Encapsulating material for power storage device, and power storage device

Abstract

A sealing material for a power storage device is provided with a base material layer, a barrier layer, an adhesive layer, and a sealant layer in this order. In the sealing material for a power storage device, the adhesive layer is a thermally adhesive resin layer or an adhesive layer, and when the adhesive layer is the thermally adhesive resin layer, the hydrogen sulfide transmission coefficient of a laminate of the thermally adhesive resin layer and the sealing layer is 1.1 * 10 <-9 > cc * mm / cm2 * sec * cmHg or more and less than 1.0 * 10 <-8 > cc * mm / cm2 * sec * cmHg, and the hydrogen sulfide transmission coefficient is 0.1 * 10 <-8 > cc * mm / cm2 * sec * cmHg or more and less than 1.0 * 10 <-8 > cc * mm / cm2 * sec * cmHg or more and less than 1.0 * 10 <-8 > cc * mm / cm2 * sec * cmHg. When the adhesive layer is the adhesive layer, the hydrogen sulfide transmission coefficient of the sealing layer is at least 1.1 * 10 <-9 > cc * mm / cm < 2 > * sec * cm < Hg > and less than 1.0 * 10 <-8 > cc * mm / cm < 2 > * sec * cm < Hg >.

Description

Encapsulation materials for energy storage devices and energy storage devices Technical Field

[0001] This disclosure relates to encapsulation materials for energy storage devices and energy storage devices. Background Technology

[0002] In energy storage devices such as all-solid-state batteries, the energy storage elements are housed in a package formed using encapsulation materials.

[0003] For example, Patent Document 1 discloses an encapsulation material for an all-solid-state battery containing a sulfide solid electrolyte material. This material is composed of a laminate comprising, in sequence, a substrate layer, a barrier layer, a barrier protective film formed on the surface of the barrier layer, and a heat-welding resin layer. The hydrogen sulfide permeability coefficient of the resin constituting the heat-welding resin layer is 1.0 × 10⁻⁶. -8 cc·mm / cm 2 ·sec·cmHg or above

[0004] Furthermore, Patent Document 2 discloses an encapsulation material for an all-solid-state battery containing a sulfide solid electrolyte material. This material is composed of a laminate comprising a substrate layer, a barrier layer, and a heat-fused resin layer, wherein the hydrogen sulfide permeability coefficient of the resin constituting the heat-fused resin layer is 1.0 × 10⁻⁶. -9 Below cc·mm / cm²·sec·cmHg.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2020 / 153456

[0008] Patent Document 2: International Publication No. 2020 / 153458 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, the encapsulation material used in energy storage devices sometimes stretches and contracts along with the expansion and contraction of the energy storage elements during the operation of the energy storage device.

[0011] However, the encapsulation materials for all-solid-state batteries disclosed in Patent Documents 1 and 2 have room for improvement, at least in suppressing the reduction in insulation caused by stretching.

[0012] This disclosure was made in view of the above circumstances, and its purpose is to provide an encapsulation material for an energy storage device and an energy storage device capable of suppressing the reduction of insulation caused by stretching.

[0013] Methods for solving problems

[0014] One aspect of this disclosure provides an encapsulation material for an energy storage device, which sequentially comprises a substrate layer, a barrier layer, an adhesive layer, and a sealing layer. The adhesive layer is a thermally adhesive resin layer or an adhesive layer. When the adhesive layer is a thermally adhesive resin layer, the hydrogen sulfide permeability coefficient of the laminate of the thermally adhesive resin layer and the sealing layer is 1.1 × 10⁻⁶. -9 cc·mm / cm 2 ·sec·cmHg or higher and less than 1.0×10 -8 cc·mm / cm 2 In the case where the adhesive layer is the adhesive layer, the hydrogen sulfide permeability coefficient of the sealing layer is 1.1 × 10⁻⁶ sec·cmHg. -9 cc·mm / cm 2 ·sec·cmHg or higher and less than 1.0×10 -8 cc·mm / cm 2 ·sec·cmHg.

[0015] The encapsulation material used in the above-mentioned energy storage device can suppress the reduction in insulation caused by stretching.

[0016] The inventors of this disclosure speculate the following reasons for achieving such an effect.

[0017] That is, firstly, when the adhesive layer is a heat-adhesive resin layer, the hydrogen sulfide permeability coefficient of the laminate of the heat-adhesive resin layer and the sealing layer is less than the lower limit of 1.1 × 10⁻⁶. -9 cc·mm / cm 2 At a temperature of ·sec·cmHg, the laminate as a whole hardens and becomes brittle, making it prone to cracking (microcracks) under stretching of the encapsulation material. On the other hand, when the hydrogen sulfide permeability reaches the upper limit of 1.0 × 10⁻⁶,… -8 cc·mm / cm 2 When the stress exceeds ·sec·cmHg, the laminate as a whole softens. Under the stretching of the encapsulation material, stress is concentrated in a hard part of the laminate, which can easily cause cracks.

[0018] In contrast, when the hydrogen sulfide permeability coefficient of the laminate as disclosed herein is within the aforementioned range, the laminate is neither too hard nor too soft. Even when stress is applied to the laminate during the stretching of the encapsulation material, the stress as a whole in the laminate is mitigated, thus suppressing the formation of cracks in the laminate. As a result, even when the encapsulation material is stretched, the reduction in the insulation of the encapsulation material can be suppressed.

[0019] The inventors of this disclosure hypothesize that, when the adhesive layer is an adhesive layer, for the same reasons described above, even when the encapsulation material is stretched, the reduction in the insulation of the encapsulation material can be suppressed.

[0020] In the encapsulation material for the above-mentioned energy storage device, it is preferred that the sealing layer contains a polypropylene resin comprising at least one of homopolymer polypropylene and block polypropylene, and a polyethylene resin, wherein the polyethylene resin has at least one melting peak in the range of 60°C to 105°C.

[0021] In this case, the improved dispersibility of polyethylene resin compared to polypropylene resin in the sealing layer results in more effective stress relief, thus effectively suppressing the reduction in insulation of the encapsulation material for energy storage devices caused by stretching.

[0022] In the above-mentioned encapsulation material for energy storage devices, it is preferable that the weight-average molecular weight Mw to the number-average molecular weight Mn ratio (Mw / Mn) of the polyethylene resin is 1.2 or more and 5.0 or less.

[0023] In this case, the dispersion of polyethylene resin relative to polypropylene resin in the sealing layer is further improved, resulting in more effective stress relief. Therefore, it is possible to more effectively suppress the reduction in insulation of the encapsulation material for energy storage devices caused by stretching.

[0024] In the above-mentioned encapsulation material for the energy storage device, it is preferred that the sealing layer contains a polypropylene resin comprising at least one of homopolymer polypropylene and block polypropylene, wherein the content of the polypropylene resin in the sealing layer is 50 to 95% by mass.

[0025] In this case, polypropylene resins possess suitable sealant properties, imparting appropriate hardness to the sealing layer. Furthermore, they can balance the hardness and flexibility of the sealing layer. Therefore, they can more effectively suppress the reduction in insulation of encapsulation materials for energy storage devices caused by stretching.

[0026] In the above-mentioned encapsulation material for the energy storage device, it is preferable that, when the adhesive layer is the above-mentioned heat-adhesive resin layer, the heat-adhesive resin layer contains a polypropylene resin, and the content of the polypropylene resin in the heat-adhesive resin layer is 50 to 95% by mass.

[0027] In this case, the hardness and flexibility of the thermally adhesive resin layer can be balanced. Therefore, the reduction in insulation of the encapsulation material for energy storage devices caused by stretching can be more effectively suppressed.

[0028] In the encapsulation material for the above-mentioned energy storage device, it is preferable that the sealing layer contains a polypropylene resin including homopolymer polypropylene and a polyethylene resin, wherein the weight-average molecular weight Mw to number-average molecular weight Mn ratio (Mw / Mn) of the polyethylene resin is 1.2 or more and 5.0 or less.

[0029] In this case, the improved dispersibility of polyethylene resin compared to polypropylene resin in the sealing layer results in effective stress relief, thus effectively suppressing the reduction in insulation of the encapsulation material for energy storage devices caused by stretching.

[0030] In the above-mentioned encapsulation material for the energy storage device, it is preferable that when the adhesive layer is the above-mentioned thermally adhesive resin layer, the total thickness of the laminate of the above-mentioned thermally adhesive resin layer and the above-mentioned sealing layer is 25 to 150 μm, and when the adhesive layer is the above-mentioned adhesive layer, the thickness of the above-mentioned sealing layer is 25 to 150 μm.

[0031] In this case, since the thermally adhesive resin layer and the sealing layer, or the sealing layer, have sufficient sealing and water vapor barrier properties, when the energy storage element is contained in a packaging bag formed by the packaging material for the energy storage device, it is easy to prevent the seepage of gases such as water vapor from the outside of the packaging bag, thus easily suppressing the deterioration of the energy storage element.

[0032] The aforementioned energy storage device is preferably an all-solid-state battery. In this case, even if the all-solid-state battery expands and contracts, the reduction in the insulation of the encapsulation material used in the energy storage device can be suppressed.

[0033] Other aspects of this disclosure provide an energy storage device having an energy storage element and a packaging bag for containing the energy storage element, the packaging bag being formed using the packaging material for the energy storage device.

[0034] According to the above-mentioned energy storage device, even if the energy storage element expands and contracts during the operation of the energy storage device, causing the encapsulation material of the energy storage device to stretch, the reduction in the insulation of the encapsulation bag formed by the encapsulation material of the energy storage device can be suppressed, so the energy storage device can have a longer lifespan.

[0035] The aforementioned energy storage device is preferably an all-solid-state battery. In this case, the energy storage element is particularly prone to expansion and contraction, but even if the energy storage element expands and contracts, the reduction in the insulation of the encapsulation material of the energy storage device caused by stretching can be suppressed. Therefore, the reduction in the insulation of the encapsulation bag can be suppressed, and the energy storage device has a longer lifespan.

[0036] The effects of the invention

[0037] According to this disclosure, an encapsulation material for an energy storage device and an energy storage device are provided, which can suppress the reduction of insulation caused by stretching. Attached Figure Description

[0038] [Figure 1] Figure 1 is a cross-sectional view schematically showing one embodiment of the encapsulation material for the energy storage device of the present disclosure.

[0039] [Figure 2] Figure 2 is a cross-sectional view schematically illustrating another embodiment of the encapsulation material for the energy storage device of the present disclosure.

[0040] [Figure 3] Figure 3 is a front view of the apparatus for measuring hydrogen sulfide permeation.

[0041] [Figure 4] Figure 4 is a perspective view of one embodiment of the energy storage device of this disclosure. Detailed Implementation

[0042] The preferred embodiments of this disclosure will now be described in detail with appropriate reference to the accompanying drawings. It should be noted that in the drawings, the same or equivalent parts are labeled with the same symbols, and repeated descriptions are omitted. Furthermore, the scale of the drawings is not limited to that shown in the illustrations.

[0043] Encapsulation materials for energy storage devices

[0044] Figure 1 is a schematic cross-sectional view showing an embodiment of the encapsulation material for an energy storage device according to the present disclosure. As shown in Figure 1, the encapsulation material for an energy storage device (hereinafter also referred to as "encapsulation material") 10 of the present embodiment is an encapsulation material for an energy storage device, which sequentially includes a substrate layer 11, a barrier layer 13, a thermally adhesive resin layer 15 as an adhesive layer, and a sealing layer 16.

[0045] Additionally, as shown in FIG1, the encapsulation material 10 may also have a first adhesive layer 12a between the substrate layer 11 and the barrier layer 13.

[0046] The encapsulation material 10 can suppress the reduction in insulation caused by stretching.

[0047] It should be noted that the barrier layer 13 may have a first anti-corrosion treatment layer 14a on the substrate layer 11 side and a second anti-corrosion treatment layer 14b on the sealing layer 16 side.

[0048] Furthermore, when the encapsulation material 10 is used as a packaging bag for an energy storage device, the substrate layer 11 is the outermost layer and the sealing layer 16 is the innermost layer in the encapsulation material 10. That is, the encapsulation material 10 is used with the substrate layer 11 facing outwards from the energy storage device and the sealing layer 16 facing inwards from the energy storage device.

[0049] The following is a detailed description of each layer constituting the encapsulation material 10.

[0050] <Substrate Layer>

[0051] The substrate layer 11 serves the following functions: during the sealing process of the encapsulation material 10 in the manufacture of the energy storage device, it imparts heat resistance to the encapsulation material 10 and suppresses the generation of pinholes that may occur during the molding and distribution of the encapsulation material 10. In particular, for the encapsulation material of large-scale energy storage devices, the substrate layer 11 can also impart scratch resistance, chemical resistance, insulation, etc. to the encapsulation material 10.

[0052] The substrate layer 11 is preferably a layer formed of an insulating resin. Suitable resins include: polyester resin, polyamide resin, polyimide resin, polyamide-imide resin, polyetherketone resin, polyphenylene sulfide resin, polyetherimide resin, polysulfone resin, fluoropolymer resin, phenolic resin, melamine resin, urethane resin, allyl resin, silicone resin, epoxy resin, furan resin, and acetylcellulose resin, etc.

[0053] Among the aforementioned resins, polyester resin and polyamide resin are preferred as the substrate layer 11 from the perspective of excellent formability. Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Examples of polyamide resins include nylon 6, nylon 6,6, copolymers of nylon 6 and nylon 6,6, nylon 9T, nylon 10, poly(m-phenylene adipamide) (MXD6), nylon 11, and nylon 12.

[0054] The substrate layer 11 can be in the form of a stretched or unstretched film, or it can be in any form as a coated film. Furthermore, the substrate layer 11 can be a single layer or multiple layers. When the substrate layer 11 is multiple layers, it can be constructed by laminating layers composed of different resins. When the substrate layer 11 is in the form of a film, a co-extruded laminate or a laminate formed by bonding agents can be used as the substrate layer 11. When the substrate layer 11 is in the form of a coated film, a coated film obtained by applying a coating film forming composition multiple times can be used as the substrate layer 11. The substrate layer 11 can also be multilayered by combining a film and a coated film.

[0055] When the aforementioned resin is used in film form, the substrate layer 11 is preferably a biaxially stretched film. In this case, the encapsulation material 10 has good formability. Examples of stretching methods for obtaining a biaxially stretched film include: successive biaxial stretching, tubular biaxial stretching, and simultaneous biaxial stretching. From the viewpoint of obtaining better deep-drawing formability of the encapsulation material 10, a biaxially stretched film is preferably a film stretched by a tubular biaxial stretching method.

[0056] The thickness of the substrate layer 11 is preferably 6–100 μm, more preferably 10–75 μm, and even more preferably 10–50 μm. Since the thickness of the substrate layer 11 is 6 μm or more, the pinhole resistance and insulation properties of the encapsulation material 10 tend to improve. When the thickness of the substrate layer 11 is 100 μm or less, the total thickness of the encapsulation material 10 can be reduced.

[0057] Furthermore, the substrate layer 11 preferably has a higher melting point than the sealing layer 16. When the substrate layer 11 or the sealing layer 16 has a multilayer structure, the melting point of the substrate layer 11 or the sealing layer 16 refers to the melting point of the layer with the highest melting point among the layers constituting the substrate layer 11 or the sealing layer 16. By having a higher melting point than the sealing layer 16, it is possible to suppress the deterioration of the appearance of the encapsulation material 10 due to the melting of the substrate layer 11 (the outermost layer) during heat sealing of the encapsulation material 10. It should be noted that, in the case where multiple melting peak temperatures exist among the layers constituting the substrate layer 11 or the sealing layer 16, the melting point of each layer refers to the melting peak temperature with the greatest heat of melting. The melting peak temperature refers to the temperature at the maximum point of the melting peak.

[0058] Melting point T of substrate layer 11 11 Melting point T of sealing layer 16 16 The difference (T) 11 -T 16 The temperature difference is preferably 20°C or higher. With this temperature difference of 20°C or higher, the appearance degradation of the encapsulation material 10 caused by the heat-sealing encapsulation material 10 can be further and sufficiently suppressed.

[0059] The melting temperature of the substrate layer 11 is preferably 240°C or higher. However, the melting temperature of the substrate layer 11 is preferably 350°C or lower. Examples of resin films that can be used as the substrate layer 11 and have a melting temperature within the above range include: polyester films such as nylon films and PET films, polyamide films, and polyphenylene sulfide films (PPS films).

[0060] The substrate layer 11 can be a commercially available film or formed by coating (coating and drying of a coating solution). It should be noted that the substrate layer 11 can be formed by coating a thermosetting resin. Furthermore, the substrate layer 11 may contain various additives (e.g., flame retardants, slip agents, anti-blocking agents, antioxidants, light stabilizers, tackifiers, etc.).

[0061] <First Adhesive Layer>

[0062] The first adhesive layer 12a is a layer that bonds the substrate layer 11 and the barrier layer 13 together. Specifically, materials constituting the first adhesive layer 12a can include, for example, polyurethane resins formed by using a polyisocyanate compound with two or more functions (polyfunctional isocyanates) as a curing agent on a main component such as a polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol. Depending on the required function and performance of the encapsulation material 10, these various polyols can be used alone or in combination of two or more. In addition to the above, substances consisting mainly of epoxy resin and a curing agent can also be used as materials constituting the first adhesive layer 12a.

[0063] The first adhesive layer 12a is formed using an adhesive composition comprising the aforementioned main agent and curing agent. Furthermore, depending on the required properties of the adhesive layer, the first adhesive layer 12a may also incorporate various other additives or stabilizers into the aforementioned adhesive composition.

[0064] The adhesive composition preferably contains at least one polyfunctional isocyanate compound selected from the group consisting of alicyclic isocyanate polymers and isocyanate polymers containing aromatic rings in their molecular structure as a curing agent. Examples of polyfunctional isocyanate compounds include: ureate form of isophorone diisocyanate, adduct of toluene diisocyanate, adduct of hexamethylene diisocyanate, biuret and ureate form of hexamethylene diisocyanate, biuret and ureate form of toluene diisocyanate, adduct of diphenylmethane diisocyanate, biuret and ureate form of diphenylmethane diisocyanate, and adduct of phenyl diisocyanate, biuret and ureate form of diphenylmethane diisocyanate.

[0065] As a curing agent, alicyclic isocyanate polymers and isocyanate polymers containing aromatic rings in their molecular structure can be used together. By using them together, the heat resistance of the encapsulation material 10 tends to be further improved.

[0066] From the viewpoint of further improving the heat resistance of the encapsulation material 10, the adhesive composition preferably contains at least one polyol selected from the group consisting of polyester polyol, acrylic polyol, and polycarbonate diol. Among these adhesive compositions, from the viewpoint of further improving the heat resistance of the encapsulation material 10, the adhesive composition more preferably contains a polyester polyol.

[0067] In the adhesive composition, the ratio (NCO / OH) of the number of isocyanate groups in the polyfunctional isocyanate compound to the number of hydroxyl groups in the polyol can be 1.5 to 40.0 or 15.0 to 30.0. When this ratio is 1.5 or higher, the curing agents react with each other, easily generating byproducts such as urea resin or biuret resin. Since these byproducts contain active hydrogen groups, they interact with the polar groups of adjacent layers, further improving the interfacial adhesion between the first adhesive layer 12a and the substrate layer 11 and the barrier layer 13. Therefore, the heat resistance of the encapsulation material 10 tends to improve. On the other hand, when the above ratio is 40.0 or lower, the lamination strength of the encapsulation material 10 at room temperature and high temperature environments can be further improved.

[0068] To promote curing, the adhesive composition may also contain tin-based, titanium-based, or zirconium-based urethane esterification catalysts. Additionally, the adhesive composition may contain an overt or covert curing agent. Examples of overt or covert curing agents include amine compounds. The aforementioned urethane esterification catalysts and overt or covert curing agents may be used individually or in combination.

[0069] The thickness of the first adhesive layer 12a is not particularly limited, but from the viewpoint of obtaining the desired adhesive strength, conformability and processability of the encapsulation material 10, it is preferably 1 to 10 μm, more preferably 2 to 7 μm.

[0070] For the encapsulation material 10, from the viewpoint of ensuring superior lamination strength and achieving better deep-drawing formability under both room temperature and high temperature conditions, the mass per unit area of ​​the first adhesive layer 12a can be 2.0–6.0 g / m². 2 It can also be 2.5–5.0 g / m³ 2 It can also be 3.0~4.0g / m 2 .

[0071] <Barrier Layer>

[0072] The barrier layer 13 has water vapor barrier properties that prevent moisture from seeping into the interior of the energy storage device. In addition, the barrier layer 13 may also have ductility suitable for deep drawing.

[0073] As a barrier layer 13, various metal foils such as aluminum, stainless steel, and copper can be used; or metal vapor-deposited films, inorganic oxide vapor-deposited films, carbon-containing inorganic oxide vapor-deposited films, films having these vapor-deposited films, etc.

[0074] As for the film with the vapor-deposited coating, for example, aluminum vapor-deposited film or inorganic oxide vapor-deposited film can be used. These can be used alone or in combination of two or more.

[0075] As the barrier layer 13, metal foil is preferred, and aluminum foil or stainless steel foil is even more preferred, in terms of barrier properties such as quality (specific gravity), moisture resistance, processability, and cost.

[0076] From the perspective of imparting the desired ductility during molding to the barrier layer 13, annealed soft aluminum foil is particularly preferred as the aluminum foil. To impart further resistance to pinholes and ductility during molding, iron-containing aluminum foil is more preferred.

[0077] In 100% by mass aluminum foil, the iron content is preferably 0.1 to 9.0% by mass, more preferably 0.5 to 2.0% by mass. With an iron content of 0.1% by mass or more, a packaging material 10 with superior pinhole resistance and ductility can be obtained. With an iron content of 9.0% by mass or less, a packaging material 10 with superior flexibility can be obtained.

[0078] While untreated aluminum foil can be used, degreasing treatment is preferred in terms of imparting corrosion resistance.

[0079] When degreasing aluminum foil, it can be done on only one side or on both sides.

[0080] The thickness of the barrier layer 13 is not particularly limited, but considering the barrier properties, pinhole resistance and processability of the barrier layer 13, it is preferably 9 to 200 μm, more preferably 15 to 100 μm.

[0081] <First and second anti-corrosion treatment layers>

[0082] The first and second anti-corrosion treatment layers 14a and 14b are layers provided to prevent corrosion of the metal foil (metal foil layer) and the like constituting the barrier layer 13. Furthermore, the first anti-corrosion treatment layer 14a serves to improve the adhesion between the barrier layer 13 and the first adhesive layer 12a. Furthermore, the second anti-corrosion treatment layer 14b serves to improve the adhesion between the barrier layer 13 and the thermally adhesive resin layer 15.

[0083] The first anti-corrosion treatment layer 14a and the second anti-corrosion treatment layer 14b can be layers with the same composition or layers with different compositions.

[0084] The first and second anti-corrosion treatment layers 14a and 14b (hereinafter also referred to as "anti-corrosion treatment layers 14a and 14b") are formed, for example, by degreasing treatment, hydrothermal modification treatment, anodizing treatment, chemical conversion treatment, or a combination of these treatments.

[0085] As a degreasing process, acid degreasing and alkali degreasing can be listed.

[0086] Examples of acid degreasing include methods using inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, and hydrofluoric acid alone, as well as methods using mixtures of these inorganic acids. Furthermore, in acid degreasing, it is preferable to use an acid degreasing agent prepared by dissolving a fluorine-containing compound such as sodium difluoride in the aforementioned inorganic acids. In this case, especially when aluminum foil is used as the barrier layer 13, a degreasing effect on aluminum is achieved. Moreover, the acid degreasing agent can form passivated aluminum fluorides, which is effective in terms of corrosion resistance.

[0087] For alkaline degreasing, methods such as using sodium hydroxide can be cited.

[0088] As a hydrothermal modification treatment, examples include boehmite treatment, which involves impregnating aluminum foil in boiling water with added triethanolamine.

[0089] Anodizing treatments, for example, include alumite treatment.

[0090] As a type of chemical conversion treatment, impregnation-type chemical conversion treatment and coating-type chemical conversion treatment can be listed.

[0091] Examples of impregnation-type chemical conversion treatments include: chromate treatment, zirconium treatment, titanium treatment, vanadium treatment, molybdenum treatment, calcium phosphate treatment, strontium hydroxide treatment, cerium treatment, ruthenium treatment, or various chemical conversion treatments consisting of mixtures thereof.

[0092] On the other hand, as a coating-type chemical conversion treatment, a method of coating a coating agent with anti-corrosion properties onto the barrier layer 13 can be listed.

[0093] In these anti-corrosion treatments, when at least a portion of the anti-corrosion layer is formed by any of the hydrothermal modification treatment, anodizing treatment, or chemical conversion treatment, it is preferable to perform the above-mentioned degreasing treatment beforehand. It should be noted that when using metal foil that has undergone degreasing treatment, such as annealed metal foil, as the barrier layer 13, it is not necessary to perform degreasing treatment again in the formation of the anti-corrosion layers 14a and 14b.

[0094] The coating agent used for coating-type chemical conversion treatment preferably contains trivalent chromium. Additionally, the coating agent may contain at least one polymer selected from the group consisting of cationic and anionic polymers.

[0095] Furthermore, in the above-mentioned processes, particularly in the hydrothermal modification and anodizing processes, the aluminum foil surface is dissolved by the treatment agent, thereby forming aluminum compounds (boehmite, acid-resistant aluminum) with excellent corrosion resistance. As a result, a co-continuous structure is obtained from the barrier layer 13 using aluminum foil to the anti-corrosion treatment layers 14a and 14b, and thus the above-mentioned processes are also included in the definition of chemical conversion processing.

[0096] As described later, the anti-corrosion treatment layers 14a and 14b can also be formed using a simple coating method not included in the definition of chemical conversion treatment. Examples of such methods include using a sol of rare earth element oxides, such as cerium oxide, with an average particle size of less than 100 nm as a material that provides corrosion protection against aluminum (corrosion inhibitor effect) and is also environmentally friendly. By using this method, even ordinary coating methods can impart anti-corrosion effects to metal foils such as aluminum foil.

[0097] Sols containing the aforementioned rare earth element oxides can include, for example, sols using various solvents such as aqueous solvents, alcohol solvents, hydrocarbon solvents, ketone solvents, ester solvents, and ether solvents. Among these, sols using aqueous solvents are preferred.

[0098] In the sols of the aforementioned rare earth element oxides, inorganic acids such as nitric acid, hydrochloric acid, and phosphoric acid, or their salts, and organic acids such as acetic acid, malic acid, ascorbic acid, and lactic acid are typically used as dispersion stabilizers to stabilize their dispersion. Among these dispersion stabilizers, phosphoric acid is particularly desirable, as it has the following effects (1) to (4) in the encapsulation material 10.

[0099] (1) Stabilize the dispersion of the sol

[0100] (2) The aluminum chelating ability of phosphoric acid is used to improve the adhesion between the barrier layer 13 and the anti-corrosion treatment layers 14a and 14b.

[0101] (3) Corrosion resistance is imparted by capturing aluminum ions (passive state formation).

[0102] (4) Phosphoric acid dehydration condensation can easily occur even at low temperatures, thereby improving the cohesion of the anti-corrosion treatment layer (oxide layer) 14a and 14b.

[0103] The anti-corrosion treatment layers 14a and 14b formed from the aforementioned rare earth element oxide sols are aggregates of inorganic particles. Therefore, even after the drying and curing process, the cohesiveness of the layers themselves may decrease. Thus, in order to replenish the cohesiveness, the anti-corrosion treatment layers 14a and 14b are preferably composited using anionic or cationic polymers.

[0104] The anti-corrosion treatment layers 14a and 14b are not limited to the aforementioned layers. For example, as with coated chromates, which are known technologies, the anti-corrosion treatment layers 14a and 14b can also be formed using a treatment agent made by combining phosphoric acid and a chromium compound in a resin binder (such as aminophenol). If this treatment agent is used, the anti-corrosion treatment layers 14a and 14b can be formed as layers that combine both anti-corrosion function and adhesion. Alternatively, although the stability of the coating solution needs to be considered, a coating agent obtained by liquefying a rare earth element oxide sol with a polycationic polymer or a polyanionic polymer can be used to form the anti-corrosion treatment layers 14a and 14b as layers that combine both anti-corrosion function and adhesion.

[0105] Regardless of whether it is a multi-layer or single-layer structure, the preferred mass per unit area of ​​the anti-corrosion treatment layers 14a and 14b is 0.005–0.200 g / m². 2 More preferably, it is 0.010–0.100 g / m 2 If the mass per unit area is 0.005 g / m² 2 The above methods easily impart anti-corrosion properties to the barrier layer 13. Furthermore, even if the mass per unit area exceeds 0.200 g / m²... 2 The anti-corrosion function remains largely unchanged. However, when using rare earth element oxide sols, if the coating is thick, the curing process using heat during drying becomes insufficient, potentially leading to a decrease in cohesion. It should be noted that the thickness of the anti-corrosion treatment layers 14a and 14b can be calculated from their specific gravity.

[0106] From the viewpoint of easily maintaining the tightness of the sealing layer 16 and the barrier layer 13, the anti-corrosion treatment layers 14a and 14b can be, for example, in the form of cerium oxide, phosphoric acid or phosphate in the form of 1 to 100 parts by mass relative to 100 parts by mass of the cerium oxide, and a cationic polymer; they can also be in the form of a barrier layer 13 formed by chemical conversion treatment; or they can be in the form of a barrier layer 13 formed by chemical conversion treatment and containing a cationic polymer.

[0107] <Thermo-adhesive resin layer>

[0108] The heat-adhesive resin layer 15 is a layer that bonds the sealing layer 16 and the barrier layer 13 together, and contains a heat-adhesive resin.

[0109] There are no particular limitations on the type of heat-adhesive resin; it can include polyolefin resins, preferably acid-modified polyolefin resins. In this case, the heat-adhesive resin layer 15 provides sufficient adhesion to both the sealing layer 16 and the barrier layer 13.

[0110] The acid-modified polyolefin resin can be a polyolefin resin modified from at least one selected from the group consisting of maleic anhydride, carboxylic acid, sulfonic acid, and their derivatives. The acid-modified polyolefin resin can be, for example, a graft copolymer, block copolymer, or random copolymer. From the viewpoint of the adhesion between the thermally adhesive resin layer 15 and the barrier layer 13, the acid-modified polyolefin resin is preferably a polyolefin resin graft-modified from maleic anhydride.

[0111] The aforementioned polyolefin resin may be, for example, a polypropylene resin, a polyethylene resin, a polybutene resin, a polypentene resin, a polyoctene resin, or a polymethylpentene resin.

[0112] Polypropylene resins are resins containing polymeric monomers comprising propylene, and serve to impart hardness to the heat-adhesive resin layer 15. Examples of polypropylene resins include homopolymer polypropylene (homogeneous PP), block polypropylene (block PP), and atactic polypropylene. They can be used alone or in combination of two or more. From the viewpoint of imparting appropriate hardness to the heat-adhesive resin layer 15, polypropylene resins containing at least one of homopolymer polypropylene and block polypropylene are preferred.

[0113] In addition to acid-modified polyolefin resins, the resin contained in the thermally adhesive resin layer 15 may also include unmodified polyolefin resins such as polyethylene resins, polypropylene resins, polybutene resins, polypentene resins, polyoctene resins, or polymethylpentene resins.

[0114] Examples of polyethylene-based resins include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and polyethylene-based elastomers. These can be used individually or in combination of two or more. In particular, polyethylene-based elastomers are preferred as polyethylene-based resins, especially considering their ability to impart flexibility to the thermally bondable resin layer 15.

[0115] As a polyethylene-based elastomer, an elastomer using an α-olefin as a comonomer can be used. Specifically, examples of such polyethylene-based elastomers include compounds obtained by copolymerizing an α-olefin composed of at least one selected from 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene with ethylene.

[0116] There is no particular limitation on the content of polypropylene resin in the heat-adhesive resin layer 15. For example, it can be 30 to 100% by mass. From the viewpoint of balancing the hardness and softness of the heat-adhesive resin layer 15, it is preferably 50 to 95% by mass, and more preferably 70 to 90% by mass.

[0117] There is no particular limitation on the content of polyethylene resin in the heat-adhesive resin layer 15, for example, it can be 2 to 70% by mass. From the viewpoint of balancing the hardness and softness of the heat-adhesive resin layer 15, it is preferably 5 to 50% by mass, and more preferably 10 to 30% by mass.

[0118] When the heat-adhesive resin layer 15 contains polypropylene resin and polyethylene resin, the polypropylene resin and polyethylene resin may be the same as or different from one or both of the polypropylene resin (A) and polyethylene resin (B) contained in the sealing layer 16.

[0119] Depending on the requirements, the thermally adhesive resin layer 15 may contain various additives such as compatible and incompatible elastomers, flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, crystal nucleating agents, and tackifiers.

[0120] <Sealing layer>

[0121] The sealing layer 16 is a layer that imparts a seal to the encapsulation material 10 through heat sealing. It is a layer that is placed on the inside and heat-sealed (heat-welded) during the assembly of the energy storage device.

[0122] The sealing layer 16 is a layer containing a heat-sealing resin. The heat-sealing resin preferably contains a polypropylene-based resin (A). The sealing layer 16 may further contain a polyethylene-based resin (B), or it may not contain a polyethylene-based resin (B), but from the viewpoint of controlling the stress relief of the sealing layer 16 and easily controlling the hydrogen sulfide permeation, it is preferable to further contain a polyethylene-based resin (B).

[0123] Polypropylene resins are resins containing polymeric monomers comprising propylene, and they serve to impart hardness to the sealing layer 16. Examples of polypropylene resins include homopolymer polypropylene (HPP), block polypropylene (PP), and atactic polypropylene. They can be used alone or in combination of two or more. Polypropylene resins are suitable as sealants, and from the viewpoint of imparting appropriate hardness to the sealing layer 16, it is preferable to include at least one of homopolymer polypropylene and block polypropylene.

[0124] Polyethylene-based resin (B) is a resin obtained from polymeric monomers containing ethylene, which imparts flexibility (stress relief) to the sealing layer 16. Examples of polyethylene-based resins include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and polyethylene-based elastomers. They can be used alone or in combination of two or more. In particular, considering its ability to impart flexibility to the sealing layer 16, a polyethylene-based resin containing a polyethylene-based elastomer is preferred.

[0125] As a polyethylene-based elastomer, an elastomer using an α-olefin as a comonomer can be used. Specifically, examples of such a polyethylene-based elastomer include ethylene-α-olefin copolymers obtained by copolymerizing an α-olefin composed of at least one selected from 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene with ethylene.

[0126] Preferably, the sealing layer 16 contains a polypropylene resin (A) comprising at least one of homopolymer polypropylene and block polypropylene, and a polyethylene resin (B), wherein the polyethylene resin (B) has at least one melting peak in the range of 60°C to 105°C.

[0127] In this case, the improved dispersibility of polyethylene resin relative to polypropylene resin in sealing layer 16 results in more effective stress relief, thus effectively suppressing the reduction in insulation of encapsulation material 10 caused by stretching.

[0128] The temperature range of the melting peak (hereinafter referred to as "melting peak temperature") is preferably 70°C to 100°C, more preferably 75°C to 95°C, and even more preferably 82°C to 95°C.

[0129] By including a polyethylene resin containing a melting peak within the aforementioned melting peak temperature range in the sealing layer 16, the dispersibility of the polyethylene resin contained in the sealing layer 16 is improved, resulting in effective stress relief. Therefore, the reduction in insulation of the encapsulation material for the energy storage device caused by stretching can be effectively suppressed.

[0130] It should be noted that the melting peak temperature in this specification was determined by differential scanning calorimetry (DSC) according to JIS K 7121-1987.

[0131] There is no particular limitation on the ratio of the weight-average molecular weight Mw to the number-average molecular weight Mn (hereinafter also referred to as "Mw / Mn") of the polyethylene resin (B) contained in the sealing layer 16, but it is preferably 1.2 or more and 5.0 or less.

[0132] With the Mw / Mn ratio of the polyethylene resin within the aforementioned range, the dispersibility of the polyethylene resin relative to the polypropylene resin in the sealing layer 16 is further improved, resulting in more effective stress relief. Therefore, it is possible to more effectively suppress the reduction in insulation of the encapsulation material for the energy storage device caused by stretching.

[0133] It should be noted that the number-average molecular weight Mn and weight-average molecular weight Mw in this specification refer to the number-average molecular weight Mn and weight-average molecular weight Mw obtained by gel permeation chromatography (GPC) at a measurement temperature of 145℃, according to JIS K7252-1 and 4:2016, converted to polystyrene.

[0134] Mw / Mn is preferably 1.5 or more and 4.5 or less, more preferably 2.0 or more and 4.0 or less.

[0135] There is no particular limitation on the content of polypropylene resin in the sealing layer 16, for example, it can be 30 to 100% by mass. From the viewpoint of balancing the hardness and softness of the sealing layer 16, it is preferably 50 to 95% by mass, and more preferably 70 to 90% by mass.

[0136] There is no particular limitation on the content of polyethylene resin in the sealing layer 16, for example, it can be 2 to 70% by mass. From the viewpoint of balancing the hardness and softness of the sealing layer 16, it is preferably 5 to 50% by mass, and more preferably 10 to 30% by mass.

[0137] In addition to the polypropylene resin (A) and polyethylene resin (B) mentioned above, the sealing layer 16 may also contain other additives such as slip agents, anti-blocking agents, antioxidants, light stabilizers, crystallizing nucleating agents, and flame retardants as needed.

[0138] When the total mass of the sealing layer 16 is set to 100% by mass, the content of these added components is preferably 5% by mass or less.

[0139] From the viewpoint of improving the hardness of the sealing part, the ratio of the thickness of the sealing layer 16 to the thickness of the heat-adhesive resin layer 15 (thickness of sealing layer 16 / thickness of heat-adhesive resin layer 15) is preferably 1 or more, more preferably 1.1 or more, and particularly preferably 1.5 or more.

[0140] From the viewpoint of improving the hardness of the sealing part, the ratio of the thickness of the sealing layer 16 to the thickness of the heat-adhesive resin layer 15 (thickness of sealing layer 16 / thickness of heat-adhesive resin layer 15) is preferably 10 or less, more preferably 3 or less.

[0141] The combined thickness of the sealing layer 16 and the thermally adhesive resin layer 15 can be 15 to 300 μm, but from the viewpoint of the sealing and water vapor barrier properties of the encapsulation material 10, it is preferably 25 to 150 μm, and more preferably 40 to 100 μm.

[0142] When the encapsulation material, such as encapsulation material 10, comprises a thermally adhesive resin layer 15 and a sealing layer 16, resin compositions for forming each layer can be prepared separately and laminated using a T-die method or a blow molding method. Alternatively, one layer can be laminated by extruding another layer after forming a film, or by bonding the layers together using an adhesive after forming each layer using a T-die method or a blow molding method. From the viewpoint of interfacial adhesion between the layer composed of the adhesive and the layer bonded to it, an adhesive containing acid-modified polypropylene and a curing agent (such as isocyanate) can be used as the adhesive.

[0143] <Laminated structure of sealing layer and heat-adhesive resin layer>

[0144] The hydrogen sulfide permeability coefficient of the laminate 17 consisting of the sealing layer 16 and the thermally adhesive resin layer 15 is 1.1 × 10⁻⁶. -9 cc·mm / cm 2 ·sec·cmHg or higher and less than 1.0×10 -8 cc·mm / cm 2 ·sec·cmHg.

[0145] With the hydrogen sulfide permeability coefficient of the laminate 17 within the aforementioned range, the laminate 17 is neither too hard nor too soft. Even when stress is applied to the laminate 17 during the stretching of the encapsulation material 10, the stress as a whole of the laminate 17 is mitigated, thus suppressing the generation of cracks in the laminate 17. As a result, even when the encapsulation material 10 is stretched, the reduction in the insulation of the encapsulation material 10 can be suppressed.

[0146] The hydrogen sulfide permeability coefficient of the laminate 17 is preferably 2.5 × 10⁻⁶. -9 cc·mm / cm 2 •sec·cmHg or more, more preferably 3.5×10 -9 cc·mm / cm 2 Above ·sec·cmHg.

[0147] The hydrogen sulfide permeability coefficient of the laminate 17 is preferably 8.5 × 10⁻⁶. -9 cc·mm / cm 2 Less than ·sec·cmHg, more preferably 7.5×10 -9 cc·mm / cm 2 Less than 6.5 × 10⁻⁶ sec·cmHg, more preferably 6.5 × 10⁻⁶. -9 cc·mm / cm 2 Below ·sec·cmHg.

[0148] It should be noted that, in this specification, the hydrogen sulfide permeability coefficient of the laminate 17 refers to the hydrogen sulfide permeability coefficient in the thickness direction of the laminate 17.

[0149] The hydrogen sulfide permeability coefficient of the laminate 17 can be determined by a gas permeation test. The method for determining the hydrogen sulfide permeability coefficient of the laminate 17 is described below.

[0150] (1) First, as shown in FIG3, the measurement sample 35 cut from the laminate 17 is positioned between the upper part 31 and the lower part 36 of the separable flask.

[0151] (2) Next, at the test temperature (23±5℃), nitrogen gas is introduced through the vent 32 of the upper part 31 of the separable container at a flow rate of 50 mL / min, and exhaust is carried out through the vent 33. On the other hand, hydrogen sulfide gas is introduced through the vent 37 at a flow rate of 50 mL / min, and exhaust is carried out through the vent 38. At this time, hydrogen sulfide gas is introduced together with nitrogen gas, and the concentration of hydrogen sulfide gas in nitrogen gas is 20±5 ppm by volume.

[0152] (3) Next, 24 hours after the start of ventilation, a resin bag is connected to the ventilation port 33, and 0.5L of sample gas is collected within 10 minutes.

[0153] (4) Next, the concentration of the sample gas collected in the resin bag (the concentration of hydrogen sulfide gas in the sample gas) was determined using a gas chromatograph-flame photometric detector (GC-FPD).

[0154] (5) Perform the above (3) and (4) operations 48 hours and 96 hours after the start of ventilation.

[0155] (6) Based on the average concentration (unit: volume ppb) of the sample gas collected after 24 hours, 48 ​​hours and 96 hours (average sample gas concentration), calculate the hydrogen sulfide permeation rate (nL / hr) per hour using the following formula 1.

[0156] (Formula 1) Hydrogen sulfide permeation rate (nL / hr) = Average sample gas concentration (volume ppb≒nL / L) × Gas volume collected per hour (※)

[0157] (※) The flow rate of nitrogen gas used as the test gas is 50 mL / min, so the amount of gas collected every hour is 3 L.

[0158] Based on the obtained hydrogen sulfide permeation rate, use the following formula 2 to calculate the hydrogen sulfide permeation rate per unit area and per day, i.e., the hydrogen sulfide permeability (cc / m²). 2 ·day).

[0159] (Equation 2) Hydrogen sulfide permeability (cc / m) 2•day) = Hydrogen sulfide permeation rate (nL / hr) × 24 (hr) / 10 6 / Effective test area (m²) 2 )

[0160] It should be noted that the effective test area uses the opening area of ​​the separable container, "0.00453m²". 2 ".

[0161] (7) Finally, the unit of hydrogen sulfide transmittance was converted to cc·mm / cm. 2 ·sec·cmHg, calculate the hydrogen sulfide permeability coefficient.

[0162] The preferred embodiments of the encapsulation material of this embodiment have been described in detail above, but this disclosure is not limited to the specific embodiments described above.

[0163] For example, Figure 1 shows the case where a thermally adhesive resin layer 15 is used as the adhesive layer, but a second adhesive layer 12b can also be used as the adhesive layer, as shown in Figure 2 for the encapsulation material 20.

[0164] <Second adhesive layer>

[0165] Here, the second adhesive layer 12b will be described.

[0166] The second adhesive layer 12b is the layer that bonds the barrier layer 13 to the sealing layer 16. The second adhesive layer 12b can use a common adhesive for bonding the barrier layer 13 and the sealing layer 16.

[0167] When the second adhesive layer 12b is used as the adhesive layer, the hydrogen sulfide permeability coefficient of the sealing layer 16 is 1.1 × 10⁻⁶. -9 cc·mm / cm 2 ·sec·cmHg or higher and less than 1.0×10 -8 cc·mm / cm 2 •sec·cmHg. The hydrogen sulfide permeability coefficient of the sealing layer 16 is a value determined by the same method as the method used to determine the hydrogen sulfide permeability coefficient of the laminate 17 described above.

[0168] The hydrogen sulfide permeability through sealing layer 16 is 1.1 × 10⁻⁶. -9 cc·mm / cm 2 With a strength of ·sec·cmHg or higher, the sealing layer 16 is neither too hard nor too soft. Even when stress is applied to the sealing layer 16 during the stretching of the encapsulation material 20, the stress is mitigated within the sealing layer 16, thus suppressing the formation of cracks in the sealing layer 16. As a result, even when the encapsulation material 20 is stretched, the reduction in the insulation of the sealing layer 16 can be suppressed, thereby suppressing the reduction in the insulation of the encapsulation material 20.

[0169] The hydrogen sulfide permeability through sealing layer 16 is 1.0 × 10⁻⁶. -8 cc·mm / cm 2 Below ·sec·cmHg, the sealing layer 16 is neither too hard nor too soft. Even when stress is applied to the sealing layer 16 when the encapsulation material 20 is stretched, the stress in the sealing layer 16 is mitigated, thus suppressing the formation of cracks in the sealing layer 16. As a result, even when the encapsulation material 20 is stretched, the reduction in the insulation of the encapsulation material 20 can be suppressed.

[0170] The hydrogen sulfide permeability coefficient of the sealing layer 16 is preferably 2.5 × 10⁻⁶. -9 cc·mm / cm 2 •sec·cmHg or more, more preferably 3.5×10 -9 cc·mm / cm 2 Above ·sec·cmHg.

[0171] Furthermore, the hydrogen sulfide permeability coefficient of the sealing layer 16 is preferably 8.5 × 10⁻⁶. -9 cc·mm / cm 2 Less than ·sec·cmHg, more preferably 7.5×10 -9 cc·mm / cm 2 Less than 6.5 × 10⁻⁶ sec·cmHg, more preferably 6.5 × 10⁻⁶. -9 cc·mm / cm 2 Below ·sec·cmHg.

[0172] When the second adhesive layer 12b is used as the adhesive layer, the thickness of the sealing layer 16 can be 15 to 300 μm. From the viewpoint of the sealing and water vapor barrier properties of the encapsulation material 20, it is preferably 25 to 150 μm, and more preferably 40 to 100 μm.

[0173] When the barrier layer 13 is provided with an anti-corrosion treatment layer 14b and the second anti-corrosion treatment layer 14b has a layer containing at least one polymer selected from the group consisting of cationic polymers and anionic polymers, the second adhesive layer 12b is preferably a layer containing a compound (hereinafter also referred to as "reactive compound") that is reactive with the polymer contained in the second anti-corrosion treatment layer 14b.

[0174] For example, if the second anti-corrosion treatment layer 14b contains a cationic polymer, the second adhesive layer 12b preferably contains a compound that is reactive with the cationic polymer.

[0175] When the second anti-corrosion treatment layer 14b contains an anionic polymer, the second adhesive layer 12b preferably contains a compound that is reactive with the anionic polymer.

[0176] Furthermore, if the second anti-corrosion layer 14b contains both cationic and anionic polymers, the second adhesive layer 12b preferably contains compounds that react with both cationic and anionic polymers. However, the second adhesive layer 12b does not necessarily have to contain both of these compounds; it may also contain compounds that react with both cationic and anionic polymers. Here, "reactive" means forming covalent bonds with either the cationic or anionic polymer. Additionally, the second adhesive layer 12b may also contain an acid-modified polyolefin resin.

[0177] As compounds that are reactive with cationic polymers, at least one compound selected from the group consisting of polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxyl group, and compounds having an oxazoline group can be listed.

[0178] Examples of these polyfunctional isocyanate compounds, glycidyl compounds, carboxyl-containing compounds, and oxazoline-containing compounds include those used as crosslinking agents for forming crosslinked structures in cationic polymers. Among these compounds, polyfunctional isocyanate compounds are preferred from the viewpoint of high reactivity with cationic polymers and ease of forming crosslinked structures.

[0179] As compounds that are reactive with anionic polymers, at least one compound selected from the group consisting of glycidyl compounds and compounds having an oxazoline group can be listed.

[0180] Examples of glycidyl compounds or compounds containing oxazoline groups include glycidyl compounds used as crosslinking agents for forming crosslinked structures in cationic polymers and compounds containing oxazoline groups. Among these compounds, glycidyl compounds are preferred from the viewpoint of high reactivity with anionic polymers.

[0181] When the second adhesive layer 12b contains an acid-modified polyolefin resin, the reactive compound preferably also reacts with the acidic groups in the acid-modified polyolefin resin (i.e., forms covalent bonds with the acidic groups).

[0182] As a result, the adhesion between the second adhesive layer 12b and the second anti-corrosion treatment layer 14b is further improved. Furthermore, the acid-modified polyolefin resin forms a cross-linked structure, further improving the solvent resistance of the encapsulation material 20.

[0183] The content of reactive compounds can be from 1 to 10 times the equivalent of the acidic groups in acid-modified polyolefin resins.

[0184] If the content of the reactive compound is 1 equivalent or more, the reactive compound reacts sufficiently with the acidic groups in the acid-modified polyolefin resin. On the other hand, when the content of the reactive compound exceeds 10 equivalents, the crosslinking reaction with the acid-modified polyolefin resin reaches full saturation, thus raising concerns about unreacted substances in the second adhesive layer 12b and a reduction in various properties. Therefore, for example, the content of the reactive compound is preferably 5 to 20 parts by weight (solids ratio) relative to 100 parts by weight of the acid-modified polyolefin resin.

[0185] Acid-modified polyolefin resin is obtained by introducing acidic groups into a polyolefin resin. Examples of acidic groups include carboxyl groups, sulfonic acid groups, and anhydride groups, with maleic anhydride groups and (meth)acrylic acid groups being particularly preferred. For example, the same modified polyolefin resin used for the sealing layer 16 can be used as the acid-modified polyolefin resin.

[0186] In the second adhesive layer 12b, various additives such as flame retardants, slip agents, anti-blocking agents, antioxidants, light stabilizers, and tackifiers may also be added.

[0187] From the viewpoint of suppressing the reduction in heat-sealing strength of the encapsulation material 10 when it is associated with corrosive gases such as hydrogen sulfide and electrolytes, and from the viewpoint of further suppressing the reduction in insulation of the encapsulation material 10, the second adhesive layer 12b may, for example, contain an acid-modified polyolefin and at least one curing agent selected from the group consisting of polyfunctional isocyanate compounds, glycidyl compounds, compounds having carboxyl groups, compounds having oxazoline groups, and carbodiimide compounds.

[0188] It should be noted that, as carbodiimide compounds, examples include: N,N'-di-o-tolyl carbodiimide, N,N'-diphenylcarbodiimide, N,N'-di-2,6-dimethylphenylcarbodiimide, N,N'-bis(2,6-diisopropylphenyl)carbodiimide, N,N'-dioctyldecylcarbodiimide, N-tolyl-N'-cyclohexylcarbodiimide, N,N'-di-2,2-di-tert-butylphenylcarbodiimide, N-tolyl-N'-phenylcarbodiimide, N,N'-di-p-nitrophenylcarbodiimide, N,N'-di-p-aminophenylcarbodiimide, N,N'-di-p-hydroxyphenylcarbodiimide, N,N'-dicyclohexylcarbodiimide, and N,N'-di-p-tolyl carbodiimide, etc.

[0189] Alternatively, as the adhesive forming the second adhesive layer 12b, a polyurethane-based adhesive, such as one composed of a polyester polyol (composed of hydrogenated dimer fatty acids and glycols) and a polyisocyanate, can also be used. Examples of adhesives include polyurethane resins formed by reacting difunctional or higher isocyanate compounds with a main agent such as a polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol; or epoxy resins formed by reacting an amine compound with a main agent having an epoxy group. These are preferred from the viewpoint of the heat resistance of the encapsulation material 10.

[0190] The thickness of the second adhesive layer 12b is not particularly limited, but from the viewpoint of obtaining the desired adhesive strength and processability of the second adhesive layer 12b, it is preferably 1 to 10 μm, more preferably 2 to 7 μm.

[0191] [Manufacturing methods for encapsulation materials]

[0192] Next, an example of a method for manufacturing the encapsulation material 10 shown in Figure 1 will be described. It should be noted that the method for manufacturing the encapsulation material 10 is not limited to the following method.

[0193] The manufacturing method of the encapsulation material 10 in this embodiment generally includes: a step of providing anti-corrosion treatment layers 14a and 14b on the barrier layer 13; a step of bonding the substrate layer 11 to the barrier layer 13 using a first adhesive layer 12a; a step of further laminating a thermally adhesive resin layer 15 and a sealing layer 16 on the surface of the barrier layer 13 on the side of the anti-corrosion treatment layer 14b to form a laminate; and a step of aging the resulting laminate as needed.

[0194] (The process of layering an anti-corrosion treatment layer onto a barrier layer)

[0195] This process involves forming anti-corrosion treatment layers 14a and 14b on the barrier layer 13. As described above, methods for this process include: degreasing the barrier layer 13, hydrothermal modification, anodizing, or chemical conversion, or applying a coating agent with anti-corrosion properties.

[0196] In addition, when the anti-corrosion treatment layers 14a and 14b are multi-layered, for example, the coating liquid (coating agent) constituting the lower layer side (barrier layer 13 side) of the anti-corrosion treatment layer can be applied to the barrier layer 13 and baked to form the first layer, and then the coating liquid (coating agent) constituting the upper layer side of the anti-corrosion treatment layer can be applied to the first layer and baked to form the second layer.

[0197] Degreasing can be performed using spraying or immersion methods. Hydrothermal modification or anodizing can be performed using immersion methods. For chemical conversion treatments, depending on the type of chemical conversion treatment, immersion, spraying, or coating methods can be appropriately selected.

[0198] Various methods can be used for coating agents with anti-corrosion properties, such as gravure coating, reverse coating, roller coating, and bar coating.

[0199] As described above, various treatments of the barrier layer 13 can be performed on either side or one side of the barrier layer 13 (e.g., metal foil). In the case of single-side treatment, it is preferable to perform the above treatment on one side of the laminated sealing layer 16. It should be noted that, depending on the requirements, the above treatment can also be performed on the surface of the substrate layer 11.

[0200] Furthermore, the coating amount of the coating agent used to form both the first and second layers is preferably 0.005 to 0.200 g / m². 2 More preferably, it is 0.010–0.100 g / m 2 .

[0201] Alternatively, when drying and curing are required, depending on the drying conditions of the anti-corrosion treatment layers 14a and 14b used, drying and curing can be carried out at a temperature ranging from 60 to 300°C. Here, the base material temperature refers to the temperature of the barrier layer 13 (e.g., metal foil).

[0202] (The bonding process between the substrate layer and the barrier layer)

[0203] This process involves bonding the barrier layer 13, which has anti-corrosion treatment layers 14a and 14b, to the substrate layer 11 via the first adhesive layer 12a. The substrate layer 11 is bonded to the surface of the barrier layer 13 on the side of the anti-corrosion treatment layer 14a.

[0204] As a bonding method, dry lamination, solvent-free lamination or wet lamination are used to bond the two (barrier layer 13 and substrate layer 11) together using the material constituting the first adhesive layer 12a.

[0205] The dry coating amount of the first adhesive layer 12a is preferably set to 1-10 g / m. 2 The range is preferably set to 2-7 g / m 2 The range.

[0206] (Laying process of thermally adhesive resin layer and sealing layer)

[0207] The lamination process of the thermally adhesive resin layer 15 and the sealing layer 16 is a process of forming the thermally adhesive resin layer 15 and the sealing layer 16 on the surface of the anti-corrosion treatment layer 14b side of the barrier layer 13.

[0208] As a method, one example is to use an extrusion laminator to sandwich-lamination the thermally adhesive resin layer 15 together with the anti-corrosion treatment layer 14b and the sealing layer 16.

[0209] Alternatively, lamination can be performed by tandem lamination of the thermo-adhesive resin layer 15 and the sealing layer 16 or by co-extrusion.

[0210] In the formation of the heat-adhesive resin layer 15, a resin composition for forming a heat-adhesive resin layer containing the constituent components of the heat-adhesive resin layer 15 is used.

[0211] In the formation of the sealing layer 16, a resin composition for forming the sealing layer containing the constituent components of the sealing layer 16 described above is used.

[0212] The laminate 17 of the thermally adhesive resin layer 15 and the sealing layer 16 has a hydrogen sulfide permeability coefficient of 1.1 × 10⁻⁶. -9 ~1.0×10 -8 [cc·mm / cm 2 It is formed in the manner of ·sec·cmHg]. For this purpose, for example, the resins used for the polypropylene resin (A) and polyethylene resin (B) contained in the sealing layer 16, and the resin used for the heat-adhesive resin layer 15 are appropriately selected, taking into account crystallinity and melting point, and the composition of the resin is appropriately set, so as to adjust the hardness and softness of the heat-adhesive resin layer 15 and the sealing layer 16 in a way that balances the hardness and softness.

[0213] Through the lamination process of the thermally adhesive resin layer 15 and the sealing layer 16, a laminate is obtained as shown in FIG1, which is formed by laminating the substrate layer 11, the first adhesive layer 12a, the first anti-corrosion treatment layer 14a, the barrier layer 13, the second anti-corrosion treatment layer 14b, the thermally adhesive resin layer 15 and the sealing layer 16 in that order.

[0214] It should be noted that the thermoplastic resin layer 15 can be laminated by directly extruding the dry-mixed components of the resin composition for forming the thermoplastic resin layer using an extrusion laminator. Alternatively, it can be pre-melted and granulated using a melt-kneading device such as a uniaxial extruder, biaxial extruder, or Brabender mixer, and then extruded using an extrusion laminator to laminate the thermoplastic resin layer 15.

[0215] The sealing layer 16 can be laminated by directly extruding the dry-mixed components of the resin composition used to form the sealing layer using an extrusion laminator. Alternatively, regarding the thermosetting resin layer 15 and the sealing layer 16, they can be pre-melted using a melt-kneading device such as a uniaxial extruder, a biaxial extruder, or a Brabender mixer to obtain granules, and then laminated using an extrusion laminator by tandem lamination or co-extrusion of the thermosetting resin layer 15 and the sealing layer 16.

[0216] Alternatively, regarding the heat-adhesive resin layer 15 and the sealing layer 16, a sealing layer forming resin composition can be used to pre-prepare the sealing layer 16 as a casting film, and the sealing layer 16 can be laminated together with the heat-adhesive resin layer 15 using a sandwich lamination method.

[0217] From the perspective of the productivity of the encapsulation material 10, the formation rate (processing speed) of the thermally adhesive resin layer 15 and the sealing layer 16 can be, for example, 80 m / min or more.

[0218] (Aging process)

[0219] The aging process is a process of aging (curing) the laminate. By aging the laminate, the bonding between the substrate layer 11, the first adhesive layer 12a, the first anti-corrosion treatment layer 14a, and the barrier layer 13 can be promoted; as well as the bonding between the barrier layer 13, the second anti-corrosion treatment layer 14b, the thermally adhesive resin layer 15, and the sealing layer 16.

[0220] The aging temperature can be above 80℃, above 100℃, or above 120℃, or below 140℃, below 150℃, or below 160℃.

[0221] The aging time can be more than 1 hour, more than 2 hours, or more than 3 hours, or less than 24 hours, less than 48 hours, or less than 72 hours.

[0222] In this way, the encapsulation material 10 shown in Figure 1 can be manufactured.

[0223] Next, an example of a method for manufacturing the encapsulation material 20 for the energy storage device shown in Figure 2 will be described. It should be noted that the method for manufacturing the encapsulation material 20 is not limited to the following method.

[0224] The manufacturing method of the encapsulation material 20 in this embodiment generally includes: a step of providing anti-corrosion treatment layers 14a and 14b on the barrier layer 13; a step of bonding the substrate layer 11 to the barrier layer 13 using a first adhesive layer 12a; a step of bonding the sealing layer 16 to the anti-corrosion treatment layer 14b side of the barrier layer 13 via a second adhesive layer 12b to obtain a laminate; and a step of aging the obtained laminate as needed.

[0225] Up to the step of bonding the substrate layer 11 and the barrier layer 13 together using the first adhesive layer 12a, the process can be performed in the same manner as the manufacturing method of the encapsulation material 10 described above. The step of aging the resulting laminate can also be performed in the same manner as the manufacturing method of the encapsulation material 10 described above.

[0226] (Laying process of the second adhesive layer and sealant layer)

[0227] The lamination process of the second adhesive layer 12b and the sealing layer 16 is a process of attaching the sealing layer 16 to the anti-corrosion treatment layer 14b side of the barrier layer 13 via the second adhesive layer 12b to obtain the laminate.

[0228] Methods of bonding include wet processing and dry lamination.

[0229] In the case of wet processing, a solution or dispersion of the adhesive constituting the second adhesive layer 12b is applied to the anti-corrosion treatment layer 14b, and the solvent is removed at a predetermined temperature to dry and form a film, or a baking treatment is performed as needed after drying and forming the film.

[0230] Then, the sealing layer 16 is stacked.

[0231] Various coating methods can be listed as coating methods. The preferred dry coating amount of the second adhesive layer 12b is the same as that of the first adhesive layer 12a.

[0232] In this case, the sealing layer 16 can be manufactured, for example, by using a sealing layer forming resin composition containing the aforementioned polypropylene resin (A) and polyethylene resin (B), and by using a melt extrusion molding machine. From the viewpoint of the productivity of the encapsulation material 10, the processing speed of the melt extrusion molding machine can be set to 80 m / min or more.

[0233] The sealing layer 16 has a hydrogen sulfide permeability coefficient of 1.1 × 10⁻⁶. -9 ~1.0×10 -8[cc·mm / cm 2 It is formed in the manner of ·sec·cmHg]. For this purpose, for example, the resins used for the polypropylene resin (A) and polyethylene resin (B) contained in the sealing layer 16 are appropriately selected considering crystallinity and melting point, and the resin content in the polypropylene resin (A) and polyethylene resin (B) is appropriately set, etc., so as to adjust the hardness and softness of the sealing layer 16 in a way that balances the hardness and softness.

[0234] In this way, the encapsulation material 20 shown in Figure 2 can be manufactured.

[0235] [Electronic Storage Device]

[0236] Next, an energy storage device according to an embodiment of the present disclosure will be described with reference to FIG4. FIG4 is a perspective view of an energy storage device according to an embodiment of the present disclosure.

[0237] As shown in Figure 4, the energy storage device 50 includes an energy storage element 52 and a packaging bag 54 for housing the energy storage element 52. The energy storage device 50 may also include two metal terminals (current output terminals) 53 extending from the energy storage element 52 for outputting current to the outside. Here, the packaging bag 54 holds the metal terminals 53. In addition, the packaging bag 54 can house the energy storage element 52 in an airtight manner.

[0238] The packaging bag 54 is formed using packaging material 10. In the packaging material 10, the substrate layer 11 is the outermost layer, and the sealing layer 16 is the innermost layer. As shown in FIG4, the packaging bag 54 can be formed by folding one packaging material 10 in half and heat-sealing its periphery, such that the substrate layer 11 is the outer side of the energy storage device 50 and the sealing layer 16 is the inner side of the energy storage device 50, or by overlapping two packaging materials 10 and heat-sealing their periphery.

[0239] The metal terminal 53 is held by an encapsulation bag 54 that forms a container with the sealing layer 16 as the inner side. The metal terminal 53 may also be held by the encapsulation material 10 through the tab seal.

[0240] According to the energy storage device 50, when the energy storage element 52 expands and contracts with charging and discharging during the operation of the energy storage device 50, even if the encapsulation material 10 is stretched, the reduction of the insulation of the encapsulation bag 54 formed by the encapsulation material 10 can be suppressed, so the energy storage device 50 can have a longer life.

[0241] The energy storage element 52 has a positive electrode, a negative electrode, and an electrolyte. The electrolyte is disposed at least between the positive and negative electrodes.

[0242] Electrolytes can be liquid or solid. Examples of solid electrolytes include oxide-based solid electrolytes and sulfide-based solid electrolytes.

[0243] Metal terminal 53 is a terminal that is part of the current collector and is removed to the outside of the encapsulation material 10. It is made of metal foil such as copper foil and aluminum foil.

[0244] It should be noted that in the energy storage device 50, the encapsulation material 20 can also be used instead of the encapsulation material 10.

[0245] Specific examples of the energy storage device 50 include all-solid-state batteries, lithium-ion batteries, nickel-metal hydride batteries, and secondary batteries such as lead-acid batteries, electrochemical capacitors such as double-layer capacitors, and semi-solid-state batteries.

[0246] When the energy storage device 50 is an all-solid-state battery, that is, when the energy storage element 52 contains a solid electrolyte, the energy storage element 52 is particularly prone to expansion and contraction. However, even if the energy storage element 52 expands and contracts, the reduction in the insulation of the energy storage device encapsulation material 10 caused by stretching can be suppressed. Therefore, the reduction in the insulation of the encapsulation bag 54 can be suppressed, and the energy storage device 50 has a longer lifespan.

[0247] Example

[0248] The present disclosure will now be described in detail based on the embodiments, but the present disclosure is not limited to the following embodiments.

[0249] [Materials Used]

[0250] The materials used as the substrate layer, the adhesive for forming the first adhesive layer, the adhesive for forming the second adhesive layer, the material for forming the first anti-corrosion treatment layer and the material for forming the second anti-corrosion treatment layer, the barrier layer, the composition for forming the thermally adhesive resin layer and the composition for forming the sealing layer are as follows.

[0251] <Substrate Layer>

[0252] PET: Polyethylene terephthalate film with one side corona treated (25 μm thickness)

[0253] <Adhesive for forming the first adhesive layer>

[0254] An adhesive (Adhesive No. 1) is prepared by combining polyester polyol (manufactured by Showa Denko Materials Co., Ltd., trade name: TESLAC 2505-63, hydroxyl value: 7-11 mgKOH / g) and isophorone diisocyanate ureate (manufactured by Mitsui Chemicals Co., Ltd., trade name: Takenate 600) with an NCO / OH ratio of 20.0 and diluting with ethyl acetate to a solid content of 26% by mass.

[0255] <Adhesive for forming the second adhesive layer>

[0256] An adhesive (second adhesive) made by combining 10 parts by weight (solid content ratio) of a polyisocyanate compound with an isocyanurate structure relative to 100 parts by weight of an acid-modified polyolefin resin dissolved in toluene.

[0257] <Materials for forming the first and second anti-corrosion treatment layers>

[0258] The materials for forming the first anti-corrosion treatment layer (substrate layer side) and the materials for forming the second anti-corrosion treatment layer (sealing layer side) are as described in (CL-1) and (CL-2) below.

[0259] (CL-1): Sodium polyphosphate stabilized cerium oxide sol with solid components adjusted to 10% by mass using distilled water as a solvent.

[0260] It should be noted that sodium polyphosphate stabilized cerium oxide sol is obtained by combining 10 parts by mass of sodium salt of phosphate with 100 parts by mass of cerium oxide.

[0261] (CL-2): A composition in which the concentration of solid components is adjusted to 5% by mass using distilled water as a solvent.

[0262] It should be noted that in the above composition, the ratio of "polyallylamine (manufactured by Nitto Boshoku Co., Ltd.)" to "polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation)" is set to 90:10 (mass ratio).

[0263] <Barrier layer (40μm thick)>

[0264] Soft aluminum foil that has undergone annealing and degreasing treatment (manufactured by Toyo Aluminum KK, "8079 material")

[0265] <Compositions for forming thermo-adhesive resin layers>

[0266] A composition for forming a heat-adhesive resin layer is obtained by mixing homopolymer modified with maleic anhydride in proportions of 80% by mass and 20% by mass, respectively, and ethylene / 1-butene copolymer as a polyethylene resin.

[0267] <Resin Composition for Sealing Layer Formation>

[0268] A resin composition for forming a sealing layer is obtained by dry mixing polypropylene resin (A) and polyethylene resin (B) of the types shown in Table 2 or Table 3 in such proportions as shown in Table 2 or Table 3.

[0269] It should be noted that the materials, melting points, and Mw / Mn of the polypropylene resins (A) and polyethylene resins (B) shown in Table 2 or Table 3 are as shown in Table 1 below. In Tables 1 to 3 below, "PP" stands for "polypropylene", "PE" stands for "polyethylene", and LLDPE stands for "linear low-density polyethylene".

[0270]

[0271] The melting peak temperature of polypropylene resin (A) was determined by differential scanning calorimetry according to JIS K 7121-1987. Furthermore, the Mw and Mn of polyethylene resin (B) were determined by gel permeation chromatography at a measurement temperature of 145°C, converted to polystyrene, according to JIS K 7252-1 and 4:2016.

[0272] [Production of Encapsulation Materials]

[0273] (Example 1)

[0274] First, apply the first and second anti-corrosion treatment layers to both sides of the barrier layer according to the following steps.

[0275] That is, the dry coating amount is made to 70 mg / m² by microgravure coating. 2 (CL-1) was coated onto both sides of the barrier layer and baked at 200°C in a drying unit. Then, microgravure coating was used to achieve a dry coating weight of 20 mg / m². 2 The (CL-2) coating is applied to the layer formed by (CL-1) on both sides. In this way, the first and second anti-corrosion treatment layers are formed on both sides of the barrier layer.

[0276] Next, the substrate layer is bonded to the first anti-corrosion treatment layer using a dry lamination method with an adhesive for forming the first adhesive layer.

[0277] That is, an adhesive for forming a first adhesive layer is applied to the surface of the barrier layer on the side of the first anti-corrosion treatment layer, such that the cured thickness is 4 μm. After being heated and dried at 80°C for 1 minute, it is laminated with the substrate layer and aged at 80°C for 120 hours. In this way, a first laminate (substrate layer / first adhesive layer / first anti-corrosion treatment layer / barrier layer / second anti-corrosion treatment layer) is obtained.

[0278] Finally, a thermally adhesive resin layer and a sealing layer are sequentially laminated on the second anti-corrosion treatment layer.

[0279] That is, the first laminate described above is placed in the winding section of an extrusion laminator. Then, by co-extruding a composition for forming a thermosetting resin layer and a resin composition for forming a sealing layer from a T-die under processing conditions of 270°C and 80 m / min, a thermosetting resin layer and a sealing layer are sequentially laminated on the second anti-corrosion treatment layer. Furthermore, the thicknesses of the thermosetting resin layer and the sealing layer are 20 μm and 60 μm, respectively, and the hydrogen sulfide permeability coefficient of the laminate composed of the thermosetting resin layer and the sealing layer is the value shown in Table 2.

[0280] Thus, the encapsulation material for the energy storage device (substrate layer / first adhesive layer / first anti-corrosion treatment layer / barrier layer / second anti-corrosion treatment layer / thermally adhesive resin layer / sealing layer) involved in Example 1 is obtained.

[0281] (Examples 2-9 and Comparative Examples 1-2)

[0282] As a resin composition for forming a sealing layer, a resin composition for forming a sealing layer was obtained by dry mixing polypropylene resin (A) and polyethylene resin (B) as shown in Table 2 with the contents shown in Table 2, and the hydrogen sulfide permeability coefficient of the laminate composed of the thermally adhesive resin layer and the sealing layer was made to the value shown in Table 2. Otherwise, the encapsulation materials for the energy storage device involved in Examples 2 to 9 and Comparative Examples 1 to 2 were obtained in the same manner as in Example 1.

[0283] (Examples 10, 11 and Comparative Example 3)

[0284] The first laminate (substrate layer / first adhesive layer / first anti-corrosion treatment layer / barrier layer / second anti-corrosion treatment layer) was obtained in the same manner as in Example 1.

[0285] Next, using a dry lamination method and an adhesive for forming a second adhesive layer, a sealing layer with a thickness of 80 μm was bonded onto the second anti-corrosion treatment layer of the first laminate, and then aged at 40°C for 96 hours. Thus, the encapsulation materials for the energy storage device described in Examples 10, 11, and Comparative Example 3 were obtained.

[0286] At this time, the sealing layer is prepared in advance using a T-mold method by dry-mixing a resin composition for forming the sealing layer, which is obtained by dry-mixing polypropylene resin (A) and polyethylene resin (B) as shown in Table 3, respectively, at the contents shown in Table 2. Furthermore, the sealing layer is bonded to the first laminate by applying a second adhesive layer forming adhesive to the second anti-corrosion treatment layer to achieve a thickness of 3 μm after heating, heating at 100°C for 1 minute to form the second adhesive layer, and then laminating the second adhesive layer and the sealing layer. Additionally, the hydrogen sulfide permeability coefficient of the sealing layer is the value shown in Table 3.

[0287] [Determination of hydrogen sulfide permeability coefficient]

[0288] (1) Hydrogen sulfide permeability coefficient of the laminate of thermally adhesive resin layer and sealing layer

[0289] A laminate of a heat-adhesive resin layer and a sealing layer was obtained by co-extruding a heat-adhesive resin layer composition and a sealing layer composition from a T-die under processing conditions of 270°C and 80 m / min. The thicknesses of the heat-adhesive resin layer and the sealing layer were 20 μm and 60 μm, respectively. Then, the hydrogen sulfide permeability coefficient of the laminate was measured according to the method for measuring the hydrogen sulfide permeability coefficient of the laminate.

[0290] (2) Hydrogen sulfide permeability coefficient of the laminated sealing layer

[0291] A sealing layer was obtained by extruding a resin composition for forming the sealing layer from a T-die under processing conditions of 270°C and 80 m / min. The thickness of the sealing layer was 80 μm. Then, the hydrogen sulfide permeability coefficient of the sealing layer was measured using the same method as that used for measuring the hydrogen sulfide permeability coefficient of the laminate described above.

[0292] [Evaluation of Insulation Performance]

[0293] The insulation properties of the encapsulation materials in the embodiments and comparative examples were evaluated.

[0294] (1) Sample preparation

[0295] First, a rectangular piece with a length of 50 mm and a width of 30 mm is cut from the packaging material obtained in the examples and comparative examples.

[0296] Next, using a tensile testing machine (manufactured by Shimadzu Corporation), the above-mentioned sheet was stretched along its length at a speed of 5 mm / min until the displacement reached 10%. The sheet obtained through stretching was used as the test sample.

[0297] (2) Insulation evaluation test

[0298] The substrate layer and a portion of the first adhesive layer of the test sample obtained as described above were sanded off with sandpaper to expose the aluminum foil that served as a barrier layer.

[0299] Next, on a flat surface, after arranging the test sample with the substrate layer facing the flat side and the sealing layer facing the opposite side of the flat surface, tap water is dropped into the center of the surface of the sealing layer of the test sample, and a 95g weight is placed in the center of the droplet.

[0300] Next, the sample was clamped with alligator clips, ensuring it was in contact with the barrier layer but not with the weights or droplets on the laminate. Then, the weights were connected to the negative terminal of the power supply, and the alligator clips were connected to the positive terminal. Voltages of 4kV, 5kV, and 6kV were applied, and the current values ​​were measured. The insulation performance was then evaluated based on the applied voltages, the measured current values, and the evaluation criteria described below. This completed the evaluation of the insulation performance after tensile testing.

[0301] In addition, except that the tensile testing was not performed using a tensile testing machine, the test samples were prepared in the same manner as described above, and the insulation properties (insulation properties before tensile testing) of the test samples were evaluated. The results are shown in Table 4.

[0302] (Evaluation criteria for insulation)

[0303] A: The current value is less than 5mA when a 6kV DC voltage is applied.

[0304] B: The current value is above 5mA when a 6kV DC voltage is applied, and the current value is less than 5mA when a 5kV DC voltage is applied.

[0305] C: The current value is above 5mA when a 5kV DC voltage is applied, and the current value is less than 5mA when a 4kV DC voltage is applied.

[0306] D: The current value is above 5mA when a 4kV DC voltage is applied.

[0307]

[0308]

[0309]

[0310] According to the results shown in Table 4, the evaluation of insulation after stretching was “A” to “C” in Examples 1 to 11, relative to “A” before stretching, and “D” in Comparative Examples 1 to 3.

[0311] In summary, it has been confirmed that the encapsulation material for the energy storage device according to this disclosure can suppress the reduction in insulation caused by stretching.

[0312] It should be noted that the summary of this disclosure is as follows.

[0313] [1] An encapsulation material for an energy storage device comprises, in sequence, a substrate layer, a barrier layer, an adhesive layer, and a sealing layer.

[0314] The adhesive layer is a heat-adhesive resin layer or an adhesive layer.

[0315] When the adhesive layer is the thermally adhesive resin layer, the hydrogen sulfide permeability coefficient of the laminate of the thermally adhesive resin layer and the sealing layer is 1.1 × 10⁻⁶. -9 cc·mm / cm 2 ·sec·cmHg or higher and less than 1.0×10 - 8 cc·mm / cm 2 ·sec·cmHg,

[0316] When the adhesive layer is the adhesive layer, the hydrogen sulfide permeability coefficient of the sealing layer is 1.1 × 10⁻⁶. -9 cc·mm / cm 2 ·sec·cmHg or higher and less than 1.0×10 -8 cc·mm / cm 2 ·sec·cmHg.

[0317] [2] According to the encapsulation material for the energy storage device described in [1], wherein the sealing layer contains a polypropylene resin comprising at least one of homopolymer polypropylene and block polypropylene, and a polyethylene resin.

[0318] The polyethylene resin has at least one melting peak in the range of 60°C to 105°C.

[0319] [3] The encapsulation material for the energy storage device according to [1] or [2], wherein the ratio (Mw / Mn) of the weight-average molecular weight Mw to the number-average molecular weight Mn of the polyethylene resin is 1.2 or more and 5.0 or less.

[0320] [4] According to the encapsulation material for the energy storage device described in [1], wherein the sealing layer contains a polypropylene resin comprising at least one of homopolymer polypropylene and block polypropylene, and the polypropylene resin in the sealing layer contains 50 to 95% by mass.

[0321] [5] The encapsulation material for an energy storage device according to any one of [1] to [4], wherein the adhesive layer is the thermally adhesive resin layer, the thermally adhesive resin layer contains a polypropylene resin, and the content of the polypropylene resin in the thermally adhesive resin layer is 50 to 95% by mass.

[0322] [6] According to the encapsulation material for the energy storage device described in [1], wherein the sealing layer contains a polypropylene resin comprising homopolymer and a polyethylene resin, wherein the weight-average molecular weight Mw of the polyethylene resin is 1.2 or more and the number-average molecular weight Mn is 5.0 or less.

[0323] [7] The encapsulation material for the energy storage device according to any one of [1] to [6], wherein, when the adhesive layer is the thermally adhesive resin layer, the total thickness of the laminate of the thermally adhesive resin layer and the sealing layer is 25 to 150 μm, and when the adhesive layer is the adhesive layer, the thickness of the sealing layer is 25 to 150 μm.

[0324] [8] The encapsulation material for the energy storage device according to any one of [1] to [7], wherein the energy storage device is an all-solid-state battery.

[0325] [9] An energy storage device comprising:

[0326] Energy storage components, and

[0327] The encapsulation bag that contains the energy storage element

[0328] The encapsulation bag is formed using any one of the encapsulation materials for energy storage devices described in [1] to [8].

[0329]

[10] The energy storage device according to [9] is an all-solid-state battery.

[0330] Industrial applicability

[0331] According to the encapsulation material for energy storage devices disclosed herein, since it can suppress the reduction of insulation caused by stretching, this disclosure is useful for energy storage devices such as all-solid-state batteries.

[0332] Explanation of symbols

[0333] 10, 20… Encapsulation material for energy storage devices, 11… Substrate layer, 13… Barrier layer, 15… Thermally adhesive resin layer (adhesive layer), 16… Sealing layer, 17… Laminate, 12b… Second adhesive layer (adhesive layer), 50… Energy storage device (all-solid-state battery), 52… Energy storage element, 54… Encapsulation bag.

Claims

1. An encapsulation material for an energy storage device, comprising, in sequence, a substrate layer, a barrier layer, an adhesive layer, and a sealing layer, wherein the adhesive layer is a thermally adhesive resin layer or an adhesive layer, and when the adhesive layer is the thermally adhesive resin layer, the hydrogen sulfide permeability coefficient of the laminate of the thermally adhesive resin layer and the sealing layer is 1.1 × 10⁻⁶. -9 cc·mm / cm 2 ·sec·cmHg or higher and less than 1.0×10 -8 cc·mm / cm 2 In the case where the adhesive layer is the adhesive layer, the hydrogen sulfide permeability coefficient of the sealing layer is 1.1 × 10⁻⁶ sec·cmHg. - 9 cc·mm / cm 2 ·sec·cmHg or higher and less than 1.0×10 -8 cc·mm / cm 2 ·sec·cmHg.

2. The encapsulation material for the energy storage device according to claim 1, wherein, The sealing layer contains a polypropylene resin comprising at least one of homopolymer polypropylene and block polypropylene, and a polyethylene resin, wherein the polyethylene resin has at least one melting peak in the range of 60°C to 105°C.

3. The encapsulation material for the energy storage device according to claim 2, wherein, The weight-average molecular weight Mw of the polyethylene resin is greater than 1.2 and less than 5.0 relative to the number-average molecular weight Mn.

4. The encapsulation material for the energy storage device according to claim 1, wherein, The sealing layer contains a polypropylene resin comprising at least one of homopolymer polypropylene and block polypropylene, wherein the polypropylene resin in the sealing layer comprises 50-95% by mass.

5. The encapsulation material for the energy storage device according to claim 4, wherein, The adhesive layer is the thermally adhesive resin layer, which contains polypropylene resin, and the content of the polypropylene resin in the thermally adhesive resin layer is 30-100% by mass.

6. The encapsulation material for the energy storage device according to claim 1, wherein, The sealing layer contains a polypropylene resin comprising homopolymer and a polyethylene resin, wherein the weight-average molecular weight Mw to number-average molecular weight Mn ratio Mw / Mn is 1.2 or more and 5.0 or less.

7. The encapsulation material for an energy storage device according to claim 1, wherein, When the adhesive layer is the thermally adhesive resin layer, the total thickness of the laminate of the thermally adhesive resin layer and the sealing layer is 25 to 150 μm; when the adhesive layer is the adhesive layer, the thickness of the sealing layer is 25 to 150 μm.

8. The encapsulation material for an energy storage device according to any one of claims 1 to 7, wherein, The energy storage device is an all-solid-state battery.

9. An energy storage device comprising: an energy storage element, and a packaging bag for containing the energy storage element, the packaging bag being formed using the packaging material for energy storage devices according to any one of claims 1 to 7.

10. The energy storage device according to claim 9, wherein it is an all-solid-state battery.

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