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Modified graphite particle and battery using it

A graphite particle modification technology, applied in the direction of graphite, battery electrodes, secondary batteries, etc., can solve the problems of reduced battery cycle life, low anode filling density, uneven reaction, etc.

Inactive Publication Date: 2005-03-16
SUMITOMO ELECTRIC IND LTD +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] (1) Anode packing density is low
[0009] (2) The reaction sites of the charging / discharging reaction are concentrated at the corner edges of graphite particles, resulting in uneven reaction
[0014] (4) Due to the above-mentioned decline in charge / discharge capacity, especially the decline in discharge capacity, lithium ions gradually gather in graphite particles with repeated charge and discharge, which increases the loss of lithium ions
[0016] As a result, the cycle life of the battery decreases

Method used

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  • Modified graphite particle and battery using it
  • Modified graphite particle and battery using it

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0086] Such as figure 1 As shown, flaky graphite particles NG12 obtained from Kansai Netsukagaku K.K. were continuously processed in an air classifier 1 . According to the throughput of graphite particles fed by the particle feeding pipe 12 per unit time, the rotational speed of the wear-resistant classifying drum 11 and the flow rate of the air fed by the air feeding pipe 13 for secondary dispersion are adjusted.

[0087] The obtained modified graphite particles had an average particle diameter Ap of 12 µm and a BET specific surface area Ss of 4.1 m2 / g, resulting in Ss / Ap of 0.342. Electron micrographs of modified graphite particles in figure 2 given in. It can be seen that the pellet has been broken or slightly folded at its circumference into an almost round and flattened pellet.

Embodiment 2

[0089] Modified graphite particles were obtained in the same manner as in Example 1 except that flake graphite particles NG 18 available from Kansai Netsukagaku K.K. were used. The average particle size Ap of the obtained modified graphite particles is 18 μm and the BET specific surface area Ss is 5.8 m 2 / g, resulting in Ss / Ap of 0.322. Electron microscopic observations showed that the particles had been broken or slightly folded at their circumference into nearly round and flat particles similar to Example 1.

Embodiment 3 and 4 and comparative example 3 and 4

[0105] (1) Preparation of anode

[0106] An anode was prepared in the same manner as above.

[0107] (2) Preparation of cathode

[0108] 10 parts of lithium cobaltate powder, 1 part of flaky graphite powder with an average particle diameter of 0.6 μm, and 1 part of PVdF powder were mixed, and then the mixture was kneaded with N-methyl-2-pyrrolidone to form a paste. Apply the paste at 0.03 g / cm per side 2 A dry coating weight of 20 μm thick aluminum foil was applied on both sides, heated to 150 °C to remove N-methyl-2-pyrrolidone, and then rolled to reduce the thickness of the active material layer to 80% of the initial thickness. The resulting sheet was cut into 20 cm squares.

[0109] (2) Insert the battery

[0110] 360 cathodes and the same number of anodes were alternately stacked with a 25 μm thick polyethylene porous membrane inserted between each adjacent electrode as a separator to prepare an electrode group.

[0111] The same nonaqueous organic electrolyte solutio...

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Abstract

Modified graphite particles are described, which have an almost circular and tabular shape, an average particle size Ap of 12 to 18 mum, a BET specific surface area Ss of 4 to 6 m2 / g, and a BET specific surface area to average particle size ratio, Ss / Ap, of 0.35 or less, and which are obtained by treating tabular particles of lumpy or flaky graphite to break or slightly fold the periphery of said tabular particles to increase the degree of circularity. A battery having the modified graphite particles as an anode active material is also described.

Description

technical field [0001] The present invention relates to modified graphite particles suitable as an active material for batteries, such as non-aqueous storage batteries, and batteries using it as an active material. Background technique [0002] Non-aqueous secondary batteries using lithium ions have high energy density and energy efficiency and provide higher voltage than other kinds of batteries. Therefore, they have been studied mainly as small to ultra-small power supplies for small cordless electronic devices such as mobile phones, personal handyphone systems (PHS), and notebook personal computers. More recently, they are also expected as large batteries with capacities exceeding 10Ah, which can be used as power sources for electric or hybrid vehicles or as small power storage devices for homes, shops or small factories. [0003] Nonaqueous secondary batteries used hitherto generally contain metallic lithium as an anode active material. In rece...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B31/04H01M4/587H01M10/05
CPCC01P2006/12H01M4/133C01P2004/54Y02E60/122H01M4/587C01P2004/22H01M2004/021C01P2004/61C01B31/04C01B32/21Y02E60/10
Inventor 真嶋正利稻泽信二氏家谕矢崎惠里子坛上和冶本间真一
Owner SUMITOMO ELECTRIC IND LTD