WO2021201293A1

WO2021201293A1 - Outer packaging for electrical storage devices, method for manufacturing said outer packaging, and electrical storage device

Info

Publication number: WO2021201293A1
Application number: PCT/JP2021/014412
Authority: WO
Inventors: 純景山; 憲村澤
Original assignee: 大日本印刷株式会社
Priority date: 2020-04-03
Filing date: 2021-04-02
Publication date: 2021-10-07
Also published as: JPWO2021201293A1

Abstract

Provided is an outer packaging for electrical storage devices that is composed of a laminate provided with at least a substrate layer, a barrier layer, and a thermally adhesive resin layer in this order, wherein in heat seal strength measurement, in which measurement is performed upon heat-sealing together the thermally adhesive resin layer under conditions of a temperature of 190°C and a specific pressure of 1.0 MPa for 3 seconds and then separating the thermally adhesive resin layer, the heat seal strength decrease temperature T°C of the outer packaging for electrical storage devices is within the measured temperature of range of 110°C to 120°C. Heat seal strength decrease temperature T°C: the measured temperature in the heat seal strength measurement at which the heat seal strength reaches 35 N/15 mm or higher, and at which the heat seal strength at the heat seal strength decrease temperature T°C +10°C is 10 N/15 mm or lower.

Description

Exterior materials for power storage devices, their manufacturing methods, and power storage devices

This disclosure relates to an exterior material for a power storage device, a manufacturing method thereof, and a power storage device.

Conventionally, various types of power storage devices have been developed, but in all power storage devices, an exterior material is an indispensable member for sealing the power storage device elements such as electrodes and electrolytes. Conventionally, a metal exterior material has been widely used as an exterior material for a power storage device.

On the other hand, in recent years, with the improvement of high performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., various shapes are required for power storage devices, and thinning and weight reduction are required. However, the metal exterior material for a power storage device, which has been widely used in the past, has a drawback that it is difficult to keep up with the diversification of shapes and there is a limit to weight reduction.

Therefore, conventionally, as an exterior material for a power storage device that can be easily processed into various shapes and can be made thinner and lighter, a base material layer / barrier layer / adhesive layer / heat-sealing resin layer is sequentially laminated. A film-like laminate has been proposed (see, for example, Patent Document 1).

In such an exterior material for a power storage device, a recess is generally formed by cold forming, and a heat-sealing resin such as an electrode or an electrolytic solution is arranged in the space formed by the recess. By heat-sealing the layers, a power storage device in which the power storage device element is housed inside the exterior material for the power storage device can be obtained.

Japanese Unexamined Patent Publication No. 2008-287971 Japanese Unexamined Patent Publication No. 2002-8616

In recent years, with the shift to high-speed, large-capacity data communication of smartphones, the amount of electricity consumed has also increased, and increasing the capacity of power storage devices is being considered. However, increasing the capacity of the battery is accompanied by an increase in the container size and the number of reactive substances, and the amount of gas generated when the power storage device is thermally runaway (that is, when the power storage device is heated) also increases, so that the power storage device The risk of explosion increases as the internal pressure of the battery rises. In a power storage device using a metal exterior material (for example, a metal can battery), a safety valve is attached to ensure safety when gas is generated (see Patent Document 2).

However, it is difficult to attach such a safety valve to a power storage device using a laminated film-like exterior material, and avoiding expansion of the power storage device due to gas generated inside the high temperature power storage device becomes an issue.

On the other hand, the power storage device is exposed to a high temperature (for example, about 100 ° C.) due to heating in the baking process in the manufacturing process of the power storage device, but the heat generated in the baking process and the generated gas open the exterior material for the power storage device. It is necessary to avoid it.

Under such circumstances, the present disclosure is an exterior material for a power storage device composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealing resin layer in this order. Until it reaches a high temperature (for example, about 100 ° C.), it is sealed with an exterior material for a power storage device. A main object of the present invention is to provide an exterior material for a power storage device, which can open the material and release the gas generated inside the power storage device to the outside.

The inventors of the present disclosure have made diligent studies to solve the above problems. As a result, the exterior material for a power storage device is composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealing resin layer in this order, and the exterior material for the power storage device has a temperature of 190. In the heat seal strength measurement measured by heat-sealing the heat-sealing resin layers with each other under the conditions of ° C. and a surface pressure of 1.0 MPa for 3 seconds and peeling the heat-sealing resin layers with each other, the measured temperature. By including the heat seal strength lowering temperature T ° C. within the range of 110 ° C. or higher and 120 ° C. or lower, the power storage device is sealed by the exterior material for the power storage device until the temperature of the power storage device becomes high (for example, about 100 ° C.). It has been found that when the temperature becomes high (for example, about 110 ° C. to 130 ° C.) and the internal pressure rises excessively, the power storage device can be opened and the gas generated inside the power storage device can be released to the outside.

(Heat seal strength reduction temperature T ° C)
In the heat seal strength measurement, the measurement temperature is such that the heat seal strength is 35 N / 15 mm or more, and the heat seal strength at the heat seal strength decrease temperature T ° C. + 10 ° C. is 10 N / 15 mm or less.

This disclosure has been completed by further studies based on these findings. That is, the present disclosure provides the inventions of the following aspects.
An exterior material for a power storage device composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealing resin layer in this order.
The exterior material for a power storage device is measured by heat-sealing the heat-sealing resin layers under the conditions of a temperature of 190 ° C. and a surface pressure of 1.0 MPa for 3 seconds, and peeling the heat-sealing resin layers from each other. An exterior material for a power storage device, wherein the heat seal strength reduction temperature T ° C. is included in the measurement temperature range of 110 ° C. or higher and 120 ° C. or lower in the heat seal strength measurement.
(Heat seal strength reduction temperature T ° C)
In the heat seal strength measurement, the measurement temperature is such that the heat seal strength is 35 N / 15 mm or more, and the heat seal strength at the heat seal strength decrease temperature T ° C. + 10 ° C. is 10 N / 15 mm or less.

According to the present disclosure, it is an exterior material for a power storage device composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealing resin layer in this order, and the power storage device has a high temperature (for example, 100). It is sealed by the exterior material for the power storage device until it reaches (° C), and when the power storage device becomes high temperature (for example, about 110 ° C to 130 ° C) and the internal pressure rises excessively, the exterior material for the power storage device is opened. Therefore, it is possible to provide an exterior material for a power storage device capable of discharging the gas generated inside the power storage device to the outside. 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 which shows an example of the cross-sectional structure of the exterior material for a power storage device of this disclosure. It is a schematic diagram which shows an example of the cross-sectional structure of the exterior material for a power storage device of this disclosure. It is a schematic diagram which shows an example of the cross-sectional structure of the exterior material for a power storage device of this disclosure. It is a schematic diagram for demonstrating the method of accommodating a power storage device element in a package formed by the exterior material for a power storage device of the present disclosure. It is a schematic diagram for demonstrating the measuring method of a heat seal strength. It is a schematic diagram for demonstrating the measuring method of a heat seal strength. It is a schematic diagram for demonstrating the measurement method of a softening point. It is a schematic diagram of the differential molecular weight distribution curve.

The exterior material for a power storage device of the present disclosure is an exterior material for a power storage device composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealing resin layer in this order. The exterior material for use is a heat measured by heat-sealing the heat-sealing resin layers with each other under the conditions of a temperature of 190 ° C. and a surface pressure of 1.0 MPa for 3 seconds, and peeling the heat-sealing resin layers from each other. In the seal strength measurement, the following heat seal strength lowering temperature T ° C. is included in the measurement temperature range of 110 ° C. or higher and 120 ° C. or lower. Since the exterior material for the power storage device of the present disclosure has the above configuration, the exterior material for the power storage device is sealed by the exterior material for the power storage device until the power storage device becomes high temperature (for example, about 100 ° C.), and the power storage device stays at a high temperature (for example, 110 ° C.). When the temperature rises from ° C. to about 130 ° C. and the internal pressure rises excessively, the power storage device can be opened and the gas generated inside the power storage device can be discharged to the outside.

(Heat seal strength reduction temperature T ° C)
The heat seal strength decrease temperature T ° C. is a measurement temperature at which the heat seal strength is 35 N / 15 mm or more in the heat seal strength measurement, and the heat seal strength at the heat seal strength decrease temperature T ° C. + 10 ° C. is 10 N / 15 mm. The measured temperature is as follows.

Hereinafter, the exterior material for the power storage device of the present disclosure will be described in detail. In this disclosure, the numerical range indicated by "-" means "greater than or equal to" and "less than or equal to". For example, the notation of 2 to 15 mm means 2 mm or more and 15 mm or less.

Regarding the barrier layer 3 described later in the exterior material for a power storage device, it is usually possible to discriminate between MD (Machine Direction) and TD (Transverse Direction) in the manufacturing process thereof. For example, when the barrier layer 3 is made of a metal foil such as an aluminum alloy foil or a stainless steel foil, a line called a so-called rolling mark is formed on the surface of the metal foil in the rolling direction (RD: Rolling Direction) of the metal foil. Shaped streaks are formed. Since the rolling marks extend along the rolling direction, the rolling direction of the metal foil can be grasped by observing the surface of the metal foil. Further, in the manufacturing process of the laminated body, since the MD of the laminated body and the RD of the metal foil usually match, the surface of the metal foil of the laminated body is observed and the rolling direction (RD) of the metal foil is specified. Thereby, the MD of the laminated body can be specified. Further, since the TD of the laminated body is in the direction perpendicular to the MD of the laminated body, the TD of the laminated body can also be specified.

If the MD of the exterior material for the power storage device cannot be specified due to the rolling marks of a metal foil such as an aluminum alloy foil or a stainless steel foil, it can be specified by the following method. As a method of confirming the MD of the exterior material for the electricity storage device, there is a method of observing the cross section of the heat-sealing resin layer of the exterior material for the electricity storage device with an electron microscope to confirm the sea-island structure. In this method, MD can be determined to be the direction parallel to the cross section in which the average diameter of the island shapes in the direction perpendicular to the thickness direction of the heat-sealing resin layer is the maximum. Specifically, the angle is changed by 10 degrees from the cross section of the heat-sealing resin layer in the length direction and the direction parallel to the cross section in the length direction to the direction perpendicular to the cross section in the length direction. Each cross section (10 cross sections in total) is observed with an electron micrograph to confirm the sea-island structure. Next, in each cross section, the shape of each island is observed. For the shape of each island, the diameter y is the linear distance connecting the leftmost end in the direction perpendicular to the thickness direction of the heat-sealing resin layer and the rightmost end in the vertical direction. In each cross section, the average of the top 20 diameters y is calculated in descending order of the diameter y of the island shape. The direction parallel to the cross section in which the average of the diameter y of the island shape is the largest is determined as MD.

1. 1. Laminated structure and physical properties of exterior material for power storage device The exterior material 10 for power storage device of the present disclosure includes, for example, a base material layer 1, a barrier layer 3, and a heat-sealing resin layer 4 in this order, as shown in FIG. It is composed of a laminated body. In the exterior material 10 for a power storage device, the base material layer 1 is on the outermost layer side, and the heat-sealing resin layer 4 is on the innermost layer. When assembling a power storage device using the power storage device exterior material 10 and the power storage device element, the peripheral portion is heat-sealed with the heat-sealing resin layers 4 of the power storage device exterior material 10 facing each other. The power storage device element is housed in the space formed by. In the laminate constituting the exterior material 10 for the power storage device of the present disclosure, the heat-sealing resin layer 4 side is inside the barrier layer 3 and the base material layer 1 side is more than the barrier layer 3 with the barrier layer 3 as a reference. It is the outside.

As shown in FIGS. 2 and 3, for example, the exterior material 10 for a power storage device is used, if necessary, for the purpose of enhancing the adhesiveness between the base material layer 1 and the barrier layer 3 and the like. It may have an adhesive layer 2. Further, as shown in FIG. 3, an adhesive layer 5 is provided between the barrier layer 3 and the heat-sealing resin layer 4 as needed for the purpose of enhancing the adhesiveness between the layers. You may. Further, as shown in FIG. 3, a surface coating layer 6 or the like may be provided on the outside of the base material layer 1 (the side opposite to the heat-sealing resin layer 4 side), if necessary.

The thickness of the laminate constituting the exterior material 10 for the power storage device is not particularly limited, but is preferably about 180 μm or less, about 155 μm or less, and about 120 μm or less from the viewpoint of cost reduction, energy density improvement, and the like. Further, the thickness of the laminate constituting the exterior material 10 for the power storage device is preferably about 35 μm or more, about 45 μm or more, and about from the viewpoint of maintaining the function of the exterior material for the power storage device of protecting the power storage device element. 60 μm or more can be mentioned. The preferred range of the laminated body constituting the exterior material 10 for the power storage device is, for example, about 35 to 180 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 180 μm, about 45 to 155 μm, about 45 to 120 μm. , About 60 to 180 μm, about 60 to 155 μm, about 60 to 120 μm, and particularly preferably about 60 to 155 μm.

In the power storage device exterior material 10, the base material layer 1, the adhesive layer 2 provided as necessary, the barrier layer 3, and if necessary with respect to the thickness (total thickness) of the laminate constituting the power storage device exterior material 10. The ratio of the total thickness of the adhesive layer 5, the heat-sealing resin layer 4, and the surface coating layer 6 provided as needed is preferably 90% or more, more preferably 95% or more. More preferably, it is 98% or more. As a specific example, when the exterior material 10 for a power storage device of the present disclosure includes a base material layer 1, an adhesive layer 2, a barrier layer 3, an adhesive layer 5, and a heat-sealing resin layer 4, the exterior for a power storage device The ratio of the total thickness of each of these layers to the thickness (total thickness) of the laminate constituting the material 10 is preferably 90% or more, more preferably 95% or more, and further preferably 98% or more.

In the exterior material 10 for a power storage device of the present disclosure, the heat-sealing resin layers 4 are heat-sealed under the conditions of a temperature of 190 ° C. and a surface pressure of 1.0 MPa for 3 seconds, and the heat-sealing resin layers 4 are peeled off from each other. In the heat seal strength measurement measured by the above, the following heat seal strength lowering temperature T ° C. is included in the range of the measurement temperature of 110 ° C. or higher and 120 ° C. or lower.

The heat seal strength at the heat seal strength lowering temperature T ° C. may be 35 N / 15 mm or more, but from the viewpoint of more preferably exerting the effect of the present invention, it is preferably about 45 N / 15 mm or more, more preferably about 50 N / 15 mm. That is all. From the same viewpoint, the heat seal strength is preferably about 80 N / 15 mm or less, preferably about 70 N / 15 mm or less. The preferable range of the heat seal strength is about 35 to 80 N / 15 mm, about 35 to 70 N / 15 mm, about 45 to 80 N / 15 mm, about 45 to 70 N / 15 mm, about 50 to 80 N / 15 mm, and about 50 to 70 N / 15 mm. The degree can be mentioned.

Further, the heat seal strength at the heat seal strength lowering temperature T ° C. + 10 ° C. may be 10 N / 15 mm or less, but from the viewpoint of more preferably exerting the effect of the present invention, it is preferably about 8 N / 15 mm or less, more preferably. It is about 5N / 15mm or less. From the same viewpoint, the heat seal strength is about 0.5 N / 15 mm or more. The preferable range of the heat seal strength is about 0.5 to 10 N / 15 mm, about 0.5 to 8 N / 15 mm, and about 0.5 to 5 N / 15 mm.

The method for measuring the heat seal strength and the method for measuring the measurement temperature range including the heat seal strength decrease temperature T ° C. are as follows.

(Measurement of heat seal strength and measurement of measurement temperature range including heat seal strength decrease temperature T ° C.)
In accordance with JIS K7127: 1999, at each measurement temperature (sample temperature) (for example, 25 ° C, 60 ° C, 80 ° C, 100 ° C, 110 ° C, 120 ° C, 130 ° C, 140 ° C), respectively. Measure the heat seal strength. As a test piece, 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. 5, first, the exterior material for the power storage device is cut into 60 mm (TD direction) × 200 mm (MD direction) (FIG. 5a). Next, the heat-sealing resin layers are made to face each other, and the exterior material for the power storage device is folded in half in the MD direction at the position of the crease P (middle in the MD direction) (FIG. 5b). The heat-sealing resin layers are heat-sealed between the heat-sealing resin layers under the conditions of a sealing width of 7 mm, a temperature of 190 ° C., and a surface pressure of 1.0 MPa for 3 seconds inside in the MD direction by about 10 mm from the crease P (FIG. 5c). In FIG. 5c, the shaded portion S is a heat-sealed portion. Next, a test piece is obtained by cutting in the direction of MD (cutting at the position of the alternate long and short dash line in FIG. 5d) so that the width in the direction of TD is 15 mm (FIG. 5e). Next, the test piece 13 is left at each measurement temperature for 2 minutes, and in each measurement temperature environment, a heat seal part (heat fusion part) is used with a tensile tester (for example, AG-Xplus (trade name) manufactured by Shimadzu Corporation). The heat-sealing resin layer of No. 1 is peeled off at a rate of 300 mm / min (FIG. 6). The maximum strength at the time of peeling is the heat seal strength (N / 15 mm). The distance between the chucks is 50 mm. The average value measured three times. From the heat seal strength obtained at each measurement temperature, the measurement temperature range including the heat seal strength decrease temperature T ° C specified in the above (heat seal strength decrease temperature T ° C) is confirmed. Specific examples are shown in Examples.

From the viewpoint of more preferably exerting the effects of the invention of the present disclosure, the exterior material for a power storage device of the present disclosure has a heat seal strength of preferably 50 N when the measurement temperature is 100 ° C. in the above-mentioned measurement of the heat seal strength. / 15 mm or more, more preferably 60 N / 15 mm or more, still more preferably 70 N / 15 mm or more. From the same viewpoint, the heat seal strength is preferably 100 N / 15 mm or less, more preferably 90 N / 15 mm or less. The preferred range of the heat seal strength is about 50 to 100 N / 15 mm, about 50 to 90 N / 15 mm, about 60 to 100 N / 15 mm, about 60 to 90 N / 15 mm, about 70 to 100 N / 15 mm, and about 70 to 90 N / 15 mm. Degree.

Further, from the viewpoint of more preferably exerting the effects of the invention of the present disclosure, the heat-sealing strength of the exterior material for a power storage device of the present disclosure is preferably 110 ° C. in the above-mentioned measurement of the heat-sealing strength. Is 35 N / 15 mm or more, more preferably 40 N / 15 mm or more, still more preferably 50 N / 15 mm or more. From the same viewpoint, the heat seal strength is preferably 80 N / 15 mm or less, more preferably 70 N / 15 mm or less. The preferable range of the heat seal strength is about 35 to 80 N / 15 mm, about 35 to 70 N / 15 mm, about 40 to 80 N / 15 mm, about 40 to 70 N / 15 mm, about 50 to 80 N / 15 mm, and about 50 to 70 N / 15 mm. Degree.

Further, from the viewpoint of more preferably exerting the effects of the invention of the present disclosure, the exterior material for a power storage device of the present disclosure preferably has a heat seal strength when the measurement temperature is 120 ° C. in the above-mentioned measurement of the heat seal strength. Is 2N / 15mm or more, more preferably 5N / 15mm or more. From the same viewpoint, the heat seal strength is preferably 70 N / 15 mm or less, more preferably 60 N / 15 mm or less. The preferable range of the heat seal strength is about 2 to 70 N / 15 mm, about 2 to 60 N / 15 mm, about 5 to 70 N / 15 mm, and about 5 to 60 N / 15 mm.

Further, from the viewpoint of more preferably exerting the effect of the invention of the present disclosure, the exterior material 10 for a power storage device of the present disclosure has a heat seal strength when the measurement temperature is 130 ° C. in the above-mentioned measurement of the heat seal strength. It is preferably 10 N / 15 mm or less, more preferably 5 N / 15 mm or less. From the same viewpoint, the heat seal strength is preferably 0 N / 15 mm or more, more preferably 1 N / 15 mm or more. The preferable range of the heat seal strength is about 0 to 10 N / 15 mm, about 0 to 5 N / 15 mm, about 1 to 10 N / 15 mm, and about 1 to 5 N / 15 mm.

Further, from the viewpoint of more preferably exerting the effect of the invention of the present disclosure, based on the indentation method, at a measurement temperature (sample temperature) of 100 ° C., the heat-sealing resin layer 4 side of the exterior material 10 for a power storage device of the present disclosure. The Vickers hardness measured by pushing a Vickers indenter to a depth of 1 μm from the surface of the above is preferably 10.0 MPa or more, more preferably 11.0 MPa or more, still more preferably 12.0 MPa or more. From the same viewpoint, the Martens hardness is preferably 25.0 MPa or less, more preferably 20.0 MPa or less. The preferred range of the Martens hardness is about 10.0 to 25.0 MPa, about 10.0 to 20.0 MPa, about 11.0 to 25.0 MPa, about 11.0 to 20.0 MPa, and about 12.0 to. About 25.0 MPa, about 12.0 to 20.0 MPa can be mentioned. Since the Martens hardness at 100 ° C. is within the above range, the heat-sealing resin layer is difficult to move even when gas is generated from the inside of the power storage device due to heat and the internal pressure starts to rise, which is unexpected. It is possible to prevent the package from being opened at a temperature, and it is possible to prevent the exterior material for the power storage device from being opened by, for example, the gas generated by heating in the baking process in the manufacturing process of the power storage device. The method for measuring the Martens hardness is as follows.

(Measurement of Martens hardness)
Based on the indentation method, at the measurement temperature (sample temperature) of 100 ° C., the Vickers indenter is pushed in the thickness direction from the surface of the heat-sealing resin layer side of the exterior material for the power storage device to a depth of 1 μm to measure the Martens hardness. do. The measurement conditions are as follows. Martens hardness is calculated from the load-displacement curve obtained by pushing the Vickers indenter. As the measured value, the average obtained for 10 places on the surface on the heat-sealing resin layer side is adopted. Martens hardness calculates the surface area A (mm ²⁾ of the indenter at the maximum indentation depth of the Vickers indenter is obtained dividing the maximum load F (N) (F / A ) that in the surface area A (mm ^2). As the measuring device, for example, a picodenter HM-500 manufactured by Fisher Instruments is used. For example, an exterior material for a power storage device is adhered to one side of a slide glass (76 mm × 26 mm × 1 mm) to which a double-sided adhesive tape is attached so that the heat-sealing resin layer side is opposite to the slide glass, and used as a measurement sample. Next, a heating stage is installed in an ultrafine hardness tester equipped with a Vickers indenter, the stage temperature is set to 110 ° C., and the sample is heated for 5 minutes. Next, the surface hardness of the surface of the measurement sample on the heat-sealing resin layer side is measured.
<Measurement conditions>
・ Indenter: Vickers (face-to-face angle 136 ° at the tip of a quadrangular pyramid)
-Measurement temperature (sample temperature): 100 ° C
・ Stage temperature: 110 ℃
・ Velocity: 1.000 μm / 10 seconds ・ Measurement depth: 1.0 μm
-Holding time: 5 seconds-Returning speed from pushing: 1.000 μm / 10 seconds

Further, the exterior material for a power storage device of the present disclosure is preferably opened at a temperature of 120 ° C. to 130 ° C. when subjected to the following opening test.

(Opening test)
The exterior material for the power storage device is cut into a size of 100 mm × 200 mm, and the heat-sealing resin layers are opposed to each other and folded back at the center position of the long side of the exterior material for the power storage device. Next, the short side is heat-sealed under the conditions of a temperature of 190 ° C., a surface pressure of 1.0 MPa, and a seal width of 7 mm for 3 seconds. Further, one long side is heat-sealed in the same manner, 2.0 g of water is added to the bag-shaped sample, and then the opening side (long side) is similarly degassed. Heat-seal to make a test sample with water sealed. The test sample is placed in an oven, heated from room temperature (25 ° C.) at a heating rate of 5 ° C./min until the test sample temperature reaches 130 ° C., and held at 130 ° C. for 30 minutes. During the test, when the temperature exceeds 100 ° C, the internal pressure rises due to the vaporization of water, and the internal pressure becomes 140 kPa at 110 ° C, 200 kPa at 120 ° C, and 270 kPa at 130 ° C.

2. Each layer forming the exterior material for the power storage device [base material layer 1]
In the present disclosure, the base material layer 1 is a layer provided for the purpose of exerting a function as a base material of an exterior material for a power storage device. The base material layer 1 is located on the outer layer side of the exterior material for the power storage device.

The material forming the base material layer 1 is not particularly limited as long as it has a function as a base material, that is, at least an insulating property. The base material layer 1 can be formed by using, for example, a resin, and the resin may contain an additive described later.

When the base material layer 1 is formed of a resin, the base material layer 1 may be, for example, a resin film formed of a resin or a resin film applied to the base material layer 1. The resin film may be an unstretched film or a stretched film. Examples of the stretched film include a uniaxially stretched film and a biaxially stretched film, and a biaxially stretched film is preferable. Examples of the stretching method for forming the biaxially stretched film include a sequential biaxial stretching method, an inflation method, and a simultaneous biaxial stretching method. Examples of the method for applying the resin include a roll coating method, a gravure coating method, and an extrusion coating method.

Examples of the resin forming the base material layer 1 include resins such as polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, and phenol resin, and modified products of these resins. Further, the resin forming the base material layer 1 may be a copolymer of these resins or a modified product of the copolymer. Further, it may be a mixture of these resins.

Among these, preferable examples of the resin forming the base material layer 1 include polyester and polyamide.

Specific examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyester. Further, examples of the copolymerized polyester include a copolymerized polyester containing ethylene terephthalate as a repeating unit as a main component. Specifically, copolymer polyester (hereinafter abbreviated after polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / adipate), polyethylene (terephthalate / terephthalate / (Sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate), polyethylene (terephthalate / decandicarboxylate) and the like. These polyesters may be used alone or in combination of two or more.

Specific examples of the polyamide include an aliphatic polyamide such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and a copolymer of nylon 6 and nylon 66; terephthalic acid and / or isophthalic acid. Hexamethylenediamine-isophthalic acid-terephthalic acid copolymerized polyamide such as nylon 6I, nylon 6T, nylon 6IT, nylon 6I6T (I stands for isophthalic acid, T stands for terephthalic acid), polyamide MXD6 (polymethaki Polyamide containing aromatics such as silylene adipamide); Alicyclic polyamide such as polyamide PACM6 (polybis (4-aminocyclohexyl) methaneadipamide); Further, lactam component and isocyanate component such as 4,4'-diphenylmethane-diisocyanate Examples thereof include a copolymerized polyamide, a polyesteramide copolymer or a polyether esteramide copolymer which is a copolymer of a copolymerized polyamide and polyester or polyalkylene ether glycol; and a polyamide such as these copolymers. These polyamides may be used alone or in combination of two or more.

The base material layer 1 preferably contains at least one of a polyester film, a polyamide film, and a polyolefin film, and preferably contains at least one of a stretched polyester film, a stretched polyamide film, and a stretched polyolefin film. It is more preferable to contain at least one of a stretched polyethylene terephthalate film, a stretched polybutylene terephthalate film, a stretched nylon film, and a stretched polypropylene film, and a biaxially stretched polyethylene terephthalate film, a biaxially stretched polybutylene terephthalate film, and a biaxially stretched nylon film. , It is more preferable to contain at least one of the biaxially stretched polypropylene films.

The base material layer 1 may be a single layer or may be composed of two or more layers. When the base material layer 1 is composed of two or more layers, the base material layer 1 may be a laminated body in which a resin film is laminated with an adhesive or the like, or the resin is co-extruded to form two or more layers. It may be a laminated body of the resin film. Further, the laminated body of the resin film obtained by co-extruding the resin into two or more layers may be used as the base material layer 1 without being stretched, or may be uniaxially stretched or biaxially stretched as the base material layer 1.

Specific examples of the laminate of two or more layers of resin film in the base material layer 1 include a laminate of a polyester film and a nylon film, a laminate of two or more layers of nylon film, and a laminate of two or more layers of polyester film. And the like, preferably, a laminate of a stretched nylon film and a stretched polyester film, a laminate of two or more layers of stretched nylon film, and a laminate of two or more layers of stretched polyester film are preferable. For example, when the base material layer 1 is a laminate of two layers of resin film, a laminate of polyester resin film and polyester resin film, a laminate of polyamide resin film and polyamide resin film, or a laminate of polyester resin film and polyamide resin film. A laminate is preferable, and a laminate of a polyethylene terephthalate film and a polyethylene terephthalate film, a laminate of a nylon film and a nylon film, or a laminate of a polyethylene terephthalate film and a nylon film is more preferable. Further, since the polyester resin is difficult to discolor when the electrolytic solution adheres to the surface, for example, when the base material layer 1 is a laminate of two or more resin films, the polyester resin film is the base material layer 1. It is preferably located in the outermost layer.

When the base material layer 1 is a laminated body of two or more layers of resin films, the two or more layers of resin films may be laminated via an adhesive. Preferred adhesives include those similar to the adhesives exemplified in the adhesive layer 2 described later. The method of laminating two or more layers of resin films is not particularly limited, and known methods can be adopted. Examples thereof include a dry laminating method, a sandwich laminating method, an extrusion laminating method, and a thermal laminating method, and a dry laminating method is preferable. The laminating method can be mentioned. When laminating by the dry laminating method, it is preferable to use a polyurethane adhesive as the adhesive. At this time, the thickness of the adhesive is, for example, about 2 to 5 μm. Further, an anchor coat layer may be formed on the resin film and laminated. Examples of the anchor coat layer include the same adhesives as those exemplified in the adhesive layer 2 described later. At this time, the thickness of the anchor coat layer is, for example, about 0.01 to 1.0 μm.

Further, even if additives such as a lubricant, a flame retardant, an antiblocking agent, an antioxidant, a light stabilizer, a tackifier, and an antistatic agent are present on at least one of the surface and the inside of the base material layer 1. good. Only one type of additive may be used, or two or more types may be mixed and used.

In the present disclosure, from the viewpoint of enhancing the moldability of the exterior material for the power storage device, it is preferable that the lubricant is present on the surface of the base material layer 1. The lubricant is not particularly limited, but an amide-based lubricant is preferable. Specific examples of the amide-based lubricant include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of the saturated fatty acid amide include lauric acid amide, palmitic acid amide, stearic acid amide, bechenic acid amide, hydroxystearic acid amide and the like. Specific examples of the unsaturated fatty acid amide include oleic acid amide and erucic acid amide. Specific examples of the substituted amide include N-oleyl palmitate amide, N-stearyl stearyl amide, N-stearyl oleate amide, N-oleyl stealic acid amide, N-stearyl erucate amide and the like. Further, specific examples of methylolamide include methylolstearic amide. Specific examples of the saturated fatty acid bisamide include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbechenic acid amide, and hexamethylene bisstearic. Acid amides, hexamethylene bisbechenic acid amides, hexamethylene hydroxystearic acid amides, N, N'-distearyl adipate amides, N, N'-distearyl sebacic acid amides and the like can be mentioned. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucate amide, hexamethylene bisoleic acid amide, N, N'-diorail adipate amide, and N, N'-diorail sebacic acid amide. And so on. Specific examples of the fatty acid ester amide include stearoamide ethyl stearate and the like. Specific examples of the aromatic bisamide include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, and N, N'-distearyl isophthalic acid amide. One type of lubricant may be used alone, or two or more types may be used in combination.

When the lubricant is present on the surface of the base material layer 1, the abundance thereof is not particularly limited, but is preferably about 3 mg / m ² or more, more preferably about 4 to 15 mg / m ² , and further preferably 5 to 14 mg. / M ² is mentioned.

The lubricant existing on the surface of the base material layer 1 may be one in which the lubricant contained in the resin constituting the base material layer 1 is exuded, or one in which the lubricant is applied to the surface of the base material layer 1. You may.

The thickness of the base material layer 1 is not particularly limited as long as it functions as a base material, but for example, it may be about 3 to 50 μm, preferably about 10 to 35 μm. When the base material layer 1 is a laminate of two or more resin films, the thickness of the resin films constituting each layer is preferably about 2 to 25 μm, respectively.

[Adhesive layer 2]
In the exterior material for a power storage device of the present disclosure, the adhesive layer 2 is a layer provided between the base material layer 1 and the barrier layer 3 as necessary for the purpose of enhancing the adhesiveness between the base material layer 1 and the barrier layer 3.

The adhesive layer 2 is formed by an adhesive capable of adhering the base material layer 1 and the barrier layer 3. The adhesive used for forming the adhesive layer 2 is not limited, but may be any of a chemical reaction type, a solvent volatile type, a heat melting type, a hot pressure type and the like. Further, it may be a two-component curable adhesive (two-component adhesive), a one-component curable adhesive (one-component adhesive), or a resin that does not involve a curing reaction. Further, the adhesive layer 2 may be a single layer or a multilayer.

Specific examples of the adhesive component 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; Phenolic resin; Polyethylene such as nylon 6, nylon 66, nylon 12, copolymerized polyamide; Polyethylene resin such as polyolefin, cyclic polyolefin, acid-modified polyolefin, acid-modified cyclic polyolefin; Polyvinyl acetate; Cellulose; (Meta) acrylic resin; Polyethylene; polycarbonate; amino resin such as urea resin and melamine resin; rubber such as chloroprene rubber, nitrile rubber and styrene-butadiene rubber; silicone resin and the like. These adhesive components may be used alone or in combination of two or more. Among these adhesive components, a polyurethane adhesive is preferable. In addition, the resins used as these adhesive components can be used in combination with an appropriate curing agent to increase the adhesive strength. An appropriate curing agent is selected from polyisocyanate, polyfunctional epoxy resin, oxazoline group-containing polymer, polyamine resin, acid anhydride and the like, depending on the functional group of the adhesive component.

Examples of the polyurethane adhesive include a polyurethane adhesive containing a first agent containing a polyol compound and a second agent containing an isocyanate compound. Preferably, a two-component curable polyurethane adhesive using a polyol such as a polyester polyol, a polyether polyol, and an acrylic polyol as a first agent and an aromatic or aliphatic polyisocyanate as a second agent can be mentioned. Examples of the polyurethane adhesive include a polyurethane adhesive in which a polyol compound and an isocyanate compound are reacted in advance, and a polyurethane adhesive containing the isocyanate compound. Further, examples of the polyurethane adhesive include a polyurethane adhesive in which a polyol compound and an isocyanate compound are reacted in advance, and a polyurethane adhesive containing the polyol compound. Examples of the polyurethane adhesive include a polyurethane adhesive obtained by reacting a polyurethane compound in which a polyol compound and an isocyanate compound are previously reacted with water such as in the air to cure the polyurethane compound. 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 aromatic aliphatic isocyanate compounds. Examples of the isocyanate-based compound include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), and diphenylmethane diisocyanate. (MDI), naphthalenediocyanate (NDI) and the like. Moreover, a polyfunctional isocyanate modified product from one kind or two or more kinds of these diisocyanates and the like can be mentioned. Further, a multimer (for example, a trimer) can be used as the polyisocyanate compound. Examples of such a multimer include an adduct body, a biuret body, a nurate body and the like. Since the adhesive layer 2 is formed of the polyurethane adhesive, excellent electrolytic solution resistance is imparted to the exterior material for the power storage device, and even if the electrolytic solution adheres to the side surface, the base material layer 1 is suppressed from peeling off. ..

Further, the adhesive layer 2 may contain a colorant, a thermoplastic elastomer, a tackifier, a filler, etc., as long as the addition of other components is permitted as long as the adhesiveness is not impaired. Since the adhesive layer 2 contains a colorant, the exterior material for the power storage device can be colored. As the colorant, known ones such as pigments and dyes can be used. Further, only one type of colorant may be used, or two or more types may be mixed and used.

The type of pigment is not particularly limited as long as it does not impair the adhesiveness of the adhesive layer 2. Examples of organic pigments include azo-based, phthalocyanine-based, quinacridone-based, anthracinone-based, dioxazine-based, indigothioindigo-based, perinone-perylene-based, isoindrenine-based, and benzimidazolone-based pigments, which are inorganic. Examples of the pigment include carbon black-based, titanium oxide-based, cadmium-based, lead-based, chromium oxide-based, and iron-based pigments, and other examples include fine powder of mica (mica) and fish scale foil.

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

The average particle size of the pigment is not particularly limited, and examples thereof include about 0.05 to 5 μm, preferably about 0.08 to 2 μm. The average particle size of the pigment is the median diameter measured by a laser diffraction / scattering type particle size distribution measuring device.

The content of the pigment in the adhesive layer 2 is not particularly limited as long as the exterior material for the power storage device is colored, and examples thereof include about 5 to 60% by mass, preferably 10 to 40% by mass.

The thickness of the adhesive layer 2 is not particularly limited as long as the base material layer 1 and the barrier layer 3 can be adhered to each other, but is, for example, about 1 μm or more and about 2 μm or more. The thickness of the adhesive layer 2 is, for example, about 10 μm or less and about 5 μm or less. The preferable range of the thickness of the adhesive layer 2 is about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, and about 2 to 5 μm.

[Colored layer]
The colored layer is a layer provided between the base material layer 1 and the barrier layer 3 as needed (not shown). When the adhesive layer 2 is provided, a colored layer may be provided between the base material layer 1 and the adhesive layer 2 and between the adhesive layer 2 and the barrier layer 3. Further, a colored layer may be provided on the outside of the base material layer 1. By providing the colored layer, the exterior material for the power storage device can be colored.

The colored layer can be formed, for example, by applying an ink containing a colorant to the surface of the base material layer 1 or the surface of the barrier layer 3. As the colorant, known ones such as pigments and dyes can be used. Further, only one type of colorant may be used, or two or more types may be mixed and used.

Specific examples of the colorant contained in the colored layer include the same as those exemplified in the column of [Adhesive layer 2].

[Barrier layer 3]
In the exterior material for a power storage device, the barrier layer 3 is at least a layer that suppresses the infiltration of water.

Examples of the barrier layer 3 include a metal foil having a barrier property, a thin-film deposition film, a resin layer, and the like. Examples of the vapor deposition film include a metal vapor deposition film, an inorganic oxide vapor deposition film, a carbon-containing inorganic oxide vapor deposition film, and the like, and examples of the resin layer include polymers and tetras mainly composed of polyvinylidene chloride and chlorotrifluoroethylene (CTFE). Examples thereof include polymers containing fluoroethylene (TFE) as a main component, polymers having a fluoroalkyl group, fluorine-containing resins such as polymers containing a fluoroalkyl unit as a main component, and ethylene vinyl alcohol copolymers. Further, examples of the barrier layer 3 include a resin film provided with at least one of these vapor-deposited films and a resin layer. A plurality of barrier layers 3 may be provided. The barrier layer 3 preferably includes a layer made of a metal material. Specific examples of the metal material constituting the barrier layer 3 include an aluminum alloy, stainless steel, titanium steel, and a steel plate. When used as a metal foil, the metal material includes at least one of an aluminum alloy foil and a stainless steel foil. Is preferable.

From the viewpoint of improving the moldability of the exterior material for the power storage device, the aluminum alloy foil is more preferably a soft aluminum alloy foil composed of, for example, an annealed aluminum alloy, and from the viewpoint of further improving the moldability. Therefore, it is preferable that the aluminum alloy foil contains 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, an exterior material for a power storage device having more excellent moldability can be obtained. When the iron content is 9.0% by mass or less, a more flexible exterior material for a power storage device can be obtained. Examples of the soft aluminum alloy foil include an aluminum alloy having a composition specified by JIS H4160: 1994 A8021HO, JIS H4160: 1994 A8079HO, JIS H4000: 2014 A8021PO, or JIS H4000: 2014 A8077P-O. Foil is mentioned. Further, if necessary, silicon, magnesium, copper, manganese and the like may be added. Further, softening can be performed by annealing or the like.

Examples of stainless steel foils include austenite-based, ferrite-based, austenite-ferritic-based, martensitic-based, and precipitation-hardened stainless steel foils. Further, from the viewpoint of providing an exterior material for a power storage device having excellent moldability, 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, and SUS316L, and among these, SUS304 is particularly preferable.

In the case of a metal foil, the thickness of the barrier layer 3 may at least exhibit a function as a barrier layer that suppresses the infiltration of water, and is, for example, about 9 to 200 μm. The thickness of the barrier layer 3 is preferably about 85 μm or less, more preferably about 50 μm or less, still more preferably about 40 μm or less, and particularly preferably about 35 μm or less. The thickness of the barrier layer 3 is preferably about 10 μm or more, more preferably about 20 μm or more, and more preferably about 25 μm or more. The preferred range of the thickness of the barrier layer 3 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. Examples thereof 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 3 is made of an aluminum alloy foil, the above range is particularly preferable. Further, in particular, when the barrier layer 3 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, still more preferably about 30 μm. Below, it is particularly preferably about 25 μm or less. The thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. The preferred 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. Examples thereof include about 40 μm, about 15 to 30 μm, and about 15 to 25 μm.

When the barrier layer 3 is a metal foil, it is preferable that a corrosion-resistant film is provided on at least the surface opposite to the base material layer in order to prevent dissolution and corrosion. The barrier layer 3 may be provided with a corrosion resistant film on both sides. Here, the corrosion-resistant film is, for example, a hot water transformation treatment such as boehmite treatment, a chemical conversion treatment, an anodic oxidation treatment, a plating treatment such as nickel or chromium, and a corrosion prevention treatment for applying a coating agent on the surface of the barrier layer. Refers to a thin film that makes the barrier layer provided with corrosion resistance (for example, acid resistance, alkali resistance, etc.). Specifically, the corrosion-resistant film means a film for improving the acid resistance of the barrier layer (acid-resistant film), a film for improving the alkali resistance of the barrier layer (alkali-resistant film), and the like. As the treatment for forming the corrosion-resistant film, one type may be performed, or two or more types may be combined. Moreover, not only one layer but also multiple layers can be used. Further, among these treatments, the hydrothermal modification treatment and the anodic oxidation treatment are treatments in which the surface of the metal foil is dissolved by the treatment agent to form a metal compound having excellent corrosion resistance. In addition, these processes may be included in the definition of chemical conversion process. When the barrier layer 3 has a corrosion-resistant film, the barrier layer 3 includes the corrosion-resistant film.

The corrosion-resistant film is formed by preventing delamination between the barrier layer (for example, aluminum alloy foil) and the base material layer during molding of the exterior material for a power storage device, and by hydrogen fluoride generated by the reaction between the electrolyte and water. , Melting and corrosion of the surface of the barrier layer, especially when the barrier layer is an aluminum alloy foil, it prevents the aluminum oxide existing on the surface of the barrier layer from melting and corroding, and the adhesiveness (wetness) of the surface of the barrier layer. The effect of preventing the corrosion between the base material layer and the barrier layer at the time of heat sealing and the prevention of the corrosion between the base material layer and the barrier layer at the time of molding is shown.

Various corrosion-resistant films formed by chemical conversion treatment are known, and mainly, at least one of phosphate, chromate, fluoride, triazinethiol compound, and rare earth oxide. Examples thereof include a corrosion-resistant film containing. Examples of the chemical conversion treatment using phosphate and chromate include chromic acid chromate treatment, chromic acid chromate treatment, phosphoric acid-chromate treatment, and chromate treatment, and chromium used in these treatments. Examples of the compound include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium bicarbonate, acetylacetate chromate, chromium chloride, chromium sulfate and the like. In addition, examples of the phosphorus compound used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, polyphosphoric acid and the like. Further, examples of the chromate treatment include etching chromate treatment, electrolytic chromate treatment, and coating type chromate treatment, and coating type chromate treatment is preferable. In this coating type chromate treatment, at least the inner layer side surface of the barrier layer (for example, aluminum alloy foil) is first known as an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, an acid activation method and the like. Degreasing is performed by the treatment method, and then metal phosphates such as Cr phosphate (chromium) salt, Ti (titanium) phosphate, Zr (zyroxide) salt, and Zn (zinc) phosphate are applied to the degreased surface. A treatment liquid containing a salt and a mixture of these non-metal salts as a main component, or a treatment liquid containing a mixture of a phosphate non-metal salt and these non-metal salts as a main component, or a synthetic resin and the like. This is a treatment in which a treatment liquid composed of a mixture is coated by a well-known coating method such as a roll coating method, a gravure printing method, or a dipping method, and dried. As the treatment liquid, for example, various solvents such as water, alcohol-based solvent, hydrocarbon-based solvent, ketone-based solvent, ester-based solvent, and ether-based solvent can be used, and water is preferable. Examples of the resin component used at this time include polymers such as phenol-based resins and acrylic-based resins, and aminoated phenol polymers having repeating units represented by the following general formulas (1) to (4) can be used. Examples thereof include the chromate treatment used. In the amination 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. May be good. The acrylic resin shall be a polyacrylic acid, an acrylic acid methacrylate copolymer, an acrylic acid maleic acid copolymer, an acrylic acid styrene copolymer, or a derivative of these sodium salts, ammonium salts, amine salts, etc. Is preferable. In particular, derivatives of polyacrylic acid such as ammonium salt, sodium salt, and amine salt of polyacrylic acid are preferable. In the present disclosure, polyacrylic acid means a polymer of acrylic acid. Further, the acrylic resin is preferably a copolymer of an acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride, and an ammonium salt or a sodium salt of a copolymer of an acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride. Alternatively, it is preferably an amine salt. Only one type of acrylic resin may be used, or two or more types may be mixed and 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 represent a hydroxy group, an alkyl group, or a hydroxyalkyl group, respectively, which are the same or different. In the general formulas (1) to (4) ^{, examples of the alkyl group represented by X, R 1} and R ² include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group and an isobutyl group. Examples thereof include a linear or branched alkyl group having 1 to 4 carbon atoms such as a tert-butyl group. Examples of the hydroxyalkyl groups represented by X, R ¹ and R ² include hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group and 3-. A linear or branched chain having 1 to 4 carbon atoms in which one hydroxy group such as a hydroxypropyl group, a 1-hydroxybutyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, or a 4-hydroxybutyl group is substituted. Alkyl groups can be mentioned. In the general formulas (1) to (4), the ^{alkyl group and the hydroxyalkyl group represented by X, R 1} and R ² may be the same or different, respectively. In the 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 amination phenol polymer having the repeating unit represented by the general formulas (1) to (4) is, for example, preferably about 5 to 1,000,000, and preferably about 1,000 to 20,000. More preferred. The amination phenol polymer is produced, for example, by polycondensing a phenol compound or a naphthol compound with formaldehyde to produce a polymer composed of repeating units represented by the above general formula (1) or general formula (3), and then forming a formaldehyde. It is produced by introducing a functional group (-CH ₂ NR ¹ R ² ) into the polymer obtained above using an amine (R ¹ R ^{2 NH).} The amination phenol polymer is used alone or in combination of two or more.

As another example of the corrosion resistant film, it is formed by a coating type corrosion prevention treatment in which a coating agent containing at least one selected from the group consisting of rare earth element oxide sol, anionic polymer, and cationic polymer is applied. The thin film to be corroded is mentioned. The coating agent may further contain phosphoric acid or phosphate, a cross-linking agent for cross-linking the polymer. In the rare earth element oxide sol, fine particles of the rare earth element oxide (for example, particles having an average particle size of 100 nm or less) are dispersed in a liquid dispersion medium. Examples of the rare earth element oxide include cerium oxide, yttrium oxide, neodium oxide, lanthanum oxide and the like, and cerium oxide is preferable from the viewpoint of further improving adhesion. The rare earth element oxide contained in the corrosion-resistant film may be used alone or in combination of two or more. As the liquid dispersion medium of the rare earth element oxide sol, for example, various solvents such as water, alcohol-based solvent, hydrocarbon-based solvent, ketone-based solvent, ester-based solvent, and ether-based solvent can be used, and water is preferable. Examples of the cationic polymer include polyethyleneimine, an ionic polymer complex composed of polyethyleneimine and a polymer having a carboxylic acid, a primary amine graft acrylic resin obtained by graft-polymerizing a primary amine on an acrylic main skeleton, polyallylamine or a derivative thereof. , Amination phenol and the like are preferable. The anionic polymer is preferably a 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 cross-linking agent is at least one selected from the group consisting of a compound having a functional group of any of an isocyanate group, a glycidyl group, a carboxyl group and an oxazoline group and a silane coupling agent. Further, it is preferable that the phosphoric acid or phosphate is condensed phosphoric acid or condensed phosphate.

As an example of the corrosion-resistant film, a film in which fine particles of metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide and barium sulfate are dispersed in phosphoric acid is applied to the surface of the barrier layer, and 150 Examples thereof include those formed by performing a baking treatment at a temperature of ° C. or higher.

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 the anionic polymer include those described above.

The composition of the corrosion-resistant film can be analyzed by using, for example, a time-of-flight secondary ion mass spectrometry method.

The amount of the corrosion-resistant film formed on the surface of the barrier layer 3 in the chemical conversion treatment is not particularly limited, but for example, in the case of performing a coating type chromate treatment, a chromic acid compound per ^{1 m 2 of the surface of the barrier layer 3} Is, for example, about 0.5 to 50 mg, preferably about 1.0 to 40 mg in terms of chromium, and the phosphorus compound is, for example, about 0.5 to 50 mg, preferably about 1.0 to 40 mg in terms of phosphorus, and an amination phenol polymer. Is preferably contained in a proportion of, 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 is preferably about 1 nm to 20 μm, more preferably 1 nm to 100 nm, from the viewpoint of the cohesive force of the film and the adhesion to the barrier layer and the heat-sealing resin layer. The degree, more preferably about 1 nm to 50 nm. The thickness of the corrosion-resistant film can be measured by observation with a transmission electron microscope or a combination of observation with a transmission electron microscope and energy dispersion type X-ray spectroscopy or electron beam energy loss spectroscopy. The time-of-flight secondary ion mass spectrometry analysis of the composition of the corrosion resistant coating using, for example, secondary ion consisting Ce and P and O _{_{^{(e.g., Ce 2 PO 4 +, CePO}}} 4 - at least 1, such as species) or, for example, secondary ion of Cr and P and O (e.g., CrPO ₂ ^+, CrPO ₄ ^- peak derived from at least one), such as is detected.

In the chemical conversion treatment, a solution containing a compound used for forming a corrosion-resistant film is applied to the surface of the barrier layer by a bar coating method, a roll coating method, a gravure coating method, a dipping method, or the like, and then the temperature of the barrier layer is applied. It is carried out by heating so that the temperature is about 70 to 200 ° C. Further, before the barrier layer is subjected to the chemical conversion treatment, the barrier layer may be subjected to a degreasing treatment by an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method or the like in advance. By performing the degreasing treatment in this way, it becomes possible to more efficiently perform the chemical conversion treatment on the surface of the barrier layer. Further, by using an acid degreasing agent in which a fluorine-containing compound is dissolved in an inorganic acid for the degreasing treatment, it is possible to form not only the degreasing effect of the metal foil but also the immobile metal fluoride. In such cases, only degreasing treatment may be performed.

[Heat-sealing resin layer 4]
In the exterior material for a power storage device of the present disclosure, the heat-sealing resin layer 4 corresponds to the innermost layer, and has a function of heat-sealing the heat-sealing resin layers with each other when assembling the power storage device to seal the power storage device element. It is a layer (sealant layer) that exerts.

From the viewpoint of more preferably exerting the effects of the invention of the present disclosure, it is preferable that the heat-sealing resin layer 4 has a melting peak temperature of 130 ° C. or lower observed in the exterior material for the power storage device of the present disclosure. From the same viewpoint, the melting peak temperature is preferably about 100 ° C. or higher, more preferably about 110 ° C. or higher, still more preferably about 120 ° C. or higher, and preferably about 150 ° C. or lower, more preferably 145 ° C. or higher. Below, it is more preferably 138 ° C. or lower. The preferred range of the melting peak temperature is about 100 to 150 ° C, about 100 to 145 ° C, about 100 to 138 ° C, about 100 to 130 ° C, about 110 to 150 ° C, about 110 to 145 ° C, and about 110 to 138 ° C. About 110 to 130 ° C, about 120 to 150 ° C, about 120 to 145 ° C, about 120 to 138 ° C, and about 120 to 130 ° C. The number of melting peak temperatures may be one or plural. Further, for example, a melting peak temperature of 130 ° C. or lower may be observed in the heat-sealing resin layer 4, and a melting peak temperature of more than 130 ° C. may be further observed. From the viewpoint of more preferably exerting the effects of the invention of the present disclosure, it is preferable that the melting peak temperatures observed in the heat-sealing resin layer 4 are all 145 ° C. or lower. The method for measuring the melting peak temperature is as follows.

(Measurement of melting peak temperature)
A heat-sealing resin layer is obtained from the exterior material for a power storage device and a measurement sample is obtained. For the measurement sample, the melting peak temperature is measured in accordance with the provisions of JIS K7121: 2012 (Plastic transition temperature measurement method (Appendix 1 of JIS K7121: 1987)). The measurement is performed using a differential scanning calorimeter (DSC, for example, a differential scanning calorimeter Q200 manufactured by TA Instruments).

Further, from the viewpoint of more preferably exerting the effect of the invention of the present disclosure, the heat-sealing resin layer has a molecular weight (concentration fraction) which is a peak value of a differential molecular weight distribution curve measured by high temperature gel permeation chromatography. The molecular weight at which the value differentiated by the logarithmic value of the molecular weight has a peak value) is preferably about 150,000 or more, more preferably about 16,000,000 or more, still more preferably 165,000 or more, still more preferably 17. It is over 0,000. The molecular weight is, for example, about 250,000 or less, about 220,000 or less, about 200,000 or less, and the like. The preferable range of the molecular weight is about 15 to 250,000, about 15 to 220,000, about 15 to 20 million, about 16.0 to 250,000, and 16.0. ~ 220,000, 16.0 to 200,000, 16.5 to 250,000, 16.5 to 220,000, 16.5 to 200,000, 17.0 It is about 250,000, about 17.0 to 220,000, and about 17.0 to 200,000. When the molecular weight is about 150,000 or more, the power storage device is more preferably sealed by the exterior material for the power storage device, particularly until the power storage device reaches a high temperature (for example, about 100 ° C.). As characteristics regarding the molecular weight of the resin, a number average molecular weight (Mn), a weight average molecular weight (Mw), Mw / Mn, and the like are often used. However, as a result of examination by the inventors of the present disclosure, no clear correlation has been found between the form in which the power storage device is preferably sealed by the exterior material for the power storage device and the form in which the power storage device is not. On the other hand, as disclosed in the present disclosure, a clear correlation was found between the peak value of the differential molecular weight distribution curve and the sealing property.

(Measurement of molecular weight that is the peak value of the differential molecular weight distribution curve)
A heat-sealing resin layer is obtained from the exterior material for a power storage device and used as a measurement sample. For each measurement sample, high temperature gel permeation chromatography (for example, SSC-7120 HT-GPC System manufactured by High Temperature GPC Senshu Kagaku Co., Ltd.) was used, and the concentration of each molecular weight was about the horizontal axis under the following measurement conditions. The fractions are sequentially integrated to obtain an integrated molecular weight distribution curve. The differential molecular weight distribution curve is obtained by obtaining the differential value of the curve at each molecular weight, and the molecular weight that becomes the peak value of the vertical axis (dw / d (Log (M))) is obtained. As shown in the schematic diagram of FIG. 8, the differential molecular weight distribution curve is a graph of values obtained by differentiating the molecular weight on the horizontal axis and the concentration fraction on the vertical axis as logarithmic values of the molecular weight. The molecular weight at the position where the value obtained by differentiating the concentration fraction by the logarithmic value of the molecular weight is the highest is the molecular weight at which the peak value of the differential molecular weight distribution curve (see the position P in FIG. 8) is obtained.

<Measurement conditions>
(Preprocessing)
The measurement sample is dissolved in a solvent (o-dichlorobenzene at 145 ° C.).
The resulting solution is allowed to stand for 1 hour and then stirred for an additional hour.
Next, the solution is pressure-filtered with membrane filters having filter pore diameters of 1.0 μm and 0.5 μm.
(measurement)
By the pretreatment, a sample in which the measurement sample is dissolved in a solvent (o-dichlorobenzene) is prepared, and a differential molecular weight distribution is used using high-temperature gel permeation chromatography (SSC-7120 HT-GPC System manufactured by High-temperature GPC Senshu Kagaku Co., Ltd.). Get the curve. The sample injection volume is 300 μL, the guard column is HT-G, the column is two HT-806M, the column temperature is 145 ° C, and the mobile phase is o-dichlorobenzene (0.025% by mass BHT (butylhydroxytoluene)). The content), the flow velocity is 1.0 mL / min, the detector is a differential refractometer, the molecular weight calibration is converted to polystyrene, and the target molecular weight range is 1,000-20,000,000.

Further, from the viewpoint of more preferably exerting the effects of the invention of the present disclosure, the difference between the melting peak temperature of the heat-sealing resin layer 4 and the softening point in the exterior material for the power storage device of the present disclosure is preferably about about. It is 30 ° C. or lower, more preferably about 20 ° C. or lower, still more preferably about 10 ° C. or lower, still more preferably about 5 ° C. or lower. Preferred ranges of the difference include about 0 to 30 ° C., about 0 to 20 ° C., about 0 to 10 ° C., and about 0 to 5 ° C. In general, a resin that exceeds the glass transition point tends to soften as the temperature rises. When the temperature of the resin exceeds the melting point, the physical properties of the resin change rapidly, and the sealing strength at the melting point becomes a very small value. However, even in the process of softening the resin, the heat-sealing resin layer Seal strength tends to decrease gradually. If the softening of the resin proceeds at a temperature significantly lower than the melting point, the exterior material for the power storage device may be opened at a temperature lower than the desired temperature. Therefore, it is desirable that the difference between the melting peak temperature and the softening point of the heat-sealing resin layer 4 satisfies the above, and it is desirable that the difference is as small as possible. The method for measuring the melting peak temperature and the softening point of the heat-sealing resin layer 4 is as follows.

(Measurement of softening point)
To measure the softening point of the exterior material for a power storage device, for example, as shown in the conceptual diagram of FIG. 7, first, the probe 11 is installed on the surface of the heat-sealing resin layer 4 in the cross section of the exterior material for the power storage device (FIG. 7). Measurement start A). The cross section at this time is a portion where the cross section of the heat-sealing resin layer 4 obtained by cutting in the thickness direction of the exterior material for the power storage device is exposed. FIG. 7 shows the probe installation position 4a. Cutting can be performed using a commercially available rotary microtome or the like. When measuring the displacement of the exterior material for a power storage device used in a battery in which an electrolyte or the like is enclosed, the portion where the heat-sealing resin layer of the exterior material for the power storage device is not fused The measurement is performed by cutting in the thickness direction in the same manner as described above. As an atomic force microscope to which a cantilever with a heating mechanism can be attached, for example, an afm plus system manufactured by ANASYS INSTRUMENTS is used, and as a probe, a cantilever THERMALever AN2-200 (spring constant 0.5 to 3 N / m) manufactured by ANASYS INSTRUMENTS is used. ) Can be used. The tip radius of the probe 11 is 30 nm or less, the set value of the deflection of the probe 11 is -4 V, and the heating rate is 5 ° C./min. Next, when the probe is heated in this state, the surface of the heat-sealing resin layer 4 expands due to the heat from the probe, the probe 11 is pushed up, and the position of the probe 11 is the initial value. (Position when the probe temperature is 40 ° C.). When the heating temperature further rises, the heat-sealing resin layer 4 softens, the probe 11 pierces the heat-sealing resin layer 4, and the position of the probe 11 is lowered, as shown in FIG. 7C. The temperature at which the position was lowered (the point of change that began to fall from the rise) was defined as the softening point of the exterior material for the power storage device. The exterior material for the power storage device to be measured is at room temperature (25 ° C.), and a probe heated to 40 ° C. is installed on the surface of the heat-sealing resin layer 4 to start the measurement.

The resin constituting the heat-fusing resin layer 4 is not particularly limited as long as it can be heat-fused, but a resin containing a polyolefin skeleton such as polyolefin or acid-modified polyolefin is preferable. The fact that the resin constituting the heat-sealing resin layer 4 contains a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography-mass spectrometry, or the like. Further, when the resin constituting the heat-sealing resin layer 4 is analyzed by infrared spectroscopy, it is preferable that a peak derived from maleic anhydride is detected. For example, when measuring the infrared spectroscopy at a maleic anhydride-modified polyolefin, a peak derived from maleic acid is detected in the vicinity of the wave number of 1760 cm ^-1 and near the wave number 1780 cm ^-1. When the heat-sealing resin layer 4 is a layer composed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected when measured by infrared spectroscopy. However, if the degree of acid denaturation is low, the peak may become small and may not be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

Specific examples of the polyolefin include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; homopolypropylene and block copolymers of polypropylene (for example, with propylene). Polyolefins such as ethylene block copolymers) and polypropylene random copolymers (eg, propylene and ethylene random copolymers); propylene-α-olefin copolymers; ethylene-butene-propylene tarpolymers and the like. Among these, polypropylene is preferable. When it is a copolymer, the polyolefin resin may be a block copolymer or a random copolymer. One type of these polyolefin resins may be used alone, or two or more types may be used in combination.

Further, the polyolefin may be a cyclic polyolefin. The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefin which is a constituent monomer of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. Be done. Examples of the cyclic monomer which is a constituent monomer of the cyclic polyolefin include cyclic alkenes such as norbornene; cyclic diene such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these, cyclic alkene is preferable, and norbornene is more preferable.

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 above-mentioned polyolefin, a copolymer obtained by copolymerizing the above-mentioned polyolefin with a polar molecule such as acrylic acid or methacrylic acid, or a polymer such as a crosslinked polyolefin can also be used. 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 anhydrides thereof.

The acid-modified polyolefin may be an acid-modified cyclic polyolefin. The acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin in place of the acid component, or by block-polymerizing or graft-polymerizing the acid component with the cyclic polyolefin. be. The same applies to the cyclic polyolefin that is acid-modified. The acid component used for acid denaturation is the same as the acid component used for denaturation of the polyolefin.

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.

The heat-sealing resin layer 4 may be formed of one type of resin alone, or may be formed of a blended polymer in which two or more types of resins are combined. Further, the heat-sealing resin layer 4 may be formed of only one layer, but may be formed of two or more layers with the same or different resins.

Further, the heat-sealing resin layer 4 may contain a lubricant or the like, if necessary. When the heat-sealing resin layer 4 contains a lubricant, the moldability of the exterior material for a power storage device can be improved. The lubricant is not particularly limited, and a known lubricant can be used. The lubricant may be used alone or in combination of two or more.

The lubricant is not particularly limited, but an amide-based lubricant is preferable. Specific examples of the lubricant include those exemplified in the base material layer 1. One type of lubricant may be used alone, or two or more types may be used in combination.

When the lubricant is present on the surface of the heat-sealing resin layer 4, the amount of the lubricant is not particularly limited, but is preferably about ^{10 to 50 mg / m 2 from the viewpoint of improving the moldability of the exterior material for the power storage device.} , More preferably about 15 to 40 mg / m ^2.

The lubricant existing on the surface of the heat-sealing resin layer 4 may be one in which the lubricant contained in the resin constituting the heat-sealing resin layer 4 is exuded, or the lubricant contained in the heat-sealing resin layer 4 may be exuded. The surface may be coated with a lubricant.

The thickness of the heat-sealing resin layer 4 is not particularly limited as long as the heat-sealing resin layers have a function of heat-sealing to seal the power storage device element, but is preferably about 100 μm or less, preferably about 100 μm or less. It is about 85 μm or less, more preferably about 15 to 85 μm. For example, when the thickness of the adhesive layer 5 described later is 10 μm or more, the thickness of the heat-sealing resin layer 4 is preferably about 85 μm or less, more preferably about 15 to 45 μm, for example. When the thickness of the adhesive layer 5 described later is less than 10 μm or when the adhesive layer 5 is not provided, the thickness of the heat-sealing resin layer 4 is preferably about 20 μm or more, more preferably 35 to 85 μm. The degree can be mentioned.

[Adhesive layer 5]
In the exterior material for a power storage device of the present disclosure, the adhesive layer 5 is between the barrier layer 3 (or the corrosion-resistant film) and the heat-sealing resin layer 4 as necessary in order to firmly bond them. It is a layer to be provided.

From the viewpoint of more preferably exerting the effects of the invention of the present disclosure, the adhesive layer 5 is preferably about 120 ° C. or higher, about 130 ° C. or higher, about 140 ° C. or higher, about 150 ° C. or higher, and preferably about 170 ° C. or higher. Hereinafter, it is 150 ° C. or lower, and preferred ranges are 120 to 170 ° C., 120 to 150 ° C., 130 to 170 ° C., 130 to 150 ° C., 140 to 170 ° C., 140 to 150 ° C., 150. A melting peak is observed in the range of about 170 ° C. The number of melting peak temperatures may be one or plural. Further, in the adhesive layer 5, a melting peak temperature outside the range of 120 to 170 ° C. may be observed. However, from the viewpoint of more preferably exerting the effects of the invention of the present disclosure, it is preferable that the melting peak temperatures observed in the adhesive layer 5 are all in the range of 120 to 170 ° C. The melting peak temperature is measured by the method described in the above (melting peak temperature) column, except that an adhesive layer is obtained from the exterior material for a power storage device and a measurement sample is obtained.

The adhesive layer 5 is formed of a resin capable of adhering the barrier layer 3 and the heat-sealing resin layer 4. As the resin used for forming the adhesive layer 5, a thermoplastic resin can be preferably used. The resin used for forming the adhesive layer 5 preferably contains a polyolefin skeleton, and examples thereof include the polyolefins exemplified in the above-mentioned heat-sealing resin layer 4 and acid-modified polyolefins. On the other hand, from the viewpoint of firmly adhering the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 preferably contains an acid-modified polyolefin. Examples of the acid-modifying component include dicarboxylic acids such as maleic acid, itaconic acid, succinic acid, and adipic acid, and anhydrides thereof, acrylic acid, and methacrylic acid. Maleic acid is most preferred. From the viewpoint of heat resistance of the exterior material for the power storage device, the olefin component is preferably polypropylene-based resin, and the adhesive layer 5 most preferably contains maleic anhydride-modified polypropylene.

The fact that the resin constituting the adhesive layer 5 contains a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography-mass spectrometry, or the like, and the analysis method is not particularly limited. Further, the resin constituting the adhesive layer 5 comprises an acid-modified polyolefin, for example, when measuring the infrared spectroscopy at maleic anhydride-modified polyolefin, anhydride in the vicinity of a wave number of 1760 cm ^-1 and near the wave number 1780 cm ^-1 A peak derived from maleic anhydride is detected. However, if the degree of acid denaturation 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 thickness of the adhesive layer 5 is preferably about 60 μm or less, about 50 μm or less, and about 45 μm or less. The thickness of the adhesive layer 5 is preferably about 10 μm or more, about 20 μm or more, about 25 μm or more, and about 30 μm or more. The thickness range of the adhesive layer 5 is preferably about 10 to 60 μm, about 10 to 50 μm, about 10 to 45 μm, about 20 to 60 μm, about 20 to 50 μm, about 20 to 45 μm, and about 25 to 60 μm. , About 25 to 50 μm, about 25 to 45 μm, about 30 to 60 μm, about 30 to 50 μm, and about 30 to 45 μm. The adhesive layer 5 can be formed by, for example, extrusion molding of the heat-sealing resin layer 4 and the adhesive layer 5.

[Surface coating layer 6]
The exterior material for a power storage device of the present disclosure is above the base material layer 1 (base material layer 1), if necessary, for the purpose of improving at least one of designability, electrolytic solution resistance, scratch resistance, moldability, and the like. The surface coating layer 6 may be provided on the side opposite to the barrier layer 3 of the above. The surface coating layer 6 is a layer located on the outermost layer side of the exterior material for the power storage device when the power storage device is assembled using the exterior material for the power storage device.

The surface coating layer 6 can be formed of, for example, a resin such as polyvinylidene chloride, polyester, polyurethane, acrylic resin, or epoxy resin.

When the resin forming the surface coating layer 6 is a curable resin, the resin may be either a one-component curable type or a two-component curable type, but is preferably a two-component curable type. Examples of the two-component curable resin include two-component curable polyurethane, two-component curable polyester, and two-component curable epoxy resin. Of these, two-component curable polyurethane is preferable.

Examples of the two-component curable polyurethane include a polyurethane containing a first agent containing a polyol compound and a second agent containing an isocyanate compound. Preferably, a two-component curable polyurethane using a polyol such as a polyester polyol, a polyether polyol, and an acrylic polyol as a first agent and an aromatic or aliphatic polyisocyanate as a second agent can be mentioned. Examples of the polyurethane include a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance, and a polyurethane containing the isocyanate compound. Examples of the polyurethane include a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance, and a polyurethane containing the polyol compound. Examples of the polyurethane include polyurethane obtained by reacting a polyurethane compound in which a polyol compound and an isocyanate compound are previously reacted with water such as in the air to cure the polyurethane. 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 aromatic aliphatic isocyanate compounds. Examples of the isocyanate-based compound include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), and diphenylmethane diisocyanate. (MDI), naphthalenediocyanate (NDI) and the like. Moreover, a polyfunctional isocyanate modified product from one kind or two or more kinds of these diisocyanates and the like can be mentioned. Further, a multimer (for example, a trimer) can be used as the polyisocyanate compound. Examples of such a multimer include an adduct body, a biuret body, a nurate body and the like. The aliphatic isocyanate-based compound refers to an isocyanate having an aliphatic group and no aromatic ring, and the alicyclic isocyanate-based compound refers to an isocyanate having an alicyclic hydrocarbon group, which is an aromatic isocyanate-based compound. Refers to an isocyanate having an aromatic ring. Since the surface coating layer 6 is made of polyurethane, excellent electrolytic solution resistance is imparted to the exterior material for the power storage device.

The surface coating layer 6 has the above-mentioned lubricant or antistatic agent on at least one of the surface and the inside of the surface coating layer 6, depending on the functionality and the like to be provided on the surface coating layer 6 and the surface thereof. It may contain additives such as a blocking agent, a matting agent, a flame retardant, an antioxidant, a tackifier, and an antistatic agent. Examples of the additive include fine particles having an average particle size of about 0.5 nm to 5 μm. The average particle size of the additive shall be the median size measured by the laser diffraction / scattering type particle size distribution measuring device.

The additive may be either an inorganic substance or an organic substance. The shape of the additive is also not particularly limited, and examples thereof include a spherical shape, a fibrous shape, a plate shape, an amorphous shape, and a scaly shape.

Specific examples of additives include talc, silica, graphite, kaolin, montmorillonite, mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodium oxide, and antimony oxide. , Titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, refractory nylon, acrylate resin, Examples thereof include crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper and nickel. The additive may be used alone or in combination of two or more. Among these additives, silica, barium sulfate, and titanium oxide are preferable from the viewpoint of dispersion stability and cost. Further, the additive may be subjected to various surface treatments such as an insulation treatment and a highly dispersible treatment on the surface.

The method for forming the surface coating layer 6 is not particularly limited, and examples thereof include a method of applying a resin for forming the surface coating layer 6. When an additive is blended in the surface coating layer 6, a resin mixed with the additive may be applied.

The thickness of the surface coating layer 6 is not particularly limited as long as it exhibits the above-mentioned functions as the surface coating layer 6, and examples thereof include about 0.5 to 10 μm, preferably about 1 to 5 μm.

3. 3. Method for Manufacturing Exterior Material for Power Storage Device The method for manufacturing the exterior material for power storage device is not particularly limited as long as a laminated body in which each layer of the exterior material for power storage device of the present disclosure is laminated can be obtained, and at least a base material is used. Examples thereof include a method including a step of laminating the layer 1, the barrier layer 3, and the heat-sealing resin layer 4 in this order. That is, the method for producing an exterior material for a power storage device of the present disclosure includes at least a step of laminating a base material layer, a barrier layer, and a heat-sealing resin layer in this order to obtain a laminate. The exterior material for a power storage device is heat-sealed between the heat-sealing resin layers under the conditions of a temperature of 190 ° C. and a surface pressure of 1.0 MPa for 3 seconds, and the heat-sealing resin layers are peeled off from each other. In the heat seal strength measurement measured in 1 above, the heat seal strength decrease temperature T ° C. is included in the range of the measurement temperature of 110 ° C. or higher and 120 ° C. or lower.

An example of the method for manufacturing the exterior material for a power storage device of the present invention is as follows. First, a laminate in which the base material layer 1, the adhesive layer 2, and the barrier layer 3 are laminated in this order (hereinafter, may be referred to as “laminate A”) is formed. Specifically, the laminated body A is formed by applying an adhesive used for forming the adhesive layer 2 on the base material layer 1 or, if necessary, on the barrier layer 3 whose surface has been chemically converted, by a gravure coating method. It can be carried out by a dry laminating method in which the barrier layer 3 or the base material layer 1 is laminated and the adhesive layer 2 is cured after being applied and dried by a coating method such as a roll coating method.

Next, the heat-sealing resin layer 4 is laminated on the barrier layer 3 of the laminated body A. When the heat-sealing resin layer 4 is directly laminated on the barrier layer 3, the heat-sealing resin layer 4 is laminated on the barrier layer 3 of the laminated body A by a method such as a thermal laminating method or an extrusion laminating method. do it. When the adhesive layer 5 is provided between the barrier layer 3 and the heat-sealing resin layer 4, for example, (1) the adhesive layer 5 and the heat-sealing resin layer are placed on the barrier layer 3 of the laminated body A. A method of laminating 4 by extruding (coextrusion laminating method, tandem laminating method), (2) Separately, a laminated body in which the adhesive layer 5 and the heat-sealing resin layer 4 are laminated is formed, and the laminated body A is formed. A method of laminating on the barrier layer 3 of the above by a thermal laminating method, or a laminating body in which an adhesive layer 5 is laminated on the barrier layer 3 of the laminated body A is formed, and this is formed by a heat-sealing resin layer 4 and a thermal laminating method. Method of Laminating, (3) While pouring the melted adhesive layer 5 between the barrier layer 3 of the laminated body A and the heat-sealing resin layer 4 which has been formed into a sheet in advance, the adhesive layer 5 is passed through. A method of laminating the laminated body A and the heat-sealing resin layer 4 (sandwich laminating method), (4) a solution coating of an adhesive for forming the adhesive layer 5 on the barrier layer 3 of the laminated body A is performed. Examples thereof include a method of laminating by a method of drying, a method of baking, and the like, and a method of laminating a heat-sealing resin layer 4 which has been formed into a sheet in advance on the adhesive layer 5.

When the surface coating layer 6 is provided, the surface coating layer 6 is laminated on the surface of the base material layer 1 opposite to the barrier layer 3. The surface coating layer 6 can be formed, for example, by applying the above resin that forms the surface coating layer 6 to the surface of the base material layer 1. The order of the step of laminating the barrier layer 3 on the surface of the base material layer 1 and the step of laminating the surface coating layer 6 on the surface of the base material layer 1 is not particularly limited. For example, after forming the surface coating layer 6 on the surface of the base material layer 1, the barrier layer 3 may be formed on the surface of the base material layer 1 opposite to the surface coating layer 6.

As described above, the surface coating layer 6 provided as needed / the base material layer 1 / the adhesive layer 2 provided as needed / the barrier layer 3 / the adhesive layer 5 provided as needed / heat fusion A laminate having the sex resin layers 4 in this order is formed, and may be further subjected to heat treatment in order to strengthen the adhesiveness of the adhesive layer 2 and the adhesive layer 5 provided as needed.

In the exterior material for a power storage device, each layer constituting the laminated body may be subjected to surface activation treatment such as corona treatment, blast treatment, oxidation treatment, ozone treatment, etc., if necessary, to improve processing suitability. .. For example, by applying a corona treatment to the surface of the base material layer 1 opposite to the barrier layer 3, the printability of the ink on the surface of the base material layer 1 can be improved.

4. Applications of exterior materials for power storage devices The exterior materials for power storage devices of the present disclosure are used for packaging for sealing and accommodating power storage device elements such as positive electrodes, negative electrodes, and electrolytes. That is, a power storage device element having 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 of the present disclosure to form a power storage device.

Specifically, a power storage device element having at least a positive electrode, a negative electrode, and an electrolyte is provided with the exterior material for the power storage device of the present disclosure in a state in which metal terminals connected to each of the positive electrode and the negative electrode are projected outward. , The peripheral edge of the power storage device element is covered so that a flange portion (a region where the heat-sealing resin layers come into contact with each other) can be formed, and the heat-sealing resin layers of the flange portion are heat-sealed and sealed. Provides a power storage device using an exterior material for the power storage device. When the power storage device element is housed in the package formed of the exterior material for the power storage device of the present disclosure, the heat-sealing resin portion of the exterior material for the power storage device of the present disclosure is inside (the surface in contact with the power storage device element). ) To form a package. The heat-sealing resin layers of the two exterior materials for power storage devices may be overlapped with each other facing each other, and the peripheral edges of the overlapped exterior materials for power storage devices may be heat-sealed to form a package. As in the example shown in FIG. 4, one exterior material for a power storage device may be folded back and overlapped, and the peripheral edge portion may be heat-sealed to form a package. In the case of folding and overlapping, as shown in the example shown in FIG. 4, the sides other than the folded side may be heat-sealed to form a package by a three-way seal, or the package may be folded so that a flange portion can be formed. It may be sealed on all sides. Further, in the exterior material for the power storage device, a recess for accommodating the power storage device element may be formed by deep drawing molding or overhang molding. As shown in the example shown in FIG. 4, it is not necessary to provide a recess in one of the exterior materials for the power storage device and not in the exterior material for the other power storage device, and the other exterior material for the power storage device also has a recess. May be provided.

The exterior material for a power storage device of the present disclosure can be suitably used for a power storage device such as a battery (including a capacitor, a capacitor, 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 type of the secondary battery to which the exterior material for the power storage device of the present disclosure is applied is not particularly limited, and for example, a lithium ion battery, a lithium ion polymer battery, an all-solid-state battery, a lead storage battery, a nickel / hydrogen storage battery, and a nickel / hydrogen storage battery. Examples thereof include cadmium storage batteries, nickel / iron storage batteries, nickel / zinc storage batteries, silver oxide / zinc storage batteries, metal air batteries, polyvalent cation batteries, capacitors, and capacitors. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries can be mentioned as suitable application targets of the exterior materials for power storage devices of the present disclosure.

The present disclosure will be described in detail below with reference to Examples and Comparative Examples. However, the present disclosure is not limited to the examples.

<Manufacturing of exterior materials for power storage devices>
Example 1-4
A stretched nylon (ONy) film (thickness 25 μm) was prepared as a base material layer. Further, as a barrier layer, an aluminum foil (JIS H4160: 1994 A8021HO (thickness 40 μm)) was prepared. Next, the base material layer and the barrier layer are adhered to each other by a dry laminating method using a two-component urethane adhesive (polyol compound and aromatic isocyanate compound), and an aging treatment is performed to carry out the base material layer. A laminate of (thickness 25 μm) / adhesive layer (thickness after curing is 3 μm) / barrier layer (thickness 40 μm) was prepared. Both sides of the aluminum foil are subjected to chemical conversion treatment. The chemical conversion treatment of the aluminum foil is performed by applying a treatment liquid consisting of a phenol resin, a chromium fluoride compound, and phosphoric acid to both sides of the aluminum foil by a roll coating method so that the ^{amount of chromium applied is 10 mg / m 2 (dry mass).} This was done by coating and baking.

Next, on the barrier layer of the laminate obtained above, maleic anhydride-modified polypropylene (PPa1 or PPa2 in Table 1, respectively) as an adhesive layer (thickness 23 μm) and a heat-sealing resin layer (thickness). Random polypropylene (PP1, PP2, PP3, or PP4 in Table 1, respectively) as (22 μm) is co-extruded onto the barrier layer to coextrude the base material layer (thickness 25 μm) / adhesive layer (3 μm) /. An exterior material for a power storage device was obtained in which a barrier layer (40 μm), an adhesive layer (23 μm), and a heat-sealing resin layer (22 μm) were laminated in this order.

In Examples 1-4, the random polypropylene PP1, PP2, PP3, or PP4 used for the heat-sealing resin layer has a melting peak as compared with the polypropire used for the heat-sealing resin layer of the exterior material. In order to suppress thermal decomposition of random polypropylene in the formation of a heat-sealing resin layer by coextrusion, a material having a low temperature and a high molecular weight that is the peak value of the differential molecular weight distribution curve is selected and used. By co-extruding under lower temperature conditions than usual, the decrease in molecular weight, which is the peak value of the differential molecular weight distribution curve, was suppressed.

Example 5
A barrier layer of maleic anhydride-modified polypropylene (PPa1 in Table 1) as an adhesive layer (thickness 23 μm) and random polypropylene (PP1 in Table 1 respectively) as a heat-sealing resin layer (thickness 22 μm). Substrate layer (thickness 25 μm) / adhesive layer (3 μm) / barrier in the same manner as in Example 1 except that the temperature for co-extruding onto the above was set 30 ° C. higher than that in Example 1. An exterior material for a power storage device was obtained in which a layer (40 μm) / adhesive layer (23 μm) / heat-sealing resin layer (22 μm) was laminated in this order.

Example 6
A barrier layer of maleic anhydride-modified polypropylene (PPa1 in Table 1) as an adhesive layer (thickness 23 μm) and random polypropylene (PP2 in Table 1 respectively) as a heat-sealing resin layer (thickness 22 μm). Substrate layer (thickness 25 μm) / adhesive layer (3 μm) / barrier in the same manner as in Example 2 except that the temperature for co-extruding onto the above was set 30 ° C higher as compared with Example 2. An exterior material for a power storage device was obtained in which a layer (40 μm) / adhesive layer (23 μm) / heat-sealing resin layer (22 μm) was laminated in this order.

Comparative Example 1
In the same manner as in Example 1-6, a laminate of a base material layer (thickness 25 μm) / adhesive layer (thickness after curing is 3 μm) / barrier layer (thickness 40 μm) was prepared. Next, this laminate and an unstretched polypropylene film (thickness 40 μm) as a heat-sealing resin layer are bonded to each other using an adhesive containing a polyolefin resin and an isocyanate compound as curing components to form a base material layer (thickness 40 μm). An exterior material for a power storage device was obtained in which a thickness of 25 μm), an adhesive layer (3 μm), a barrier layer (40 μm), an adhesive layer (3 μm), and a heat-sealing resin layer (40 μm) were laminated in this order.

The melting peak temperatures of the adhesive layer or the heat-sealing resin layer of Examples 1-6 and Comparative Example 1 are as shown in Table 1. Moreover, these melting peak temperatures were measured by the following methods.

(Measurement of melting peak temperature)
An adhesive layer and a heat-sealing resin layer were obtained from the exterior material for the power storage device and used as measurement samples. For each measurement sample, the melting peak temperature was measured in accordance with the provisions of JIS K7121: 2012 (Plastic transition temperature measurement method (Appendix 1 of JIS K7121: 1987)). The measurement was performed using a differential scanning calorimeter (DSC, differential scanning calorimeter Q200 manufactured by TA Instruments).

(Measurement of molecular weight that is the peak value of the differential molecular weight distribution curve)
A heat-sealing resin layer was obtained from the exterior material for the power storage device and used as a measurement sample. For each measurement sample, high temperature gel permeation chromatography (SSC-7120 HT-GPC System manufactured by High Temperature GPC Senshu Kagaku Co., Ltd.) was used, and the concentration fraction of each molecular weight was plotted on the horizontal axis under the following measurement conditions. Was sequentially integrated to obtain an integrated molecular weight distribution curve. The differential molecular weight distribution curve was obtained by obtaining the differential value of the curve at each molecular weight, and the molecular weight which became the peak value on the vertical axis (dw / d (Log (M))) was obtained. As shown in the schematic diagram of FIG. 8, the differential molecular weight distribution curve is a graph of values obtained by differentiating the molecular weight on the horizontal axis and the concentration fraction on the vertical axis as logarithmic values of the molecular weight. The molecular weight at the position where the value obtained by differentiating the concentration fraction by the logarithmic value of the molecular weight is the highest is the molecular weight at which the peak value of the differential molecular weight distribution curve (see the position P in FIG. 8) is obtained.

(Measurement of softening point)
To measure the softening point of the exterior material for the power storage device, for example, as shown in the conceptual diagram of FIG. 7, the probe 11 is first installed on the surface of the heat-sealing resin layer 4 in the cross section of the exterior material for the power storage device (FIG. 7). Measurement start A). The cross section at this time is a portion where the cross section of the heat-sealing resin layer 4 obtained by cutting in the thickness direction of the exterior material for the power storage device is exposed. FIG. 7 shows the probe installation position 4a. Cutting was performed using a commercially available rotary microtome. As an atomic force microscope to which a cantilever with a heating mechanism can be attached, an afm plus system manufactured by ANASYS INSTRUMENTS is used, and as a probe, a cantilever THERMALever AN2-200 (spring constant 0.5 to 3 N / m) manufactured by ANASYS INSTRUMENTS is used. used. The tip radius of the probe 11 was 30 nm or less, the set value of the deflection of the probe 11 was -4 V, and the heating rate was 5 ° C./min. Next, when the probe is heated in this state, the surface of the heat-sealing resin layer 4 expands due to the heat from the probe, the probe 11 is pushed up, and the position of the probe 11 is the initial value. (Position when the probe temperature is 40 ° C.). When the heating temperature further increased, the heat-sealing resin layer 4 softened, the probe 11 pierced the heat-sealing resin layer 4, and the position of the probe 11 was lowered, as shown in FIG. 7C. The temperature at which the position was lowered (the point of change that began to fall from the rise) was defined as the softening point of the exterior material for the power storage device. The exterior material for the power storage device to be measured was at room temperature (25 ° C.), and a probe heated to 40 ° C. was placed on the surface of the heat-sealing resin layer 4 to start the measurement.

In Example 1, the difference between the melting peak temperature and the softening point of the heat-sealing resin layer was 3 ° C. Further, in Example 5, the difference between the melting peak temperature and the softening point of the heat-sealing resin layer was 2 ° C.

(Measurement of heat seal strength and measurement of measurement temperature range including heat seal strength decrease temperature T ° C.)
In accordance with the provisions of JIS K7127: 1999, the sealing strength of the exterior material for the power storage device at each measurement temperature (sample temperature) shown in Table 1 was measured as follows. As a test piece, an exterior material for a power storage device cut into strips having a width in the TD direction of 15 mm was prepared. Specifically, as shown in FIG. 5, first, the exterior material for each power storage device was cut into 60 mm (TD direction) × 200 mm (MD direction) (FIG. 5a). Next, the heat-sealing resin layers were made to face each other, and the exterior material for the power storage device was folded in half in the MD direction at the position of the crease P (middle in the MD direction) (FIG. 5b). Heat-sealing resin layers were heat-sealed between the heat-sealing resin layers under the conditions of a sealing width of 7 mm, a temperature of 190 ° C., and a surface pressure of 1.0 MPa for 3 seconds in the direction of MD about 10 mm from the crease P (FIG. 5c). In FIG. 5c, the shaded portion S is a heat-sealed portion. Next, a test piece was obtained by cutting in the direction of MD (cutting at the position of the alternate long and short dash line in FIG. 5d) so that the width in the direction of TD was 15 mm (FIG. 5e). Next, the test piece 13 was left at each measurement temperature for 2 minutes, and in each measurement temperature environment, the heat of the heat seal part (heat fusion part) was generated by a tensile tester (manufactured by Shimadzu Corporation, AG-Xplus (trade name)). The fusible resin layer was peeled off at a rate of 300 mm / min (FIG. 6). The maximum strength at the time of peeling was defined as the heat seal strength (N / 15 mm). The distance between the chucks is 50 mm. The average value measured three times was used. The results are shown in Table 1. Table 1 shows the temperature range in which the heat seal strength lowering temperature T ° C. exists.

(Measurement of Martens hardness)
Based on the indentation method, at the measurement temperature (sample temperature) of 100 ° C., the Vickers indenter is pushed in the thickness direction from the surface of the exterior material for each power storage device on the heat-sealing resin layer side to a depth of 1 μm to increase the Martens hardness. It was measured. The measurement conditions are as follows. The Martens hardness was calculated from the load-displacement curve obtained by pushing the Vickers indenter. As the measured value, the average obtained for 10 places on the surface on the heat-sealing resin layer side was adopted. Martens hardness calculates the surface area A (mm ²⁾ of the indenter at the maximum indentation depth of the Vickers indenter is obtained dividing the maximum load F (N) (F / A ) that in the surface area A (mm ^2). The details of the method for measuring the Martens hardness of the surface of the heat-sealing resin layer are as follows. As a measuring device, a picodenter HM-500 manufactured by Fisher Instruments Co., Ltd. was used. An exterior material for a power storage device was adhered to one side of a slide glass (76 mm × 26 mm × 1 mm) to which a double-sided adhesive tape was attached so that the heat-sealing resin layer side was opposite to the slide glass, and used as a measurement sample. Next, a heating stage was placed on an ultra-micro hardness tester equipped with a Vickers indenter, the stage temperature was set to 110 ° C., and the sample was heated for 5 minutes. Next, the surface hardness of the surface of the measurement sample on the heat-sealing resin layer side was measured. The results are shown in Table 2.
<Measurement conditions>
・ Indenter: Vickers (face-to-face angle 136 ° at the tip of a quadrangular pyramid)
-Measurement temperature (sample temperature): 100 ° C
・ Stage temperature: 110 ℃
・ Velocity: 1.000 μm / 10 seconds ・ Measurement depth: 1.0 μm
-Holding time: 5 seconds-Returning speed from pushing: 1.000 μm / 10 seconds

(Opening test)
The exterior material for the power storage device was cut into a size of 100 mm × 200 mm, and the heat-sealing resin layers were folded so as to face each other at the center position of the long side of the exterior material for the power storage device. Next, the short side was heat-sealed under the conditions of a temperature of 190 ° C., a surface pressure of 1.0 MPa, and a seal width of 7 mm for 3 seconds. Further, one long side was heat-sealed in the same manner, 2.0 g of water was added to the bag-shaped sample, and then the opening side (long side) was heat-sealed in the same manner to seal the water. It was used as a test sample. The test sample was placed in an oven, heated from room temperature (25 ° C.) at a heating rate of 5 ° C./min until the test sample temperature reached 130 ° C., and held at 130 ° C. for 30 minutes. The opening of the exterior material for the power storage device due to the increase in internal pressure was evaluated according to the following criteria. The results are shown in Table 1.
A: The package was opened in a temperature rise of 120 ° C. or higher and 130 ° C. or lower, or opened while being held at 130 ° C. for 30 minutes.
B: The package was opened at a temperature of 110 ° C. or higher and lower than 120 ° C.
C: The package was not opened even after being held at 130 ° C. for 30 minutes, or was opened at a temperature lower than 110 ° C.

In Table 1, the notation "122/134" means that the melting peak temperatures were observed at 122 ° C and 134 ° C. The notation 140/160 means that the melting peak temperatures were observed at 140 ° C and 160 ° C.

In the exterior material for the power storage device of Example 1-6, the heat-sealing resin layers were heat-sealed under the conditions of a temperature of 190 ° C. and a surface pressure of 1.0 MPa for 3 seconds, and the heat-sealing resin layers were peeled off from each other. In the heat seal strength measurement measured by the above, the predetermined heat seal strength decrease temperature T ° C. is included in the range of the measurement temperature of 110 ° C. or higher and 120 ° C. or lower. The exterior material for the power storage device of Example 1-6 is sealed by the exterior material for the power storage device until the power storage device reaches a high temperature of about 100 ° C., the power storage device becomes a high temperature of 120 ° C to 130 ° C, and the internal pressure is increased. It can be seen that when the temperature rises excessively, the exterior material for the power storage device can be opened and the gas generated inside the power storage device can be released to the outside. In particular, as is clear from Table 1, in Examples 1 and 5, and in Example 2 and Example 6, the same resin (PPa and PP1) is used for the adhesive layer and the heat-sealing resin layer, respectively. Alternatively, PP2) is used, and even though the melting peak temperature of the heat-sealing resin layer is as low as 125 ° C., the heat-sealing property of the exterior material for the power storage device of Examples 1 and 2 is used. Each of the resin layers had a higher molecular weight, which was the peak value of the differential molecular weight distribution curve, and a higher heat seal strength at 100 ° C. than the heat-sealing resin layers of the exterior materials for power storage devices of Examples 5 and 6, respectively.

When the predetermined heat seal strength lowering temperature T ° C. is at the measurement temperature of 130 ° C. or higher, it is considered that stable opening is not performed between the measurement temperature of 120 ° C. and 130 ° C. in the opening test evaluation.

As described above, the present disclosure provides the inventions of the following aspects.
Item 1. An exterior material for a power storage device composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealing resin layer in this order.
The exterior material for a power storage device is measured by heat-sealing the heat-sealing resin layers under the conditions of a temperature of 190 ° C. and a surface pressure of 1.0 MPa for 3 seconds, and peeling the heat-sealing resin layers from each other. An exterior material for a power storage device, wherein the heat seal strength reduction temperature T ° C. is included in the measurement temperature range of 110 ° C. or higher and 120 ° C. or lower in the heat seal strength measurement.
(Heat seal strength reduction temperature T ° C)
In the heat seal strength measurement, the measurement temperature is such that the heat seal strength is 35 N / 15 mm or more, and the heat seal strength at the heat seal strength decrease temperature T ° C. + 10 ° C. is 10 N / 15 mm or less.
Item 2. Item 2. The exterior material for a power storage device according to Item 1, wherein the heat-sealing resin layer has a melting peak temperature of 130 ° C. or lower.
Item 3. Item 2. The exterior material for a power storage device according to Item 1 or 2, wherein the heat-sealing resin layer has a molecular weight of 150,000 or more, which is a peak value of a differential molecular weight distribution curve measured by high-temperature gel permeation chromatography. ..
Item 4. Item 2. The exterior material for a power storage device according to any one of Items 1 to 3, wherein the resin constituting the heat-sealing resin layer has a polyolefin skeleton.
Item 5. Item 2. The exterior material for a power storage device according to any one of Items 1 to 4, wherein the resin constituting the heat-sealing resin layer contains polypropylene.
Item 6. An adhesive layer is provided between the barrier layer and the heat-sealing resin layer.
Item 2. The exterior material for a power storage device according to any one of Items 1 to 5, wherein the resin constituting the adhesive layer has a polyolefin skeleton.
Item 7. Item 6. The exterior material for a power storage device according to Item 6, wherein the adhesive layer has a melting peak observed in the range of 120 ° C. or higher and 170 ° C. or lower.
Item 8. Item 6. The exterior material for a power storage device according to Item 6 or 7, wherein the resin constituting the adhesive layer contains acid-modified polypropylene.
Item 9. Based on the indentation method, the Vickers hardness measured by pushing the Vickers indenter to a depth of 1 μm in the thickness direction from the surface of the exterior material for the power storage device on the heat-sealing resin layer side at a measurement temperature of 100 ° C. The exterior material for a power storage device according to any one of Items 1 to 8, which is 10.0 MPa or more.
Item 10. Item 2. The exterior material for a power storage device according to any one of Items 1 to 9, wherein the difference between the melting peak temperature and the softening point of the heat-sealing resin layer is 30 ° C. or less.
Item 11. At least, it includes a step of laminating the base material layer, the barrier layer, and the heat-sealing resin layer in this order to obtain a laminate.
The exterior material for a power storage device is measured by heat-sealing the heat-sealing resin layers under the conditions of a temperature of 190 ° C. and a surface pressure of 1.0 MPa for 3 seconds, and peeling the heat-sealing resin layers from each other. A method for manufacturing an exterior material for a power storage device, wherein the heat seal strength reduction temperature T ° C. is included in the measurement temperature range of 110 ° C. or higher and 120 ° C. or lower in the heat seal strength measurement.
(Heat seal strength reduction temperature T ° C)
In the heat seal strength measurement, the measurement temperature is such that the heat seal strength is 35 N / 15 mm or more, and the heat seal strength at the heat seal strength decrease temperature T ° C. + 10 ° C. is 10 N / 15 mm or less.
Item 12. A power storage device in which a power storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of the exterior material for the power storage device according to any one of Items 1 to 10.

1 Base material layer 2 Adhesive layer 3 Barrier layer 4 Heat-sealing resin layer 5 Adhesive layer 6 Surface coating layer 10 Exterior material for power storage devices

Claims

An exterior material for a power storage device composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealing resin layer in this order.
The exterior material for a power storage device is measured by heat-sealing the heat-sealing resin layers under the conditions of a temperature of 190 ° C. and a surface pressure of 1.0 MPa for 3 seconds, and peeling the heat-sealing resin layers from each other. An exterior material for a power storage device, wherein the heat seal strength reduction temperature T ° C. is included in the measurement temperature range of 110 ° C. or higher and 120 ° C. or lower in the heat seal strength measurement.
(Heat seal strength reduction temperature T ° C)
In the heat seal strength measurement, the measurement temperature is such that the heat seal strength is 35 N / 15 mm or more, and the heat seal strength at the heat seal strength decrease temperature T ° C. + 10 ° C. is 10 N / 15 mm or less.
The exterior material for a power storage device according to claim 1, wherein the heat-sealing resin layer is observed to have a melting peak temperature of 130 ° C. or lower.
The exterior for a power storage device according to claim 1 or 2, wherein the heat-sealing resin layer has a molecular weight of 150,000 or more, which is a peak value of a differential molecular weight distribution curve measured by high-temperature gel permeation chromatography. Material.
The exterior material for a power storage device according to any one of claims 1 to 3, wherein the resin constituting the heat-sealing resin layer has a polyolefin skeleton.
The exterior material for a power storage device according to any one of claims 1 to 4, wherein the resin constituting the heat-sealing resin layer contains polypropylene.
An adhesive layer is provided between the barrier layer and the heat-sealing resin layer.
The exterior material for a power storage device according to any one of claims 1 to 5, wherein the resin constituting the adhesive layer has a polyolefin skeleton.
The exterior material for a power storage device according to claim 6, wherein the adhesive layer has a melting peak observed in the range of 120 ° C. or higher and 170 ° C. or lower.
The exterior material for a power storage device according to claim 6 or 7, wherein the resin constituting the adhesive layer contains acid-modified polypropylene.
Based on the indentation method, the Vickers hardness measured by pushing the Vickers indenter to a depth of 1 μm in the thickness direction from the surface of the exterior material for the power storage device on the heat-sealing resin layer side at a measurement temperature of 100 ° C. The exterior material for a power storage device according to any one of claims 1 to 8, which is 10.0 MPa or more.
The exterior material for a power storage device according to any one of claims 1 to 9, wherein the difference between the melting peak temperature and the softening point of the heat-sealing resin layer is 30 ° C. or less.
At least, it includes a step of laminating the base material layer, the barrier layer, and the heat-sealing resin layer in this order to obtain a laminate.
The exterior material for a power storage device is measured by heat-sealing the heat-sealing resin layers under the conditions of a temperature of 190 ° C. and a surface pressure of 1.0 MPa for 3 seconds, and peeling the heat-sealing resin layers from each other. A method for manufacturing an exterior material for a power storage device, wherein the heat seal strength reduction temperature T ° C. is included in the measurement temperature range of 110 ° C. or higher and 120 ° C. or lower in the heat seal strength measurement.
(Heat seal strength reduction temperature T ° C)
In the heat seal strength measurement, the measurement temperature is such that the heat seal strength is 35 N / 15 mm or more, and the heat seal strength at the heat seal strength decrease temperature T ° C. + 10 ° C. is 10 N / 15 mm or less.
A power storage device in which a power storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of the exterior material for the power storage device according to any one of claims 1 to 10.