Adhesive film for metal terminals and method for manufacturing the same; metal terminal with adhesive film for metal terminals; exterior material for energy storage device; kit comprising exterior material for energy storage device and adhesive film for metal terminals; and energy storage device and method for manufacturing the same.

Abstract

Provided is a metal-terminal adhesive film interposed between a metal terminal that is electrically connected to an electrode of a power storage device element and a power-storage-device exterior material that seals the power storage device element, wherein the metal-terminal adhesive film comprises a thermochromic layer.

Description

[Technical Field]

[0001] This disclosure relates to an adhesive film for metal terminals and a method for manufacturing the same, a metal terminal with an adhesive film for metal terminals, an exterior material for an energy storage device, a kit comprising the exterior material for an energy storage device and an adhesive film for metal terminals, and an energy storage device and a method for manufacturing the same. [Background technology]

[0002] While various types of energy storage devices have been developed, casing materials for energy storage devices are essential components for sealing the device elements such as electrodes and electrolytes in all of them. Traditionally, metal casing materials for energy storage devices have been widely used. However, in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, and mobile phones, energy storage devices are required to come in a variety of shapes, and there is a demand for thinner and lighter designs. However, conventionally used metal casing materials for energy storage devices have the drawback of being unable to keep up with the diversification of shapes, and also have limitations in terms of weight reduction.

[0003] Therefore, in recent years, laminated sheets have been proposed as exterior materials for energy storage devices, in which a base layer, adhesive layer, barrier layer, and heat-sealable resin layer are sequentially laminated. These sheets are easily processed into various shapes and enable thinning and weight reduction. When using such a laminated film-like exterior material for energy storage devices, the peripheral edges of the exterior material are heat-sealed together with the heat-sealable resin layers located in the innermost layers of the exterior material facing each other, thereby sealing the energy storage device elements with the exterior material.

[0004] Metal terminals protrude from the heat-sealed portion of the casing material for energy storage devices. The energy storage device element sealed by the casing material is electrically connected to the outside by the metal terminals, which are electrically connected to the electrodes of the energy storage device element. In other words, in the heat-sealed portion of the casing material for energy storage devices, the portion where the metal terminals are present is heat-sealed with the metal terminals sandwiched between heat-fusible resin layers. Since the metal terminals and the heat-fusible resin layer are composed of dissimilar materials, adhesion tends to decrease at the interface between the metal terminals and the heat-fusible resin layer.

[0005] For this reason, an adhesive film is sometimes placed between the metal terminal and the heat-sealable resin layer to improve their adhesion. An example of such an adhesive film is the one described in Patent Document 1. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2015-79638 [Overview of the project] [Problems that the invention aims to solve]

[0007] The adhesive film placed between the metal terminal and the outer casing material for the energy storage device covers the metal terminal by heat-sealing the outer casing material while the metal terminal is sandwiched between the adhesive film. For example, during heat sealing, the adhesive film is heated to a high temperature. Also, when manufacturing the adhesive film, the resin that forms the adhesive film is melted and molded into a film, so the resin that forms the adhesive film is heated to a high temperature. Furthermore, even after the adhesive film is applied to the energy storage device, if the energy storage device is exposed to a high-temperature environment or generates heat and becomes hot, the adhesive film will also be heated to a high temperature.

[0008] Thus, the adhesive film placed between the metal terminals and the outer casing material for the energy storage device may be exposed to high-temperature environments during the manufacturing of the adhesive film, when the adhesive film is applied to the energy storage device, and even after application.

[0009] When the resin forming the adhesive film is exposed to high temperatures, the resin may degrade, potentially leading to a decrease in the properties of the adhesive film (for example, a decrease in adhesion to metal terminals).

[0010] The inventors of this disclosure have set a novel problem: determining from its appearance whether the resin forming the adhesive film has been heated to a predetermined temperature. If this problem is solved, excellent effects can be achieved, such as being able to identify adhesive films that may have deteriorated properties from their appearance.

[0011] Under these circumstances, the primary objective of this disclosure is to provide an adhesive film for metal terminals, which is interposed between a metal terminal electrically connected to the electrodes of an energy storage device element and an outer casing material for an energy storage device that seals the energy storage device element, and which allows the heating to a predetermined temperature to be determined by its appearance. Furthermore, this disclosure also aims to provide a method for manufacturing the adhesive film for metal terminals, a metal terminal with the adhesive film for metal terminals, an outer casing material for an energy storage device, a kit comprising the outer casing material for an energy storage device and the adhesive film for metal terminals, an energy storage device, and a method for manufacturing the energy storage device. [Means for solving the problem]

[0012] The inventors of this disclosure have diligently studied to solve the above-mentioned problems. As a result, they have found that by providing a heat-discoloring layer in an adhesive film for metal terminals, which is interposed between a metal terminal electrically connected to the electrode of an energy storage device element and an outer material for an energy storage device that seals the energy storage device element, it is possible to determine from the appearance that the resin contained in the adhesive film for metal terminals has been heated to a predetermined temperature. This disclosure was completed by further studies based on this finding.

[0013] That is, the present disclosure provides an invention in the following aspects. An adhesive film for a metal terminal interposed between a metal terminal electrically connected to an electrode of a power storage device element and an exterior material for a power storage device that seals the power storage device element, The adhesive film for a metal terminal includes a thermochromic layer.

Advantages of the Invention

[0014] According to the present disclosure, there is provided an adhesive film for a metal terminal interposed between a metal terminal electrically connected to an electrode of a power storage device element and an exterior material for a power storage device that seals the power storage device element, and it is possible to visually confirm from the appearance that the adhesive film has been heated to a predetermined temperature. Further, the present disclosure also aims to provide a method for manufacturing the adhesive film for a metal terminal, a metal terminal with the adhesive film for a metal terminal, an exterior material for a power storage device, a kit including the exterior material for a power storage device and the adhesive film for a metal terminal, and a power storage device and a method for manufacturing the same.

Brief Description of the Drawings

[0015] [Figure 1] A schematic plan view of the power storage device of the present disclosure. [Figure 2] A schematic cross-sectional view taken along line A-A' of FIG. 1. [Figure 3] A schematic cross-sectional view taken along line B-B' of FIG. 1. [Figure 4] A schematic cross-sectional view of the adhesive film for a metal terminal of the present disclosure. [Figure 5] A schematic cross-sectional view of the adhesive film for a metal terminal of the present disclosure. [Figure 6] A schematic cross-sectional view of the adhesive film for a metal terminal of the present disclosure. [Figure 7] A schematic cross-sectional view of the adhesive film for a metal terminal of the present disclosure. [[ID=4I]] [Figure 8]This is a schematic cross-sectional view of the exterior material for the energy storage device disclosed herein. [Modes for carrying out the invention]

[0016] The adhesive film for metal terminals of the present disclosure is an adhesive film for metal terminals interposed between a metal terminal electrically connected to an electrode of an energy storage device element and an outer material for an energy storage device that seals the energy storage device element, wherein the adhesive film for metal terminals is characterized by comprising a heat-discoloring layer.

[0017] Furthermore, the energy storage device of the present disclosure is an energy storage device comprising at least an energy storage device element having a positive electrode, a negative electrode, and an electrolyte, an outer casing material for the energy storage device that seals the energy storage device element, and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the outer casing material for the energy storage device, wherein the adhesive film for metal terminals of the present disclosure is interposed between the metal terminals and the outer casing material for the energy storage device.

[0018] The following describes in detail the adhesive film for metal terminals and its manufacturing method, as well as the energy storage device and its manufacturing method.

[0019] In this specification, numerical ranges indicated by "~" mean "greater than or equal to" and "less than or equal to" respectively. For example, the notation 2~15mm means 2mm or more and 15mm or less. In numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Alternatively, upper and lower limits, upper and lower limits, or lower and lower limits described separately may be combined to form numerical ranges. Furthermore, in numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples.

[0020] 1. Adhesive film for metal terminals The adhesive film for metal terminals of this disclosure is interposed between a metal terminal electrically connected to the electrodes of an energy storage device element and an outer casing material for an energy storage device that seals the energy storage device element. Specifically, as shown in Figures 1 to 3, for example, the adhesive film for metal terminals 1 of this disclosure is interposed between a metal terminal 2 electrically connected to the electrodes of an energy storage device element 4 and an outer casing material 3 for an energy storage device that seals the energy storage device element 4. The metal terminal 2 protrudes to the outside of the outer casing material 3 and is sandwiched between the outer casing material 3 and the heat-sealed outer casing material 3 via the adhesive film for metal terminals 1 at the peripheral edge 3a of the outer casing material 3.

[0021] In this disclosure, the preliminary bonding process of the adhesive film for metal terminals to the metal terminals is performed under conditions such as a temperature of approximately 140 to 160°C, a pressure of approximately 0.01 to 1.0 MPa, a time of approximately 3 to 15 seconds, and 3 to 6 times. The main bonding process is performed under conditions such as a temperature of approximately 160 to 240°C, a pressure of approximately 0.01 to 1.0 MPa, a time of approximately 3 to 15 seconds, and 1 to 3 times. Furthermore, when heat sealing a metal terminal with an adhesive film for metal terminals interposed in an exterior material for an energy storage device, the heating temperature is typically in the range of approximately 180 to 210°C, the pressure is typically approximately 1.0 to 2.0 MPa, the time of approximately 3 to 5 seconds, and 1 time.

[0022] The adhesive film 1 for metal terminals of this disclosure is provided to improve the adhesion between the metal terminals 2 and the exterior material 3 for the energy storage device. By improving the adhesion between the metal terminals 2 and the exterior material 3 for the energy storage device, the sealing performance of the energy storage device element 4 is improved. As described above, when heat sealing the energy storage device element 4, the metal terminals 2 electrically connected to the electrodes of the energy storage device element 4 protrude to the outside of the exterior material 3 for the energy storage device, thereby sealing the energy storage device element. At this time, since the metal terminals 2, which are made of metal, and the heat-fusible resin layer 35 (a layer made of a heat-fusible resin such as polyolefin) located in the innermost layer of the exterior material 3 for the energy storage device are made of different materials, if such an adhesive film is not used, the sealing performance of the energy storage device element tends to be low at the interface between the metal terminals 2 and the heat-fusible resin layer 35.

[0023] [Thermal discoloration layer] The adhesive film 1 for metal terminals of this disclosure comprises at least a thermochromic layer. The thermochromic layer is, for example, a resin layer formed from a resin composition containing a thermochromic material and a resin. A thermochromic material refers to a material (compound) that has the property of changing color when exposed to a certain temperature environment, and as described below, various inorganic compounds and organic compounds are known as materials having such properties.

[0024] The heat-discoloring layer may be a layer that forms at least one surface of the adhesive film 1 for metal terminals (i.e., the outermost layer, such as the first resin layer 12a and the second resin layer 12b described later), or it may be a layer that does not constitute the surface (such as the intermediate layer 11 and the adhesion promoter layer 13 described later).

[0025] To the extent that the effects of this disclosure are achieved, the adhesive film 1 for metal terminals of this disclosure may be a single layer as shown in Figure 4, or a multi-layered film as shown in Figures 5 to 7.

[0026] When the adhesive film 1 for metal terminals of this disclosure is a single layer, the adhesive film 1 for metal terminals is composed of a heat-discoloring layer, and the surface on the metal terminal side and the surface of the exterior material for the energy storage device are formed by this heat-discoloring layer. In this case, the resin forming the surface of the adhesive film 1 for metal terminals on the exterior material side for the energy storage device and the resin forming the surface on the metal terminal side are a common resin (i.e., the resin that forms the heat-discoloring layer). Note that "common" means that, for example, 80% or more by mass of the resin forming the surface on the exterior material side for the energy storage device and the resin forming the surface on the metal terminal side of these resins are the same, 90% or more by mass are the same, 95% or more by mass are the same, or 100% by mass are the same, etc.

[0027] When the adhesive film 1 for metal terminals of this disclosure is multilayered, for example as shown in Figure 5, when the adhesive film 1 for metal terminals of this disclosure has a two-layer structure, the adhesive film 1 for metal terminals is a laminate of a first resin layer 12a and a second resin layer 12b, and at least one of the first resin layer 12a and the second resin layer 12b is a heat-discoloring layer. Even when the adhesive film 1 for metal terminals of this disclosure is multilayered, the resin forming the surface on the exterior material side for the energy storage device and the resin forming the surface on the metal terminal side may be the same resin.

[0028] For example, as shown in Figure 6, if the adhesive film 1 for metal terminals of this disclosure has a three-layer structure, the adhesive film 1 for metal terminals is a laminate in which a first resin layer 12a, an intermediate layer 11, and a second resin layer 12b are laminated in this order. In this disclosure, the first resin layer 12a constitutes the surface on the metal terminal side, and the second resin layer 12b constitutes the surface on the exterior material side for the energy storage device.

[0029] In the adhesive film 1 for metal terminals of this disclosure, it is preferable that the heat-discoloring layer has heat-fusible properties to the metal (the metal constituting the metal terminal). In this case, the heat-discoloring layer can be placed on the metal terminal side of the adhesive film 1 for metal terminals and used. For example, in this disclosure, of the first resin layer 12a and the second resin layer 12b, at least the first resin layer 12a can be formed by the heat-discoloring layer.

[0030] The surface of the adhesive film 1 for metal terminals in this disclosure on the exterior material side for energy storage devices (for example, the second resin layer 12b) has thermal fusion properties to the heat-fusible resin layer described later. Preferably, the heat-discoloration layer also has thermal fusion properties to the heat-fusible resin layer described later. The heat-discoloration layer can be placed on the exterior material side for energy storage devices of the adhesive film 1 for metal terminals and used. For example, in this disclosure, of the first resin layer 12a and the second resin layer 12b, at least the second resin layer 12b can be formed by the heat-discoloration layer.

[0031] Furthermore, the heat-discoloring layer can also be used as an intermediate layer 11 located between the first resin layer 12a and the second resin layer 12b.

[0032] The thermochromic layer is a layer containing a thermochromic agent. That is, the thermochromic layer is, for example, a resin layer formed from a resin composition containing a thermochromic agent and a resin.

[0033] As a temperature-indicating material, there are no particular limitations as long as it is a material (compound) that has the property of changing color when exposed to a certain temperature environment. Various inorganic and organic compounds are known to possess such properties.

[0034] The temperature at which a temperature-indicating material changes color when heated from room temperature (25°C) is unique to each temperature-indicating material. Therefore, the temperature-indicating material should be selected according to the heating temperature that should be determined from the appearance of the adhesive film 1 for metal terminals. Examples of temperature ranges in which the temperature-indicating material used in this disclosure changes color when heated from room temperature (25°C) include, for example, between 120 and 150°C, between 200 and 240°C, and between 280 and 320°C. For example, if the adhesive film 1 for metal terminals contains polyolefin, it is preferable that the discoloration occurs between 280 and 320°C, where the polyolefin begins to deteriorate. Furthermore, when pre-heat-sealing the adhesive film 1 for metal terminals to metal terminals, and when heat-sealing the exterior material for energy storage devices via the adhesive film 1 for metal terminals, it is preferable that the discoloration occurs between 200 and 240°C from the viewpoint of confirming that the adhesive film 1 for metal terminals is heat-sealed, and it is preferable that the discoloration occurs between 280 and 320°C from the viewpoint of determining that the heat-sealing temperature was too high. Furthermore, when detecting that the energy storage device is experiencing thermal runaway and has reached a high temperature from the adhesive film 1 for metal terminals, it is preferable that the film changes color between 120 and 150°C. As mentioned above, for example, titanium nitride changes from black to white when heated to about 300°C.

[0035] For example, titanium nitride (titanium black), which is preferably used as a temperature indicator in this disclosure, is black at room temperature (25°C) and remains black even when heated to, for example, 280°C. However, when heated to 300°C, it oxidizes and changes to titanium dioxide, changing color to white. Therefore, if titanium nitride (titanium black) is used as a temperature indicator for the thermochromic layer, the adhesive film 1 for metal terminals will remain black from room temperature up to 280°C, but will change to white when heated to 300°C, allowing it to be determined from its appearance that it has been exposed to a very high temperature environment of 300°C. When the adhesive film 1 for metal terminals is exposed to a high temperature environment of 300°C, the resin deteriorates, and the properties of the adhesive film 1 for metal terminals tend to decrease. Therefore, it is possible to determine from its appearance whether the properties of the adhesive film 1 for metal terminals have deteriorated. In addition, the resin may be heated to 300°C during the manufacturing process of the adhesive film 1 for metal terminals. In such cases, by confirming that the heat-discolored layer, which should be manufactured as black, has changed to white, it becomes possible to determine from its appearance whether there is a risk of deterioration in the properties of the adhesive film 1 for metal terminals.

[0036] Specific examples of thermochromic materials include inorganic compounds such as titanium nitride (titanium black), titanium dioxide, and zinc sulfide, and organic compounds such as thermochromic liquid crystals (cholesterol derivatives and cyanobiphenyls). Furthermore, inorganic particles, for example, do not leach into the electrolyte. In addition, inorganic particles provide a sufficient coloring effect with an amount that does not significantly impede adhesion, and they do not melt with heat, thus increasing the apparent melt viscosity of the added resin. Moreover, they prevent the pressurized area from becoming thin during heat bonding (heat sealing), providing excellent sealing between the exterior material for energy storage devices and the metal terminals. The thermochromic material contained in the heat-coloring layer may be one type or two or more types. From the viewpoint of more favorably exhibiting the effects of this disclosure, titanium nitride (titanium black) is particularly preferred among these thermochromic materials.

[0037] The color of the temperature-indicating material is not particularly limited, but from the viewpoint of more favorably exhibiting the effects of this disclosure, black, gray, etc. are preferred, and black is particularly preferred. The thermochromic layer can be colored to a color corresponding to the color of the temperature-indicating material, and the color of the thermochromic layer of the adhesive film 1 for metal terminals of this disclosure can be visually confirmed from its appearance.

[0038] The thermal discoloration layer is measured using the SCI method, with a field of view of 10° and a light source of F2, and the L of the reflected light is measured. * a * b * L in color space * The value is preferably about 90 or less, more preferably about 80 or less, and even more preferably about 70 or less, and also preferably about 10 or more, more preferably about 20 or more, and even more preferably about 30 or more. Preferred ranges include 10-90, 10-80, 10-70, 20-90, 20-80, 20-70, 30-90, 30-80, and 30-70.

[0039] Furthermore, the L before and after heating the adhesive film 1 for metal terminals * The greater the difference, the easier it becomes to recognize the change in appearance due to the color of the adhesive film 1 for metal terminals before and after heating. Therefore, the L of the adhesive film 1 for metal terminals before and after heating * The difference is preferably about 10 or more, more preferably about 20 or more, and even more preferably about 30 or more, with an upper limit of usually about 90 or less, and preferred ranges include about 10 to 90, about 20 to 90, and about 30 to 90.

[0040] From the viewpoint of more favorably exhibiting the effects of this disclosure, the average particle diameter of the temperature-indicating material is preferably about 300 nm or less, more preferably about 200 nm or less, even more preferably about 100 nm or less, and also preferably about 10 nm or more, more preferably about 20 nm or more, even more preferably about 30 nm or more, and even more preferably about 50 nm or more. Preferred ranges include about 10-300 nm, about 10-200 nm, about 10-100 nm, about 20-300 nm, about 20-200 nm, about 20-100 nm, about 30-300 nm, about 30-200 nm, about 30-100 nm, about 50-300 nm, about 50-200 nm, and about 50-100 nm. The average particle diameter of the temperature-indicating material is the median diameter measured by a laser diffraction / scattering particle size distribution analyzer.

[0041] From the viewpoint of more favorably exhibiting the effects of this disclosure, the content of the thermochromic material in the thermochromic layer is preferably about 50% by mass or less, more preferably about 40% by mass or less, even more preferably about 30% by mass or less, and even more preferably about 20% by mass or less, and also preferably about 0.01% by mass or more, more preferably about 0.1% by mass or more, and preferred ranges include about 0.01 to 50% by mass, about 0.01 to 40% by mass, about 0.01 to 30% by mass, about 0.01 to 20% by mass, about 0.1 to 50% by mass, about 0.1 to 40% by mass, about 0.1 to 30% by mass, and about 0.1 to 20% by mass.

[0042] Examples of resins included in the heat-discoloring layer are polyolefin resins, polyamide resins, polyester resins, epoxy resins, acrylic resins, fluororesins, silicon resins, phenolic resins, polyetherimides, polyimides, polycarbonates, and mixtures or copolymers thereof. Among these, polyolefin resins are particularly preferred. Examples of polyolefin resins include polyolefins and acid-modified polyolefins.

[0043] From the viewpoint of more favorably exhibiting the effects of this disclosure, the heat-changeable layer preferably contains a polyolefin resin (i.e., has a polyolefin skeleton), preferably contains polyolefin, and more preferably is a layer formed of polyolefin. Among polyolefin resins, the heat-changeable layer preferably contains polyolefin or acid-modified polyolefin. Furthermore, the polyolefin is preferably polypropylene, and the acid-modified polyolefin is preferably acid-modified polypropylene.

[0044] The resin contained in the thermochromic layer may be of one type or two or more types. From the viewpoint of film-forming properties, it is preferable that the resin in the thermochromic layer is a blended polymer combining two or more resin components. When a blended polymer is used, for example, if the thermochromic layer contains acid-modified polypropylene, it is preferable that acid-modified polypropylene be the main component (50% by mass or more) and 50% by mass or less be other resins (preferably polyethylene from the viewpoint of improving flexibility). Similarly, if the thermochromic layer contains polypropylene, it is preferable that polypropylene be the main component (50% by mass or more) and 50% by mass or less be other resins (preferably polyethylene from the viewpoint of improving flexibility). On the other hand, from the viewpoint of the electrolyte resistance of the thermochromic layer, it is preferable that the thermochromic layer containing acid-modified polypropylene contains acid-modified polypropylene alone as the resin, and it is preferable that the thermochromic layer containing polypropylene contains either acid-modified polypropylene or polypropylene alone as the resin.

[0045] Because of its excellent adhesion to metal terminals, the thermochromic layer preferably contains an acid-modified polyolefin. From the viewpoint of more favorably exhibiting the effects of this disclosure, the thermochromic layer is preferably formed of an acid-modified polyolefin containing a temperature-indicating material. That is, the thermochromic layer can be suitably constructed from an acid-modified polyolefin film containing a temperature-indicating material.

[0046] The acid-modified polyolefin is not particularly limited as long as it is an acid-modified polyolefin, but preferably it is a polyolefin graft-modified with an unsaturated carboxylic acid or its anhydride.

[0047] Examples of polyolefins that can be acid-modified include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymer of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymer of propylene and ethylene); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferred, and polypropylene is particularly preferred.

[0048] Furthermore, the polyolefin that is acid-modified may be a cyclic polyolefin. For example, a carboxylic acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a portion of the monomers constituting the cyclic polyolefin with an α,β-unsaturated carboxylic acid or its anhydride, or by block polymerization or graft polymerization of an α,β-unsaturated carboxylic acid or its anhydride to a cyclic polyolefin.

[0049] The acid-modified cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of olefins that are constituent monomers of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of cyclic monomers that are constituent monomers of the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, cyclic alkenes are preferred, and norbornene is more preferred. Styrene can also be used as a constituent monomer.

[0050] Examples of carboxylic acids or their anhydrides used in acid modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride. When the thermally discolored layer is analyzed by infrared spectroscopy, it is preferable that a peak originating from maleic anhydride is detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak at wavenumber 1760 cm⁻¹ is detected. -1 Nearby wave frequency 1780cm -1 A peak originating from maleic anhydride is detected in the vicinity. If the thermally discolored layer is composed of maleic anhydride-modified polyolefin, a peak originating from maleic anhydride will be detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak may become small and not be detected. In that case, analysis can be performed by nuclear magnetic resonance spectroscopy.

[0051] The heat-coloring layer may, in addition to the temperature-indicating material and resin, optionally contain known additives such as fillers, to the extent that they do not impair the effects of the present disclosure.

[0052] For example, the heat-discoloring layer may contain a filler as needed. The inclusion of a filler in the heat-discoloring layer allows the filler to function as a spacer, effectively suppressing short circuits between the metal terminal 2 and the barrier layer 33 of the energy storage device's exterior material 3. The particle size of the filler can range from approximately 0.1 to 35 μm, preferably 5.0 to 30 μm, and more preferably 10 to 25 μm. The filler content can be approximately 5 to 30 parts by mass, more preferably 10 to 20 parts by mass, per 100 parts by mass of the resin component forming the heat-discoloring layer.

[0053] Both inorganic and organic fillers can be used. Examples of inorganic fillers include carbon (carbon, graphite), silica, aluminum oxide, barium titanate, iron oxide, silicon carbide, zirconium oxide, zirconium silicate, magnesium oxide, titanium oxide, calcium aluminate, calcium hydroxide, aluminum hydroxide, magnesium hydroxide, and calcium carbonate. Examples of organic fillers include fluororesins, phenolic resins, urea resins, epoxy resins, acrylic resins, benzoguanamine-formaldehyde condensates, melamine-formaldehyde condensates, polymethyl methacrylate crosslinked products, and polyethylene crosslinked products. From the viewpoint of shape stability, rigidity, and content resistance, aluminum oxide, silica, fluororesins, acrylic resins, and benzoguanamine-formaldehyde condensates are preferred, and among these, spherical aluminum oxide and silica are particularly preferred. Methods for mixing the filler with the resin component that forms the heat-discoloration layer include a method in which the two are melt-blended in advance using a Banbury mixer or the like to create a masterbatch and then mixing it in a predetermined ratio, or a method of directly mixing it with the resin component.

[0054] When adding a filler to the heat-coloring layer, a thermochromic agent and a pigment may be added to the heat-coloring layer. However, from the viewpoint of not hindering the heat-sealing properties of the adhesive film 1 for metal terminals, it is preferable to add the filler and pigment separately to different layers (for example, the first resin layer 12a, the second resin layer 12b, the intermediate layer 11, etc., as described later).

[0055] From the viewpoint of more favorably achieving the effects of this disclosure, the melting peak temperature of the thermal discoloration layer is preferably 110°C or higher, more preferably about 120°C or higher, and even more preferably about 130°C or higher. From a similar viewpoint, the melting peak temperature is, for example, 200°C or lower, preferably 190°C or lower, more preferably 180°C or lower, even more preferably about 175°C or lower, and even more preferably about 170°C or lower. The preferred range for the melting peak temperature is approximately 110-200°C, 110-190°C, 110-180°C, 110-175°C, 110-170°C, 120-200°C, 120-190°C, 120-180°C, 120-175°C, 120-170°C, 130-200°C, 130-190°C, 130-180°C, 130-175°C, and 130-170°C. In this disclosure, the method for measuring the melting peak temperature is as follows.

[0056] <Measurement of melting peak temperature> For each sample, the melting peak temperature is measured in accordance with the provisions of JIS K7121:2012 (Method for Measuring Transition Temperature of Plastics (Supplement 1 to JIS K7121:1987)). The measurement is performed using a differential scanning calorimeter (DSC, for example, a Q200 differential scanning calorimeter manufactured by T.A. Instruments). The sample is held at -50°C for 15 minutes, then heated from -50°C to 210°C at a heating rate of 10°C / min, and the first melting peak temperature P (°C) is measured, after which it is held at 210°C for 10 minutes. Next, it is cooled from 210°C to -50°C at a cooling rate of 10°C / min and held for 15 minutes. Furthermore, it is heated from -50°C to 210°C at a heating rate of 10°C / min and the second melting peak temperature Q (°C) is measured. The nitrogen gas flow rate is 50 ml / min. Following the above procedure, the melting peak temperature P (°C) measured in the first measurement and the melting peak temperature Q (°C) measured in the second measurement are determined. The value of the melting peak temperature P (°C) measured in the first measurement is adopted.

[0057] When the adhesive film 1 for metal terminals of this disclosure is composed of a single layer of a heat-discoloring layer, the total thickness of the adhesive film 1 for metal terminals, as described later, corresponds to the thickness of the heat-discoloring layer.

[0058] When the adhesive film 1 for metal terminals of this disclosure is composed of multiple layers, from the viewpoint of more favorably achieving the effects of this disclosure, the thickness of the heat-discoloring layer is preferably about 20 μm or more, more preferably about 30 μm or more, even more preferably about 40 μm or more, and also preferably about 200 μm or less, more preferably about 150 μm or less, and even more preferably 100 μm or less. Preferred ranges for the thickness of the heat-discoloring layer include about 20 to 200 μm, about 20 to 150 μm, about 20 to 100 μm, about 30 to 200 μm, about 30 to 150 μm, about 30 to 100 μm, about 40 to 200 μm, about 40 to 150 μm, and about 40 to 100 μm. When the adhesive film 1 for metal terminals of this disclosure contains multiple heat-discoloring layers, it is preferable that the thickness of each heat-discoloring layer is as described above.

[0059] Furthermore, when the adhesive film 1 for metal terminals of this disclosure has a thermochromic layer as the first resin layer 12a, from the viewpoint of more favorably achieving the effects of this disclosure, the thickness of the thermochromic layer is preferably about 20 μm or more, more preferably about 30 μm or more, even more preferably about 40 μm or more, and also preferably about 200 μm or less, more preferably about 150 μm or less, and even more preferably 100 μm or less. Preferred ranges for the thickness of the thermochromic layer include about 20 to 200 μm, about 20 to 150 μm, about 20 to 100 μm, about 30 to 200 μm, about 30 to 150 μm, about 30 to 100 μm, about 40 to 200 μm, about 40 to 150 μm, and about 40 to 100 μm.

[0060] Furthermore, when the adhesive film 1 for metal terminals of this disclosure has a thermochromic layer as the second resin layer 12b, from the viewpoint of more favorably achieving the effects of this disclosure, the thickness of the thermochromic layer is preferably about 20 μm or more, more preferably about 30 μm or more, even more preferably about 40 μm or more, and also preferably about 200 μm or less, more preferably about 150 μm or less, and even more preferably 100 μm or less. A preferred range for the thickness of the thermochromic layer is about 40 to 100 μm.

[0061] Furthermore, when the adhesive film 1 for metal terminals of this disclosure has a heat-discoloring layer as an intermediate layer 11, from the viewpoint of more favorably achieving the effects of this disclosure, the thickness of the heat-discoloring layer is preferably about 20 μm or more, more preferably about 30 μm or more, even more preferably about 40 μm or more, and also preferably about 200 μm or less, more preferably about 150 μm or less, and even more preferably 100 μm or less. Preferred ranges for the thickness of the heat-discoloring layer include about 20 to 200 μm, about 20 to 150 μm, about 20 to 100 μm, about 30 to 200 μm, about 30 to 150 μm, about 30 to 100 μm, about 40 to 200 μm, about 40 to 150 μm, and about 40 to 100 μm.

[0062] As described above, the adhesive film 1 for metal terminals of this disclosure can have a configuration in which at least a first resin layer 12a, an intermediate layer 11, and a second resin layer 12b are laminated in this order, as shown in Figure 6, for example. In the adhesive film 1 for metal terminals of this disclosure, the first resin layer 12a is arranged on the metal terminal 2 side, and the second resin layer 12b is arranged on the exterior material 3 side for the energy storage device. In this configuration, the first resin layer 12a and the second resin layer 12b are located on the surfaces of both sides, respectively.

[0063] The second resin layer 12b is a layer made of resin. The second resin layer 12b may be formed by a thermochromic layer, or it may be formed by a resin layer B different from the thermochromic layer (i.e., resin layer B is a resin layer that does not contain a temperature-indicating material).

[0064] Furthermore, the intermediate layer 11 may be formed from a heat-discoloring layer, or it may be formed from a resin layer B different from the heat-discoloring layer.

[0065] [Resin layer B] Resin layer B is a different resin layer from the heat-discoloring layer (that is, resin layer B is a non-heat-discoloring layer that does not change color at the temperature at which the heat-discoloring layer changes color, and can be considered a resin layer that does not contain a temperature-indicating material, for example).

[0066] Examples of resins constituting resin layer B include polyolefin resins, polyamide resins, polyester resins, epoxy resins, acrylic resins, fluororesins, silicon resins, phenolic resins, polyetherimides, polyimides, polycarbonates, and mixtures or copolymers thereof. Among these, polyolefin resins are particularly preferred. Examples of polyolefin resins include polyolefins and acid-modified polyolefins.

[0067] The resin contained in resin layer B may be of one type or two or more types. From the viewpoint of film-forming properties, it is preferable that the resin in resin layer B is a blended polymer combining two or more resin components. When a blended polymer is used, for example, if resin layer B contains acid-modified polypropylene, it is preferable that acid-modified polypropylene be the main component (50% by mass or more) and 50% by mass or less be other resins (preferably polyethylene from the viewpoint of improving flexibility). Also, if resin layer B contains polypropylene, it is preferable that polypropylene be the main component (50% by mass or more) and 50% by mass or less be other resins (preferably polyethylene from the viewpoint of improving flexibility). On the other hand, from the viewpoint of the electrolyte resistance of resin layer B, it is preferable that resin layer B containing acid-modified polypropylene contains acid-modified polypropylene alone as the resin, and it is preferable that resin layer B containing polypropylene contains either acid-modified polypropylene or polypropylene alone as the resin.

[0068] The melting peak temperature of resin layer B is preferably 110°C or higher, more preferably about 120°C or higher, and even more preferably about 130°C or higher. The melting peak temperature is, for example, 200°C or lower, preferably 190°C or lower, more preferably 180°C or lower, even more preferably about 175°C or lower, and even more preferably about 170°C or lower. A preferred range for the melting peak temperature is approximately 110-200°C, 110-190°C, 110-180°C, 110-175°C, 110-170°C, 120-200°C, 120-190°C, 120-180°C, 120-175°C, 120-170°C, 130-200°C, 130-190°C, 130-180°C, 130-175°C, and 130-170°C.

[0069] Furthermore, when the adhesive film 1 for metal terminals of this disclosure has a resin layer B as the first resin layer 12a, from the viewpoint of more favorably achieving the effects of this disclosure, the thickness of the resin layer B is preferably about 20 μm or more, more preferably about 30 μm or more, even more preferably about 40 μm or more, and also preferably about 200 μm or less, more preferably about 150 μm or less, and even more preferably 100 μm or less. Preferred ranges for the thickness of the resin layer B include about 20 to 200 μm, about 20 to 150 μm, about 20 to 100 μm, about 30 to 200 μm, about 30 to 150 μm, about 30 to 100 μm, about 40 to 200 μm, about 40 to 150 μm, and about 40 to 100 μm.

[0070] Furthermore, when the adhesive film 1 for metal terminals of this disclosure has a resin layer B as the second resin layer 12b, from the viewpoint of more favorably achieving the effects of this disclosure, the thickness of the resin layer B is preferably about 20 μm or more, more preferably about 30 μm or more, even more preferably about 40 μm or more, and also preferably about 200 μm or less, more preferably about 150 μm or less, and even more preferably 100 μm or less. Preferred ranges for the thickness of the resin layer B include about 20 to 200 μm, about 20 to 150 μm, about 20 to 100 μm, about 30 to 200 μm, about 30 to 150 μm, about 30 to 100 μm, about 40 to 200 μm, about 40 to 150 μm, and about 40 to 100 μm.

[0071] Furthermore, when the adhesive film 1 for metal terminals of this disclosure has a resin layer B as an intermediate layer 11, from the viewpoint of more favorably achieving the effects of this disclosure, the thickness of the resin layer B is preferably about 20 μm or more, more preferably about 30 μm or more, even more preferably about 40 μm or more, and also preferably about 200 μm or less, more preferably about 150 μm or less, and even more preferably 100 μm or less. Preferred ranges for the thickness of the resin layer B include about 20 to 200 μm, about 20 to 150 μm, about 20 to 100 μm, about 30 to 200 μm, about 30 to 150 μm, about 30 to 100 μm, about 40 to 200 μm, about 40 to 150 μm, and about 40 to 100 μm.

[0072] Resin layer B may contain known additives (pigments, fillers, etc.), similar to the heat-discoloring layer. For example, resin layer B may contain a pigment. Various inorganic pigments can be used as pigments. Specific examples of pigments include carbon (graphite), as exemplified by the fillers mentioned above. Carbon (graphite) is a material commonly used inside energy storage devices and does not leach into the electrolyte. Furthermore, a sufficient coloring effect can be obtained with an amount that does not significantly impede adhesion, and it does not melt with heat, thus increasing the apparent melt viscosity of the added resin. In addition, it prevents the pressurized area from becoming thin during heat bonding (heat sealing), providing excellent sealing between the energy storage device exterior material and the metal terminals. Also, for example, resin layer B may contain a filler. The type and amount of filler are the same as those for the heat-discoloring layer.

[0073] The resin layer B may be colored or colorless and transparent.

[0074] From the viewpoint of more favorably achieving the effects of this disclosure, the total thickness of the adhesive film 1 for metal terminals is, for example, about 50 μm or more, preferably about 100 μm or more, and more preferably about 150 μm or more. Furthermore, the total thickness of the adhesive film 1 for metal terminals of this disclosure is preferably about 400 μm or less, more preferably about 350 μm or less, and even more preferably about 300 μm or less. Preferred ranges for the total thickness of the adhesive film 1 for metal terminals of this disclosure include about 50 to 400 μm, about 50 to 350 μm, about 50 to 300 μm, about 100 to 400 μm, about 100 to 350 μm, about 100 to 300 μm, about 150 to 400 μm, about 150 to 350 μm, and about 150 to 300 μm.

[0075] The adhesive film 1 for metal terminals of this disclosure preferably has fine irregularities on at least one surface of its outermost layer. This further improves the adhesion between the heat-sealable resin layer 35 or the metal terminal 2 of the exterior material 3 for the energy storage device. Methods for forming fine irregularities on the surface of the outermost layer of the adhesive film 1 for metal terminals include adding additives such as fine particles to the outermost layer, and forming the film by contacting a cooling roll having irregularities on its surface. Preferably, the ten-point average roughness of the surface of the outermost layer is about 0.1 μm or more, more preferably about 0.2 μm or more, and also preferably about 35 μm or less, more preferably about 10 μm or less, with preferred ranges being about 0.1 to 35 μm, about 0.1 to 10 μm, about 0.2 to 35 μm, and about 0.2 to 10 μm. The ten-point average roughness was measured using a Keyence VK-9710 laser microscope, with a 50x objective lens and no cutoff, in accordance with the provisions of JIS B0601:1994.

[0076] The adhesive film 1 for metal terminals of this disclosure is preferably formed of a polyolefin resin. For example, the resin component contained in the adhesive film 1 for metal terminals of this disclosure is preferably acid-modified polyolefin only, or acid-modified polyolefin and polyolefin only. Preferred acid-modified polyolefin and polyolefin are as described in the sections on the heat-discoloration layer and resin layer B.

[0077] The adhesive film 1 for metal terminals of this disclosure is preferably composed of a laminate comprising a first resin layer 12a, an intermediate layer 11, and a second resin layer 12b in that order. Hereinafter, preferred embodiments of the adhesive film 1 for metal terminals of this disclosure will be described in detail, using as an example the case in which the adhesive film 1 for metal terminals of this disclosure is composed of a laminate comprising at least a first resin layer 12a, an intermediate layer 11, and a second resin layer 12b in that order.

[0078] When the adhesive film 1 for metal terminals of this disclosure is placed between the metal terminal 2 of the energy storage device 10 and the exterior material 3 for the energy storage device, the surface of the metal terminal 2 and the heat-fusible resin layer 35 (a layer formed of a heat-fusible resin such as polyolefin) of the exterior material 3 for the energy storage device are bonded together via the adhesive film 1. The first resin layer 12a of the adhesive film 1 for metal terminals is positioned on the metal terminal 2 side, and the second resin layer 12b is positioned on the exterior material 3 side, with the first resin layer 12a in close contact with the metal terminal 2 and the second resin layer 12b in close contact with the heat-fusible resin layer 35 of the exterior material 3 for the energy storage device.

[0079] [First resin layer 12a and second resin layer 12b] As shown in Figure 6, the adhesive film 1 for metal terminals according to a preferred embodiment of the present disclosure comprises a first resin layer 12a on one side of the intermediate layer 11 and a second resin layer 12b on the other side. The first resin layer 12a is positioned on the metal terminal 2 side. The second resin layer 12b is positioned on the exterior material 3 side for the energy storage device. In the adhesive film 1 for metal terminals according to the present disclosure, the first resin layer 12a and the second resin layer 12b are located on the surfaces of both sides, respectively.

[0080] In this disclosure, at least one of the first resin layer 12a, the intermediate layer 11, and the second resin layer 12b is formed of the aforementioned heat-discoloring layer.

[0081] As described above, the first resin layer 12a and the second resin layer 12b preferably contain a polyolefin resin (i.e., have a polyolefin skeleton), preferably contain polyolefin, and more preferably be layers formed of polyolefin. The first resin layer 12a preferably contains polyolefin or acid-modified polyolefin among polyolefin resins, more preferably contain acid-modified polyolefin, and more preferably be a layer formed of an acid-modified polyolefin film. The polyolefin resin is preferably a polypropylene resin. The second resin layer 12b preferably contains polyolefin or acid-modified polyolefin among polyolefin resins, more preferably contain polyolefin, and more preferably be a layer formed of a polyolefin film. The polyolefin resin is preferably a polypropylene resin. The polyolefin is preferably polypropylene, and the acid-modified polyolefin is preferably polypropylene.

[0082] The melting peak temperature of the first resin layer 12a is preferably 110°C or higher, more preferably about 120°C or higher, and even more preferably about 130°C or higher. The melting peak temperature is, for example, 200°C or lower, preferably 190°C or lower, more preferably 180°C or lower, even more preferably about 175°C or lower, and even more preferably about 170°C or lower. Preferred ranges for the melting peak temperature include approximately 110-200°C, 110-190°C, 110-180°C, 110-175°C, 110-170°C, 120-200°C, 120-190°C, 120-180°C, 120-175°C, 120-170°C, 130-200°C, 130-190°C, 130-180°C, 130-175°C, and 130-170°C.

[0083] The melting peak temperature of the second resin layer 12b is preferably 110°C or higher, more preferably about 120°C or higher, and even more preferably about 130°C or higher. The melting peak temperature is, for example, 200°C or lower, preferably 190°C or lower, more preferably 180°C or lower, even more preferably about 175°C or lower, and even more preferably about 170°C or lower. Preferred ranges for the melting peak temperature include approximately 110-200°C, 110-190°C, 110-180°C, 110-175°C, 110-170°C, 120-200°C, 120-190°C, 120-180°C, 120-175°C, 120-170°C, 130-200°C, 130-190°C, 130-180°C, 130-175°C, and 130-170°C.

[0084] From the viewpoint of more favorably achieving the effects of this disclosure, the thickness of the first resin layer 12a is preferably about 20 μm or more, more preferably about 30 μm or more, even more preferably about 40 μm or more, and also preferably about 200 μm or less, more preferably about 150 μm or less, and even more preferably 100 μm or less. A preferred range for the thickness of the first resin layer 12a is about 40 to 100 μm.

[0085] Furthermore, from the viewpoint of more favorably achieving the effects of this disclosure, the thickness of the second resin layer 12b is preferably about 20 μm or more, more preferably about 30 μm or more, even more preferably about 40 μm or more, and also preferably about 200 μm or less, more preferably about 150 μm or less, and even more preferably 100 μm or less. Preferred ranges for the thickness of the second resin layer 12b include about 20 to 200 μm, about 20 to 150 μm, about 20 to 100 μm, about 30 to 200 μm, about 30 to 150 μm, about 30 to 100 μm, about 40 to 200 μm, about 40 to 150 μm, and about 40 to 100 μm.

[0086] [Middle layer 11] In the adhesive film 1 for metal terminals, the intermediate layer 11 is a layer that functions as a support for the adhesive film 1 for metal terminals.

[0087] The intermediate layer 11 may be formed from the aforementioned heat-discoloring layer, or from the aforementioned resin layer B.

[0088] The material forming the intermediate layer 11 is not particularly limited. Examples of materials for forming the intermediate layer 11 include polyolefin resins, polyamide resins, polyester resins, epoxy resins, acrylic resins, fluororesins, silicon resins, phenolic resins, polyetherimides, polyimides, polycarbonates, and mixtures or copolymers thereof, among which polyolefin resins are particularly preferred. In other words, the material forming the intermediate layer 11 is preferably a resin containing a polyolefin skeleton, such as polyolefin or acid-modified polyolefin. The presence of a polyolefin skeleton in the resin constituting the intermediate layer 11 can be analyzed, for example, by infrared spectroscopy or gas chromatography-mass spectrometry.

[0089] As described above, the intermediate layer 11 preferably contains a polyolefin resin, preferably contains a polyolefin, and more preferably is a layer formed of a polyolefin. The layer formed of a polyolefin may be a stretched polyolefin film or an unstretched polyolefin film, but it is preferably an unstretched polyolefin film. Specifically, examples of polyolefins include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymer of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymer of propylene and ethylene); and ethylene-butene-propylene terpolymer. Among these polyolefins, polyethylene and polypropylene are preferred, and polypropylene is more preferred. Furthermore, because of its excellent electrolyte resistance, the intermediate layer 11 preferably contains homopolypropylene, more preferably is formed of homopolypropylene, and even more preferably is an unstretched homopolypropylene film.

[0090] Specifically, 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 (where I represents isophthalic acid and T represents terephthalic acid), which contain constituent units derived from terephthalic acid and / or isophthalic acid; aromatic polyamides such as polymetaxylylene adipamide (MXD6); alicyclic polyamides such as polyaminomethylcyclohexyl adipamide (PACM6); polyamides copolymerized with lactam components or isocyanate components such as 4,4'-diphenylmethane-diisocyanate; polyesteramide copolymers and polyether esteramide copolymers, which are copolymers of copolymerized polyamides with polyester or polyalkylene ether glycol; and copolymers thereof. These polyamides may be used individually or in combination of two or more.

[0091] Specifically, examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, copolymer polyesters with ethylene terephthalate as the main repeating unit, and copolymer polyesters with butylene terephthalate as the main repeating unit. Furthermore, specific examples of copolymer polyesters with ethylene terephthalate as the main repeating unit include copolymer polyesters polymerized with ethylene isophthalate using ethylene terephthalate as the main repeating unit (hereinafter abbreviated as polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / isophthalate), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl dicarboxylate), and polyethylene (terephthalate / decanedicarboxylate). Furthermore, specific examples of copolymer polyesters with butylene terephthalate as the main repeating unit include copolymer polyesters polymerized with butylene isophthalate using butylene terephthalate as the main repeating unit (hereinafter abbreviated as polybutylene(terephthalate / isophthalate)), polybutylene(terephthalate / adipate), polybutylene(terephthalate / sebacate), polybutylene(terephthalate / decanedicarboxylate), and polybutylene naphthalate. These polyesters may be used individually or in combination of two or more types.

[0092] Furthermore, the intermediate layer 11 may be formed from a nonwoven fabric made of the above-mentioned resin. When the intermediate layer 11 is a nonwoven fabric, it is preferable that the intermediate layer 11 is made of the aforementioned polyolefin resin, polyamide resin, etc.

[0093] The melting peak temperature of the intermediate layer 11 is preferably 110°C or higher, more preferably about 120°C or higher, and even more preferably about 130°C or higher. From a similar viewpoint, the melting peak temperature is, for example, 300°C or lower, preferably 290°C or lower, more preferably 280°C or lower, even more preferably about 275°C or lower, and even more preferably about 270°C or lower. Preferred ranges for the melting peak temperature include approximately 110-300°C, 110-290°C, 110-280°C, 110-275°C, 110-270°C, 120-300°C, 120-290°C, 120-280°C, 120-275°C, 120-270°C, 130-300°C, 130-290°C, 130-280°C, 130-275°C, and 130-270°C.

[0094] The intermediate layer 11 may be a single layer or a multi-layered layer.

[0095] Furthermore, by incorporating a coloring agent into the intermediate layer 11, the intermediate layer 11 can be made into a layer containing a coloring agent. Light transmittance can also be adjusted by selecting a resin with low transparency. If the intermediate layer 11 is a film, a colored film or a film with low transparency can be used. If the intermediate layer 11 is a nonwoven fabric, a nonwoven fabric using fibers or binders containing a coloring agent, or a nonwoven fabric with low transparency can be used.

[0096] If the intermediate layer 11 is made of a resin film, the surface of the intermediate layer 11 may be subjected to known easy-adhesion methods such as corona discharge treatment, ozone treatment, or plasma treatment, as needed.

[0097] Furthermore, from the viewpoint of more favorably achieving the effects of this disclosure, the thickness of the intermediate layer 11 is preferably about 20 μm or more, more preferably about 30 μm or more, even more preferably about 40 μm or more, and also preferably about 200 μm or less, more preferably about 150 μm or less, and even more preferably 100 μm or less. Preferred ranges for the thickness of the intermediate layer 11 include about 20 to 200 μm, about 20 to 150 μm, about 20 to 100 μm, about 30 to 200 μm, about 30 to 150 μm, about 30 to 100 μm, about 40 to 200 μm, about 40 to 150 μm, and about 40 to 100 μm.

[0098] From a similar viewpoint, the ratio of the thickness of the intermediate layer 11 to the total thickness of the first resin layer 12a and the second resin layer 12b is preferably about 0.3 or more, more preferably about 0.4 or more, and also preferably about 1.0 or less, more preferably about 0.8 or less. Preferred ranges include about 0.3 to 1.0, about 0.3 to 0.8, about 0.4 to 1.0, and about 0.4 to 0.8.

[0099] Furthermore, when the total thickness of the adhesive film 1 for metal terminals is set to 100%, the ratio of the total thickness of the first resin layer 12a and the second resin layer 12b is preferably about 30-80%, more preferably about 50-70%.

[0100] The adhesive film 1 for metal terminals of this disclosure can be manufactured, for example, by laminating a first resin layer 12a and a second resin layer 12b on both surfaces of an intermediate layer 11, respectively. The lamination of the intermediate layer 11 and the first resin layer 12a and the second resin layer 12b can be carried out by known methods such as extrusion lamination, T-die lamination, inflation lamination, and thermal lamination.

[0101] There are no particular limitations on the method of interposing the adhesive film 1 for metal terminals between the metal terminals 2 and the outer casing material 3 for the energy storage device. For example, as shown in Figures 1 to 3, the adhesive film 1 for metal terminals may be wrapped around the metal terminals 2 in the portion where the metal terminals 2 are sandwiched by the outer casing material 3 for the energy storage device. Although not shown in the figures, the adhesive film 1 for metal terminals may also be placed on both sides of the metal terminals 2 so as to cross both metal terminals 2 in the portion where the metal terminals 2 are sandwiched by the outer casing material 3 for the energy storage device.

[0102] The adhesion promoter layer 13 is a layer provided as needed for the purpose of firmly bonding the intermediate layer 11 to the first resin layer 12a, and to the intermediate layer 11 to the second resin layer 12b (see Figure 7). The adhesion promoter layer 13 may be provided on only one side between the intermediate layer 11 and the first resin layer 12a and the second resin layer 12b, or on both sides. The adhesion promoter layer may contain a temperature-indicating material.

[0103] The adhesion promoter layer 13 can be formed using known adhesion promoters such as isocyanate-based, polyethyleneimine-based, polyester-based, polyurethane-based, and polybutadiene-based promoters. From the viewpoint of obtaining strong adhesion strength, it is preferable that the layer be formed using an isocyanate-based adhesion promoter. Among isocyanate-based adhesion promoters, those consisting of an isocyanate component selected from triisocyanate monomer and polymeric MDI exhibit excellent laminate strength and less reduction in laminate strength at high temperatures. In particular, it is especially preferable to form the bond using an adhesion promoter consisting of a triisocyanate monomer such as triphenylmethane-4,4',4"-triisocyanate or a polymeric MDI such as polymethylene polyphenyl polyisocyanate (NCO content of approximately 30%, viscosity of 200-700 mPa·s). It is also preferable to form the bond using a triisocyanate monomer such as tris(p-isocyanatephenyl)thiophosphate or a two-component curing type adhesion promoter mainly composed of polyethyleneimine with polycarbodiimide as a crosslinking agent.

[0104] Next, the adhesion promoter layer 13 can be formed by applying and drying it by a known coating method such as a bar coating method, a roll coating method, a gravure coating method, etc. The coating amount of the adhesion promoter is, in the case of an adhesion promoter composed of triisocyanate, 20 to 100 mg / m 2 level, preferably 40 to 60 mg / m 2 level, and in the case of an adhesion promoter composed of polymeric MDI, 40 to 150 mg / m 2 level, preferably 60 to 100 mg / m 2 level, and in the case of a two-component curable adhesion promoter with a polyethyleneimine-based main component and a polycarbodiimide crosslinking agent, 5 to 50 mg / m 2 level, preferably 10 to 30 mg / m 2 level. Note that the triisocyanate monomer is a monomer having three isocyanate groups in one molecule, and polymeric MDI is a mixture of MDI and MDI oligomers polymerized by MDI, and is represented by the following formula.

[0105]

Chemical formula

[0106] From the viewpoint of more preferably achieving the effects of the present invention, it is preferable that the first resin layer 12a and the intermediate layer 11 are in contact with each other, and the second resin layer 12b and the intermediate layer 11 are in contact with each other.

[0107] Specific examples of the preferred laminated structure of the adhesive film 1 for metal terminals of the present disclosure include a three-layer structure in which a first resin layer formed of acid-modified polypropylene / an intermediate layer (base material) formed of polypropylene / a second resin layer formed of acid-modified polypropylene are laminated in this order; a three-layer structure in which a first resin layer formed of acid-modified polypropylene / an intermediate layer (base material) formed of polypropylene / a second resin layer formed of polypropylene are laminated in this order, etc. Among these, from the viewpoint of the adhesiveness between the heat-fusible resin layer 35 of the exterior material 3 for the power storage device and the second resin layer 12b, the latter three-layer structure is particularly preferable.

[0108] [Metal terminal 2] The adhesive film 1 for metal terminals of this disclosure is used interposed between a metal terminal 2 and an outer casing material 3 for an energy storage device. The metal terminal 2 (tab) is a conductive member electrically connected to the electrode (positive or negative electrode) of an energy storage device element 4, and is made of a metallic material. The metallic material constituting the metal terminal 2 is not particularly limited and includes, for example, aluminum, nickel, and copper. For example, the metal terminal 2 connected to the positive electrode of a lithium-ion energy storage device is usually made of aluminum or the like. Also, the metal terminal 2 connected to the negative electrode of a lithium-ion energy storage device is usually made of copper, nickel, or the like.

[0109] From the viewpoint of improving electrolyte resistance, it is preferable that the surface of the metal terminal 2 be subjected to a chemical conversion treatment. For example, when the metal terminal 2 is made of aluminum, specific examples of chemical conversion treatment include known methods for forming corrosion-resistant coatings such as phosphates, chromates, fluorides, and triazinethiol compounds. Among the methods for forming corrosion-resistant coatings, phosphate chromate treatment using a material composed of three components: phenolic resin, chromium(III) fluoride compound, and phosphoric acid is preferred.

[0110] The size of the metal terminal 2 can be appropriately set according to the size of the energy storage device used. The thickness of the metal terminal 2 is preferably about 50 to 1000 μm, more preferably about 70 to 800 μm. The length of the metal terminal 2 is preferably about 1 to 200 mm, more preferably about 3 to 150 mm. The width of the metal terminal 2 is preferably about 1 to 200 mm, more preferably about 3 to 150 mm.

[0111] [Exterior material for energy storage devices 3] An example of an exterior material 3 for an energy storage device is one having a laminated structure consisting of a base layer 31, a barrier layer 33, and a heat-fusible resin layer 35 in that order. Figure 8 shows an example of the cross-sectional structure of the exterior material 3 for an energy storage device, in which the base layer 31, an adhesive layer 32 (if necessary), a barrier layer 33, an adhesive layer 34 (if necessary), and a heat-fusible resin layer 35 are laminated in that order. In the exterior material 3 for an energy storage device, the base layer 31 is the outer layer, and the heat-fusible resin layer 35 is the innermost layer. When assembling the energy storage device, the heat-fusible resin layers 35 located around the periphery of the energy storage device element 4 are brought into contact and heat-fused to seal the energy storage device element 4, thereby sealing the energy storage device element 4. Figures 1 to 3 show an energy storage device 10 using an embossed type exterior material 3 for an energy storage device formed by embossing, but the exterior material 3 for an energy storage device may be an unformed pouch type. Note that pouch-type packaging includes three-sided seal, four-sided seal, and pillow-type packaging, but any type is acceptable.

[0112] The thickness of the laminate constituting the outer casing material 3 for the energy storage device is not particularly limited, but from the viewpoint of cost reduction and energy density improvement, the upper limit is preferably about 190 μm or less, preferably about 180 μm or less, about 160 μm or less, about 155 μm or less, about 140 μm or less, about 130 μm or less, and about 120 μm or less. From the viewpoint of maintaining the function of the outer casing material 3 for the energy storage device, which is to protect the energy storage device element 4, the lower limit is preferably about 35 μm or more, about 45 μm or more, about 60 μm or more, and about 80 μm or more. A preferred range is, for example, about 35 to 190 μm, about 35 to 180 μm, and about 35 to 160 μm. degree, about 35 to 155 μm, about 35 to 140 μm, about 35 to 130 μm, about 35 to 120 μm, about 45 to 190 μm, about 45 to 180 μm, 45 ~160μm, 45~155μm, 45~140μm, 45~130μm, 45~120μm, 60~190μm, 60~180μm Examples include approximately m, 60-160 μm, 60-155 μm, 60-140 μm, 60-130 μm, 60-120 μm, 80-190 μm, 80-180 μm, 80-160 μm, 80-155 μm, 80-140 μm, 80-130 μm, and 80-120 μm.

[0113] (Base material layer 31) In the exterior material 3 for the energy storage device, the base layer 31 is a layer that functions as the base material for the exterior material of the energy storage device and is the layer that forms the outermost layer.

[0114] The material forming the base layer 31 is not particularly limited, as long as it possesses insulating properties. Examples of materials for forming the base layer 31 include polyester, polyamide, epoxy, acrylic resin, fluororesin, polyurethane, silicon resin, phenol, polyetherimide, polyimide, and mixtures or copolymers thereof. Polyesters such as polyethylene terephthalate and polybutylene terephthalate have excellent electrolyte resistance and are less prone to whitening when exposed to electrolyte, making them suitable for use as a material for forming the base layer 31. Polyamide films also have excellent stretchability, which can prevent whitening due to resin cracking of the base layer 31 during molding, making them suitable for use as a material for forming the base layer 31.

[0115] The base layer 31 may be formed from a uniaxially or biaxially stretched resin film, or from an unstretched resin film. Among these, uniaxially or biaxially stretched resin films, and especially biaxially stretched resin films, are suitable for use as the base layer 31 because their heat resistance is improved by oriented crystallization.

[0116] Among these, the resin film forming the base layer 31 is preferably nylon, polyester, and more preferably biaxially oriented nylon and biaxially oriented polyester.

[0117] The base layer 31 can also be constructed by laminating resin films of different materials to improve pinhole resistance and insulation when used as packaging for energy storage devices. Specifically, examples include a multilayer structure in which polyester film and nylon film are laminated, or a multilayer structure in which biaxially oriented polyester and biaxially oriented nylon are laminated. When the base layer 31 is made into a multilayer structure, each resin film may be bonded via an adhesive, or it may be laminated directly without an adhesive. When bonding without an adhesive, examples include bonding in a thermally fused state such as co-extrusion, sand lamination, or thermal lamination.

[0118] Furthermore, the base layer 31 may be made friction-reducing to improve moldability. When the base layer 31 is made friction-reducing, there are no particular restrictions on the coefficient of friction of its surface, but for example, it may be 1.0 or less. Examples of methods for making the base layer 31 friction-reducing include mat treatment, formation of a thin film layer of a slip agent, and combinations thereof.

[0119] The thickness of the substrate layer 31 can be, for example, about 10 to 50 μm, preferably about 15 to 30 μm.

[0120] (Adhesive layer 32) In the exterior material 3 for the energy storage device, the adhesive layer 32 is a layer that is placed on the base material layer 31 as needed in order to provide adhesion to the base material layer 31. That is, the adhesive layer 32 is provided between the base material layer 31 and the barrier layer 33.

[0121] The adhesive layer 32 is formed by an adhesive capable of bonding the base layer 31 and the barrier layer 33. The adhesive used to form the adhesive layer 32 may be a two-component curing adhesive or a one-component curing adhesive. Furthermore, the bonding mechanism of the adhesive used to form the adhesive layer 32 is not particularly limited and may be a chemical reaction type, solvent evaporation type, thermal melting type, hot pressure type, etc.

[0122] As for the resin component of the adhesive that can be used to form the adhesive layer 32, from the viewpoint of having excellent ductility, durability under high humidity conditions, yellowing suppression effect, and heat degradation suppression effect during heat sealing, and effectively suppressing the occurrence of delamination by suppressing the decrease in laminate strength between the base layer 31 and the barrier layer 33, two-component curable polyurethane adhesives; polyamide, polyester, or blended resins of these with modified polyolefins are preferred.

[0123] Furthermore, the adhesive layer 32 may be multilayered with different adhesive components. When the adhesive layer 32 is multilayered with different adhesive components, from the viewpoint of improving the lamination strength between the base material layer 31 and the barrier layer 33, it is preferable to select a resin with excellent adhesion to the base material layer 31 as the adhesive component arranged on the base material layer 31 side, and an adhesive component with excellent adhesion to the barrier layer 33 as the adhesive component arranged on the barrier layer 33 side. Specifically, when the adhesive layer 32 is multilayered with different adhesive components, preferred adhesive components arranged on the barrier layer 33 side include acid-modified polyolefins, metal-modified polyolefins, mixed resins of polyester and acid-modified polyolefins, and resins containing copolymerized polyesters.

[0124] The thickness of the adhesive layer 32 can be, for example, about 2 to 50 μm, preferably about 3 to 25 μm.

[0125] (Barrier layer 33) In the exterior material 3 for energy storage devices, the barrier layer 33 is a layer that not only improves the strength of the exterior material for energy storage devices but also prevents water vapor, oxygen, light, etc. from entering the inside of the energy storage device. The barrier layer 33 is preferably a metal layer, that is, a layer made of metal. Specifically, examples of metals that make up the barrier layer 33 include aluminum, stainless steel, and titanium, with aluminum being preferred. The barrier layer 33 can be formed from, for example, metal foil, metal vapor-deposited film, inorganic oxide vapor-deposited film, carbon-containing inorganic oxide vapor-deposited film, or a film provided with these vapor-deposited films, and it is preferably formed from metal foil, and even more preferably from aluminum foil. From the viewpoint of preventing wrinkles and pinholes from occurring in the barrier layer 33 during the manufacturing of the exterior material for energy storage devices, it is more preferable that the barrier layer be formed from soft aluminum foil, such as annealed aluminum (JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, JIS H4000:2014 A8079P-O).

[0126] Regarding the thickness of the barrier layer 33, from the viewpoint of making the exterior material for the energy storage device thinner while also making it less likely for pinholes to occur during molding, it is preferably about 10 to 200 μm, and more preferably about 20 to 100 μm.

[0127] Furthermore, it is preferable that at least one surface, preferably both surfaces, of the barrier layer 33 be chemically treated to stabilize adhesion and prevent dissolution and corrosion. Here, chemical treatment refers to a treatment that forms a corrosion-resistant film on the surface of the barrier layer.

[0128] (adhesive layer 34) In the exterior material 3 for the energy storage device, the adhesive layer 34 is a layer provided between the barrier layer 33 and the heat-fusible resin layer 35 as needed, in order to firmly bond the heat-fusible resin layer 35.

[0129] The adhesive layer 34 is formed by an adhesive capable of bonding the barrier layer 33 and the heat-fusible resin layer 35. The composition of the adhesive used to form the adhesive layer is not particularly limited, but examples include resin compositions containing acid-modified polyolefins. Examples of acid-modified polyolefins are the same as those exemplified in the first resin layer 12a and the second resin layer 12b.

[0130] The thickness of the adhesive layer 34 can be, for example, about 1 to 40 μm, preferably about 2 to 30 μm.

[0131] (Thermal adhesive resin layer 35) In the exterior material 3 for the energy storage device, the heat-sealable resin layer 35 is the innermost layer, and during the assembly of the energy storage device, the heat-sealable resin layers heat-seal each other to seal the energy storage device elements.

[0132] The resin component used in the heat-fusible resin layer 35 is not particularly limited, as long as it is heat-fusible, but examples include polyolefins and cyclic polyolefins.

[0133] Specifically, the polyolefins include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymer of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymer of propylene and ethylene); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferred.

[0134] The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of olefins that are constituent monomers of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, isoprene, and the like. Examples of cyclic monomers that are constituent monomers of the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, norbornadiene, etc. Among these polyolefins, cyclic alkenes are preferred, and norbornene is more preferred. Styrene can also be used as a constituent monomer.

[0135] Among these resin components, preferred are crystalline or amorphous polyolefins, cyclic polyolefins, and blends thereof; more preferably, polyethylene, polypropylene, copolymers of ethylene and norbornene, and blends of two or more of these.

[0136] The heat-fusible resin layer 35 may be formed by a single resin component or by a blended polymer combining two or more resin components. Furthermore, the heat-fusible resin layer 35 may be formed as a single layer or as two or more layers made of the same or different resin components. It is particularly preferable that the resin of the second resin layer 12b and the heat-fusible resin layer 35 are the same, as this improves the adhesion between these layers.

[0137] Furthermore, the thickness of the heat-fusible resin layer 35 is not particularly limited, but is preferably about 2 to 2000 μm, preferably about 5 to 1000 μm, and more preferably about 10 to 500 μm. Also, the thickness of the heat-fusible resin layer 35 can be, for example, about 100 μm or less, preferably about 85 μm or less, and more preferably about 15 to 85 μm. For example, if the thickness of the adhesive layer 34 described later is 10 μm or more, the thickness of the heat-fusible resin layer 35 can be preferably about 85 μm or less, and more preferably about 15 to 45 μm. For example, if the thickness of the adhesive layer 34 is less than 10 μm or if the adhesive layer 34 is not provided, the thickness of the heat-fusible resin layer 35 can be preferably about 20 μm or more, and more preferably about 35 to 85 μm.

[0138] The casing material for energy storage devices of this disclosure may also be in the form of a kit, comprising the casing material for energy storage devices for use in an energy storage device and the adhesive film for metal terminals of this disclosure. In this case as well, the applicable energy storage device comprises at least an energy storage device element having a positive electrode, a negative electrode, and an electrolyte, an casing material for energy storage devices that seals the energy storage device element, and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding from the outside of the casing material for energy storage devices. The kit of this disclosure is used such that the adhesive film for metal terminals of this disclosure is interposed between the metal terminals and the casing material for energy storage devices during use.

[0139] 2. Energy storage devices The energy storage device 10 of this disclosure comprises at least an energy storage device element 4 having a positive electrode, a negative electrode, and an electrolyte; an outer casing material 3 for the energy storage device that seals the energy storage device element 4; and metal terminals 2 electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the outer casing material 3 for the energy storage device. The energy storage device 10 of this disclosure is characterized in that the adhesive film 1 for metal terminals of this disclosure is interposed between the metal terminals 2 and the outer casing material 3 for the energy storage device. That is, the energy storage device 10 of this disclosure can be manufactured by a method that includes a step of interposing the adhesive film 1 for metal terminals of this disclosure between the metal terminals 2 and the outer casing material 3 for the energy storage device.

[0140] Specifically, a storage device element 4 comprising at least a positive electrode, a negative electrode, and an electrolyte is covered with a storage device exterior material 3, with the metal terminals 2 connected to the positive and negative electrodes respectively protruding outwards. The adhesive film 1 for metal terminals of this disclosure is interposed between the metal terminals 2 and the heat-sealable resin layer 35. A flange portion (the area where the heat-sealable resin layers 35 come into contact with each other, and the peripheral edge portion 3a of the storage device exterior material 3) of the storage device exterior material 3 is formed around the periphery of the storage device element 4. The heat-sealable resin layers 35 of the flange portion are then heat-sealed to create a sealed storage device 10 using the storage device exterior material 3. When housing the storage device element 4 using the storage device exterior material 3, the heat-sealable resin layer 35 of the storage device exterior material 3 is used so that it faces inwards (the surface in contact with the storage device element 4).

[0141] The casing material for energy storage devices disclosed herein can be suitably used in energy storage devices such as batteries (including capacitors, capacitors, etc.). Furthermore, the casing material for energy storage devices disclosed herein can be used in either primary batteries or secondary batteries, but is preferably used in secondary batteries. The type of secondary battery to which the casing material for energy storage devices disclosed herein can be 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, capacitors, capacitors, etc. Among these secondary batteries, lithium-ion batteries and lithium-ion polymer batteries are particularly suitable applications for the casing material for energy storage devices disclosed herein. [Examples]

[0142] The present disclosure will be described in detail below with reference to examples and comparative examples. However, the present disclosure is not limited to the examples.

[0143] <Manufacturing of adhesive films for metal terminals> Example 1 Using an extruder and a T-die casting apparatus, a polypropylene (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50 μm) was used as an intermediate layer. On one side, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) was used as the second resin layer on the exterior material side. On the other side, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) containing 0.1% by mass of titanium nitride (average particle size 70 nm) as a thermochromic agent was used as the first resin layer (thermochromic layer) on the metal terminal side. Both layers were extruded to a thickness of 50 μm, resulting in an adhesive film (total thickness 150 μm) in which the first resin layer (thermochromic layer containing titanium nitride, PPa layer, melting peak temperature 140°C, thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163°C, thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124°C, thickness 50 μm) were laminated in that order. The resulting adhesive film had a black appearance because the first resin layer (thermochromic layer) contained black titanium nitride. The intermediate layer and the second resin layer were colorless and transparent.

[0144] Example 2 Using an extruder and a T-die casting apparatus, a polypropylene (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50 μm) was used as an intermediate layer. On one side, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) was used as the second resin layer on the exterior material side. On the other side, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) containing 1.0 mass% titanium nitride (average particle size 70 nm) as a thermochromic agent was used as the first resin layer (thermochromic layer) on the metal terminal side. Both layers were extruded to a thickness of 50 μm, resulting in an adhesive film (total thickness 150 μm) in which the first resin layer (thermochromic layer containing titanium nitride, PPa layer, melting peak temperature 140°C, thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163°C, thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124°C, thickness 50 μm) were laminated in that order. The resulting adhesive film had a black appearance because the first resin layer (thermochromic layer) contained black titanium nitride. The intermediate layer and the second resin layer were colorless and transparent.

[0145] Example 3 Using an extruder and a T-die casting apparatus, a polypropylene (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50 μm) was used as an intermediate layer. On one side, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) was used as the second resin layer on the exterior material side. On the other side, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) containing 1.0 mass% titanium nitride (average particle size 20 nm) as a thermochromic agent was used as the first resin layer (thermochromic layer) on the metal terminal side. Both layers were extruded to a thickness of 50 μm, resulting in an adhesive film (total thickness 150 μm) in which the first resin layer (thermochromic layer containing titanium nitride, PPa layer, melting peak temperature 140°C, thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163°C, thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124°C, thickness 50 μm) were laminated in that order. The resulting adhesive film had a black appearance because the first resin layer (thermochromic layer) contained black titanium nitride. The intermediate layer and the second resin layer were colorless and transparent.

[0146] Example 4 Using an extruder and a T-die casting apparatus, a polypropylene (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50 μm) was used as an intermediate layer. On one side, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) was used as the second resin layer on the exterior material side. On the other side, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) containing 1.0 mass% titanium nitride (average particle size 50 nm) as a thermochromic agent was used as the first resin layer (thermochromic layer) on the metal terminal side. Both layers were extruded to a thickness of 50 μm, resulting in an adhesive film (total thickness 150 μm) in which the first resin layer (thermochromic layer containing titanium nitride, PPa layer, melting peak temperature 140°C, thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163°C, thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124°C, thickness 50 μm) were laminated in that order. The resulting adhesive film had a black appearance because the first resin layer (thermochromic layer) contained black titanium nitride. The intermediate layer and the second resin layer were colorless and transparent.

[0147] Example 5 Using an extruder and a T-die casting apparatus, a polypropylene (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50 μm) was used as an intermediate layer. On one side, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) was used as the second resin layer on the exterior material side. On the other side, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) containing 10.0% by mass of titanium nitride (average particle size 70 nm) as a thermochromic agent was used as the first resin layer (thermochromic layer) on the metal terminal side. Both layers were extruded to a thickness of 50 μm, resulting in an adhesive film (total thickness 150 μm) in which the first resin layer (thermochromic layer containing titanium nitride, PPa layer, melting peak temperature 140°C, thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163°C, thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124°C, thickness 50 μm) were laminated in that order. The resulting adhesive film had a black appearance because the first resin layer (thermochromic layer) contained black titanium nitride. The intermediate layer and the second resin layer were colorless and transparent.

[0148] Example 6 Using an extruder and a T-die casting apparatus, a polypropylene (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50 μm) was used as an intermediate layer. On one side, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) was used as the second resin layer on the exterior material side. On the other side, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) containing 0.01% by mass of titanium nitride (average particle size 70 nm) as a thermochromic agent was used as the first resin layer (thermochromic layer) on the metal terminal side. Both layers were extruded to a thickness of 50 μm, resulting in an adhesive film (total thickness 150 μm) in which the first resin layer (thermochromic layer containing titanium nitride, PPa layer, melting peak temperature 140°C, thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163°C, thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124°C, thickness 50 μm) were laminated in that order. The resulting adhesive film had a black appearance because the first resin layer (thermochromic layer) contained black titanium nitride. The intermediate layer and the second resin layer were colorless and transparent.

[0149] Example 7 Using an extruder and a T-die casting apparatus, a polypropylene (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50 μm) was used as an intermediate layer. On one side, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) was used as the second resin layer on the exterior material side. On the other side, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) containing 50.0% by mass of titanium nitride (average particle size 70 nm) as a thermochromic agent was used as the first resin layer (thermochromic layer) on the metal terminal side. Both layers were extruded to a thickness of 50 μm, resulting in an adhesive film (total thickness 150 μm) in which the first resin layer (thermochromic layer containing titanium nitride, PPa layer, melting peak temperature 140°C, thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163°C, thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124°C, thickness 50 μm) were laminated in that order. The resulting adhesive film had a black appearance because the first resin layer (thermochromic layer) contained black titanium nitride. The intermediate layer and the second resin layer were colorless and transparent.

[0150] Comparative Example 1 Using an extruder and a T-die casting apparatus, a polypropylene (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50 μm) was used as an intermediate layer. On one side, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) was used as the second resin layer on the exterior material side. On the other side, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) containing 0.5% by mass of carbon black (average particle size 300 nm) was used as the first resin layer on the metal terminal side. Both layers were extruded to a thickness of 50 μm, resulting in an adhesive film (total thickness 150 μm) in which the first resin layer (layer containing carbon black, PPa layer, melting peak temperature 140°C, thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163°C, thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124°C, thickness 50 μm) were laminated in that order. The resulting adhesive film had a black appearance because the first resin layer contained black carbon black. The intermediate layer and the second resin layer were colorless and transparent.

[0151] Comparative Example 2 Using an extruder and a T-die casting apparatus, a polypropylene (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50 μm) was extruded as an intermediate layer, with a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) as the second resin layer on the exterior material side, and a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) as the first resin layer on the metal terminal side, both with a thickness of 50 μm. An adhesive film (total thickness 150 μm) was obtained in which the first resin layer (PPa layer, melting peak temperature 140°C, thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163°C, thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124°C, thickness 50 μm) were laminated in that order. The obtained adhesive film is colorless and transparent.

[0152] Comparative Example 3 Using an extruder and a T-die casting apparatus, a polypropylene (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50 μm) was extruded as an intermediate layer, with a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) as the second resin layer on the exterior material side, and a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) as the first resin layer on the metal terminal side, both with a thickness of 50 μm. An adhesive film (total thickness 150 μm) was obtained in which the first resin layer (PPa layer, melting peak temperature 140°C, thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163°C, thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124°C, thickness 50 μm) were laminated in that order. The obtained adhesive film is colorless and transparent.

[0153] Comparative Example 4 Using an extruder and a T-die casting apparatus, a polypropylene (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50 μm) was used as an intermediate layer. On one side, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) was used as the second resin layer on the exterior material side. On the other side, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) containing 1.0 mass% carbon black (average particle size 300 nm) was used as the first resin layer on the metal terminal side. Both layers were extruded to a thickness of 50 μm, resulting in an adhesive film (total thickness 150 μm) in which the first resin layer (layer containing carbon black, PPa layer, melting peak temperature 140°C, thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163°C, thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124°C, thickness 50 μm) were laminated in that order. The resulting adhesive film had a black appearance because the first resin layer contained black carbon black. The intermediate layer and the second resin layer were colorless and transparent.

[0154] <Measurement of melting peak temperature> For adhesive films, the melting peak temperature was measured in accordance with the provisions of JIS K7121:2012 (Method for Measuring Transition Temperature of Plastics (Supplement 1 to JIS K7121:1987)). The measurement was performed using a differential scanning calorimeter (DSC, Q200 differential scanning calorimeter manufactured by T.A. Instruments). The sample was held at -50°C for 15 minutes, then heated from -50°C to 210°C at a heating rate of 10°C / min, and the first melting peak temperature P (°C) was measured. After that, it was held at 210°C for 10 minutes. Next, it was cooled from 210°C to -50°C at a cooling rate of 10°C / min and held for 15 minutes. Furthermore, it was heated from -50°C to 210°C at a heating rate of 10°C / min, and the second melting peak temperature Q (°C) was measured. The nitrogen gas flow rate was 50 ml / min. Following the above procedure, the melting peak temperature P (°C) measured in the first measurement and the melting peak temperature Q (°C) measured in the second measurement were determined. The value of the melting peak temperature P (°C) measured in the first measurement was adopted.

[0155] <L of adhesive film before and after heating *Measurement of values ​​> As metal terminals, aluminum (JIS H4160:1994 A8079H-O) with dimensions of 50 mm in length, 45 mm in width, and 0.4 mm in thickness was prepared. Two pieces of adhesive film for metal terminals from the examples and comparative examples were also prepared, each 45 mm long and 10 mm wide. Next, an adhesive film for metal terminals was sandwiched between the two adhesive films to obtain a laminate of adhesive film / metal terminal / adhesive film. At this time, the vertical and horizontal directions of the metal terminals coincided with the width and length directions of the adhesive film for metal terminals, respectively, and the centers of the metal terminals and the adhesive film for metal terminals coincided. The obtained laminate was placed on a hot plate. Next, the adhesive film was heated under the following conditions (heating temperature of 280°C and 300°C, heating pressure of 0.25 MPa, and heating time of 16 seconds). Next, the surface of the first resin layer side of the adhesive film before and after heating was subjected to the following conditions: * a * b * L in color space * The values ​​were measured. The observation conditions of a Konica Minolta spectrophotometer (CM-700d), calibrated with a white calibration cap (CM-A177: manufactured by Konica Minolta), were set to 10°, the observation light source to F2, and SCI mode (JIS Z8722-2009). Next, the L on the surface of the first resin layer was measured. * The values ​​were measured under normal temperature and humidity conditions. The measurement diameter was set to 8 mmφ. The results are shown in Table 1. Note that in Table 1, L * The values ​​shown are the measured values ​​rounded to the first decimal place.

[0156] <Evaluation of adhesion to metal terminals> The above-mentioned L of the adhesive film before and after heating *In the measurement of values, adhesive films for the examples and comparative examples were prepared by heating and pressurizing under the same conditions as the adhesive films heated at 280°C and 300°C, respectively, and the adhesion of these adhesive films to metal terminals was evaluated by the following method. The results are shown in Table 1. In the expression of the size of the rectangular strip adhesive film, the length and width are specified as the MD direction for length and the TD direction for width. As the metal terminal, aluminum (JIS H4160:1994 A8079H-O) with a length of 50 mm, a width of 22.5 mm, and a thickness of 0.4 mm was prepared. The adhesive film for metal terminals was cut to a length of 45 mm and a width of 10 mm. Next, the adhesive film for metal terminals was placed on the metal terminal to obtain a laminate of metal terminal / adhesive film. At this time, the vertical and horizontal directions of the metal terminal coincided with the length and width directions of the adhesive film for metal terminals, respectively, and the lamination was performed so that the centers of the metal terminal and the adhesive film for metal terminals coincided. Furthermore, the first resin layer of the adhesive film for metal terminals is positioned on the metal terminal side. Next, a tetrafluoroethylene-ethylene copolymer film (ETFE film, 100 μm thick) was placed on top of the adhesive film for metal terminals of the laminate (the surface of the adhesive film for metal terminals was covered with the ETFE film), and the laminate was placed on a press heated to 200°C (with the metal terminals on the hot plate side), and a silicone sponge sheet was placed on top, and the laminate was left standing at a pressure of 0.25 MPa for 16 seconds to heat-seal the adhesive film to the metal terminals. The laminate was then allowed to cool naturally to 25°C. Next, in an environment of 25°C, the adhesive film for metal terminals was peeled off the metal terminals using a Tensilon universal material tester (RTG-1210, manufactured by A&D Co., Ltd.). The maximum strength at the time of peeling was defined as the adhesion strength to the metal terminals (N / 15 mm). Note that this adhesion strength is a converted value from the measurement result at a width of 10 mm to the measurement result at a width of 15 mm. The peeling speed was set to 50 mm / min, the peeling angle to 180°, and the chuck distance to 30 mm. The average value of three measurements was used. The treatment of leaving the material undisturbed for 16 seconds in a heated and pressurized environment at a temperature of 200°C and a surface pressure of 0.25 MPa was intended to simulate the heat and pressure applied during the temporary bonding and main bonding processes described above. (Evaluation criteria for adhesion at 280°C and 300°C) A: The adhesion strength is 40 N / 15 mm or higher. B: Adhesion strength is less than 40 N / 15 mm

[0157] [Table 1]

[0158] The adhesive films for metal terminals of Examples 1 to 7 are equipped with a thermochromic layer containing titanium nitride as a thermochromic agent, and are suitable for use between 280°C and 320°C. * The value had changed significantly, and it was evident from its appearance that it had been heated to the predetermined temperature.

[0159] As described above, this disclosure provides inventions in the following embodiments. Item 1. An adhesive film for metal terminals, interposed between a metal terminal electrically connected to the electrodes of a power storage device element and an outer casing material for a power storage device that seals the power storage device element, The aforementioned adhesive film for metal terminals is an adhesive film for metal terminals comprising a heat-discoloring layer. Item 2. The adhesive film for metal terminals according to Item 1, wherein the heat-sensitive layer is formed from a resin composition comprising a thermochromic material and a resin. Item 3. The temperature-indicating material is an adhesive film for metal terminals as described in Item 2, comprising an inorganic compound. Item 4. The temperature-indicating material is an adhesive film for metal terminals as described in Item 2 or 3, wherein the average particle size is 10 nm or more and 100 nm or less. Item 5. The adhesive film for metal terminals according to any one of items 2 to 4, wherein the content of the thermochromic material in the heat-discoloring layer is 0.01% by mass or more and 50% by mass or less. Item 6. The adhesive film for metal terminals according to any one of items 2 to 5, wherein the temperature-indicating material is titanium nitride. Item 7. The heat-discoloring layer is an adhesive film for metal terminals according to any one of items 1 to 6, having a polyolefin skeleton. Item 8. The adhesive film for metal terminals according to any one of items 1 to 7, wherein the thermally discolored layer, when analyzed by infrared spectroscopy, shows a peak originating from maleic anhydride. Item 9. The L of the reflected light of the thermal discoloration layer is measured under the measurement conditions of SCI method, field of view 10° and light source F2. * a * b * L in color space * An adhesive film for metal terminals as described in any one of items 1 to 8, wherein the value is 80 or less. Item 10. The adhesive film for metal terminals is composed of a laminate comprising, in this order, a first resin layer disposed on the metal terminal side, an intermediate layer, and a second resin layer disposed on the exterior material side for the energy storage device. The adhesive film for metal terminals according to any one of claims 1 to 9, wherein at least one of the first resin layer, the intermediate layer, and the second resin layer is the heat-discoloring layer. Item 11. The adhesive film for metal terminals according to any one of items 1 to 10, wherein the adhesive film for metal terminals is formed of a polyolefin resin. Item 12. A method for manufacturing an adhesive film for metal terminals, which is interposed between a metal terminal electrically connected to the electrodes of an energy storage device element and an outer casing material for an energy storage device that seals the energy storage device element, The adhesive film for metal terminals comprises a heat-discoloring layer, and the method for manufacturing an adhesive film for metal terminals. Item 13. A metal terminal with an adhesive film for metal terminals, wherein an adhesive film for metal terminals described in any one of items 1 to 11 is attached to the metal terminal. Item 14. A power storage device comprising at least a positive electrode, a negative electrode, and an electrolyte; an outer casing material for a power storage device that seals the power storage device element; and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the outer casing material for a power storage device, An energy storage device in which an adhesive film for metal terminals described in any one of items 1 to 11 is interposed between the metal terminal and the exterior material for the energy storage device. Item 15. A method for manufacturing an energy storage device comprising at least a positive electrode, a negative electrode, and an electrolyte; an outer casing material for the energy storage device that seals the energy storage device element; and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the outer casing material for the energy storage device, A method for manufacturing an energy storage device, comprising the step of interposing an adhesive film for metal terminals described in any one of items 1 to 11 between the metal terminals and the exterior material for the energy storage device, and sealing the energy storage device element with the exterior material for the energy storage device. Item 16. Exterior material for energy storage devices, for use in energy storage devices, The energy storage device comprises at least an energy storage device element having a positive electrode, a negative electrode, and an electrolyte; an outer casing material for the energy storage device that seals the energy storage device element; and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the outer casing material for the energy storage device, with an adhesive film for metal terminals interposed between the metal terminals and the outer casing material for the energy storage device. The adhesive film for metal terminals is the adhesive film for metal terminals described in any one of items 1 to 11. The exterior material for the energy storage device is composed of a laminate comprising at least a base layer, a barrier layer, and a heat-fusible resin layer. Item 17. A kit comprising an exterior material for energy storage devices for use in energy storage devices and an adhesive film for metal terminals as described in any one of items 1 to 11, The energy storage device comprises at least an energy storage device element having a positive electrode, a negative electrode, and an electrolyte; an outer casing material for the energy storage device that encloses the energy storage device element; and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the outer casing material for the energy storage device. A kit used in which, when in use, the adhesive film for metal terminals is interposed between the metal terminals and the outer material for the energy storage device. [Explanation of Symbols]

[0160] 1. Adhesive film for metal terminals 2 metal terminals 3. Exterior materials for energy storage devices 3a Peripheral edge of exterior material for energy storage device 4 Energy Storage Device Elements 10 Energy storage devices 11 Middle Class 12a 1st resin layer 12b 2nd resin layer 31 Base material layer 32 Adhesive layer 33 Barrier layer 34 Adhesive layer 35 Heat-fusible resin layer

Claims

1. An adhesive film for metal terminals, interposed between a metal terminal electrically connected to the electrode of an energy storage device element and an outer casing material for an energy storage device that seals the energy storage device element, The aforementioned adhesive film for metal terminals includes a heat-discoloring layer, The aforementioned heat-sensitive layer is formed from a resin composition containing a temperature-indicating material and a resin. The temperature-indicating material contains titanium nitride. The average particle size of the titanium nitride is 10 nm or more and 100 nm or less. The heat-discoloring layer is measured under the SCI method, field of view 10°, and light source F2 measurement conditions before and after the adhesive film for metal terminals is heated from 25°C to 300°C, and the L of the reflected light is measured. * a * b * L in color space * Adhesive film for metal terminals, where the difference in values ​​is between 10 and 90.

2. The adhesive film for metal terminals according to claim 1, wherein the temperature-indicating material has an average particle diameter of 10 nm or more and 100 nm or less.

3. The adhesive film for metal terminals according to claim 1 or 2, wherein the content of the thermochromic material in the heat-discoloring layer is 0.01% by mass or more and 50% by mass or less.

4. The adhesive film for metal terminals according to claim 2 or 3, wherein the temperature-indicating material is titanium nitride.

5. The heat-discoloring layer has a polyolefin backbone, as described in claim 1 or 2, for the adhesive film for metal terminals.

6. The adhesive film for metal terminals according to claim 1 or 2, wherein when the thermally discolored layer is analyzed by infrared spectroscopy, a peak originating from maleic anhydride is detected.

7. The aforementioned thermal discoloration layer is measured under the SCI method, field of view 10°, and light source F2 conditions, and the reflected light L * a * b * L in color space * The adhesive film for metal terminals according to claim 1 or 2, wherein the value is 80 or less.

8. The adhesive film for metal terminals is composed of a laminate comprising, in this order, a first resin layer disposed on the metal terminal side, an intermediate layer, and a second resin layer disposed on the exterior material side for the energy storage device. The adhesive film for metal terminals according to claim 1 or 2, wherein at least one of the first resin layer, the intermediate layer, and the second resin layer is the heat-discoloring layer.

9. The adhesive film for metal terminals according to claim 1 or 2, wherein the adhesive film for metal terminals is formed of a polyolefin resin.

10. A metal terminal with an adhesive film for metal terminals, wherein the adhesive film for metal terminals described in claim 1 or 2 is attached to the metal terminal.

11. A power storage device comprising at least a positive electrode, a negative electrode, and an electrolyte; an outer casing material for the power storage device that seals the power storage device element; and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the outer casing material for the power storage device, An energy storage device comprising an adhesive film for metal terminals according to claim 1 or 2 interposed between the metal terminal and the exterior material for the energy storage device.

12. A method for manufacturing an energy storage device comprising at least a positive electrode, a negative electrode, and an electrolyte; an outer casing material for the energy storage device that seals the energy storage device element; and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the outer casing material for the energy storage device, A method for manufacturing an energy storage device, comprising the step of interposing an adhesive film for metal terminals according to claim 1 or 2 between the metal terminals and the exterior material for the energy storage device, and sealing the energy storage device element with the exterior material for the energy storage device.

13. A kit comprising an exterior material for energy storage devices for use in energy storage devices and an adhesive film for metal terminals according to claim 1 or 2, The energy storage device comprises at least an energy storage device element having a positive electrode, a negative electrode, and an electrolyte; an outer casing material for the energy storage device that encloses the energy storage device element; and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the outer casing material for the energy storage device. A kit used in which, when in use, the adhesive film for metal terminals is interposed between the metal terminals and the outer material for the energy storage device.

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