阅读说明：本技术 蓄电装置用外包装材料及蓄电装置 (Outer packaging material for electricity storage device and electricity storage device ) 是由 吉野贤二 唐津诚 于 2017-07-07 设计创作，主要内容包括：本发明涉及蓄电装置用外包装材料及蓄电装置。本发明的蓄电装置用外包装材料构成为包含作为外侧层的耐热性树脂层(2)、作为内侧层的密封层(3)、和配置于这两层之间的金属箔层(4),密封层(3)的至少最内层(7)含有弹性体改性烯烃系树脂,所述弹性体改性烯烃系树脂包含烯烃系热塑性弹性体改性均聚丙烯或/及烯烃系热塑性弹性体改性无规共聚物,所述烯烃系热塑性弹性体改性无规共聚物是含有丙烯及除丙烯以外的其他共聚成分作为共聚成分的无规共聚物的烯烃系热塑性弹性体改性体。通过该结构,可提供即使长时间暴露在高温环境下也仍然能够良好地维持外包装材料密封部的密封性的蓄电装置用外包装材料。(The present invention relates to an outer package for an electricity storage device and an electricity storage device. The outer covering material for an electricity storage device of the present invention is configured to include 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 the two layers, wherein at least an innermost layer (7) of the sealant layer (3) contains an elastomer-modified olefin-based resin including an olefin-based thermoplastic elastomer-modified homopolypropylene or/and an olefin-based thermoplastic elastomer-modified random copolymer that is a random copolymer containing propylene and a copolymerization component other than propylene as a copolymerization component. With this configuration, it is possible to provide an outer cover for an electric storage device, which can maintain the sealing property of the outer cover sealing portion satisfactorily even when exposed to a high-temperature environment for a long time.)

1. An outer package for a power storage device, characterized by comprising a heat-resistant resin layer as an outer layer, a sealant layer as an inner layer, and a metal foil layer disposed between the two layers,

the sealing layer is formed from 1 layer to a plurality of layers, at least the innermost layer of the sealing layer contains an elastomer-modified olefinic resin,

the elastomer-modified olefinic resin comprises an olefinic thermoplastic elastomer-modified homopolypropylene or/and an olefinic thermoplastic elastomer-modified random copolymer,

the olefin-based thermoplastic elastomer-modified random copolymer is a random copolymer containing propylene and a copolymerization component other than propylene as a copolymerization component.

2. The electricity storage device exterior material according to claim 1, wherein a content of the olefinic thermoplastic elastomer in the innermost layer is 0.1 mass% or more and less than 20 mass%.

3. The electricity storage device exterior material according to claim 1 or 2, wherein the melting point of the elastomer-modified olefin-based resin constituting the innermost layer is 160 ℃ to 180 ℃.

4. The outer package for power storage devices according to claim 1 or 2, wherein the olefinic thermoplastic elastomer component present in the innermost layer has a plurality of crystallization temperatures, and a lowest crystallization temperature among the plurality of crystallization temperatures is 40 ℃ to 80 ℃.

5. The electricity storage device exterior packaging material according to claim 1 or 2, wherein the olefinic thermoplastic elastomer component present in the innermost layer has an MFR of 0.1g/10 min to 1.4g/10 min.

6. The outer packaging material for power storage devices according to claim 1 or 2, wherein the seal film constituting the seal layer has a tensile yield strength of 3.5MPa to 15.0MPa at 80 ℃.

7. The outer package for power storage devices according to claim 1 or 2, wherein the metal foil layer and the sealant layer are bonded to each other through an adhesive layer.

8. The exterior material for a power storage device according to claim 7, wherein the adhesive layer is formed of an adhesive containing an olefin resin having a carboxyl group and a polyfunctional isocyanate compound.

9. An electricity storage device is characterized by comprising:

an electricity storage device main body section; and

the outer packaging material for a power storage device according to any one of claims 1 to 8,

the power storage device main body is externally coated with the outer coating material.

Technical Field

The present invention relates to an outer package for a power storage device such as a battery or a capacitor (capacitor) used in a portable device such as a smartphone or a tablet computer, or a battery or a capacitor used in a power storage application of a hybrid vehicle, an electric vehicle, wind power generation, solar power generation, or night power, and to a power storage device.

In the present specification and claims, the term "tensile yield strength" means the tensile yield strength measured under the conditions of a specimen width of 15mm, an inter-scale distance of 50mm, and a tensile speed of 100 mm/min in accordance with JIS K7127-1999 (tensile test method).

Background

Lithium ion secondary batteries are widely used as power sources for, for example, notebook computers, video cameras, cellular phones, and the like. As the lithium ion secondary battery, a battery having a structure in which the periphery of a battery main body (main body including a positive electrode, a negative electrode, and an electrolyte) is surrounded by a case is used. As this material for a case (outer covering material), for example, a material having a structure in which an outer layer formed of a heat-resistant resin film, an aluminum foil layer, and an inner layer formed of a thermoplastic resin film are sequentially bonded and integrated is known (see patent document 1).

The power storage device is configured by sandwiching a power storage device body between a pair of outer packaging materials, and sealing the outer packaging materials by fusion-bonding (heat-sealing) peripheral edges of the outer packaging materials. By sufficiently sealing the electrolyte by such heat-seal bonding, leakage of the electrolyte can be prevented.

Patent document 1: japanese patent laid-open publication No. 2005-22336

Disclosure of Invention

Problems to be solved by the invention

Such batteries such as lithium ion secondary batteries are assumed to be used in a normal temperature environment such as a notebook computer and a mobile phone.

However, in recent years, with the diversification of the use applications of the lithium ion secondary battery, new applications of the battery, which are used outside exposed to a high temperature environment, including the use in an automobile application, are increasing.

For example, in the use for automobile applications, when an automobile is parked outdoors in summer, the temperature becomes very high, and therefore, in the case of a battery such as a lithium ion secondary battery, it is desired to develop an exterior material capable of maintaining the sealing property of the exterior material sealing portion satisfactorily even when exposed to such a high temperature environment for a long time.

The present invention has been made in view of the above-described background of the art, and an object thereof is to provide an outer package for a power storage device and a power storage device, which can maintain the sealing property of the outer package sealing portion satisfactorily even when exposed to a high-temperature environment for a long time.

Means for solving the problems

To achieve the above object, the present invention provides the following means.

[1] An outer package for a power storage device, characterized by comprising a heat-resistant resin layer as an outer layer, a sealant layer as an inner layer, and a metal foil layer disposed between the two layers,

the sealing layer is formed from 1 layer to a plurality of layers, at least the innermost layer of the sealing layer contains an elastomer-modified olefinic resin,

the elastomer-modified olefinic resin comprises an olefinic thermoplastic elastomer-modified homopolypropylene or/and an olefinic thermoplastic elastomer-modified random copolymer,

the olefin-based thermoplastic elastomer-modified random copolymer is a random copolymer containing propylene and a copolymerization component other than propylene as a copolymerization component.

[2] The outer cover for a power storage device according to the above item 1, wherein a content of the olefinic thermoplastic elastomer in the innermost layer is 0.1% by mass or more and less than 20% by mass.

[3] The outer covering material for a power storage device according to the above 1 or 2, wherein the melting point of the elastomer-modified olefinic resin constituting the innermost layer is 160 ℃ to 180 ℃.

[4] The outer covering material for a power storage device according to any one of the above items 1 to 3, wherein the olefinic thermoplastic elastomer component present in the innermost layer has a plurality of crystallization temperatures, and a lowest crystallization temperature among the plurality of crystallization temperatures is 40 ℃ to 80 ℃.

[5] The outer covering material for a power storage device according to any one of the aforementioned items 1 to 4, wherein the MFR of the olefinic thermoplastic elastomer component present in the innermost layer is from 0.1g/10 min to 1.4g/10 min.

[6] The outer packaging material for a power storage device according to any one of the above items 1 to 5, wherein a tensile yield strength of a sealing film constituting the sealing layer at 80 ℃ is 3.5MPa to 15.0 MPa.

[7] The outer covering material for a power storage device according to any one of the above items 1 to 6, wherein the sealant layer is formed of a plurality of layers, a second sealant layer is disposed on a side closest to the metal foil layer in the sealant layer, and the second sealant layer contains 50 mass% or more of a propylene-ethylene random copolymer and does not contain an elastomer component.

[8] The outer covering material for a power storage device according to any one of the above items 1 to 7, wherein the metal foil layer and the sealing layer are bonded via an adhesive layer.

[9] The outer packaging material for a power storage device according to item 8 above, wherein the adhesive layer is formed of an adhesive containing an olefin resin having a carboxyl group and a polyfunctional isocyanate compound.

[10] An electricity storage device is characterized by comprising:

an electricity storage device main body section; and

the outer packaging material for an electricity storage device as described in any one of the aforementioned items 1 to 9,

the power storage device main body is externally coated with the outer coating material.

ADVANTAGEOUS EFFECTS OF INVENTION

[1] In the invention according to (1), since at least the innermost layer of the sealing layer constituting the exterior material contains the specific elastomer-modified olefinic resin, the initial sealing strength between the exterior materials can be sufficiently ensured even in a high-temperature environment, and the sufficient sealing strength can be maintained even when the exterior material is left in a high-temperature environment for a long time (for example, in a vehicle interior in summer).

[2] In the invention as described above, the content of the olefinic thermoplastic elastomer in the innermost layer of the sealant layer is 0.1 mass% or more and less than 20 mass%, whereby the film strength of the sealant layer is increased, and therefore, breakage (cracking) from the initiation of the sealant layer is less likely to occur.

[3] In the invention as described above, the melting point of the elastomer-modified olefinic resin constituting the innermost layer of the sealing layer is 160 to 180 ℃, and therefore, the flow-out of the sealing layer can be sufficiently suppressed when the outer packaging material is heat-sealed, and the heat resistance under the high-temperature environment is also excellent.

[4] In the invention (2), since the lowest crystallization temperature is 40 to 80 ℃, the bonding time at normal temperature (bonding time at heat sealing) can be shortened.

[5] In the invention according to (1), the resin (the olefin-based resin of the innermost layer) is less likely to be melted out at the time of heat sealing, and therefore, a higher adhesive strength can be secured.

[6] In the invention according to (1), since the sealant film having a tensile yield strength of 3.5MPa to 15.0MPa at 80 ℃ is used for the sealant layer, even when the power storage device is used in a high-temperature environment (for example, in a vehicle in summer) for a long time, cracking of the outer package due to an increase in internal pressure can be prevented.

[7] In the invention according to (1), since the second sealant layer located closest to the metal foil layer contains not less than 50 mass% of a propylene-ethylene random copolymer and does not contain an elastomer component, the adhesion to the metal foil layer side is improved, and delamination does not easily occur even if deformation occurs. Further, since the second sealant layer located closest to the metal foil layer does not contain an elastomer component, the electrolyte solution does not enter the vicinity of the metal foil layer due to silver streaks (cracks, separation of an interface without gaps) that may occur at the interface between the propylene-ethylene random copolymer and the elastomer component, and sufficient insulation properties can be ensured.

[8] In the invention of (1), the interlayer adhesion between the metal foil layer and the sealant layer can be further improved.

[9] In the invention as described above, the adhesive layer is formed of the adhesive containing the olefin resin having a carboxyl group and the polyfunctional isocyanate compound, and therefore, the electrolyte resistance can be further improved.

[10] The present invention can provide a power storage device having excellent high-temperature durability formed by exterior-packaging an exterior material that can sufficiently ensure initial seal strength between exterior materials even in a high-temperature environment and can maintain sufficient seal strength even when left in a high-temperature environment for a long time (for example, in a vehicle in summer).

Drawings

Fig. 1 is a sectional view showing an embodiment of an outer package for a power storage device according to the present invention.

Fig. 2 is a cross-sectional view showing another embodiment of the outer package for a power storage device according to the present invention.

Fig. 3 is a cross-sectional view showing an embodiment of the power storage device according to the present invention.

Fig. 4 is a perspective view showing a separated state before heat sealing of an outer covering material (a planar object), a power storage device main body, and an outer covering case (a molded body molded into a three-dimensional shape) constituting the power storage device of fig. 3.

Description of the reference numerals

1 … outer packaging material for electricity storage device

2 … Heat-resistant resin layer (outer layer)

3 … sealing 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 (sealant closest to foil side)

10 … outer case for electricity storage device

15 … external packing member

30 … electric storage device

31 … electric storage device body section

Detailed Description

Fig. 1 shows an embodiment of an outer package 1 for a power storage device according to the present invention. This outer package 1 for a power storage device is used as an outer package for a lithium-ion secondary battery, for example. The outer package material 1 for the electricity storage device may be used as it is without being subjected to molding, or may be used in the form of an outer package case 10 by being subjected to molding such as deep drawing molding or bulging molding (see fig. 4).

The outer package 1 for a power storage device includes: a base material layer (outer layer) 2 is laminated and integrated on one surface of a metal foil layer 4 via a first adhesive layer 5, and an inner sealant layer (inner layer) 3 is laminated and integrated on the other surface of the metal foil layer 4 via a second adhesive layer 6 (see fig. 1 and 2).

In outer package 1 of fig. 1, inner seal layer (inner layer) 3 is formed as a single layer (1 layer) of first seal layer 7. Therefore, the first sealing layer 7 is disposed on the innermost side (the first sealing layer 7 is the innermost layer).

In the exterior material 1 of fig. 2, the inner sealant layer (inner layer) 3 has a 2-layer laminated structure including a first sealant layer 7 as an innermost layer and a second sealant layer 8 disposed on a side closest to the metal foil layer 4, and the first sealant layer 7 is disposed on the innermost layer.

In the present invention, the inner sealant layer (inner layer) 3 plays the following roles: the outer packaging material is provided with excellent chemical resistance even against highly corrosive electrolyte solutions used in lithium ion secondary batteries and the like, and heat sealability is imparted to the outer packaging material. The seal layer (inner layer) 3 is formed of an unstretched seal film.

In the present invention, the sealing layer (inner layer) 3 may be formed of 1 layer or a plurality of 2 or more layers, and at least the innermost layer (first sealing layer) 7 of the sealing layer (inner layer) 3 is configured to contain an elastomer-modified olefin resin.

The elastomer-modified olefinic resin (polypropylene block copolymer) preferably contains an olefinic thermoplastic elastomer-modified homopolypropylene or/and an olefinic thermoplastic elastomer-modified random copolymer, and the olefinic thermoplastic elastomer-modified random copolymer is a random copolymer containing "propylene" and "a copolymerization component other than propylene" as copolymerization components, and the "copolymerization component other than propylene" is not particularly limited, and examples thereof include an olefin component such as ethylene, 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, and butadiene. The olefinic thermoplastic elastomer is not particularly limited, and examples thereof include EPR (ethylene propylene rubber), propylene-butene elastomer, propylene-butene-ethylene elastomer, EPDM (ethylene-propylene-diene rubber), and the like, and among them, EPR (ethylene propylene rubber) is preferably used.

The elastomer-modified olefinic resin may be graft polymerized as a form of "modification of olefinic thermoplastic elastomer" or may be modified in another form.

The elastomer-modified olefinic resin can be produced, for example, by the following reactor production method. This represents only 1 example, and is not particularly limited to the production by such a production method.

First, a Ziegler-Natta catalyst, a cocatalyst, propylene and hydrogen are supplied to a first reactor, and homopolypropylene is polymerized. The resulting homopolypropylene is moved to the second reactor in a state of containing unreacted propylene and the Ziegler-Natta catalyst. Further, propylene and hydrogen were added to the second reactor to polymerize homopolypropylene. The resulting homopolypropylene is moved to the third reactor in a state of containing unreacted propylene and the Ziegler-Natta catalyst. The elastomer-modified olefinic resin can be produced by further adding ethylene, propylene and hydrogen to the third reactor and polymerizing an ethylene-propylene rubber (EPR) obtained by copolymerizing ethylene and propylene. For example, the elastomer-modified olefinic resin can be produced by adding a solvent and conducting the production in a liquid phase, and the elastomer-modified olefinic resin can be produced by conducting the reaction in a gas phase without using a solvent.

The content of the olefinic thermoplastic elastomer in the innermost layer (first sealant layer) 7 of the sealant layer 3 is preferably 0.1 mass% or more and less than 20 mass%. The content of homopolypropylene (a portion that has not been modified with the olefin-based thermoplastic elastomer) or/and the random copolymer (a portion that has not been modified with the olefin-based thermoplastic elastomer) in the innermost layer (first sealing layer) 7 of the sealing layer 3 is preferably 80 mass% or more and 99 mass% or less.

The melting point of the elastomer-modified olefinic resin constituting the innermost layer (first sealant layer) 7 of the sealant layer 3 is preferably in the range of 160 to 180 ℃. The flow-out of the sealing layer 3 can be sufficiently suppressed when the outer package material is heat-sealed, and the heat resistance in a high-temperature environment is also excellent. Among these, the melting point of the elastomer-modified olefinic resin constituting the innermost layer (first sealing layer) 7 of the sealing layer 3 is preferably 163 ℃ or higher, and particularly preferably in the range of 163 to 169 ℃. The melting point is a melting point measured by a Differential Scanning Calorimetry (DSC) method in accordance with JIS K7121-1987.

The olefinic thermoplastic elastomer component (only this component) present in the innermost layer (first sealant layer) 7 preferably has a plurality of crystallization temperatures. When the temperature is higher than the melting point of the olefin-based resin, the resin (the olefin-based resin in the innermost layer) is less likely to melt out during bonding. In the case of a plurality of crystallization temperatures, the lowest crystallization temperature among the plurality of crystallization temperatures is preferably in the range of 40 to 80 ℃, and more preferably in the range of 40 to 75 ℃. By setting the minimum crystallization temperature to 40 to 80 ℃, an effect of shortening the bonding time at room temperature (bonding time at heat sealing) can be obtained. The above-mentioned crystallization temperature is a crystallization temperature (crystallization peak) measured by a Differential Scanning Calorimetry (DSC) method in accordance with JIS K7121-1987.

The MFR of the olefinic thermoplastic elastomer component (only this component) present in the innermost layer (first sealant layer) 7 is preferably 0.1g/10 min to 1.4g/10 min, and in this case, the resin (olefinic resin of the innermost layer) becomes less likely to melt out at the time of heat sealing, and therefore a greater adhesive strength can be ensured. Among these, the MFR of the olefinic thermoplastic elastomer component (only this component) present in the innermost layer (first sealant layer) 7 is more preferably 0.1g/10 min to 1.0g/10 min, and particularly preferably 0.1g/10 min to 0.6g/10 min. The MFR (melt flow rate) is an MFR measured at 230 ℃ under 2.16kg in accordance with JIS K7210-1-2014.

The seal film constituting the seal layer 3 preferably has a tensile yield strength of 3.5MPa to 15.0MPa at 80 ℃. For example, when the sealing layer 3 is composed of only the first sealing layer 7, the tensile yield strength at 80 ℃ of the first sealing film is preferably 3.5 to 15.0MPa, and when the sealing layer 3 is composed of a laminate of the first sealing layer 7 and the second sealing layer 8, the tensile yield strength at 80 ℃ of the laminated sealing film is preferably 3.5 to 15.0 MPa. When the sealing layer 3 has a plurality of layers of 3 or more, the tensile yield strength at 80 ℃ of the laminated sealing film is preferably 3.5MPa to 15.0 MPa. By setting the tensile yield strength of the sealing film constituting the sealing layer 3 to 3.5MPa to 15.0MPa at 80 ℃, as described above, it is possible to prevent cracking of the outer covering material due to an increase in internal pressure even when the power storage device is used in a high-temperature environment (for example, in a vehicle in summer) for a long time. Among them, the tensile yield strength at 80 ℃ of the sealing film constituting the sealing layer 3 is particularly preferably 4MPa to 12 MPa.

The thickness of the innermost layer (first sealing layer) 7 is preferably 30 μm or more, and in this case, there is an advantage that the toughness of the first sealing layer 7 can be improved. Among them, the thickness of the innermost layer (first sealing layer) 7 is more preferably 30 μm to 100 μm.

When the second sealing layer 8 is provided, the thickness of the second sealing layer 8 is preferably 3 μm to 60 μm, and more preferably 5 μm to 20 μm. When the second sealing layer 8 is provided, the resin forming the second sealing layer 8 is not particularly limited, and examples thereof include a propylene-ethylene random copolymer, homopolypropylene, polyethylene, and olefin-based thermoplastic elastomer-modified homopolypropylene, an olefin-based thermoplastic elastomer-modified random copolymer (an olefin-based thermoplastic elastomer-modified random copolymer containing "propylene" and "a copolymerization component other than propylene" as a copolymerization component), and the like.

The thickness of the sealing layer 3 is preferably set to 30 μm to 200 μm.

In the present invention, the sealant layer 3 is formed of a plurality of layers, and has an innermost layer (first sealant layer) 7 containing the elastomer-modified olefin resin, and a second sealant layer 8 (see fig. 2) disposed on the side closest to the metal foil layer 4, and the second sealant layer is preferably configured to contain 50 mass% or more of a propylene-ethylene random copolymer and not to contain an elastomer component. In the case of such a structure, the second sealant layer 8 located on the side closest to the metal foil layer 4 is configured to contain 50 mass% or more of a propylene-ethylene random copolymer and not to contain an elastomer component, and therefore, adhesiveness to the metal foil layer side is improved, and even if deformation occurs, interlayer peeling is less likely to occur. Further, since the second sealant 8 located closest to the metal foil layer 4 does not contain an elastomer component, the electrolyte solution does not enter the vicinity of the metal foil layer due to silver streaks (cracks, separation of an interface without gaps) that may occur at the interface between the propylene-ethylene random copolymer and the elastomer component, and sufficient insulation properties can be ensured. Among these, the second sealant layer is more preferably configured to contain 70 mass% or more of a propylene-ethylene random copolymer and not to contain an elastomer component. The term "composition containing no elastomer component" as used herein means that neither an elastomer component nor an elastomer-modified resin is mixed (doped).

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

The method of laminating the sealing film constituting the sealing layer (inner layer) 3 on the metal foil layer 4 is not particularly limited, and examples thereof include a dry lamination method and a sandwich lamination method (a method of extruding an adhesive film such as acid-modified polypropylene, laminating the adhesive film between the metal foil and the sealing film with a sandwich therebetween, and then thermally laminating the adhesive film with a hot roll).

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 a heat-sealing temperature when heat-sealing the exterior material is performed is used. As the heat-resistant resin, a heat-resistant resin having a melting point higher than that of the sealing layer 3 by 10 ℃ or more is preferably used, and a heat-resistant resin having a melting point higher than that of the sealing layer 3 by 20 ℃ or more is particularly preferably used.

The heat-resistant resin layer (outer layer) 2 is not particularly limited, and examples thereof include polyamide films such as nylon films, polyester films, and the like, and stretched films of these films can be preferably used. Among them, as the heat-resistant resin layer 2, 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 a biaxially stretched polyethylene naphthalate (PEN) film is particularly preferably used. The nylon film is not particularly limited, and examples thereof include a nylon 6 film, a nylon 6,6 film, and a nylon MXD film. The heat-resistant resin layer 2 may be formed of a single layer, or may be formed of a plurality of layers including a polyester film/a polyamide film (a plurality of layers including a PET film/a nylon film, etc.), for example. In the case of the multilayer, the polyester film side may be disposed at the outermost side.

The thickness of the outer layer (base material layer) 2 is preferably 2 to 50 μm. When a polyester film is used, the thickness is preferably 5 to 40 μm, and when a nylon film is used, the thickness is preferably 15 to 50 μm. By setting the preferable lower limit value or more, sufficient strength as an outer covering material can be secured, and by setting the preferable upper limit value or less, stress at the time of forming such as bulging forming or drawing forming can be reduced, and formability can be improved.

In the outer package material for a power storage device according to the present invention, the metal foil layer 4 plays a role of imparting gas barrier properties (blocking intrusion of oxygen and moisture) to the outer package material 1. The metal foil layer 4 is not particularly limited, and examples thereof include aluminum foil, SUS foil (stainless steel foil), and copper foil, and among these, aluminum foil and SUS foil (stainless steel foil) are preferably used. The thickness of the metal foil layer 4 is preferably 10 μm to 120 μm. By having the thickness of 10 μm or more, pinholes can be prevented from being generated during rolling in the production of the metal foil, and by having the thickness of 120 μm or less, stress during forming such as bulging forming and drawing can be reduced, and formability can be improved.

It is preferable that at least the inner surface (the surface on the second adhesive layer 6 side) of the metal foil layer 4 is subjected to chemical conversion treatment. By performing such chemical conversion treatment, corrosion of the surface of the metal foil by the contents (electrolyte solution of the battery, etc.) can be sufficiently prevented. For example, the metal foil is subjected to a chemical conversion treatment by performing the following treatment. That is, for example, the chemical conversion treatment is performed by applying any one of aqueous solutions 1) to 3) described below to the surface of the degreased metal foil and then drying the applied aqueous solution.

1) An aqueous solution of a mixture comprising:

phosphoric acid;

chromic acid; and

at least 1 compound selected from the group consisting of metal salts of fluoride and non-metal salts of fluoride,

2) an aqueous solution of a mixture comprising:

phosphoric acid;

at least 1 resin selected from the group consisting of acrylic resins, chitosan (chitosan) derivative resins, and phenolic resins; and

at least 1 compound selected from the group consisting of chromic acid and chromium (III) salts,

3) an aqueous solution of a mixture comprising:

phosphoric acid;

at least 1 resin selected from the group consisting of acrylic resins, chitosan derivative resins, and phenolic resins;

at least one compound selected from the group consisting of chromic acid and chromium (III) salts; and

at least 1 compound selected from the group consisting of metal salts of fluoride and non-metal salts of fluoride.

The chemical conversion coating is preferably 0.1mg/m in terms of chromium adhesion (per surface)²～50mg/m²Particularly preferably 2mg/m²～20mg/m²。

The first adhesive layer (outer adhesive layer) 5 is not particularly limited, and examples thereof include a urethane polyolefin adhesive layer, a urethane adhesive layer, a polyester urethane adhesive layer, and a polyether urethane adhesive layer. The thickness of the first adhesive layer 5 is preferably set to 1 μm to 6 μm. Among them, the thickness of the first adhesive layer 5 is particularly preferably set to 1 μm to 3 μm from the viewpoint of making the outer package 1 thinner and lighter.

The second adhesive layer (inner adhesive layer) 6 is not particularly limited, and for example, those listed as the first adhesive layer 5 may be used, but a polyolefin adhesive which is less swollen by an electrolytic solution is preferably used. Among these, the second adhesive layer (inner adhesive layer) 6 is particularly preferably formed of an adhesive containing an olefin resin having a carboxyl group and a polyfunctional isocyanate compound. The second adhesive layer can be formed by dry lamination of the adhesive. Alternatively, the second adhesive layer (inner adhesive layer) 6 is preferably formed of an olefin resin having a carboxyl group. In this case, the second adhesive layer can be formed by melt extrusion of an olefin resin having a carboxyl group and extrusion lamination. The olefinic resin having a carboxyl group is not particularly limited, and examples thereof include carboxylic acid-modified olefinic resins such as maleic acid-modified polypropylene, maleic acid-modified polyethylene, acrylic acid-modified polypropylene, acrylic acid-modified polyethylene, methacrylic acid-modified polypropylene, methacrylic acid-modified polyethylene, 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 them, the thickness of the second adhesive layer 6 is particularly preferably set to 1 μm to 3 μm from the viewpoint of making the outer covering thinner and lighter.

By molding (deep drawing, bulging, etc.) the exterior material 1 of the present invention, an exterior case (battery case, etc.) 10 can be obtained (fig. 4). The outer package 1 of the present invention may be used without molding (fig. 4).

Fig. 3 shows an embodiment of a power storage device 30 configured using the exterior material 1 of the present invention. The power storage device 30 is a lithium ion secondary battery. In the present embodiment, as shown in fig. 3 and 4, the outer package member 15 is composed of the outer package case 10 obtained by molding the outer package 1 and the planar outer package 1. Then, the power storage device 30 of the present invention is configured by housing a substantially rectangular parallelepiped power storage device main body portion (electrochemical element or the like) 31 in a housing recess of an outer case 10 obtained by molding the outer case 1 of the present invention, disposing the outer case 1 of the present invention above the power storage device main body portion 31 without molding so that the sealing layer 3 side is an inner side (lower side), and sealing and joining a peripheral edge portion of the sealing layer 3 of the planar outer case 1 and the sealing layer 3 of the flange portion (sealing peripheral edge portion) 29 of the outer case 10 by heat sealing (see fig. 3 and 4). The surface of the outer case 10 on the inner side of the housing recess is the sealing layer 3, and the outer surface of the housing recess is the base material layer (outer layer) 2 (see fig. 4).

In fig. 3, reference numeral 39 denotes a heat-sealed portion formed by joining (welding) the peripheral edge portion of the outer package 1 to the flange portion (sealing peripheral edge portion) 29 of the outer case 10. In the power storage device 30, the tip end portions of the tabs connected to the power storage device main body portion 31 are led out of the outer cover member 15, and are not shown in the drawings.

The power storage device body 31 is not particularly limited, and examples thereof include a battery body, a capacitor (capacitor) body, and a capacitor body.

The width of the heat-seal land 39 is preferably set to 0.5mm or more. By setting the thickness to 0.5mm or more, sealing can be reliably performed. The width of the heat-seal land 39 is preferably set to 3mm to 15 mm.

In the above embodiment, the outer package member 15 is formed of the outer package case 10 obtained by molding the outer package 1 and the planar outer package 1 (see fig. 3 and 4), but is not particularly limited to this combination, and for example, the outer package member 15 may be formed of a pair of planar outer packages 1 or a pair of outer package cases 10.

Examples

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 contains an EPR-modified homopolypropylene and an EPR-modified ethylene-propylene random copolymer. The above EPR represents an ethylene-propylene rubber. The content of the elastomer component in the elastomer-modified olefin-based resin a was 15% by mass. The melting point of the elastomer-modified olefin-based resin A was 166 ℃.

(elastomer-modified olefin-based resin B)

The elastomer-modified olefin-based resin B comprises a propylene-butene elastomer-modified propylene-butene homopolymer and an ethylene-propylene random copolymer. The content of the elastomer component in the elastomer-modified olefin-based resin B was 18% by mass. The melting point of the elastomer-modified olefin-based resin B was 164 ℃.

(elastomer-modified olefin-based resin C)

The elastomer-modified olefin-based resin C contains a propylene-butene-ethylene elastomer-modified homopolypropylene and a propylene-propylene random copolymer. The content of the elastomer component in the elastomer-modified olefin-based resin C was 16% by mass. The melting point of the elastomer-modified olefin-based resin C was 164 ℃.

< example 1 >

A chemical conversion treatment solution containing phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol was applied to both surfaces of an aluminum foil 4 having a thickness of 35 μm, and then dried at 180 ℃. The chemical conversion coating had a chromium deposit amount of 10mg/m per surface²。

Next, a biaxially stretched nylon 6 film 2 having a thickness of 15 μm was dry-laminated (bonded) on one surface of the aluminum foil 4 on which the chemical conversion treatment was completed, via a two-pack curable urethane adhesive (outer adhesive) 5.

Next, a sealing film (first sealing layer) 7 having a thickness of 80 μm and formed of an elastomer-modified olefin resin a was extruded, and then the other surface of the aluminum foil 4 after dry lamination was laminated on one surface of the sealing film 7(3) via a two-pack curable urethane adhesive (inner adhesive layer) 6, and dry lamination was performed by sandwiching and pressure-bonding the other surface between a rubber nip roller and a laminating roller heated to 100 ℃, and then cured (heated) at 50 ℃ for 5 days, thereby obtaining an outer packaging material 1 for an electric storage device having the structure shown in fig. 1.

< example 2 >

An outer cover material 1 for an electric storage device having a structure shown in fig. 1 was obtained in the same manner as in example 1, except that a two-pack curing type acrylic adhesive 6 was used instead of the two-pack curing type urethane adhesive as the inner adhesive 6.

< example 3 >

A chemical conversion treatment solution containing phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol was applied to both surfaces of an aluminum foil 4 having a thickness of 35 μm, and then dried at 180 ℃. The chemical conversion coating had a chromium deposit amount of 10mg/m per surface²。

Next, a biaxially stretched nylon 6 film 2 having a thickness of 15 μm was dry-laminated (bonded) on one surface of the aluminum foil 4 on which the chemical conversion treatment was completed, via a two-pack curable urethane adhesive 5.

Subsequently, a maleic anhydride-modified polypropylene film (inner adhesive layer) 6 having a thickness of 4 μm, a propylene-ethylene random copolymer film (second sealant layer) 8 having a thickness of 8 μm, and an elastomer-modified olefin-based resin a film (first sealant layer) 7 having a thickness of 72 μm were co-extruded, and they were sequentially laminated on the other surface of the aluminum foil 4 after dry lamination, and they were sandwiched between a rubber nip roller and a laminating roller heated to 100 ℃ and pressure-bonded to perform dry lamination, and then cured (heated) at 50 ℃ for 5 days, thereby obtaining an outer covering material 1 for an electric storage device having a structure shown in fig. 2.

< example 4 >

A chemical conversion treatment solution containing phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol was applied to both surfaces of an aluminum foil 4 having a thickness of 35 μm, and then dried at 180 ℃. The chemical conversion coating had a chromium deposit amount of 10mg/m per surface²。

Next, a biaxially stretched nylon 6 film 2 having a thickness of 15 μm was dry-laminated (bonded) on one surface of the aluminum foil 4 on which the chemical conversion treatment was completed, via a two-pack curable urethane adhesive 5.

Next, a maleic anhydride-modified polypropylene film (inner adhesive layer) 6 having a thickness of 4 μm and an elastomer-modified olefin-based resin a film 3 having a thickness of 80 μm were co-extruded, and they were sequentially laminated on the other surface of the aluminum foil 4 after dry lamination, and dry lamination was performed by sandwiching and pressure-bonding the film between a rubber nip roller and a lamination roller heated to 100 ℃, and then, aging (heating) was performed at 50 ℃ for 5 days, thereby obtaining an outer cover 1 for an electric storage device having a structure shown in fig. 1.

< example 5 >

An outer cover 1 for an electricity storage device having a structure shown in fig. 1 was obtained in the same manner as in example 1, except that the elastomer-modified olefinic resin B was used instead of the elastomer-modified olefinic resin a.

< example 6 >

An outer cover 1 for an electricity storage device having a structure shown in fig. 1 was obtained in the same manner as in example 1, except that the elastomer-modified olefinic resin C was used instead of the elastomer-modified olefinic resin a.

< example 7 >

A chemical conversion treatment solution containing phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol was applied to both surfaces of an aluminum foil 4 having a thickness of 35 μm, and then dried at 180 ℃. The chemical conversion coating had a chromium deposit amount of 10mg/m per surface²。

Next, a biaxially stretched nylon 6 film 2 having a thickness of 15 μm was dry-laminated (bonded) on one surface of the aluminum foil 4 on which the chemical conversion treatment was completed, via a two-pack curable urethane adhesive 5.

Next, a two-pack curable urethane adhesive (inner adhesive layer) 6 was applied to the other surface of the aluminum foil 4 after dry lamination, and then a homopolypropylene film (second sealant layer) 8 having a thickness of 8 μm and an elastomer-modified olefin-based resin a film (first sealant layer) 7 having a thickness of 72 μm were co-extruded on the applied surface in this manner, and the laminate was sandwiched between a rubber nip roll and a laminating roll heated to 100 ℃ and pressure-bonded to perform dry lamination, and then cured (heated) at 50 ℃ for 5 days, thereby obtaining an outer cover 1 for an electric storage device having a structure shown in fig. 2.

< example 8 >

An outer cover 1 for a power storage device having a structure shown in fig. 2 was obtained in the same manner as in example 7, except that a propylene-ethylene random copolymer film 8 having a thickness of 8 μm was used as the second sealing layer 8 instead of the homopolypropylene film having a thickness of 8 μm.

< example 9 >

An outer cover material 1 for an electric storage device having a structure shown in fig. 2 was obtained in the same manner as in example 8, except that a two-pack curing type acrylic adhesive 6 was used instead of the two-pack curing type urethane adhesive as the inner adhesive 6.

< comparative example 1 >

An outer covering material for an electricity storage device having a 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 olefinic resin a.

< comparative example 2 >

A chemical conversion treatment solution containing phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol was applied to both surfaces of an aluminum foil 4 having a thickness of 35 μm, and then dried at 180 ℃. The chemical conversion coating had a chromium deposit amount of 10mg/m per surface²。

Next, a biaxially stretched nylon 6 film 2 having a thickness of 15 μm was dry-laminated (bonded) on one surface of the aluminum foil 4 on which the chemical conversion treatment was completed, via a two-pack curable urethane adhesive 5.

Next, the other surface of the aluminum foil 4 after dry lamination was coated with a two-pack curable acrylic adhesive 6, and then a structure obtained by co-extruding an elastomer-modified olefin-based resin a film (second sealant) 8 having a thickness of 68 μm and a propylene-ethylene random copolymer film (first sealant) 7 having a thickness of 12 μm was sequentially laminated on the coated surface, and dry lamination was performed by sandwiching and pressure-bonding the films between a rubber nip roll and a laminating roll heated to 100 ℃, and then, aging (heating) was performed at 50 ℃ for 5 days, thereby obtaining an outer covering material for an electric storage device having a structure shown in fig. 2.

The tensile yield strength (see table 1) of the seal film (thickness 80 μm)3 used for producing the outer packaging materials of examples 1 to 9 and comparative examples 1 to 2 was measured as follows.

< method for measuring tensile yield strength of seal film >

A type 2 test piece (length: 150mm or more) was prepared according to JIS K7127-1999 (tensile test method for plastic films) for an unstretched sealing film 3 (thickness: 80 μm) prepared in the same manner as used for other measurements, and a tensile yield strength was determined by conducting a tensile test under conditions of a specimen width of 15mm, an inter-jig distance of 100mm, an inter-scale distance of 50mm, and a tensile rate of 100 mm/min at 80 ℃. The load at the yield point in the S-S curve was taken as the tensile yield strength. After the test piece was mounted in the tensile test apparatus in the thermostatic bath set at 80 ℃, the test piece was left standing in the environment of 80 ℃ for 1 minute, and then the tensile test was performed in the environment of 80 ℃. The results of measuring the tensile yield strength at 80 ℃ are shown in Table 1.

The thickness of the test piece was set to 80 μm and measured, but for example, when the sealing film 3 having a thickness of 64 μm was used in a 2-layer laminate structure of the second sealant layer having a thickness of 6 μm and the first sealant layer having a thickness of 58 μm, a test piece having a thickness of 80 μm was produced and measured so that the thickness ratio of the 2 layers was not changed. That is, a test piece having a 2-layer laminated structure of the second sealing layer having a thickness of 7.5 μm and the first sealing layer having a thickness of 72.5 μm was prepared and measured. In the case of a laminate structure having 3 or more layers, a test piece having a thickness of 80 μm was prepared and measured in the same manner.

Each of the outer packaging materials for power storage devices obtained as described above was evaluated by the following measurement method.

< method for measuring initial seal strength at high temperature >

After cutting 2 test pieces 15mm wide by 150mm long from the obtained outer packaging material, the 2 test pieces were stacked with the inner side seal layers in contact with each other, and in this state, heat-sealing was performed by heating one side of a heat-seal apparatus (TP-701-a) using a TESTER SANGYO co., ltd, under conditions of a heat-seal temperature of 200 ℃, a seal pressure of 0.2MPa (gauge pressure) and a seal time of 2 seconds.

Next, with respect to a pair of outer packaging materials obtained by heat-sealing and joining the inner side seal layers as described above, the peel strength when the inner side seal layers of the sealed portion of the outer packaging material (test body) were peeled at 90 degrees at a tensile rate of 100 mm/min was measured as the seal strength (N/15mm width) in accordance with JIS Z0238-1998 using a tensile tester (AGS-5kNX) made by Shimadzu Access Corporation placed in a constant temperature bath. The seal strength at 100 ℃ and the seal strength at 120 ℃ were measured.

In the measurement of the seal strength at 100 ℃, the test piece was mounted in a tensile test apparatus in a thermostatic bath set to 100 ℃, then left to stand in an environment of 100 ℃ for 1 minute, and then measured in an environment of 100 ℃. The test piece was mounted in a tensile testing apparatus in a thermostatic bath set at 120 ℃ and then allowed to stand still at 120 ℃ for 1 minute, and then the seal strength at 120 ℃ was measured.

Both the seal strength at 100 ℃ and the seal strength at 120 ℃ were judged to be acceptable when the width was 27N/15mm or more.

Method for measuring sealing strength after 90 days in high-temperature environment

2 pieces of outer packaging materials cut into 200mm long × 150mm wide are stacked and arranged so that the sealing layers face each other with the inner side, and 3 edges thereof are heat-sealed at 180 ℃ and 0.2MPa for 2 seconds. After 10mL of the electrolyte was injected through the opening of the remaining 1 side which was not sealed, the remaining 1 side was also heat-sealed under the same sealing conditions as described above while extracting air, thereby producing a pseudo battery (test body). As the electrolyte, the following electrolyte was used: reacting lithium hexafluorophosphate (LiPF)₆) Dissolved in a mixed solvent in which Ethylene Carbonate (EC) and dimethyl carbonate (DMC) were mixed in an equivalent volume ratio to give a concentration of 1 mol/L.

The obtained battery was placed in a constant temperature and humidity apparatus manufactured by ESPEC corporation, and allowed to stand for 90 days under a condition of 80 ℃x90% Rh (exposure for 90 days under a high temperature and high humidity environment).

The simulated battery after the lapse of 90 days was taken out, the electrolyte was removed by opening 1 side, the inside was washed several times with water, and then 2 sheets of outer packaging materials were stacked and cut into a size of 15mm in width × 150mm in length so as to include the sealed portion of the 2 sheets of outer packaging materials, and with respect to the pair of outer packaging materials thus obtained, the peel strength when the pair of outer packaging materials were peeled at 90 degrees between the sealing layers of the sealed portion at a tensile rate of 100 mm/min was measured as the seal strength (N/15mm in width) according to JIS Z0238-1998 using a tensile tester (AGS-5kNX) manufactured by Shimadzu Access Corporation. The seal strength at 25 ℃ was measured. The sealing strength was 27N/15mm wide or more.

As is clear from table 1, the exterior materials for power storage devices of examples 1 to 9 according to the present invention can sufficiently ensure the initial seal strength even in a high-temperature environment, and can maintain the sufficient seal strength even when left in a high-temperature environment for a long time.

In contrast, in comparative examples 1 and 2, the initial seal strength in a high-temperature environment was insufficient, and the seal strength after long-term exposure to a high-temperature environment was greatly reduced.

Industrial applicability

The outer package for power storage devices manufactured using the seal film according to the present invention and the outer package for power storage devices according to the present invention can be used as outer packages for various power storage devices, and specific examples of the power storage devices include, for example:

an electric storage device such as a lithium secondary battery (lithium ion battery, lithium polymer battery, or the like);

a lithium ion capacitor;

an electric double layer capacitor; and so on.

The power storage device according to the present invention includes not only the power storage device described above as an example, but also an all-solid-state battery.

The present application claims priority from japanese patent application No. 2016-.

The terms and descriptions used herein are used for the purpose of describing embodiments of the present invention and are not intended to be limiting thereof. The present invention also allows any design change within the scope of claims as long as it does not depart from the gist thereof.