KR102669314B1 - Outer material and power storage device for power storage device - Google Patents

Abstract

It includes a heat-resistant resin layer (2) as an outer layer, a sealant layer (3) as an inner layer, and a metal foil layer (4) disposed between both layers, and at least the innermost layer (7) of the sealant layer (3) , containing an elastomer-modified olefin-based resin, wherein the elastomer-modified olefin-based resin is composed of olefin-based thermoplastic elastomer-modified homopolypropylene or/and olefin-based thermoplastic elastomer-modified random copolymer, The olefin-based thermoplastic elastomer-modified random copolymer is composed of an olefin-based thermoplastic elastomer-modified random copolymer containing propylene as a copolymerization component and other copolymerization components other than propylene. With this configuration, it is possible to provide an exterior material for an electrical storage device that can maintain good sealing properties of the seal portion of the exterior material even when exposed to a high temperature environment for a long period of time.

Description

Exterior material for power storage device and power storage device {OUTER MATERIAL AND POWER STORAGE DEVICE FOR POWER STORAGE DEVICE}

The present invention relates to exterior materials and storage devices for batteries and condensers used in portable devices such as smartphones and tablets, and batteries and condensers used for hybrid vehicles, electric vehicles, wind power generation, solar power generation, and night-time electricity storage. It's about devices.

In addition, in the scope of this specification and patent claims, the term "tensile yield strength" is based on JIS K7127-1999 (tensile test method), with a sample width of 15 mm, a distance between marking lines of 50 mm, and a tensile speed of 100 mm/min. It refers to the tensile yield strength (tensile yield strength) obtained by measuring under the conditions of.

Lithium ion secondary batteries are widely used as power sources for, for example, notebook personal computers, video cameras, and mobile phones. As this lithium ion secondary battery, one is used in which a case surrounds the battery body (main body including the positive electrode, negative electrode, and electrolyte). It is known that the material (exterior material) for this case has a structure in which, for example, an outer layer made of a heat-resistant resin film, an aluminum foil layer, and an inner layer made of a thermoplastic resin film are bonded and integrated in this order (see Patent Document 1).

The power storage device is constructed by sandwiching the main body of the power storage device with a pair of exterior materials and sealing the peripheral portions of the pair of exterior materials by fusion bonding (heat sealing). By sufficiently sealing with such a heat seal joint, leakage of the electrolyte can be prevented.

Patent Document 1: Japanese Patent Laid-Open No. 2005-22336

However, batteries such as such lithium ion secondary batteries are assumed to be used in a room temperature environment in laptops, personal computers, mobile phones, etc.

However, in recent years, along with the diversification of the uses of such lithium-ion secondary batteries, new uses for external use exposed to high-temperature environments, such as use in automobiles, have also been increasing.

For example, in automotive applications, the temperature becomes quite high when the car is parked outdoors in the summer, and therefore, even for batteries such as lithium-ion secondary batteries, the sealing of the exterior material is damaged even if exposed to such a high temperature environment for a long period of time. There is a demand for the development of an exterior material that can maintain good sealing properties.

The present invention was made in consideration of this technical background, and its purpose is to provide an exterior material for an electrical storage device and an electrical storage device that can maintain good sealing properties of the seal portion of the exterior material even when exposed to a high temperature environment for a long period of time.

In order to achieve the above object, the present invention provides the following means.

[1] An exterior material for an electrical storage device comprising a heat-resistant resin layer as an outer layer, a sealant layer as an inner layer, and a metal foil layer disposed between these two layers,

The sealant layer consists of one to multiple layers,

At least the innermost layer of the sealant layer contains an elastomer-modified olefin resin,

The elastomer-modified olefin-based resin is composed of olefin-based thermoplastic elastomer-modified homopolypropylene or/and olefin-based thermoplastic elastomer-modified random copolymer,

The olefin-based thermoplastic elastomer-modified random copolymer is an olefin-based thermoplastic elastomer-modified random copolymer containing propylene as a copolymerization component and other copolymerization components other than propylene. An exterior material for an electrical storage device, characterized in that:

[2] The exterior material for an electrical storage device according to the preceding item 1, wherein the content of the olefin-based thermoplastic elastomer in the innermost layer is 0.1% by mass or more and less than 20% by mass.

[3] The exterior material for an electrical storage device according to the preceding item 1 or 2, wherein the melting point of the elastomer-modified olefin resin constituting the innermost layer is 160°C to 180°C.

[4] The olefinic thermoplastic elastomer component present in the innermost layer has a plurality of crystallization temperatures, and the lowest crystallization temperature among the plurality of crystallization temperatures is 40°C to 80°C. The exterior material for the power storage device described in the clause.

[5] The exterior material for an electrical storage device according to any one of the preceding paragraphs 1 to 4, wherein the MFR of the olefin-based thermoplastic elastomer component present in the innermost layer is 0.1 g/10 min to 1.4 g/10 min.

[6] The sealant film constituting the sealant layer is the exterior material for an electrical storage device according to any one of the preceding paragraphs 1 to 5, wherein the sealant film has a tensile yield strength of 3.5 MPa to 15.0 MPa at 80°C.

[7] The sealant layer is composed of multiple layers, and a second sealant layer is disposed on the side of the sealant layer closest to the metal foil layer, and the second sealant layer is a propylene-ethylene random copolymer of 50%. The exterior material for an electrical storage device according to any one of the preceding paragraphs 1 to 6, which contains % by mass or more and does not contain an elastomer component.

[8] The exterior material for an electrical storage device according to any one of the preceding paragraphs 1 to 7, wherein the metal foil layer and the sealant layer are bonded to each other through an adhesive layer.

[9] The exterior material for an electrical storage device according to the preceding item 8, wherein the adhesive layer is made of an adhesive containing an olefin-based resin having a carboxyl group and a polyfunctional isocyanate compound.

[10] A power storage device main body,

Provided with an exterior material for an electrical storage device according to any one of the preceding paragraphs 1 to 9,

A power storage device characterized in that the power storage device main body portion is exteriorized with the exterior material.

In the invention of [1], since at least the innermost layer of the sealant layer of the exterior material contains the specific elastomer-modified olefin resin, the initial seal strength between the exterior materials can be sufficiently secured even in a high temperature environment. Together, sufficient yarn strength can be maintained even when placed in a high-temperature environment (for example, in a car in the summer) for a long period of time.

In the invention of [2], the film strength of the sealant layer increases when the content of the olefin-based thermoplastic elastomer in the innermost layer of the sealant layer is 0.1 mass% or more and less than 20 mass%. It becomes difficult for destruction (breakage) to occur.

In the invention of [3], since the melting point of the elastomer-modified olefin resin constituting the innermost layer of the sealant layer is 160°C to 180°C, leakage of the sealant layer can be sufficiently suppressed when heat sealing the exterior material, It is also excellent in heat resistance under the above-mentioned high temperature environment.

In the invention of [4], the lowest crystallization temperature is 40°C to 80°C, so that the adhesion time at room temperature (adhesion time when heat sealing) can be shortened.

In the invention of [5], since it is difficult for the resin (olefin-based resin of the innermost layer) to elute during heat treatment, greater adhesive strength can be secured.

In the invention of [6], a sealant film with a tensile yield strength of 3.5 MPa to 15.0 MPa at 80°C is used in the sealant layer, so the power storage device is placed in a high temperature environment (for example, in a car in the summer) for a long period of time. Even if it is used, it can prevent rupture of the exterior material due to an increase in internal pressure.

In the invention of [7], the second sealant layer on the side closest to the metal foil layer contains 50% by mass or more of propylene-ethylene random copolymer and does not contain an elastomer component, so that the second sealant layer on the side closest to the metal foil layer is The adhesiveness of the layer improves, and even if deformation occurs, separation between layers becomes less likely to occur. In addition, since the second sealant layer on the side closest to the metal foil layer does not contain an elastomer component, crazes (cracks and gaps) that may occur at the interface between the propylene-ethylene random copolymer and the elastomer component There is no intrusion of the electrolyte into the vicinity of the metal foil layer due to a gap in the interface, and sufficient insulation can be secured.

In the invention of [8], the interlayer adhesion between the metal foil layer and the sealant layer can be further increased.

In the invention of [9], since the adhesive layer is made of an adhesive containing an olefin-based resin having a carboxyl group and a polyfunctional isocyanate compound, electrolyte resistance can be further improved.

In the invention of [10], the initial seal strength of the exterior materials can be sufficiently secured even in a high temperature environment, and the exterior material can maintain sufficient yarn strength even when placed in a high temperature environment (for example, inside a car in the summer) for a long period of time. It is possible to provide a power storage device excellent in high temperature durability.

1 is a cross-sectional view showing one embodiment of an exterior material for an electrical storage device according to the present invention.
Fig. 2 is a cross-sectional view showing another embodiment of an exterior material for an electrical storage device according to the present invention.
Fig. 3 is a cross-sectional view showing one embodiment of a power storage device according to the present invention.
FIG. 4 is a perspective view showing the exterior material (flat shape), the power storage device main body, and the exterior case (molded body molded into a three-dimensional shape) that constitute the power storage device of FIG. 3 in a separated state before heat sealing.

One embodiment of the exterior material 1 for an electrical storage device according to the present invention is shown in Fig. 1. This exterior material 1 for an electrical storage device is used, for example, as an exterior material for a lithium ion secondary battery. The exterior material 1 for an electrical storage device may be used as an exterior material as is without undergoing molding, and may be used as the exterior case 10 by being subjected to molding such as deep drawing molding or extrusion molding, for example. This may be acceptable (see Figure 4).

The exterior material 1 for an electrical storage device includes a base material layer (outer layer) 2 laminated and integrated on one side of the metal foil layer 4 through a first adhesive layer 5, and the metal foil layer 4 The inner sealant layer (inner layer) 3 is laminated and integrated on the other side through the second adhesive layer 6 (see Figs. 1 and 2).

In the exterior material 1 of FIG. 1, the inner sealant layer (inner layer) 3 is composed of a single layer (one layer) made of the first sealant layer 7. Accordingly, the first sealant layer 7 is disposed innermost (the first sealant layer 7 is the innermost layer).

In addition, in the exterior material 1 of FIG. 2, the inner sealant layer (inner layer) 3 is a first sealant layer 7, which is the innermost layer, and a second sealant layer disposed on the side closest to the metal foil layer 4. It has a two-layer lamination structure consisting of two sealant layers (8), and the first sealant layer (7) is disposed at the innermost side.

In the present invention, the inner sealant layer (inner layer) 3 provides excellent chemical resistance even to highly corrosive electrolytes used in lithium ion secondary batteries, etc., and also serves to provide heat sealing properties to the exterior material. It is in charge. The sealant layer (inner layer) 3 is made of a non-stretched sealant film.

In the present invention, the sealant layer (inner layer) 3 may be formed of one layer or may be formed of two or more layers, but at least the innermost layer ( The first sealant layer (7) is configured to contain an elastomer-modified olefin resin.

The elastomer-modified olefin-based resin (polypropylene block copolymer) is preferably composed of olefin-based thermoplastic elastomer-modified homopolypropylene or/and olefin-based thermoplastic elastomer-modified random copolymer, and the olefin-based thermoplastic elastomer-modified random copolymer The elastomer-modified random copolymer is an olefin-based thermoplastic elastomer modified product of a random copolymer containing “propylene” and “other copolymerization components excluding propylene” as copolymerization components, and the “other copolymerization components excluding propylene” It is not particularly limited, but examples include olefin components such as ethylene, 1-butene, 1-hexene, 1-pentene, and 4methyl-1-pentene, as well as butadiene. The olefin-based thermoplastic elastomer is not particularly limited, but examples include EPR (ethylene propylene rubber), propylene-butene elastomer, propylene-butene-ethylene elastomer, and EPDM (ethylene-propylene-diene rubber). ), etc., and among them, it is preferable to use EPR (ethylene propylene rubber).

Regarding the elastomer-modified olefin-based resin, the state of “olefin-based thermoplastic elastomer-modified” may be graft polymerization or any other modified state.

The elastomer-modified olefin resin can be produced, for example, by the following reactor-made method. This is only an example, and is not particularly limited to those manufactured by this manufacturing method.

First, a Ziegler Natta catalyst, cocatalyst, propylene, and hydrogen are supplied to the first reactor to polymerize homopolypropylene. The obtained homopolypropylene is transferred to the second reactor in a state containing unreacted propylene and Ziegler Natta catalyst. In the second reactor, propylene and hydrogen are again added to polymerize homopolypropylene. The obtained homopolypropylene is transferred to the third reactor in a state containing unreacted propylene and Ziegler Natta catalyst. The elastomer-modified olefin resin can be produced by adding ethylene, propylene, and hydrogen again in the third reactor to polymerize ethylene-propylene rubber (EPR), which is a copolymerization of ethylene and propylene. For example, the elastomer-modified olefin-based resin can be produced by adding a solvent and producing it in a liquid phase, and the elastomer-modified olefin-based resin can be produced by reacting in the gas phase without using a solvent. It can be manufactured.

The content of the olefin-based thermoplastic elastomer in the innermost layer (first sealant layer) 7 of the sealant layer 3 is preferably 0.1% by mass or more and less than 20% by mass. In addition, in the innermost layer (first sealant layer) 7 of the sealant layer 3, homopolypropylene (part not modified with olefin-based thermoplastic elastomer) or/and the random copolymer (olefin-based thermoplastic elastomer) It is preferable that the content of the portion that has not been modified into mer is 80% by mass or more and 99% by mass or less.

The melting point of the elastomer-modified olefin resin constituting the innermost layer (first sealant layer) 7 of the sealant layer 3 is preferably in the range of 160°C to 180°C. When heat sealing the exterior material, leakage of the sealant layer 3 can be sufficiently suppressed, and it is also excellent in heat resistance in a high temperature environment. Among them, the melting point of the elastomer-modified olefin resin constituting the innermost layer (first sealant layer) 7 of the sealant layer 3 is preferably 163°C or higher, and the range of 163°C to 169°C is particularly high. desirable. The melting point is the melting point measured by differential scanning calorimetry (DSC) method in accordance with JIS K7121-1987.

The olefinic thermoplastic elastomer component (this component alone) present in the innermost layer (first sealant layer) 7 preferably has a plurality of crystallization temperatures. In the case of having multiple crystallization temperatures in this way, the effect of making it difficult for the resin (olefin-based resin of the innermost layer) to elute during adhesion can be obtained. Additionally, in the case of having multiple crystallization temperatures, the lowest crystallization temperature among the multiple crystallization temperatures is preferably in the range of 40°C to 80°C, and more preferably in the range of 40°C to 75°C. . The lowest crystallization temperature is 40°C to 80°C, which has the effect of shortening the adhesion time at room temperature (adhesion time when heat sealing). The crystallization temperature is the crystallization temperature (crystallization peak) measured by differential scanning calorimetry (DSC) in accordance with JIS K7121-1987.

The MFR of the olefinic thermoplastic elastomer component (this component alone) present in the innermost layer (first sealant layer) 7 is preferably 0.1 g/10 min to 1.4 g/10 min, and in this case, the heat Since the resin (olefin-based resin of the innermost layer) is difficult to elute during implementation, greater adhesive strength can be secured. Among them, it is more preferable that the MFR of the olefin-based thermoplastic elastomer component (this component alone) present in the innermost layer (first sealant layer) 7 is 0.1 g/10 min to 1.0 g/10 min. , it is particularly preferable that it is 0.1 g/10 min to 0.6 g/10 min. In addition, the MFR (melt flow rate) is the MFR measured under the conditions of 230°C and 2.16 kg based on JIS K7210-1-2014.

The sealant film constituting the sealant layer 3 preferably has a tensile yield strength of 3.5 MPa to 15.0 MPa at 80°C. For example, when the sealant layer 3 is composed of only the first sealant layer 7, it is preferable that the first sealant film has a tensile yield strength of 3.5 MPa to 15.0 MPa at 80°C. When the sealant layer 3 is composed of a laminate of the first sealant layer 7 and the second sealant layer 8, the tensile yield strength of the laminated sealant film at 80°C is 3.5 MPa to 15.0 MPa. desirable. This applies even when the sealant layer 3 is a multi-layer of three or more layers. As the sealant film constituting the sealant layer 3 has a tensile yield strength of 3.5 MPa to 15.0 MPa at 80°C, even if the power storage device is placed in a high temperature environment (for example, in a car in the summer) for a long period of time, it can be used. It can prevent rupture of the exterior material due to an increase in internal pressure. Among these, it is particularly preferable that the sealant film constituting the sealant layer 3 has a tensile yield strength of 4 MPa to 12 MPa at 80°C.

The thickness of the innermost layer (first sealant layer) 7 is preferably 30 μm or more, and in this case, there is an advantage of improving the toughness of the first sealant layer 7. Among these, the thickness of the innermost layer (first sealant layer) 7 is more preferably 30 μm to 100 μm.

When providing the second sealant layer 8, the thickness of the second sealant layer 8 is preferably 3 μm to 60 μm, and more preferably 5 μm to 20 μm. In addition, when providing the second sealant layer 8, the resin forming the second sealant layer 8 is not particularly limited, but examples include propylene-ethylene random copolymer and homopolypropylene. , In addition to polyethylene, olefin-based thermoplastic elastomer-modified homopolypropylene, olefin-based thermoplastic elastomer-modified random copolymer (olefin-based random copolymer containing “propylene” and “other copolymerization components other than propylene” as copolymerization components) Thermoplastic elastomer modified product) etc. can be mentioned.

Additionally, the thickness of the sealant layer 3 is preferably set to 30 μm to 200 μm.

In the present invention, the sealant layer 3 is composed of multiple layers, and is comprised of an innermost layer (first sealant layer) 7 containing the elastomer-modified olefin resin and the metal foil layer 4. It has a second sealant layer 8 disposed on the proximal side (see Fig. 2), wherein the second sealant layer contains 50% by mass or more of propylene-ethylene random copolymer and does not contain an elastomer component. It is desirable to have a configuration. When such a configuration is adopted, the second sealant layer 8 on the side closest to the metal foil layer 4 contains 50% by mass or more of propylene-ethylene random copolymer and does not contain an elastomer component. Because of the structure, adhesion to the metal foil layer side is improved, and peeling between layers is unlikely to occur even if deformation occurs. In addition, since the second sealant layer 8 on the side closest to the metal foil layer 4 does not contain an elastomer component, there is a possibility that it may occur at the interface between the propylene-ethylene random copolymer and the elastomer component. There is no intrusion of electrolyte into the vicinity of the metal foil layer due to craze (interface gap without cracks or gaps), and sufficient insulation can be secured. Among these, it is more preferable that the second sealant layer contains 70% by mass or more of propylene-ethylene random copolymer and does not contain an elastomer component. Here, the constitution not containing an elastomer component means that the elastomer component is not mixed (blended) and also means that the elastomer modified resin is not mixed.

The sealant film constituting the sealant layer (inner layer) 3 is preferably manufactured by a molding method such as multilayer extrusion molding, inflation molding, or T die cast film molding.

The method of laminating the sealant film constituting the sealant layer (inner layer) 3 on the metal foil layer 4 is not particularly limited, but is a dry lamination method or a sandwich lamination method (using an adhesive film such as acid-modified polypropylene). A method of extruding, sand laminating this between metal foil and the sealant film, and then heat laminating with a hot roll) can be mentioned.

In the present invention, the base layer (outer layer) 2 is preferably formed of a heat-resistant resin layer. As the heat-resistant resin constituting the heat-resistant resin layer 2, a heat-resistant resin that does not melt at the heat-sealing temperature used when heat-sealing the exterior material is used. As the heat-resistant resin, it is preferable to use a heat-resistant resin having a melting point 10°C or more higher than the melting point of the sealant layer 3, and to use a heat-resistant resin having a melting point 20°C or more higher than the melting point of the sealant layer 3. Particularly desirable.

The heat-resistant resin layer (outer layer) 2 is not particularly limited, but examples include polyamide films such as nylon films, polyester films, etc., and stretched films thereof are preferably used. Among them, the heat-resistant resin layer 2 may be a biaxially stretched polyamide film such as a biaxially stretched nylon film, a biaxially stretched polybutylene terephthalate (PBT) film, a biaxially stretched polyethylene terephthalate (PET) film, or It is particularly preferred to use biaxially oriented polyethylene naphthalate (PEN) film. The nylon film is not particularly limited, but examples include 6 nylon film, 6,6 nylon film, and MXD nylon film. In addition, the heat-resistant resin layer 2 may be formed as a single layer, or may be formed as a multiple layer made of, for example, a polyester film/polyamide film (a multiple layer made of a PET film/nylon film, etc.). In addition, in the case of the above-mentioned multiple layers, it is better to arrange the polyester film side at the outermost side.

The thickness of the outer layer (base layer) 2 is preferably 2 μm to 50 μm. When a polyester film is used, the thickness is preferably 5 μm to 40 μm, and when a nylon film is used, the thickness is preferably 15 μm to 50 μm. By setting it above the highly suitable lower limit, sufficient strength as an exterior material can be secured, and by setting it below the highly suitable upper limit, stress during molding such as extrusion molding and drawing can be reduced and formability can be improved. .

In the exterior material for an electrical storage device according to the present invention, the metal foil layer 4 plays a role in providing gas barrier properties to the exterior material 1 to prevent oxygen or moisture from entering. The metal foil layer 4 is not particularly limited, but examples include aluminum foil, SUS foil (stainless steel foil), and copper foil. Among these, aluminum foil and SUS foil (stainless steel foil) are used. It is desirable to do so. The thickness of the metal foil layer 4 is preferably 10 μm to 120 μm. By being 10 ㎛ or more, it is possible to prevent the occurrence of pinholes during rolling when manufacturing metal foil, and by being 120 ㎛ or less, the stress during molding such as extrusion molding and drawing can be reduced and formability can be improved. there is.

As for the metal foil layer 4, it is preferable that chemical conversion treatment is applied to at least the inner surface (the surface on the second adhesive layer 6 side). By performing this chemical treatment, corrosion of the metal foil surface caused by the contents (electrolyte solution of the battery, etc.) can be sufficiently prevented. For example, chemical conversion treatment is performed on the metal foil by performing the following treatment. That is, for example, on the surface of a metal foil that has been degreased,

1) An aqueous solution of a mixture containing at least one compound selected from the group consisting of phosphoric acid, chromic acid, metal salts of fluoride, and non-metal salts of fluoride.

2) A mixture containing at least one type of resin selected from the group consisting of phosphoric acid, acrylic resin, chitosan derivative resin, and phenol type resin, and at least one type of compound selected from the group consisting of chromic acid and chromium (III) salt. aqueous solution of

3) At least one resin selected from the group consisting of phosphoric acid, acrylic resin, chitosan derivative resin, and phenol resin, at least one compound selected from the group consisting of chromic acid and chromium (III) salt, and fluoride An aqueous solution of a mixture containing at least one compound selected from the group consisting of metal salts and non-metal salts of fluoride

After applying the aqueous solution of any one of 1) to 3) above, chemical conversion treatment is performed by drying.

The amount of chromium adhesion (per side) of the chemical conversion film is preferably 0.1 mg/m2 to 50 mg/m2, and particularly preferably 2 mg/m2 to 20 mg/m2.

The first adhesive layer (outer adhesive layer) 5 is not particularly limited, but includes, for example, a polyurethane polyolefin adhesive layer, a polyurethane adhesive layer, a polyester polyurethane adhesive layer, a polyether polyurethane adhesive layer, etc. can be mentioned. The thickness of the first adhesive layer 5 is preferably set to 1 μm to 6 μm. Among these, from the viewpoint of thinning and weight reduction of the exterior material 1, it is particularly preferable that the thickness of the first adhesive layer 5 is set to 1 μm to 3 μm.

The second adhesive layer (inner adhesive layer) 6 is not particularly limited, and for example, those exemplified as the first adhesive layer 5 can be used, but are polyolefin-based adhesives that are less prone to expansion due to electrolyte solution. It is desirable to use . Among these, it is particularly preferable that the second adhesive layer (inner adhesive layer) 6 is formed of an adhesive containing an olefin resin having a carboxyl group and a polyfunctional isocyanate compound. A second adhesive layer can be formed by dry laminating the adhesive. Alternatively, the second adhesive layer (inner adhesive layer) 6 is particularly preferably formed of an olefin resin having a carboxyl group. In this case, the second adhesive layer can be formed by extrusion laminate by melt extrusion of an olefin resin having a carboxyl group. The olefin resin having the carboxyl group is not particularly limited, but examples include maleic acid-modified polypropylene, maleic acid-modified polyethylene, acrylic acid-modified polypropylene, acrylic acid-modified polyethylene, methacrylic acid-modified polypropylene, methacrylic acid-modified polyethylene, and carboxylic acid-modified olefin resins such as fumaric acid-modified polypropylene and fumaric acid-modified polyethylene. The thickness of the second adhesive layer 6 is preferably set to 1 μm to 4 μm. Among these, from the viewpoint of thinning and weight reduction of the exterior material, it is particularly preferable that the thickness of the second adhesive layer 6 is set to 1 μm to 3 μm.

By molding (deep drawing molding, expansion molding, etc.) the exterior material 1 of the present invention, an exterior case (battery case, etc.) 10 can be obtained (FIG. 4). Additionally, the exterior material 1 of the present invention can be used as is without being subjected to molding (FIG. 4).

One embodiment of a power storage device 30 constructed using the exterior material 1 of the present invention is shown in FIG. 3. This electrical storage device 30 is a lithium ion secondary battery. In this embodiment, as shown in FIGS. 3 and 4, the exterior member 15 is comprised of an exterior case 10 obtained by molding the exterior material 1 and the planar exterior material 1. Thus, an electrical storage device main body portion (electrochemical element, etc.) 31 of a roughly rectangular parallelepiped shape is accommodated in the receiving recess of the exterior case 10 obtained by molding the exterior material 1 of the present invention, and the electrical storage device main body portion On top of (31), the exterior material 1 of the present invention is disposed with the sealant layer 3 side facing inward (lower side) without being molded, and the sealant layer of the planar exterior material 1 ( The peripheral portion of 3) and the sealant layer 3 of the flange portion (peripheral portion for sealing) 29 of the exterior case 10 are sealed by heat sealing, thereby forming the electrical storage device 30 of the present invention. It is composed (see Figures 3 and 4). Additionally, the inner surface of the receiving recess of the exterior case 10 is made of a sealant layer 3, and the outer surface of the receiving recess is made of a base material layer (outer layer) 2 (see Fig. 4).

In FIG. 3, 39 is a heat seal portion where the peripheral portion of the exterior material 1 and the flange portion (peripheral portion for sealing) 29 of the exterior case 10 are joined (welded). In addition, in the power storage device 30, the tip of the tab lead connected to the power storage device main body 31 is extended to the outside of the exterior member 15, but is not shown.

The electrical storage device main body 31 is not particularly limited, but examples include a battery main body, a capacitor main body, and a condenser main body.

The width of the heat seal portion 39 is preferably set to 0.5 mm or more. By setting it to 0.5 mm or more, sealing can be performed reliably. Among these, the width of the heat seal portion 39 is preferably set to 3 mm to 15 mm.

In addition, in the above embodiment, the exterior member 15 was composed of an exterior case 10 obtained by molding the exterior material 1 and a planar exterior material 1 (see FIGS. 3 and 4), especially in this case. It is not limited to combinations, and for example, the exterior member 15 may be composed of a pair of planar exterior materials 1, or may be composed of a pair of exterior cases 10.

Example

Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples.

<Materials used>

(Elastomer modified olefin resin (A))

The elastomer-modified olefin-based resin (A) consists of EPR-modified homopolypropylene and an EPR-modified product of ethylene-propylene random copolymer. The EPR means ethylene-propylene rubber. The content of the elastomer component in the elastomer-modified olefin resin (A) is 15% by mass. The melting point of the elastomer-modified olefin resin (A) is 166°C.

(Elastomer modified olefin resin (B))

The elastomer-modified olefin resin (B) consists of propylene-butene elastomer-modified homopolypropylene and propylene-butene elastomer-modified products of ethylene-propylene random copolymer. The content of the elastomer component in the elastomer-modified olefin resin (B) is 18% by mass. The melting point of the elastomer-modified olefin resin (B) is 164°C.

(Elastomer modified olefin resin (C))

The elastomer-modified olefin-based resin (C) consists of propylene-butene-ethylene elastomer-modified homopolypropylene and propylene-butene-ethylene elastomer modified product of ethylene-propylene random copolymer. The content of the elastomer component in the elastomer-modified olefin resin (C) is 16% by mass. The melting point of the elastomer-modified olefin resin (C) is 164°C.

<Example 1>

A chemical treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol is applied to both sides of the 35㎛ thick aluminum foil (4), and then dried at 180°C. This was performed to form a chemical conversion film. The chromium adhesion amount of this chemical conversion film was 10 mg/m2 per side.

Next, a biaxially stretched 6-nylon film (2) with a thickness of 15 μm was dry laminated to one side of the chemically treated aluminum foil (4) using a two-component curing type urethane-based adhesive (outer adhesive) (5). (Fighted).

Next, a sealant film (first sealant layer) 7 with a thickness of 80 μm made of elastomer-modified olefin resin (A) is extruded, and then 2 is applied to one side of the sealant film 7 (3). The other side of the dry laminated aluminum foil 4 is overlapped via a liquid-curing urethane adhesive (inner adhesive layer) 6 and sandwiched between a rubber nip roll and a laminate roll heated to 100°C. Dry lamination was carried out by pressing and then aging (heating) at 50° C. for 5 days to obtain the exterior material 1 for an electrical storage device having the structure shown in FIG. 1 .

<Example 2>

As the inner adhesive 6, a two-component curing type acrylic adhesive 6 was used instead of a two-component curing type urethane adhesive in the same manner as in Example 1, and an exterior material for an electrical storage device having the configuration shown in FIG. 1 ( 1) was obtained.

<Example 3>

A chemical treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol is applied to both sides of the aluminum foil 4 with a thickness of 35 μm, followed by drying at 180°C to achieve chemical conversion. A film was formed. The chromium adhesion amount of this chemical conversion film was 10 mg/m2 per side.

Next, a biaxially stretched 6-nylon film (2) with a thickness of 15 μm was dry laminated (attached) to one side of the chemically treated aluminum foil (4) through a two-component curing type urethane-based adhesive (5). .

Next, on the other side of the dry laminated aluminum foil 4, a maleic anhydride modified polypropylene film (inner adhesive layer) 6 with a thickness of 4 μm and a propylene-ethylene random copolymer film with a thickness of 8 μm (second 2 sealant layer (8) and the 72 ㎛ thick elastomer-modified olefin resin (A) film (first sealant layer) (7) were co-extruded and bonded together in this order to form a rubber nip roll. and a laminate roll heated to 100°C, dry laminated by sandwiching and pressing, and then aged (heated) at 50°C for 5 days to produce an exterior material for an electrical storage device having the configuration shown in FIG. (1) was obtained.

<Example 4>

A chemical treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol is applied to both sides of the aluminum foil 4 with a thickness of 35 μm, followed by drying at 180°C to achieve chemical conversion. A film was formed. The chromium adhesion amount of this chemical conversion film was 10 mg/m2 per side.

Next, a biaxially stretched 6-nylon film (2) with a thickness of 15 μm was dry laminated (attached) to one side of the chemically treated aluminum foil (4) through a two-component curing type urethane-based adhesive (5). .

Next, on the other side of the dry laminated aluminum foil 4, a maleic anhydride-modified polypropylene film (inner adhesive layer) 6 with a thickness of 4 μm and an elastomer-modified olefin resin (A) with a thickness of 80 μm are applied. ) The co-extruded film 3 is bonded together in this order, sandwiched between a rubber nip roll and a laminate roll heated to 100°C, and dry laminated by pressing, and then aged at 50°C for 5 days. By heating (heating), the exterior material 1 for an electrical storage device having the structure shown in FIG. 1 was obtained.

<Example 5>

An exterior material (1) for an electrical storage device having the structure shown in FIG. 1 in the same manner as in Example 1, except that elastomer-modified olefin-based resin (B) was used instead of elastomer-modified olefin-based resin (A). got it

<Example 6>

An exterior material (1) for an electrical storage device having the structure shown in FIG. 1 in the same manner as in Example 1, except that an elastomer-modified olefin-based resin (C) was used instead of the elastomer-modified olefin-based resin (A). got it

<Example 7>

A chemical treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol is applied to both sides of the aluminum foil 4 with a thickness of 35 μm, followed by drying at 180°C to achieve chemical conversion. A film was formed. The chromium adhesion amount of this chemical conversion film was 10 mg/m2 per side.

Next, a biaxially stretched 6-nylon film (2) with a thickness of 15 μm was dry laminated (attached) to one side of the chemically treated aluminum foil (4) through a two-component curing type urethane-based adhesive (5). .

Next, a two-component curing type urethane-based adhesive (inner adhesive layer) 6 is applied to the other side of the dry laminated aluminum foil 4, and then a homopolypropylene film (made of 2 sealant layer) (8) and the 72-μm-thick elastomer-modified olefin-based resin (A) film (first sealant layer) (7) were co-extruded and bonded together in this order with a rubber nip roll at 100°C. Dry lamination is performed by sandwiching and pressing between heated laminate rolls, and then aging (heating) at 50° C. for 5 days to produce the exterior material 1 for an electrical storage device having the structure shown in FIG. got it

<Example 8>

As the second sealant layer 8, the same procedure as in Example 7 was performed, except that an 8 μm thick propylene-ethylene random copolymer film 8 was used instead of the 8 μm thick homopolypropylene film, as shown in Fig. 2. An exterior material 1 for an electrical storage device having the structure shown was obtained.

<Example 9>

As the inner adhesive 6, a two-component curing type acrylic adhesive 6 was used instead of a two-component curing type urethane adhesive in the same manner as in Example 8, and an exterior material for an electrical storage device having the configuration shown in FIG. 2 was prepared ( 1) was obtained.

<Comparative example 1>

An exterior material for an electrical storage device having the structure shown in FIG. 1 was obtained in the same manner as in Example 1, except that a propylene-ethylene random copolymer was used instead of the elastomer-modified olefin resin (A).

<Comparative example 2>

A chemical treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol is applied to both sides of the aluminum foil 4 with a thickness of 35 μm, followed by drying at 180°C to achieve chemical conversion. A film was formed. The chromium adhesion amount of this chemical conversion film was 10 mg/m2 per side.

Next, a biaxially stretched 6-nylon film (2) with a thickness of 15 μm was dry laminated (attached) to one side of the chemically treated aluminum foil (4) through a two-component curing type urethane-based adhesive (5). .

Next, a two-component curing type acrylic adhesive 6 is applied to the other side of the dry laminated aluminum foil 4, and then a 68 μm thick elastomer-modified olefin resin (A) film is applied to the applied surface. (second sealant layer) (8) and the propylene-ethylene random copolymer film (first sealant layer) (7) with a thickness of 12 μm were co-extruded and bonded in this order and heated to 100°C with a rubber nip roll. It was dry laminated by sandwiching it between the laminated rolls and pressing, and then aging (heating) at 50°C for 5 days to obtain an exterior material for an electrical storage device with the structure shown in FIG. 2.

In addition, the tensile yield strength (see Table 1) of the sealant film (thickness 80 μm) (3) used to prepare the exterior materials of Examples 1 to 9 and Comparative Examples 1 to 2 was the tensile yield strength measured as follows ( tensile yield strength).

<Method for measuring tensile yield strength of sealant film>

Regarding the non-stretched sealant film (3) (thickness 80㎛) prepared in the same manner for separate measurement purposes, a type 2 test piece (length of 150 mm or more) was prepared in accordance with JIS K7127-1999 (tensile test method for plastic films). And, under the conditions of 80℃, a tensile test was performed under the conditions of sample width 15mm, distance between grippers 100mm, distance between marking lines 50mm, and tensile speed 100mm/min, and tensile yield strength (tensile yield strength) was obtained. The load at the yield point in the S-S curve is called tensile yield strength. Additionally, the test piece was set in a tensile test device in a constant temperature bath set at 80°C, left to stand in this 80°C environment for 1 minute, and then subjected to a tensile test in an 80°C environment. The measurement results of the tensile yield strength at 80°C are shown in Table 1.

In addition, the thickness of the test piece is set to 80 ㎛ and measured, but for example, the sealant film 3 with a thickness of 64 ㎛ used is 2 of the second sealant layer with a thickness of 6 ㎛ and the first sealant layer with a thickness of 58 ㎛. In the case of a layered configuration, a test piece with a thickness of 80 μm is prepared and measured so that the thickness ratio of the two layers does not change. That is, a test piece having a two-layer lamination structure of a second sealant layer with a thickness of 7.5 μm and a first sealant layer with a thickness of 72.5 μm is prepared and measured. In the case of a laminated structure of three or more layers, a test piece with a thickness of 80 ㎛ is prepared and measured in the same manner.

Each of the exterior materials for electrical storage devices obtained as described above was evaluated based on the following measurement method.

<Method for measuring initial yarn strength at high temperature>

After cutting out two test specimens with a width of 15 mm Using a device (TP-701-A), heat sealing was performed by heating on one side under the following conditions: heat seal temperature: 200°C, actual pressure: 0.2 MPa (gauge display pressure), and real time: 2 seconds.

Next, regarding a pair of exterior materials whose inner sealant layers were heat-sealed to each other as described above, a strokerograph (tensile test device) (AGS-5kNX) manufactured by Shimadzu Access was placed in a constant temperature chamber in accordance with JIS Z0238-1998. was used to measure the peeling strength when the exterior material (test specimen) was peeled 90 degrees from the inner sealant layers of the seal portion at a tensile speed of 100 mm/min, and this was called the seal strength (N/15 mm width). Additionally, the yarn strength at 100°C and the yarn strength at 120°C were measured.

In the measurement of yarn strength at 100°C, the test specimen was set in a tensile test device in a constant temperature bath set at 100°C, left in the 100°C environment for 1 minute, and then measured in the 100°C environment. For the measurement of yarn strength at 120°C, the test specimen was set in a tensile test device in a constant temperature bath set at 120°C, left to stand in this 120°C environment for 1 minute, and then measured in an environment of 120°C.

If both the yarn strength at 100°C and the yarn strength at 120°C are 27N/15mm width or more, it is said to pass.

<Method for measuring thread strength after 90 days in a high temperature environment>

Two pieces of exterior material cut to a size of 200 mm long x 150 mm wide were placed overlapping each other with the sealant layers facing each other on the inside, and the edges of the three sides were heat sealed at 180°C and 0.2 MPa for 2 seconds. After injecting 10 ml of electrolyte through the opening of the remaining unsealed side, this remaining side was also heat-sealed under the same seal conditions as above while removing the air inside to create a mock battery (test specimen). Additionally, as the electrolyte solution, an electrolyte solution in which lithium hexafluorophosphate (LiPF ₆ ) was dissolved at a concentration of 1 mol/l in a mixed solvent containing ethylene carbonate (EC) and dimethyl carbonate (DMC) in an equal volume ratio was used.

The obtained simulated battery was placed in a constant temperature and humidity chamber manufactured by ESPEC and left to stand for 90 days under conditions of 80°C x 90%Rh (exposed to a high temperature and high humidity environment for 90 days).

After the above 90 days have elapsed, the mock battery is taken out, one side is opened to remove the electrolyte, and the inside is washed with water several times. Then, the two exterior materials are overlapped to include the seal portion of the two exterior materials, and a width of 15 mm Regarding this pair of exterior materials obtained by cutting them to a size of 150 mm in length, the pair of exterior materials was threaded using a Strograph (tensile test device) (AGS-5kNX) manufactured by Shimadzu Access in accordance with JIS Z0238-1998. The peeling strength when the sealant layers were peeled at 90 degrees at a tensile speed of 100 mm/min was measured, and this was called the thread strength (N/15 mm width). Additionally, the yarn strength at 25°C was measured. A test with a yarn strength of 27N/15mm width or more is said to pass.

As is clear from Table 1, the exterior materials for electrical storage devices of Examples 1 to 9 of the present invention can secure sufficient initial yarn strength even in a high temperature environment, and maintain sufficient yarn strength even when placed in a high temperature environment for a long period of time. You can.

On the other hand, in Comparative Examples 1 and 2, the initial yarn strength was insufficient in a high temperature environment, and the yarn strength after being placed in a high temperature environment for a long period of time decreased significantly.

[Industrial applicability]

The exterior material for an electrical storage device produced using the sealant film according to the present invention and the exterior material for an electrical storage device according to the present invention are specific examples, for example,

·Electric storage devices such as lithium secondary batteries (lithium ion batteries, lithium polymer batteries, etc.)

Lithium ion capacitor

·Electrical double layer condenser

It is used as an exterior material for various electrical storage devices. In addition, the electrical storage device according to the present invention includes an all-solid-state battery in addition to the electrical storage devices illustrated above.

This application claims priority from Japanese Patent Application No. 2016-159935 filed on August 17, 2016, and its disclosure constitutes a part of this application as is.

The terms and descriptions used herein are used to describe embodiments related to the present invention, and the present invention is not limited thereto. The present invention, as long as it is within the scope of the claims, allows any design changes as long as it does not deviate from the spirit.

1: Exterior material for electricity storage device 2: Heat-resistant resin layer (outer layer)
3: Sealant layer (inner layer) 4: Metal foil layer
5: Outer adhesive layer (first adhesive layer) 6: Inner adhesive layer (second adhesive layer)
7: First sealant layer (innermost layer; innermost sealant layer)
8: Second sealant layer (sealant layer closest to the metal foil layer side)
10: External case for power storage device 15: External member
30: Power storage device 31: Power storage device main body

Claims (10)

An exterior material for an electrical storage device comprising a heat-resistant resin layer as an outer layer, a sealant layer as an inner layer, and a metal foil layer disposed between these two layers,
The sealant layer is composed of multiple layers, and at least the innermost layer of the sealant layer contains an elastomer-modified olefin resin,
The elastomer-modified olefin-based resin is composed of olefin-based thermoplastic elastomer-modified homopolypropylene or/and olefin-based thermoplastic elastomer-modified random copolymer,
The olefin-based thermoplastic elastomer-modified random copolymer is an olefin-based thermoplastic elastomer-modified random copolymer containing propylene as a copolymerization component and other copolymerization components other than propylene,
A second sealant layer is disposed on the side of the sealant layer closest to the metal foil layer, and the second sealant layer contains 50% by mass or more of propylene-ethylene random copolymer and does not contain an elastomer component. ,
The content rate of homopolypropylene (part not modified with olefinic thermoplastic elastomer) or/and the random copolymer (part not modified with olefinic thermoplastic elastomer) in the innermost part of the sealant layer (first sealant layer) is An exterior material for a power storage device, characterized in that it contains 80% by mass or more and 99% by mass or less. According to paragraph 1,
An exterior material for an electrical storage device, characterized in that the content of the olefin-based thermoplastic elastomer in the innermost layer is 0.1% by mass or more and less than 20% by mass. According to claim 1 or 2,
An exterior material for an electrical storage device, wherein the elastomer-modified olefin resin constituting the innermost layer has a melting point of 160°C to 180°C. According to claim 1 or 2,
The olefin-based thermoplastic elastomer component present in the innermost layer has a plurality of crystallization temperatures, and the lowest crystallization temperature among the plurality of crystallization temperatures is 40°C to 80°C. According to claim 1 or 2,
An exterior material for an electrical storage device, wherein the MFR of the olefin-based thermoplastic elastomer component present in the innermost layer is 0.1 g/10 min to 1.4 g/10 min. According to claim 1 or 2,
The sealant film constituting the sealant layer is an exterior material for an electrical storage device, characterized in that the tensile yield strength at 80°C is 3.5 MPa to 15.0 MPa. According to claim 1 or 2,
An exterior material for an electrical storage device, wherein the metal foil layer and the sealant layer are bonded to each other through an adhesive layer. In clause 7,
An exterior material for an electrical storage device, wherein the adhesive layer is made of an adhesive containing an olefin-based resin having a carboxyl group and a polyfunctional isocyanate compound. A power storage device main body,
Equipped with an exterior material for an electrical storage device according to claim 1 or 2,
A power storage device characterized in that the main body of the power storage device is exteriorized with the exterior material. delete