KR20170142624A - Aluminium pouch film for secondary battery and the manufacturing method of the same - Google Patents

Abstract

The present invention provides an aluminum pouch film for a secondary battery which includes: an inner resin layer; an aluminum layer formed on the inner resin layer; an outer resin layer formed on the aluminum layer; a PET layer formed on the outer resin layer; and a polyurethane-based or polyolefin-based adhesive layer including heat radiation fillers between the inner resign layer and the aluminum layer, between the aluminum layer and the outer resin layer, and between the outer resin layer and the PET layer, respectively, and a manufacturing method thereof. Accordingly, the present invention can obtain an efficient heat radiation property.

Description

Technical Field [0001] The present invention relates to an aluminum pouch film for a secondary battery, and a method for manufacturing the aluminum pouch film.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum pouch film for a secondary battery and a method of manufacturing the same. More particularly, the present invention relates to the production of an aluminum pouch film for a secondary battery having an efficient heat dissipation property as compared with a conventional pouch film for a secondary battery.

The secondary battery generally refers to a lithium secondary battery, and is a battery used for an electric vehicle including a portable terminal device such as a notebook, a smart phone, a tablet PC, a video camera, a hybrid vehicle, a smart grid for energy storage, At the same time, research is underway to overcome various environmental factors such as harsh thermal environment and mechanical impact.

Unlike a can-type packaging material used in conventional packaging materials, a packaging material used for such a lithium battery has a multilayer structure (for example, an inner resin layer, an aluminum layer, and an outer layer A resin layer) is used as a pouch for a secondary battery.

A commonly used secondary battery pouch film is a polyolefin such as polyethylene (PE), casted polypropylene (cPP) or polypropylene (PP), which has a heat sealability and is sequential in sealing performance An inner resin layer composed of these copolymers, a base material for maintaining mechanical strength, and an aluminum layer serving as a barrier layer of water and oxygen. In order to protect the battery cell from external shock, a polyethylene terephthalate , PET (polyethylene terephthalate) resin, polyethylene naphthalate (PEN), nylon resin or liquid crystal polymer (LCP) constitutes an outer resin layer.

In particular, in the case of mid-sized batteries such as batteries for electric vehicles and batteries for energy storage devices (ESS), the outer resin layer is formed in a two-layer structure to protect the battery from external impact or environment. Two-layer external resin A material similar to that of the above-mentioned one-layer external resin can also be used.

The multilayer structure of such a polymer film has a low thermal conductivity. Particularly, in the case of a pouch film for a lithium secondary battery used for electric vehicles, the cell itself is designed to serve as a heat sink in order to efficiently cool the heat generation of the battery during driving of the vehicle. However, the aluminum pouch film used for automobile battery has a problem that it is not effective for a heat dissipation structure because a polymer film and an adhesive are overlapped with each other while forming a multilayer film.

Patent Document 1: KR 10-2001-7010231

It is an object of the present invention to provide an aluminum pouch film for a secondary battery which can be used in a middle- or large-sized battery of an electric vehicle or the like by using a thermally conductive filler to efficiently dissipate heat.

The present invention relates to a method for manufacturing a semiconductor device, which comprises an inner resin layer, an aluminum layer formed on the inner resin layer, a first outer resin layer formed on the aluminum layer, and a second outer resin layer formed on the first outer resin layer, Based or polyolefin-based adhesive layer including a heat-radiating filler between the layer and the aluminum layer, between the aluminum layer and the first outer resin layer, and between the first outer resin layer and the second outer resin layer, respectively And an aluminum pouch film for a secondary battery.

B) applying an adhesive to both sides of the aluminum layer; c) forming a first outer resin layer and an inner resin layer on the adhesive; d) Applying an adhesive on the first outer resin layer, and e) forming a second outer resin layer on the first outer resin layer. The present invention also provides a method of manufacturing an aluminum pouch film for a secondary battery, do.

The use of the aluminum pouch film for a secondary battery according to the present invention has an advantage that it can be used for a middle- or large-sized battery of an electric automobile or the like because it has an efficient heat dissipation characteristic while maintaining insulating property and electrolytic solution property.

1 shows a structure of an aluminum pouch film for a secondary battery according to a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1, the aluminum pouch film for a secondary battery of the present invention comprises an inner resin layer 4, an aluminum layer 3 formed on the inner resin layer, a first outer resin layer 2 formed on the aluminum layer, And a second external resin layer (1) formed on the first external resin layer, wherein the first external resin layer and the second external resin layer are disposed between the inner resin layer and the aluminum layer, between the aluminum layer and the first outer resin layer, And a polyurethane-based or polyolefin-based adhesive layer (5, 6, 7) each including a heat-radiating filler between the outer resin layers.

Hereinafter, each constitution of the aluminum pouch for a secondary battery of the present invention will be described in detail.

Aluminum layer

In the aluminum pouch film for a secondary battery of the present invention, the aluminum layer (3) can be preferably a soft aluminum foil, more preferably, an aluminum foil containing iron Use a foil. The iron-containing aluminum foil may contain 0.1 to 9.0% by weight, more preferably 0.5 to 2.0% by weight, based on 100% by weight of the total aluminum foil. When the content of iron in the aluminum foil is less than 0.1 wt%, the ductility of the aluminum layer is deteriorated. When the content of aluminum is more than 9.0 wt%, the formability is deteriorated. The aluminum foil to be used for the aluminum layer can be etched or degreased on its surface in order to improve the adhesion with the internal resin layer, but it can be omitted for the purpose of reducing the processing speed. The thickness of the aluminum layer is preferably 10 to 100 占 퐉, more preferably 30 to 50 占 퐉 in consideration of workability, oxygen and moisture barrier properties. If the above range is not satisfied, if it is less than 10 탆, it tears easily, and the electrolytic resistance and insulating property are deteriorated, and if it exceeds 100 탆, the moldability is deteriorated.

The first outer resin layer

In the aluminum pouch film for a secondary battery of the present invention, the first outer resin layer (2) may be a polyester such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymer polyester, polycarbonate It is preferable to use a resin or a nylon film, and it is particularly preferable to use a nylon film. The nylon film is excellent in heat resistance, cold resistance and mechanical strength as well as excellent in rupture strength, pinhole property, gas barrier property and the like, and thus is mainly used as packaging film. Specific examples of the nylon film include polyamide resins such as nylon 6, nylon 66, copolymers of nylon 6 and nylon 66, nylon 610, and polymetaxylene imine amide (MXD6). When the first external resin layer is laminated, the thickness of the laminated first external resin layer is preferably 10 to 30 μm or more, particularly preferably 12 to 25 μm. If it is less than 10 탆, the physical property tends to be lost and tear easily. If it is more than 30 탆, the moldability is deteriorated.

The second outer resin layer

In the aluminum pouch film for a secondary battery of the present invention, the second outer resin layer (1) may be formed on the first outer resin layer (2) to protect the battery from external impact and environment. The second external resin layer can be used without any particular limitation as long as it is commonly used as an exterior material. The second outer resin layer may be formed by using a polyester resin such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymerized polyester, polycarbonate or the like as the first external resin layer Or a nylon film is preferably used, and it is particularly preferable to use a PET film. The thickness of the polymer layer of the second external resin layer is preferably 5 to 30 占 퐉, more preferably 10 to 20 占 퐉 in consideration of moldability, insulation and the like. If the above-mentioned range is not satisfied, there is a possibility that moldability and insulation become poor.

The inner resin layer

In the aluminum pouch film for a secondary battery of the present invention, the inner resin layer 4 may be a polyolefin such as polyethylene (PE) or polypropylene (PP), or a copolymer thereof. When the polymer layer is made of a polyolefin such as PE or PP or a copolymer thereof, it is preferable to have good physical properties as a packaging material for a secondary battery such as heat-sealing property, moisture-proofing property and heat resistance, Do. The thickness of the polymer layer of the internal resin layer is preferably 40 to 100 占 퐉, more preferably 70 to 90 占 퐉 in consideration of moldability, insulation, electrolyte resistance, and the like. If the above range is not satisfied, there may arise a problem that moldability, insulation, and electrolytic solution resistance are deteriorated.

Adhesive layer

In the aluminum pouch film for a secondary battery according to the present invention, it is preferable that the distance between the inner resin layer (4) and the aluminum layer (3), between the aluminum layer (3) and the first outer resin layer (2) (5, 6, 7) each including a heat-radiating filler between the first external resin layer (2) and the second external resin layer (1). 1, an adhesive layer between the inner resin layer 4 and the aluminum layer 3 is divided into a third adhesive layer 7, the aluminum layer 3 and the first outer resin layer 2 can be divided into a second adhesive layer 6 and an adhesive layer between the first outer resin layer 2 and the second outer resin layer 1 as the first adhesive layer 5. [ It is preferable that the composition of each adhesive layer is a polyurethane system for the first adhesive layer and the second adhesive layer, and a polyolefin-based adhesive for the third adhesive layer.

The adhesive layers 5, 6, and 7 may include a polyurethane-based or polyolefin-based adhesive as well as a heat-radiating filler for releasing heat generated inside the battery to the outside. The heat-radiating filler may be a ceramic filler including graphite, carbon fiber, carbon black, carbon filler and boron nitride heat-radiating filler having high thermal conductivity; And a metal-based filler. In particular, graphite (100 ~ 400W / mk) and boron nitride (250 ~ 300W / mk) have much higher thermal conductivity than amorphous polymers (about 0.11W / mk) , Which is higher in thermal conductivity than aluminum (204 W / mk), which is a metal. Therefore, by appropriately dispersing these heat-radiating fillers between the polymers of the adhesive, it becomes possible to realize a thermally conductive polymer composite material. Particularly, carbon-based fillers such as graphite, carbon fiber and carbon black can be most suitably used as heat-radiating fillers because of their high thermal conductivity, low thermal expansion coefficient and light weight. Boron nitride can also be preferably used as a heat-radiating material because of its excellent electrical insulation and high thermal conductivity.

In addition, the thermal conductivity of the heat-radiating filler is greatly influenced not only by the material of the filler but also by the size of the filler. For example, when nanoparticles are used in a micropiller of the same material, the thermal conductivity increases by about 200% or more. Therefore, the size of the heat-radiating filler is preferably 0.01 to 3 탆, more preferably 0.01 to 1 탆.

The shape of the heat-radiating filler is not particularly limited, but may be preferably a fiber type, a plate type, a spherical type or a cubic type.

The heat-radiating filler of the third adhesive layer may be one which has been subjected to an acid-resistance-treatment treatment so as to impart acid resistance. The heat-radiating filler exhibits properties of resistance to electrolysis and corrosion due to the acid-rust-proofing treatment, and has an advantage that the adhesive force can be maintained in the electrolytic solution.

The amount of the heat-radiating filler may be varied according to the needs of the user. However, since the high content of the filler can increase the thermal conductivity, the low content of the polymer lowers the physical properties. Therefore, the amount of the heat-radiating filler may be 1 to 10 wt% based on the total weight of the adhesive layer. When the content is less than 1% by weight, the heat radiation effect is insignificant, and when it is more than 30% by weight, the adhesive strength is weakened. The thickness of the adhesive layer may be 1 to 5 占 퐉 in consideration of adhesiveness, thickness after molding, and the like. When the thickness is less than 1 탆, sufficient adhesiveness is not exhibited. If the thickness is more than 5 탆, cracks may be generated in the molding process. In the aluminum pouch film for a secondary battery of the present invention, the use of the heat dissipation filler as described above can improve the thermal conductivity by 150% or more.

Next, each production step of the aluminum pouch film for a secondary battery of the present invention will be described in detail.

The aluminum pouch film for a secondary battery according to the present invention may further comprise: a) preparing an aluminum layer; b) applying an adhesive to both surfaces of the aluminum layer; c) forming a first outer resin layer and an inner resin layer D) applying an adhesive on the first outer resin layer, and e) forming a second outer resin layer on the first outer resin layer.

a) The aluminum layer  Steps to prepare

As the aluminum layer of the aluminum pouch film for a secondary battery of the present invention, preferably, a soft aluminum foil can be used, and more preferably, an aluminum foil containing iron is used in order to further impart flexibility during cold filling and cold forming There is a number. In the aluminum foil containing the iron, the content of iron may include preferably 0.1 to 9.0% by weight, more preferably 0.5 to 2.0% by weight, based on 100% by weight of the total aluminum foil have. If the content of iron is less than 0.1% by weight based on 100% by weight of the total aluminum foil, ductility of the aluminum layer is deteriorated. If the content of aluminum exceeds 9.0% by weight, moldability is deteriorated.

The thickness of the aluminum layer is preferably 10 to 100 占 퐉, more preferably 30 to 50 占 퐉 in consideration of the hole filling property, workability, oxygen and moisture barrier properties. If the above range is not satisfied, if it is less than 10 탆, it easily tears and deteriorates the electrolytic resistance and insulation property, and if it exceeds 100 탆, the moldability becomes poor.

As the aluminum foil used for the aluminum layer, an untreated aluminum foil may be used, but it is more preferable to use an aluminum foil subjected to the degreasing treatment in order to impart electrolytic solution resistance and electrolyte resistance. Examples of the degreasing treatment method include wet type and dry type treatment methods.

Examples of the wet type degreasing include sapphire and alkali degreasing. The acid used for acid degreasing includes, for example, inorganic acids such as sulfuric acid, acetic acid, phosphoric acid, and hydrofluoric acid. These acids may be used singly or in combination. Further, in order to improve the etching effect of the aluminum foil, various metal salts may be blended if necessary. The alkali used for alkali degreasing includes, for example, strong alkali such as sodium hydroxide, and a weak alkaline compound or a surfactant may be blended together.

An example of a dry type degreasing treatment is a step of annealing aluminum at a high temperature, and a degreasing treatment is performed.

b) applying an adhesive to both sides of the aluminum layer

Polyurethane-based and polyolefin-based adhesives are applied to both surfaces of the aluminum layer prepared as described above to form adhesive layers 6 and 7.

c) forming a first outer resin layer and an inner resin layer on the adhesive

A first outer resin layer (2) and an inner resin layer (4) are formed on an adhesive formed on both surfaces of the aluminum layer. At this time, there is no particular limitation on the method of forming the resin layer, but lamination can be carried out by lamination using a dry lamination method or an extrusion lamination method.

d) applying an adhesive onto the first outer resin layer

An adhesive is applied again on the first external resin layer 2 prepared as described above to form the adhesive layer 5. [

e) forming a second outer resin layer on the first outer resin layer

When the second outer resin layer 1 is formed on the first outer resin layer 2, there is no particular limitation, but preferably the second outer resin layer 1 is laminated on the adhesive applied by lamination using the dry lamination method ) Can be formed.

The configuration of the second outer resin layer 1 and the first outer resin layer 2 is the same as that of the aluminum pouch film for a secondary battery described above.

Further, in the present invention, the order of steps b) to e) may be changed except that step d) is followed by step e).

A specific example of manufacturing an aluminum pouch film for a secondary battery will be described below.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the embodiments of the present invention described below are illustrative only and the scope of the present invention is not limited to these embodiments. The scope of the present invention is indicated in the claims, and moreover, includes all changes within the meaning and range of equivalency of the claims. In the following Examples and Comparative Examples, "%" and "part" representing the content are on a mass basis unless otherwise specified.

Example  And Comparative Example  : Manufacture of aluminum pouch film

The aluminum pouch film for a secondary battery of the present invention will be described in more detail with reference to Examples.

[Example 1]

An aluminum foil (made of the same aluminum) having a thickness of 40 mu m was prepared, and both surfaces of the aluminum were chemically treated using a chromate surface treatment (admission chemical) dilution solution. A nylon film (Kolon) having a thickness of 25 μm was used as a first outer resin layer, and a PET film (PET film having a thickness of 15 μm) Kolon) was used as the second outer resin layer. The first adhesive layer and the second adhesive layer were prepared by adding 10% by weight of a boron nitride cooling filler (product of 3M) having an average size of 0.5 탆 and a plate-like shape as a heat-radiating filler in a polyurethane-based adhesive . As the third adhesive layer, the above-mentioned heat-radiating filler is applied to a polyolefin-based adhesive (Lotte Chemical) using a chromate surface-treated dilute solution, and then 10 wt% of the solution is used.

The second and third adhesive layers are applied to the aluminum layer to a thickness of 3 mu m, and the first external resin layer and the internal resin layer are laminated by dry lamination.

A first adhesive layer is applied to the first external resin layer to a thickness of 3 mu m to laminate the second external resin layer

[Example 2]

An aluminum pouch film was prepared in the same manner as in Example 1, except that the heat-radiating filler was not subjected to chromate-acid-fastening treatment.

[Comparative Example 1]

An aluminum pouch film was produced in the same manner as in Example 1, except that a polyurethane-based adhesive and a polyolefin-based adhesive agent not containing a heat-radiating filler were used for the adhesive layer.

[Comparative Example 2]

An aluminum pouch film was prepared in the same manner as in Example 1, except that the heat-radiating filler was used in an amount of 0.5 wt% based on the adhesive.

[Comparative Example 3]

An aluminum pouch film was prepared in the same manner as in Example 1 except that the heat-radiating filler was used in an amount of 40 wt% based on the adhesive.

[Comparative Example 4]

An aluminum pouch film was prepared in the same manner as in Example 1, except that the heat-radiating filler having an average size of 5 mu m was used.

Experimental Example

Thermal conductivity evaluation

The thermal conductivity of the aluminum pouch film for secondary batteries according to Examples 1 and 2 and Comparative Examples 1 to 4 was evaluated using a thermal conductivity measuring device. (Temperature 25 ° C, W / mK)

Thermal conductivity Example 1 52 Example 2 51 Comparative Example 1 35 Comparative Example 2 41 Comparative Example 3 58 Comparative Example 4 48

As shown in Table 1, it was found that the aluminum pouch film of Example 1 and Comparative Examples 1 to 4 had a higher thermal conductivity according to the use of the heat-radiating filler.

Electrolytic solution resistance  evaluation

The aluminum pouch films for secondary batteries according to Examples 1 and 2 and Comparative Examples 1 to 4 were cut into 1.5 cm x 12 cm pieces, respectively, and the test pieces were sealed with a LiPF ₆ electrolyte solution (manufactured by RICHM Co., Ltd.) The film was taken every 7 days, and the film was peeled off every day. The peeling of the film was visually observed to evaluate the electrolyte resistance.

0 days 1 day 2 days 3 days 4 days 5 days 6 days 7 days Example 1 ○ ○ ○ ○ ○ ○ ○ ○ Example 2 ○ ○ ○ ○ ○ ○ △ △ Comparative Example 1 ○ ○ ○ ○ ○ ○ △ △ Comparative Example 2 ○ ○ ○ △ △ △ × × Comparative Example 3 △ △ △ △ × × × × Comparative Example 4 ○ ○ △ △ △ × × ×

○: No peeling occurred

DELTA: Partial peeling occurred

×: Peeling occurred

As shown in Table 2, it was found that the aluminum pouch films of Examples 1 and 2 and Comparative Examples 1 to 4 had no change in adhesive force even when a heat radiating filler of 30% by weight or less was used in the adhesive layer, It was found that the use of the heat-radiating filler was excellent in the electrolytic resistance.

Claims (5)

Internal resin layer;
An aluminum layer formed on the internal resin layer;
A first outer resin layer formed on the aluminum layer;
A second external resin layer formed on the first external resin layer; And
Based or polyolefin-based adhesive layer including a heat-radiating filler between the inner resin layer and the aluminum layer, between the aluminum layer and the first outer resin layer, and between the first outer resin layer and the second outer resin layer, Wherein the aluminum pouch film has a thickness of at least 20 mm. The method according to claim 1,
The heat-radiating filler may be a ceramic filler including graphite, carbon fiber, carbon black, carbon filler, and boron nitride heat radiating filler; And metallic fillers, and the shape of the heat-radiating pillar is at least one selected from the group consisting of a fibrous, plate-like, spherical or cubic type. The method according to claim 1,
Wherein the heat-radiating filler is at least one selected from the group consisting of 0.01 to 3 占 퐉. The method according to claim 1,
Wherein the heat-radiating filler is subjected to an acid-resistance-imparting treatment. The method according to claim 1,
Wherein the heat-radiating filler is contained in an amount of 1 to 30 wt% based on the total weight of the adhesive layer.

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