    Inventors: Tetsuya Kajita, Ryuichi Kasahara, Jiro Iriyama, Tatsuji Numata
  • Publication number: 20130252106
    Abstract: Provided is a nonaqueous electrolytic solution secondary battery having a high energy density, and a positive electrode and a negative electrode used therefor. The nonaqueous electrolytic solution secondary battery includes a positive electrode and a negative electrode, wherein: the negative electrode contains a negative electrode active material having an initial charge/discharge efficiency of 75% or less when charged and discharged by employing metallic Li as a ocounter electrode; and the positive electrode contains a metal oxide (X) represented by AxMeOy (wherein A is Na and/or K, Me is Ni and/or Cu, x satisfies 1.9?x?2.1, and y satisfies 1.9?y?2.1).
    Type: Application
    Filed: December 9, 2011
    Publication date: September 26, 2013
    Applicant: NEC CORPORATION
    Inventors: Tatsuji Numata, Hiroo Takahashi, Tetsuya Kajita
  • Publication number: 20130244086
    Abstract: Provided are a negative electrode for a secondary battery realizing satisfactory cycle characteristics and a method for manufacturing the same, and a nonaqueous electrolyte secondary battery having satisfactory cycle characteristics. A negative electrode for a secondary battery formed by bonding a negative electrode active material to a negative electrode collector with a negative electrode binder, in which the negative electrode binder is a polyimide or a polyamide-imide, and the negative electrode collector is a Cu alloy containing at least one metal (a) selected from the group consisting of Sn, In, Mg and Ag and has a conductivity of 50 IACS % or more.
    Type: Application
    Filed: August 25, 2011
    Publication date: September 19, 2013
    Applicant: NEC ENERGY DEVICES, LTD.
    Inventors: Jiro Iriyama, Daisuke Kawasaki, Ryuichi Kasahara, Tetsuya Kajita, Tatsuji Numata
  • Publication number: 20130119940
    Abstract: There is provided a control system for a lithium secondary battery that can quantitatively sense a deterioration state inherent in a lithium secondary battery using silicon oxide as a negative electrode active material, that is, the nonuniform reaction state of a negative electrode.
    Type: Application
    Filed: July 20, 2011
    Publication date: May 16, 2013
    Applicants: NEC ENERGY DEVICES, LTD., NEC CORPORATION
    Inventors: Jiro Iriyama, Tetsuya Kajita, Daisuke Kawasaki, Ryuichi Kasahara, Tatsuji Numata
  • Publication number: 20130108914
    Abstract: In a lithium ion secondary battery including a positive electrode, a separator, a negative electrode, and a package body, the negative electrode includes simple substance silicon as a negative electrode active material, and a negative electrode binder, and is doped with lithium, and the following formulas (1) and (2) are satisfied: 1.2?Ma/Mc?1.9??(1) 1.0<Ma/(Mc+MLi)<1.6??(2) wherein an amount of lithium inserted into the negative electrode until the negative electrode reaches a potential of 0.02 V with respect to metal lithium is Ma (a number of atoms), an amount of lithium released from the positive electrode until the positive electrode reaches a potential of 4.3 V with respect to metal lithium is Mc (a number of atoms), and an amount of lithium with which the negative electrode is doped is MLi (a number of atoms).
    Type: Application
    Filed: July 29, 2011
    Publication date: May 2, 2013
    Applicants: NEC ENERGY DEVICES, LTD., NEC CORPORATION
    Inventors: Ryuichi Kasahara, Jiro Iriyama, Tetsuya Kajita, Hiroo Takahashi, Tatsuji Numata, Daisuke Kawasaki
  • Publication number: 20130101899
    Abstract: There is provided a nonaqueous electrolyte secondary battery having high capacity in which the reduction in the capacity of the battery due to the irreversible capacity in the first charge and discharge is suppressed using a high capacity positive electrode.
    Type: Application
    Filed: June 6, 2011
    Publication date: April 25, 2013
    Applicant: NEC ENERGY DEVICES, LTD.
    Inventors: Tetsuya Kajita, Hiroo Takahashi, Ryuichi Kasahara, Jiro Iriyama, Tatsuji Numata
  • Publication number: 20120321962
    Abstract: There is provided a polymer secondary battery using silicon and silicon oxide as a negative electrode active material that shows a high capacity retention rate also when a charge and discharge cycle is repeated. A polymer secondary battery including a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a polymer-containing gel electrolyte, wherein the negative electrode includes silicon and silicon oxide as a negative electrode active material, and the polymer-containing gel electrolyte is present in voids formed by fine division of particles of the negative electrode active material.
    Type: Application
    Filed: February 18, 2011
    Publication date: December 20, 2012
    Applicant: NEC ENERGY DEVICES, LTD.
    Inventors: Tetsuya Kajita, Yasutaka Kono, Ryuichi Kasahara, Jiro Iriyama, Tatsuji Numata
  • Publication number: 20120286982
    Abstract: The disclosed device easily and precisely satisfies a requested output range, and is provided with: a ??-modulator (12) which converts a digital input signal to a pulse signal; an input comparison device (11) which compares an input value that corresponds to the digital input signal, and a pre-set threshold value; and a thinned output control unit (14) which, when the result of the comparison by the input comparison device (11) shows that the input value is less than the threshold value, reduces the output value corresponding to the input value in accordance with the size of the difference between the input value and the threshold value, and sets the output value to 0 when the input value is 0.
    Type: Application
    Filed: September 30, 2010
    Publication date: November 15, 2012
    Inventors: Tetsuya Kajita, Seita Nashimoto, Naoki Nagashima, Kouji Okuda
  • Publication number: 20120244420
    Abstract: A secondary battery according to the present exemplary embodiment is a secondary battery including a laminated electrode body provided with at least one pair of positive and negative electrodes and an outer enclosure that accommodates the laminated electrode body, wherein the outer enclosure includes one or more concave portions, inside a border corresponding to an outer edge of an electrode surface of an outermost layer of the laminated electrode body, on a surface facing the electrode surface, and wherein, when a band-shaped outer circumferential region having an area that is a half of an area inside the border is set inside the border, at least one of the concave portions is located inside the outer circumferential region.
    Type: Application
    Filed: March 21, 2012
    Publication date: September 27, 2012
    Applicant: NEC CORPORATION
    Inventors: Shin SERIZAWA, Hiroo TAKAHASHI, Daisuke KAWASAKI, Jiro IRIYAMA, Ryuichi KASAHARA, Emiko FUJII, Tetsuya KAJITA, Tatsuji NUMATA
  • Publication number: 20110274966
    Abstract: An exemplary embodiment of the invention provides a nonaqueous electrolytic solution secondary battery in which capacity deterioration associated with a charge/discharge cycle at a high temperature (45° C. or higher) can be prevented. An exemplary embodiment of the invention is a nonaqueous electrolytic solution secondary battery, comprising an electrode element in which a cathode and an anode are stacked, a nonaqueous electrolytic solution which contains at least one of carbonate solvent, and a gel in an outer packaging body; wherein the anode comprises a silicon oxide represented by SiOx (0<x?2) as an anode active material, and the gel comprises a cross-linked unsaturated carboxylate ester polymer and a carbonate solvent which is the same as at least one of the carbonate solvent contained in the nonaqueous electrolytic solution.
    Type: Application
    Filed: January 19, 2010
    Publication date: November 10, 2011
    Inventors: Jiro Iriyama, Tatsuji Numata, Ryuichi Kasahara, Tetsuya Kajita
  • Publication number: 20110244328
    Abstract: There is provided a negative electrode for a nonaqueous electrolyte secondary battery in which when a battery is formed, the energy density is high, and moreover, the decrease in charge and discharge capacity is small even if charge and discharge are repeated. By using silicon oxide particles having a particle diameter in a particular range as a starting raw material, and heating these particles in the range of 850° C. to 1050° C., Si microcrystals are deposited on the surfaces of the particles. Then, by performing doping of Li, a structure comprising a plurality of protrusions having height and cross-sectional area in a particular range is formed on the surfaces. The average value of the height of the above protrusions is 2% to 19% of the average particle diameter of the above lithium-containing silicon oxide particles.
    Type: Application
    Filed: December 17, 2009
    Publication date: October 6, 2011
    Applicant: NEC ENERGY DEVICES, LTD.
    Inventors: Jiro Iriyama, Ryuichi Kasahara, Tetsuya Kajita, Tatsuji Numata
  • Patent number: 7950292
    Abstract: In a constant current circuit, a constant current is caused to flow through a resistor, thereby causing a constant voltage to occur across the resistor. This constant voltage is then superimposed on an output signal of an operational amplifier that is to be fed back to the drain of a field effect transistor, thereby maintaining the same potential in an AC manner between the output terminal of the operational amplifier and the drain of the field effect transistor. In this way, the gate and drain of the field effect transistor is caused to exhibit the same potential in an AC manner, so that no current will occur through the stray capacitance between the gate and drain of the field effect transistor. As a result, similarly to a case of using a feedback capacitor, the input impedance of the field effect transistor can be raised.
    Type: Grant
    Filed: August 3, 2007
    Date of Patent: May 31, 2011
    Assignee: Yamatake Corp.
    Inventors: Yutaka Harada, Ichiro Mitsutake, Kouji Okuda, Taka Inoue, Tetsuya Kajita
  • Publication number: 20100071476
    Abstract: In a constant current circuit, a constant current is caused to flow through a resistor, thereby causing a constant voltage to occur across the resistor. This constant voltage is then superimposed on an output signal of an operational amplifier that is to be fed back to the drain of a field effect transistor, thereby maintaining the same potential in an AC manner between the output terminal of the operational amplifier and the drain of the field effect transistor. In this way, the gate and drain of the field effect transistor is caused to exhibit the same potential in an AC manner, so that no current will occur through the stray capacitance between the gate and drain of the field effect transistor. As a result, similarly to a case of using a feedback capacitor, the input impedance of the field effect transistor can be raised.
    Type: Application
    Filed: August 3, 2007
    Publication date: March 25, 2010
    Applicant: Yamatake Corporation
    Inventors: Yutaka Harada, Ichiro Mitsutake, Kouji Okuda, Taka Inoue, Tetsuya Kajita
  • Patent number: 7633286
    Abstract: An electric current monitoring device is provided to be used in conjunction with a measuring instrument that converts a physical quantity measured thereby to a signal current and outputs the signal current to a two-wire transmission line. The electric current monitoring device includes an electric current detector inserted in the transmission line for measuring an electric current value of the signal current outputted to the transmission line, and a supply voltage generator inserted in the transmission line for outputting a voltage generated due to the flow of the signal current. The electric current detector is driven by the voltage outputted from the supply voltage generator.
    Type: Grant
    Filed: August 9, 2006
    Date of Patent: December 15, 2009
    Assignee: Yamatake Corporation
    Inventor: Tetsuya Kajita