Resin film for electricity storage device, and electricity storage device

Abstract

A resin film for an electricity storage device, the resin film comprising two or more layers including at least one layer (A) having a water absorbent content of 5% by mass or more and at least one layer (B) having a water absorbent content of less than 5% by mass.

Description

Technical Field

[0001] The present invention relates to a resin film for an electricity storage device and an electricity storage device. Background Art

[0002] Currently, various types of electricity storage devices are being developed, but in all electricity storage devices, an exterior component is an indispensable component in order to seal an electrode body such as an electrode, an electrolyte, etc. Conventionally, metal exterior components are often used as exterior components for electricity storage devices.

[0003] On the other hand, in recent years, with the high performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., various shapes, thinness, and lightness are required for power storage devices. Therefore, the metal power storage device exterior parts commonly used in the prior art have the disadvantages of being difficult to follow the diversification of shapes and also having limitations in terms of lightness.

[0004] Therefore, in the prior art, as an exterior component for a storage device that can be easily processed into a variety of shapes and can be made thinner and lighter, a film-like laminate obtained by stacking a base layer / barrier layer / adhesive layer / thermofusible resin layer in sequence has been proposed (for example, refer to Patent Document 1).

[0005] In such an exterior component for an electrical storage device, a recess is usually formed by cold forming, an electrode body such as an electrode and an electrolyte is arranged in the space formed by the recess, and a heat-fusible resin layer is heat-fused, thereby obtaining an electrical storage device in which the electrode body is accommodated inside the exterior component for an electrical storage device.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2008-287971. Summary of the invention

[0009] Problems to be solved by the invention

[0010] When water penetrates into the interior of the storage device, the performance of the storage device deteriorates, so when the film-like laminate is used as an exterior material, a barrier layer (e.g., made of metal foil) is provided to prevent water from penetrating from the outside of the barrier layer.

[0011] However, when the electric storage device element is sealed by heat-sealing the heat-fusible resin layer of the exterior material, since the end surface of the heat-fusible resin layer is exposed to the outside, there is a possibility that moisture may penetrate through the end surface of the heat-fusible resin layer.

[0012] Furthermore, if the heat-fusible resin layer of the exterior material absorbs water before the power storage device element is sealed with the exterior material, the water in the heat-fusible resin layer may penetrate into the power storage device element after the power storage device element is sealed.

[0013] In addition, some components used in power storage devices are required to have excellent insulation properties.

[0014] Under such circumstances, a main object of the present invention is to provide a resin film for an electricity storage device which has excellent insulation properties and suppresses the penetration of moisture into an electricity storage device element.

[0015] Technical solutions to the problem

[0016] The inventors of the present invention have conducted intensive research to solve the above-mentioned problems. As a result, it has been found that by configuring the resin film for a storage device with two or more layers, setting the content of the water absorbing agent in at least one of the two or more layers to 5% by mass or more, and setting the content of the water absorbing agent in at least one of the two or more layers to less than 5% by mass, it is possible to have excellent insulation and suppress the intrusion of water into the interior of the storage device element.

[0017] The present invention has been completed through further research based on these findings. That is, the present invention provides the technical solutions listed below.

[0018] A resin film for an electric storage device, wherein:

[0019] The resin film for a power storage device is composed of two or more layers.

[0020] The two or more layers include at least one layer A and at least one layer B, wherein the content of the water absorbing agent in the layer A is 5% by mass or more, and the content of the water absorbing agent in the layer B is less than 5% by mass.

[0021] Effects of the Invention

[0022] According to the present invention, it is possible to provide a resin film for an electricity storage device that has excellent insulation properties and suppresses the penetration of water into the interior of an electricity storage device element. In addition, according to the present invention, it is possible to provide an electricity storage device using this technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram showing an example of the cross-sectional structure of the resin film for an electricity storage device of the present invention.

[0024] Figure 2 It is a schematic diagram showing an example of the cross-sectional structure of the resin film for an electricity storage device of the present invention.

[0025] Figure 3It is a schematic diagram showing an example of the cross-sectional structure of the external packaging material for an electric storage device of the present invention.

[0026] Figure 4 It is a schematic diagram showing an example of the cross-sectional structure of the power storage device of the present invention.

[0027] Figure 5 It is a schematic diagram showing an example of the cross-sectional structure of the power storage device of the present invention.

[0028] Figure 6 It is a schematic diagram showing an example of the cross-sectional structure of the power storage device of the present invention.

[0029] Figure 7 It is a schematic diagram showing an example of the cross-sectional structure of the power storage device of the present invention.

[0030] Figure 8 It is a schematic diagram showing an example of the cross-sectional structure of the power storage device of the present invention.

[0031] Fig. 9 It is a schematic diagram showing an example of the cross-sectional structure of the power storage device of the present invention.

[0032] Fig.10 It is a schematic perspective view showing an example of the power storage device of the present invention.

[0033] Fig.11 It is a schematic diagram showing an example of the cross-sectional structure of the power storage device of the present invention. DETAILED DESCRIPTION

[0034] The resin film for a power storage device of the present invention is characterized in that it is composed of two or more layers, the two or more layers include at least one layer A and at least one layer B, the content of the water absorbing agent in the layer A is 5% by mass or more, and the content of the water absorbing agent in the layer B is less than 5% by mass. The resin film for a power storage device of the present invention has excellent insulation and can suppress the intrusion of water into the interior of the power storage device element by having such a structure.

[0035] Hereinafter, the resin film for a power storage device of the present invention will be described in detail. In the present invention, a numerical range represented by "to" means "above" or "below". For example, the description of 2 to 15 mm means 2 mm or more and 15 mm or less.

[0036] In addition, as a method for confirming the MD of a resin film for a storage device, there is a method for confirming the sea island structure by observing a cross section of a resin film for a storage device (for example, a cross section of an acid-modified polyolefin layer or a polyolefin layer) using an electron microscope. In this method, the direction parallel to the cross section with the largest average diameter of the shape of the island in the direction perpendicular to the thickness direction of the resin film for the storage device can be judged as MD. Specifically, for the cross section in the length direction of the resin film for the storage device and each cross section (a total of 10 cross sections) that changes the angle every 10 degrees from the direction parallel to the cross section in the length direction until the direction perpendicular to the cross section in the length direction, the sea island structure is confirmed. Then, in each cross section, the shape of each island is observed separately. Regarding the shape of each island, the straight line distance connecting the leftmost end in the direction perpendicular to the thickness direction of the resin film for the storage device and the rightmost end in the perpendicular direction is taken as the diameter y. In each cross section, the average value of the first 20 diameters y is calculated in the order of the size of the diameter y of the shape of the island. The direction parallel to the cross section with the largest average diameter y of the shape of the island is judged as MD. Furthermore, for example, the heat shrinkage rate of the resin film for a power storage device after being left in an environment at 150° C. for 2 minutes can be measured, and the one with a larger shrinkage rate can be determined as MD.

[0037] 1. Resin films for power storage devices

[0038] The resin film for a power storage device of the present invention is composed of two or more layers. The two or more layers include at least one layer A having a water absorbing agent content of 5% by mass or more and at least one layer B having a water absorbing agent content of less than 5% by mass. Figure 1 and Figure 2 In the embodiment, among the two or more layers, the layer A having a water absorbing agent content of 5% by mass or more is the first layer 11, and the layer B having a water absorbing agent content of less than 5% by mass is the second layer 12. Figure 2 Among them, the third layer 13 is layer B having a water absorbing agent content of less than 5% by mass.

[0039] The resin film for a storage device of the present invention has excellent insulation and can inhibit the penetration of moisture into the interior of the storage device element, so it can be preferably used as a resin film for a storage device. For example, the resin film 1 for a storage device is preferably used for the following purposes: 1) to be arranged between the storage device outer packaging material and the storage device element; 2) to be used as a heat-fusible resin layer of the storage device outer packaging material; 3) to be used as an adhesive layer between the barrier layer and the heat-fusible resin layer of the storage device outer packaging material; or, 4) to be used as an adhesive film for a metal terminal between a metal terminal electrically connected to an electrode of the storage device element and the storage device outer packaging material that seals the storage device element. Furthermore, the resin film for a storage device of the present invention can also be used in a manner of being interposed between heat-fusible resin layers at a position where the heat-fusible resin layers of the storage device outer packaging material are heat-fused to each other.

[0040] 1) In the application of being arranged between an outer packaging material for a storage device and a storage device element, the resin film 1 for a storage device of the present invention is as follows Figure 5 to Fig. 9 As shown in the schematic diagram of , it is arranged between the exterior material 3 of the power storage device 10 and the power storage device element 4 .

[0041] As described above, when moisture penetrates into the interior of the storage device element, the performance of the storage device will deteriorate, so a barrier layer (for example, composed of metal foil) is provided in the film-like outer packaging material. By providing a barrier layer, it is possible to suppress the penetration of moisture from the outside of the barrier layer. However, in the case of sealing the storage device element by heat-melting the heat-melting resin layer of the outer packaging material, since the end surface of the heat-melting resin layer is exposed to the outside, there is a possibility that moisture penetrates from the end surface of the heat-melting resin layer. In addition, in the case where the heat-melting resin layer of the outer packaging material absorbs water before the storage device element is sealed with the outer packaging material, there is also a possibility that the moisture in the heat-melting resin layer penetrates into the storage device element after the storage device element is sealed.

[0042] In this regard, by arranging the resin film 1 for the storage device of the present invention between the outer packaging material 3 and the storage device element 4 of the storage device 10, it is possible to effectively suppress the infiltration of moisture from the end of the heat-fusible resin layer of the outer packaging material and the infiltration of moisture contained in the heat-fusible resin layer of the outer packaging material into the storage device element. That is, since the resin film 1 for the storage device of the present invention contains a water absorbent, it is possible to suppress the moisture from reaching the storage device element 4 by allowing the resin film 1 for the storage device to absorb / retain the moisture infiltrated from the heat-fusible resin layer of the outer packaging material. Furthermore, since the resin film 1 for the storage device of the present invention has a layer B having a content of the water absorbent of less than 5% by mass, it is possible to ensure excellent insulation.

[0043] In addition, in the application of the resin film 1 for a storage device of the present invention as 2) a heat-fusible resin layer of an exterior material for a storage device, Figure 3 As shown in FIG. 1 , the resin film 1 for a storage device of the present invention is used as the heat-fusible resin layer 35 of the storage device exterior material 3 composed of a laminated body including at least a base layer 31, a barrier layer 33 and a heat-fusible resin layer 35 in this order. In addition, in the application of 3) using the resin film 1 for a storage device of the present invention as an adhesive layer between the barrier layer and the heat-fusible resin layer of the storage device exterior material, as Figure 3 As shown, the resin film 1 for a storage battery device of the present invention is used as the adhesive layer 34 of the storage battery device exterior material 3 composed of a laminate including at least a base layer 31, a barrier layer 33, an adhesive layer 34 and a thermally fusible resin layer 35 in this order.

[0044] As described above, when the heat-fusible resin layer of the external material is heat-fused to seal the storage device element, since the end surface of the heat-fusible resin layer is exposed to the outside, there is a possibility that moisture will penetrate from the end surface of the heat-fusible resin layer. In addition, if the heat-fusible resin layer of the external material absorbs water before the storage device element is sealed with the external material, there is also a possibility that the moisture in the heat-fusible resin layer will penetrate into the storage device element after the storage device element is sealed. The same is true for the adhesive layer located between the barrier layer and the heat-fusible resin layer.

[0045] In this regard, by using the resin film 1 for a storage device of the present invention as a heat-melting resin layer or an adhesive layer of the exterior material 3, it is possible to effectively suppress the infiltration of moisture from the end of the heat-melting resin layer of the exterior material and the infiltration of moisture contained in the heat-melting resin layer or the adhesive layer of the exterior material into the storage device element. That is, since the resin film 1 for a storage device of the present invention contains a water absorbent, it is possible to suppress the water from reaching the storage device element 4 by allowing the resin film 1 for a storage device to absorb / retain the water infiltrated from the heat-melting resin layer of the exterior material. Furthermore, since the resin film 1 for a storage device of the present invention has a layer B having a water absorbent content of less than 5% by mass, it is possible to ensure excellent insulation.

[0046] In addition, in the application of the resin film 1 for a storage device of the present invention as an adhesive film for a metal terminal between a metal terminal electrically connected to an electrode of a storage device element and an exterior material for a storage device that seals the storage device element, as in 4) Figure 4 As shown, the resin film 1 for an electric storage device is used as the adhesive film 21 for a metal terminal.

[0047] Since the end surface of the adhesive film for metal terminals is exposed to the outside, there is a possibility that moisture may penetrate from the end surface of the adhesive film for metal terminals. In addition, if the adhesive film for metal terminals absorbs water before the adhesive film for metal terminals is interposed between the metal terminal and the external packaging material for the storage device, there is also a possibility that the moisture in the adhesive film for metal terminals penetrates into the storage device element after the adhesive film for metal terminals is interposed between the metal terminal and the external packaging material for the storage device.

[0048] In this regard, by using the resin film 1 for a storage device of the present invention as an adhesive film for a metal terminal, it is possible to effectively suppress the infiltration of moisture from the end of the adhesive film for a metal terminal and the infiltration of moisture contained in the adhesive film for a metal terminal. That is, since the resin film 1 for a storage device of the present invention contains a water absorbent, it is possible to suppress the moisture from reaching the storage device element 4 by allowing the resin film 1 for a storage device to absorb / retain the moisture infiltrated from the adhesive film for a metal terminal. Furthermore, since the resin film 1 for a storage device of the present invention has a layer B having a content of the water absorbent of less than 5% by mass, it is possible to ensure excellent insulation.

[0049] In the present invention, the moisture to be absorbed is gaseous and / or liquid moisture. For example, when absorbed by a solid electrolyte type lithium ion battery, the moisture to be absorbed generates various off-gases.

[0050] The power storage device 10 is, for example, Figures 4 to 11 As shown in FIG. 1 , the storage device 10 has a structure in which the storage device element 4 is sealed with the outer packaging material 3. The metal terminal 2 protrudes to the outside of the outer packaging material 3. The metal terminal 2 is connected to the positive electrode and the negative electrode of the storage device element 4, respectively. An adhesive film 21 for the metal terminal is arranged between the metal terminal 2 and the outer packaging material 3 to improve the adhesion between the metal terminal 2 and the heat-fusible resin layer 35 of the outer packaging material. The storage device 10 is sealed in the following manner, that is, the storage device element 4 is covered with the outer packaging material 3 in such a manner that the flange portion of the outer packaging material 3 (the peripheral portion 3a of the outer packaging material 3) can be formed on the periphery of the storage device element 4, and the flange portion of the outer packaging material 3 is heat-sealed to seal. When the outer packaging material 3 is used to accommodate the storage device element 4, it is used in such a manner that the heat-fusible resin layer 35 of the outer packaging material 3 becomes the inner side (the surface in contact with the storage device element 4). When the resin film 1 for a storage device of the present invention is used as an adhesive film for a metal terminal, for example, the adhesive film for a metal terminal can be colored to arrange the adhesive film for a metal terminal between the metal terminal and the external material for a storage device with high positional accuracy. In addition, the layer constituting the surface of the metal terminal side of the adhesive film for a metal terminal is preferably composed of an acid-modified polyolefin. Thus, the adhesion of the adhesive film for a metal terminal to the metal terminal can be improved.

[0051] In addition, if Fig.10 and Fig.11 As shown in the figure, the electric storage device element 4 (in Fig.10 and Fig.11 The outer packaging material 3 is wound around (waist-wound) the outer packaging material 3 (in the rectangular parallelepiped shape), the heat-fusible resin layers are heat-sealed to form a heat-welded portion 70, and the cover 60 is arranged in a manner that the openings at both ends are respectively closed. The resin film 1 for the storage device of the present invention may be arranged between the cover 60 of the outer packaging material 3 of the storage device and the storage device element 4, or between the outer packaging material 3 on which the resin film for the storage device is wound and the storage device element 4. In this case, the cover 60 constitutes a part of the outer packaging material 3 for the storage device, and the resin film 1 for the storage device of the present invention is arranged between the outer packaging material 3 and the storage device element 4. In addition, the cover 60 may be composed of one component or a plurality of components.

[0052] In the above-mentioned application 1) of being arranged between the outer packaging material for a storage device and the storage device element, the resin film 1 for a storage device of the present invention may be located on the entire surface of the outer packaging material 3 on the storage device element 4 side (the heat-fusible resin layer 35 side) or on a portion of the surface on the storage device element 4 side (the heat-fusible resin layer 35 side). From the viewpoint of appropriately exerting the effects of the present invention, the resin film 1 for a storage device is preferably arranged between the outer packaging material 3 of the storage device 10 and the storage device element 4 in a manner such that the entire surface is located on the storage device element 4 side (the heat-fusible resin layer 35 side) of the outer packaging material 3 (see Figures 5 to 9 For example, you can Figure 5 As shown in the figure, only the resin film 1 for the storage device is arranged between the storage device exterior material 3 and the storage device element 4, or Figure 6 As shown in the figure, the outer packaging material 3 is arranged between the peripheral edge portion 3a (heat-welded portion) of the outer packaging material 3 and the power storage device element 4, and the outer packaging material 3 can also be arranged between the peripheral edge portion 3a (heat-welded portion) of the outer packaging material 3 and the power storage device element 4. Figure 7 As shown in the figure, the storage device element 4 is covered with the storage device resin film 1, and the storage device element 4 can also be covered with the resin film 1. Figure 8 As shown in FIG. 1 , a part of the surface of the metal terminal 2 is further covered with the resin film 1 for the power storage device. Fig. 9 As shown, the resin film 1 for a storage device of the present invention is arranged between the outer packaging material 3 of the storage device 10 and the storage device element 4 so that the storage device element 4 is sealed by the resin film 1 for a storage device. In addition, the resin film 1 for a storage device may be placed between the outer packaging material 3 and the metal terminal 2 and heat-sealed.

[0053] When the resin film 1 for a storage device is located at the flange portion of the exterior material 3 (the peripheral edge portion 3a of the exterior material 3), the resin film 1 for a storage device preferably has thermal fusion properties. Fig. 9 In the schematic diagram of , since the resin film 1 for the storage device is located at the flange portion where the exterior material 3 is heat-sealed, the resin film 1 for the storage device preferably has thermal fusion properties with the thermal fusion resin layer 35 and the adhesive film 21 for the metal terminal. In addition, the resin films 1 for the storage device preferably have thermal fusion properties with each other.

[0054] In the resin film 1 for storage device of the present invention, the layer A having a water absorbing agent content of 5 mass % or more may be a single layer or multiple layers, preferably a single layer. In addition, the layer B having a water absorbing agent content of less than 5 mass % may be a single layer or multiple layers.

[0055] The resin film 1 for a power storage device of the present invention is, for example, Figure 1 and Figure 2 As shown, it is composed of two or more layers. Figure 1 The resin film 1 for an electric storage device is composed of a two-layer laminated body in which a first layer 11 and a second layer 12 are laminated. Figure 2 1 shows a resin film 1 for a power storage device, which is composed of a three-layer laminated body in which a second layer 12, a first layer 11, and a third layer 13 are laminated in this order. Figure 1 and Figure 2 In the embodiment, the first layer 11 is layer A having a water absorbing agent content of 5 mass % or more, and the second layer 12 and the third layer 13 are layers B having a water absorbing agent content of less than 5 mass %.

[0056] In the present invention, a layer containing a water absorbing agent is sometimes referred to as a "water absorbing layer". That is, in the present invention, layer A (first layer 11) having a water absorbing agent content of 5% by mass or more is a water absorbing layer, and layer B (second layer 12 and third layer 13) having a water absorbing agent content of less than 5% by mass also becomes a water absorbing layer when containing a water absorbing agent. Specific examples of the laminated structure of the resin film 1 for a storage device include, for example, Figure 1 The first layer 11 is a water-absorbing layer, and the second layer 12 is a laminated structure of a layer without a water-absorbing agent. Figure 2 The first layer 11 located in the middle is a water-absorbing layer, and the second layer 12 and the third layer 13 located on the surface are a laminated structure of layers not containing a water-absorbing agent.

[0057] In the present invention, the two or more layers of the resin film for a storage device may include at least one layer A having a water absorbing agent content of 5% by mass or more and at least one layer B having a water absorbing agent content of less than 5% by mass. However, from the viewpoint of better exerting the effect of the present invention, the content of the water absorbing agent in layer A is preferably about 10% by mass or more, more preferably about 15% by mass or more, and preferably about 50% by mass or less, more preferably about 40% by mass or less, and further preferably about 30% by mass or less. Preferred ranges include about 5 to 50% by mass, about 5 to 40% by mass, about 5 to 30% by mass, about 10 to 50% by mass, about 10 to 40% by mass, about 10 to 30% by mass, about 15 to 50% by mass, about 15 to 40% by mass, about 15 to 30% by mass, etc. When the content of the water absorbing agent in layer A exceeds 50% by mass, there is a concern of poor film formation due to the generation of foreign matter in layer A, a decrease in interlayer adhesion, and a decrease in lamination strength or sealing strength. On the other hand, when the content of the water absorbing agent is 5% or less, sufficient water absorption cannot be exhibited.

[0058] Furthermore, from the viewpoint of better exerting the effects of the present invention, the content of the water absorbing agent in layer B having a content of less than 5% by mass is preferably about 3% by mass or less, more preferably 0% by mass, and preferred ranges include about 0 to 5% by mass, about 0 to 3% by mass, etc.

[0059] Furthermore, from the viewpoint of better exerting the effects of the present invention, the thickness of layer A having a water-absorbing agent content of 5% by mass or more is preferably about 3 μm or more, more preferably about 5 μm or more, and further preferably about 10 μm or more. Furthermore, it is preferably about 200 μm or less, more preferably about 150 μm or less, and further preferably about 100 μm or less. Preferred ranges include about 3 to 200 μm, about 3 to 150 μm, about 3 to 100 μm, about 5 to 200 μm, about 5 to 150 μm, about 5 to 100 μm, about 10 to 200 μm, about 10 to 150 μm, and about 10 to 100 μm.

[0060] In addition, from the viewpoint of better exerting the effects of the present invention (especially excellent insulation properties), the thickness of layer B having a water-absorbing agent content of less than 5% by mass is preferably about 3 μm or more, more preferably about 5 μm or more, and further preferably about 10 μm or more. In addition, it is preferably about 100 μm or less, more preferably about 80 μm or less, and further preferably about 50 μm or less. Preferred ranges include about 3 to 100 μm, about 3 to 80 μm, about 3 to 50 μm, about 5 to 100 μm, about 5 to 80 μm, about 5 to 50 μm, about 10 to 100 μm, about 10 to 80 μm, and about 10 to 50 μm.

[0061] The total thickness of the resin film 1 for a storage device is not particularly limited as long as the effect of the present invention is exerted, but is preferably about 10 μm or more, more preferably about 15 μm or more, and further preferably about 20 μm or more. In addition, it is preferably about 1000 μm or less, more preferably about 900 μm or less, and further preferably about 500 μm or less. As a preferred range of the thickness, there can be listed about 10 to 1000 μm, about 10 to 900 μm, about 10 to 500 μm, about 15 to 1000 μm, about 15 to 900 μm, about 15 to 500 μm, about 20 to 1000 μm, about 20 to 900 μm, and about 20 to 500 μm.

[0062] In addition, when the adhesive film for metal terminals is used as the resin film 1 for the storage device of the present invention, the total thickness may be within the above-mentioned range, but is preferably about 30 μm or more, more preferably about 50 μm or more, and further preferably about 60 μm or more. In addition, it is preferably about 1000 μm or less, more preferably about 500 μm or less, and further preferably about 300 μm or less. Preferred ranges include about 30 to 1000 μm, about 30 to 500 μm, about 30 to 300 μm, about 50 to 1000 μm, about 50 to 500 μm, about 50 to 300 μm, about 60 to 1000 μm, about 60 to 500 μm, and about 60 to 300 μm.

[0063] In addition, from the viewpoint of better exerting the effect of the present invention, the ratio of the thickness of layer B having a water absorbent content of less than 5% by mass to the total thickness of the resin film 1 for a storage device (thickness of layer B / total thickness) is preferably about 0.80 or less, more preferably about 0.75 or less, and further preferably about 0.50 or less. As for the lower limit, for example, about 0.01, about 0.05, and about 0.10 can be listed. As preferred ranges, about 0.01 to 0.80, about 0.01 to 0.75, about 0.01 to 0.50, about 0.05 to 0.80, about 0.05 to 0.75, about 0.05 to 0.50, about 0.10 to 0.80, about 0.10 to 0.75, and about 0.10 to 0.50 can be listed.

[0064] It is preferred that at least one layer of the two or more layers of the resin film 1 for a storage device contain a heat-fusible resin. Furthermore, it is preferred that one or both surfaces of the resin film 1 for a storage device have heat-fusible properties. For example, in the above-mentioned 2) use of the heat-fusible resin layer as an exterior material for a storage device, at least one surface of the resin film 1 for a storage device needs to have heat-fusible properties. It is particularly preferred that all layers of the resin film 1 for a storage device contain a heat-fusible resin.

[0065] In the above-mentioned application 1) of being arranged between the outer packaging material for a storage device and the storage device element, when the resin film 1 for a storage device is located at the flange portion of the outer packaging material 3 (the peripheral edge portion 3a of the outer packaging material 3), it is preferable to improve the heat-welding property of the resin film 1 for a storage device. For example, when the resin film 1 for a storage device is composed of three or more layers, it is preferable that the layer located on the surface (if Figure 2 , then the second layer 12 and the third layer 13) contain a heat-fusible resin. In addition, from the viewpoint of suppressing the decrease in the heat-fusible property of the layer located on the surface, it is preferred that the layer located on the surface does not contain a water absorbent (especially an inorganic water absorbent). In the storage device, from the viewpoint of better exerting the water absorption performance of the water absorption layer of the resin film 1 for the storage device, it is preferred that the water absorption layer is arranged between the layers located on the surface. This is because, when the water absorption layer is located on the surface, it will absorb moisture in the atmosphere before the storage device is manufactured, and the water absorption performance of the water absorption layer is likely to decrease. In addition, in the storage device, the water absorption layer is preferably located on the third layer 13 on the side of the outer packaging material 3 as a water absorption layer. This is because the third layer 13 is close to the outer packaging material 3 and easily absorbs moisture infiltrated from the side of the outer packaging material 3. In addition, in the storage device, the water absorption layer is preferably located on the second layer 12 on the side of the storage device element 4 as a water absorption layer. This is because the second layer 12 is close to the storage device element 4 and easily absorbs moisture contained in the storage device element 4.

[0066] The resin contained in the resin film 1 for storage device is not particularly limited as long as it does not hinder the effect of the present invention. For example, it is preferably a thermoplastic resin, and more preferably a heat-fusible resin. As specific examples of resins, resins such as polyolefins, polyesters, polyamides, epoxy resins, acrylic resins, fluororesins, polyurethanes, silicone resins, phenolic resins, and thermoplastic resins such as modified products of these resins can be listed. In addition, the resin forming the resin film 1 for storage device can be a copolymer of these resins or a modified product of the copolymer. Furthermore, it can also be a mixture of these resins. Among them, heat-fusible resins such as polyolefins and polyesters are particularly preferred.

[0067] In addition, as polyolefins, specifically, polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene can be listed; ethylene-α-olefin copolymers; polypropylenes such as homopolypropylene, polypropylene block copolymers (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); propylene-α-olefin copolymers; terpolymers of ethylene-butene-propylene, etc. The polyolefin resin in the case of a copolymer may be a block copolymer or a random copolymer. These polyolefin resins may be used alone or in combination of two or more. Among them, polypropylene is particularly preferred because of its excellent thermal fusion properties. Polypropylene may be either random polypropylene or homopolypropylene, but random polypropylene is more preferred from the viewpoint of water absorption speed and film-forming properties.

[0068] As polyester, specifically, polyethylene terephthalate, polybutylene terephthalate, polybutylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, copolyester, etc. can be cited. In addition, as copolyester, copolyester with ethylene terephthalate as the main repeating unit can be cited. Specifically, copolymer polyester (hereinafter abbreviated as polyethylene (terephthalic acid / isophthalic acid) mode) with ethylene terephthalate as the main repeating unit polymerized with ethylene isophthalate can be cited. Polyethylene (terephthalic acid / adipic acid), polyethylene (terephthalic acid / sodium sulfoisophthalate), polyethylene (terephthalic acid / sodium isophthalate), polyethylene (terephthalic acid / phenyl diphthalate), polyethylene (terephthalic acid / sebacic acid), etc. can be cited. These polyesters can be used alone or in combination of two or more. Among them, polybutylene terephthalate is particularly preferred from the viewpoint of improving heat resistance and pressure resistance (for example, reduction in insulation when the power storage device element 4 is sealed with the exterior material 3 (damage due to heat sealing)).

[0069] The resin contained in the resin film 1 for storage device may also contain an elastomer. The elastomer plays a role in ensuring the durability of the resin film 1 for storage device in a high temperature environment and improving its flexibility. As a preferred elastomer, at least one thermoplastic elastomer selected from polyesters, polyamides, polyurethanes, polyolefins, polystyrenes, and polyethers, or a thermoplastic elastomer as a copolymer thereof, etc., can be cited. In the resin film 1 for storage device, the amount of the elastomer contained is not particularly limited as long as it ensures the durability of the resin film 1 for storage device in a high temperature environment and improves its flexibility, for example, 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 further preferably about 3.0% by mass or more. In addition, the amount is, for example, about 10.0% by mass or less, about 8.0% by mass or less, about 5.0% by mass or less, etc. Preferred ranges of the content include about 0.1 to 10.0 mass %, about 0.1 to 8.0 mass %, about 0.1 to 5.0 mass %, about 0.5 to 10.0 mass %, about 0.5 to 8.0 mass %, about 0.5 to 5.0 mass %, about 1.0 to 10.0 mass %, about 1.0 to 8.0 mass %, about 1.0 to 5.0 mass %, about 3.0 to 10.0 mass %, about 3.0 to 8.0 mass %, about 3.0 to 5.0 mass %, etc.

[0070] The content of the resin contained in the resin film 1 for storage device can be, for example, 40.0 mass %, 45.0 mass %, 50.0 mass %, 55.0 mass %, 60.0 mass %, 65.0 mass %, 70.0 mass %, 75.0 mass %, 80.0 mass %, 85.0 mass %, 90.0 mass %, 95.0 mass %, 99.0 mass %, 99.5 mass %, 99.9 mass % or more, etc.

[0071] In addition, from the viewpoint of better exerting the effect of the present invention, the content of the absorbent contained in the resin film for a storage device is preferably 3% by mass or more, more preferably 6% by mass or more, and further preferably 9% by mass or more. In addition, it is preferably 30% by mass or less, more preferably 25% by mass or less, and further preferably 20% by mass or less. As preferred ranges, about 3 to 30% by mass, about 3 to 25% by mass, about 3 to 20% by mass, about 6 to 30% by mass, about 6 to 25% by mass, about 6 to 20% by mass, about 9 to 30% by mass, about 9 to 25% by mass, and about 9 to 20% by mass can be listed.

[0072] The water absorbent contained in the resin film 1 for storage devices is not particularly limited as long as it can be dispersed in the resin film to exert water absorption. For example, from the perspective of stability over time in the storage device, an inorganic water absorbent can be preferably used. As an inorganic water absorbent, for example, alkali metal compounds, alkaline earth metal compounds, etc. are preferred. As preferred specific examples of inorganic water absorbents, calcium oxide, anhydrous magnesium sulfate, magnesium oxide, calcium chloride, zeolite, aluminum oxide, silica gel, aluminum oxide gel and burnt alum can be cited. Generally speaking, among inorganic water absorbents, especially inorganic chemical water absorbents have a higher water absorption effect than inorganic physical water absorbents, can reduce the content, and are easy to achieve sufficient water absorption and thermal fusion properties with a single layer. Moreover, among inorganic chemical water absorbents, especially calcium oxide, anhydrous magnesium sulfate, and magnesium oxide have less water re-release, high stability over time in a low humidity state in the package, and have an absolute dry effect, so they are particularly preferred. In addition, the absolute dry effect refers to the effect of absorbing water when the relative humidity is close to 0%, and the humidity control effect refers to the effect of absorbing water when the humidity is high and releasing moisture when the humidity is low, so as to keep the humidity constant. In addition, when used in a high temperature environment such as an all-solid-state battery, an inorganic chemical absorbent with a high temperature band that releases moisture is preferably used.

[0073] In the resin film 1 for storage devices, the water absorbing agent contained in the water absorbing layer is preferably contained in a masterbatch obtained by melt-blending the water absorbing agent and the resin. Specifically, the water absorbing agent is melt-blended with the resin at a relatively high concentration to prepare the masterbatch. The water absorbing layer can be formed by further mixing the obtained masterbatch with the resin and forming it into a film. The content of the water absorbing agent in the masterbatch is preferably about 20 to 90% by mass, and more preferably about 30 to 70% by mass. As long as it is within the above range, it is easy to contain a necessary and sufficient amount of the water absorbing agent in a dispersed state in the water absorbing layer.

[0074] The resin film 1 for storage device can, for example, contain various plastic compounding agents, additives, etc., in order to improve and modify processability, heat resistance, weather resistance, mechanical properties, dimensional stability, oxidation resistance, smoothness, deformability, flame retardancy, antifungal property, electrical characteristics, strength, etc. As its content, it can be contained arbitrarily from a very small amount to tens of % according to its purpose. In the above description, as common additives, for example, anti-adhesion agents, lubricants, cross-linking agents, antioxidants, ultraviolet absorbers, light stabilizers, fillers (fillers), reinforcing agents, antistatic agents, pigments, modified resins, etc. can be contained.

[0075] From the viewpoint of better exerting the effects of the present invention (especially excellent insulation), in the resin film 1 for storage battery devices of the present invention, the content of solid particles in layer A of two or more layers is preferably about 10% by mass or more, more preferably about 15% by mass or more, and is preferably about 50% by mass or less, more preferably about 40% by mass or less, and more preferably about 30% by mass or less. Preferred ranges include about 5 to 50% by mass, about 5 to 40% by mass, about 5 to 30% by mass, about 10 to 50% by mass, about 10 to 40% by mass, about 10 to 30% by mass, about 15 to 50% by mass, about 15 to 40% by mass, about 15 to 30% by mass, etc. In addition, the content of solid particles in layer B having a water absorbing agent content of less than 5% by mass is preferably less than about 5%, more preferably less than about 3% by mass, and more preferably 0% by mass. Preferred ranges include about 0 to 5% by mass, about 0 to 3% by mass, etc. As solid particles, for example, part of the water absorbents exemplified above are solid particles, and pigments (such as carbon black, titanium oxides, cadmium, lead, chromium oxides, iron, etc.) and fillers (such as silicon dioxide) are also solid particles.

[0076] The dielectric breakdown strength of the resin film for a power storage device of the present invention after absorbing water, as measured by the following measurement method, is preferably about 40 kV / mm or more, more preferably about 50 to 200 kV / mm, and even more preferably about 50 to 150 kV / mm.

[0077] (Measurement of dielectric breakdown strength after water absorption)

[0078] Prepare a 10 cm square resin film for storage devices and immerse it in warm water at 80°C. Continue immersing until the water absorbent in the resin film for storage devices absorbs 100% of the water, thereby obtaining the resin film for storage devices after water absorption. When the weight change of the resin film due to immersion no longer occurs, it is judged that the water absorbent in the resin film has absorbed 100% of the water. The water absorption of the resin film for storage devices is calculated from the weight of the film before and after immersion. Next, according to the provisions of JIS C 2110-1:2016, the measurement environment is 23°C in the atmosphere, the boost method is the short time method (AC, 50Hz), the boost speed is 0.3kV / s, and the electrodes are cylinder / The dielectric breakdown strength of the resin film for power storage devices after water absorption was measured under the cylindrical measurement condition. The measured value is the average value of 5 samples.

[0079] (Method for producing resin film for power storage device)

[0080] The manufacturing method of the resin film 1 for storage device is not particularly limited as long as the resin film 1 for storage device can be obtained, and known or conventional film-making methods and lamination methods can be applied. The manufacture of the resin film 1 for storage device can be carried out by known film-making methods and / or lamination methods such as extrusion or coextrusion, cast molding, T-die head method, cutting method, inflation method, etc. For example, the pre-made film constituting each layer can be laminated via an adhesive layer, and the molten resin composition can also be laminated on the pre-made layer by extrusion or coextrusion, and it is also possible to laminate by melt-compression bonding while making multiple layers at the same time, or it is also possible to apply one or more resins on other layers and dry them to form a coating.

[0081] The layer constituting the resin film 1 for storage device can also be laminated by extrusion or coextrusion, or laminated via an adhesive layer after film-making by inflation method or casting method. In the case of extrusion coating method, it can also be laminated across an adhesive layer as required. Alternatively, the film made in advance can also be laminated and bonded via an adhesive layer laminated by extrusion coating method, dry lamination method, solvent-free lamination method, etc. Then, aging treatment can be performed as required.

[0082] For example, when laminating each layer by extrusion coating, first, heat the resin composition forming the layer to melt it, expand and stretch it in the necessary width direction in a T-die and extrude or co-extrude it into a curtain shape, so that the molten resin flows down to the laminated surface, and is clamped with a rubber roller and a cooled metal roller, thereby forming the layer and laminating and bonding on the laminated surface at the same time. The melt flow rate (MFR) of the resin component contained in each layer when laminating by extrusion coating is preferably 0.2 to 50 g / 10 minutes, more preferably 0.5 to 30 g / 10 minutes. When MFR is less than or greater than the above range, processing adaptability tends to deteriorate. It should be noted that in this specification, MFR refers to the value measured by the method according to JIS K7210.

[0083] When the inflation method is used, the melt flow rate (MFR) of the resin component contained in each layer is preferably 0.2 to 10 g / 10 min, more preferably 0.2 to 9.5 g / 10 min. When the MFR is less than or greater than the above range, the processability tends to deteriorate.

[0084] In addition, in order to improve the adhesion between the layers constituting the resin film for the storage device, the surface of each layer can be pre-treated as needed. For example, pre-treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen or nitrogen, glow discharge treatment, oxidation treatment using chemicals, etc. can be arbitrarily implemented to form and set a corona treatment layer, an ozone treatment layer, a plasma treatment layer, an oxidation treatment layer, etc. Alternatively, various coating layers such as a primer layer, a primer layer, an anchor coating layer, an adhesive layer, and a vapor-deposited anchor coating layer can also be arbitrarily formed on the surface as a surface treatment layer. Among the above-mentioned various coating agent layers, for example, a resin composition with a polyester resin, a polyamide resin, a polyurethane resin, an epoxy resin, a phenolic resin, a (meth) acrylic resin, a polyvinyl acetate resin, a polyolefin resin such as polyethylene or polypropylene or its copolymer or a modified resin, a cellulose resin, etc. as the main component of the carrier can be used.

[0085] Each layer constituting the resin film for a power storage device may be further uniaxially stretched or biaxially stretched by a conventionally known method such as a tension frame method or a tube frame method, as required.

[0086] 2. Power storage devices

[0087] As described above, the power storage device 10 of the present invention has a structure in which the power storage device element 4 is sealed with the exterior material 3. The power storage device 10 is sealed as follows: the power storage device element 4 is covered with the exterior material 3 in such a manner that a flange portion of the exterior material 3 (peripheral portion 3a of the exterior material 3) can be formed at the periphery of the power storage device element 4, and the flange portion of the exterior material 3 is heat-sealed to be sealed.

[0088] In the storage device 10 of the present invention, the storage device resin film 1 may be located on the entire surface of the storage device element 4 side (thermal adhesive resin layer 35 side) of the exterior material 3 or may be located on a portion of the surface of the storage device element 4 side (thermal adhesive resin layer 35 side) in the application 1) of being arranged between the storage device exterior material and the storage device element. From the viewpoint of appropriately exerting the effect of the present invention, it is preferred that the storage device resin film 1 be arranged between the storage device exterior material 3 and the storage device element 4 of the storage device 10 in such a manner that the entire surface of the exterior material 3 is located on the storage device element 4 side (thermal adhesive resin layer 35 side) (see Figures 5 to 9 For example, you can Figure 5 As shown in the figure, only the resin film 1 for the storage device is arranged between the storage device exterior material 3 and the storage device element 4, or Figure 6 As shown in FIG. 1 , the outer packaging material 3 is disposed between the peripheral edge portion 3a (heat-welded portion) of the outer packaging material 3 and the power storage device element 4, and the outer packaging material 3 can also be disposed between the peripheral edge portion 3a (heat-welded portion) of the outer packaging material 3 and the power storage device element 4. Figure 7As shown in the figure, the power storage device element 4 is covered with the power storage device resin film 1, and it is also possible to Figure 8 As shown in FIG. 1 , a part of the surface of the metal terminal 2 is further covered with the resin film 1 for the power storage device. Fig. 9 As shown in the figure, the resin film 1 for a storage device of the present invention is arranged between the outer packaging material 3 of the storage device 10 and the storage device element 4 so that the storage device element 4 is sealed by the resin film 1 for a storage device. Alternatively, the resin film 1 for a storage device may be present between the outer packaging material 3 and the metal terminal 2 and heat-sealed.

[0089] In the power storage device 10 of the present invention, the resin film 1 for power storage device is used as the heat-fusible resin layer of the power storage device exterior material in the above-mentioned 2) Figure 3 As shown, the resin film 1 for a power storage device of the present invention is used as the heat-fusible resin layer 35 of the power storage device exterior material 3 composed of a laminate including at least a base layer 31 , a barrier layer 33 , and a heat-fusible resin layer 35 in this order.

[0090] In the storage device 10 of the present invention, the storage device resin film 1 is used as an adhesive film for a metal terminal between a metal terminal electrically connected to an electrode of a storage device element and a storage device outer packaging material sealing the storage device element in the above-mentioned 4). Figure 4 As shown, the resin film 1 for an electric storage device is used as the adhesive film 21 for a metal terminal.

[0091] [Exterior material 3]

[0092] The outer packaging material 3 may be a metal can or a laminated film having a barrier layer. As the outer packaging material 3 composed of a laminated film, there can be cited an outer packaging material having a laminated structure formed by a laminate having at least a base layer 31, a barrier layer 33 and a heat-fusible resin layer 35 in this order. Figure 3 In the figure, as an example of the cross-sectional structure of the exterior material 3, a substrate layer 31, an adhesive layer 32 provided as required, a barrier layer 33, an adhesive layer 34 provided as required, and a heat-fusible resin layer 35 are sequentially stacked. In the exterior material 3, the substrate layer 31 becomes the outer layer side, and the heat-fusible resin layer 35 becomes the innermost layer. When assembling the power storage device, the heat-fusible resin layers 35 located at the periphery of the power storage device element 4 are brought into surface contact with each other and heat-fused, thereby sealing the power storage device element 4. It should be noted that in Figures 4 to 9 , the power storage device 10 is shown using an embossed outer packaging material 3 formed by embossing, etc., but the outer packaging material 3 may also be an unformed bag type. In addition, there are three-sided sealed type, four-sided sealed type, pillow type, etc. in the bag type, and any type is acceptable.

[0093] There is no particular limitation on the thickness of the laminate constituting the outer packaging material 3. As for the upper limit, from the viewpoints of reducing costs and improving energy density, for example, about 190 μm or less can be cited, 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, about 120 μm or less can be cited. As for the lower limit, from the viewpoint of maintaining the function of the outer packaging material 3 such as protecting the energy storage device element 4, preferably about 35 μm or more, about 45 μm or more, about 60 μm or more, about 80 μm or more can be cited. As for the preferred range, for example, about 35 to 190 μm, about 35 to 180 μm, about 35 to 160 μm, about 35 to 155 μm, and 35 to 140 μm can be cited. About 35-130μm, about 35-120μm, about 45-190μm, about 45-180μm, about 45-160μm, about 45-155μm, about 45-140μm, about 45-130μm, about 45-120μm, about 60-190μm, about 60-180μm, about 60-160μm, about 60-155μm, about 60-140μm, about 60-130μm, about 60-120μm, about 80-190μm, about 80-180μm, about 80-160μm, about 80-155μm, about 80-140μm, about 80-130μm, about 80-120μm.

[0094] In addition, the resin film 1 for a storage battery device of the present invention can be suitably applied to an exterior material for an all-solid-state battery. The thickness of the laminate constituting the exterior material for an all-solid-state battery is not particularly limited. From the viewpoint of reducing costs and improving energy density, preferably, it is about 10000 μm or less, about 8000 μm or less, or about 5000 μm or less. From the viewpoint of maintaining the function of the exterior material for an all-solid-state battery such as protecting battery elements, preferably, it is about 100 μm or more, about 150 μm or more, or about 200 μm or more. μm or more, about 200 μm or more, the preferred range includes, for example, about 100 to 10000 μm, about 100 to 8000 μm, about 100 to 5000 μm, about 150 to 10000 μm, about 150 to 8000 μm, about 150 to 5000 μm, about 200 to 10000 μm, about 200 to 8000 μm, about 200 to 5000 μm, and particularly preferably about 200 to 5000 μm.

[0095] (Base material layer 31)

[0096] In the exterior material 3 , the base material layer 31 is a layer that functions as a base material of the exterior material and is a layer forming the outermost layer side.

[0097] There are no particular restrictions on the raw materials for forming the substrate layer 31 as long as they have insulating properties. Examples of the raw materials for forming the substrate layer 31 include polyester, polyamide, epoxy resin, acrylic acid, fluororesin, polyurethane, silicone resin, phenol, polyetherimide, polyimide, and mixtures and copolymers thereof. Polyesters such as polyethylene terephthalate and polybutylene terephthalate have advantages such as excellent resistance to electrolyte and low whitening due to adhesion of electrolyte, and are suitable for use as the raw materials for forming the substrate layer 31. In addition, polyamide films have excellent stretchability and can prevent whitening caused by resin rupture of the substrate layer 31 during molding, and are suitable for use as the raw materials for forming the substrate layer 31.

[0098] The substrate layer 31 may be formed of a uniaxially or biaxially stretched resin film or an unstretched resin film. Among them, a uniaxially or biaxially stretched resin film, especially a biaxially stretched resin film, has improved heat resistance through orientation crystallization and is therefore suitable for use as the substrate layer 31.

[0099] Among them, nylon and polyester are preferred as the resin film forming the substrate layer 31, and biaxially stretched nylon and biaxially stretched polyester are more preferred. In addition, in order to make the all-solid-state battery have a durable temperature of 150°C or more, it is often sealed at a high temperature of 200°C or more, and biaxially stretched polyester is most suitable.

[0100] In order to improve the pinhole resistance and the insulation when the packaging body of the power storage device is made, the base layer 31 can also be laminated with resin films of different raw materials. Specifically, a multilayer structure formed by laminating a polyester film and a nylon film, a multilayer structure formed by laminating a biaxially stretched polyester and a biaxially stretched nylon, etc. can be listed. In the case of making the base layer 31 a multilayer structure, each resin film can be bonded via an adhesive, and can also be directly laminated without an adhesive. In the case of bonding without an adhesive, for example, a method of bonding in a hot melt state such as a co-extrusion method, a sandwich lamination method, and a hot lamination method can be listed. For the above-mentioned high-temperature sealing, it is preferred that at least the outermost layer is a biaxially stretched polyester.

[0101] In addition, in order to improve the formability, the friction of the base layer 31 can also be reduced. When the friction of the base layer 31 is reduced, there is no particular limitation on the friction coefficient of the surface thereof, and for example, it can be 1.0 or less. In order to reduce the friction of the base layer 31, for example, matte treatment, formation of a film layer of a lubricant, and a combination thereof can be cited.

[0102] The thickness of the substrate layer 31 is, for example, about 3 μm or more, about 4 μm or more, about 5 μm or more, about 10 μm or more, about 15 μm or more, and about 100 μm or less, about 75 μm or less, about 50 μm or less, about 30 μm or less, and preferred ranges include about 3 to 100 μm, about 3 to 75 μm, about 3 to 50 μm, about 3 to 30 μm, about 4 to 100 μm, about 4 to 75 μm, about 50 μm, about 3 to 30 μm, about 6 to 100 μm, about 6 to 150 μm, about 7 to 150 μm, about 8 to 200 μm, about 9 to 100 μm, about 10 to 200 μm, about 15 to 2 ... ~75μm, about 4~50μm, about 3~30μm, about 5~100μm, about 5~75μm, about 5~50μm, about 5~30μm, about 10~100μm, about 10~75μm, about 10~50μm, about 10~30μm, about 15~100μm, about 15~75μm, about 15~50μm, about 15~30μm.

[0103] (Adhesive layer 32)

[0104] In the exterior material 3, the adhesive layer 32 is a layer disposed on the base layer 31 as necessary in order to impart adhesion to the base layer 31. That is, the adhesive layer 32 is provided between the base layer 31 and the barrier layer 33.

[0105] The adhesive layer 32 is formed of an adhesive capable of bonding the base material layer 31 to 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. In addition, there is no particular limitation on the bonding mechanism of the adhesive used in forming the adhesive layer 32, and the adhesive may be any of a chemical reaction type, a solvent volatilization type, a hot melt type, a hot pressing type, and the like.

[0106] As the resin component of the adhesive that can be used to form the adhesive layer 32, from the viewpoint of excellent ductility, durability under high humidity conditions, yellowing inhibition, thermal degradation inhibition during heat sealing, and effectively inhibiting the occurrence of delamination by inhibiting the reduction in the lamination strength between the base layer 31 and the barrier layer 33, preferably included are: polyurethane-based two-component curing adhesives; polyamides, polyesters or blended resins of these with modified polyolefins.

[0107] In addition, 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 layer 31 and the barrier layer 33, it is preferred to select a resin having excellent adhesion to the base layer 31 as the adhesive component disposed on the base layer 31 side, and to select an adhesive component having excellent adhesion to the barrier layer 33 as the adhesive component disposed on the barrier layer 33 side. When the adhesive layer 32 is multilayered with different adhesive components, specifically, as the adhesive component disposed on the barrier layer 33 side, preferably, an acid-modified polyolefin, a metal-modified polyolefin, a mixed resin of a polyester and an acid-modified polyolefin, a resin containing a copolyester, an alicyclic isocyanate compound, etc. are listed.

[0108] The thickness of the adhesive layer 32 may be, for example, approximately 2 μm to 50 μm, and preferably approximately 3 μm to 25 μm.

[0109] (Barrier layer 33)

[0110] In the outer packaging material, the barrier layer 33 is a layer that has the function of preventing water vapor, oxygen, light, etc. from invading the interior of the storage device element in addition to improving the strength of the outer packaging material. The barrier layer 33 is preferably a metal layer, that is, a layer formed of metal. As the metal constituting the barrier layer 33, specifically, aluminum, stainless steel, titanium, etc. can be listed, and aluminum can be preferably listed. The barrier layer 33 can be formed, for example, of a metal foil, a metal vapor-deposited film, an inorganic oxide vapor-deposited film, a carbon-containing inorganic oxide vapor-deposited film, a film provided with these vapor-deposited films, etc., preferably formed of a metal foil, and more preferably formed of an aluminum foil. When manufacturing the exterior material, from the viewpoint of preventing wrinkles and pinholes from being generated in the barrier layer 33, the barrier layer is more preferably formed of a soft aluminum foil such as annealed aluminum (JIS H4160: 1994A8021H-O, JIS H4160: 1994A8079H-O, JIS H4000: 2014A8021P-O, JIS H4000: 2014A8079P-O).

[0111] Regarding the thickness of the barrier layer 33, from the viewpoint of making the outer packaging material thinner and less likely to generate pinholes even during molding, the thickness is preferably about 10 to 200 μm, and more preferably about 20 to 100 μm. From the viewpoint of imparting high moldability or high rigidity to the outer packaging material 3 for the storage device, the thickness of the barrier layer 33 is preferably about 45 μm or more, more preferably about 50 μm or more, preferably about 85 μm or less, and more preferably 75 μm or less. As preferred ranges, about 45 to 85 μm, about 45 to 75 μm, about 50 to 85 μm, and about 50 to 75 μm can be listed.

[0112] In order to stabilize adhesion, prevent dissolution, corrosion, etc., it is preferred that at least one surface, preferably both surfaces, of the barrier layer 33 be subjected to chemical conversion treatment. Here, chemical conversion treatment refers to a treatment for forming a corrosion-resistant film on the surface of the barrier layer.

[0113] (Adhesive layer 34)

[0114] In the exterior material 3 , the adhesive layer 34 is a layer provided between the barrier layer 33 and the thermally-adhesive resin layer 35 as necessary in order to firmly adhere the thermally-adhesive resin layer 35 .

[0115] The adhesive layer 34 is formed of 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, and examples thereof include an adhesive containing a polyester polyol compound and an alicyclic isocyanate compound.

[0116] The thickness of the adhesive layer 34 is, for example, approximately 1 μm to 40 μm, and preferably approximately 2 μm to 30 μm.

[0117] (Thermal Fusible Resin Layer 35)

[0118] In the exterior material 3 , the heat-fusible resin layer 35 corresponds to the innermost layer, and is a layer in which the heat-fusible resin layers are heat-fused to each other to seal the electric storage device element when the electric storage device is assembled.

[0119] The resin component used in the heat-fusible resin layer 35 is not particularly limited as long as it can be heat-fused. For example, among the outer packaging materials, polyolefins and cyclic polyolefins are generally used. In addition, in the application of the resin film 1 for a storage device of the present invention in the above-mentioned 2) as a heat-fusible resin layer of an outer packaging material for a storage device, for example Figure 3 As shown, the resin film 1 for a storage device of the present invention is used as the heat-fusible resin layer 35 of the storage device exterior material 3 including a laminate including at least a base layer 31 , a barrier layer 33 , and a heat-fusible resin layer 35 in this order.

[0120] Specifically, the polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); terpolymers of ethylene-butene-propylene, etc. Among these polyolefins, polyethylene and polypropylene are preferably included.

[0121] The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. As the olefin constituting the cyclic polyolefin, for example, ethylene, propylene, 4-methyl-1-pentene, butadiene, isoprene, etc. can be cited. In addition, as the cyclic monomer constituting the cyclic polyolefin, for example, cyclic olefins such as norbornene can be cited; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene can be cited. Among these polyolefins, cyclic olefins are preferably cited, and norbornene is further preferably cited. As a constituent monomer, styrene can also be cited.

[0122] Among these resin components, preferred are crystalline or amorphous polyolefins, cyclic polyolefins, and polymer blends thereof; more preferred are polyethylene, polypropylene, copolymers of ethylene and norbornene, and polymer blends of two or more thereof.

[0123] The heat-adhesive resin layer 35 may be formed of a single resin component or a blended polymer of two or more resin components. Furthermore, the heat-adhesive resin layer 35 may be formed of only one layer or two or more layers of the same or different resin components.

[0124] The thickness of the thermally fusible resin layer 35 is not particularly limited, but is about 2 to 2000 μm, preferably about 5 to 1000 μm, and more preferably about 10 to 500 μm.

[0125] In addition, the resin film 1 for the storage device of the present invention can be suitably applied to the external packaging material for all-solid-state batteries, and the melting point of the heat-fusible resin layer 35 of the external packaging material for all-solid-state batteries is preferably 150 to 250°C, more preferably 180 to 270°C, further preferably 200 to 270°C, and further preferably 200 to 250°C.

[0126] In addition, as the resin contained in the heat-fusible resin layer 35 of the all-solid-state battery exterior material, for example, polyolefins such as polypropylene and polyethylene, acid-modified polyolefins such as acid-modified polypropylene and acid-modified polyethylene, polybutylene terephthalate, etc. can be listed. Among them, polybutylene terephthalate has excellent heat resistance, so in the all-solid-state battery exterior material, the heat-fusible resin layer 35 is preferably formed of a polybutylene terephthalate film. In addition, since the heat-fusible resin layer 35 is formed of a polybutylene terephthalate film, the adhesion with the resin film 1 for the storage device of the present invention is also excellent. It should be noted that the polybutylene terephthalate film forming the heat-fusible resin layer 35 can be made by laminating a pre-prepared polybutylene terephthalate film with the adhesive layer 34 to form the heat-fusible resin layer 35, or the resin forming the polybutylene terephthalate film can be melt-extruded to form a film and laminated with the adhesive layer 34, or the resin forming the heat-fusible resin layer 35 and the resin forming the adhesive layer 34 can be co-extruded and laminated.

[0127] The polybutylene terephthalate film may be a stretched polybutylene terephthalate film or an unstretched polybutylene terephthalate film, and is preferably an unstretched polybutylene terephthalate film.

[0128] The polybutylene terephthalate film preferably also includes an elastomer in addition to polybutylene terephthalate. The elastomer plays a role in improving its flexibility while ensuring the durability of the polybutylene terephthalate film under a high temperature environment. As a preferred elastomer, at least one thermoplastic elastomer selected from polyesters, polyamides, polyurethanes, polyolefins, polystyrenes, and polyethers, or a thermoplastic elastomer as their copolymer, etc. can be cited. In the polybutylene terephthalate film, as the content of the elastomer, as long as it is possible to ensure the durability of the polybutylene terephthalate film under a high temperature environment and improve its flexibility, there is no particular restriction, for example, 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 further preferably about 3.0% by mass or more. In addition, the content is, for example, about 10.0% by mass or less, about 8.0% by mass or less, about 5.0% by mass or less, etc. Preferred ranges of the content include about 0.1 to 10.0 mass %, about 0.1 to 8.0 mass %, about 0.1 to 5.0 mass %, about 0.5 to 10.0 mass %, about 0.5 to 8.0 mass %, about 0.5 to 5.0 mass %, about 1.0 to 10.0 mass %, about 1.0 to 8.0 mass %, about 1.0 to 5.0 mass %, about 3.0 to 10.0 mass %, about 3.0 to 8.0 mass %, about 3.0 to 5.0 mass %, etc.

[0129] The heat-fusible resin layer 35 can be formed by only one layer, or by more than two layers of the same or different resins. When the heat-fusible resin layer 35 is formed by more than two layers, it is preferred that at least one layer is formed by a polybutylene terephthalate film, which is the innermost layer of the exterior material for the all-solid-state battery. In addition, the layer bonded to the adhesive layer 34 is preferably a polybutylene terephthalate film. In the case where the heat-fusible resin layer 35 is formed by more than two layers, the layer not formed by the polybutylene terephthalate film can be, for example, a layer formed by polyolefins such as polypropylene and polyethylene, acid-modified polypropylene, acid-modified polyethylene, etc. However, polyolefins and acid-modified polyolefins have low durability under high temperature environments compared to polybutylene terephthalate, so the heat-fusible resin layer 35 is preferably composed only of polybutylene terephthalate film.

[0130] The power storage device of the present invention is a power storage device such as a battery (including a capacitor, a capacitor, etc.). In addition, the power storage device of the present invention can be used for any one of a primary battery and a secondary battery, preferably a secondary battery. There is no particular restriction on the type of secondary battery, for example, lithium ion batteries, lithium ion polymer batteries, all-solid-state batteries, lead storage batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver-zinc oxide batteries, metal-air batteries, multivalent cation batteries, capacitors, capacitors, etc. can be listed. Among these secondary batteries, as the power storage device of the present invention, lithium ion batteries, lithium ion polymer batteries, all-solid-state batteries can be listed, and are particularly suitable for all-solid-state batteries.

[0131] Example

[0132] The present invention will be described in detail below with reference to Examples and Comparative Examples, but the present invention is not limited to the Examples.

[0133] <Manufacturing of Resin Film for Electricity Storage Device>

[0134] (Example 1)

[0135] A random polypropylene film (water absorbent content 0 mass%, thickness 10 μm) was laminated on both sides of a random polypropylene film (thickness 30 μm) containing 20 mass% of calcium oxide (CaO) as a water absorbent to produce a resin film for a storage device with a three-layer structure of r-PP (water absorbent content 0 mass%, 10 μm) / r-PP (water absorbent content 20 mass%, 30 μm) / r-PP (water absorbent content 0 mass%, 10 μm).

[0136] (Example 2)

[0137] A random polypropylene film (water absorbent content 0 mass%, thickness 20 μm) was laminated on one side of a random polypropylene film (thickness 30 μm) containing 20 mass% of CaO as a water absorbent to produce a resin film for a storage device having a two-layer structure of r-PP (water absorbent content 0 mass%, 20 μm) / r-PP (water absorbent content 20 mass%, 30 μm). The resin film for a storage device of Example 2 was used in such a manner that the r-PP (water absorbent content 0 mass%, 20 μm) side was arranged on the exterior material side, and the r-PP (water absorbent content 20 mass%, 30 μm) side was arranged on the storage device element side.

[0138] (Example 3)

[0139] In the same manner as in Example 2, a random polypropylene film (water absorbent content 0 mass%, thickness 20 μm) was laminated on one side of a random polypropylene film (thickness 30 μm) containing 20 mass% of CaO as a water absorbent, to produce a resin film for a storage device having a two-layer structure of r-PP (water absorbent content 20 mass%, 30 μm) / r-PP (water absorbent content 0 mass%, 20 μm). The resin film for a storage device of Example 3 was used in such a manner that the r-PP (water absorbent content 0 mass%, thickness 20 μm) side was arranged on the storage device element side, and the r-PP (water absorbent content 20 mass%, 30 μm) was arranged on the exterior material side.

[0140] (Example 4)

[0141] A random polypropylene film (thickness 15 μm) containing 20% ​​by mass of CaO as a water absorbent was laminated on both surfaces of a random polypropylene film (water absorbent content 0% by mass, thickness 20 μm) to produce a resin film for a storage device with a three-layer structure of r-PP (water absorbent content 20% by mass, 15 μm) / r-PP (water absorbent content 0% by mass, 20 μm) / r-PP (water absorbent content 20% by mass, 15 μm).

[0142] (Example 5)

[0143] A random polypropylene film (water absorbent content 0 mass%, thickness 10 μm) was laminated on both sides of a random polypropylene film (thickness 30 μm) containing 20 mass% of CaO as a water absorbent and 5 mass% of titanium oxide particles as solid particles, to produce a resin film for a storage device with a three-layer structure of r-PP (water absorbent content 0 mass%, 10 μm) / r-PP (water absorbent content 20 mass%, 30 μm) / r-PP (water absorbent content 0 mass%, 10 μm).

[0144] (Example 6)

[0145] A resin film for a storage device having a three-layer structure of PBT (water absorbent content 0 mass%, 10 μm) / PBT (water absorbent content 20 mass%, 30 μm) / PBT (water absorbent content 0 mass%, 10 μm) was manufactured by laminating polybutylene terephthalate films (water absorbent content 0 mass%, thickness 10 μm) on both sides of a polybutylene terephthalate film (thickness 30 μm) containing 20 mass% of CaO as a water absorbent.

[0146] (Example 7)

[0147] A resin film for a storage device is manufactured in the same manner as in Example 2, and is used as a heat-fusible resin layer of an exterior material for a storage device. As a base material layer for an exterior material for a storage device, a material to which a corona treatment has been applied on the bonding surface side of a polyethylene terephthalate film (thickness 25 μm or 12 μm), and a nylon film (thickness 25 μm) are prepared. In addition, as a barrier layer, an aluminum alloy foil (JIS H 4160: 1994A8021H-O, thickness 40 μm) is prepared. In addition, as a heat-fusible resin layer, the above-mentioned resin film for a storage device is used. Next, a two-component curing urethane adhesive (polyester polyol and alicyclic isocyanate compound) is used to prepare a laminate in which a polyethylene terephthalate film and a nylon film, and a nylon film and a barrier layer are bonded by a dry lamination method. Furthermore, using a two-component curing urethane adhesive (polyester polyol and alicyclic isocyanate compound), the barrier layer side of the obtained laminate is bonded to the resin film for the storage device by a dry lamination method, and an adhesive layer (4 μm) / resin film for the storage device is stacked on the barrier layer. Next, the obtained laminate is aged and heated to obtain an external packaging material for the storage device consisting of a laminate of polyethylene terephthalate film / adhesive layer / nylon film / adhesive layer / barrier layer / adhesive layer / resin film for the storage device. The heat-fusible resin layer is stacked in the order of r-PP (water absorbent content 20% by mass, 30 μm) / r-PP (water absorbent content 0% by mass, 20 μm) from the barrier layer side.

[0148] (Example 8)

[0149] Two resin films for storage devices were prepared in the same manner as in Example 2, and used as adhesive films for metal terminals (length 10 mm, width 55 mm). At the center of the length direction of an aluminum metal terminal (length 60 mm, width 45 mm, thickness 400 μm), the metal terminal was clamped with two adhesive films for metal terminals in a manner orthogonal to the length direction, and hot pressing was performed from both sides (temperature 190°C, pressure 0.25 MPa, 16 seconds), thereby installing the adhesive film for metal terminals on the metal terminals to obtain metal terminals with adhesive films for metal terminals. The adhesive films for metal terminals were stacked in the order of r-PP (water absorbent content 20% by mass, 30 μm) / r-PP (water absorbent content 0% by mass, 20 μm) from the metal terminal side.

[0150] (Example 9)

[0151] A random polypropylene film (water absorbent content 0 mass%, thickness 5 μm) was laminated on both sides of a random polypropylene film (thickness 40 μm) containing 15 mass% of calcium oxide (CaO) as a water absorbent, to produce a resin film for a storage device with a three-layer structure of r-PP (water absorbent content 0 mass%, 5 μm) / r-PP (water absorbent content 15 mass%, 40 μm) / r-PP (water absorbent content 0 mass%, 5 μm).

[0152] (Example 10)

[0153] A random polypropylene film (water absorbent content 0 mass%, thickness 90 μm) was laminated on one side of a random polypropylene film (thickness 30 μm) containing 20 mass% of CaO as a water absorbent to produce a resin film for a storage device having a two-layer structure of r-PP (water absorbent content 0 mass%, 90 μm) / r-PP (water absorbent content 20 mass%, 30 μm). The resin film for a storage device of Example 10 was used in a manner in which r-PP (water absorbent content 0 mass%, 90 μm) was arranged on the outer packaging material side and r-PP (water absorbent content 20 mass%, 30 μm) was arranged on the storage device element side.

[0154] (Example 11)

[0155] A random polypropylene film (water absorbent content 4 mass%, thickness 10 μm) containing 4 mass% of calcium oxide (CaO) as a water absorbent was laminated on both surfaces of a random polypropylene film (thickness 30 μm) containing 17.4 mass% of calcium oxide (CaO) as a water absorbent, to produce a resin film for a storage device having a three-layer structure of r-PP (water absorbent content 4 mass%, 10 μm) / r-PP (water absorbent content 17.4 mass%, 30 μm) / r-PP (water absorbent content 4 mass%, 10 μm).

[0156] (Example 12)

[0157] A random polypropylene film (water absorbent content 20 mass%, thickness 90 μm) containing 20 mass% of CaO as a water absorbent was laminated on one side of a random polypropylene film (water absorbent content 0 mass%, thickness 30 μm) to produce a resin film for a storage device having a two-layer structure of r-PP (water absorbent content 20 mass%, 90 μm) / r-PP (water absorbent content 0 mass%, 30 μm). The resin film for a storage device of Example 12 was used in a manner in which r-PP (water absorbent content 20 mass%, 90 μm) was arranged on the outer packaging material side, and r-PP (water absorbent content 0 mass%, 30 μm) was arranged on the storage device element side.

[0158] (Example 13)

[0159] A random polypropylene film (water absorbent content 45 mass%, thickness 30 μm) containing 45 mass% CaO as a water absorbent was laminated on one side of a random polypropylene film (water absorbent content 0 mass%, thickness 20 μm) to produce a resin film for a storage device having a two-layer structure of r-PP (water absorbent content 45 mass%, 30 μm) / r-PP (water absorbent content 0 mass%, 20 μm). The resin film for a storage device of Example 13 was used in a manner in which r-PP (water absorbent content 45 mass%, 30 μm) was arranged on the outer packaging material side, and r-PP (water absorbent content 0 mass%, 20 μm) was arranged on the storage device element side.

[0160] (Example 14)

[0161] A random polypropylene film (water absorbent content 0 mass%, thickness 10 μm) was laminated on both sides of a random polypropylene film (thickness 30 μm) containing 20 mass% of magnesium oxide (MgO) as a water absorbent, to produce a resin film for a storage device with a three-layer structure of r-PP (water absorbent content 0 mass%, 10 μm) / r-PP (water absorbent content 20 mass%, 30 μm) / r-PP (water absorbent content 0 mass%, 10 μm).

[0162] (Example 15)

[0163] In the presence of 20 mass % of magnesium sulfate (MgSO 4 ) are laminated on both sides of a random polypropylene film (thickness 30 μm) to manufacture a resin film for storage devices with a three-layer structure of r-PP (water absorbent content 0 mass%, thickness 10 μm) / r-PP (water absorbent content 20 mass%, 30 μm) / r-PP (water absorbent content 0 mass%, 10 μm).

[0164] (Example 16)

[0165] A maleic anhydride-modified random polypropylene film (water absorbent content 0 mass%, thickness 20 μm) was laminated on one side of a random polypropylene film (thickness 30 μm) containing 20 mass% of CaO as a water absorbent to produce a resin film for a storage device having a two-layer structure of r-PPa (water absorbent content 0 mass%, 20 μm) / r-PP (water absorbent content 20 mass%, 30 μm). The resin film for a storage device of Example 16 is an adhesive film for metal terminals, and is used in a manner in which r-PP (water absorbent content 20 mass%, 30 μm) is arranged on the outer packaging material side, and r-PPa (water absorbent content 0 mass%, 20 μm) is arranged on the metal terminal side.

[0166] (Example 17)

[0167] A maleic anhydride-modified homopolypropylene film (water absorbent content 0 mass%, thickness 20 μm) was laminated on one side of a homopolypropylene film (thickness 30 μm) containing 20 mass% of CaO as a water absorbent, to produce a resin film for a storage device having a two-layer structure of h-PPa (water absorbent content 0 mass%, 20 μm) / h-PP (water absorbent content 20 mass%, 30 μm). The resin film for a storage device of Example 17 is an adhesive film for metal terminals, and is used in a manner in which h-PP (water absorbent content 20 mass%, 30 μm) is arranged on the outer packaging material side, and h-PPa (water absorbent content 0 mass%, 20 μm) is arranged on the metal terminal side.

[0168] (Example 18)

[0169] A maleic anhydride-modified random polypropylene film (thickness 20 μm) containing 1% of CaO as a water absorbent was laminated on one side of a random polypropylene film (thickness 30 μm) containing 20% ​​of CaO as a water absorbent to produce a resin film for a storage device having a two-layer structure of r-PPa (water absorbent content 1% by mass, 20 μm) / r-PP (water absorbent content 20% by mass, 30 μm). The resin film for a storage device of Example 18 is an adhesive film for metal terminals, and is used in a manner in which r-PP (water absorbent content 20% by mass, 30 μm) is arranged on the outer packaging material side, and r-PPa (water absorbent content 1% by mass, 20 μm) is arranged on the metal terminal side.

[0170] (Example 19)

[0171] A random polypropylene film (30 μm thick) containing 20% ​​by mass of calcium oxide (CaO) as a water absorbent was laminated with a maleic anhydride-modified random polypropylene film (water absorbent content 0% by mass, thickness, 10 μm) on one surface, and a random polypropylene film (water absorbent content 0% by mass, thickness 10 μm) was laminated on the other surface to produce a resin film for a storage device having a three-layer structure of r-PPa (water absorbent content 0% by mass, 10 μm) / r-PP (water absorbent content 20% by mass, 30 μm) / r-PP (water absorbent content 0% by mass, 10 μm). The resin film for a storage device of Example 19 is an adhesive film for a metal terminal, and is used in a manner in which r-PP (water absorbent content 0% by mass, 10 μm) is arranged on the exterior material side, and r-PPa (water absorbent content 0% by mass, 10 μm) is arranged on the metal terminal side.

[0172] (Example 20)

[0173] A maleic anhydride-modified random polypropylene film (water absorbent content 0 mass%, thickness 10 μm) containing a black pigment was laminated on one side of a homopolypropylene film (thickness 30 μm) containing 20 mass% of calcium oxide (CaO) as a water absorbent, and a random polypropylene film (water absorbent content 0 mass%, thickness 10 μm) was laminated on the other side to produce a resin film for a storage device having a three-layer structure of black r-PPa (water absorbent content 0 mass%, 10 μm) / h-PP (water absorbent content 20 mass%, 30 μm) / r-PP (water absorbent content 0 mass%, 10 μm). The resin film for a storage device of Example 20 is an adhesive film for a metal terminal, and is used in a manner in which the black r-PPa (water absorbent content 0 mass%, 10 μm) is arranged on the metal terminal side, and the r-PP (water absorbent content 0 mass%, 10 μm) is arranged on the exterior material side.

[0174] (Comparative Example 1)

[0175] A random polypropylene film (water absorbing agent content: 12 mass %, 50 μm, single layer structure) containing 12 mass % of CaO as a water absorbing agent was used as a resin film for an electricity storage device.

[0176] (Comparative Example 2)

[0177] A random polypropylene film (water absorbing agent content 0 mass %, 50 μm, single layer structure) was used as the resin film for the power storage device.

[0178] (Comparative Example 3)

[0179] A random polypropylene film (water absorbent content: 12 mass%, thickness: 10 μm) containing 12 mass% of CaO was laminated on both surfaces of a random polypropylene film (thickness: 30 μm) containing 12 mass% of CaO as a water absorbent, to produce a resin film for a storage device having a three-layer structure of r-PP (water absorbent content: 12 mass%, 10 μm) / r-PP (water absorbent content: 12 mass%, 30 μm) / r-PP (water absorbent content: 12 mass%, 10 μm).

[0180] <Evaluation of water absorption of resin film>

[0181] A 10 cm square resin film (a resin film dried by standing in a vacuum oven (-50 MPa) for 24 hours immediately after the resin film is made) is prepared and immersed in warm water at 80°C. The water absorption is calculated based on the weight of the resin film before and after the immersion, and the state in which the water absorbent in the resin film absorbs 100% of the water is taken as the disappearance of the weight change of the resin film caused by the immersion. The weight increase per unit area at this time is taken as the water absorption performance (water release (g / m 2 )). The detection limit is 0.1 mg / m 2 The results are shown in Table 1.

[0182] Moisture absorption performance (g / m 2 ) = (weight of resin film after immersion (g) - weight of resin film before immersion (g)) / area of ​​resin film after immersion (m 2 ).

[0183] <Evaluation of insulation properties of resin film after water absorption>

[0184] The insulation was evaluated in accordance with the provisions of JIS C 2110-1:2016. Specifically, the test environment was set to 23°C in the atmosphere, and the dielectric breakdown strength was measured for each of the five resin films obtained in the above <Evaluation of water absorption of resin film> after absorbing water. Based on the average value of the dielectric breakdown strength (the dielectric breakdown voltage was converted to unit thickness) of each of the five films, the evaluation was performed according to the following criteria. The results are shown in Table 1. The measurement conditions are as follows.

[0185] Boost method: short time method (AC, 50Hz)

[0186] Boost speed: 0.3kV / s

[0187] electrode: cylinder / cylinder

[0188] Device: Insulation breakdown test device YST-243-100RHO (YAMAYO tester (available))

[0189] (Evaluation Criteria)

[0190] A': Dielectric breakdown strength is above 100kV / mm

[0191] A: Dielectric breakdown strength is 50kV / mm or more and less than 100kV / mm

[0192] B: Dielectric breakdown strength is 40kV / mm or more and less than 50kV / mm

[0193] C: Dielectric breakdown strength is less than 40kV / mm

[0194] (Preparation of Metal Terminal with Adhesive Film for Metal Terminal)

[0195] Using the adhesive films for metal terminals of Examples 8, 16 to 20, metal terminals with adhesive films for metal terminals were prepared respectively. Aluminum alloy foil (JIS H 4160: 1994A8079H-O) with a thickness of 400μm×TD45mm×MD60mm was used as a metal terminal, and it was sintered with a treatment agent composed of three components: acrylic resin, chromium (III) nitrate compound, and phosphoric acid in a manner that the treatment layer had a thickness of about 100nm to prepare a surface-treated metal terminal. Next, two pieces of adhesive films for metal terminals cut into a size of TD10mm×MD55mm were prepared, and the two pieces of adhesive films for metal terminals were arranged on both sides at a position 10mm away from the longitudinal end of the surface-treated metal terminal in a manner that the center of the width direction of the surface-treated metal terminal was aligned with the center of the width direction of the surface-treated metal terminal. Next, a metal terminal with an adhesive film for metal terminal, in which an adhesive film for metal terminal / surface-treated metal terminal / adhesive film for metal terminal are sequentially laminated, was prepared by heat-sealing at 190°C×0.25MPa (surface pressure applied to the silicone rubber)×16 seconds using a flat plate press machine with a metal head having a thickness of 3.0mm and a hardness of 40 attached to the top and bottom. At this time, the MD of the metal terminal was arranged to be orthogonal to the MD of the adhesive film for metal terminal.

[0196] <Evaluation of Adhesion of Adhesive Film for Metal Terminal>

[0197] An exterior material for a storage device (hereinafter sometimes referred to as an "exterior material") is produced. A substrate layer (30 μm thick) composed of a polyethylene terephthalate film (12 μm thick) / adhesive layer (3 μm thick) / nylon film (15 μm thick) is laminated on an aluminum alloy foil (40 μm thick JIS H4160: 1994A8079H-O) by dry lamination, and a heat-welded resin layer is laminated on the other side by co-extrusion. Specifically, a two-component urethane adhesive (polyol compound and aromatic isocyanate compound) is applied on the nylon film to form an adhesive layer (3 μm thick) on the nylon film. Next, an adhesive layer and a polyethylene terephthalate film are laminated on the nylon film to produce a substrate layer. Next, a two-component urethane adhesive (polyol compound and aromatic isocyanate compound) is applied to one side of the barrier layer composed of aluminum alloy foil to form an adhesive layer (thickness 3 μm) on the aluminum alloy foil. Next, after laminating the adhesive layer and the base layer with the nylon film side as the bonding surface on the aluminum alloy foil, an aging treatment is performed to produce a laminate of base layer / adhesive layer / barrier layer. Next, an adhesive layer (thickness 40 μm, arranged on the metal layer side) formed of maleic anhydride modified polypropylene resin and a heat-fusible resin layer (thickness 40 μm, innermost layer) formed of random polypropylene resin are coextruded on the barrier layer of the laminate, thereby laminating the adhesive layer / heat-fusible resin layer on the barrier layer to obtain an external packaging material for a storage device having a base layer, an adhesive layer, a barrier layer, an adhesive layer, and a heat-fusible resin layer laminated in sequence.

[0198] Next, the outer material is cut into a size of TD60mm and MD200mm, and the outer material's heat-melting resin layer is made to be opposite to each other in a manner that the heat-melting resin layer is on the inside, and the metal terminal with the adhesive film obtained above is clamped between the relative heat-melting resin layers. At this time, the MD and TD of the outer material are stacked in a manner that is consistent with the TD direction and MD direction of the metal terminal with the adhesive film for the metal terminal. In this state, a heat seal tester is used to perform heat sealing under the conditions of 7mm width, 190℃×0.25MPa×16 seconds, and naturally cooled to 25℃ to obtain a laminate formed by heat-melting the outer material and the adhesive film. The 7mm width is the direction of the MD of the outer material. Among them, these heat sealing conditions are temperature conditions suitable for the resin used for the adhesive film for the metal terminal. The heat-sealed portion of the obtained laminate becomes a structure in which the outer material / adhesive film for metal terminal / metal terminal / adhesive film for metal terminal / outer material are stacked in sequence. Next, cut the laminate in a direction at right angles to the sealing width of 7 mm to obtain a sample with a width of 15 mm. At this time, the sample is taken from the center of the laminate. The width of 15 mm is the TD direction of the exterior material. Next, clamp the exterior material and metal terminal on one side of the sample, stretch the exterior material and metal terminal in the 180°C direction at a speed of 50 mm / min, and measure the sealing strength. These measurements are carried out at 25°C 50%. The sealing of the metal terminal is evaluated according to the following criteria. The results are shown in Table 2.

[0199] A: The sealing strength is 20N / 15mm or more.

[0200] B: The sealing strength is 10 N / 15 mm or more and less than 20 N / 15 mm.

[0201] C: Sealing strength is less than 10N / 15mm.

[0202] [Table 1]

[0203]

[0204] [Table 2]

[0205]

[0206] As described above, the present invention provides the following aspects of the invention.

[0207] Item 1. A resin film for an electricity storage device, wherein

[0208] The resin film for a power storage device is composed of two or more layers.

[0209] The two or more layers include at least one layer A and at least one layer B, wherein the content of the water absorbing agent in the layer A is 5% by mass or more, and the content of the water absorbing agent in the layer B is less than 5% by mass.

[0210] Item 2. The resin film for an electricity storage device according to Item 1, wherein the content of the water absorbing agent in at least one layer of the layer B is 0%.

[0211] Item 3. The resin film for an electricity storage device according to Item 1 or 2, wherein the content of solid particles in at least one layer among the two or more layers is less than 5% by mass.

[0212] Item 4. The resin film for an electricity storage device according to any one of Items 1 to 3, wherein the water absorbing agent contains an inorganic water absorbing agent.

[0213] Item 5. The resin film for a power storage device according to any one of Items 1 to 4, wherein the water absorbing agent comprises at least one selected from the group consisting of calcium oxide, anhydrous magnesium sulfate, magnesium oxide, calcium chloride, zeolite, alumina, silica gel, alumina gel, and burnt alum.

[0214] Item 6. The resin film for a power storage device according to any one of Items 1 to 5, wherein at least one layer among the two or more layers contains a thermally fusible resin.

[0215] Item 7. The resin film for a power storage device according to Item 6, wherein the thermally fusible resin contains at least one selected from the group consisting of polyesters and polyolefins.

[0216] Item 8. The resin film for a power storage device according to any one of Items 1 to 7, wherein the dielectric breakdown strength of the resin film for a power storage device after water absorption measured by the following measurement method is 40 kV / mm or more.

[0217] (Measurement of dielectric breakdown strength after water absorption)

[0218] Prepare a 10 cm square resin film for storage devices, immerse it in 80°C warm water, and continue immersing until the water absorbent in the resin film for storage devices absorbs 100% of the water, thereby obtaining the resin film for storage devices after water absorption. The water absorption of the resin film for storage devices is calculated from the weight of the film before and after immersion. Next, according to the provisions of JIS C 2110-1:2016, the measurement environment is 23°C in the atmosphere, the boost method is the short-time method (AC, 50Hz), the boost speed is 0.3kV / s, and the electrode is cylinder / The dielectric breakdown strength of the resin film for power storage devices after water absorption was measured under the cylindrical measurement condition. The measured value is the average value of the measurements of 5 samples.

[0219] Item 9. A resin film for an electrical storage device as described in any one of Items 1 to 8, wherein the resin film for an electrical storage device: 1) is arranged between an outer packaging material for an electrical storage device and an electrical storage device element; or 2) is used as a heat-fusible resin layer of an outer packaging material for an electrical storage device; or 3) is used as an adhesive layer between a barrier layer and a heat-fusible resin layer of an outer packaging material for an electrical storage device; or 4) is used as an adhesive film for a metal terminal between a metal terminal electrically connected to an electrode of an electrical storage device element and an outer packaging material for an electrical storage device that seals the electrical storage device element.

[0220] Item 10. An electric storage device, comprising an electric storage device element having at least a positive electrode, a negative electrode and an electrolyte housed in a package formed of an outer material, wherein:

[0221] The resin film for an electricity storage device according to any one of items 1 to 9 is arranged between the exterior material and the electricity storage device.

[0222] Description of Reference Numerals

[0223] 1Resin film for power storage devices

[0224] 2 Metal terminals

[0225] 3Exterior materials

[0226] 3a The peripheral part of the exterior material

[0227] 4Electrical storage device components

[0228] 10Electrical storage devices

[0229] 11First Floor

[0230] 12 Second Floor

[0231] 13Third floor

[0232] 21 Adhesive film for metal terminals

[0233] 31 base material layer

[0234] 32 Adhesive layer

[0235] 33 barrier layer

[0236] 34 Adhesive layer

[0237] 35: Thermally fusible resin layer.

Claims

1. A resin film for an electric storage device, characterized in that: The resin film for a power storage device is composed of two or more layers. The two or more layers include at least one layer A and at least one layer B, wherein the content of the water absorbing agent in the layer A is 5% by mass or more, and the content of the water absorbing agent in the layer B is less than 5% by mass.

2. The resin film for an electric storage device according to claim 1, wherein: The content of the water absorbing agent in at least one layer of the layer B is 0%.

3. The resin film for an electric storage device according to claim 1 or 2, wherein: The content of solid particles in at least one layer among the two or more layers is less than 5% by mass.

4. The resin film for an electric storage device according to claim 1 or 2, wherein: The water absorbing agent includes an inorganic water absorbing agent.

5. The resin film for an electric storage device according to claim 1 or 2, wherein: The water absorbing agent comprises at least one selected from the group consisting of calcium oxide, anhydrous magnesium sulfate, magnesium oxide, calcium chloride, zeolite, aluminum oxide, silica gel, aluminum oxide gel and burnt alum.

6. The resin film for an electric storage device according to claim 1 or 2, wherein: At least one layer among the two or more layers contains a thermally fusible resin.

7. The resin film for an electric storage device according to claim 6, wherein: The thermally fusible resin includes at least one selected from polyester and polyolefin.

8. The resin film for an electric storage device according to claim 1 or 2, wherein: The dielectric breakdown strength of the resin film for a power storage device after absorbing water measured by the following measurement method is 40 kV / mm or more. The method for measuring the dielectric breakdown strength after water absorption is: A 10 cm square resin film for a storage device was prepared and immersed in warm water at 80°C. The immersion was continued until the water absorbent in the resin film for the storage device absorbed 100% of the water, thereby obtaining the resin film for the storage device after water absorption. Then, the water absorption of the resin film for the storage device was calculated from the weight of the film before and after the immersion. Then, according to the provisions of JIS C 2110-1:2016, the dielectric breakdown strength of the resin film for the storage device after water absorption was measured under the measurement conditions of 23°C in the atmosphere, the boost method was the short time method, 50 Hz AC voltage was used, the boost speed was 0.3 kV / s, and the electrode was 25 mmφ cylinder / 75 mmφ cylinder. The measured value was the average value of the measurements of 5 samples.

9. The resin film for an electric storage device according to claim 1 or 2, wherein: The resin film for a storage device is: 1) arranged between a storage device outer packaging material and a storage device element; or, 2) used as a heat-fusible resin layer of a storage device outer packaging material; or, 3) used as an adhesive layer between a barrier layer and a heat-fusible resin layer of a storage device outer packaging material; Alternatively, 4) it is used as an adhesive film for metal terminals interposed between a metal terminal electrically connected to an electrode of an electric storage device element and an outer packaging material for an electric storage device that seals the electric storage device element.

10. An electric storage device, wherein an electric storage device element having at least a positive electrode, a negative electrode and an electrolyte is housed in a package formed of an outer packaging material, characterized in that: The resin film for an electricity storage device according to claim 1 or 2 is disposed between the exterior material and the electricity storage device.

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