Lithium ion secondary battery

A secondary battery and lithium-ion technology, applied in the direction of secondary batteries, battery pack components, non-aqueous electrolyte battery electrodes, etc., can solve problems such as insufficient movement channels, difficulty in porous membrane strength, etc., to ensure heat resistance, The effect of suppressing internal short circuit and suppressing falling off

Active Publication Date: 2006-06-28
PANASONIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

As a result, contrary to the strength, the voids between the filler particles are reduced, which tends to make the electrolyte solution or the movement path of lithium ions between the positive electrode 53 and the negative electrode 54 insufficient.
In other words, it is difficult to ensure sufficient lithium ion conductivity while maintaining a certain strength
[0012] In addition, since no resin with suitable physical properties has been found as a resin binder for a porous membrane, it is difficult to further improve the strength of the porous membrane while maintaining lithium ion conductivity.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0111] Refer below figure 2 versus image 3 Be explained.

[0112] (i) Production of positive electrode

[0113] Relative to 100 parts by weight of LiCoO 2 , Add 4 parts by weight of polyvinylidene fluoride (PVDF) as a binder and 3 parts by weight of acetylene carbon black as a conductive agent, and then add an appropriate amount of NMP (N-methyl-2-pyrrolidone) for mixing to prepare The positive electrode mixture paste is produced.

[0114] The obtained positive electrode mixture paste was coated on both sides of an aluminum foil core material 21 with a thickness of 20 μm, and rolled so that the active material density (LiCoO 2 The density) is 3.3 g / ml, which is used as the positive electrode 23. A positive electrode lead 24 made of aluminum is connected to the positive electrode 23.

[0115] (ii) Production of negative electrode

[0116] Relative to 100 parts by weight of spherical artificial graphite, add 1 part by weight of styrene-methacrylic acid-butadiene copolymer as a bin...

Embodiment 2

[0151] (i) Production of positive and negative electrodes

[0152] In the same manner as in Example 1, a positive electrode and a negative electrode were produced.

[0153] (ii) Formation of porous membrane

[0154] The raw material paste of the porous membrane was prepared in the same manner as in Example 1. Here, at the ratio shown in Table 3, the filler and the resin binder were dispersed in NMP and kneaded to prepare the raw material paste of the porous membrane. The content of the raw materials (the total amount of the filler and the resin binder) in the paste is set to 50% by weight in any case. The filler alone uses alumina (Al 2 O 3 ).

[0155]

Example

Relative to every 100 parts by weight of filler

Amount of resin binder (parts by weight)

Filler average

Particle size (μm)

Porous membrane micro

Average pore size

(μm)

Porous membrane

Stripping

High rate

Characteristics

(%)

BM500B

PVDF

A...

Embodiment 3

[0177] (i) Production of positive electrode

[0178] A positive electrode was produced in the same manner as in Example 1, except that the size of the electrode plate was changed to a predetermined size.

[0179] (ii) Production of negative electrode

[0180] The negative electrode mixture was attached to both sides of the copper foil core material, and the active material density (the density of graphite) was rolled to 1.4 g / ml, and the size of the electrode plate was changed to a predetermined size, except that it was produced in the same manner as in Example 1. negative electrode.

[0181] (iii) Formation of porous membrane

[0182] According to the ratio shown in Table 4, the filler and the resin binder were dispersed in NMP and kneaded to prepare the raw material paste of the porous membrane. The content of the raw materials (the total amount of the filler and the resin binder) in the paste is set to 50% by weight in any case.

[0183] As in Example 1, the filler alone used a...

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Abstract

A lithium ion secondary battery includes a positive electrode capable of absorbing and desorbing lithium ion, a negative electrode capable of absorbing and desorbing lithium ion, a porous film interposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte: the porous film being adhered to a surface of at least one of the positive electrode and the negative electrode; the porous film including a filler and a resin binder; the resin binder content in the porous film being 1.5 to 8 parts by weight per 100 parts by weight of the filler; and the resin binder including an acrylonitrile unit, an acrylate unit, or a methacrylate unit.

Description

Technical field [0001] The present invention relates to a lithium ion secondary battery having a porous film, wherein the porous film is composed of a filler and a resin binder and is bonded to the surface of at least one of a positive electrode and a negative electrode. The invention relates to a lithium ion secondary battery, which does not cause thermal runaway even if it is short-circuited, and has excellent safety. Background technique [0002] With the development of mobile and wireless electronic equipment, as its driving power source, the attention is drawn to small, lightweight and high-energy density lithium ion secondary batteries. The lithium ion secondary battery has a positive electrode composed of a transition metal oxide containing lithium or the like, a negative electrode composed of a carbon material or the like, and a non-aqueous electrolyte. [0003] In a lithium ion secondary battery, the separator is interposed between the positive electrode and the negative...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/40H01M2/16H01M4/02H01M4/13H01M10/0525H01M10/0587H01M50/409H01M50/491
CPCY02E60/122Y02E60/10Y02P70/50
Inventor 大畠积中岛润二林徹也高野隆生田茂雄铃木刚平西田耕次福永政雄藤野明子
Owner PANASONIC CORP
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