Patents by Inventor Wan-uk Choi

Wan-uk Choi 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: 6887622
    Abstract: Disclosed is carbonaceous active material for a lithium-ion secondary battery. Conducting a differential thermal analysis on the carbonaceous active material results in the displaying of at least two exothermic peaks overlapping to form shoulders.
    Type: Grant
    Filed: July 29, 1999
    Date of Patent: May 3, 2005
    Assignee: Samsung Display Devices Co., Ltd.
    Inventors: Jae-yul Ryu, Sang-young Yoon, Kyou-yoon Sheem, Sang-jin Kim, Wan-uk Choi
  • Patent number: 6730135
    Abstract: A negative active material for a lithium secondary battery includes a graphite-like carbon material having an intensity ratio I(110)/I(002) of an X-ray diffraction peak intensity I(002) at a (002) plane to an X-ray diffraction peak intensity I(110) at a (110) plane of less than 0.2. The negative active material prepared by dissolving a coar tar pitch or a petroleum pitch in an organic solvent to remove insoluble components therefrom, heat-treating the pitch at a temperature in the range of 400 to 450° C. for 4 hours or more under an inert atmosphere to thereby produce at least 50 weight percent of mesophase particles based on the pitch, coking the pitch including mesophase particles, carbonizing the coked pitch, pulverizing the carbonized pitch; and graphitizing the pulverized pitch.
    Type: Grant
    Filed: March 10, 1999
    Date of Patent: May 4, 2004
    Assignee: Samsung Display Devices Co., Ltd.
    Inventors: Wan-uk Choi, Kyou-yoon Sheem, Sang-young Yoon
  • Publication number: 20030175591
    Abstract: A negative electrode active material for a lithium-based secondary battery includes a graphite-like carbon material having an intensity ratio I(110)/I(002) of an X-ray diffraction peak intensity I(002) at a (002) plane to an X-ray diffraction peak intensity I(110) at a (110) plane of less than 0.2.
    Type: Application
    Filed: March 17, 2003
    Publication date: September 18, 2003
    Applicant: Samsung Display Devices Co. Ltd.
    Inventors: Wan-Uk Choi, Jae-Yul Ryu, Sang-Young Yoon
  • Patent number: 6521380
    Abstract: A rechargeable lithium battery includes a negative electrode with a graphite-based active material with boron as a donor and a positive electrode with a transition metal oxide-based active material. A separator is interposed between the negative and positive electrodes. The positive and negative electrodes and the separator are all saturated with an electrolyte. The electrolyte contains cyclic carbonate and chain carbonate at a ratio of 51:49 by volume percent.
    Type: Grant
    Filed: October 29, 1999
    Date of Patent: February 18, 2003
    Assignee: Samsung Display Devices Co., Ltd.
    Inventors: Jae-Yul Ryu, Sang-Young Yoon, Wan-Uk Choi, Kyoo-Yoon Shim, Sang-Jim Kim
  • Patent number: 6482547
    Abstract: A negative active material for a lithium secondary battery which is capable of improving packing density and has good high-rate charge/discharge and cycle life characteristics is provided. The negative active material includes a crystalline carbon core and an amorphous carbon shell. Alternatively, the negative active material includes secondary particles prepared by gathering at least one crystalline carbon primary particle. A surface of the secondary particles is coated with an amorphous carbon and the secondary particles has a substantially spherical form. The negative active material has two exothermic peak of the differential thermal analysis at 1000° C. or less. A lithium secondary battery using the negative active material can use propylene carbonate for an organic solvent of an electrolyte.
    Type: Grant
    Filed: May 21, 1999
    Date of Patent: November 19, 2002
    Assignee: Samsung Display Devices Co., Ltd.
    Inventors: Sang-young Yoon, Jeong-ju Cho, Jae-yul Ryu, Kyou-yoon Sheem, Wan-uk Choi, Sang-jin Kim
  • Patent number: 6479426
    Abstract: Disclosed is a negative active material for a lithium secondary battery. The negative active material includes graphitized coke having a graphitization catalyst element and non-flat artificial graphite. The negative active material for a lithium secondary battery has good electrolyte-immersibility due to the gap between the graphite particles from graphitized coke having a graphitization catalyst element, and non-flat artificial graphite. Therefore, the present invention may provide a lithium secondary battery which has good high-rate capacity and initial efficiency.
    Type: Grant
    Filed: May 9, 2001
    Date of Patent: November 12, 2002
    Assignee: Samsung SDI Co., Ltd.
    Inventors: Jae-Yul Ryu, Sang-Young Yoon, Wan-Uk Choi, Kyou-Yoon Sheem, Sang-Jin Kim
  • Publication number: 20020127172
    Abstract: A negative electrode active material for a lithium-based secondary battery includes a graphite-like carbon material having an intensity ratio I(110)/I(002) of an X-ray diffraction peak intensity I(002) at a (002) plane to an X-ray diffraction peak intensity I(110) at a (110) plane of less than 0.2.
    Type: Application
    Filed: February 23, 2001
    Publication date: September 12, 2002
    Applicant: Samsung Display Devices Co., Ltd.
    Inventors: Wan-Uk Choi, Jae-Yul Ryu, Sang-Young Yoon
  • Patent number: 6399250
    Abstract: A negative active material for a rechargeable lithium battery having the high content of boron is provided. A mixed solution including a pitch, a boron compound and a solvent is prepared and the solvent is removed from the mixed solution to prepare mesophase pitch. The mesophase pitch is then carbonized and the carbonized material is graphitized to obtain the negative active material.
    Type: Grant
    Filed: November 23, 1999
    Date of Patent: June 4, 2002
    Assignee: Samsung Display Devices Co., Ltd.
    Inventors: Kyou-Yoon Sheem, Sang-Young Yoon, Jeong-Ju Cho, Wan-Uk Choi
  • Patent number: 6395427
    Abstract: A negative active material for a rechargeable lithium battery which exhibits good discharge capacity and charge and discharge efficiency, and enables the use of all types of electrolytes. The active material includes a crystalline carbon core and a semi-crystalline carbon shell. The semi-crystalline carbon shell includes at least one element or a compound of at least two different types of elements, and has a turbostratic or half onion-sheath. The compound includes only element. The element serves graphitization catalyst and causes a change in a structure of surrounding carbon. In particular, the negative active material includes metal boride.
    Type: Grant
    Filed: August 29, 2000
    Date of Patent: May 28, 2002
    Assignee: Samsung SDI Co., Ltd.
    Inventors: Kyou-Yoon Sheem, Sang-Young Yoon, Wan-Uk Choi, Jae-Yul Ryu, Sang-Jin Kim
  • Patent number: 6391495
    Abstract: A negative active material for a lithium secondary battery includes a crystalline graphite core and a carbon shell. The carbon shell includes at least one material selected from a transition metal, an alkali metal, an alkaline earth metal, an element of Group 3B of the Periodic table, an element of Group 4B, an element of Group 5B or a mixture thereof. The carbon shell is a turbostratic carbon layer, or am amorphous or crystalline carbon layer having different physical properties from the core. The negative active material can be used in a lithium secondary battery such that the battery has a large discharge capacity and a high charge/discharge efficiency.
    Type: Grant
    Filed: November 23, 1999
    Date of Patent: May 21, 2002
    Assignee: Samsung Display Devices Co., Ltd.
    Inventors: Wan-Uk Choi, Kyou-Yoon Sheem, Sang-Young Yoon, Jae-Yul Ryu
  • Publication number: 20020039685
    Abstract: A negative active material for a lithium secondary battery includes a graphite-like carbon material having an intensity ratio I(110)/I(002) of an X-ray diffraction peak intensity I(002) at a (002) plane to an X-ray diffraction peak intensity I(110) at a (110) plane of less than 0.2. The negative active material prepared by dissolving a coar tar pitch or a petroleum pitch in an organic solvent to remove insoluble components therefrom, heat-treating the pitch at a temperature in the range of 400 to 450° C. for 4 hours or more under an inert atmosphere to thereby produce at least 50 weight percent of mesophase particles based on the pitch, coking the pitch including mesophase particles, carbonizing the coked pitch, pulverizing the carbonized pitch; and graphitizing the pulverized pitch.
    Type: Application
    Filed: March 10, 1999
    Publication date: April 4, 2002
    Inventors: WAN-UK CHOI, KYOU-YOON SHEEM, SANG-YOUNG YOON
  • Patent number: 6355377
    Abstract: A negative active material for a rechargeable lithium battery which exhibits good high-rate charge characteristics and cycle life characteristics. The active material includes a crystalline carbon core and a semi-crystalline carbon shell. The semi-crystalline carbon shell includes at least one element or a compound of at least two different types of elements and carbides thereof, and has a turbostratic or half onion-sheath. The compound includes only element. The element serves a graphitization catalyst and causes a change in a structure of surrounding carbon. In particular, the negative active material includes metal boride and metal carbide.
    Type: Grant
    Filed: September 22, 2000
    Date of Patent: March 12, 2002
    Assignee: Samsung SDI Co., Ltd.
    Inventors: Kyou-Yoon Sheem, Sang-Young Yoon, Wan-Uk Choi, Jae-Yul Ryu, Sang-Jin Kim
  • Publication number: 20020012845
    Abstract: The present invention relates to a negative active material for a rechargeable lithium battery and a method of preparing the same, said negative active material comprising crystalline carbon having a dispersed element serving as graphitization catalyst therein. Said negative active material for a rechargeable lithium battery is prepared by the steps of adding an element serving as a graphitization catalyst to a carbon precursor; coking the mixture by heat-treating at 300 to 600° C. carbonizing the cokes; and graphitizing the carbide at 2800 to 3000° C.
    Type: Application
    Filed: June 11, 2001
    Publication date: January 31, 2002
    Inventors: Wan-Uk Choi, Kyou-Yoon Sheem, Sang-Jin Kim, Jae-Yul Ryu, Sang-Young Yoon
  • Publication number: 20020006551
    Abstract: Disclosed is carbonaceous active material for a lithium-ion secondary battery. Conducting a differential thermal analysis on the carbonaceous active material results in the displaying of at least two exothermic peaks overlapping to form shoulders.
    Type: Application
    Filed: July 29, 1999
    Publication date: January 17, 2002
    Inventors: JAE-YUL RYU, SANG-YOUNG YOON, KYOU-YOON SHEEM, SANG-JIN KIM, WAN-UK CHOI
  • Publication number: 20010053743
    Abstract: Disclosed is a negative active material for a lithium secondary battery. The negative active material includes graphitized coke having a graphitization catalyst element and non-flat artificial graphite. The negative active material for a lithium secondary battery has good electrolyte-immersibility due to the gap between the graphite particles from graphitized coke having a graphitization catalyst element, and non-flat artificial graphite. Therefore, the present invention may provide a lithium secondary battery which has good high-rate capacity and initial efficiency.
    Type: Application
    Filed: May 9, 2001
    Publication date: December 20, 2001
    Inventors: Jae-Yul Ryu, Sang-Young Yoon, Wan-Uk Choi, Kyou-Yoon Sheem, Sang-Jin Kim
  • Patent number: 6245460
    Abstract: A negative electrode active material for a lithium-based secondary battery includes a graphite-like carbon material having an intensity ratio I(110)/I(002) of an X-ray diffraction peak intensity I(002) at a (002) plane to an X-ray diffraction peak intensity I(110) at a (110) plane of less than 0.2.
    Type: Grant
    Filed: August 28, 1998
    Date of Patent: June 12, 2001
    Assignee: Samsung Display Devices Co., Ltd.
    Inventors: Wan-uk Choi, Jae-Yul Ryu, Sang-Young Yoon