Patents by Inventor Kenta Nakai

Kenta Nakai 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: 11515537
    Abstract: An energy storage device includes a negative electrode having a negative active material layer containing amorphous carbon as an active material, a curve attained by determining a rate of change (dQ/dV) in a potential (V) of the amorphous carbon in a discharge capacity (Q) of the amorphous carbon per unit quantity based on a result attained by measuring the potential (V) with respect to the discharge capacity (Q) and representing the rate of change (dQ/dV) with respect to the potential (V) has one or more peaks in a range in which the potential of the amorphous carbon is 0.8 V or more and 1.5 V or less, and a potential of the negative electrode at time of full charge is 0.25 V or more with respect to a lithium potential.
    Type: Grant
    Filed: November 21, 2018
    Date of Patent: November 29, 2022
    Assignee: GS YUASA INTERNATIONAL LTD.
    Inventors: Tomonori Kako, Akihiko Miyazaki, Masashi Takano, Kenta Nakai, Ukyo Harinaga
  • Patent number: 11258065
    Abstract: An energy storage device includes: a positive electrode plate containing a positive composite layer including a positive active material capable of occluding and releasing a lithium ion; and a negative electrode plate containing a negative composite layer including a negative active material capable of occluding and releasing a lithium ion. A peak pore diameter Rp of the positive composite layer in a pore distribution measured by a mercury penetration method is 0.5 ?m or less, and a peak pore diameter Rn of the negative composite layer in a pore distribution measured by a mercury penetration method is 0.5 ?m or less. A ratio Rp/Rn of the peak pore diameter of the positive composite layer to the peak pore diameter of the negative composite layer is 0.60 or more and 1.70 or less.
    Type: Grant
    Filed: January 13, 2017
    Date of Patent: February 22, 2022
    Assignee: GS Yuasa International Ltd.
    Inventors: Shota Ito, Kenta Nakai, Akihiko Miyazaki, Tomonori Kako, Sumio Mori
  • Publication number: 20210399347
    Abstract: Provided is a method for manufacturing an energy storage device including an electrode that has an active material layer, an electrolyte solution, and a case. According to the present embodiment, the method including injecting an electrolyte solution in a predetermined amount into a case is characterized in that the predetermined amount is an amount such that, an alkali metal or an alkaline earth metal at least partially comes into contact with a free electrolyte solution that is the electrolyte solution excluding the electrolyte solution soaking into the electrode assembly in the case, with the case housing therein: the alkali metal or the alkaline earth metal of an ion supply member that has the alkali metal or the alkaline earth metal disposed on a conductive member other than the active material layer; and an electrode assembly including the stacked electrode that has electrical conduction to the conducive member of the ion supply member.
    Type: Application
    Filed: September 26, 2019
    Publication date: December 23, 2021
    Inventors: Taro YAMAFUKU, Kenta NAKAI, Jun OYAMA
  • Publication number: 20200388845
    Abstract: An energy storage device includes a negative electrode having a negative active material layer containing amorphous carbon as an active material, a curve attained by determining a rate of change (dQ/dV) in a potential (V) of the amorphous carbon in a discharge capacity (Q) of the amorphous carbon per unit quantity based on a result attained by measuring the potential (V) with respect to the discharge capacity (Q) and representing the rate of change (dQ/dV) with respect to the potential (V) has one or more peaks in a range in which the potential of the amorphous carbon is 0.8 V or more and 1.5 V or less, and a potential of the negative electrode at time of full charge is 0.25 V or more with respect to a lithium potential.
    Type: Application
    Filed: November 21, 2018
    Publication date: December 10, 2020
    Inventors: Tomonori KAKO, Akihiko MIYAZAKI, Masashi TAKANO, Kenta NAKAI, Ukyo HARINAGA
  • Patent number: 10833349
    Abstract: An energy storage device includes: an electrode assembly which includes: an approximately rectangular positive electrode; an approximately rectangular negative electrode which is stacked alternately with the positive electrode; and a strip-like elongated separator having a base material layer and an inorganic layer which is made to overlap with the first base material layer, wherein the elongated separator is arranged between the positive electrode and the negative electrode, and the base material layer of the elongated separator faces the negative electrode in an opposed manner between the positive electrode and the negative electrode.
    Type: Grant
    Filed: March 14, 2016
    Date of Patent: November 10, 2020
    Assignee: GS YUASA INTERNATIONAL LTD.
    Inventors: Kenta Nakai, Tomonori Kako, Akihiko Miyazaki, Sumio Mori
  • Publication number: 20200144615
    Abstract: There is provided an energy storage device which can have a relatively high initial power and whereby it becomes possible to prevent the occurrence of electrodeposition of lithium even when a charge-discharge procedure is performed repeatedly at a high rate.
    Type: Application
    Filed: November 6, 2018
    Publication date: May 7, 2020
    Inventors: Tomonori KAKO, Akihiko MIYAZAKI, Kenta NAKAI, Shota ITO
  • Publication number: 20190027753
    Abstract: An energy storage device of which endurance capacity retention ratio is improved is provided. An energy storage device 10 includes: a positive electrode plate 12 containing a positive composite layer including a positive active material capable of occluding and releasing a lithium ion; and a negative electrode plate 13 containing a negative composite layer including a negative active material capable of occluding and releasing a lithium ion. A peak pore diameter Rp of the positive composite layer in a pore distribution measured by a mercury penetration method is 0.5 ?m or less, and a peak pore diameter Rn of the negative composite layer in a pore distribution measured by a mercury penetration method is 0.5 ?m or less. A ratio Rp/Rn of the peak pore diameter of the positive composite layer to the peak pore diameter of the negative composite layer is 0.60 or more and 1.70 or less.
    Type: Application
    Filed: January 13, 2017
    Publication date: January 24, 2019
    Inventors: Shota ITO, Kenta NAKAI, Akihiko MIYAZAKI, Tomonori KAKO, Sumio MORI
  • Patent number: 9905822
    Abstract: An energy storage unit having plural energy storage devices, each of which includes a container housing an electrode assembly and positive and negative electrode terminals electrically connected to the electrode assembly and extending from the container in the same direction, includes: a bus bar electrically connecting a first terminal, which is one of the positive electrode terminal and the negative electrode terminal of a first energy storage device included in the plural energy storage devices, and a second terminal, which is one of the positive electrode terminal and the negative electrode terminal of a second energy storage device included in the plural energy storage devices and opposite in polarity to the first terminal; a packing member interposed between the first terminal and the container of the first energy storage device; and an insulating member interposed between the bus bar and the container of the first energy storage device.
    Type: Grant
    Filed: December 2, 2013
    Date of Patent: February 27, 2018
    Assignee: GS YUASA INTERNATIONAL LTD.
    Inventors: Sumio Mori, Tomonori Kako, Akihiko Miyazaki, Kenta Nakai
  • Patent number: 9865855
    Abstract: An energy storage device includes a positive electrode, a negative electrode, and an insulating layer arranged between these electrodes to electrically insulate these electrodes. The negative electrode includes a composite layer containing active material particles. The composite layer of the negative electrode, and the positive electrode are arranged to face each other across the insulating layer. The insulating layer contains electrically insulating particles, and is made porous by a gap between these particles. The composite layer of the negative electrode is made porous by a gap between the active material particles, and “?0.8?Log B?Log A?1.0” is satisfied in which in a pore distribution of the composite layer, a pore peak diameter is represented by A (?m), and in a pore distribution of the insulating layer, a peak diameter is represented by B (?m).
    Type: Grant
    Filed: February 24, 2016
    Date of Patent: January 9, 2018
    Assignee: GS Yuasa International Ltd.
    Inventors: Akihiko Miyazaki, Kenta Nakai, Tomonori Kako, Sumio Mori
  • Patent number: 9865878
    Abstract: An energy storage device includes a positive electrode, a negative electrode, and a nonaqueous electrolyte solution. The negative electrode includes an active material layer, and the active material layer has pores having a pore size of 0.1 ?m or more and 1.0 ?m or less, and a total volume of the pores is 0.26 cm3/g or more and 0.46 cm3/g or less.
    Type: Grant
    Filed: March 17, 2016
    Date of Patent: January 9, 2018
    Assignee: GS Yuasa International Ltd.
    Inventors: Kenta Nakai, Akihiko Miyazaki, Tomonori Kako, Sumio Mori
  • Patent number: 9806376
    Abstract: Provided is an energy storage device including an electrolyte solution including a compound represented by the general formula (1), a compound represented by the general formula (2), and a compound represented by the general formula (3):
    Type: Grant
    Filed: August 24, 2015
    Date of Patent: October 31, 2017
    Assignee: GS Yuasa International Ltd.
    Inventors: Tomonori Kako, Sumio Mori, Akihiko Miyazaki, Kenta Nakai
  • Patent number: 9761876
    Abstract: An energy storage device including a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte, wherein the negative electrode includes a negative electrode active material layer containing a non-graphitizable carbon as a negative electrode active material, and the negative electrode active material has a negative electrode active material weight per unit volume of the negative electrode active material layer of 0.92 g/cc or more and 1.13 g/cc or less and a particle size D90 of 4.3 ?m or more and 11.5 ?m or less, the particle size D90 being a particle size in particle size distribution in which a cumulative volume is 90%.
    Type: Grant
    Filed: December 2, 2013
    Date of Patent: September 12, 2017
    Assignee: GS YUASA INTERNATIONAL LTD.
    Inventors: Sumio Mori, Kenta Nakai, Akihiko Miyazaki, Tomonori Kako
  • Patent number: 9705119
    Abstract: An energy storage device comprises a positive electrode, a negative electrode, a separator arranged between the positive electrode and the negative electrode, and a nonaqueous electrolyte. The negative electrode has a negative substrate layer, and a negative composite layer arranged on the surface of the negative substrate layer. The separator has a separator substrate layer. The negative composite layer contains a non-graphitizable carbon having a particle diameter D50 of 2.0 ?m or more and 6.0 ?m or less. A corrected negative electrode density, which is defined as a value obtained by dividing, by a thickness of the separator substrate layer, a value obtained by multiplying a density of the negative composite layer by a thickness of the negative composite layer, is 1.2 (g/cm3) or more and 5.1 (g/cm3) or less.
    Type: Grant
    Filed: May 22, 2015
    Date of Patent: July 11, 2017
    Assignee: GS Yuasa International Ltd.
    Inventors: Akihiko Miyazaki, Sumio Mori, Tomonori Kako, Kenta Nakai
  • Patent number: 9653714
    Abstract: An electric storage device is provided with an electrode assembly including a positive electrode plate and a negative electrode plate; a case for housing the electrode assembly; a positive-electrode external terminal arranged on an outer surface of the case and electrically connected to the positive electrode plate; a negative-electrode external terminal arranged on an outer surface of the case and electrically connected to the negative electrode plate; and a gas exhaust valve formed in a region of the case on the opposite side of a region where the positive-electrode external terminal and the negative-electrode external terminal are arranged.
    Type: Grant
    Filed: March 27, 2014
    Date of Patent: May 16, 2017
    Assignee: GS YUASA INTERNATIONAL LTD.
    Inventors: Sumio Mori, Tomonori Kako, Akihiko Miyazaki, Kenta Nakai
  • Patent number: 9455091
    Abstract: An electric storage device having a positive electrode, a negative electrode, a separator located between the positive electrode and the negative electrode, and a nonaqueous electrolyte. The positive electrode has a positive substrate layer, a positive composite layer containing a positive active material, and an undercoat layer located between the positive substrate layer and the positive composite layer. A density of the positive composite layer is 2.1 g/cm3 or more and 2.7 g/cm3 or less. The positive electrode has the rate of increase in sheet resistance after a solvent immersion test of 30% or less. The undercoat layer contains a binder selected from the group consisting of chitosan derivatives, cellulose derivatives and acrylic acid derivatives.
    Type: Grant
    Filed: September 26, 2014
    Date of Patent: September 27, 2016
    Assignee: GS Yuasa International Ltd.
    Inventors: Akihiko Miyazaki, Sumio Mori, Tomonori Kako, Kenta Nakai
  • Publication number: 20160276667
    Abstract: An energy storage device includes a positive electrode, a negative electrode, and a nonaqueous electrolyte solution. The negative electrode includes an active material layer, and the active material layer has pores having a pore size of 0.1 ?m or more and 1.0 ?m or less, and a total volume of the pores is 0.26 cm3/g or more and 0.46 cm3/g or less.
    Type: Application
    Filed: March 17, 2016
    Publication date: September 22, 2016
    Inventors: Kenta NAKAI, Akihiko MIYAZAKI, Tomonori KAKO, Sumio MORI
  • Publication number: 20160276702
    Abstract: An energy storage device includes: an electrode assembly which includes: an approximately rectangular positive electrode; an approximately rectangular negative electrode which is stacked alternately with the positive electrode; and a strip-like elongated separator having a base material layer and an inorganic layer which is made to overlap with the first base material layer, wherein the elongated separator is arranged between the positive electrode and the negative electrode, and the base material layer of the elongated separator faces the negative electrode in an opposed manner between the positive electrode and the negative electrode.
    Type: Application
    Filed: March 14, 2016
    Publication date: September 22, 2016
    Inventors: Kenta NAKAI, Tomonori KAKO, Akihiko MIYAZAKI, Sumio MORI
  • Publication number: 20160248065
    Abstract: An energy storage device includes a positive electrode, a negative electrode, and an insulating layer arranged between these electrodes to electrically insulate these electrodes. The negative electrode includes a composite layer containing active material particles. The composite layer of the negative electrode, and the positive electrode are arranged to face each other across the insulating layer. The insulating layer contains electrically insulating particles, and is made porous by a gap between these particles. The composite layer of the negative electrode is made porous by a gap between the active material particles, and “?0.8?Log B?Log A?1.0” is satisfied in which in a pore distribution of the composite layer, a pore peak diameter is represented by A (?m), and in a pore distribution of the insulating layer, a peak diameter is represented by B (?m).
    Type: Application
    Filed: February 24, 2016
    Publication date: August 25, 2016
    Inventors: Akihiko MIYAZAKI, Kenta NAKAI, Tomonori KAKO, Sumio MORI
  • Patent number: 9397364
    Abstract: An electric storage device includes: an electrode assembly in which electrodes are wound such that paired curved portions and a straight portion connecting the paired curved portions are formed; a case which houses the electrode assembly, the case comprising a convex part protruding toward the straight portion of the electrode assembly to support the straight portion; and a support portion which supports the curved portion toward an inside of the electrode assembly.
    Type: Grant
    Filed: October 1, 2014
    Date of Patent: July 19, 2016
    Assignee: GS YUASA INTERNATIONAL LTD.
    Inventors: Akihiko Miyazaki, Sumio Mori, Tomonori Kako, Kenta Nakai
  • Patent number: 9350049
    Abstract: The electric storage device includes: an electrode assembly; and an electrolytic solution at least part of which is impregnated into the electrode assembly, wherein the electrode assembly includes, as electrode assembly forming members, at least a positive electrode and a negative electrode that face each other, and contains lithium carbonate, the electrolytic solution contains at least lithium hexafluorophosphate, at least one of the positive electrode and the negative electrode includes an active material layer containing a metal compound, the active material layer includes a peripheral area and an inner area inside the peripheral area, the electrode assembly includes a high-content part the ratio of lithium carbonate content of which is higher than that of the inner area.
    Type: Grant
    Filed: November 28, 2014
    Date of Patent: May 24, 2016
    Assignee: GS YUASA INTERNATIONAL LTD.
    Inventors: Kenta Nakai, Takeshi Sasaki