KR20170142625A - Aluminium pouch film for secondary battery and the manufacturing method of the same - Google Patents

Abstract

The present invention relates to an aluminum pouch film for a secondary battery. The aluminum pouch film comprises: an aluminum layer, an outer resin layer formed on one side of the aluminum layer, an inner resin layer formed on the other side of the aluminum layer, a first adhesive layer formed between the aluminum layer and an external resin layer, and a second adhesive layer formed between the aluminum layer and the inner resin layer. A plasma treatment layer and a chemical treatment layer are sequentially formed on at least one surface of the aluminum layer. It is possible to prevent cracks and interfacial peeling of a contact layer inside a pouch.

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.

The present invention relates to an aluminum pouch film for a secondary battery, and more particularly, to an aluminum pouch film for a secondary battery, and more particularly to an aluminum pouch film for a secondary battery, which improves adhesion between an outer resin layer or an inner resin layer and an aluminum surface through plasma treatment, To an aluminum pouch film for a secondary battery capable of preventing corrosion.

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 computer, 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 an adhesive layer made of these copolymers, a base material for maintaining mechanical strength, and an aluminum layer serving as a metal foil layer serving as a barrier layer of water and oxygen. In order to protect the battery cell from external impact, polyethylene terephthalate A multilayer film structure in which a functional polymer film such as polyethylene terephthalate (PET) resin, polyethylene naphthalate (PEN), nylon resin or liquid crystal polymer (LCP) forms an outer resin layer Consists of.

The pouch type secondary battery has flexibility in shape and has an advantage that a secondary battery of the same capacity can be realized with a smaller volume and mass than a can type. Unlike the can type, however, the pouch type uses a soft pouch as a container, which can be damaged in various processes for various reasons. For example, during the process of housing the electrode assembly in the pouch, protrusions such as electrode tabs and electrode leads may damage the internal PP and cPP layers of the pouch, Layer is exposed, and in this case, a side reaction occurs due to reactivity with the electrolyte solution. The aluminum layer exposed to the electrolytic solution may be corroded by causing a chemical reaction with oxygen or moisture, which is penetrated or diffused into the inside of the battery, and a corrosive gas is generated, thereby causing a swelling phenomenon There is a problem that will occur. More specifically, LiPF6 reacts with water and oxygen to produce hydrofluoric acid (HF), which is a corrosive gas. Such hydrofluoric acid may react with aluminum to cause a rapid exothermic reaction. When the aluminum is adsorbed on the aluminum surface due to the secondary reaction and penetrates into the inside of the structure, the brittleness of the structure is increased and cracks of the pouch film occur even in a fine impact. The reaction between lithium and the atmosphere may cause ignition. Therefore, in order to prevent contact with aluminum even if corrosive hydrofluoric acid is generated as described above, various aluminum surface modification techniques have been researched.

As a most effective aluminum surface modification method, a method of performing a conversion treatment on an aluminum foil as disclosed in Korean Patent Publication No. 10-2001-7010231 is known, and an example of a conversion treatment is a chromate treatment. In particular, there are many chromate treatment methods such as a coating type chromate treatment and a chromate treatment by a dipping method. However, in the chromate treatment as described above, materials using hexavalent chromium as a main component have good functions. However, in terms of environmental aspects, it is necessary to use Cd, Pb and Hg, which are toxic environmental pollutants harmful to human and living organisms, It is one of the four heavy metals that have problems to be removed, which is an undesirable material. In addition, due to worldwide strong regulations on the use of hexavalent chromium, economic factors such as its manufacture, use, processing and disposal have been continuously increasing, and research and development has been made on alternative materials and alternative processes. As a result of research and development, it has been generalized to perform chromate treatment using a trivalent chromium that is relatively safe to an organism as compared to hexavalent chromium. However, since the function equivalent to hexavalent chromium is difficult to obtain and chromium used as a heavy metal is used, There is a problem that the treatment is not desirable as an environmental aspect. In addition, the treating agent used in the chemical conversion treatment often accompanies the corrosion of the coating device, which not only suffers from the limitations of the coating device but also tends to lead to deterioration of the working environment. In order to further improve the adhesion of the treating agent, a step of immersing the substrate with acid or alkali and performing degreasing and etching must be provided during the manufacturing process. However, the cost of these steps is high, It is necessary to find a way to maintain the performance as a secondary battery packaging material while omitting the aluminum surface treatment process.

Patent Document 1: KR 10-2001-7010231

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and it is an object of the present invention to provide a method of manufacturing an aluminum pouch in which cracking of an adhesive layer inside the pouch is suppressed even when a battery is exposed to physical, And to provide a method for manufacturing an aluminum pouch film for a secondary battery, which is excellent in moldability, insulation and electrolytic solution resistance.

The present invention provides a method of manufacturing a semiconductor device, comprising the steps of: forming an aluminum layer, an outer resin layer formed on one side of the aluminum layer, an inner resin layer formed on the other side of the aluminum layer, a first adhesive layer formed between the aluminum layer and the outer resin layer, And a second adhesive layer formed on at least one surface of the aluminum layer, wherein the plasma treatment layer and the converted layer are sequentially formed on at least one surface of the aluminum layer.

B) forming a bonding layer on both surfaces of the aluminum layer; d) forming a bonding layer on both surfaces of the aluminum layer; d) forming a bonding layer on both surfaces of the aluminum layer; d) ) Forming an outer resin layer and an inner resin layer on both sides of the aluminum layer. The present invention also provides a method of manufacturing an aluminum pouch film for a secondary battery.

When the aluminum pouch film for a secondary battery according to the present invention is used, it is possible to prevent cracking of the adhesive layer inside the pouch and interface separation of the resin layer, even when exposed to physical, chemical impact or electrical stress. Therefore, it is possible to reduce the risk of explosion of the battery due to the generation of gas in the inside of the battery or the explosion due to the high temperature.

In addition, when the uniformity and corrosion resistance of the chemical conversion treatment layer are increased and used in a sealing material for packing a secondary battery, it is possible to improve the electrolyte resistance, which is one of the most important characteristics, and to prevent corrosion of the inner layer by the electrolyte.

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

Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

The aluminum pouch film for a secondary battery of the present invention comprises an aluminum layer, an outer resin layer formed on one side of the aluminum layer, an inner resin layer formed on the other side of the aluminum layer, A first adhesive layer, and a second adhesive layer formed between the aluminum layer and the inner resin layer, wherein the plasma treatment layer and the chemical treatment layer are formed in sequence on at least one surface of the aluminum layer.

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 (2) can preferably be 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 mass, more preferably 0.5 to 2.0% by mass, based on 100% by mass of the total aluminum foil. When the content of iron in the aluminum foil is less than 0.1 mass%, the ductility of the aluminum layer is deteriorated. When the content of aluminum exceeds 9.0 mass%, 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 80 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. If it exceeds 80 탆, the moldability is deteriorated.

The outer resin layer

In the aluminum pouch film for a secondary battery of the present invention, the outer resin layer (1) corresponds to a portion in direct contact with hardware, and therefore is preferably a resin having insulating properties. Therefore, as the resin used as the external resin layer, a polyester resin such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymer polyester and polycarbonate is used, or a nylon film is used , 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 external resin layer is laminated, the thickness of the laminated external resin layer is preferably 15 to 80 탆 or more, particularly preferably 20 to 50 탆. In the case where the above range is not satisfied, when the thickness is less than 15 탆, the physical properties are deteriorated and easily torn, and when it exceeds 80 탆, the moldability is deteriorated.

The inner resin layer

In the aluminum pouch film for a secondary battery of the present invention, as the internal resin layer 3, a polyolefin such as polyethylene (PE) or polypropylene (PP) or a copolymer thereof may be used. When the polymer layer is made of a polyolefin such as PE or PP or a copolymer thereof, the polymer layer preferably has good physical properties such as good heat-sealability, moisture-proofing property, heat resistance and the like as a packaging material for a secondary battery, Do. The thickness of the polymer layer of the internal resin layer is preferably 15 to 80 占 퐉, more preferably 20 to 50 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.

The first adhesive layer and the second adhesive layer

The aluminum pouch film for a secondary battery of the present invention is characterized in that the aluminum layer 2 and the external resin layer 1 and the adhesive layers 4 and 5 are sandwiched between the aluminum layer 2 and the internal resin layer 4 And the adhesive layer on the side of the outer resin layer is used as the first adhesive layer 4 and the adhesive layer on the side of the inner resin layer is used as the second adhesive layer 5. [

As the adhesive constituting the first adhesive layer 4 and the second adhesive layer 5, polyurethane, acid-modified polyolefin resin, epoxy, or the like can be used, and a urethane-based adhesive having a metal adhesive layer can be preferably used.

It is preferable that the first adhesive layer 4 and the second adhesive layer 5 have a thickness of 1 to 5 占 퐉 in view of the adhesion between the resin layers 1 and 3 and the aluminum layer 2 and the thickness after molding. In the case where the above range is not satisfied, when the thickness is less than 1 탆, the tackiness is poor, and when it is more than 5 탆, cracks may occur.

plasma Treatment layer

In the aluminum pouch film for a secondary battery of the present invention, the plasma treatment layer (6, 6 ') is a layer formed by performing plasma treatment on the aluminum layer (2). The plasma treatment layer may be formed on either one side or both sides of the aluminum layer 2 if necessary, and when the plasma treatment layer is formed on both sides, the effect of the plasma treatment can be maximized. Since the hydrophilic functional group is formed by the formation of the treatment layer, the surface tension of the aluminum layer is controlled so that when the chemical conversion treatment layer 5 or 5 'described later reacts with the adhesive layer 4 or 5, have. At this time, in order to obtain the effect of the plasma treatment of the present invention, the surface tension of the plasma treatment layer is preferably 82 Dyne or more. In the case of a surface tension of less than 82 Dyen which does not satisfy the above range, there is no effect by the plasma treatment, or there is a problem that the effect of decomposition of the molecules of the aluminum surface layer due to over energy may occur.

Mars Treatment layer

In the aluminum pouch film for a secondary battery of the present invention, the chemical conversion layers (7, 7 ') are formed by chemical conversion treatment on aluminum to form an acid resistant film (chemical conversion layer). The chemical conversion treatment layer can prevent interface delamination between the aluminum layer and the resin layer and is capable of preventing dissolution and corrosion of the aluminum surface due to hydrogen fluoride generated in the reaction of the electrolyte of the polymer battery with moisture, It is possible to prevent the aluminum oxide from dissolving and corroding.

The chemical treatment may be a phosphate, a chromate, a fluoride, a triazinethiol compound, or the like, and preferably a phosphate chromate treatment using trivalent chromium phosphate as a main component.

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

The aluminum pouch for a secondary battery of the present invention may further comprise: a) subjecting the aluminum layer to a plasma treatment on one or both surfaces thereof, b) performing a chemical treatment on the plasma treatment layer of the aluminum layer, c) forming an adhesive layer on both surfaces of the aluminum layer And d) forming an outer resin layer and an inner resin layer on both sides of the aluminum layer.

a) On one or both sides of the aluminum layer plasma  Processing step

In the step a), the plasma treatment is performed on one or both surfaces of the aluminum layer 2 to form the plasma treatment layers 6 and 6 '. The plasma treatment is not particularly limited as long as it is a plasma treatment method used in the industry, but generally refers to a plasma treatment method that proceeds under atmospheric pressure. The aluminum layer and the plasma nozzle can be processed under continuous process conditions of 10 to 150 m / min, with an output of 0.8 to 3.5 KW, with a spacing of 10 to 150 mm. However, in the case of an output of less than 0.8 KW, the treatment effect can not be expected, or in the output of 3.5 KW or more, surface energy loss due to molecular decomposition may occur, and the economical efficiency may be lowered due to excessive energy consumption.

Also, in the step of the plasma treatment layer, the oxide film on the aluminum surface and the surface of the aluminum surface can be eco-friendly because of the dry cleaning effect.

The power control of the plasma treatment is not particularly limited as long as it uses a method used in the art, but it is possible to optimize the treatment range through structural changes if necessary. For example, a plasma processing can be performed by connecting multiple 1 KW heads.

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 from 0.1 to 9.0 mass%, more preferably from 0.5 to 2.0 mass%, based on 100 mass% of the entire aluminum foil have. If the content of iron is less than 0.1% by mass based on 100% by mass of the total aluminum foil, ductility of the aluminum layer is deteriorated. If the content of aluminum exceeds 9.0% by mass, moldability is deteriorated.

The thickness of the aluminum layer is preferably 10 to 100 占 퐉, more preferably 30 to 50 占 퐉, in view 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 method of performing a degreasing treatment in a step of annealing aluminum at a high temperature.

b) plasma Treatment layer  A step of chemical conversion treatment

In the step b), chemical conversion treatment is performed on the plasma treatment layers 6 and 6 'formed on one surface or both surfaces of the aluminum layer 2 to form chemical conversion layers 7 and 7'. The chemical conversion treatment is not particularly limited as long as it is a chemical conversion treatment method used in the art, but preferably a phosphate, chromate, fluoride, triazine thiol compound or the like can be used, and more preferably, chromate treatment can be used.

The contents of the aluminum layer 2 and the chemical conversion layers 7 and 7 'are as shown in the respective constitutions of the aluminum pouches previously described.

c) forming an adhesive layer on both sides of the aluminum layer

In step c), the adhesive layers 4 and 5 are formed by applying a urethane adhesive having a metal adhesive layer on both sides of the aluminum layer. The adhesive layer has an adhesive layer on the side of the outer resin layer as the first adhesive layer 4 and an adhesive layer on the side of the inner resin layer as the second adhesive layer 5 as shown in the respective structures of the aluminum pouch.

It is preferable that the first adhesive layer 4 and the second adhesive layer 5 have a thickness of 1 to 5 탆. In the case where the above range is not satisfied, when the thickness is less than 1 탆, the tackiness is poor, and when it is more than 5 탆, cracks may occur.

In addition, the adhesive layers 4 and 5 are as described above for the aluminum pouches.

d) forming an outer resin layer and an inner resin layer on both sides of the aluminum layer

In the step d), the external resin layer 1 and the internal resin layer 3 are formed on both surfaces of the aluminum layer. The external resin layer 1 and the internal resin layer 3 are formed by pressing the external resin layer and the internal resin layer on the adhesive layer. The bonding method may be a conventional bonding method, preferably a lamination method using a dry lamination method or an extrusion lamination method.

The structures of the outer numerical layer 1, the inner resin layer 3, the adhesive layers 4 and 5, and the aluminum layer 2 are as described above for the aluminum pouch.

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

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]

Atmospheric pressure plasma treatment was performed on both sides of an aluminum foil having a thickness of 40 탆 at an output of 1 KW and at a distance of 60 mm from the nozzle at a continuous condition of 60 m / min.

Thereafter, a polyurethane adhesive (manufactured by Yasunobu Polymer Co., Ltd.) was applied to a thickness of 3 탆 in order to laminate the outer resin layer on the first surface of the aluminum foil, and then a 12 탆 thick nylon film (manufactured by Kolon) was subjected to dry lamination Respectively. Thereafter, a modified olefin adhesive (Lotte Chemical Co., Ltd.) was applied to a thickness of 3 탆 in order to laminate the inner resin layer on the second surface of the aluminum foil, and then a 20 탆 thick polypropylene film (manufactured by Sammine Kogyo K.K.) To prepare an aluminum pouch film.

The plasma treated layer measured during the fabrication was measured for surface tension using Dyne Ink, and its value was 84 Dyne.

[Example 2]

Plasma treatment An aluminum pouch film for a secondary battery was prepared in the same manner as in Example 1, except that it was treated with 3 KW. The surface tension of the plasma treated layer measured during manufacture was 84 Dyne.

[Comparative Example 1]

An aluminum pouch film was produced in the same manner as in Example 1 except that chromate treatment was applied to the aluminum layer without plasma treatment to form a chemical conversion layer between the inner layer and the aluminum layer. The surface tension of the plasma treated layer measured during manufacturing was 72 Dyne.

[Comparative Example 2]

An aluminum pouch film for a secondary battery was prepared in the same manner as in Example 1, except that the plasma treatment was performed at 0.5 KW. The surface tension of the plasma treated layer measured during manufacturing was 76 Dyne.

[Comparative Example 3]

An aluminum pouch film for a secondary battery was prepared in the same manner as in Example 1, except that the plasma treatment was conducted at 4 KW. The surface tension of the plasma treated layer measured during manufacturing was 70 Dyne.

Experimental Example

Adhesiveness evaluation

The adhesive strength between the aluminum layer 2 and the inner resin layer 3 and the adhesive force between the aluminum layer 2 and the outer resin layer 1 after the respective aluminum pouch films for secondary batteries according to Examples 1 to 2 and Comparative Examples 1 to 3 were completed, ) Were evaluated respectively.

(Between the aluminum layer and the inner resin layer)
Adhesion (Between the aluminum layer and the outer resin layer)
Adhesion Example 1 13.0 N 7.1 N Example 2 13.2N 7.0 N Comparative Example 1 9.7N 5.5N Comparative Example 2 9.9N 5.7N Comparative Example 3 9.6N 5.1N

Electrolytic solution resistance  evaluation

Each of the aluminum pouch films for secondary batteries according to Examples 1 to 2 and Comparative Examples 1 to 3 was cut into 1.5 cm x 12 cm and placed in a test vessel together with LiPF ₆ standard electrolyte (Panaxitec) Heat in oven. Thereafter, the test pieces were taken out at 1, 3, 5, and 7 days and at each point of time, and the electrolyte resistance was evaluated by measuring the change in the adhesive strength between the aluminum layer (2) and the internal resin layer (3) after washing.

Around 1 day Around three days Around 5th Around 7th Example 1 12.1 N 11.3 N 10.7N 10.2N Example 2 12.5N 11.2N 10.4 N 10.1 N Comparative Example 1 8.7N 8.1 N 7.8 N 7.9 N Comparative Example 2 9.1 N 8.7N 8.5N 8.2N Comparative Example 3 8.4 N 8.0 N 7.6 N 7.4N

As shown in Table 2, Examples 1 and 2 exhibited a higher adhesive strength than Comparative Example 1 without plasma treatment and Comparative Examples 2 and 3 treated with 0.5 KW and 4 KW, respectively.

Claims (4)

An aluminum layer, an outer resin layer formed on one side of the aluminum layer, an inner resin layer formed on the other side of the aluminum layer, a first adhesive layer formed between the aluminum layer and the outer resin layer, And a second adhesive layer, wherein the plasma treatment layer and the chemical conversion treatment layer are sequentially formed on at least one surface of the aluminum layer. The method according to claim 1,
Wherein the plasma treatment layer has a surface tension of 82 Dyne or more. a) plasma treating one or both surfaces of the aluminum layer;
b) subjecting the plasma treatment layer of the aluminum layer to a chemical treatment;
c) forming an adhesive layer on both sides of the aluminum layer;
and d) forming an outer resin layer and an inner resin layer on both sides of the aluminum layer. The method of claim 3,
Wherein the plasma treatment in step a) is performed at an output of 0.8 to 3.5 KW under atmospheric pressure.

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