JP6969892B2 - Exterior materials for power storage devices and power storage devices - Google Patents

Description

The present invention is for storage devices such as batteries and capacitors used in mobile devices such as smartphones and tablets, hybrid vehicles, electric vehicles, wind power generation, solar power generation, and nighttime electricity storage. Regarding exterior materials and power storage devices.

In the present specification and the scope of the patent claim, the term "tensile yield strength" is based on JIS K7127-1999 (tensile test method), and has a sample width of 15 mm, a distance between marked lines of 50 mm, and a tensile speed of 100 mm / min. It means the tensile yield strength (tensile yield strength) obtained by measuring under the conditions of.

Lithium-ion secondary batteries are widely used as a power source for, for example, notebook computers, video cameras, mobile phones and the like. As the lithium ion secondary battery, a battery having a structure in which the periphery of the battery main body (main body including the positive electrode, the negative electrode and the electrolyte) is surrounded by a case is used. As the case material (exterior material), for example, a material in which 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 is known (Patent Documents). 1).

The power storage device is configured by sandwiching the power storage device main body with a pair of exterior materials and fusing-bonding (heat-sealing) the peripheral edges of the pair of exterior materials to each other. By sufficiently sealing with such a heat seal joint, leakage of the electrolytic solution can be prevented.

Japanese Unexamined Patent Publication No. 2005-22336

By the way, such a battery such as a lithium ion secondary battery is supposed 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 such uses of lithium ion secondary batteries, new uses such as those used for automobiles, which are exposed to a high temperature environment, are increasing. ..

For example, in the case of use for automobiles, the temperature is considerably high when the automobile is parked outdoors in the summer, and therefore, even as a battery such as a lithium ion secondary battery, it is used for a long period of time in such a high temperature environment. It is desired to develop an exterior material that can maintain good sealing performance of the sealed portion of the exterior material even when exposed.

INDUSTRIAL APPLICABILITY The present invention has been made in view of such a technical background, and provides an exterior material for a power storage device and a power storage device that can maintain good sealing performance of the seal portion of the exterior material even when exposed to a high temperature environment for a long period of time. The purpose is to provide.

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

[1] In an exterior material for a power storage device, which includes a heat-resistant resin layer as an outer layer, a sealant layer as an inner layer, and a metal foil layer arranged between both layers.
The sealant layer is composed of one layer or a plurality of layers, and at least the innermost layer of the sealant layer contains an elastomer-modified olefin resin.
The elastomer-modified olefin-based resin comprises an olefin-based thermoplastic elastomer-modified homopolypropylene and / and an olefin-based thermoplastic elastomer-modified random copolymer.
The olefin-based thermoplastic elastomer-modified random copolymer is an olefin-based thermoplastic elastomer-modified product of a random copolymer containing propylene and other copolymerization components other than propylene as copolymerization components. Exterior material for devices.

[2] The exterior material for a power storage device according to item 1 above, 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 a power storage device according to item 1 or 2 above, wherein the elastomer-modified olefin resin constituting the innermost layer has a melting point higher than 160 ° C.

[4] The exterior material for a power storage device according to any one of Items 1 to 3 above, wherein the sealant film constituting the sealant layer has a tensile yield strength of 3.5 MPa to 15.0 MPa at 80 ° C.

[5] The sealant layer is composed of a plurality of layers, and a second sealant layer is arranged on the side of the sealant layer closest to the metal foil layer, and the second sealant layer contains 50 propylene-ethylene random copolymers. The exterior material for a power storage device according to any one of Items 1 to 4 above, which contains a mass% or more and does not contain an elastomer component.

[6] The exterior material for a power storage device according to any one of the above items 1 to 5, wherein the metal foil layer and the sealant layer are adhered to each other via an adhesive layer.

[7] The exterior material for a power storage device according to item 6, wherein the adhesive layer comprises an adhesive containing an olefin resin having a carboxyl group and a polyfunctional isocyanate compound.

[8] The main body of the power storage device and
The exterior material for a power storage device according to any one of the above items 1 to 7 is provided.
A power storage device characterized in that the power storage device main body is covered 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 above-mentioned specific elastomer-modified olefin resin, the initial sealing strength between the exterior materials is sufficiently secured even in a high temperature environment. At the same time, sufficient seal strength can be maintained even if it is left in a high temperature environment (for example, in a car in summer) for a long period of time.

In the invention of [2], the film strength of the sealant layer is increased by the content of the olefin-based thermoplastic elastomer in the innermost layer of the sealant layer being 0.1% by mass or more and less than 20% by mass. Destruction (tear) from the above is unlikely 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 higher than 160 ° C., the outflow of the sealant layer can be sufficiently suppressed when the exterior material is heat-sealed, and the high temperature is described. It also has excellent heat resistance in the environment.

In the invention of [4], since the sealant film having a tensile yield strength at 80 ° C. of 3.5 MPa to 15.0 MPa is used for the sealant layer, the power storage device is long in a high temperature environment (for example, in a car in summer). Even if it is used for a period of time, it is possible to prevent the exterior material from bursting due to an increase in internal pressure.

In the invention of [5], the second sealant layer closest to the metal foil layer contains 50% by mass or more of the propylene-ethylene random copolymer and does not contain an elastomer component. Therefore, the metal foil layer is formed. Adhesion to the side is improved, and even if deformation occurs, delamination is unlikely to occur. Furthermore, since the second sealant layer closest to the metal foil layer does not contain an elastomer component, there are no crazes (no cracks or gaps) that may occur at the interface between the propylene-ethylene random copolymer and the elastomer component. Sufficient insulating property can be ensured because the electrolytic solution does not infiltrate the vicinity of the metal foil layer due to the dissociation of the interface).

In the invention of [6], the interlayer adhesive force between the metal foil layer and the sealant layer can be further enhanced.

In the invention of [7], since the adhesive layer is composed of an adhesive containing an olefin resin having a carboxyl group and a polyfunctional isocyanate compound, the electrolytic solution resistance can be further improved.

According to the invention of [8], the exterior material can sufficiently secure the initial sealing strength between the exterior materials even in a high temperature environment and can maintain the sufficient sealing strength even when left in a high temperature environment (for example, in a car in summer) for a long period of time. It is possible to provide an external storage device having excellent high-temperature durability.

It is sectional drawing which shows one Embodiment of the exterior material for a power storage device which concerns on this invention. It is sectional drawing which shows the other embodiment of the exterior material for a power storage device which concerns on this invention. It is sectional drawing which shows one Embodiment of the power storage device which concerns on this invention. FIG. 3 is a perspective view showing an exterior material (planar shape) constituting the power storage device, a power storage device main body, and an exterior case (molded body molded into a three-dimensional shape) in a separated state before heat sealing.

FIG. 1 shows an embodiment of the exterior material 1 for a power storage device according to the present invention. The exterior material 1 for a power storage device is used, for example, as an exterior material for a lithium ion secondary battery. The exterior material 1 for a power storage device may be used as an exterior material as it is without being molded, or may be used as an exterior case 10 by being subjected to molding such as deep drawing molding or overhang molding. Good (see Figure 4).

In the exterior material 1 for a power storage device, the base material layer (outer layer) 2 is laminated and integrated on one surface of the metal foil layer 4 via the first adhesive layer 5, and the other of the metal foil layer 4 is laminated. The inner sealant layer (inner layer) 3 is laminated and integrated on the surface of the surface via 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) composed of the first sealant layer 7. Therefore, the first sealant layer 7 is arranged on the innermost side (the first sealant layer 7 is the innermost layer).

Further, in the exterior material 1 of FIG. 2, the inner sealant layer (inner layer) 3 includes the innermost first sealant layer 7 and the second sealant layer 8 arranged on the side closest to the metal foil layer 4. , And the first sealant layer 7 is arranged on the innermost side.

In the present invention, the inner sealant layer (inner layer) 3 is provided with excellent chemical resistance against a highly corrosive electrolytic solution used in a lithium ion secondary battery or the like, and the exterior material is heat-sealed. It plays a role in imparting sex. 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 a plurality of two or more layers, but at least the sealant layer (inner layer) 3 may be formed. The innermost layer (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 an olefin-based thermoplastic elastomer-modified homopolypropylene and / and an olefin-based thermoplastic elastomer-modified random copolymer, and the olefin-based thermoplastic elastomer-modified random copolymer. The coalescence 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 above-mentioned "other copolymerization components excluding propylene". Examples thereof include, but are not limited to, olefin components such as ethylene, 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, and butadiene and the like. The olefin-based thermoplastic elastomer is not particularly limited, and examples thereof include EPR (ethylene propylene rubber), propylene-butene elastomer, propylene-butene-ethylene elastomer, and EPDM (ethylene-propylene-diene rubber). Above all, it is preferable to use EPR (ethylene propylene rubber).

Regarding the elastomer-modified olefin-based resin, the embodiment of the "olefin-based thermoplastic elastomer modification" may be graft polymerization or other modification.

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 such a manufacturing method.

First, a Ziegler-Natta catalyst, a co-catalyst, 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 a Ziegler-Natta catalyst. In the second reactor, propylene and hydrogen are further added to polymerize homopolypropylene. The obtained homopolypropylene is transferred to a third reactor containing unreacted propylene and a Ziegler-Natta catalyst. The above elastomer-modified olefin resin can be produced by further adding ethylene, propylene and hydrogen in the third reactor to polymerize ethylene-propylene rubber (EPR) obtained by copolymerizing ethylene and propylene. For example, the elastomer-modified olefin-based resin can be produced by adding a solvent and producing in a liquid phase, and the elastomer-modified olefin-based resin can be produced by carrying out the reaction in a gas phase without using a solvent. can.

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, homopolypropylene (a site not modified with an olefin-based thermoplastic elastomer) or / and the random copolymer (modified with an olefin-based thermoplastic elastomer) in the innermost layer (first sealant layer) 7 of the sealant layer 3 The content of the non-existent portion) is preferably 80% by mass or more and 99% by mass or less.

It is desirable that the melting point of the elastomer-modified olefin resin constituting the innermost layer (first sealant layer) 7 of the sealant layer 3 is in the range of 160 ° C to 180 ° C. The outflow of the sealant layer 3 can be sufficiently suppressed when the exterior material is heat-sealed, and the heat resistance in a high temperature environment is also excellent. Above all, 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 particularly preferably in the range of 163 ° C. to 169 ° C. The melting point is the melting point measured by the differential scanning calorimetry (DSC) method according to JIS K7121-1987.

The olefin-based thermoplastic elastomer component (this component alone) existing in the innermost layer (first sealant layer) 7 preferably has a plurality of crystallization temperatures. In the case of having a plurality of crystallization temperatures as described above, it is possible to obtain the effect that the resin (the olefin-based resin in the innermost layer) is less likely to elute at the time of bonding. Further, in the case of having a plurality of crystallization temperatures, it is desirable that the lowest crystallization temperature among the plurality of crystallization temperatures is in the range of 40 ° C to 80 ° C, and further in the range of 40 ° C to 75 ° C. Is more desirable. When the lowest crystallization temperature is 40 ° C to 80 ° C, the effect that the bonding time at room temperature (bonding time at the time of heat sealing) can be shortened can be obtained. The crystallization temperature is a crystallization temperature (crystallization peak) measured by a differential scanning calorimetry (DSC) method according to JIS K7121-1987.

The MFR of the olefin-based thermoplastic elastomer component (this component alone) existing in the innermost layer (first sealant layer) 7 is preferably 0.1 g / 10 minutes to 1.4 g / 10 minutes, in this case. Since the resin (olefin-based resin in the innermost layer) is less likely to elute during heat sealing, greater adhesive strength can be ensured. Above all, the MFR of the olefin-based thermoplastic elastomer component (this component alone) existing in the innermost layer (first sealant layer) 7 is more preferably 0.1 g / 10 minutes to 1.0 g / 10 minutes. , 0.1 g / 10 minutes to 0.6 g / 10 minutes is particularly preferable. The MFR (melt flow rate) is an MFR measured under the conditions of 230 ° C. and 2.16 kg in accordance with 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, the tensile yield strength of the first sealant film at 80 ° C. is preferably 3.5 MPa to 15.0 MPa, and the sealant. When the 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 preferably 3.5 MPa to 15.0 MPa. .. The same applies to the case where the sealant layer 3 has three or more layers. Since the tensile yield strength of the sealant film constituting the sealant layer 3 at 80 ° C. is 3.5 MPa to 15.0 MPa, the power storage device is used in a high temperature environment (for example, in a car in summer) for a long period of time. Even if it is done, it is possible to prevent the exterior material from bursting due to an increase in internal pressure. Above all, 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 that the toughness of the first sealant layer 7 can be improved. Above all, the thickness of the innermost layer (first sealant layer) 7 is more preferably 30 μm to 100 μm.

When the second sealant layer 8 is provided, the thickness of the second sealant layer 8 is preferably 3 μm to 60 μm, more preferably 5 μm to 20 μm. When the second sealant layer 8 is provided, the resin forming the second sealant layer 8 is not particularly limited, but for example, a propylene-ethylene random copolymer, homopolypropylene, or polyethylene. In addition, olefins of random copolymers containing olefin-based thermoplastic elastomer-modified homopolypropylene and olefin-based thermoplastic elastomer-modified random copolymers ("propylene" as a copolymerization component and "other copolymerization components other than propylene"". System thermoplastic elastomer modified product) and the like.

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 a plurality of layers, and is arranged on the innermost layer (first sealant layer) 7 containing the elastomer-modified olefin resin 7 and the second side closest to the metal foil layer 4. It is preferable that the second sealant layer is provided with the sealant layer 8 (see FIG. 2), and the second sealant layer contains 50% by mass or more of the propylene-ethylene random copolymer and does not contain an elastomer component. When such a structure is adopted, the second sealant layer 8 on the side closest to the metal foil layer 4 contains 50% by mass or more of the propylene-ethylene random copolymer and does not contain the elastomer component. The adhesiveness with the metal foil layer side is improved, and even if deformation occurs, delamination is unlikely to occur. Further, since the second sealant layer 8 on the side closest to the metal foil layer 4 does not contain an elastomer component, crazes (cracks / gaps) that may occur at the interface between the propylene-ethylene random copolymer and the elastomer component There is no infiltration of the electrolytic solution into the vicinity of the metal foil layer due to (dissociation of the interface), and sufficient insulating properties can be ensured. Above all, it is more preferable that the second sealant layer contains 70% by mass or more of the propylene-ethylene random copolymer and does not contain an elastomer component. Here, the configuration containing no elastomer component means that the elastomer component is not mixed (blended) and 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 multi-layer extrusion molding, inflation molding, or T-die cast film molding.

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

In the present invention, the base material 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 when the exterior material is heat-sealed is used. As the heat-resistant resin, it is preferable to use a heat-resistant resin having a melting point higher than the melting point of the sealant layer 3 by 10 ° C. or more, and it is particularly preferable to use a heat-resistant resin having a melting point higher than the melting point of the sealant layer 3 by 20 ° C. or more. preferable.

The heat-resistant resin layer (outer layer) 2 is not particularly limited, and examples thereof include a polyamide film such as a nylon film and a polyester film, and these stretched films are preferably used. Among them, the heat-resistant resin layer 2 includes 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 na. It is particularly preferable to use a phthalate (PEN) film. The nylon film is not particularly limited, and examples thereof include a 6-nylon film, a 6,6 nylon film, and an MXD nylon film. The heat-resistant resin layer 2 may be formed of a single layer, or may be formed of, for example, a plurality of layers made of a polyester film / a polyamide film (a plurality of layers made of a PET film / a nylon film, etc.). Is also good. In the case of the plurality of layers, it is preferable to arrange the polyester film side on the outermost side.

The thickness of the outer layer (base material 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 to the above-mentioned suitable lower limit value or more, sufficient strength as an exterior material can be secured, and by setting it to the above-mentioned suitable upper limit value or less, stress during forming such as overhang molding and draw forming can be reduced and formability is improved. Can be made to.

In the exterior material for a power storage device according to the present invention, the metal leaf layer 4 plays a role of imparting a gas barrier property to prevent the intrusion of oxygen and moisture into the exterior material 1. The metal foil layer 4 is not particularly limited, and examples thereof include an aluminum foil, a SUS foil (stainless foil), and a copper foil. Among them, an aluminum foil and a SUS foil (stainless foil) are used. Is preferable. The thickness of the metal foil layer 4 is preferably 10 μm to 120 μm. When it is 10 μm or more, it is possible to prevent the occurrence of pinholes during rolling when manufacturing a metal foil, and when it is 120 μm or less, the stress during forming such as overhang forming and draw forming can be reduced and the formability is improved. be able to.

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 a chemical conversion treatment, it is possible to sufficiently prevent corrosion of the metal foil surface due to the contents (electrolyte solution of the battery, etc.). For example, the metal foil is subjected to chemical conversion treatment by performing the following treatment. That is, for example, on the surface of the metal leaf that has been degreased,
1) Phosphoric acid and
With chromic acid,
An aqueous solution of a mixture containing at least one compound selected from the group consisting of a metal salt of fluoride and a non-metal salt of fluoride 2) Phosphoric acid.
At least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins, and
An aqueous solution of a mixture containing at least one compound selected from the group consisting of chromic acid and a chromium (III) salt 3) phosphoric acid.
At least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins, and
At least one compound selected from the group consisting of chromic acid and chromium (III) salt, and
An aqueous solution of a mixture containing at least one compound selected from the group consisting of a metal salt of fluoride and a non-metal salt of fluoride An aqueous solution of any one of 1) to 3) above is applied and then dried. By doing so, the chemical conversion process is performed.

The conversion coating, chromium coating weight preferably is 0.1mg / m ² ~50mg / m ² as a (per one surface), in particular 2mg / m ² ~20mg / m 2 preferred.

The first adhesive layer (outer adhesive layer) 5 is not particularly limited, but is, for example, a polyurethane polyolefin adhesive layer, a polyurethane adhesive layer, a polyester polyurethane adhesive layer, or a polyether polyurethane adhesive layer. And so on. The thickness of the first adhesive layer 5 is preferably set to 1 μm to 6 μm. Above all, 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, the one exemplified as the first adhesive layer 5 can be used, but the polyolefin has less swelling due to the electrolytic solution. It is preferable to use a system adhesive. Above all, 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. The 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 laminating of an olefin resin having a carboxyl group by melt extrusion. The olefin resin having a carboxyl group is not particularly limited, but for example, maleic acid-modified polypropylene, maleic acid-modified polyethylene, acrylic acid-modified polypropylene, acrylic acid-modified polyethylene, methacrylic acid-modified polypropylene, and methacrylic acid-modified. Examples thereof include carboxylic acid-modified olefin resins such as 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. Above all, 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.

The exterior case (battery case, etc.) 10 can be obtained by molding the exterior material 1 of the present invention (deep drawing molding, overhang molding, etc.) (FIG. 4). The exterior material 1 of the present invention can be used as it is without being subjected to molding (FIG. 4).

FIG. 3 shows an embodiment of the power storage device 30 configured by 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 FIGS. 3 and 4, the exterior member 15 is composed of the exterior case 10 obtained by molding the exterior material 1 and the flat exterior material 1. The storage device main body (electrochemical element or the like) 31 having a substantially rectangular shape is housed in the storage recess of the exterior case 10 obtained by molding the exterior material 1 of the present invention. The exterior material 1 of the present invention is arranged on the sealant layer 3 side of the present invention with the sealant layer 3 side inward (lower side), and the peripheral portion of the sealant layer 3 of the planar exterior material 1 and the exterior. The energy storage device 30 of the present invention is configured by sealing and sealing the sealant layer 3 of the flange portion (sealing peripheral portion) 29 of the case 10 by heat sealing (see FIGS. 3 and 4). ). The inner surface of the accommodating recess of the exterior case 10 is the sealant layer 3, and the outer surface of the accommodating recess is the base material layer (outer layer) 2 (see FIG. 4).

In FIG. 3, 39 is a heat-sealed portion in which the peripheral edge portion of the exterior material 1 and the flange portion (sealing peripheral edge portion) 29 of the exterior case 10 are joined (welded). In the power storage device 30, the tip of the tab lead connected to the power storage device main body 31 is led out to the outside of the exterior member 15, but the illustration is omitted.

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

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

In the above embodiment, the exterior member 15 is composed of an exterior case 10 obtained by molding the exterior material 1 and a flat exterior material 1 (see FIGS. 3 and 4). The combination is not particularly limited, and for example, the exterior member 15 may be composed of a pair of flat exterior materials 1, or may be composed of a pair of exterior cases 10. You may.

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

<Material used>
(Elastomer-modified olefin resin A)
The elastomer-modified olefin resin A comprises an EPR-modified homopolypropylene and an EPR-modified product of an 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 comprises a propylene-butene elastomer-modified homopolypropylene and a propylene-butene elastomer-modified product of an 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 resin C comprises a propylene-butene-ethylene elastomer-modified homopolypropylene and a propylene-butene-ethylene elastomer-modified product of an 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.

< Reference example 1 >
A chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol was applied to both sides of an aluminum foil 4 having a thickness of 35 μm, and then dried at 180 ° C. , Formed a chemical conversion film. The amount of chromium adhered to this chemical conversion film was ^{10 mg / m 2 per side.}

Next, a biaxially stretched 6 nylon film 2 having a thickness of 15 μm was dry-laminated on one surface of the chemical conversion-treated aluminum foil 4 via a two-component curable urethane adhesive (outer adhesive) 5. I pasted them together).

Next, after extruding a sealant film (first sealant layer) 7 having a thickness of 80 μm made of an elastomer-modified olefin resin A, a two-component curable urethane adhesive is applied to one surface of the sealant film 7 (3). By superimposing the other surface of the dry-laminated aluminum foil 4 via the (inner adhesive layer) 6, the rubber nip roll is sandwiched between the rubber nip roll and the laminate roll heated to 100 ° C. and crimped. After dry laminating and then aging (heating) at 50 ° C. for 5 days, the exterior material 1 for a power storage device having the configuration shown in FIG. 1 was obtained.

< Reference example 2 >
As the inner adhesive 6, the storage storage having the configuration shown in FIG. 1 is the same as in Example 1 except that the two-component curable acrylic adhesive 6 is used instead of the two-component curable urethane adhesive. The exterior material 1 for the device was obtained.

<Example 3>
A chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol was applied to both sides of a 35 μm-thick aluminum foil 4, and then dried at 180 ° C. , Formed a chemical conversion film. The amount of chromium adhered to this chemical conversion film was ^{10 mg / m 2 per side.}

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

Next, on the other surface of the aluminum foil 4 after the dry laminating, a 4 μm thick anhydrous maleic acid-modified polypropylene film (inner adhesive layer) 6 and an 8 μm thick propylene-ethylene random copolymer film (second). The coextruded sealant layer 8 and the elastomer-modified olefin resin A film (first sealant layer) 7 having a thickness of 72 μm are laminated in this order, and between the rubber nip roll and the laminate roll heated to 100 ° C. The exterior material 1 for a power storage device having the configuration shown in FIG. 2 was obtained by sandwiching it in a film and crimping it to dry-laminate it, and then aging (heating) it at 50 ° C. for 5 days.

< Reference example 3 >
A chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol was applied to both sides of an aluminum foil 4 having a thickness of 35 μm, and then dried at 180 ° C. , Formed a chemical conversion film. The amount of chromium adhered to this chemical conversion film was ^{10 mg / m 2 per side.}

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

Next, a 4 μm-thick anhydrous maleic acid-modified polypropylene film (inner adhesive layer) 6 and an 80 μm-thick elastomer-modified olefin resin A film 3 are coextruded onto the other surface of the dry-laminated aluminum foil 4. These are layered in this order, sandwiched between a rubber nip roll and a laminate roll heated to 100 ° C, and crimped for dry laminating, and then aged (heated) at 50 ° C for 5 days. Obtained the exterior material 1 for a power storage device having the configuration shown in FIG.

< Reference example 4 >
An exterior material 1 for a power storage device having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1 except that the elastomer-modified olefin resin B was used instead of the elastomer-modified olefin resin A.

< Reference example 5 >
An exterior material 1 for a power storage device having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1 except that the elastomer-modified olefin resin C was used instead of the elastomer-modified olefin resin A.

< Reference example 6 >
A chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol was applied to both sides of an aluminum foil 4 having a thickness of 35 μm, and then dried at 180 ° C. , Formed a chemical conversion film. The amount of chromium adhered to this chemical conversion film was ^{10 mg / m 2 per side.}

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

Next, a two-component curable urethane-based adhesive (inner adhesive layer) 6 is applied to the other surface of the dry-laminated aluminum foil 4, and then a homopolypropylene film having a thickness of 8 μm (8 μm thick homopolypropylene film) is applied to the applied surface. The second sealant layer) 8 and the elastomer-modified olefin resin A film (first sealant layer) 7 having a thickness of 72 μm were co-extruded and laminated in this order, and a rubber nip roll and a laminate roll heated to 100 ° C. The exterior material 1 for a power storage device having the configuration shown in FIG. 2 was obtained by sandwiching it between the two and crimping it for dry laminating, and then aging (heating) it at 50 ° C. for 5 days.

<Example 8>
As the second sealant layer 8, the configuration shown in FIG. 2 is the same as in Example 7, except that a propylene-ethylene random copolymer film 8 having a thickness of 8 μm is used instead of the homopolypropylene film having a thickness of 8 μm. The exterior material 1 for a power storage device was obtained.

<Example 9>
As the inner adhesive 6, the storage storage having the configuration shown in FIG. 2 is the same as in Example 8 except that the two-component curable acrylic adhesive 6 is used instead of the two-component curable urethane adhesive. The exterior material 1 for the device was obtained.

<Comparative Example 1>
An exterior material for a power storage device having the configuration 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 conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol was applied to both sides of an aluminum foil 4 having a thickness of 35 μm, and then dried at 180 ° C. , Formed a chemical conversion film. The amount of chromium adhered to this chemical conversion film was ^{10 mg / m 2 per side.}

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

Next, after applying a two-component curable acrylic adhesive 6 to the other surface of the dry-laminated aluminum foil 4, an elastomer-modified olefin resin A film having a thickness of 68 μm (second) is applied to the coated surface. The sealant layer) 8 and the propylene-ethylene random copolymer film (first sealant layer) 7 having a thickness of 12 μm were co-extruded and laminated in this order, and a rubber nip roll and a laminate roll heated to 100 ° C. were combined. By sandwiching it between them and crimping it for dry laminating, and then aging (heating) it at 50 ° C. for 5 days, an exterior material for a power storage device having the configuration shown in FIG. 2 was obtained.

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 and 2 was measured as follows. Yield strength (tensile yield strength).

<Measurement method of tensile yield strength of sealant film>
For the unstretched sealant film 3 (thickness 80 μm) separately prepared for measurement in the same manner, a type 2 test piece (length 150 mm or more) was used in accordance with JIS K7127-1999 (tensile test method for plastic film). The tensile yield strength (tensile yield strength) was determined by conducting a tensile test under the conditions of a sample width of 15 mm, a grip distance of 100 mm, a marked line distance of 50 mm, and a tensile speed of 100 mm / min under the conditions of 80 ° C. I asked. The load at the yield point on the SS curve is defined as the tensile yield strength. After setting the test piece in the tensile test device in the constant temperature bath set at 80 ° C, let it stand in this 80 ° C environment for 1 minute, and then perform the tensile test in the 80 ° C environment. bottom. Table 1 shows the measurement results of the tensile yield strength at 80 ° C.

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

The exterior materials for each power storage device obtained as described above were evaluated based on the following measurement methods.

<Measurement method of initial seal strength at high temperature>
Two test pieces having a width of 15 mm and a length of 150 mm were cut out from the obtained exterior material, and then the two test pieces were superposed so as to be in contact with each other's inner sealant layers. Heat seal by single-sided heating under the conditions of heat seal temperature: 200 ° C., seal pressure: 0.2 MPa (gauge display pressure), and seal time: 2 seconds using the heat seal device (TP-701-A) manufactured by the same company. went.

Next, with respect to the pair of exterior materials in which the inner sealant layers were heat-sealed as described above, a strograph (tensile test device) manufactured by Shimadzu Access Co., Ltd. was arranged in a constant temperature bath in accordance with JIS Z0238-1998. ) (AGS-5kNX) was used to measure the peel strength when the exterior material (test piece) was peeled 90 degrees between the inner sealant layers of the seal portion at a tensile speed of 100 mm / min, and this was measured as the seal strength (AGS-5kNX). N / 15 mm width). The seal strength at 100 ° C. and the seal strength at 120 ° C. were measured.

In the measurement of the seal strength at 100 ° C, the test piece is set in a tensile test device in a constant temperature bath set at 100 ° C, and then allowed to stand in this 100 ° C environment for 1 minute and then in an environment of 100 ° C. I tried to carry out the measurement at. For the measurement of the seal strength at 120 ° C, after setting the test piece in the tensile test device in the constant temperature bath set at 120 ° C, the test piece is allowed to stand in this 120 ° C environment for 1 minute and then in the 120 ° C environment. I tried to carry out the measurement at.

Those having both a seal strength at 100 ° C. and a seal strength at 120 ° C. of 27 N / 15 mm width or more are accepted.

<Seal strength measurement method after 90 days in a high temperature environment>
Two exterior materials cut to a size of 200 mm in length × 150 mm in width are placed on top of each other so that the sealant layers face each other on the inside, and the edges of the three sides are placed at 180 ° C. and 0.2 MPa. Heat sealed for 2 seconds. After injecting 10 mL of the electrolytic solution through the opening of the remaining one unsealed side, heat-seal the remaining one side while removing the air inside under the same sealing conditions as described above to create a simulated battery (test piece). bottom. _{As the electrolytic solution, electrolytic 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 equal volume ratios. A liquid was used.

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

After the 90 days have passed, the simulated battery is taken out, one side is opened to remove the electrolytic solution, the inside is washed with water several times, and then the two exterior materials are put together so as to include the sealing portion of the two exterior materials. This pair of exterior materials obtained by cutting into a size of 15 mm in width × 150 mm in length in a superposed state is strograph (tensile test device) (AGS-5kNX) manufactured by Shimadzu Access Co., Ltd. in accordance with JIS Z0238-1998. ) Was used to measure the peel strength when the pair of exterior materials were peeled 90 degrees between the sealant layers of the seal portion at a tensile speed of 100 mm / min, and this was defined as the seal strength (N / 15 mm width). The seal strength at 25 ° C. was measured. Those having a seal strength of 27 N / 15 mm width or more are accepted.

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 secure the initial seal strength even in a high temperature environment and can be left in a high temperature environment for a long period of time. Sufficient seal strength can be maintained.

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

The exterior material for a power storage device manufactured by using the sealant film according to the present invention and the exterior material for a power storage device according to the present invention are, for example, as specific examples.
-Used as an exterior material for various power storage devices such as power storage devices such as lithium secondary batteries (lithium ion batteries, lithium polymer batteries, etc.), lithium ion capacitors, and electric double-layer capacitors. Further, the power storage device according to the present invention includes an all-solid-state battery in addition to the power storage device exemplified above.

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

Claims (7)

In the exterior material for a power storage device, which includes a heat-resistant resin layer as an outer layer, a sealant layer as an inner layer, and a metal foil layer arranged between both layers thereof.
The sealant layer is composed of a plurality of layers, and at least the innermost layer of the sealant layer is composed of a plurality of layers.
Contains elastomer-modified olefin resin,
The elastomer-modified olefin-based resin comprises an olefin-based thermoplastic elastomer-modified homopolypropylene and / and an olefin-based thermoplastic elastomer-modified random copolymer.
The olefin-based thermoplastic elastomer-modified random copolymer is an olefin-based thermoplastic elastomer-modified product of a random copolymer containing propylene as a copolymerization component and other copolymerization components other than propylene.
The sealant layer is composed of a plurality of layers, and a second sealant layer is arranged 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 a propylene-ethylene random copolymer. An exterior material for a power storage device, which contains and does not contain an elastomer component. The exterior material for a power storage device according to claim 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. The exterior material for a power storage device according to claim 1 or 2, wherein the elastomer-modified olefin resin constituting the innermost layer has a melting point higher than 160 ° C. The sealant film constituting the sealant layer has a tensile yield strength of 3 at 80 ° C.
.. The exterior material for a power storage device according to any one of claims 1 to 3, which is 5 MPa to 15.0 MPa. The exterior material for a power storage device according to any one of claims 1 to 4, wherein the metal foil layer and the sealant layer are adhered to each other via an adhesive layer. The exterior material for a power storage device according to claim 5, wherein the adhesive layer comprises an adhesive containing an olefin resin having a carboxyl group and a polyfunctional isocyanate compound. The main body of the power storage device and
The exterior material for a power storage device according to any one of claims 1 to 6 is provided.
A power storage device characterized in that the power storage device main body is covered with the exterior material.

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