Process for producing negative electrode material for lithium ion secondary battery

A secondary battery and negative electrode material technology, applied in the direction of secondary batteries, battery electrodes, chemical instruments and methods, etc., to achieve the effect of improving grinding ability and suppressing the increase of irreversible capacity

Active Publication Date: 2009-01-21
TOKAI CARBON CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] The object of the present invention is to solve the above-mentioned problems related to negative electrode materials for lithium-ion secondary batteries

Method used

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  • Process for producing negative electrode material for lithium ion secondary battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] 500 g of natural graphite with an average particle diameter of 20.2 μm and 175 g of coal tar pitch with a quinoline insoluble content of 0.2% and a fixed carbon content of 52% were put into the Werner mixer. The above components were stirred at 130°C for 20 minutes. After adding 25g of molten engine oil as a molten organic substance, the components were melted and kneaded for 10 minutes. The engine oil volatilized 70% under heating at 400°C in air and had a residual carbon content of 0.6% under heating at 800°C in an inert atmosphere.

[0039] After the obtained mixture was cooled, the mixture was placed in a graphite crucible, and the mixture was calcined at 1000° C. in a nitrogen atmosphere to be carbonized. The resulting product was placed in a graphitization furnace and graphitized at 2500°C. The graphitized material was ground using a cyclone sample mill "CSM-F1" (manufactured by Fujiwara Scientific Co., Ltd.), and sieved using a sieve with an aperture of 44 μm to...

Embodiment 2

[0041] The components were melted and kneaded in the same manner as in Example 1, except that stearic acid, which volatilized 63% under heating at 400°C in air and had a carbon residue content of 0.4% under heating at 800°C in an inert atmosphere, was used instead of melting non-toxic motor oil. The mixture was calcined, carbonized and graphitized in the same manner as in Example 1, and sieved to adjust the average particle size to 20.9 μm.

Embodiment 3

[0043] Components are melt-kneaded in the same manner as in Example 1, except that coal tar with quinoline insoluble content of 0.2% and fixed carbon content of 55% is used, and 63% is volatilized under heating at 400° C. in air. Stearic acid with a carbon residue content of 0.4% under heating at 800°C in an inert atmosphere is used instead of molten motor oil. The mixture was calcined, carbonized and graphitized in the same manner as in Example 1, and sieved to adjust the average particle size to 20.9 μm.

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Abstract

A process for producing a negative electrode material for lithium ion secondary battery having reduced irreversible capacity and increased reversible capacity through inhibiting of a fresh exposure of active surface of graphite generated by pulverization. The process is characterized in that graphite particles, pitch of 0.3% or less quinoline insoluble content and 50% or more fixed carbon content and a fusible organic substance of 50% or more volatile content when heated in air at 400 DEG C and 3% or less residual carbon ratio when heated in an inert atmosphere at 800 DEG C are melt kneaded together and the resultant mixture is fired so as to attain carbonization and graphitization and thereafter pulverized. In this process, preferably, the mixing ratio of graphite particles and pitch is such that 25 to 40 parts by weight of pitch is used per 100 parts by weight of carbonaceous particles, and the kneaded mixture after being molded into a molded form is fired so as to attain carbonization and graphitization and thereafter pulverized.

Description

technical field [0001] The invention relates to a manufacturing method of a negative electrode material for a lithium ion secondary battery. The negative electrode material has a small irreversible capacity and a large reversible capacity. Background technique [0002] Lithium ion secondary batteries are lightweight and have high energy density. Therefore, the lithium-ion secondary battery is regarded as a promising power source for driving portable instruments, storage battery, etc., and has been extensively studied. Carbon materials are used as negative electrode materials for lithium ion secondary batteries. In particular, graphite materials have high charge / discharge efficiency due to the high reversibility of insertion / extraction of lithium ions, and have a high theoretical capacity of 372mAh / g, and since the voltage during charge / discharge is almost equal to that of lithium, Capable of producing high voltage batteries. [0003] Graphite materials that are highly gra...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58C01B31/04H01M4/36H01M4/587
CPCC04B35/532H01M4/587H01M4/366H01M10/0525C04B2235/5436H01M4/133C04B35/522C04B2235/425Y02E60/10C01B32/205C01B32/21C01P2004/80C01P2006/40
Inventor 堂园充昭山本优威日向野聪泷泽健太郎
Owner TOKAI CARBON CO LTD
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