Metal-terminal adhesive film and manufacturing method therefor, metal terminal equipped with metal-terminal adhesive film, power-storage-device external packaging material, kit comprising power-storage-device external packaging material and metal-terminal adhesive film, and power storage device and manufacturing method therefor

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

Adhesive film for metal terminal and manufacturing method thereof, metal terminal with adhesive film for metal terminal, exterior material for electricity storage device, kit including exterior material for electricity storage device and adhesive film for metal terminal, and electricity storage device and manufacturing method thereof

[0001] The present 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 electricity storage device, a kit including an exterior material for an electricity storage device and an adhesive film for metal terminals, and an electricity storage device and a method for manufacturing the same.

[0002] Various types of electricity storage devices have been developed to date, and in all electricity storage devices, exterior materials for electricity storage devices have become essential components for sealing electricity storage device elements such as electrodes and electrolytes. Metal exterior materials for electricity storage devices have traditionally been widely used as exterior materials for electricity storage devices. However, in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, and the like, electricity storage devices are being required to have a variety of shapes, as well as to be thinner and lighter. However, the metal exterior materials for electricity storage devices that have traditionally been widely used have the drawbacks of being difficult to keep up with the diversification of shapes and also having limitations on how much they can be made lighter.

[0003] Therefore, in recent years, a laminate sheet in which a base material layer / an adhesive layer / a barrier layer / a heat-sealable resin layer are laminated in this order has been proposed as an electrical storage device packaging material that can be easily processed into a variety of shapes and can achieve thinning and weight reduction. When such a laminate film-like electrical storage device packaging material is used, the electrical storage device elements are sealed by the electrical storage device packaging material by heat-sealing the peripheral edge of the electrical storage device packaging material with the heat-sealable resin layers positioned in the innermost layers of the electrical storage device packaging material facing each other.

[0004] Metal terminals protrude from the heat-sealed portions of the exterior material for an electricity storage device, and the electricity storage device elements sealed with the exterior material for an electricity storage device are electrically connected to the outside via the metal terminals electrically connected to the electrodes of the electricity storage device elements. That is, the portions of the heat-sealed exterior material for an electricity storage device where the metal terminals are present are heat-sealed in a state where the metal terminals are sandwiched between the heat-sealable resin layers. Because the metal terminals and the heat-sealable resin layer are made of different materials, adhesion is likely to decrease at the interface between the metal terminals and the heat-sealable resin layer.

[0005] For this reason, an adhesive film is sometimes disposed between the metal terminal and the heat-sealable resin layer in order to enhance adhesion therebetween, etc. Examples of such adhesive films include those described in Patent Document 1.

[0006] JP 2015-79638 A

[0007] The adhesive film disposed between the metal terminal and the exterior material for an electricity storage device covers the periphery of the metal terminal by heat-sealing the exterior material while sandwiching the metal terminal between the adhesive film on both sides. For example, during heat sealing, the adhesive film is heated to a high temperature. Furthermore, during production of the adhesive film, the resin forming the adhesive film is melted and formed into a film, so the resin forming the adhesive film is heated to a high temperature. Furthermore, even after the adhesive film is applied to an electricity storage device, if the electricity 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] In this way, the adhesive film disposed between the metal terminal and the exterior material for the electricity storage device may be exposed to a high-temperature environment during the manufacturing of the adhesive film, when the adhesive film is applied to the electricity storage device, and even after application.

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

[0010] The inventors of the present disclosure have set a new problem of determining from the appearance whether the resin forming the adhesive film has been heated to a predetermined temperature. If such a problem is solved, an excellent effect can be achieved, for example, in that an adhesive film whose properties may have deteriorated can be identified from the appearance.

[0011] In light of these circumstances, a primary object of the present disclosure is to provide an adhesive film for metal terminals that is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, and that allows for visual confirmation that the film has been heated to a predetermined temperature. Further, other objects of the present disclosure include providing a method for manufacturing the adhesive film for metal terminals, a metal terminal with an adhesive film for metal terminals, an exterior material for an electricity storage device, a kit including an exterior material for an electricity storage device and the adhesive film for metal terminals, an electricity storage device, and a method for manufacturing the electricity storage device.

[0012] The inventors of the present disclosure conducted extensive research to solve the above-mentioned problems. As a result, they found that by providing a thermochromic layer in an adhesive film for metal terminals, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, it is possible to determine from the appearance that a resin contained in the adhesive film for metal terminals has been heated to a predetermined temperature. The present disclosure was completed through further research based on this finding.

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

[0014] According to the present disclosure, it is possible to provide an adhesive film for metal terminals that is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, and that makes it possible to determine from its appearance whether the film has been heated to a predetermined temperature.Furthermore, it is an object of the present disclosure to provide a method for manufacturing the adhesive film for metal terminals, a metal terminal with an adhesive film for metal terminals, an exterior material for an electricity storage device, a kit including an exterior material for an electricity storage device and an adhesive film for metal terminals, and an electricity storage device and a method for manufacturing the same.

[0015] Fig. 1 is a schematic plan view of an electricity storage device according to the present disclosure. Fig. 2 is a schematic cross-sectional view taken along line AA' in Fig. 1. Fig. 3 is a schematic cross-sectional view taken along line BB' in Fig. 1. Fig. 4 is a schematic cross-sectional view of an adhesive film for a metal terminal according to the present disclosure. Fig. 5 is a schematic cross-sectional view of an adhesive film for a metal terminal according to the present disclosure. Fig. 6 is a schematic cross-sectional view of an adhesive film for a metal terminal according to the present disclosure. Fig. 7 is a schematic cross-sectional view of an exterior material for an electricity storage device according to the present disclosure.

[0016] The adhesive film for metal terminals of the present disclosure is an adhesive film for metal terminals that is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that seals the electricity storage device element, and is characterized in that the adhesive film for metal terminals has a thermochromic layer.

[0017] The electricity storage device of the present disclosure is also an electricity storage device comprising at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude outside the exterior material for an electricity storage device, and is characterized in that an adhesive film for metal terminals of the present disclosure is interposed between the metal terminals and the exterior material for an electricity storage device.

[0018] The adhesive film for metal terminal and its manufacturing method, and the electricity storage device and its manufacturing method according to the present disclosure will be described in detail below.

[0019] In this specification, when referring to a numerical range, a numerical range indicated with "to" means "greater than or equal to" or "less than or equal to." For example, the notation 2 to 15 mm means 2 mm or greater and 15 mm or less. In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, separately described upper and lower limits, upper and lower limits, or lower and lower limits may each be combined to form a numerical range. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples.

[0020] 1. Adhesive Film for Metal Terminal The adhesive film for metal terminal of the present disclosure is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element. Specifically, as shown in Figures 1 to 3, for example, an adhesive film for metal terminal 1 of the present disclosure is interposed between a metal terminal 2 electrically connected to an electrode of an electricity storage device element 4 and an exterior material for an electricity storage device 3 that encapsulates the electricity storage device element 4. The metal terminal 2 protrudes outside the exterior material for an electricity storage device 3 and is sandwiched between the exterior material for an electricity storage device 3, via the adhesive film for metal terminal 1, at a peripheral portion 3a of the heat-sealed exterior material for an electricity storage device 3.

[0021] In the present disclosure, the temporary bonding step of the adhesive film for metal terminal to the metal terminal is carried out, for example, under conditions of a temperature of about 140 to 160°C, a pressure of about 0.01 to 1.0 MPa, a time of about 3 to 15 seconds, and a number of times of about 3 to 6, while the main bonding step is carried out, for example, under conditions of a temperature of about 160 to 240°C, a pressure of about 0.01 to 1.0 MPa, a time of about 3 to 15 seconds, and a number of times of about 1 to 3. Furthermore, when the metal terminal with the adhesive film for metal terminal is interposed between the exterior material for an electricity storage device and heat-sealed, the heating temperature is typically in the range of about 180 to 210°C, the pressure is typically about 1.0 to 2.0 MPa, the time is about 3 to 5 seconds, and a number of times of about 1.

[0022] The adhesive film 1 for metal terminals of the present disclosure is provided to improve adhesion between the metal terminal 2 and the electricity storage device exterior material 3. By improving adhesion between the metal terminal 2 and the electricity storage device exterior material 3, the sealing performance of the electricity storage device element 4 is improved. As described above, when the electricity storage device element 4 is heat-sealed, the electricity storage device element is sealed such that the metal terminal 2 electrically connected to the electrode of the electricity storage device element 4 protrudes outside the electricity storage device exterior material 3. At this time, the metal terminal 2 made of metal and the heat-sealable resin layer 35 (a layer made of a heat-sealable resin such as polyolefin) located in the innermost layer of the electricity storage device exterior material 3 are made of different materials. Therefore, without using such an adhesive film, the sealing performance of the electricity storage device element is likely to be reduced at the interface between the metal terminal 2 and the heat-sealable resin layer 35.

[0023] [Thermochromic Layer] The adhesive film 1 for metal terminals of the present disclosure includes 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. The thermochromic material refers to a material (compound) that has the property of changing color when placed in a certain temperature environment. As described below, various inorganic and organic compounds are known as materials that have this property.

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

[0025] As long as the effects of the present disclosure are achieved, the adhesive film 1 for metal terminals of the present disclosure may be a single layer as shown in FIG. 4 or may be a multilayer as shown in FIGS.

[0026] When the adhesive film for metal terminal 1 of the present disclosure is a single layer, the adhesive film for metal terminal 1 is composed of a thermochromic layer, and the surface on the metal terminal side and the surface of the exterior material for an electrical storage device are formed by this thermochromic layer. In this case, the resin forming the surface on the exterior material for an electrical storage device side of the adhesive film for metal terminal 1 and the resin forming the surface on the metal terminal side are the same resin (i.e., the resin forming the thermochromic layer). Note that the resin forming the surface on the exterior material for an electrical storage device side of the adhesive film for metal terminal 1 and the resin forming the surface on the metal terminal side being the same means that, for example, 80% by mass or more of the components in these resins are the same, 90% by mass or more of the same, 95% by mass or more of the same, or 100% by mass or more of the same.

[0027] When the adhesive film for metal terminal 1 of the present disclosure has a multilayer structure, for example, when the adhesive film for metal terminal 1 of the present disclosure has a two-layer structure as shown in Figure 5, the adhesive film for metal terminal 1 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 thermochromic layer. Even when the adhesive film for metal terminal 1 of the present disclosure has a multilayer structure, the resin forming the surface on the exterior material side for an electricity storage device and the resin forming the surface on the metal terminal side may be the same resin.

[0028] 6, when the adhesive film for metal terminal 1 of the present disclosure has a three-layer structure, the adhesive film for metal terminal 1 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 the present disclosure, the first resin layer 12a forms the surface on the metal terminal side, and the second resin layer 12b forms the surface on the exterior material side for an electricity storage device.

[0029] In the adhesive film for metal terminal 1 of the present disclosure, the thermochromic layer preferably has thermal adhesion to metal (the metal constituting the metal terminal). In this case, the thermochromic layer can be disposed on the metal terminal side of the adhesive film for metal terminal 1. For example, in the present disclosure, of the first resin layer 12a and the second resin layer 12b, at least the first resin layer 12a can be formed of a thermochromic layer.

[0030] The surface of the adhesive film for metal terminal 1 of the present disclosure facing the exterior material for an electrical storage device (e.g., the second resin layer 12b) has thermal adhesion to the thermally adhesive resin layer described below. The thermochromic layer preferably also has thermal adhesion to the thermally adhesive resin layer described below. The thermochromic layer can be disposed on the exterior material side of the adhesive film for metal terminal 1 for an electrical storage device. For example, in the present disclosure, of the first resin layer 12a and the second resin layer 12b, at least the second resin layer 12b can be formed by a thermochromic layer.

[0031] The thermochromic 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 temperature indicating material, that is, the thermochromic layer is, for example, a resin layer formed from a resin composition containing a temperature indicating material and a resin.

[0033] There are no particular restrictions on the temperature-indicating material, as long as it is a material (compound) that has the property of changing color when placed in a certain temperature environment, and various inorganic and organic compounds are known as materials that have this property.

[0034] The temperature at which a temperature indicator changes color when heated from room temperature (25°C) is specific to each temperature indicator, so a temperature indicator can be selected depending on the heating temperature to be determined from the appearance of the adhesive film for metal terminal 1. Examples of temperature ranges at which the temperature indicator used in the present disclosure changes color when heated from room temperature (25°C) include 120 to 150°C, 200 to 240°C, and 280 to 320°C. For example, if the adhesive film for metal terminal 1 contains a polyolefin, the color change preferably occurs between 280 and 320°C, at which point the polyolefin begins to deteriorate. Furthermore, when the adhesive film for metal terminal 1 is preheat-sealed to a metal terminal or when an exterior material for an electrical storage device is heat-sealed via the adhesive film for metal terminal 1, the color change preferably occurs between 200 and 240°C from the perspective of confirming that the adhesive film for metal terminal 1 has been heat-sealed. The color change preferably occurs between 280 and 320°C from the perspective of determining whether the heat-sealing temperature was too high. Furthermore, when it is possible to determine from the adhesive film 1 for metal terminals whether the electricity storage device has experienced thermal runaway and is reaching a high temperature, it is preferable that the color change occurs between 120 and 150° C. As described 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 the present 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 is oxidized to titanium dioxide and changes color to white. Therefore, if titanium nitride (titanium black) is used as the temperature indicator for the thermochromic layer, the adhesive film 1 for metal terminals retains its black color from room temperature to 280°C, but changes color to white when heated to 300°C. This makes it possible to determine from its appearance whether the film has been exposed to an extremely high temperature of 300°C. When the adhesive film 1 for metal terminals is exposed to a high temperature of 300°C, the resin deteriorates and the properties of the adhesive film 1 for metal terminals tend to deteriorate. Therefore, it is possible to determine from its appearance whether the properties of the adhesive film 1 for metal terminals are degraded. Furthermore, during the manufacturing process of the adhesive film 1 for metal terminals, the resin may be heated to 300°C. Even in such cases, by confirming that the thermochromic layer, which should be manufactured as black, has changed to white, it is possible to determine from the appearance whether the properties of the adhesive film 1 for metal terminals may be degraded.

[0036] Specific examples of temperature indicators 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, for example, inorganic particles are unlikely to leach into the electrolyte. Furthermore, inorganic particles have a significant coloring effect, and can achieve a sufficient coloring effect even when added in an amount that does not impair adhesion. They do not melt due to heat, and can increase the apparent melt viscosity of the added resin. Furthermore, they can prevent the pressure-applied portion from becoming thin during thermal bonding (heat sealing), thereby providing excellent sealing between the exterior material for an electrical storage device and the metal terminal. The thermochromic layer may contain only one type of temperature indicator, or two or more types. Among these temperature indicators, titanium nitride (titanium black) is particularly preferred from the viewpoint of more optimally demonstrating the effects of the present disclosure.

[0037] The color of the temperature indicator is not particularly limited, but from the viewpoint of more suitably exhibiting the effects of the present disclosure, black, gray, etc. are preferred, and black is particularly preferred. The thermochromic layer can be colored in a color corresponding to the color of the temperature indicator, and the adhesive film for metal terminal 1 of the present disclosure allows the color of the thermochromic layer to be visually recognized from the exterior.

[0038] The thermochromic layer is measured by the SCI method under the measurement conditions of a 10° field of view and an F2 light source. * a * b * L in color space * The value is preferably about 90 or less, more preferably about 80 or less, even more preferably about 70 or less, and is preferably about 10 or more, more preferably about 20 or more, even more preferably about 30 or more. Preferred ranges include about 10 to 90, about 10 to 80, about 10 to 70, about 20 to 90, about 20 to 80, about 20 to 70, about 30 to 90, about 30 to 80, and about 30 to 70.

[0039] In addition, the L * The greater the difference between the L values, the easier it is to recognize the change in appearance due to the color of the adhesive film 1 for a metal terminal before and after heating. * is preferably about 10 or more, more preferably about 20 or more, and even more preferably about 30 or more, and the upper limit is usually about 90 or less. Preferred ranges include about 10 to 90, about 20 to 90, and about 30 to 90.

[0040] From the viewpoint of more suitably exhibiting the effects of the present disclosure, the average particle diameter of the temperature indicator is preferably about 300 nm or less, more preferably about 200 nm or less, and even more preferably about 100 nm or less, and is 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 to 300 nm, about 10 to 200 nm, about 10 to 100 nm, about 20 to 300 nm, about 20 to 200 nm, about 20 to 100 nm, about 30 to 300 nm, about 30 to 200 nm, about 30 to 100 nm, about 50 to 300 nm, about 50 to 200 nm, and about 50 to 100 nm. The average particle diameter of the temperature indicator is the median diameter measured using a laser diffraction / scattering particle size distribution measuring device.

[0041] From the viewpoint of more suitably exerting the effects of the present disclosure, the content of the temperature indicator 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 preferably about 0.01% by mass or more, more preferably about 0.1% by mass or more. 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 contained in the thermochromic layer include polyolefin resins, polyamide resins, polyester resins, epoxy resins, acrylic resins, fluororesins, silicone resins, phenolic resins, polyetherimides, polyimides, polycarbonates, and mixtures or copolymers thereof, among which polyolefin resins are particularly preferred. Examples of polyolefin resins include polyolefins and acid-modified polyolefins.

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

[0044] The thermochromic layer may contain only one type of resin, or two or more types. From the viewpoint of film-forming properties, the resin of the thermochromic layer is preferably a blend polymer combining two or more resin components. When using a blend polymer, for example, in the case of a thermochromic layer containing acid-modified polypropylene, it is preferable that the acid-modified polypropylene be the main component (50% by mass or more of a component), with 50% by mass or less of other resins (preferably polyethylene from the viewpoint of improving flexibility). Furthermore, in the case of a thermochromic layer containing polypropylene, it is preferable that the polypropylene be the main component (50% by mass or more of a component), with 50% by mass or less of 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 acid-modified polypropylene or polypropylene alone as the resin.

[0045] The thermochromic layer preferably contains an acid-modified polyolefin because it has excellent adhesion to the metal terminal. From the viewpoint of more suitably exhibiting the effects of the present disclosure, the thermochromic layer is preferably formed of an acid-modified polyolefin containing a temperature indicator. That is, the thermochromic layer can be suitably constituted by an acid-modified polyolefin film containing a temperature indicator.

[0046] The acid-modified polyolefin is not particularly limited as long as it is an acid-modified polyolefin, but preferred examples include polyolefins graft-modified with an unsaturated carboxylic acid or an anhydride thereof.

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

[0048] The acid-modified polyolefin may be a cyclic polyolefin. For example, a carboxylic acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a cyclic polyolefin by substituting an α,β-unsaturated carboxylic acid or an anhydride thereof for some of the monomers constituting the cyclic polyolefin, or by block polymerizing or graft polymerizing an α,β-unsaturated carboxylic acid or an anhydride thereof with a cyclic polyolefin.

[0049] The acid-modified cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefin constituting the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of the cyclic monomer constituting the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, preferred are cyclic alkenes, and more preferred are norbornene. Another example of the constituting monomer is styrene.

[0050] Examples of carboxylic acids or anhydrides thereof used for acid modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride, etc. When the thermochromic layer is analyzed by infrared spectroscopy, it is preferable that a peak derived from maleic anhydride is detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak derived from maleic anhydride is detected at a wave number of 1760 cm. -1 Nearby and wave number 1780 cm -1 A peak derived from maleic anhydride is detected around . If the thermochromic layer is a layer composed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride will be detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak will be small and may not be detected. In such cases, analysis can be performed by nuclear magnetic resonance spectroscopy.

[0051] In addition to the temperature indicator and resin, the thermochromic layer may further contain known additives such as fillers, as needed, to the extent that the effects of the present disclosure are not impaired.

[0052] For example, the thermochromic layer may contain a filler as needed. When the thermochromic layer contains a filler, the filler functions as a spacer, effectively suppressing short circuits between the metal terminal 2 and the barrier layer 33 of the electrical storage device exterior material 3. The particle size of the filler may be about 0.1 to 35 μm, preferably about 5.0 to 30 μm, and more preferably about 10 to 25 μm. The content of the filler may be about 5 to 30 parts by mass, more preferably about 10 to 20 parts by mass, per 100 parts by mass of the resin component that forms the thermochromic layer.

[0053] The filler can be either inorganic or organic. 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, cross-linked polymethyl methacrylates, and cross-linked polyethylenes. From the viewpoints of shape stability, rigidity, and content resistance, aluminum oxide, silica, fluororesins, acrylic resins, and benzoguanamine-formaldehyde condensates are preferred, with spherical aluminum oxide and silica being particularly preferred. The filler can be mixed into the resin component that forms the thermochromic layer by melt-blending the two components in advance using a Banbury mixer or the like to form a masterbatch and then mixing the masterbatch in a predetermined ratio, or by directly mixing the filler with the resin component.

[0054] When adding a filler to the thermochromic layer, a temperature indicator and a pigment may be added to the thermochromic layer, but from the viewpoint of not impairing the thermal fusion 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. described below).

[0055] From the viewpoint of more suitably achieving the effects of the present disclosure, the melting peak temperature of the thermochromic layer is preferably 110° C. or higher, more preferably about 120° C. or higher, and even more preferably about 130° C. or higher. From the same 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. Preferred ranges of the melting peak temperature include about 110 to 200°C, about 110 to 190°C, about 110 to 180°C, about 110 to 175°C, about 110 to 170°C, about 120 to 200°C, about 120 to 190°C, about 120 to 180°C, about 120 to 175°C, about 120 to 170°C, about 130 to 200°C, about 130 to 190°C, about 130 to 180°C, about 130 to 175°C, and about 130 to 170°C. In the present disclosure, the method for measuring the melting peak temperature is as follows.

[0056] <Measurement of Melting Peak Temperature> The melting peak temperature of each measurement sample is measured in accordance with the provisions of JIS K7121:2012 (Method for measuring transition temperatures of plastics (JIS K7121:1987 Supplement 1)). The measurement is carried out using a differential scanning calorimeter (DSC, for example, a differential scanning calorimeter Q200 manufactured by TA Instruments). The measurement 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, and then held at 210°C for 10 minutes. Next, the temperature is lowered from 210°C to -50°C at a heating rate of 10°C / min and held for 15 minutes. Furthermore, the temperature is raised 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 flow rate of nitrogen gas is 50 ml / min. By the above procedure, the melting peak temperature P (°C) measured the first time and the melting peak temperature Q (°C) measured the second time are determined. The value of the melting peak temperature P (°C) measured the first time by the above procedure is adopted.

[0057] When the adhesive film 1 for a metal terminal of the present disclosure is configured with a single layer of a thermochromic layer, the total thickness of the adhesive film 1 for a metal terminal, which will be described later, corresponds to the thickness of the thermochromic layer.

[0058] When the adhesive film 1 for metal terminals of the present disclosure is composed of multiple layers, from the viewpoint of more optimally achieving the effects of the present 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 preferably about 200 μm or less, more preferably about 150 μm or less, even more preferably about 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. Note that when the adhesive film 1 for metal terminals of the present disclosure contains multiple thermochromic layers, it is preferable that the thickness of each thermochromic layer be the thickness described above.

[0059] Furthermore, when the adhesive film for metal terminal 1 of the present disclosure has a thermochromic layer as the first resin layer 12a, from the viewpoint of more suitably achieving the effects of the present 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 is preferably about 200 μm or less, more preferably about 150 μm or less, 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 for metal terminal 1 of the present disclosure has a thermochromic layer as the second resin layer 12b, from the viewpoint of more suitably achieving the effects of the present 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 is preferably about 200 μm or less, more preferably about 150 μm or less, 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 for metal terminal 1 of the present disclosure has a thermochromic layer as the intermediate layer 11, from the viewpoint of more suitably achieving the effects of the present 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 is preferably about 200 μm or less, more preferably about 150 μm or less, 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.

[0062] As described above, the adhesive film 1 for a metal terminal of the present 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 Fig. 6, for example. In the adhesive film 1 for a metal terminal of the present disclosure, in this configuration, the first resin layer 12a is disposed on the metal terminal 2 side, and the second resin layer 12b is disposed on the electrical storage device sheath 3 side. 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 of a thermochromic layer, or may be formed of a resin layer B different from the thermochromic layer (i.e., the resin layer B is a resin layer that does not contain a temperature indicator).

[0064] The intermediate layer 11 may also be formed from a thermochromic layer, or may be formed from a resin layer B different from the thermochromic layer.

[0065] [Resin Layer B] Resin layer B is a resin layer different from the thermochromic layer (i.e., resin layer B can be said to be a non-thermochromic layer that does not thermochromic at the temperature at which the thermochromic layer thermochromic changes, for example, a resin layer that does not contain a temperature indicator).

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

[0067] The resin contained in the resin layer B may be only one type, or may be two or more types. From the viewpoint of film formability, the resin of the resin layer B is preferably a blend polymer combining two or more resin components. When using a blend polymer, for example, in the case of a resin layer B containing acid-modified polypropylene, it is preferable that the acid-modified polypropylene be the main component (a component of 50% by mass or more), and 50% by mass or less of another resin (preferably polyethylene from the viewpoint of improving flexibility). Furthermore, in the case of a resin layer B containing polypropylene, it is preferable that the polypropylene be the main component (a component of 50% by mass or more), and 50% by mass or less of another resin (preferably polyethylene from the viewpoint of improving flexibility). On the other hand, from the viewpoint of the electrolyte resistance of the resin layer B, the resin layer B containing acid-modified polypropylene preferably contains acid-modified polypropylene alone as the resin, and the resin layer B containing polypropylene preferably contains 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. Preferred ranges of the melting peak temperature include about 110 to 200 ° C., about 110 to 190 ° C., about 110 to 180 ° C., about 110 to 175 ° C., about 110 to 170 ° C., about 120 to 200 ° C., about 120 to 190 ° C., about 120 to 180 ° C., about 120 to 175 ° C., about 120 to 170 ° C., about 130 to 200 ° C., about 130 to 190 ° C., about 130 to 180 ° C., about 130 to 175 ° C., and about 130 to 170 ° C.

[0069] Furthermore, when the adhesive film for metal terminal 1 of the present disclosure has a resin layer B as the first resin layer 12a, from the viewpoint of more suitably exhibiting the effects of the present 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 is preferably about 200 μm or less, more preferably about 150 μm or less, 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 for metal terminal 1 of the present disclosure has a resin layer B as the second resin layer 12b, from the viewpoint of more suitably achieving the effects of the present 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 is 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 for metal terminal 1 of the present disclosure has a resin layer B as the intermediate layer 11, from the viewpoint of more suitably achieving the effects of the present 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 is 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] Like the thermochromic layer, the resin layer B may contain known additives (pigments, fillers, etc.). For example, the resin layer B may contain a pigment. Various inorganic pigments can be used as the pigment. Specific examples of pigments include carbon (carbon, graphite), which is listed as an example of a filler. Carbon (carbon, graphite) is a material commonly used inside electricity storage devices and is unlikely to leach into the electrolyte. Furthermore, the coloring effect is significant, and a sufficient coloring effect can be obtained with an amount added that does not impair adhesion. Furthermore, the additive does not melt due to heat, and the apparent melt viscosity of the added resin can be increased. Furthermore, the additive prevents the pressurized portion from becoming thin during thermal bonding (heat sealing), thereby providing excellent sealing between the electricity storage device exterior material and the metal terminal. Furthermore, the resin layer B may contain a filler, for example. The type and amount of the filler are the same as those for the thermochromic layer.

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

[0074] From the viewpoint of more suitably achieving the effects of the present 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. The total thickness of the adhesive film 1 for metal terminals of the present 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 the present 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 the present disclosure preferably has fine irregularities on at least one surface of the outermost layer. This can further improve adhesion to the heat-sealable resin layer 35 of the exterior packaging material 3 for an electrical storage device or the metal terminal 2. 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 shaping the film by contacting it with a cooling roll having an irregular surface. The fine irregularities preferably have a ten-point average roughness of the surface of the outermost layer of at least about 0.1 μm, more preferably at least about 0.2 μm, and also preferably at most about 35 μm, more preferably at most about 10 μm. Preferred ranges include 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 is a value measured in accordance with the method specified in JIS B0601:1994 using a laser microscope VK-9710 manufactured by Keyence Corporation under measurement conditions of a 50x objective lens and no cutoff.

[0076] The adhesive film for metal terminal 1 of the present disclosure is preferably formed from a polyolefin resin. For example, the resin components contained in the adhesive film for metal terminal 1 of the present disclosure are preferably only an acid-modified polyolefin or only an acid-modified polyolefin and a polyolefin. The preferred acid-modified polyolefin and polyolefin are as described in the thermochromic layer and resin layer B.

[0077] The adhesive film 1 for metal terminal of the present disclosure is preferably composed of a laminate including, in this order, a first resin layer 12 a, an intermediate layer 11, and a second resin layer 12 b. Hereinafter, a preferred embodiment of the adhesive film 1 for metal terminal of the present disclosure will be described in detail, taking as an example a case where the adhesive film 1 for metal terminal of the present disclosure is composed of a laminate including, in this order, at least a first resin layer 12 a, an intermediate layer 11, and a second resin layer 12 b.

[0078] When the adhesive film 1 for metal terminals of the present disclosure is placed between the metal terminal 2 of the electricity storage device 10 and the exterior material 3 for an electricity storage device, the surface of the metal terminal 2 made of metal and the heat-sealable resin layer 35 (a layer formed of a heat-sealable resin such as polyolefin) of the exterior material 3 for an electricity storage device are bonded via the adhesive film 1 for metal terminals. The first resin layer 12a of the adhesive film 1 for metal terminals is placed on the metal terminal 2 side, and the second resin layer 12b is placed on the exterior material 3 for an electricity storage device, 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-sealable resin layer 35 of the exterior material 3 for an electricity storage device.

[0079] [First resin layer 12a and second resin layer 12b] As shown in Fig. 6, the adhesive film 1 for a metal terminal 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 disposed on the metal terminal 2 side. The second resin layer 12b is disposed on the exterior material 3 for an electrical storage device. In the adhesive film 1 for a metal terminal 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 the present disclosure, at least one of the first resin layer 12a, the intermediate layer 11, and the second resin layer 12b is formed of the above-mentioned thermochromic layer.

[0081] As described above, the first resin layer 12a and the second resin layer 12b each preferably contain a polyolefin-based resin (i.e., have a polyolefin skeleton), preferably contain a polyolefin, and more preferably be a layer formed of a polyolefin. The first resin layer 12a preferably contains a polyolefin or an acid-modified polyolefin among polyolefin-based resins, more preferably contain an acid-modified polyolefin, and more preferably be a layer formed of an acid-modified polyolefin film. The polyolefin-based resin is preferably a polypropylene-based resin. The second resin layer 12b preferably contains a polyolefin or an acid-modified polyolefin among polyolefin-based resins, more preferably contain a polyolefin, and more preferably be a layer formed of a polyolefin film. The polyolefin-based resin is preferably a polypropylene-based 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 of the melting peak temperature include about 110 to 200°C, about 110 to 190°C, about 110 to 180°C, about 110 to 175°C, about 110 to 170°C, about 120 to 200°C, about 120 to 190°C, about 120 to 180°C, about 120 to 175°C, about 120 to 170°C, about 130 to 200°C, about 130 to 190°C, about 130 to 180°C, about 130 to 175°C, and about 130 to 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 of the melting peak temperature include about 110 to 200°C, about 110 to 190°C, about 110 to 180°C, about 110 to 175°C, about 110 to 170°C, about 120 to 200°C, about 120 to 190°C, about 120 to 180°C, about 120 to 175°C, about 120 to 170°C, about 130 to 200°C, about 130 to 190°C, about 130 to 180°C, about 130 to 175°C, and about 130 to 170°C.

[0084] From the viewpoint of more suitably achieving the effects of the present 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 is preferably about 200 μm or less, more preferably about 150 μm or less, 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 suitably achieving the effects of the present disclosure, the thickness of the second resin layer 12b is preferably about 20 μm or more, more preferably about 30 μm or more, and even more preferably about 40 μm or more, and is preferably about 200 μm or less, more preferably about 150 μm or less, and even more preferably about 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] [Intermediate Layer 11 ] In the adhesive film for a metal terminal 1 , the intermediate layer 11 is a layer that functions as a support for the adhesive film for a metal terminal 1 .

[0087] The intermediate layer 11 may be formed from the thermochromic layer described above, or may be formed from the resin layer B described above.

[0088] The material forming the intermediate layer 11 is not particularly limited. Examples of materials that can be used to form the intermediate layer 11 include polyolefin resins, polyamide resins, polyester resins, epoxy resins, acrylic resins, fluororesins, silicone resins, phenolic resins, polyetherimides, polyimides, polycarbonates, and mixtures or copolymers thereof. Among these, polyolefin resins are particularly preferred. That is, 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 determined by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like.

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

[0090] Specific examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (where I represents isophthalic acid and T represents terephthalic acid) containing structural units derived from terephthalic acid and / or isophthalic acid; and aromatic polyamides such as polymetaxylylene adipamide (MXD6); alicyclic polyamides such as polyaminomethylcyclohexyl adipamide (PACM6); polyamides copolymerized with a lactam component or an isocyanate component such as 4,4'-diphenylmethane-diisocyanate; polyesteramide copolymers and polyetheresteramide copolymers, which are copolymers of copolymerized polyamides with polyesters or polyalkylene ether glycols; and copolymers thereof. These polyamides may be used alone or in combination of two or more.

[0091] Specific examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, copolymer polyesters whose repeating units are primarily ethylene terephthalate, copolymer polyesters whose repeating units are primarily butylene terephthalate, etc. Specific examples of copolymer polyesters whose repeating units are primarily ethylene terephthalate include copolymer polyesters in which ethylene terephthalate is the main repeating unit and is polymerized with ethylene isophthalate (hereinafter abbreviated as polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / isophthalate), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate), polyethylene (terephthalate / decanedicarboxylate), etc. Specific examples of copolymer polyesters containing butylene terephthalate as the main repeating unit include copolymer polyesters in which butylene terephthalate is the main repeating unit and is polymerized with butylene isophthalate (hereinafter abbreviated as polybutylene (terephthalate / isophthalate)), polybutylene (terephthalate / adipate), polybutylene (terephthalate / sebacate), polybutylene (terephthalate / decanedicarboxylate), polybutylene naphthalate, etc. These polyesters may be used alone or in combination of two or more.

[0092] Alternatively, the intermediate layer 11 may be formed of 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 above-mentioned polyolefin resin, polyamide resin, or the like.

[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 the same 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 of the melting peak temperature include about 110 to 300°C, about 110 to 290°C, about 110 to 280°C, about 110 to 275°C, about 110 to 270°C, about 120 to 300°C, about 120 to 290°C, about 120 to 280°C, about 120 to 275°C, about 120 to 270°C, about 130 to 300°C, about 130 to 290°C, about 130 to 280°C, about 130 to 275°C, and about 130 to 270°C.

[0094] The intermediate layer 11 may be a single layer or multiple layers.

[0095] Furthermore, by blending a colorant into the intermediate layer 11, the intermediate layer 11 can be made a layer containing a colorant. Furthermore, light transmittance can be adjusted by selecting a resin with low transparency. When the intermediate layer 11 is a film, a colored film or a film with low transparency can be used. When the intermediate layer 11 is a nonwoven fabric, a nonwoven fabric using fibers or a binder containing a colorant, or a nonwoven fabric with low transparency can be used.

[0096] When the intermediate layer 11 is made of a resin film, the surface of the intermediate layer 11 may be subjected to a known adhesion-facilitating treatment such as corona discharge treatment, ozone treatment, or plasma treatment, if necessary.

[0097] Furthermore, from the viewpoint of more suitably achieving the effects of the present 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 is preferably about 200 μm or less, more preferably about 150 μm or less, 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 the same 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 not less than about 0.3, more preferably not less than about 0.4, and is preferably not more than about 1.0, more preferably not more than about 0.8, and 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, if the total thickness of the adhesive film 1 for metal terminals is 100%, the proportion of the total thickness of the first resin layer 12a and the second resin layer 12b is preferably approximately 30 to 80%, and more preferably approximately 50 to 70%.

[0100] The adhesive film for metal terminal 1 of the present disclosure can be produced, for example, by laminating a first resin layer 12a and a second resin layer 12b, respectively, on both surfaces of an intermediate layer 11. The intermediate layer 11 can be laminated with the first resin layer 12a and the second resin layer 12b by a known method such as extrusion lamination, T-die lamination, inflation lamination, or thermal lamination.

[0101] The method for interposing the adhesive film 1 for a metal terminal between the metal terminal 2 and the exterior material 3 for an electricity storage device is not particularly limited, and for example, as shown in Figures 1 to 3, the adhesive film 1 for a metal terminal may be wrapped around the metal terminal 2 in the portion where the metal terminal 2 is sandwiched by the exterior material 3 for an electricity storage device. Furthermore, although not shown, in the portion where the metal terminal 2 is sandwiched by the exterior material 3 for an electricity storage device, the adhesive film 1 for a metal terminal may be arranged on both sides of the metal terminal 2 so as to cross the two metal terminals 2.

[0102] The adhesion promoter layer 13 is a layer provided as needed for the purpose of firmly adhering the intermediate layer 11 to the first resin layer 12a and the intermediate layer 11 to the second resin layer 12b (see FIG. 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 indicator.

[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. From the viewpoint of obtaining strong adhesive strength, it is preferable to form the layer using an isocyanate-based adhesion promoter. Among these, isocyanate-based adhesion promoters, those containing an isocyanate component selected from triisocyanate monomer and polymeric MDI, have excellent laminate strength and show little deterioration in laminate strength at high temperatures. It is particularly preferable to form the adhesive layer using an adhesion promoter made of triphenylmethane-4,4',4"-triisocyanate, which is a triisocyanate monomer, or polymethylene polyphenyl polyisocyanate, which is a polymeric MDI (NCO content of about 30%, viscosity of 200 to 700 mPa·s). It is also preferable to form the adhesive layer using tris(p-isocyanatephenyl)thiophosphate, which is a triisocyanate monomer, or a two-component curing adhesion promoter that uses a polyethyleneimine-based compound as the main component and polycarbodiimide as the crosslinking agent.

[0104] The adhesion promoter layer 13 can be formed by coating and drying using a known coating method such as bar coating, roll coating, or gravure coating. The amount of the adhesion promoter to be applied is 20 to 100 mg / m when the adhesion promoter is made of triisocyanate. 2 about 40 to 60 mg / m 2 In the case of an adhesion promoter made of polymeric MDI, the concentration is 40 to 150 mg / m 2 about 60 to 100 mg / m 2 In the case of a two-component curing adhesion promoter that uses polyethyleneimine as the main component and polycarbodiimide as the crosslinking agent, the adhesive strength is about 5 to 50 mg / m 2 about 10 to 30 mg / m 2 The triisocyanate monomer is a monomer having three isocyanate groups in one molecule, and polymeric MDI is a mixture of MDI and MDI oligomers formed by polymerizing MDI, and is represented by the following formula:

[0105]

[0106] In order to more suitably achieve 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 that the second resin layer 12b and the intermediate layer 11 are in contact with each other.

[0107] Specific examples of preferred laminated structures for the adhesive film 1 for metal terminals of the present disclosure include a three-layer structure in which a first resin layer formed from acid-modified polypropylene, an intermediate layer (substrate) formed from polypropylene, and a second resin layer formed from acid-modified polypropylene are laminated in this order; and a three-layer structure in which a first resin layer formed from acid-modified polypropylene, an intermediate layer (substrate) formed from polypropylene, and a second resin layer formed from polypropylene are laminated in this order. Of these, the latter three-layer structure is particularly preferred in terms of adhesion between the heat-sealable resin layer 35 of the exterior material 3 for an electrical storage device and the second resin layer 12b.

[0108] [Metal Terminal 2] The adhesive film 1 for metal terminals of the present disclosure is used by being interposed between the metal terminal 2 and the exterior material 3 for an electricity storage device. The metal terminal 2 (tab) is a conductive member electrically connected to an electrode (positive electrode or negative electrode) of the electricity storage device element 4, and is made of a metal material. The metal material constituting the metal terminal 2 is not particularly limited, and examples include aluminum, nickel, copper, etc. For example, the metal terminal 2 connected to the positive electrode of a lithium ion electricity storage device is usually made of aluminum, etc. Furthermore, the metal terminal 2 connected to the negative electrode of a lithium ion electricity storage device is usually made of copper, nickel, etc.

[0109] From the viewpoint of enhancing electrolyte resistance, it is preferable that the surface of the metal terminal 2 is subjected to a chemical conversion treatment. For example, when the metal terminal 2 is formed of aluminum, specific examples of the chemical conversion treatment include known methods for forming a corrosion-resistant film using phosphates, chromates, fluorides, triazine thiol compounds, etc. Among the methods for forming a corrosion-resistant film, a chromate phosphate treatment using a compound consisting of three components: a phenolic resin, a chromium (III) fluoride compound, and phosphoric acid is preferred.

[0110] The size of the metal terminal 2 may be set appropriately depending on the size of the electricity storage device to be 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] [Electricity Storage Device Exterior Material 3] The electricity storage device exterior material 3 may have a laminate structure made of a laminate having at least a base material layer 31, a barrier layer 33, and a heat-sealable resin layer 35 in this order. Fig. 8 shows an example of the cross-sectional structure of the electricity storage device exterior material 3, in which the base material layer 31, an optional adhesive layer 32, a barrier layer 33, an optional adhesive layer 34, and a heat-sealable resin layer 35 are laminated in this order. In the electricity storage device exterior material 3, the base material layer 31 is the outer layer side, and the heat-sealable resin layer 35 is the innermost layer. When assembling the electricity storage device, the heat-sealable resin layers 35 located on the peripheries of the electricity storage device elements 4 are brought into contact with each other and heat-sealed to seal the electricity storage device elements 4. 1 to 3 show an electricity storage device 10 using an embossed-type electricity storage device exterior material 3 formed by embossing or the like, but the electricity storage device exterior material 3 may also be an unformed pouch-type. Pouch types include three-sided seal, four-sided seal, and pillow type, and any of these types may be used.

[0112] The thickness of the laminate constituting the electrical storage device packaging material 3 is not particularly limited, but the upper limit, from the viewpoint of cost reduction, energy density improvement, etc., is, for example, 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, or about 120 μm or less; and the lower limit, from the viewpoint of maintaining the function of the electrical storage device packaging material 3 to protect the electrical storage device elements 4, is preferably about 35 μm or more, about 45 μm or more, about 60 μm or more, or about 80 μm or more; preferred ranges are, for example, about 35 to 190 μm, about 35 to 180 μm, or 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 about 60 to 160 μm, about 60 to 155 μm, about 60 to 140 μm, about 60 to 130 μm, about 60 to 120 μm, about 80 to 190 μm, about 80 to 180 μm, about 80 to 160 μm, about 80 to 155 μm, about 80 to 140 μm, about 80 to 130 μm, and about 80 to 120 μm.

[0113] (Substrate Layer 31) In the packaging material for an electricity storage device 3, the substrate layer 31 is a layer that functions as a substrate of the packaging material for an electricity storage device, and is a layer that forms the outermost layer side.

[0114] The material for forming the substrate layer 31 is not particularly limited, as long as it has insulating properties. Examples of materials for forming the substrate layer 31 include polyester, polyamide, epoxy, acrylic resin, fluororesin, polyurethane, silicone resin, phenol, polyetherimide, polyimide, and mixtures or copolymers thereof. Polyesters such as polyethylene terephthalate and polybutylene terephthalate have the advantage of being highly resistant to electrolyte and being less susceptible to whitening due to adhesion of electrolyte, and are therefore preferably used as materials for forming the substrate layer 31. Furthermore, polyamide film has excellent stretchability and can prevent whitening due to resin cracking of the substrate layer 31 during molding, and is therefore preferably used as materials for forming the substrate layer 31.

[0115] The base layer 31 may be formed of a uniaxially or biaxially stretched resin film or an unstretched resin film. Among them, a uniaxially or biaxially stretched resin film, especially a biaxially stretched resin film, is preferably used as the base layer 31 because its heat resistance is improved by oriented crystallization.

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

[0117] The base material layer 31 may be formed by laminating resin films made of different materials to improve pinhole resistance and insulation when used as a package for an electricity storage device. Specific examples include a multilayer structure in which a polyester film and a nylon film are laminated together, or a multilayer structure in which a biaxially oriented polyester film and a biaxially oriented nylon film are laminated together. When the base material layer 31 has a multilayer structure, the resin films may be bonded together via an adhesive, or may be laminated together directly without an adhesive. When the resin films are bonded together without an adhesive, examples of the methods that can be used include a coextrusion method, a sand lamination method, a thermal lamination method, and the like, in which the resin films are bonded together in a hot-melt state.

[0118] The base layer 31 may be made low-friction to improve formability. When making the base layer 31 low-friction, the coefficient of friction of the surface is not particularly limited, but may be, for example, 1.0 or less. To make the base layer 31 low-friction, for example, matte treatment, formation of a thin film layer of a slip agent, or a combination thereof may be used.

[0119] The thickness of the base layer 31 is, for example, about 10 to 50 μm, and preferably about 15 to 30 μm.

[0120] (Adhesive Layer 32) In the packaging material 3 for an electricity storage device, the adhesive layer 32 is a layer that is disposed on the base material layer 31 as necessary in order to impart 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 of an adhesive capable of bonding the base material 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. The bonding mechanism of the adhesive used to form the adhesive layer 32 is not particularly limited, and may be any of a chemical reaction type, a solvent volatilization type, a hot melt type, a hot pressure type, or the like.

[0122] The resin component of the adhesive that can be used to form the adhesive layer 32 is preferably a polyurethane-based two-component curing adhesive; polyamide, polyester, or a blend resin of these with modified polyolefin, from the viewpoint of having excellent ductility, durability under high humidity conditions, yellowing prevention, and thermal degradation prevention during heat sealing, and of effectively suppressing a decrease in the laminate strength between the base material layer 31 and the barrier layer 33 and preventing delamination.

[0123] Furthermore, the adhesive layer 32 may be multi-layered with different adhesive components. When the adhesive layer 32 is multi-layered with different adhesive components, it is preferable to select a resin that has excellent adhesion to the base material layer 31 as the adhesive component disposed on the base material layer 31 side, and an adhesive component that has excellent adhesion to the barrier layer 33 as the adhesive component disposed on the barrier layer 33 side, from the viewpoint of improving the laminate strength between the base material layer 31 and the barrier layer 33. When the adhesive layer 32 is multi-layered with different adhesive components, specifically, the adhesive component disposed on the barrier layer 33 side is preferably an acid-modified polyolefin, a metal-modified polyolefin, a mixed resin of polyester and acid-modified polyolefin, a resin containing a copolymer polyester, or the like.

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

[0125] (Barrier Layer 33) In the electrical storage device packaging material 3, the barrier layer 33 is a layer that not only improves the strength of the electrical storage device packaging material but also has the function of preventing water vapor, oxygen, light, and the like from penetrating into the electrical storage device. The barrier layer 33 is preferably a metal layer, i.e., a layer formed of a metal. Specific examples of metals constituting the barrier layer 33 include aluminum, stainless steel, and titanium, and aluminum is preferred. The barrier layer 33 can be formed, for example, from a metal foil, a metal vapor deposition film, an inorganic oxide vapor deposition film, a carbon-containing inorganic oxide vapor deposition film, or a film provided with any of these vapor deposition films. It is preferably formed from a metal foil, and more preferably from an aluminum foil. From the viewpoint of preventing the occurrence of wrinkles or pinholes in the barrier layer 33 during the production of the exterior material for an electricity storage device, it is more preferable that the barrier layer be formed from a 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] The thickness of the barrier layer 33 is preferably about 10 to 200 μm, more preferably about 20 to 100 μm, from the viewpoint of making the packaging material for an electricity storage device thinner while making it less likely to develop pinholes during molding.

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

[0128] (Adhesive Layer 34) In the packaging material 3 for an electricity storage device, the adhesive layer 34 is a layer that is provided as needed between the barrier layer 33 and the heat-sealable resin layer 35 in order to firmly bond the heat-sealable resin layer 35.

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

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

[0131] (Heat-sealable resin layer 35) In the packaging material 3 for an electricity storage device, the heat-sealable resin layer 35 corresponds to the innermost layer, and is a layer that seals the electricity storage device elements by heat-sealing the heat-sealable resin layers together when assembling the electricity storage device.

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

[0133] Specific examples of the polyolefin include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); 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, and examples of the olefin constituting the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of the cyclic monomer constituting the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, preferred are cyclic alkenes, and more preferred are norbornene. Another example of the constituting monomer is styrene.

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

[0136] The heat-sealable resin layer 35 may be formed of a single resin component alone, or may be formed of a blend polymer of two or more resin components. The heat-sealable resin layer 35 may be formed of only one layer, or may be formed of two or more layers of the same or different resin components. It is particularly preferable that the second resin layer 12b and the heat-sealable resin layer 35 use the same resin, since this improves the adhesion between these layers.

[0137] The thickness of the heat-sealable resin layer 35 is not particularly limited, but may be about 2 to 2000 μm, preferably about 5 to 1000 μm, and more preferably about 10 to 500 μm. The thickness of the heat-sealable resin layer 35 is, for example, about 100 μm or less, preferably about 85 μm or less, and more preferably about 15 to 85 μm. For example, when the thickness of the adhesive layer 34 described below is 10 μm or more, the thickness of the heat-sealable resin layer 35 is preferably about 85 μm or less, and more preferably about 15 to 45 μm. For example, when the thickness of the adhesive layer 34 described above is less than 10 μm or when the adhesive layer 34 is not provided, the thickness of the heat-sealable resin layer 35 is preferably about 20 μm or more, and more preferably about 35 to 85 μm.

[0138] The electrical storage device exterior material of the present disclosure can also be in the form of a kit including an electrical storage device exterior material for use in an electrical storage device and the adhesive film for a metal terminal of the present disclosure. In this case, the applicable electrical storage device also includes at least an electrical storage device element including a positive electrode, a negative electrode, and an electrolyte, an electrical storage device exterior material that encapsulates the electrical storage device element, and metal terminals electrically connected to the positive electrode and the negative electrode and protruding outside the electrical storage device exterior material. The kit of the present disclosure is used such that, during use, the adhesive film for a metal terminal of the present disclosure is interposed between the metal terminal and the electrical storage device exterior material.

[0139] 2. Electricity Storage Device The electricity storage device 10 of the present disclosure comprises at least an electricity storage device element 4 including a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device 3 that seals the electricity storage device element 4, and metal terminals 2 that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude to the outside of the exterior material for an electricity storage device 3. The electricity storage device 10 of the present disclosure is characterized in that an adhesive film for a metal terminal 1 of the present disclosure is interposed between the metal terminal 2 and the exterior material for an electricity storage device 3. In other words, the electricity storage device 10 of the present disclosure can be manufactured by a method that includes a step of interposing an adhesive film for a metal terminal 1 of the present disclosure between the metal terminal 2 and the exterior material for an electricity storage device 3.

[0140] Specifically, an electricity storage device element 4 including at least a positive electrode, a negative electrode, and an electrolyte is enclosed in an electricity storage device exterior material 3, with metal terminals 2 connected to the positive and negative electrodes protruding outward, and the adhesive film 1 for metal terminals of the present disclosure is interposed between the metal terminals 2 and the heat-sealable resin layer 35, and the electricity storage device element 4 is covered around its periphery so as to form a flange portion (a region where the heat-sealable resin layers 35 contact each other, i.e., the peripheral portion 3a of the electricity storage device exterior material 3), and the heat-sealable resin layers 35 of the flange portion are heat-sealed to provide an electricity storage device 10 using the electricity storage device exterior material 3. When the electricity storage device element 4 is housed using the electricity storage device exterior material 3, the heat-sealable resin layer 35 of the electricity storage device exterior material 3 is used so that it faces inside (the surface in contact with the electricity storage device element 4).

[0141] The exterior material for an electricity storage device of the present disclosure can be suitably used for electricity storage devices such as batteries (including condensers, capacitors, etc.). The exterior material for an electricity storage device of the present disclosure may be used for either a primary battery or a secondary battery, but is preferably used for a secondary battery. The type of secondary battery to which the exterior material for an electricity storage device of the present disclosure is applied is not particularly limited, and examples include lithium ion batteries, lithium ion polymer batteries, all-solid-state batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, condensers, and capacitors. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are suitable applications for the exterior material for an electricity storage device of the present disclosure.

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

[0143] <Production of adhesive film for metal terminal> Example 1 Using an extruder and a T-die casting machine, a maleic anhydride-modified polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C., thickness 50 μm) was used as an intermediate layer on one side of the outer casing. The second resin layer on the outer casing was a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124 ° C.), and the other side was used as a first resin layer (thermochromic layer) on the metal terminal side. Titanium nitride (average particle diameter 70 nm) was used as a thermochromic material. 0.1% by mass of maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140 ° C.) was extruded to a thickness of 50 μm, and 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) was laminated in this order to obtain an adhesive film (total thickness 150 μm). The adhesive film thus obtained had a black appearance due to the inclusion of black titanium nitride in the first resin layer (thermochromic layer), while the intermediate layer and second resin layer were colorless and transparent.

[0144] Example 2 Using an extruder and a T die-casting machine, on one side of the polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C., thickness 50 μm) as an intermediate layer, maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124 ° C.) as the second resin layer on the exterior material side, and on the other side, as the first resin layer (thermochromic layer) on the metal terminal side, titanium nitride (average particle diameter 70 nm) as a temperature indicator. 1.0 mass% of maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140 ° C.) was extruded to a thickness of 50 μm, and 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) was laminated in order to obtain an adhesive film (total thickness 150 μm). The adhesive film thus obtained had a black appearance due to the inclusion of black titanium nitride in the first resin layer (thermochromic layer), while the intermediate layer and second resin layer were colorless and transparent.

[0145] Example 3 Using an extruder and a T die-casting machine, a maleic anhydride-modified polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C., thickness 50 μm) was used as an intermediate layer on one side of the outer casing. The second resin layer on the outer casing side was a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124 ° C.), and the other side was used as a first resin layer (thermochromic layer) on the metal terminal side. Titanium nitride (average particle diameter 20 nm) as a temperature indicator. 1.0 mass% of maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140 ° C.) was extruded to a thickness of 50 μm, and 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) was laminated in this order to obtain an adhesive film (total thickness 150 μm). The adhesive film thus obtained had a black appearance due to the inclusion of black titanium nitride in the first resin layer (thermochromic layer), while the intermediate layer and second resin layer were colorless and transparent.

[0146] Example 4 Using an extruder and a T die-casting machine, on one side of the polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C., thickness 50 μm) as an intermediate layer, maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124 ° C.) as the second resin layer on the exterior material side, and on the other side, as the first resin layer (thermochromic layer) on the metal terminal side, titanium nitride (average particle diameter 50 nm) as a temperature indicator. Maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140 ° C.) containing 1.0% by mass was extruded to a thickness of 50 μm, and 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) was laminated in order to obtain an adhesive film (total thickness 150 μm). The adhesive film thus obtained had a black appearance due to the inclusion of black titanium nitride in the first resin layer (thermochromic layer), while the intermediate layer and second resin layer were colorless and transparent.

[0147] Example 5 Using an extruder and a T-die casting machine, a polypropylene intermediate layer (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50 μm) was formed on one side of a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) as a second resin layer on the exterior material side, and a thermochromic layer containing 10.0 mass% titanium nitride (average particle diameter 70 nm) as a temperature indicator was formed on the other side of a first resin layer (thermochromic layer) on the metal terminal side. Water-maleic acid-modified polypropylene (PPa layer, melting peak temperature 140 ° C) was extruded to a thickness of 50 μm, and a 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) was laminated in this order to obtain an adhesive film (total thickness 150 μm). The obtained adhesive film had a black appearance due to the inclusion of black titanium nitride in the first resin layer (thermochromic layer). The intermediate layer and second resin layer were colorless and transparent.

[0148] Example 6 Using an extruder and a T-die casting machine, a polypropylene intermediate layer (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50 μm) was formed on one side of a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) as a second resin layer on the exterior material side, and a thermochromic layer containing 0.01 mass% titanium nitride (average particle diameter 70 nm) as a temperature indicator was formed on the other side of a first resin layer (thermochromic layer) on the metal terminal side. Water-maleic acid-modified polypropylene (PPa layer, melting peak temperature 140 ° C) was extruded to a thickness of 50 μm, and a 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) was laminated in this order to obtain an adhesive film (total thickness 150 μm). The obtained adhesive film had a black appearance due to the inclusion of black titanium nitride in the first resin layer (thermochromic layer). The intermediate layer and second resin layer were colorless and transparent.

[0149] Example 7 Using an extruder and a T-die casting machine, a polypropylene intermediate layer (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50 μm) was formed on one side of a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) as a second resin layer on the exterior material side, and a thermochromic layer containing 50.0 mass% titanium nitride (average particle diameter 70 nm) as a temperature indicator was formed on the other side of the first resin layer (thermochromic layer) on the metal terminal side. Water-maleic acid-modified polypropylene (PPa layer, melting peak temperature 140 ° C) was extruded to a thickness of 50 μm, and a 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) was laminated in this order to obtain an adhesive film (total thickness 150 μm). The obtained adhesive film had a black appearance due to the inclusion of black titanium nitride in the first resin layer (thermochromic layer). The intermediate layer and second resin layer were colorless and transparent.

[0150] Comparative Example 1 Using an extruder and a T-die casting machine, a maleic anhydride-modified polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C., thickness 50 μm) was extruded on one side of a polypropylene intermediate layer (PP layer, homopolypropylene, melting peak temperature 163 ° C., thickness 50 μm) as a second resin layer on the exterior material side, and a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124 ° C.) containing 0.5% by mass of carbon black (average particle diameter 300 nm) as a first resin layer on the metal terminal side (PPa layer, melting peak temperature 140 ° C.) was extruded on the other side to a thickness of 50 μm, and 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) was obtained. The adhesive film obtained had a black appearance due to the inclusion of black carbon black in the first resin layer, while the intermediate layer and the second resin layer were colorless and transparent.

[0151] Comparative Example 2 Using an extruder and a T-die casting machine, a maleic anhydride-modified polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C, thickness 50 μm) was extruded on one side of a polypropylene intermediate layer (PP layer, homopolypropylene, melting peak temperature 163 ° C, thickness 50 μm) as the second resin layer on the exterior material side, and a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124 ° C) was extruded on the other side as the first resin layer on the metal terminal side, each to a thickness of 50 μm, and 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) was laminated in this order. The resulting adhesive film was colorless and transparent.

[0152] Comparative Example 3 Using an extruder and a T-die casting machine, a maleic anhydride-modified polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C, thickness 50 μm) was extruded on one side of a polypropylene intermediate layer (PP layer, homopolypropylene, melting peak temperature 163 ° C, thickness 50 μm) as the second resin layer on the exterior material side, and a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124 ° C) was extruded on the other side as the first resin layer on the metal terminal side, each to a thickness of 50 μm, and 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) was laminated in this order. The resulting adhesive film was colorless and transparent.

[0153] Comparative Example 4 Using an extruder and a T-die casting machine, a maleic anhydride-modified polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C., thickness 50 μm) was extruded onto one side of a polypropylene intermediate layer (PP layer, homopolypropylene, melting peak temperature 163 ° C., thickness 50 μm) as the second resin layer on the exterior material side, and a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124 ° C.) containing 1.0 mass% carbon black (average particle diameter 300 nm) as the first resin layer on the metal terminal side (PP layer, melting peak temperature 140 ° C.) were extruded onto the other side to a thickness of 50 μm, and 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 (PP layer, melting peak temperature 124 ° C., thickness 50 μm) was obtained. The adhesive film obtained had a black appearance due to the inclusion of black carbon black in the first resin layer, while the intermediate layer and the second resin layer were colorless and transparent.

[0154] <Measurement of Melting Peak Temperature> The melting peak temperature of the adhesive film is measured in accordance with the provisions of JIS K7121:2012 (Method for measuring transition temperature of plastics (JIS K7121:1987 Supplement 1)). The measurement was carried out using a differential scanning calorimeter (DSC, differential scanning calorimeter Q200 manufactured by TA Instruments). The measurement 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, and then held at 210°C for 10 minutes. Next, the temperature was lowered from 210°C to -50°C at a heating rate of 10°C / min and held for 15 minutes. Furthermore, the temperature was raised 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 flow rate of nitrogen gas was 50 ml / min. The melting peak temperature P (°C) measured the first time and the melting peak temperature Q (°C) measured the second time were determined by the above procedure. The melting peak temperature P (°C) measured the first time was used.

[0155] <L before and after heating of adhesive film *Measurement of Values> Aluminum (JIS H4160:1994 A8079H-O) measuring 50 mm in length, 45 mm in width, and 0.4 mm in thickness was prepared as a metal terminal. Two sheets of the adhesive film for metal terminals of the Examples and Comparative Examples were cut to a length of 45 mm and a width of 10 mm. Next, the adhesive film for metal terminals was sandwiched between the two adhesive films to obtain an adhesive film / metal terminal / adhesive film laminate. The metal terminals were laminated so that the longitudinal and lateral directions of the metal terminals were aligned with the width and length directions of the adhesive film for metal terminals, respectively, and the centers of the metal terminals and adhesive films for metal terminals were aligned. The resulting laminate was placed on a hot plate. The adhesive films were then heated under various heating conditions (heating temperatures of 280°C and 300°C, heating pressure of 0.25 MPa, and heating time of 16 seconds, respectively). Next, the surface of the adhesive film on the first resin layer side before and after heating was subjected to L * a * b * L in color space * The observation conditions of a spectrophotometer (CM-700d) manufactured by Konica Minolta, calibrated with a white calibration cap (CM-A177: manufactured by Konica Minolta), were set to 10°, an observation light source of F2, and SCI mode (JIS Z8722-2009). Next, the L * The measurement of the value was carried out under normal temperature and humidity. The measurement diameter was set to 8 mm. The results are shown in Table 1. In Table 1, L * The values ​​shown were measured values ​​rounded off to the first decimal place.

[0156] <Evaluation of Adhesion to Metal Terminal> The above-mentioned <L before and after heating of adhesive film> *In the measurement of adhesion values, adhesive films of Examples and Comparative Examples were prepared by heating and pressing 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 using the following method. The results are shown in Table 1. Note that when describing the size of rectangular strips of adhesive film, the terms "length" and "width" refer to the machine direction (MD) and the transverse direction (TD). Aluminum (JIS H4160:1994 A8079H-O) measuring 50 mm in length, 22.5 mm in width, and 0.4 mm in thickness was prepared as the metal terminal. 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 metal terminal / adhesive film laminate. The metal terminals were laminated so that the longitudinal and lateral directions of the metal terminals coincided with the longitudinal and lateral directions of the adhesive film for metal terminals, respectively, and so that the centers of the metal terminals and the adhesive film for metal terminals were aligned. The first resin layer of the adhesive film for metal terminals was 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 terminal facing the hot plate). A silicone sponge sheet was then 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 terminal. The heat-sealed laminate was then allowed to cool naturally to 25°C. Next, in a 25°C environment, the adhesive film for metal terminals was peeled from the metal terminal using a Tensilon universal material testing machine (RTG-1210, manufactured by A&D Co., Ltd.). The maximum strength at the time of peeling was defined as the adhesion strength (N / 15 mm) to the metal terminal. Note that this adhesion strength is a conversion value from the measurement results at a width of 10 mm to the measurement value at a width of 15 mm. The peel speed was 50 mm / min, the peel angle was 180°, and the distance between chucks was 30 mm, and the average value was measured three times. Note that the treatment of leaving the sample standing for 16 seconds in a heated and pressurized environment at a temperature of 200°C and a surface pressure of 0.25 MPa simulates the heat and pressure applied in the temporary bonding step and the main bonding step.(Evaluation criteria for adhesion at 280°C and 300°C) A: Adhesion strength is 40N / 15mm or more. B: Adhesion strength is less than 40N / 15mm.

[0157]

[0158] The adhesive films for metal terminals of Examples 1 to 7 have a thermochromic layer containing titanium nitride as a temperature indicator, and exhibit a temperature change resistance of L between 280°C and 320°C. * The value changed significantly, and it was possible to tell from the appearance that it had been heated to the specified temperature.

[0159] As described above, the present disclosure provides the following aspects of the invention. Item 1. An adhesive film for metal terminals, interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, the adhesive film for metal terminals comprising a thermochromic layer. Item 2. The adhesive film for metal terminals according to Item 1, wherein the thermochromic layer is formed from a resin composition containing a temperature indicator and a resin. Item 3. The adhesive film for metal terminals according to Item 2, wherein the temperature indicator contains an inorganic compound. Item 4. The adhesive film for metal terminals according to Item 2 or 3, wherein the temperature indicator has an average particle size of 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 temperature indicator in the thermochromic layer is 0.01 mass % or more and 50 mass % or less. Item 6. Item 7. The adhesive film for a metal terminal according to any one of Items 2 to 5, wherein the temperature indicator is titanium nitride. Item 8. The adhesive film for a metal terminal according to any one of Items 1 to 6, wherein the thermochromic layer has a polyolefin skeleton. Item 9. The adhesive film for a metal terminal according to any one of Items 1 to 7, wherein a peak derived from maleic anhydride is detected when the thermochromic layer is analyzed by infrared spectroscopy. Item 10. The thermochromic layer exhibits a peak derived from maleic anhydride when measured by the SCI method under the measurement conditions of a field of view of 10° and a light source F2. * a * b * L in color space *Item 10. The adhesive film for metal terminal according to any one of Items 1 to 8, wherein the value of the adhesive film for metal terminal is 80 or less. Item 10. The adhesive film for metal terminal according to any one of Items 1 to 9, wherein the adhesive film for metal terminal is composed of a laminate including, in this order, a first resin layer disposed on the metal terminal side, an intermediate layer, and a second resin layer disposed on the electricity storage device exterior material side, and at least one layer of the first resin layer, the intermediate layer, and the second resin layer is the thermochromic layer. Item 11. The adhesive film for metal terminal according to any one of Items 1 to 10, wherein the adhesive film for metal terminal is formed from a polyolefin resin. Item 12. A method for producing an adhesive film for metal terminal, wherein the adhesive film for metal terminal is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, wherein the adhesive film for metal terminal has a thermochromic layer. Item 13. Item 14. A metal terminal with an adhesive film for a metal terminal, comprising a metal terminal attached with the adhesive film for a metal terminal according to any one of Items 1 to 11. Item 14. An electricity storage device comprising at least an electricity storage device element including a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding outside the exterior material for an electricity storage device, wherein the adhesive film for a metal terminal according to any one of Items 1 to 11 is interposed between the metal terminal and the exterior material for an electricity storage device. Item 12. A method for manufacturing an electricity storage device including at least an electricity storage device element including a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and that protrude to the outside of the exterior material for an electricity storage device, the method comprising the step of interposing the adhesive film for metal terminal according to any one of Items 1 to 11 between the metal terminal and the exterior material for an electricity storage device, and sealing the electricity storage device element with the exterior material for an electricity storage device.Item 16. A packaging material for an electricity storage device for use in an electricity storage device, wherein the electricity storage device comprises an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte, the packaging material for an electricity storage device sealing the electricity storage device element, and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the packaging material for an electricity storage device, wherein an adhesive film for a metal terminal is interposed between the metal terminal and the packaging material for an electricity storage device, the adhesive film for a metal terminal being the adhesive film for a metal terminal according to any one of Items 1 to 11, and the packaging material for an electricity storage device is constituted by a laminate including at least a base layer, a barrier layer, and a heat-sealable resin layer. Item 12. A kit comprising an exterior material for an electricity storage device for use in an electricity storage device and the adhesive film for a metal terminal according to any one of Items 1 to 11, wherein the electricity storage device comprises an electricity storage device element having at least a positive electrode, a negative electrode, and an electrolyte, the exterior material for an electricity storage device that seals the electricity storage device element, and the metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and that protrude outside the exterior material for an electricity storage device, and the kit is used such that the adhesive film for a metal terminal is interposed between the metal terminal and the exterior material for an electricity storage device during use.

[0160] REFERENCE SIGNS LIST 1 adhesive film for metal terminal 2 metal terminal 3 packaging material for electricity storage device 3a peripheral portion of packaging material for electricity storage device 4 electricity storage device element 10 electricity storage device 11 intermediate layer 12a first resin layer 12b second resin layer 31 substrate layer 32 adhesive layer 33 barrier layer 34 adhesive layer 35 heat-sealable resin layer

Claims

1. An adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, The adhesive film for metal terminal has a thermochromic layer, The thermochromic layer is formed of a resin composition containing a temperature indicating material and a resin, The temperature indicator includes titanium nitride, An adhesive film for metal terminals, wherein the average particle size of the titanium nitride is 10 nm or more and 100 nm or less.

2. The adhesive film for metal terminal according to claim 1 , wherein the temperature indicator has an average particle size of 10 nm or more and 100 nm or less.

3. The adhesive film for metal terminal according to claim 1 or 2, wherein the content of the temperature indicator in the thermochromic layer is 0.01% by mass or more and 50% by mass or less.

4. The adhesive film for metal terminal according to claim 2 or 3, wherein the temperature indicator is titanium nitride.

5. The adhesive film for metal terminal according to claim 1 or 2, wherein the thermochromic layer has a polyolefin skeleton.

6. 3. The adhesive film for metal terminal according to claim 1, wherein when the thermochromic layer is analyzed by infrared spectroscopy, a peak derived from maleic anhydride is detected.

7. The thermochromic layer has a reflectance of 10°, a viewing angle of 10°, and a light source of F2. * a * b * L in color space * The adhesive film for metal terminal according to claim 1 or 2, wherein the value is 80 or less.

8. The adhesive film for a metal terminal is composed of a laminate including, 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 for an electricity storage device, 3 . The adhesive film for metal terminal according to claim 1 , wherein at least one of the first resin layer, the intermediate layer and the second resin layer is the thermochromic layer.

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

10. A method for producing an adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, comprising: The adhesive film for metal terminal has a thermochromic layer, The thermochromic layer is formed of a resin composition containing a temperature indicating material and a resin, The temperature indicator includes titanium nitride, A method for producing an adhesive film for a metal terminal, wherein the average particle size of the titanium nitride is 10 nm or more and 100 nm or less.

11. A metal terminal with an adhesive film for a metal terminal, comprising the adhesive film for a metal terminal according to claim 1 or 2 attached to a metal terminal.

12. An electricity storage device comprising at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude to an outside of the exterior material for an electricity storage device, 3. An electricity storage device, comprising the adhesive film for a metal terminal according to claim 1 or 2 interposed between the metal terminal and the exterior material for an electricity storage device.

13. A method for manufacturing an electricity storage device including at least an electricity storage device element including a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude to an outside of the exterior material for an electricity storage device, A method for manufacturing an electricity storage device, comprising a step of interposing the adhesive film for metal terminals according to claim 1 or 2 between the metal terminals and the exterior material for electricity storage devices, and sealing the electricity storage device elements with the exterior material for electricity storage devices.

14. An exterior material for an electricity storage device for use in an electricity storage device, The electricity storage device includes at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude to the outside of the exterior material for an electricity storage device, and an adhesive film for a metal terminal is interposed between the metal terminal and the exterior material for an electricity storage device, The adhesive film for a metal terminal is the adhesive film for a metal terminal according to claim 1 or 2, The electrical storage device packaging material is composed of a laminate including at least a base layer, a barrier layer, and a heat-sealable resin layer.

15. A kit comprising an exterior material for an electricity storage device for use in an electricity storage device and the adhesive film for a metal terminal according to claim 1 or 2, The electricity storage device includes at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and the metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude to the outside of the exterior material for an electricity storage device, The kit is used such that, when in use, the adhesive film for a metal terminal is interposed between the metal terminal and the exterior material for an electricity storage device.