JPH10308198A - Layered film for battery enclosing body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a short circuit between terminals through a metallic layer by arranging a resin layer which has respectively a tensile elastic modulus and/or a compression elastic modulus of a layered film not less than a specific range so as to be sandwiched between a metallic layer and a thermally welding resin layer. SOLUTION: A resin layer which has high mechanical strength and has a tensile elastic modulus not less than 300 kg/mm<2> and/or a compressive elastic modulus not less than 50 kg/mm<2> , is arranged so as to be sandwiched between a metallic layer and a thermally welding resin layer. A polyester resin layer and an aromatic polyamide resin layer are desirable. A polyethylene terephthalate film has a tensile elastic modulus not less than 400 kg/mm<2> , and is desirably used as a polyester resin film. A thickness of the resin film is desirable to be 10 to 50 μm. The resin film has electric insulating performance, and volume resistivity is set not less than 10<6> Ω.cm. Therefore, weight reduction and high capacity of a battery are realized, and stability and safety are also improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film material that is a battery outer package material.

2. Description of the Related Art Lightening of battery-applied devices such as portable devices,
With the reduction in thickness, the weight and capacity of batteries to be mounted have been reduced. For example, lithium batteries are widely used as high-capacity batteries utilizing a low oxidation-reduction potential of lithium. Heretofore, a container formed of a metal plate as a material and formed into a cylindrical shape, a square shape, a coin shape, or the like has been used for the outer body of these batteries depending on the application. However, when a metal plate is used, there is a limit in weight reduction and freedom in shape. On the other hand, a flat battery mainly composed of a metal foil and a resin film is disclosed in JP-A-60-100362, and a solid electrolyte battery using a laminate film composed of a metal foil and a heat-fusible film is disclosed in JP-A-60-100. -49568 discloses are disclosed in, JP 60-65442. In this case, the metal foil does not double as an external terminal and is used as a gas shielding material, and is formed of two layers of metal foil / heat-fusible film or three layers of resin film / metal foil / heat-fusible film. From the inside of the heat-fusible film
The terminal is taken out by a US film or the like. Japanese Patent Application Laid-Open Nos. 4-51455 and 4-106 disclose a thin battery in which a heat-fusible resin is sandwiched between metal plates also serving as current collectors.
No. 867 and the like. On the other hand, in a battery using a metal plate, an exterior body also serves as a terminal, and a power generation element is connected to the exterior body / terminal inside the battery. The insulation between the positive electrode terminal and the negative electrode terminal is maintained by a glass hermetic seal or by sandwiching an insulating resin between the exterior and external terminals.

However, in a battery packaged with a package made of a laminate film having a metal layer and a heat-fusible resin layer, the outside of the package is covered with an insulating resin film. In some cases, a phenomenon of short-circuiting between external terminals may be observed. This is because when the laminate film is heat-sealed, minute projections or irregularities of the metal terminal penetrate the heat-fusible resin layer and come into contact with the metal layer, so that the positive electrode terminal and the negative electrode terminal are interposed through the metal layer. Is short-circuited.
When such a short circuit occurs, the potential does not increase when charging the battery. In addition, there is a case where the heat-fusible resin layer does not penetrate, but may be thin, and in such a case, a problem such as a short circuit due to an impact or the like in a charged state and heat generation may occur. On the other hand, when there is no metal layer, the gas shielding property, particularly the shielding effect against water vapor, is significantly reduced. For this reason, in a lithium battery or the like, there is a problem that the battery performance is greatly deteriorated. Therefore, the metal layer is indispensable in the laminated film for the battery package. The present invention
An object of the present invention is to provide a battery with high safety and stability by preventing a short circuit between terminals via a metal layer.

Means for Solving the Problems The present inventors have proposed a battery lighter.
Metal layer and heat-fusible resin layer
On batteries with a laminated film having an outer package
After proceeding with the study, as mentioned above,
Clarified the problem of terminal short-circuit through the resulting metal layer,
As a solution, the metal layer of the exterior body and the heat-fusible resin layer
To provide a resin layer with high mechanical strength between
Thus, the present invention has been completed. That is, the present invention provides (1)
And a laminated film having a metal layer and a heat-fusible resin layer.
Has a tensile modulus of elasticity of 300 kg / mm^TwoAnd / or
Or the compression modulus is 50kg / mm^TwoAbove the resin layer above
It is specially provided between the metal layer and the heat-fusible resin layer.
Laminated film for battery exterior body, (2) metal layer and
The resin layer provided between the heat-fusible resin layers is
400 kg / mm^TwoAbove and / or compression elasticity
Rate is 50kg / mm^TwoIn the above polyester resin layer
(1) The laminated film for a battery outer package according to the above (1),
Lum, (3) sandwiched between the metal layer and the heat-fusible resin layer
Resin layer has a tensile modulus of elasticity of 300 kg / mm^Twothat's all
And / or a compression modulus of 50 kg / mm^TwoBetter
The above-mentioned 1 characterized in that it is an aromatic polyamide resin layer.
(4) The above-mentioned (1),
(2) or (3) using the laminated film for a battery package.
A caged battery. Less than,
The present invention will be described in detail. Laminated foil for battery exterior body of the present invention
The film has at least a metal layer and a heat-fusible resin layer.
And a resin layer with high mechanical strength between both layers
It is a laminated body provided, preferably having four or more layers,
Having an insulating resin layer on the outside and a heat-fusible resin layer on the innermost side,
A metal layer is provided between the metal layer and the heat-fusible resin layer.
It has a resin layer with high mechanical strength. Innermost heat
As the heat fusible resin used for the fusible resin layer, poly
Ethylene, polypropylene, ionomer resin, police
Tylene, polyvinyl alcohol, polyvinyl chloride, poly
Amide, polyester, polyvinylidene chloride, polycarbonate
Thermoplastic resins such as carbonate and polyphenylene oxide
No. Of these thermoplastic resins, polyethylene
, Ionomer resin and polypropylene are in close contact with the electrode terminals
It has a high sealing property and is preferably used for a battery exterior body.
Also, the adhesion between the laminated layers and the electrode terminals
The surface of the heat-fusible resin film is oxidized to improve
Can be applied. Strength and lightness at the time of fusion
From the balance of quantification, the thickness of the heat-fusible resin layer is 30 μm
The thickness is preferably 100 μm or less. More than 30μm
Above, 70 μm or less is preferable. Used in the present invention
Aluminum, aluminum
Alloy, SUS, Ni and the like. Among these
Aluminum metal and aluminum alloy are lightweight
It is preferable because of excellent workability. The thickness of the metal layer is
7μm or more from the balance between water vapor shielding effect and weight reduction
It is preferably 30 μm or less, more preferably 10 μm or less.
The upper limit is 25 μm or less. The metal layer is sheet-shaped and heat
Lamination with plastic resin film, or evaporation
It is formed by a method or the like. In the present invention, the metal layer
High mechanical strength between the adhesive resin layers, that is, tensile
The elastic modulus is 300kg / mm^TwoOr more and / or compressed bullets
50 kg / mm^TwoIt is recommended to provide the above resin layer
Is necessary. Sandwiched between the metal layer and the heat-fusible resin layer
Resin film used to form a resin layer with high mechanical strength
As aromatic polyamide resin film,
Tell-based resin film, glass fiber-containing nylon fill
Film, cellophane, biaxially stretched polyvinyl alcohol film
And the like. Aromatic polyamide resin film
For example, Kapton (product of Toray Industries, Inc.)
Aramica (trade name, manufactured by Asahi Kasei Kogyo Co., Ltd.)
I can do it. Among them, Aramica has a tensile modulus of elasticity of 1000.
kg / mm^Two, Compression modulus 100 kg / mm^TwoAbove,
It is preferably used because of its excellent mechanical strength.
You. Polyester resin films include polyethylene
The terephthalate film has a tensile modulus of elasticity of 400 kg /
mm^TwoThis is the preferred method. The resin fill
To prevent the metal terminal projections from sticking out.
300 kg / mm^TwoAbove and / or compression elasticity
Rate 50 kg / mm^TwoMust be at least
Or the tensile modulus is 350kg / mm^TwoAnd / or
Or compression modulus 70 kg / mm^TwoThat is all. further
Preferably, the tensile modulus is 400 kg / mm^TwoAnd / or
Or compression modulus 100 kg / mm^TwoThat is all. Ma
The thickness of the resin film is 1 μm or more and 50 μm or less.
The lower part is preferable, and more preferably 10 μm or more, 50 μm
m or less. The resin film used in the present invention is an electric
Insulating, volume resistivity is 10⁶Ω · cm or more
Is preferred. In the present invention, the outermost insulating resin
Layers can be provided, in a preferred manner as described above.
is there. As an insulating resin used for the insulating resin layer,
Is cellophane, nylon, polyethylene terephthale
, Vinylidene chloride polymer, aromatic polyamide,
Carbonate and even vinylidene chloride coated
Nylon, polyethylene terephthalate, polypropylene
And phenolic resins, fluororesins, etc.
But nylon, polyethylene terephthalate,
Nilidene polymer, aromatic polyamide, vinylidene chloride
Coated nylon, polyethylene terephthalate
Is preferably used because of its high mechanical strength. The
Is the thickness of the insulating resin layer a balance between mechanical strength and weight reduction?
It is preferable that the thickness is 10 μm or more and 50 μm or less.
It is more preferably 10 μm or more and 30 μm or less. Book
The method for producing a laminated film for a battery outer package of the present invention
, Wet lamination, extrusion coating,
Co-extrusion lamination, dry lamination,
Tmel lamination, heat lamination, etc.
But not particularly limited to these methods.
Absent. For example, heat lamination and fusion of sheets
Method, low melting point
And a method of sandwiching the lum between them. Also moisture curing
Urethane polyether, moisture-curable urethane poly
Ester, urethanized polyether, urethanized polyether
Stels, polyester polyols, polyisocyanates
And the like. In addition, hotmel
Glue the polymer melt on the substrate
Cast or extruded film forming method, polymer solution or
It is possible to cast the polymer precursor in the liquid state
is there. This laminated film structure and manufacturing method
Water barrier properties, sealing method, and adhesion of electrode terminals
Can be determined in consideration of Battery outer body of the present invention
As a specific example of the laminated structure of a laminated film for
Terephthalate / aluminum / aromatic polyamide /
Polypropylene, stretched nylon / aluminum / aromatic
Polyamide / polyethylene, aromatic polyamide / aluminum
/ Aromatic polyamide / ionomer resin, polye
Tylene terephthalate / aluminum / polyethylene te
Lephthalate / polypropylene, polyethylene terephthalate
Rate / polyethylene / aluminum / polyethylene te
Phthalate / polypropylene, polyethylene / aluminum
Nylon / glass fiber containing nylon / polypropylene etc.
Can be mentioned. Aluminum layer // heatable
A structure in which unit laminates of plastic resin layers are further laminated
It can also be used. Further, the laminated film
The laminated film from which a part of the minium layer has been removed is also the present invention.
It can be used as a laminated film for battery exterior
Seal the electrode terminal area with the part not containing the aluminum layer
You. Outside the battery comprising the laminated film for a battery exterior body of the present invention
The battery can be manufactured by packaging the package. The battery
Heat sealing, impulse
Method using friction heat such as seal, spin weld, laser
External heating such as heat, infrared, hot jet, high frequency
Internal heating method such as seal, ultrasonic seal, polyvinyl alcohol
Alcohol, olefin, rubber, polyamide, etc.
Hot melt adhesive can be used. Any
Whether the sealing method is used depends on whether the polymer
What is necessary is just to determine in consideration of the kind and structure of a layer material. Ma
In addition, the adhesive between the polymer laminate materials
They can also be joined and packaged. Battery of the present invention
The water permeability of the laminated film for exterior body is 1 g / m^Two・ 2
It is 4 hours or less. This water permeability is low for a non-aqueous battery
And preferably 0.2 g / m^Two・ 24hr
Or less, more preferably 0.1 g / m^Two・ 24 hours or less
It is. Permeability 1g / m^Two・ Battery exterior that exceeds 24 hours
Batteries using body materials have battery structural elements inside the battery
Deteriorated by water absorption, which is preferable because it reduces battery capacity.
I don't. Also, the internal electrolyte material is separated by this water absorption.
Undesirably, gas may be generated. This water permeability
The amount of water absorption such as anhydrous calcium chloride inside the package
After enclosing the material and maintaining it in the specified atmosphere, measure the weight increase.
The present invention, which can be measured and determined, is used for a lithium battery.
In this case, aluminum is used as the positive electrode current collector,
Copper and nickel are used as the negative electrode current collector. To the terminal
SUS, nickel, aluminum and copper are used.
Further, as an active material used for the positive electrode material, LiCoO_Two
Transition metal composite oxides such as MnO_TwoSuch as
Composite oxides with oxides or hydroxides of other metals, V_TwoO_Five
Such as vanadium oxide, Cr_TwoO_FiveChromium oxide, etc.
TiS_Two, MoS_Two, FeS_TwoTransition metal dichalcogenes
Knight, NbSe_ThreeTransition metal trichalcogenites such as
Chevrelle phase (AxMo₆Y ₈, A = Li, Cu, Y =
S, Se) and the like are used. The active material used for the negative electrode material
Metal lithium, lithium alloy, needle coke
Can store lithium such as graphite and graphite
Carbon material, Si_xSn _1-xO_FourComplex oxides such as
Conductive polymer that can be doped with undoped and undoped
Is used. Carbonate as an ion transfer medium between electrodes
Uses lithium salt solutions, gel electrolytes, and solid electrolytes
Can be. Among them, polymer materials of gel electrolyte
Materials include polyvinylidene fluoride polymer, polyacryloyl
Nitrile polymers and the like are used, and ethylene is used as an organic solvent.
Carbonate, propylene carbonate, γ-butyro
Lactone, 1,2 dimethoxyethane, tetrahydrof
Orchid is used, and LiClO_Four, LiP
F₆, LiBF_FourAre used. As described above, the present invention
Battery is lightweight, has excellent battery performance stability, safety, and production
This is industrially preferable because the above failure rate can be reduced.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the battery of the present invention will be described based on examples.

Example 1 A positive electrode made of 6 cm × 50 cm LiCoO ₂ and a 7 cm × 52 cm polyvinylidene fluoride (Kynar2850 trade name, manufactured by Atochem) were mixed with 1.5 M L
A gel electrolyte swelled with a 1: 1: 2 mixed solution of iBF ₄ / ethylene carbonate, propylene carbonate, and γ-butyrolactone, and a 6 cm × 50 cm negative electrode made of carbon are laminated. It was folded in five. 7cm ×
13cm x 0.5cm polyethylene terephthalate /
Aluminum / Aromatic polyamide / Polyethylene (PE
(T / Al / PPTA / PE) (made by Asahi Kasei Polyflex Corp.). The thickness of each layer is 12 μm, 9 μm, 25 μm, and 60 μm, respectively.
m. As the aromatic polyamide film, Aramica (trade name, manufactured by Asahi Kasei Corporation) 25 μm was used. The tensile modulus was measured using a constant-speed elongation type elongation meter (DSS-500, manufactured by Shimadzu Corporation) and found to be 1500 kg / mm ² . Further, the compression modulus was 200 kg / mm ² . PET / Al and Al / PPTA were bonded by dry lamination. The mouth of the PET / Al / PPTA / PE laminated film bag was sealed by heating at 120 ° C. for 6 seconds. Similarly, five batteries were prepared. Battery charge / discharge characteristics measurement device (HJ-101S manufactured by Hokuto Denko Co., Ltd.)
When charging and discharging were performed using M6), no short circuit occurred in any of the five batteries, and the discharge capacity of the obtained batteries was 900 mAh, and no reduction in discharge capacity due to the short circuit was observed.

Example 2 Instead of the gel electrolyte made of polyvinylidene fluoride used in Example 1, crosslinked polyacrylonitrile was added to 1.5 M LiBF ₄ / ethylene carbonate, propylene carbonate, and γ-butyrolactone in a ratio of 1: 1: 2 Using a gel electrolyte swelling the mixed solution,
A five-folded laminate was obtained in the same manner as in Example 1. The laminate was stretched to 7 cm × 13 cm × 0.5 cm stretched nylon / aluminum / aramid / polypropylene (ON / A
1 / PPTA / CPP) (Asahi Kasei Polyflex Corp.)
) Was placed in a bag made of a laminated film of The thickness of each layer is 15 μm, 9 μm, 25 μm, and 40 μm, respectively. The same film as in Example 1 was used for PPTA. O
N / Al / PPTA / CPP laminated film bag mouth
It was sealed by heating at 140 ° C. for 6 seconds. Similarly, five batteries were prepared. When charging and discharging were performed in the same manner as in Example 1, no short circuit occurred in any of the five batteries, and the discharge capacity of the obtained batteries was 900 mAh, and no decrease in the discharge capacity due to the short circuit was observed.

Example 3 A laminate folded in five was obtained in the same manner as in Example 1. The laminate is placed in a bag of a 7 cm × 13 cm × 0.5 cm laminated film of polyethylene terephthalate / polyethylene / aluminum / polyethylene terephthalate / polypropylene (PET / PE / Al / PET / PP) (manufactured by Asahi Kasei Polyflex Corp.). I put it. The thickness of each layer is 12 μm, 20 μm, 25
μm, 12 μm, and 40 μm. When the tensile elastic modulus of the PET film was measured using a constant-speed elongation type elongation meter (DSS-500 manufactured by Shimadzu Corporation), it was 400 kg /
mm ² . The mouth of the PET / PE / Al / PET / PP laminated film bag was sealed by heating at 140 ° C. for 6 seconds. Similarly, five batteries were prepared. When charging and discharging were performed in the same manner as in Example 1, no short circuit occurred in any of the five batteries, and the discharge capacity of the obtained batteries was 900 mAh, and no decrease in the discharge capacity due to the short circuit was observed.

Example 4 In the same manner as in Example 1, a five-folded laminate was obtained. A 7 cm × 13 cm × 0.5 cm polyethylene terephthalate / aluminum / glass fiber-containing nylon / polypropylene (PET / Al / Ny)
/ PP) (manufactured by Asahi Kasei Polyflex Corp.). The thickness of each layer is 12
μm, 9 μm, 30 μm, and 40 μm. As the glass fiber-containing nylon, a film cast from 33% glass fiber-containing Leona (trade name, manufactured by Asahi Kasei Corporation) was used. Constant-speed elongation elongation meter (DSS-500, manufactured by Shimadzu Corporation)
The tensile modulus was measured using
mm ² . The mouth of the PET / Al / Ny / CPP laminated film bag was sealed by heating at 140 ° C. for 6 seconds. Similarly, five batteries were prepared. When charging and discharging were performed in the same manner as in Example 1, no short circuit occurred in any of the five batteries, and the obtained battery had a discharge capacity of 900 mAh.
No decrease in the discharge capacity due to the short circuit was observed.

Comparative Example 1 Five batteries were made in the same manner as in Example 1 using a polyethylene terephthalate / aluminum / polyethylene (PET / Al / PE) laminated film.
Four of the five batteries had zero potential between the terminals and were charged, but the potential did not rise. The tensile modulus of the polyethylene film was 90 kg / mm ² and the compressive modulus was 20 kg / mm ² .

Comparative Example 2 Five batteries were produced in the same manner as in Example 1 using a laminated film of polyethylene terephthalate / aluminum / biaxially oriented polypropylene / unoriented polypropylene (PET / Al / BOPP / CPP). The thickness of each layer of the laminated film is 12 μm and 9 μm, respectively.
m, 25 μm, and 30 μm. In three of the five, the potential between the terminals was zero, and charging was performed, but the potential did not increase. The biaxially stretched polypropylene film has a tensile modulus of 250 kg / mm ² and a compressive modulus of 48 k.
g / mm ² .

According to the present invention, a short circuit between terminals via a metal layer is prevented,
It has become possible to provide a battery with high safety and stability.

Claims (4)

[Claims] A laminated film having at least a metal layer and a heat-fusible resin layer has a tensile modulus of 300 kg.
/ Mm ² or more and / or compression modulus of 50 kg / m
A laminated film for a battery package, wherein a resin layer having a thickness of at least m ² is provided between the metal layer and the heat-fusible resin layer. 2. A polyester resin layer having a tensile modulus of 400 kg / mm ² or more and / or a compressive modulus of 50 kg / mm ² or more, wherein the resin layer is provided between the metal layer and the heat-fusible resin layer. The laminated film for a battery exterior body according to claim 1, wherein: 3. An aromatic polyamide resin having a tensile modulus of at least 300 kg / mm ² and / or a compressive modulus of at least 50 kg / mm ² , wherein the resin layer is provided between the metal layer and the heat-fusible resin layer. The laminated film for a battery package according to claim 1, which is a resin layer. 4. A battery packaged with the laminated film for a battery package according to claim 1, 2 or 3.