Exterior material for power storage device and power storage device

Abstract

To provide an exterior material for a power storage device and a power storage device which can improve the size stability of a seal part formed by using an exterior material even after a heat impact is applied.SOLUTION: The exterior material for a power storage device includes at least a base material layer, a barrier layer, an adhesive layer, and a sealant layer in that order. The amount of transmission of hydrogen sulfide in the thickness direction of the sealant layer and the adhesive layer at the temperature of 100°C is 3.7×10-15 to 1.8×10-12[(mol.m) / (m2.s.Pa)].SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an exterior material for an electricity storage device and an electricity storage device. [Background technology]

[0002] Known examples of power storage devices include secondary batteries such as lithium ion batteries, nickel metal hydride batteries, and lead storage batteries, as well as electrochemical capacitors such as electric double layer capacitors. Due to the miniaturization of portable devices or the limitations of installation space, there is a demand for further miniaturization of power storage devices, and lithium ion batteries with high energy density have attracted attention. Metallic cans have traditionally been used as exterior materials for lithium ion batteries, but multilayer films that are lightweight, have high heat dissipation properties, and can be produced at low cost have come to be used.

[0003] A lithium ion battery using the above multilayer film as an exterior material is called a laminated lithium ion battery. A laminated lithium ion battery includes an electric storage element having a positive electrode, a liquid electrolyte, and a negative electrode, and an exterior bag that houses the electric storage element, and prevents moisture from penetrating into the battery. The exterior bag has an exterior material, and the exterior material includes a base layer, a barrier layer, an adhesive layer, and a sealant layer in this order. The exterior material covers the electric storage element with the sealant layer facing inward and the base layer facing outward. A laminated lithium ion battery is manufactured, for example, by forming a recess in a part of the exterior material by cold molding, housing the electric storage element in the recess, folding back the remaining part of the exterior material, and sealing the edge portion by heat sealing (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-101765 A Summary of the Invention [Problem to be solved by the invention]

[0005] Meanwhile, research and development of an electricity storage device called an all-solid-state battery has been conducted as a next-generation battery of lithium-ion batteries. The all-solid-state battery may be housed in a device storage container. The all-solid-state battery includes an exterior bag that houses an electricity storage element, and the exterior bag is formed using an exterior material so as to have a seal part around the bag body. The seal part is a part where the exterior materials are integrated by contacting the sealant layers with each other and heat sealing them. In the device storage container, the electricity storage element is restrained in a pressurized state via the exterior bag in order to increase the conductivity of the all-solid-state battery. At this time, in order to operate the all-solid-state battery efficiently, it is desirable to apply pressure uniformly to the electricity storage element.

[0006] However, it was confirmed that the sealed portion of the all-solid-state battery shrinks after it is subjected to a thermal shock caused by the surrounding temperature rising and falling between -40°C and 100°C. When the sealed portion shrinks, the gap between the inner wall of the device storage container and the sealed portion becomes larger, which makes the all-solid-state battery more likely to move due to vibrations or the like inside the device storage container. If the all-solid-state battery is displaced from its fixed position, it is thought that uniform pressure cannot be applied to the all-solid-state battery, resulting in a decrease in output efficiency.

[0007] Even if the power storage device is not an all-solid-state battery, it is not desirable for the power storage device to shift from its fixed position within the device storage container due to vibration or the like, since this may cause wiring or the like connected to the power storage device to be broken.

[0008] Therefore, there has been a demand for an exterior material for an electricity storage device that can improve the dimensional stability of a seal portion formed using the exterior material even after being subjected to thermal shock.

[0009] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide an exterior material for an electricity storage device and an electricity storage device that can improve the dimensional stability of a sealing portion formed using the exterior material even after being subjected to thermal shock. [Means for solving the problem]

[0010] The inventors of the present disclosure have conducted intensive research to solve the above problems. In order to improve the dimensional stability of the seal portion formed using the exterior material after being subjected to thermal shock, it is important that the seal portion disperses the stress acting in the shrinking direction due to thermal shock (i.e., stress relaxation). On the other hand, it has been confirmed that if the seal portion is too soft (if the stress relaxation is too high), it cannot maintain its shape at high temperatures and shrinks, so the hardness of the seal portion is also important. In other words, in order to improve the dimensional stability of the seal portion due to thermal shock, it is important to balance the "hardness" for maintaining a certain shape and the "stress relaxation". Therefore, the inventors of the present disclosure have conducted intensive research to balance the "hardness" and "stress relaxation" in the seal portion. As a result, the inventors of the present disclosure discovered that in an exterior material for an electricity storage device comprising a base layer, a barrier layer, an adhesive layer, and a sealant layer in this order, by setting the hydrogen sulfide permeation amount at 100°C in the thickness direction of the sealant layer and the adhesive layer within a specific range, the dimensional stability of the sealed portion is improved even after being subjected to thermal shock, leading to the present disclosure.

[0011] That is, one aspect of the present disclosure is a composite material having at least a base layer, a barrier layer, an adhesive layer, and a sealant layer in this order, and a hydrogen sulfide permeation amount in a thickness direction of the sealant layer and the adhesive layer at 100° C. is 3.7×10 -15 ~1.8×10 -12 [(mol m) / (m 2 The present invention provides an exterior material for an electricity storage device having a thermal conductivity of 1.0 s Pa.

[0012] The exterior material for an electricity storage device can improve the dimensional stability of a seal portion formed using the exterior material even after being subjected to thermal shock. The inventors of the present disclosure speculate as follows about the reason why such an effect is achieved. That is, first, it is believed that the permeability of hydrogen sulfide decreases when the sealant layer and adhesive layer are too hard, and increases when they are too soft (the stress relaxation property becomes too high). Therefore, the inventors of the present disclosure speculate that by specifying the hydrogen sulfide permeation amount of the sealant layer and the adhesive layer within an appropriate range, the "hardness" and "stress relaxation property" in the sealed portion are balanced, and the shrinkage of the sealed portion is suppressed and the dimensional stability of the sealed portion is improved, even after the sealed portion is subjected to a thermal shock. In particular, in a high temperature environment of 100°C, the molecules constituting the sealant layer and the adhesive layer become more mobile, and the amount of hydrogen sulfide permeation increases, so that the amount of hydrogen sulfide permeation at 100°C is thought to be more likely to reflect the degree of hardness and stress relaxation property of the sealed portion.

[0013] In the exterior material for an electricity storage device, when a cross section of the sealant layer is observed with a scanning electron microscope, a sea-island structure having a sea portion and island portions present in the sea portion is preferably observed. In this case, even if the sealed portion formed using the exterior material attempts to shrink after being subjected to thermal shock, the shrinkage stress is efficiently mitigated at the interface between the sea and island parts of the sea-island structure, making it easier to improve the dimensional stability of the sealed portion even after it has been subjected to thermal shock.

[0014] In the exterior packaging material for an electricity storage device, the sealant layer may contain a base resin (A) including a polyolefin-based resin.

[0015] In the exterior packaging material for an electricity storage device, the polyolefin-based resin preferably contains a polypropylene-based resin and a polyethylene-based resin. In this case, the polypropylene-based resin imparts hardness to the sealed portion while the polyethylene-based resin imparts softness (stress relaxation properties) to the sealed portion, so that even if the sealed portion attempts to shrink after being subjected to thermal shock, the shrinkage of the sealed portion is suppressed.

[0016] In the exterior packaging material for an electricity storage device, it is preferable that the sealant layer further contains a compatibilizer (B) having a portion compatible with the polypropylene-based resin and a portion compatible with the polyethylene-based resin. In this case, since the compatibilizer (B) has a portion compatible with the polypropylene resin and a portion compatible with the polyethylene resin, the polyethylene resin is easily dispersed in the polypropylene resin, and the polyethylene resin is finely dispersed in the polypropylene resin. As a result, even if the sealed portion tries to shrink after being subjected to a thermal shock, the shrinkage stress is effectively alleviated, and the shrinkage of the sealed portion is effectively suppressed.

[0017] In the exterior packaging material for an electricity storage device, the compatibilizer (B) preferably contains at least one of a block copolymer (B1) of polypropylene and polyethylene, and a block copolymer (B2) of polyethylene and polyethylenebutylene. In this case, the polyethylene resin is effectively dispersed in the polypropylene resin, and the polyethylene resin is more finely dispersed in the polypropylene resin, so that even if the sealed portion tries to shrink after being subjected to a thermal shock, the shrinkage stress is more effectively alleviated, and the shrinkage of the sealed portion is more effectively suppressed.

[0018] Another aspect of the present disclosure provides an electricity storage device comprising an electricity storage element and an outer bag that houses the electricity storage element, the outer bag being formed using the above-mentioned outer casing material for an electricity storage device so as to have a bag body and a seal portion provided on the bag body. According to the above-mentioned electricity storage device, the dimensional stability of the sealed portion of the outer bag is improved even after the sealed portion is subjected to a thermal shock. Therefore, even after the electricity storage device is stored in a device storage container and is subjected to a thermal shock, the gap between the sealed portion of the outer bag of the electricity storage device and the inner surface of the device storage container is unlikely to become large. As a result, even if vibration or the like is applied, the electricity storage device is unlikely to shift from its fixed position in the device storage container. As a result, when wiring or the like is connected to the electricity storage device, breakage of the wiring or the like is suppressed.

[0019] The power storage device may be an all-solid-state battery. In this case, when the electricity storage device is stored in a pressurized state in the device storage container, the electricity storage device is unlikely to shift from its fixed position in the device storage container even when subjected to vibration, etc. Therefore, uniform pressure is maintained on the electricity storage device in the device storage container, and a decrease in the output efficiency of the all-solid-state battery as the electricity storage device is suppressed. Effect of the Invention

[0020] According to the present disclosure, there is provided an exterior material for an electricity storage device, which can improve the dimensional stability of a seal portion formed using the exterior material even after being subjected to thermal shock, and an electricity storage device. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic cross-sectional view of an exterior material for an electricity storage device according to an embodiment of the present disclosure. [Diagram 2] 2 is a schematic cross-sectional view showing a modified example of the exterior material for an electricity storage device in FIG. 1. [Diagram 3] FIG. 1 is a perspective view illustrating an electricity storage device according to an embodiment of the present disclosure. [Figure 4] 4 is a partial cross-sectional view showing a state in which the electricity storage device of FIG. 3 is housed in a device housing container. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and duplicated explanations will be omitted. In addition, the dimensional ratios of the drawings are not limited to the ratios shown in the drawings.

[0023] [Exterior materials for energy storage devices] Fig. 1 is a cross-sectional view that shows a schematic diagram of an exterior material for an electricity storage device according to an embodiment of the present disclosure. As shown in Fig. 1, an exterior material for an electricity storage device (hereinafter, also simply referred to as "exterior material") 10 of this embodiment is an exterior material used for an electricity storage device, and includes, in this order, a base layer 11, a first adhesive layer 12a, a barrier layer 13, an adhesive resin layer 15 as an adhesive layer, and a sealant layer 16. Here, the hydrogen sulfide permeation amount at 100°C in the thickness direction of the sealant layer 16 and the adhesive resin layer 15 is 3.7 x 10 -15 ~1.8×10 -12 [(mol m) / (m 2 s·Pa).

[0024] According to this exterior material 10, it is possible to improve the dimensional stability of the seal portion formed using the exterior material even after it is subjected to thermal shock.

[0025] The barrier layer 13 has a first corrosion prevention treatment layer 14a on the substrate layer 11 side, and a second corrosion prevention treatment layer 14b on the sealant layer 16 side. Furthermore, when the exterior material 10 is used as an exterior bag for an electricity storage device, the base material layer 11 is the outermost layer and the sealant layer 16 is the innermost layer in the exterior material 10. That is, the exterior material 10 is used with the base material layer 11 facing the outside of the electricity storage device and the sealant layer 16 facing the inside of the electricity storage device.

[0026] Each layer constituting the packaging material 10 will now be described in detail.

[0027] <Base material layer> The base layer 11 imparts heat resistance in a sealing process when manufacturing an electricity storage device and plays a role in suppressing the occurrence of pinholes that may occur during molding and distribution. In particular, in the case of an exterior material for a large-scale electricity storage device, the base layer 11 can also impart scratch resistance, chemical resistance, insulation, and the like.

[0028] The base layer 11 is preferably a layer formed of 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, acetyl cellulose resin, or the like.

[0029] Among these resins, polyester resin and polyamide resin are preferable for the base layer 11 because of their excellent moldability. Examples of polyester resin include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Examples of polyamide resin include nylon 6, nylon 6,6, a copolymer of nylon 6 and nylon 6,6, nylon 6, nylon 9T, nylon 10, polymetaxylylene adipamide (MXD6), nylon 11, and nylon 12.

[0030] The substrate layer 11 may be in the form of a stretched or unstretched film, or in the form of a coating film. The substrate layer 11 may be a single layer or a multilayer. When the substrate layer 11 is a multilayer, it is formed by laminating layers made of different resins. When the substrate layer 11 is in the form of a film, it may be a co-extruded film or a laminated film using an adhesive. When the substrate layer 11 is a coating film, it may be a coating film obtained by coating a composition for forming a coating film multiple times. The substrate layer 11 may be a multilayer film by combining a film and a coating film.

[0031] When the above-mentioned resin is used in the form of a film, the base layer 11 is preferably a biaxially stretched film. In this case, the moldability of the packaging material 10 is improved. Examples of the stretching method for the biaxially stretched film include a sequential biaxial stretching method, a tubular biaxial stretching method, and a simultaneous biaxial stretching method. From the viewpoint of obtaining better deep-draw moldability, the biaxially stretched film is preferably a film stretched by a tubular biaxial stretching method.

[0032] The thickness of the substrate layer 11 is preferably 6 to 100 μm, more preferably 10 to 75 μm, and even more preferably 10 to 50 μm. When the thickness of the substrate layer 11 is 6 μm or more, the pinhole resistance and insulating properties of the packaging material 10 tend to be improved. When the thickness of the substrate layer 11 is 100 μm or less, the total thickness of the packaging material 10 can be reduced.

[0033] In addition, it is preferable that the base material layer 11 has a melting temperature higher than that of the sealant layer 16. When the sealant layer 16 has a multi-layer structure, the melting temperature of the sealant layer 16 means the melting temperature of the layer with the highest melting temperature. By making the base material layer 11 have a melting temperature higher than that of the sealant layer 16, it is possible to prevent the appearance of the packaging material 10 from deteriorating due to melting of the base material layer 11 (outer layer) during heat sealing.

[0034] Melting temperature T of the base layer 11 11 and the melting temperature T of the sealant layer 16 16 The difference (T 11 -T 16 ) is preferably 20° C. or more. When this temperature difference is 20° C. or more, deterioration of the appearance of the packaging material 10 due to heat sealing can be more sufficiently suppressed.

[0035] The melting temperature of the base layer 11 is preferably 240° C. or higher. However, the melting temperature of the base layer 11 is preferably 350° C. or lower. Examples of resin films that can be used as the base layer 11 and have a melting temperature in the above range include nylon films, polyester films such as PET films, polyamide films, and polyphenylene sulfide films (PPS films). The base layer 11 may be a commercially available film, or may be formed by coating (application of a coating liquid and drying). The base layer 11 may be formed by coating a thermosetting resin. Furthermore, the base layer 11 may contain, for example, various additives (for example, a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, a tackifier, etc.).

[0036] <First adhesive layer> The first adhesive layer 12a is a layer that bonds the base material layer 11 and the barrier layer 13. Specific examples of materials constituting the first adhesive layer 12a include polyurethane resins in which a bifunctional or higher isocyanate compound (polyfunctional isocyanate compound) acts as a curing agent on a base material such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol. The above-mentioned various polyols can be used alone or in combination of two or more types depending on the functions and performance required for the exterior material 10. In addition, materials constituting the first adhesive layer 12a can also be used that use an epoxy resin as a base material and a curing agent in addition to the above.

[0037] The first adhesive layer 12a is formed using an adhesive composition containing the above-mentioned base agent and curing agent. In addition, the first adhesive layer 12a may contain various other additives and stabilizers in the above-mentioned adhesive composition depending on the performance required for the adhesive layer.

[0038] The adhesive composition preferably contains at least one polyfunctional isocyanate compound selected from the group consisting of alicyclic isocyanate polymers and isocyanate polymers containing an aromatic ring in the molecular structure as a curing agent. Examples of the polyfunctional isocyanate compound include a nurate of isophorone diisocyanate, an adduct of tolylene diisocyanate, an adduct of hexamethylene diisocyanate, a biuret and a nurate of hexamethylene diisocyanate, a biuret and a nurate of tolylene diisocyanate, an adduct, a biuret and a nurate of diphenylmethane diisocyanate, and an adduct, a biuret and a nurate of xylylene diisocyanate.

[0039] As the curing agent, an alicyclic isocyanate polymer may be used in combination with an isocyanate polymer containing an aromatic ring in the molecular structure. By using these in combination, the heat resistance tends to be further improved.

[0040] From the viewpoint of further improving heat resistance, the adhesive composition preferably contains at least one polyol selected from the group consisting of polyester polyol, acrylic polyol, and polycarbonate diol. Among these, from the viewpoint of further improving heat resistance, polyester polyol is more preferable.

[0041] In the adhesive composition, the ratio (NCO / OH) of the number of isocyanate groups contained in the polyfunctional isocyanate compound to the number of hydroxyl groups contained in the polyol may be 1.5 to 40.0, or may be 15.0 to 30.0. If this ratio is 1.5 or more, the curing agents react with each other, and by-products such as urea resin and biuret resin are easily generated. Since these by-products contain active hydrogen groups, they interact with polar groups of adjacent layers, and the interfacial adhesion between the first adhesive layer 12a and the base material layer 11 and the barrier layer 13 is further improved. Therefore, the heat resistance of the packaging material 10 tends to be improved. On the other hand, if the ratio is 40.0 or less, the laminate strength of the packaging material 10 can be further improved in room temperature and high temperature environments. The adhesive composition may further include a tin-based, titanium-based, or zirconium-based urethane catalyst to accelerate curing. The adhesive composition may further include a visible curing agent or a latent curing agent. Examples of the visible curing agent or latent curing agent include amine-based compounds. The above urethane catalyst and the visible curing agent or the latent curing agent may each be used alone or in a blend of multiple types.

[0042] The thickness of the first adhesive layer 12a is not particularly limited, but from the viewpoint of obtaining the desired adhesive strength, followability, processability, etc., it is preferably, for example, 1 to 10 μm, and more preferably 2 to 7 μm.

[0043] The mass per unit area of ​​the first adhesive layer 12a is set to 2.0 to 6.0 g / m from the viewpoint of ensuring superior lamination strength both in room temperature and high temperature environments and obtaining superior deep drawability. 2 and 2.5 to 5.0 g / m 2 and 3.0 to 4.0 g / m 2 may be also possible.

[0044] <Barrier layer> The barrier layer 13 has a water vapor barrier property that prevents moisture from penetrating into the inside of the electricity storage device. The barrier layer 13 may also have extensibility for deep drawing. As the barrier layer 13, 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, and films provided with these vapor deposition films can be used. Examples of films having a vapor deposition layer include aluminum vapor deposition films and inorganic oxide vapor deposition films. These may be used alone or in combination of two or more. As the barrier layer 13, in terms of mass (specific gravity), barrier properties such as moisture resistance, processability, and cost, a metal foil is preferred, and an aluminum foil or a stainless steel foil is more preferred.

[0045] As the aluminum foil, a soft aluminum foil that has been annealed can be preferably used because it can impart the desired ductility during molding. In order to impart further pinhole resistance and ductility during molding, it is more preferable to use an aluminum foil containing iron. The iron content in the aluminum foil is preferably 0.1 to 9.0 mass%, and more preferably 0.5 to 2.0 mass%, based on 100 mass% of the aluminum foil. When the iron content is 0.1 mass% or more, an exterior material 10 having better pinhole resistance and ductility can be obtained. When the iron content is 9.0 mass% or less, an exterior material 10 having better flexibility can be obtained. As the aluminum foil, untreated aluminum foil may be used, but it is preferable to use aluminum foil that has been subjected to a degreasing treatment in order to impart corrosion resistance. When the aluminum foil is subjected to a degreasing treatment, the degreasing treatment may be performed on only one side of the aluminum foil or on both sides of the aluminum foil.

[0046] The thickness of the barrier layer 13 is not particularly limited, but taking into consideration the barrier properties, pinhole resistance, and processability, it is preferably 9 to 200 μm, and more preferably 15 to 100 μm.

[0047] <First and second corrosion prevention treatment layers> The first and second corrosion prevention treatment layers 14a, 14b are layers provided to prevent corrosion of the metal foil (metal foil layer) constituting the barrier layer 13. The first corrosion prevention treatment layer 14a serves to increase the adhesion between the barrier layer 13 and the first adhesive layer 12a. The second corrosion prevention treatment layer 14b serves to increase the adhesion between the barrier layer 13 and the adhesive resin layer 15. The first corrosion prevention treatment layer 14a and the second corrosion prevention treatment layer 14b may be layers having the same configuration, or may be layers having different configurations. The first and second corrosion prevention treatment layers 14a, 14b (hereinafter also simply referred to as "corrosion prevention treatment layers 14a, 14b") are formed, for example, by degreasing treatment, hydrothermal conversion treatment, anodizing treatment, chemical conversion treatment, or a combination of these treatments.

[0048] The degreasing treatment includes acid degreasing and alkaline degreasing. Examples of acid degreasing include a method using an inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid, or hydrofluoric acid alone or a mixture of these. In addition, in acid degreasing, it is preferable to use an acid degreasing agent in which a fluorine-containing compound such as monosodium ammonium difluoride is dissolved in the inorganic acid. In this case, the aluminum degreasing effect can be obtained, particularly when an aluminum foil is used for the barrier layer 13. Furthermore, the acid degreasing agent can form a fluoride of aluminum, which is a passive state, and is effective in terms of corrosion resistance. The alkaline degreasing method includes a method using sodium hydroxide or the like.

[0049] An example of the hydrothermal modification treatment is a boehmite treatment in which an aluminum foil is immersed in boiling water containing added triethanolamine. An example of the anodizing treatment is an alumite treatment.

[0050] The chemical conversion treatment may be of the immersion type or coating type. Examples of the immersion type chemical conversion treatment include chromate treatment, zirconium treatment, titanium treatment, vanadium treatment, molybdenum treatment, calcium phosphate treatment, strontium hydroxide treatment, cerium treatment, ruthenium treatment, and various chemical conversion treatments consisting of a mixture of these treatments. On the other hand, coating-type chemical conversion treatments include a method in which a coating agent having anticorrosive properties is applied onto the barrier layer 13 .

[0051] When forming at least a part of the corrosion prevention layer by any of these corrosion prevention treatments, namely, hydrothermal conversion treatment, anodizing treatment, and chemical conversion treatment, it is preferable to perform the above-mentioned degreasing treatment in advance. When using a degreased metal foil, such as a metal foil that has been subjected to an annealing process, as the barrier layer 13, there is no need to perform a degreasing treatment again in forming the corrosion prevention layers 14a and 14b.

[0052] The coating agent used in the spray-type chemical conversion treatment preferably contains trivalent chromium. The coating agent may also contain at least one polymer selected from the group consisting of cationic polymers and anionic polymers, which will be described later.

[0053] Among the above treatments, particularly hydrothermal conversion treatment and anodizing treatment dissolve the aluminum foil surface with a treatment agent to form aluminum compounds (boehmite, alumite) with excellent corrosion resistance. Therefore, a form in which a bicontinuous structure is formed from the barrier layer 13 using the aluminum foil to the corrosion prevention treatment layers 14a, 14b is obtained, and the above treatments are included in the definition of chemical conversion treatment. On the other hand, it is also possible to form the corrosion prevention treatment layers 14a, 14b by a pure coating method that is not included in the definition of chemical conversion treatment, as described later. For example, this method uses a sol of a rare earth element oxide such as cerium oxide having an average particle size of 100 nm or less, which has an aluminum corrosion prevention effect (inhibitor effect) and is also environmentally friendly. By using this method, it is possible to impart a corrosion prevention effect to metal foil such as aluminum foil, even with a general coating method.

[0054] Examples of the rare earth element oxide sol include sols using various solvents such as water-based, alcohol-based, hydrocarbon-based, ketone-based, ester-based, ether-based, etc. Among these, water-based sols are preferred.

[0055] In order to stabilize the dispersion of the rare earth element oxide sol, inorganic acids such as nitric acid, hydrochloric acid, phosphoric acid, etc. or their salts, and organic acids such as acetic acid, malic acid, ascorbic acid, lactic acid, etc. are usually used as dispersion stabilizers. Among these dispersion stabilizers, phosphoric acid in particular is expected to provide the following effects (1) to (4) in the exterior packaging material 10. (1) Dispersion stabilization of sol (2) Improved adhesion to the barrier layer 13 by utilizing the aluminum chelating ability of phosphoric acid (3) Imparting corrosion resistance by capturing aluminum ions (passivation) (4) The dehydration and condensation of phosphoric acid occurs easily even at low temperatures, improving the cohesive strength of the corrosion prevention treatment layers (oxide layers) 14a and 14b.

[0056] The corrosion prevention layers 14a and 14b formed from the rare earth oxide sol are aggregates of inorganic particles, and therefore may lose their cohesive strength even after the drying and curing process. Therefore, it is preferable that the corrosion prevention layers 14a and 14b in this case are compounded with an anionic polymer or a cationic polymer to compensate for the cohesive strength.

[0057] The corrosion prevention treatment layers 14a, 14b are not limited to the above-mentioned layers. For example, they may be formed using a treatment agent in which phosphoric acid and a chromium compound are mixed with a resin binder (such as aminophenol), as in the case of coating-type chromate, which is a known technology. By using this treatment agent, a layer having both corrosion prevention function and adhesion can be formed. In addition, although it is necessary to consider the stability of the coating liquid, a coating agent in which a rare earth oxide sol and a polycationic polymer or a polyanionic polymer are mixed in advance into a one-component solution can be used to form a layer having both corrosion prevention function and adhesion.

[0058] The mass per unit area of ​​the corrosion prevention layers 14a and 14b is 0.005 to 0.200 g / m2 regardless of whether the layer has a multi-layer structure or a single-layer structure. 2 It is preferable that the thickness is 0.010 to 0.100 g / m 2It is more preferable that the mass per unit area is 0.005 g / m. 2 If the mass per unit area is 0.200 g / m or more, it is easy to impart a corrosion prevention function to the barrier layer 13. 2 Even if the thickness exceeds 100 mm, the corrosion prevention function does not change much. On the other hand, when a rare earth oxide sol is used, if the coating is thick, the heat curing during drying may be insufficient, which may result in a decrease in cohesive force. The thickness of the corrosion prevention layers 14a and 14b can be calculated from their specific gravity.

[0059] From the viewpoint of easily maintaining the adhesion between the sealant layer 16 and the barrier layer 13, the corrosion prevention treatment layers 14a, 14b may be in an embodiment containing, for example, cerium oxide, 1 to 100 parts by mass of phosphoric acid or a phosphate relative to 100 parts by mass of the cerium oxide, and a cationic polymer, or may be formed by subjecting the barrier layer 13 to a chemical conversion treatment, or may be formed by subjecting the barrier layer 13 to a chemical conversion treatment and contain a cationic polymer.

[0060] <Sealant layer and adhesive resin layer> The sealant layer 16 is a layer that imparts heat-sealing sealability to the exterior material 10, and is a layer that is placed on the inside and heat-sealed (thermally fused) when the electricity storage device is assembled. The adhesive resin layer 15 is a layer that bonds the sealant layer 16 and the barrier layer 13, and contains an adhesive resin.

[0061] The hydrogen sulfide permeation amount of the sealant layer 16 and the adhesive resin layer 15 at 100°C is 3.7 x 10 -15 ~1.8×10 -12 [(mol m) / (m 2 ·s·Pa). The hydrogen sulfide permeation rate of the sealant layer 16 at 100° C. is preferably 1.8×10 -14 ~3.7×10 -13 [(mol m) / (m 2 s Pa)], and more preferably 3.3 × 10 -14 ~2.2×10 -13[(mol m) / (m 2 s·Pa).

[0062] The sealant layer 16 may contain a base resin (A) containing a polyolefin resin. The sealant layer 16 may further contain a compatibilizer (B), or may not further contain a compatibilizer (B).

[0063] The polyolefin resin may contain at least one of a polypropylene resin and a polyethylene resin, but preferably contains a polypropylene resin and a polyethylene resin. In this case, in the sealed portion formed using the exterior material 10, the polypropylene resin provides hardness while the polyethylene resin provides softness (stress relaxation), so that even if the sealed portion attempts to shrink after being subjected to a thermal shock, the shrinkage of the sealed portion is suppressed.

[0064] The polypropylene resin is a resin containing a resin obtained from a polymer monomer containing propylene, and serves to impart hardness. Examples of the polypropylene resin include homopolypropylene, block polypropylene, and random polypropylene. These may be used alone or in combination of two or more. The polypropylene resin preferably contains at least one of homopolypropylene and block polypropylene, which can impart hardness.

[0065] Polyethylene resins are resins obtained from polymerization monomers containing ethylene, and play a role in imparting softness (stress relaxation properties). Examples of polyethylene resins include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and polyethylene elastomers. These may be used alone or in combination of two or more. The polyethylene resin preferably contains a polyethylene elastomer, since it can impart softness in particular.

[0066] The polyethylene elastomer may be an elastomer having an α-olefin as a comonomer. Specifically, such a polyethylene elastomer may be a compound 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.

[0067] When a cross section of the sealant layer 16 is observed with a scanning electron microscope (hereinafter also referred to as "SEM"), it is preferable that a sea-island structure having a sea portion and islands present in the sea portion is observed. In this case, even if the seal portion formed using the packaging material 10 attempts to shrink after being subjected to thermal shock, the shrinkage stress is efficiently alleviated at the interface between the sea portion and the island portion of the sea-island structure, which makes it easier to improve the dimensional stability of the seal portion.

[0068] When the area of ​​the entire field of view observed with an SEM is taken as the reference (100%), the proportion of the island portion is not particularly limited, but from the viewpoint of further improving the dimensional stability of the sealed portion after thermal shock, it is preferably 2 to 98%, and more preferably 10 to 90%.

[0069] The content of the polypropylene resin in the sealant layer 16 is not particularly limited and may be, for example, 30 to 100 mass %. From the viewpoint of the balance between hardness and softness, however, it is preferably 50 to 95 mass %, and more preferably 70 to 90 mass %.

[0070] The content of the polyethylene resin in the sealant layer 16 is not particularly limited and may be, for example, 2 to 70 mass %. From the viewpoint of the balance between hardness and softness, however, it is preferably 5 to 50 mass %, and more preferably 10 to 30 mass %.

[0071] The compatibilizer (B) is not particularly limited as long as it has a portion compatible with polypropylene-based resins (hereinafter also referred to as a "PP-compatible portion") and a portion compatible with polyethylene-based resins (hereinafter also referred to as a "PE-compatible portion"). Specifically, examples of the compatibilizer (B) include graft copolymers in which the PP compatible portion is the main chain and the PE compatible portion is the side chain, graft copolymers in which the PE compatible portion is the main chain and the PP compatible portion is the side chain, and block copolymers in which the PP compatible portion and the PE compatible portion each exist as a block. In particular, a block copolymer in which the PP compatible portion and the PE compatible portion each exist as a block is particularly preferred from the viewpoint of improving the dispersibility of the compatibilizer (B). Examples of such a block copolymer include a block copolymer of polypropylene and polyethylene (PP-PE block copolymer) and a block copolymer of polyethylene and polyethylenebutylene (PE-PE-butylene block copolymer).

[0072] The content of the compatibilizer (B) in the sealant layer 16 is not particularly limited and may be, for example, 1 to 50 mass %. From the viewpoint of the balance between hardness and softness, however, it is preferably 2 to 30 mass %, more preferably 5 to 15 mass %, and particularly preferably 6 to 15 mass %.

[0073] The mass ratio of the compatibilizer (B) to the polyethylene resin (PE) is not particularly limited and may be, for example, PE:B=5:1 to 1:5. From the viewpoint of dispersion efficiency, however, it is preferably 2:1 to 1:4, and more preferably 1:1.1 to 1:3.

[0074] In addition to the above-mentioned base resin (A) and compatibilizer (B), the sealant layer 16 may contain other additive components as necessary, such as slip agents, antiblocking agents, antioxidants, light stabilizers, crystal nucleating agents, and flame retardants. The content of these additive components is preferably 5% by mass or less, assuming the total mass of the sealant layer 16 to be 100% by mass.

[0075] The adhesive resin layer 15 is not particularly limited as long as it contains a resin that bonds the sealant layer 16 and the barrier layer 13, and examples of such resins include acid-modified polyolefin resins.

[0076] The acid-modified polyolefin resin may be a polyolefin resin modified with maleic anhydride, carboxylic acid, sulfonic acid, or a derivative thereof. The acid-modified polyolefin resin may be, for example, a graft copolymer, a block copolymer, or a random copolymer. From the viewpoint of adhesion to the barrier layer 13, the acid-modified polyolefin resin is preferably a polyolefin resin graft-modified with maleic anhydride.

[0077] The adhesive resin layer 15 may contain various additives, as necessary, such as various compatible and incompatible elastomers, flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, crystal nucleating agents, and tackifiers.

[0078] From the viewpoint of improving the hardness of the sealed portion, the ratio of the thickness of the sealant layer 16 to the thickness of the adhesive resin layer 15 (thickness of the sealant layer 16 / thickness of the adhesive resin layer 15) is preferably 1 or more, more preferably 1.1 or more, and particularly preferably 1.5 or more. From the viewpoint of improving the hardness of the sealed portion, the ratio of the thickness of the sealant layer 16 to the thickness of the adhesive resin layer 15 (thickness of the sealant layer 16 / thickness of the adhesive resin layer 15) is preferably 10 or less, and more preferably 3 or less.

[0079] The total thickness of the sealant layer 16 and the adhesive resin layer 15 may be 15 to 300 μm, and from the viewpoints of sealing properties and water vapor barrier properties, it is preferably 25 to 150 μm, and more preferably 40 to 100 μm.

[0080] When an exterior material includes an adhesive resin layer 15 and a sealant layer 16 like the exterior material 10, resin compositions for forming each layer may be prepared and laminated by the T-die method or the inflation method, or one layer may be formed and then another layer may be extruded thereon, or each layer may be produced by the T-die method or the inflation method and then laminated by bonding them together with an adhesive. From the viewpoint of interfacial adhesion, an adhesive containing an acid-modified polypropylene and a curing agent (such as isocyanate) may be used as the adhesive used.

[0081] Although the preferred embodiment of the exterior material of the present embodiment has been described in detail above, the present disclosure is not limited to the above-described specific embodiment.

[0082] For example, while FIG. 1 shows an exterior material having corrosion prevention treatment layers 14a, 14b on both sides of the barrier layer 13, the exterior material may have only one of the corrosion prevention treatment layers 14a, 14b, or may not have the corrosion prevention treatment layers 14a, 14b.

[0083] FIG. 1 shows a case in which the barrier layer 13 and the sealant layer 16 are laminated using the adhesive resin layer 15, but as in the exterior material 20 shown in FIG. 2, the barrier layer 13 and the sealant layer 16 may be laminated using a second adhesive layer 12b.

[0084] <Second adhesive layer> Here, the second adhesive layer 12b will be described. The second adhesive layer 12b is a layer that bonds the barrier layer 13 and the sealant layer 16. For the second adhesive layer 12b, a general adhesive for bonding the barrier layer 13 and the sealant layer 16 can be used.

[0085] When a corrosion prevention treatment layer 14b is provided on the barrier layer 13, and the second corrosion prevention treatment layer 14b has a layer containing at least one polymer selected from the group consisting of the above-mentioned cationic polymers and anionic polymers, the second adhesive layer 12b is preferably a layer containing a compound (hereinafter also referred to as a "reactive compound") that is reactive with the above-mentioned polymer contained in the second corrosion prevention treatment layer 14b.

[0086] For example, when the second corrosion prevention treatment layer 14b contains a cationic polymer, the second adhesive layer 12b preferably contains a compound reactive with the cationic polymer. When the second corrosion prevention treatment layer 14b contains an anionic polymer, the second adhesive layer 12b preferably contains a compound reactive with the anionic polymer. In addition, when the second corrosion prevention treatment layer 14b contains a cationic polymer and an anionic polymer, the second adhesive layer 12b preferably contains a compound reactive with the cationic polymer and a compound reactive with the anionic polymer. However, the second adhesive layer 12b does not necessarily need to contain the above two types of compounds, and may contain a compound reactive with both the cationic polymer and the anionic polymer. Here, "reactive" means forming a covalent bond with the cationic polymer or the anionic polymer. In addition, the second adhesive layer 12b may further contain an acid-modified polyolefin resin.

[0087] The compound reactive with the cationic polymer may be at least one compound selected from the group consisting of a polyfunctional isocyanate compound, a glycidyl compound, a compound having a carboxy group, and a compound having an oxazoline group.

[0088] Examples of the polyfunctional isocyanate compound, glycidyl compound, compound having a carboxy group, and compound having an oxazoline group include the polyfunctional isocyanate compound, glycidyl compound, compound having a carboxy group, and compound having an oxazoline group, which are exemplified above as crosslinking agents for forming a crosslinked structure from a cationic polymer. Among these, the polyfunctional isocyanate compound is preferred in terms of high reactivity with the cationic polymer and ease of forming a crosslinked structure.

[0089] The compound reactive with an anionic polymer may be at least one compound selected from the group consisting of glycidyl compounds and compounds having an oxazoline group. Examples of the glycidyl compound and the compound having an oxazoline group include the glycidyl compounds and the compounds having an oxazoline group exemplified above as crosslinking agents for forming a crosslinked structure from a cationic polymer. Among these, the glycidyl compound is preferred because of its high reactivity with an anionic polymer.

[0090] When the second adhesive layer 12b contains an acid-modified polyolefin resin, the reactive compound preferably also has a reactivity with the acidic groups in the acid-modified polyolefin resin (ie, forms a covalent bond with the acidic groups). This further enhances the adhesion to the second corrosion prevention treatment layer 14b. In addition, the acid-modified polyolefin resin has a crosslinked structure, and the solvent resistance of the exterior material 20 is further improved.

[0091] The content of the reactive compound is preferably from one equivalent to ten equivalents relative to the acidic groups in the acid-modified polyolefin resin. If the amount is equal to or more than 10 times, the reactive compound reacts sufficiently with the acid group in the acid-modified polyolefin resin. On the other hand, if the amount is more than 10 times, the crosslinking reaction with the acid-modified polyolefin resin is sufficiently saturated, so that there is a concern that unreacted matter remains and various performances may be reduced. Therefore, for example, the content of the reactive compound is preferably 5 to 20 parts by mass (solid content ratio) per 100 parts by mass of the acid-modified polyolefin resin.

[0092] The acid-modified polyolefin resin is a polyolefin resin to which an acidic group has been introduced. Examples of the acidic group include a carboxyl group, a sulfonic acid group, and an acid anhydride group, and maleic anhydride groups and (meth)acrylic acid groups are particularly preferred. For example, the acid-modified polyolefin resin may be the same as the modified polyolefin resin used in the sealant layer 16.

[0093] The second adhesive layer 12b may contain various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, and a tackifier.

[0094] The second adhesive layer 12b may contain, for example, an acid-modified polyolefin and at least one curing agent selected from the group consisting of a polyfunctional isocyanate compound, a glycidyl compound, a compound having a carboxy group, a compound having an oxazoline group, and a carbodiimide compound, from the viewpoint of suppressing a decrease in heat seal strength when corrosive gases such as hydrogen sulfide or an electrolyte are involved and from the viewpoint of further suppressing a decrease in insulating properties. Examples of the carbodiimide compound include N,N'-di-o-toluylcarbodiimide, N,N'-diphenylcarbodiimide, N,N'-di-2,6-dimethylphenylcarbodiimide, N,N'-bis(2,6-diisopropylphenyl)carbodiimide, N,N'-dioctyldecylcarbodiimide, N-triyl-N'-cyclohexylcarbodiimide, N,N'-di-2,2-di-t-butylphenylcarbodiimide, N-triyl-N'-phenylcarbodiimide, N,N'-di-p-nitrophenylcarbodiimide, N,N'-di-p-aminophenylcarbodiimide, N,N'-di-p-hydroxyphenylcarbodiimide, N,N'-di-cyclohexylcarbodiimide, and N,N'-di-p-toluylcarbodiimide.

[0095] In addition, as the adhesive for forming the second adhesive layer 12b, for example, a polyurethane adhesive obtained by blending polyester polyol made of hydrogenated dimer fatty acid and diol with polyisocyanate can be used. Examples of the adhesive include polyurethane resins obtained by reacting a bifunctional or higher isocyanate compound with a base material such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol, and epoxy resins obtained by reacting an amine compound with a base material having an epoxy group. These are preferable from the viewpoint of heat resistance.

[0096] The thickness of the second adhesive layer 12b is not particularly limited, but from the viewpoint of obtaining the desired adhesive strength, processability, and the like, it is preferably 1 to 10 μm, and more preferably 2 to 7 μm.

[0097] [Exterior material manufacturing method] Next, there will be described an example of a method for manufacturing the exterior packaging material 10 shown in Fig. 1. Note that the method for manufacturing the exterior packaging material 10 is not limited to the following method.

[0098] The manufacturing method of the exterior material 10 of this embodiment is roughly composed of the steps of providing corrosion prevention treatment layers 14a, 14b on the barrier layer 13, bonding the base material layer 11 and the barrier layer 13 together using the first adhesive layer 12a, further laminating an adhesive resin layer 15 and a sealant layer 16 on the surface of the barrier layer 13 facing the corrosion prevention treatment layer 14b to produce a laminate, and, if necessary, aging the obtained laminate.

[0099] (Laminating process of corrosion prevention treatment layer onto barrier layer) This step is a step of forming the corrosion prevention treatment layers 14a, 14b on the barrier layer 13. As described above, examples of the method include subjecting the barrier layer 13 to a degreasing treatment, a hydrothermal conversion treatment, an anodizing treatment, or a chemical conversion treatment, or applying a coating agent having corrosion prevention properties.

[0100] Furthermore, when the corrosion prevention treatment layers 14a, 14b are multiple layers, for example, a coating liquid (coating agent) constituting the lower corrosion prevention treatment layer (barrier layer 13 side) may be applied to the barrier layer 13 and baked to form a first layer, and then a coating liquid (coating agent) constituting the upper corrosion prevention treatment layer may be applied to the first layer and baked to form a second layer.

[0101] The degreasing treatment may be performed by spraying or immersion. The hydrothermal conversion treatment and anodizing treatment may be performed by immersion. The chemical conversion treatment may be performed by an appropriate method such as immersion, spraying, or coating, depending on the type of chemical conversion treatment.

[0102] Regarding the coating method of the coating agent having corrosion prevention properties, various methods such as gravure coating, reverse coating, roll coating, bar coating, etc. can be used.

[0103] As described above, the various treatments for the barrier layer 13 may be performed on either one or both sides of the metal foil, but in the case of one-sided treatment, the treated side is preferably the side on which the sealant layer 16 is laminated. If required, the surface of the base layer 11 may also be subjected to the above treatments.

[0104] The amount of coating agent applied to form the first layer and the second layer is 0.005 to 0.200 g / m 2 It is preferable that the thickness is 0.010 to 0.100 g / m 2 It is more preferable that:

[0105] Furthermore, when dry curing is required, it can be performed at a base material temperature in the range of 60 to 300° C. depending on the drying conditions of the corrosion prevention treatment layers 14a and 14b used.

[0106] (Laminating process of substrate layer and barrier layer) This step is a step of bonding the barrier layer 13 provided with the anti-corrosion treatment layers 14a and 14b to the base material layer 11 via the first adhesive layer 12a. The base material layer 11 is bonded to the surface of the barrier layer 13 facing the anti-corrosion treatment layer 14a. The lamination may be performed by dry lamination, non-solvent lamination, wet lamination or the like, and the two are bonded together using the material constituting the first adhesive layer 12a described above. The first adhesive layer 12a has a dry coating amount of preferably 1 to 10 g / m 2 More preferably, the range is 2 to 7 g / m 2 It is set within the range.

[0107] (Laminating process of adhesive resin layer and sealant layer) The step of laminating the adhesive resin layer and the sealant layer is a step of forming an adhesive resin layer 15 and a sealant layer 16 on the surface of the barrier layer 13 on the side of the corrosion prevention treatment layer 14b. As a method for this, there is a method in which the adhesive resin layer 15 is sandwiched together with the sealant layer 16 by using an extrusion laminator. Furthermore, lamination is also possible by a tandem lamination method in which the adhesive resin layer 15 and the sealant layer 16 are extruded, or a co-extrusion method. In forming the adhesive resin layer 15 and the sealant layer 16, for example, the components are mixed so as to satisfy the above-mentioned configurations of the adhesive resin layer 15 and the sealant layer 16. For forming the adhesive resin layer 15, a resin composition for forming an adhesive resin layer containing the above-mentioned components for the adhesive resin layer 15 is used. To form the sealant layer 16, a resin composition for forming a sealant layer containing the above-mentioned components of the sealant layer 16 is used. The adhesive resin layer 15 and the sealant layer 16 have a hydrogen sulfide permeation rate of 3.7×10 at 100° C. in their thickness direction. -15 ~1.8×10 -12 [(mol m) / (m 2 For this purpose, for example, the resins used for the base resin (A) and the compatibilizer (B) contained in the sealant layer 16 and the resin used for the adhesive resin layer 15 may be appropriately selected in consideration of the crystallinity and melting point, and the resin contents in the base resin (A) and the compatibilizer (B) may be appropriately set to adjust the hardness and softness in a balanced manner.

[0108] The process of laminating the adhesive resin layer and the sealant layer produces a laminate in which the layers are laminated in the following order: base layer 11 / first adhesive layer 12a / first corrosion prevention treatment layer 14a / barrier layer 13 / second corrosion prevention treatment layer 14b / adhesive resin layer 15 / sealant layer 16, as shown in FIG. 1.

[0109] The adhesive resin layer 15 may be laminated by directly extruding the materials dry-blended to have the above-mentioned material composition using an extrusion laminator. Alternatively, the adhesive resin layer 15 may be laminated by extruding the granulated material, which has been melt-blended in advance using a melt kneading device such as a single-screw extruder, a twin-screw extruder, or a Brabender mixer, using an extrusion laminator.

[0110] The sealant layer 16 may be laminated by directly extruding, with an extrusion laminator, a material obtained by dry blending the components of the resin composition for forming a sealant layer. Alternatively, the adhesive resin layer 15 and the sealant layer 16 may be laminated by a tandem lamination method in which the adhesive resin layer 15 and the sealant layer 16 are extruded with an extrusion laminator using a granulated product obtained by previously melt blending with a melt kneading device such as a single screw extruder, a twin screw extruder, or a Brabender mixer, or by a co-extrusion method. Alternatively, the adhesive resin layer 15 and the sealant layer 16 may be formed in advance as a cast film using a resin composition for forming a sealant layer, and then laminated by a method in which the sealant layer is sand-laminated together with the adhesive resin. From the viewpoint of productivity, the forming speed (processing speed) of the adhesive resin layer 15 and the sealant layer 16 can be, for example, 80 m / min or more.

[0111] (Aging process) The aging treatment step is a step of aging (curing) the laminate. By aging the laminate, it is possible to promote adhesion between the base layer 11 / first adhesive layer 12a / first corrosion prevention treatment layer 14a / barrier layer 13 and between the barrier layer 13 / second corrosion prevention treatment layer 14b / second adhesive layer 12b / sealant layer 16. The aging temperature may be 80° C. or more, 100° C. or more, or 120° C. or more, and may be 140° C. or less, 150° C. or less, or 160° C. or less. The aging time may be 1 hour or more, 2 hours or more, or 3 hours or more, and may be 24 hours or less, 48 ​​hours or less, or 72 hours or less.

[0112] In this manner, the exterior material 10 of the present embodiment as shown in FIG. 1 can be manufactured.

[0113] Next, a description will be given of an example of a method for manufacturing the exterior material 20 shown in Fig. 2. Note that the method for manufacturing the exterior material 20 is not limited to the following method.

[0114] The manufacturing method of the exterior material 20 of this embodiment is roughly composed of the steps of providing corrosion prevention treatment layers 14a, 14b on the barrier layer 13, bonding the base material layer 11 and the barrier layer 13 together using the first adhesive layer 12a, bonding the sealant layer 16 to the corrosion prevention treatment layer 14b side of the barrier layer 13 via the second adhesive layer 12b to obtain a laminate, and, if necessary, subjecting the obtained laminate to an aging treatment. The steps up to the step of bonding the base layer 11 and the barrier layer 13 with the first adhesive layer 12a can be performed in the same manner as in the above-mentioned method for producing the exterior material 10. The step of subjecting the obtained laminate to an aging treatment can be performed in the same manner as in the above-mentioned method for producing the exterior material 10.

[0115] (Lamination process of second adhesive layer and sealant layer) The lamination step of the second adhesive layer and sealant layer is a step of laminating the sealant layer 16 to the corrosion prevention treatment layer 14b side of the barrier layer 13 via the second adhesive layer 12b to obtain a laminate. The lamination method may be a wet process or a dry lamination.

[0116] In the case of a wet process, a solution or dispersion of the adhesive that constitutes the second adhesive layer 12b is applied onto the corrosion prevention treatment layer 14b, and the solvent is evaporated at a predetermined temperature to form a dry film, or after the dry film is formed, a baking process is performed as necessary. Thereafter, the sealant layer 16 is laminated. The coating method may be any of the various coating methods exemplified above. The preferred dry coating amount of the second adhesive layer 12b is the same as that of the first adhesive layer 12a.

[0117] In this case, the sealant layer 16 can be produced, for example, by a melt extrusion molding machine using a resin composition for forming a sealant layer containing the above-mentioned base resin (A) and the compatibilizer (B). In the melt extrusion molding machine, the processing speed can be set to 80 m / min or more from the viewpoint of productivity.

[0118] The second adhesive layer 12b and the sealant layer 16 have a hydrogen sulfide permeation rate of 3.7×10 at 100° C. in their thickness direction. -15 ~1.8×10 -12 [(mol m) / (m 2 For this purpose, for example, the resins used for the base resin (A) and the compatibilizer (B) contained in the sealant layer 16 and the resin used for the second adhesive layer 12b may be appropriately selected in consideration of the crystallinity and melting point, and the resin contents in the base resin (A) and the compatibilizer (B) may be appropriately set to adjust the hardness and softness in a balanced manner. In this manner, the exterior material 20 is manufactured.

[0119] The packaging material of the present disclosure can also be suitably used as a packaging material for electricity storage devices such as secondary batteries such as lithium ion batteries, nickel-metal hydride batteries, and lead-acid batteries, and electrochemical capacitors such as electric double layer capacitors. The exterior material can improve the dimensional stability of the seal portion even after it is subjected to a thermal shock. Therefore, even after the electricity storage device is stored in a device storage container and is subjected to a thermal shock, the gap between the seal portion of the exterior bag of the electricity storage device and the inner surface of the device storage container is unlikely to become large. Therefore, even if vibration or the like is applied, the electricity storage device is unlikely to shift from its fixed position in the device storage container. As a result, when wiring or the like is connected to the electricity storage device, breakage of the wiring or the like is suppressed. The exterior material of the present disclosure can be particularly suitably used as an exterior material for an electricity storage device made of an all-solid-state battery. The electricity storage device is stored in a device storage container with the electricity storage element being pressurized via an exterior bag, and is unlikely to shift from a fixed position in the device storage container. Therefore, uniform pressure is maintained on the electricity storage device in the device storage container, and a decrease in the output efficiency of the all-solid-state battery as an electricity storage device is suppressed.

[0120] [Electricity storage device] Next, an embodiment of the electricity storage device according to the present disclosure will be described. Fig. 3 is a perspective view showing an electricity storage device according to an embodiment of the present disclosure, and Fig. 4 is a partial cross-sectional view showing a state in which the electricity storage device of Fig. 3 is stored in a device storage container. As shown in Fig. 3, an all-solid-state battery 50 serving as an electricity storage device includes an electricity storage element 52, two metal terminals (current extraction terminals) 53 for extracting current from the electricity storage element 52 to the outside, and an exterior bag 54 for housing the electricity storage element 52 in an airtight state.

[0121] The exterior bag 54 is formed using the exterior material 10 according to the present embodiment described above to have a bag main body 54a and a seal portion 54b provided on the bag main body 54a, and is used as a container for accommodating the energy storage element 52. In the exterior material 10, the base material layer 11 is the outermost layer, and the sealant layer 16 is the innermost layer. That is, the exterior bag 54 can accommodate the energy storage element 52 inside by folding one exterior material 10 in half and heat-sealing the peripheral portions, or by stacking two exterior materials 10 and heat-sealing the peripheral portions, so that the base material layer 11 is on the outside of the all-solid-state battery 50 and the sealant layer 16 is on the inside of the all-solid-state battery 50.

[0122] Metal terminal 53 is sandwiched by exterior bag 54 with sealant layer 16 on the inside. Metal terminal 53 may be sandwiched by exterior bag 54 via tab sealant. Metal terminal 53 is a part of the current collector taken out to the outside of exterior material 10, and is made of metal foil such as copper foil or aluminum foil.

[0123] The energy storage element 52 has a pair of electrodes and a solid electrolyte sandwiched between the pair of electrodes. One of the pair of electrodes is a positive electrode, and the other is a negative electrode. Examples of the solid electrolyte include a sulfide-based solid electrolyte and an oxide-based solid electrolyte.

[0124] According to the all-solid-state battery 50, even after the sealed portion 54b of the exterior bag 54 is subjected to a thermal shock, the shrinkage of the sealed portion 54b is suppressed, and the dimensional stability of the sealed portion 54b is improved. Therefore, as shown in FIG. 4, even after the all-solid-state battery 50 is stored in the device storage container 100 and is subjected to a thermal shock, the gap between the sealed portion 54b of the exterior bag 54 of the all-solid-state battery 50 and the inner surface of the device storage container 100 is unlikely to become large. Therefore, even if vibration or the like is applied, the all-solid-state battery 50 is unlikely to shift from the fixed position in the device storage container 100. As a result, when wiring or the like is connected to the all-solid-state battery 50, breakage of the wiring or the like is suppressed.

[0125] 4, the all-solid-state battery 50 is stored in the device storage container 100 with the power storage element 52 being pressurized via the outer bag 54 by the pressurizing member 60, but is unlikely to shift from the fixed position in the device storage container 100. Therefore, uniform pressure is maintained on the all-solid-state battery 50 in the device storage container, and a decrease in the output efficiency of the all-solid-state battery 50 as a power storage device is suppressed.

[0126] In the all-solid-state battery 50, the exterior bag 54 may have an exterior material 20 instead of the exterior material 10.

[0127] Furthermore, instead of the all-solid-state battery 50, it is also possible to use, as the power storage device, 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, semi-solid batteries, and the like.

[0128] The outline of this disclosure is as follows. [1] A composite material having at least a base layer, a barrier layer, an adhesive layer, and a sealant layer in this order, and having a hydrogen sulfide permeation rate of 3.7 × 10 at 100 ° C. in the thickness direction of the sealant layer and the adhesive layer. -15 ~1.8×10 -12 [(mol m) / (m 2 An exterior material for an electricity storage device with a thermal conductivity of 1.0 s·Pa). [2] The exterior material for an electricity storage device according to [1], in which, when a cross section of the sealant layer is observed with a scanning electron microscope, a sea-island structure having a sea portion and island portions present in the sea portion is observed. [3] The exterior packaging material for an electricity storage device according to [1] or [2], wherein the sealant layer contains a base resin (A) containing a polyolefin-based resin. [4] The exterior packaging material for an electricity storage device according to [3], wherein the polyolefin-based resin contains a polypropylene-based resin and a polyethylene-based resin. [5] The exterior packaging material for an electricity storage device according to [4], wherein the sealant layer further contains a compatibilizer (B) having a portion compatible with the polypropylene-based resin and a portion compatible with the polyethylene-based resin. [6] The exterior packaging material for an electricity storage device according to [5], wherein the compatibilizer (B) contains at least one of a block copolymer (B1) of polypropylene and polyethylene, and a block copolymer (B2) of polyethylene and polyethylenebutylene. [7] The exterior packaging material for an electricity storage device according to any one of [1] to [6], wherein the electricity storage device is an all-solid-state battery. [8] An electricity storage device comprising: an electricity storage element; and an outer bag for accommodating the electricity storage element, the outer bag being formed using the outer casing material for an electricity storage device according to any one of [1] to [6] so as to have a bag body and a seal portion provided on the bag body. [9] The power storage device according to [8], which is an all-solid-state battery. EXAMPLES

[0129] The present disclosure will be specifically described below based on examples, but the present disclosure is not limited to the following examples.

[0130] [Materials used] The materials used as the base layer, the adhesive for forming the first adhesive layer, the adhesive for forming the second adhesive layer, the material for forming the first and second corrosion prevention treatment layers, the barrier layer, the adhesive resin layer, and the sealant layer are as follows.

[0131] <Base material layer> PET: Polyethylene terephthalate film (thickness 25 μm) with corona treatment on one side

[0132] <First adhesive layer (mass per unit area: 4.0 g / m 2 ) for forming adhesives> An adhesive (first adhesive) prepared by mixing polyester polyol (manufactured by Showa Denko Materials Co., Ltd., product name: Teslac 2505-63, hydroxyl value: 7 to 11 mgKOH / g) and a nurate of isophorone diisocyanate (manufactured by Mitsui Chemicals, Inc., product name: Takenate 600) so that the NCO / OH ratio is 20.0, and diluting with ethyl acetate to a solid content of 26 mass%.

[0133] <Second adhesive layer (mass per unit area 3.0 g / m 2 ) for forming adhesives> An adhesive (second adhesive) made by mixing 100 parts by mass of acid-modified polyolefin resin dissolved in toluene with 10 parts by mass (solid content ratio) of a polyisocyanate compound with an isocyanurate structure.

[0134] <Material for forming first corrosion prevention treatment layer and material for forming second corrosion prevention treatment layer> The first corrosion prevention treatment layer forming material (substrate layer side) and the second corrosion prevention treatment layer forming material (sealant layer side) are as follows (CL-1) and (CL-2). (CL-1): Sodium polyphosphate-stabilized cerium oxide sol adjusted to a solid content of 10% by mass using distilled water as a solvent. The sodium polyphosphate-stabilized cerium oxide sol was obtained by mixing 100 parts by mass of cerium oxide with 10 parts by mass of sodium salt of phosphoric acid. (CL-2): A composition prepared by using distilled water as a solvent and adjusting the solid content concentration to 5% by mass. In the above composition, the ratio of polyallylamine (manufactured by Nitto Boseki Co., Ltd.) to polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation) was 90:10 (mass ratio).

[0135] <Barrier layer (thickness 40 μm)> AL: Annealed and degreased soft aluminum foil (manufactured by Toyo Aluminum, "8079 material")

[0136] <Adhesive resin layer (adhesive layer)> Maleic anhydride modified homopolypropylene (Hydrogen sulfide permeation at 100℃: 1.8×10 -14 [(mol m) / (m 2 ·s·Pa)], melting temperature: 162℃)

[0137] <Sealant layer> The base resin (A) and the compatibilizer (B) used in the sealant layer are as shown in the following Table 1. In the following Table 1, "PP" stands for "polypropylene" and "PE" stands for "polyethylene."

[0138] [Table 1]

[0139] [Creating exterior materials] Example 1 First, a first and a second corrosion prevention treatment layer were provided on the barrier layer by the following procedure. That is, (CL-1) was applied to both sides of the barrier layer at a dry coating amount of 70 mg / m 2 The layer was then coated by microgravure coating so that the thickness of the layer was 200 mm, and the layer was baked at 200° C. in a drying unit. Next, (CL-2) was applied to the layer obtained in a dry coating amount of 20 mg / m 2 By applying the coating by microgravure coating so that the above-mentioned coating conditions were satisfied, a composite layer consisting of (CL-1) and (CL-2) was formed as the first and second corrosion prevention treatment layers. This composite layer exhibits corrosion prevention performance by combining the two types of materials, (CL-1) and (CL-2).

[0140] Next, the first anti-corrosion treatment layer side of the barrier layer provided with the first anti-corrosion treatment layer and the second anti-corrosion treatment layer was attached to the base layer by dry lamination using the first adhesive to form the first adhesive layer, to obtain a first laminate (base layer / first adhesive layer / first anti-corrosion treatment layer / barrier layer / second anti-corrosion treatment layer). Specifically, the first adhesive was applied to the surface of the barrier layer facing the first anti-corrosion treatment layer so that the thickness after curing was 5 μm, and the first adhesive was dried at 80° C. for 1 minute, and then laminated with the base layer and aged at 80° C. for 120 hours to obtain a first laminate.

[0141] Next, the first laminate was set on the unwinding section of the extrusion laminator. An adhesive resin layer and a sealant layer were laminated in this order on the second corrosion prevention treatment layer of the first laminate by co-extrusion from a T-die under processing conditions of 270°C and 80m / min, to obtain an exterior material (a laminate of a substrate layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer / adhesive resin layer / sealant layer). At this time, the thicknesses of the adhesive resin layer and the sealant layer were 25μm and 55μm, respectively. At this time, for the sealant layer, a resin composition for forming a sealant layer was prepared in advance by dry blending the base resin (A) and the compatibilizer (B) shown in Table 2, and this resin composition was used. At this time, the composition of the sealant layer (type and content of the base resin (A) and the compatibilizer (B)) was as shown in Table 2. In addition, the hydrogen sulfide permeation amount at 100°C in the thickness direction of the adhesive resin layer as the sealant layer and the adhesive layer was as shown in Table 2.

[0142] (Examples 2 to 18 and Comparative Example 1) An exterior material was prepared in the same manner as in Example 1, except that the hydrogen sulfide permeation amounts at 100° C. in the thickness direction of the sealant layer and adhesive layer, and the composition of the sealant layer were as shown in Table 2.

[0143] (Examples 19 and 20, Comparative Examples 2 and 3) In the same manner as in Example 1, a first laminate (substrate layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer) was obtained. Next, a sealant layer having the composition shown in Table 2 was attached onto the second corrosion prevention treatment layer of the first laminate by dry lamination using a second adhesive for forming a second adhesive layer. In this way, a second adhesive layer and a sealant layer serving as adhesive layers were formed on the first laminate. At this time, the hydrogen sulfide permeation amounts at 100°C in the thickness direction of the second adhesive layer and the sealant layer were set to the values ​​shown in Table 2. The lamination of the first laminate and the sealant layer was performed by applying the second adhesive layer onto the second corrosion prevention treatment layer so that the thickness after drying would be 3 μm, drying at 80°C for 1 minute, laminating it with the sealant layer, and aging it at 120°C for 3 hours. In this manner, an exterior material (a laminate of substrate layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer / second adhesive layer / sealant layer) was produced.

[0144] <Hydrogen sulfide permeation rate> The amount of hydrogen sulfide permeated through the sealant layer and adhesive layer in the thickness direction at 100° C. was measured as follows. First, the resin composition for forming a sealant layer was heated and melted at 200° C. to prepare a measurement sheet having a thickness of 80 μm. Next, a differential pressure type gas permeability measuring device was prepared. As the differential pressure type gas permeability measuring device, a device equipped with a first gas pipe and a second gas pipe equipped with a valve and a pressure sensor, and a ceramic electric tubular furnace (model: ARF-50K, manufactured by Asahi Rika Seisakusho Co., Ltd.) having a heater was used. Then, using this differential pressure type gas permeability measuring device, the hydrogen sulfide permeation amount of the measurement sheet was measured by a differential pressure method. Specifically, the measurement sheet was arranged so as to be sandwiched between the end face of the first gas pipe and the end face of the second gas pipe, and kept at 100 ° C. in the ceramic electric tubular furnace, and hydrogen sulfide gas was supplied to the first gas pipe on one side of the measurement sheet so that the pressure difference between the first gas pipe and the second gas pipe was 0.1 MPa, and the hydrogen sulfide permeation amount was measured by measuring the change over time in the pressure of the hydrogen sulfide gas in the second gas pipe that permeates the measurement sheet. The results are shown in Table 2.

[0145] [Dimensional stability evaluation] (1) Preparation of samples Two sheets measuring 100 mm×100 mm were cut out from each of the exterior packaging materials obtained in the examples and comparative examples. Next, the sheets were stacked so that the sealant layers faced each other, and heat-sealed using a 10 mm wide seal bar at a heating temperature of 220°C and a surface pressure of 0.5 MPa for 10 seconds. In this way, samples with a strip-shaped sealed portion of 10 mm x 100 mm were produced. Two samples were produced for each Example and Comparative Example. (2) Thermal shock test Of the two samples prepared for each of the examples and comparative examples, one sample was subjected to a thermal shock test as follows. The sample was placed in a nitrogen-purged metal container and set to 100° C. The sample was then cooled to -40° C. in 2 minutes, held at -40° C. for 28 minutes, then heated to 100° C. in 2 minutes, and held at 100° C. for 28 minutes. This heat cycle was counted as one cycle, and 600 heat cycles were performed. (3) Evaluation For the samples that were not subjected to the thermal shock test, a 10 mm wide cut was obtained in a direction perpendicular to the longitudinal direction of the band-shaped seal portion. The cut piece thus obtained was solidified using an epoxy resin, and then polished to expose the cut surface of the cut piece. The length of the seal portion was measured by observing it using a microscope. On the other hand, for the samples that had been subjected to the thermal shock test, the length of the sealed portion was measured in the same manner as above. The shrinkage was calculated based on the following formula: Shrinkage Width = Length of the seal on the sample that was not subjected to thermal shock test -Length of the seal after thermal shock test The dimensional stability after thermal shock was evaluated based on the following criteria. The results are shown in Table 2. (Judgment criteria) A: Shrinkage width is less than 1mm B: Shrinkage width is 1mm or more and less than 2mm C: Shrinkage width is 2mm or more and less than 3mm D: Shrinkage width is 3mm or more Samples rated A to C were deemed to have passed the test in terms of dimensional stability after being subjected to thermal shock.

[0146] [Table 2]

[0147] From the results shown in Table 2, the dimensional stability after the thermal shock was evaluated as "A," "B," or "C" for all of the packaging materials of Examples 1 to 20. In contrast, the dimensional stability after the thermal shock was evaluated as "D" for all of the packaging materials of Comparative Examples 1 to 3. From the above, it has been confirmed that the exterior material of the present disclosure can improve the dimensional stability of the seal portion formed using the exterior material, even after being subjected to thermal shock. [Explanation of symbols]

[0148] Reference Signs List: 10, 20...outer packaging material, 11...base material layer, 12b...second adhesive layer (adhesive layer), 13...barrier layer, 15...adhesive resin layer (adhesive layer), 16...sealant layer, 50...all-solid-state battery (energy storage device), 52...energy storage element, 54...outer packaging bag, 54a...bag body, 54b...sealing portion.

Claims

1. At a minimum, the system comprises a base layer, a barrier layer, an adhesive layer, and a sealant layer in this order. The adhesive layer comprises an acid-modified polyolefin resin. The sealant layer contains a base resin (A) comprising a polypropylene resin and a polyethylene resin, and a compatibilizer (B) having a portion compatible with the polypropylene resin and a portion compatible with the polyethylene resin. The polypropylene resin is at least one selected from the group consisting of homopolypropylene, block polypropylene, and random polypropylene. The compatibilizer (B) comprises at least one of a block copolymer of polypropylene and polyethylene (B1) and a block copolymer of polyethylene and polyethylenebutylene (B2). The content of the polypropylene resin in the sealant layer is 70 to 90% by mass. An exterior material for an energy storage device, wherein the content of the compatibilizer (B) in the sealant layer is 5 to 15% by mass.

2. The exterior material for an energy storage device according to claim 1, wherein when the cross-section of the sealant layer is observed with a scanning electron microscope, a sea-island structure having a sea portion and an island portion located in the sea portion is observed.

3. The exterior material for an energy storage device according to claim 1 or 2, wherein the energy storage device is an all-solid-state battery.

4. Energy storage element, The system comprises an outer bag for housing the energy storage element, An energy storage device in which the outer bag is formed using the outer material for an energy storage device described in claim 1 or 2, and having a bag body and a sealing portion provided on the bag body.

5. The energy storage device according to claim 4, which is an all-solid-state battery.

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