Energy storage devices

Abstract

To provide a power storage device that is capable of at least one of suppressing the intrusion of moisture into an electrode body and absorbing gas generated from the electrode body.SOLUTION: A power storage device includes an electrode body, an electrode terminal connected to the electrode body, and an exterior body that seals the electrode body. The exterior body is formed of a film-like exterior member, and the exterior body includes a first sealing portion that is joined with the exterior member encasing the electrode body, and the exterior member includes a barrier layer. The power storage device has a resin film for power storage devices that is arranged at least partially inside the barrier layer. The resin film for power storage devices includes at least one of a water absorbing agent and a gas absorbing agent.SELECTED DRAWING: Figure 1B

Description

[Technical Field]

[0001] The present invention relates to an electricity storage device. [Background technology]

[0002] Various types of electricity storage devices have been developed, and in all of them, exterior members are essential components for sealing electrode bodies such as electrodes and electrolytes. Conventionally, metal exterior members have been widely used as exterior members for electricity storage devices.

[0003] Meanwhile, in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., there has been a demand for electricity storage devices to have a variety of shapes as well as to be thinner and lighter in weight. However, the metallic exterior members for electricity storage devices that have been widely used in the past have the drawbacks of being difficult to keep up with the diversification of shapes and also having limitations on how light they can be made.

[0004] Therefore, a film-like laminate in which a base layer / barrier layer / adhesive layer / thermally adhesive resin layer are laminated in this order has been proposed as an exterior material for an electricity storage device that can be easily processed into a variety of shapes and can be made thinner and lighter (see, for example, Patent Document 1).

[0005] In such an exterior member for an electrical storage device, a recess is generally formed by cold forming, and an electrode body such as an electrode and an electrolyte solution is placed in the space formed by the recess, and a heat-sealable resin layer is heat-sealed to obtain an electrical storage device in which the electrode body is housed inside the exterior member for an electrical storage device. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-287971 Summary of the Invention [Problem to be solved by the invention]

[0007] If moisture penetrates into the electrode body, the performance of the electricity storage device will deteriorate, so if the above-mentioned film-like laminate is used as an exterior member, for example, a barrier layer (made of, for example, metal foil) is provided. By providing the barrier layer, it is possible to suppress the penetration of moisture from outside the barrier layer.

[0008] However, when the electrode body is sealed by heat-sealing the heat-sealable resin layer of the exterior member, the end faces of the heat-sealable resin layer are exposed to the outside, and there is a risk of moisture penetrating through the end faces of the heat-sealable resin layer.

[0009] Furthermore, if the heat-sealable resin layer of the exterior member absorbs water before the electrode body is sealed with the exterior member, there is a risk that the moisture in the heat-sealable resin layer will penetrate into the electrode body after the electrode body is sealed.

[0010] Furthermore, when the electricity storage device is an all-solid-state battery, if moisture comes into contact with a solid electrolyte contained in an element constituting the all-solid-state battery, gas such as hydrogen sulfide may be generated depending on the type of solid electrolyte.

[0011] An object of the present invention is to provide an electricity storage device that can achieve at least one of suppressing the intrusion of moisture into the electrode body and absorbing gas generated from the electrode body. [Means for solving the problem]

[0012] An electricity storage device according to a first aspect of the present invention includes an electrode assembly, an electrode terminal connected to the electrode assembly, and an exterior body sealing the electrode assembly. The exterior body is configured with a film-like exterior member, and the exterior body includes a first sealing portion joined with the exterior member encasing the electrode assembly. The exterior member includes a barrier layer. The electricity storage device has a resin film for an electricity storage device arranged at least partially inside the barrier layer. The resin film for an electricity storage device includes at least one of a water absorbing agent and a gas absorbing agent.

[0013] An electricity storage device according to a second aspect of the present invention is the electricity storage device according to the first aspect, wherein the resin film for an electricity storage device is used as a heat-sealable resin layer of the exterior member.

[0014] An electricity storage device according to a third aspect of the present invention is the electricity storage device according to the first or second aspect, wherein the resin film for an electricity storage device is used as an adhesive film for a terminal that joins the exterior member and the electrode terminal.

[0015] An electric storage device according to a fourth aspect of the present invention is the electric storage device according to any one of the first to third aspects, further comprising a lid body to which the electrode terminal is attached and which is arranged to the side of the electrode body, and a portion of the lid body is joined to the exterior member.

[0016] An electricity storage device according to a fifth aspect of the present invention is the electricity storage device according to the fourth aspect, wherein the material constituting the lid includes at least one of a resin material and a metal material.

[0017] An electricity storage device according to a sixth aspect of the present invention is the electricity storage device according to the fourth or fifth aspect, wherein the resin film for an electricity storage device is disposed at least partially between the lid body and the electrode body.

[0018] An electricity storage device according to a seventh aspect of the present invention is the electricity storage device according to any one of the fourth to sixth aspects, wherein the resin film for an electricity storage device is disposed at least partially between the lid and the electrode terminal.

[0019] An electricity storage device according to an eighth aspect of the present invention is the electricity storage device according to any one of the fourth to seventh aspects, wherein the resin film for an electricity storage device is disposed at least partially between the lid and the exterior member.

[0020] An electricity storage device according to a ninth aspect of the present invention is the electricity storage device according to any one of the fourth to eighth aspects, wherein the lid has a hole through which the electrode terminal passes, and the resin film for an electricity storage device is disposed in the hole.

[0021] An electricity storage device according to a tenth aspect of the present invention is the electricity storage device according to any one of the fourth to ninth aspects, wherein the lid body includes a first surface facing the electrode body and a second surface opposite to the first surface, and the resin film for an electricity storage device is bonded to at least a portion of the second surface of the lid body. [Effects of the Invention]

[0022] According to the present invention, it is possible to provide an electricity storage device that can achieve at least one of suppressing the intrusion of moisture into the electrode body and absorbing hydrogen sulfide generated from the electrode body. [Brief explanation of the drawings]

[0023] [Figure 1A] FIG. 1 is a perspective view schematically showing an electricity accumulation device according to a first embodiment. [Figure 1B] 1B is a cross-sectional view showing an example of a layer structure of the exterior member of FIG. 1A. FIG. [Figure 2] FIG. 2 is a plan view schematically illustrating the electricity storage device. [Figure 3] FIG. 2 is a side view schematically illustrating the electricity storage device. [Figure 4] FIG. 4 is a side view showing a state in which a sheath member is wrapped around an electrode body during the manufacture of the electricity storage device according to the first embodiment. [Figure 5] FIG. 10 is a view showing a state in which a sheath member is wrapped around an electrode body, as viewed from below, during the manufacture of the electricity storage device according to the first embodiment. [Figure 6] FIG. 6 is a diagram schematically illustrating a part of a cross section taken along the line VI-VI in FIG. [Figure 7A] 10A and 10B are diagrams illustrating a method for forming a second sealing portion. [Figure 7B] FIG. 6 is a cross-sectional view showing another example taken along line VI-VI in FIG. [Figure 7C] FIG. 6 is a cross-sectional view showing yet another example taken along line VI-VI in FIG. [Figure 7D] FIG. 6 is a cross-sectional view showing yet another example taken along line VI-VI in FIG. [Figure 7E] FIG. 6 is a cross-sectional view showing yet another example taken along line VI-VI in FIG. [Figure 7F] 1 is a cross-sectional view showing an example of a layer structure of a resin film for an electricity storage device included in the electricity storage device of the first embodiment. [Figure 7G] FIG. 4 is a cross-sectional view showing another example of the layer structure of the resin film for an electricity storage device included in the electricity storage device of the first embodiment. [Figure 7H] FIG. 4 is a cross-sectional view showing yet another example of the layer structure of the resin film for an electricity storage device included in the electricity storage device of the first embodiment. [Figure 8] 5 is a flowchart showing a manufacturing procedure for the electricity storage device according to the first embodiment. [Figure 9] FIG. 10 is a plan view schematically showing an electricity storage device according to a second embodiment. [Figure 10] FIG. 2 is a side view schematically illustrating the electricity storage device. [Figure 11] FIG. 2 is a perspective view schematically showing a lid body. [Figure 12] FIG. 10 is a diagram showing a first example in which the lid and the electrode terminal are integrally formed. [Figure 13] FIG. 10 is a diagram showing a second example in which the lid and the electrode terminal are integrally formed. [Figure 14] 10 is a flowchart showing a manufacturing procedure for an electricity storage device according to a second embodiment. [Figure 15] 10 is a flowchart showing another manufacturing procedure for the electricity storage device according to the second embodiment. [Figure 16] FIG. 11 is a side view showing a state in which an exterior member is wrapped around an electrode body in a third embodiment. [Figure 17] FIG. 11 is a view showing a state in which an exterior member is wrapped around an electrode body and a lid body is attached to the exterior member, as viewed from below, in a third embodiment. [Figure 18]10 is a flowchart showing a manufacturing procedure for an electricity storage device according to a third embodiment. [Figure 19] FIG. 10 is a plan view schematically showing an electricity storage device according to a fourth embodiment. [Figure 20] FIG. 10 is a side view schematically showing an electricity accumulation device according to a fourth embodiment. [Figure 21] FIG. 10 is a side view showing a state in which an exterior member is wrapped around an electrode body in a modified example. [Figure 22] FIG. 10 is a perspective view schematically showing an electricity storage device according to a modified example. [Figure 23] FIG. 10 is a perspective view schematically showing a lid body and an electrode terminal attached to the lid body according to a modified example. [Figure 24] 10A to 10C are diagrams illustrating an insertion step in a manufacturing method of an electricity storage device according to a modified example. [Figure 25] FIG. 10 is a perspective view schematically showing a lid body and an electrode terminal attached to the lid body according to a modified example. [Figure 26] FIG. 24 is a perspective view schematically showing an electricity storage device to which the lid of FIG. 23 is attached. [Figure 27] FIG. 10 is a front view schematically showing a cover according to another modified example. [Figure 28] FIG. 10 is a front view schematically showing a cover according to still another modified example. [Figure 29A] FIG. 10 is a cross-sectional view showing an example of the arrangement of a resin film for an electricity storage device in an electricity storage device according to a second embodiment. [Figure 29B] 29B is a cross-sectional view showing another example of the arrangement of the resin film for an electricity storage device in the electricity storage device of FIG. 29A. [Figure 29C] FIG. 29B is a cross-sectional view showing yet another example of the arrangement of the resin film for an electricity storage device in the electricity storage device of FIG. 29A. [Figure 30] FIG. 10 is a plan view schematically showing an electricity storage device according to another modified example. [Figure 31] FIG. 10 is a side view showing a state in which an exterior member is wrapped around an electrode body during the manufacture of an electricity storage device according to another modified example. [Figure 32] FIG. 32 is an enlarged view of the X portion of FIG. 31. [Figure 33]FIG. 10 is a cross-sectional view of an electricity storage device according to a modified example. [Figure 34] FIG. 10 is a cross-sectional view of an electricity storage device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their description will not be repeated. In the present embodiment, a numerical range indicated by "to" means "greater than or equal to" or "less than or equal to." For example, the notation 2 to 15 mm means 2 mm or more and 15 mm or less. In the numerical ranges described in stages in this embodiment, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, separately described upper and lower limits, upper and lower limits, or lower and lower limits may each be combined to form a numerical range.

[0025] [1. First embodiment] <1-1. Configuration of the power storage device> Fig. 1A is a perspective view that schematically shows an electricity storage device 10 according to a first embodiment. Fig. 2 is a plan view that schematically shows the electricity storage device 10. Fig. 3 is a side view that schematically shows the electricity storage device 10. In each of Figs. 2 and 3, the direction of arrows UD indicates the thickness direction of the electricity storage device 10, and the direction of arrows LR indicates the width direction of the electricity storage device 10. Furthermore, the direction of arrows FB indicates the depth direction of the electricity storage device 10. The directions indicated by the arrows UDLRFB are common to the subsequent figures.

[0026] 1A, 1B, 2, and 3, the electricity storage device 10 includes an electrode assembly 200, an exterior body 100, and a plurality (two) of electrode terminals 300. The electrode assembly 200 includes electrodes (positive and negative electrodes) and separators that constitute an electricity storage member such as a lithium ion battery, a capacitor, or an all-solid-state battery. The shape of the electrode assembly 200 is a substantially rectangular parallelepiped. Note that the term "substantially rectangular parallelepiped" refers not only to a perfect rectangular parallelepiped, but also to a solid that can be regarded as a rectangular parallelepiped by, for example, modifying the shape of a portion of its outer surface.

[0027] The electrode terminal 300 is a metal terminal used for inputting and outputting power to and from the electrode body 200. One end of the electrode terminal 300 is electrically connected to an electrode (positive electrode or negative electrode) included in the electrode body 200, and the other end protrudes outward from the edge of the exterior body 100.

[0028] The metal material constituting the electrode terminal 300 is, for example, aluminum, nickel, copper, etc. For example, when the electrode body 200 is a lithium ion battery, the electrode terminal 300 connected to the positive electrode is usually made of aluminum, etc., and the electrode terminal 300 connected to the negative electrode is usually made of copper, nickel, etc.

[0029] The exterior body 100 is made of a film-like exterior member 101 (see FIG. 4, etc.) and seals the electrode body 200. In the electricity storage device 10, the exterior body 100 is formed by wrapping the exterior member 101 around the electrode body 200 and sealing the open portion.

[0030] For example, there is a method of forming a storage portion (recess) in the exterior member 101 through cold forming to store the electrode assembly 200. However, it is not necessarily easy to form a deep storage portion using such a method. If an attempt is made to form a deep storage portion (recess) through cold forming (for example, a forming depth of 15 mm), pinholes and cracks are likely to occur in the exterior member, leading to a decrease in battery performance. On the other hand, the exterior member 100 seals the electrode assembly 200 by wrapping the exterior member 101 around the electrode assembly 200, so the electrode assembly 200 can be easily sealed regardless of the thickness of the electrode assembly 200. Note that in order to reduce the dead space between the electrode assembly 200 and the exterior member 101 so as to improve the volumetric energy density of the electricity storage device 10, it is preferable that the exterior member 101 be wrapped so as to come into contact with the outer surface of the electrode assembly 200. Furthermore, in an all-solid-state battery, it is necessary to apply a high pressure uniformly from the outer surface of the battery to exert battery performance, and therefore it is necessary to eliminate the space between the electrode body 200 and the exterior member 101. Therefore, it is preferable that the exterior member 101 is wrapped around the electrode body 200 so as to contact the outer surface of the electrode body 200.

[0031] 1B is a cross-sectional view showing an example of the layer structure of the exterior member 101. The exterior member 101 is, for example, a laminate 101Z (laminate film) having a base layer 101A, a barrier layer 101B, and a heat-sealable resin layer 101C in this order. Note that the exterior member 101 does not need to include all of these layers, and for example, the base layer 101A may not be included. Note that the exterior member 101 is preferably heat-sealable.

[0032] The base material layer 101A included in the exterior member 101 is a layer that imparts heat resistance to the exterior member 101 and prevents pinholes from occurring during processing or distribution. The base material layer 101A is configured to include, for example, at least one layer of a stretched polyester resin layer and a stretched polyamide resin layer. For example, when the base material layer 101A includes at least one layer of a stretched polyester resin layer and a stretched polyamide resin layer, the barrier layer 101B is protected during processing of the exterior member 101, and breakage of the exterior member 101 can be prevented. Furthermore, from the viewpoint of increasing the tensile elongation of the exterior member 101, the stretched polyester resin layer is preferably a biaxially stretched polyester resin layer, and the stretched polyamide resin layer is preferably a biaxially stretched polyamide resin layer. Furthermore, from the viewpoint of excellent puncture strength or impact strength, the stretched polyester resin layer is more preferably a biaxially stretched polyethylene terephthalate (PET) film, and the stretched polyamide resin layer is more preferably a biaxially stretched nylon (ONy) film. The base layer 101A may be configured to include both a stretched polyester resin layer and a stretched polyamide resin layer. From the viewpoint of film strength, the thickness of the base layer 101A is preferably, for example, 5 to 300 μm, and more preferably 20 to 150 μm.

[0033] Furthermore, the barrier layer 101B included in the packaging member 101 is made of, for example, a metal foil from the viewpoints of processability such as moisture resistance and ductility, and cost. Specific examples of the metal foil that can be used include aluminum, steel plate, and stainless steel. Furthermore, the metal foil preferably contains iron from the viewpoints of packaging suitability and pinhole resistance when packaging the electrode body 200. The iron content in the metal foil is preferably 0.5 to 5.0 mass %, and more preferably 0.7 to 2.0 mass %. By ensuring that the iron content is 0.5 mass % or more, packaging suitability, excellent pinhole resistance, and ductility of the packaging member 101 can be obtained. Furthermore, by ensuring that the iron content is 5.0 mass % or less, excellent flexibility of the packaging member 101 can be obtained.

[0034] From the viewpoints of barrier properties, pinhole resistance, and packaging suitability, the thickness of the barrier layer 101B is preferably, for example, 15 to 100 μm, and more preferably 30 to 80 μm. When the thickness of the barrier layer 101B is 15 μm or more, the exterior member 101 is less likely to break even when stress is applied during packaging processing. When the thickness of the barrier layer 101B is 100 μm or less, an increase in the mass of the exterior member 101 can be reduced, and a decrease in the weight energy density of the electricity storage device 10 can be suppressed.

[0035] Furthermore, when the barrier layer 101B is a metal foil, it is preferable that a corrosion-resistant coating be provided on at least the surface opposite the base layer 101A to prevent dissolution and corrosion. The barrier layer 101B may be provided with a corrosion-resistant coating on both sides. Here, the corrosion-resistant coating refers to a thin film that is provided with corrosion resistance (e.g., acid resistance, alkali resistance, etc.) by performing, for example, a hydrothermal conversion treatment such as boehmite treatment, a chemical conversion treatment, an anodizing treatment, a plating treatment using nickel or chromium, or a corrosion prevention treatment such as applying a coating agent on the surface of the barrier layer 101B. Specifically, the corrosion-resistant coating refers to a coating that improves the acid resistance of the barrier layer 101B (acid-resistant coating), a coating that improves the alkali resistance of the barrier layer 101B (alkali-resistant coating), or the like. The corrosion-resistant coating may be formed by one type of treatment or a combination of two or more types. Furthermore, the barrier layer 101B may be formed not only as a single layer but also as a multi-layer. Furthermore, among these treatments, hydrothermal conversion treatment and anodizing treatment are treatments in which the surface of the metal foil is dissolved using a treatment agent to form a metal compound with excellent corrosion resistance. Note that these treatments may also be included in the definition of chemical conversion treatment. Furthermore, if the barrier layer 101B has a corrosion-resistant coating, the corrosion-resistant coating is also included in the barrier layer 101B.

[0036] The corrosion-resistant coating prevents delamination between the barrier layer 101B (e.g., aluminum alloy foil) and the base layer 101A during molding of the exterior member 101, and prevents dissolution and corrosion of the surface of the barrier layer 101B due to hydrogen fluoride produced by a reaction between an electrolyte and water, particularly when the barrier layer 101B is an aluminum alloy foil, preventing dissolution and corrosion of aluminum oxide present on the surface of the barrier layer 101B. The corrosion-resistant coating also improves the adhesiveness (wettability) of the surface of the barrier layer 101B, thereby preventing delamination between the base layer 101A and the barrier layer 101B during heat sealing, and between the base layer 101A and the barrier layer 101B during molding of the exterior member 101.

[0037] The thermally adhesive resin layer 101C included in the exterior member 101 is a layer that provides heat-sealing properties to the exterior member 101. Examples of the thermally adhesive resin layer 101C include a resin film made of a polyolefin resin or an acid-modified polyolefin resin obtained by graft-modifying a polyolefin resin with an acid such as maleic anhydride. From the viewpoints of sealing properties and strength, the thickness of the thermally adhesive resin layer 101C is preferably, for example, 20 to 300 μm, and more preferably 40 to 150 μm.

[0038] If the heat-sealable resin layer 101C is too hard, it may slip at the contact points with the device when the roll material or the exterior member 101 is used to make the exterior body 100, preventing it from being transported properly. Furthermore, if the exterior member 101 is scratched by this friction, the heat-sealable resin layer 101C will be damaged. Damage to the heat-sealable resin layer 101C may result in a decrease in heat seal strength, so it is preferable that the heat-sealable resin layer have a moderately slippery property. For this reason, when a non-slip or non-slip material is used as the material constituting the heat-sealable resin layer 101C, it is preferable to add a lubricant from the viewpoint of transportability.

[0039] Furthermore, from the viewpoint of contamination resistance and processability, the thermally adhesive resin layer 101C preferably has a tensile modulus of elasticity measured in accordance with JIS K7161: 2014 in the range of 500 MPa to 1000 MPa. A more preferred range for the tensile modulus of elasticity of the thermally adhesive resin layer 101C is 500 MPa to 800 MPa, an even more preferred range is 500 MPa to 750 MPa, an even more preferred range is 500 MPa to 700 MPa, and an even more preferred range is 510 MPa to 700 MPa.

[0040] Having the thermally adhesive resin layer 101C have a tensile modulus of 500 MPa or more effectively prevents contamination of the device during molding and transportation of the exterior body 100. That is, having the thermally adhesive resin layer 101C have a tensile modulus of 500 MPa or more makes it difficult for the lubricant located on the surface of the thermally adhesive resin layer 101C to be scraped off by the device, etc., and therefore the lubricant located on the surface portion of the thermally adhesive resin layer 101C is unlikely to transfer to the device, etc., effectively preventing contamination of the device, etc. Furthermore, having the thermally adhesive resin layer 101C have a tensile modulus of 1000 MPa or less ensures high sealing strength by heat fusion. That is, having the thermally adhesive resin layer 101C have a tensile modulus of 1000 MPa or less ensures that the thermally adhesive resin layer 101C is unlikely to become brittle, and therefore provides high sealing strength by heat fusion. If the tensile modulus of the heat-sealable resin layer 101C exceeds 1000 MPa, the heat-sealable resin layer 101C becomes brittle and easily peels off from the barrier layer 101B laminated thereon via an adhesive layer, resulting in reduced seal strength. Furthermore, stretching at the folded portion during molding of the exterior body 100 can cause whitening or cracking at the stretched portion, potentially resulting in reduced battery performance. Furthermore, if the tensile modulus of the heat-sealable resin layer 101C exceeds 1000 MPa, extrudability decreases, resulting in reduced productivity. Therefore, in the exterior member 101 of the power storage device 10 of this embodiment, by setting the tensile modulus of the heat-sealable resin layer 101C to a range of 500 to 1000 MPa, the effects of preventing contamination of the device and improving the seal strength due to heat fusion are favorably exhibited. The tensile modulus of the heat-sealable resin layer 101C can be adjusted by adjusting the molecular weight, melt mass-flow rate (MFR), etc., of the resin constituting the heat-sealable resin layer 101C.

[0041] Furthermore, when the work of butting together the sealed portions for pillow sealing and the work of folding are called "processing" when manufacturing the exterior body 100, the same problems as described above occur during this processing. Since the exterior member 101 is particularly susceptible to damage during processing, solving the above problems is important. Setting the tensile modulus of elasticity of the heat-fusible resin layer 101C to be in the range of 500 MPa or more and 1000 MPa or less allows for good processing.

[0042] The exterior member 101 preferably has one or more layers having a buffer function (hereinafter referred to as "buffer layer") outside the thermally adhesive resin layer 101C (upper side in FIG. 1B), more preferably outside the barrier layer 101B. The buffer layer may be laminated on the outside of the base material layer 101A, or the base material layer 101A may also function as a buffer layer. When the exterior member 101 has multiple buffer layers, the multiple buffer layers may be adjacent to each other, or may be laminated with the base material layer 101A, the barrier layer 101B, or the like interposed therebetween.

[0043] The material constituting the buffer layer can be arbitrarily selected from materials having cushioning properties. Examples of the material having cushioning properties include rubber, nonwoven fabric, and foam sheet. Examples of rubber include natural rubber, fluororubber, and silicone rubber. The rubber hardness is preferably about 20 to 90. The material constituting the nonwoven fabric is preferably a material having excellent heat resistance. When the buffer layer is made of nonwoven fabric, the lower limit of the thickness of the buffer layer is preferably 100 μm, more preferably 200 μm, and even more preferably 1000 μm. When the buffer layer is made of nonwoven fabric, the upper limit of the thickness of the buffer layer is preferably 5000 μm, and even more preferably 3000 μm. The thickness of the buffer layer is preferably in the range of 100 μm to 5000 μm, 100 μm to 3000 μm, 200 μm to 5000 μm, 200 μm to 3000 μm, 1000 μm to 5000 μm, or 1000 μm to 3000 μm, and most preferably in the range of 1000 μm to 3000 μm.

[0044] When the buffer layer is made of rubber, the lower limit of the buffer layer thickness is preferably 0.5 mm. When the buffer layer is made of rubber, the upper limit of the buffer layer thickness is preferably 10 mm, more preferably 5 mm, and even more preferably 2 mm. When the buffer layer is made of rubber, the preferred range of the buffer layer thickness is 0.5 mm to 10 mm, 0.5 mm to 5 mm, or 0.5 mm to 2 mm.

[0045] When the exterior member 101 has a buffer layer, the buffer layer functions as a cushion, thereby preventing the exterior member 101 from being damaged by an impact when the energy storage device 10 is dropped or by handling during the manufacture of the energy storage device 10.

[0046] Because the exterior housing 100 of this embodiment can be formed with a deep housing portion, the weight of the electrode assembly 200 increases, making the exterior housing 100 more susceptible to attacks from impacts and the like. For this reason, in this embodiment, when the thickness of the exterior member 101 is 195 μm or less and the thickness of the barrier layer 101B is in the range of 20 to 85 μm, the puncture strength when pierced from the base layer 101A side of the exterior member 101, as measured by a method conforming to the provisions of JIS Z1707:1997, is preferably 30 N or more. Preferred ranges for the puncture strength include, for example, approximately 30 to 45 N, approximately 30 to 40 N, approximately 35 to 45 N, and approximately 35 to 40 N. The puncture strength of the exterior member 101 is measured as follows.

[0047] The puncture strength of the exterior member 101 from the base layer 101A side is measured according to the method specified in JIS Z1707:1997. Specifically, in a measurement environment of 23±2°C and 50±5% relative humidity, a test specimen is fixed using a 115mm diameter table with a 15mm diameter opening in the center and a pressure plate. A semicircular needle with a 1.0mm diameter and a 0.5mm tip radius is pierced at a rate of 50±5mm per minute, and the maximum stress until the needle penetrates is measured. Five test specimens are measured, and the average value is calculated. If there are not enough test specimens to measure five, the remaining number is measured and the average value is calculated. The puncture strength can be measured using Imada's ZP-500N force gauge and MX2-500N measurement stand.

[0048] In the electricity storage device 10 of this embodiment, the weight of the electrode assembly 200 increases, which tends to cause friction between the electricity storage devices 10 themselves, friction between the electricity storage device 10 and peripheral members, and friction during transportation of the electricity storage device 10. For this reason, in this embodiment, it is preferable that the ink on the surface of the exterior member 101 facing the base material layer 101A of the exterior member 101 not only has good fixability (good printing characteristics) but also that the fixed ink is not easily erased. From this perspective, it is preferable that the exterior member 101 of this embodiment has a contact angle of 80° or less on the surface facing the base material layer 101A. That is, when the base material layer 101A constitutes the outermost surface of the exterior member 101, the contact angle of the surface of the base material layer 101A is 80° or less. Furthermore, when a coating layer is provided on the outer side of the base material layer 101A, the contact angle of the surface of the coating layer is 80° or less. In this embodiment, the contact angle of the surface of the exterior member 101 facing the base material layer 101A is 80° or less, which makes the surface on the base material layer 101A side less likely to repel ink, resulting in excellent printing properties and less likely to cause the fixed ink to disappear. In particular, when ink is printed by pad printing on an exterior member 101 in which a lubricant is present on the surface on the base material layer 101A side to enhance formability, the ink may be repelled by the surface on the base material layer 101A side, resulting in poor printing. However, even in such cases, the exterior member 101 of the electricity storage device 10 of this embodiment has a contact angle of 80° or less on the surface on the base material layer 101A side, which makes the exterior member 101 less likely to repel ink and particularly suitable as an exterior member 101 on which printing or the like is formed on the surface of the base material layer 101A by pad printing.

[0049] In this embodiment, from the viewpoint of improving printability and making it difficult for the fixed ink to disappear, the contact angle on the surface on the substrate layer 101A side is more preferably 79° or less, and even more preferably 72° or less. The contact angle on the surface on the substrate layer 101A side can be determined by measuring the contact angle of the interface between the substrate and the water droplet 5 seconds after the water droplet is applied using an LSE-A210 manufactured by NIC Corporation.

[0050] In this embodiment, the contact angle of the surface on the substrate layer 101A side can be suitably reduced to 80° or less by, for example, subjecting the surface on the substrate layer 101A side to corona treatment. Corona treatment can be performed by irradiating the surface on the substrate layer 101A side with corona discharge using a commercially available corona surface treatment device. The corona treatment conditions are, for example, treating the surface on the substrate layer 101A side at an irradiation output of 1 kW or more and a speed of 10 MT / min, thereby reducing the contact angle of the surface on the substrate layer 101A side to 80° or less.

[0051] Furthermore, when printing ink on the surface of the exterior member 101, a corona treatment is performed, followed by a step of printing ink on at least a portion of the surface of the base material layer 101A. The printing method is not particularly limited, but inkjet printing or pad printing is preferred when printing on the molded exterior member 101. The exterior member 101 of the electricity storage device 10 of this embodiment has a contact angle of 80° or less on the surface facing the base material layer 101A. Therefore, ink can be suitably printed even by pad printing, in which ink is easily repelled by the base material layer 101A, which has a lubricant on its surface. Therefore, it is possible to suitably print, for example, barcodes, patterns, letters, and the like, on at least a portion of the surface of the base material layer 101A.

[0052] FIG. 4 is a side view showing a state in which a packaging member 101 is wrapped around an electrode assembly 200 during the manufacturing process of the electricity storage device 10. As shown in FIG. 4, the packaging member 101 is wrapped around the electrode assembly 200. In this case, the outermost layer of the electrode assembly 200 does not necessarily have to be an electrode and may be, for example, a protective tape or a separator. With the packaging member 101 wrapped around the electrode assembly 200, the facing surfaces (thermal adhesive resin layers) of the packaging member 101 are heat-sealed to form a first sealing portion 110. Note that the first sealing portion 110 may be formed by joining the innermost layer and the outermost layer of the packaging member 101. In this case, the innermost layer and the outermost layer of the packaging member 101 are preferably thermal adhesive resin layers 101C.

[0053] The root portion of the first sealing unit 110 is preferably located on a side 135 of the exterior housing 100. In this embodiment, the side 135 is formed at the boundary between the first surface 130 and the second surface 140, which has a smaller area than the first surface 130. That is, in this embodiment, the root portion of the first sealing unit 110 can be said to be formed at the boundary between the first surface 130 and the second surface 140, and not to be located on either the first surface 130 or the second surface 140. The root portion of the first sealing unit 110 may be located at a position other than the side 135. In the energy storage device 10, the first sealing unit 110 is bent toward the second surface 140 around the side 135. In the energy storage device 10, the first sealing unit 110 is in contact with the second surface 140 and covers substantially the entire second surface 140. Note that "substantially the entire second surface 140" means a region occupying 75% or more of the area of ​​the second surface 140.

[0054] That is, in the electricity storage device 10, the first sealing portion 110 is not formed on the first surface 130, which has a large area. The first surface 130 is flatter than when a sealing portion such as the first sealing portion 110 is in contact with the first surface 130. Therefore, even if another electricity storage device 10 is placed on the first surface 130, the other electricity storage device 10 will not tilt. As a result, the electricity storage device 10 can suppress unevenness in the distribution of pressure applied to the lower electricity storage device 10 when multiple electricity storage devices 10 are stacked. In other words, when multiple electricity storage devices 10 are stacked to form a module, the first sealing portion 110 is not disposed on the surface (first surface 130) adjacent to the adjacent electricity storage device 10. Furthermore, such a configuration is preferable from the viewpoint that in all-solid-state batteries, high pressure needs to be applied uniformly from the outer surface of the battery to exhibit battery performance.

[0055] Furthermore, in the power storage device 10, the base portion of the first sealing portion 110 is located on the side 135 of the exterior body 100. Therefore, with the power storage device 10, a wider bonding area can be ensured in the first sealing portion 110 compared to when the base portion of the first sealing portion 110 is located on the second surface 140 (for example, the central portion of the second surface 140 in the direction of the arrow UD). Note that the bonding area of ​​the first sealing portion 110 does not necessarily have to be the entire area of ​​the first sealing portion 110, and may be a part of the first sealing portion 110, such as only the vicinity of the base portion of the first sealing portion 110, for example.

[0056] Furthermore, in the electricity storage device 10, substantially the entire second surface 140 is covered by the first sealing portion 110. That is, in the electricity storage device 10, the length of the first sealing portion 110 in the direction of the arrow UD is longer than in a case where the first sealing portion 110 covers only half or less of the area of ​​the second surface 140 (see FIG. 3 ). Therefore, according to the electricity storage device 10, a wide bonding area can be secured in the first sealing portion 110. Furthermore, since substantially the entire second surface 140 is covered by the first sealing portion 110, the electricity storage device 10 is stable even if the electricity storage device 10 is placed upright so that the second surface 140 is in contact with a mounting surface. That is, the electricity storage device 10 is unlikely to tilt relative to the mounting surface. Therefore, such a configuration is effective, for example, when a plurality of electricity storage devices 10 are arranged horizontally to form a module.

[0057] Fig. 5 is a view showing, from below, a state in which the exterior member 101 is wrapped around the electrode assembly 200 during the manufacture of the electricity storage device 10. As shown in Fig. 5, in the electricity storage device 10, the direction along the side 135 is the TD (Transverse Direction) of the exterior member 101, and the direction perpendicular to the side 135 is the MD (Machine Direction) of the exterior member 101. In other words, the direction along the side 135 is the direction (TD) perpendicular to the flow direction (MD) of the exterior member 101.

[0058] In the electricity storage device 10, the first sealing unit 110 is folded along the side 135, and the direction along the side 135 is perpendicular to the flow direction of the exterior member 101. Therefore, according to the electricity storage device 10, even if a crease is formed in the direction perpendicular to the flow direction of the exterior member 101, the exterior member 101 is unlikely to break, and therefore, it is possible to reduce the possibility that the first sealing unit 110 will break when the first sealing unit 110 is folded.

[0059] The machine direction (MD) of the exterior member 101 corresponds to the rolling direction (RD) of the metal foil (aluminum alloy foil, etc.) of the barrier layer included in the exterior member 101. The TD of the exterior member 101 corresponds to the TD of the metal foil. The rolling direction (RD) of the metal foil can be determined by the rolling marks.

[0060] Furthermore, the sea-island structure can be confirmed by observing multiple cross sections of the heat-fusible resin layer of the exterior member 101 with an electron microscope, and the direction parallel to the cross section in which the average diameter of the islands in the direction perpendicular to the thickness direction of the heat-fusible resin layer (hereinafter also referred to as the "length direction of the heat-fusible resin layer") was the largest can be determined as the MD. When the MD of the exterior member 101 cannot be identified by the rolling marks of the metal foil, the MD can be identified by this method.

[0061] Specifically, the sea-island structure is confirmed by observing electron microscope photographs of a cross section of the heat-sealable resin layer in the longitudinal direction and cross sections at angles of 10 degrees from the direction parallel to the longitudinal cross section, up to a direction perpendicular to the longitudinal cross section (a total of 10 cross sections). Next, for each island on each cross section, the island diameter d is measured as the linear distance connecting both ends in the direction perpendicular to the thickness direction of the heat-sealable resin layer. Next, the average diameter d of the 20 largest islands is calculated for each cross section. The direction parallel to the cross section with the largest average island diameter d is then determined as the MD.

[0062] Fig. 6 is a diagram schematically showing a part of the cross section taken along line VI-VI in Fig. 2. As shown in Fig. 6, second sealing portion 120 seals electrode terminal 300 in a state where package 100 sandwiches electrode terminal 300 therebetween.

[0063] 7A is a diagram illustrating a method for forming the second sealed portion 120. As shown in FIG. 7A, the exterior member 101 is folded, and the surfaces (thermally adhesive resin layers) of the exterior member 101 that face each other are heat-sealed to form the second sealed portion 120. Although not shown in FIG. 7A, an electrode terminal 300 is positioned between the surfaces of the exterior member 101 that face each other. An adhesive film for a terminal 30 (see FIGS. 7B to 7E) that adheres to both metal and resin may be disposed between the electrode terminal 300 and the exterior member 101.

[0064] The adhesive film may be configured as one or more layers of resin film made of, for example, a polyolefin resin or an acid-modified polyolefin resin obtained by graft-modifying a polyolefin resin with an acid such as maleic anhydride. When the adhesive film is configured as two or more layers, it is preferable to place a resin film made of a polyolefin resin on the side that bonds to the exterior member 101. When the adhesive film is configured as two or more layers, it is preferable to place a resin film made of an acid-modified polyolefin resin obtained by graft-modifying a polyolefin resin with an acid such as maleic anhydride on the side that bonds to the electrode terminal 300.

[0065] 6 again, the electrode assembly 200 includes a plurality of electrodes 210 (positive and negative electrodes). Current collectors 215 extending from each electrode 210 are connected to an electrode terminal 300. In the electricity storage device 10, a portion of the electrode terminal 300 that is outside the exterior body 100 is located at a position that is approximately half the thickness of the electricity storage device 10 in the thickness direction of the electricity storage device 10. In other words, the length L2 is approximately half the length L1. Note that "approximately half the thickness of the electricity storage device 10" means 35% to 65% of the thickness of the electricity storage device 10.

[0066] Therefore, according to the energy storage device 10, the difference between the longest and shortest distances between each of the multiple electrodes 210 and the electrode terminal 300 can be made smaller than when, for example, the electrode terminal 300 is located at approximately the same position as the first surface 130 in the thickness direction of the energy storage device 10.

[0067] If moisture penetrates into the electrode body 200, the performance of the electricity storage device 10 will deteriorate, and therefore, for example, if the above-mentioned film-like laminate is used as the exterior member 101, a barrier layer 101B (made of, for example, metal foil) is provided. By providing the barrier layer 101B, it is possible to suppress the penetration of moisture from outside the barrier layer 101B.

[0068] However, when the heat-sealable resin layer 101C of the exterior member 101 is heat-sealed to seal the electrode body 200, the end surface of the heat-sealable resin layer 101C is exposed to the outside, and there is a risk of moisture penetrating through the end surface of the heat-sealable resin layer 101C.

[0069] Furthermore, if the heat-sealable resin layer 101C of the exterior member 101 absorbs water before the electrode body 200 is sealed with the exterior member 101, there is a risk that the moisture in the heat-sealable resin layer 101C will penetrate into the electrode body 200 after the electrode body 200 is sealed.

[0070] Furthermore, when the electricity storage device 10 is an all-solid-state battery, if moisture comes into contact with a solid electrolyte contained in an element that constitutes the all-solid-state battery, gas such as hydrogen sulfide may be generated depending on the type of solid electrolyte.

[0071] The electricity storage device 10 of this embodiment includes a resin film 20 for an electricity storage device (hereinafter referred to as "film 20") to achieve at least one of suppressing the penetration of moisture into the electrode body 200 and absorbing gases such as hydrogen sulfide generated from the electrode body 200. The film 20 contains at least one of a water absorbing agent and a gas absorbing agent. Hereinafter, the case where the film 20 contains at least a water absorbing agent may be referred to as a first embodiment of the film 20. The case where the film 20 contains at least a gas absorbing agent may be referred to as a second embodiment of the film 20.

[0072] In the electricity storage device 10, the location of the film 20 can be selected arbitrarily as long as it is inside the barrier layer 101B of the packaging member 101. In the present embodiment, inside the barrier layer 101B refers to the side opposite the base layer 101A with respect to the barrier layer 101B in the direction in which the layers 101A to 101C of the packaging member 101 are stacked. By arranging the film 20 of the first aspect inside the barrier layer 101B of the packaging member 101, it is possible to prevent moisture from penetrating from the edge of the heat-sealable resin layer 101C of the packaging member 101 and moisture contained in the heat-sealable resin layer 101C of the packaging member 101 from penetrating into the electrode assembly 200. That is, in the electricity storage device 10 including the film 20 of the first aspect, since the film 20 contains a water absorbing agent, the film 20 absorbs and retains moisture that has penetrated from the heat-sealable resin layer 101C of the packaging member 101, thereby preventing moisture from reaching the electrode assembly 200. Furthermore, by arranging the film 20 of the second embodiment inside the barrier layer 101B of the exterior member 101, for example, when the electrode assembly 200 is an all-solid-state battery, it is possible to absorb gases such as hydrogen sulfide generated by contact between a solid electrolyte layer included in an element constituting the all-solid-state battery and water. That is, in the electricity storage device 10 including the film 20 of the second embodiment, the film 20 contains a gas absorbent, and therefore gases such as hydrogen sulfide generated from the electrode assembly 200 are absorbed by the film 20. Therefore, it is possible to prevent the internal pressure of the exterior assembly 100 from increasing excessively. Specific examples of the arrangement of the film 20 in the electricity storage device 10 are described below.

[0073] As shown in FIG. 1B , the film 20 can also be used as the heat-sealable resin layer 101C of the exterior member 101. The film 20 may also be used as an adhesive layer between the barrier layer 101B and the heat-sealable resin layer 101C. The film 20 can also be used as an adhesive film interposed between the heat-sealable resin layers 101C facing each other at a position where the heat-sealable resin layers 101C of the exterior member 101, such as the first sealing portion 110, are heat-sealed to each other. When the film 20 is used as an adhesive film, the film 20 may have a function of peeling off the portion of the heat-sealable resin layer 101C where the film 20 is interposed, thereby releasing the gas to the outside, when the internal pressure of the exterior member 100 increases due to gas generation from the electrode body 200.

[0074] Fig. 7B is another cross-sectional view taken along line VI-VI in Fig. 2. In the example shown in Fig. 7B, the film 20 is disposed between the exterior member 101 and the electrode body 200 so as to cover almost the entire upper and lower surfaces of the electrode body 200. The film 20 and the inner surface of the exterior member 101 (thermally adhesive resin layer 101C) may or may not be bonded to each other.

[0075] Fig. 7C is a cross-sectional view showing yet another example taken along line VI-VI in Fig. 2. In the example shown in Fig. 7C, the film 20 is disposed between the exterior member 101 and the electrode body 200 so as to cover almost the entire side surface of the electrode body 200. The film 20 and the inner surface of the exterior member 101 (thermally adhesive resin layer 101C) may or may not be bonded to each other.

[0076] Fig. 7D is a cross-sectional view showing yet another example taken along line VI-VI in Fig. 2. In the example shown in Fig. 7D, the film 20 is disposed between the exterior member 101 and the electrode body 200 so as to cover substantially the entire electrode body 200. The film 20 and the inner surface of the exterior member 101 (thermally adhesive resin layer 101C) may or may not be bonded to each other.

[0077] Fig. 7E is a cross-sectional view showing yet another example taken along line VI-VI in Fig. 2. In the example shown in Fig. 7E, the electricity storage device 10 has an adhesive film for a terminal 30 that adheres to both metal and resin between the electrode terminal 300 and the exterior member 101. In the example shown in Fig. 7E, a film 20 is used as the adhesive film for a terminal 30.

[0078] Because the end faces of the adhesive film for a terminal 30 are exposed to the outside, there is a risk that moisture may penetrate through the end faces of the adhesive film for a terminal 30. Furthermore, if the adhesive film for a terminal 30 absorbs water before being interposed between the electrode terminal 300 and the exterior member 101, there is a risk that the moisture in the adhesive film for a terminal 30 may penetrate into the electrode body 200 after the adhesive film for a terminal 30 is interposed between the electrode terminal 300 and the exterior member 101.

[0079] By using the film 20 of the first embodiment as the adhesive film for a terminal 30, it is possible to effectively prevent moisture from penetrating from the edge of the adhesive film for a terminal 30 and moisture contained in the adhesive film for a terminal 30 from penetrating into the electrode body 200. That is, in an electricity storage device 10 including the film 20 of the first embodiment, the film 20 contains a water absorbing agent, and therefore the film 20 absorbs and retains moisture that has penetrated through the adhesive film for a terminal 30, thereby preventing moisture from reaching the electrode body 200. Furthermore, by using the film 20 of the second embodiment as the adhesive film for a terminal 30, for example, when the electrode body 200 is an all-solid-state battery, it is possible to effectively absorb gases such as hydrogen sulfide generated by contact between moisture and a solid electrolyte layer contained in an element constituting the all-solid-state battery. That is, in an electricity storage device 10 including the film 20 of the second embodiment, the film 20 contains a gas absorbent, and therefore gases such as hydrogen sulfide generated from the electrode body 200 are absorbed by the film 20. Therefore, gases such as hydrogen sulfide are less likely to be released to the outside.

[0080] <1-2. Specific configuration of resin film for electricity storage device> In the first aspect of the film 20, the moisture to be absorbed is gaseous and / or liquid moisture. Furthermore, as described below, the gas absorbing film according to the first aspect of this embodiment can also absorb sulfur-based gases, if necessary. Examples of sulfur-based gases include hydrogen sulfide, dimethyl sulfide, methyl mercaptan, and sulfur oxides represented by SOx. When absorbed by, for example, a solid electrolyte-type lithium ion battery, the moisture to be absorbed generates various outgases, and the sulfur-based gases are components of these outgases (for example, generated when the power storage device 10 is an all-solid-state battery using a sulfide-based inorganic solid electrolyte or a lithium secondary battery using lithium-sulfur in the positive electrode).

[0081] The film 20 of this embodiment may be composed of a single layer, as shown in Fig. 7F, or may be composed of two or more layers, as shown in Figs. 7G and 7H. Fig. 7G shows a film 20 composed of a laminate in which a first layer 21 and a second layer 22 are stacked. Fig. 7H shows a film 20 composed of a laminate in which a second layer 22, a first layer 21, and a third layer 23 are stacked in this order.

[0082] In the first aspect, when the film 20 is composed of two or more layers, at least one of the two or more layers may contain a water-absorbing agent. In this embodiment, a layer containing a water-absorbing agent may be referred to as a "water-absorbing layer." Specific examples of the layer structure of the film 20 according to the first aspect include a layer structure in FIG. 7G in which the first layer 21 on the exterior member 101 side is a water-absorbing layer and the second layer 22 on the electrode assembly 200 side is a layer that does not contain a water-absorbing agent. Also, examples of the layer structure in FIG. 7H include a layer structure in which the intermediate first layer 21 is a water-absorbing layer and the second layer 22 on the electrode assembly 200 side and the third layer 23 on the exterior member 101 side are layers that do not contain a water-absorbing agent; and a layer structure in which at least one of the first layer 21 and the third layer 23 is a water-absorbing layer and the second layer 22 is a layer that does not contain a water-absorbing agent.

[0083] In the second aspect, when the film 20 is composed of two or more layers, at least one of the two or more layers may contain a gas absorbent. The gas absorbent is, for example, at least one of a sulfur-based gas absorbent, a carbon dioxide absorbent, and an oxygen absorbent. In this embodiment, the second aspect of the film 20 will be described using an example in which the gas absorbent is a sulfur-based gas absorbent. Specific examples of the layer structure of the film 20 according to the second aspect include, for example, a layer structure in FIG. 7G in which the first layer 21 on the exterior member 101 side is a sulfur-based gas absorbing layer and the second layer 22 on the electrode assembly 200 side is a layer that does not contain a sulfur-based gas absorbent; and a layer structure in which the first layer 21 on the exterior member 101 side is a layer that does not contain a sulfur-based gas absorbing layer and the second layer 22 on the electrode assembly 200 side is a layer that contains a sulfur-based gas absorbent. 7H, examples of the laminated structure include a laminated structure in which the first layer 21 located in the middle is a sulfur-based gas absorbing layer, and the second layer 22 on the electrode assembly 200 side and the third layer 23 on the exterior member 101 side are layers that do not contain a sulfur-based gas absorbent; a laminated structure in which at least one of the first layer 21 and the third layer 23 is a sulfur-based gas absorbing layer, and the second layer 22 is a layer that does not contain a sulfur-based gas absorbent; a laminated structure in which the first layer 21 located in the middle is a layer that does not contain a sulfur-based gas absorbing layer, and the second layer 22 on the electrode assembly 200 side and the third layer 23 on the exterior member 101 side are layers that contain a sulfur-based gas absorbent; and a laminated structure in which at least one of the first layer 21 and the third layer 23 is a layer that does not contain a sulfur-based gas absorbing layer, and the second layer 22 is a layer that contains a sulfur-based gas absorbent. Because hydrogen sulfide gas is generated from the electrode assembly 200, it is preferable that the second layer 22 located on the electrode assembly 200 side be a sulfur-based gas absorbing layer.

[0084] In the first embodiment, it is preferable that one or both surfaces of the film 20 have heat-sealing properties. When the film 20 according to the first embodiment is located in the second sealed portion 120 of the exterior member 101, it is preferable to enhance the heat-sealing properties of the film 20. Therefore, for example, when the film 20 is composed of three or more layers, it is preferable that the layers located on the surface (the second layer 22 and the third layer 23 in FIG. 7H ) contain a heat-sealing resin. Furthermore, from the viewpoint of suppressing a decrease in the heat-sealing properties of the layers located on the surface, it is preferable that the layers located on the surface do not contain a water-absorbing agent (particularly an inorganic water-absorbing agent). In the electricity storage device 10, from the viewpoint of more optimally exhibiting the water-absorbing performance of the water-absorbing layer of the film 20, it is preferable that the water-absorbing layer is provided between the layers located on the surface. This is because if the water-absorbing layer is located on the surface, it will absorb moisture from the atmosphere before the electricity storage device 10 is manufactured, and the water-absorbing performance of the water-absorbing layer will likely decrease. Furthermore, in the electricity storage device 10, it is also preferable that the third layer 23 located on the exterior member 101 side is the water-absorbing layer. This is because the third layer 23 is close to the exterior member 101 and therefore easily absorbs moisture that has infiltrated from the exterior member 101 side. In addition, in the electricity storage device 10, it is also preferable that the second layer 22 located on the electrode assembly 200 side is the water absorption layer. This is because the second layer 22 is close to the electrode assembly 200 and therefore easily absorbs moisture contained in the electrode assembly 200.

[0085] In the second embodiment, too, it is preferable that one or both sides of the film 20 have heat-sealing properties. When the film 20 according to the second embodiment is located in the second sealing portion 120 of the exterior member 101, it is preferable to enhance the heat-sealing properties of the film 20. Therefore, for example, when the film 20 is composed of three or more layers, it is preferable that the layers located on the surface (the second layer 22 and the third layer 23 in FIG. 7H) contain a heat-sealing resin. Furthermore, from the viewpoint of preventing a decrease in the heat-sealing properties of the layers located on the surface, it is preferable that the layers located on the surface do not contain a sulfur-based gas absorbent.

[0086] The film 20 according to the first embodiment may further contain a sulfur-based gas absorbent, as described below, in addition to the water-absorbing agent. In this embodiment, a layer containing a sulfur-based gas absorbent may be referred to as a "sulfur-based gas absorbing layer." When a sulfur-based gas absorbent is contained, the sulfur-based gas absorbent may be contained in a water-absorbing layer or in a layer that does not contain a water-absorbing agent. When the film 20 is composed of two or more layers, it is preferable that the sulfur-based gas absorbent be contained in a layer that does not contain a water-absorbing agent, thereby constituting the sulfur-based gas absorbing layer. Concerns arising from the inclusion of multiple types of particles in a single layer include the difficulty in dispersing the particles during film formation, which may result in holes in the film or variations in strength depending on the location of the film 20. Furthermore, if the amount of particles contained in a single layer exceeds a certain level, the film's elongation and strength may decrease, making it more susceptible to tearing at the corners of the battery, etc. If the amounts are small, these concerns are unlikely to arise even if the water-absorbing agent and the sulfur-based gas absorbent are contained in a single layer. However, in order to maintain the water-absorbing effect and the sulfur-based gas absorbing effect for a long period of time, it is preferable that the water-absorbing layer and the sulfur-based gas absorbing layer are separate layers.

[0087] When the film 20 according to the first embodiment is composed of two or more layers, specific examples of the laminate structure of the film 20 include, for example, a laminate structure in which the first layer 21 is a water-absorbing layer and the second layer 22 is a sulfur-based gas-absorbing layer, as shown in FIG. 7G. Also, for example, a laminate structure in which the first layer 21 is a water-absorbing layer and at least one of the second layer 22 and the third layer 23 is a sulfur-based gas-absorbing layer, as shown in FIG. 7H, is included. Also, a laminate structure in which at least one of the first layer 21 and the third layer 23 is a water-absorbing layer and the second layer 22 is a sulfur-based gas-absorbing layer, as shown in FIG. 7H, is included. Because hydrogen sulfide gas is generated from the electrode assembly 200, it is preferable that the second layer 22 located on the electrode assembly 200 side be a sulfur-based gas-absorbing layer. Furthermore, as described above, it is preferable that the water-absorbing layer be provided between layers located on the surface. Therefore, among these, a laminate structure in which the first layer 21 located between the second layer 22 and the third layer 23 is a water-absorbing layer and the second layer 22 located on the electrode assembly 200 side is a sulfur-based gas-absorbing layer is the most preferable.

[0088] Furthermore, the film 20 according to the second embodiment may further contain a water-absorbing agent, as described below, in addition to the sulfur-based gas absorbent. As described above, in this embodiment, a layer containing a water-absorbing agent may be referred to as a "water-absorbing layer." When a water-absorbing agent is contained, the water-absorbing agent may be contained in the sulfur-based gas-absorbing layer or in a layer that does not contain the water-absorbing agent. When the film 20 according to the second embodiment is composed of two or more layers, it is preferable that the water-absorbing agent be contained in a layer that does not contain the sulfur-based gas absorbent, thereby forming the water-absorbing layer. Concerns arising from the inclusion of multiple types of particles in a single layer include the difficulty in dispersing the particles during film formation of the film 20, which may result in holes in the film or variations in strength depending on the location of the film 20. Furthermore, if the amount of particles contained in a single layer exceeds a certain level, the film's elongation and strength may decrease, making it more susceptible to tearing at the corners of the battery, etc. If the amounts are small, these concerns are unlikely to arise even if the water-absorbing agent and the sulfur-based gas absorbent are contained in a single layer. However, in order to maintain the water-absorbing effect and the sulfur-based gas absorbing effect for a long period of time, it is preferable that the water-absorbing layer and the sulfur-based gas absorbing layer are separate layers.

[0089] When the film 20 according to the second embodiment is composed of two or more layers, specific examples of the laminate structure of the film 20 include, for example, a laminate structure in which the first layer 21 is a sulfur-based gas absorbing layer and the second layer 22 is a water-absorbing layer, as shown in FIG. 7G. Also, for example, a laminate structure in which the first layer 21 is a sulfur-based gas absorbing layer and at least one of the second layer 22 and the third layer 23 is a water-absorbing layer, as shown in FIG. 7H, is included. Also, examples of the laminate structure include a laminate structure in which the first layer 21 is a sulfur-based gas absorbing layer and at least one of the second layer 22 and the third layer 23 is a sulfur-based gas absorbing layer and the second layer 22 is a water-absorbing layer. In the electricity storage device 10, from the viewpoint of more optimally exhibiting the water absorption performance of the water absorption layer of the film 20, it is preferable that the water absorption layer be provided between layers located on the surface. This is because if the water absorption layer is located on the surface, it will absorb moisture from the atmosphere before the electricity storage device 10 is manufactured, which will likely reduce the water absorption performance of the water absorption layer. The most preferred laminated structure is one in which the first layer 21 located between the second layer 22 and the third layer 23 is a water absorption layer, which will be described later, and the second layer 22 located on the electrode assembly 200 side is a sulfur-based gas absorption layer. In the electricity storage device 10, it is also preferred that the third layer 23 located on the exterior member 101 side be the water absorption layer. This is because the third layer 23 is close to the exterior member 101 and therefore easily absorbs moisture that has infiltrated from the exterior member 101 side. In the electricity storage device 10, it is also preferred that the second layer 22 located on the electrode assembly 200 side be the water absorption layer. This is because the second layer 22 is close to the electrode assembly 200 and therefore easily absorbs moisture contained in the electrode assembly 200.

[0090] In this embodiment, the resin contained in the film 20 is not particularly limited as long as it does not impair the effects of this embodiment. For example, a thermoplastic resin is preferable, and a heat-sealable resin is more preferable. Specific examples of resins include thermoplastic resins such as polyester, polyolefin, polyamide, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenolic resin, as well as modified versions of these resins. The resin forming the film 20 may also be a copolymer of these resins or a modified version of the copolymer. Furthermore, it may also be a mixture of these resins. Among these, heat-sealable resins such as polyester and polyolefin are preferred.

[0091] Specific examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyesters. Examples of copolymer polyesters include copolymer polyesters whose repeating units are primarily ethylene terephthalate. Specific examples include copolymer polyesters in which ethylene terephthalate is the main repeating unit and is polymerized with ethylene isophthalate (hereinafter abbreviated as polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate), and polyethylene (terephthalate / decanedicarboxylate). These polyesters may be used alone or in combination of two or more. Among these, polybutylene terephthalate is particularly preferred from the viewpoint of improving heat resistance and pressure resistance (for example, preventing a decrease in insulation when sealing the electrode body 200 with the exterior member 101 (due to crushing due to heat sealing)).

[0092] Specific examples of polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. When the polyolefin resin is a copolymer, it may be a block copolymer or a random copolymer. These polyolefin resins may be used alone or in combination of two or more. Among these, polypropylene is particularly preferred because of its excellent thermal adhesiveness.

[0093] The resin contained in film 20 preferably contains a resin having a polyolefin skeleton as a primary component, more preferably a polyolefin as a primary component, and even more preferably polypropylene as a primary component. Here, "primary component" refers to a resin component whose content of the resin components contained in film 20 is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more. For example, "the resin contained in film 20 contains polypropylene as a primary component" means that the polypropylene content of the resin components contained in film 20 is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0094] The resin contained in film 20 preferably contains polyester as a primary component. Here, "primary component" means that the resin component contained in film 20 contains a resin component whose content is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more of the resin component. For example, "the resin contained in film 20 contains polyester as a primary component" means that the resin component contained in film 20 contains polyester whose content is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more of the polyester.

[0095] When producing the film 20 of this embodiment, a pre-formed resin film may be used as the film 20. Alternatively, the resin forming the film 20 may be formed into a film by extrusion molding, coating, or the like, to form a resin film.

[0096] In this embodiment, the resin contained in the film 20 may include an elastomer. The elastomer serves to ensure the durability of the film 20 in high-temperature environments while increasing its flexibility. Preferred elastomers include at least one thermoplastic elastomer selected from polyesters, polyamides, polyurethanes, polyolefins, polystyrenes, and polyethers, or thermoplastic elastomer copolymers thereof. The elastomer content in the film 20 is not particularly limited as long as it ensures the durability of the film 20 in high-temperature environments while increasing its flexibility. For example, the content is about 0.1% by mass or more, preferably about 0.5% by mass or more, more preferably about 1.0% by mass or more, and even more preferably about 3.0% by mass or more. The content is, for example, about 10.0% by mass or less, about 8.0% by mass or less, or about 5.0% by mass or less. Preferred ranges for the content include about 0.1 to 10.0 mass%, about 0.1 to 8.0 mass%, about 0.1 to 5.0 mass%, about 0.5 to 10.0 mass%, about 0.5 to 8.0 mass%, about 0.5 to 5.0 mass%, about 1.0 to 10.0 mass%, about 1.0 to 8.0 mass%, about 1.0 to 5.0 mass%, about 3.0 to 10.0 mass%, about 3.0 to 8.0 mass%, and about 3.0 to 5.0 mass%, etc.

[0097] The content of the resin contained in the film 20 according to the first embodiment is, for example, 99.9% by mass or more, preferably 99.5% by mass or more, and more preferably 99.0% by mass or more.

[0098] The content of the resin contained in the film 20 according to the second embodiment is, for example, 50% by mass or more, preferably 55% by mass or more, and more preferably 60% by mass or more.

[0099] The water-absorbing agent contained in the film 20 according to the first embodiment is not particularly limited as long as it exhibits water absorption when dispersed in a resin film. For example, inorganic water-absorbing agents can be suitably used from the viewpoint of temporal stability in the electricity storage device 10. Specific examples of preferred inorganic water-absorbing agents include calcium oxide, anhydrous magnesium sulfate, magnesium oxide, calcium chloride, zeolite, aluminum oxide, silica gel, alumina gel, and calcined alum. Generally, inorganic chemical water-absorbing agents have a higher water-absorbing effect than inorganic physical water-absorbing agents, can be reduced in content, and easily achieve sufficient water absorption and heat-sealing properties in a single layer. Among inorganic chemical water-absorbing agents, calcium oxide, anhydrous magnesium sulfate, and magnesium oxide are particularly preferred because they release little moisture, have high temporal stability in a low-humidity state within the package, and have an absolute dry effect. The absolute dry effect refers to the effect of absorbing water until the relative humidity reaches approximately 0%, and the humidity-regulating effect refers to the effect of absorbing water when the humidity is high and releasing moisture when the humidity is low, thereby maintaining a constant humidity. Furthermore, when the material is used in a high-temperature environment, such as for an all-solid-state battery, an inorganic chemical absorbent that re-releases moisture in a high temperature range is preferred.

[0100] In the first embodiment, the resin contained in the water absorption layer may be the same as the resin exemplified as the resin contained in the film 20 .

[0101] In the first embodiment, the content of the resin in the water absorption layer of the film 20 is, for example, 50% by mass or more, preferably 55% by mass or more, and more preferably 60% by mass or more.

[0102] In the first aspect, the content of the water-absorbing agent contained in the film 20 is not particularly limited as long as the effect of this embodiment is exhibited, and is preferably about 0.5 parts by mass or more, more preferably about 2 parts by mass or more, and even more preferably about 3 parts by mass or more relative to 100 parts by mass of the resin contained in the film 20, and is also preferably about 50 parts by mass or less, more preferably about 45 parts by mass or less, and even more preferably 40 parts by mass or less. Preferred ranges of the content include about 0.5 to 50 parts by mass, about 0.5 to 45 parts by mass, about 0.5 to 40 parts by mass, about 2 to 50 parts by mass, about 2 to 45 parts by mass, about 2 to 40 parts by mass, about 3 to 50 parts by mass, about 3 to 45 parts by mass, and about 3 to 40 parts by mass. The content of the water-absorbing agent contained in the water-absorbing layer of the film 20 is not particularly limited as long as the effect of this embodiment is achieved, and is preferably at least about 0.5 parts by mass, more preferably at least about 2 parts by mass, and even more preferably at least about 3 parts by mass, relative to 100 parts by mass of the resin contained in the water-absorbing layer. The content is also preferably at most about 50 parts by mass, more preferably at most about 45 parts by mass, and even more preferably at most 40 parts by mass. Preferred ranges for the content include about 0.5 to 50 parts by mass, about 0.5 to 45 parts by mass, about 0.5 to 40 parts by mass, about 2 to 50 parts by mass, about 2 to 45 parts by mass, about 2 to 40 parts by mass, about 3 to 50 parts by mass, about 3 to 45 parts by mass, and about 3 to 40 parts by mass.

[0103] In the film 20 according to the first embodiment, the water-absorbing agent contained in the water-absorbing layer is preferably contained via a masterbatch obtained by melt-blending the water-absorbing agent with a resin. Specifically, the water-absorbing agent is melt-blended with a resin at a relatively high concentration to prepare a masterbatch. The obtained masterbatch is further mixed with a resin and formed into a film, thereby forming the water-absorbing layer. The content of the water-absorbing agent in the masterbatch is preferably about 20 to 90% by mass, more preferably about 30 to 70% by mass. Within the above range, it is easy to incorporate a necessary and sufficient amount of the water-absorbing agent in the water-absorbing layer in a dispersed state.

[0104] As described above, the film 20 according to the first embodiment may further contain a sulfur-based gas absorbent in addition to the water-absorbing agent. The sulfur-based gas absorbent preferably contains a sulfur-based gas physical absorbent and / or a sulfur-based gas chemical absorbent. By using various sulfur-based gas absorbents in combination, for example, by using a sulfur-based gas physical absorbent and a sulfur-based gas chemical absorbent in combination, it becomes possible to easily absorb a variety of sulfur-based gases. The sulfur-based gas absorbent is used, for example, in the form of a powder. The maximum particle size of the sulfur-based gas absorbent is preferably 20 μm or less, and the number-average particle size of the powder is preferably 0.1 μm or more and 15 μm or less. If the number-average particle size is smaller than the above range, the sulfur-based gas absorbent is likely to aggregate. If the number-average particle size is larger than the above range, the homogeneity of the sulfur-based gas absorbing film may be poor, and the surface area of ​​the sulfur-based gas absorbent may be reduced, resulting in poor sulfur-based gas absorption.

[0105] (Sulfur gas physical absorbent) The sulfur-containing gas physical absorbent is a gas absorbent that has the effect of physically absorbing the sulfur-containing gas to be absorbed. The sulfur-containing gas physical absorbent preferably contains one or more selected from the group consisting of hydrophobic zeolite, bentonite, and sepiolite having an SiO2 / Al2O3 molar ratio of 1 / 1 to 2000 / 1.

[0106] Hydrophobic zeolites have a porous structure and are excellent at absorbing low-polarity molecules such as sulfur-based gases. Generally, the higher the molar ratio of SiO2 / Al2O3, the more hydrophobic the zeolite. Higher hydrophobicity facilitates the absorption of low-polarity molecules such as sulfur-based gases, while conversely, lowering the affinity for highly polar molecules such as water makes absorption more difficult. The SiO2 / Al2O3 molar ratio of hydrophobic zeolites is preferably 30 / 1 to 10,000 / 1, more preferably 35 / 1 to 9,000 / 1, and even more preferably 40 / 1 to 8,500 / 1. Furthermore, hydrophobic zeolites have high heat resistance and can maintain their absorption effect even when exposed to temperatures above 230°C. In the present invention, hydrophobic zeolites with a molar ratio within the above range are preferably used to balance sulfur-based gas absorption capacity and availability.

[0107] Bentonite is an inorganic substance whose main component is the clay mineral montmorillonite, containing a large amount of layered aluminum phyllosilicate and impurities such as quartz and feldspar. Bentonite includes, for example, Na-type bentonite, which contains a large amount of Na+ ions; Ca-type bentonite, which contains a large amount of Ca2+ ions; and activated bentonite, which is artificially converted to Na-type by adding a few wt% of sodium carbonate to Ca-type bentonite.

[0108] Sepiolite is a clay mineral whose main component is hydrous magnesium silicate, and its general chemical composition is Mg8Si 12 O 30 It is expressed as (OH2)4(OH)4·6-8H2O and has a porous structure. From the viewpoint of availability, the pH (3% suspension) is preferably 8.0-9.0, more preferably 8.9-9.3.

[0109] (Sulfur gas chemical absorbent) The sulfur-based gas chemical absorbent is a gas absorbent that has the function of chemically absorbing or decomposing sulfur-based gases in the gas to be absorbed. Because of the chemical absorption or decomposition, it is less susceptible to the influence of water and the like, and once absorbed, sulfur-based gas molecules are less likely to desorb, allowing for efficient absorption. The decomposition products are absorbed by the sulfur-based gas physical absorbent or sulfur-based gas chemical absorbent. The sulfur-based gas chemical absorbent preferably contains one or more metals selected from the group consisting of inorganic materials carrying metal oxides, glass containing metals, and glass containing metal ions. The metal oxide in the inorganic material carrying metal oxides preferably contains one or more metals selected from the group consisting of CuO, ZnO, and AgO. The inorganic material to be supported is preferably an inorganic porous material such as zeolite. The metal in the glass mixed with a metal, or the metal species of the metal ions in the glass mixed with metal ions, preferably includes one or more species selected from the group consisting of Ca, Mg, Na, Cu, Zn, Ag, Pt, Au, Fe, Al, and Ni.

[0110] In the first embodiment, the content of the sulfur-based gas absorbent in the film 20 is not particularly limited as long as it is sufficient to absorb sulfur-based gases, and is preferably at least about 0.1 part by mass, more preferably at least about 0.2 part by mass, and even more preferably at least about 0.3 part by mass, relative to 100 parts by mass of the resin contained in the film 20. The content is also preferably at most about 30 parts by mass, more preferably at most about 27 parts by mass, and even more preferably at most 25 parts by mass. Preferred ranges for the content include about 0.1 to 30 parts by mass, about 0.1 to 27 parts by mass, about 0.1 to 25 parts by mass, about 0.2 to 30 parts by mass, about 0.2 to 27 parts by mass, about 0.2 to 25 parts by mass, about 0.3 to 30 parts by mass, about 0.3 to 27 parts by mass, and about 0.3 to 25 parts by mass. The content of the sulfur-based gas absorbent contained in the sulfur-based gas absorbing layer of the film 20 is not particularly limited as long as it absorbs sulfur-based gases. The content is preferably about 5 parts by mass or more, more preferably about 6 parts by mass or more, and even more preferably about 7 parts by mass or more, relative to 100 parts by mass of the resin contained in the sulfur-based gas absorbing layer. The content is preferably about 60 parts by mass or less, more preferably about 55 parts by mass or less, and even more preferably about 50 parts by mass or less, or about 30 parts by mass or less. Preferred ranges for the content include about 5 to 60 parts by mass, about 5 to 55 parts by mass, about 5 to 50 parts by mass, about 5 to 30 parts by mass, about 6 to 60 parts by mass, about 6 to 55 parts by mass, about 6 to 50 parts by mass, about 6 to 30 parts by mass, about 7 to 60 parts by mass, about 7 to 55 parts by mass, about 7 to 50 parts by mass, and about 7 to 30 parts by mass.

[0111] In the first embodiment, the content of the resin contained in the sulfur-containing gas absorbing layer is, for example, 50% by mass or more, preferably 55% by mass or more, and more preferably 60% by mass or more.

[0112] In the first embodiment, the sulfur-based gas absorbent contained in the sulfur-based gas absorbing layer is preferably contained via a masterbatch obtained by melt-blending the sulfur-based gas absorbent with a resin. Specifically, it is preferable to prepare a masterbatch by melt-blending the sulfur-based gas absorbent with a resin at a relatively high concentration, and then dry-blend the masterbatch with other components to achieve a desired concentration in the sulfur-based gas absorbing layer. The sulfur-based gas absorbent and resin to be melt-blended may each be one type or two or more types. The content of the sulfur-based gas absorbent in the masterbatch is preferably about 20 to 90 mass %, more preferably about 30 to 70 mass %. Within the above range, it is easy to incorporate a necessary and sufficient amount of the sulfur-based gas absorbent in a dispersed state into the sulfur-based gas absorbing layer.

[0113] In the first embodiment, examples of the resin contained in the sulfur-based gas absorbing layer include the same resins as those exemplified as the resin contained in the water absorbing layer.

[0114] As described above, when the film 20 according to the first embodiment contains a sulfur-based gas absorbent, the sulfur-based gas absorbent may be contained in the water-absorbing layer, or may be contained in a layer that does not contain a water-absorbing agent. When the sulfur-based gas absorbent is contained in the water-absorbing layer, the water-absorbing layer also functions as a sulfur-based gas-absorbing layer.

[0115] The film 20 according to the first embodiment may contain various plastic compounding agents and additives for the purpose of improving or modifying, for example, processability, heat resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, slipperiness, release properties, flame retardancy, mildew resistance, electrical properties, strength, etc. The content of these may be any amount, ranging from trace amounts to several tens of percent, depending on the purpose. Common additives that may be included include, for example, antiblocking agents, lubricants, crosslinking agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, modifying resins, etc.

[0116] The thickness of the film 20 according to the first embodiment is not particularly limited as long as the effects of the present invention are achieved, and is preferably at least about 10 μm, more preferably at least about 15 μm, and even more preferably at least about 20 μm, and is preferably not more than about 1000 μm, more preferably not more than about 900 μm, and even more preferably not more than about 500 μm. Preferred ranges for the thickness include about 10 to 1000 μm, about 10 to 900 μm, about 10 to 500 μm, about 15 to 1000 μm, about 15 to 900 μm, about 15 to 500 μm, about 20 to 1000 μm, about 20 to 900 μm, and about 20 to 500 μm.

[0117] Furthermore, in the first embodiment, when film 20 is composed of two or more layers, the thickness of each layer may be as described above, provided that the thickness of film 20 is as described above. For example, the thickness of the water-absorbing layer is preferably about 5 μm or more, more preferably about 6 μm or more, and even more preferably about 7 μm or more, and is preferably about 500 μm or less, more preferably about 400 μm or less, and even more preferably about 300 μm or less, and preferred ranges for the thickness include about 5 to 500 μm, about 5 to 400 μm, about 5 to 300 μm, about 6 to 500 μm, about 6 to 400 μm, about 6 to 300 μm, about 7 to 500 μm, about 7 to 400 μm, and about 7 to 300 μm. The thickness of the sulfur-based gas absorbing layer is preferably about 5 μm or more, more preferably about 7 μm or more, and even more preferably about 10 μm or more, and is preferably about 500 μm or less, more preferably about 400 μm or less, and even more preferably about 300 μm or less. Preferred ranges for the thickness include about 5 to 500 μm, about 5 to 400 μm, about 5 to 300 μm, about 7 to 500 μm, about 7 to 400 μm, about 7 to 300 μm, about 10 to 500 μm, about 10 to 400 μm, and about 10 to 300 μm.

[0118] In the second embodiment, the sulfur-based gas absorbent preferably contains a sulfur-based gas physical absorbent and / or a sulfur-based gas chemical absorbent. By using various sulfur-based gas absorbents in combination, for example, by using a sulfur-based gas physical absorbent and a sulfur-based gas chemical absorbent in combination, it becomes possible to easily absorb a variety of sulfur-based gases. The sulfur-based gas absorbent is used, for example, in the form of a powder. The maximum particle size of the sulfur-based gas absorbent is preferably 20 μm or less, and the number average particle size of the powder is preferably 0.1 μm or more, 1.0 μm or more, or the like, and is also preferably 15 μm or less, 10 μm or less, or 8 μm or less, with preferred ranges being about 0.1 to 15 μm, about 0.1 to 10 μm, about 0.1 to 8 μm, about 1 to 15 μm, about 1 to 10 μm, about 1 to 8 μm. If the number average particle size is smaller than the above range, the sulfur-based gas absorbent will be prone to aggregation, and if the number average particle size is larger than the above range, the homogeneity of the sulfur-based gas absorbing film may be poor, and the surface area of ​​the sulfur-based gas absorbent may be small, resulting in poor sulfur-based gas absorption.

[0119] (Sulfur gas physical absorbent) The sulfur-containing gas physical absorbent is a gas absorbent that has the effect of physically absorbing the sulfur-containing gas to be absorbed. The sulfur-containing gas physical absorbent preferably contains one or more selected from the group consisting of hydrophobic zeolite, bentonite, and sepiolite having an SiO2 / Al2O3 molar ratio of 1 / 1 to 2000 / 1.

[0120] Specific examples of hydrophobic zeolite, bentonite, and sepiolite are the same as those described in the first embodiment, and therefore will not be described here.

[0121] (Sulfur gas chemical absorbent) The sulfur-based gas chemical absorbent is the same as that described in the first embodiment, and the description thereof will be omitted.

[0122] Examples of the resin contained in the sulfur-based gas absorbing layer include the same resins as those exemplified as the resin contained in the film 20 .

[0123] In the second embodiment, the content of the sulfur-based gas absorbent in the film 20 is not particularly limited as long as it is sufficient to absorb sulfur-based gases, and is preferably at least about 0.1 part by mass, more preferably at least about 0.2 part by mass, and even more preferably at least about 0.3 part by mass, relative to 100 parts by mass of the resin contained in the film 20. The content is also preferably at most about 30 parts by mass, more preferably at most about 29 parts by mass, and even more preferably at most 28 parts by mass. Preferred ranges for the content include about 0.1 to 30 parts by mass, about 0.1 to 29 parts by mass, about 0.1 to 28 parts by mass, about 0.2 to 30 parts by mass, about 0.2 to 29 parts by mass, about 0.2 to 28 parts by mass, about 0.3 to 30 parts by mass, about 0.3 to 29 parts by mass, and about 0.3 to 28 parts by mass. The content of the sulfur-based gas absorbent contained in the sulfur-based gas absorbing layer of the film 20 is not particularly limited as long as it absorbs sulfur-based gases. The content is preferably about 5 parts by mass or more, more preferably about 6 parts by mass or more, and even more preferably about 7 parts by mass or more, relative to 100 parts by mass of the resin contained in the sulfur-based gas absorbing layer. The content is preferably about 60 parts by mass or less, more preferably about 55 parts by mass or less, even more preferably about 50 parts by mass or less, and even more preferably about 30 parts by mass or less. Preferred ranges for the content include about 5 to 60 parts by mass, about 5 to 55 parts by mass, about 5 to 50 parts by mass, about 5 to 30 parts by mass, about 6 to 60 parts by mass, about 6 to 55 parts by mass, about 6 to 50 parts by mass, about 6 to 30 parts by mass, about 7 to 60 parts by mass, about 7 to 55 parts by mass, about 7 to 50 parts by mass, and about 7 to 30 parts by mass.

[0124] In the second embodiment, the content of the resin contained in the sulfur-containing gas absorbing layer is, for example, 40% by mass or more, preferably 45% by mass or more, and more preferably 50% by mass or more.

[0125] In the second embodiment, the sulfur-based gas absorbent contained in the sulfur-based gas absorbing layer is preferably contained via a masterbatch obtained by melt-blending the sulfur-based gas absorbent with a resin. Specifically, it is preferable to prepare a masterbatch by melt-blending the sulfur-based gas absorbent with a resin at a relatively high concentration, and then dry-blend the masterbatch with other components to achieve a desired concentration in the sulfur-based gas absorbing layer. The sulfur-based gas absorbent and resin to be melt-blended may each be one type or two or more types. The content of the sulfur-based gas absorbent in the masterbatch is preferably about 20 to 90 mass %, more preferably about 30 to 70 mass %. Within the above range, it is easy to incorporate a necessary and sufficient amount of the sulfur-based gas absorbent in a dispersed state into the sulfur-based gas absorbing layer.

[0126] As described above, in the second embodiment, the film 20 may further contain a water-absorbing agent in addition to the sulfur-based gas absorbent. The water-absorbing agent contained in the film 20 is not particularly limited as long as it exhibits water absorption when dispersed in a resin film. For example, from the viewpoint of temporal stability in the electricity storage device 10, an inorganic water-absorbing agent can be suitably used. Specific examples of preferred inorganic water-absorbing agents include calcium oxide, anhydrous magnesium sulfate, magnesium oxide, calcium chloride, zeolite, aluminum oxide, silica gel, alumina gel, and burnt alum. Generally, among inorganic water-absorbing agents, inorganic chemical water-absorbing agents have a higher water-absorbing effect than inorganic physical water-absorbing agents, can be reduced in content, and easily achieve sufficient water absorption and heat-sealing properties in a single layer. Among inorganic chemical water-absorbing agents, calcium oxide, anhydrous magnesium sulfate, and magnesium oxide are particularly preferred because they release less moisture, are stable over time in a low-humidity state within the package, and have an absolute dry effect. The bone-drying effect refers to the effect of absorbing water until the relative humidity reaches nearly 0%, and the humidity-regulating effect refers to the effect of absorbing water when the humidity is high and releasing moisture when the humidity is low, thereby maintaining a constant humidity. Furthermore, when used in a high-temperature environment, such as for all-solid-state batteries, inorganic chemical absorbents with a high temperature range for re-releasing moisture are preferred.

[0127] In the second aspect, the content of the water-absorbing agent contained in the film 20 is not particularly limited as long as the effect of this embodiment is exhibited, and is preferably about 0.5 parts by mass or more, more preferably about 2 parts by mass or more, even more preferably about 3 parts by mass or more, relative to 100 parts by mass of the resin contained in the film 20, and is preferably about 50 parts by mass or less, more preferably about 45 parts by mass or less, even more preferably 40 parts by mass or less, and preferred ranges of the content include about 0.5 to 50 parts by mass, about 0.5 to 45 parts by mass, about 0.5 to 40 parts by mass, about 2 to 50 parts by mass, about 2 to 45 parts by mass, about 2 to 40 parts by mass, about 3 to 50 parts by mass, about 3 to 45 parts by mass, and about 3 to 40 parts by mass. The content of the water-absorbing agent contained in the water-absorbing layer of the film 20 is not particularly limited as long as the effect of this embodiment is achieved, and is preferably at least about 0.5 parts by mass, more preferably at least about 2 parts by mass, and even more preferably at least about 3 parts by mass, relative to 100 parts by mass of the resin contained in the water-absorbing layer. The content is also preferably at most about 50 parts by mass, more preferably at most about 45 parts by mass, and even more preferably at most 40 parts by mass. Preferred ranges for the content include about 0.5 to 50 parts by mass, about 0.5 to 45 parts by mass, about 0.5 to 40 parts by mass, about 2 to 50 parts by mass, about 2 to 45 parts by mass, about 2 to 40 parts by mass, about 3 to 50 parts by mass, about 3 to 45 parts by mass, and about 3 to 40 parts by mass.

[0128] In the film 20 according to the second embodiment, the water-absorbing agent contained in the water-absorbing layer is preferably contained via a masterbatch obtained by melt-blending the water-absorbing agent with a resin. Specifically, the water-absorbing agent is melt-blended with a resin at a relatively high concentration to prepare a masterbatch. The obtained masterbatch is further mixed with a resin and formed into a film, thereby forming the water-absorbing layer. The content of the water-absorbing agent in the masterbatch is preferably about 20 to 90% by mass, more preferably about 30 to 70% by mass. Within the above range, it is easy to incorporate a necessary and sufficient amount of the water-absorbing agent in the water-absorbing layer in a dispersed state.

[0129] In the second embodiment, the resin contained in the water absorption layer may be the same as the resin exemplified as the resin contained in the film 20 .

[0130] In the second embodiment, the content of the resin in the water absorption layer of the film 20 is, for example, 50% by mass or more, preferably 55% by mass or more, and more preferably 60% by mass or more.

[0131] As described above, when the film 20 according to the second embodiment contains a water-absorbing agent, the water-absorbing agent may be contained in the sulfur-based gas absorbing layer, or may be contained in a layer that does not contain a sulfur-based gas absorbent. When the water-absorbing agent is contained in the sulfur-based gas absorbing layer, the sulfur-based gas absorbing layer also functions as a water-absorbing layer.

[0132] In the second embodiment, the film 20 may contain various plastic compounding agents and additives for the purpose of improving or modifying, for example, processability, heat resistance, weather resistance, mechanical properties, dimensional stability, oxidation resistance, slipperiness, release properties, flame retardancy, mildew resistance, electrical properties, strength, etc. The content of these may be any amount, ranging from trace amounts to several tens of percent, depending on the purpose. Common additives that may be contained in the film 20 include, for example, antiblocking agents, lubricants, crosslinking agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, modifying resins, etc.

[0133] In the second embodiment, the thickness of the film 20 is not particularly limited as long as the effects of the present invention are achieved, and is preferably at least about 25 μm, more preferably at least about 30 μm, and even more preferably at least about 40 μm, and is preferably not more than about 250 μm, more preferably not more than about 240 μm, and even more preferably not more than about 230 μm. Preferred ranges for the thickness include about 25 to 250 μm, about 25 to 240 μm, about 25 to 230 μm, about 30 to 250 μm, about 30 to 240 μm, about 30 to 230 μm, about 40 to 250 μm, about 40 to 240 μm, and about 40 to 230 μm.

[0134] In the second embodiment, when the film 20 is composed of two or more layers, the thickness of each layer may be as described above, provided that the thickness of the film 20 is as described above. For example, the thickness of the sulfur-based gas absorbing layer is preferably about 10 μm or more, more preferably about 15 μm or more, and even more preferably about 20 μm or more, and is, for example, about 100 μm or less, preferably about 95 μm or less, more preferably about 90 μm or less, and even more preferably about 85 μm or less. Preferred ranges of the thickness include about 10 to 100 μm, about 10 to 95 μm, about 10 to 90 μm, about 10 to 85 μm, about 15 to 100 μm, about 15 to 95 μm, about 15 to 90 μm, about 15 to 85 μm, about 20 to 100 μm, about 20 to 95 μm, about 20 to 90 μm, and about 20 to 85 μm. The thickness of the water absorption layer is preferably about 5 μm or more, more preferably about 6 μm or more, and even more preferably about 7 μm or more, and is preferably about 60 μm or less, more preferably about 55 μm or less, and even more preferably about 50 μm or less. Preferred ranges for the thickness include about 5 to 60 μm, about 5 to 55 μm, about 5 to 50 μm, about 6 to 60 μm, about 6 to 55 μm, about 6 to 50 μm, about 7 to 60 μm, about 7 to 55 μm, and about 7 to 50 μm.

[0135] (Method of manufacturing film 20) In the present embodiment, the method for producing film 20 is not particularly limited as long as film 20 can be obtained, and known or commonly used film-forming methods and lamination methods can be applied. Film 20 can be produced by known film-forming and / or lamination methods, such as extrusion or co-extrusion, cast molding, T-die molding, cutting, or inflation. When film 20 is composed of two or more layers, for example, pre-prepared films constituting each layer may be laminated via an adhesive layer, a molten resin composition may be laminated onto a pre-prepared layer by extrusion or co-extrusion, multiple layers may be simultaneously produced and laminated by melt-press bonding, or one or more resins may be applied and dried to coat another layer.

[0136] In the first embodiment, the layers constituting the film 20, such as the water-absorbing layer (sulfur-based gas absorbing layer), can be laminated by extrusion or co-extrusion using an extrusion coating method, or can be laminated via an adhesive layer after film formation using an inflation method or a casting method. Even in the case of the extrusion coating method, lamination may be performed via an adhesive layer as needed. Alternatively, a film for the water-absorbing layer (or sulfur-based gas absorbing layer) that has been previously formed may be laminated and bonded via an adhesive layer that has been laminated by an extrusion coating method, a dry lamination method, a non-solvent lamination method, or the like. Then, an aging treatment may be performed as needed.

[0137] In the first embodiment, for example, when laminating a water-absorbing layer or the like by extrusion coating, the resin composition forming the water-absorbing layer or the like is first heated and melted, and then expanded and stretched in the required width direction using a T-die to form a curtain-like extrusion or co-extrusion. The molten resin is then allowed to flow onto the surface to be laminated and sandwiched between a rubber roll and a cooled metal roll, thereby simultaneously forming the water-absorbing layer or the like and laminating and adhering it to the surface to be laminated. When laminating by extrusion coating, the melt flow rate (MFR) of the resin component contained in each layer is preferably 0.2 to 50 g / 10 min, more preferably 0.5 to 30 g / 10 min. If the MFR is smaller or larger than the above range, processability is likely to be poor. Note that, in this specification, MFR is a value measured using a method in accordance with JIS K7210.

[0138] In the first embodiment, when an inflation method is used, the melt flow rate (MFR) of the resin component contained in each layer is preferably 0.2 to 10 g / 10 min, more preferably 0.2 to 9.5 g / 10 min. If the MFR is lower or higher than the above range, the processability is likely to be poor.

[0139] In the second embodiment, the layers constituting the film 20, such as the sulfur-based gas absorbing layer (water absorbing layer), can be laminated by extrusion or co-extrusion using an extrusion coating method, or can be laminated via an adhesive layer after film formation using an inflation method or a casting method. Even in the case of the extrusion coating method, lamination may be performed via an adhesive layer as needed. Alternatively, a film for the sulfur-based gas absorbing layer (or water absorbing layer) that has been previously formed may be laminated and bonded via an adhesive layer that has been laminated by an extrusion coating method, a dry lamination method, a non-solvent lamination method, or the like. Then, an aging treatment may be performed as needed.

[0140] In the second embodiment, for example, when laminating a sulfur-based gas absorbing layer or the like by extrusion coating, a resin composition for forming the sulfur-based gas absorbing layer or the like is first heated and melted, and then expanded and stretched in the required width direction through a T-die to form a curtain-like extrusion or co-extrusion. The molten resin is then allowed to flow onto the surface to be laminated and sandwiched between a rubber roll and a cooled metal roll, thereby simultaneously forming the sulfur-based gas absorbing layer or the like and laminating and adhering it to the surface to be laminated. When laminating by extrusion coating, the melt flow rate (MFR) of the resin component contained in each layer is preferably 0.2 to 50 g / 10 min, more preferably 0.5 to 30 g / 10 min. If the MFR is smaller or larger than the above range, processability tends to be poor. In this specification, the MFR is a value measured by a method conforming to JIS K7210.

[0141] In the second embodiment, when the inflation method is used, the melt flow rate (MFR) of the resin component contained in each layer is preferably 0.2 to 10 g / 10 min, more preferably 0.2 to 9.5 g / 10 min. If the MFR is lower or higher than the above range, the processability is likely to be poor.

[0142] In this embodiment, the surfaces of the layers constituting the film 20 may be subjected to a desired surface treatment in advance, as needed, to improve adhesion between the layers. For example, pretreatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, and oxidation treatment using chemicals may be optionally performed to form a corona-treated layer, ozone-treated layer, plasma-treated layer, oxidation-treated layer, etc. Alternatively, various coating layers such as a primer coating layer, undercoat layer, anchor coating layer, adhesive layer, and vapor-deposited anchor coating layer may be optionally formed on the surface to form a surface-treated layer. The various coating layers may be, for example, resin compositions containing polyester resins, polyamide resins, polyurethane resins, epoxy resins, phenolic resins, (meth)acrylic resins, polyvinyl acetate resins, polyolefin resins such as polyethylene or polypropylene, or copolymers or modified resins thereof, or cellulose resins as the main vehicle component.

[0143] In this embodiment, each layer constituting the film 20 can be further uniaxially or biaxially stretched as needed by a conventionally known method using a tenter system, a tubular system, or the like.

[0144] <1-3. Manufacturing method of energy storage device> 8 is a flowchart showing a manufacturing procedure for the power storage device 10. The steps shown in FIG.

[0145] The manufacturing equipment wraps the exterior member 101 around the electrode body 200 (step S100). The manufacturing equipment heat-seals the surfaces (thermal adhesive resin layers) of the exterior member 101 that face each other to form the first sealed portion 110 (step S110). This completes the unfinished product shown in FIGS. 4 and 5.

[0146] The manufacturing equipment folds the first sealing portion 110 so that the first sealing portion 110 contacts the second surface 140 (step S120). The manufacturing equipment folds the exterior member 101 with the electrode body 200 stored therein, and forms the second sealing portion 120 by heat-sealing the surfaces (thermal adhesive resin layers) of the exterior member 101 that face each other (step S130). This completes the electricity storage device 10.

[0147] <1-4. Features> In the electricity storage device 10 including the film 20 of the first embodiment, the film 20 contains a water absorbing agent, and therefore the film 20 absorbs and retains moisture that has penetrated through the heat-sealable resin layer 101C of the exterior member 101, thereby preventing the moisture from reaching the electrode assembly 200. In the electricity storage device 10 including the film 20 of the second embodiment, the film 20 contains a sulfur-based gas absorbent, and therefore the film 20 absorbs hydrogen sulfide generated from the electrode assembly 200. This makes it possible to prevent the internal pressure of the exterior assembly 100 from increasing excessively.

[0148] Furthermore, in the energy storage device 10 according to the first embodiment, the first sealing portion 110 is bent toward the second surface 140, which has a smaller area. That is, the first sealing portion 110 is not present on the first surface 130, which has a larger area. Therefore, even if another energy storage device 10 is placed on the first surface 130, the other energy storage device 10 will not tilt. As a result, the energy storage device 10 can suppress unevenness in the distribution of pressure applied to the lower energy storage device 10 when multiple energy storage devices 10 are stacked. Furthermore, when used in an all-solid-state battery, high pressure must be applied uniformly from the outer surface of the battery to maximize battery performance, and therefore the packaging form of the present invention is preferable. Furthermore, in the energy storage device 10, the base portion of the first sealing portion 110 is located on a side 135 of the exterior body 100. Therefore, according to the energy storage device 10, when the first sealing portion 110 is fitted onto the second surface 140, a wider bonding width can be ensured in the first sealing portion 110 compared to when the base portion of the first sealing portion 110 is on the second surface 140.

[0149] [2. Second Embodiment] In the electricity storage device 10 according to the first embodiment, the second sealed portion 120 is formed by folding the exterior member 101 and heat-sealing the surfaces of the exterior member 101 that face each other. However, the shape and method of forming the second sealed portion 120 are not limited to this. The following description will focus on parts that are different from the first embodiment, and a description of parts that are common to the first embodiment will be omitted.

[0150] <2-1. Configuration of the energy storage device> Fig. 9 is a plan view schematically showing an electricity storage device 10X according to the second embodiment, Fig. 10 is a side view schematically showing an electricity storage device 10X, and Fig. 11 is a perspective view schematically showing a lid 400.

[0151] 9, 10, and 11, the exterior body 100X is formed by fitting a lid body 400 into each of the openings at both ends of an exterior member 101 wrapped around the electrode assembly 200. With the lid body 400 fitted, the exterior member 101 and the lid body 400 are heat-sealed to form a second sealed portion 120X.

[0152] The lid 400 is a bottomed tray-like member having a rectangular shape in a plan view and is formed by, for example, cold-forming the exterior member 101. The lid 400 does not necessarily have to be made of the exterior member 101, but may be a metal molded product or a resin molded product. That is, the material constituting the lid 400 may include at least one of a resin material and a metal material. For example, the lid 400 may have a main body portion containing a metal material and a covering body containing a resin material that covers a portion of the main body portion. The covering body may be a frame-shaped object made of a resin molded product, or may be an adhesive film that is suitably bonded to both metal materials and resin materials. The main body portion is preferably bonded to the exterior member 101 via the covering body. In the power storage device 10X, the lid 400 is arranged so that the bottom side of the lid 400 is located inside the exterior member 100X. In the power storage device 10X, the bottom side of the lid 400 does not necessarily have to be located inside the exterior member 100X. In the electricity storage device 10X, the bottom side of the lid body 400 may be located outside the exterior body 100X. When the lid body 400 is a metal molded product or a resin molded product, it is preferable that the material constituting the lid body 400 has a certain thickness so that deformation of the exterior body 100X is suppressed even when the electricity storage device 10X is placed on top of it. The minimum thickness of the material constituting the lid body 400 is, for example, 1.0 mm, more preferably 3 mm, and even more preferably 4 mm. The maximum thickness of the material constituting the lid body 400 is, for example, 10 mm, more preferably 8.0 mm, and even more preferably 7.0 mm. The maximum thickness of the material constituting the lid body 400 may be 10 mm or more. Preferred ranges for the thickness of the material constituting the lid body 400 are 1.0 mm to 10 mm, 1.0 mm to 8.0 mm, 1.0 mm to 7.0 mm, 3.0 mm to 10 mm, 3.0 mm to 8.0 mm, 3.0 mm to 7.0 mm, 4.0 mm to 10 mm, 4.0 mm to 8.0 mm, and 4.0 mm to 7.0 mm. In the present disclosure, when the lid body 400 is expressed as a metal molded product or a resin molded product, a film is not included as a material constituting the lid body 400. The film is, for example, a film defined by the JIS (Japanese Industrial Standards) "Packaging Terminology" standard.The film specified by the JIS [Packaging Terminology] standard is a plastic membrane with a thickness of less than 250 μm. The thickness of the material constituting the lid body 400 may vary depending on the part of the lid body 400. When the thickness of the material constituting the lid body 400 varies depending on the part of the lid body 400, the thickness of the material constituting the lid body 400 is the thickness of the thickest part.

[0153] Furthermore, when the electrode body 200 is stored, the electrode terminal 300 passes between the lid body 400 and the exterior member 101 and protrudes to the outside of the exterior body 100X. That is, the lid body 400 and the exterior member 101 are heat-sealed with the electrode terminal 300 sandwiched between them. Note that in the power storage device 10X, the position from which the electrode terminal 300 protrudes to the outside does not necessarily have to be between the lid body 400 and the exterior member 101. For example, the electrode terminal 300 may protrude to the outside from a hole formed in any one of the six surfaces of the exterior body 100X. In this case, a small gap between the exterior body 100X and the electrode terminal 300 is filled with, for example, resin.

[0154] Furthermore, in the power storage device 10X, the lid body 400 and the electrode terminal 300 are provided as separate bodies. However, the lid body 400 and the electrode terminal 300 do not necessarily have to be provided as separate bodies. For example, the lid body 400 and the electrode terminal 300 may be integrally formed.

[0155] FIG. 12 is a diagram showing a first example in which the lid 400 and the electrode terminal 300 are integrally formed. As shown in FIG. 12, in the first example, the electrode terminal 300 is pre-heat-sealed to the side surface of the lid 400. Note that, for example, when the lid 400 is formed of an exterior member 101, an adhesive film that adheres to both metal and resin, as described in the first embodiment, may be disposed between the lid 400 and the electrode terminal 300. When the adhesive film has two or more layers, it is preferable to dispose a resin film made of a polyolefin resin on the side that is bonded to the lid 400. When the adhesive film has two or more layers, it is preferable to dispose a resin film made of an acid-modified polyolefin resin, which is obtained by graft-modifying a polyolefin resin with an acid such as maleic anhydride, on the side that is bonded to the electrode terminal 300.

[0156] Fig. 13 is a diagram showing a second example in which the lid 400 and the electrode terminal 300 are integrally formed. As shown in Fig. 13, in the second example, the electrode terminal 300 passes through a hole formed in the bottom surface of the lid 400. A small gap in the hole in the bottom surface of the lid 400 is filled with, for example, resin.

[0157] Furthermore, in the power storage device 10X, a gas valve may be attached to a hole formed in the second sealing portion 120X or in any one of the six surfaces of the exterior body 100X. The gas valve is configured, for example, as a check valve or a breaker valve, and is configured to reduce the pressure inside the exterior body 100X when the pressure increases due to gas generated inside the power storage device 10X.

[0158] <2-2. Manufacturing method of electricity storage device> Fig. 14 is a flowchart showing a manufacturing procedure for the power storage device 10X. The steps shown in Fig. 14 are performed by, for example, a manufacturing apparatus for the power storage device 10X.

[0159] The manufacturing equipment wraps the exterior member 101 around the electrode body 200 (step S200). The manufacturing equipment heat-seals the surfaces (thermal adhesive resin layers) of the exterior member 101 that face each other to form the first sealed portion 110 (step S210). This completes the unfinished product shown in FIGS. 4 and 5.

[0160] The manufacturing equipment bends the first sealing portion 110 so that the first sealing portion 110 contacts the second surface 140 (step S220). The manufacturing equipment houses the electrode assembly 200 in the unfinished product produced in step S220 and attaches lid bodies 400 to the openings at both ends (step S230). The manufacturing equipment forms the second sealing portion 120X by heat-sealing the exterior member 101 and the lid body 400 (step S240). This completes the electricity storage device 10X.

[0161] <2-3. Features> In the power storage device 10X according to the second embodiment, the first sealing portion 110 is also bent toward the second surface 140, which has a smaller area. Therefore, with the power storage device 10X, when a plurality of power storage devices 10X are stacked, unevenness in the distribution of pressure applied to the lower power storage device 10X can be suppressed.

[0162] <2-4. Other features> In the power storage device 10X according to the second embodiment, the first sealing unit 110 does not necessarily have to be bent toward the second surface 140, which has a smaller area. For example, the first sealing unit 110 may be bent toward the first surface 130, which has a larger area. Furthermore, the base portion of the first sealing unit 110 does not necessarily have to be on the side 135 of the exterior body 100X. The base portion of the first sealing unit 110 may be located on a surface of the exterior body 100X other than the lid body 400, for example. Even in this case, the power storage device 10X according to the second embodiment includes, for example, the following features.

[0163] The energy storage device 10X comprises an electrode body (electrode body 200) and an exterior body (exterior body 100X) that seals the electrode body (electrode body 200). The exterior body (exterior body 100X) is wrapped around the electrode body (electrode body 200) and comprises an exterior member (exterior member 101) having openings formed at both ends, and a lid (lid body 400) that seals the openings.

[0164] In the electricity storage device 10X, the second sealed portion 120X is not formed by heat-sealing mutually facing surfaces of the exterior member 101 as in the first embodiment (see FIG. 7). In the electricity storage device 10X, the opening of the exterior member 101 wrapped around the electrode assembly 200 is sealed by the lid body 400. That is, the second sealed portion 120X is formed in the portion where the lid body 400 and the exterior member 101 overlap (see FIGS. 9 and 10). With this configuration, the area of ​​the second sealed portion 120X can be easily narrowed by adjusting the depth L3 (FIG. 11) of the lid body 400.

[0165] Furthermore, in the electricity storage device 10X, an excessive load caused by the corner C1 (FIGS. 9 and 10) of the electrode body 200 piercing the exterior member 101 is not generated at a position of the exterior member 101 that covers the corner C1. This is because, as described above, in the electricity storage device 10X, the second sealed portion 120X is not formed by heat-sealing the mutually facing surfaces of the exterior member 101 as in the first embodiment.

[0166] Furthermore, the manufacturing procedure for the power storage device 10X is not limited to the procedure shown in the flowchart of Fig. 14. For example, the power storage device 10X may be manufactured according to the procedure shown in the flowchart of Fig. 15.

[0167] FIG. 15 is a flowchart showing another manufacturing procedure for the power storage device 10X according to the second embodiment. The steps shown in FIG. 15 are performed, for example, by a manufacturing apparatus for the power storage device 10X. The manufacturing apparatus attaches a member (for example, the member shown in FIGS. 12 and 13) in which the electrode terminal 300 and the lid body 400 are integrated to the electrode body 200 (step S250). For example, the electrode terminal 300 is welded to the electrode body 200. The manufacturing apparatus then wraps the exterior member 101 around the electrode body 200 (step S260). The manufacturing apparatus forms the first sealed portion 110 by heat-sealing the surfaces (thermally adhesive resin layers) of the exterior member 101 that face each other, and forms the second sealed portion 120X by heat-sealing the exterior member 101 and the lid body 400 together (step S270). This completes the power storage device 10X. The power storage device 10X may be manufactured by such a procedure.

[0168] 3. Third Embodiment In a battery manufacturing process, a temporarily sealed electricity storage device typically undergoes a step of aging for a predetermined time in a predetermined temperature environment (hereinafter referred to as the aging step) for the purpose of allowing an electrolyte solution to penetrate into the electrode body. During the aging step, gas is generated from the electrode body 200, and it is necessary to discharge the gas to the outside of the battery. In the electricity storage device 10X according to the second embodiment, no mechanism is provided for releasing the gas generated in the aging step in the final stage of manufacturing the electricity storage device 10X. In the electricity storage device 10Y according to the third embodiment, a mechanism is provided for releasing the gas generated from the electrode body 200 in the final stage of manufacturing the electricity storage device 10Y. Note that the following description will focus on differences from the second embodiment, and a description of parts common to the second embodiment will be omitted.

[0169] <3-1. Configuration of the energy storage device> Fig. 16 is a side view showing a state in which the exterior member 101Y is wrapped around the electrode body 200 during the manufacture of the electricity storage device 10Y. Fig. 17 is a bottom view showing a state in which the exterior member 101Y is wrapped around the electrode body 200 and the lid body 400 is attached to the exterior member 101Y during the manufacture of the electricity storage device 10Y.

[0170] 16 and 17, a piece 150 is formed when the exterior member 101Y is wrapped around the electrode body 200. The piece 150 is formed by joining mutually facing surfaces of the exterior member 101Y when the exterior member 101Y is wrapped around the electrode body 200. More specifically, the piece 150 is formed by joining (heat sealing) the peripheral edges of the surfaces that face each other when the exterior member 101Y is wrapped around the electrode body 200. That is, a first sealed portion 154 is formed on the peripheral edge of the piece 150.

[0171] Furthermore, in the piece 150, spaces 152 are formed where the opposing surfaces of the exterior member 101Y are not joined. In the vicinity of the side 135, joined regions 151 where the opposing surfaces of the exterior member 101Y are joined and unjoined regions 153 where the opposing surfaces of the exterior member 101Y are not joined are arranged alternately. That is, in the piece 150, a pattern of joined regions 151 is formed along the side 135.

[0172] The gas generated from the electrode body 200 is discharged to the outside of the exterior body 100Y by releasing the sealed state of the exterior body 100Y, for example by cutting off a part of the piece 150. Note that the gas discharged to the outside of the exterior body 100Y here is not necessarily limited to the gas generated from the electrode body 200, and may be a gas other than the gas generated from the electrode body 200, such as air, water vapor, or hydrogen sulfide.

[0173] Thereafter, the portion including the vicinity of side 135 is heat-sealed in a strip shape, thereby sealing the exterior body 100Y again. This completes the electricity storage device 10Y. In the completed electricity storage device 10Y, near side 135, regions where the bonding strength between the opposing surfaces of the exterior member 101Y is strong and regions where the bonding strength between the surfaces is weak are alternately arranged along side 135. In other words, in the heat-sealed portion near side 135, thin portions and thick portions are alternately arranged along side 135. This is because, by heat-sealing the vicinity of side 135 again, the unbonded region 153 is single-sealed, but the bonded region 151 is double-sealed.

[0174] <3-2. Method of manufacturing electricity storage devices> Fig. 18 is a flowchart showing a manufacturing procedure for the power storage device 10Y. The steps shown in Fig. 18 are performed by, for example, a manufacturing apparatus for the power storage device 10Y.

[0175] The manufacturing equipment wraps the exterior member 101Y around the electrode body 200 (step S300). The manufacturing equipment forms the first sealed portion 154 by heat-sealing the peripheral edges of the opposing surfaces (thermally adhesive resin layers) of the exterior member 101Y (step S310). The manufacturing equipment forms the pattern of the bonding region 151 by heat-sealing the opposing surfaces of the exterior member 101Y in the vicinity of the side 135 (step S320).

[0176] The manufacturing equipment attaches lid bodies 400 to the openings at both ends with the electrode assembly 200 housed in the unfinished product produced in step S320 (step S330). The manufacturing equipment forms the second sealed portion 120X by heat-sealing the exterior member 101Y and the lid body 400 (step S340). Then, an aging process is performed.

[0177] The manufacturing equipment removes gas generated in the aging step by, for example, cutting off piece 150 (step S350). The manufacturing equipment heat-seals a portion of piece 150 including bonding region 151 into a strip shape and removes the edge portion to reseal exterior body 100Y (step S360). Thereafter, piece 150 is folded toward second surface 140, thereby completing electricity storage device 10Y.

[0178] <3-3. Features> In the electricity storage device 10Y according to the third embodiment, the piece 150 including the first sealing portion 154 is also folded toward the second surface 140, which has a smaller area. Therefore, with the electricity storage device 10Y, when a plurality of electricity storage devices 10Y are stacked, unevenness in the distribution of pressure applied to the lower electricity storage device 10Y can be suppressed. When used in an all-solid-state battery, the packaging form of the present invention is preferred because it is necessary to apply high pressure uniformly from the outer surface of the battery to exhibit battery performance.

[0179] [4. Fourth Embodiment] In the power storage device 10X according to the second embodiment, the position from which the electrode terminals 300 protrude to the outside is between the lid body 400 and the exterior member 101. However, the position from which the electrode terminals 300 protrude to the outside is not limited to this. The following description will focus on the parts that are different from the second embodiment, and a description of the parts that are common to the second embodiment will be omitted.

[0180] <4-1. Configuration of the energy storage device> FIG. 19 is a plan view schematically showing an electricity storage device 10XA according to a fourth embodiment. FIG. 20 is a side view schematically showing the electricity storage device 10XA. In a plan view, the exterior body 100X of the electricity storage device 10XA includes a pair of long sides 100XA and a pair of short sides 100XB. The exterior body 100X is formed by fitting a lid body 400 into each of openings along the long sides 100XA of an exterior member 101 wrapped around the electrode assembly 200. With the lid body 400 fitted, the exterior member 101 and the lid body 400 are heat-sealed to form a second sealed portion 120X. A through hole (not shown) is formed in the lid body 400. Two electrode terminals 300 protrude from the through holes of the lid body 400 to the outside of the exterior body 100X. The two electrode terminals 300 are shaped to fit along the long sides 100XA of the exterior body 100X. Small gaps between the through holes and the electrode terminals 300 are filled with, for example, resin. In the fourth embodiment, the first sealing portion 110 is formed on one side of the pair of short sides 100XB.

[0181] The position from which the electrode terminal 300 protrudes in the lid body 400 in the thickness direction (arrow UD direction) of the power storage device 10XA can be selected arbitrarily. In the fourth embodiment, as shown in FIG. 20 , the electrode terminal 300 protrudes from approximately the center of the lid body 400 to the outside of the exterior body 100X in the thickness direction of the power storage device 10XA. The length of the electrode terminal 300 in the depth direction (arrow FB direction) of the power storage device 10XA can be selected arbitrarily. In the fourth embodiment, the length of the electrode terminal 300 in the depth direction (arrow FB direction) of the power storage device 10XA is substantially the same as the length of the electrode body 200.

[0182] <4-2. Features> In the power storage device 10XA according to the fourth embodiment, the electrode terminals 300 are arranged along the long side 100XA that is longer in the depth direction, and therefore larger electrode terminals 300 can be used, making it possible to provide a high-output power storage device 10XA.

[0183] [5. Modifications] The above-described embodiments are examples of possible forms of the power storage device according to the present invention, and are not intended to limit the forms. The power storage device according to the present invention may take forms different from those exemplified in the above-described embodiments. Examples of such forms include forms in which part of the configuration of each of the above-described embodiments is replaced, modified, or omitted, or forms in which a new configuration is added to each of the above-described embodiments. Some examples of modified versions of each of the above-described embodiments are shown below. Note that the above-described embodiments can also be combined within the scope of not causing technical contradictions.

[0184] <5-1> In the first to fourth embodiments, one exterior member is wrapped around the electrode body 200. However, it is not necessary to wrap one exterior member around the electrode body 200. For example, two or more exterior members may be wrapped around the electrode body 200.

[0185] FIG. 21 is a side view showing the state in which exterior members 101Z1 and 101Z2 are wrapped around the electrode assembly 200 during the manufacturing process of an electric storage device according to a modified example. As shown in FIG. 21, the electrode assembly 200 is surrounded by the exterior members 101Z1 and 101Z2. The first sealing portion 110Z is formed by joining the opposing surfaces of the exterior members 101Z1 and 101Z2. In this example, each first sealing portion 110Z is bent toward the second surface 140Z, not toward the first surface 130Z. Even with this configuration, it is possible to suppress unevenness in the distribution of pressure applied to the lower electric storage device when multiple electric storage devices are stacked. When used in an all-solid-state battery, the packaging form of the present invention is preferable because high pressure must be applied uniformly from the outer surface of the battery to maximize battery performance. Note that in this example, each first sealing portion 110Z does not necessarily need to be bent. In this modified example, each sealing portion 110Z may seal while sandwiching a part of the electrode terminal 300. Furthermore, in this modified example, each first sealing portion 110Z does not need to be formed on the side 135Z, and may protrude outward from approximately the center of the second surface 140Z in the thickness direction of the power storage device.

[0186] <5-2> Furthermore, in the first to fourth embodiments, the electrode body 200 is a so-called stack type formed by stacking a plurality of electrodes 210, but the form of the electrode body 200 is not limited to this. The electrode body 200 may be, for example, a so-called wound type formed by winding a positive electrode and a negative electrode with a separator interposed therebetween. Furthermore, the electrode body 200 may be formed by stacking a plurality of so-called wound type electrode bodies.

[0187] <5-3> Furthermore, in the first to fourth embodiments, the second surface 140 is a flat surface that extends downward from the first surface 130 at a substantially right angle. However, the form of the second surface 140 is not limited to this. For example, consider a case where the electrode body 200 is a wound electrode body with flat and curved surfaces formed on the outer periphery. Here, assume that the area of ​​the flat surface is larger than the area of ​​the curved surface, and the first surface 130 covers the flat surface of the electrode body, and the second surface 140 covers the curved surface of the electrode body. In this case, the second surface 140 may be configured as a curved surface. In this case, the boundary where the second surface 140 extends downward from the first surface 130 is the side 135.

[0188] <5-4> Furthermore, in the third embodiment, the bonding regions 151 are formed in four locations. However, the number of locations where the bonding regions 151 are formed is not limited to this. For example, the bonding regions 151 may be formed in two locations near both ends along the side 135, in one location near the center of the side 135, or in five or more locations.

[0189] <5-5> Furthermore, in the second embodiment, the electrode terminal 300 is disposed in the second sealing portion 120X, but the position at which the electrode terminal 300 is disposed in the exterior body 100X is not limited to this. For example, as shown in FIG. 22 , in the second embodiment, the electrode terminal 300 can also be disposed in the first sealing portion 110. In other words, the first sealing portion 110 is sealed with the electrode terminal 300 sandwiched between them. In this modification, at least one of the two electrode terminals 300 may be bent toward the second surface 140, bent away from the second surface 140, or not bent so as to protrude outward from the side 135. In this modification, the electrode terminal 300 and the first sealing portion 110 can be easily sealed, thereby improving the hermeticity of the exterior body 100X. Furthermore, the electrode body 200 can be easily accommodated in the exterior body 100X. In this modification, for example, as in the second embodiment, the lid 400 is fitted into each of the openings at both ends of the exterior member 101X. With the lid 400 fitted, the exterior member 101X and the lid 400 are heat-sealed to form the second sealing portion 120. In the first embodiment, the electrode terminal 300 may also be disposed in the first sealing portion 110.

[0190] <5-6> Furthermore, in the second embodiment, the configuration of the lid 400 can be modified as desired. FIG. 23 is a perspective view showing a lid 500, which is a modified version of the lid 400. The lid 500 is, for example, plate-shaped and includes a first surface 500A facing the electrode assembly 200 (see FIG. 9) and a second surface 500B opposite the first surface 500A. A hole 500C penetrating the first surface 500A and the second surface 500B is formed in the center of the lid 500. The material constituting the lid 500 includes, for example, a resin material. The lid 500 may also include a metal material. That is, the material constituting the lid 500 may include at least one of a resin material and a metal material. For example, the lid 500 may have a main body portion containing a metal material and a covering portion containing a resin material that covers a portion of the main body portion. The covering portion may be a frame-shaped object made of resin, or an adhesive film that can be suitably bonded to both metal materials and resin materials. The main body is preferably joined to the exterior member 101 via a cover. In this modification, a terminal adhesive film 530 that adheres to both the electrode terminal 300 and the lid body 500 is preferably attached to a predetermined area including the portion of the electrode terminal 300 that is joined to the lid body 500. The specifications of the terminal adhesive film 530 are the same as those of the terminal adhesive film 30 described in the first embodiment. In this modification, the method for manufacturing the electricity storage device 10X may include the steps of electrically connecting the electrode body 200 and the electrode terminal 300, manufacturing the lid body 500, and inserting the electrode terminal 300, connected to the electrode body 200, into the hole 500C of the lid body 500 (see FIG. 24 , hereinafter referred to as the "insertion step").

[0191] When the lid body 500 is plate-shaped, it is preferable that the lid body 500 has a certain degree of thickness so that deformation of the exterior body 100X is suppressed even when the power storage device 10X is placed on top of it. From another perspective, when the lid body 500 is plate-shaped, it is preferable that the side surface of the lid body 500 has a certain degree of thickness so that the side surface of the lid body 500 and the exterior member 101X can be suitably heat-sealed when forming the second sealing portion 120X. The minimum thickness of the lid body 500 is, for example, 1.0 mm, more preferably 3 mm, and even more preferably 4 mm. The maximum thickness of the lid body 500 is, for example, 10 mm, more preferably 8.0 mm, and even more preferably 7.0 mm. The maximum thickness of the lid body 500 may be 10 mm or more. The preferred ranges for the thickness of the material constituting the lid body 500 are 1.0 mm to 10 mm, 1.0 mm to 8.0 mm, 1.0 mm to 7.0 mm, 3.0 mm to 10 mm, 3.0 mm to 8.0 mm, 3.0 mm to 7.0 mm, 4.0 mm to 10 mm, 4.0 mm to 8.0 mm, and 4.0 mm to 7.0 mm. In the present disclosure, when the lid body 500 is described as being plate-shaped, films defined by the JIS (Japanese Industrial Standards) "Packaging Terminology" standard are not included as materials constituting the lid body 500. The thickness of the lid body 500 may vary depending on the region of the lid body 500. When the thickness of the lid body 500 varies depending on the region, the thickness of the lid body 500 is the thickness of the thickest portion.

[0192] The lid 500 may be formed from a member divided into a first portion 510 and a second portion 520, and may be manufactured by joining the first portion 510 and the second portion 520 together so as to sandwich the electrode terminal 300 and the adhesive film for the terminal 530. In these modified examples, if a gap occurs between the adhesive film for the terminal 530 and the hole 530C, it is preferable that this gap be filled with a resin material such as hot melt or by resin welding.

[0193] When the lid body 500 is formed of a member divided into a first portion 510 and a second portion 520, the relationship between the width LA of the electrode terminal 300 and the width LB of the lid body 500 can be selected arbitrarily. From the viewpoint of more firmly bonding the electrode terminal 300 and the lid body 500, the ratio RA of the width LA to the width LB is preferably 50% or more. In the example shown in FIG. 25 , the widths LA and LB are substantially equal; in other words, the ratio RA is 100%. When the ratio RA is 50% or more, the area of ​​the electrode terminal 300 that is bonded to the lid body 500 is large, and therefore, by heating the electrode terminal 300, the electrode terminal 300 and the lid body 500 can be more firmly bonded. Note that in this modification, the width LC of the terminal adhesive film 530 is preferably substantially equal to the width LA of the electrode terminal 300.

[0194] The lid body 500 may be manufactured by insert molding the lid body 500 onto the electrode terminal 300 to which the terminal adhesive film 530 is attached. In this case, the manufacturing method of the electricity storage device 10X includes the steps of electrically connecting the electrode body 200 and the electrode terminal 300, and insert molding the lid body 500 onto the electrode terminal 300 connected to the electrode body 200 (hereinafter referred to as the "insert molding step"). After the insert molding step, the exterior member 101 is wrapped around the electrode body 200 and the lid body 500. Note that in the insert molding step, it is preferable to place a heat insulating material for protecting the electrode body 200 between the electrode body 200 and the portion where the lid body 500 is to be formed. It is preferable to remove the heat insulating material after the insert molding step.

[0195] In these modified examples, as shown in FIG. 26 , the exterior body 100X may have the second sealing portion 120X formed by bonding the exterior member 101 to the second surface 500B of the lid 500 with the lid 500 fitted. The bonding means between the exterior member 101 and the second surface 500B of the lid 500 is, for example, heat sealing. In this modified example, the exterior member 101 is bonded to a wider area of ​​the lid 500, thereby improving the sealing performance of the exterior body 100X. Alternatively, the lid may be formed by folding the adhesive film for terminals 530, and the second sealing portion 120X may be formed by bonding any portion of the adhesive film for terminals 530 to the exterior member 101X. In these modified examples, a barrier layer is preferably laminated on at least a portion of the surface of the lid 500. Alternatively, if the lid 500 has multiple layers, a barrier layer may be formed on any of the layers. The material constituting the barrier layer is, for example, aluminum, steel plate, or stainless steel.

[0196] FIG. 27 is a front view of a lid body 600, which is another modification of the lid body 400 in the second embodiment. The lid body 600 includes a metal portion 610, which is a portion where metal is exposed on the surface. The metal portion 610 is welded to the electrode 210 of the electrode body 200. The lid body 600 may be entirely formed of the metal portion 610, or the metal portion 610 may be partially formed. When the metal portion 610 is partially formed, the lid body 600 is formed of a multilayer material including a metal layer. When the lid body 600 is formed of a multilayer material with a metal layer as an intermediate layer, the metal portion 610 is a portion where layers other than the metal layer are partially removed so that the metal layer is exposed. In the example shown in FIG. 27, the metal portion 610 of the lid body 600 functions as an electrode terminal, so that space between the lid body 600 and the electrode 210 is not required. This allows the power storage device 10X (see FIG. 9) to be configured in a compact size.

[0197] FIG. 28 is a front view of a lid body 700 that is another modified example of the lid body 400 in the second embodiment. The lid body 700 includes a metal portion 710 made of a metal material and a non-metal portion 720 that is connected to the metal portion 710 and made of a resin material. The metal portion 710 is welded to the electrode 210 of the electrode assembly 200. In the example shown in FIG. 28, the metal portion 710 of the lid body 700 functions as an electrode terminal, so there is no need for space between the lid body 700 and the electrode 210. This allows the power storage device 10X (see FIG. 9) to be configured in a compact size.

[0198] <5-7> The electricity storage device 10X according to the second embodiment or a modified example of the second embodiment may include the film 20 described in the first embodiment. In the electricity storage device 10X, the location where the film 20 is disposed can be selected arbitrarily as long as it is located inside the barrier layer 101B (see FIG. 2) of the exterior member 101. By disposing the film 20 of the first aspect inside the barrier layer 101B of the exterior member 101, it is possible to prevent moisture from penetrating from the end of the heat-sealable resin layer 101C of the exterior member 101 and moisture contained in the heat-sealable resin layer 101C of the exterior member 101 from penetrating into the electrode assembly 200. That is, in the electricity storage device 10X including the film 20 of the first aspect, the film 20 contains a water absorbing agent, and therefore the film 20 can absorb and retain moisture that has penetrated from the heat-sealable resin layer 101C of the exterior member 101, thereby preventing moisture from reaching the electrode assembly 200. Furthermore, by disposing the film 20 of the second embodiment inside the barrier layer 101B of the exterior member 101, for example, when the electrode assembly 200 is an all-solid-state battery, it is possible to absorb gases such as hydrogen sulfide generated by contact between a solid electrolyte layer included in an element constituting the all-solid-state battery and water. That is, in the electricity storage device 10X including the film 20 of the second embodiment, the film 20 contains a gas absorbent, and therefore gases such as hydrogen sulfide generated from the electrode assembly 200 are absorbed by the film 20.

[0199] 29A is a cross-sectional view showing a modified example of the electricity storage device 10X of the second embodiment. In the example shown in FIG. 29A, the film 20 is disposed between the exterior member 101 and the electrode body 200 so as to cover substantially the entire upper and lower surfaces of the electrode body 200. The film 20 and the inner surface of the exterior member 101 (thermally adhesive resin layer 101C) may or may not be bonded together. At least a portion of the film 20 may be disposed between the exterior member 101 and the lid body 500.

[0200] FIG. 29B is a cross-sectional view showing another modified example of the electricity storage device 10X of the second embodiment. In the example shown in FIG. 29B, the film 20 is disposed between the lid body 500 and the electrode body 200 so as to cover substantially the entire side surface of the electrode body 200. The film 20 and the first surface 500A of the lid body 500 may or may not be bonded to each other. The film 20 and the first surface 500A of the lid body 500 may be in contact with each other or may be spaced apart. The film 20 may be disposed between the exterior member 101 and the electrode body 200 so as to cover substantially the entire electrode body 200. The film 20 and the inner surface (thermally adhesive resin layer 101C) of the exterior member 101 may or may not be bonded to each other.

[0201] FIG. 29C is a cross-sectional view showing another modified example of the electricity storage device 10X of the second embodiment. In the example shown in FIG. 29C, the electricity storage device 10X has a terminal adhesive film 530 that adheres to both metal and resin between the electrode terminal 300 and the lid body 500. In the example shown in FIG. 29C, a film 20 is used as the terminal adhesive film 530. The film 20 is preferably placed at least in the hole 500C of the lid body 500. The film 20 may be exposed from the hole 500C of the lid body 500. An electricity storage device 10X including the lid body 500 may be susceptible to moisture intrusion through the hole 500C of the lid body 500. In the electricity storage device 10X including the film 20 of the first aspect, the film 20 contains a water-absorbing agent, and therefore the film 20 absorbs and retains moisture that has infiltrated through the hole 500C of the lid body 500, thereby preventing the moisture from reaching the electrode body 200. In the electricity storage device 10X including the film 20 of the second embodiment, the film 20 contains a gas absorbent, and therefore gases such as hydrogen sulfide generated from the electrode body 200 are absorbed by the film 20. Therefore, gases such as hydrogen sulfide are less likely to be released to the outside through the holes 500C of the lid body 500.

[0202] 23 , when the lid body 500 is configured by a member divided into at least a first portion 510 and a second portion 520, the film 20 may be disposed at least partially between the first portion 510 and the second portion 520. Furthermore, for example, when the lid body 500 is configured by one part and the electrode terminal 300 is disposed between the top surface of the lid body 500 and the exterior member 101, the film 20 as the terminal adhesive film 530 may be disposed between the top surface of the lid body 500 and the exterior member 101.

[0203] <5-8> Furthermore, in the first embodiment, the second sealed portion 120 is formed by folding the exterior member 101 and heat-sealing the heat-sealable resin layers of the exterior member 101. However, the method of forming the second sealed portion 120 is not limited to this. FIG. 30 is a plan view schematically showing an electricity storage device 10 having a modified second sealed portion 120Y. The exterior member 101 has a protruding portion 101XA that extends outward from the exterior body 100, and the second sealed portion 120Y is formed by heat-sealing the heat-sealable resin layers of the protruding portion 101XA to each other. In the portion of the protruding portion 101XA where the electrode terminal 300 is disposed, the heat-sealable resin layer of the protruding portion 101XA and the electrode terminal 300 are heat-sealed. According to this modified example, the second sealed portion 120Y can be heat-sealed more firmly, thereby improving the hermeticity of the exterior body 100. In this modification, the protruding portion 101XA may be cut as necessary except for the portion heat-sealed to the electrode terminal 300. This modification can also be applied to the modification shown in FIG.

[0204] <5-9> In the first embodiment, the method for forming the first sealing portion 110 can be selected arbitrarily. As shown in FIG. 31 , for example, in step S110 (see FIG. 8 ), the manufacturing apparatus may form the first sealing portion 110 by pressing a seal bar 800 against a portion 110Y of the exterior body 100 where the first sealing portion 110 is to be formed, at a position away from a base 135X. According to this manufacturing method, as shown in FIG. 32 , a recess 110X is formed in the first sealing portion 110, which is a trace of the seal bar 800 being pressed against the portion. In the portion of the exterior body 100 where the recess 110X is formed, opposing surfaces (thermally adhesive resin layers) of the exterior member 101 are directly bonded to each other. Between the recess 110X and the base 135X of the exterior body 100, a polymer pool 900, where a portion of the resin constituting the exterior member 101 has melted, is formed between the opposing surfaces of the exterior member 101. In the portion of the exterior body 100 between the recess 110X and the base 135X, the facing surfaces (thermally adhesive resin layers) of the exterior member 101 are joined via a poly pool 900. That is, in this modification, the first sealing portion 110 includes a portion where the facing surfaces of the exterior member 101 are joined directly, and a portion where the facing surfaces of the exterior member 101 are joined via the poly pool 900. The poly pool 900 prevents water vapor and the like from entering the interior of the exterior body 100 from the outside, thereby improving the barrier properties of the exterior body 100. Note that when the seal bar 800 is pressed against the portion 110Y, it is necessary for the facing surfaces of the exterior member 101 in the portion where the poly pool 900 is formed, in other words, the portion between the recess 110X and the base 135X, to be in contact with each other.

[0205] The distance X between the base 135X and the edge 810 of the seal bar 800 in the LR direction, in other words, the distance between the base 135X and the recess 110X in the LR direction, can be selected arbitrarily. From the viewpoint of forming the polymer pool 900 over a wider area, the distance X is preferably, for example, 1 mm or more, more preferably 1.5 mm or more, and even more preferably 1.7 mm or more. From the viewpoint of forming the first sealing portion 110 compactly, the distance X is preferably, for example, 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less. Preferred ranges for the distance X include, for example, approximately 1 mm to 10 mm, approximately 1 mm to 5 mm, approximately 1 mm to 3 mm, approximately 1.5 mm to 10 mm, approximately 1.5 mm to 5 mm, approximately 1.5 mm to 3 mm, approximately 1.7 mm to 10 mm, approximately 1.7 mm to 5 mm, and approximately 1.7 mm to 3 mm. The distance X is most preferably, for example, 2 mm. Alternatively, the distance X may be substantially 0. When the distance X is substantially 0, the seal bar 800 is pressed against the exterior body 100 so that the base 135X and the edge 810 of the seal bar 800 substantially coincide with each other. Note that "substantially coincident" includes a case where the base 135X and the edge 810 of the seal bar 800 completely coincide with each other, and a case where the positions of the base 135X and the edge 810 of the seal bar 800 are slightly misaligned due to manufacturing errors or the like. Therefore, "the distance X is substantially 0" also includes a case where the distance X is less than 1 mm, for example. These modified examples can be similarly applied to the second to fourth embodiments. Note that depending on the shape of the portion of the recess 110X corresponding to the edge 810 of the seal bar 800, the distance between the base 135X and the recess 110X may not be constant. In such a case, the distance X may be the distance between the center of the recess 110X and the center of the base 135X in the FB direction. In another example, distance X may be calculated based on the average value of multiple values ​​including the maximum and minimum values ​​of the distance between base 135X and recess 110X. Similarly, depending on the shape of base 135X, the distance between base 135X and recess 110X may not be constant. In such cases, distance X may be the distance between the center of base 135X and the center of recess 110X in the FB direction.In another example, the distance X may be calculated based on the average value of a plurality of values ​​including the maximum and minimum values ​​of the distance between the recess 110X and the base 135X.

[0206] In the second embodiment, as shown in FIG. 33, the exterior housing 100X may include a barrier film 91 that suppresses permeation of the electrolyte solution. The barrier film 91 is preferably disposed at least between the inner surface of the exterior housing member 101X and the electrode assembly 200. The barrier film 91 is preferably bonded to the inner surface of the exterior housing member 101X. The barrier film 91 is preferably made of a material that allows permeation of gas generated inside the exterior housing 100X. The material that constitutes the barrier film 91 is, for example, a resin film or a porous film. Because the exterior housing 100X includes the barrier film 91, deterioration of the exterior housing member 101X due to the electrolyte solution can be suppressed.

[0207] In the first embodiment, as shown in FIG. 34 , the exterior housing 100 may include a buffer film 92 for increasing the strength of the exterior housing member 101. The buffer film 92 is preferably disposed on the inner surface of the exterior housing member 101, at least at a corner 100Z of the exterior housing 100. Because the exterior housing 100 includes the buffer film 92, the occurrence of pinholes in the exterior housing 100 can be suppressed. Examples of materials that make up the buffer film 92 include polyester-based materials, polyolefin-based materials, and fluorine-based materials. In this modification, as shown in FIG. 34 , the second sealing portion 120 may be formed by joining the inner surface of the exterior housing member 101 and the electrode terminal 300. A space 93 between the second sealing portion 120 and the electrode assembly 200 is preferably filled with an electrolyte.

[0208] In the first embodiment, it has been explained that a terminal adhesive film 30 that adheres to both metal and resin may be arranged between the electrode terminal 300 and the exterior member 101, but in other embodiments, a terminal adhesive film 30 may also be arranged in a similar manner.

[0209] In the second embodiment, it has been explained that an adhesive film for terminals 30 that adheres to both metal and resin, similar to that in the first embodiment, may be arranged between the lid body 400 and the electrode terminal 300, but an adhesive film may also be arranged in a similar manner in other embodiments.

[0210] 6. Working Example The inventors of the present application manufactured electricity storage devices of Examples 1 and 2 and Comparative Example 1, and conducted tests to confirm whether moisture penetrated into the electrode body. Note that, for the sake of convenience of explanation, in the following, among the elements constituting the electricity storage devices of Examples 1 and 2 and Comparative Example 1, elements that are the same as those in the embodiment may be described using the same reference numerals as those in the embodiment.

[0211] The power storage devices of Examples 1 and 2 and Comparative Example 1 have a configuration similar to that of the power storage device 10X of the second embodiment. The power storage devices of Examples 1 and 2 and Comparative Example 1 include two lid bodies 500 (see FIG. 23). However, in the power storage devices of Examples 1 and 2 and Comparative Example 1, the two lid bodies 500 are not divided into a first portion 510 and a second portion 520. The size of the two lid bodies 500 is 100 mm in width, 30 mm in height, and 5 mm in thickness. The power storage devices of Examples 1 and 2 and Comparative Example 1 include an aluminum block instead of the electrode body 200. The size of the aluminum block is 100 mm in width, 30 mm in height, and 150 mm in thickness.

[0212] The inventors of the present application bonded the film 20 of the first embodiment to the first surfaces 500A of two lid bodies 500. Each film 20 had a width of 100 mm and a height of 30 mm. The films 20 were used after being left to dry in a vacuum oven (-50 MPa) for 24 hours before testing (before sealing). In the electricity storage device of Example 1, three films 20 were bonded to each of the first surfaces 500A of the two lid bodies 500 in a stacked manner. In the electricity storage device of Example 2, six films 20 were bonded to each of the first surfaces 500A of the two lid bodies 500 in a stacked manner. In the electricity storage devices of Examples 1 and 2, the films 20 cover substantially the entire first surfaces 500A of the lid bodies 500. In the electricity storage device of Comparative Example 1, the films 20 are not bonded to the lid bodies 500.

[0213] The inventors of the present application wrapped an exterior member 101 around two lid bodies 500, each having an aluminum block and a film 20 bonded thereto, to form a first sealed portion 110. The exterior member 101 was rectangular, measuring 300 mm x 160 mm. The heat sealing conditions for forming the first sealed portion 110 were a temperature of 190°C, a pressure of 1 MPa, and a time of 3 seconds.

[0214] Next, the inventors formed the second sealed portion 120 by heat-sealing the side surfaces (total of eight sides) of the two lids 500 to the exterior member 101. The heat-sealing conditions for forming the second sealed portion 120 were a temperature of 180°C, a pressure of 0.2 MPa, and a time of 5 seconds.

[0215] Next, the inventors cut the electricity storage devices of Examples 1 and 2 and Comparative Example 1 in half at a position 80 mm from the end of the lid 500 to form an opening, and then removed the aluminum block through the opening. Then, 20 g of salt-free electrolyte (EC:DMC:DEC=1:1:1) was poured through the opening, and the heat-sealable resin layers 101C present in the opening were strongly heat-sealed twice with a 7 mm wide seal bar to close the opening. The second strong heat-seal was performed so that it overlapped the first strong heat-sealed portion by 4 mm. Therefore, the seal width of the opening was 10 mm. The heat-sealing conditions for strongly heat-sealing the heat-sealable resin layers 101C present in the opening were a temperature of 220°C, a pressure of 0.45 MPa, and a time of 3 seconds.

[0216] The electricity storage devices of Examples 1 and 2 and Comparative Example 1 were left in a thermostatic chamber at a temperature of 65°C and a humidity of 90% for one week, and then the exterior member 101 was opened at an arbitrary location, and the moisture content of the salt-free electrolyte inside was measured by the Karl Fischer method. The Karl Fischer moisture meter used in this test was a Karl Fischer moisture meter MKC-610 manufactured by Kyoto Electronics Manufacturing Co., Ltd. The anolyte used was Chem-Aqua anolyte AGE, and the catholyte used was Chem-Aqua catholyte CGE. For the electricity storage devices of Examples 1 and 2 and Comparative Example 1, the moisture content of the salt-free electrolyte after the test was measured three times using 1 g of sample, and the average of the three measurements was used as the measurement result. Note that 1 g of sample includes an error of approximately 0.95 g to 1.05 g.

[0217] In the electricity storage device of Example 1, the water content of the salt-free electrolyte after the test, minus the water content of the salt-free electrolyte before the test, was 3 mg. In the electricity storage device of Example 2, the water content of the salt-free electrolyte after the test, minus the water content of the salt-free electrolyte before the test, was 1.5 mg. In the electricity storage device of Comparative Example 1, the water content of the salt-free electrolyte after the test, minus the water content of the salt-free electrolyte before the test, was 25 mg.

[0218] It was confirmed that the moisture content of the electrolyte solution in the electricity storage devices of Examples 1 and 2 increased only slightly compared to the moisture content of the electrolyte solution before the test. From this result, it is considered that the electricity storage device including the film 20 of the first aspect can suppress the penetration of moisture from the end of the heat-sealable resin layer 101C of the exterior member 101 and the penetration of moisture contained in the heat-sealable resin layer 101C of the exterior member 101 into the electrode body 200.

[0219] [7. Additional Notes] The first aspect of the film 20 of each of the above embodiments includes the following features.

[0220] Item 1A. A resin film for an electricity storage device that is disposed inside a barrier layer of an exterior member of an electricity storage device, the resin film for an electricity storage device containing a water absorbing agent. Item 2A: The resin film for a storage battery device according to Item 1A, wherein the water-absorbing agent is an inorganic water-absorbing agent. Item 3A. The resin film for a storage battery device according to Item 1A or 2A, wherein the water-absorbing agent is at least one selected from the group consisting of calcium oxide, anhydrous magnesium sulfate, magnesium oxide, calcium chloride, zeolite, aluminum oxide, silica gel, alumina gel, and calcined alum. Item 4A: The resin film for an electricity storage device according to any one of Items 1A to 3A, wherein the content of the water absorbing agent is 0.1 parts by mass or more per 100 parts by mass of the resin contained in the resin film for an electricity storage device. Item 5A: The resin film for an electricity storage device according to any one of Items 1A to 4A, which is composed of two or more layers. Item 6A. The resin film for a storage battery device according to Item 5A, wherein at least one of the two or more layers contains the water-absorbing agent and at least one layer contains a sulfur-based gas absorbent. Item 7A: The resin film for a storage battery device according to any one of Items 1A to 6A, wherein the layer containing the water-absorbing agent of the resin film for a storage battery device contains 0.5 mass parts or more of the absorbent per 100 mass parts of resin. Item 8A: The resin film for an electricity storage device according to any one of Items 1A to 7A, which contains a heat-sealable resin. Item 9A: The resin film for a storage battery device according to Item 8A, wherein the heat-sealable resin includes at least one selected from the group consisting of polyesters and polyolefins.

[0221] A second aspect of the film 20 of each of the above embodiments includes the following. Item 1B. A resin film for an electricity storage device that is disposed inside a barrier layer of an exterior member of an electricity storage device, the resin film for an electricity storage device containing a sulfur-based gas absorbent. Item 2B: The resin film for an electricity storage device according to Item 1B, wherein the content of the sulfur-based gas absorbent is 0.1 parts by mass or more per 100 parts by mass of the resin contained in the resin film for an electricity storage device. Item 3B: The resin film for a storage battery device according to Item 1B or 2B, wherein the sulfur-based gas absorbent has a maximum particle size of 20 μm or less and a number average particle size of 0.1 μm or more and 15 μm or less. Item 4B: The resin film for an electricity storage device according to any one of Items 1B to 3B, wherein the sulfur-based gas absorbent includes at least one selected from the group consisting of a sulfur-based gas chemical absorbent and a sulfur-based gas physical absorbent. Item 5B: The resin film for a storage battery device according to Item 4B, wherein the sulfur-containing gas physical absorbent includes at least one selected from the group consisting of hydrophobic zeolite having an SiO2 / Al2O3 molar ratio of 1 / 1 to 2000 / 1, bentonite, and sepiolite. Item 6B: The resin film for a storage battery device according to Item 4B or 5B, wherein the sulfur-based gas chemical absorbent is a metal oxide or an inorganic material carrying or containing a metal or metal ions. Item 7B: The resin film for a storage battery device according to Item 6B, wherein the metal oxide includes at least one selected from the group consisting of CuO, ZnO, and AgO. Item 8B: The resin film for a storage battery device according to Item 6B or 7B, wherein the metal species in the inorganic material carrying or incorporating a metal or metal ion is at least one selected from the group consisting of Ca, Mg, Na, Cu, Zn, Ag, Pt, Au, Fe, Al, and Ni. Item 9B: The resin film for a storage battery device according to any one of Items 1B to 8B, wherein the layer containing the sulfur-based gas absorbent of the resin film for a storage battery device contains 5 mass parts of the sulfur-based gas absorbent or more per 100 mass parts of resin. Item 10B: The resin film for an electricity storage device according to any one of Items 1B to 9B, which contains a heat-sealable resin. Item 11B: The resin film for a storage battery device according to Item 10B, wherein the heat-sealable resin includes at least one selected from the group consisting of polyesters and polyolefins. [Explanation of symbols]

[0222] 10, 10X, 10XA, 10Y, 10Z Energy Storage Device 20 Resin films for energy storage devices 30 Adhesive film for terminals 100, 100X, 100Y exterior body 101, 101Y, 101Z1, 101Z2 exterior materials 101A Base material layer 101B Barrier layer 101C Heat-fusible resin layer 101Z laminate 101X Overhang 110,110Z,154 1st sealing part 110X recess 120,120X,120Y 2nd sealing part 130,130Z Page 1 135,135Z Side 1 35X Base 140,140Z 2nd side 150 One side 151 Joint area 152 Space 153 Unjoined area 200 Electrode body 210 electrode 215 Current collector 300 electrode terminal 500A Page 1 500B 2nd side 400,500,700 Lid 610,710 Metal parts 800 Seal Bar C1 corner.

Claims

1. An electrode body; an electrode terminal connected to the electrode body; an exterior body that seals the electrode body, the exterior body is made of a film-like exterior member, The outer casing is a first sealing portion formed by joining the exterior member to the electrode body while the exterior member is encased therein; a cover body to which the electrode terminal is attached and which is entirely disposed to the side of the electrode body, a portion of the lid body is joined to the exterior member, the exterior member includes a barrier layer, the electricity storage device has a resin film for an electricity storage device that is disposed at least partially inside the barrier layer, the resin film for an electricity storage device contains at least one of a water absorbing agent and a gas absorbing agent, the lid body includes a first surface facing a side surface of the electrode body and a second surface opposite to the first surface, The resin film for an electricity storage device is bonded to at least a part of the second surface of the lid. Energy storage device.

2. The material constituting the lid includes at least one of a resin material and a metal material. The electricity storage device according to claim 1 .

3. The resin film for an electricity storage device is disposed at least partially between the lid and the electrode body. The electricity storage device according to claim 1 or 2.

4. The resin film for an electricity storage device is disposed at least partially between the lid and the electrode terminal. The electricity storage device according to claim 1 or 2.

Images