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Graphite particle, carbon-graphite composite particle and their production process

A graphite particle and manufacturing method technology, applied in the direction of graphite, carbon compounds, chemical instruments and methods, etc., can solve the problems of good diffusion and high-speed charge and discharge characteristics damage, and achieve excellent cycle performance, small resistance, and large charge and discharge energy Effect

Active Publication Date: 2008-11-19
NIPPON POWER GRAPHITE CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] When such auxiliary materials and conductive additives are mixed or added, there is a problem that good diffusion of the electrolyte into the electrode and high-speed charge and discharge characteristics, which are the characteristics of the carbon-graphite composite particles, are impaired due to the addition of the auxiliary materials.

Method used

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  • Graphite particle, carbon-graphite composite particle and their production process
  • Graphite particle, carbon-graphite composite particle and their production process
  • Graphite particle, carbon-graphite composite particle and their production process

Examples

Experimental program
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Effect test

Embodiment 1

[0216] 100 g of copper particles (average particle size: 10 μm) was added to 100 g of flaky graphite (the average length along the plane direction was 28 μm, and the thickness was 5 μm), and mixed for 5 minutes with a stand mixer. After mixing, use a desktop molding machine to form a cylindrical shape of 4 to 5 cm φ under a pressure of 50 MPa. The molded product was pulverized with a mortar to an average particle diameter of 40 μm, and the pulverized product was immersed in a 5% by mass sulfuric acid solution at room temperature for 24 hours to dissolve and remove copper. The mixed solution of copper and graphite was filtered, washed with water, and the graphite was recovered, and dried at 105° C. for 12 hours. 10 g of the obtained graphite particles were kept at 900° C. for 20 minutes under a nitrogen flow in an electric furnace, and 2 g of toluene was added to perform CVD treatment. The treated particles were recovered, and the measurements of tamping density, average parti...

Embodiment 2

[0231] 10 g of silica particles (average particle size: 6 μm) were added to 100 g of spherical graphite (average particle size: 28 μm), and mixed for 5 minutes with a stand mixer. After mixing, use a desktop molding machine to form a cylindrical shape of 4 to 5 cm φ under a pressure of 50 MPa. The molded product was pulverized with a mortar, and the pulverized product was immersed in a 46% by mass hydrofluoric acid solution at room temperature for 24 hours to dissolve and remove silica. The mixed solution of silicon dioxide and graphite was filtered, washed with water, and the recovered graphite was kept dry at 105° C. for 12 hours. 10 g of the recovered particles were kept at 900° C. for 20 minutes under a nitrogen flow in an electric furnace, and 2 g of toluene was added to perform CVD treatment. The treated particles were recovered, and the measurements of tamping density, average particle diameter, SEM observation, carbon coating amount, recess depth, electrode density, e...

Embodiment 3

[0234] 20 g of polyethylene particles (average particle size: 5 μm) were added to 100 g of spherical graphite (average particle size: 26 μm), and mixed for 5 minutes with a stand mixer. After mixing, use a desktop molding machine to form a cylindrical shape of 4 to 5 cm φ under a pressure of 50 MPa. The molded product was pulverized in a mortar, and the pulverized product was fired in an electric furnace at 900° C. for 1 hour under a nitrogen flow to remove polyethylene. While maintaining 10 g of the recovered particles at 900° C. for 20 minutes under a nitrogen flow in an electric furnace, 2 g of toluene was added to perform CVD treatment. The treated particles were recovered, and the measurements of tamping density, average particle size, SEM observation, carbon coating amount, recess depth, electrode density, electrode evaluation, etc. were performed. The pore diameter of the concave part is 5.7 μm, and the depth of the concave part is 2.1 μm. The SEM photo of the obtained...

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Abstract

Disclosed are a graphite particle and a carbon-graphite composite particle suitable for negative electrodes for lithium ion secondary batteries, and processes for producing those particles. Specifically disclosed is a graphite particle having an average particle diameter of 5-50 [mu]m, wherein one or more recesses having a depth of 0.1-10 [mu]m are formed in the surface. The graphite particle is produced by a process comprising a mixing step for mixing raw material graphite particles and recess-forming particles; a press molding step for obtaining a molded article by press-molding the mixture composed of the raw material graphite particles and the recess-forming particles; a pulverization step for pulverizing the molded article; and a separation step for separating and removing the recess-forming particles from the pulverized molded article. A carbon-graphite composite particle is produced by performing a thermal CVD process for coating the surface of the graphite particle with a carbon layer.

Description

technical field [0001] The present invention relates to graphite particles, carbon-graphite composite particles, and methods for producing them, which are suitable for use as negative electrode materials for secondary lithium ion batteries having high capacity, high efficiency, high load characteristics, and excellent charge-discharge cycle characteristics. Background technique [0002] With progress in size and weight reduction and diversification of functions of electronic equipment centered on mobile phones, higher capacity of secondary lithium ion batteries is required. [0003] For the background of the existing high capacity, it is often accompanied by the improvement of the structure and material of the secondary lithium ion battery or the high capacity of the positive electrode material. It can be said that the effect of increasing the volume specific gravity (electrode density) of the negative electrode formed using graphite particles makes the greatest contribution...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B31/04H01M4/58H01M4/02H01M10/40H01M4/583H01M10/0525H01M10/36
CPCH01M4/583C04B35/62839C04B2235/5292Y02E60/122H01M4/366Y10T29/49108C04B35/62884C04B2235/425C04B2235/5409C04B2235/5436H01M10/0525C04B2235/5296C04B2235/528C01B31/04Y10T428/2982C01B32/20C01B32/205Y02E60/10H01M2004/027C01P2004/61C01P2006/11C01P2006/12
Inventor 梅野达夫岩尾孝士
Owner NIPPON POWER GRAPHITE CO LTD
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