WO2023190997A1

WO2023190997A1 - Outer package material for power storage devices, method for producing same and power storage device

Info

Publication number: WO2023190997A1
Application number: PCT/JP2023/013407
Authority: WO
Inventors: 真天野; 孝典山下
Original assignee: 大日本印刷株式会社
Priority date: 2022-03-31
Filing date: 2023-03-30
Publication date: 2023-10-05

Abstract

The present invention provides a novel outer package material for power storage devices, the outer package material enabling the outer surface of a power storage device to be thermally fused to an adherend by being utilized as an outer package material for the power storage device.　The present invention provides an outer package material for power storage devices, the outer package material being configured from a multilayer body that sequentially comprises, from the outer side, at least a first thermally fusible resin layer, a barrier layer and a second thermally fusible resin layer, wherein: the first thermally fusible resin layer contains a polyethylene as a main component; and the second thermally fusible resin layer contains a polyethylene as a main component.

Description

Exterior material for power storage device, manufacturing method thereof, and power storage device

The present disclosure relates to an exterior material for a power storage device, a method for manufacturing the same, and a power storage device.

Conventionally, various types of electricity storage devices have been developed, and in all electricity storage devices, an exterior material has become an essential component to seal electricity storage device elements such as electrodes and electrolytes. Conventionally, metal exterior materials have been frequently used as exterior materials for power storage devices.

On the other hand, in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., power storage devices are required to have a variety of shapes, as well as to be thinner and lighter. However, metal exterior materials for power storage devices, which have been widely used in the past, have the disadvantage that it is difficult to keep up with the diversification of shapes, and there is also a limit to the reduction in weight.

Therefore, in the past, base material layer/barrier layer/adhesive layer/thermal adhesive resin layer were sequentially laminated as exterior materials for power storage devices that can be easily processed into various shapes and can be made thinner and lighter. A film-like laminate has been proposed (see, for example, Patent Document 1).

In such exterior materials for power storage devices, generally, a recess is formed by cold forming, power storage device elements such as electrodes and electrolyte are arranged in the space formed by the recess, and heat-sealable resin is placed in the space formed by the recess. By heat-sealing the layers, a power storage device in which power storage device elements are housed inside the power storage device exterior material is obtained.

JP2008-287971A

Power storage devices are used for a variety of purposes, and the needs for power storage devices are diverse. The inventors of the present disclosure believe that if a power storage device is provided that has the function of thermally bonding to an adherend, for example, the power storage device can be fixed in a product by thermal bonding, or multiple power storage devices can be stacked together. By heat-sealing and fixing them in a stacked state, even if multiple power storage devices are built into a product in a stacked state, each power storage device is fixed, so there is no risk of power storage due to product vibration, etc. We believe that this has the advantage of suppressing device misalignment and damage caused by shocks transmitted to each energy storage device when external force is applied to the product.

The present disclosure addresses these new challenges and provides a new method for use in power storage devices that can be used as an exterior material for power storage devices by heat-sealing the outer surface of the power storage device to an adherend. Its main purpose is to provide exterior materials.

The inventors of the present disclosure have conducted extensive studies to solve the above problems. As a result, the laminate structure of the exterior material for a power storage device is a laminate including, in order from the outside, at least a first heat-fusible resin layer, a barrier layer, and a second heat-fusible resin layer; The heat-fusible resin layer and the second heat-fusible resin layer are each made of a resin whose main component is polyethylene, instead of polypropylene, which is generally used as a heat-fusible resin layer for exterior materials for power storage devices. We have obtained a new finding that the outer surface of a power storage device can be thermally fused to an adherend by using .

The present disclosure has been completed through further studies based on these findings. That is, the present disclosure provides inventions of the following aspects.
Consisting of a laminate including, in order from the outside, at least a first heat-fusible resin layer, a barrier layer, and a second heat-fusible resin layer,
The first heat-fusible resin layer contains polyethylene as a main component,
The second heat-fusible resin layer is an exterior material for a power storage device, which contains polyethylene as a main component.

According to the present disclosure, it is possible to provide a novel exterior material for an electricity storage device, which can be used as an exterior material for an electricity storage device by heat-sealing the outer surface of the energy storage device to an adherend. . Further, according to the present disclosure, it is also possible to provide a method for manufacturing an exterior material for a power storage device and a power storage device.

It is a schematic diagram showing an example of the cross-sectional structure of the exterior material for electricity storage devices of this indication. It is a schematic diagram showing an example of the cross-sectional structure of the exterior material for electricity storage devices of this indication. It is a schematic diagram showing an example of the cross-sectional structure of the exterior material for electricity storage devices of this indication. It is a schematic diagram showing an example of the cross-sectional structure of the exterior material for electricity storage devices of this indication. It is a schematic diagram for demonstrating the method of accommodating an electrical storage device element in the package formed of the exterior material for electrical storage devices of this indication. FIG. 3 is a schematic diagram for explaining a method of measuring seal strength. FIG. 3 is a schematic diagram for explaining a method of measuring seal strength. FIG. 3 is a schematic diagram for explaining an insulation evaluation method.

The exterior material for a power storage device according to the present disclosure is composed of a laminate including, in order from the outside, at least a first heat-fusible resin layer, a barrier layer, and a second heat-fusible resin layer; The heat-fusible resin layer contains polyethylene as a main component, and the second heat-fusible resin layer contains polyethylene as a main component. By having such a configuration, the exterior material for an electricity storage device of the present disclosure can be used as an exterior material for an electricity storage device, thereby allowing the outer surface of the electricity storage device to be thermally fused to an adherend.

Hereinafter, the exterior material for a power storage device of the present disclosure will be described in detail. In the present disclosure, the numerical range indicated by "~" means "more than" or "less than". For example, the expression 2 to 15 mm means 2 mm or more and 15 mm or less. In the numerical ranges described step by step in the present disclosure, the upper limit or lower limit described in a certain numerical range may be replaced with the upper limit or lower limit of another numerical range described step by step. Further, the upper limit value and the upper limit value, the upper limit value and the lower limit value, or the lower limit value and the lower limit value, which are described separately, may be combined to form a numerical range. Furthermore, in the numerical ranges described in this disclosure, the upper limit or lower limit described in a certain numerical range may be replaced with the value shown in the Examples.

Regarding the barrier layer 5 described below in the exterior material for a power storage device, it is usually possible to distinguish between MD (Machine Direction) and TD (Transverse Direction) in the manufacturing process. For example, when the barrier layer 5 is made of metal foil such as aluminum alloy foil or stainless steel foil, there are lines called so-called rolling marks on the surface of the metal foil in the rolling direction (RD) of the metal foil. Lines are formed. Since the rolling marks extend along the rolling direction, the rolling direction of the metal foil can be determined by observing the surface of the metal foil. In addition, in the process of manufacturing a laminate, the MD of the laminate and the RD of the metal foil usually match, so the surface of the metal foil of the laminate is observed and the rolling direction (RD) of the metal foil is identified. By doing so, the MD of the laminate can be specified. Further, since the TD of the laminate is perpendicular to the MD of the laminate, the TD of the laminate can also be specified.

Furthermore, if the MD of the exterior material for a power storage device cannot be identified due to rolling marks on metal foil such as aluminum alloy foil or stainless steel foil, it can be identified by the following method. As a method for confirming the MD of the exterior material for power storage devices, there is a method of observing a cross section of the heat-fusible resin layer of the exterior material for power storage devices with an electron microscope to confirm the sea-island structure. In this method, the MD can be determined as the direction parallel to the cross section in which the average diameter of the island shape in the direction perpendicular to the thickness direction of the heat-fusible resin layer is maximum. Specifically, the angle is changed by 10 degrees from the longitudinal cross section of the heat-fusible resin layer and the direction parallel to the longitudinal cross section, until the angle is perpendicular to the longitudinal cross section. Each cross section (10 cross sections in total) is observed using an electron microscope to confirm the sea-island structure. Next, in each cross section, the shape of each individual island is observed. Regarding the shape of each island, the straight line distance connecting the leftmost end in the direction perpendicular to the thickness direction of the heat-fusible resin layer and the rightmost end in the perpendicular direction is defined as the diameter y. In each cross section, the average of the top 20 diameters y of the island shape is calculated in descending order of diameter y. The direction parallel to the cross section where the average diameter y of the island shape is the largest is determined to be the MD.

1. Laminated structure and physical properties of exterior material for power storage devices The exterior material 10 for power storage devices of the present disclosure includes, for example, as shown in FIG. It is composed of a laminate including a heat-fusible resin layer 2. In the exterior material 10 for a power storage device, the first heat-fusible resin layer 1 is the outermost layer, and the second heat-fusible resin layer 2 is the innermost layer. When assembling a power storage device using the power storage device exterior material 10 and power storage device elements, the peripheral edges are heat fused with the second heat-fusible resin layers 2 of the power storage device exterior material 10 facing each other. The electricity storage device element is accommodated in the space formed by the above-described process. Further, the power storage device using the exterior material for power storage device of the present disclosure can be used by heat-sealing the surface of the first heat-fusible resin layer 1 side that constitutes the outer surface of the power storage device to an adherend. I can do it. For example, if a power storage device in a product is fixed by heat fusion, or if multiple power storage devices are stacked and fixed by heat fusion, multiple power storage devices can be stacked and incorporated into the product. Even in cases where the individual power storage devices are fixed, there are advantages such as being able to prevent the power storage devices from shifting due to product vibration or damage caused by shocks transmitted to each power storage device when external force is applied to the product. be. In the laminate that constitutes the exterior material 10 for a power storage device of the present disclosure, the second heat-fusible resin layer 2 side is on the inner side than the barrier layer 5, and the first heat-sealing resin layer 2 side is on the inner side than the barrier layer 5, The fusible resin layer 1 side is the outside.

For example, as shown in FIGS. 2 to 4, the exterior material 10 for an electricity storage device is made of materials that are necessary for the purpose of increasing the adhesiveness between the first heat-fusible resin layer 1 and a layer adjacent thereto. The first adhesive layer 12 may be provided depending on the situation. In addition, as shown in FIGS. 3 to 4, for example, a second adhesive layer may be used as necessary for the purpose of increasing the adhesiveness between the second heat-fusible resin layer 2 and a layer adjacent thereto. It may have a layer 22.

Furthermore, as shown in FIG. 4, for example, the exterior material 10 for power storage devices includes a layer between the first heat-fusible resin layer 1 and the barrier layer 5 to increase the heat resistance of the exterior material 10 for power storage devices. For this purpose, the first heat-resistant layer 3 may be included if necessary. For example, as shown in FIG. 4, between the second heat-fusible resin layer 2 and the barrier layer 5, for the purpose of increasing the heat resistance of the exterior material 10 for an electricity storage device, if necessary, It may also have a second heat-resistant layer 4.

Furthermore, as shown in FIG. 4, for example, the exterior material 10 for a power storage device has a structure in which the first heat resistant layer 3 and the barrier layer 5 are bonded together for the purpose of increasing the adhesiveness between the first heat resistant layer 3 and the barrier layer 5. If necessary, a third adhesive layer 32 may be provided between the two. For example, as shown in FIG. 4, for the purpose of increasing the adhesion between the second heat-resistant layer 4 and the barrier layer 5, if necessary, In addition, a fourth adhesive layer 42 may be included.

The thickness of the laminate constituting the exterior material 10 for power storage devices is not particularly limited, but from the viewpoint of cost reduction, energy density improvement, etc., it is, for example, 300 μm or less, preferably about 250 μm or less, about 230 μm or less, about 210 μm or less can be mentioned. In addition, from the viewpoint of maintaining the function of the power storage device exterior material to protect the power storage device elements, the thickness of the laminate constituting the power storage device exterior material 10 is preferably approximately 60 μm or more, approximately 80 μm or more, or approximately Examples include 100 μm or more. Further, preferred ranges of the laminate constituting the exterior material 10 for power storage devices include, for example, about 60 to 300 μm, about 60 to 250 μm, about 60 to 230 μm, about 60 to 210 μm, about 80 to 300 μm, and about 80 to 250 μm. , about 80 to 230 μm, about 80 to 210 μm, about 100 to 300 μm, about 100 to 250 μm, about 100 to 230 μm, and about 100 to 210 μm, and in particular, about 100 to 230 μm when making the electricity storage device lightweight and thin. Preferably, when moldability and impact resistance are required, the thickness is preferably about 230 to 300 μm.

In the exterior material 10 for power storage devices, the first heat-fusible resin layer 1, the first adhesive layer 12 provided as needed, and the necessary A first heat-resistant layer 3 provided as necessary, a third adhesive layer 32 provided as necessary, a barrier layer 5, a fourth adhesive layer 42 provided as necessary, a second heat-resistant layer 4 provided as necessary. The ratio of the total thickness of the second adhesive layer 22 and the second heat-fusible resin layer 2, which are provided as necessary, is preferably 90% or more, more preferably 95% or more, and still more preferably 98% or more. % or more. As a specific example, the exterior material 10 for a power storage device of the present disclosure includes a first heat-fusible resin layer 1, a first adhesive layer 12, a first heat-resistant layer 3, a third adhesive layer 32, a barrier layer 5, a fourth When the adhesive layer 42, the second heat-resistant layer 4, the second adhesive layer 22, and the second heat-fusible resin layer 2 are included, these are relative to the thickness (total thickness) of the laminate constituting the exterior material 10 for an electricity storage device. The ratio of the total thickness of each layer is preferably 90% or more, more preferably 95% or more, and still more preferably 98% or more. Moreover, the exterior material 10 for a power storage device of the present disclosure includes a first heat-fusible resin layer 1 , a first adhesive layer 12 , a first heat-resistant layer 3 , a third adhesive layer 32 , a barrier layer 5 , a second heat-resistant layer 4 , the second adhesive layer 22, and the second heat-fusible resin layer 2, the ratio of the total thickness of each of these layers to the thickness (total thickness) of the laminate constituting the exterior material 10 for power storage device is , for example, 80% or more, preferably 90% or more, more preferably 95% or more, still more preferably 98% or more. Moreover, the exterior material 10 for a power storage device of the present disclosure includes a first heat-fusible resin layer 1 , a first adhesive layer 12 , a first heat-resistant layer 3 , a barrier layer 5 , a second heat-resistant layer 4 , a second adhesive layer 22 , and the second heat-fusible resin layer 2, the ratio of the total thickness of each of these layers to the thickness (total thickness) of the laminate constituting the exterior material 10 for power storage device is, for example, 80% or more, It is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

The exterior material for a power storage device of the present disclosure is produced using the first heat-fusible resin of the exterior material for a power storage device 10 under the conditions of each temperature (° C.), surface pressure (MPa), and time (seconds) listed in Table 1. The seal strength (25°C environment) of the test sample obtained by heat-sealing the layers 1 to each other is preferably about 30 N/15 mm or more, more preferably about 35 N, as measured in accordance with the provisions of JIS K7127:1999. /15mm or more, more preferably about 40N/15mm or more, and the upper limit is, for example, about 150N/15mm or less, and preferable ranges are about 30 to 150N/15mm, about 35 to 150N/15mm, and 40 to 150N/15mm. That's about it. A specific method for measuring the seal strength in a 25°C environment is as follows.

[Measurement of seal strength]
In accordance with the regulations of JIS K7127:1999, the seal strength of the exterior material for a power storage device at a measurement temperature of 25° C. environment is measured as follows. As a test sample, an exterior material for a power storage device cut into strips having a width in the TD direction of 15 mm is prepared. Specifically, as shown in FIG. 6, first, each exterior material for an electricity storage device is cut into 60 mm (TD direction) x 200 mm (MD direction) (FIG. 6a). Next, the exterior material for a power storage device is folded in half in the MD direction at a crease P (middle in the MD direction) so that the first heat-fusible resin layers on the outside face each other (FIG. 6b). About 10 mm inside from the crease P in the MD direction, the first heat-fusible resin layers were bonded together under the conditions of a seal width of 7 mm, each temperature (°C), surface pressure (MPa), and time (seconds) listed in Table 1. Heat seal (Figure 6c). In FIG. 6c, the shaded area S is the heat-sealed area. Next, the test sample 13 is obtained by cutting in the MD direction (cutting at the position of the two-dot chain line in FIG. 6d) so that the width in the TD direction is 15 mm (FIG. 6e). Next, the first heat-fusible resin layer of the heat-sealed portion of the test sample 13 is peeled off at a rate of 300 mm/min using a tensile testing machine (FIG. 7). The maximum strength at the time of peeling is defined as the seal strength (N/15 mm). The distance between chucks is 50 mm. The average value of three measurements is taken. In the measurement of seal strength, the test sample 13 is peeled off (destroyed) at the heat seal interface A shown in FIG. In some cases, the test sample 13 may break. When the test sample 13 breaks, the breaking strength is taken as the sealing strength.

Furthermore, in the exterior material for an energy storage device of the present disclosure, the total thickness of the first heat-resistant layer 3 and the second heat-resistant layer 4 is measured for the exterior material for an energy storage device before and after the heat sealing, and the total thickness of the exterior material for the energy storage device before and after the heat sealing is measured. The ratio (%) of the total thickness of the first heat-resistant layer 3 and the second heat-resistant layer 4 after heat sealing to the total thickness of the first heat-resistant layer 3 and the second heat-resistant layer 4 is preferably about 60% or more, more preferably is about 70% or more, more preferably about 80% or more, and the upper limit is, for example, 95% or less, and the preferable range is about 60 to 95%, about 70 to 95%, and 80 to 95%. The degree is mentioned.

[Measurement of thickness remaining rate]
Similar to the sample used in the above-mentioned [Measurement of seal strength], the sample used in [Measurement of thickness residual rate] uses the exterior material for the electricity storage device before and after heat sealing, and the first heat-resistant layer and the second heat-resistant layer are Measure the total thickness of the layers and calculate the ratio (%) of the total thickness of the first heat-resistant layer and second heat-resistant layer after heat-sealing to the total thickness of the first heat-resistant layer and second heat-resistant layer before heat-sealing. do. The residual rate of total thickness is the average value for two measurement samples. To measure the thickness, use a microtome to cut the measurement sample in the thickness direction, aiming at the middle of the 7 mm head width of the heat seal seal bar and the middle of the sample width of 60 mm, and observe the obtained cross section with a laser microscope. and do it.

In addition, the exterior material for a power storage device of the present disclosure has a time until a short circuit occurs, which is measured in the following insulation evaluation, preferably about 20 seconds or more, more preferably about 30 seconds or more, and still more preferably about 40 seconds. The upper limit is, for example, about 180 seconds or less, and preferable ranges include about 20 to 180 seconds, about 30 to 180 seconds, and about 40 to 180 seconds.

[Evaluation of insulation]
The exterior material 10 for a power storage device is cut to produce a strip with a width of 40 mm and a length of 100 mm, which is used as a test sample. Note that the width refers to the TD direction, and the length refers to the MD direction. After placing a stainless steel wire 20 with a diameter of 25 μm and a length of 70 mm in the widthwise center of the strip on the second heat-fusible resin layer side, an aluminum plate 30 with a width of 30 mm, a length of 100 mm, and a thickness of 100 μm was placed on each test sample. It is arranged so as to face the second heat-fusible resin layer side. At this time, the center of the strip in the width direction is made to coincide with the center of the aluminum plate 30 in the width direction. Next, the positive electrode of the tester is connected to the aluminum plate 30, and the negative electrode is connected to the exterior material for the power storage device. For the negative electrode of the tester, insert an alligator clip so that it reaches the barrier layer from the first heat-fusible resin layer side of the exterior material for the power storage device, and electrically connect the negative electrode of the tester and the barrier layer. . The tester is prepared to issue a continuity (short circuit) signal when the applied voltage is 100 V and the resistance is less than 200 MΩ. Next, a voltage of 100V was applied between the testers, and in this state, with the stainless steel wire 20 interposed between the aluminum plate 30 and the exterior material for the power storage device, the wire was heated at 190°C, 1MPa, and the width was perpendicular to the wire 20. Heat seal with 7mm and measure the time until a short circuit signal is generated. Measure 5 times, remove the longest and shortest points, and use the average value of the three points.

From the viewpoint of particularly suitably achieving the effects of the present disclosure, a preferable laminated structure of the exterior material 10 for an electricity storage device of the present disclosure is illustrated below.

(Lamination configuration A)
In order from the outside, the first heat-fusible resin layer 1, the first adhesive layer 12, the first heat-resistant layer 3, the third adhesive layer 32, the barrier layer 5, the fourth adhesive layer 42, the second heat-resistant layer 4, the second It is composed of a laminate including an adhesive layer 22 and a second heat-fusible resin layer 2 (9-layer composition). The thickness of the first heat-fusible resin layer 1 and the second heat-fusible resin layer 2 is about 30 to 80 μm (more preferably about 40 to 60 μm), and the thickness of the first heat-resistant layer 3 and the second heat-fusible resin layer The thickness of the heat-resistant layer 4 is about 15 to 50 μm (more preferably about 20 to 40 μm), and the thickness of the first adhesive layer 12 , the second adhesive layer 22 , the third adhesive layer 32 , and the fourth adhesive layer 42 The thickness of each layer is approximately 1 to 7 μm (and further approximately 2 to 5 μm). The first heat-fusible resin layer 1 and the second heat-fusible resin layer 2 each have a content of polyethylene (preferably high-density polyethylene, acid-modified polyethylene, or polyethylene with a melting peak temperature of 110 to 135°C). is 80% by mass or more (furthermore, 90% by mass or more, even 95% by mass or more), and the first heat-resistant layer 3 and the second heat-resistant layer 4 are each made of polypropylene resin (preferably polypropylene and acid-modified polypropylene). The content of at least one of them is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more (even more preferably 90% by mass or more, even more preferably 95% by mass or more). ). It is preferable that the first adhesive layer 12, the second adhesive layer 22, the third adhesive layer 32, and the fourth adhesive layer 42 each contain acid-modified polyolefin. In the laminated configuration A, the first heat-resistant layer 3 is particularly preferably formed of unstretched polypropylene or maleic anhydride-modified polypropylene.

(Lamination configuration B)
In order from the outside, the first heat-fusible resin layer 1, the first adhesive layer 12, the first heat-resistant layer 3, the third adhesive layer 32, the barrier layer 5, the second heat-resistant layer 4, the second adhesive layer 22, and the It is composed of a laminate including two heat-fusible resin layers 2 (8-layer composition). The thickness of the first heat-fusible resin layer 1 and the second heat-fusible resin layer 2 is about 30 to 80 μm (more preferably about 40 to 60 μm), and the thickness of the first heat-resistant layer 3 and the second heat-fusible resin layer The thickness of the heat-resistant layer 4 is about 15 to 50 μm (more preferably about 20 to 40 μm), and the thickness of the first adhesive layer 12, the second adhesive layer 22, and the third adhesive layer 32 is about 15 to 50 μm, respectively. , about 1 to 7 μm (even about 2 to 5 μm). The first heat-fusible resin layer 1 and the second heat-fusible resin layer 2 each have a content of polyethylene (preferably high-density polyethylene, acid-modified polyethylene, or polyethylene with a melting peak temperature of 110 to 135°C). is 80% by mass or more (further, 90% by mass or more, even 95% by mass or more), and the first heat-resistant layer 3 has a content of polypropylene resin (preferably polypropylene) of 50% by mass or more, preferably 60% by mass or more. The second heat-resistant layer 4 is composed of polypropylene resin ( Preferably, the content of acid-modified polypropylene is 80% by mass or more (more preferably 90% by mass or more, further still 95% by mass or more). It is preferable that the first adhesive layer 12, the second adhesive layer 22, and the third adhesive layer 32 each contain acid-modified polyolefin. In the laminated structure B, the first heat-resistant layer 3 is particularly preferably formed of unstretched polypropylene or maleic anhydride-modified polypropylene, and the second heat-resistant layer 4 is preferably formed of maleic anhydride-modified polypropylene. Particularly preferred.

(Lamination configuration C)
In order from the outside, the first heat-fusible resin layer 1, the first adhesive layer 12, the first heat-resistant layer 3, the barrier layer 5, the second heat-resistant layer 4, the second adhesive layer 22, and the second heat-fusible resin. It is constructed from a laminate including layer 2 (seven-layer construction). The thickness of the first heat-fusible resin layer 1 and the second heat-fusible resin layer 2 is about 30 to 80 μm (more preferably about 40 to 60 μm), and the thickness of the first heat-resistant layer 3 and the second heat-fusible resin layer The thickness of the heat-resistant layer 4 is about 15 to 50 μm (more preferably about 20 to 40 μm), and the thickness of the first adhesive layer 12 and the second adhesive layer 22 is about 1 to 7 μm (more preferably about 20 to 40 μm). is approximately 2 to 5 μm). The first heat-fusible resin layer 1 and the second heat-fusible resin layer 2 each have a content of polyethylene (preferably high-density polyethylene, acid-modified polyethylene, or polyethylene with a melting peak temperature of 110 to 135°C). is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more (even more preferably 90% by mass or more, still more preferably 95% by mass or more), and the first The heat-resistant layer 3 and the second heat-resistant layer 4 each have a polypropylene resin (preferably acid-modified polypropylene) content of 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and still more preferably It is 80% by mass or more (more preferably 90% by mass or more, even more preferably 95% by mass or more). It is preferable that the first adhesive layer 12 and the second adhesive layer 22 each contain acid-modified polyolefin. In the laminated structure C, it is particularly preferable that the first heat-resistant layer 3 and the second heat-resistant layer 4 are each formed of maleic anhydride-modified polypropylene.

2. Each layer forming the exterior material for power storage device [first heat-fusible resin layer 1 and second heat-fusible resin layer 2]
In the present disclosure, the first heat-fusible resin layer 1 is a layer that constitutes the outer surface of an exterior material for an electricity storage device, and when applied to an electricity storage device, the outer surface of the electricity storage device is heated to an adherend. This is a layer that performs the function of fusing. In addition, in the exterior material for a power storage device of the present disclosure, the second heat-fusible resin layer 2 corresponds to the innermost layer, and the second heat-fusible resin layers 2 are heat-fused to each other during assembly of the power storage device. This is a layer (sealant layer) that functions to seal the electricity storage device element.

The first heat-fusible resin layer 1 and the second heat-fusible resin layer 2 each contain polyethylene as a main component. In the present disclosure, containing polyethylene as a main component means that the content of polyethylene is, for example, 50% by mass among the resin components contained in the first heat-fusible resin layer 1 and the second heat-fusible resin layer 2. The above is preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, still more preferably 98% by mass or more, and This means that it is preferably 99% by mass or more, and the polyethylene content may be 100% by mass. The resin component other than polyethylene is not particularly limited as long as it does not impede the effects of the present disclosure, and examples thereof include polypropylene.

The water vapor permeability of the polyethylene of the first heat-fusible resin layer 1 in an environment of 40°C and 90% RH is preferably 0.50 g·mm/m ² ·24 h or less, more preferably 0.40 g·mm/m ² - 24 hours or less, more preferably 0.30 g·mm/m ² ·24 hours or less. The method for measuring water vapor permeability is as follows. The unit of water vapor permeability is g/( ^m2・24h), but in order to make it easier to compare the numerical values of test samples with different thicknesses, the numerical value obtained by measurement is calculated using a thickness of 1.0 mm. The unit g·mm/m ² ·24h was used.

<Measurement method of water vapor permeability>
Water vapor permeability is measured in accordance with JIS K 7129-2 "Plastics - Films and sheets - How to determine water vapor permeability - Part 2: Infrared sensor method". After cutting a film-like sample into 100 mm x 100 mm, it was measured at 40° C. and 90% RH to determine the water vapor permeability.

Specific examples of polyethylene include polyethylene such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene. Among these, high-density polyethylene is preferred from the viewpoint of more suitably exhibiting the effects of the present disclosure. These polyethylenes may be used alone or in combination of two or more. High-density polyethylene has low water vapor permeability and is particularly preferred as a layer included in the exterior material for power storage devices.

Moreover, acid-modified polyethylene may be sufficient as polyethylene. Acid-modified polyethylene is a polymer modified by block polymerization or graft polymerization of polyethylene with an acid component. As the acid-modified polyethylene, the above-mentioned polyethylene, a copolymer obtained by copolymerizing the above-mentioned polyethylene with a polar molecule such as acrylic acid or methacrylic acid, or a polymer such as crosslinked polyolefin can also be used. Further, examples of the acid component used for acid modification include carboxylic acids such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride, or their anhydrides. Preferred acid-modified polyethylenes include polyethylenes modified with carboxylic acids or their anhydrides. When the first heat-fusible resin layer 1 and the second heat-fusible resin layer 2 are each analyzed by infrared spectroscopy, it is preferable that a peak derived from maleic anhydride is detected. For example, when maleic anhydride-modified polyethylene is measured by infrared spectroscopy, peaks derived from maleic anhydride are detected at wave numbers around 1760 cm ^-1 and around 1780 cm ^-1 wave numbers. When the first heat-fusible resin layer 1 and the second heat-fusible resin layer 2 each contain maleic anhydride-modified polyethylene, a peak derived from maleic anhydride is detected when measured by infrared spectroscopy. Ru. However, if the degree of acid modification is low, the peak may become small and may not be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

The first heat-fusible resin layer 1 and the second heat-fusible resin layer 2 may each be formed from one type of resin alone, or may be formed from a blended polymer that is a combination of two or more types of resin. Good too. Further, each of the first heat-fusible resin layer 1 and the second heat-fusible resin layer 2 may be formed of only one layer, but may be formed of two or more layers of the same or different resins. Good too.

From the viewpoint of more preferably exhibiting the effects of the present disclosure, the melting peak temperatures of the first heat-fusible resin layer 1 and the second heat-fusible resin layer 2 are preferably about 130°C or less, more preferably The temperature is about 110 to 130°C, more preferably about 120 to 130°C. In addition, since the melting peak temperature is 110°C or higher, blocking occurs easily during winding during heating in the aging process when manufacturing the exterior material for power storage devices, and the melting peak temperature is 130°C. By being below, the benefit of the heat resistance improvement effect of the first heat resistant layer 2 and the second heat resistant layer 4 is enhanced.

In addition, at least one of the surface and inside of the first heat-fusible resin layer 1 and the second heat-fusible resin layer 2 includes a lubricant, a flame retardant, an anti-blocking agent, an antioxidant, a light stabilizer, Additives such as tackifiers and antistatic agents may also be present. Only one type of additive may be used, or a mixture of two or more types may be used.

In the present disclosure, a lubricant may be present on the surfaces of the first heat-fusible resin layer 1 and the second heat-fusible resin layer 2, respectively. The lubricant is not particularly limited, but preferably includes an amide lubricant. Specific examples of amide lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, aromatic bisamides, and the like. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, and the like. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, and the like. Furthermore, specific examples of methylolamide include methylolstearamide and the like. Specific examples of saturated fatty acid bisamides include methylene bisstearamide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, and hexamethylene bis stearic acid amide. Examples include acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipic acid amide, N,N'-distearyl sebacic acid amide, and the like. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyladipic acid amide, and N,N'-dioleyl sebacic acid amide. Examples include. Specific examples of fatty acid ester amides include stearamide ethyl stearate. Specific examples of aromatic bisamides include m-xylylene bisstearamide, m-xylylene bishydroxystearamide, and N,N'-distearylisophthalic acid amide. One type of lubricant may be used alone, or two or more types may be used in combination.

When a lubricant is present on the surfaces of the first heat-fusible resin layer 1 and the second heat-fusible resin layer 2, the amount thereof is not particularly limited, but is preferably about 3 mg/m ² or more, for example. Examples include about 4 mg/m ² or more, about 5 mg/m ² or more. Further, the amount of lubricant present on the surface of the first heat-fusible resin layer 1 is, for example, about 15 mg/m ² or less, preferably about 14 mg/m ² or less, and about 10 mg/m ² or less. Further, the preferable range of the amount of lubricant present on the surface of the first heat-fusible resin layer 1 is about 3 to 15 mg/m ² , about 3 to 14 mg/m ² , about 3 to 10 mg/m ² , and about 4 to 15 mg/m 2 . Examples include about 15 mg/m ² , about 4 to 14 mg/m ² , about 4 to 10 mg/m ² , about 5 to 15 mg/m ² , about 5 to 14 mg/m ² , and about 5 to 10 mg/m ² .

The lubricants present on the surfaces of the first heat-fusible resin layer 1 and the second heat-fusible resin layer 2 constitute the first heat-fusible resin layer 1 and the second heat-fusible resin layer 2, respectively. The lubricant contained in the resin may be exuded, or the lubricant may be applied to the surface of the first heat-fusible resin layer 1.

Further, from the viewpoint of more preferably exhibiting the effects of the present disclosure, the thickness of the first heat-fusible resin layer 1 and the second heat-fusible resin layer 2 is preferably about 20 μm or more, and more preferably about 20 μm or more. It is about 30 μm or more, more preferably about 40 μm or more, and preferably about 100 μm or less, more preferably about 80 μm or less, even more preferably about 60 μm or less, and the preferable range is about 20 to 100 μm, 20 to Examples include about 80 μm, about 20 to 60 μm, about 30 to 100 μm, about 30 to 80 μm, about 30 to 60 μm, about 40 to 100 μm, about 40 to 80 μm, and about 40 to 60 μm. When the thickness of the first heat-fusible resin layer 1 and the second heat-fusible resin layer 2 is about 20 μm or more, the sealing strength is easily increased, and when the thickness is about 100 μm or less, the Energy density becomes easier to improve.

In the exterior material 10 for a power storage device of the present disclosure, the first heat-fusible resin layer 1 is formed using a pre-formed resin film (i.e., a resin film containing polyethylene as a main component (polyethylene film)). Alternatively, when laminating the first heat-fusible resin layer 1 with a barrier layer 5, a first heat-resistant layer 3, etc., which will be described later, the resin forming the first heat-fusible resin layer 1 (i.e., polyethylene) may be used. The first heat-fusible resin layer 1 may be formed by forming a resin (main component) into a film (that is, a resin film (polyethylene film)) by extrusion molding, coating, or the like. Regarding the formation of the second heat-fusible resin layer 2, a pre-formed resin film (i.e., a resin film containing polyethylene as a main component (polyethylene film)) may be used, or a second heat-fusible resin When layer 2 is laminated with barrier layer 5, second heat-resistant layer 4, etc., which will be described later, the resin that forms the second heat-fusible resin layer 2 (i.e., the resin whose main component is polyethylene) is extruded or coated. The second heat-fusible resin layer 2 may be formed into a film (ie, as a resin film (polyethylene film)) by a method such as the following. The resin film may be an unstretched film or a stretched film. Examples of the stretched film include uniaxially stretched film and biaxially stretched film, with biaxially stretched film being preferred. Examples of the stretching method for forming a biaxially stretched film include a sequential biaxial stretching method, an inflation method, and a simultaneous biaxial stretching method. Examples of methods for applying the resin include roll coating, gravure coating, and extrusion coating.

[First heat-resistant layer 3 and second heat-resistant layer 4]
The first heat-resistant layer 3 is a layer provided between the first heat-fusible resin layer 1 and the barrier layer 5 as necessary for the purpose of increasing the heat resistance of the exterior material 10 for an electricity storage device. be. Further, the second heat-resistant layer 4 is provided between the second heat-fusible resin layer 2 and the barrier layer 5 as necessary for the purpose of increasing the heat resistance of the exterior material 10 for an electricity storage device. It is a layer.

The first heat-resistant layer 3 and the second heat-resistant layer 4 can each be formed of resin or the like with excellent heat resistance.

From the viewpoint of more preferably exhibiting the effects of the present disclosure, the melting peak temperatures of the first heat-resistant layer 3 and the second heat-resistant layer 4 are preferably about 130° C. or higher, more preferably about 140 to 300° C., and even more preferably about 140 to 300° C. is about 150 to 250°C. Since the melting peak temperature of the first heat-resistant layer 3 and the second heat-resistant layer 4 is 130°C or higher, high heat resistance can be exhibited, and since the melting peak temperature is 250°C or lower, costs can be reduced. advantageous in terms of

Examples of the resin forming the first heat-resistant layer 3 and the second heat-resistant layer 4 include resins such as polyolefin, polyester, polyamide, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenol resin, respectively. Examples include modified resins. Further, the resin forming the first heat-resistant layer 3 and the second heat-resistant layer 4 may be a copolymer of these resins, or may be a modified product of the copolymer. Furthermore, a mixture of these resins may be used.

From the viewpoint of more suitably exhibiting the effects of the present disclosure, the resins forming the first heat-resistant layer 3 and the second heat-resistant layer 4 are preferably polyolefin or polyester.

Specifically, the polyolefin includes polypropylene such as homopolypropylene, a block copolymer of polypropylene (for example, a block copolymer of propylene and ethylene), and a random copolymer of polypropylene (for example, a random copolymer of propylene and ethylene); Polymer; terpolymer of ethylene-butene-propylene and the like. Among these, polypropylene is preferred. The polyolefin resin in the case of a copolymer may be a block copolymer or a random copolymer. These polyolefin resins may be used alone or in combination of two or more.

Additionally, the polyolefin may be a cyclic polyolefin. A cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefin that is a constituent monomer of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. It will be done. Examples of the cyclic monomer that is a constituent monomer of the cyclic polyolefin include cyclic alkenes such as norbornene; cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these, cyclic alkenes are preferred, and norbornene is more preferred.

Additionally, the polyolefin may be an acid-modified polyolefin. Acid-modified polyolefin is a polymer modified by block polymerization or graft polymerization of polyolefin with an acid component. As the acid-modified polyolefin, the aforementioned polyolefins, copolymers obtained by copolymerizing the aforementioned polyolefins with polar molecules such as acrylic acid or methacrylic acid, or polymers such as crosslinked polyolefins can also be used. Further, examples of the acid component used for acid modification include carboxylic acids such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride, or their anhydrides.

The acid-modified polyolefin may be an acid-modified cyclic polyolefin. Acid-modified cyclic polyolefin is a polymer obtained by copolymerizing some of the monomers constituting the cyclic polyolefin in place of the acid component, or by block polymerizing or graft polymerizing the acid component to the cyclic polyolefin. be. The cyclic polyolefin to be acid-modified is the same as described above. Further, the acid component used for acid modification is the same as the acid component used for modifying the polyolefin described above.

Preferred acid-modified polyolefins include polyolefins modified with carboxylic acid or its anhydride, polypropylene modified with carboxylic acid or its anhydride, maleic anhydride-modified polyolefin, and maleic anhydride-modified polypropylene.

Specific examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, copolymerized polyester, and the like. Examples of the copolyester include copolyesters containing ethylene terephthalate as a main repeating unit. Specifically, copolymer polyester polymerized with ethylene isophthalate with ethylene terephthalate as the main repeating unit (hereinafter abbreviated as polyethylene (terephthalate/isophthalate)), polyethylene (terephthalate/adipate), polyethylene (terephthalate/adipate), etc. Examples include sodium sulfoisophthalate), polyethylene (terephthalate/sodium isophthalate), polyethylene (terephthalate/phenyl-dicarboxylate), and polyethylene (terephthalate/decanedicarboxylate). These polyesters may be used alone or in combination of two or more.

The first heat-resistant layer 3 and the second heat-resistant layer 4 may each be formed from one type of resin alone, or may be formed from a blended polymer that is a combination of two or more types of resin. Further, each of the first heat-resistant layer 3 and the second heat-resistant layer 4 may be formed of only one layer, or may be formed of two or more layers of the same or different resins.

In the exterior material 10 for power storage devices of the present disclosure, a pre-formed resin film may be used to form the first heat-resistant layer 3, or the first heat-resistant layer 3 may be replaced by a barrier layer 5 or a first heat-melting layer 5, which will be described later. When laminating with the adhesive resin layer 1 or the like, the first heat-resistant layer 3 may be formed by forming the resin forming the first heat-resistant layer 3 into a film (ie, a resin film) by extrusion molding, coating, or the like. Regarding the formation of the second heat-resistant layer 4, a pre-formed resin film may be used, or when the second heat-resistant layer 4 is laminated with a barrier layer 5, a second heat-fusible resin layer 2, etc., which will be described later. The second heat-resistant layer 4 may be formed by forming the resin forming the second heat-resistant layer 4 into a film (ie, a resin film) by extrusion molding, coating, or the like. The resin film may be an unstretched film or a stretched film. Examples of the stretched film include uniaxially stretched film and biaxially stretched film, with biaxially stretched film being preferred. Examples of the stretching method for forming a biaxially stretched film include a sequential biaxial stretching method, an inflation method, and a simultaneous biaxial stretching method. Examples of methods for applying the resin include roll coating, gravure coating, and extrusion coating.

From the viewpoint of more preferably exhibiting the effects of the present disclosure, the thickness of the first heat-resistant layer 3 and the second heat-resistant layer 4 is preferably about 5 μm or more, more preferably about 10 μm or more, and even more preferably about 20 μm or more. , and is preferably about 50 μm or less, more preferably about 40 μm or less, even more preferably about 30 μm or less, and the preferable range is about 5 to 50 μm, about 5 to 40 μm, about 5 to 30 μm, and 10 to Examples include about 50 μm, about 10 to 40 μm, about 10 to 30 μm, about 20 to 50 μm, about 20 to 40 μm, and about 20 to 30 μm. When the thickness of the first heat-resistant layer 3 and the second heat-resistant layer 4 is about 5 μm or more, resistance to physical contact is increased, and when the thickness is about 50 μm or less, the energy density of the electricity storage device can be improved. .

[First adhesive layer 12, second adhesive layer 22, third adhesive layer 32, fourth adhesive layer 42]
The first adhesive layer 12 is a layer provided as necessary for the purpose of increasing the adhesiveness between the first heat-fusible resin layer 1 and a layer adjacent thereto. Therefore, the first adhesive layer 12 is adjacent to the first heat-fusible resin layer 1 . Further, the second adhesive layer 22 is a layer provided as necessary for the purpose of increasing the adhesiveness between the second heat-fusible resin layer 2 and a layer adjacent thereto. Therefore, the second adhesive layer 22 is adjacent to the second heat-fusible resin layer 2. Further, the third adhesive layer 32 is provided between the first heat resistant layer 3 and the barrier layer 5 as necessary for the purpose of increasing the adhesiveness between the first heat resistant layer 3 and the barrier layer 5. This is the layer where The third adhesive layer 32 is adjacent to the first heat-resistant layer 3. The fourth adhesive layer 42 is provided between the second heat resistant layer 4 and the barrier layer 5 as necessary for the purpose of increasing the adhesiveness between the second heat resistant layer 4 and the barrier layer 5. It is a layer. The fourth adhesive layer 42 is adjacent to the second heat-resistant layer 4 .

The first adhesive layer 12, the second adhesive layer 22, the third adhesive layer 32, and the fourth adhesive layer 42 are each formed of a resin (adhesive) having adhesive properties. The adhesives used for forming the first adhesive layer 12, the second adhesive layer 22, the third adhesive layer 32, and the fourth adhesive layer 42 are not particularly limited, and are chemical reaction type, solvent volatilization type, thermal adhesive, etc. Any type of adhesive, such as a melt type adhesive or a hot pressure type adhesive, may be used. Further, the adhesive may be a two-component curing adhesive (two-component adhesive) or a one-component curing adhesive (one-component adhesive), which does not involve a curing reaction. It may also be made of resin. Moreover, the first adhesive layer 12, the second adhesive layer 22, the third adhesive layer 32, and the fourth adhesive layer 42 may each be a single layer or a multilayer.

Specifically, the adhesive components contained in the adhesive include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyester; polyether; polyurethane; epoxy resin; Phenol resins; polyamides such as nylon 6, nylon 66, nylon 12, and copolymerized polyamides; polyolefin resins such as polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins; polyvinyl acetate; cellulose; (meth)acrylic resins; Examples include polyimide; polycarbonate; amino resins such as urea resin and melamine resin; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; and silicone resins. These adhesive components may be used alone or in combination of two or more. Among these adhesive components, polyurethane (polyurethane adhesive) is preferred. Further, the adhesive strength of these adhesive component resins can be increased by using an appropriate curing agent in combination. The curing agent is selected from among polyisocyanates, polyfunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, etc., depending on the functional groups of the adhesive component.

Examples of the polyurethane adhesive include a polyurethane adhesive that includes a first part containing a polyol compound and a second part containing an isocyanate compound. Preferred examples include two-component curing polyurethane adhesives in which a polyol such as a polyester polyol, a polyether polyol, or an acrylic polyol is used as a first part and an aromatic or aliphatic polyisocyanate is used as a second part. Further, examples of the polyurethane adhesive include a polyurethane adhesive containing a polyurethane compound prepared by reacting a polyol compound and an isocyanate compound in advance, and an isocyanate compound. Further, examples of the polyurethane adhesive include a polyurethane adhesive containing a polyurethane compound prepared by reacting a polyol compound and an isocyanate compound in advance, and a polyol compound. Further, examples of the polyurethane adhesive include, for example, a polyurethane adhesive obtained by curing a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance with moisture in the air or the like. As the polyol compound, it is preferable to use a polyester polyol having a hydroxyl group in the side chain in addition to the hydroxyl group at the end of the repeating unit. Examples of the second agent include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), and diphenylmethane diisocyanate. (MDI), naphthalene diisocyanate (NDI), and the like. Also included are polyfunctional isocyanate modified products of one or more of these diisocyanates. It is also possible to use multimers (for example trimers) as the polyisocyanate compound. Such multimers include adducts, biurets, nurates, and the like. Since the adhesive layer is formed of a polyurethane adhesive, the exterior material for the power storage device has excellent electrolyte resistance, and even if the electrolyte adheres to the side surface, the first heat-fusible resin layer 1 will not peel off. suppressed.

In addition, the first adhesive layer 12, the second adhesive layer 22, the third adhesive layer 32, and the fourth adhesive layer 42 are allowed to contain other components as long as they do not impede the adhesive properties, such as colorants and thermoplastic elastomers. , a tackifier, a filler, etc. The first adhesive layer 12, the second adhesive layer 22, the third adhesive layer 32, and the fourth adhesive layer 42 each contain a coloring agent, so that the exterior material for the electricity storage device can be colored. As the colorant, known colorants such as pigments and dyes can be used. Moreover, only one type of coloring agent may be used, or two or more types of coloring agents may be used in combination.

The type of pigment is not particularly limited as long as it does not impair the adhesive properties of the first adhesive layer 12, second adhesive layer 22, third adhesive layer 32, and fourth adhesive layer 42. Examples of organic pigments include azo pigments, phthalocyanine pigments, quinacridone pigments, anthraquinone pigments, dioxazine pigments, indigothioindigo pigments, perinone-perylene pigments, isoindolenine pigments, and benzimidazolone pigments. Examples of the pigment include carbon black-based, titanium oxide-based, cadmium-based, lead-based, chromium oxide-based, and iron-based pigments, and in addition, mica (mica) fine powder, fish scale foil, and the like.

Among the colorants, carbon black is preferable, for example, in order to make the exterior of the power storage device exterior black.

The average particle diameter of the pigment is not particularly limited, and may be, for example, about 0.05 to 5 μm, preferably about 0.08 to 2 μm. Note that the average particle diameter of the pigment is the median diameter measured by a laser diffraction/scattering particle diameter distribution measuring device.

The pigment content in the first adhesive layer 12, the second adhesive layer 22, the third adhesive layer 32, and the fourth adhesive layer 42 is not particularly limited as long as the exterior material for the electricity storage device is colored, for example. The amount may be about 5 to 60% by weight, preferably 10 to 40% by weight.

The thicknesses of the first adhesive layer 12, the second adhesive layer 22, the third adhesive layer 32, and the fourth adhesive layer 42 are not particularly limited, but are, for example, about 1 μm or more, about 2 μm or more, and, for example, , about 10 μm or less, about 7 μm or less, about 5 μm or less, and preferred ranges are about 1 to 10 μm, about 1 to 7 μm, about 1 to 5 μm, about 2 to 10 μm, about 2 to 7 μm, and about 2 to 5 μm. Can be mentioned.

[Colored layer]
The colored layer is a layer provided as necessary between the first heat-fusible resin layer 1 and the barrier layer 5 (not shown). When the first adhesive layer 12 is provided, a colored layer may be provided between the first heat-fusible resin layer 1 and the first adhesive layer 12 and between the first adhesive layer 12 and the barrier layer 5. .

The colored layer can be formed, for example, by applying ink containing a coloring agent to the surface of the first heat-fusible resin layer 1 or the surface of the barrier layer 5. As the colorant, known colorants such as pigments and dyes can be used. Moreover, only one type of coloring agent may be used, or two or more types of coloring agents may be used in combination.

As specific examples of the coloring agent contained in the colored layer, the same ones as those exemplified in the column [first adhesive layer 12, second adhesive layer 22, third adhesive layer 32, fourth adhesive layer 42] are exemplified. Ru.

[Barrier layer 5]
In the exterior material for a power storage device, the barrier layer 5 is a layer that prevents at least moisture from entering.

Examples of the barrier layer 5 include metal foil, vapor deposited film, and resin layer having barrier properties. Examples of the vapor-deposited film include a metal vapor-deposited film, an inorganic oxide vapor-deposited film, a carbon-containing inorganic oxide vapor-deposited film, etc., and resin layers include polyvinylidene chloride, polymers mainly composed of chlorotrifluoroethylene (CTFE), and tetrafluoroethylene. Examples include fluorine-containing resins such as polymers containing fluoroethylene (TFE) as a main component, polymers having a fluoroalkyl group, and polymers containing fluoroalkyl units as a main component, and ethylene vinyl alcohol copolymers. Further, examples of the barrier layer 5 include a resin film provided with at least one of these vapor-deposited films and a resin layer. A plurality of barrier layers 5 may be provided. It is preferable that the barrier layer 5 includes a layer made of a metal material. Specific examples of the metal material constituting the barrier layer 5 include aluminum alloy, stainless steel, titanium steel, steel plate, etc. When used as metal foil, it includes at least one of aluminum alloy foil and stainless steel foil. It is preferable.

When the aluminum alloy foil is required to have formability as an exterior material for a power storage device, it is more preferable to use a soft aluminum alloy foil made of annealed aluminum alloy, for example, and when higher formability is required. In such cases, it is preferable to use an aluminum alloy foil containing iron. In the aluminum alloy foil containing iron (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, more preferably 0.5 to 2.0% by mass. When the iron content is 0.1% by mass or more, it is possible to obtain an exterior material for a power storage device that has better formability. By having an iron content of 9.0% by mass or less, it is possible to obtain an exterior material for a power storage device that has more excellent flexibility. Examples of the soft aluminum alloy foil include JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P- Aluminum alloy with a composition specified by O One example is foil. Further, silicon, magnesium, copper, manganese, etc. may be added as necessary. Further, softening can be performed by annealing treatment or the like.

Examples of the stainless steel foil include austenitic, ferritic, austenite-ferritic, martensitic, and precipitation hardening stainless steel foils. If further formability is required, the stainless steel foil is preferably made of austenitic stainless steel.

Specific examples of the austenitic stainless steel constituting the stainless steel foil include SUS304, SUS301, SUS316L, etc. Among these, SUS304 is particularly preferred.

In the case of metal foil, the thickness of the barrier layer 5 may be about 9 to 200 μm, as long as it can at least function as a barrier layer to prevent moisture from entering. The thickness of the barrier layer 5 is preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, particularly preferably about 35 μm or less. Further, the thickness of the barrier layer 5 is preferably about 10 μm or more, more preferably about 20 μm or more, and even more preferably about 25 μm or more. Further, the preferable range of the thickness of the barrier layer 5 is about 10 to 85 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 35 μm, about 20 to 85 μm, about 20 to 50 μm, about 20 to 40 μm, and about 20 to 40 μm. Examples include about 35 μm, about 25 to 85 μm, about 25 to 50 μm, about 25 to 40 μm, and about 25 to 35 μm. When the barrier layer 5 is made of aluminum alloy foil, the above-mentioned range is particularly preferable. In addition, from the viewpoint of imparting high formability and high rigidity to the exterior material 10 for power storage devices, the thickness of the barrier layer 3 is preferably about 35 μm or more, more preferably about 45 μm or more, still more preferably about 50 μm or more, and It is preferably about 55 μm or more, and preferably about 200 μm or less, more preferably about 85 μm or less, even more preferably about 75 μm or less, even more preferably about 70 μm or less, and the preferable range is about 35 to 200 μm, 35 μm or less. ~85μm, 35-75μm, 35-70μm, 45-200μm, 45-85μm, 45-75μm, 45-70μm, 50-200μm, 50-85μm, 50-75μm, 50 - about 70 μm, about 55 to 200 μm, about 55 to 85 μm, about 55 to 75 μm, and about 55 to 70 μm. When the exterior material 10 for an electricity storage device has high formability, deep drawing becomes easy, which can contribute to increasing the capacity of the electricity storage device. Further, when the capacity of the power storage device is increased, the weight of the power storage device increases, but the increased rigidity of the exterior material 10 for the power storage device can contribute to high sealing performance of the power storage device. In addition, particularly when the barrier layer 5 is made of stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, still more preferably about 40 μm or less, and even more preferably about 30 μm. It is particularly preferably about 25 μm or less. Further, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Further, the preferable range of the thickness of the stainless steel foil is about 10 to 60 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 30 μm, about 10 to 25 μm, about 15 to 60 μm, about 15 to 50 μm, and about 15 to 50 μm. Examples include about 40 μm, about 15 to 30 μm, and about 15 to 25 μm.

Further, when the barrier layer 5 is a metal foil, it is preferable that a corrosion-resistant film is provided at least on the surface opposite to the first heat-fusible resin layer in order to prevent dissolution and corrosion. The barrier layer 5 may be provided with a corrosion-resistant coating on both sides. Here, the corrosion-resistant film refers to, for example, hydrothermal conversion treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment with nickel or chromium, or corrosion prevention treatment such as applying a coating agent to the surface of the barrier layer. A thin film that provides corrosion resistance (for example, acid resistance, alkali resistance, etc.) to the barrier layer. Specifically, the corrosion-resistant film refers to a film that improves the acid resistance of the barrier layer (acid-resistant film), a film that improves the alkali resistance of the barrier layer (alkali-resistant film), and the like. As the treatment for forming a corrosion-resistant film, one type of treatment may be performed or a combination of two or more types may be performed. Furthermore, it is possible to have not only one layer but also multiple layers. Furthermore, among these treatments, hydrothermal conversion treatment and anodization treatment are treatments in which the surface of the metal foil is dissolved with a treatment agent to form a metal compound with excellent corrosion resistance. Note that these treatments may be included in the definition of chemical conversion treatment. Further, when the barrier layer 5 includes a corrosion-resistant film, the barrier layer 5 includes the corrosion-resistant film.

The corrosion-resistant film is produced by preventing delamination between the barrier layer (for example, aluminum alloy foil) and the first heat-fusible resin layer, and by a reaction between electrolyte and moisture during molding of the exterior material for power storage devices. Hydrogen fluoride prevents the surface of the barrier layer from dissolving and corroding, especially when the barrier layer is made of aluminum alloy foil, the aluminum oxide present on the surface of the barrier layer is prevented from dissolving and corroding, and also prevents the adhesion of the surface of the barrier layer. properties (wettability) to prevent delamination between the first heat-fusible resin layer and the barrier layer during heat sealing, and to prevent delamination between the first heat-fusible resin layer and the barrier layer during molding. Show effectiveness.

Various types of corrosion-resistant coatings are known that are formed by chemical conversion treatment, and mainly include at least one of phosphates, chromates, fluorides, triazinethiol compounds, and rare earth oxides. Examples include corrosion-resistant coatings containing. Examples of chemical conversion treatments using phosphates and chromates include chromic acid chromate treatment, phosphoric acid chromate treatment, phosphoric acid-chromate treatment, and chromate treatment. Examples of the compound include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium diphosphate, chromic acid acetylacetate, chromium chloride, potassium chromium sulfate, and the like. Further, examples of phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphoric acid. Examples of the chromate treatment include etching chromate treatment, electrolytic chromate treatment, coating type chromate treatment, and coating type chromate treatment is preferred. In this coating-type chromate treatment, at least the inner layer side of the barrier layer (for example, aluminum alloy foil) is first coated using a well-known method such as an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, an acid activation method, etc. Degrease treatment is performed using a treatment method, and then metal phosphates such as Cr (chromium) phosphate, Ti (titanium) phosphate, Zr (zirconium) phosphate, and Zn (zinc) phosphate are applied to the degreased surface. Treatment liquids whose main components are salts and mixtures of these metal salts, treatment liquids whose main components are nonmetallic phosphoric acid salts and mixtures of these nonmetallic salts, or combinations of these with synthetic resins, etc. This is a process in which a treatment liquid consisting of a mixture is applied by a well-known coating method such as a roll coating method, a gravure printing method, or a dipping method, and then dried. Various solvents such as water, alcohol solvents, hydrocarbon solvents, ketone solvents, ester solvents, and ether solvents can be used as the treatment liquid, and water is preferable. In addition, the resin component used at this time includes polymers such as phenolic resins and acrylic resins, and aminated phenol polymers having repeating units represented by the following general formulas (1) to (4) are used. Examples include chromate treatment. In addition, in the aminated phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be contained alone or in any combination of two or more. Good too. The acrylic resin must be polyacrylic acid, acrylic acid methacrylate copolymer, acrylic acid maleic acid copolymer, acrylic acid styrene copolymer, or derivatives thereof such as sodium salt, ammonium salt, or amine salt. is preferred. Particularly preferred are polyacrylic acid derivatives such as ammonium salts, sodium salts, or amine salts of polyacrylic acid. In the present disclosure, polyacrylic acid refers to a polymer of acrylic acid. Further, the acrylic resin is also preferably a copolymer of acrylic acid and dicarboxylic acid or dicarboxylic anhydride, such as ammonium salt, sodium salt, Or it is also preferable that it is an amine salt. Only one type of acrylic resin may be used, or a mixture of two or more types may be used.

In the general formulas (1) to (4), X represents a hydrogen atom, a hydroxy group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. Further, R ¹ and R ² are each the same or different and represent a hydroxy group, an alkyl group, or a hydroxyalkyl group. In general formulas (1) to ( ⁴ ), ^the alkyl group represented by Examples include straight chain or branched alkyl groups having 1 to 4 carbon atoms such as tert-butyl group. Furthermore, examples of the hydroxyalkyl group represented by X, R ¹ and R ² include hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group, Straight chain or branched chain with 1 to 4 carbon atoms substituted with one hydroxy group such as hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group Examples include alkyl groups. In the general formulas (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, R ¹ and R ² may be the same or different. In general formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group or a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer having repeating units represented by general formulas (1) to (4) is preferably about 500 to 1,000,000, and preferably about 1,000 to 20,000, for example. More preferred. Aminated phenol polymers can be produced, for example, by polycondensing a phenol compound or a naphthol compound with formaldehyde to produce a polymer consisting of repeating units represented by the above general formula (1) or general formula (3), and then adding formaldehyde to the polymer. and amine (R ¹ R ² NH) to introduce a functional group (-CH ₂ NR ¹ R ² ) into the polymer obtained above. Aminated phenol polymers may be used alone or in combination of two or more.

Another example of a corrosion-resistant film is a film formed by a coating-type corrosion-preventing treatment in which a coating agent containing at least one selected from the group consisting of a rare earth element oxide sol, an anionic polymer, and a cationic polymer is applied. Examples include thin films that are The coating agent may further contain phosphoric acid or a phosphate salt, a crosslinking agent for crosslinking the polymer. The rare earth element oxide sol includes rare earth element oxide fine particles (for example, particles with an average particle size of 100 nm or less) dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, with cerium oxide being preferred from the viewpoint of further improving adhesion. The rare earth element oxides contained in the corrosion-resistant film can be used alone or in combination of two or more. As the liquid dispersion medium for the rare earth element oxide sol, various solvents such as water, alcohol solvents, hydrocarbon solvents, ketone solvents, ester solvents, and ether solvents can be used, with water being preferred. Examples of the cationic polymer include polyethyleneimine, an ionic polymer complex consisting of a polymer containing polyethyleneimine and a carboxylic acid, a primary amine-grafted acrylic resin in which a primary amine is graft-polymerized onto an acrylic main skeleton, polyallylamine or its derivatives. , aminated phenol, etc. are preferred. The anionic polymer is preferably poly(meth)acrylic acid or a salt thereof, or a copolymer containing (meth)acrylic acid or a salt thereof as a main component. Further, it is preferable that the crosslinking agent is at least one selected from the group consisting of a compound having a functional group such as an isocyanate group, a glycidyl group, a carboxyl group, or an oxazoline group, and a silane coupling agent. Moreover, it is preferable that the phosphoric acid or phosphate is a condensed phosphoric acid or a condensed phosphate.

An example of a corrosion-resistant film is to coat fine particles of barium sulfate or metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide in phosphoric acid on the surface of the barrier layer. Examples include those formed by performing baking treatment at temperatures above .degree.

The corrosion-resistant film may have a laminated structure in which at least one of a cationic polymer and an anionic polymer is further laminated, if necessary. Examples of the cationic polymer and anionic polymer include those mentioned above.

Note that the composition of the corrosion-resistant film can be analyzed using, for example, time-of-flight secondary ion mass spectrometry.

The amount of the corrosion-resistant film formed on the surface of the barrier layer 5 in the chemical conversion treatment ^is not particularly limited. is, for example, about 0.5 to 50 mg, preferably about 1.0 to 40 mg, in terms of chromium, the phosphorus compound is, for example, about 0.5 to 50 mg, preferably about 1.0 to 40 mg, in terms of phosphorus, and the aminated phenol polymer. It is desirable that the content is, for example, about 1.0 to 200 mg, preferably about 5.0 to 150 mg.

The thickness of the corrosion-resistant film is not particularly limited, but from the viewpoint of the cohesive force of the film and the adhesion with the barrier layer and the heat-fusible resin layer, it is preferably about 1 nm to 20 μm, more preferably 1 nm to 100 nm. More preferably, it is about 1 nm to 50 nm. The thickness of the corrosion-resistant film can be measured by observation using a transmission electron microscope, or by a combination of observation using a transmission electron microscope and energy dispersive X-ray spectroscopy or electron beam energy loss spectroscopy. Analysis of the composition of the corrosion-resistant film using time-of-flight secondary ion mass spectrometry reveals that, for example, secondary ions consisting of Ce, P, and O (for example, at least one of Ce ₂ PO ₄ ⁺ , CePO ₄ ^- , etc.) peaks derived from secondary ions (for example, at least one of CrPO ₂ ⁺ and CrPO ₄ ^- ) made of Cr, P, and O are detected.

Chemical conversion treatment involves applying a solution containing a compound used to form a corrosion-resistant film to the surface of the barrier layer using a bar coating method, roll coating method, gravure coating method, dipping method, etc., and then changing the temperature of the barrier layer. This is done by heating to a temperature of about 70 to 200°C. Furthermore, before the barrier layer is subjected to the chemical conversion treatment, the barrier layer may be previously subjected to a degreasing treatment using an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, or the like. By performing the degreasing treatment in this manner, it becomes possible to perform the chemical conversion treatment on the surface of the barrier layer more efficiently. In addition, by using an acid degreasing agent in which a fluorine-containing compound is dissolved in an inorganic acid for degreasing treatment, it is possible to not only degrease the metal foil but also form passive metal fluoride. In such cases, only degreasing treatment may be performed.

3. Method for manufacturing an exterior material for an energy storage device The method for manufacturing an exterior material for an energy storage device is not particularly limited as long as a laminate in which each layer of the exterior material for an energy storage device of the present disclosure is laminated can be obtained. A method including a step of laminating the heat-fusible resin layer 1, the barrier layer 5, and the second heat-fusible resin layer 2 in this order can be mentioned. Also in the method for manufacturing an exterior material for a power storage device of the present disclosure, the first heat-fusible resin layer 1 contains polyethylene as a main component, and the second heat-fusible resin layer 2 contains polyethylene as a main component. There is.

An example of the method for manufacturing the exterior material for a power storage device of the present disclosure is as follows.

A laminate is formed in which the first heat-fusible resin layer 1, the first adhesive layer 12, and the barrier layer 5 are laminated in this order. Specifically, the formation of the laminate is performed by applying an adhesive used to form the first adhesive layer 12 on the first heat-fusible resin layer 1 or on the barrier layer 5 whose surface has been subjected to chemical conversion treatment if necessary. is coated and dried by a coating method such as a gravure coating method or a roll coating method, and then the barrier layer 5 or the first heat-fusible resin layer 1 is laminated and the first adhesive layer 12 is cured by a dry lamination method. It can be carried out.

When providing the first heat-resistant layer 3, for example, a laminate is formed in which the first heat-fusible resin layer 1, the first adhesive layer 12, and the first heat-resistant layer 3 are laminated in this order. Specifically, the formation of the laminate is performed by applying the adhesive used for forming the first adhesive layer 12 on the first heat-fusible resin layer 1 or the first heat-resistant layer 3 using a gravure coating method, a roll coating method, etc. It can be performed by a dry lamination method in which the first heat-resistant layer 3 or the first heat-fusible resin layer 1 is laminated and the first adhesive layer 12 is cured after coating and drying by a coating method such as a coating method. Next, the first heat-resistant layer 3 side of the obtained laminate and the barrier layer 5 are laminated. For example, the adhesive used to form the third adhesive layer 32 is applied to the first heat-resistant layer 3 or to the barrier layer 5 whose surface has been subjected to a chemical conversion treatment if necessary, by a coating method such as a gravure coating method or a roll coating method. This can be carried out by a dry lamination method in which after coating and drying, the barrier layer 5 or the first heat-resistant layer 3 is laminated and the third adhesive layer 32 is cured. Furthermore, when the first heat-resistant layer 3 and the barrier layer 5 are laminated without interposing the third adhesive layer 32, extrusion molding or thermal fusion of the first heat-resistant layer 3 can be used.

Next, the second heat-fusible resin layer 2 is laminated on the barrier layer 5 of the obtained laminate. Specifically, the adhesive used to form the second adhesive layer 22 is coated on the second heat-fusible resin layer 2 or on the barrier layer 5 whose surface has been subjected to a chemical conversion treatment if necessary, using a gravure coating method or a roll coating method. It can be performed by a dry lamination method in which the barrier layer 5 or the second heat-fusible resin layer 2 is laminated and the second adhesive layer 22 is cured after coating and drying by a coating method such as a coating method.

When providing the second heat-resistant layer 4, a laminate is formed in which the second heat-fusible resin layer 2, the second adhesive layer 22, and the second heat-resistant layer 4 are laminated in this order. Specifically, the formation of the laminate is performed by applying the adhesive used for forming the second adhesive layer 22 on the second heat-fusible resin layer 2 or the second heat-resistant layer 4 using a gravure coating method or a roll method. It can be performed by a dry lamination method in which the second heat-resistant layer 4 or the second heat-fusible resin layer 2 is laminated and the second adhesive layer 22 is cured after coating and drying by a coating method such as a coating method. Next, the second heat-resistant layer 4 side of the obtained laminate and the barrier layer 5 are laminated. For example, the adhesive used to form the fourth adhesive layer 42 may be applied on the second heat-resistant layer 4 or on the barrier layer 5 whose surface has been subjected to a chemical conversion treatment if necessary, by a coating method such as a gravure coating method or a roll coating method. This can be carried out by a dry lamination method in which the barrier layer 5 or the second heat-resistant layer 4 is laminated after coating and drying, and the fourth adhesive layer 42 is cured. Furthermore, when the second heat-resistant layer 4 and the barrier layer 5 are laminated without interposing the fourth adhesive layer 42, extrusion molding or thermal fusion of the second heat-resistant layer 4 can be used.

As described above, first heat-fusible resin layer 1 / first adhesive layer 12 provided as necessary / first heat-resistant layer 3 provided as necessary / third adhesive layer provided as necessary 32/Barrier layer 5/Fourth adhesive layer 42 provided as necessary/Second heat-resistant layer 4 provided as necessary/Second adhesive layer 22 provided as necessary/Second heat-fusible resin layer 2 is formed in this order, and the adhesiveness of the first adhesive layer 12, second adhesive layer 22, third adhesive layer 32, and fourth adhesive layer 42 provided as necessary is strengthened. For this reason, it may be further subjected to heat treatment.

4. Application of exterior packaging material for power storage devices The exterior packaging material for power storage devices of the present disclosure is used for a package for sealing and accommodating power storage device elements such as a positive electrode, a negative electrode, and an electrolyte. That is, a power storage device element including at least a positive electrode, a negative electrode, and an electrolyte can be housed in a package formed of the exterior material for a power storage device according to the present disclosure to form a power storage device.

Specifically, an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is prepared using the exterior material for an electricity storage device of the present disclosure, with metal terminals connected to each of the positive electrode and the negative electrode protruding outward. , Covering the electricity storage device element so that a flange portion (an area where the heat-fusible resin layers contact each other) is formed around the periphery of the power storage device element, and sealing the heat-fusible resin layers of the flange portion by heat-sealing each other. provides an electricity storage device using an exterior material for an electricity storage device. Note that when a power storage device element is housed in a package formed of the power storage device exterior material of the present disclosure, the heat-fusible resin portion of the power storage device exterior material of the present disclosure is placed on the inside (the surface in contact with the power storage device element). ) to form a package. The heat-fusible resin layers of two exterior materials for power storage devices may be stacked facing each other, and the peripheral edges of the stacked exterior materials for power storage devices may be heat-sealed to form a package; As in the example shown in FIG. 5, a package may be formed by folding and overlapping one exterior material for a power storage device and heat-sealing the peripheral edge portions. When folded and stacked, the package may be formed by heat-sealing the sides other than the folded edges and sealing on three sides, as shown in the example shown in Fig. 5, or the package may be folded back so that a flange can be formed. It may be sealed on all sides, or the exterior material for the power storage device is wrapped around the power storage device element and the heat-sealable resin layers are sealed to form a heat-sealed part and the openings at both ends are closed. A lid body or the like may be arranged in this manner and sealed by heat-sealing with the exterior material for the power storage device wrapped around the power storage device element. The lid body can be formed of, for example, a resin molded product, a metal molded product, an exterior material for a power storage device, or the like. Further, a recessed portion for accommodating the power storage device element may be formed in the exterior material for the power storage device by deep drawing or stretch molding. As in the example shown in FIG. 5, one exterior material for an energy storage device may have a recess and the other exterior material for an energy storage device may not have a recess, or the other exterior material for an energy storage device may also have a recess. may be provided.

The exterior material for power storage devices of the present disclosure can be suitably used for power storage devices such as batteries (including capacitors, capacitors, etc.). Further, the exterior material for a power storage device of the present disclosure may be used for either a primary battery or a secondary battery, but is preferably used for a secondary battery. The types of secondary batteries to which the exterior material for power storage devices of the present disclosure is applied are not particularly limited, and include, for example, lithium-ion batteries, lithium-ion polymer batteries, all-solid-state batteries, semi-solid-state batteries, pseudo-solid-state batteries, and polymer batteries. , all-resin batteries, lead-acid batteries, nickel-hydrogen batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver-zinc oxide batteries, metal-air batteries, polyvalent cation batteries, capacitors, capacitors, etc. . Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are suitable for application of the exterior material for power storage devices of the present disclosure.

As mentioned above, power storage devices are used for various purposes, and the needs for power storage devices are also diverse. Since the exterior material 10 for a power storage device of the present disclosure has a function of thermally fusing an adherend, it can also provide a power storage device with a function of thermally fusing an adherend. . If the power storage device of the present disclosure is fixed in a product by heat fusion, or if a plurality of power storage devices are stacked and fixed by heat fusion, the plurality of power storage devices can be incorporated into the product in a stacked state. Even in cases where the power storage devices are fixed, each power storage device is fixed, which has the advantage of suppressing misalignment of the power storage devices due to product vibration or damage caused by shocks transmitted to each power storage device when external force is applied to the product. There is.

The present disclosure will be explained in detail by showing Examples and Comparative Examples below. However, the present disclosure is not limited to the examples.

<Manufacture of exterior materials for power storage devices>
Example 1
As the first heat-fusible resin layer and the second heat-fusible resin layer, high-density polyethylene (HDPE) films (thickness 50 μm, melting peak temperature 130°C, water vapor permeability 0.28 g・mm/m ²・24h) was prepared. Unstretched polypropylene (CPP) films (thickness: 30 μm, melting peak temperature: 161° C., water vapor permeability: 0.40 g·mm/m ² ·24 h) were prepared as the first heat-resistant layer and the second heat-resistant layer, respectively. As a barrier layer, aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 40 μm) was prepared. Both sides of the aluminum alloy foil were chemically treated. The chemical conversion treatment of the aluminum alloy foil was performed using phenol resin, A treatment solution consisting of a chromium fluoride compound and phosphoric acid was applied to both sides of an aluminum alloy foil using a roll coating method so that the amount of chromium applied was 10 mg/m ² (dry mass), and then baked. .

By adhering the first heat-fusible resin layer and the first heat-resistant layer using a polyolefin adhesive (acid-modified polyolefin compound) that forms the first adhesive layer, and performing an aging treatment, the first A laminate 1 was obtained in which a heat-fusible resin layer (thickness: 50 μm)/first adhesive layer (thickness after curing: 1.5 μm)/first heat-resistant layer (thickness: 30 μm) were laminated in this order from the outside. .

In addition, by bonding the second heat-fusible resin layer and the second heat-resistant layer using a polyolefin adhesive (acid-modified polyolefin compound) that forms the second adhesive layer, and performing an aging treatment, A laminate 2 of second heat-resistant layer (thickness: 30 μm)/second adhesive layer (thickness: 1.5 μm)/second heat-fusible resin layer (thickness: 50 μm) was produced.

Next, the surface of the laminate 1 on the first heat-resistant layer side and the barrier layer are bonded using a polyolefin adhesive (acid-modified polyolefin compound) that forms a third adhesive layer, and an aging treatment is performed. By this, first heat-fusible resin layer (thickness: 50 μm) / first adhesive layer (thickness after curing is 1.5 μm) / first heat-resistant layer (thickness: 30 μm) / third adhesive layer (after curing) A laminate 3 of 1.5 μm thick/barrier layer (40 μm thick) was prepared. Next, the surface of the laminate 3 on the barrier layer side and the surface of the laminate 2 on the second heat-resistant layer side are bonded together using a polyolefin adhesive (acid-modified polyolefin compound) that forms a fourth adhesive layer. Then, by performing the aging treatment, the first heat-fusible resin layer (thickness: 50 μm)/first adhesive layer (thickness after curing is 1.5 μm)/first heat-resistant layer (thickness: 30 μm)/ Third adhesive layer (thickness after curing is 1.5 μm) / Barrier layer (thickness 40 μm) / Fourth adhesive layer (thickness after curing is 1.5 μm) / Second heat-resistant layer (thickness 30 μm) / A laminate of second adhesive layer (thickness after curing is 1.5 μm)/second heat-fusible resin layer (thickness 50 μm) was produced, and used as an exterior material for a power storage device.

Example 2
As the first heat-fusible resin layer and the second heat-fusible resin layer, high-density polyethylene (HDPE) films (thickness 50 μm, melting peak temperature 130°C, water vapor permeability 0.28 g・mm/m ²・24h) was prepared. As the first heat-resistant layer, an unstretched polypropylene (CPP) film (thickness: 30 μm, melting peak temperature: 161° C., water vapor permeability: 0.40 g·mm/m ² ·24 h) was prepared. As the second heat-resistant layer, maleic anhydride-modified polypropylene (PPa) (thickness: 30 μm, melting peak temperature: 160° C., water vapor permeability: 0.45 g·mm/m ² ·24 h) was prepared. As a barrier layer, aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 40 μm) was prepared. Both sides of the aluminum alloy foil were chemically treated. The chemical conversion treatment of the aluminum alloy foil was performed using phenol resin, A treatment solution consisting of a chromium fluoride compound and phosphoric acid was applied to both sides of an aluminum alloy foil using a roll coating method so that the amount of chromium applied was 10 mg/m ² (dry mass), and then baked. .

In the same manner as in Example 1, the first heat-fusible resin layer and the first heat-resistant layer were adhered using a polyolefin adhesive (acid-modified polyolefin compound) forming the first adhesive layer, and then subjected to aging treatment. By carrying out, the first heat-fusible resin layer (thickness: 50 μm)/first adhesive layer (thickness after curing is 1.5 μm)/first heat-resistant layer (thickness: 30 μm) are laminated in order from the outside. A laminate 1 was obtained.

Next, in the same manner as in Example 1, the surface of the laminate 1 on the first heat-resistant layer side and the barrier layer were bonded using a polyolefin adhesive (acid-modified polyolefin compound) that forms the third adhesive layer. By adhering and performing aging treatment, the first heat-fusible resin layer (thickness: 50 μm)/first adhesive layer (thickness after curing is 1.5 μm)/first heat-resistant layer (thickness: 30 μm) A laminate 3 of /third adhesive layer (thickness after curing is 1.5 μm)/barrier layer (thickness 40 μm) was produced.

Next, a second heat-resistant layer was laminated on the barrier layer side surface of the laminate 3 by melt-extruding the resin forming the second heat-resistant layer. Furthermore, the surface of the second heat-resistant layer side of the obtained laminate and the second heat-fusible resin layer are adhered using a polyolefin adhesive (acid-modified polyolefin compound) that forms the second adhesive layer, and aging is performed. The treatment is carried out to laminate the second heat-fusible resin layer, and the first heat-fusible resin layer (thickness: 50 μm)/first adhesive layer (thickness after curing is 1.5 μm)/first Heat-resistant layer (30 μm thick) / 3rd adhesive layer (1.5 μm thick after curing) / Barrier layer (40 μm thick) / 2nd heat-resistant layer (30 μm thick) / 2nd adhesive layer (1.5 μm thick after curing) A laminate of 1.5 μm thick/2nd heat-fusible resin layer (50 μm thick) was produced, and used as an exterior material for a power storage device.

Example 3
As the first heat-fusible resin layer and the second heat-fusible resin layer, high-density polyethylene (HDPE) films (thickness 50 μm, melting peak temperature 130°C, water vapor permeability 0.28 g・mm/m ²・24h) was prepared. In addition, maleic anhydride-modified polypropylene (PPa) (thickness 30 μm, melting peak temperature 160°C, water vapor permeability 0.45 g·mm/m ² ·24 h) was used as the first heat-resistant layer and the second heat-resistant layer, respectively. . As a barrier layer, aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 40 μm) was prepared. Both sides of the aluminum alloy foil were chemically treated. The chemical conversion treatment of the aluminum alloy foil was performed using phenol resin, A treatment solution consisting of a chromium fluoride compound and phosphoric acid was applied to both sides of an aluminum alloy foil using a roll coating method so that the amount of chromium applied was 10 mg/m ² (dry mass), and then baked. .

First, a resin forming a first heat-resistant layer is melt-extruded on one surface of the barrier layer to form a first heat-resistant layer, and a resin forming a second heat-resistant layer is further formed on the other surface of the barrier layer. A second heat-resistant layer was formed by melt-extruding to obtain a laminate of first heat-resistant layer (thickness: 30 μm)/barrier layer (thickness: 40 μm)/second heat-resistant layer (thickness: 30 μm).

Next, the first heat-resistant layer (thickness: 30 μm) side surface of the obtained laminate and the first heat-fusible resin layer are bonded together using a polyolefin adhesive (acid-modified polyolefin compound) that forms the first adhesive layer. ), and by performing aging treatment, the first heat-fusible resin layer (thickness: 50 μm)/first adhesive layer (thickness after curing: 1.5 μm)/first heat-resistant layer ( A laminate was obtained in which layers (thickness: 30 μm)/barrier layer (thickness: 40 μm)/second heat-resistant layer (thickness: 30 μm) were laminated in this order from the outside.

Furthermore, the second heat-resistant layer (thickness: 30 μm) side surface of the obtained laminate and the second heat-fusible resin layer are bonded using a polyolefin adhesive (acid-modified polyolefin compound) that forms the second adhesive layer. By adhering using a resin and performing an aging treatment, the first heat-fusible resin layer (thickness: 50 μm)/first adhesive layer (thickness after curing is 1.5 μm)/first heat-resistant layer (thickness: thickness 30 μm) / barrier layer (thickness 40 μm) / second heat-resistant layer (thickness 30 μm) / second adhesive layer (thickness after curing is 1.5 μm) / second heat-fusible resin layer (thickness 50 μm) ) was produced and used as an exterior material for power storage devices.

Example 4
As the first heat-fusible resin layer and the second heat-fusible resin layer, high-density polyethylene (HDPE) films (thickness 50 μm, melting peak temperature 130°C, water vapor permeability 0.28 g・mm/m ²・Example 3 except that a maleic anhydride-modified polyethylene (PEa) film (thickness 50 μm, melting peak temperature 128°C, water vapor permeability 0.46 g mm/m ² ·24 h) was used instead of 24 h). Similarly, first heat-fusible resin layer (thickness: 50 μm)/first adhesive layer (thickness after curing is 1.5 μm)/first heat-resistant layer (thickness: 30 μm)/barrier layer (thickness: 40 μm) ) / second heat-resistant layer (thickness: 30 μm) / second adhesive layer (thickness after curing: 1.5 μm) / second heat-fusible resin layer (thickness: 50 μm) was prepared, and a power storage device was fabricated. It was used as an exterior material.

Example 5
As the first heat-resistant layer and the second heat-resistant layer, anhydrous anhydride was used instead of maleic anhydride-modified polypropylene (PPa) (thickness 30 μm, melting peak temperature 160°C, water vapor permeability 0.45 g・mm/m ²・24 h). Maleic acid-modified polypropylene (PPa) (thickness 15 μm, melting peak temperature 160°C, water vapor permeability 0.45 g・mm/m ²・24 h) and polypropylene (PP) (thickness 15 μm, melting peak temperature 160°C, water vapor permeability 0) The first heat-fusible resin layer (thickness 50 μm) was prepared in the same manner as in Example 3, except that a laminate (formed by melt extrusion of PPa and ^PP ) of ) / first adhesive layer (thickness after curing is 1.5 μm) / first heat-resistant layer (thickness 30 μm) / barrier layer (thickness 40 μm) / second heat-resistant layer (thickness 30 μm) / second adhesive layer (Thickness after curing: 1.5 μm)/Second heat-fusible resin layer (thickness: 50 μm) A laminate was produced and used as an exterior material for a power storage device. Note that the PPa of the first heat-resistant layer and the second heat-resistant layer were respectively arranged on the barrier layer side.

Example 6
As the first heat-resistant layer and the second heat-resistant layer, anhydrous anhydride was used instead of maleic anhydride-modified polypropylene (PPa) (thickness 30 μm, melting peak temperature 160°C, water vapor permeability 0.45 g・mm/m ²・24 h). Maleic acid-modified polypropylene (PPa) (thickness 15 μm, melting peak temperature 160°C, water vapor permeability 0.45 g・mm/m ²・24 h) and polypropylene (PP) (thickness 15 μm, melting peak temperature 160°C, water vapor permeability 0) ^The first heat-fusible resin layer (thickness 50 μm) was prepared in the same manner as in Example 4, except that a laminate (formed by melt extrusion of PPa and PP) of ) / first adhesive layer (thickness after curing is 1.5 μm) / first heat-resistant layer (thickness 30 μm) / barrier layer (thickness 40 μm) / second heat-resistant layer (thickness 30 μm) / second adhesive layer (Thickness after curing: 1.5 μm)/Second heat-fusible resin layer (thickness: 50 μm) A laminate was produced and used as an exterior material for a power storage device. Note that the PPa of the first heat-resistant layer and the second heat-resistant layer were respectively arranged on the barrier layer side.

Comparative example 1
Polypropylene (PP) (thickness 50 μm, melting peak temperature 160°C, water vapor permeability 0.40 g・mm/m ²・24 h) was used as the first heat-fusible resin layer and the second heat-fusible resin layer, respectively. Prepared. In addition, maleic anhydride-modified polypropylene (PPa) (thickness 30 μm, melting peak temperature 160°C, water vapor permeability 0.45 g·mm/m ² ·24 h) was used as the first heat-resistant layer and the second heat-resistant layer, respectively. . As a barrier layer, aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 40 μm) was prepared. Both sides of the aluminum alloy foil were chemically treated. The chemical conversion treatment of the aluminum alloy foil was performed using phenol resin, A treatment solution consisting of a chromium fluoride compound and phosphoric acid was applied to both sides of an aluminum alloy foil using a roll coating method so that the amount of chromium applied was 10 mg/m ² (dry mass), and then baked. .

Next, the resin forming the first heat-fusible resin layer is melt-extruded onto the first heat-resistant layer (thickness: 30 μm) side surface of the obtained laminate, and the first heat-fusible resin layer (thickness: A laminate was obtained in which the following layers were sequentially laminated from the outside: first heat-resistant layer (thickness: 50 μm)/first heat-resistant layer (thickness: 30 μm)/barrier layer (thickness: 40 μm)/second heat-resistant layer (thickness: 30 μm).

Furthermore, a resin forming a second heat-fusible resin layer is melt-extruded on the second heat-resistant layer (thickness: 30 μm) side surface of the obtained laminate, and a first heat-fusible resin layer (thickness: 50 μm) is melt-extruded. )/first heat-resistant layer (thickness: 30 μm)/barrier layer (thickness: 40 μm)/second heat-resistant layer (thickness: 30 μm)/second heat-fusible resin layer (thickness: 50 μm). Used as exterior material for power storage devices.

Comparative example 2
As the first heat-resistant layer and the second heat-resistant layer, anhydrous anhydride was used instead of maleic anhydride-modified polypropylene (PPa) (thickness 30 μm, melting peak temperature 160°C, water vapor permeability 0.45 g・mm/m ²・24 h). Maleic acid-modified polypropylene (PPa) (thickness 15 μm, melting peak temperature 160°C, water vapor permeability 0.45 g・mm/m ²・24 h) and polypropylene (PP) (thickness 15 μm, melting peak temperature 160°C, water vapor permeability 0) ^The first heat-fusible resin layer (thickness 50 μm )/first heat-resistant layer (thickness: 30 μm)/barrier layer (thickness: 40 μm)/second heat-resistant layer (thickness: 30 μm)/second heat-fusible resin layer (thickness: 50 μm). , used as an exterior material for power storage devices. Note that the PPa of the first heat-resistant layer and the second heat-resistant layer were respectively arranged on the barrier layer side.

<Measurement method of water vapor permeability>
The measurement of water vapor permeability is based on JIS K 7129-2 "Plastics - Films and sheets - Determination of water vapor permeability - Part 2: Infrared sensor method", and the measuring device is MOCON's product name "PERMATRAN". ” was used. After cutting the film-like sample into 100 mm x 100 mm, it was measured under conditions of 40° C. and 90% RH to determine the water vapor permeability. The unit of water vapor permeability is g/( ^m2・24h), but in order to make it easier to compare the numerical values of test samples with different thicknesses, the numerical value obtained by measurement is calculated using a thickness of 1.0 mm. The unit g·mm/m ² ·24h was used.

[Measurement of seal strength]
In accordance with the regulations of JIS K7127:1999, the seal strength of the exterior material for a power storage device at a measurement temperature of 25° C. environment was measured as follows. As a test sample, an exterior material for a power storage device was prepared which was cut into strips having a width in the TD direction of 15 mm. Specifically, as shown in FIG. 6, each exterior material for an electricity storage device was first cut into 60 mm (TD direction) x 200 mm (MD direction) (FIG. 6a). Next, the exterior material for a power storage device was folded in half in the MD direction at a crease P (middle in the MD direction) so that the outer first heat-fusible resin layers faced each other (FIG. 6b). About 10 mm inside from the crease P in the MD direction, the first heat-fusible resin layers were bonded together under the conditions of a seal width of 7 mm, each temperature (°C), surface pressure (MPa), and time (seconds) listed in Table 1. Heat sealed (Figure 6c). During heat sealing, the heat seal bar was coated with Teflon (registered trademark) so that the molten heat-adhesive resin layer did not adhere to the heat seal bar. In FIG. 6c, the shaded area S is the heat-sealed area. Next, test sample 13 was obtained by cutting in the MD direction (cutting at the position of the two-dot chain line in FIG. 6d) so that the width in the TD direction was 15 mm (FIG. 6e). Next, the test sample 13 was left for 2 minutes at each measurement temperature, and in each measurement temperature environment, a tensile tester (manufactured by Shimadzu Corporation, AG-Xplus (trade name)) was used to test the first thermal bonding property of the thermally bonded part. The resin layer was peeled off at a speed of 300 mm/min (FIG. 7). The maximum strength at the time of peeling was defined as the seal strength (N/15 mm). The distance between chucks is 50 mm. The average value of three measurements was taken. Seal strength was evaluated based on the following criteria. The results are shown in Table 1. In the measurement of seal strength, the test sample 13 is peeled off (destroyed) at the heat seal interface A shown in FIG. In some cases, the test sample 13 may break. When the test sample 13 breaks, the breaking strength is taken as the sealing strength.
A: Seal strength is 30N/15mm or more.
B: Seal strength is 20 N/15 mm or more and less than 30 N/15 mm.
C: Seal strength is less than 20N/15mm.

[Measurement of thickness remaining rate]
Similar to the sample used in the above-mentioned [Measurement of seal strength], the sample used in [Measurement of thickness residual rate] uses the exterior material for a power storage device before and after heat sealing, and the first heat-resistant layer and the second heat-resistant layer. Measure the total thickness of the layer, and calculate the ratio (%) of the total thickness of the first heat-resistant layer and second heat-resistant layer after heat-sealing to the total thickness of the first heat-resistant layer and second heat-resistant layer before heat-sealing. did. The residual rate of total thickness was the average value of the two measurement samples. The thickness was measured by cutting the measurement sample in the thickness direction using a microtome (REM-710 litratome manufactured by Daiwa Koki Industries), and observing the obtained cross section with a laser microscope (VK-9700 manufactured by Keyence). went. The thickness residual rate was evaluated based on the following criteria. The results are shown in Table 1.
A: The thickness remaining rate is 80% or more.
B: The thickness residual rate is 70% or more and less than 80%.
C: Thickness remaining rate is less than 70%.

[Evaluation of insulation]
The exterior material 10 for a power storage device was cut to produce a strip with a width of 40 mm and a length of 100 mm, which was used as a test sample. Note that the width refers to the TD direction, and the length refers to the MD direction. After arranging a stainless steel wire 20 with a diameter of 25 μm and a length of 70 mm at the center in the width direction on the side of the second heat-fusible resin layer of the strip, an aluminum plate 30 with a width of 30 mm, a length of 100 mm, and a thickness of 100 μm was placed on each test sample. It was arranged so as to face the second heat-fusible resin layer side. At this time, the center of the strip in the width direction was made to coincide with the center of the aluminum plate 30 in the width direction. Next, the positive electrode of the tester was connected to the aluminum plate 30, and the negative electrode was connected to the exterior material for the power storage device. For the negative terminal of the tester, insert an alligator clip so that it reaches the barrier layer from the first heat-fusible resin layer side of the exterior material for the power storage device, and electrically connect the negative terminal of the tester and the barrier layer. Ta. The tester was prepared to issue a continuity (short circuit) signal when the applied voltage was 100 V and the resistance was 200 MΩ or less. Next, a voltage of 100V is applied between the testers, and in this state, with the stainless steel wire 20 interposed between the aluminum plate 30 and the exterior material for the power storage device, the seal width is 7 mm, and the surface is made perpendicular to the wire 20. The first heat-fusible resin layers were heat-sealed to each other under the conditions of each temperature (° C.) and surface pressure (MPa) described in Section 1, and the time until a short circuit signal was generated was measured. The measurement was performed five times, and the longest and shortest points were excluded to take the average value of the three points. The insulation was evaluated based on the following criteria. The results are shown in Table 1.
A+: The time until short circuit occurs is 40 seconds or more.
A: The time until short circuit occurs is 30 seconds or more and less than 40 seconds.
B: The time until short circuit occurs is 20 seconds or more and less than 30 seconds.
C: The time until short circuit occurs is less than 20 seconds.

The exterior materials for power storage devices of Examples 1 to 6 are composed of a laminate including, in order from the outside, at least a first heat-fusible resin layer, a barrier layer, and a second heat-fusible resin layer, The first heat-fusible resin layer contains polyethylene as a main component, and the second heat-fusible resin layer contains polyethylene as a main component. In the exterior materials for power storage devices of Examples 1 to 6, the sealing strength of the first heat-fusible resin layer located on the outside was high, and collapse after sealing was suppressed, and the insulation properties were excellent. From these results, it is evaluated that the exterior materials for power storage devices of Examples 1 to 6 can be used by heat-sealing the outer surface of the power storage device to the adherend by applying it to the power storage device. Ru.

As described above, the present disclosure provides inventions of the following aspects.
Item 1. Consisting of a laminate including, in order from the outside, at least a first heat-fusible resin layer, a barrier layer, and a second heat-fusible resin layer,
The first heat-fusible resin layer contains polyethylene as a main component,
The second heat-fusible resin layer is an exterior material for a power storage device, which contains polyethylene as a main component.
Item 2. Item 2. The exterior material for an electricity storage device according to Item 1, wherein the first heat-fusible resin layer has a thickness of 30 μm or more.
Item 3. Item 3. The exterior material for an electricity storage device according to Item 1 or 2, wherein the polyethylene of the first heat-fusible resin layer is high-density polyethylene.
Item 4. Any one of items 1 to 3, wherein the polyethylene of the second heat-fusible resin layer has a water vapor permeability of 0.50 g mm/m ² 24 h or less in an environment of 40° C. and 90% RH. The exterior material for the electricity storage device described above.
Item 5. Item 5. The exterior material for a power storage device according to any one of Items 1 to 4, wherein the polyethylene of the second heat-fusible resin layer is high-density polyethylene.
Item 6. Item 6. The exterior material for a power storage device according to any one of Items 1 to 5, wherein the first heat-fusible resin layer has a melting peak temperature of 130° C. or less.
Section 7. Item 7. The exterior material for a power storage device according to any one of Items 1 to 6, wherein the second heat-fusible resin layer has a melting peak temperature of 130° C. or less.
Section 8. Item 8. The exterior material for a power storage device according to any one of Items 1 to 7, further comprising a first heat-resistant layer between the first heat-fusible resin layer and the barrier layer.
Item 9. Item 9. The exterior material for a power storage device according to Item 8, wherein the first heat-resistant layer contains polypropylene or acid-modified polypropylene as a main component.
Item 10. Item 9. The exterior material for an electricity storage device according to Item 8 or 9, wherein the first heat-resistant layer has a thickness of 15 μm or more.
Item 11. Item 11. The exterior material for an electricity storage device according to any one of Items 1 to 10, further comprising a second heat-resistant layer between the barrier layer and the second heat-fusible resin layer.
Item 12. Item 12. The exterior material for a power storage device according to Item 11, wherein the second heat-resistant layer contains polypropylene or acid-modified polypropylene as a main component.
Item 13. Item 13. The exterior material for an electricity storage device according to Item 11 or 12, wherein the second heat-resistant layer has a thickness of 15 μm or more.
Section 14. Any one of Items 1 to 13, wherein the polyethylene of the first heat-fusible resin layer has a water vapor permeability of 0.50 g mm / m ² · 24 h or less in an environment of 40 ° C. and 90% RH. The exterior material for the electricity storage device described above.
Item 15. Item 15. The exterior material for a power storage device according to any one of Items 1 to 14, wherein the second heat-fusible resin layer has a thickness of 30 μm or more.
Section 16. Item 16. The exterior packaging material for a power storage device according to any one of Items 1 to 15, wherein the barrier layer has a thickness of 30 μm or more.
Section 17. Item 17. The exterior packaging material for a power storage device according to any one of Items 1 to 16, wherein the barrier layer is made of aluminum alloy foil or stainless steel foil.
Section 18. A step of obtaining a laminate including at least a first heat-fusible resin layer, a barrier layer, and a second heat-fusible resin layer in order from the outside,
The first heat-fusible resin layer contains polyethylene as a main component,
The method for manufacturing an exterior material for a power storage device, wherein the second heat-fusible resin layer contains polyethylene as a main component.
Item 19. An electricity storage device, wherein an electricity storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of the exterior material for an electricity storage device according to any one of Items 1 to 17.
Section 20. Item 20. The electricity storage device according to Item 19, wherein the first heat-fusible resin layer constituting the outer surface of the electricity storage device is used so as to be heat-sealed to an adherend.
Section 21. Item 19 or 20. The power storage device according to item 19 or 20, wherein the first heat-fusible resin layers constituting the outer surface of the power storage device are thermally fused to each other so that a plurality of power storage devices are stacked. device.

1 First heat-fusible resin layer 2 Second heat-fusible resin layer 3 First heat-resistant layer 4 Second heat-resistant layer 5 Barrier layer 10 Exterior material for power storage device 12 First adhesive layer 13 Test sample 22 Second adhesive layer 20 wire 30 aluminum plate 32 third adhesive layer 42 fourth adhesive layer

Claims

Consisting of a laminate including, in order from the outside, at least a first heat-fusible resin layer, a barrier layer, and a second heat-fusible resin layer,
The first heat-fusible resin layer contains polyethylene as a main component,
The second heat-fusible resin layer is an exterior material for a power storage device, which contains polyethylene as a main component.
The exterior material for a power storage device according to claim 1, wherein the first heat-fusible resin layer has a thickness of 30 μm or more.
The exterior material for a power storage device according to claim 1 or 2, wherein the polyethylene of the first heat-fusible resin layer is high-density polyethylene.
The electricity storage device according to claim 1 or 2, wherein the polyethylene of the second heat-fusible resin layer has a water vapor permeability of 0.50 g·mm/m 2 ·24 h or less in a 40° C., 90% RH environment. exterior material.
The exterior material for a power storage device according to claim 1 or 2, wherein the polyethylene of the second heat-fusible resin layer is high-density polyethylene.
The exterior material for an electricity storage device according to claim 1 or 2, wherein the first heat-fusible resin layer has a melting peak temperature of 130°C or less.
The exterior material for an electricity storage device according to claim 1 or 2, wherein the second heat-fusible resin layer has a melting peak temperature of 130°C or less.
The exterior material for an electricity storage device according to claim 1, further comprising a first heat-resistant layer between the first heat-fusible resin layer and the barrier layer.
The exterior material for a power storage device according to claim 8, wherein the first heat-resistant layer contains polypropylene or acid-modified polypropylene as a main component.
The exterior material for an electricity storage device according to claim 8 or 9, wherein the first heat-resistant layer has a thickness of 15 μm or more.
The exterior material for an electricity storage device according to claim 1 or 2, further comprising a second heat-resistant layer between the barrier layer and the second heat-fusible resin layer.
The exterior material for a power storage device according to claim 11, wherein the second heat-resistant layer contains polypropylene or acid-modified polypropylene as a main component.
The exterior material for an electricity storage device according to claim 11 or 12, wherein the second heat-resistant layer has a thickness of 15 μm or more.
The electricity storage device according to claim 1 or 2, wherein the polyethylene of the first heat-fusible resin layer has a water vapor permeability of 0.50 g·mm/m 2 ·24 h or less in a 40° C., 90% RH environment. exterior material.
The exterior material for an electricity storage device according to claim 1 or 2, wherein the second heat-fusible resin layer has a thickness of 30 μm or more.
The exterior material for a power storage device according to claim 1 or 2, wherein the barrier layer has a thickness of 30 μm or more.
The exterior material for an electricity storage device according to claim 1 or 2, wherein the barrier layer is made of aluminum alloy foil or stainless steel foil.
A step of obtaining a laminate including at least a first heat-fusible resin layer, a barrier layer, and a second heat-fusible resin layer in order from the outside,
The first heat-fusible resin layer contains polyethylene as a main component,
The method for manufacturing an exterior material for a power storage device, wherein the second heat-fusible resin layer contains polyethylene as a main component.
An electricity storage device, wherein an electricity storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of the exterior material for an electricity storage device according to claim 1 or 2.
The power storage device according to claim 19, wherein the first heat-fusible resin layer forming the outer surface of the power storage device is used so as to be heat-sealed to an adherend.
The power storage device according to claim 19, wherein the first heat-fusible resin layers constituting the outer surface of the power storage device are heat-sealed to each other, so that a plurality of power storage devices are used in a stacked manner. .