Non-permeable gas venting film for energy storage devices

Abstract

Provided is a water-impermeable degassing film for a power storage device which can be easily attached to the exterior material of a power storage device and makes it possible to discharge gas generated in the interior of the power storage device.　The water-impermeable degassing film is made to adhere to the exterior material of a power storage device so as to block a communication section provided to the exterior material and is used to discharge gas generated in the interior of the power storage device from the communication section. The water-impermeable degassing film is configured from a laminate comprising at least a substrate layer and an adhesive layer, and the adhesive layer of the water-impermeable degassing film is made to adhere to the surface of the power storage device.

Description

[Technical Field]

[0001] This disclosure relates to a water-impermeable gas venting film for energy storage devices. [Background technology]

[0002] While various types of energy storage devices have been developed, casing materials are essential components in all of them for sealing the energy storage device elements such as electrodes and electrolytes.

[0003] Traditionally, metal exterior materials have been widely used as exterior materials.

[0004] Furthermore, in recent years, laminated sheets have been proposed as exterior materials that can be easily processed into various shapes and that can be made thinner and lighter. These sheets consist of a base layer, a barrier layer, and a heat-sealable resin layer that are sequentially laminated. When using such a laminated film-like exterior material, the heat-sealable resin layers located in the innermost layers of the exterior material are facing each other, and the peripheral edges of the exterior material are heat-sealed to seal them, thereby encapsulating the energy storage device elements with the exterior material. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2016-31934 [Patent Document 2] Japanese Patent Publication No. 2010-153841 [Overview of the project] [Problems that the invention aims to solve]

[0006] For example, Patent Document 1 discloses a battery in which the battery element is housed in a pouch. The pouch has a valve structure with a check valve attached to a heat-sealed portion formed along its periphery. This check valve is configured to activate and release gas when the internal pressure of the pouch rises above a certain level.

[0007] Furthermore, Patent Document 2 discloses a battery in which the battery element is housed in a box-shaped laminate container. In this laminate container, a flange-shaped heat-sealed portion formed along its periphery has a section that is easier to peel off than other parts (hereinafter referred to as the easy-peel section). The easy-peel section peels off when the internal pressure of the laminate container rises above a certain level, and gas is released through a hole formed in the center of the easy-peel section. Unlike check valves such as those in Patent Document 1, the easy-peel section is a break valve that does not return to its original state once it has peeled off.

[0008] The primary objective of this disclosure is to provide a non-permeable gas venting film for energy storage devices that is easy to attach to the exterior material of the energy storage device and can discharge gases generated inside the energy storage device. [Means for solving the problem]

[0009] The inventors of this disclosure have diligently studied to solve the above problems. As a result, they have found that by adhering a non-permeable gas venting film to the surface of the exterior material of the energy storage device so as to seal the communication portion provided in the exterior material of the energy storage device, and by allowing gas generated inside the energy storage device to be discharged from the communication portion, the non-permeable gas venting film is composed of a laminate comprising at least a base layer and an adhesive layer, and by using the adhesive layer of the non-permeable gas venting film by adhering it to the surface of the energy storage device, the non-permeable gas venting film can be easily attached to the exterior material of the energy storage device and can discharge gas generated inside the energy storage device.

[0010] In addition, the inventor of the present disclosure arranged so that a non-water-permeable gas venting film is interposed between the welded portions of the exterior material of the power storage device, and configured to discharge the gas generated inside the power storage device. The non-water-permeable gas venting film is composed of at least a laminate including a base material layer and an adhesive layer. The adhesive layer of the non-water-permeable gas venting film is adhered to the welded portion of the exterior material, and the gas is permeated in the thickness direction of the non-water-permeable gas venting film to discharge the gas generated inside the power storage device. As a result, it has been found that the power storage device can be easily attached to the exterior material and the gas generated inside the power storage device can be discharged.

[0011] The present disclosure has been completed by further studies based on these findings.

[0012] That is, the present disclosure provides the inventions of the first aspect and the second aspect listed below.

[0013] The invention of the first aspect of the present disclosure is a non-water-permeable gas venting film that is adhered to the surface of the exterior material of the power storage device so as to block a communication portion provided in the exterior material of the power storage device and is used to discharge the gas generated inside the power storage device from the communication portion. The non-water-permeable gas venting film is composed of at least a laminate including a base material layer and an adhesive layer, and the adhesive layer of the non-water-permeable gas venting film is adhered to the surface of the power storage device.

[0014] In addition, the invention of the second aspect of the present disclosure is a non-water-permeable gas venting film that is arranged to be interposed between the welded portions of the exterior material of the power storage device and is used to discharge the gas generated inside the power storage device. The non-water-permeable gas venting film is composed of at least a laminate including a base material layer and an adhesive layer, and the adhesive layer of the non-water-permeable gas venting film is adhered to the welded portion of the exterior material. The gas permeates in the thickness direction of the non-water-permeable gas venting film to discharge the gas.

Advantages of the Invention

[0015] According to the present disclosure, it is possible to provide a non-water-permeable gas venting film for a power storage device that is easy to attach to the exterior material of the power storage device and can discharge the gas generated inside the power storage device.

Brief Description of the Drawings

[0016] [Figure 1] It is a schematic diagram of an example in which the non-water-permeable gas venting film of the first aspect of the present disclosure is applied to the surface of an exterior material (rectangular metal can) of a power storage device. [Figure 2] It is a schematic diagram of an example in which the non-water-permeable gas venting film of the first aspect of the present disclosure is applied to the surface of an exterior material (rectangular metal can) of a power storage device. [Figure 3] It is a schematic diagram of an example in which the non-water-permeable gas venting film of the first aspect of the present disclosure is applied to the surface of an exterior material (cylindrical metal can) of a power storage device. [Figure 4] It is a schematic diagram of an example in which the non-water-permeable gas venting film of the first aspect of the present disclosure is applied to the surface of an exterior material (cylindrical metal can) of a power storage device. [Figure 5] It is a schematic diagram of an example in which the non-water-permeable gas venting film of the first aspect of the present disclosure is applied to the surface of an exterior material (laminated film) of a power storage device. [Figure 6] It is a schematic diagram of an example in which the non-water-permeable gas venting film of the first aspect of the present disclosure is applied to the surface of an exterior material (laminated film) of a power storage device. [Figure 7] It is a schematic diagram of an example in which the non-water-permeable gas venting film of the first aspect of the present disclosure is applied to the welded portion of an exterior material (laminated film) of a power storage device. [Figure 8] It is a schematic cross-sectional view taken along line A-A' of FIG. 7. [Figure 9] It is an enlarged view of the region IX of FIG. 8. [Figure 10] It is a schematic diagram of an example in which the non-water-permeable gas venting film of the second aspect of the present disclosure is applied to the welded portion of an exterior material (laminated film) of a power storage device. [Figure 11] It is a schematic cross-sectional view taken along line A-A' of FIG. 10. [Figure 12] This is an enlarged view of region XII in Figure 11. [Figure 13] This is a schematic cross-sectional view of a non-permeable gas venting film in which two non-permeable gas venting films are stacked on top of each other, with only the edges heat-sealed and folded over. [Figure 14] This is a schematic diagram of an example in which a non-permeable gas venting film according to a second aspect of the present disclosure is applied to the welded portion of the exterior material (laminated film) of an energy storage device. [Figure 15] This is a schematic cross-sectional view along the line A-A' in Figure 14. [Figure 16] This is an enlarged view of region XVI in Figure 15. [Figure 17] This is a schematic diagram of an example in which a non-permeable gas venting film according to a second aspect of the present disclosure is applied to the welded portion of the exterior material (laminated film) of an energy storage device. [Figure 18] This is a schematic cross-sectional view along the line A-A' in Figure 17. [Figure 19] This is an enlarged view of region XIX in Figure 18. [Figure 20] This is an example of a schematic cross-sectional view of the non-permeable gas venting film of this disclosure. [Figure 21] This is an example of a schematic cross-sectional view of the non-permeable gas venting film of this disclosure. [Figure 22] This is an example of a schematic cross-sectional view of the non-permeable gas venting film of this disclosure. [Figure 23] This is a schematic cross-sectional view of an exterior material made of laminated film. [Modes for carrying out the invention]

[0017] A first aspect of the present disclosure is a non-permeable gas venting film that is adhered to the surface of an exterior material of an energy storage device so as to block a communication portion provided on the exterior material of the energy storage device, and is used to discharge gas generated inside the energy storage device from the communication portion, and is composed of a laminate comprising at least a base layer and an adhesive layer, characterized in that the adhesive layer of the non-permeable gas venting film is adhered to the surface of the energy storage device. The non-permeable gas venting film of the first aspect, having this configuration, is easy to attach to the exterior material of an energy storage device and can discharge gas generated inside the energy storage device.

[0018] Furthermore, the water-impermeable gas venting film of the second aspect of this disclosure is a water-impermeable gas venting film that is arranged to be interposed between the welded portions of the exterior material of an energy storage device and used to vent gas generated inside the energy storage device, and is composed of a laminate comprising at least a base layer and an adhesive layer, wherein the adhesive layer of the water-impermeable gas venting film is adhered to the welded portions of the exterior material, and the gas permeates in the thickness direction of the water-impermeable gas venting film, thereby venting the gas. The water-impermeable gas venting film of the second aspect, having this configuration, is easy to attach to the exterior material of an energy storage device and can vent gas generated inside the energy storage device.

[0019] The non-permeable gas venting films of the first and second embodiments of this disclosure will be described in detail below with reference to Figures 1 to 23.

[0020] In this specification, numerical ranges indicated by "~" mean "greater than or equal to" and "less than or equal to." For example, the notation 2~15mm means 2mm or more and 15mm or less.

[0021] The non-permeable gas venting films of the first and second embodiments of this disclosure are adhesive films used in energy storage devices. First, the methods of using the non-permeable gas venting films of this disclosure in energy storage devices will be described in detail in the first and second embodiments, respectively. Next, the laminated structure of the non-permeable gas venting films and the properties and physical characteristics of the resins used in each layer will be described in detail.

[0022] A non-permeable gas venting film according to a first aspect of the present disclosure is adhered to the surface of an exterior material of an energy storage device so as to seal a communication portion provided in the exterior material of the energy storage device, and is used to discharge gas generated inside the energy storage device from the communication portion. In the non-permeable gas venting film according to a first aspect of the present disclosure, the adhesive layer is adhered to the surface of the energy storage device so as to seal a communication portion provided in the exterior material of the energy storage device, thereby adhering the non-permeable gas venting film to the surface of the exterior material of the energy storage device.

[0023] For example, as shown in the schematic diagrams of Figures 1 to 9, the non-permeable gas venting film 1 of the first embodiment is adhered to the surface of the exterior material 3 such that it blocks the communication portion H provided on the exterior material 3 of the energy storage device 10. Gas generated inside the energy storage device 10 (energy storage device element 4) passes through the non-permeable gas venting film 1 and is discharged from the communication portion H. In other words, the communication portion H is a communication portion that connects the energy storage device element 4 to the outside, and the non-permeable gas venting film 1 prevents moisture from entering the energy storage device 10 from the outside, and the gas generated inside the energy storage device 10 (energy storage device element 4) is discharged to the outside.

[0024] Figures 1 and 2 illustrate an embodiment in which the exterior material 3 of the energy storage device 10 is made of a rectangular metal can. Figures 3 and 4 also illustrate an embodiment in which the exterior material 3 of the energy storage device 10 is made of a cylindrical metal can.

[0025] In the energy storage devices shown in Figures 1-4, the surface of the exterior material 3 to which the non-permeable gas venting film 1 is bonded is made of metal. That is, in the first embodiment, when the non-permeable gas venting film 1 is applied to the exterior material 3 made of a metal can, the adhesive layer 12 of the non-permeable gas venting film 1 can be made of a resin that is both non-permeable and gas-permeable, and that has adhesive properties to the metal constituting the outer surface of the exterior material 3.

[0026] Figures 5 to 9 illustrate an embodiment in which the exterior material 3 of the energy storage device 10 is composed of a laminate (laminated film) comprising at least a base material layer 31, a barrier layer 33, and a heat-fusible resin layer 35 in that order.

[0027] In the energy storage devices shown in Figures 5-9, the surface of the exterior material 3 to which the non-permeable gas venting film 1 is bonded is made of resin. That is, in the first embodiment, when the non-permeable gas venting film 1 is applied to the exterior material 3 made of laminated film, the adhesive layer 12 of the non-permeable gas venting film 1 can be made of a resin that is non-permeable and gas-permeable, and that has adhesive properties to the resin constituting the outer surface of the exterior material.

[0028] In the first embodiment, the shape of the connecting portion H provided in the exterior material 3 (shape in plan view) is not particularly limited. For example, Figures 1, 3, and 5 show a configuration in which the connecting portion H is circular, and Figures 2, 4, and 6 show a configuration in which the connecting portion H is slit-shaped.

[0029] Furthermore, there are no particular restrictions on the location where the communication portion H is provided; it can be provided on the bottom surface, side surface, or welded portion of the energy storage device 10. For example, Figures 1 to 6 illustrate an embodiment in which the communication portion H is provided on the bottom surface (which can also be called the top surface, lower surface, or top surface) of the energy storage device 10. Also, for example, Figures 7 to 9 illustrate an embodiment in which the communication portion H is provided on the welded portion of the energy storage device 10 (the welded portion between the heat-fusible resin layers 35 formed on the peripheral edge 3a of the exterior material 3, which will be described later). As shown in Figures 7 to 9, when the communication portion H is provided on the welded portion of the energy storage device 10, an unwelded portion can be formed on a part of the welded portion between the heat-fusible resin layers 35 formed on the peripheral edge 3a of the exterior material 3, and this portion can be designated as the communication portion H.

[0030] In the first embodiment, gas generated inside the energy storage device 10 reaches the impermeable gas venting film 1 through the communication portion H, and the impermeable gas venting film 1 is adhered to the surface of the energy storage device 10 in such a way that the gas can permeate in the thickness direction of the impermeable gas venting film 1. As described later, in the thickness direction of the impermeable gas venting film 1, the distance the gas can permeate is short, so the gas can pass through the impermeable gas venting film 1. On the other hand, in the direction perpendicular to the thickness direction of the impermeable gas venting film 1, the distance the gas can permeate is longer, so the gas is less likely to permeate. Therefore, in the first embodiment, it is important to adhere the impermeable gas venting film 1 to the surface of the exterior material 3 in such a way that the communication portion H provided in the exterior material 3 of the energy storage device 10 is blocked, so that the gas can permeate in the thickness direction of the impermeable gas venting film 1.

[0031] Furthermore, in the embodiment shown in Figures 7 to 9, where the communication portion H is provided on the welded portion of the energy storage device 10 (the welded portion of the heat-fusible resin layer 35 formed on the peripheral edge 3a of the exterior material 3, which will be described later), a non-permeable gas venting film 1 is attached to the communication portion H provided on a part of the welded portion of the peripheral edge 3a of the exterior material 3. As shown in the enlarged view of Figure 9, the structure allows gas generated inside the energy storage device 10 to permeate the non-permeable gas venting film 1 in the thickness direction and be discharged to the outside. In the second embodiment, it is preferable that the non-permeable gas venting film 1 is interposed between the welded portions such that the heat-fusible resin layer 35 of the exterior material 3 (described later) and the adhesive layer 12 of the non-permeable gas venting film 1 are bonded together at the welded portion of the non-permeable gas venting film 1. With the non-permeable gas venting film 1 interposed in the welded portion, a portion of the welded portion is provided where the heat-fusible resin layers 35 are not welded together, and this portion can be made into a communication portion H. Furthermore, it is also possible to form a portion of the exterior material 3 that does not have a heat-fusible resin layer 35, and use that portion as a connecting portion H.

[0032] Next, the non-permeable gas venting film of the second aspect of the present disclosure is arranged to be interposed between the welded portions of the exterior material of an energy storage device and is used to vent gas generated inside the energy storage device. In the non-permeable gas venting film of the second aspect of the present disclosure, the adhesive layer of the non-permeable gas venting film is adhered to the welded portions of the exterior material, and gas generated inside the energy storage device is vented to the outside by permeating the non-permeable gas venting film in the thickness direction. In the non-permeable gas venting film of the second aspect of the present disclosure, in order for gas to permeate the non-permeable gas venting film in the thickness direction, the non-permeable gas venting film is arranged to be interposed between the welded portions of the exterior material such that the thickness direction of the non-permeable gas venting film blocks the opening of the communication portion of the exterior material.

[0033] For example, as shown in the schematic diagrams of Figures 10-12 and 14-19, the non-permeable gas venting film 1 of the second embodiment is positioned between the welded portions of the exterior material 3 of the energy storage device 10. Gas generated inside the energy storage device 10 (energy storage device element 4) is discharged by passing through the non-permeable gas venting film 1. In other words, the non-permeable gas venting film 1 positioned between the welded portions plays a role in blocking the communication portion connecting the energy storage device element 4 to the outside, and the non-permeable gas venting film 1 suppresses the intrusion of moisture from the outside of the energy storage device 10, and the gas generated inside the energy storage device 10 (energy storage device element 4) is discharged to the outside.

[0034] In the schematic diagrams of Figures 10-12 and 14-19, the non-permeable gas venting film 1 is folded back and sandwiched between the welded joints of the exterior material 3 of the energy storage device 10. By folding the non-permeable gas venting film 1 so that the adhesive layer 12 is on the outside and the base material layer 11 is on the inside, the outer adhesive layer 12 can be bonded to the heat-sealable resin layer 35 of the exterior material 3.

[0035] Furthermore, as a method for creating a folded shape for the non-permeable gas venting film 1 placed between the welded parts, in addition to folding the non-permeable gas venting film 1, for example, as shown in the schematic diagram of Figure 13, two non-permeable gas venting films may be placed on top of each other and only the ends may be heat-sealed (at the position of the heat-sealed part HS in Figure 13) to create a folded shape. In this case, the heat sealing of the two non-permeable gas venting films 1 may be performed before the non-permeable gas venting films 1 are placed between the welded parts, or it may be performed when forming the welded parts of the exterior material 3, by placing the two non-permeable gas venting films on top of each other between the exterior material 3 and heat-sealing the ends of the non-permeable gas venting films 1 at the same time as forming the welded parts. Furthermore, as shown in Figure 16, for example, if the area over which the two non-permeable gas venting films 1 are heat-fused becomes large, gas will have difficulty passing through the heat-fused portion. Therefore, it is desirable to design the non-permeable gas venting film 1 to be positioned at the welded portion of the exterior material 3 so that a portion of the non-permeable gas venting film 1 protrudes from the welded portion of the exterior material 3, as shown in Figures 14 to 16 described later, so that the gas can permeate in the thickness direction of the non-permeable gas venting film and be discharged.

[0036] Figures 10-12 and 14-19 illustrate an embodiment in which the exterior material 3 of the energy storage device 10 is composed of a laminate (laminated film) comprising at least a base material layer 31, a barrier layer 33, and a heat-fusible resin layer 35 in that order.

[0037] In the energy storage device 10 shown in Figures 10-12 and 14-19, the welded portion formed on the peripheral edge 3a of the exterior material 3 is made of resin (for example, the heat-sealable resin layer 35 of the exterior material 3, which will be described later). That is, in the second embodiment, when the non-permeable gas venting film 1 is applied to the exterior material 3 made of a laminated film, the non-permeable gas venting film 1 can be made of a resin that is non-permeable and gas-permeable, and that has adhesion to the resin constituting the innermost layer of the exterior material (i.e., the heat-sealable resin layer 35 of the exterior material 3, which will be described later).

[0038] As shown in Figures 14-16, in the second embodiment, the non-permeable gas venting film 1 can also be positioned at the welded portion of the exterior material 3 such that a portion of the non-permeable gas venting film 1 protrudes from the welded portion of the exterior material 3. In the schematic diagrams of Figures 14-16, the portion of the non-permeable gas venting film 1 that protrudes from the welded portion has its periphery heat-sealed, forming a bag shape, and as shown in the schematic diagram of Figure 16, it is positioned so that gas can permeate from the thickness direction of the non-permeable gas venting film 1. Note that Figures 14-16 show an example in which two non-permeable gas venting films 1 are laminated and three sides of the portion of the non-permeable gas venting film 1 that protrudes from the welded portion (the x1 side, x2 side, and z1 side in Figure 14) are heat-sealed, but it is also possible to fold a single non-permeable gas venting film 1 and heat-seal two sides (the x1 side and x2 side in Figure 14) (the z1 side being the folded portion).

[0039] Furthermore, as shown in Figures 17-19, in the second embodiment, a communication portion H can be provided in the welded portion of the exterior material 3, exposing the surface of the non-permeable gas venting film 1. Gas can also be discharged through this communication portion H. As with the first embodiment, the shape of the communication portion H (shape in plan view) is not particularly limited. For example, Figure 17 illustrates a configuration in which the communication portion H is slit-shaped, but it may also be circular or the like.

[0040] As explained in the first embodiment, in the thickness direction of the non-permeable gas venting film 1, the distance the gas can permeate is short, so the gas can pass through the non-permeable gas venting film 1. On the other hand, in the direction perpendicular to the thickness direction of the non-permeable gas venting film 1, the distance the gas can permeate is longer, so the gas is less likely to permeate. Therefore, in the second embodiment as well, it is important to ensure that the gas can permeate in the thickness direction of the non-permeable gas venting film 1.

[0041] Next, the lamination structure, resin, and physical properties of the non-permeable gas venting film of this disclosure will be described in detail.

[0042] The water-impermeable gas venting film 1 of this disclosure is composed of a laminate comprising at least a base layer 11 and an adhesive layer 12. Furthermore, the water-impermeable gas venting film 1 of this disclosure has the function of allowing gas generated inside the energy storage device to permeate in the thickness direction of the water-impermeable gas venting film 1. In addition, the water-impermeable gas venting film 1 is water-impermeable.

[0043] In other words, the non-permeable gas venting film 1 of this disclosure must, as a whole, be permeable to gas generated inside the energy storage device (allowing gas to pass through in the thickness direction of the non-permeable gas venting film 1) and to suppress the intrusion of moisture from the external environment of the energy storage device.

[0044] From the viewpoint of suitably exhibiting the effects of the present invention, the non-permeable gas venting film 1 of this disclosure preferably has a water vapor transmission rate of 10 cc / m² when left standing for 48 hours in an environment of 60°C and 90% RH. 2 Less than / day, more preferably 5cc / m 2 Less than or equal to / day, more preferably 2cc / m³ 2 Less than or equal to / day, more preferably 0 cc / m³ 2 The value is / day. The method for measuring the water vapor transmission rate of the non-permeable gas venting film 1 is as follows:

[0045] <Water vapor transmission rate> In accordance with the cup method specified in JIS Z 0208, water vapor transmission rate is measured in an environment of 60°C and 90% RH. Using a screw-type clamp, the test specimen is cut from the sample to a diameter of 75 mm, and three 5 mm diameter holes are drilled 5 mm inward from the outer circumference before being set in the jig. A cup with a transmission area of ​​60 mm diameter is used.

[0046] Furthermore, from the viewpoint of suitably exhibiting the effects of the present invention, the non-permeable gas venting film 1 of this disclosure preferably has a carbon dioxide transmission rate of 5000 cm². 3 / (m 2 (24 hours atm) or more, more preferably 8000 cm² 3 / (m 2 (24 hours atm) or more, more preferably 10,000 cm²3 / (m 2 ·24 h·atm) or more. Regarding the upper limit of the carbon dioxide permeability of the water-impermeable gas-venting film 1 of the present disclosure, for example, 100,000 cm 3 / (m 2 ·24 h·atm) or less can be mentioned. The method for measuring the carbon dioxide permeability of the water-impermeable gas-venting film 1 is as follows.

[0047] <Carbon dioxide permeability> Conform to the test items specified in JIS K 7126-1:2006: gas permeability and gas permeability coefficient (differential pressure method), and measure the carbon dioxide permeability of the film under the following conditions. Detector: Gas chromatograph (thermal conductivity detector (TDC)) Gas: Carbon dioxide gas (CO2) (atmosphere under humidification) Temperature and humidity: 60 ± 2 °C · 50 ± 5% RH Differential pressure: 1 atm (partial pressure in the state of 60 °C · 50% RH (gas: 68.52 cmHg, water vapor: 7.48 cmHg) Permeation area: 15.2 × 10 -4 m 2 (Permeation part diameter φ4.4 × 10 -2 m) Number of tests: n = 1 Measuring device: Differential pressure type gas / vapor permeability measuring device

[0048] Also, from the viewpoint of preferably exerting the effects of the present invention, the oxygen permeability of the water-impermeable gas-venting film 1 of the present disclosure is preferably 50 cm 3 / (m 2 ·24 h·atm) or more, more preferably 100 cm 3 / (m 2 ·24 h·atm) or more, still more preferably 200 cm 3 / (m 2 ·24 h·atm) or more. Regarding the upper limit of the oxygen permeability of the water-impermeable gas-venting film 1 of the present disclosure, for example, 100,000 cm 3 / (m 2 ·24 h·atm) or less can be mentioned. The method for measuring the oxygen permeability of the water-impermeable gas-venting film 1 is as follows.

[0049] <Oxygen permeability> Oxygen permeability can be measured using an oxygen gas permeability measuring device under conditions of 40°C and 90% RH, in accordance with JIS K7126-2:2006 (Plastics - Films and Sheets - Gas Permeability Test Methods - Part 2: Isobaric Method, Annex A: Test Method for Oxygen Gas Permeability by Electrolytic Sensor Method). For example, the OXTRAN2 / 22 manufactured by MOCON, Inc., USA, can be used as the oxygen gas permeability measuring device. The measurement is performed by placing the non-permeable gas-venting film inside the device so that its surface is in contact with oxygen gas, with a permeation area of ​​50 cm². 2 The measurements shall be carried out under the following conditions. The above measurements shall be performed in the following procedure. First, the apparatus shall be purged by supplying a carrier gas at a flow rate of 10 cc / min for 60 minutes or more. The carrier gas may be nitrogen gas containing approximately 5% hydrogen. After purging, the test gas shall be flowed into the apparatus, and after allowing 12 hours to be allowed to reach equilibrium, measurements shall be started under the above temperature and humidity conditions. The test gas shall be dry oxygen containing at least 99.5% (by volume) of oxygen. At least three samples shall be measured under each condition, and the average of these measurements shall be taken as the oxygen permeability value for that condition.

[0050] For example, polyolefin resins have low water vapor permeability and high carbon dioxide permeability, making them suitable as resins for the non-permeable gas venting film 1 of this disclosure. On the other hand, polyester, polyamide, polyurethane, polycarbonate, polyvinyl alcohol, etc., have high water vapor permeability and are therefore unsuitable as resins for the non-permeable gas venting film 1 of this disclosure. Furthermore, polyester, polyamide, vinyl fluoride resin, AS resin (acrylonitrile styrene copolymer), polyacetal, etc., have low carbon dioxide gas permeability and are therefore unsuitable as resins for the non-permeable gas venting film 1 of this disclosure.

[0051] The non-permeable gas venting film 1 of this disclosure has a structure in which at least a base layer 11 and an adhesive layer 12 are laminated, and the adhesive layer 12 constitutes one side surface of the non-permeable gas venting film 1.

[0052] The non-permeable gas venting film 1 may further include at least one resin layer on the substrate layer 11 side of the adhesive layer 12. The resin layer is laminated between the adhesive layer 12 and the substrate layer 11, on the side of the substrate layer 11 opposite to the adhesive layer 12. The resin layer is at least one layer; for example, Figure 21 shows a laminated configuration with one resin layer 13, and Figure 22 shows a laminated configuration with two resin layers, resin layer 13 and resin layer 14. Laminated configurations of the non-permeable gas venting film 1 of this disclosure include a 2-layer configuration, a 3-layer configuration, a 4-layer configuration, a 5-layer configuration, etc. Among these, a 2-layer configuration or a 3-layer configuration is preferred.

[0053] Examples of the laminate configurations of the non-permeable gas venting film 1 of this disclosure include a two-layer configuration in which a base layer 11 and an adhesive layer 12 are laminated in that order (see Figure 20); a three-layer configuration in which an adhesive layer 12, a base layer 11, and a resin layer 13 are laminated in that order (see Figure 21); and a four-layer configuration in which an adhesive layer 12, a base layer 11, a resin layer 13, and a resin layer 14 are laminated in that order (see Figure 22).

[0054] The total thickness of the non-permeable gas venting film 1 of this disclosure is, for example, about 5 μm or more, preferably about 20 μm or more, and more preferably about 30 μm or more, from the viewpoint of suitably exhibiting the effects of this disclosure. Alternatively, the total thickness of the non-permeable gas venting film 1 of this disclosure is, for example, about 500 μm or less, preferably about 200 μm or less, and more preferably 180 μm or less. Preferred ranges for the total thickness of the non-permeable gas venting film 1 of this disclosure include about 5 to 500 μm, about 5 to 200 μm, about 5 to 180 μm, about 20 to 500 μm, about 20 to 200 μm, about 20 to 180 μm, about 30 to 500 μm, about 30 to 200 μm, and about 30 to 180 μm. More specifically, when the non-permeable gas venting film 1 of this disclosure is used in consumer energy storage devices, the total thickness is preferably about 60 to 100 μm, and when it is used in automotive energy storage devices, the total thickness is preferably about 80 to 500 μm.

[0055] The following details the materials, thicknesses, etc., that constitute the base layer 11, adhesive layer 12, and optional resin layers (e.g., resin layer 13, resin layer 14, etc.) included in the non-permeable gas venting film 1 of this disclosure.

[0056] [Base material layer 11] In the non-permeable gas venting film 1 of this disclosure, the substrate layer 11 is a layer that functions as a support.

[0057] The base layer 11 is preferably formed from a resin that has low water vapor permeability and high carbon dioxide permeability.

[0058] The base layer 11 is preferably a layer containing a polyolefin resin (i.e., having a polyolefin skeleton), and more preferably a layer formed of a polyolefin resin. Examples of polyolefin resins include polyethylene and polypropylene. The polyolefin resin may also be a resin in which polyolefin has been acid-modified (acid-modified polyolefin). As for acid-modified polyolefins, there are no particular limitations as long as they are acid-modified polyolefins, but preferably examples include polyolefins graft-modified with an unsaturated carboxylic acid or its anhydride, such as acid-modified polyethylene and acid-modified polypropylene.

[0059] Examples of polyolefins include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymer of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymer of propylene and ethylene); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferred.

[0060] Furthermore, the polyolefin may be a cyclic polyolefin. A cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of olefins that are constituent monomers of a cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of cyclic monomers that are constituent monomers of the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, examples of cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, cyclic alkenes are preferred, and norbornene is more preferred. Styrene can also be used as a constituent monomer.

[0061] In acid-modified polyolefins, the polyolefin to be acid-modified is also preferably the aforementioned polyolefin. For example, a carboxylic acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a portion of the monomers constituting the cyclic polyolefin with an α,β-unsaturated carboxylic acid or its anhydride, or by block polymerization or graft polymerization of an α,β-unsaturated carboxylic acid or its anhydride to a cyclic polyolefin.

[0062] Examples of carboxylic acids or their anhydrides used for acid modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride. When polyolefin resins are analyzed by infrared spectroscopy, it is preferable that a peak originating from maleic anhydride is detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak originating from maleic anhydride is detected at wavenumber 1760 cm⁻¹. -1 Nearby wave frequency 1780cm -1 A peak originating from maleic anhydride is detected in the vicinity. In other words, when polyolefin resins are measured by infrared spectroscopy in this case, a peak originating from maleic anhydride is detected. However, if the degree of acid modification is low, the peak may become small and not be detected. In that case, analysis is possible by nuclear magnetic resonance spectroscopy.

[0063] The base layer 11 may be formed by a single resin component or by a blended polymer combining two or more resin components. From the viewpoint of film-forming properties of the base layer 11, it is preferable to form it by a blended polymer combining two or more resin components. When using a blended polymer, it is preferable that the base layer 11 has acid-modified polypropylene as the main component (50% by mass or more) and 50% by mass or less of other resins (preferably polyethylene from the viewpoint of improving flexibility). On the other hand, from the viewpoint of improving the electrolyte resistance of the base layer 11, it is preferable that the base layer 11 contains polypropylene or acid-modified polypropylene alone as the resin.

[0064] In the non-permeable gas venting film 1 of this disclosure, from the viewpoint of enabling the base layer 11 to function suitably as a support (for example, from the viewpoint of suitably adhering the non-permeable gas venting film 1 to the exterior material 3), it is preferable that the base layer 11 has excellent heat resistance.

[0065] Because the base layer 11 has excellent heat resistance, the melting peak temperature of the resin constituting the base layer 11 is preferably 100°C or higher, more preferably 120°C or higher, and even more preferably 140°C or higher. The upper limit of the melting peak temperature of the resin constituting the base layer 11 can be, for example, 300°C or lower.

[0066] In this disclosure, the method for measuring the melting peak temperature of the resin is as follows:

[0067] <Measurement of melting peak temperature> For each resin, the melting peak temperature is measured in accordance with the provisions of JIS K7121:2012 (Method for Measuring Transition Temperature of Plastics (Supplement 1 to JIS K7121:1987)). The measurement is performed using a differential scanning calorimeter (e.g., DSC, differential scanning calorimeter Q200 manufactured by T.A. Instruments). The sample is held at -50°C for 15 minutes, then heated from -50°C to 210°C at a heating rate of 10°C / min, and the first melting peak temperature P (°C) is measured, followed by holding at 210°C for 10 minutes. Next, the temperature is cooled from 210°C to -50°C at a cooling rate of 10°C / min and held for 15 minutes. Furthermore, the temperature is heated from -50°C to 210°C at a heating rate of 10°C / min, and the second melting peak temperature Q (°C) is measured. The nitrogen gas flow rate is 50 ml / min. By following the above procedure, the melting peak temperature P (°C) measured in the first measurement and the melting peak temperature Q (°C) measured in the second measurement are determined, and the melting peak temperature measured in the first measurement is taken as the melting peak temperature. When measuring samples with high melting peak temperatures, measurements may be taken in the range from -50°C to 500°C at the same heating rate.

[0068] Furthermore, from the viewpoint of more favorably achieving the effects of this disclosure, the thickness of the substrate layer 11 is preferably about 10 μm or more, more preferably about 20 μm or more, even more preferably about 30 μm or more, and also preferably about 300 μm or less, more preferably about 200 μm or less, even more preferably about 150 μm or less, with preferred ranges being about 10 to 300 μm, about 10 to 200 μm, about 10 to 150 μm, about 20 to 300 μm, about 20 to 200 μm, about 20 to 150 μm, about 30 to 300 μm, about 30 to 200 μm, and about 30 to 150 μm.

[0069] In this disclosure, from the viewpoint of more favorably exhibiting the effects of this disclosure, the ratio of the thickness of the substrate layer 11 to the total thickness (100%) of the non-permeable gas venting film 1 is preferably about 5% or more, more preferably about 10% or more, even more preferably about 15% or more, and also preferably about 95% or less, more preferably about 90% or less, even more preferably about 85% or less, and preferred ranges are about 5-95%, about 5-90%, about 5-85%, about 10-95%, about 10-90%, about 10-85%, about 15-95%, about 15-90%, and about 15-85%.

[0070] [Adhesive layer 12] In the non-permeable gas venting film 1 of this disclosure, the adhesive layer 12 is a layer that provides adhesion to the exterior material 3 of the energy storage device 10. Specifically, in the first embodiment, it provides adhesion to the surface of the exterior material 3, and in the second embodiment, it provides adhesion (preferably heat-sealable) to the welded portion of the exterior material 3.

[0071] As described above, in the first embodiment, when the non-permeable gas venting film 1 is applied to the exterior material 3 made of a metal can, as shown in Figures 1 to 4, the adhesive layer 12 of the non-permeable gas venting film 1 can be made of a resin that is impermeable and permeable to gas, and that has adhesive properties (preferably heat-sealable) to the metal constituting the outer surface of the exterior material 3. Also, in the first embodiment, when the non-permeable gas venting film 1 is applied to the outer surface of the exterior material 3 made of the laminated film, as shown in Figures 5 to 9, the adhesive layer 12 of the non-permeable gas venting film 1 can be made of a resin that is impermeable and permeable to gas, and that has adhesive properties (preferably heat-sealable) to the resin constituting the outer surface of the exterior material.

[0072] Furthermore, as described above, in the second embodiment, when the non-permeable gas venting film 1 is applied to an exterior material 3 made of a laminated film (a laminate comprising at least a base layer 31, a barrier layer 33, and a heat-fusible resin layer 35 in this order), as shown in Figures 10-12 and 14-19, the non-permeable gas venting film 1 can be made of a resin that is non-permeable and gas-permeable, and that has adhesion (preferably heat-fusible) to the resin constituting the innermost layer of the exterior material (i.e., the heat-fusible resin layer 35 of the exterior material 3, which will be described later).

[0073] The adhesive layer 12 is preferably formed from a resin that has low water vapor permeability and high carbon dioxide permeability.

[0074] The adhesive layer 12 is preferably a layer containing a polyolefin resin (i.e., having a polyolefin skeleton), and more preferably a layer formed of a polyolefin resin. Examples of polyolefin resins include polyethylene and polypropylene. The polyolefin resin may also be an acid-modified resin (acid-modified polyolefin). As for acid-modified polyolefins, there are no particular limitations as long as they are acid-modified polyolefins, but preferably examples include polyolefins graft-modified with an unsaturated carboxylic acid or its anhydride, such as acid-modified polyethylene and acid-modified polypropylene.

[0075] In the adhesive layer 12, the specific examples of polyolefin resins are the same as those exemplified in the base layer 11, such as polyolefins and acid-modified polyolefins, so the above examples will be used by reference.

[0076] The adhesive layer 12 may be formed by a single resin component or by a blended polymer combining two or more resin components. From the viewpoint of film-forming properties of the adhesive layer 12, it is preferable to form it by a blended polymer combining two or more resin components. When a blended polymer is used, it is preferable that the adhesive layer 12 has acid-modified polypropylene as the main component (50% by mass or more) and 50% by mass or less of other resins (preferably polyethylene from the viewpoint of improving flexibility). On the other hand, from the viewpoint of improving the electrolyte resistance of the adhesive layer 12, it is preferable that the adhesive layer 12 contains polypropylene or acid-modified polypropylene alone as the resin.

[0077] Furthermore, the adhesive layer 12 may contain an adhesive component. Examples of adhesive components include elastomers.

[0078] The elastomer is not particularly limited as long as it exhibits adhesive properties when compounded with polyolefin, for example, an elastomer composed of a thermoplastic resin (thermoplastic elastomer) is preferred.

[0079] Preferred elastomers include styrene-based elastomers, olefin-based elastomers, acrylic-based elastomers, silicone-based elastomers, urethane-based elastomers, polyester-based elastomers, polyamide-based elastomers, and rubber-based elastomers. The elastomer may be used individually or in combination of two or more types.

[0080] There are no particular limitations on the type of styrene-based elastomer, but specific examples include styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, and styrene-ethylene-propylene-styrene block copolymer.

[0081] Examples of olefin-based elastomers include copolymers of α-olefins having 2 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene, and 4-methylpentene. For example, ethylene-propylene copolymer (EPR) and ethylene-propylene-diene copolymer (EPDM) are preferred. Also, copolymers of α-olefins with non-conjugated dienes having 2 to 20 carbon atoms, such as dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylenenorbornene, ethylidenenorbornene, butadiene, and isoprene, are also used. Furthermore, carboxylated nitrile rubber obtained by copolymerizing butadiene-acrylonitrile copolymer with methacrylic acid is also an example.

[0082] Acrylic elastomers are mainly composed of acrylic acid esters, and specifically, ethyl acrylate, butyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, etc., are preferably used. In addition, glycidyl methacrylate, allyl glycidyl ether, etc., can be used as crosslinking monomers. Furthermore, copolymers with acrylonitrile or ethylene can also be used. Specifically, examples include acrylonitrile-butyl acrylate copolymer, acrylonitrile-butyl acrylate-ethyl acrylate copolymer, and acrylonitrile-butyl acrylate-glycidyl methacrylate copolymer.

[0083] Silicone-based elastomers primarily consist of organopolysiloxanes, and include polydimethylsiloxane-based, polymethylphenylsiloxane-based, and polydiphenylsiloxane-based elastomers.

[0084] Urethane elastomers consist of structural units of a hard segment made of low molecular weight ethylene glycol and diisocyanate, and a soft segment made of high molecular weight (long-chain) diol and diisocyanate. Examples of high molecular weight (long-chain) diols include polypropylene glycol, polytetramethylene oxide, poly(1,4-butylene adipate), poly(ethylene-1,4-butylene adipate), polycaprolactone, poly(1,6-hexylene carbonate), and poly(1,6-hexylene neopentylene adipate).

[0085] Polyester elastomers are obtained by polycondensation of a dicarboxylic acid or its derivative with a diol compound or its derivative. Specific examples of dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid, as well as aromatic dicarboxylic acids in which the hydrogen atoms of the aromatic kernel are substituted with methyl, ethyl, or phenyl groups, aliphatic dicarboxylic acids having 2 to 20 carbon atoms such as adipic acid, sebacic acid, and dodecanedicarboxylic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. These compounds can be used individually or in combination of two or more.

[0086] Specific examples of diol compounds include aliphatic and alicyclic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol, and 1,4-cyclohexanediol. Furthermore, examples include bisphenol A, bis-(4-hydroxyphenyl)-methane, bis-(4-hydroxy-3-methylphenyl)-propane, and resorcinol. These compounds can be used individually or in combination of two or more.

[0087] Examples of polyamide-based elastomers include block copolymers in which polyamide is the hard segment component and polybutadiene, butadiene-acrylonitrile copolymer, styrene-butadiene copolymer, polyisoprene, ethylene-propylene copolymer, polyether, polyester, polybutadiene, polycarbonate, polyacrylate, polymethacrylate, polyurethane, or silicone rubber are the soft segment components.

[0088] Examples of rubber-based elastomers include polyisobutylene.

[0089] Among elastomers, styrene-based elastomers and olefin-based elastomers are preferred, with styrene-based elastomers being particularly preferred.

[0090] The proportion of elastomer contained in the adhesive layer 12 is not particularly limited, but is preferably about 50% by mass or less, more preferably about 10 to 50% by mass, and even more preferably about 10 to 40% by mass.

[0091] Because the adhesive layer 12 has excellent heat-sealing properties, the melting peak temperature of the resin constituting the adhesive layer 12 is preferably 300°C or lower, more preferably 200°C or lower, and even more preferably 160°C or lower, and also preferably 100°C or higher, more preferably 120°C or higher, and even more preferably 140°C or higher. Preferred ranges are approximately 100-300°C, 100-200°C, 100-160°C, 120-300°C, 120-200°C, 120-160°C, 140-300°C, 140-200°C, and 140-160°C.

[0092] Furthermore, from the viewpoint of more favorably achieving the effects of this disclosure, the thickness of the adhesive layer 12 is preferably about 10 μm or more, more preferably about 20 μm or more, even more preferably about 30 μm or more, and also preferably about 300 μm or less, more preferably about 200 μm or less, even more preferably about 150 μm or less, with preferred ranges being approximately 10-300 μm, 10-200 μm, 10-150 μm, 20-300 μm, 20-200 μm, 20-150 μm, 30-300 μm, 30-200 μm, and 30-150 μm.

[0093] In this disclosure, from the viewpoint of more favorably exhibiting the effects of this disclosure, the ratio of the thickness of the adhesive layer 12 to the total thickness (100%) of the non-permeable gas venting film 1 is preferably about 5% or more, more preferably about 10% or more, even more preferably about 15% or more, and also preferably about 95% or less, more preferably about 90% or less, even more preferably about 85% or less, and preferred ranges are about 5-95%, about 5-90%, about 5-85%, about 10-95%, about 10-90%, about 10-85%, about 15-95%, about 15-90%, and about 15-85%.

[0094] [Resin layer (resin layer 13, resin layer 14, etc.)] The non-permeable gas venting film 1 of this disclosure has a multilayer structure, and in addition to the base layer 11 and adhesive layer 12, it may further include at least one resin layer on the base layer 11 side of the adhesive layer 12. The resin layer is laminated between the adhesive layer 12 and the base layer 11, on the side of the base layer 11 opposite to the adhesive layer 12. The resin layer is at least one layer, and for example, Figure 21 shows a laminated configuration with one resin layer 13, and Figure 22 shows a laminated configuration with two resin layers, resin layer 13 and resin layer 14.

[0095] The resin layer is preferably formed from a resin that has low water vapor permeability and high carbon dioxide permeability.

[0096] The resin layer is preferably a layer containing a polyolefin resin (i.e., having a polyolefin skeleton), and more preferably a layer formed of a polyolefin resin. Examples of polyolefin resins include polyolefins such as polyethylene and polypropylene. The polyolefin resin may also be an acid-modified resin (acid-modified polyolefin). There are no particular limitations on acid-modified polyolefins, but preferred examples include polyolefins graft-modified with unsaturated carboxylic acids or their anhydrides, such as acid-modified polyethylene and acid-modified polypropylene.

[0097] In the resin layer, specific examples of polyolefin resins are the same as those exemplified in the base layer 11, such as polyolefins and acid-modified polyolefins, so the above examples will be used by reference. Furthermore, the resin layer may also contain an adhesive component, similar to the adhesive layer 12. Examples of adhesive components include elastomers, and specific examples are the same as those exemplified in the adhesive layer 12, so the above description will be used by reference.

[0098] The melting peak temperature of the resin constituting the resin layer is preferably 350°C or lower, more preferably 300°C or lower, even more preferably 250°C or lower, and also preferably 100°C or higher, more preferably 120°C or higher, and even more preferably 140°C or higher.

[0099] Furthermore, if the non-permeable gas venting film 1 of this disclosure includes a resin layer, from the viewpoint of more favorably achieving the effects of this disclosure, the thickness of each resin layer is preferably about 10 μm or more, more preferably about 20 μm or more, even more preferably about 30 μm or more, and also preferably about 500 μm or less, more preferably about 300 μm or less, and even more preferably about 200 μm or less.

[0100] In this disclosure, when the non-permeable gas venting film 1 of this disclosure comprises a resin layer, from the viewpoint of more favorably exhibiting the effects of this disclosure, the ratio of the thickness of each resin layer to the total thickness (100%) of the non-permeable gas venting film 1 is preferably about 5% or more, more preferably about 10% or more, even more preferably about 15% or more, and also preferably about 95% or less, more preferably about 90% or less, even more preferably about 85% or less, and preferred ranges are about 5-95%, about 5-90%, about 5-85%, about 10-95%, about 10-90%, about 10-85%, about 15-95%, about 15-90%, and about 15-85%.

[0101] From the viewpoint of more favorably exhibiting the effects of this disclosure, it is also preferable that the non-permeable gas venting film 1 substantially does not contain polyester, polyamide, polyurethane, polycarbonate, polyvinyl alcohol, vinyl fluoride resin, AS resin, or polyacetal. Substantially not containing these resins means that the total proportion of these resins in the non-permeable gas venting film 1 is 5% by mass or less, more preferably 1% by mass or less, and more preferably 0% by mass. From the viewpoint of more favorably exhibiting the effects of this disclosure, the proportion of polyolefin resin in the resin constituting the non-permeable gas venting film 1 is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 100% by mass.

[0102] Of the layers constituting the non-permeable gas venting film 1 of this disclosure, at least one layer may contain, in addition to the resin, additives such as colorants like pigments, fillers, and lubricants.

[0103] [Exterior material 3] Examples of exterior materials 3 for the energy storage device 10 include metal cans and laminated films. For example, Figures 1 and 2 illustrate an embodiment in which the exterior material 3 of the energy storage device 10 is made of a rectangular metal can. Figures 3 and 4 illustrate an embodiment in which the exterior material 3 of the energy storage device 10 is made of a cylindrical metal can. Figures 5 to 12 and 14 to 19 illustrate an embodiment in which the exterior material 3 of the energy storage device 10 is made of a laminated film (for example, a laminate comprising at least a base layer 31, a barrier layer 33, and a heat-fusible resin layer 35 in this order).

[0104] In addition to the exterior material 3, at least terminals 2 are provided on the outer surface of the energy storage device 10. The terminals 2 are components that electrically connect the inside and outside of the energy storage device 10 and allow electricity to be drawn from the energy storage device 10.

[0105] When the outer packaging is a metal can, the outer packaging is made of metal, and examples of such metals include stainless steel, aluminum alloy, and steel plate.

[0106] Furthermore, an exterior material 3 composed of a laminated film may have a laminated structure consisting of a laminate having at least a base layer 31, a barrier layer 33, and a heat-fusible resin layer 35 in that order. Figure 23 shows an example of the cross-sectional structure of the exterior material 3, in which a base layer 31, an adhesive layer 32 provided as needed, a barrier layer 33, an adhesive layer 34 provided as needed, and a heat-fusible resin layer 35 are laminated in that order. In the exterior material 3, the base layer 31 is the outer layer, and the heat-fusible resin layer 35 is the innermost layer. When assembling the energy storage device, the heat-fusible resin layers 35 located on the periphery of the energy storage device element 4 are brought into contact with each other and heat-fused to seal the energy storage device element 4, thereby sealing the energy storage device element 4. Figures 5 to 12 and 14 to 19 show an energy storage device 10 using an embossed type exterior material 3 formed by embossing, but the exterior material 3 may be an unformed pouch type. Note that pouch-type packaging includes three-sided seal, four-sided seal, and pillow-type packaging, but any type is acceptable.

[0107] The thickness of the laminate constituting the exterior material 3 is not particularly limited, but from the viewpoint of cost reduction and energy density improvement, the upper limit is preferably 190 μm or less, preferably about 180 μm or less, about 160 μm or less, about 155 μm or less, about 140 μm or less, about 130 μm or less, and about 120 μm or less. From the viewpoint of maintaining the function of the exterior material 3 in protecting the energy storage device element 4, the lower limit is preferably about 35 μm or more, about 45 μm or more, about 60 μm or more, and about 80 μm or more. For example, the preferred range is about 35 to 190 μm, about 35 to 180 μm, about 35 to 160 μm, and 35 to 15 Approx. 5μm, approx. 35~140μm, approx. 35~130μm, approx. 35~120μm, approx. 45~190μm, approx. 45~180μm, 45~160μm degree, about 45-155μm, about 45-140μm, about 45-130μm, about 45-120μm, about 60-190μm, about 60-180μm, Examples include approximately 60-160 μm, 60-155 μm, 60-140 μm, 60-130 μm, 60-120 μm, 80-190 μm, 80-180 μm, 80-160 μm, 80-155 μm, 80-140 μm, 80-130 μm, and 80-120 μm.

[0108] Furthermore, the non-permeable gas venting film 1 of this disclosure can also be suitably applied to exterior materials for all-solid-state batteries. The thickness of the laminate constituting the exterior material for all-solid-state batteries is not particularly limited, but from the viewpoint of cost reduction and energy density improvement, it is preferably about 10,000 μm or less, about 8,000 μm or less, and about 5,000 μm or less. From the viewpoint of maintaining the function of the exterior material for all-solid-state batteries, which is to protect the battery elements, it is preferably about 1 Examples of preferred ranges include 00 μm or more, approximately 150 μm or more, and approximately 200 μm or more. For example, preferred ranges include approximately 100 to 10000 μm, approximately 100 to 8000 μm, approximately 100 to 5000 μm, approximately 150 to 10000 μm, approximately 150 to 8000 μm, approximately 150 to 5000 μm, approximately 200 to 10000 μm, approximately 200 to 8000 μm, and approximately 200 to 5000 μm, with approximately 100 to 5000 μm being particularly preferred.

[0109] (Base material layer 31) In the exterior material 3, the base material layer 31 is a layer that functions as the base material of the exterior material and is the layer that forms the outermost layer.

[0110] The material forming the base layer 31 is not particularly limited, as long as it possesses insulating properties. Examples of materials for forming the base layer 31 include polyester, polyamide, epoxy, acrylic, fluororesin, polyurethane, silicon resin, phenol, polyetherimide, polyimide, and mixtures or copolymers thereof. Polyesters such as polyethylene terephthalate and polybutylene terephthalate have excellent electrolyte resistance and are less prone to whitening when exposed to electrolyte, making them suitable for use as a material for forming the base layer 31. Polyamide films also have excellent stretchability, which can prevent whitening due to resin cracking of the base layer 31 during molding, making them suitable for use as a material for forming the base layer 31.

[0111] The base layer 31 may be formed from a uniaxially or biaxially stretched resin film, or from an unstretched resin film. Among these, uniaxially or biaxially stretched resin films, and especially biaxially stretched resin films, are suitable for use as the base layer 31 because their heat resistance is improved by oriented crystallization.

[0112] Among these, nylon, polyester, and more preferably biaxially oriented nylon and biaxially oriented polyester are used as the resin film forming the base layer 31. Furthermore, since all-solid-state batteries are often sealed at high temperatures of 200°C or higher to achieve a service temperature of 150°C or higher, biaxially oriented polyester is the most suitable.

[0113] The base layer 31 can also be constructed by laminating resin films of different materials to improve pinhole resistance and insulation when used as packaging for energy storage devices. Specifically, examples include a multilayer structure in which polyester film and nylon film are laminated, or a multilayer structure in which biaxially oriented polyester and biaxially oriented nylon are laminated. When the base layer 31 is a multilayer structure, each resin film may be bonded via an adhesive, or it may be laminated directly without an adhesive. When bonding without an adhesive, examples include bonding in a thermally molten state such as co-extrusion, sand lamination, or thermal lamination. For the above high-temperature sealing, it is desirable that at least the outermost layer be biaxially oriented polyester.

[0114] Furthermore, the base layer 31 may be made friction-reducing to improve moldability. When the base layer 31 is made friction-reducing, there are no particular restrictions on the coefficient of friction of its surface, but for example, it may be 1.0 or less. Examples of methods for making the base layer 31 friction-reducing include mat treatment, formation of a thin film layer of a slip agent, and combinations thereof.

[0115] The thickness of the substrate layer 31 can be, for example, about 10 to 50 μm, preferably about 15 to 30 μm.

[0116] (Adhesive layer 32) In the exterior material 3, the adhesive layer 32 is a layer that is placed on the base material layer 31 as needed in order to provide adhesion to the base material layer 31. That is, the adhesive layer 32 is provided between the base material layer 31 and the barrier layer 33.

[0117] The adhesive layer 32 is formed by an adhesive capable of bonding the base layer 31 and the barrier layer 33. The adhesive used to form the adhesive layer 32 may be a two-component curing adhesive or a one-component curing adhesive. Furthermore, the bonding mechanism of the adhesive used to form the adhesive layer 32 is not particularly limited and may be a chemical reaction type, solvent evaporation type, thermal melting type, hot pressure type, etc.

[0118] As for the resin component of the adhesive that can be used to form the adhesive layer 32, from the viewpoint of having excellent ductility, durability under high humidity conditions, yellowing suppression effect, and heat degradation suppression effect during heat sealing, and effectively suppressing the occurrence of delamination by suppressing the decrease in laminate strength between the base layer 31 and the barrier layer 33, two-component curable polyurethane adhesives; polyamide, polyester, or blended resins of these with modified polyolefins are preferred.

[0119] Furthermore, the adhesive layer 32 may be multilayered with different adhesive components. When the adhesive layer 32 is multilayered with different adhesive components, from the viewpoint of improving the lamination strength between the base material layer 31 and the barrier layer 33, it is preferable to select a resin with excellent adhesion to the base material layer 31 as the adhesive component arranged on the base material layer 31 side, and an adhesive component with excellent adhesion to the barrier layer 33 as the adhesive component arranged on the barrier layer 33 side. Specifically, when the adhesive layer 32 is multilayered with different adhesive components, preferred adhesive components arranged on the barrier layer 33 side include acid-modified polyolefins, metal-modified polyolefins, mixed resins of polyester and acid-modified polyolefins, and resins containing copolymerized polyesters.

[0120] The thickness of the adhesive layer 32 can be, for example, about 2 to 50 μm, preferably about 3 to 25 μm.

[0121] (Barrier layer 33) In the exterior material, the barrier layer 33 is a layer that not only improves the strength of the exterior material but also has the function of preventing water vapor, oxygen, light, etc. from entering the inside of the energy storage device. The barrier layer 33 is preferably a metal layer, that is, a layer made of metal. Specifically, examples of metals that make up the barrier layer 33 include aluminum, stainless steel, and titanium, with aluminum being preferred. The barrier layer 33 can be formed from, for example, metal foil, metal vapor-deposited film, inorganic oxide vapor-deposited film, carbon-containing inorganic oxide vapor-deposited film, or a film provided with these vapor-deposited films, and it is preferably formed from metal foil, and more preferably from aluminum foil. From the viewpoint of preventing wrinkles and pinholes from occurring in the barrier layer 33 during the manufacturing of the exterior material, it is more preferable that the barrier layer be formed from soft aluminum foil, such as annealed aluminum (JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, JIS H4000:2014 A8079P-O).

[0122] Regarding the thickness of the barrier layer 33, from the viewpoint of making the exterior material thinner while also making it difficult for pinholes to occur during molding, it is preferably about 10 to 200 μm, and more preferably about 20 to 100 μm.

[0123] Furthermore, it is preferable that at least one surface, preferably both surfaces, of the barrier layer 33 be chemically treated to stabilize adhesion and prevent dissolution and corrosion. Here, chemical treatment refers to a treatment that forms a corrosion-resistant film on the surface of the barrier layer.

[0124] (adhesive layer 34) In the exterior material 3, the adhesive layer 34 is a layer provided between the barrier layer 33 and the heat-fusible resin layer 35 as needed, in order to firmly bond the heat-fusible resin layer 35.

[0125] The adhesive layer 34 is formed by an adhesive capable of bonding the barrier layer 33 and the heat-fusible resin layer 35. The composition of the adhesive used to form the adhesive layer is not particularly limited, but examples include adhesives consisting of a polyester polyol compound and an alicyclic isocyanate compound.

[0126] The thickness of the adhesive layer 34 can be, for example, about 1 to 40 μm, preferably about 2 to 30 μm.

[0127] (Thermal adhesive resin layer 35) In the exterior material 3, the heat-sealable resin layer 35 is the innermost layer, and during the assembly of the energy storage device, the heat-sealable resin layers heat-seal each other to seal the energy storage device elements.

[0128] The resin components used in the heat-fusible resin layer 35 are not particularly limited, as long as they are heat-fusible. For example, in exterior materials, polyolefins and cyclic polyolefins are generally used.

[0129] Specifically, the polyolefins include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymer of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymer of propylene and ethylene); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferred.

[0130] The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of olefins that are constituent monomers of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, isoprene, and the like. Examples of cyclic monomers that are constituent monomers of the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, norbornadiene, etc. Among these polyolefins, cyclic alkenes are preferred, and norbornene is more preferred. Styrene can also be used as a constituent monomer.

[0131] Among these resin components, preferred are crystalline or amorphous polyolefins, cyclic polyolefins, and blends thereof; more preferably, polyethylene, polypropylene, copolymers of ethylene and norbornene, and blends of two or more of these.

[0132] The heat-fusible resin layer 35 may be formed by a single resin component, or by a blended polymer combining two or more resin components. Furthermore, the heat-fusible resin layer 35 may be formed as a single layer, or it may be formed as two or more layers made of the same or different resin components.

[0133] Furthermore, the thickness of the heat-sealable resin layer 35 is not particularly limited, but is preferably about 2 to 2000 μm, more preferably about 5 to 1000 μm, and more preferably about 10 to 500 μm.

[0134] As described above, it is more desirable that the melting peak temperature of the heat-fusible resin layer 35 of the exterior material 3 be above the lower limit of the melting peak temperature of the base layer 11, which is 100°C. The melting peak temperature of the heat-fusible resin layer 35 is preferably 150 to 250°C, more preferably 180 to 270°C, even more preferably 200 to 270°C, and even more preferably 200 to 250°C. As described above, from the viewpoint of exhibiting the effects of this disclosure more favorably, it is preferable that the melting peak temperature of the base layer 11 be 5°C or more lower than the melting peak temperature of the heat-fusible resin layer 35 of the exterior material 3, more preferably 10°C or more lower, and even more preferably 15°C or more lower.

[0135] Furthermore, examples of resins included in the heat-sealable resin layer 35 of the exterior material for all-solid-state batteries include polyolefins such as polypropylene and polyethylene, acid-modified polyolefins such as acid-modified polypropylene and acid-modified polyethylene, and polybutylene terephthalate. Among these, polybutylene terephthalate has excellent heat resistance, so in the exterior material for all-solid-state batteries, the heat-sealable resin layer 35 is preferably formed from a polybutylene terephthalate film. In addition, because the heat-sealable resin layer 35 is formed from a polybutylene terephthalate film, it also has excellent adhesion to the base layer 11 of the adhesive film of this disclosure. The polybutylene terephthalate film forming the heat-sealable resin layer 35 may be formed by laminating a pre-prepared polybutylene terephthalate film with the adhesive layer 34, or the resin forming the polybutylene terephthalate film may be melt-extruded to form a film and then laminated with the adhesive layer 34.

[0136] The polybutylene terephthalate film may be an stretched polybutylene terephthalate film or an unstretched polybutylene terephthalate film, and an unstretched polybutylene terephthalate film is preferred.

[0137] The polybutylene terephthalate film preferably contains an elastomer in addition to polybutylene terephthalate. The elastomer plays a role in enhancing the flexibility of the polybutylene terephthalate film while ensuring its durability in high-temperature environments. Preferred elastomers include at least one thermoplastic elastomer selected from polyester, polyamide, polyurethane, polyolefin, polystyrene, and polyether types, or thermoplastic elastomers that are copolymers thereof. In the polybutylene terephthalate film, there are no particular restrictions on the elastomer content, as long as it is sufficient to enhance the flexibility of the polybutylene terephthalate film while ensuring its durability in high-temperature environments. For example, it is about 0.1% by mass or more, preferably about 0.5% by mass or more, more preferably about 1.0% by mass or more, and even more preferably about 3.0% by mass or more. Alternatively, the content may be about 10.0% by mass or less, about 8.0% by mass or less, or about 5.0% by mass or less. Preferred ranges for the content include approximately 0.1 to 10.0 mass%, 0.1 to 8.0 mass%, 0.1 to 5.0 mass%, 0.5 to 10.0 mass%, 0.5 to 8.0 mass%, 0.5 to 5.0 mass%, 1.0 to 10.0 mass%, 1.0 to 8.0 mass%, 1.0 to 5.0 mass%, 3.0 to 10.0 mass%, 3.0 to 8.0 mass%, and 3.0 to 5.0 mass%.

[0138] The heat-sealable resin layer 35 may be formed as a single layer, or it may be formed as two or more layers of the same or different resins. When the heat-sealable resin layer 35 is formed as two or more layers, at least one layer is preferably made of polybutylene terephthalate film, and the polybutylene terephthalate film is preferably the innermost layer of the exterior material for the all-solid-state battery. Furthermore, the layer that adheres to the adhesive layer 34 is preferably made of polybutylene terephthalate film. When the heat-sealable resin layer 35 is formed as two or more layers, the layer not made of polybutylene terephthalate film may be made of, for example, polyolefins such as polypropylene and polyethylene, or acid-modified polyolefins such as acid-modified polypropylene and acid-modified polyethylene. However, since polyolefins and acid-modified polyolefins have lower durability in high-temperature environments compared to polybutylene terephthalate, it is preferable that the heat-sealable resin layer 35 is composed solely of polybutylene terephthalate film.

[0139] Energy storage devices The energy storage device 10 of this disclosure is an energy storage device having a structure in which an energy storage device element 4 is housed in a package formed of an outer material 3.

[0140] In the first embodiment, a water-impermeable gas-venting film 1 is adhered to the surface of the exterior material 3 so as to block the communication portion H provided in the exterior material 3 of the energy storage device 10, and gas generated inside the energy storage device 10 is discharged from the communication portion H. The diameter of the cross-section of the communication portion H (the diameter of the cross-section of the gas flow path) can be appropriately set according to the size of the energy storage device 10, etc.

[0141] In the second embodiment, a water-impermeable gas venting film 1 is positioned between the welded portions of the exterior material 3 of the energy storage device 10, and gas generated inside the energy storage device 10 is discharged through the water-impermeable gas venting film 1 positioned between the welded portions. The diameter of the cross-section of the portion positioned between the welded portions (the diameter of the cross-section of the gas flow path) can be appropriately set according to the size of the energy storage device 10.

[0142] The non-permeable gas venting film 1 and exterior material 3 are as described above.

[0143] For example, the outer packaging material 3, which is made of a laminated film, is composed of a laminate comprising, at least from the outside, a base layer 31, a barrier layer 33, and a heat-sealable resin layer 35 in that order, and the energy storage device element 4 is housed in the packaging by heat-sealing the heat-sealable resin layers 35 of the outer packaging material 3 together. In a second embodiment, for example, a non-permeable gas venting film 1 is placed between the heat-sealable resin layers 35 at the position where the heat-sealable resin layers 35 are welded (heat-sealed). The energy storage device 10 of this disclosure can be manufactured by a method that includes a housing step in which the energy storage device element 4 is housed in the packaging by placing a non-permeable gas venting film 1 between the heat-sealable resin layers 35 at the position where the heat-sealable resin layers 35 of the outer packaging material 3 are heat-sealed, and then heat-sealing the heat-sealable resin layers 35 via the non-permeable gas venting film 1. At this time, the adhesive layer 12 of the non-permeable gas venting film is bonded to the welded portion of the exterior material 3, allowing gas to permeate in the thickness direction of the non-permeable gas venting film and be discharged. A particularly preferred configuration is shown in Figures 10 to 12 and Figures 14 to 19, in which the non-permeable gas venting film 1 is folded over and sandwiched between the welded portions of the exterior material 3 of the energy storage device 10.

[0144] The energy storage device 10 of this disclosure can be an energy storage device such as a battery (including capacitors, capacitors, etc.). The energy storage device 10 of this disclosure may be either a primary battery or a secondary battery, but is preferably a secondary battery. The type of secondary battery is not particularly limited and examples include lithium-ion batteries, lithium-ion polymer batteries, all-solid-state batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, capacitors, capacitors, etc. Among these secondary batteries, lithium-ion batteries and lithium-ion polymer batteries are preferred. [Examples]

[0145] 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.

[0146] <Manufacturing of adhesive films> Example 1 Using an extruder and a T-die casting apparatus, polyarylate nonwoven fabric (basis weight 14 g / m²) is used as the base layer. 2 On both sides of the material, maleic anhydride-modified polypropylene is extruded as an adhesive layer, resulting in a maleic anhydride-modified polypropylene (thickness 42 μm) / polyarylate nonwoven fabric (basis weight 14 g / m²). 2 A water-permeable gas-venting film (total thickness 100 μm) was obtained, consisting of three layers laminated in this order: ) / maleic anhydride-modified polypropylene (thickness 42 μm).

[0147] Comparative Example 1 Using an extruder and a T-die casting apparatus, maleic anhydride-modified polypropylene was extruded onto both sides of a polyethylene naphthalate film (12 μm thick), resulting in a three-layer non-permeable gas-venting film (total thickness 100 μm) in which maleic anhydride-modified polypropylene (44 μm thick) / polyethylene naphthalate film (12 μm thick) / maleic anhydride-modified polypropylene (44 μm thick) were laminated in this order.

[0148] Example 2 Using an extruder and a T-die casting apparatus, polypropylene was extruded onto one side of an unstretched polypropylene film (thickness 95 μm) as the base layer, and maleic anhydride-modified polypropylene was extruded onto the other side as the adhesive layer, resulting in a three-layer non-permeable gas-venting film (total thickness 200 μm) in which polypropylene (thickness 52.5 μm) / unstretched polypropylene film (thickness 95 μm) / maleic anhydride-modified polypropylene (thickness 52.5 μm) were laminated in this order.

[0149] Example 3 Using an extruder and a T-die casting apparatus, polypropylene was extruded onto one side of an unstretched polypropylene film (thickness 50 μm) as a base layer, and maleic anhydride-modified polypropylene was extruded onto the other side, resulting in a three-layer non-permeable gas-venting film (total thickness 200 μm) in which polypropylene (thickness 50 μm) / unstretched polypropylene film (thickness 50 μm) / maleic anhydride-modified polypropylene (thickness 100 μm) were laminated in this order.

[0150] Example 4 Using an extruder and a T-die casting apparatus, maleic anhydride-modified polypropylene as the adhesive layer and polypropylene as the base layer were co-extruded to obtain a two-layer non-permeable venting film (total thickness 80 μm) consisting of maleic anhydride-modified polypropylene (thickness 40 μm) / polypropylene (thickness 40 μm) laminated together.

[0151] Example 5 Using an extruder and a T-die casting apparatus, maleic anhydride-modified polypropylene as the adhesive layer and polypropylene and polypropylene as the base layer were co-extruded to obtain a three-layer non-permeable gas-venting film (total thickness 80 μm) consisting of maleic anhydride-modified polypropylene (thickness 30 μm) / polypropylene (thickness 30 μm) / polypropylene (thickness 20 μm) laminated together.

[0152] For each film obtained in the examples and comparative examples, the water vapor permeability, oxygen permeability, and carbon dioxide permeability were measured by the following method. The results are shown in Table 1.

[0153] <Water vapor transmission rate> In accordance with the cup method specified in JIS Z 0208, water vapor transmission was measured in an environment of 60°C and 90% RH. An appropriate amount of anhydrous calcium chloride was placed in a screw-type cup (permeable area 60 mmφ), and a test specimen was cut to 75 mmφ with three 5 mmφ holes drilled 5 mm inside the outer circumference. This specimen was set in a jig, and the water vapor transmission was calculated after weighing the specimen at 24, 48, and 96 hours in the 60°C, 90% RH environment. The same test was performed on three or more samples, and the average value was taken as the water vapor transmission.

[0154] <Carbon dioxide transmission rate> The carbon dioxide transmission rate of the film was measured under the following conditions, in accordance with the test items specified in JIS K 7126-1:2006: gas transmission rate and gas transmission coefficient (differential pressure method). Detector: Gas chromatograph (thermal conductivity detector (TDC)) Gas: Carbon dioxide (CO2) (humidified atmosphere) Temperature and humidity: 60±2℃·50±5%RH Differential pressure: 1 atm (partial pressure at 60°C and 50% RH (gas: 68.52 cmHg, water vapor: 7.48 cmHg)) Transmission area: 15.2×10 -4 m 2 (Transmission part diameter φ4.4×10 -2 m) Number of tests: n=1 Measurement device: Differential pressure type gas / vapor permeability measuring device

[0155] <Oxygen permeability> Oxygen permeability was measured in accordance with JIS K7126-2:2006 (Plastics - Films and Sheets - Gas Permeability Test Methods - Part 2: Isobaric Method, Annex A: Test Method for Oxygen Gas Permeability by Electrolytic Sensor Method) under conditions of 40°C and 90% RH humidity using an oxygen gas permeability measuring device. The OXTRAN2 / 22 manufactured by MOCON, Inc., USA, was used as the oxygen gas permeability measuring device. The measurement was performed by placing the non-permeable gas-venting film inside the device so that its surface was in contact with oxygen gas, with a permeation area of ​​50 cm². 2 The measurements were performed under the following conditions. The above measurements were carried out using the following procedure. First, the apparatus was purged by supplying a carrier gas at a flow rate of 10 cc / min for more than 60 minutes. The carrier gas used was nitrogen gas containing approximately 5% hydrogen. The test gas was flowed into the apparatus, and after allowing 12 hours to be allowed to reach equilibrium, measurements were started under the above temperature and humidity conditions. The test gas used was dry oxygen containing at least 99.5% (by volume) of oxygen. At least three samples were measured under each condition, and the average of these measurements was taken as the oxygen permeability value for that condition. Note that "200<" in Table 1 refers to the measurement limit of the oxygen gas permeability measuring device, where the oxygen permeability is 200 cm⁻¹. 3 / (m 2 This means the value was greater than or equal to (24 hours atm).

[0156] [Table 1]

[0157] In Table 1, PPa represents maleic anhydride-modified polypropylene, PP represents polypropylene, PEN represents polyethylene naphthalate, and CPP represents unstretched polypropylene film.

[0158] The films of Examples 1-5 comprise maleic anhydride-modified polypropylene as an adhesive layer and polyarylate nonwoven fabric, unoriented polypropylene film, or polypropylene as a base layer. They exhibit very low water vapor permeability and high carbon dioxide and oxygen permeability, making them suitable for use as the water-permeable gas-venting films of the present invention.

[0159] As described above, this disclosure provides inventions in the following embodiments. Item 1. A non-permeable gas venting film, which is adhered to the surface of an exterior material of an energy storage device so as to seal a communication portion provided in the exterior material of the energy storage device, and is used to discharge gas generated inside the energy storage device from the communication portion, The aforementioned non-permeable gas venting film is composed of a laminate comprising at least a base layer and an adhesive layer. A non-permeable gas venting film wherein the adhesive layer of the non-permeable gas venting film is adhered to the surface of the exterior material of the energy storage device. Item 2. The non-permeable gas venting film according to Item 1, wherein the surface of the exterior material is made of metal or resin. Item 3. The non-permeable gas venting film according to item 1 or 2, wherein the communication portion is provided on the bottom surface, side surface, or welded portion of the energy storage device. Item 4. The non-permeable gas venting film according to any one of items 1 to 3, wherein the communicating portion is circular or slit-shaped. Item 5. A non-permeable venting film, which is positioned to be interposed between the welded portions of the exterior material of an energy storage device and used to vent gas generated inside the energy storage device, The aforementioned non-permeable gas venting film is composed of a laminate comprising at least a base layer and an adhesive layer. The adhesive layer of the non-permeable gas venting film is bonded to the welded portion of the exterior material. A non-permeable gas venting film through which the gas permeates in the thickness direction and is discharged. Item 6. The non-permeable gas venting film according to Item 5, wherein the non-permeable gas venting film is folded in a manner and sandwiched between the welded portions of the exterior material of the energy storage device. Item 7. The exterior material is composed of a laminate in which at least a base layer, a barrier layer, and a heat-fusible resin layer are laminated in this order. The non-permeable gas venting film according to claim 5 or 6, wherein the non-permeable gas venting film is interposed between the welded portions of the exterior material such that the heat-fusible resin layer and the adhesive layer of the non-permeable gas venting film are bonded together. Item 8. The welded portion of the exterior material is provided with a communication portion in which the surface of the non-permeable gas venting film is exposed. A non-permeable gas venting film according to any one of items 5 to 7, wherein the gas is discharged through the aforementioned communication portion. Item 9. The non-permeable gas venting film according to Item 8, wherein the connecting portion is circular or slit-shaped. Item 10. The non-permeable gas venting film according to any one of items 1 to 9, further comprising at least one resin layer on the substrate layer side of the adhesive layer. Item 11. The non-permeable gas venting film according to any one of items 1 to 10, wherein the non-permeable gas venting film is formed of a polyolefin resin. [Explanation of Symbols]

[0160] 1. Non-permeable gas venting film 2 terminals 3. Exterior materials 3a Peripheral edge of exterior material 4 Energy Storage Device Elements 10 Energy Storage Devices 11 Base material layer 12 Adhesive layer 13 Resin layer 14 resin layer 31 Base material layer 32 Adhesive layer 33 Barrier layer 34 Next layer 35. Heat-adhesive resin layer H Connecting part HS hot melt adhesive

Claims

1. A non-permeable gas venting film is used to seal a communication portion provided in the exterior material of an energy storage device, and is adhered to the surface of the exterior material, and to discharge gas generated inside the energy storage device through the communication portion, The aforementioned non-permeable gas-venting film has a water vapor transmission rate of 10 cc / m² / day or less when left standing for 48 hours in an environment of 60°C and 90% RH, a carbon dioxide transmission rate of 5000 cm³ / (m²・24h・atm) or more as measured in accordance with JIS K 7126-1:2006, and an oxygen transmission rate of 50 cm³ / (m²・24h・atm) or more as measured in accordance with JIS K 7126-2:2006. The aforementioned non-permeable gas venting film is composed of a laminate comprising at least a base layer and an adhesive layer. The ratio of the thickness of the adhesive layer to the total thickness (100%) of the non-permeable gas-venting film is 5% or more. A non-permeable gas venting film wherein the adhesive layer of the non-permeable gas venting film is adhered to the surface of the exterior material of the energy storage device.

2. The non-permeable gas venting film according to claim 1, wherein the surface of the exterior material is made of metal or resin.

3. The non-permeable gas venting film according to claim 1 or 2, wherein the communication portion is provided on the bottom surface, side surface, or welded portion of the energy storage device.

4. The non-permeable gas venting film according to claim 1 or 2, wherein the communicating portion is circular or slit-shaped.

5. A non-permeable gas venting film is positioned between the welded portions of the exterior material of a power storage device and used to vent gas generated inside the power storage device, The aforementioned non-permeable gas-venting film has a water vapor transmission rate of 10 cc / m² / day or less when left standing for 48 hours in an environment of 60°C and 90% RH, a carbon dioxide transmission rate of 5000 cm³ / (m²・24h・atm) or more as measured in accordance with JIS K 7126-1:2006, and an oxygen transmission rate of 50 cm³ / (m²・24h・atm) or more as measured in accordance with JIS K 7126-2:2006. The aforementioned non-permeable gas venting film is composed of a laminate comprising at least a base layer and an adhesive layer. The adhesive layer of the non-permeable gas venting film is bonded to the welded portion of the exterior material. A non-permeable gas venting film through which the gas permeates in the thickness direction and is discharged.

6. The non-permeable gas venting film according to claim 5, wherein the non-permeable gas venting film is folded in a folded shape and sandwiched between the welded portions of the exterior material of the energy storage device.

7. The exterior material is composed of a laminate in which at least a base layer, a barrier layer, and a heat-fusible resin layer are laminated in this order. The non-permeable gas venting film according to claim 5 or 6, wherein the non-permeable gas venting film is arranged such that the heat-sealable resin layer and the adhesive layer of the non-permeable gas venting film are bonded together at the welded portion of the non-permeable gas venting film, and the non-permeable gas venting film is interposed between the welded portions.

8. The welded portion of the exterior material is provided with a communication portion in which the surface of the non-permeable gas venting film is exposed. The non-permeable gas venting film according to claim 5 or 6, wherein the gas is discharged through the communication portion.

9. The non-permeable gas venting film according to claim 8, wherein the communication portion is circular or slit-shaped.

10. The non-permeable gas venting film according to claim 1 or 5, further comprising at least one resin layer on the substrate layer side of the adhesive layer.

11. The non-permeable gas venting film according to claim 1 or 5, wherein the non-permeable gas venting film is formed of a polyolefin resin.

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