Anode material for lithium secondary battery, manufacturing method of the same, lithium secondary battery anode using the same, and lithium secondary battery

A lithium secondary battery and negative electrode material technology, which is applied in the field of negative electrode materials and preparation of the negative electrode material, can solve the problems of easily broken particles, decreased load characteristics, and reduced space, and achieve high efficiency, large discharge capacity, and excellent load characteristics. Effect

Active Publication Date: 2007-02-21
MITSUBISHI RAYON CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] Another problem that arises when graphite anode materials are used at higher electrode densities is that the reaction with the electrolyte is accelerated as the graphite anode material cracks and exposes more surface area that is highly reactive to the electrolyte, easily leading to charging and Reduced discharge efficiency
[0009] In addition, since the particles are easily broken when used at a higher electrode density, the spaces serving as lithium ion channels in the electrode are reduced, impairing lithium ion mobility, and deteriorating load characteristics

Method used

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  • Anode material for lithium secondary battery, manufacturing method of the same, lithium secondary battery anode using the same, and lithium secondary battery

Examples

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Effect test

preparation example Construction

[0141] (1) Preparation of electrodes

[0142] The negative electrode material is mixed with an aqueous solution of CMC (carboxymethyl cellulose) acting as a thickener and an aqueous solution of SBR (styrene butadiene rubber) acting as a binder resin, so that the negative electrode material obtained by drying, CMC The total weight of the mixture with SBR, the content of each of CMC and SBR is 1% by weight. The mixture was stirred into a slurry form, and then coated on a copper foil with a thickness of 18 μm with a doctor blade. Adjust the slit width of the doctor blade that limits the coating thickness so that the amount of electrode after drying (excluding copper foil) is 10mg / cm 2 . Then dry the obtained electrode at 80°C and press to make the electrode density (excluding copper foil) 1.63±0.05g / cm 3 .

[0143] (2) Determination of active material orientation ratio

[0144] Using the extruded electrode, the active material orientation ratio of the electrode was measured by X-ray ...

Embodiment 1

[0286] The coal tar pitch with a quinoline insoluble content of 0.05% by weight or less is heat-treated in a reaction furnace at 460°C for 10 hours to obtain a meltable block heat-treated graphite crystal precursor with a softening point of 385°C. Determine the softening point using the method described previously.

[0287] The block heat-treated graphite crystal precursor thus obtained is first pulverized with an intermediate pulverizer (Orient Mill produced by Seishin Enterprise Co., Ltd.), and then pulverized to a fine powder using a micro pulverizer (Turbo-Mill produced by Matsubo Corporation), A micronized graphite crystal precursor powder with a median diameter of 17 μm was obtained. Determine the median diameter using the method described above.

[0288] The micronized graphite crystal precursor powder obtained above is mixed with natural graphite, the median diameter of the natural graphite is 17 μm, the aspect ratio is 1.9 and the tap density is 1.0 g / cm 3 The ratio of th...

Embodiment 2

[0320] A coarse pulverizer (roller jaw crusher produced by Yoshida Manufacturing Co., Ltd.) was used to pulverize the block graphite crystal precursor mixture obtained by a similar procedure in Example 1 to coarse powder, and then a pulverizer (from Dalton Co., Hammer mill produced by Ltd.) pulverized to finer powder. The obtained fine powder was sieved with a sieve with a mesh of 45 μm to obtain a micronized graphite crystal precursor powder with a median diameter of 21.0 μm. The calcination treatment and subsequent procedures are the same as those of Example 1, to obtain a graphite composite mixed powder (C) (the negative electrode material of Example 2).

[0321] The physical properties of the negative electrode material obtained in Example 2 were measured by the same method as in Example 1. The measurement result was that the median diameter was 20.0μm and the tap density was 1.20g / cm 3 And BET specific surface area is 1.8m 2 / g. As in Example 1, the crystallinity was measured...

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Abstract

The invention provides an excellent graphite negative electrode material for lithium secondary batteries which enables to obtain a lithium secondary battery which has high discharge capacity, high charge / discharge efficiency, and excellent load characteristics when used at a high electrode density and also has small electrode expansion at charging. The graphite negative electrode material contains a graphite composite mixed powder (C) composed of a graphite composite powder (A), wherein a graphite (D) having an aspect ratio of not less than 1.2 and not more than 4.0 and a graphite (E) having an orientation different from that of the graphite (D) are composited, and an artificial graphite powder (B).

Description

Technical field [0001] The invention relates to a negative electrode material for a lithium secondary battery made of graphite composite mixed powder, a preparation method thereof, and a negative electrode for a lithium secondary battery and a lithium secondary battery using the negative electrode material. Specifically, the present invention relates to a negative electrode material, when used with a high electrode density, it can produce an excellent lithium secondary battery, the lithium secondary battery has a large discharge capacity, high efficiency in charge and discharge, performance It has excellent load characteristics and only a small amount of electrode expansion during charging; the present invention also relates to a method for preparing the negative electrode material and a lithium secondary battery negative electrode and a lithium secondary battery using the negative electrode material. Background technique [0002] In recent years, with the miniaturization of elec...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58C01B31/04H01M4/02H01M10/40H01M4/587H01M10/0525H01M10/36
CPCY02E60/122H01M10/0525H01M4/587C01B31/04C01B32/20C01B32/205C01B32/21Y02E60/10H01M2004/027
Inventor 宇尾野宏之山口庆太布施亨
Owner MITSUBISHI RAYON CO LTD
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