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Graphite granules and their method of fabrication

a graphite granule and graphite technology, applied in the field of graphite granules, can solve the problems of deterioration of cycle and high current characteristics, increasing demand for power sources of portable electronic products, and increasing complexity of electronic products, etc., to achieve excellent high current characteristics, excellent electrochemical properties, and high reversible specific capacity

Inactive Publication Date: 2004-11-18
BYD AMERICA CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0010] An object of this invention is to provide improved graphite granules that have excellent electrochemical properties; such that when for negative electrodes in batteries such as lithium ion rechargeable batteries, it produces batteries with high current characteristics, higher reversible specific capacity, and longer cycle life.
[0011] Another object of this invention is to provide a method for fabricating said improved graphite granules with technology that is simple, of low cost and easy for mass production.
[0013] The advantages of said improved graphite granules of the embodiments of this invention are: said improved graphite granules have excellent electrochemical properties, which, when used as the active material for the negative electrode in batteries (e.g. lithium ion batteries), produces batteries with excellent high current characteristics, higher reversible specific capacity, and longer cycle life that can satisfy the demands of practical application.
[0014] The advantages of said method for fabrication of said improved graphite granules of this invention is that the technology for the fabrication is simple and inexpensive, thus making it easy to use for commercial production.

Problems solved by technology

Since electronic products, especially portable electronic products, are gradually becoming more complex and miniaturized, the demand for power sources of these products is also increasing.
However, in the process of attaching and detaching lithium, the structure of the crystallite in the natural graphite can easily be loosened or even destroyed resulting in the deterioration of the cycle and high current characteristics.
However, this method for fabricating graphite is actually is a type of man-made graphite treatment process that needs temperatures as high as 2800.degree. C. for the graphitization treatment resulting in high cost and difficult technology, thus making it difficult to implement for industrial production as well.

Method used

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  • Graphite granules and their method of fabrication
  • Graphite granules and their method of fabrication
  • Graphite granules and their method of fabrication

Examples

Experimental program
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embodiment 1

[0042] The following steps comprise the method for the fabrication of Embodiment 1:

[0043] Dissolve 8 g of petroleum coke in carbon tetrachloride to formulate 200 ml of 4% surface modifying solution;

[0044] Immerse 100 g of unimproved dried natural graphite granules and immerse in the surface modifying agent organic solution;

[0045] Stir at 300 rpm speed for 1 hour to form a thin layer of surface modifying membrane on the surface of the unimproved graphite granules;

[0046] Filter the coated graphite granules that are obtained; Heat to dry and sift with 300 mesh;

[0047] Put sifted coated graphite granules into sealed tubular high temperature furnace. Pass highly pure nitrogen at 10 liters / min of flow volume and increase the temperature at 15.degree. C. / min to 400.degree. C. and hold the temperature for 1 hour; and

[0048] Increase the temperature at 10.degree. C. / min to 1000.degree. C. and hold the temperature for 3 hours. Lower the temperature naturally to room temperature to obtain the im...

embodiment 2

[0050] In this embodiment, the surface modifying solution is a 5% coal pitch in tetrahydrofuran. Other than this, all other steps and specifications are the same as Embodiment 1. The improved graphite granule obtained from this embodiment has fundamentally the same average granule diameter D.sub.50 and crystallite interlayer spacing, d.sub.002. as the improved graphite granules of Embodiment 1.

embodiment 3

[0051] In this embodiment, the surface modifying solution is a 3% petroleum pitch and chloroform solution. Other than this all other steps and specifications are the same as Embodiment 1. The improved graphite granules obtained from this embodiment has fundamentally the same average granule diameter D.sub.50 and crystallite interlayer spacing, d.sub.002, as the improved graphite granules of Embodiment 1.

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Abstract

This invention discloses a type of improved graphite granules and the method for their fabrication. Each improved graphite granule includes an unimproved graphite granule whose electrochemical properties need to be improved, and a membrane of amorphous carbon enveloping said unimproved graphite granule forming the membrane. The thickness of said amorphous carbon membrane is between 0.05 mum and 1 mum. To fabricate said improved graphite granules, said unimproved graphite granules are immersed in a polymer surface modifying solution, stirred, separated, sifted, and then solidified and carbonized. Said improved graphite granules, when used as the negative electrode of a lithium ion rechargeable battery produces a battery with excellent high current characteristics, high reversible specific capacity, long cycle life, and can satisfy the performance demands on rechargeable batteries. The technology for the fabrication of this improved graphite granules is simple. Its cost of production is low. Therefore, it is easy to implement this technology for mass production.

Description

CROSS REFERENCE[0001] This application claims priority from the following Chinese patent applications: "A Type of Improved Graphite and Its Method of Fabrication" filed on Aug. 16, 2003, having a Chinese Application No. 03140199.6; "The Fabrication Method of A Type of Improved Graphite" filed on May 16, 2003, having a Chinese Application No. 03126631.2; "Method for the Fabrication of a Carbon Containing Material for the Negative Electrode of A Type Lithium Ion Rechargeable Battery" filed on Jun. 20, 2003, having a Chinese Application No. 03 1 26961.3; and "A Type of Lithium Ion Rechargeable Battery" filed on Jul. 22, 2003, having a Chinese Application No. of 03132939.X. All of the above applications are incorporated herein by reference.[0002] This invention relates to improved graphite granules and their method of fabrication. In particular, it relates to improved graphite granules used as the active material in the negative electrode of a battery.[0003] With the rapid development o...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C01B31/04H01M4/04H01M4/36H01M4/58H01M4/587
CPCC01B31/04C01P2004/61H01M4/0471Y10T428/30H01M4/587Y10T428/2982Y10T29/49115H01M4/366C01B32/21Y02E60/10
Inventor ZOU, CAISONGWANG, CHUANFUDONG, JUNQING
Owner BYD AMERICA CORP
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