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Method of producing negative electrode for non-aqueous electrolyte secondary battery, negative electrode, and non-aqueous electrolyte secondary battery using the same

A non-aqueous electrolyte and secondary battery technology, which is applied in the direction of electrode manufacturing, secondary batteries, battery electrodes, etc., can solve the problem of cycle characteristics degradation, and achieve the suppression of the degradation of charge and discharge cycle characteristics, high reliability, and excellent charge and discharge Effects of Cyclic Properties

Inactive Publication Date: 2011-08-10
PANASONIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, the negative electrode mixture layer may be peeled off from the negative electrode core material, and the cycle characteristics may be reduced.

Method used

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  • Method of producing negative electrode for non-aqueous electrolyte secondary battery, negative electrode, and non-aqueous electrolyte secondary battery using the same
  • Method of producing negative electrode for non-aqueous electrolyte secondary battery, negative electrode, and non-aqueous electrolyte secondary battery using the same
  • Method of producing negative electrode for non-aqueous electrolyte secondary battery, negative electrode, and non-aqueous electrolyte secondary battery using the same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0075] (1) Preparation of negative electrode

[0076] With artificial graphite 3kg (manufactured by Mitsubishi Chemical Co., Ltd., average particle diameter 20 μ m, average circularity 0.72) as the negative electrode active material, BM-400B (the styrene-butadiene rubber (SBR containing 40% by weight) made by Japan Zeon Co., Ltd. ) of aqueous dispersion) 75g, and 30g of carboxymethylcellulose (CMC) and an appropriate amount of water were stirred with a double-arm kneader to prepare negative electrode slurry. The negative electrode slurry was coated on both sides of the negative electrode core material formed by a copper foil with a thickness of 10 μm, and dried to form a negative electrode active material layer. In this way a negative electrode precursor is obtained.

[0077] Then, the negative electrode precursor was compressed by passing between a pair of heated rollers. The number of times of compression is set to 1 time. More specifically, while heating the negative ele...

Embodiment 2

[0131] In addition to setting the line pressure in process (2) to 2.0×10 2 Except that kgf / cm and heating temperature were changed to the values ​​shown in Table 3, a negative electrode was produced in the same manner as in Example 1. Using this negative electrode, a battery was fabricated by the same method as in Example 1. The negative electrodes and batteries were evaluated by the methods described above. The evaluation results are shown in Table 3.

[0132] table 3

[0133]

[0134] In negative electrodes B to E, the density of graphite particles in the negative electrode mixture layer is 1.5g / cm 3 As mentioned above, the decrease rate of the average circularity of graphite particles at the time of compression is 20% or less. In Batteries B to E in which the heating temperature in the step (2) was 50 to 100° C., a negative electrode having a high density of graphite particles in the negative electrode mixture layer was obtained, and excellent charge-discharge cycle ...

Embodiment 3

[0136] A negative electrode was produced in the same manner as in Example 1, except that the heating temperature in step (2) was set to 80° C. and the line pressure was changed to the value shown in Table 4. Using this negative electrode, a battery was fabricated by the same method as in Example 1. The negative electrodes and batteries were evaluated by the methods described above. The evaluation results are shown in Table 4.

[0137] Table 4

[0138]

[0139] In negative electrodes G~J, the density of graphite particles in the negative electrode mixture layer is 1.5g / cm 3 As mentioned above, the decrease rate of the average circularity of the graphite particles at the time of compression is 30% or less. The line pressure in process (2) is 1.0×10 2 ~3.0×10 2 In Batteries G to J of kgf / cm, negative electrodes having a high density of graphite particles in the negative electrode mixture layer were obtained, and excellent charge-discharge cycle characteristics were obtain...

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Abstract

A method of producing a non-aqueous electrolyte secondary battery of the present invention includes the steps of: (1) producing a negative electrode precursor by applying a negative electrode slurry including graphite particles and a binder onto a negative electrode core material and drying the same to form a negative electrode material mixture layer; and (2) producing a negative electrode by compressing while heating the negative electrode precursor at a temperature at which the binder softens. In the step (2), a temperature at which the negative electrode precursor is heated and a force with which the negative electrode precursor is compressed are controlled such that the compressed negative electrode material mixture layer in the negative electrode includes 1.5 g or more of the graphite particles per 1 cm3 of the negative electrode material mixture layer, and that an average circular degree of the graphite particles maintains 70% or more of an average circular degree of graphite particles in the negative electrode precursor.

Description

technical field [0001] The present invention relates to a non-aqueous electrolyte secondary battery, and particularly to a method for producing a negative electrode containing graphite particles as a negative electrode active material. Background technique [0002] The negative electrode of a nonaqueous electrolyte secondary battery represented by a lithium ion secondary battery generally contains graphite particles as a negative electrode active material. [0003] This negative electrode was produced as follows. Negative electrode slurry is prepared by mixing graphite particles, a binder and, if necessary, a conductive agent in the presence of a predetermined dispersion medium. This negative electrode slurry is coated on a negative electrode core material made of copper foil or the like, and then dried to form a negative electrode mixture layer to obtain a negative electrode precursor. Then, by compressing the negative electrode precursor with a roller, the density of the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/1393H01M4/133
CPCH01M4/0402H01M4/661H01M4/1393H01M4/622H01M4/621H01M4/623H01M4/0471H01M10/0525Y02E60/122H01M4/133Y02E60/10
Inventor 菅谷纯一村冈芳幸
Owner PANASONIC CORP
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