Package

Abstract

This package is composed from a laminate in which at least a base material layer, an adhesive layer, a barrier layer, and a sealant layer are laminated in this order, and covers an electric storage device. The package includes: an accommodation portion for accommodating the electric storage device by the laminate; and a sealing portion which is arranged on the outside of the accommodation portion in a direction perpendicular to the lamination direction of the laminate, the laminate being formed into a two-layer structure so that the sealant layers face each other, and in which the sealant layers are thermally fused with each other. The sealing portion has a first region and a second region in which the thickness of the sealant layer is smaller than that of the first region. An end face of the second region in the lamination direction has a shape recessed with respect to an end face of the first region in the lamination direction.

Description

packaging

[0001] The present disclosure relates to packaging.

[0002] Known examples of storage battery devices include secondary batteries such as lithium-ion batteries, nickel-metal hydride batteries, and lead-acid batteries, as well as electrochemical capacitors such as electric double-layer capacitors. Due to the miniaturization of portable devices and limitations on installation space, there is a demand for further miniaturization of storage battery devices, and lithium-ion batteries with high energy density have attracted attention. Multilayer films (laminates) that are lightweight, have high heat dissipation properties, and can be produced at low cost have begun to be used as exterior materials for lithium-ion batteries.

[0003] Patent Document 1 discloses an invention related to a container for a lithium-ion battery. This container is formed by using a film having at least an adhesive layer, an aluminum foil layer, an adhesive resin layer, and a sealant layer laminated in this order on one side of a base layer, and heat-sealing the edges of the two films so that the sealant layers are bonded together. In the heat-sealed portion, the total thickness of the adhesive resin layer and the sealant layer changes continuously from the inside to the outside of the container (see Figure 2 of Patent Document 1).

[0004] JP 2011-192603 A

[0005] Meanwhile, research and development is being conducted on storage battery devices known as all-solid-state batteries as the next generation of lithium-ion batteries. All-solid-state batteries use a solid electrolyte instead of an organic electrolyte solution as the electrolyte. Sulfide-based materials are the mainstream solid electrolytes used in all-solid-state batteries. Sulfide-based solid electrolytes may generate hydrogen sulfide in the presence of moisture. Therefore, moisture permeation prevention is required in the packaging. In the above-mentioned conventional technology, moisture permeation is prevented by providing an inclined portion in the sealed portion of the packaging, but there is still room for improvement in terms of preventing moisture permeation through the sealant layer.

[0006] An object of the present disclosure is to provide a package that can suppress moisture permeation through a sealant layer while ensuring the seal strength of the sealant layer.

[0007] (1) One aspect of the present disclosure is a packaging body for exteriorly packaging an energy storage device, the packaging body being composed of a laminate having at least a base layer, an adhesive layer, a barrier layer, and a sealant layer stacked in this order, the packaging body comprising: a storage section for storing the energy storage device using the laminate; and a sealing section arranged outside the storage section in a direction perpendicular to the stacking direction of the laminate, the sealing section having a two-layer structure with the sealant layers facing each other and heat-sealed to each other, the sealing section having a first region and a second region in which the sealant layer is thinner than the first region, and the end face in the stacking direction of the second region has a recessed shape relative to the end face in the stacking direction of the first region.

[0008] In such a package, a first region and a second region are formed in the seal portion of a laminate having a two-layer structure. The end face of the second region in the stacking direction has a recessed shape relative to the end face of the first region in the stacking direction. The thickness of the sealant layer in the second region is smaller than the thickness of the sealant layer in the first region. This makes the second region less susceptible to moisture permeation than the first region. Furthermore, the thickness of the sealant layer in the first region is greater than the thickness of the sealant layer in the second region. This provides the first region with sufficient seal strength compared to the second region. Therefore, it is possible to suppress moisture permeation through the sealant layer while ensuring the seal strength of the sealant layer.

[0009] (2) In the above (1), the end face of the second region in the stacking direction may have a stepped or substantially stepped recessed shape relative to the end face of the first region in the stacking direction. In this configuration, for example, by using a seal bar with a simple structure to thermally seal the sealant layers of the two-layer laminate, the end face of the second region in the stacking direction can be formed into a stepped or substantially stepped recessed shape relative to the end face of the first region in the stacking direction. This allows for reduced manufacturing costs.

[0010] (3) In the above (1) or (2), the second region may be located at an outer edge of the sealed portion in a direction perpendicular to the stacking direction or at a central portion of the sealed portion in a direction perpendicular to the stacking direction. In this configuration, the second region is formed at a position away from the energy storage device. This allows the seal strength of the sealed portion on the energy storage device side to be maintained. In addition, moisture that has penetrated from outside the packaging body can be quickly brought into contact with the second region. This further suppresses moisture permeation through the sealant layer.

[0011] (4) In any of the above (1) to (3), the total length of the second region along the direction perpendicular to the stacking direction may be 2 mm or more. In this configuration, the length of the second region is sufficiently ensured, so that moisture that has penetrated the sealant layer can travel a longer distance to reach the electricity storage device. This makes it possible to reliably suppress moisture permeation through the sealant layer.

[0012] (5) In any of the above (1) to (4), the thickness of the first region may be 60 μm to 150 μm, and the thickness of the second region may be 45 μm to 100 μm. In this configuration, the second region is more resistant to moisture penetration than the first region. Furthermore, the first region can achieve a more sufficient seal strength than the second region.

[0013] (6) In any of the above (1) to (5), the sealant layer may be formed of a material whose main component is a thermoplastic resin. In this configuration, the sealant layer softens when heated and hardens when cooled. This allows the sealant layers of the two-layer laminate to adhere to each other by thermal fusion, forming a seal with excellent sealing properties.

[0014] (7) In any of the above (1) to (6), a metal adhesive layer may be disposed between the sealant layer and the barrier layer. In such a configuration, the metal adhesive layer promotes adhesion between the sealant layer and the barrier layer, thereby improving the strength and durability of the laminate.

[0015] (8) In the above (7), the metal adhesive layer may be formed of a material whose main component is a thermoplastic resin. In such a configuration, the metal adhesive layer softens when heated and hardens when cooled. In this manner, the metal adhesive layer has the same function as the sealant layer. Therefore, the metal adhesive layer and the sealant layer of the two-layer laminate are adhered to each other by thermal fusion, forming a seal portion with excellent sealing properties.

[0016] (9) In the above (8), the metal adhesive layer may contain an acid-modified polyolefin or an acid-modified elastomer. In this configuration, the metal adhesive layer has good adhesion to the metal surface. This allows a strong bond to be formed between the sealant layer and the barrier layer. Therefore, peeling between the sealant layer and the barrier layer can be suppressed.

[0017] (10) In any one of the above (1) to (9), the power storage device may be an all-solid-state battery. In such a configuration, moisture permeation through the sealant layer can be suppressed, thereby imparting the necessary water vapor barrier properties to the all-solid-state battery.

[0018] According to the present disclosure, it is possible to provide a package that can suppress moisture permeation through the sealant layer while ensuring the seal strength of the sealant layer.

[0019] FIG. 1 is a perspective view showing a package according to one embodiment of the present disclosure. FIG. 2 is a cross-sectional view showing a laminate. FIG. 3 is a cross-sectional view taken along line III-III shown in FIG. 1. FIG. 4 is an enlarged cross-sectional view showing a seal portion of a package according to one embodiment. FIG. 5 is a cross-sectional view showing a method for producing a package according to one embodiment. FIG. 6 is a cross-sectional view showing a method for producing a package according to a modified example. FIG. 7 is a cross-sectional view showing a method for producing a package according to another modified example. FIGS. 8(a) and 8(b) are a plan view and a cross-sectional view showing a seal portion of a package according to yet another modified example.

[0020] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are designated by the same reference numerals, and redundant description will be omitted.

[0021] First Embodiment Fig. 1 is a perspective view showing a packaging body 1 according to one embodiment of the present disclosure. The packaging body 1 houses an electricity storage device 30, which will be described later. In one example, the packaging body 1 is a pouch type. The electricity storage device 30 is disposed in the center of the packaging body 1. The electricity storage device 30 is, for example, an all-solid-state battery. In one example, the electricity storage device 30 is a driving battery for an electric vehicle or a battery for a portable electronic device such as a smartphone.

[0022] In the following description, the thickness direction of the packaging body 1 is referred to as the stacking direction D1, the longitudinal direction of the packaging body 1 as the longitudinal direction D2 (direction perpendicular to the stacking direction), and the width direction of the packaging body 1 as the width direction D3 (direction perpendicular to the stacking direction). For example, the longitudinal direction D2 and the width direction D3 are horizontal directions, and the stacking direction D1 is a vertical direction. The stacking direction D1, the longitudinal direction D2, and the width direction D3 are perpendicular to one another.

[0023] The power storage device 30 has terminals 20. The power storage device 30 is provided with two terminals 20. The terminals 20 are a positive terminal and a negative terminal. The terminals 20 are attached to one end of the packaging body 1 in the longitudinal direction D2. The terminals 20 are arranged side by side along the width direction D3. The terminals 20 protrude from the power storage device 30, which is exteriorly packaged in the packaging body 1, toward the outside of the packaging body 1. However, the terminals 20 may also be attached to one end of the packaging body 1 in the width direction D3.

[0024] The terminal 20 protrudes from between the layers of the laminate 10, which has a two-layer structure described below, toward the outside of the packaging body 1. In other words, a part of the terminal 20 is disposed between one laminate 10 and the other laminate 10.

[0025] 2 is a cross-sectional view showing the laminate 10. The packaging body 1 is composed of the laminate 10, which is formed by laminating at least a base material layer 2, an adhesive layer 3, a barrier layer 4, and a sealant layer 6 in this order. More specifically, the laminate 10 has the base material layer 2, the adhesive layer 3, the barrier layer 4, a metal adhesive layer 5, and the sealant layer 6.

[0026] The base material layer 2, adhesive layer 3, barrier layer 4, metal adhesive layer 5, and sealant layer 6 are laminated along a lamination direction D1. In the package 1, the base material layer 2 is the outermost layer, and the sealant layer 6 is the innermost layer. The "outermost layer" is the layer located farthest from the energy storage device 30. The "innermost layer" is the layer located closest to the energy storage device 30.

[0027] The base material layer 2 is a sheet-like member. The base material layer 2 has heat resistance in the sealing process when manufacturing the electricity storage device 30. The base material layer 2 plays a role in suppressing the occurrence of pinholes that may occur during distribution, etc., during molding processing. In particular, in the case of a package 1 that exteriorly houses a large-scale electricity storage device 30, the base material layer 2 has scratch resistance, chemical resistance, insulating properties, etc.

[0028] The base layer 2 may have a peak melting temperature higher than the peak melting temperature of the sealant layer 6. In this case, it is possible to suppress deformation of the laminate 10 caused by melting of the base layer 2 when the laminate 10 is heat-sealed. The "peak melting temperature of the sealant layer 6" is the peak melting temperature of the sealant layer having the highest peak melting temperature in the sealant layer 6 having a multilayer structure.

[0029] The melting peak temperature of the base layer 2 is, for example, 250°C to 350°C. The melting peak temperature is a value determined in accordance with the method described in JIS K7121-1987. The temperature difference (T11-T16) between the melting peak temperature T11 of the base layer 2 and the melting peak temperature T16 of the sealant layer 6 is, for example, 20°C or more. When the temperature difference is 20°C or more, deterioration of the appearance of the laminate 10 due to heat sealing can be effectively suppressed.

[0030] The base layer 2 is a layer formed of, for example, an insulating resin, such as polyester resin, polyamide resin, polyimide resin, polyamideimide resin, polyetherketone resin, polyphenylene sulfide resin, polyetherimide resin, polysulfone resin, fluororesin, phenol resin, melamine resin, urethane resin, allyl resin, silicone resin, epoxy resin, furan resin, or acetyl cellulose resin.

[0031] Among the above resins, from the viewpoint of moldability, at least one of a polyester resin and a polyamide resin may be used as the resin for the base layer 2. Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.

[0032] Examples of polyamide resins include nylon 6, nylon 6,6, a copolymer of nylon 6 and nylon 6,6, nylon 9T, nylon 10, polymetaxylylene adipamide (MXD6), nylon 11, and nylon 12. The base material layer 2 may contain additives and the like depending on the required performance.

[0033] The substrate layer 2 may be in the form of a stretched or unstretched film, but is not limited thereto. The substrate layer 2 may also be in the form of a coating film. The substrate layer 2 may be a single layer or may be multilayer. When the substrate layer 2 is multilayer, the layers included in the substrate layer 2 may be formed from different resins or may be formed from the same resin.

[0034] When the substrate layer 2 is in the form of a film, the substrate layer 2 may be formed by coextrusion or may be laminated via an adhesive. When the substrate layer 2 is a coating film, the coating film is obtained, for example, by coating a coating film-forming composition multiple times. The substrate layer 2 may have a multilayer structure combining a film and a coating film.

[0035] When the resin described above is used in the form of a film, the base layer 2 may be a biaxially stretched film. In this case, the formability of the laminate 10 is improved. Examples of stretching methods for biaxially stretched films include sequential biaxial stretching, tubular biaxial stretching, and simultaneous biaxial stretching. The biaxially stretched film may be a film stretched by tubular biaxial stretching, from the viewpoint of obtaining better deep draw formability.

[0036] The thickness of the substrate layer 2 in the stacking direction D1 is, for example, 10 μm to 60 μm. When the thickness of the substrate layer 2 in the stacking direction D1 is within the above range, the thermal conductivity of the substrate layer 2 can be set within a favorable range. The substrate layer 2 may contain, for example, an additive. Examples of the additive include a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, and a tackifier.

[0037] The adhesive layer 3 is a layer that bonds the barrier layer 4, which has a corrosion prevention treatment layer provided thereon, to the substrate layer 2. The adhesive layer 3 has the adhesive strength required to firmly bond the substrate layer 2 and the barrier layer 4. The adhesive layer 3 has conformability to prevent the barrier layer 4 from being broken by the substrate layer 2. "Conformability" refers to the property of the adhesive layer 3 remaining on the member without peeling off, even if the member is deformed due to expansion and contraction or the like.

[0038] Examples of adhesive components that form the adhesive layer 3 include urethane-based compounds, urea-based compounds, epoxy-based compounds, and silicon-based compounds. These compounds may be used alone or in combination of two or more.

[0039] The urethane-based compound can be obtained by reacting a polyol resin with a polyfunctional isocyanate compound, and the urea-based compound can be obtained by reacting an amine-based compound or an amine derivative with a polyfunctional isocyanate compound.

[0040] Examples of polyol resins include polyester polyols, polyether polyols, polycarbonate diols, and polyacrylic polyols.

[0041] Examples of polyester polyols include polyester polyols obtained by reacting one or more dicarboxylic acids with a diol.

[0042] Examples of polyether polyols include those produced by addition polymerization of ethylene oxide or propylene oxide with propylene glycol, glycerin, pentaerythritol, or the like.

[0043] Examples of polycarbonate polyols include polycarbonate polyols obtained by reacting a carbonic acid diester such as diphenyl carbonate with a diol.

[0044] Examples of polyacrylic polyols include copolymers obtained by copolymerizing at least a hydroxyl group-containing acrylic monomer with (meth)acrylic acid, which may contain structural units derived from (meth)acrylic acid as a main component.

[0045] Examples of hydroxyl group-containing acrylic monomers include 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate.

[0046] The polyfunctional isocyanate compound contains a plurality of isocyanate groups. The polyfunctional isocyanate compound can function as a crosslinking agent that crosslinks the amine resin or polyol. The polyfunctional isocyanate compound may be used alone or in combination of two or more. Examples of the polyfunctional isocyanate compound include an aliphatic polyfunctional isocyanate compound, an alicyclic polyfunctional isocyanate compound, and a polyfunctional isocyanate compound having an aromatic ring.

[0047] Examples of the aliphatic polyfunctional isocyanate compound include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), etc. Examples of the alicyclic polyfunctional isocyanate compound include isophorone diisocyanate (IPDI), etc.

[0048] Examples of polyfunctional isocyanate compounds having an aromatic ring include tolylene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI). Multimers (e.g., trimers) of these compounds can also be used as the polyfunctional isocyanate compound. Specifically, adducts, biurets, isocyanurates, and the like can be used.

[0049] From the viewpoint of improving the pot life, the isocyanate group of the polyfunctional isocyanate compound may be bonded to a blocking agent, such as methyl ethyl ketoxime (MEKO).

[0050] The temperature at which the blocking agent is cleaved from the isocyanate group of the polyfunctional isocyanate compound may be 50°C or higher. From the viewpoint of improving the pot life, the temperature may be 60°C or higher. The temperature at which the blocking agent is cleaved from the isocyanate group of the polyfunctional isocyanate compound may be 140°C or lower. From the viewpoint of molding curl resistance of the laminate 10, the temperature may be 120°C or lower.

[0051] In order to lower the dissociation temperature of the blocking agent, a catalyst that lowers the dissociation temperature may be used in the adhesive layer 3. Examples of the catalyst that lowers the dissociation temperature include tertiary amines such as triethylenediamine and N-methylmorpholine, and metal organic acid salts such as dibutyltin dilaurate.

[0052] An amine compound is a compound having an amino group in the molecule. ２ , -NHR, -NR ２ where R represents an alkyl group and / or an allyl group. The amine derivative is a compound derived from an amine compound and does not have an amino group in the molecule.

[0053] The amine compound and the amine derivative may be a latent curing agent or a latent curing agent. The latent curing agent is a curing agent that is activated by an external stimulus to generate a reactive group that can react with an isocyanate group. When the amine compound and the amine derivative are a latent curing agent, the pot life tends to be improved.

[0054] Examples of the external stimuli include heat and moisture. Examples of the latent curing agent include imidazole-based curing agents, imine-based curing agents, amine imide-based curing agents, dicyandiamide-based curing agents, aromatic polyamine-based curing agents, aliphatic polyamine-based curing agents, polyamidoamine-based curing agents, tertiary amine salt-based curing agents, and oxazolidine-based curing agents.

[0055] Among the above, examples of the latent curing agent that is activated by heating include imidazole-based curing agents, dicyandiamide-based curing agents, polyamine-based curing agents, and amine imide-based curing agents.

[0056] Examples of latent curing agents that are activated by moisture include imine-based curing agents and oxazolidine-based curing agents. From the viewpoint of improving pot life, the latent curing agent may be one that is activated by moisture.

[0057] From the viewpoint of inhibiting corrosion of the barrier layer 4 by hydrogen sulfide, the adhesive layer 3 may contain a hydrogen sulfide treatment substance. The hydrogen sulfide treatment substance is a substance that chemically reacts with hydrogen sulfide (hydrogen sulfide reactive substance). Examples of the hydrogen sulfide treatment substance include zinc oxide and potassium permanganate.

[0058] The hydrogen sulfide-treated substance also functions as a thermally conductive filler, thereby improving the heat dissipation properties of the laminate 10. From the viewpoint of inhibiting corrosion of the barrier layer 4 by hydrogen sulfide, the content of the hydrogen sulfide-treated substance in the adhesive layer 3 is, for example, 1 mass % to 50 mass % relative to the total amount of the adhesive layer 3.

[0059] The thickness of the adhesive layer 3 in the stacking direction D1 is not particularly limited, but is, for example, 1 μm to 10 μm from the viewpoint of obtaining desired adhesive strength, thermal conductivity, conformability, processability, and the like.

[0060] The mass per unit area of ​​the adhesive layer 3 is set to, for example, 2.0 g / m from the viewpoint of ensuring superior lamination strength both in a room temperature environment and a high temperature environment and obtaining superior deep drawability. ２ ~6.0g / m ２ is.

[0061] The barrier layer 4 has a water vapor barrier property that prevents moisture from penetrating into the inside of the power storage device 30. The barrier layer 4 may have extensibility for deep drawing. In this embodiment, the barrier layer 4 is, for example, a metal foil layer provided with a corrosion prevention treatment layer.

[0062] The corrosion prevention treatment layer is located on the surface of the metal foil layer facing the adhesive layer 3. The corrosion prevention treatment layer is located on the surface of the metal foil layer facing the metal adhesive layer 5. In the stacking direction D1, the thickness of the metal foil layer is significantly greater than the thickness of the corrosion prevention treatment layer. Therefore, in the stacking direction D1, the thickness of the barrier layer 4 corresponds to the thickness of the metal foil layer.

[0063] As the barrier layer 4, for example, various metal foils such as aluminum, stainless steel, and copper, or metal vapor deposition films, inorganic oxide vapor deposition films, carbon-containing inorganic oxide vapor deposition films, films provided with these vapor deposition films, and the like can be used.

[0064] Examples of films provided with a vapor-deposited film include aluminum vapor-deposited films and inorganic oxide vapor-deposited films. These may be used alone or in combination of two or more. The barrier layer 4 may contain aluminum foil from the viewpoints of mass (specific gravity), barrier properties such as moisture resistance, processability, and cost.

[0065] When the barrier layer 4 contains aluminum foil, the barrier layer 4 may contain soft aluminum foil that has been annealed, which can impart desired ductility during forming. The barrier layer 4 may also contain aluminum foil containing iron, which can impart further pinhole resistance and ductility during forming.

[0066] The iron content in the aluminum foil is, for example, 0.1 to 9.0% by mass relative to 100% by mass of the aluminum foil. The aluminum foil is, for example, 8021 material or 8079 material specified in the JIS standard.

[0067] When the iron content is 0.1% by mass or more, the laminate 10 can have better pinhole resistance and ductility. When the iron content is 9.0% by mass or less, the laminate 10 can have better flexibility.

[0068] As the aluminum foil, untreated aluminum foil may be used, or degreased aluminum foil may be used to impart corrosion resistance. When the aluminum foil is degreased, the degreasing treatment may be performed on only one side of the aluminum foil, or on both sides.

[0069] The degreasing treatment may be, for example, a wet type degreasing treatment or a dry type degreasing treatment. However, from the viewpoint of simplifying the manufacturing process, the dry type degreasing treatment may also be used as the degreasing treatment.

[0070] An example of a dry-type degreasing treatment is a method in which the degreasing treatment is performed by extending the treatment time during the annealing treatment of the metal foil. Sufficient electrolyte resistance can be obtained even with the degreasing treatment performed simultaneously with the annealing treatment performed to soften the metal foil.

[0071] The dry-type degreasing treatment may be a treatment other than the annealing treatment, such as a flame treatment or a corona treatment. Furthermore, the dry-type degreasing treatment may be, for example, a degreasing treatment in which contaminants are oxidatively decomposed and removed by active oxygen generated when a metal foil is irradiated with ultraviolet light of a specific wavelength.

[0072] As the wet-type degreasing treatment, for example, an acid degreasing treatment, an alkali degreasing treatment, etc. may be used. As the acid used in the acid degreasing treatment, for example, an inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid, etc. These acids may be used alone or in combination of two or more.

[0073] The alkali used in the alkaline degreasing treatment may be, for example, sodium hydroxide, which has a high etching effect. Alternatively, the alkaline degreasing treatment may be performed using a weak alkaline material or a material containing a surfactant, etc. The wet-type degreasing treatment described above may be performed by, for example, a dipping method or a spray method.

[0074] The thickness of the barrier layer 4 in the stacking direction D1 is not particularly limited, but is, for example, 9 μm to 200 μm from the viewpoints of barrier properties, pinhole resistance, processability, etc. When the thickness of the barrier layer 4 in the stacking direction D1 is 9 μm or more, the barrier layer 4 is less likely to break even when stress is applied during molding. When the thickness of the barrier layer 4 in the stacking direction D1 is 200 μm or less, the increase in mass of the laminate 10 can be reduced.

[0075] From the viewpoint of the thermal diffusivity of the laminate 10, the ratio of the thickness of the barrier layer 4 to the thickness of the laminate 10 is, for example, 15% or more. From the viewpoint of the insulating properties of the laminate 10, the ratio of the thickness of the barrier layer 4 to the thickness of the laminate 10 is, for example, 50% or less. In other words, the ratio of the thickness of the barrier layer 4 to the thickness of the laminate 10 is 15% to 50%.

[0076] The metal adhesive layer 5 is disposed between the sealant layer 6 and the barrier layer 4. The metal adhesive layer 5 is formed from a material whose main component is a thermoplastic resin. The metal adhesive layer 5 is a layer that bonds the sealant layer 6 and the barrier layer 4. The material of the metal adhesive layer 5 is not particularly limited as long as it contains a resin that bonds the sealant layer 6 and the barrier layer 4. From the viewpoint of adhesion and moisture barrier properties, the metal adhesive layer 5 may contain an acid-modified polyolefin or an acid-modified elastomer.

[0077] The acid-modified polyolefin may be a polyolefin resin modified with maleic anhydride, carboxylic acid, sulfonic acid, or a derivative thereof, and is, for example, a graft copolymer, a block copolymer, or a random copolymer.

[0078] The acid-modified polyolefin may be a polyolefin resin graft-modified with maleic anhydride from the viewpoint of adhesion to the barrier layer 4. Alternatively, the acid-modified polyolefin may contain a reaction product (hereinafter referred to as "reaction product X") of the acid-modified polyolefin and a polyfunctional isocyanate compound serving as a curing agent.

[0079] The components for obtaining the reaction product X may consist of only the acid-modified polyolefin and the polyfunctional isocyanate compound, or may contain other components in addition to the acid-modified polyolefin and the polyfunctional isocyanate compound.

[0080] The acid-modified polyolefin contains polar groups such as hydroxyl groups, carboxylic groups, etc. The hydroxyl value of the acid-modified polyolefin is, for example, 5 KOH mg / g to 120 KOH mg / g or less from the viewpoint of reactivity.

[0081] The acid-modified polyolefin may be a polyolefin graft-modified with an unsaturated carboxylic acid derivative derived from an unsaturated carboxylic acid, an unsaturated sulfonic acid, an acid anhydride of an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, etc. In this case, the degree of acid modification in the acid-modified polyolefin is, for example, 2.0 mass% or less.

[0082] Examples of acid-modified polyolefins include maleic anhydride-modified polyolefins obtained by reacting maleic anhydride with a polyolefin, such as maleic anhydride-modified polypropylene and maleic anhydride-modified polyethylene.

[0083] Examples of polyfunctional isocyanate compounds include diisocyanates such as tolylene diisocyanate, xylylene diisocyanate or hydrogenated products thereof, hexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate or hydrogenated products thereof, and isophorone diisocyanate; or polyisocyanates such as adducts obtained by reacting these isocyanates with polyhydric alcohols such as trimethylolpropane, biuret compounds obtained by reacting these isocyanates with water, or trimer isocyanurates (isocyanurate-type polyfunctional isocyanate compounds); and blocked polyisocyanates obtained by blocking these polyisocyanates with alcohols, lactams, oximes, or the like.

[0084] The polyfunctional isocyanate compound may contain an isocyanurate (isocyanurate-type polyfunctional isocyanate compound), in which case the metal adhesive layer 5 can have good adhesion and heat resistance.

[0085] The metal adhesive layer 5 may contain various additives as needed, such as various compatible and incompatible elastomers, flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, crystal nucleating agents, and tackifiers. The resin in the metal adhesive layer 5 can be analyzed by known analytical methods such as IR, NMR, various mass spectrometry methods, X-ray analysis, Raman spectroscopy, GPC, DSC, and DMA.

[0086] The sealant layer 6 is a layer that provides the laminate 10 with heat-sealing (thermal fusion) sealing properties. The sealant layer 6 is the innermost layer described above and is the layer that is heat-sealed. The sealant layer 6 is formed of a material whose main component is a thermoplastic resin. The resin material that constitutes the sealant layer 6 may be a polypropylene-based resin, a polyethylene-based resin, or a combination of these resins.

[0087] In the sealant layer 6, the proportion of the polypropylene-based resin relative to the total of the polypropylene-based resin and the polyethylene-based resin is, for example, 85% by mass or more and less than 100% by mass. In the sealant layer 6, the proportion of the polyethylene-based resin relative to the total of the polypropylene-based resin and the polyethylene-based resin is, for example, more than 0% by mass and 20% by mass or less.

[0088] From the viewpoint of the deformation rate of the sealant layer 6 in a high-temperature environment, the proportion of the polypropylene-based resin to the total of the polypropylene-based resin and the polyethylene-based resin is, for example, 85% by mass or more. The proportion is not particularly limited as long as it is less than 100% by mass, but is, for example, 98% by mass or less.

[0089] The polypropylene-based resin contained in the sealant layer 6 is, for example, the base resin of the sealant layer 6. The polypropylene-based resin is a resin obtained from a polymerized monomer containing propylene. Examples of the polypropylene-based resin include homopolypropylene, block polypropylene, and random polypropylene. These may be used alone or in combination of two or more.

[0090] The polypropylene-based resin may contain at least one of homopolypropylene and block polypropylene from the viewpoint of hardness of the laminate 10. In this case, the scratch resistance of the laminate 10 is improved compared to when the polypropylene is composed of only random polypropylene.

[0091] The crystallization temperature of the polypropylene-based resin is not particularly limited, but is, for example, 100° C. to 120° C. From the viewpoint of the scratch resistance of the laminate 10, the crystallization temperature of the polypropylene-based resin is, for example, 102° C. or higher. The melting temperature (melting point) of the polypropylene-based resin is, for example, 160° C. to 168° C.

[0092] From the viewpoint of sealing properties in a high-temperature environment, the melting point may be 162° C. or higher. The difference between the melting temperature and the crystallization temperature is not particularly limited and is, for example, 30° C. to 70° C. From the viewpoint of the balance between hardness and softness in the sealant layer 6, the difference between the melting temperature and the crystallization temperature may be 40° C. to 65° C.

[0093] The polyethylene-based resin is a resin obtained from a polymerized monomer containing ethylene, and serves to impart softness (stress relaxation properties). Examples of the polyethylene-based resin include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and polyethylene-based elastomers. These may be used alone or in combination of two or more. From the viewpoint of imparting softness to the sealant layer 6, the polyethylene-based resin may contain a polyethylene-based elastomer.

[0094] The polyethylene elastomer may be an elastomer containing an α-olefin as a comonomer, specifically, a compound (copolymer) obtained by copolymerizing ethylene with at least one α-olefin selected from 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene.

[0095] Examples of such copolymers include polyethylene-butene copolymers, polyethylene-pentene copolymers, and polyethylene-hexene copolymers.

[0096] The polyethylene resin may contain a copolymer that functions as a compatibilizer, which efficiently imparts softness by finely dispersing the polyethylene resin in the polypropylene resin base resin.

[0097] The copolymer has, for example, a portion compatible with polypropylene-based resins (hereinafter referred to as a "PP-compatible portion") and a portion compatible with polyethylene-based resins (hereinafter referred to as a "PE-compatible portion"). Specific examples of the copolymer include a graft copolymer in which the PP-compatible portion is the main chain and the PE-compatible portion is the side chain, a graft copolymer in which the PE-compatible portion is the main chain and the PP-compatible portion is the side chain, and a block copolymer in which the PP-compatible portion and the PE-compatible portion are each present as a block.

[0098] From the viewpoint of improving the dispersibility of the polyethylene resin, the copolymer may be a block copolymer in which at least the PP-compatible portion exists as a block, or a block copolymer in which the PP-compatible portion and the PE-compatible portion each exist as a block.

[0099] Examples of such block copolymers include a block copolymer of polypropylene and polyethylene (PP-PE block copolymer), a block copolymer of polyethylene and polyethylene butylene (PE-PE-butylene block copolymer), etc. In the PE-PE-butylene block copolymer, the butylene portion corresponds to the PP compatible portion.

[0100] The crystallization temperature of the polyethylene resin is not particularly limited, but is, for example, 50° C. to 90° C. The melting temperature (melting point) of the polyethylene resin is, for example, greater than 70° C. and equal to or less than 120° C.

[0101] When the crystallization temperature and melting temperature of the polyethylene resin are each within the above ranges, a good balance between hardness and softness can be achieved in the sealant layer 6. In this case, stress applied to the sealant layer 6 during the production of the laminate 10 is more likely to be alleviated.

[0102] For example, when the laminate 10 is transported by rolls and stress is applied from the rolls to the sealant layer 6, the rebound of the stress from the rolls toward the barrier layer 4 is suppressed. Therefore, the surface of the sealant layer 6 is less likely to be damaged.

[0103] From the viewpoint of the scratch resistance of the laminate 10, the crystallization temperature of the polyethylene resin is, for example, 55°C to 85°C. From the viewpoint of the scratch resistance of the laminate 10, the melting temperature of the polyethylene resin is 80°C or higher. The temperature difference between the melting temperature and the crystallization temperature is not particularly limited and is, for example, 10°C to 45°C. From the viewpoint of the balance between hardness and softness in the sealant layer 6, the temperature difference between the melting temperature and the crystallization temperature may be 15°C to 40°C.

[0104] The sealant layer 6 may contain other additive components as needed, such as a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, a crystal nucleating agent, a flame retardant, etc. The content of these additive components is, for example, 5% by mass or less, when the total mass of the sealant layer 6 is 100% by mass.

[0105] When the laminate 10 includes the metal adhesive layer 5 and the sealant layer 6, the metal adhesive layer 5 and the sealant layer 6 may be formed simultaneously or at different times by a T-die method, an inflation method, or the like. In the latter case, the metal adhesive layer 5 and the sealant layer 6 may be bonded together with an adhesive. In this case, the adhesive may contain acid-modified polypropylene and a curing agent (e.g., isocyanate) from the viewpoint of interfacial adhesion.

[0106] A polyethylene terephthalate (PET) film or a polybutylene terephthalate (PBT) film may be used as the sealant layer 6. When a resin film is used as the sealant layer 6, it is preferable to attach the sealant layer 6 to the barrier layer 4 by dry lamination. Specifically, a coating of an adhesive for forming the metal adhesive layer 5 is formed on the surface of the barrier layer 4. This coating is dried, for example, at 80°C for 1 minute, and then the film that constitutes the sealant layer 6 is attached. This is then aged, for example, at 60°C for 6 days. The thickness of the adhesive after drying may be, for example, 1 μm to 5 μm.

[0107] By using a polyester resin film such as a PET film or a PBT film as the film constituting the sealant layer 6, a sufficiently high seal strength can be maintained even in a high-temperature environment. For example, a seal strength of 10 N / 10 mm or more can be achieved in a 200°C environment. According to the inventors' studies, by using a PBT film as the film constituting the sealant layer 6, a seal strength of 10 N / 10 mm or more can be achieved in a 200°C environment, and by using a PET film, a seal strength of preferably 20 N / 10 mm or more, more preferably 25 N / 10 mm or more, and even more preferably 30 N / 10 mm or more can be achieved in a 200°C environment. The ability to maintain seal strength under such high-temperature conditions is useful for housing all-solid-state batteries that can operate at high temperatures.

[0108] Fig. 3 is a cross-sectional view taken along line III-III in Fig. 1. As shown in Fig. 1 and Fig. 3, the package 1 includes a storage section 1b and a seal section 1a. The storage section 1b is a portion that stores the power storage device 30 using the laminate 10.

[0109] In the accommodation portion 1b, the stack body 10 is arranged so as to sandwich the power storage device 30 in the stacking direction D1. The stack body 10 is also arranged so as to sandwich the power storage device 30 in the longitudinal direction D2 and the width direction D3. The power storage device 30 is surrounded by the stack body 10.

[0110] In the housing portion 1b, the stack body 10, the electricity storage device 30, and the stack body 10 are arranged side by side in the stacking direction D1. The electricity storage device 30 faces the sealant layer 6.

[0111] The sealed portion 1a is disposed outside the housing portion 1b in the longitudinal direction D2 and the width direction D3. The sealed portion 1a is composed of a two-layer laminate 10. The sealed portion 1a is a portion where the laminate 10 has a two-layer structure so that the sealant layers 6 face each other, and the sealant layers 6 are heat-sealed. In the sealed portion 1a, the two-layer laminate 10 is laminated facing opposite the lamination direction D1. In FIG. 3, for ease of explanation, two sealant layers 6 are shown, but because the sealant layers 6 are heat-sealed, the boundary between the sealant layers 6 is unclear.

[0112] The seal portion 1a is formed by stacking one laminate 10 having been processed to form a recess for accommodating the power storage device 30 on another flat laminate 10, and heat-sealing their peripheral edges together. The seal portion 1a may also be formed by folding one laminate 10 having been processed to form a recess for accommodating the power storage device 30 in half, and heat-sealing their peripheral edges together.

[0113] 4 is an enlarged cross-sectional view showing the sealed portion 1a of the package 1 according to one embodiment. The sealed portion 1a has a first region A and a second region B in which the thickness of the sealant layer 6 is smaller than that of the first region A.

[0114] The thickness P1 of the sealant layer 6 in the first region A is, for example, 60 μm to 150 μm. The thickness P1 of the sealant layer 6 in the first region A is equal or approximately equal overall. The thickness P2 of the sealant layer 6 in the second region B is, for example, 45 μm to 100 μm. The thickness P2 of the sealant layer 6 in the second region B is equal or approximately equal overall. The thickness of the sealant layer 6 is the dimension of the sealant layer 6 in the stacking direction D1.

[0115] The total length Q of the second region B along the longitudinal direction D2 and the width direction D3, which are directions perpendicular to the stacking direction D1, is, for example, 2 mm or more. The "total length Q" refers to the sum of the lengths of the second region B along the longitudinal direction D2 and the width direction D3 in the seal portion 1a.

[0116] The length of the second region B along the longitudinal direction D2 and the width direction D3 in the sealed portion 1a is not limited to the case where it is formed by one second region B. For example, in the case where the sealed portion 1a is provided with a plurality of second regions B along the longitudinal direction D2 and the width direction D3, this means that the total length of the plurality of second regions B is, for example, 2 mm or more.

[0117] The distance from the outer end to the inner end (the end on the side of the power storage device 30) of the seal portion 1a in the longitudinal direction D2 and the width direction D3 is longer than 2 mm. The thickness P2 of the sealant layer 6 in the second region B is smaller than the thickness P1 of the sealant layer 6 in the first region A. This makes the sealant layer 6 in the second region B less permeable to moisture than the sealant layer 6 in the first region A.

[0118] The second region B is disposed at the outer end of the seal portion 1a in the longitudinal direction D2 and the width direction D3, which are directions perpendicular to the stacking direction D1. The second region B is formed at a position away from the electricity storage device 30. Moisture penetrating from outside the package 1 immediately comes into contact with the second region B, so that the sealant layer 6 can suppress moisture penetration at an early stage.

[0119] An end face Eb of the second region B in the stacking direction D1 has a recessed shape with respect to an end face Ea of the first region A in the stacking direction D1. Specifically, the end face Eb of the second region B in the stacking direction D1 has a stepped or substantially stepped recessed shape with respect to an end face Ea of the first region A in the stacking direction D1.

[0120] A step Ec is provided at the end of the seal portion 1a in the stacking direction D1, connecting the end face Ea and the end face Eb. The step Ec is a side surface that forms the boundary between the first region A and the second region B.

[0121] The end surface Eb of the second region B in the stacking direction D1 does not have an inclined or curved shape tapering outward in the longitudinal direction D2 and the width direction D3 with respect to the stacking direction D1. Therefore, the thickness P2 of the sealant layer 6 in the second region B does not gradually decrease outward in the longitudinal direction D2 and the width direction D3.

[0122] The recessed shape will be described in detail below with reference to Figures 5 to 8. Figure 5 is a cross-sectional view showing a method for producing a package 1 according to one embodiment. The seal bar 41 shown in Figure 5 is a processing tool that presses the two-layered laminate 10 from both directions in the stacking direction D1 when producing the package 1.

[0123] The seal bar 41 has a press surface 41 a and a side surface 41 b that is continuous with the press surface 41 a. The seal bars 41 are arranged on both sides of the laminate 10 in the stacking direction D1. The press surfaces 41 a are surfaces that face each other in the stacking direction D1.

[0124] The press surface 41a is the surface facing the base material layer 2 located at both ends of the two-layer laminate 10 in the stacking direction D1. The press surface 41a is flat throughout the entire length direction D2 and width direction D3. The laminate 10 is sealed by pressing the laminate 10 with the seal bar 41 from both sides in the stacking direction D1. This is called the "first press." Thereafter, the laminate 10 is shifted to one side in the width direction D3 (e.g., the left side as viewed in FIG. 5 ), and the laminate 10 is pressed again with the seal bar 41. This is called the "second press." The press pressure during the second press is greater than the press pressure during the first press.

[0125] As described above, by pressing twice, a first region A and a second region B are formed in the sealed portion 1a of the package 1. The press surface 41a of the seal bar 41 and the side surface 41b of the seal bar 41 are continuous with each other, including the corners. Therefore, when the laminate 10 is shifted to one side in the width direction D3 and pressed a second time, the end surface Eb of the second region B in the stacking direction D1 has a stepped recessed shape relative to the end surface Ea of the first region A in the stacking direction D1. In other words, a stepped portion Ec is formed between the end surface Ea and the end surface Eb. Because the two-layer laminate 10 is pressed by the seal bar 41 from both sides in the stacking direction D1, the stepped recessed shape is formed on both sides of the two-layer laminate 10 in the stacking direction D1.

[0126] As described above, the stepped recessed shape is formed on both sides of the two-layer laminate 10 in the stacking direction D1. However, the stepped recessed shape may be formed on only one side of the two-layer laminate 10 in the stacking direction D1. In this case, of the seal bars 41 provided on both sides in the stacking direction D1, only one seal bar 41 operates in the second pressing.

[0127] Fig. 6 is a cross-sectional view showing a method for producing a package 1A according to a modified example. In this modified example, the laminate 10 is pressed only once, and differs from the above embodiment in that a seal bar 42 is used in the pressing. In the modified example shown in Fig. 6, the package 1A is produced by pressing with the seal bar 42. Note that in this modified example, the laminate 10 is not shifted to one side in the width direction D3.

[0128] The seal bar 42 has a press surface 42a. The seal bar 42 is arranged on both sides of the two-layer laminate 10 in the stacking direction D1. The press surfaces 42a are surfaces that face each other in the stacking direction D1. The press surface 42a is a surface that faces the laminate 10 in the stacking direction D1. A protrusion 42b is provided on one side of the press surface 42a (for example, the right side of the paper in FIG. 6). The protrusion 42b protrudes from the seal bar 42 toward the laminate 10. The protrusion 42b has a cross-sectional shape that includes angular corners. The protrusion 42b may be integral with the press surface 42a or may be a separate body.

[0129] The protrusion 42b forms a step in the stacking direction D1 on the press surface 42a. The end face Eb of the second region B in the stacking direction D1 has a recessed, stepped shape relative to the end face Ea of the first region A in the stacking direction D1. In other words, a step Ec is formed between the end faces Ea and Eb. Therefore, by using the seal bar 42, a single press operation can achieve the same effect as when the laminate 10 is pressed twice using only the seal bar 41 and shifted to one side in the width direction D3.

[0130] Figure 7 is a cross-sectional view showing a method for producing a package 1B according to another modified example. This modified example differs from the above embodiment in that the laminate 10 is pressed only once, and a seal bar 43 is used in the pressing. In the modified example shown in Figure 7, the package 1B is produced by pressing with the seal bar 43. Note that in this modified example, the laminate 10 is not shifted to one side in the width direction D3.

[0131] The seal bar 43 has a press surface 43a. The seal bar 43 is arranged on both sides of the two-layer laminate 10 in the stacking direction D1. The press surfaces 43a are surfaces that face each other in the stacking direction D1. The press surfaces 43a are surfaces that face the laminate 10 in the stacking direction D1. A protrusion 43b having a rectangular cross section is provided in the center of the press surface 43a in the width direction D3. The protrusion 43b protrudes from the seal bar 43 toward the laminate 10 in the stacking direction D1. One protrusion 43b is provided on the seal bar 43. The protrusion 43b may be integral with the press surface 43a or may be a separate body.

[0132] In this modified example, a recess (concave shape) is formed in the center of the seal portion 1a in the width direction D3 by pressing. That is, in this modified example, the second region B is formed in the center of the width direction D3. The first region A is formed on both the left and right sides of the second region B in the width direction D3. Therefore, two step portions Ec are formed in the seal portion 1a along the width direction D3.

[0133] The recess depends on the shape of the protrusion 43b, etc. In other words, in this modified example, only one protrusion 43b is provided on the seal bar 43, so one recess is formed in the laminate 10. In addition, in this modified example, the protrusion 43b has a rectangular cross section, so the corners of the recess have a shape that includes angles.

[0134] In this modification, the recessed shape is formed in one location on the laminate 10, but the recessed shape may be formed in two or more locations on the laminate 10. That is, two or more protrusions 43b may be provided on the seal bar 43. The end face of the laminate 10 may have a stripe shape when viewed from the stacking direction D1.

[0135] Although the corners of the recessed shape in this modification include sharp edges, the corners of the recessed shape may be rounded. That is, the protrusion 43b may have rounded corners in cross section. In this case, the end face Eb of the second region B in the stacking direction D1 has a substantially stepped recessed shape relative to the end face Ea of the first region A in the stacking direction D1.

[0136] The recessed shape may also be curved as viewed from the longitudinal direction D2. In this case, too, the end face Eb of the second region B in the stacking direction D1 has a substantially stepped recessed shape relative to the end face Ea of the first region A in the stacking direction D1. Furthermore, the recessed shape may have a trapezoidal cross section as viewed from the longitudinal direction D2. That is, the protrusion 43b may have a trapezoidal cross section. In this case, the end face Eb of the second region B in the stacking direction D1 has a stepped recessed shape relative to the end face Ea of the first region A in the stacking direction D1.

[0137] Figure 8 shows a plan view and a cross-sectional view of the seal portion 1a of a package 1C according to yet another modification. Figure 8(a) is a plan view of the package 1C as viewed from the stacking direction D1. Figure 8(b) is a cross-sectional view taken along line VIII-VIII shown in Figure 8(a). Figure 8 shows the package 1C after pressing. Note that in this modification, the stack 10 is not shifted to one side in the width direction D3.

[0138] In this modification, the seal bar (not shown) has a plurality of protrusions, each having a rectangular cross section, on its press surface. The protrusions of the seal bar are arranged at regular intervals along the longitudinal direction D2 and the width direction D3.

[0139] In the sealed portion 1a of the package 1C, portions pressed by the seal bar and portions not pressed are arranged alternately along the longitudinal direction D2 and the width direction D3. That is, in the sealed portion 1a of the package 1C, the first region A and the second region B are arranged alternately along the longitudinal direction D2 and the width direction D3. Therefore, the stepped recesses in which the end faces Eb of the second region B in the stacking direction D1 are recessed relative to the end faces Ea of the first region A in the stacking direction D1 are arranged alternately along the longitudinal direction D2 and the width direction D3. In other words, in the sealed portion 1a of the package 1C, the stepped portions Ec are formed in a staggered pattern when viewed from the stacking direction D1, and the end faces of the laminate 10 in the stacking direction D1 have an embossed shape in which the end faces Ea and Eb are arranged alternately.

[0140] The total length Q of the second region B along the longitudinal direction D2 and the width direction D3 of the packaging body 1C is the total length of the second region B formed in a staggered pattern along the longitudinal direction D2 and the width direction D3.

[0141] As described above, in this embodiment, the seal portion 1a of the laminate 10 having a two-layer structure includes a first region A and a second region B. The end face Eb of the second region B in the stacking direction D1 is recessed relative to the end face Ea of the first region A in the stacking direction D1. The thickness P2 of the sealant layer 6 in the second region B is smaller than the thickness P1 of the sealant layer 6 in the first region A. This makes the second region B less permeable to moisture than the first region A. Furthermore, the thickness P1 of the sealant layer 6 in the first region A is larger than the thickness P2 of the sealant layer 6 in the second region B. This provides the first region A with sufficient sealing strength compared to the second region B. Therefore, it is possible to suppress moisture permeation through the sealant layer 6 while ensuring the sealing strength of the sealant layer 6. Furthermore, because moisture permeation through the sealant layer 6 can be suppressed, the water vapor barrier properties required for an all-solid-state battery (power storage device 30) can be imparted.

[0142] In this embodiment, the end face Eb of the second region B in the stacking direction D1 has a recessed, stepped or substantially stepped shape relative to the end face Ea of the first region A in the stacking direction D1. Therefore, by using seal bars 41 to 43 having a simple structure to thermally seal the sealant layers 6 of the two-layer laminate 10, the end face Eb of the second region B in the stacking direction D1 can be recessed relative to the end face Ea of the first region A in the stacking direction D1. This allows for reduced manufacturing costs.

[0143] In this embodiment, the second region B is disposed at the outer end of the sealed portion 1a in the longitudinal direction D2 and width direction D3 perpendicular to the stacking direction D1, or at the center of the sealed portion 1a in the longitudinal direction D2 and width direction D3. Therefore, the second region B is formed at a position away from the electricity storage device 30. This allows the seal strength of the sealed portion 1a on the electricity storage device 30 side to be maintained. In addition, moisture that has penetrated from outside the package 1 can be quickly brought into contact with the second region B. This further suppresses moisture permeation through the sealant layer 6.

[0144] In this embodiment, the total length Q of the second region B along the longitudinal direction D2 and width direction D3 perpendicular to the stacking direction D1 is 2 mm or more. Therefore, the length of the second region B is sufficiently ensured, so that moisture that has penetrated the sealant layer 6 can travel a longer distance to reach the electricity storage device 30. This makes it possible to reliably suppress moisture permeation through the sealant layer 6.

[0145] In this embodiment, the thickness P1 of the first region A is 60 μm to 150 μm, and the thickness P2 of the second region B is 45 μm to 100 μm. Therefore, the second region B is even more resistant to moisture penetration than the first region A. Furthermore, the first region A can obtain a more sufficient seal strength than the second region B.

[0146] In this embodiment, the sealant layer 6 is made of a material whose main component is a thermoplastic resin. Therefore, the sealant layer 6 softens when heated and hardens when cooled. As a result, the sealant layers 6 of the two-layer laminate 10 adhere to each other by thermal fusion, forming a seal portion 1a with excellent sealing properties.

[0147] In this embodiment, the metal adhesive layer 5 is disposed between the sealant layer 6 and the barrier layer 4. Therefore, the metal adhesive layer 5 promotes adhesion between the sealant layer 6 and the barrier layer 4. This improves the strength and durability of the laminate 10.

[0148] In this embodiment, the metal adhesive layer 5 is formed from a material whose main component is a thermoplastic resin. Therefore, the metal adhesive layer 5 softens when heated and hardens when cooled. In this manner, the metal adhesive layer 5 has the same function as the sealant layer 6. Therefore, the metal adhesive layer 5 and the sealant layer 6 of the two-layer laminate 10 are adhered to each other by thermal fusion, forming a seal portion 1a with excellent sealing properties.

[0149] In this embodiment, the metal adhesive layer 5 contains an acid-modified polyolefin or an acid-modified elastomer. Therefore, the metal adhesive layer 5 has good adhesion to the metal surface. This forms a strong bond between the sealant layer 6 and the barrier layer 4. Therefore, peeling between the sealant layer 6 and the barrier layer 4 can be suppressed.

[0150] The present disclosure is not limited to the above-described embodiment. For example, in the above-described embodiment, the second region B is disposed at the outer end of the seal portion 1a in the longitudinal direction D2 and the width direction D3, but is not particularly limited to such a configuration. For example, the second region B may be disposed at the inner end (on the side of the power storage device 30) of the seal portion 1a in the longitudinal direction D2 and the width direction D3. Even in this case, moisture permeation can be suppressed in the second region B as in the above-described embodiment.

[0151] In the above embodiment, the end face Eb of the second region B in the stacking direction D1 has a stepped or substantially stepped recessed shape relative to the end face Ea of the first region A in the stacking direction D1, but this is not limited to such a shape. For example, the end face Eb of the second region B in the stacking direction D1 may have a U-shaped or V-shaped cross section recessed relative to the end face Ea of the first region A in the stacking direction D1.

[0152] In the above embodiment, a package for containing a power storage device 30 has been illustrated. However, the package may contain contents other than a power storage device. For example, a fire-extinguishing film may be contained in the package instead of a power storage device. The fire-extinguishing film is a film that exhibits a fire-extinguishing function in response to heat during a fire. By containing the fire-extinguishing film in a gas-barrier laminate, the fire-extinguishing agent contained in the fire-extinguishing film can be prevented from deliquescing due to moisture in the atmosphere. The fire-extinguishing film, for example, includes a fire-extinguishing agent layer containing a fire-extinguishing agent and a resin film supporting the fire-extinguishing agent layer. The thickness of the fire-extinguishing agent layer is, for example, 30 to 600 μm. The thickness of the resin film is, for example, 5 to 100 μm. The overall thickness of the fire-extinguishing film is, for example, 35 to 800 μm. When the content is a fire-extinguishing film, the thickness P1 of the sealant layer 6 in the first region A is, for example, 35 μm to 90 μm. The thickness P2 of the sealant layer 6 in the second region B is, for example, 25 μm to 60 μm.

[0153] The extinguishing agent used has four fire-extinguishing elements (removal action, cooling action, suffocation action, and negative catalytic action) depending on the fire to be extinguished. The extinguishing agent contains at least one salt of an organic salt and an inorganic salt. The organic salt and the inorganic salt may be used alone or in combination of two or more. Examples of organic salts that function as extinguishing agents include potassium salts, sodium salts, and ammonium salts. From the viewpoint of usefulness in the negative catalytic effect, potassium salts are preferably used as the organic salt. Examples of organic potassium salts include potassium acetate, potassium citrate (monopotassium citrate, dipotassium citrate, tripotassium citrate), potassium tartrate, potassium lactate, potassium oxalate, and potassium maleate, among other potassium carboxylates. Among these, examples of organic potassium salts that are deliquescent include potassium acetate, potassium citrate, potassium tartrate, and potassium lactate. Among these, potassium citrate can be used from the viewpoint of reaction efficiency of the negative catalytic effect of combustion.

[0154] Examples of inorganic salts that function as fire extinguishing agents include potassium salts and sodium salts. From the viewpoint of usefulness in the negative catalytic effect, potassium salts can be preferably used as the inorganic salt. Examples of inorganic potassium salts include potassium tetraborate, potassium carbonate, potassium hydrogen carbonate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate. Among these, examples of inorganic potassium salts that are deliquescent include potassium carbonate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate. Among these, potassium carbonate can be used from the viewpoint of reaction efficiency of the negative catalytic effect of combustion.

[0155] The invention according to the present disclosure will be described in more detail below using examples, but the invention according to the present disclosure is not limited to the following examples.

[0156] <Base layer> A 25 μm thick nylon film (manufactured by Toyobo Co., Ltd., product name: Harden N112) and a 25 μm thick polyethylene terephthalate film (manufactured by Toray Industries, Inc., product name: Lumirror S10) were prepared as resin films for the base layer. One side of the polyethylene terephthalate film was subjected to a corona treatment.

[0157] <First adhesive> A polyester polyol resin (manufactured by Mitsui Chemicals, Inc., product name Takelac A-515 (solid content concentration 50% by mass)) was prepared as the base agent. An isocyanate compound (manufactured by Mitsui Chemicals, Inc., product name Takenate D-140N (solid content concentration 74% by mass)) was prepared as the curing agent. The solid content mass ratio of base agent:curing agent was adjusted to 80:20, and the total solid content was adjusted to 20%.

[0158] <Metal Foil Layer (Thickness: 40 μm)> A soft aluminum foil (manufactured by Toyo Aluminum Co., Ltd., "8079 material") that had been subjected to a pure baking and degreasing treatment was prepared.

[0159] <Metal Adhesive Layer> A random polypropylene-based acid-modified polypropylene resin composition (manufactured by Mitsui Chemicals, Inc., trade name QF551) was prepared.

[0160] <Sealant Layer (for Extrusion Lamination)> A polypropylene-polyethylene random copolymer (manufactured by Prime Polymer Co., Ltd., trade name F744NP) was prepared.

[0161] <Second adhesive> An acid-modified polyolefin resin (manufactured by Toyobo Co., Ltd., product name: TD-15B) was prepared as the base agent. An isocyanate compound (manufactured by Mitsui Chemicals, Inc., product name: Takenate D-140N (solid content concentration: 74 mass%)) was prepared as the curing agent. The solid content mass ratio of base agent:curing agent was adjusted to 90:10, and the total solid content was adjusted to 10%.

[0162] <Sealant Layer (for Dry Lamination)> As the sealant layer, an 80 μm thick polypropylene film (manufactured by Okamoto Corporation, product name: ET), a 50 μm thick PET film (manufactured by Toyobo Co., Ltd., product name: DE046), and a 50 μm thick polybutylene terephthalate film (manufactured by Kojin Co., Ltd., product name: Boblet CF) were prepared.

[0163] Example 1: A metal foil layer (40 μm) was attached to the nylon film (25 μm) using a dry lamination technique with a first adhesive to form a first adhesive layer. Specifically, the first adhesive was applied to the substrate layer so that the thickness of the first adhesive after drying was 4 μm. The first adhesive was dried at 80°C for 1 minute, and then the substrate layer and the metal foil layer were attached together. This was followed by aging at 60°C for 6 days. As a result, a first laminate having a layer structure of substrate layer / first adhesive layer / metal foil layer was obtained.

[0164] A metal adhesive layer and a sealant layer (for extrusion lamination) were formed in this order on the metal foil surface of the first laminate by co-extrusion using an extrusion laminator. The thickness of the metal adhesive layer in the lamination direction D1 was 23 μm. The thickness of the polypropylene-polyethylene random copolymer layer (sealant layer) in the lamination direction D1 was 57 μm. Since the metal adhesive layer also served as a sealant layer, the total thickness of the sealant layer was 80 μm. As a result, a second laminate (exterior material) having a layer structure of base layer / first adhesive layer / metal foil layer / metal adhesive layer / sealant layer was obtained.

[0165] The following describes a method for producing and sealing the package 1. The package 1 is formed by folding one laminate 10 in half so that the base layer 2 is the layer farthest from the electricity storage device 30 and the sealant layer 6 is the layer closer to the electricity storage device 30, and then heat-sealing the peripheral edges of the laminate 10. However, the package 1 may also be formed by stacking two laminates 10 together and heat-sealing the peripheral edges of the laminates 10 together.

[0166] A seal bar 41 was used for the heat fusion. The width of the seal bar 41 in the width direction D3 was 10 mm. This heat fusion refers to the first pressing. The first pressing was performed at a temperature of 200°C, a pressing pressure of 0.25 MPa, and a pressing time of 2 seconds.

[0167] The second pressing was performed at a temperature of 200° C., a pressure of 0.5 MPa, and a pressing time of 2.5 seconds. The thickness of the sealant layer 6 in the first region A in the stacking direction D1 was 148 μm. The thickness of the sealant layer 6 in the second region B in the stacking direction D1 was 98 μm.

[0168] The method for measuring the seal strength will be described. The seal strength was measured in a room temperature (25°C) environment at a tensile speed of 50 mm / min. The seal strength was measured by performing a T-peel test using a tensile tester (manufactured by Shimadzu Corporation) to peel the package 1 from the chemically treated aluminum foil. The seal strength (burst strength) was judged from the measured seal strength. As a judgment criterion, a seal strength of 70 N / 10 mm or more was considered to be pass.

[0169] The method for measuring moisture permeability will be described. Two pieces of the prepared package 1 were cut out, and the sealant layers 6 were placed facing each other. The three sides were heat-sealed to make the package size 100 mm x 45 mm. 3 g of ethylene glycol was injected through the open side, and the open side was heat-sealed to close the package. The package was then left for 7 days in an environment of 80°C and 90% RH (relative humidity).

[0170] Thereafter, the amount of water contained in the encapsulated ethylene glycol was measured using a Karl Fischer moisture meter, and the amount of water permeated was calculated from the measured amount of water content. The moisture barrier property was evaluated based on the obtained amount of water. The unit of the concentration of water contained in ethylene glycol was [ppm]. A concentration of the obtained amount of water of 250 ppm or less was considered to be acceptable.

[0171] In Example 1, the thickness of the sealant layer 6 in the stacking direction D1 of one laminate 10 before the first pressing was 80 μm. In the heat-sealed sealant layer 6, the thickness of the sealant layer 6 in the first region A after the second pressing was 148 μm. The thickness of the sealant layer 6 in the second region B after the second pressing was 98 μm. The thicknesses of the sealant layer 6 in the first region A and the second region B are the thicknesses of the sealant layer 6 in the stacking direction D1 of two laminates 10. The length of the first region A in the longitudinal direction D2 and the width direction D3 was 8 mm. The length of the second region B in the longitudinal direction D2 and the width direction D3 was 2 mm. In Examples 2 and onward, the sealing conditions, pressure, and pressing time were appropriately adjusted compared to Example 1. Explanation of conditions overlapping with Example 1 will be omitted.

[0172] In Example 2, the thickness of the sealant layer 6 in the first region A after the second pressing was set to 112 μm. The thickness of the sealant layer 6 in the second region B after the second pressing was set to 81 μm.

[0173] In Example 3, the thickness of the sealant layer 6 in the first region A after the second pressing was set to 80 μm. The thickness of the sealant layer 6 in the second region B after the second pressing was set to 66 μm.

[0174] Example 4 In Example 4, the thickness of the sealant layer 6 in the lamination direction D1 of one laminate 10 before the first pressing was set to 50 μm. The thickness of the sealant layer 6 in the first region A after the second pressing was set to 65 μm. The thickness of the sealant layer 6 in the second region B after the second pressing was set to 46 μm.

[0175] Example 5 In Example 5, the thickness of the sealant layer 6 in the first region A after the second pressing was 115 μm. The thickness of the sealant layer 6 in the second region B after the second pressing was 82 μm. The length of the first region A in the longitudinal direction D2 and the width direction D3 was 5 mm. The length of the second region B in the longitudinal direction D2 and the width direction D3 was 5 mm.

[0176] <Comparative Example 1> In Comparative Example 1, the second pressing was not performed, and the second region B was not formed. The thickness of the sealant layer 6 in the first region A was set to 144 μm. The length of the first region A in the longitudinal direction D2 and the width direction D3 was set to 10 mm.

[0177] <Comparative Example 2> In Comparative Example 2, the second pressing was not performed, and the second region B was not formed. The thickness of the sealant layer 6 in the first region A was set to 112 μm. The length of the first region A in the longitudinal direction D2 and the width direction D3 was set to 10 mm.

[0178] <Comparative Example 3> In Comparative Example 3, the outer portions of the laminate in the longitudinal direction D2 or width direction D3 were inclined relative to the horizontal direction along the longitudinal direction D2 or width direction D3 during heat sealing of the package. This laminate was inclined so that the thickness in the lamination direction D1 gradually decreased toward the outside in the longitudinal direction D2 and width direction D3. The thickest portion of the sealant layer 6 of this laminate was 140 μm. The thinnest portion of the sealant layer 6 of this laminate was 95 μm.

[0179] Table 1 shows the evaluation results for Examples 1 to 5 and Comparative Examples 1 to 3. In Examples 1 to 5, the moisture concentration was 250 ppm or less, and the moisture permeation amount was smaller than that of Comparative Examples 1 to 3. In addition, in Examples 1 to 5, the seal strength was 70 N / 10 mm or more.

[0180] Example 6 A second adhesive layer and a sealant layer (polypropylene film: 80 μm) were laminated in this order on the metal foil of a first laminate obtained in the same manner as in Example 1. Specifically, the second adhesive was applied to the metal foil of the first laminate so that the thickness after drying was 4 μm. The second adhesive was dried at 80°C for 1 minute and then attached to the sealant layer. The laminate was then aged at 60°C for 6 days. As a result, a second laminate (exterior material) having a layer structure of base layer / first adhesive layer / metal foil layer / second adhesive layer / sealant layer was obtained. In Example 6, the thickness of the sealant layer 6 in the first region A after the second pressing was 110 μm. The thickness of the sealant layer 6 in the second region B after the second pressing was 78 μm. The length of the first region A in the longitudinal direction D2 and width direction D3 was 8 mm. The length of the second region B in the longitudinal direction D2 and width direction D3 was 2 mm.

[0181] Example 7 A second laminate was produced in the same manner as in Example 6, except that a 50 μm-thick polybutylene terephthalate film was used as the sealant layer. In Example 7, the thickness of the sealant layer 6 in the first region A after the second pressing was 81 μm. The thickness of the sealant layer 6 in the second region B after the second pressing was 58 μm. The length of the first region A in the longitudinal direction D2 and width direction D3 was 8 mm. The length of the second region B in the longitudinal direction D2 and width direction D3 was 2 mm.

[0182] Example 8 A second laminate was produced in the same manner as in Example 6, except that a 25 μm thick PET film was used as the resin film constituting the base layer. In Example 8, the thickness of the sealant layer 6 in the first region A after the second pressing was 112 μm. The thickness of the sealant layer 6 in the second region B after the second pressing was 81 μm. The length of the first region A in the longitudinal direction D2 and width direction D3 was 8 mm. The length of the second region B in the longitudinal direction D2 and width direction D3 was 2 mm.

[0183] Example 9 A second laminate was produced in the same manner as in Example 8, except that a 50 μm thick PET film was used as the sealant layer. In Example 9, the thickness of the sealant layer 6 in the first region A after the second pressing was 85 μm. The thickness of the sealant layer 6 in the second region B after the second pressing was 60 μm. The length of the first region A in the longitudinal direction D2 and width direction D3 was 8 mm. The length of the second region B in the longitudinal direction D2 and width direction D3 was 2 mm.

[0184] Example 10 A second laminate was produced in the same manner as in Example 8, except that a 50 μm thick PBT film was used as the resin film constituting the sealant layer. In Example 10, the thickness of the sealant layer 6 in the first region A after the second pressing was 82 μm. The thickness of the sealant layer 6 in the second region B after the second pressing was 57 μm. The length of the first region A in the longitudinal direction D2 and width direction D3 was 8 mm. The length of the second region B in the longitudinal direction D2 and width direction D3 was 2 mm.

[0185] Comparative Example 4 A second laminate was produced in the same manner as in Example 9, except that the second region B was not provided. In Comparative Example 4, the thickness of the sealant layer 6 in the first region A after the first pressing was set to 84 μm. The length of the first region A in the longitudinal direction D2 and the width direction D3 was set to 10 mm.

[0186] Table 2 shows the evaluation results for Examples 6 to 10 and Comparative Example 4. Examples 7 and 10 are examples in which a PBT film was used as the film constituting the sealant layer, and Example 9 is an example in which a PET film was used. Even when these polyester resin films were used as the film constituting the sealant layer, it was shown that by providing a second region in the sealed portion, moisture permeation could be suppressed and a decrease in seal strength could be suppressed compared to when a second region was not provided in the sealed portion (Comparative Example 4).

[0187]

[0188] 1, 1A, 1B, 1C...packaging body, 1a...sealed portion, 1b...storage portion, 2...substrate layer, 3...adhesive layer, 4...barrier layer, 5...metal adhesive layer, 6...sealant layer, 10...laminated body, 30...energy storage device, A...first region, B...second region, D1...stacking direction, D2...longitudinal direction, D3...width direction, Ea...end surface, Eb...end surface, Ec...step portion, P1...thickness, P2...thickness.

Claims

1. A packaging for exteriorly packaging an electricity storage device, the packaging comprising a laminate having at least a base layer, an adhesive layer, a barrier layer, and a sealant layer laminated in this order, the laminate comprising: a storage section for storing the electricity storage device using the laminate; and a sealing section that is positioned outside the storage section in a direction perpendicular to the stacking direction of the laminate, the laminate having a two-layer structure with the sealant layers facing each other, and the sealant layers being heat-sealed together, the sealing section having a first region and a second region in which the sealant layer is thinner than the first region, the end face in the stacking direction of the second region having a recessed shape relative to the end face in the stacking direction of the first region.

2. A package according to claim 1, wherein the end face of the second region in the stacking direction has a stepped or substantially stepped recessed shape relative to the end face of the first region in the stacking direction.

3. A packaging body as described in claim 1, wherein the second region is positioned at the outer end of the seal portion in a direction perpendicular to the stacking direction or at the center of the seal portion in a direction perpendicular to the stacking direction.

4. The package according to claim 1, wherein the total length of the second region along a direction perpendicular to the stacking direction is 2 mm or more.

5. The package according to claim 1, wherein the thickness of the first region is 60 μm to 150 μm, and the thickness of the second region is 45 μm to 100 μm.

6. The package according to claim 1, wherein the sealant layer is formed from a material whose main component is a thermoplastic resin.

7. The package of claim 1, wherein a metallic adhesive layer is disposed between the sealant layer and the barrier layer.

8. The package according to claim 7, wherein the metal adhesive layer is formed from a material whose main component is a thermoplastic resin.

9. The package of claim 8, wherein the metal adhesive layer comprises an acid-modified polyolefin or an acid-modified elastomer.

10. The package according to claim 1, wherein the power storage device is an all-solid-state battery.

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