JP2002110248A - Non-aqueous electrolyte secondary battery and method of manufacturing the same - Google Patents

Abstract

(57) [Problem] To provide a non-aqueous electrolyte secondary battery excellent in shape freedom and a method of manufacturing the same. SOLUTION: A non-aqueous electrolyte secondary battery having an outer case composed of a laminate sheet mainly composed of a resin film is molded by a mold having a shape optimal for the shape of equipment to be used,
By a method of manufacturing by roll pressing, a thin device without dead space can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte secondary battery having an excellent degree of freedom in shape and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the performance of portable electronic devices such as mobile phones and personal digital assistants largely depends on not only the semiconductor elements and electronic circuits to be mounted but also the performance of rechargeable secondary batteries. It is desired that the capacity of the mounted secondary battery be increased and the weight and thickness be reduced at the same time. As a secondary battery that meets these demands, a nickel-metal hydride storage battery with an energy density about twice that of a nickel cadmium storage battery has been developed. It has been developed and is in the spotlight.

[0003] The non-aqueous electrolyte secondary battery has a cylindrical, square or flat shape. In particular, a non-aqueous electrolyte containing a battery element in an outer case formed of a laminate sheet mainly composed of a resin film. Secondary batteries are expected to be thinner batteries, and their development is urgent.

[0004]

However, such cylindrical, square and flat batteries are not optimal in the shape of the equipment, but have a dead space even if there are differences in length, width and height. Was occurring.

An object of the present invention is to eliminate the dead space by providing a non-aqueous secondary electrolyte secondary battery having an excellent degree of freedom in shape.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a flat battery element comprising a sheet-like or film-like positive electrode plate, a separator holding an electrolyte and a negative electrode plate, each of which is made of a resin film. In a battery stored in an outer case formed of a laminate sheet,
The non-aqueous electrolyte secondary battery, wherein the shape of the battery is a shape having a non-linear portion that is optimal for a device shape in which the battery is disposed, and the thickness is 4.0 mm or less. It is preferable for securing a degree of freedom.

A method for manufacturing a non-aqueous electrolyte secondary battery is characterized in that the battery is manufactured by molding in a mold having an optimum shape for the device in which the battery is to be disposed or by roll pressing. Yes, the temperature may be room temperature, but 40
By heating from a temperature of ° C. to a temperature equal to or lower than the softening point of the binder, it is possible to manufacture a battery having a shape optimal for a device at a low pressure.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a non-aqueous electrolyte secondary battery according to the present invention. The positive electrode is obtained by coating a paste obtained by kneading and dispersing a positive electrode active material, a binder, and, if necessary, a solvent in a solvent, onto an aluminum foil current collector 3, drying and rolling to form a positive electrode mixture layer 4. . A paste obtained by kneading and dispersing a carbon material capable of absorbing and releasing lithium through a separator 5 and a binder between the two positive electrodes in a solvent is applied to a copper foil current collector 7, dried and rolled. Then, the negative electrode on which the negative electrode mixture layer 6 is formed is provided, and the whole is laminated as shown in FIG. After the battery element 8 is housed inside the outer case 1, a predetermined amount of electrolyte is injected from the opening of the outer case 1, and the battery element 8 is sealed at the sealing portion 2 by heat welding.

Since the outer case 1 is required to have a barrier property of an electrolyte and water and a light shielding property, an electrolytic solution resistance and a mechanical strength are provided outside a metal foil layer made of aluminum foil of 20 to 50 μm. 10μm ~ 50μm thickness as required
Polyamide (nylon) resin layer, polyolefin resin such as polyethylene resin or polypropylene resin, which is required to have heat-sealing property and anti-short-circuit property with lead inside, and a copolymer or acid-modified resin layer of these An outer case is preferred.

As the positive electrode active material, a lithium-containing transition metal compound which can accept lithium ions as a guest is used. For example, cobalt, manganese, nickel,
A composite metal oxide of at least one metal selected from chromium, iron and vanadium with lithium, LiCoO ₂ ,
LiMoO ₂ , LiNiO ₂ , LiCo _x Ni _(1-x) O
₂ (0 <x <1) LiCrO ₂ , αLiFeO ₂ , LiV
O _{2 and the} like are preferred.

Examples of the negative electrode active material include graphite, activated carbon, and calcination and carbonized phenol resin or pitch. In particular, from the viewpoint of safety and cycle life characteristics, the lattice spacing of the lattice plane (002) is considered. (D ₀₀₂ ) is 3.35
A carbon material having a graphite type crystal structure of 0 to 3.400 ° is preferable.

Examples of the binder include a fluororesin material for maintaining the adhesion between active materials, a polymer material having a polyalkylene oxide skeleton, and a styrene-butadiene copolymer. As a fluorine-based resin material, polyvinylidene fluoride (PVDF), a copolymer P of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) (VDF-
HFP) is preferred.

The conductive material added as necessary is preferably a carbon-based conductive material such as acetylene black, graphite, or carbon fiber, and the plasticizer is diisobutyl phthalate, diethyl phthalate, di-n-butyl phthalate, or phthalate. Phthalates such as dipropyl acrylate and dihexyl phthalate are preferred.

As the solvent, a solvent capable of dissolving the binder is suitable. In the case of an organic binder, organic solvents such as acetone, cyclohexanone, N-methyl-2-pyrrolidone (NMP), and methyl ethyl ketone (MEK) are used. A solvent alone or a mixed solvent obtained by mixing these is preferable. In the case of an aqueous binder, water is preferable.

The positive electrode current collector is made of aluminum foil, lathed foil, or etched foil, and preferably has a thickness of 15 μm to 60 μm. The negative electrode current collector is made of copper foil, lath-finished foil, or etched foil, and has a thickness of 15 μm to 5 μm.
0 μm is preferred.

The same polymer as the binder can be used for the separator, and the polymer paste dissolved in the solvent is formed on a heat-resistant film such as polyethylene terephthalate (PET) resin and dried. The positive electrode and the negative electrode are laminated by applying temperature and pressure via the separator 5 to form an electrode plate group.

The non-aqueous electrolyte contains a non-aqueous solvent and an electrolyte. The non-aqueous solvent contains cyclic carbonate and chain carbonate as main components. Examples of the cyclic carbonate include ethylene carbonate (EC),
It is preferably at least one selected from propylene carbonate (PC) and butylene carbonate (BC). The chain carbonate is preferably at least one selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and the like.

As the electrolyte, for example, a lithium salt having a strong electron-withdrawing property is used. For example, LiPF ₆ , LiB
F ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , L
iN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , Li
C (SO ₂ CF ₃ ) _{3 and the} like. These electrolytes may be used alone or in combination of two or more. These electrolytes are preferably dissolved in the non-aqueous solvent at a concentration of 0.5 to 1.5M.

Next, the non-aqueous electrolyte secondary battery sealed in this manner is formed in a mold having an optimum shape for the device in which the battery is to be disposed, or is roll-pressed. A water electrolyte secondary battery is manufactured, and a battery having a shape optimal for a device shape can be obtained.

The optimal shape of the battery for the device varies depending on the shape of the device used, but various shapes such as a curved shape, a substantially U-shape, and a pipe shape are conceivable. In order to secure these free shapes, it is preferable that the thickness is 4.0 mm or less and that it is flexible.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to embodiments.

(Example 1) The positive electrode was LiCo as an active material.
O ₂ , a copolymer P (VDF-HFP) of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) as polymers as binders, and acetylene black as a conductive material were NMP (N-methyl). -2-pyrrolidone) is applied to a lath-processed aluminum foil current collector 3, dried and rolled to form a positive electrode mixture layer 4. Between the two positive electrodes, the graphitizable carbon capable of inserting and extracting lithium through the separator 5 composed of the P (VDF-HFP) film, and the P (VDF-HFP) powder mixed with acetone. A paste kneaded and dispersed in a mixed organic solvent composed of cyclohexanone was applied to a current collector 7 made of copper foil, dried and rolled to provide a negative electrode having a negative electrode mixture layer 6 formed thereon.
Are stacked to form the battery element 8.

After the battery element 8 is housed in the outer case 1, 1 to 1.5 mol of LiPF ₆ is mixed into a mixed solvent of ethylene carbonate and ethyl methyl carbonate at a volume ratio of 1: 3 through the opening of the outer case 1. After injecting a predetermined amount of the dissolved electrolytic solution, the non-aqueous electrolyte secondary battery was manufactured by sealing the sealing portion 2 by heat welding.

The lead portion of the non-aqueous electrolyte secondary battery thus manufactured was insulated with an insulating tape, and then pressed with a hot roll heated to 60 ° C.
A battery 9 having a vertical dimension of 95 mm, a horizontal dimension of 190 mm, and a thickness of 2.8 mm as shown in FIG.
This battery could be arranged along the curved part of the information device exterior body 10, and a thin device with no dead space could be obtained.

(Example 2) A lead portion of a non-aqueous electrolyte secondary battery produced in the same manner as in Example 1 was insulated with an insulating tape, and then a vertical dimension was 30 mm, a horizontal dimension was 500 mm, and a thickness was 1.9 mm. The arc-shaped battery 11 was produced. This battery could be arranged along the entire outer edge of the audio equipment exterior body 12, and a thin apparatus with no dead space could be obtained.

[0027]

As described above, the nonaqueous electrolyte battery according to the present invention is excellent in the degree of freedom of the shape of the battery, can be formed in the shape most suitable for the shape of the equipment to be used, and has no dead space. Equipment can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a battery according to an embodiment of the present invention.

FIG. 2 is a schematic view of a usage example of a battery according to an embodiment of the present invention.

FIG. 3 is a schematic view of another example of use of the battery in one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer case 2 Sealing part 3 Positive electrode collector 4 Positive electrode mixture layer 5 Separator 6 Negative electrode mixture layer 7 Negative electrode collector 8 Battery element 9 Curved battery 10, 12 Equipment exterior body 11 Pipe-shaped battery

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H011 AA06 CC02 CC10 5H029 AJ00 AK03 AK05 AL06 AL07 AL08 AM03 AM05 AM07 BJ04 BJ12 CJ03 CJ06 CJ28 DJ02 DJ04 HJ04

Claims (3)

[Claims] 1. A battery in which a flat battery element in which a sheet-like or film-like positive electrode plate, a separator holding an electrolyte, and a negative electrode plate are laminated, respectively, is housed in an outer case formed of a laminate sheet mainly composed of a resin film. A non-aqueous electrolyte secondary battery characterized in that the shape of the battery is a shape having a non-linear portion that is optimal for the device shape in which the battery is disposed. 2. A battery in which a flat battery element in which a sheet-like or film-like positive electrode plate, a separator holding an electrolyte, and a negative electrode plate are laminated is housed in an outer case formed of a laminate sheet mainly composed of a resin film. In the manufacturing method, the non-aqueous electrolyte secondary is characterized in that the shape of the battery is manufactured by molding in a mold having an optimum shape for the device shape in which the battery is arranged, or by roll pressing. Battery manufacturing method. 3. The shape of the battery has a thickness of 4.0 m.
2. The non-aqueous electrolyte secondary battery according to claim 1, wherein m is equal to or less than m.