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

Abstract

To provide an exterior material for a power storage device, which is composed of a laminate including a base material layer, a barrier layer, and an inner layer in this order, and has excellent sealing performance in a high temperature environment.SOLUTION: An exterior material for a power storage device is composed of a laminate including at least a base material layer, a barrier layer, and an inner layer in this order, and the inner layer includes an adhesive layer and a heat-sealing resin layer from the barrier layer side. When the dynamic viscoelasticity measurement by tension is performed on the inner layer, the elongation rate at 80°C is 8.0% or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to an exterior material for an electricity storage device, a method for producing the same, and an electricity storage device. [Background technology]

[0002] Various types of electricity storage devices have been developed, and in all of them, exterior materials are essential components for sealing the electricity storage device elements such as electrodes and electrolytes. Conventionally, metal exterior materials have been widely used as exterior materials for electricity storage devices.

[0003] Meanwhile, along with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., electricity storage devices are being required to have a variety of shapes as well as to be thinner and lighter in weight. However, the metallic exterior materials for electricity storage devices that have been widely used up until now have the drawbacks of being difficult to keep up with the diversification of shapes and also having limitations on how much they can be made lighter.

[0004] Therefore, in recent years, a film-like laminate in which a base layer / barrier layer / adhesive layer / thermally adhesive resin layer are laminated in this order has been proposed as an exterior material for an electricity storage device that can be easily processed into a variety of shapes and can be made thinner and lighter (see, for example, Patent Document 1).

[0005] In such an electrical storage device packaging material, a recess is generally formed by cold forming, and electrical storage device elements such as electrodes and electrolyte are placed in the space formed by the recess, and a heat-sealable resin layer is heat-sealed to obtain an electrical storage device in which the electrical storage device elements are housed inside the electrical storage device packaging material. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-287971 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-101778 Summary of the Invention [Problem to be solved by the invention]

[0007] Depending on the application, an electricity storage device may be placed in a high-temperature environment. For example, an in-vehicle electricity storage device is expected to be used in a high-temperature environment. When an electricity storage device is placed in a high-temperature environment, gas may be generated from the electrolyte solution contained inside the electricity storage device, causing an increase in internal pressure. Therefore, electricity storage devices are required to have high sealing properties in a high-temperature environment.

[0008] However, in the above-mentioned film-like electrical storage device packaging material, the electrical storage device elements are sealed by heat-sealing the heat-sealable resin layers together, and the adhesive layer and the heat-sealable resin layer located inside the barrier layer are likely to soften in a high-temperature environment. As a result, when the internal pressure of the electrical storage device increases in a high-temperature environment, at least one of the adhesive layer and the heat-sealable resin layer may be destroyed, and the electrical storage device packaging material may not be able to maintain the sealing of the electrical storage device elements.

[0009] Under these circumstances, a first embodiment of the present disclosure has a primary object to provide an exterior packaging material for an electricity storage device that is composed of a laminate having at least a base layer, a barrier layer, and an inner layer in this order, and that has excellent sealing properties in high-temperature environments.

[0010] In addition, in the above-mentioned film-like packaging material for an electricity storage device, a polypropylene-based resin such as acid-modified polypropylene may be used as a material for forming an adhesive layer that bonds the barrier layer and the heat-sealable resin layer. For example, when the adhesive layer is formed from a polypropylene-based resin, polyethylene may be blended into the polypropylene-based resin in order to improve processability and flexibility.

[0011] However, polypropylene-based resins and polyethylene are not highly compatible. For example, when a small amount of polyethylene is added to a polypropylene-based resin and a heat-sealable resin layer is formed by melt extrusion molding, a sea-island structure is formed in which polyethylene islands are dispersed in the sea of the polypropylene-based resin (note that, to observe this sea-island structure, a cross section of the heat-sealable resin layer is stained with ruthenium tetroxide or the like, and a cross-sectional image is obtained and observed using a scanning electron microscope).

[0012] When a large stress is applied to a packaging material for an electricity storage device provided with an adhesive layer in which such a sea-island structure is observed in a high-temperature environment, the mechanical strength of the adhesive layer located inside the barrier layer is likely to decrease. As a result, when the internal pressure of the electricity storage device increases in a high-temperature environment, the adhesive layer may be destroyed, and the packaging material for an electricity storage device may not be able to maintain the hermetic sealing of the electricity storage device element.

[0013] Under these circumstances, a second embodiment of the present disclosure has a main object to provide an exterior packaging material for an electricity storage device that is composed of a laminate having at least a base material layer, a barrier layer, an adhesive layer, and a heat-sealable resin layer in this order, and that has excellent sealing properties in high-temperature environments.

[0014] In addition, in the above-mentioned film-like packaging material for an electricity storage device, a polyolefin such as polypropylene may be used as a material for forming the heat-sealable resin layer. For example, when polypropylene is used to form the heat-sealable resin layer, polyethylene may be used in combination to improve processability and flexibility.

[0015] However, polypropylene and polyethylene are not highly compatible. For example, when a small amount of polyethylene is added to polypropylene and a heat-sealable resin layer is formed by melt extrusion molding, a sea-island structure is formed in which polyethylene islands are dispersed in a polypropylene sea (note that, to observe this sea-island structure, a cross section of the heat-sealable resin layer is stained with ruthenium tetroxide or the like, and a cross-sectional image is obtained and observed using a scanning electron microscope). For this reason, when an electrical storage device packaging material is subjected to the above-mentioned cold molding, the stress applied during molding can cause fine cracks to form at the interface between the polypropylene and polyethylene portions of the heat-sealable resin layer, which can lead to whitening of the heat-sealable resin layer and a decrease in the insulating properties of the electrical storage device packaging material.

[0016] For example, Patent Document 2 describes that when the inner layer of a battery exterior material is made of a mixture of polypropylene resin and polyethylene resin, the seal strength between the heat-sealed inner layers can be controlled by controlling the size and number of "islands" by controlling the manufacturing conditions of the battery exterior material, the thickness of the inner layer, the mixing ratio of the polypropylene resin and the polyethylene resin, etc., and that in a mixture with an island-in-sea structure, the particle size of the polyethylene resin, which is the size of the "islands," is in the range of 0.5 to 5 μm (i.e., 0.196 to 19.6 μm). 2 It is stated that it is preferable that the temperature is about 100°C.

[0017] However, through investigations, the inventors of the present disclosure have found that in conventional battery exterior materials in which polypropylene and polyethylene are blended in the inner layer, as disclosed in Patent Document 2, the particle size of the polyethylene resin is large, and whitening and deterioration of insulating properties due to molding cannot be sufficiently suppressed.

[0018] Under these circumstances, a third embodiment of the present disclosure has a main object to provide an exterior packaging material for an electricity storage device that includes a heat-sealable resin layer containing polypropylene and polyethylene, and that is suppressed from whitening and deterioration in insulation properties due to molding. [Means for solving the problem]

[0019] The inventors of the present disclosure conducted extensive research to solve the problems of the invention according to the first embodiment as described above. As a result, they found that, in a packaging material for an electricity storage device constituted by a laminate including at least a base layer, a barrier layer, and an inner layer in this order, when dynamic viscoelasticity measurement was performed on the inner layer under tension, a packaging material for an electricity storage device having an elongation rate of 8.0% or less at 80°C has excellent sealing properties in a high-temperature environment.

[0020] The first embodiment of the present disclosure was completed based on these findings and further investigations. That is, the first embodiment of the present disclosure provides the invention of the following aspects. The laminate is composed of at least a substrate layer, a barrier layer, and an inner layer in this order, the inner layer includes an adhesive layer and a heat-sealable resin layer from the barrier layer side, The outer casing material for an electricity storage device, wherein when the inner layer is subjected to dynamic viscoelasticity measurement under tension, the elongation rate at 80°C is 8.0% or less.

[0021] The inventors of the present disclosure have conducted extensive studies to solve the problems of the invention according to the second embodiment as described above. As a result, they have found a laminate comprising at least a base layer, a barrier layer, an adhesive layer, and a thermally adhesive resin layer in this order, the adhesive layer containing a polypropylene-based resin and polyethylene, in which a sea-island structure is observed in a cross-sectional image obtained using a scanning electron microscope of a cross section of the adhesive layer in a direction parallel to the transverse direction (TD) and in the thickness direction, the cross-sectional image being a cross-sectional image obtained within a range from the surface of the adhesive layer on the barrier layer side to a portion of the thickness that is 25% of the thickness when the thickness of the adhesive layer is taken as 100%, and in the cross-sectional image, the area of the island portions relative to the total number of island portions in the sea-island structure is 0.25 μm 2 The ratio of the total number of islands smaller than 0.25 μm is 40% or more (i.e., 2 The inventors have found that when the ratio of the total number of island portions to the total number of all island portions is ≧40%), the packaging material for an electricity storage device has excellent sealing properties in a high-temperature environment.

[0022] The second embodiment of the present disclosure was completed based on these findings and further investigations. That is, the second embodiment of the present disclosure provides the invention of the following aspects. The laminate is composed of at least a base layer, a barrier layer, an adhesive layer, and a heat-sealable resin layer in this order, the adhesive layer contains a polypropylene-based resin and polyethylene, a sea-island structure is observed in a cross-sectional image of the adhesive layer taken in a direction parallel to the TD and in the thickness direction, the cross-sectional image being obtained using a scanning electron microscope; the cross-sectional image is a cross-sectional image obtained within a range from the surface of the adhesive layer on the barrier layer side to a portion of the adhesive layer that is 25% of the thickness of the adhesive layer, where the thickness of the adhesive layer is 100%, In the cross-sectional image, the area of the island portion is 0.25 μm with respect to the total number of island portions of the sea-island structure. 2 The proportion of the total number of island portions smaller than this is 40% or more.

[0023] The inventors of the present disclosure have conducted extensive research to solve the problems of the invention according to the third embodiment as described above. As a result, they have found a laminate including, from the outside to the inside, at least a base layer, a barrier layer, and a thermally adhesive resin layer in this order, the thermally adhesive resin layer containing polypropylene and polyethylene, a sea-island structure is observed in a cross-sectional image obtained using a scanning electron microscope of a cross section of the thermally adhesive resin layer in a direction parallel to the transverse direction (TD) and in the thickness direction, and in the cross-sectional image, the area of the island portions of the sea-island structure is 0.02 μm 2 The ratio of the total number of islands below is 8 It has been found that an electrical storage device packaging material having a SiO2 content of 0.0% or more and containing at least one of an antioxidant and a radical scavenger in at least one layer inside the barrier layer suppresses whitening and a decrease in insulation properties due to molding. The cross-sectional image is a cross-sectional image acquired within a range of 12.5% of the thickness from the surface of the thermally adhesive resin layer opposite the barrier layer, assuming the total thickness of the layers inside the barrier layer to be 100%. The MD and TD directions of the thermally adhesive resin layer laminated on the laminate can generally be determined from the barrier layer described below. That is, in an electrical storage device packaging material, the MD and TD directions of the barrier layer described below can generally be determined during its manufacturing process. For example, when the barrier layer is made of aluminum foil, linear lines known as rolling marks are formed on the surface of the aluminum foil in the rolling direction (RD) of the aluminum foil. Since the rolling marks extend along the rolling direction, the rolling direction of the aluminum foil can be determined by observing the surface of the aluminum foil. In addition, in the manufacturing process of the laminate, the MD of the laminate and the RD of the aluminum foil generally coincide, so by observing the surface of the aluminum foil of the laminate and identifying the rolling direction (RD) of the aluminum foil, the MD of the laminate (i.e., the MD of the heat-fusible resin layer) can be identified. In addition, since the TD of the laminate is perpendicular to the MD of the laminate, the TD of the laminate (i.e., the TD of the heat-fusible resin layer) can also be identified.

[0024] The third embodiment of the present disclosure was completed based on these findings and further investigations, and provides the following aspects of the invention. The laminate is composed of a base material layer, a barrier layer, and a heat-sealable resin layer, arranged in this order from the outside to the inside, the heat-sealable resin layer contains polypropylene and polyethylene, a sea-island structure is observed in a cross-sectional image of the heat-fusion resin layer taken in a direction parallel to the TD and in the thickness direction, the cross-sectional image being obtained using a scanning electron microscope; the cross-sectional image is a cross-sectional image obtained within a range of a thickness of 12.5% from the surface of the thermal adhesive resin layer opposite to the barrier layer side, where the total thickness of layers located inside the barrier layer is taken as 100%, and In the cross-sectional image, the area of the island portion is 0.02 μm with respect to the total number of island portions of the sea-island structure. 2 The total number of the following islands is 80.0% or more: The packaging material for an electricity storage device comprises at least one of an antioxidant and a radical scavenger in at least one of the layers located on the inner side of the barrier layer. [Effects of the Invention]

[0025] According to the first embodiment of the present disclosure, it is possible to provide an electrical storage device packaging material that is composed of a laminate having at least a base layer, a barrier layer, and an inner layer in this order, and that has excellent sealing properties in high-temperature environments. Furthermore, according to the first embodiment of the present disclosure, it is also possible to provide a method for manufacturing an electrical storage device packaging material, and an electrical storage device.

[0026] Furthermore, according to a second embodiment of the present disclosure, it is possible to provide a packaging material for an electricity storage device that is composed of a laminate having at least a base layer, a barrier layer, an adhesive layer, and a heat-sealable resin layer in this order, and that has excellent sealing properties in a high-temperature environment. Furthermore, according to the second embodiment of the present disclosure, it is also possible to provide a method for manufacturing a packaging material for an electricity storage device, and an electricity storage device.

[0027] According to the third embodiment of the present disclosure, it is possible to provide a packaging material for an electricity storage device that includes a heat-sealable resin layer containing polypropylene and polyethylene and that is suppressed from whitening and deterioration in insulation properties due to molding. Furthermore, according to the third embodiment of the present disclosure, it is also possible to provide a method for manufacturing a packaging material for an electricity storage device, and an electricity storage device. [Brief explanation of the drawings]

[0028] [Figure 1]1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to a first embodiment of the present disclosure. [Figure 2] 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to a first embodiment of the present disclosure. [Figure 3] 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to a first embodiment of the present disclosure. [Figure 4] FIG. 2 is a schematic diagram illustrating a method for preparing a sample for a creep test in the examples. [Figure 5] FIG. 2 is a schematic diagram for explaining a method for conducting a creep test in the examples. [Figure 6] FIG. 2 is a schematic diagram illustrating a method for housing an electricity storage device element in a package formed from the exterior packaging material for an electricity storage device of the present disclosure. [Figure 7] FIG. 1 is a schematic diagram of a graph showing the relationship between elongation (%) and temperature (° C.) obtained by dynamic viscoelasticity measurement. [Figure 8] 1 is a cross-sectional image (SEM image) in the thickness direction of the packaging material for an electricity storage device of Example 1A after a creep test. [Figure 9] 1 is a cross-sectional image (SEM image) in the thickness direction of the packaging material for an electricity storage device of Comparative Example 1A after a creep test. [Figure 10] FIG. 4 is a schematic view showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to a second embodiment. [Figure 11] FIG. 4 is a schematic view showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to a second embodiment. [Figure 12] FIG. 4 is a schematic view showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to a second embodiment. [Figure 13] FIG. 4 is a schematic view showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to a second embodiment. [Figure 14] 1 is a graph showing the relationship between the area (μm 2 ) of the island portions and the percentage (%) of the number of island portions of each area to the total number of all island portions in the adhesive layer of Example 1B. [Figure 15]10 is a graph showing the relationship between the area (μm 2 ) of the island portions and the percentage (%) of the number of island portions of each area to the total number of all island portions in the adhesive layer of Example 2B. [Figure 16] 10 is a graph showing the relationship between the area (μm 2 ) of the island portions and the percentage (%) of the number of island portions of each area to the total number of all island portions in the adhesive layer of Example 3B. [Figure 17] 10 is a graph showing the relationship between the area (μm 2 ) of the island portions and the percentage (%) of the number of island portions of each area to the total number of all island portions in the adhesive layer of Example 4B. [Figure 18] 10 is a graph showing the relationship between the area (μm 2 ) of the island portions and the percentage (%) of the number of island portions of each area to the total number of all island portions in the adhesive layer of Comparative Example 1B. [Figure 19] FIG. 10 is a schematic view showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to a third embodiment. [Figure 20] FIG. 10 is a schematic view showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to a third embodiment. [Figure 21] FIG. 10 is a schematic view showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to a third embodiment. [Figure 22] FIG. 10 is a schematic view showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0029] The packaging material for an electricity storage device according to the first embodiment of the present disclosure is composed of a laminate including at least a base material layer, a barrier layer, and an inner layer in this order, and is characterized in that when dynamic viscoelasticity measurement is performed on the inner layer under tension, the elongation at 80°C is 8.0% or less.

[0030] According to the packaging material for an electricity storage device according to the first embodiment of the present disclosure, by virtue of having this configuration, when the heat-sealable resin layers are heat-sealed to each other, the heat-sealable resin layers have high adhesion to each other in a high-temperature environment, and can exhibit excellent sealing properties in a high-temperature environment.

[0031] An exterior packaging material for an electricity storage device according to a second embodiment of the present disclosure is composed of a laminate including at least a base material layer, a barrier layer, an adhesive layer, and a heat-sealable resin layer in this order, the adhesive layer containing a polypropylene-based resin and polyethylene, a sea-island structure is observed in a cross-sectional image obtained using a scanning electron microscope of a cross section of the adhesive layer in a direction parallel to the TD and in the thickness direction, the cross-sectional image being a cross-sectional image obtained within a range from the surface of the adhesive layer on the barrier layer side to a portion that is 25% of the thickness when the thickness of the adhesive layer is taken as 100%, and in the cross-sectional image, an area of the island portions relative to the total number of island portions in the sea-island structure is 0.25 μm 2 The proportion of the total number of island portions less than 100% is 40% or more. The packaging material for an electricity storage device according to the second embodiment of the present disclosure has this configuration and is therefore excellent in sealing properties in high-temperature environments.

[0032] An exterior packaging material for an electricity storage device according to a third embodiment of the present disclosure is composed of a laminate including, from outside to inside, at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order, the heat-sealable resin layer containing polypropylene and polyethylene, a sea-island structure is observed in a cross-sectional image obtained using a scanning electron microscope of a cross section of the heat-sealable resin layer in a direction parallel to the TD and in the thickness direction, the cross-sectional image being a cross-sectional image obtained within a range of 12.5% of the thickness from the surface of the heat-sealable resin layer opposite to the barrier layer side, where the total thickness of layers located inside the barrier layer is taken as 100%, and in the cross-sectional image, the area of the island portions relative to the total number of island portions in the sea-island structure is 0.02 μm 2 The packaging material for an electricity storage device according to the third embodiment of the present disclosure is characterized in that the ratio of the total number of the following island portions is 80.0% or more, and at least one of an antioxidant and a radical scavenger is contained in at least one of the layers located inside the barrier layer. By having this configuration, whitening and a decrease in insulating properties due to molding are suppressed.

[0033] The packaging material for an electricity storage device of the present disclosure will be described in detail below. In this specification, a numerical range indicated by "to" means "not less than" or "not more than." For example, the expression "2 to 15 mm" means 2 mm or more and 15 mm or less.

[0034] In the following description, matters specific to the first, second, or third embodiment of the present disclosure will be clearly indicated. Unless otherwise specified, when the present disclosure is described, the description will be about matters common to the first, second, and third embodiments.

[0035] In the packaging material for an electricity storage device, the MD (Machine Direction) and TD (Transverse Direction) of the barrier layer 3 described below can usually be determined during the manufacturing process. For example, when the barrier layer 3 is made of aluminum foil, linear streaks called rolling marks are formed on the surface of the aluminum foil in the rolling direction (RD) of the aluminum foil. Since the rolling marks extend along the rolling direction, the rolling direction of the aluminum foil can be determined by observing the surface of the aluminum foil. Furthermore, during the manufacturing process of a laminate, the MD of the laminate usually coincides with the RD of the aluminum foil, so the MD of the laminate can be identified by observing the surface of the aluminum foil of the laminate and identifying the rolling direction (RD) of the aluminum foil. Furthermore, since the TD of the laminate is perpendicular to the MD of the laminate, the TD of the laminate can also be identified.

[0036] Furthermore, when the MD of the electrical storage device packaging material cannot be determined from the rolling marks of the aluminum alloy foil, it can be determined by the following method. One method for determining the MD of an electrical storage device packaging material is to observe the cross section of the heat-sealable resin layer of the electrical storage device packaging material using an electron microscope to confirm the sea-island structure. In this method, the direction parallel to the cross section in which the average diameter of the island shapes in the direction perpendicular to the thickness direction of the heat-sealable resin layer is the largest can be determined as the MD. Specifically, the longitudinal cross section of the heat-sealable resin layer and each cross section at an angle of 10 degrees from the direction parallel to the longitudinal cross section to the direction perpendicular to the longitudinal cross section (a total of 10 cross sections) are observed using an electron microscope to confirm the sea-island structure. Next, the shape of each individual island is observed in each cross section. For each island shape, the linear distance connecting the leftmost end in the direction perpendicular to the thickness direction of the heat-sealable resin layer to the rightmost end in the perpendicular direction is defined as the diameter y. For each cross section, the average of the diameters y of the top 20 island shapes in order of largest diameter y is calculated. The direction parallel to the cross section where the average diameter y of the island shape was the largest was determined to be the MD.

[0037] 1.Layer structure and physical properties of exterior materials for energy storage devices As shown in FIG. 1 , for example, an electrical storage device packaging material 10 according to the first embodiment of the present disclosure is composed of a laminate including a base material layer 1, a barrier layer 3, and an inner layer (an adhesive layer 5 and a heat-sealable resin layer 4) in this order. In the electrical storage device packaging material 10, the base material layer 1 is the outermost layer, and the inner heat-sealable resin layer 4 is the innermost layer. When assembling an electrical storage device using the electrical storage device packaging material 10 and an electrical storage device element, the electrical storage device element is housed in a space formed by heat-sealing the peripheral portions of the electrical storage device packaging material 10 with the heat-sealable resin layers 4 of the electrical storage device packaging material 10 facing each other. In the laminate constituting the electrical storage device packaging material 10 according to the first embodiment of the present disclosure, with the barrier layer 3 as the reference, the heat-sealable resin layer 4 side of the barrier layer 3 is the inner side, and the base material layer 1 side of the barrier layer 3 is the outer side.

[0038] 2 and 3, the packaging material 10 for an electricity storage device according to the first embodiment may have an adhesive layer 2 between the base material layer 1 and the barrier layer 3, if necessary, for the purpose of improving the adhesion between these layers. Furthermore, as shown in FIG. 3, a surface coating layer 6 or the like may be provided on the outer side of the base material layer 1 (the side opposite to the heat-sealable resin layer 4 side), if necessary.

[0039] Furthermore, as shown in Fig. 10, for example, an electrical storage device packaging material 10 according to a second embodiment of the present disclosure is composed of a laminate including a base material layer 1, a barrier layer 3, an adhesive layer 5, and a heat-sealable resin layer 4 in this order. In the electrical storage device packaging material 10, the base material layer 1 is the outermost layer, and the heat-sealable resin layer 4 is the innermost layer. When assembling an electrical storage device using the electrical storage device packaging material 10 and an electrical storage device element, the electrical storage device element is housed in a space formed by heat-sealing the peripheral portions of the electrical storage device packaging material 10 with the heat-sealable resin layers 4 facing each other.

[0040] 11 to 13, the packaging material 10 for an electricity storage device according to the second embodiment may have an adhesive layer 2 between the base material layer 1 and the barrier layer 3, if necessary, for the purpose of improving the adhesion between these layers. Furthermore, as shown in FIG. 13, a surface coating layer 6 or the like may be provided on the outer side of the base material layer 1 (the side opposite to the heat-sealable resin layer 4 side) if necessary.

[0041] Furthermore, as shown in Fig. 19, for example, an electrical storage device packaging material 10 according to a third embodiment of the present disclosure is composed of a laminate including a base material layer 1, a barrier layer 3, and a heat-sealable resin layer 4 in this order. In the electrical storage device packaging material 10, the base material layer 1 is the outermost layer, and the heat-sealable resin layer 4 is the innermost layer. When assembling an electrical storage device using the electrical storage device packaging material 10 and an electrical storage device element, the electrical storage device element is housed in a space formed by heat-sealing the peripheral portions of the electrical storage device packaging material 10 with the heat-sealable resin layers 4 facing each other.

[0042] 20 to 22, for example, the packaging material 10 for an electricity storage device according to the third embodiment may have an adhesive layer 2 between the base material layer 1 and the barrier layer 3, if necessary, for the purpose of increasing the adhesion between these layers. Furthermore, as shown in FIGS. 21 and 22, for example, the packaging material 10 for an electricity storage device according to the third embodiment may have an adhesive layer 5 between the barrier layer 3 and the heat-sealable resin layer 4, if necessary, for the purpose of increasing the adhesion between these layers. Furthermore, as shown in FIG. 22, a surface coating layer 6 or the like may be provided on the outer side of the base material layer 1 (the side opposite to the heat-sealable resin layer 4 side), if necessary.

[0043] Furthermore, as shown in Fig. 19, for example, an electrical storage device packaging material 10 according to a third embodiment of the present disclosure is composed of a laminate including a base material layer 1, a barrier layer 3, and a heat-sealable resin layer 4 in this order. In the electrical storage device packaging material 10, the base material layer 1 is the outermost layer, and the heat-sealable resin layer 4 is the innermost layer. When assembling an electrical storage device using the electrical storage device packaging material 10 and an electrical storage device element, the electrical storage device element is housed in a space formed by heat-sealing the peripheral portions of the electrical storage device packaging material 10 with the heat-sealable resin layers 4 facing each other.

[0044] 20 to 22, for example, the packaging material 10 for an electricity storage device according to the third embodiment may have an adhesive layer 2 between the base material layer 1 and the barrier layer 3, if necessary, for the purpose of increasing the adhesion between these layers. Furthermore, as shown in FIGS. 21 and 22, for example, the packaging material 10 for an electricity storage device according to the third embodiment may have an adhesive layer 5 between the barrier layer 3 and the heat-sealable resin layer 4, if necessary, for the purpose of increasing the adhesion between these layers. Furthermore, as shown in FIG. 22, a surface coating layer 6 or the like may be provided on the outer side of the base material layer 1 (the side opposite to the heat-sealable resin layer 4 side), if necessary.

[0045] In the present disclosure, the thickness of the laminate constituting the electricity storage device packaging material 10 is not particularly limited, but from the viewpoints of cost reduction, improving energy density, etc., it is, for example, about 190 μm or less, preferably about 180 μm or less, about 155 μm or less, or about 120 μm or less. Furthermore, from the viewpoint of maintaining the function of the electricity storage device packaging material 10, which is to protect the electricity storage device elements, the thickness of the laminate constituting the electricity storage device packaging material 10 is preferably about 35 μm or more, about 45 μm or more, or about 60 μm or more. Furthermore, preferred ranges for the laminate constituting the packaging material 10 for an electricity storage device include, for example, about 35 to 190 μm, about 35 to 180 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 190 μm, about 45 to 180 μm, about 45 to 155 μm, about 45 to 120 μm, about 60 to 190 μm, about 60 to 180 μm, about 60 to 155 μm, and about 60 to 120 μm, with about 60 to 155 μm being particularly preferred.

[0046] In the electrical storage device packaging material 10 according to the first embodiment of the present disclosure, the ratio of the total thickness of the base material layer 1, the adhesive layer 2 provided as needed, the barrier layer 3, the inner layer (adhesive layer 5, heat-sealable resin layer 4), and the surface coating layer 6 provided as needed to the thickness (total thickness) of the laminate constituting the electrical storage device packaging material 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. As a specific example, when the electrical storage device packaging material 10 according to the first embodiment of the present disclosure includes the base material layer 1, the adhesive layer 2, the barrier layer 3, and the inner layer (adhesive layer 5 and heat-sealable resin layer 4), the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the electrical storage device packaging material 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0047] Furthermore, in the electrical storage device packaging material 10 according to the second embodiment of the present disclosure, the ratio of the total thickness of the base material layer 1, the adhesive layer 2 (which is provided as needed), the barrier layer 3, the adhesive layer 5, the heat-sealable resin layer 4, and the surface coating layer 6 (which is provided as needed) to the thickness (total thickness) of the laminate constituting the electrical storage device packaging material 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. As a specific example, when the electrical storage device packaging material 10 according to the second embodiment of the present disclosure includes the base material layer 1, the adhesive layer 2, the barrier layer 3, the adhesive layer 5, and the heat-sealable resin layer 4, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the electrical storage device packaging material 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0048] In the electrical storage device packaging material 10 according to the third embodiment of the present disclosure, the ratio of the total thickness of the base material layer 1, the adhesive layer 2 (if provided as needed), the barrier layer 3, the adhesive layer 5 (if provided as needed), the heat-sealable resin layer 4, and the surface coating layer 6 (if provided as needed) to the thickness (total thickness) of the laminate constituting the electrical storage device packaging material 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. As a specific example, when the electrical storage device packaging material 10 according to the third embodiment of the present disclosure includes the base material layer 1, the adhesive layer 2, the barrier layer 3, the adhesive layer 5, and the heat-sealable resin layer 4, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the electrical storage device packaging material 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0049] In the electrical storage device packaging material 10 according to the first embodiment of the present disclosure, when dynamic viscoelasticity measurement is performed on the inner layer by tension, the elongation at 80°C is 8.0% or less. The method for measuring the elongation by the dynamic viscoelasticity measurement is as follows. The lower the elongation by the dynamic viscoelasticity measurement, the higher the crystallinity of the inner layer (the adhesive layer 5 and the heat-sealable resin layer 4) and the more suppressed the softening of the inner layer, thereby improving the sealing ability against internal stress in a high-temperature environment.

[0050] <Dynamic Viscoelasticity (DMA) Measurement> A sample is prepared from the inner layer of the electrical storage device packaging material, and dynamic viscoelasticity measurement is performed. Specifically, the electrical storage device packaging material is immersed in a 10% hydrochloric acid aqueous solution for 24 hours to dissolve the barrier layer, thereby obtaining the inner layer (a laminate of an adhesive layer and a heat-sealable resin layer). This inner layer is a laminate composed only of the adhesive layer 5 and the heat-sealable resin layer 4, from which the layers on the barrier layer side of the adhesive layer of the electrical storage device packaging material (i.e., the barrier layer 3, the adhesive layer 2 (optional), the base layer 1, the surface coating layer 6 (optional), etc.) have been removed. Next, this inner layer is washed with water, dried, and cut into a sample with a width of 5 mm and a length of 10 mm. Next, dynamic viscoelasticity measurement is performed on the obtained sample using a dynamic viscoelasticity measurement device (for example, a Rheogel-E4000 product name manufactured by UBM Corporation) under the following measurement conditions.

[0051] (Measurement conditions) Sample width 5mm Starting temperature 30℃ End temperature 160℃ Heating rate: 2°C / min Static load 50g Length between test holders (distance between chucks): 10 mm Chuck tension Software used for measurement: RheoStation (ver. 7) Step temperature 1℃ Waveform: Sine wave, 10Hz, distortion 10μm, distortion control (automatic adjustment) Measuring tool: tension To prevent the sample from breaking and becoming impossible to measure, the load is controlled at a constant level up to an elongation rate of 10%, after which the load control is stopped and the sample is elongated by 20 μm for every 1° C.

[0052] The elongation at 80°C may be 8.0% or less, but from the viewpoint of further improving the sealing ability of the electrical storage device packaging material in a high-temperature environment, it is preferably about 7.0% or less, more preferably about 6.0% or less, and even more preferably about 5.5% or less. The elongation at 80°C may be, for example, about 0.0% or more, about 1.0% or more, or about 2.0% or more. Preferred ranges for the elongation at 80°C include about 0.0 to 8.0%, about 0.0 to 7.0%, about 0.0 to 6.0%, about 0.0 to 5.5%, about 1.0 to 8.0%, about 1.0 to 7.0%, about 1.0 to 6.0%, about 1.0 to 5.5%, about 2.0 to 8.0%, about 2.0 to 7.0%, about 2.0 to 6.0%, about 2.0 to 5.5%, and about 3.7 to 4.7%.

[0053] In the electrical storage device packaging material according to the first embodiment of the present disclosure, a suitable example for setting the elongation at 80°C of the inner layer in a tensile dynamic viscoelasticity measurement to 8.0% or less is to increase the crystallinity of the adhesive layer and the heat-sealable resin layer. Specifically, when manufacturing the electrical storage device packaging material, the adhesive layer and the heat-sealable resin layer are formed by melt extrusion molding, cooled, and then post-heated to a temperature above the melting point of the adhesive layer and the heat-sealable resin layer, followed by cooling. Furthermore, the cooling rate after post-heating is preferably 60°C or less, more preferably 50°C or less, and even more preferably 45°C or less within 3 seconds from the start of cooling, and the initial cooling conditions are controlled to be very slow, thereby promoting crystal growth of the resin in the adhesive layer and the heat-sealable resin layer. For example, by forming the adhesive layer and the heat-sealable resin layer using such a method, the crystallinity of the adhesive layer and the heat-sealable resin layer is increased, improving hermeticity in high-temperature environments.

[0054] The elongation of the inner layer at 110°C measured by the dynamic viscoelasticity measurement is not particularly limited, but is preferably about 15.0% or less, more preferably about 14.0% or less, and even more preferably 13.5% or less, from the viewpoint of further improving the sealing performance of the electrical storage device packaging material in a high-temperature environment. The elongation at 110°C may be, for example, about 5.0% or more, about 6.0% or more, about 7.0% or more, or about 8.0% or more. Preferred ranges for the elongation at 110°C are about 5.0 to 15.0%, about 5.0 to 14.0%, about 5.0 to 13.5%, about 6.0 to 15.0%, about 6.0 to 14.0%, about 6.0 to 13.5%, about 7.0 to 15.0%, about 7.0 to 14.0%, about 7.0 to 13.5%, about 8.0 to 15.0%, about 8.0 to 14.0%, about 8.0 to 13.5%, and about 10.0 to 13.0%.

[0055] In the outer casing material for an electricity storage device according to the first embodiment of the present disclosure, a method for setting the elongation percentage at 110°C in the tensile dynamic viscoelasticity measurement of the inner layer to 15.0% or less can be achieved by setting the elongation percentage at 80°C in the tensile dynamic viscoelasticity measurement described above to 8.0% or less (i.e., very slow cooling conditions immediately after the post-heating step described above).

[0056] Furthermore, in the graph showing the relationship between elongation (%) and temperature (°C) obtained by the dynamic viscoelasticity measurement for the electrical storage device packaging material according to the first embodiment of the present disclosure, the temperature at an elongation of 10% is not particularly limited, but from the viewpoint of further improving the hermetic sealing performance of the electrical storage device packaging material in a high-temperature environment, it is preferably 85°C or higher, more preferably 90°C or higher, even more preferably 100°C or higher, and particularly preferably 105°C or higher. The temperature is, for example, 130°C or lower, 120°C or lower, or 110°C or lower. Preferred ranges for the temperature are about 85 to 130° C., about 85 to 120° C., about 85 to 110° C., about 90 to 130° C., about 90 to 120° C., about 90 to 110° C., about 100 to 130° C., about 100 to 120° C., about 100 to 110° C., about 105 to 130° C., about 105 to 120° C., and about 105 to 110° C. The temperature at which the elongation rate is 10% is, for example, the temperature at position I in the schematic diagram of FIG. 7, and at temperatures higher than position I, the graph becomes a straight line.

[0057] In the packaging material for an electricity storage device according to the first embodiment of the present disclosure, a method for setting the temperature to 85°C or higher can be adopted in which the elongation at 80°C in the above-mentioned tensile dynamic viscoelasticity measurement is set to 8.0% or less (i.e., very slow cooling conditions immediately after the above-mentioned post-heating step).

[0058] 2. Each layer that forms the exterior material for the energy storage device [Base material layer 1] In the present disclosure, the substrate layer 1 is a layer provided for the purpose of allowing the packaging material for an electricity storage device to function as a substrate. The substrate layer 1 is located on the outer layer side of the packaging material for an electricity storage device.

[0059] There are no particular limitations on the material forming the base layer 1, as long as it functions as a base, i.e., has at least insulating properties. The base layer 1 can be formed using, for example, a resin, which may contain additives described below.

[0060] When the base layer 1 is formed of a resin, the base layer 1 may be, for example, a resin film formed of a resin, or may be formed by applying a resin. The resin film may be an unstretched film or a stretched film. Examples of stretched films include uniaxially stretched films and biaxially stretched films, with biaxially stretched films being preferred. Examples of stretching methods for forming biaxially stretched films include sequential biaxial stretching, inflation, and simultaneous biaxial stretching. Examples of methods for applying a resin include roll coating, gravure coating, and extrusion coating.

[0061] Examples of resins that form the base layer 1 include polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenolic resin, as well as modified versions of these resins. The resin that forms the base layer 1 may also be a copolymer of these resins or a modified version of the copolymer. Furthermore, it may also be a mixture of these resins.

[0062] Of these, preferred resins for forming the base layer 1 include polyester and polyamide.

[0063] Specific examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyesters. Examples of copolymer polyesters include copolymer polyesters in which ethylene terephthalate is the main repeating unit. Specific examples include copolymer polyesters in which ethylene terephthalate is the main repeating unit and is polymerized with ethylene isophthalate (hereinafter abbreviated as polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate), and polyethylene (terephthalate / decanedicarboxylate). These polyesters may be used alone or in combination of two or more.

[0064] Specific examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (I represents isophthalic acid, T represents terephthalic acid) containing structural units derived from terephthalic acid and / or isophthalic acid; aromatic polyamides such as polyamide MXD6 (polymetaxylylene adipamide); alicyclic polyamides such as polyamide PACM6 (polybis(4-aminocyclohexyl)methane adipamide); and polyamides containing lactam components and 4,4'-diphenylmethane-diisocyanate. Examples of polyamides include polyamides copolymerized with an isocyanate component such as olefin copolymer, polyester amide copolymers and polyether ester amide copolymers, which are copolymers of copolymerized polyamides with polyester or polyalkylene ether glycol; and polyamides such as copolymers of these polyamides. These polyamides may be used alone or in combination of two or more.

[0065] The base layer 1 preferably includes at least one of a polyester film, a polyamide film, and a polyolefin film, preferably includes at least one of a stretched polyester film, a stretched polyamide film, and a stretched polyolefin film, more preferably includes at least one of a stretched polyethylene terephthalate film, a stretched polybutylene terephthalate film, a stretched nylon film, and a stretched polypropylene film, and even more preferably includes at least one of a biaxially oriented polyethylene terephthalate film, a biaxially oriented polybutylene terephthalate film, a biaxially oriented nylon film, and a biaxially oriented polypropylene film.

[0066] The base material layer 1 may be a single layer, or may be composed of two or more layers. When the base material layer 1 is composed of two or more layers, the base material layer 1 may be a laminate in which resin films are laminated with an adhesive or the like, or a laminate of resin films formed by co-extrusion of resins into two or more layers. Furthermore, a laminate of resin films formed by co-extrusion of resins into two or more layers may be used as the base material layer 1 without being stretched, or may be uniaxially or biaxially stretched to form the base material layer 1.

[0067] Specific examples of laminates of two or more resin films in the base layer 1 include laminates of polyester film and nylon film, laminates of two or more nylon films, and laminates of two or more polyester films. Preferably, laminates of stretched nylon film and stretched polyester film, laminates of two or more stretched nylon films, and laminates of two or more stretched polyester films are preferred. For example, when the base layer 1 is a laminate of two resin films, a laminate of polyester resin film and polyester resin film, a laminate of polyamide resin film and polyamide resin film, or a laminate of polyester resin film and polyamide resin film is preferred. A laminate of polyethylene terephthalate film and polyethylene terephthalate film, a laminate of nylon film and nylon film, or a laminate of polyethylene terephthalate film and nylon film is more preferred. Furthermore, when the base layer 1 is a laminate of two or more resin films, it is preferred that the polyester resin film be located as the outermost layer of the base layer 1, because polyester resins are less likely to discolor when an electrolyte solution adheres to their surface.

[0068] When the base layer 1 is a laminate of two or more resin film layers, the two or more resin film layers may be laminated via an adhesive. Examples of preferred adhesives include those similar to those exemplified for adhesive layer 2 described below. The method for laminating two or more resin film layers is not particularly limited, and known methods can be used, such as dry lamination, sandwich lamination, extrusion lamination, and thermal lamination, with dry lamination being preferred. When laminating using the dry lamination method, it is preferable to use a polyurethane adhesive as the adhesive. In this case, the thickness of the adhesive may be, for example, about 2 to 5 μm. Alternatively, an anchor coat layer may be formed on the resin film before lamination. Examples of the anchor coat layer include those similar to those exemplified for adhesive layer 2 described below. In this case, the thickness of the anchor coat layer may be, for example, about 0.01 to 1.0 μm.

[0069] Furthermore, additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents may be present on at least one of the surface and the interior of the base material layer 1. Only one type of additive may be used, or two or more types may be mixed and used.

[0070] In the present disclosure, from the viewpoint of improving the formability of the exterior material for an electrical storage device, it is preferable that a lubricant be present on the surface of the base layer 1. The lubricant is not particularly limited, but preferably an amide-based lubricant is used. Specific examples of amide-based lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, and N-stearyl erucic acid amide. Specific examples of methylolamides include methylol stearic acid amide. Specific examples of saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipamide, and N,N'-distearyl sebacic acid amide. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipamide, and N,N'-dioleyl sebacic acid amide. Specific examples of fatty acid ester amides include stearamidoethyl stearate. Specific examples of aromatic bisamides include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, N,N'-distearyl isophthalic acid amide, etc. The lubricants may be used singly or in combination of two or more.

[0071] When a lubricant is present on the surface of the base layer 1, the amount of the lubricant is not particularly limited, but is preferably about 3 mg / m 2 or more, more preferably 4 to 15 mg / m 2 approximately, more preferably 5 to 14 mg / m 2 The degree of

[0072] The lubricant present on the surface of the base layer 1 may be a lubricant exuded from the resin that constitutes the base layer 1, or a lubricant applied to the surface of the base layer 1.

[0073] The thickness of the base layer 1 is not particularly limited as long as it functions as a base, but may be, for example, about 3 to 50 μm, and preferably about 10 to 35 μm. When the base layer 1 is a laminate of two or more resin films, the thickness of each resin film constituting each layer is preferably about 2 to 25 μm.

[0074] [Adhesive layer 2] In the packaging material for an electricity storage device of the present disclosure, the adhesive layer 2 is a layer that is provided between the base layer 1 and the barrier layer 3 as needed for the purpose of increasing the adhesion between them.

[0075] The adhesive layer 2 is formed from an adhesive capable of bonding the base material layer 1 and the barrier layer 3. There are no limitations on the adhesive used to form the adhesive layer 2, and it may be any of a chemical reaction type, a solvent evaporation type, a hot melt type, a hot pressure type, etc. It may also be a two-component curing adhesive (two-component adhesive), a one-component curing adhesive (one-component adhesive), or a resin that does not involve a curing reaction. The adhesive layer 2 may be a single layer or multiple layers.

[0076] Specific examples of adhesive components contained in the adhesive include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyesters; polyethers; polyurethanes; epoxy resins; phenolic resins; polyamides such as nylon 6, nylon 66, nylon 12, and copolymer polyamides; polyolefin-based resins such as polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins; polyvinyl acetate; cellulose; (meth)acrylic resins; polyimides; polycarbonates; amino resins such as urea resins and melamine resins; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; and silicone resins. These adhesive components may be used alone or in combination. Among these adhesive components, polyurethane adhesives are preferred. Furthermore, the adhesive strength of these adhesive component resins can be increased by using an appropriate curing agent in combination. The curing agent is selected appropriately from polyisocyanates, multifunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, and the like, depending on the functional groups of the adhesive components.

[0077] Examples of polyurethane adhesives include polyurethane adhesives containing a base agent containing a polyol compound and a curing agent containing an isocyanate compound. Two-component curing polyurethane adhesives are preferred, using a polyol such as polyester polyol, polyether polyol, or acrylic polyol as the base agent and an aromatic or aliphatic polyisocyanate as the curing agent. Furthermore, as the polyol compound, polyester polyols having hydroxyl groups on the side chains in addition to terminal hydroxyl groups in the repeating unit are preferably used. Examples of curing agents include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). Further examples include polyfunctional isocyanate modified products obtained from one or more of these diisocyanates. Furthermore, a polymer (e.g., a trimer) can also be used as the polyisocyanate compound. Examples of such polymers include adducts, biurets, and nurates. Forming the adhesive layer 2 from a polyurethane adhesive provides the electrical storage device exterior packaging material with excellent electrolyte resistance, and prevents the base layer 1 from peeling off even if the electrolyte adheres to the side surface.

[0078] Furthermore, the adhesive layer 2 may contain other components as long as they do not impair adhesion, and may contain colorants, thermoplastic elastomers, tackifiers, fillers, and the like. When the adhesive layer 2 contains a colorant, the exterior material for an electricity storage device can be colored. Known colorants such as pigments and dyes can be used as the colorant. Furthermore, only one type of colorant may be used, or two or more types may be mixed together.

[0079] The type of pigment is not particularly limited as long as it does not impair the adhesiveness of the adhesive layer 2. Examples of organic pigments include azo-based, phthalocyanine-based, quinacridone-based, anthraquinone-based, dioxazine-based, indigothioindigo-based, perinone-perylene-based, isoindolenine-based, and benzimidazolone-based pigments, while examples of inorganic pigments include carbon black-based, titanium oxide-based, cadmium-based, lead-based, chromium oxide-based, and iron-based pigments, and other examples include finely powdered mica and fish scale foil.

[0080] Among colorants, carbon black is preferred in order to give the exterior appearance of the electrical storage device packaging material a black color, for example.

[0081] The average particle size of the pigment is not particularly limited and may be, for example, about 0.05 to 5 μm, and preferably about 0.08 to 2 μm. The average particle size of the pigment is the median size measured with a laser diffraction / scattering particle size distribution measuring device.

[0082] The content of the pigment in the adhesive layer 2 is not particularly limited as long as it colors the packaging material for an electricity storage device, and may be, for example, about 5 to 60 mass %, and preferably 10 to 40 mass %.

[0083] The thickness of the adhesive layer 2 is not particularly limited as long as it can bond the base layer 1 and the barrier layer 3, but is, for example, about 1 μm or more, or about 2 μm or more. The thickness of the adhesive layer 2 is, for example, about 10 μm or less, or about 5 μm or less. Preferred ranges for the thickness of the adhesive layer 2 include about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, and about 2 to 5 μm.

[0084] [Colored layer] The colored layer is a layer (not shown) that is provided between the base material layer 1 and the barrier layer 3 as needed. When the adhesive layer 2 is provided, a colored layer may be provided between the base material layer 1 and the adhesive layer 2, or between the adhesive layer 2 and the barrier layer 3. Alternatively, a colored layer may be provided on the outside of the base material layer 1. By providing a colored layer, the packaging material for an electricity storage device can be colored.

[0085] The colored layer can be formed, for example, by applying ink containing a colorant to the surface of the base layer 1 or the surface of the barrier layer 3. Known colorants such as pigments and dyes can be used as the colorant. Furthermore, only one type of colorant may be used, or two or more types may be mixed together.

[0086] Specific examples of the colorant contained in the colored layer include the same as those exemplified in the section [Adhesive layer 2].

[0087] [Barrier layer 3] In the packaging material for an electricity storage device, the barrier layer 3 is a layer that at least prevents the penetration of moisture.

[0088] Examples of the barrier layer 3 include metal foils, vapor-deposited films, and resin layers having barrier properties. Vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Resin layers include fluorine-containing resins such as polyvinylidene chloride, polymers mainly composed of chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers mainly composed of fluoroalkyl units, as well as ethylene-vinyl alcohol copolymers. Examples of the barrier layer 3 also include resin films comprising at least one of these vapor-deposited films and resin layers. The barrier layer 3 may comprise multiple layers. The barrier layer 3 preferably includes a layer composed of a metal material. Specific examples of metal materials constituting the barrier layer 3 include aluminum alloys, stainless steel, titanium steel, and steel plates. When used as a metal foil, the barrier layer 3 preferably includes at least one of aluminum alloy foil and stainless steel foil.

[0089] From the viewpoint of improving the formability of the electrical storage device packaging material, the aluminum alloy foil is preferably a soft aluminum alloy foil made of, for example, an annealed aluminum alloy, and from the viewpoint of further improving formability, an iron-containing aluminum alloy foil is preferred. In the iron-containing aluminum alloy foil (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, more preferably 0.5 to 2.0% by mass. By setting the iron content to 0.1% by mass or more, an electrical storage device packaging material with better formability can be obtained. By setting the iron content to 9.0% by mass or less, an electrical storage device packaging material with better flexibility can be obtained. Examples of soft aluminum alloy foils include aluminum alloy foils having a composition specified in JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Silicon, magnesium, copper, manganese, etc. may be added as needed. Softening can be achieved by annealing or other methods.

[0090] Examples of stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation hardened stainless steel foils. From the viewpoint of providing an exterior material for an electricity storage device that has excellent formability, the stainless steel foil is preferably made of austenitic stainless steel.

[0091] Specific examples of austenitic stainless steels that can be used to form the stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred.

[0092] In the case of a metal foil, the thickness of the barrier layer 3 should be sufficient to at least function as a barrier layer that prevents moisture penetration, and is, for example, approximately 9 to 200 μm. The thickness of the barrier layer 3 is preferably approximately 85 μm or less, more preferably approximately 50 μm or less, even more preferably approximately 40 μm or less, and particularly preferably approximately 35 μm or less. The thickness of the barrier layer 3 is preferably approximately 10 μm or more, even more preferably approximately 20 μm or more, and more preferably approximately 25 μm or more. Preferred thickness ranges for the barrier layer 3 include approximately 10 to 85 μm, approximately 10 to 50 μm, approximately 10 to 40 μm, approximately 10 to 35 μm, approximately 20 to 85 μm, approximately 20 to 50 μm, approximately 20 to 40 μm, approximately 20 to 35 μm, approximately 25 to 85 μm, approximately 25 to 50 μm, approximately 25 to 40 μm, and approximately 25 to 35 μm. When the barrier layer 3 is made of aluminum alloy foil, the above-mentioned ranges are particularly preferred. Furthermore, when the barrier layer 3 is made of aluminum alloy foil, from the viewpoint of imparting high formability and high rigidity to the packaging material 10 for an electricity storage device, the thickness of the barrier layer 3 is preferably about 45 μm or more, more preferably about 50 μm or more, and more preferably about 55 μm or more, and is preferably about 80 μm or less, more preferably 75 μm or less, and even more preferably 70 μm or less, with preferred ranges being about 45 to 80 μm, about 45 to 75 μm, about 45 to 70 μm, about 50 to 80 μm, about 50 to 75 μm, about 50 to 70 μm, about 55 to 80 μm, about 55 to 75 μm, and about 55 to 70 μm. When the packaging material 10 for an electricity storage device has high formability, deep drawing becomes easy, which can contribute to increasing the capacity of the electricity storage device. Furthermore, when the capacity of an electricity storage device is increased, the weight of the electricity storage device increases, but increasing the rigidity of the exterior packaging material 10 for an electricity storage device can contribute to high sealing performance of the electricity storage device.

[0093] In particular, when the barrier layer 3 is made of stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, even more preferably about 30 μm or less, and particularly preferably about 25 μm or less. The thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Preferred ranges for the thickness of the stainless steel foil include about 10 to 60 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 30 μm, about 10 to 25 μm, about 15 to 60 μm, about 15 to 50 μm, about 15 to 40 μm, about 15 to 30 μm, and about 15 to 25 μm.

[0094] Furthermore, when the barrier layer 3 is a metal foil, it is preferable that a corrosion-resistant coating be provided on at least the surface opposite the substrate layer to prevent dissolution and corrosion. The barrier layer 3 may be provided with a corrosion-resistant coating on both sides. Here, the corrosion-resistant coating refers to a thin film formed on the surface of the barrier layer by, for example, a hydrothermal conversion treatment such as boehmite treatment, a chemical conversion treatment, anodizing treatment, a nickel or chromium plating treatment, or a corrosion prevention treatment such as applying a coating agent, to provide the barrier layer with corrosion resistance (e.g., acid resistance, alkali resistance, etc.). Specifically, the corrosion-resistant coating refers to a coating that improves the acid resistance of the barrier layer (acid-resistant coating) or a coating that improves the alkali resistance of the barrier layer (alkali-resistant coating). The corrosion-resistant coating may be formed by one type of treatment or a combination of two or more types. Furthermore, not only one layer but also multiple layers can be formed. Furthermore, among these treatments, the hydrothermal conversion treatment and anodizing treatment are treatments that dissolve the metal foil surface with a treatment agent to form a metal compound with excellent corrosion resistance. These treatments may be included in the definition of chemical conversion treatment. In addition, when the barrier layer 3 is provided with a corrosion-resistant coating, the barrier layer 3 includes the corrosion-resistant coating.

[0095] The corrosion-resistant coating prevents delamination between the barrier layer (e.g., aluminum alloy foil) and the substrate layer during molding of the exterior packaging material for an electricity storage device, prevents dissolution and corrosion of the barrier layer surface due to hydrogen fluoride produced by the reaction between the electrolyte and water, and in particular prevents dissolution and corrosion of aluminum oxide present on the barrier layer surface when the barrier layer is an aluminum alloy foil, and also improves the adhesion (wettability) of the barrier layer surface, thereby preventing delamination between the substrate layer and the barrier layer during heat sealing and between the substrate layer and the barrier layer during molding.

[0096] Various corrosion-resistant coatings formed by chemical conversion treatments are known, including corrosion-resistant coatings containing at least one of phosphates, chromates, fluorides, triazine thiol compounds, and rare earth oxides. Examples of chemical conversion treatments using phosphates and chromates include chromate chromate treatment, phosphate chromate treatment, phosphate-chromate treatment, and chromate treatment. Examples of chromium compounds used in these treatments include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromate acetylacetate, chromium chloride, and potassium chromium sulfate. Examples of phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphoric acid. Examples of chromate treatments include etching chromate treatment, electrolytic chromate treatment, and paint-on chromate treatment, with paint-on chromate treatment being preferred. This paint-type chromate treatment involves first degreasing at least the inner surface of a barrier layer (e.g., an aluminum alloy foil) using a well-known method such as alkali immersion, electrolytic cleaning, acid pickling, electrolytic pickling, or acid activation, and then coating the degreased surface with a treatment solution primarily composed of a metal phosphate such as Cr (chromium) phosphate, Ti (titanium) phosphate, Zr (zirconium) phosphate, or Zn (zinc) phosphate, or a mixture of these metal salts, or a treatment solution primarily composed of a nonmetallic phosphate and a mixture of these nonmetallic salts, or a mixture of these with a synthetic resin, using a well-known coating method such as roll coating, gravure printing, or immersion, followed by drying. The treatment solution can be, for example, water, alcoholic solvents, hydrocarbon solvents, ketone solvents, ester solvents, or ether solvents, with water being preferred. The resin component used here may be a polymer such as a phenolic resin or an acrylic resin, or may be a chromate treatment using an aminated phenol polymer having repeating units represented by the following general formulas (1) to (4): In the aminated phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be contained alone or in any combination of two or more types.The acrylic resin is preferably polyacrylic acid, an acrylic acid methacrylic acid ester copolymer, an acrylic acid maleic acid copolymer, an acrylic acid styrene copolymer, or a derivative thereof such as a sodium salt, an ammonium salt, or an amine salt. A derivative of polyacrylic acid, such as an ammonium salt, a sodium salt, or an amine salt of polyacrylic acid, is particularly preferred. In the present disclosure, polyacrylic acid refers to a polymer of acrylic acid. The acrylic resin is also preferably a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride, or an ammonium salt, a sodium salt, or an amine salt of a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride. Only one type of acrylic resin may be used, or two or more types may be mixed and used.

[0097] [ka]

[0098] [ka]

[0099] [ka]

[0100] [ka]

[0101] In the general formulas (1) to (4), X represents a hydrogen atom, a hydroxy group, an alkyl group, a hydroxyalkyl group, an allyl group, or a benzyl group. 1 and R 2 are the same or different and represent a hydroxy group, an alkyl group, or a hydroxyalkyl group. 1 and R 2Examples of the alkyl group represented by X and R include linear or branched alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl. 1 and R 2 Examples of the hydroxyalkyl group represented by the formula (1) include a linear or branched alkyl group having 1 to 4 carbon atoms substituted with one hydroxy group, such as a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, a 3-hydroxypropyl group, a 1-hydroxybutyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, and a 4-hydroxybutyl group. 1 and R 2 The alkyl group and hydroxyalkyl group represented by the formula (1) may be the same or different. In the formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group, or a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer having repeating units represented by the formulas (1) to (4) is preferably about 500 to 1,000,000, and more preferably about 1,000 to 20,000. The aminated phenol polymer can be prepared, for example, by polycondensing a phenol compound or a naphthol compound with formaldehyde to produce a polymer comprising repeating units represented by the formula (1) or (3), and then polycondensing the polymer with formaldehyde and an amine (R 1 R 2 NH) to the functional group (-CHNR 1 R 2 ) into the polymer obtained above. The aminated phenol polymers may be used singly or in combination of two or more.

[0102] Another example of a corrosion-resistant coating is a thin film formed by a coating-type corrosion prevention treatment in which a coating agent containing at least one selected from the group consisting of a rare earth element oxide sol, an anionic polymer, and a cationic polymer is applied. The coating agent may further contain phosphoric acid or a phosphate salt, and a crosslinking agent for crosslinking the polymer. The rare earth element oxide sol has rare earth element oxide fine particles (e.g., particles with an average particle size of 100 nm or less) dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, with cerium oxide being preferred from the perspective of further improving adhesion. The rare earth element oxide contained in the corrosion-resistant coating can be used alone or in combination of two or more. The liquid dispersion medium for the rare earth element oxide sol can be various solvents such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Preferred examples of cationic polymers include polyethyleneimine, ionic polymer complexes composed of polyethyleneimine and a polymer having a carboxylic acid, primary amine-grafted acrylic resins in which a primary amine is graft-polymerized onto an acrylic backbone, polyallylamine or its derivatives, and aminated phenols. Preferred anionic polymers are poly(meth)acrylic acid or its salts, or copolymers primarily composed of (meth)acrylic acid or its salts. The crosslinking agent is preferably at least one selected from the group consisting of a compound having a functional group selected from an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group, and a silane coupling agent. The phosphoric acid or phosphoric acid salt is preferably a condensed phosphoric acid or a condensed phosphate salt.

[0103] An example of a corrosion-resistant coating is one formed by applying a solution of fine particles of metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide, or barium sulfate dispersed in phosphoric acid to the surface of a barrier layer and baking the coating at 150°C or higher.

[0104] The corrosion-resistant coating may have a laminated structure, if necessary, by further laminating at least one of a cationic polymer and an anionic polymer, such as those mentioned above.

[0105] The composition of the corrosion-resistant film can be analyzed using, for example, time-of-flight secondary ion mass spectrometry.

[0106] The amount of the corrosion-resistant film formed on the surface of the barrier layer 3 in the chemical conversion treatment is not particularly limited. For example, in the case of applying chromate treatment, the amount of the corrosion-resistant film formed on the surface of the barrier layer 3 is 2 For example, the amount of the chromate compound is about 0.5 to 50 mg, preferably 1 mg, in terms of chromium. It is desirable that the content be about 0.0 to 40 mg, the phosphorus compound be about 0.5 to 50 mg, preferably about 1.0 to 40 mg, and the aminated phenol polymer be about 1.0 to 200 mg, preferably about 5.0 to 150 mg, in terms of phosphorus.

[0107] The thickness of the corrosion-resistant coating is not particularly limited, but is preferably about 1 nm to 20 μm, more preferably about 1 nm to 100 nm, and even more preferably about 1 nm to 50 nm, from the viewpoint of the cohesive strength of the coating and the adhesive strength with the barrier layer or the thermally adhesive resin layer. The thickness of the corrosion-resistant coating can be measured by observation with a transmission electron microscope, or by a combination of observation with a transmission electron microscope and energy dispersive X-ray spectroscopy or electron energy loss spectroscopy. Analysis of the composition of the corrosion-resistant coating using time-of-flight secondary ion mass spectrometry can reveal the thickness of the corrosion-resistant coating, for example, by measuring the thickness of the coating with secondary ions consisting of Ce, P, and O (e.g., Ce2PO4 + , C ePO4 - At least one of the following ions may be present: Cr, P, and O secondary ions (e.g., CrPO2 + , CrPO4 - Peaks derived from at least one of the above are detected.

[0108] The chemical conversion treatment is carried out by applying a solution containing a compound used to form a corrosion-resistant coating to the surface of the barrier layer by bar coating, roll coating, gravure coating, immersion, or other methods, and then heating the barrier layer to a temperature of approximately 70 to 200°C. Furthermore, before applying the chemical conversion treatment to the barrier layer, the barrier layer may be subjected to a degreasing treatment using an alkali immersion method, electrolytic cleaning, acid cleaning, electrolytic acid cleaning, or other methods. By performing such a degreasing treatment, the chemical conversion treatment of the surface of the barrier layer can be carried out more efficiently. Furthermore, using an acid degreasing agent prepared by dissolving a fluorine-containing compound in an inorganic acid for the degreasing treatment not only degreases the metal foil but also forms a passive metal fluoride. In such cases, only the degreasing treatment may be performed.

[0109] [Thermal adhesive resin layer 4] In the packaging material for an electricity storage device of the present disclosure, the heat-sealable resin layer 4 included in the inner layer corresponds to the innermost layer and is a layer (sealant layer) that functions to seal the electricity storage device elements by heat-sealing the heat-sealable resin layers to each other when assembling the electricity storage device.

[0110] In the first embodiment, the resin constituting the heat-fusible resin layer 4 is not particularly limited as long as it is heat-fusible and, when the inner layer is subjected to dynamic viscoelasticity measurement under tension, has an elongation of 8.0% or less at 80°C, but resins containing a polyolefin skeleton such as polyolefin and acid-modified polyolefin are preferred. In the second embodiment, the resin constituting the heat-fusible resin layer 4 is not particularly limited as long as it is heat-fusible, but resins containing a polyolefin skeleton such as polyolefin and acid-modified polyolefin are preferred.

[0111] In the present disclosure, the presence of a polyolefin skeleton in the resin constituting the thermally adhesive resin layer 4 can be determined by, for example, infrared spectroscopy, gas chromatography mass spectrometry, etc. Furthermore, when the resin constituting the thermally adhesive resin layer 4 is analyzed by infrared spectroscopy, it is preferable that a peak derived from maleic anhydride is detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak derived from maleic anhydride is detected at a wave number of 1760 cm. -1 Near and wave number 1780cm -1 A peak derived from maleic anhydride is detected around . When the thermally adhesive resin layer 4 is a layer made of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak becomes small and may not be detected. In such cases, analysis can be performed by nuclear magnetic resonance spectroscopy.

[0112] In the present disclosure, specific examples of polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; 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); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. Among these, polypropylene is preferred. When the polyolefin resin is a copolymer, it may be a block copolymer or a random copolymer. These polyolefin resins may be used alone or in combination of two or more.

[0113] In the present disclosure, the polyolefin may be a cyclic polyolefin. Cyclic polyolefins are copolymers of olefins and cyclic monomers, and examples of olefins constituting the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. Examples of cyclic monomers constituting the cyclic polyolefin include cyclic alkenes such as norbornene; and cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these, cyclic alkenes are preferred, and norbornene is more preferred.

[0114] In the present disclosure, acid-modified polyolefins are polymers modified by block polymerization or graft polymerization of polyolefins with an acid component. Examples of acid-modified polyolefins include the above-mentioned polyolefins, copolymers of the above-mentioned polyolefins with polar molecules such as acrylic acid or methacrylic acid, and crosslinked polyolefins. Examples of acid components used for acid modification include carboxylic acids or anhydrides thereof, such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

[0115] In the present disclosure, the acid-modified polyolefin may be an acid-modified cyclic polyolefin. The acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin in place of an acid component, or by block polymerizing or graft polymerizing an acid component onto the cyclic polyolefin. The acid-modified cyclic polyolefin is the same as described above. The acid component used for the acid modification is the same as the acid component used for the modification of the polyolefin.

[0116] In the present disclosure, preferred acid-modified polyolefins include polyolefins modified with carboxylic acids or their anhydrides, polypropylenes modified with carboxylic acids or their anhydrides, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

[0117] In the present disclosure, the thermally adhesive resin layer 4 may be formed of one type of resin alone or may be formed of a blend polymer of two or more types of resins. Furthermore, the thermally adhesive resin layer 4 may be formed of only one layer, or may be formed of two or more layers of the same or different resins.

[0118] In the present disclosure, the thermally adhesive resin layer 4 may contain a lubricant or the like as needed. When the thermally adhesive resin layer 4 contains a lubricant, the formability of the electrical storage device packaging material can be improved. The lubricant is not particularly limited, and known lubricants can be used. The lubricants may be used alone or in combination of two or more.

[0119] The lubricant is not particularly limited, but preferably an amide-based lubricant is used. Specific examples of the lubricant include those exemplified for the base layer 1. The lubricant may be used alone or in combination of two or more.

[0120] In the present disclosure, when a lubricant is present on the surface of the heat-sealable resin layer 4, the amount of the lubricant present is not particularly limited. However, from the viewpoint of improving the formability of the packaging material for an electricity storage device, the amount of the lubricant present is preferably 10 to 50 mg / m 2 about 15 to 40 mg / m 2 The degree of

[0121] In the present disclosure, the lubricant present on the surface of the heat-sealable resin layer 4 may be a lubricant exuded from the resin constituting the heat-sealable resin layer 4, or a lubricant applied to the surface of the heat-sealable resin layer 4.

[0122] In the present disclosure, the thickness of the heat-sealable resin layer 4 is not particularly limited as long as it functions to heat-seal the heat-sealable resin layers together and seal the electricity storage device element, but may be, for example, about 100 μm or less, preferably about 85 μm or less, and more preferably about 15 to 85 μm. In the present disclosure, for example, when the thickness of the adhesive layer 5 described below is 10 μm or more, the thickness of the heat-sealable resin layer 4 is preferably about 85 μm or less, more preferably about 15 to 45 μm. In the present disclosure, for example, when the thickness of the adhesive layer 5 described below is less than 10 μm or when the adhesive layer 5 is not provided, the thickness of the heat-sealable resin layer 4 is preferably about 20 μm or more, more preferably about 35 to 85 μm.

[0123] As described above, in the packaging material for an electricity storage device according to the first embodiment of the present disclosure, a suitable example for setting the elongation at 80°C in the tensile dynamic viscoelasticity measurement of the inner layer to 8.0% or less is to increase the crystallinity of the adhesive layer and the heat-sealable resin layer, and it is desirable to control the initial cooling conditions after post-heating to very slow cooling conditions to promote crystal growth of the resin in the adhesive layer and the heat-sealable resin layer. For example, by employing such a method to form the heat-sealable resin layer, the crystallinity of the adhesive layer and the heat-sealable resin layer is increased, and the hermetic seal in a high-temperature environment is improved.

[0124] In the third embodiment, the heat-sealable resin layer 4 contains polypropylene and polyethylene. In the packaging material for an electricity storage device according to the third embodiment of the present disclosure, a sea-island structure is observed in a cross-sectional image of the heat-sealable resin layer 4 taken using a scanning electron microscope, in a cross section parallel to the TD and in the thickness direction y. As shown in the schematic diagram of FIG. 21 , for example, the cross-sectional image is taken within a range from the surface of the heat-sealable resin layer 4 opposite the barrier layer 3 to a portion 12.5% of the thickness, where the total thickness of the layers located inside the barrier layer 3 is taken as 100%. The surface of the heat-sealable resin layer 4 opposite the barrier layer 3 has a thickness of 0%. To explain this using a specific example, in the case of an electrical storage device packaging material in which a base material layer (30 μm thick including the adhesive) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (40 μm) / thermal adhesive resin layer (40 μm) are laminated in this order, as in Examples 1 and 2 described below, the layers located inside the barrier layer 3 are the adhesive layer (40 μm) and the thermal adhesive resin layer (40 μm), and the total thickness of these, 80 μm, is taken as 100%. Furthermore, the position of the surface of the thermal adhesive resin layer 4 opposite to the barrier layer 3 side is the inner surface (inner surface) of the electrical storage device packaging material 10, and the thickness at this position is taken as 0%. Then, a cross-sectional image is obtained using a scanning electron microscope within the range from the surface (0% thickness) to the 12.5% thickness position (i.e., the total of 80 μm is 100%, and the 12.5% thickness position is the position 10 μm thick from the surface of the thermally adhesive resin layer 4 opposite the barrier layer 3 side toward the barrier layer 3 side).

[0125] Observation of a sea-island structure in a cross-sectional image means that a sea portion (sea part) and island portions (island parts) are observed in the cross-sectional image. As described above, when a small amount of polyethylene is added to polypropylene and a heat-sealable resin layer is formed by melt extrusion molding, a sea-island structure is formed in which polyethylene island parts are dispersed in the sea portion of polypropylene. In other words, the island parts contain polyethylene. To observe the sea-island structure, as described below, the cross section of the heat-sealable resin layer is stained with ruthenium tetroxide or the like, and a cross-sectional image is obtained and observed using a scanning electron microscope.

[0126] In the packaging material for an electricity storage device of the third embodiment, in a cross-sectional image of the heat-sealable resin layer 4, the area of the island portions relative to the total number of island portions in the sea-island structure is 0.02 μm 2 The following islands The proportion of the total number is 80.0% or more. The packaging material for an electricity storage device of the third embodiment has such characteristics, and thus whitening of the heat-sealable resin layer due to cold forming of the packaging material for an electricity storage device and deterioration of the insulating properties of the packaging material for an electricity storage device are suppressed. That is, in the packaging material for an electricity storage device of the third embodiment of the present disclosure, in the heat-sealable resin layer 4 containing polypropylene and polyethylene, of all the island portions, 2 The following By setting the proportion of extremely fine island portions to be high, it is thought that the occurrence of fine cracks at the interface between the polypropylene portion and the polyethylene portion of the heat-sealable resin layer is effectively suppressed, and as a result, whitening of the heat-sealable resin layer 4 due to cold forming of the electrical storage device packaging material and a decrease in the insulating properties of the electrical storage device packaging material are suppressed.

[0127] In the cross-sectional image of the heat-sealable resin layer 4 of the third embodiment, the area of the island portion is 0.02 μm with respect to the total number of the island portions of the sea-island structure. 2 The ratio of the total number of islands below (0.02 μm 2 The ratio (total number of island portions / total number of all island portions) described below may be 80.0% or more, but from the viewpoint of more effectively suppressing the above-mentioned whitening and deterioration of insulating properties, it is preferably 90.0% or more, and more preferably 95.0% or more. The percentage of the total number is, for example, 100.0% or less, 99.0% or less, or 98.0% or less. Preferred ranges for the percentage of the total number include, for example, about 80.0 to 100.0%, about 80.0 to 99.0%, about 80.0 to 98.0%, about 90.0 to 100.0%, about 90.0 to 99.0%, about 90.0 to 98.0%, about 95.0 to 100.0%, about 95.0 to 99.0%, and about 95.0 to 98.0%.

[0128] In order to more effectively suppress the whitening and the deterioration of the insulating properties, in the cross-sectional image of the heat-sealable resin layer 4 of the third embodiment, the area of the islands in the sea-island structure is set to 0.01 μm 2 with respect to the total number of the islands. 2 The ratio of the total number of islands below (0.01 μm 2 The ratio (total number of island portions / total number of all island portions) is preferably 50.0% or more, more preferably 55.0% or more, and even more preferably 60.0% or more. The ratio of the total number is, for example, 80.0% or less, 75.0% or less, or 70.0% or less. Preferred ranges for the ratio of the total number include, for example, about 50.0 to 80.0%, about 50.0 to 75.0%, about 50.0 to 70.0%, about 55.0 to 80.0%, about 55.0 to 75.0%, about 55.0 to 70.0%, about 60.0 to 80.0%, about 60.0 to 75.0%, and about 60.0 to 70.0%.

[0129] In order to more effectively suppress the whitening and the deterioration of the insulating properties, the cross-sectional image of the heat-sealable resin layer 4 of the third embodiment shows that the area of the islands in the sea-island structure is 0.03 μm 2 The ratio of the total number of islands below (0.03 μm 2 The ratio (total number of island portions / total number of all island portions) below is preferably 90.0% or more, more preferably 95.0% or more, and even more preferably 97.0% or more. The percentage of the total number is, for example, 100.0% or less, 99.0% or less, or 98.0% or less. Preferred ranges for the percentage of the total number include, for example, about 90.0 to 100.0%, about 90.0 to 99.0%, about 90.0 to 98.0%, about 95.0 to 100.0%, about 95.0 to 99.0%, about 95.0 to 98.0%, about 97.0 to 100.0%, about 97.0 to 99.0%, and about 97.0 to 98.0%.

[0130] In order to more effectively suppress the whitening and the deterioration of the insulating properties, the cross-sectional image of the heat-sealable resin layer 4 of the third embodiment shows that the area of the islands in the sea-island structure is 0.30 μm 2The ratio of the total number of islands above (0.30 μm 2 The ratio (total number of the above island portions / total number of all island portions) is preferably 1.0% or less, more preferably 0.5% or less, and even more preferably 0.1% or less. The ratio of the total number is, for example, 0.0% or more.

[0131] Furthermore, from the viewpoint of more effectively suppressing the whitening and the deterioration of the insulating property, in the cross-sectional image of the heat-sealable resin layer 4 of the third embodiment, the area of the island portions relative to the total number of the island portions of the sea-island structure is set to 0.15 μm 2 The ratio of the total number of islands above (0.15 μm 2 The ratio (total number of the above island portions / total number of all island portions) is preferably 1.0% or less, more preferably 0.5% or less, and even more preferably 0.1% or less. The ratio of the total number is, for example, 0.0% or more.

[0132] Furthermore, from the viewpoint of more effectively suppressing the above-mentioned whitening and deterioration of insulating properties, in a cross-sectional image of the thermally adhesive resin layer 4 of the third embodiment, the ratio of the total area of the islands in the sea-island structure to the area of the measurement range of the cross-sectional image (total area of islands / area of measurement range of the cross-sectional image) is preferably 12.0% or less, more preferably 5.0% or less, and even more preferably 1.0% or less. The total area ratio may be, for example, 0.1% or more. Preferred ranges for the total area ratio include, for example, about 0.1 to 12.0%, about 0.1 to 5.0%, and about 0.1 to 1.0%.

[0133] In the third embodiment, the ratio of the total area of the island portions of each area can be adjusted by adjusting the conditions for forming the heat-sealable resin layer 4 in addition to the blending ratio of polypropylene and polyethylene contained in the heat-sealable resin layer 4 (for example, when the heat-sealable resin layer 4 is formed by melt extrusion molding, as described below, the cooling conditions for the heat-sealable resin layer using a chill roll can be set to rapid cooling conditions (for example, the difference in surface temperature between the melt-extruded heat-sealable resin layer and the chill roll can be set to 70°C or more), thereby suppressing crystal growth of polyethylene in the polypropylene). In addition, the type and content of at least one of the antioxidant and radical scavenger contained in the heat-sealable resin layer 4 can also be used as a means for adjusting the ratio of the total area of the island portions of each area.

[0134] In the third embodiment, the method for measuring the area ratio of the islands in the sea-island structure in the cross-sectional image of the heat-fusible resin layer 4 is as follows.

[0135] <Measurement of the area and number of islands in a sea-island structure> The casing material for an electricity storage device is embedded in a thermosetting epoxy resin and allowed to harden. A cross-section parallel to the TD and in the thickness direction y is prepared using a commercially available rotary microtome (e.g., LEICA EM UC6) and a glass knife. The cross-section is prepared using a room-temperature microtome. The heat-sealable resin layer of the casing material for an electricity storage device is stained with ruthenium tetroxide for 3 hours, along with the embedded resin. Since the resin expands upon staining, making it impossible to observe the sea-island structure near the cross-section, the expanded portion is trimmed using a microtome. After cutting approximately 1 to 2 μm, a stained section approximately 100 nm thick is taken from the cross-section using a diamond knife and observed as follows. Cross-sectional images of the stained section are obtained using a field-emission scanning electron microscope (e.g., Hitachi High-Technologies Corporation S-4800). As described above, the cross-sectional image was acquired within a range of 12.5% of the thickness of the thermally adhesive resin layer from the surface opposite the barrier layer, assuming that the total thickness of the layers located inside the barrier layer is 100%. When using a field emission scanning electron microscope, such as the S-4800 manufactured by Hitachi High-Technologies Corporation, the measurement conditions are an acceleration voltage of 30 kV, an emission current of 10 μA, a transmission detector, no tilt (0°), and a magnification of 5000x. Next, the cross-sectional image was binarized to separate the island and sea portions of the sea-island structure using image processing software capable of binarizing cross-sectional images (e.g., image analysis software included with the Keyence VHX-5000 electron microscope). For example, if the image processing software used is the image analysis software included with the Keyence VHX-5000 electron microscope, measurement is started under the brightness (standard) conditions of the image analysis software, and the extraction area (measurement range) is set to a rectangular shape (7 μm long, 13 μm wide), the image size is set to standard (1600 × 1200), the tilt angle is set to 0 degrees, the shooting mode is set to normal shooting, and the extraction target is set to "dark area." Furthermore, automatic measurement is performed to correct for missing or redundantly extracted areas, and the total area and number of extracted areas (islands) are measured. At this time, the area and number of all islands present in the extraction area are measured, respectively.Using the acquired data, the ratio of the total area of all islands to the area of the measurement range of the cross-sectional image (total area of islands / area of measurement range of the cross-sectional image) was calculated, and the area of all islands was calculated to be 0.01 μm. 2 The ratio of the total number of islands below (0.01 μm 2 (Total number of islands below / Total number of all islands), 0.02 μm 2 Percentage of the total number of islands below (0.02μm 2 (total number of islands below / total number of all islands), 0.03 μm 2 The ratio of the total number of islands below (0.03 μm 2 (total number of islands below / total number of all islands), 0.30 μm 2 The ratio of the total number of islands above (0.30 μm 2 (Total number of islands above / Total number of all islands), 0.15 μm 2 The ratio of the total number of islands above (0.15 μm 2 Calculate the total number of islands above / total number of all islands.

[0136] In the third embodiment, examples of polypropylene include homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene, block copolymers of propylene and butene, block copolymers of propylene, ethylene and butene, preferably block copolymers of propylene and ethylene), random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene, random copolymers of propylene and butene, random copolymers of propylene, ethylene and butene, preferably random copolymers of propylene and ethylene), and propylene-α-olefin copolymers. Examples of polyethylene include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and ethylene-α-olefin copolymers. The polypropylene and polyethylene contained in the heat-sealable resin layer 4 may each be one type or two or more types.

[0137] The heat-sealable resin layer 4 of the third embodiment is preferably formed of a polypropylene resin composition containing 45 mass % or less of polyethylene. The polyethylene content in the heat-sealable resin layer 4 is determined based on the ratio of the area of the islands in the sea-island structure to the total number of islands in the cross-sectional image to the area of 0.02 μm. 2 The total number of the following islands should be 80.0% or more. The polyethylene content is, for example, about 45% by mass or less, preferably about 30% by mass or less, more preferably about 20% by mass or less, and preferably about 5% by mass or more, more preferably about 10% by mass or more. Preferred ranges include about 5 to 45% by mass, about 5 to 30% by mass, about 5 to 20% by mass, about 10 to 45% by mass, about 10 to 30% by mass, and about 10 to 20% by mass. The polypropylene content is, for example, 95% by mass or less or 90% by mass or less. The polypropylene content is, for example, 55% by mass or more, 70% by mass or more, or 80% by mass or more. Preferred ranges for the polypropylene content include about 55 to 95% by mass, about 70 to 95% by mass, about 80 to 95% by mass, about 55 to 90% by mass, about 70 to 90% by mass, and about 80 to 90% by mass. The mass ratio of polypropylene to polyethylene in the polypropylene resin composition is preferably about 5 to 80 parts by mass, more preferably about 5 to 45 parts by mass, and even more preferably about 10 to 30 parts by mass of polyethylene per 100 parts by mass of polypropylene.

[0138] The heat-sealable resin layer 4 of the third embodiment may contain other resins in addition to polypropylene and polyethylene, such as the acid-modified polyolefins mentioned above.

[0139] In the third embodiment, the thermally adhesive resin layer 4 may be formed of only one layer, or may be formed of two or more layers made of the same or different resins.

[0140] The thickness of the heat-sealable resin layer 4 is not particularly limited as long as it can heat-seal the heat-sealable resin layers to each other and function to seal the electricity storage device element, but may be, for example, about 100 μm or less, preferably about 85 μm or less, and more preferably about 15 to 85 μm. For example, when the thickness of the adhesive layer 5 described below is 10 μm or more, the thickness of the heat-sealable resin layer 4 is preferably about 85 μm or less, and more preferably about 15 to 45 μm. For example, when the thickness of the adhesive layer 5 described below is less than 10 μm or when the adhesive layer 5 is not provided, the thickness of the heat-sealable resin layer 4 is preferably about 20 μm or more, and more preferably about 35 to 85 μm.

[0141] The heat-sealable resin layer 4 of the third embodiment is preferably formed by melt extrusion molding. Furthermore, when an adhesive layer 5 described below is provided, the adhesive layer 5 and the heat-sealable resin layer 4 are preferably formed by melt co-extrusion molding. In the third embodiment of the present disclosure, the molten resin forming the heat-sealable resin layer 4 is preferably cooled under rapid cooling conditions to suppress crystal growth of polyethylene in the polypropylene, and as a result, in the cross-sectional image, the area of the islands relative to the total number of islands in the sea-island structure is preferably 0.02 μm 2 Below For example, as described above, when the heat-sealable resin layer 4 is formed by melt extrusion molding or the like while appropriately adjusting the blending ratio of polypropylene and polyethylene contained in the heat-sealable resin layer 4, the cooling conditions of the molten resin (molten resin forming the heat-sealable resin layer) by a cooling roll (a roll that cools a sheet formed from the molten resin while conveying it) are set to rapid cooling conditions (for example, the difference in surface temperature between the melt-extruded heat-sealable resin layer and the cooling roll is set to 70°C or more), thereby suppressing crystal growth of polyethylene in the polypropylene, and thereby, in the cross-sectional image, the area of the islands relative to the total number of islands in the sea-island structure can be adjusted to 0.02 µm 2The ratio of the total number of the following island portions can be adjusted to 80.0% or more. Furthermore, as described above, the type and content of at least one of the antioxidant and radical scavenger contained in the heat-sealable resin layer 4 can also be used as a means for adjusting the ratio of the total area of the island portions for each area. When the adhesive layer 5 and the heat-sealable resin layer 4 are formed by melt co-extrusion molding, it is preferable that the thickness of the adhesive layer 5 is 15 to 45 μm and the thickness of the heat-sealable resin layer 4 is 15 to 45 μm.

[0142] [Adhesive layer 5] In the packaging material for an electricity storage device of the present disclosure, the adhesive layer 5 included in the inner layer is a layer provided between the barrier layer 3 (or corrosion-resistant coating) and the heat-sealable resin layer 4 in order to firmly bond them together.

[0143] In the first embodiment of the present disclosure, the adhesive layer 5 is formed from a resin that can bond the barrier layer 3 and the heat-sealable resin layer 4 and that, when the inner layer is subjected to tensile dynamic viscoelasticity measurement, exhibits an elongation of 8.0% or less at 80°C. A thermoplastic resin is preferably used as the resin used to form the adhesive layer 5. The resin used to form the adhesive layer 5 preferably contains a polyolefin skeleton, such as the polyolefins and acid-modified polyolefins exemplified for the heat-sealable resin layer 4. On the other hand, from the viewpoint of firmly bonding the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 preferably contains an acid-modified polyolefin. Examples of acid-modified components include dicarboxylic acids such as maleic acid, itaconic acid, succinic acid, and adipic acid, as well as anhydrides thereof, acrylic acid, and methacrylic acid. However, maleic anhydride is most preferred from the viewpoints of ease of modification and versatility. Furthermore, from the viewpoint of the heat resistance of the electrical storage device exterior material, the olefin component is preferably a polypropylene-based resin, and the adhesive layer 5 most preferably contains maleic anhydride-modified polypropylene.

[0144] In the present disclosure, the inclusion of a polyolefin skeleton in the resin constituting the adhesive layer 5 can be determined by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like, and the analysis method is not particularly limited. Furthermore, the inclusion of an acid-modified polyolefin in the resin constituting the adhesive layer 5 can be determined by, for example, measuring a maleic anhydride-modified polyolefin by infrared spectroscopy, and finding a peak at a wave number of 1760 cm. -1 Near and wave number 1780cm -1 A peak derived from maleic anhydride is detected around this point. However, if the degree of acid modification is low, the peak may be small and not be detected. In this case, analysis can be performed using nuclear magnetic resonance spectroscopy.

[0145] In the first embodiment of the present disclosure, the thickness of the adhesive layer 5 is preferably about 60 μm or less, about 50 μm or less, or about 45 μm or less. The thickness of the adhesive layer 5 is preferably about 10 μm or more, about 20 μm or more, about 25 μm or more, or about 30 μm or more. The thickness of the adhesive layer 5 is preferably in the range of about 10 to 60 μm, about 10 to 50 μm, about 10 to 45 μm, about 20 to 60 μm, about 20 to 50 μm, about 20 to 45 μm, about 25 to 60 μm, about 25 to 50 μm, about 25 to 45 μm, about 30 to 60 μm, about 30 to 50 μm, or about 30 to 45 μm. The adhesive layer 5 can be formed, for example, by extrusion molding the heat-sealable resin layer 4 and the adhesive layer 5 together.

[0146] In the first embodiment of the present disclosure, from the viewpoint of further improving the sealing performance of the packaging material for an electricity storage device in a high-temperature environment, the ratio of the thickness of the heat-sealable resin layer to the thickness of the adhesive layer 5 (thickness of heat-sealable resin layer 4 / thickness of adhesive layer 5) is preferably about 0.3 or more, more preferably about 0.4 or more. From the same viewpoint, the thickness ratio is preferably about 2.0 or less, more preferably about 1.5 or less. Preferred ranges for the thickness ratio are about 0.3 to 2.0, about 0.3 to 1.5, about 0.4 to 2.0, about 0.4 to 1.5, and about 1.2 to 1.4.

[0147] Furthermore, as described above, in the packaging material for an electricity storage device according to the first embodiment of the present disclosure, a suitable example of setting the elongation at 80°C in the tensile dynamic viscoelasticity measurement of the inner layer to 8.0% or less is to increase the crystallinity of the adhesive layer and the heat-sealable resin layer, and it is desirable to control the initial cooling conditions after post-heating to very slow cooling conditions to promote crystal growth of the resin in the adhesive layer and the heat-sealable resin layer. For example, by employing such a method to form the heat-sealable resin layer, the crystallinity of the adhesive layer and the heat-sealable resin layer is increased, and the sealing performance in a high-temperature environment is improved.

[0148] Furthermore, in a second embodiment of the present disclosure, the adhesive layer 5 contains a polypropylene-based resin and polyethylene. In the electrical storage device packaging material of the second embodiment, a sea-island structure is observed in a cross-sectional image of the adhesive layer 5 taken using a scanning electron microscope in a cross section parallel to the TD and in the thickness direction y. The cross-sectional image is a cross-sectional image taken within a range from the surface of the adhesive layer 5 on the barrier layer 3 side to a thickness of 25% (the area surrounded by the dashed line in FIG. 12 ), where the total thickness of the adhesive layer 5 is taken as 100%, as shown in the schematic diagram of FIG. 12 . The surface of the adhesive layer 5 on the barrier layer 3 side represents a thickness of 0%. To give a specific example, in the case of an electrical storage device packaging material in which a base layer (thickness 30 μm including the adhesive), an adhesive layer (3 μm), a barrier layer (40 μm), an adhesive layer (40 μm), and a thermally adhesive resin layer (40 μm) are laminated in this order, as in Examples 1B to 3B described below, the thickness of the adhesive layer 5, 40 μm, is taken as 100%. 12, the position of the surface of the adhesive layer 5 on the barrier layer 3 side is the position of the interface where the barrier layer 3 and the adhesive layer 5 are in contact, and the thickness at this position is set to 0%. Then, a cross-sectional image is obtained using a scanning electron microscope within the range from this surface (0% thickness) to a position at 25% thickness (i.e., assuming that the thickness of the adhesive layer 5, 40 μm, is 100%, the position at 25% thickness is a position 10 μm thick from the surface of the adhesive layer 5 on the barrier layer 3 side toward the thermally adhesive resin layer 4 side).

[0149] Observing a sea-island structure in a cross-sectional image means that a sea portion (sea part) and an island portion (island part) are observed in the cross-sectional image. As described above, when a small amount of polyethylene is added to a polypropylene-based resin and an adhesive layer is formed by melt extrusion molding, a sea-island structure is formed in which polyethylene island parts are dispersed in the sea portion of the polypropylene-based resin. In other words, the island parts contain polyethylene. To observe the sea-island structure, as described below, the cross-section of the adhesive layer 5 is stained with ruthenium tetroxide or the like, and a cross-sectional image is obtained and observed using a scanning electron microscope.

[0150] In the cross-sectional image of the adhesive layer 5 of the electrical storage device packaging material of the second embodiment, the area of the island portions relative to the total number of island portions of the sea-island structure is 0.25 μm 2 The proportion of the total number of island portions having an area of less than 0.25 μm is 40% or more. The electrical storage device packaging material of the second embodiment has such characteristics, and thereby the sealing performance of the electrical storage device packaging material in a high-temperature environment is improved. That is, in the electrical storage device packaging material of the second embodiment of the present disclosure, in the adhesive layer 5 containing a polypropylene-based resin and polyethylene, the proportion of the total number of island portions having an area of less than 0.25 μm is 40% or more. 2 The ratio of the total number of particles occupying the minute island portion of less than 1000 is set high. As a result, minute islands of polyethylene are dispersed in the sea of polypropylene resin in the adhesive layer 5, suppressing separation of the polypropylene resin and polyethylene. This is thought to maintain hermeticity even when the electricity storage device is placed in a high-temperature environment, causing the internal pressure to increase and applying a large stress to the exterior material for the electricity storage device.

[0151] From the viewpoint of more suitably achieving the effects of the invention of the second embodiment, in the cross-sectional image of the adhesive layer 5, the area of the island portions is 0.25 μm 2 with respect to the total number of island portions of the sea-island structure. 2 The ratio of the total number of islands less than 0.25 μm 2The ratio (total number of island portions less than 1 / total number of all island portions) is preferably about 41% or more, more preferably about 50% or more, even more preferably about 55% or more, even more preferably about 65% or more, and even more preferably about 75% or more. The percentage of the total number is, for example, about 100% or less, about 99% or less, about 98% or less, about 90% or less, or about 85% or less. Preferred ranges of the percentage of the total number include, for example, about 40 to 100%, about 40 to 99%, about 40 to 98%, about 40 to 90%, about 40 to 85%, about 41 to 100%, about 41 to 99%, about 41 to 98%, about 41 to 90%, about 41 to 85%, about 50 to 100%, about 50 to 99%, about 50 to 98%, about 50 to 90%, and Examples include approximately 50 to 85%, approximately 55 to 100%, approximately 55 to 99%, approximately 55 to 98%, approximately 55 to 90%, approximately 55 to 85%, approximately 65 to 100%, approximately 65 to 99%, approximately 65 to 98%, approximately 65 to 90%, approximately 65 to 85%, approximately 75 to 100%, approximately 75 to 99%, approximately 75 to 98%, approximately 75 to 90%, and approximately 75 to 85%.

[0152] In order to more suitably achieve the effects of the second embodiment of the invention, in the cross-sectional image of the adhesive layer 5, the area of the island portions is 0.15 μm 2 with respect to the total number of island portions of the sea-island structure. 2 The ratio of the total number of islands less than 0.15 μm 2 The ratio (total number of island portions less than 1 / total number of all island portions) is preferably about 10% or more, more preferably about 20% or more, even more preferably about 25% or more, even more preferably about 30% or more, even more preferably about 40% or more, even more preferably about 50% or more, and even more preferably about 60% or more. The percentage of the total number is, for example, about 85% or less, about 80% or less, etc. Preferred ranges for the percentage of the total number include, for example, about 10 to 85%, about 10 to 80%, about 20 to 85%, about 20 to 80%, about 25 to 85%, about 25 to 80%, about 30 to 85%, about 30 to 80%, about 40 to 85%, about 40 to 80%, about 50 to 85%, about 50 to 80%, about 60 to 85%, and about 60 to 80%.

[0153] In order to more suitably achieve the effects of the second embodiment of the invention, in the cross-sectional image of the adhesive layer 5, the area of the island portions is 0.10 μm 2 with respect to the total number of island portions of the sea-island structure. 2 The ratio of the total number of islands less than 0.10 μm 2 The ratio (total number of islands less than 1 / total number of all islands) is preferably about 10% or more, more preferably about 15% or more, even more preferably about 20% or more, even more preferably about 30% or more, even more preferably about 40% or more, and even more preferably about 50% or more. The percentage of the total number is, for example, about 80% or less, about 75% or less, etc. Preferred ranges for the percentage of the total number include, for example, about 10 to 60%, about 10 to 50%, about 15 to 60%, about 15 to 50%, about 20 to 60%, about 20 to 50%, about 30 to 60%, and about 30 to 50%.

[0154] In addition, from the viewpoint of more suitably achieving the effects of the invention of the second embodiment, in the cross-sectional image of the adhesive layer 5, the area of the island portions relative to the total number of the island portions of the sea-island structure is 1.50 μm 2 The ratio of the total number of islands above (1.50 μm 2 The ratio (total number of the above island portions / total number of all island portions) is preferably about 10% or less, more preferably about 9% or less, even more preferably about 8% or less, and even more preferably about 5% or less. The percentage of the total number is, for example, about 0% or more, about 1% or more, etc. Preferred ranges for the percentage of the total number include, for example, about 0 to 10%, about 0 to 9%, about 0 to 8%, about 0 to 5%, about 1 to 10%, about 1 to 9%, about 1 to 8%, and about 1 to 5%.

[0155] The ratio of the total number of island portions for each area can be set to the above value by adjusting the conditions for forming the adhesive layer 5 in addition to the blending ratio of the polypropylene resin and polyethylene contained in the adhesive layer 5. For example, as described later, by setting the temperature (the temperature when the pellets are melted and kneaded in a twin-screw extruder to melt) to a low temperature when forming pellets in which polyethylene is highly uniformly dispersed in the polypropylene resin into a film by melt extrusion, and by shortening the time (residence time) from when the resin is melted until it is formed into a film, aggregation of polyethylene in the polypropylene resin can be suppressed, and a density of 0.25 μm can be achieved. 2 The formation of the above-mentioned island portions is suppressed. The ratio of the total number of island portions for each area can also be adjusted by adding at least one selected from the group consisting of an antioxidant and a radical scavenger to the adhesive layer 5. Furthermore, the above value can also be adjusted by appropriately adjusting the type and content of the antioxidant or radical scavenger.

[0156] The method for measuring the total number of islands in each area in the sea-island structure in the cross-sectional image of the adhesive layer 5 is as follows.

[0157] <Measurement of the area and number of islands in a sea-island structure> The casing material for an electricity storage device is embedded in a thermosetting epoxy resin and allowed to harden. A cross-section parallel to the TD and in the thickness direction y is prepared using a commercially available rotary microtome (e.g., LEICA EM UC6) and a glass knife. The cross-section is prepared using a room-temperature microtome. The adhesive layer of the casing material for an electricity storage device is stained with ruthenium tetroxide along with the embedding resin for 3 hours. Since the staining causes the resin to expand and the sea-island structure cannot be observed near the cross-section, the expanded portion is trimmed using a microtome. After cutting approximately 1 to 2 μm, stained sections approximately 100 nm thick are taken using a diamond knife and observed as follows. Cross-sectional images of the stained sections are obtained using a field-emission scanning electron microscope (e.g., Hitachi High-Technologies Corporation S-4800). As mentioned above, the cross-sectional image was acquired within a range of 25% of the thickness of the adhesive layer from the surface on the barrier layer side, assuming the total thickness of the adhesive layer to be 100%. When using a field emission scanning electron microscope, such as the S-4800 manufactured by Hitachi High-Technologies Corporation, the measurement conditions are an acceleration voltage of 30 kV, an emission current of 10 μA, a transmission detector, no tilt (0°), and an observation magnification of 5000x. Next, using image processing software capable of binarizing cross-sectional images (e.g., image analysis software included with the Keyence VHX-5000 electron microscope), the island and sea portions of the sea-island structure in the cross-sectional image are binarized. For example, if the image analysis software included with the Keyence electron microscope VHX-5000 is used as the image processing software, measurement is started under the brightness (standard) conditions of the image analysis software, the extracted area (measurement range) is set to a rectangular shape (7 μm long, 13 μm wide), the image size is set to standard (1600 × 1200), the tilt angle is set to 0 degrees, the shooting mode is set to normal shooting, and the extraction target is set to "dark area." Furthermore, automatic measurement is used to correct for missing extraction areas and extraneous extracted areas, and the total area and total number of extracted areas (islands) are measured. At this time, the area and number of all islands present in the extracted area are measured. The acquired data is used to calculate the island area (μm 2 ) and the ratio (%) of the number of islands in the area to the total number of all islands (for example, the above (0.25 μm 2(total number of islands less than 0.20 μm / total number of all islands) 2 (total number of islands less than 0.10 μm / total number of all islands) 2 Calculate the total number of islands less than 1 / total number of all islands, etc.

[0158] In the second embodiment, the polypropylene resin is preferably acid-modified polypropylene because it has excellent adhesion to the barrier layer 3 and the heat-sealable resin layer. Acid-modified polypropylene is a polymer modified by block polymerization or graft polymerization of polypropylene with an acid component.

[0159] In the second embodiment, specific examples of the polypropylene to be acid-modified include 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); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. When the polyolefin resin is a copolymer, it may be a block copolymer or a random copolymer. These polyolefin resins may be used alone or in combination of two or more.

[0160] In the second embodiment, the acid-modified polypropylene may be a copolymer obtained by copolymerizing the above-mentioned polypropylene with a polar molecule such as acrylic acid or methacrylic acid, or a polymer such as cross-linked polypropylene. Examples of the acid component used for the acid modification include carboxylic acids or anhydrides thereof, such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

[0161] In the second embodiment, the acid-modified polypropylene may be an acid-modified cyclic polypropylene. The acid-modified cyclic polypropylene is a polymer obtained by copolymerizing a part of the monomers constituting the cyclic polypropylene with an acid component instead, or by block-polymerizing or graft-polymerizing the acid component onto the cyclic polypropylene. The cyclic polyolefin to be acid-modified is the same as described above. The acid component used for the acid modification is the same as the acid component used for the modification of the polypropylene.

[0162] In the second embodiment, the acid-modified polypropylene preferably includes polypropylene modified with a carboxylic acid or anhydride thereof, and more preferably includes maleic anhydride-modified polypropylene.

[0163] In the second embodiment, examples of polyethylene include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and ethylene-α-olefin copolymer.

[0164] In the second embodiment, the adhesive layer 5 is preferably formed of a polypropylene resin composition containing a polypropylene resin and 45% by mass or less of polyethylene. The preferred polypropylene resins are as described above. The polyethylene content in the adhesive layer 5 is determined by the ratio of the area of the islands in the sea-island structure to the total number of islands in the sea-island structure in the cross-sectional image. 2The total number of island portions less than 100% is adjusted to 40% or more. The polyethylene content in the resin composition forming the adhesive layer is, for example, about 45% by mass or less, preferably about 30% by mass or less, and also preferably about 5% by mass or more, more preferably about 10% by mass or more, even more preferably about 15% by mass or more, and even more preferably 20% by mass or more. Preferred ranges include about 5 to 45% by mass, about 5 to 30% by mass, about 10 to 45% by mass, about 10 to 30% by mass, about 15 to 45% by mass, about 15 to 30% by mass, about 20 to 45% by mass, and about 20 to 30% by mass. The polypropylene resin content is, for example, 95% by mass or less, 90% by mass or less, 85% by mass or less, or 80% by mass or less. The polypropylene resin content is, for example, 55% by mass or more, or 70% by mass or more. Preferred ranges for the polypropylene resin content include about 55 to 95% by mass, about 55 to 90% by mass, about 55 to 85% by mass, about 55 to 80% by mass, about 70 to 95% by mass, about 70 to 90% by mass, about 70 to 85% by mass, and about 70 to 80% by mass. The mass ratio of polypropylene resin to polyethylene in the polypropylene resin composition that forms adhesive layer 5 is preferably about 5 to 80 parts by mass, more preferably about 5 to 45 parts by mass, and even more preferably about 10 to 30 parts by mass of polyethylene per 100 parts by mass of polypropylene resin.

[0165] In the second embodiment, the adhesive layer 5 may contain other resins in addition to the polypropylene resin and polyethylene. However, the total proportion of the polypropylene resin and polyethylene among the resins contained in the adhesive layer 5 is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more. In particular, the total proportion of the acid-modified polypropylene and polyethylene among the resins contained in the adhesive layer 5 is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0166] In the second embodiment, the adhesive layer 5 is usually provided so as to be in contact with the barrier layer 3 (or the corrosion-resistant coating), and is a single layer.

[0167] In the second embodiment, the thickness of the adhesive layer 5 is preferably about 80 μm or less, about 60 μm or less, or about 50 μm or less. Furthermore, the thickness of the adhesive layer 5 is preferably about 5 μm or more, about 10 μm or more, about 20 μm or more, or about 30 μm or more. The thickness range is preferably about 5 to 80 μm, about 5 to 60 μm, about 5 to 50 μm, about 10 to 80 μm, about 10 to 60 μm, about 10 to 50 μm, about 20 to 80 μm, about 20 to 60 μm, about 20 to 50 μm, about 30 to 80 μm, about 30 to 60 μm, or about 30 to 50 μm.

[0168] (Antioxidants and radical scavengers) In the electrical storage device packaging material 10 of the second embodiment, from the viewpoint of further improving the sealing performance in a high-temperature environment, at least one layer inside the barrier layer 3 preferably contains at least one selected from the group consisting of an antioxidant and a radical scavenger. Examples of layers inside the barrier layer 3 (hereinafter sometimes referred to as "inner layer") include the thermally adhesive resin layer 4 and the adhesive layer 5. At least one selected from the group consisting of an antioxidant and a radical scavenger is preferably contained in at least one layer of the thermally adhesive resin layer 4 and the adhesive layer 5. That is, at least one selected from the group consisting of an antioxidant and a radical scavenger may be contained in both the thermally adhesive resin layer 4 and the adhesive layer 5, or may be contained only in the thermally adhesive resin layer 4, or may be contained only in the adhesive layer 5. In the second embodiment, an antioxidant may be blended to suppress oxidation of the inner layer in a high-temperature environment when the inner layer is formed. In addition, in the second embodiment, a radical scavenger may be blended to capture radicals generated in the inner layer in a high-temperature environment when the inner layer is formed.

[0169] In the second embodiment, the antioxidant is not particularly limited as long as it does not impair the effects of the second embodiment. Specific examples of the antioxidant include tris(2,4-di-t-butylphenoxy)phosphine, 2,2-methylenebis(4,6-di-t-butylphenyl)-2-ethylhexyl phosphite, 4,4'-butylidene-bis(3-methyl-6-t-butylphenylditridecyl)phosphite, 6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t-butyl Phosphorus-based antioxidants such as tetrakis(methylene-3-(3,5-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite), tetrakis(2,4-di-t-butylphenyl)-4,4'-bisphenyldiphosphonite, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, and bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite; -hydroxyphenyl)propionate)methane, 1,3,5-tris[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 3,9-bis(2-(3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate)methane Examples of antioxidants include phenolic antioxidants such as (1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro(5,5)undecane, and sulfur-based antioxidants such as tetrakis[methylene-3-(laurylthio)propionate]methane, dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, and distearyl-3,3'-thiodipropionate. The antioxidant contained in the layer(s) inner than the barrier layer 3 may be one type or two or more types.

[0170] In the second embodiment, preferred examples of the phosphorus-based antioxidant include compounds represented by the following general formula (A).

[0171] [ka]

[0172] The presence of the compound represented by general formula (A) in the inner layer can be confirmed by using various analytical methods such as NMR.

[0173] In general formula (A), R 11 and R 12 are each independently an alkyl group having 1 to 18 carbon atoms or a phenyl group which may have a substituent. 11 and R 12 and each independently represent a phenyl group which may have a substituent. The compound represented by general formula (A) contained in the inner layer may be one type, or two or more types.

[0174] In general formula (A), R 11 and R 12 Preferably, the phenyl groups in R each independently have at least one substituent selected from the group consisting of an alkyl group having 1 to 9 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, an alkylcycloalkyl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms. Among these groups, the phenyl group preferably has at least one of an alkyl group having 1 to 9 carbon atoms and an aralkyl group having 7 to 12 carbon atoms as a substituent. Furthermore, R 11 and R 12 The number of substituents on each of the phenyl groups may be 1 to 5, and preferably 2 to 3.

[0175] Preferable specific examples of the compound represented by the general formula (A) include a compound represented by the following formula (A1) (bis(2,4-dicumylphenyl)pentaerythritol diphosphite) and a compound represented by the following formula (A2) (bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite).

[0176] [ka]

[0177] In the second embodiment, it is particularly preferable that the inner layer contains a compound represented by the formula (A1) as the compound represented by the general formula (A).

[0178] As described above, in the second embodiment, the thermally adhesive resin layer 4 and the adhesive layer 5 may each be a single layer or multiple layers. When the thermally adhesive resin layer 4 and the adhesive layer 5 are multiple layers, at least one of the layers may contain the compound represented by the general formula (A). For example, the compound represented by the general formula (A) may be contained in both the thermally adhesive resin layer 4 and the adhesive layer 5, or may be contained only in the thermally adhesive resin layer 4, or may be contained only in the adhesive layer 5. When the compound represented by the general formula (A) is contained in at least one of the layers constituting the inner layer, the resin forming the layer can be heated to a higher temperature (e.g., 300°C or higher) than conventionally to form the layer, thereby shortening the lead time. Furthermore, the layer is suppressed from deteriorating due to high temperatures and can exhibit high insulating properties.

[0179] In an electricity storage device, since the inner layer comes into contact with the electrolyte, there is concern about adverse effects due to the antioxidant contained in the inner layer leaching into the electrolyte. However, the compound represented by formula (A1) has low solubility in electrolyte solvents, and even when a large amount is added to improve insulation, it is expected that there will be little adverse effect on the characteristics of the electricity storage device. Examples of solvents for the electrolyte of an electricity storage device include cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and vinylene carbonate (VC); chain carbonates such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and dipropyl carbonate (DPC); aliphatic carboxylic acid esters such as methyl formate, methyl acetate, methyl propionate, and ethyl propionate; γ-lactones such as γ-butyrolactone; Examples of suitable solvents include chain ethers such as 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), and ethoxymethoxyethane (EME); cyclic ethers such as tetrahydrofuran and 2-methyltetrahydrofuran; dimethyl sulfoxide, formamide, acetamide, dimethylformamide, dimethylacetamide, dioxolane, acetonitrile, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, propylene carbonate derivatives, tetrahydrofuran derivatives, and dimethyl sulfoxide. These may be used alone or in combination of two or more. Among these, at least one of cyclic carbonates, chain carbonates, and aliphatic carboxylic acid esters is preferably used. In particular, a mixture of a cyclic carbonate and a chain carbonate, or a mixture of a cyclic carbonate, a chain carbonate, and an aliphatic carboxylic acid ester is preferably used.

[0180] The antioxidant content in the inner layer containing the antioxidant is not particularly limited as long as the effects of the second embodiment are achieved, but is preferably about 0.01% by mass or more, more preferably about 0.03% by mass or more, and even more preferably about 0.05% by mass or more. The content is preferably about 2% by mass or less, more preferably about 1% by mass or less, and even more preferably about 0.5% by mass or less. Preferred ranges for the content include about 0.01 to 2% by mass, about 0.01 to 1% by mass, about 0.01 to 0.5% by mass, about 0.03 to 2% by mass, about 0.03 to 1% by mass, and about 0.03 to 0.5% by mass.

[0181] In the second embodiment, the inner layer may contain a radical scavenger. The radical scavenger is not particularly limited, and examples thereof include alkyl radical scavengers, alkoxy radical scavengers, and peroxy radical scavengers. Examples of alkyl radical scavengers include compounds having an acrylate group and a phenolic hydroxyl group in the same molecule, such as 1'-hydroxy[2,2'-ethylidenebis[4,6-bis(1,1-dimethylpropyl)benzene]]-1-yl acrylate and 2-t-butyl-4-methyl-6-(2-hydroxy-3-t-butyl-5-methylbenzyl)phenyl acrylate. When a radical scavenger is contained in the inner layer, the radical scavenger may be one type or two or more types.

[0182] When a radical scavenger is contained in the inner layer, the content of the radical scavenger in the inner layer containing the radical scavenger is not particularly limited as long as the effects of the second embodiment described above are achieved. However, from the viewpoint of more optimally achieving the effects of the second embodiment, the content is preferably about 0.01% by mass or more, more preferably about 0.03% by mass or more. Furthermore, the content is preferably about 0.5% by mass or less, more preferably about 0.3% by mass or less, and even more preferably about 0.2% by mass or less. Preferred ranges for the content include about 0.01 to 0.5% by mass, about 0.01 to 0.3% by mass, about 0.01 to 0.2% by mass, about 0.03 to 0.5% by mass, about 0.03 to 0.3% by mass, and about 0.03 to 0.2% by mass.

[0183] In the third embodiment, the adhesive layer 5 is formed of a resin capable of bonding the barrier layer 3 and the heat-sealable resin layer 4. The resin used to form the adhesive layer 5 can be, for example, the same adhesive as exemplified for the adhesive layer 2. The resin used to form the adhesive layer 5 preferably contains a polyolefin skeleton, such as the polyolefins and acid-modified polyolefins exemplified for the heat-sealable resin layer 4. The presence of a polyolefin skeleton in the resin constituting the adhesive layer 5 can be determined by, for example, infrared spectroscopy or gas chromatography-mass spectrometry, and the analysis method is not particularly limited. Furthermore, when the resin constituting the adhesive layer 5 is analyzed by infrared spectroscopy, a peak derived from maleic anhydride is preferably detected. For example, when a maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak derived from maleic anhydride is detected at a wavenumber of 1760 cm. -1 Near and wave number 1780cm -1 A peak derived from maleic anhydride is detected around this point. However, if the degree of acid modification is low, the peak may be small and not be detected. In this case, analysis can be performed using nuclear magnetic resonance spectroscopy.

[0184] In the third embodiment, the adhesive layer 5 preferably contains an acid-modified polyolefin from the viewpoint of firmly bonding the barrier layer 3 and the heat-sealable resin layer 4. Particularly preferred examples of the acid-modified polyolefin include polyolefins modified with carboxylic acid or its anhydride, polypropylenes modified with carboxylic acid or its anhydride, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

[0185] Furthermore, in the third embodiment, from the viewpoint of reducing the thickness of the electrical storage device packaging material while providing an electrical storage device packaging material that has excellent shape stability after molding, the adhesive layer 5 is more preferably a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. Preferred examples of the acid-modified polyolefin include those mentioned above.

[0186] In the third embodiment, the adhesive layer 5 is preferably a cured product of a resin composition containing an acid-modified polyolefin and at least one selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and a compound having an epoxy group. It is particularly preferably a cured product of a resin composition containing an acid-modified polyolefin and at least one selected from the group consisting of a compound having an isocyanate group and a compound having an epoxy group. The adhesive layer 5 preferably contains at least one selected from the group consisting of polyurethane, polyester, and epoxy resin, and more preferably contains polyurethane and epoxy resin. A preferred polyester is, for example, an amide ester resin. Amide ester resins are generally produced by the reaction of a carboxyl group with an oxazoline group. It is more preferred that the adhesive layer 5 is a cured product of a resin composition containing at least one of these resins and the acid-modified polyolefin. In addition, if unreacted compounds of curing agents such as compounds having an isocyanate group, compounds having an oxazoline group, and epoxy resins remain in the adhesive layer 5, the presence of the unreacted compounds can be confirmed by a method selected from, for example, infrared spectroscopy, Raman spectroscopy, time-of-flight secondary ion mass spectrometry (TOF-SIMS), etc.

[0187] In the third embodiment, in order to further enhance the adhesion between the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 is preferably a cured product of a resin composition containing a curing agent having at least one selected from the group consisting of an oxygen atom, a heterocycle, a C═N bond, and a COC bond. Examples of curing agents having a heterocycle include curing agents having an oxazoline group and curing agents having an epoxy group. Examples of curing agents having a C═N bond include curing agents having an oxazoline group and curing agents having an isocyanate group. Examples of curing agents having a COC bond include curing agents having an oxazoline group, curing agents having an epoxy group, and polyurethane. Whether the adhesive layer 5 is a cured product of a resin composition containing such a curing agent can be confirmed by, for example, gas chromatography mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), or other methods.

[0188] In the third embodiment, the compound having an isocyanate group is not particularly limited, but from the viewpoint of effectively improving the adhesion between the barrier layer 3 and the adhesive layer 5, a polyfunctional isocyanate compound is preferably used. The polyfunctional isocyanate compound is not particularly limited as long as it is a compound having two or more isocyanate groups. Specific examples of polyfunctional isocyanate curing agents include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymers or nurates thereof, mixtures of these, and copolymers with other polymers. Other examples include adducts, biuret compounds, and isocyanurates.

[0189] In the third embodiment, the content of the compound having an isocyanate group in the adhesive layer 5 is preferably in the range of 0.1 to 50 mass %, and more preferably in the range of 0.5 to 40 mass %, in the resin composition constituting the adhesive layer 5. This can effectively improve the adhesion between the barrier layer 3 and the adhesive layer 5.

[0190] In the third embodiment, the compound having an oxazoline group is not particularly limited as long as it is a compound having an oxazoline skeleton. Specific examples of the compound having an oxazoline group include those having a polystyrene main chain and those having an acrylic main chain. Furthermore, examples of commercially available products include the Epocross series manufactured by Nippon Shokubai Co., Ltd.

[0191] In the third embodiment, the proportion of the compound having an oxazoline group in the adhesive layer 5 is preferably in the range of 0.1 to 50 mass %, and more preferably in the range of 0.5 to 40 mass %, in the resin composition constituting the adhesive layer 5. This makes it possible to effectively improve the adhesion between the barrier layer 3 and the adhesive layer 5.

[0192] In the third embodiment, an example of a compound having an epoxy group is an epoxy resin. The epoxy resin is not particularly limited as long as it is a resin capable of forming a crosslinked structure by the epoxy groups present in the molecule, and known epoxy resins can be used. The weight-average molecular weight of the epoxy resin is preferably about 50 to 2,000, more preferably about 100 to 1,000, and even more preferably about 200 to 800. In the first disclosure, the weight-average molecular weight of the epoxy resin is a value measured by gel permeation chromatography (GPC) under conditions using polystyrene as a standard sample.

[0193] In the third embodiment, specific examples of the epoxy resin include a glycidyl ether derivative of trimethylolpropane, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, polyglycerin polyglycidyl ether, etc. One type of epoxy resin may be used alone, or two or more types may be used in combination.

[0194] In the third embodiment, the proportion of the epoxy resin in the adhesive layer 5 is preferably in the range of 0.1 to 50 mass %, and more preferably in the range of 0.5 to 40 mass %, in the resin composition constituting the adhesive layer 5. This makes it possible to effectively improve the adhesion between the barrier layer 3 and the adhesive layer 5.

[0195] In the third embodiment, the polyurethane is not particularly limited, and any known polyurethane can be used. The adhesive layer 5 may be, for example, a cured product of two-component curing polyurethane.

[0196] In the third embodiment, the proportion of polyurethane in the adhesive layer 5 is preferably in the range of 0.1 to 50 mass %, and more preferably in the range of 0.5 to 40 mass %, in the resin composition constituting the adhesive layer 5. This effectively improves the adhesion between the barrier layer 3 and the adhesive layer 5 in an atmosphere containing a component that induces corrosion of the barrier layer, such as an electrolyte solution.

[0197] In the third embodiment, when the adhesive layer 5 is a cured product of a resin composition containing at least one selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and an epoxy resin, and the acid-modified polyolefin, the acid-modified polyolefin functions as the main agent, and the compound having an isocyanate group, the compound having an oxazoline group, and the compound having an epoxy group each function as a curing agent.

[0198] In the third embodiment, the thickness of the adhesive layer 5 is preferably about 50 μm or less, about 45 μm or less, about 30 μm or less, about 20 μm or less, or about 5 μm or less, and is preferably about 0.1 μm or more, about 0.5 μm or more, about 5 μm or more, about 10 μm or more, or about 15 μm or more. The thickness range is preferably about 0.1 to 50 μm, about 0.1 to 45 μm, about 0.1 to 30 μm, about 0.1 to 20 μm, about 0.1 to 5 μm, about 0.5 to 50 μm, about 0.5 to 45 μm, about 0.5 to 30 μm, about 0.5 to 20 μm, about 0.5 to 5 μm, about 5 to 50 μm, about 5 to 45 μm, about 5 to 30 μm, about 5 to 20 μm, about 10 to 50 μm, about 10 to 45 μm, about 10 to 30 μm, about 10 to 20 μm, about 15 to 50 μm, about 15 to 45 μm, about 15 to 30 μm, or about 15 to 20 μm.

[0199] More specifically, in the third embodiment, particularly when the adhesive layer 2 is an adhesive such as that exemplified above, or a cured product of an acid-modified polyolefin and a curing agent, the thickness is preferably about 1 to 10 μm, more preferably about 1 to 5 μm. Furthermore, particularly when a resin such as an acid-modified polyolefin is used as an example of the heat-sealable resin layer 4, the thickness is preferably about 5 to 50 μm, about 5 to 45 μm, about 10 to 50 μm, about 10 to 45 μm, about 15 to 50 μm, or about 15 to 45 μm. When the adhesive layer 5 is an adhesive such as that exemplified above, or a cured product of a resin composition containing an acid-modified polyolefin and a curing agent, the adhesive layer 5 can be formed, for example, by applying the resin composition and curing it by heating or the like. Furthermore, when a resin such as that exemplified above is used as the heat-sealable resin layer 4, the heat-sealable resin layer 4 and the adhesive layer 5 can be suitably formed, for example, by melt co-extrusion molding.

[0200] (Antioxidants and radical scavengers) The electrical storage device packaging material 10 of the third embodiment contains at least one of an antioxidant and a radical scavenger in at least one of the layers located inside the barrier layer 3. Examples of layers located inside the barrier layer 3 (hereinafter sometimes referred to as "inner layers") include the thermally adhesive resin layer 4 and the adhesive layer 5. At least one of the antioxidant and the radical scavenger is preferably contained in at least one of the thermally adhesive resin layer 4 and the adhesive layer 5. That is, the antioxidant and the radical scavenger may each be contained in both the thermally adhesive resin layer 4 and the adhesive layer 5, or may be contained only in the thermally adhesive resin layer 4, or may be contained only in the adhesive layer 5. In the third embodiment, the antioxidant is blended to suppress oxidation of the inner layer in a high-temperature environment when the inner layer is formed. In addition, in the third embodiment, the radical scavenger is blended to capture radicals generated in the inner layer in a high-temperature environment when the inner layer is formed.

[0201] In the third embodiment, the antioxidant is not particularly limited as long as it does not impair the effects of the third embodiment. Specific examples of the antioxidant include tris(2,4-di-t-butylphenoxy)phosphine, 2,2-methylenebis(4,6-di-t-butylphenyl)-2-ethylhexyl phosphite, 4,4'-butylidene-bis(3-methyl-6-t-butylphenylditridecyl)phosphite, 6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t-butyl Phosphorus-based antioxidants such as tetrakis(methylene-3-(3,5-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite), tetrakis(2,4-di-t-butylphenyl)-4,4'-bisphenyldiphosphonite, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, and bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite; -hydroxyphenyl)propionate)methane, 1,3,5-tris[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 3,9-bis(2-(3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate)methane and sulfur-based antioxidants such as tetrakis[methylene-3-(laurylthio)propionate]methane, dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, and distearyl-3,3'-thiodipropionate. The layer(s) contained inside the barrier layer 3 may contain one type of antioxidant, or two or more types of antioxidants.

[0202] In the third embodiment, preferred examples of the phosphorus-based antioxidant include compounds represented by the following general formula (A).

[0203] [ka]

[0204] The presence of the compound represented by general formula (A) in the inner layer can be confirmed by using various analytical methods such as NMR.

[0205] In general formula (A), R 11 and R 12 are each independently an alkyl group having 1 to 18 carbon atoms or a phenyl group which may have a substituent. 11 and R 12 and each independently represent a phenyl group which may have a substituent. The compound represented by general formula (A) contained in the inner layer may be one type, or two or more types.

[0206] In general formula (A), R 11 and R 12 Preferably, the phenyl groups in R each independently have at least one substituent selected from the group consisting of an alkyl group having 1 to 9 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, an alkylcycloalkyl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms. Among these groups, the phenyl group preferably has at least one of an alkyl group having 1 to 9 carbon atoms and an aralkyl group having 7 to 12 carbon atoms as a substituent. Furthermore, R 11 and R 12 The number of substituents on each of the phenyl groups may be 1 to 5, and preferably 2 to 3.

[0207] Preferable specific examples of the compound represented by the general formula (A) include a compound represented by the following formula (A1) (bis(2,4-dicumylphenyl)pentaerythritol diphosphite) and a compound represented by the following formula (A2) (bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite).

[0208] [ka]

[0209] In the third embodiment, it is particularly preferable that the inner layer contains a compound represented by the formula (A1) as the compound represented by the general formula (A).

[0210] As described above, in the third embodiment, the inner layer may be a single layer or multiple layers. When the inner layer is multiple layers, at least one of the layers contained in the inner layer may contain the compound represented by the general formula (A). For example, the compound represented by the general formula (A) may be contained in both the thermally adhesive resin layer 4 and the adhesive layer 5, or may be contained only in the thermally adhesive resin layer 4, or may be contained only in the adhesive layer 5. By containing the compound represented by the general formula (A) in at least one of the layers constituting the inner layer, the resin forming the layer can be heated to a higher temperature (e.g., 300°C or higher) than conventionally to form the layer, thereby shortening the lead time. Furthermore, the layer is less susceptible to deterioration due to high temperatures and can exhibit high insulating properties.

[0211] In an electricity storage device, since the inner layer comes into contact with the electrolyte, there is concern about adverse effects due to the antioxidant contained in the inner layer eluting into the electrolyte. However, in the third embodiment, the compound represented by formula (A1) has low solubility in electrolyte solvents, and even when a large amount is added to improve insulation, it is expected that there will be little adverse effect on the characteristics of the electricity storage device. Examples of solvents for the electrolyte of an electricity storage device include cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and vinylene carbonate (VC); chain carbonates such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and dipropyl carbonate (DPC); aliphatic carboxylic acid esters such as methyl formate, methyl acetate, methyl propionate, and ethyl propionate; γ-lactones such as γ-butyrolactone; Examples of suitable solvents include chain ethers such as 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), and ethoxymethoxyethane (EME); cyclic ethers such as tetrahydrofuran and 2-methyltetrahydrofuran; dimethyl sulfoxide, formamide, acetamide, dimethylformamide, dimethylacetamide, dioxolane, acetonitrile, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, propylene carbonate derivatives, tetrahydrofuran derivatives, and dimethyl sulfoxide. These may be used alone or in combination of two or more. Among these, at least one of cyclic carbonates, chain carbonates, and aliphatic carboxylic acid esters is preferably used. In particular, a mixture of a cyclic carbonate and a chain carbonate, or a mixture of a cyclic carbonate, a chain carbonate, and an aliphatic carboxylic acid ester is preferably used.

[0212] The antioxidant content in the inner layer containing the antioxidant is not particularly limited as long as the effects of the third embodiment are achieved, but is preferably about 0.01% by mass or more, more preferably about 0.03% by mass or more, and even more preferably about 0.05% by mass or more. The content is preferably about 2% by mass or less, more preferably about 1% by mass or less, and even more preferably about 0.5% by mass or less. Preferred ranges for the content include about 0.01 to 2% by mass, about 0.01 to 1% by mass, about 0.01 to 0.5% by mass, about 0.03 to 2% by mass, about 0.03 to 1% by mass, and about 0.03 to 0.5% by mass.

[0213] In the third embodiment, the inner layer may contain a radical scavenger. The radical scavenger is not particularly limited, and examples thereof include alkyl radical scavengers, alkoxy radical scavengers, and peroxy radical scavengers. Examples of alkyl radical scavengers include compounds having an acrylate group and a phenolic hydroxyl group in the same molecule, such as 1'-hydroxy[2,2'-ethylidenebis[4,6-bis(1,1-dimethylpropyl)benzene]]-1-yl acrylate and 2-t-butyl-4-methyl-6-(2-hydroxy-3-t-butyl-5-methylbenzyl)phenyl acrylate. When a radical scavenger is contained in the inner layer, the radical scavenger may be one type or two or more types.

[0214] When a radical scavenger is contained in the inner layer, the content of the radical scavenger in the inner layer containing the radical scavenger is not particularly limited as long as the effects of the third embodiment described above are achieved. However, from the viewpoint of more optimally achieving the effects of the third embodiment, the content is preferably about 0.01% by mass or more, more preferably about 0.03% by mass or more. Furthermore, the content is preferably about 0.5% by mass or less, more preferably about 0.3% by mass or less, and even more preferably about 0.2% by mass or less. Preferred ranges for the content include about 0.01 to 0.5% by mass, about 0.01 to 0.3% by mass, about 0.01 to 0.2% by mass, about 0.03 to 0.5% by mass, about 0.03 to 0.3% by mass, and about 0.03 to 0.2% by mass.

[0215] [Surface coating layer 6] The packaging material for an electricity storage device according to the present disclosure may have a surface coating layer 6 on the substrate layer 1 (the side of the substrate layer 1 opposite to the barrier layer 3) as needed, for the purpose of improving at least one of design, electrolyte resistance, scratch resistance, formability, etc. The surface coating layer 6 is a layer located on the outermost layer side of the packaging material for an electricity storage device when an electricity storage device is assembled using the packaging material for an electricity storage device.

[0216] The surface coating layer 6 can be formed from a resin such as polyvinylidene chloride, polyester, polyurethane, acrylic resin, or epoxy resin.

[0217] When the resin forming the surface coating layer 6 is a curable resin, the resin may be either a one-component curable resin or a two-component curable resin, but is preferably a two-component curable resin. Examples of two-component curable resins include two-component curable polyurethane, two-component curable polyester, and two-component curable epoxy resin. Among these, two-component curable polyurethane is preferred.

[0218] Examples of two-component curing polyurethanes include polyurethanes containing a polyol compound as a base component and an isocyanate compound as a curing agent. Preferred examples of two-component curing polyurethanes include those using a polyol such as polyester polyol, polyether polyol, or acrylic polyol as a base component and an aromatic or aliphatic polyisocyanate as a curing agent. Furthermore, as the polyol compound, polyester polyols having hydroxyl groups on the side chains in addition to terminal hydroxyl groups in the repeating units are preferably used. Examples of curing agents include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). Further examples include polyfunctional isocyanate modified products obtained from one or more of these diisocyanates. Furthermore, a polymer (e.g., a trimer) can also be used as the polyisocyanate compound. Examples of such polymers include adducts, biurets, and nurates. The aliphatic isocyanate compound refers to an isocyanate having an aliphatic group but no aromatic ring, the alicyclic isocyanate compound refers to an isocyanate having an alicyclic hydrocarbon group, and the aromatic isocyanate compound refers to an isocyanate having an aromatic ring. The surface coating layer 6 is formed from polyurethane, which provides the exterior material for an electricity storage device with excellent electrolyte resistance.

[0219] The surface coating layer 6 may contain additives such as the aforementioned lubricants, antiblocking agents, matting agents, flame retardants, antioxidants, tackifiers, and antistatic agents, at least on the surface and / or inside of the surface coating layer 6, as needed, depending on the functionality to be imparted to the surface of the surface coating layer 6. Examples of additives include fine particles with an average particle size of approximately 0.5 nm to 5 μm. The average particle size of the additive is the median size measured with a laser diffraction / scattering particle size distribution analyzer.

[0220] The additive may be either inorganic or organic. The shape of the additive is not particularly limited, and examples thereof include spherical, fibrous, plate-like, amorphous, and scaly shapes.

[0221] Specific examples of additives include talc, silica, graphite, kaolin, montmorillonite, mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, high-melting-point nylon, acrylate resin, crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper, and nickel. The additives may be used alone or in combination of two or more. Among these additives, silica, barium sulfate, and titanium oxide are preferred from the viewpoints of dispersion stability, cost, and the like. The additives may also be subjected to various surface treatments, such as insulation treatment and high-dispersibility treatment.

[0222] The method for forming the surface coating layer 6 is not particularly limited, and examples thereof include a method of applying a resin to form the surface coating layer 6. When an additive is blended into the surface coating layer 6, a resin mixed with the additive may be applied.

[0223] The thickness of the surface coating layer 6 is not particularly limited as long as the surface coating layer 6 exhibits the above-mentioned functions, and may be, for example, about 0.5 to 10 μm, and preferably about 1 to 5 μm.

[0224] 3. Manufacturing method for exterior materials for power storage devices The method for manufacturing the exterior packaging material for an electricity storage device is not particularly limited, as long as a laminate is obtained in which the layers of the exterior packaging material for an electricity storage device of the present disclosure are laminated, and examples include a method comprising a step of laminating at least a base material layer 1, a barrier layer 3, and an inner layer (adhesive layer 5 and heat-sealable resin layer 4) in this order.

[0225] That is, the manufacturing method of the electrical storage device exterior material according to the first embodiment includes a step of laminating at least a base material layer, a barrier layer, and an inner layer (an adhesive layer and a heat-sealable resin layer) in this order to obtain a laminate, and when dynamic viscoelasticity measurement is performed on the inner layer, the elongation at 80°C is 8.0% or less.

[0226] Furthermore, a manufacturing method of an exterior packaging material for an electricity storage device according to a second embodiment includes a step of laminating at least a base material layer, a barrier layer, an adhesive layer, and a heat-sealable resin layer in this order to obtain a laminate, the adhesive layer containing a polypropylene-based resin and polyethylene, a sea-island structure is observed in a cross-sectional image obtained using a scanning electron microscope of a cross section of the adhesive layer in a direction parallel to the TD and in the thickness direction, the cross-sectional image being a cross-sectional image obtained within a range from the surface of the adhesive layer on the barrier layer side to a portion that is 25% of the thickness when the thickness of the adhesive layer is taken as 100%, and in the cross-sectional image, the area of the island portions relative to the total number of island portions in the sea-island structure is 0.25 μm 2 In this method, the proportion of the total number of island portions less than 100% is 40% or more.

[0227] Further, a manufacturing method of an exterior packaging material for an electricity storage device according to a third embodiment includes a step of laminating at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order to obtain a laminate, the heat-sealable resin layer containing polypropylene and polyethylene, a sea-island structure is observed in a cross-sectional image obtained using a scanning electron microscope of a cross section of the heat-sealable resin layer in a direction parallel to TD and in a thickness direction y, and in the cross-sectional image, an area of the island portions relative to the total number of island portions of the sea-island structure is 0.02 μm 2 The total number of islands below The method for producing an exterior material for an electricity storage device is characterized in that the proportion of the antioxidant and the radical scavenger is 80.0% or more, and at least one of the layers located on the inner side of the barrier layer contains at least one of an antioxidant and a radical scavenger.

[0228] An example of a method for manufacturing an exterior material for an electricity storage device according to the present disclosure is as follows: First, a laminate (hereinafter, sometimes referred to as "laminate A") is formed in which a base layer 1, an adhesive layer 2, and a barrier layer 3 are laminated in this order. Specifically, laminate A can be formed by a dry lamination method in which an adhesive used to form adhesive layer 2 is applied to base layer 1 or to barrier layer 3, the surface of which has been chemically treated as necessary, by a coating method such as gravure coating or roll coating, and then dried, followed by laminating the barrier layer 3 or base layer 1 and curing the adhesive layer 2.

[0229] Next, the inner layer (adhesive layer 5 and heat-sealable resin layer 4) is laminated on the barrier layer 3 of the laminate A. For example, (1) a method of laminating the adhesive layer 5 and the heat-sealable resin layer 4 by extruding them onto the barrier layer 3 of the laminate A (co-extrusion lamination method, tandem lamination method), (2) a method of separately forming a laminate in which the adhesive layer 5 and the heat-sealable resin layer 4 are laminated, and laminating this on the barrier layer 3 of the laminate A by a thermal lamination method, or a method of forming a laminate in which the adhesive layer 5 is laminated on the barrier layer 3 of the laminate A, and laminating this on the heat-sealable resin layer 4 by a thermal lamination method, or (3) a laminate (4) a method in which an adhesive for forming the adhesive layer 5 is solution-coated onto the barrier layer 3 of the laminate A, followed by drying or baking, and then laminating the heat-sealable resin layer 4, which has been previously formed into a sheet, on the adhesive layer 5, and the like.

[0230] As described above, in the electrical storage device packaging material according to the first embodiment of the present disclosure, a suitable example for setting the elongation at 80°C of the inner layer in a tensile dynamic viscoelasticity measurement to 8.0% or less is to increase the crystallinity of the adhesive layer and the heat-sealable resin layer. For example, when manufacturing an electrical storage device packaging material, the adhesive layer and the heat-sealable resin layer are formed by melt extrusion molding, cooled, and then post-heated to a temperature above the melting point of the adhesive layer and the heat-sealable resin layer, followed by cooling. Furthermore, the cooling rate after post-heating is preferably 60°C or less, more preferably 50°C or less, and even more preferably 45°C or less within 3 seconds from the start of cooling, and the initial cooling conditions are controlled to be very slow, thereby promoting crystal growth in the adhesive layer and the heat-sealable resin layer. For example, by forming the adhesive layer 5 and the heat-sealable resin layer 4 using such a method, the crystallinity of the adhesive layer and the heat-sealable resin layer is increased, improving hermeticity in high-temperature environments. As mentioned above, methods of increasing crystallinity can also be adopted such as setting the elongation at 110°C in the tensile dynamic viscoelasticity measurement to 15.0% or less, and setting the temperature at 10% elongation to 85°C or higher.

[0231] When the surface coating layer 6 is provided, the surface coating layer 6 is laminated on the surface of the base material layer 1 opposite to the barrier layer 3. The surface coating layer 6 can be formed, for example, by applying the above-mentioned resin for forming the surface coating layer 6 to the surface of the base material layer 1. The order of the step of laminating the barrier layer 3 on the surface of the base material layer 1 and the step of laminating the surface coating layer 6 on the surface of the base material layer 1 is not particularly limited. For example, after the surface coating layer 6 is formed on the surface of the base material layer 1, the barrier layer 3 may be formed on the surface of the base material layer 1 opposite to the surface coating layer 6.

[0232] As described above, a laminate is formed which includes the optional surface coating layer 6, the base material layer 1, the optional adhesive layer 2, the barrier layer 3, the adhesive layer 5, and the heat-sealable resin layer 4 in this order. In order to strengthen the adhesion of the optional adhesive layer 2 and the adhesive layer 5, the laminate may be further subjected to a heat treatment.

[0233] In the packaging material for an electricity storage device, each layer constituting the laminate may be subjected to a surface activation treatment such as corona treatment, blast treatment, oxidation treatment, ozone treatment, etc., as needed to improve processability. For example, by subjecting the surface of the base layer 1 opposite to the barrier layer 3 to corona treatment, the printability of ink on the surface of the base layer 1 can be improved.

[0234] 4. Applications of exterior materials for energy storage devices The exterior packaging material for an electricity storage device according to the present disclosure is used in a package for hermetically housing an electricity storage device element such as a positive electrode, a negative electrode, an electrolyte, etc. That is, an electricity storage device can be formed by housing an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte in a package formed from the exterior packaging material for an electricity storage device according to the present disclosure.

[0235] Specifically, an electricity storage device using the electricity storage device packaging material is provided by covering an electricity storage device element having at least a positive electrode, a negative electrode, and an electrolyte with the electricity storage device packaging material of the present disclosure in a state in which metal terminals connected to each of the positive electrode and the negative electrode protrude outward, so that a flange portion (a region where the heat-sealable resin layers contact each other) can be formed around the periphery of the electricity storage device element, and heat-sealing the heat-sealable resin layers of the flange portion to form a hermetic seal. Note that when an electricity storage device element is housed in a package formed from the electricity storage device packaging material of the present disclosure, the package is formed so that the heat-sealable resin portion of the electricity storage device packaging material of the present disclosure faces inside (the surface in contact with the electricity storage device element). A package may be formed by overlapping two electrical storage device exterior packaging materials with the heat-sealable resin layers facing each other and heat-sealing the peripheral portions of the overlapped electrical storage device exterior packaging materials. Alternatively, as shown in the example of FIG. 6, one electrical storage device exterior packaging material may be folded back and overlapped, and the peripheral portions may be heat-sealed to form a package. When folding back and overlapping, as shown in the example of FIG. 6, the sides other than the folded side may be heat-sealed to form a package with a three-sided seal, or the material may be folded back to form a flange and sealed on all four sides. Furthermore, a recess for accommodating an electrical storage device element may be formed in the electrical storage device exterior packaging material by deep drawing or bulging molding. As shown in the example of FIG. 6, a recess may be provided in one electrical storage device exterior packaging material and no recess may be provided in the other electrical storage device exterior packaging material, or a recess may be provided in the other electrical storage device exterior packaging material.

[0236] The exterior material for an electricity storage device according to the present disclosure can be suitably used in electricity storage devices such as batteries (including condensers, capacitors, etc.). The exterior material for an electricity storage device according to the present disclosure may be used in either primary or secondary batteries, but is preferably used in secondary batteries. The type of secondary battery to which the exterior material for an electricity storage device according to the present disclosure is applied is not particularly limited, and examples include lithium ion batteries, lithium ion polymer batteries, all-solid-state batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, condensers, and capacitors. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are suitable applications for the exterior material for an electricity storage device according to the present disclosure. [Example]

[0237] The present disclosure will be described in detail below with reference to examples and comparative examples, but the present disclosure is not limited to the examples.

[0238] The following Examples 1A to 4A and Comparative Examples 1A to 2A are experimental results relating to the first embodiment of the present disclosure. The following Examples 1B to 10B and Comparative Example 1A are experimental results relating to the second embodiment of the present disclosure. The following Examples 1C to 10C and Comparative Examples 1C to 2C are experimental results relating to the third embodiment of the present disclosure.

[0239] <Manufacturing of exterior materials for energy storage devices> Example 1A A polyethylene terephthalate (PET) film (12 μm thick) and an oriented nylon (ONy) film (15 μm thick) were prepared as the substrate layer. A two-component urethane adhesive (a polyol compound and an aromatic isocyanate compound) was applied (3 μm) to the PET film to adhere it to the ONy film. Aluminum foil (JIS H4160:1994 A8021H-O (40 μm thick)) was prepared as the barrier layer. A two-component urethane adhesive (a polyol compound and an aromatic isocyanate compound) was then applied to one side of the aluminum foil to form an adhesive layer (3 μm thick) on the barrier layer. The adhesive layer on the barrier layer and the substrate layer (ONy film side) were then laminated by dry lamination, followed by aging treatment to produce a substrate layer / adhesive layer / barrier layer laminate. Both sides of the aluminum foil were chemically treated. The chemical conversion treatment of aluminum foil is carried out using a treatment solution consisting of phenolic resin, chromium fluoride compound, and phosphoric acid, with a coating amount of chromium of 10 mg / m 2 (dry mass) was applied to both sides of an aluminum foil by roll coating, and baked.

[0240] Next, maleic anhydride-modified polypropylene as an adhesive layer (40 μm thick) and random polypropylene as a heat-sealable resin layer (40 μm thick) were laminated on the barrier layer of each of the laminates obtained above, thereby obtaining an exterior material for an electricity storage device in which the base layer (30 μm thick including the adhesive) / adhesive layer (3 μm) / barrier layer (40 μm) / inner layer (adhesive layer (40 μm) / heat-sealable resin layer (40 μm)) was laminated in this order.

[0241] When laminating the adhesive layer and the heat-sealable resin layer on the barrier layer, the resins constituting the adhesive layer and the heat-sealable resin layer were co-extruded onto the barrier layer in a molten state, cooled to about several tens of degrees Celsius, and then post-heated again to a temperature (a hundred and several tens of degrees Celsius) above the melting points of the adhesive layer and the heat-sealable resin layer, and cooled. The cooling rate after post-heating was set to 42°C for 3 seconds from the start of cooling, and the initial cooling conditions were controlled to be very slow, promoting crystal growth in the adhesive layer and the heat-sealable resin layer.

[0242] Example 2A An exterior material for a power storage device was obtained in the same manner as in Example 1A, except that resins having a lower melt mass flow rate (MFR) than the resin used in Example 1A were used as the resins constituting the adhesive layer and the heat-sealable resin layer.

[0243] Example 3A A polyethylene terephthalate (PET) film (12 μm thick) and an oriented nylon (ONy) film (25 μm thick) were prepared as the substrate layer. A two-component urethane adhesive (a polyol compound and an aromatic isocyanate compound) was applied (3 μm) to the PET film to adhere it to the ONy film. Aluminum foil (JIS H4160:1994 A8021H-O (60 μm thick)) was prepared as the barrier layer. A two-component urethane adhesive (a polyol compound and an aromatic isocyanate compound) was then applied to one side of the aluminum foil to form an adhesive layer (3 μm thick) on the barrier layer. The adhesive layer on the barrier layer and the substrate layer (ONy film side) were then laminated by dry lamination, followed by aging treatment to produce a substrate layer / adhesive layer / barrier layer laminate. Both sides of the aluminum foil were chemically treated. The chemical conversion treatment of aluminum foil is carried out using a treatment solution consisting of phenolic resin, chromium fluoride compound, and phosphoric acid, with a coating amount of chromium of 10 mg / m 2 (dry mass) was applied to both sides of an aluminum foil by roll coating, and baked.

[0244] Next, maleic anhydride-modified polypropylene as an adhesive layer (40 μm thick) and random polypropylene as a heat-sealable resin layer (40 μm thick) were laminated on top of the barrier layer of each laminate obtained above, thereby obtaining an exterior packaging material for an electricity storage device in which the base layer (40 μm thick including the adhesive) / adhesive layer (3 μm) / barrier layer (60 μm) / inner layer (adhesive layer (40 μm) / heat-sealable resin layer (40 μm)) was laminated in this order.

[0245] When laminating the adhesive layer and the heat-sealable resin layer on the barrier layer, the resins constituting the adhesive layer and the heat-sealable resin layer were co-extruded onto the barrier layer in a molten state, cooled to about several tens of degrees Celsius, and then post-heated again to a temperature (a hundred and several tens of degrees Celsius) above the melting points of the adhesive layer and the heat-sealable resin layer, and cooled. The cooling rate after post-heating was set to 42°C for 3 seconds from the start of cooling, and the initial cooling conditions were controlled to be very slow, promoting crystal growth in the adhesive layer and the heat-sealable resin layer.

[0246] Example 4A An exterior packaging material for an electricity storage device was obtained in the same manner as in Example 1A, except that a resin with a smaller melt mass flow rate (MFR) than the resin used in Example 1A was used as the resin constituting the adhesive layer and the heat-sealable resin layer, and further, a propylene resin with a melt mass flow rate (MFR) between that of the adhesive layer and the heat-sealable resin layer was used, and a propylene resin layer (second heat-sealable resin layer) was laminated between the adhesive layer (30 μm) and the heat-sealable resin layer (20 μm) as the inner layer. The interior packaging material was obtained in the same manner as in Example 1A, in which the substrate layer (thickness 30 μm including the adhesive) / adhesive layer (3 μm) / barrier layer (40 μm) / inner layer (adhesive layer (30 μm) / propylene resin layer (30 μm second heat-sealable resin layer) / heat-sealable resin layer (20 μm)) was laminated in that order.

[0247] Comparative Example 1A An exterior material for an electricity storage device was obtained in the same manner as in Example 1A, except that the post-heating and subsequent cooling steps were not performed when laminating the adhesive layer and the heat-fusible resin layer on the barrier layer.

[0248] Comparative example 2A An exterior material for a power storage device was obtained in the same manner as in Example 1A, except that when laminating the adhesive layer and the heat-sealable resin layer on the barrier layer, the temperature decrease over 3 seconds from the start of cooling after post-heating was set to 90°C / 3 seconds, which is generally considered to be a slow cooling condition.

[0249] <Dynamic Viscoelasticity (DMA) Measurement> For each of the electrical storage device exterior materials obtained in the Examples and Comparative Examples, samples were prepared from the inner layer and subjected to dynamic viscoelasticity measurements. Specifically, each electrical storage device exterior material was immersed in a 10% hydrochloric acid solution for 24 hours to dissolve the barrier layer and obtain the inner layer (a two-layer structure consisting of an adhesive layer and a thermally fused resin layer). The inner layer was then washed with water, dried, and cut into a 5 mm wide x 10 mm long sample. Each of the obtained samples was then subjected to dynamic viscoelasticity measurements under the following measurement conditions using a dynamic viscoelasticity measuring device (product name: Rheogel-E4000) manufactured by UBM Corporation. The elongation percentages (%) at a temperature of 80°C and at a temperature of 110°C are shown in Table 1A. The temperature at 10% elongation is also shown in Table 1A in a graph showing the relationship between elongation and temperature obtained by the dynamic viscoelasticity measurements. For reference, a schematic diagram of a graph showing the relationship between elongation and temperature obtained by tensile dynamic viscoelasticity measurements is shown in FIG. 7. Point I in FIG. 7 is the point where the elongation rate reaches 10%.

[0250] (Measurement conditions) Sample width 5mm Starting temperature 30℃ End temperature 160℃ Heating rate: 2°C / min Static load 50g Length between test holders (distance between chucks): 10 mm Chuck tension Software used for measurement: RheoStation (ver. 7) Step temperature 1℃ Waveform: Sine wave, 10Hz Distortion 10μm, distortion control (automatic adjustment) Measuring tool: tension The load was controlled at a constant level up to an elongation rate of 10%, and once the elongation rate reached 10%, the load control was stopped and the specimen was subsequently elongated by 20 μm every 1° C.

[0251] <Creep test (evaluation of sealing performance in high temperature environments)> In accordance with the provisions of JIS K7127:1999, creep tests were conducted on each of the electrical storage device packaging materials in an 80°C environment as follows. Test specimens were prepared by cutting the electrical storage device packaging materials into strips with a width of 15 mm in the TD direction. Specifically, as shown in Figure 4, each electrical storage device packaging material was first cut into a 60 mm (TD direction) x 200 mm (MD direction) size (Figure 4a). Next, the electrical storage device packaging material was folded in half in the MD direction at fold line P (the middle in the MD direction) so that the heat-sealable resin layers faced each other (Figure 4b). The heat-sealable resin layers were heat-sealed approximately 10 mm inward from fold line P under the following conditions: a seal width of 7 mm, a temperature of 190°C, a surface pressure of 0.6 MPa, and a duration of 3 seconds (Figure 4c). In Figure 4c, the shaded area S indicates the heat-sealed area (sealed area S). Next, the test pieces 13 were cut in the MD direction (cut at the two-dot chain line in Figure 4d) so that the width in the TD direction was 15 mm (Figure 4f). Next, using a Tester Sangyo BE-501, the upper part of each test piece 13 was fixed in an 80°C environment as shown in the schematic diagram in Figure 5, and a 2 kg weight W was hung from the bottom, and the time until the seal part S was broken was measured. The results are shown in Table 1A.

[0252] For reference, cross-sectional images (SEM images) in the thickness direction of the electrical storage device packaging materials of Example 1A and Comparative Example 1A after the creep test are shown in Figure 8 (Example 1A) and Figure 9 (Comparative Example 1A), respectively. From the image in Figure 9, it can be seen that the adhesive layer of Comparative Example 1A has undergone cohesive failure after the creep test. It is believed that the adhesive layer of Comparative Example 1A has undergone cohesive failure due to insufficient crystal growth.

[0253] [Table 1A]

[0254] As shown in Table 1A, when the inner layers of the packaging materials for electricity storage devices of Examples 1A to 4A were subjected to dynamic viscoelasticity measurement, they had elongations of 8.0% or less at 80° C. In a creep test at 80° C., the packaging materials for electricity storage devices of Examples 1A to 4A had a very long time until the seals between the heat-fusible resin layers were destroyed, and they were evaluated as having excellent sealing properties in high-temperature environments.

[0255] In addition, for the packaging material for an electricity storage device of Comparative Example 2A, cooling was also started at a cooling rate of 90°C / 3 seconds, which can generally be considered to be slow cooling conditions. For this reason, it is thought that crystal growth in the adhesive layer and the heat-sealable resin layer also progressed in Comparative Example 2A, and the time until the seal part was destroyed in the creep test at 80°C was relatively long at 43 hours, and although not as long as in Examples 1A-4A, the sealability was improved compared to Comparative Example 1A.

[0256] <Manufacturing of exterior materials for energy storage devices> Examples 1B, 2B and Comparative Example 1B A polyethylene terephthalate (PET) film (12 μm thick) and an oriented nylon (ONy) film (15 μm thick) were prepared. The PET film and the ONy film were bonded together with a two-component urethane adhesive (a polyol compound and an aromatic isocyanate compound) to form a substrate layer. An aluminum alloy foil (JIS H4160:1994 A8021H-O (40 μm thick)) was prepared as a barrier layer. Next, the aluminum alloy foil and the substrate layer (ONy film side) were laminated by dry lamination using a two-component urethane adhesive (a polyol compound and an aromatic isocyanate compound, a thickness of 3 μm after curing), followed by aging treatment to produce a substrate layer / adhesive layer / barrier layer laminate. Both sides of the aluminum alloy foil were subjected to a chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was performed using a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid, with a chromium coating amount of 10 mg / m. 2 (dry mass) by applying the coating solution to both sides of the aluminum alloy foil by roll coating, and baking the coating solution.

[0257] Next, on the barrier layer of each laminate obtained above, pellets of maleic anhydride-modified polypropylene resin (a composition of maleic anhydride-modified polypropylene and polyethylene) as an adhesive layer (thickness 40 μm) and pellets of random polypropylene resin (a composition of random polypropylene and polyethylene) as a heat-sealable resin layer (thickness 40 μm) were molded into a film under the melt extrusion conditions described below (specifically, the pellets were melted and kneaded in a twin-screw extruder, and then extruded from a T-die to form a film). This resulted in an adhesive layer / heat-sealable resin layer being laminated on the barrier layer, and an exterior packaging material for an electricity storage device (total thickness 153 μm) in which the base layer (thickness 30 μm including the adhesive) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (40 μm) / heat-sealable resin layer (40 μm) were laminated in this order.

[0258] In Examples 1B and 2B and Comparative Example 1B, the materials constituting each layer were all the same, and the content of polyethylene in the adhesive layer was about 25% by mass.

[0259] Example 3B An outer casing material for a power storage device was obtained in the same manner as in Example 1B, except that resins having a melt mass flow rate (MFR) lower than that of the resin used in Example 1B were used as the resins constituting the adhesive layer and the heat-sealable resin layer.

[0260] Example 4B An outer casing material for a power storage device was obtained in the same manner as in Example 1B, except that the resins constituting the adhesive layer and the heat-sealable resin layer each had a melt mass flow rate (MFR) lower than that of the resin used in Example 1B, and the thickness of the adhesive layer was 30 μm and the thickness of the heat-sealable resin layer was 50 μm.

[0261] Example 5B An outer casing material for a power storage device was obtained in the same manner as in Example 1B, except that a stretched nylon (ONy) film with a thickness of 25 μm was used as the base layer and an aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 60 μm)) was used as the barrier layer.

[0262] Example 6B An outer casing material for an electricity storage device was obtained in the same manner as in Example 5B, except that melt extrusion conditions B described below were used as the melt extrusion conditions for the resin when forming the adhesive layer.

[0263] Example 7B An exterior packaging material for an electricity storage device was obtained in the same manner as in Example 4B, except that the heat-sealable resin layer had a two-layer structure, and the antioxidant and radical scavenger described below were used for the adhesive layer and the heat-sealable resin layer, the same resin as that for the adhesive layer in Example 4B was used as the resin for the adhesive layer, a resin with a lower elastic modulus than that of the heat-sealable resin layer in Example 4B was used as the resin for the heat-sealable resin layer in contact with the adhesive layer, and the same resin as that for the heat-sealable resin layer in Example 4B was used as the resin for the innermost heat-sealable resin layer.

[0264] Example 8B An exterior material for a power storage device was obtained in the same manner as in Example 7B, except that the antioxidant and radical scavenger described below were used for the adhesive layer and the heat-sealable resin layer, and the melt extrusion conditions for the resin when forming the adhesive layer were the melt extrusion conditions B described below.

[0265] Example 9B An outer casing material for a power storage device was obtained in the same manner as in Example 1B, except that the antioxidant and radical scavenger described below were used for the adhesive layer and the heat-fusible resin layer.

[0266] Example 10B An outer casing material for an electricity storage device was obtained in the same manner as in Example 9B, except that melt extrusion conditions B described below were used as the melt extrusion conditions for the resin when forming the adhesive layer.

[0267] (Melt extrusion conditions) The melt extrusion conditions for the resin when forming the adhesive layer by melt extrusion are as follows: The melt extrusion conditions employed in the examples and comparative examples are shown in Table 1B. Melt extrusion condition A: The temperature during melt kneading of the resin is low (about 200 to 240°C), and the time until discharge from the T-die (residence time of the molten resin) is shorter than under general conditions. Melt extrusion condition B: The temperature during melt kneading of the resin is low (about 240 to 260°C), and the time until extrusion from the T-die (residence time of the molten resin) is about the same as under general conditions. Melt extrusion condition C: The temperature during melt kneading of the resin is high (about 260 to 280°C), and the time until extrusion from the T-die (residence time of the molten resin) is about the same as under general conditions. Melt extrusion condition D: The temperature during melt kneading of the resin is set to a high temperature (approximately 260 to 280°C), and the time until extrusion from the T-die (residence time of the molten resin) is set to be shorter than under general conditions.

[0268] <Measurement of the area and number of islands in a sea-island structure> The casing material for an electricity storage device was embedded in a thermosetting epoxy resin and cured. A cross-section parallel to the TD and in the thickness direction was prepared using a commercially available rotary microtome (LEICA EM UC6) and a glass knife. The cross-section was prepared using a room-temperature microtome. The adhesive layer of the casing material for an electricity storage device, along with the embedding resin, was stained with ruthenium tetroxide for 3 hours. Since the staining caused the resin to expand, making the sea-island structure obscured near the cross-section, the expanded portion was trimmed using the microtome. Stained sections approximately 100 nm thick were then taken from the cross-section after cutting approximately 1 μm to 2 μm using a diamond knife and observed as follows. Cross-sectional images of the stained sections were obtained using a field-emission scanning electron microscope (Hitachi High-Technologies Corporation S-4800). Note that the cross-sectional images were obtained within a range of 25% of the thickness from the surface of the barrier layer side of the adhesive layer, assuming the thickness of the adhesive layer to be 100%. The measurement conditions were: acceleration voltage: 30 kV, emission current: 10 μA, detector: transmission detector, tilt: none (0°), and observation magnification: 5000x. Next, image processing software capable of binarizing cross-sectional images (image analysis software included with the Keyence VHX-5000 electron microscope) was used to binarize the island and sea portions of the sea-island structure for the cross-sectional image. Specifically, measurement was started under the brightness (standard) conditions of the image analysis software, and the extraction area (measurement range) was set to a rectangular shape (7 μm long, 13 μm wide), the image size was set to standard (1600 × 1200), the tilt angle was set to 0°, the shooting mode was set to normal shooting, and the extraction target was set to "dark area." Furthermore, automatic measurement was used to correct for missing extraction areas and extra extraction areas, and the total area and total number of extracted areas (islands) were measured. At this time, the area and number of all islands present in the extraction area were measured. The acquired data was used to calculate the island area (μm 2 ) and the entire island The relationship between the ratio (%) of the number of island portions of a given area to the total number is shown in the bar graphs of Figure 14 (Example 1B), Figure 15 (Example 2B), Figure 16 (Example 3B), Figure 17 (Example 4B), and Figure 18 (Comparative Example 1B). 2The percentage of the number shown in the position is the percentage of the area of 0.10 μm, with the number of all islands being 100%. 2 The figure shows the percentage of islands with an area of less than 0.25 μm. 2 The percentage of the number shown in the position is calculated by dividing the number of all islands by the number of the surface area. Area is 0.20 μm 2 More than 0.25μm 2 The figure shows the percentage of islands with an area of less than 0.10 μm. 2 The percentage of islands with an area of less than 0.15 μm 2 The percentage of islands with an area of less than 0.25 μm 2 The percentage of islands with an area of less than 1.50 μm 2 The percentages (%) of the number of the above islands are shown in Table 1B. In each of the bar graphs in Figures 14 to 18, the area is 2 μm 2 It shows up to less than.

[0269] <Creep test (evaluation of sealing performance in high temperature environments)> In accordance with the provisions of JIS K7127:1999, creep tests were conducted on each of the electrical storage device packaging materials in an 80°C environment as follows. Test specimens were prepared by cutting the electrical storage device packaging materials into strips with a width of 15 mm in the TD direction. Specifically, as shown in Figure 4, each electrical storage device packaging material was first cut into a 60 mm (TD direction) x 200 mm (MD direction) size (Figure 4a). Next, the electrical storage device packaging material was folded in half in the MD direction at fold line P (the middle in the MD direction) so that the heat-sealable resin layers faced each other (Figure 4b). The heat-sealable resin layers were heat-sealed approximately 10 mm inward from fold line P under the following conditions: a seal width of 7 mm, a temperature of 190°C, a surface pressure of 0.6 MPa, and a duration of 3 seconds (Figure 4c). In Figure 4c, the shaded area S indicates the heat-sealed area (sealed area S). Next, the test pieces 13 were cut in the MD (at the two-dot chain line in Figure 4d) so that the width in the TD direction was 15 mm (Figure 4e). Next, using a Tester Sangyo BE-501, the upper part of each test piece 13 was fixed in an 80°C environment as shown in the schematic diagram in Figure 5, and a 2 kg weight W was hung from the bottom. The time until the seal S was broken was measured. The results are shown in Table 1B.

[0270] In Examples 7B to 10B, the types and contents of the antioxidants and radical scavengers contained in the adhesive layer and the heat-fusible resin layer are as follows:

[0271] Examples 7B to 8B: The adhesive layer and the heat-sealable resin layer contained 0.4 mass % or less in total of tris(2,4-di-t-butylphenoxy)phosphine and tetrakis(methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate)methane.

[0272] Examples 9B to 10B: The adhesive layer and the heat-sealable resin layer contain a total of 0.6 mass% or less of bis(2,4-dicumylphenyl)pentaerythritol diphosphite, tris(2,4-di-t-butylphenoxy)phosphine, tetrakis(methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate)methane, and 1'-hydroxy[2,2'-ethylidenebis[4,6-bis(1,1-dimethylpropyl)benzene]]-1-yl acrylate.

[0273] [Table 1B]

[0274] As is clear from Table 1B, the packaging materials for electricity storage devices of Examples 1B to 10B have an area of 0.25 μm with respect to the total number of islands in the sea-island structure in a cross-sectional image of the adhesive layer containing a polypropylene-based resin and polyethylene. 2 The total number of island portions smaller than this is 40% or more, and in a creep test at 80°C, the time until the seal portion is destroyed is very long, and the seal is evaluated as having excellent sealing properties in high-temperature environments.

[0275] In addition, in forming the adhesive layer, except for adopting the melt extrusion condition D, packaging materials for electricity storage devices were produced in the same manner as in Examples 1B and 2B and Comparative Example 1B. In a cross-sectional image of the adhesive layer, the area of the island portions relative to the total number of island portions in the sea-island structure was 0.25 μm 2 The proportion of the total number of island portions smaller than this was less than 40%, and in a creep test at 80°C, the time until the seal portion was destroyed was shorter than in Examples 1B to 10B.

[0276] <Manufacturing of exterior materials for energy storage devices> Examples 1C and 2C and Comparative Examples 1C and 2C A polyethylene terephthalate (PET) film (12 μm thick) and an oriented nylon (ONy) film (15 μm thick) were prepared. A two-component urethane adhesive (a polyol compound and an aromatic isocyanate compound) was applied to the PET film (3 μm thick), and the ONy film was bonded to form a substrate layer. An aluminum alloy foil (JIS H4160:1994 A8021H-O (40 μm thick)) was prepared as a barrier layer. A two-component urethane adhesive (a polyol compound and an aromatic isocyanate compound) was then applied to one side of the aluminum alloy foil to form an adhesive layer (3 μm thick) on the barrier layer. The adhesive layer on the barrier layer and the substrate layer (ONy film side) were then dry-laminated, followed by aging treatment to produce a substrate layer / adhesive layer / barrier layer laminate. Both sides of the aluminum alloy foil were chemically treated. The chemical conversion treatment of aluminum alloy foil is carried out using a treatment solution consisting of phenolic resin, chromium fluoride compound, and phosphoric acid, with a coating amount of chromium of 10 mg / m 2 (dry mass) by roll coating aluminum alloy foil The coating was applied to both sides of the substrate and baked.

[0277] Next, maleic anhydride-modified polypropylene as an adhesive layer (40 μm thick) and random polypropylene (a composition of random polypropylene and polyethylene) as a heat-sealable resin layer (40 μm thick) were melt-extruded onto the barrier layer of each laminate obtained above. The heat-sealable resin layer side was contacted with a cooling roll and cooled (under cooling conditions A or B, respectively, described below), thereby laminating the adhesive layer / heat-sealable resin layer on the barrier layer. This produced an electrical storage device packaging material (total thickness 153 μm) in which the substrate layer (30 μm thick including the adhesive) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (40 μm) / heat-sealable resin layer (40 μm) were laminated in this order. Example 2C had a lower polyethylene content in the heat-sealable resin layer than Example 1C. Comparative Example 1C had a higher polyethylene content in the heat-sealable resin layer than Example 1C. In Comparative Example 2C, the composition of the heat-fusible resin layer was the same as in Example 1C, and cooling condition B was employed.

[0278] (Cooling conditions) The conditions for cooling the heat-fusible resin layer side by contacting it with a cooling roll are as follows: The cooling conditions employed in the examples and comparative examples are shown in Table 1C. Cooling condition A: The difference between the temperature of the melt-coextruded molten resin (the molten resin that forms the heat-sealable resin layer) and the surface temperature of the cooling roll is set to 70°C or more, and the molten resin is rapidly cooled to form a heat-sealable resin layer (conditions that suppress crystal growth of polyethylene). Cooling condition B: The difference between the temperature of the melt-coextruded molten resin (the molten resin that forms the heat-sealable resin layer) and the surface temperature of the cooling roll is set to 50°C or less, and the molten resin is slowly cooled to form the heat-sealable resin layer.

[0279] <Measurement of the area and number of islands in a sea-island structure> The casing material for an energy storage device was embedded in a thermosetting epoxy resin and cured. A cross-section parallel to the TD and in the thickness direction was prepared using a commercially available rotary microtome (LEICA EM UC6) and a glass knife. The cross-section was prepared using a room-temperature microtome. The heat-sealable resin layer of the casing material for an energy storage device, along with the embedded resin, was stained with ruthenium tetroxide for 3 hours. Since the resin expanded during staining, making the sea-island structure obscured near the cross-section, the expanded portion was trimmed using a microtome. After cutting approximately 1 to 2 μm, stained sections approximately 100 nm thick were extracted using a diamond knife and observed as follows. Cross-sectional images of the stained sections were obtained using a field-emission scanning electron microscope (Hitachi High-Technologies Corporation S-4800). The cross-sectional image was taken within a range of 12.5% of the thickness of the thermally adhesive resin layer from the surface opposite the barrier layer, assuming the total thickness of the layers located inside the barrier layer to be 100%. The measurement conditions were an acceleration voltage of 30 kV, an emission current of 10 μA, a transmission detector, no tilt (0°), and a magnification of 5000x. Next, image processing software capable of binarizing cross-sectional images (image analysis software included with the Keyence VHX-5000 electron microscope) was used to binarize the island and sea portions of the sea-island structure. Specifically, measurement was started under the brightness (standard) setting of the image analysis software. The extraction area (measurement range) was set to a rectangular shape (7 μm long, 13 μm wide), the image size was set to standard (1600 × 1200), the tilt angle was set to 0°, the imaging mode was set to normal imaging, and the extraction target was set to the "dark area." Furthermore, automatic measurement was used to correct for missing extraction areas and excess extraction areas, and the total area and total number of extracted areas (islands) were measured. At this time, the area and number of all islands present in the extracted area were measured. Using the acquired data, the ratio of the total area of all islands to the area of the measurement range of the cross-sectional image (total area of islands / area of measurement range of the cross-sectional image) and the area of all islands were measured to be 0.01 μm or less, respectively. 2 The ratio of the total number of islands below (0.01 μm 2 (Total number of islands below / Total number of all islands), 0.02 μm 2 The ratio of the total number of islands below (0.02 μm2 (total number of islands below / total number of all islands), 0.03 μm 2 The ratio of the total number of islands below (0.03 μm 2 (total number of islands below / total number of all islands), 0.30 μm 2 The ratio of the total number of islands above (0.30 μm 2 (Total number of islands above / Total number of all islands), 0.15 μm 2 The ratio of the total number of islands above (0.15 μm 2 The total number of the above islands / total number of all islands was calculated. The results are shown in Table 1C.

[0280] (antioxidant) In the examples and comparative examples, the types and contents of antioxidants contained in the adhesive layer and the heat-fusible resin layer are as follows:

[0281] Example 1C: The adhesive layer and the heat-sealable resin layer contained tris(2,4-di-t-butylphenoxy)phosphine and tetrakis(methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate)methane in a total amount of 0.4 mass % or less. Example 2C: The adhesive layer and the heat-sealable resin layer contained 0.4 mass % of tris(2,4-di-t-butylphenoxy)phosphine.

[0282] Comparative Example 1C: The adhesive layer and the heat-sealable resin layer contained 0.4 mass % or less in total of tris(2,4-di-t-butylphenoxy)phosphine and tetrakis(methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate)methane. Comparative Example 2C: The adhesive layer and the heat-sealable resin layer contained 0.4 mass % or less in total of tris(2,4-di-t-butylphenoxy)phosphine and tetrakis(methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate)methane.

[0283] <Whitening due to molding> Each electrical storage device packaging material was cut into a rectangle with a length (MD: Machine Direction) of 90 mm and a width (TD) of 150 mm to prepare a test sample. The MD of the electrical storage device packaging material corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the electrical storage device packaging material corresponds to the TD of the aluminum alloy foil. This test sample was placed in a 25°C environment in a rectangular molding die (female die, the surface of which had a maximum height roughness (nominal value of Rz) of 3.2 μm as specified in Table 2 of the surface roughness standard for comparison in JIS B 0659-1:2002, Annex 1 (Reference), corner R2.0 mm, ridge R1.0 mm) with a diameter of 31.6 mm (MD) x 54.5 mm (TD) and a corresponding molding die (male die, the surface of the ridgeline had a maximum height roughness (nominal value of Rz) of 1.6 μm as specified in Table 2 of the surface roughness standard for comparison in JIS B 0659-1:2002, Annex 1 (Reference), and the surface other than the ridgeline had a maximum height roughness (nominal value of Rz) of 1.6 μm as specified in Table 2 of the surface roughness standard for comparison in JIS B 0659-1:2002, Annex 1 (Reference). The maximum height roughness (nominal Rz value) of the comparative surface roughness standard specimen, as specified in Table 2, was 3.2 μm. Using a corner radius of 2.0 mm and a ridge radius of 1.0 mm, cold forming (single-stage drawing) was performed with a pressing pressure (surface pressure) of 0.1 MPa to achieve a forming depth of 6.0 mm. The test sample was placed on a female mold with the heat-sealable resin layer facing the male mold. The clearance between the male and female molds was 0.3 mm. The heat-sealable resin layer of the test sample after molding was visually inspected for whitening. Those with no whitening were rated A, those with slight whitening were rated B, and those with clear whitening were rated C. The results are shown in Table 1C. Note that whitening mainly occurred around the sidewalls on the short sides of the molded portion.

[0284] <Insulation> The exterior material for an electricity storage device was cut into a sheet piece having a length (MD) of 160 mm and a width (TD) of 90 mm. Next, these sheet pieces were placed in a rectangular forming die (female die, the surface of which had a maximum height roughness (nominal value of Rz) of 3.2 μm as specified in Table 2 of the surface roughness standard for comparison in JIS B 0659-1:2002, Annex 1 (Reference), corner R2.0 mm, ridge R1.0 mm) with a diameter of 31.6 mm (MD) x 54.5 mm (TD) in an environment of 25°C, and a corresponding forming die (male die, the surface of the ridge line had a maximum height roughness (nominal value of Rz) of 1.6 μm as specified in Table 2 of the surface roughness standard for comparison in JIS B 0659-1:2002, Annex 1 (Reference), and the surface other than the ridge line had a maximum height roughness (nominal value of Rz) of 1.6 μm as specified in Table 2 of the surface roughness standard for comparison in JIS B 0659-1:2002, Annex 1 (Reference), The maximum height roughness (nominal Rz value) of the comparative surface roughness standard specimen, as specified in Table 2, is 3.2 μm. Using a corner radius of 2.0 mm and a ridge radius of 1.0 mm, cold molding (single-stage drawing molding) was performed at a pressing pressure (surface pressure) of 0.1 MPa to achieve a molding depth of 3.0 mm. The molded sample piece was then folded in half in the MD direction with the heat-sealable resin layers facing each other, and cut to a width of 3 mm from the molded portion to the edge on the MD side to obtain a molded product. The molded portion was positioned so that the distance between the molded portion and both end edges of the sheet piece in the TD was 25 mm and 32 mm, respectively.

[0285] Next, a polyethylene terephthalate (PET) plate measuring 3.0 mm thick, 30.0 mm long (MD), and 52.5 mm wide (TD) was prepared, along with an aluminum terminal measuring 70 μm thick, 55 mm long (MD), and 5 mm wide (TD). A 100 μm thick, 10 mm wide tab film (made of maleic anhydride-modified polypropylene) was wrapped around the center of the aluminum terminal. The aluminum terminal was attached to the MD end of the PET plate using paper tape, and the PET plate was inserted into the molded section of the molded body described above. At this time, the aluminum terminal protruded from the molded section, with the tab film positioned between the heat-sealable resin layers of the molded body. In this state, the edge of the molded body where the aluminum terminal protruded was heat-sealed to a width of 3 mm, with a surface pressure of 4.0 MPa, a sealing temperature of 170°C, and a sealing time of 3.0 seconds. Next, one edge perpendicular to the heat-sealed edge was heat-sealed under conditions of a width of 3 mm, a surface pressure of 1.0 MPa, a sealing temperature of 170 ° C, and a sealing time of 3.0 seconds to form a bag-shaped molded body. Next, the bag-shaped molded body was stored in a dry room for 1 day, and an electrolyte solution (obtained by mixing a solution of ethylene carbonate: diethyl carbonate: dimethyl carbonate in a volume ratio of 1:1:1 with lithium hexafluorophosphate at 1 mol / L) was poured into the remaining open edge (opening), and the opening was heat-sealed under conditions of a width of 3 mm, a surface pressure of 1.0 MPa, a sealing temperature of 170 ° C, and a sealing time of 3.0 seconds to seal the electrolyte solution within the molded body. Finally, the molded body was stored in a 60 ° C environment for 6 hours with the heat-sealed edge facing up. Next, between the last heat-sealed edge and the molded portion, the heat-sealable resin layers were heat-sealed together along the molded portion under the conditions of a width of 3 mm, a surface pressure of 1.0 MPa, a sealing temperature of 170°C, and a sealing time of 3.0 seconds, thereby obtaining a test sample in which the electrolyte was sealed in the molded portion.

[0286] Next, the insulation between the barrier layer of the obtained test samples and the aluminum terminal was evaluated using a tester (Hioki E.E. Insulation Resistance Tester 3154). First, 10 test samples were prepared. Next, one terminal of the tester was connected to the aluminum terminal of the test sample, and the other terminal was connected with an alligator clip so that it was in contact with the barrier layer of the exterior material for an electricity storage device. Next, a voltage of 25 V was applied between the testers, and samples with a resistance value of 200 MΩ or more after 10 seconds were judged as passing (OK), and samples with a resistance value of less than 200 MΩ after 10 seconds were judged as failing (NG). The number of test samples that failed (NG) out of the 10 test samples is shown in Table 1C.

[0287] [Table 1C]

[0288] As is clear from Table 1C, in the packaging materials for electricity storage devices of Examples 1C and 2C, in the cross-sectional image of the heat-sealable resin layer containing polypropylene and polyethylene, the area of the islands relative to the total number of islands in the sea-island structure is 0.02 μm 2 The ratio of the total number of the following island portions is 80.0% or more, and whitening due to molding and deterioration of insulation properties are effectively suppressed.

[0289] As described above, the first embodiment of the present disclosure provides the invention in the following aspects. Item 1A. It is composed of a laminate having at least a base layer, a barrier layer, and an inner layer in this order, the inner layer includes an adhesive layer and a heat-sealable resin layer from the barrier layer side, The outer casing material for an electricity storage device, wherein when the inner layer is subjected to dynamic viscoelasticity measurement under tension, the elongation rate at 80°C is 8.0% or less. Item 2A. The packaging material for an electricity storage device according to Item 1A, wherein in a graph showing the relationship between elongation and temperature obtained by the dynamic viscoelasticity measurement, the temperature at an elongation of 10% is 85°C or higher. Item 3A. The exterior packaging material for an electricity storage device according to Item 1A or 2A, wherein the inner layer has an elongation rate of 15.0% or less at 110°C in the dynamic viscoelasticity measurement. Item 4A: The packaging material for an electricity storage device according to any one of Items A1 to 3A, wherein the ratio of the thickness of the heat-sealable resin layer to the thickness of the adhesive layer is 0.3 or more and 1.5 or less. Item 5A: The packaging material for an electricity storage device according to any one of Items 1A to 4A, wherein the adhesive layer is made of a thermoplastic resin. Item 6A. The method includes a step of laminating at least a substrate layer, a barrier layer, and an inner layer in this order to obtain a laminate, the inner layer includes an adhesive layer and a heat-sealable resin layer from the barrier layer side, A method for producing an exterior material for an electricity storage device, wherein, when dynamic viscoelasticity measurement is performed on the inner layer by tension, the elongation rate at 80°C is 8.0% or less. Item 7A. An electricity storage device, in which an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the exterior packaging material for an electricity storage device according to any one of Items 1A to 5A.

[0290] The second embodiment of the present disclosure provides the following aspects of the invention. Item 1B. The laminate is composed of at least a base layer, a barrier layer, an adhesive layer, and a heat-sealable resin layer in this order, the adhesive layer contains a polypropylene-based resin and polyethylene, a sea-island structure is observed in a cross-sectional image of the adhesive layer taken in a direction parallel to the TD and in the thickness direction, the cross-sectional image being obtained using a scanning electron microscope; the cross-sectional image is a cross-sectional image obtained within a range from the surface of the adhesive layer on the barrier layer side to a portion of the adhesive layer that is 25% of the thickness of the adhesive layer, where the thickness of the adhesive layer is 100%, In the cross-sectional image, the area of the island portion is 0.25 μm with respect to the total number of island portions of the sea-island structure. 2 The proportion of the total number of island portions smaller than this is 40% or more. Item 2B. In the cross-sectional image of the adhesive layer, the area of the island portion relative to the total number of the island portions of the sea-island structure is 1.50 μm 2 Item 2. The packaging material for an electricity storage device according to Item 1, wherein the proportion of the total number of the island portions is 10% or less. Item 3B. In the cross-sectional image of the adhesive layer, the area of the island portion relative to the total number of the island portions of the sea-island structure is 0.15 μm 2 Item 1B or 2B. The packaging material for an electricity storage device according to Item 1B or 2B, wherein the proportion of the total number of island portions less than 100% is 20% or more. Item 4B. In the cross-sectional image of the adhesive layer, the area of the island portion relative to the total number of the island portions of the sea-island structure is 0.10 μm 2 Item 1B or 2B. The packaging material for an electricity storage device according to Item 1B or 2B, wherein the proportion of the total number of island portions less than 10% is 10% or more. Item 5B: The packaging material for an electricity storage device according to any one of Items 1B to 4B, wherein the polypropylene resin of the adhesive layer is acid-modified polypropylene. Item 6B: The packaging material for an electricity storage device according to any one of Items 1B to 5B, wherein the adhesive layer has a thickness of 5 μm or more. Item 7B: The packaging material for an electricity storage device according to any one of Items 1B to 6B, wherein the resin forming the heat-sealable resin layer contains a polyolefin skeleton. Item 8B: The packaging material for an electricity storage device according to any one of Items 1B to 7B, wherein at least one of the layers located on an inner side of the barrier layer contains at least one selected from the group consisting of an antioxidant and a radical scavenger. Item 9B: The packaging material for an electricity storage device according to Item 8B, wherein the antioxidant is at least one selected from the group consisting of phosphorus-based antioxidants and phenol-based antioxidants. Item 10B: The packaging material for an electricity storage device according to any one of Items 1B to 9B, wherein the radical scavenger is an alkyl radical scavenger. Item 11B. The method includes a step of laminating at least a base layer, a barrier layer, an adhesive layer, and a heat-sealable resin layer in this order from the outside to the inside to obtain a laminate, the adhesive layer contains a polypropylene-based resin and polyethylene, a sea-island structure is observed in a cross-sectional image of the adhesive layer taken in a direction parallel to the TD and in the thickness direction, the cross-sectional image being obtained using a scanning electron microscope; the cross-sectional image is a cross-sectional image obtained within a range from the surface of the adhesive layer on the barrier layer side to a portion of the adhesive layer that is 25% of the thickness of the adhesive layer, where the thickness of the adhesive layer is 100%, In the cross-sectional image, the area of the island portion is 0.25 μm with respect to the total number of island portions of the sea-island structure. 2 a ratio of the total number of island portions smaller than 1 / 2 mm to 40% or more. Item 12B. An electricity storage device, in which an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the exterior packaging material for an electricity storage device according to any one of Items 1B to 10B.

[0291] Furthermore, the third embodiment of the present disclosure provides the invention having the following aspects. Item 1C. It is composed of a laminate having at least a base layer, a barrier layer, and a heat-sealable resin layer in this order from the outside to the inside, the heat-sealable resin layer contains polypropylene and polyethylene, a sea-island structure is observed in a cross-sectional image of the heat-fusion resin layer taken in a direction parallel to the TD and in the thickness direction, the cross-sectional image being obtained using a scanning electron microscope; the cross-sectional image is a cross-sectional image obtained within a range of a thickness of 12.5% from the surface of the thermal adhesive resin layer opposite to the barrier layer side, where the total thickness of layers located inside the barrier layer is taken as 100%, and In the cross-sectional image, the area of the island portion is 0.02 μm with respect to the total number of island portions of the sea-island structure. 2 The total number of the following islands is 80.0% or more: The packaging material for an electricity storage device comprises at least one of an antioxidant and a radical scavenger in at least one layer located inside the barrier layer. Item 2C: The packaging material for an electricity storage device according to Item 1C, wherein the antioxidant is at least one selected from the group consisting of phosphorus-based antioxidants and phenol-based antioxidants. Item 3C: The packaging material for an electricity storage device according to Item 1C or 2C, wherein the radical scavenger is an alkyl radical scavenger. Item 4C: The packaging material for an electricity storage device according to any one of Items 1C to 3C, wherein in the cross-sectional image of the heat-fusible resin layer, a ratio of the total area of the island portions of the sea-island structure to the area of the measurement range of the cross-sectional image is 12.0% or less. Item 5C. In the cross-sectional image of the heat-sealable resin layer, the area of the island portions relative to the total number of island portions of the sea-island structure is 0.03 μm 2 The packaging material for an electricity storage device according to any one of items 1C to 4C, wherein the proportion of the total number of the following island portions is 90.0% or more. Item 6C. In the cross-sectional image of the heat-sealable resin layer, the area of the island portions relative to the total number of island portions of the sea-island structure is 0.01 μm 2 The packaging material for an electricity storage device according to any one of items 1C to 5C, wherein the proportion of the total number of the following island portions is 50.0% or more. Item 7C. In the cross-sectional image of the heat-sealable resin layer, the area of the island portions relative to the total number of island portions of the sea-island structure is 0.30 μm 2 The packaging material for an electricity storage device according to any one of items 1C to 6C, wherein the proportion of the total number of the island portions is 1.0% or less. Item 8C: The packaging material for an electricity storage device according to any one of Items 1C to 7C, further comprising an adhesive layer between the barrier layer and the heat-sealable resin layer. Item 9C: The packaging material for a power storage device according to Item 8C, wherein the adhesive layer has a thickness of 5 μm or more. Item 10C. The method includes a step of laminating at least a base layer, a barrier layer, and a heat-sealable resin layer in this order from the outside to the inside to obtain a laminate, the heat-sealable resin layer contains polypropylene and polyethylene, a sea-island structure is observed in a cross-sectional image of the heat-fusion resin layer taken in a direction parallel to the TD and in the thickness direction, the cross-sectional image being obtained using a scanning electron microscope; the cross-sectional image is a cross-sectional image obtained within a range of a thickness of 12.5% from the surface of the thermal adhesive resin layer opposite to the barrier layer side, where the total thickness of layers located inside the barrier layer is taken as 100%, and In the cross-sectional image, the area of the island portion is 0.02 μm with respect to the total number of island portions of the sea-island structure. 2 The total number of the following islands is 80.0% or more: A method for producing an exterior material for an electricity storage device, wherein at least one of an antioxidant and a radical scavenger is contained in at least one layer located inside the barrier layer. Item 11C: An electricity storage device, in which an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the exterior packaging material for an electricity storage device according to any one of Items 1C to 9C. [Explanation of symbols]

[0292] 1 Base material layer 2 Adhesive layer 3 Barrier layer 4 Heat-fusible resin layer 5 Adhesive layer 6 Surface coating layer 10. Exterior materials for energy storage devices

Claims

1. The laminate is composed of at least a base layer, a barrier layer, an adhesive layer, and a heat-sealable resin layer in this order, the base layer is formed of two or more layers of resin film, the adhesive layer contains a polypropylene-based resin and polyethylene, a sea-island structure is observed in a cross-sectional image of the adhesive layer taken in a direction parallel to the TD and in the thickness direction, the cross-sectional image being obtained using a scanning electron microscope; the cross-sectional image is a cross-sectional image obtained within a range from a surface of the adhesive layer on the barrier layer side to a portion of the adhesive layer that is 25% of the thickness of the adhesive layer, where the thickness of the adhesive layer is 100%, In the cross-sectional image, the area of the island portion is 0.25 μm with respect to the total number of island portions of the sea-island structure. 2 a proportion of the total number of island portions smaller than 40% by weight is 40% or more.

2. The laminate is composed of at least a base layer, a barrier layer, an adhesive layer, and a heat-sealable resin layer in this order, the base layer is formed of a single-layer polyester film, the adhesive layer contains a polypropylene-based resin and polyethylene, a sea-island structure is observed in a cross-sectional image of the adhesive layer taken in a direction parallel to the TD and in the thickness direction, the cross-sectional image being obtained using a scanning electron microscope; the cross-sectional image is a cross-sectional image obtained within a range from a surface of the adhesive layer on the barrier layer side to a portion of the adhesive layer that is 25% of the thickness of the adhesive layer, where the thickness of the adhesive layer is 100%, In the cross-sectional image, the area of the island portion is 0.25 μm with respect to the total number of island portions of the sea-island structure. 2 a proportion of the total number of island portions smaller than 40% by weight is 40% or more.

3. The laminate is composed of at least a base layer, a barrier layer, an adhesive layer, and a heat-sealable resin layer in this order, the thickness of the barrier layer is 50 μm or more and 80 μm or less; the adhesive layer contains a polypropylene-based resin and polyethylene, a sea-island structure is observed in a cross-sectional image of the adhesive layer taken in a direction parallel to the TD and in the thickness direction, the cross-sectional image being obtained using a scanning electron microscope; the cross-sectional image is a cross-sectional image obtained within a range from a surface of the adhesive layer on the barrier layer side to a portion of the adhesive layer that is 25% of the thickness of the adhesive layer, where the thickness of the adhesive layer is 100%, In the cross-sectional image, the area of the island portion is 0.25 μm with respect to the total number of island portions of the sea-island structure. 2 a proportion of the total number of island portions smaller than 40% by weight is 40% or more.

4. The laminate is composed of a base material layer, a barrier layer, and a heat-sealable resin layer, arranged in this order from the outside to the inside, the base layer is formed of two or more layers of resin film, the heat-sealable resin layer contains polypropylene and polyethylene, a sea-island structure is observed in a cross-sectional image of the heat-fusible resin layer taken in a direction parallel to the TD and in the thickness direction, the cross-sectional image being obtained using a scanning electron microscope; the cross-sectional image is a cross-sectional image obtained within a range of a thickness of 12.5% from the surface of the thermal adhesive resin layer opposite to the barrier layer side, where the total thickness of layers located inside the barrier layer is taken as 100%, and In the cross-sectional image, the area of the island portion is 0.02 μm with respect to the total number of island portions of the sea-island structure. 2 The ratio of the total number of the following island portions is 80.0% or more, The packaging material for an electricity storage device comprises at least one of an antioxidant and a radical scavenger in at least one layer located inside the barrier layer.

5. The laminate is composed of a base material layer, a barrier layer, and a heat-sealable resin layer, arranged in this order from the outside to the inside, the base layer is formed of a single-layer polyester film, the heat-sealable resin layer contains polypropylene and polyethylene, a sea-island structure is observed in a cross-sectional image of the heat-fusible resin layer taken in a direction parallel to the TD and in the thickness direction, the cross-sectional image being obtained using a scanning electron microscope; the cross-sectional image is a cross-sectional image obtained within a range of a thickness of 12.5% from the surface of the thermal adhesive resin layer opposite to the barrier layer side, where the total thickness of layers located inside the barrier layer is taken as 100%, and In the cross-sectional image, the area of the island portion is 0.02 μm with respect to the total number of island portions of the sea-island structure. 2 The ratio of the total number of the following island portions is 80.0% or more, The packaging material for an electricity storage device comprises at least one of an antioxidant and a radical scavenger in at least one layer located inside the barrier layer.

6. The laminate is composed of a base material layer, a barrier layer, and a heat-sealable resin layer, arranged in this order from the outside to the inside, the thickness of the barrier layer is 50 μm or more and 80 μm or less; the heat-sealable resin layer contains polypropylene and polyethylene, a sea-island structure is observed in a cross-sectional image of the heat-fusible resin layer taken in a direction parallel to the TD and in the thickness direction, the cross-sectional image being obtained using a scanning electron microscope; the cross-sectional image is a cross-sectional image obtained within a range of a thickness of 12.5% from the surface of the thermal adhesive resin layer opposite to the barrier layer side, where the total thickness of layers located inside the barrier layer is taken as 100%, and In the cross-sectional image, the area of the island portion is 0.02 μm with respect to the total number of island portions of the sea-island structure. 2 The ratio of the total number of the following island portions is 80.0% or more, The packaging material for an electricity storage device comprises at least one of an antioxidant and a radical scavenger in at least one layer located inside the barrier layer.

7. The laminate is composed of at least a substrate layer, a barrier layer, and an inner layer in this order, the base layer is formed of two or more layers of resin film, the inner layer includes an adhesive layer and a heat-sealable resin layer from the barrier layer side, the heat-sealable resin layer contains 55% by mass or more of polypropylene, The outer casing material for an electricity storage device, wherein when the inner layer is subjected to dynamic viscoelasticity measurement under tension, the elongation rate at 80°C is 8.0% or less.

8. The laminate is composed of at least a substrate layer, a barrier layer, and an inner layer in this order, the base layer is formed of a single-layer polyester film, the inner layer includes an adhesive layer and a heat-sealable resin layer from the barrier layer side, the heat-sealable resin layer contains 55% by mass or more of polypropylene, The outer casing material for an electricity storage device, wherein when the inner layer is subjected to dynamic viscoelasticity measurement under tension, the elongation rate at 80°C is 8.0% or less.

9. The laminate is composed of at least a substrate layer, a barrier layer, and an inner layer in this order, the thickness of the barrier layer is 50 μm or more and 80 μm or less; the inner layer includes an adhesive layer and a heat-sealable resin layer from the barrier layer side, the heat-sealable resin layer contains 55% by mass or more of polypropylene, The outer casing material for an electricity storage device, wherein when the inner layer is subjected to dynamic viscoelasticity measurement under tension, the elongation rate at 80°C is 8.0% or less.

10. The packaging material for an electricity storage device according to claim 1 , wherein the thickness of each resin film constituting each layer of the base material layer is 2 μm or more and 25 μm or less.

11. In the cross-sectional image of the adhesive layer, the area of the island portions relative to the total number of island portions of the sea-island structure is 1.50 μm 2 The packaging material for an electricity storage device according to any one of claims 1 to 3, wherein a proportion of the total number of the island portions is 10% or less.

12. In the cross-sectional image of the adhesive layer, the area of the island portion relative to the total number of island portions of the sea-island structure is 0.15 μm 2 The packaging material for an electricity storage device according to any one of claims 1 to 3, wherein a proportion of the total number of island portions less than 100% is 20% or more.

13. In the cross-sectional image of the adhesive layer, the area of the island portion relative to the total number of island portions of the sea-island structure is 0.10 μm 2 The packaging material for an electricity storage device according to any one of claims 1 to 3, wherein a proportion of the total number of island portions less than 10% is 10% or more.

14. 7. The packaging material for an electricity storage device according to claim 4, wherein in the cross-sectional image of the heat-fusible resin layer, a ratio of a total area of island portions of the sea-island structure to an area of a measurement range of the cross-sectional image is 12.0% or less.

15. In the cross-sectional image of the heat-fusible resin layer, the area of the island portions relative to the total number of island portions of the sea-island structure is 0.03 μm 2 The packaging material for an electricity storage device according to any one of claims 4 to 6, wherein a ratio of the total number of the following island portions is 90.0% or more:

16. In the cross-sectional image of the heat-fusible resin layer, the area of the island portion relative to the total number of island portions of the sea-island structure is 0.01 μm 2 The packaging material for an electricity storage device according to any one of claims 4 to 6, wherein a ratio of the total number of the following island portions is 50.0% or more:

17. In the cross-sectional image of the heat-fusible resin layer, the area of the island portions relative to the total number of island portions of the sea-island structure is 0.30 μm 2 The packaging material for an electricity storage device according to any one of claims 4 to 6, wherein a proportion of the total number of the island portions is 1.0% or less.

18. 10. The electrical storage device packaging material according to any one of claims 7 to 9, wherein in a graph showing the relationship between elongation and temperature obtained by the dynamic viscoelasticity measurement, the temperature at an elongation of 10% is 85°C or higher.

19. The outer casing material for an electricity storage device according to any one of claims 7 to 9, wherein the inner layer has an elongation rate of 15.0% or less at 110°C in the dynamic viscoelasticity measurement.

20. The packaging material for an electricity storage device according to any one of claims 7 to 9, wherein a ratio of a thickness of the heat-fusible resin layer to a thickness of the adhesive layer is 0.3 or more and 1.5 or less.

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