Cover, energy storage device, peripheral member

Abstract

Provided is a lid used with a casing of a power storage device, wherein the lid includes a heat-fusible resin layer the main material of which is an olefin-based copolymer.

Description

[Technical field]

[0001] The present invention relates to a lid, an electricity storage device, and a peripheral member. [Background technology]

[0002] Patent Document 1 discloses an example of an electricity storage device. This electricity storage device includes an electrode assembly and an exterior body that seals the electrode assembly. The exterior body includes an exterior film that encases the electrode assembly and a lid that is joined to the exterior film. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-123686 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned electricity storage device, if the exterior film and the lid are not sufficiently joined, a gap may be formed between the outer film and the lid, leaving room for improvement in terms of adequately sealing the electrode assembly with the exterior.

[0005] An object of the present invention is to provide an electricity storage device in which an electrode assembly can be suitably sealed with an exterior body, a lid body used in this electricity storage device, and a peripheral member constituting this lid body. [Means for solving the problem]

[0006] A lid according to a first aspect of the present invention is a lid used for an exterior body of an electricity storage device, the lid including a heat-sealable resin layer whose main material is an olefin-based copolymer.

[0007] A lid body according to a second aspect of the present invention is a lid body used as an exterior body for an electricity storage device, the lid body including a lid main body and a peripheral member joined to at least a portion of the peripheral edge of the lid main body, the peripheral member including a heat-sealable resin layer whose main material is an olefin-based copolymer.

[0008] A lid body according to a third aspect of the present invention is the lid body according to the second aspect, wherein the peripheral member is an adhesive film bonded to the lid body.

[0009] A lid body according to a fourth aspect of the present invention is the lid body according to the second aspect, wherein the peripheral member is a frame body joined to the lid main body.

[0010] A lid according to a fifth aspect of the present invention is the lid according to any one of the first to third aspects, wherein the olefin-based copolymer is an olefin-based random copolymer.

[0011] A lid body according to a sixth aspect of the present invention is a lid body according to any one of the first to fifth aspects, the lid body comprising a lid seal portion that is sealed to an exterior film that constitutes the exterior body, and a protrusion that protrudes from the lid seal portion.

[0012] A lid according to a seventh aspect of the present invention is the lid according to any one of the first to sixth aspects, wherein the heat-fusible resin layer contains a fatty acid amide-based lubricant.

[0013] A lid according to an eighth aspect of the present invention is the lid according to the seventh aspect, wherein there are multiple types of fatty acid amide-based lubricants, and at least one of the fatty acid amide-based lubricants is a saturated fatty acid amide.

[0014] A lid according to a ninth aspect of the present invention is the lid according to the eighth aspect, wherein the plurality of types of fatty acid amide-based lubricants further include an unsaturated fatty acid amide.

[0015] A cap according to a tenth aspect of the present invention is the cap according to the eighth or ninth aspect, wherein the saturated fatty acid amide has 18 or more carbon atoms.

[0016] A lid according to an eleventh aspect of the present invention is the lid according to any one of the eighth to tenth aspects, wherein the saturated fatty acid amide is behenic acid amide.

[0017] A lid according to a twelfth aspect of the present invention is the lid according to the ninth aspect, wherein the unsaturated fatty acid amide is erucic acid amide.

[0018] A lid body according to a thirteenth aspect of the present invention is a lid body according to any one of the first to fourth aspects, wherein the heat-sealable resin layer is composed of any one of an acid-modified polyolefin resin, an unsaturated carboxylic acid grafted polyolefin resin, a polypropylene resin, a metal ion cross-linked polyethylene, a copolymer resin of ethylene and an acrylic acid derivative, and an ethylene and a methacrylic acid derivative.

[0019] A lid according to a fourteenth aspect of the present invention is the lid according to any one of the first to fourth aspects, wherein the heat-fusible resin layer contains a propylene-based elastomer resin having a melting point of 150°C or higher.

[0020] The electricity storage device according to a fifteenth aspect of the present invention comprises an electrode body and an exterior body that seals the electrode body, the exterior body including an exterior film that wraps the electrode body and a lid body that is joined to the exterior film, and the lid body includes a heat-sealable resin layer whose main material is an olefin-based copolymer.

[0021] The electricity storage device according to a sixteenth aspect of the present invention comprises an electrode body and an exterior body that seals the electrode body, the exterior body including an exterior film that wraps the electrode body and a lid body that is joined to the exterior film, the lid body including a lid main body and a peripheral member that is joined to at least a portion of the peripheral edge of the lid main body, and the peripheral member includes a heat-sealable resin layer whose main material is an olefin-based copolymer.

[0022] A peripheral member according to a seventeenth aspect of the present invention is a peripheral member constituting a lid body used in an outer casing of an electricity storage device, the lid body including a lid main body and the peripheral member joined to at least a portion of the peripheral edge of the lid main body, and the peripheral member including a heat-sealable resin layer whose main material is an olefin-based copolymer.

[0023] A peripheral member according to an eighteenth aspect of the present invention is the peripheral member according to the seventeenth aspect, which is an adhesive film bonded to the lid main body.

[0024] A peripheral member according to a nineteenth aspect of the present invention is the peripheral member according to the seventeenth aspect, which is a frame body joined to the lid main body.

[0025] A lid according to a twentieth aspect of the present invention is a lid used for an exterior body of an electric storage device, and includes a heat-sealable resin layer, and the heat-sealable resin layer is measured by the following method for measuring a temperature difference T1 and a temperature difference T2, and a value obtained by dividing the temperature difference T2 by the temperature difference T1 is 0.60 or more. A temperature difference T1 between an extrapolated melting start temperature and an extrapolated melting end temperature of a melting peak temperature of the heat-sealable resin layer is measured by differential scanning calorimetry. In an environment of a temperature of 85°C, the heat-sealable resin layer is left to stand for 72 hours in an electrolyte solution that is a solution having a lithium hexafluorophosphate concentration of 1 mol / l and a volume ratio of ethylene carbonate, diethyl carbonate, and dimethyl carbonate of 1:1:1, and then dried. A temperature difference T2 between an extrapolated melting start temperature and an extrapolated melting end temperature of a melting peak temperature of the heat-sealable resin layer after drying is measured by differential scanning calorimetry.

[0026] A lid according to a twenty-first aspect of the present invention is a lid used for an exterior body of an electricity storage device, the lid including a heat-sealable resin layer, the lid having a lid seal portion that is sealed to an exterior film that constitutes the exterior body, a sea-island structure is observed in a cross-sectional image of a thickness-wise cross section of the lid seal portion obtained using a field emission scanning electron microscope, and in the cross-sectional image, the area ratio of the island portions of the sea-island structure is 0.1% or more and 50% or less.

[0027] A peripheral member according to a twenty-second aspect of the present invention is a peripheral member constituting a lid used for an exterior body of an electricity storage device, the lid includes a lid body and the peripheral member joined to at least a part of the peripheral portion of the lid body, and the peripheral member includes a heat-sealable resin layer. The heat-sealable resin layer is measured by the following method for measuring a temperature difference T1 and a temperature difference T2, and a value obtained by dividing the temperature difference T2 by the temperature difference T1 is 0.60 or more. The temperature difference T1 between the extrapolated melting start temperature and the extrapolated melting end temperature of the melting peak temperature of the heat-sealable resin layer is measured by differential scanning calorimetry. In an environment of a temperature of 85°C, the heat-sealable resin layer is left to stand for 72 hours in an electrolyte solution that is a solution having a lithium hexafluorophosphate concentration of 1 mol / l and a volume ratio of ethylene carbonate, diethyl carbonate, and dimethyl carbonate of 1:1:1, and then dried. The temperature difference T2 between the extrapolated melting start temperature and the extrapolated melting end temperature of the melting peak temperature of the heat-fusible resin layer after drying is measured by differential scanning calorimetry.

[0028] A peripheral member according to a twenty-third aspect of the present invention is a peripheral member constituting a lid used in an outer casing of an electricity storage device, the lid including a lid main body and the peripheral member joined to at least a portion of the peripheral portion of the lid main body, the peripheral member having a peripheral member seal portion that is sealed to an outer casing film that constitutes the outer casing, a sea-island structure is observed in a cross-sectional image obtained using a field emission scanning electron microscope for a cross-section in the thickness direction of the peripheral member seal portion, and in the cross-sectional image, the area ratio of the island portions of the sea-island structure is 0.1% or more and 50% or less. Effect of the Invention

[0029] The electricity storage device, the lid, and the peripheral member according to the present invention can contribute to suitably sealing the electrode assembly with the exterior body. [Brief description of the drawings]

[0030] [Figure 1A] FIG. 1 is a perspective view of an electricity storage device according to an embodiment. [Figure 1B]1B is a diagram showing a method for measuring the seal strength of a second sealing portion of the electricity storage device in FIG. 1A. [Diagram 2] 1B is a cross-sectional view showing a layer structure of an exterior film included in the electricity storage device of FIG. 1A. [Diagram 3] FIG. 1B is a diagram showing the state in which the exterior film of the power storage device of FIG. 1A is unfolded. [Figure 4] 1B is a cross-sectional view taken along line D4-D4 in FIG. 1A. [Diagram 5] FIG. 5 is a side view of the lid body with the exterior film of FIG. 4 omitted. [Figure 6] FIG. 5 is a plan view of the lid body with the exterior film of FIG. 4 omitted. [Figure 7] 1B is a flowchart showing an example of a manufacturing process for the electricity storage device in FIG. 1A. [Figure 8] FIG. 11 is a cross-sectional view of a lid provided in an electricity accumulation device according to a second modified example. [Figure 9] FIG. 13 is a cross-sectional view of a lid provided in an electricity accumulation device according to a third modified example. [Figure 10] FIG. 13 is a cross-sectional view of a lid provided in an electricity accumulation device according to a fourth modified example. [Figure 11] 11 is a cross-sectional view showing an example of a layer structure of the peripheral member of FIG. 10. [Figure 12] FIG. 23 is a cross-sectional view of a lid provided in an electricity accumulation device according to a tenth modified example. [Figure 13] FIG. 23 is a cross-sectional view of a lid provided in another electricity storage device according to a tenth modified example. [Figure 14] FIG. 23 is a cross-sectional view showing an example of a layer structure of a peripheral member included in still another electricity accumulation device according to a tenth modified example. [Figure 15] FIG. 23 is a cross-sectional view showing an example of a layer structure of a peripheral member included in an electricity accumulation device according to an eleventh modified example. [Figure 16] FIG. 23 is a cross-sectional view of a lid provided in an electricity accumulation device according to a twelfth modified example. [Figure 17] FIG. 23 is a cross-sectional view of an electricity accumulation device 10 according to a fourteenth modification. [Figure 18] FIG. 18 is a cross-sectional view of the lid and its surroundings in FIG. 17 . [Figure 19] FIG. 18 is a cross-sectional view showing an example of a layer structure of the barrier film in FIG. [Figure 20]FIG. 18 is a cross-sectional view showing another example of the layer structure of the barrier film in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Hereinafter, an electricity storage device according to one embodiment of the present invention will be described with reference to the drawings. In this specification, a numerical range indicated by "to" means "not less than" or "not more than." For example, the expression "2 to 15 mm" means 2 mm or more and 15 mm or less.

[0032] [Embodiment] <1-1. Configuration of the power storage device> FIG. 1A is a plan view that shows a schematic diagram of an electricity storage device 10 of a first embodiment. FIG. 1B is a diagram that shows a method for measuring the seal strength of the second sealing portion 80 of the electricity storage device 10 of FIG. 1A. FIG. 2 is a cross-sectional view that shows a layer structure of an exterior film 50 that is included in the electricity storage device 10 of FIG. 1A. FIG. 3 is a diagram that shows the exterior film 50 that is included in the electricity storage device 10 of FIG. 1A in an unfolded state. FIG. 4 is a cross-sectional view along the line D4-D4 in FIG. 1A. FIG. 5 is a side view of a lid body 60 that is included in the electricity storage device 10 of FIG. 1A. FIG. 6 is a plan view of the lid body 60 of FIG. 5. In FIG. 1A, FIGS. 4 to 6, FIG. 8, and FIG. 9, the direction of the arrow UD indicates the thickness direction of the electricity storage device 10, the direction of the arrow LR indicates the width direction of the electricity storage device 10, and the direction of the arrow FB indicates the depth direction of the electricity storage device 10. The directions shown by the arrows UDLRFB are common to the following figures.

[0033] The power storage device 10 includes an electrode body 20, an electrode terminal 30, and an exterior body 40. The electrode body 20 includes electrodes (positive and negative electrodes) constituting a power storage member such as a lithium ion battery, a capacitor, an all-solid-state battery, a semi-solid battery, a quasi-solid battery, a polymer battery, an all-resin battery, a lead-acid battery, a nickel-metal hydride battery, a nickel-cadmium battery, a nickel-iron battery, a nickel-zinc battery, a silver oxide-zinc battery, a metal-air battery, a polyvalent cation battery, or a capacitor, and a separator. In this embodiment, the shape of the electrode body 20 is an approximately rectangular parallelepiped. Note that the term "approximately rectangular parallelepiped" includes, in addition to a complete rectangular parallelepiped, a solid body that can be regarded as a rectangular parallelepiped by modifying the shape of a part of the outer surface, for example. The shape of the electrode body 20 may be, for example, a cylinder or a polygonal prism.

[0034] In this embodiment, the power storage device 10 includes two electrode terminals 30. The electrode terminals 30 are metal terminals used for inputting and outputting electric power in the electrode body 20. One end of the electrode terminal 30 is electrically connected to an electrode (positive electrode or negative electrode) included in the electrode body 20. The other end of the electrode terminal 30 protrudes outward from an edge of the exterior body 40, for example. Note that the electrode terminal 30 may not protrude from the exterior body 40, for example, as long as it is capable of inputting and outputting electric power to and from the electrode body 20. When the cover body 60 described later is made of, for example, a metal, the cover body 60 may also function as the electrode terminal 30. In this case, the cover body 60 having the function as an electrode terminal may or may not protrude from the exterior body 40.

[0035] The metal material constituting the electrode terminal 30 is, for example, aluminum, nickel, copper, etc. For example, when the electrode body 20 is a lithium ion battery, the electrode terminal 30 connected to the positive electrode is usually made of aluminum, etc., and the electrode terminal 30 connected to the negative electrode is usually made of copper, nickel, etc. The outermost layer of the electrode body 20 does not necessarily have to be an electrode, and may be, for example, a protective tape or a separator.

[0036] The exterior body 40 seals the electrode body 20. The exterior body 40 includes an exterior film 50 and a lid body 60. The exterior film 50 wraps the electrode body 20 so as to have an opening 40A. In this embodiment, the exterior film 50 is wrapped around the electrode body 20 so as to have an opening 40A. The lid body 60 is disposed on the side of the electrode body 20 so as to close the opening 40A. Note that the electrode body 20 may be housed inside the exterior film 50 configured in a cylindrical shape so as to form the opening 40A, and the opening 40A may be closed by the lid body 60.

[0037] For example, there is a method of forming a storage portion (recess) for storing the electrode body 20 in the exterior film 50 through cold forming. However, it is not necessarily easy to form a deep storage portion by such a method. If an attempt is made to form a deep storage portion (recess) by cold forming (for example, a forming depth of 15 mm), pinholes or cracks will occur in the exterior film 50, which is likely to cause a decrease in battery performance. On the other hand, the exterior body 40 seals the electrode body 20 by wrapping the exterior film 50 around the electrode body 20, so that the electrode body 20 can be easily sealed regardless of the thickness of the electrode body 20. In addition, in order to reduce the dead space between the electrode body 20 and the exterior film 50 to improve the volumetric energy density of the power storage device 10, it is preferable that the exterior film 50 is wrapped so as to contact the outer surface of the electrode body 20. In addition, in an all-solid-state battery, it is necessary to apply a high pressure uniformly from the outer surface of the battery to exhibit battery performance, so it is necessary to eliminate the space between the electrode body 20 and the exterior film 50, and therefore it is preferable that the exterior film 50 is wrapped so as to contact the outer surface of the electrode body 20.

[0038] As shown in FIG. 2, the exterior film 50 is a laminate (laminate film) having, for example, a base layer 51, a barrier layer 52, and a heat-sealable resin layer 53 in this order. The exterior film 50 does not need to include all of these layers, and may not include, for example, the barrier layer 52. That is, the exterior film 50 may be made of a material that is flexible and easy to bend, and may be made of, for example, a resin film. The exterior film 50 is preferably heat-sealable. The innermost layer and the outermost layer of the exterior film 50 may be the heat-sealable resin layer 53. In this case, the exterior film 50 may wrap the electrode body 20 and the lid body 60 by joining the outermost layer and the innermost layer.

[0039] The base layer 51 included in the exterior film 50 is a layer for imparting heat resistance to the exterior film 50 and suppressing the occurrence of pinholes that may occur during processing or distribution. The base layer 51 is configured to include at least one layer of a stretched polyester resin layer and a stretched polyamide resin layer. For example, the base layer 51 includes at least one layer of a stretched polyester resin layer and a stretched polyamide resin layer, so that the barrier layer 52 can be protected during processing of the exterior film 50 and breakage of the exterior film 50 can be suppressed. In addition, from the viewpoint of increasing the tensile elongation of the exterior film 50, 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, in terms 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 51 may be configured to include both a stretched polyester resin layer and a stretched polyamide resin layer. The thickness of the base layer 51 is, for example, preferably 5 to 300 μm, and more preferably 5 to 150 μm, from the viewpoint of film strength.

[0040] The barrier layer 52 is a layer that at least prevents the intrusion of moisture. The barrier layer 52 is bonded to the base layer 51 via, for example, an adhesive layer 54. Examples of the barrier layer 52 include metal foil, vapor deposition film, and resin layer having barrier properties. Examples of the vapor deposition film include metal vapor deposition film, inorganic oxide vapor deposition film, and carbon-containing inorganic oxide vapor deposition film, and examples of the resin layer include fluorine-containing resins such as polyvinylidene chloride, polymers mainly composed of chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers mainly composed of fluoroalkyl units, and ethylene-vinyl alcohol copolymers. Examples of the barrier layer 52 include resin films having at least one of these vapor deposition films and resin layers. The barrier layer 52 may be provided in a plurality of layers. It is preferable that the barrier layer 52 includes a layer made of a metal material. Specific examples of the metal material constituting the barrier layer 52 include aluminum alloys, stainless steel, titanium steel, and steel plates. When used as a metal foil, it is preferable that the material contains at least one of an aluminum alloy foil and a stainless steel foil.

[0041] In the barrier layer 52, the layer made of the above-mentioned metal material may contain recycled metal material. Examples of recycled metal material include recycled aluminum alloy, stainless steel, titanium steel, or steel plate. These recycled materials can be obtained by known methods. The recycled aluminum alloy material can be obtained by the manufacturing method described in International Publication No. 2022 / 092231. The barrier layer 52 may be made of only recycled materials, or may be made of a mixed material of recycled materials and virgin materials. Note that recycled metal materials refer to metal materials that have been made reusable by collecting, isolating, and refining various products used in the city and waste from the manufacturing process. In addition, virgin metal materials refer to new metal materials refined from natural metal resources (raw materials) and are not recycled materials.

[0042] From the viewpoint of improving the formability or conformability of the exterior film 50, the aluminum alloy foil is preferably a soft aluminum alloy foil made of, for example, an annealed aluminum alloy, and from the viewpoint of further improving the formability or conformability, the aluminum alloy foil is preferably an iron-containing aluminum alloy foil. In the iron-containing aluminum alloy foil (100 mass%), the iron content is preferably 0.1 to 9.0 mass%, more preferably 0.5 to 2.0 mass%. By making the iron content 0.1 mass% or more, an exterior film 50 having better formability can be obtained. By making the iron content 9.0 mass% or less, an exterior film 50 having better flexibility can be obtained. In addition, silicon, magnesium, copper, manganese, etc. may be added as necessary. In addition, softening can be performed by annealing treatment, etc. From the viewpoint of improving the mechanical strength of the exterior film 50, the aluminum alloy foil is more preferably a hard aluminum alloy foil made of, for example, a work-hardened aluminum alloy.

[0043] Examples of the stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation hardened stainless steel foils. From the viewpoint of providing an exterior film 50 with excellent formability, the stainless steel foil is preferably made of austenitic stainless steel.

[0044] Specific examples of the austenitic stainless steel constituting the stainless steel foil include SUS304, SUS301, and SUS316L, and among these, SUS304 is particularly preferred.

[0045] In the case of a metal foil, the thickness of the barrier layer 52 should be such that it at least functions as a barrier layer to prevent the intrusion of moisture, and may be, for example, about 5 to 200 μm. The thickness of the barrier layer 52 is preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, and particularly preferably about 35 μm or less. The thickness of the barrier layer 52 is preferably about 9.0 μm or more, more preferably about 20 μm or more, and more preferably about 25 μm or more. Preferable ranges for the thickness of the barrier layer 52 include about 9.0 to 85 μm, about 9.0 to 50 μm, about 9.0 to 40 μm, about 9.0 to 35 μm, about 20 to 85 μm, about 20 to 50 μm, about 20 to 40 μm, about 20 to 35 μm, about 25 to 85 μm, about 25 to 50 μm, about 25 to 40 μm, and about 25 to 35 μm. When the barrier layer 52 is made of an aluminum alloy foil, the above-mentioned ranges are particularly preferable. From the viewpoint of imparting high formability and high rigidity to the exterior film 50, the thickness of the barrier layer 52 is preferably about 35 μm or more, more preferably about 45 μm or more, even more preferably about 50 μm or more, and even more preferably about 55 μm or more, and is preferably about 200 μm or less, more preferably about 85 μm or less, even more preferably about 75 μm or less, and even more preferably about 70 μm or less. Preferable ranges are about 35 to 200 μm, about 35 to 85 μm, about 35 to 75 μm, about 35 to 70 μm, about 45 to 200 μm, about 45 to 85 μm, about 45 to 75 μm, about 45 to 70 μm, about 50 to 200 μm, about 50 to 85 μm, about 50 to 75 μm, about 50 to 70 μm, about 55 to 200 μm, about 55 to 85 μm, about 55 to 75 μm, and about 55 to 70 μm. When the exterior film 50 has high formability, deep drawing becomes easy, which can contribute to increasing the capacity of the electricity storage device. Furthermore, when the capacity of the electricity storage device is increased, the weight of the electricity storage device increases, but the rigidity of the exterior film 50 is increased, which can contribute to high sealing performance of the electricity storage device.In particular, when the barrier layer 52 is made of stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, even more preferably about 30 μm or less, and particularly preferably about 25 μm or less. The thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Preferred ranges for the thickness of the stainless steel foil include about 10 to 60 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 30 μm, about 10 to 25 μm, about 15 to 60 μm, about 15 to 50 μm, about 15 to 40 μm, about 15 to 30 μm, and about 15 to 25 μm.

[0046] In addition, when the barrier layer 52 is an aluminum foil, it is preferable that at least the surface opposite to the base layer 51 is provided with a corrosion-resistant film in order to prevent dissolution and corrosion. The barrier layer 52 may be provided with a corrosion-resistant film on both sides. Here, the corrosion-resistant film refers to a thin film that is provided with corrosion resistance (e.g., acid resistance, alkali resistance, etc.) on the barrier layer 52 by performing, for example, hydrothermal conversion treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment such as nickel or chromium, or corrosion prevention treatment by applying a coating agent on the surface of the barrier layer 52. Specifically, the corrosion-resistant film refers to a film that improves the acid resistance of the barrier layer 52 (acid-resistant film), a film that improves the alkali resistance of the barrier layer 52 (alkali-resistant film), etc. The treatment for forming the corrosion-resistant film may be one type, or two or more types may be combined. In addition, not only one layer but also multiple layers may be formed. Furthermore, among these treatments, hydrothermal conversion treatment and anodizing treatment are treatments in which the metal foil surface is dissolved by 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. In addition, when the barrier layer 52 has a corrosion-resistant coating, the corrosion-resistant coating is also included in the barrier layer 52.

[0047] The corrosion-resistant coating prevents delamination between the barrier layer 52 (e.g., aluminum alloy foil) and the base layer 51 during molding of the exterior film 50, prevents dissolution and corrosion of the surface of the barrier layer 52 due to hydrogen fluoride produced by a reaction between an electrolyte and moisture, and in particular prevents dissolution and corrosion of aluminum oxide present on the surface of the barrier layer 52 when the barrier layer 52 is an aluminum alloy foil, and also improves the adhesion (wettability) of the surface of the barrier layer 52, thereby preventing delamination between the base layer 51 and the barrier layer 52 during heat sealing and between the base layer 51 and the barrier layer 52 during molding.

[0048] The heat-sealable resin layer 53 is bonded to the barrier layer 52, for example, via an adhesive layer 55. The heat-sealable resin layer 53 included in the exterior film 50 is a layer that imparts heat-sealing sealability to the exterior film 50. Examples of the heat-sealable resin layer 53 include resin films made of polyester resins such as polyethylene terephthalate resins and polybutylene terephthalate resins, polyolefin resins such as polyethylene resins and polypropylene resins, or acid-modified polyolefin resins obtained by graft-modifying these polyolefin resins with an acid such as maleic anhydride. The thickness of the heat-sealable resin layer 53 is preferably, for example, 20 to 300 μm, and more preferably 40 to 150 μm, in terms of sealability and strength.

[0049] The exterior film 50 preferably has one or more layers having a buffer function (hereinafter referred to as "buffer layer") outside the heat-sealable resin layer 53, more preferably outside the barrier layer 52. The buffer layer may be laminated on the outside of the base material layer 51, or the base material layer 51 may also function as a buffer layer. When the exterior film 50 has multiple buffer layers, the multiple buffer layers may be adjacent to each other, or may be laminated via the base material layer 51, the barrier layer 52, etc.

[0050] The material constituting the buffer layer can be arbitrarily selected from materials having cushioning properties. The material having cushioning properties is, for example, rubber, nonwoven fabric, or foam sheet. The rubber is, for example, natural rubber, fluororubber, or 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 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 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. Among these, the thickness of the buffer layer is most preferably in the range of 1000 μm to 3000 μm.

[0051] When the buffer layer is made of rubber, the lower limit of the thickness of the buffer layer is preferably 0.5 mm. When the buffer layer is made of rubber, the upper limit of the thickness of the buffer layer is preferably 10 mm, more preferably 5 mm, and more preferably 2 mm. When the buffer layer is made of rubber, the preferred range of the thickness of the buffer layer is 0.5 mm to 10 mm, 0.5 mm to 5 mm, or 0.5 mm to 2 mm.

[0052] When the exterior film 50 has a buffer layer, the buffer layer functions as a cushion, thereby preventing the exterior film 50 from being damaged by impact when the electricity storage device 10 is dropped or by handling during production of the electricity storage device 10.

[0053] The lid body 60 has, for example, a rectangular parallelepiped shape and is made of, for example, a resin material. The lid body 60 may be formed by, for example, cold forming the exterior film 50, or may be a metal molded product. When the lid body 60 is a metal molded product, it is preferable that the lid body 60 has the corrosion-resistant coating described in the barrier layer 52. The lid body 60 has a lid main body 60A. The lid main body 60A has a first surface 61, a second surface 62, and a lid seal portion 63. The first surface 61 faces the electrode body 20. The second surface 62 is the surface opposite to the first surface 61. The lid seal portion 63 is connected to the first surface 61 and the second surface 62, and is heat-sealed to the heat-fusible resin layer 53 of the exterior film 50. The lid seal portion 63 includes a first seal surface 63A, a second seal surface 63B, a third seal surface 63C, and a fourth seal surface 63D. The first seal surface 63A constitutes the upper surface of the lid body 60. The first seal surface 63A extends in a first direction (LR direction in this embodiment) in a front view of the lid body 60. The second seal surface 63B and the third seal surface 63C are connected to the first seal surface 63A and constitute the side surface of the lid body 60. The second seal surface 63B and the third seal surface 63C extend in a second direction (UD direction in this embodiment) intersecting with the first direction in a front view of the lid body 60. In this embodiment, the first direction and the second direction are orthogonal in a front view of the lid body 60. The first direction and the second direction do not have to be orthogonal in a front view of the lid body 60. The fourth seal surface 63D constitutes the lower surface of the lid body 60. The fourth seal surface 63D extends in a first direction (LR direction in this embodiment) in a front view of the lid body 60.

[0054] When the lid body 60 is plate-shaped, it is preferable that the lid body 60 has a certain degree of thickness so that deformation of the exterior body 40 is suppressed even when the power storage device 10 is arranged in a stacked manner. From another viewpoint, when the lid body 60 is plate-shaped, it is preferable that the lid seal portion 63 of the lid body 60 has a certain degree of thickness so that the lid seal portion 63 of the lid body 60 and the exterior film 50 can be suitably heat-sealed when forming the second sealing portion 80 described later. The minimum value of the thickness of the lid seal portion 63 of the lid body 60 is, for example, 1.0 mm, more preferably 3.0 mm, and even more preferably 4.0 mm. The maximum value of the thickness of the lid seal portion 63 of the lid body 60 is, for example, 20 mm, more preferably 15 mm, and even more preferably 10 mm. The maximum value of the thickness of the lid seal portion 63 of the lid body 60 may be 20 mm or more. The preferred ranges of the thickness of the lid seal portion 63 of the lid body 60 are 1.0 mm to 20 mm, 1.0 mm to 15 mm, 1.0 mm to 10 mm, 3.0 mm to 20 mm, 3.0 mm to 15 mm, 3.0 mm to 10 mm, 4.0 mm to 20 mm, 4.0 mm to 15 mm, and 4.0 mm to 10 mm. In this embodiment, when the lid body 60 is expressed as a plate-like body, the embodiment in which the lid body 60 is composed only of a film defined by the [packaging terminology] standard of JIS (Japanese Industrial Standards) is not included. The thickness of the lid seal portion 63 of the lid body 60 may be different depending on the part of the lid body 60. When the thickness of the lid seal portion 63 of the lid body 60 varies depending on the part, the thickness of the lid seal portion 63 of the lid body 60 is the thickness of the thickest part.

[0055] The lid seal portion 63 further includes boundaries 64, 65, 66, and 67. The boundary 64 is a boundary between the first seal surface 63A and the second seal surface 63B. The boundary 65 is a boundary between the first seal surface 63A and the third seal surface 63C. The boundary 66 is a boundary between the fourth seal surface 63D and the second seal surface 63B. The boundary 67 is a boundary between the fourth seal surface 63D and the third seal surface 63C. The shapes of the boundaries 64 to 67 may be angular, or may be rounded by performing R processing. In this embodiment, the boundaries 64 to 67 are angular.

[0056] From the viewpoint of suitable heat sealing between the lid 60 and the exterior film 50, it is preferable that the material constituting the lid 60 and the material constituting the heat-sealable resin layer 53 of the exterior film 50 are mainly made of the same material. In this embodiment, the material constituting the lid 60 and the material constituting the heat-sealable resin layer 53 are mainly made of polypropylene. Note that the main material refers to, for example, a material that accounts for 50% or more of the materials contained in the components.

[0057] In this embodiment, the lid body 60 includes a heat-sealable resin layer 60Z whose main material is an olefin-based copolymer. In this embodiment, the entire lid body 60 is made of the heat-sealable resin layer 60Z. It is sufficient that at least a portion of the lid body 60 including the lid seal portion 63 is made of the heat-sealable resin layer 60Z. The main material constituting the heat-sealable resin layer 60Z is preferably an olefin-based random copolymer.

[0058] The thermally adhesive resin layer 60Z contains a polyolefin skeleton such as polyolefin or acid-modified polyolefin. The inclusion of a polyolefin skeleton in the resin constituting the thermally adhesive resin layer 60Z can be determined by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like. When the resin constituting the thermally adhesive resin layer 60Z is analyzed by infrared spectroscopy, it is preferable that a peak derived from maleic anhydride is detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak derived from maleic anhydride is detected at a wave number of 1760 cm. -1 Nearby and wave number 1780cm -1 A peak derived from maleic anhydride is detected near the peak. When the thermally adhesive resin layer 60Z is a layer made of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected by infrared spectroscopy. However, if the degree of acid modification is low, the peak becomes small and may not be detected. In that case, analysis can be performed by nuclear magnetic resonance spectroscopy.

[0059] The heat-sealable resin layer 60Z preferably contains a resin containing a polyolefin skeleton as a main component, more preferably contains polyolefin as a main component, and even more preferably contains polypropylene as a main component. Here, the main component means that the content of the resin components contained in the heat-sealable resin layer 60Z is, for example, 35% by mass or more, preferably 50% by mass or more, more preferably 60% by mass or more, even 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 heat-sealable resin layer 60Z contains polypropylene as a main component means that the content of polypropylene of the resin components contained in the heat-sealable resin layer 60Z 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.

[0060] 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. Among these, polypropylene is preferred. 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.

[0061] The polyolefin may be a cyclic polyolefin. The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefins constituting the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. Examples of the cyclic monomers constituting the cyclic polyolefin include cyclic alkenes such as norbornene; and cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these, cyclic alkenes are preferred, and norbornene is more preferred.

[0062] The polyolefin may be an acid-modified polyolefin. The acid-modified polyolefin is a polymer modified by block polymerization or graft polymerization of a polyolefin with an acid component. The polyolefin to be acid-modified may be the above-mentioned polyolefin, a copolymer obtained by copolymerizing the above-mentioned polyolefin with a polar molecule such as acrylic acid or methacrylic acid, or a polymer such as a crosslinked polyolefin. The acid component used for the acid modification may be, for example, a carboxylic acid or an anhydride such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, or itaconic anhydride.

[0063] The acid-modified polyolefin may be an acid-modified cyclic polyolefin. The acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin by replacing it with an acid component, or by block-polymerizing or graft-polymerizing an acid component to the cyclic polyolefin. The cyclic polyolefin to be acid-modified is the same as described above. The acid component used for the acid modification is the same as the acid component used for the modification of the polyolefin.

[0064] Preferred acid-modified polyolefins include polyolefins modified with a carboxylic acid or anhydride thereof, polypropylenes modified with a carboxylic acid or anhydride thereof, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

[0065] It is preferable that a plurality of types of amide-based lubricants are present in the heat-sealable resin layer 60Z. When the lid 60 is molded in the manufacture of the electricity storage device 10, the amide-based lubricants are present on the surface of the heat-sealable resin layer 60Z. This improves the slipperiness of the surface of the heat-sealable resin layer 60Z, and enhances the moldability of the lid 60.

[0066] Examples of methods for making the heat-sealable resin layer 60Z have an amide-based lubricant present therein include coating the surface of the heat-sealable resin layer 60Z of the lid 60 with an amide-based lubricant, or blending an amide-based lubricant into the polyolefin resin forming the heat-sealable resin layer 60Z. Even when blending an amide-based lubricant into the polyolefin resin forming the heat-sealable resin layer 60Z, the amide-based lubricant can be made to exist on the surface of the heat-sealable resin layer 60Z by bleeding out the amide-based lubricant on the surface of the heat-sealable resin layer 60Z. On the other hand, even when coating the surface of the heat-sealable resin layer 60Z of the lid 60 with an amide-based lubricant, a portion of the amide-based lubricant can migrate from the surface to the inside, so that the amide-based lubricant can be made to exist inside the heat-sealable resin layer 60Z. A common method for bleeding out the amide-based lubricant onto the surface of the heat-sealable resin layer 60Z is to mature the lid body 60 at a slightly high temperature of about 30 to 50°C for several hours to three days to accelerate the bleeding. However, as the melting point of the amide-based lubricant is approached, the saturated amount of lubricant in the heat-sealable resin layer 60Z increases, so care must be taken with the amount added and the maturation temperature.

[0067] In this embodiment, it is preferable that the heat-sealable resin layer 60Z contains a plurality of types of fatty acid amide lubricants, and at least one of the fatty acid amide lubricants is a saturated fatty acid amide. The heat-sealable resin layer 60Z may contain one type of fatty acid amide lubricant.

[0068] The saturated fatty acid amide may be used alone or in combination of two or more. The saturated fatty acid amide is not particularly limited, but from the viewpoint of further improving moldability and continuous productivity of the electricity storage device 10, preferably, saturated fatty acid amide having 18 or more carbon atoms, more preferably, stearic acid amide, behenic acid amide, arachidic acid amide, etc., are mentioned, and particularly preferably, behenic acid amide is mentioned.

[0069] In this embodiment, the amide-based lubricant other than the saturated fatty acid amide is not particularly limited, and examples thereof include saturated fatty acid amides other than the saturated fatty acid amides exemplified above, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, etc. Specific examples of other saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, hydroxystearic acid amide, etc. Specific examples of unsaturated fatty acid amides include oleic acid amide, erucic acid amide, etc. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, etc. In addition, specific examples of methylol amides include methylol stearic acid amide, etc. Specific examples of saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipic acid amide, N,N'-distearyl sebacic acid amide, etc. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipic acid amide, N,N'-dioleyl sebacic acid amide, etc. Specific examples of fatty acid ester amides include stearamide ethyl stearate, etc. Specific examples of aromatic bisamides include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, N,N'-cystearylisophthalic acid amide, etc. These amide lubricants may be used alone or in combination of two or more.

[0070] In this embodiment, it is preferable that the multiple types of amide-based lubricants further contain unsaturated fatty acid amide in addition to the saturated fatty acid amide. This can further improve the moldability and continuous productivity of the electricity storage device 10 when the lid body 60 is not exposed to high temperatures. Although the details of this mechanism are not clear, it can be considered, for example, as follows. That is, the unsaturated fatty acid amide has a double bond in its molecular structure, and when the molecules form an association, the olefin chain has a folded structure. For this reason, the unsaturated fatty acid amide is relatively easy to move inside the heat-sealable resin layer 60Z, and is easy to bleed onto the surface of the heat-sealable resin layer 60Z, and is easy to develop slipperiness. On the other hand, the saturated fatty acid amide does not have a double bond in its molecular structure, is linear, and has a bulky structure when the molecules form an association (especially when the number of carbon atoms is 18 or more), so it is difficult to bleed onto the surface of the heat-sealable resin layer 60Z even during high-temperature storage, and is difficult to develop slipperiness. One hypothesis is that the unsaturated fatty acid amide and the saturated fatty acid amide are associated to form an associated body with appropriate bleeding and slip properties. The second hypothesis is that the unsaturated fatty acid bleeds first to form a first layer on the surface of the heat-sealable resin layer 60Z, and then the bled saturated fatty acid forms a second layer between the first layer and the heat-sealable resin layer 60Z, so that further bleeding of the unsaturated fatty acid, which causes the problem of white powder, is suppressed.

[0071] Regarding the carbon number of the saturated fatty acid amide, the weight loss due to overheating in the temperature range of about 230 to 280°C in which the resin (such as polypropylene) forming the heat-sealable resin layer 60Z is melt-extruded reaches about 50% or more when the carbon number is less than 18, and from the viewpoint of controlling the content, it is desirable that the carbon number is 18 or more, and further, as described above, the saturated fatty acid suppresses excessive bleeding of the lubricant (regardless of the above speculation), so that the carbon number is desirably about 22, such as behenic acid amide. From the viewpoint of further improving the moldability and the continuous productivity of the electricity storage device 10, erucic acid amide is particularly preferable as the unsaturated fatty acid amide. The unsaturated fatty acid amide may be used alone or in combination of two or more kinds.

[0072] In another example, the heat-sealable resin layer 60Z may be made of any one of an acid-modified polyolefin resin, an unsaturated carboxylic acid grafted polyolefin resin, a polypropylene resin, a metal ion cross-linked polyethylene, a copolymer resin of ethylene and an acrylic acid derivative, and a copolymer resin of ethylene and a methacrylic acid derivative.

[0073] In yet another example, the heat-sealable resin layer 60Z may be made of a polyolefin resin to which a propylene-based elastomer having a melting point higher than 150° C. is added. Compared with a polyolefin resin to which a propylene-based elastomer having a melting point higher than 150° C. is not added, the heat-sealable resin layer 60Z has a stable adhesive strength with the heat-sealable resin layer 53 of the exterior film 50 in an environment of about 150° C. This is because the heat-sealable resin layer 60Z is formed in a state in which a propylene-based elastomer resin having a melting point higher than 150° C. is uniformly dispersed in the polyolefin resin, and the high-melting-point propylene-based elastomer resin is maintained in a uniformly dispersed state in the polyolefin resin even after heat sealing (e.g., sealing temperature 190° C., surface pressure 1.0 MPa, sealing time 3.0 seconds). This prevents the portion where the heat-sealable resin layer 60Z and the heat-sealable resin layer 53 are sealed, ie, the second sealing portion 80 described below, from melting and softening even in a high-temperature environment of around 150°C.

[0074] The heat-sealable resin layer 60Z is characterized by having at least one layer having an elastic modulus of 1300 MPa or more measured at a pressing load of 100 μN in the FB direction. Since the heat-sealable resin layer 60Z has an elastic modulus of 1300 MPa or more, it can exhibit high insulation even when minute foreign matter is present in the heat-sealed portion of the heat-sealable resin layer 60Z. Since the heat-sealable resin layer 60Z has at least one layer having a high elastic modulus of 1300 MPa or more, it can effectively prevent the heat-sealable resin layer 60Z from becoming thin-walled even when heat-sealed at a location where minute foreign matter is present.

[0075] From the viewpoint of further improving the insulating properties, the elastic modulus is preferably 1500 MPa or more, more preferably 1800 MPa or more, and even more preferably 2000 MPa or more, and is preferably 3000 MPa or less, more preferably 2800 MPa or less, and even more preferably 2500 MPa or less. Preferred ranges include about 1300 to 3000 MPa, about 1300 to 2800 MPa, about 1300 to 2500 MPa, about 1500 to 3000 MPa, about 1500 to 2800 MPa, about 1500 to 2500 MPa, about 1800 to 3000 MPa, about 1800 to 2800 MPa, about 1800 to 2500 MPa, about 2000 to 3000 MPa, about 2000 to 2800 MPa, and about 2000 to 2600 MPa. More specifically, when the thermally adhesive resin layer 60Z is a layer having a strength of 1300 MPa or more, the above elastic modulus is preferable.

[0076] The elastic modulus of the thermally adhesive resin layer 60Z is measured by the indentation method as follows. The elastic modulus is measured using a nanoindenter (TriboIndenter TI950 manufactured by HYSITRON). In the nanoindenter, a regular triangular pyramid (Berkovich type) indenter with a diamond tip (TI-0039 manufactured by HYSITRON) is used. At room temperature (25°C), the thermally adhesive resin layer 60Z is cut to expose the cross section of the thermally adhesive resin layer 60Z. Next, the elastic modulus is measured when the indenter is pressed vertically against the cross section of the layer to be measured in the thermally adhesive resin layer 60Z using the nanoindenter. The measurement conditions are a load control method, and the pressing load is constant at 100μN (load is applied from 0 to 100μN in 10 seconds, 100μN is held for 5 seconds, and the load is removed from 100 to 0μN in 10 seconds).

[0077] The heat-fusible resin layer 60Z preferably has a logarithmic attenuation factor ΔE of 0.50 or less at 120° C. in a rigid pendulum measurement. When the logarithmic attenuation factor ΔE is 0.50 or less at 120° C., the heat-fusible resin layer 60Z is effectively prevented from collapsing when heat-fusible resin layer 60Z is heat-fused.

[0078] The logarithmic attenuation at 120°C in the rigid pendulum measurement is an index representing the hardness of the resin in a high-temperature environment of 120°C, and the smaller the logarithmic attenuation, the higher the hardness of the resin. The temperature when the thermally adhesive resin layer 60Z is thermally fused is high, and in the thermally fused portion formed by thermally fusing the thermally adhesive resin layer 60Z, the thermally adhesive resin layer 60Z may protrude significantly toward the inside of the thermally fused portion (the space side where the electrode body 20 is accommodated). If the thermally adhesive resin layer 60Z protrudes significantly toward the inside of the thermally fused portion, cracks will occur in the thermally adhesive resin layer 60Z starting from this protruding portion (so-called poly pool), and the insulation will likely decrease. Therefore, if the thermally adhesive resin layer 60Z protrudes significantly toward the inside of the thermally fused portion to form a protruding portion, the insulation will likely decrease due to the cracks. For this reason, it is important to control the shape of the thermally fused portion, and for this purpose, the hardness of the thermally adhesive resin layer 60Z at high temperatures is important. Therefore, in this embodiment, the logarithmic attenuation rate at a high temperature of 120°C is adopted. In the rigid pendulum measurement, the attenuation rate of the pendulum is measured when the temperature of the resin is increased from a low temperature to a high temperature. In the rigid pendulum measurement, the edge part is generally brought into contact with the surface of the measurement object, and the measurement object is caused to vibrate by pendulum movement in the left and right directions. In this embodiment, the hard heat-sealable resin layer 60Z having a logarithmic attenuation rate of 0.50 or less in a high temperature environment of 120°C is used as the material constituting the lid body 60, so that the collapse (thinning) of the heat-sealable resin layer 60Z during the heat fusion of the lid body 60 is suppressed. By suppressing the collapse of the heat-sealable resin layer 60Z, the heat-sealable resin layer 60Z is suppressed from protruding significantly to the inside of the heat-sealed portion in the heat-sealed portion formed by heat-sealing the heat-sealable resin layer 60Z, and the deterioration of the insulation of the lid body 60 due to heat fusion is effectively suppressed.

[0079] The logarithmic decrement ΔE is calculated by the following formula. ΔE=[ln(A1 / A2)+ln(A2 / A3)+...ln(An / An+1)] / n A: Amplitude n: wave number

[0080] From the viewpoint of effectively suppressing the collapse of the heat-fusible resin layer 60Z when the heat-fusible resin layer 60Z is heat-fused, the logarithmic decrement ΔE at 120°C is preferably about 0.10 or more, more preferably about 0.11 or more, and even more preferably about 0.12 or more, and is preferably about 0.50 or less, more preferably about 0.30 or less, even more preferably about 0.22 or less, and even more preferably 0.16 or less. Preferable ranges of the logarithmic decay rate ΔE include about 0.10 to 0.50, about 0.10 to 0.30, about 0.10 to 0.22, about 0.10 to 0.16, about 0.11 to 0.50, about 0.11 to 0.30, about 0.11 to 0.22, about 0.11 to 0.16, about 0.12 to 0.50, about 0.12 to 0.30, about 0.12 to 0.22, and about 0.12 to 0.16.

[0081] The logarithmic decrement ΔE of the heat-fusible resin layer 60Z can be adjusted by, for example, the melt mass flow rate (MFR), molecular weight, melting point, softening point, molecular weight distribution, degree of crystallinity, etc. of the resin constituting the heat-fusible resin layer 60Z.

[0082] In measuring the logarithmic decrement ΔE, a commercially available rigid pendulum type physical property tester is used, and a rigid pendulum physical property test is performed on the heat-sealable resin layer 60Z under the following conditions: a cylindrical cylinder edge is used as the edge pressed against the heat-sealable resin layer 60Z, the initial amplitude is 0.3 degrees, and the temperature range is from 30°C to 200°C with a heating rate of 3°C / min.

[0083] The melt mass flow rate of the heat-fusible resin layer 60Z at 230° C. is preferably in the range of 1 g / 10 min to 80 g / 10 min, and more preferably in the range of 5 g / 10 min to 60 g / 10 min. The melt mass flow rate is measured based on JIS K7210-1:2014.

[0084] From the viewpoint of effectively suppressing misalignment of the second sealing portion 80 described below, the melting point Tm1 of the heat-fusible resin layer 60Z is preferably 90° C. or more and 245° C. or less, more preferably 100° C. or more and 220° C. or less. From the same viewpoint, the softening point Ts1 of the heat-fusible resin layer 60Z is preferably 70° C. or more and 180° C. or less, more preferably 80° C. or more and 150° C. or less.

[0085] Here, the melting point Tm1 of the heat-sealable resin layer 60Z is a value obtained by measuring the melting points of the resin components constituting the heat-sealable resin layer 60Z by a DSC method in accordance with JIS K6921-2 (ISO1873-2.2:95). When the heat-sealable resin layer 60Z is made of a blended resin containing a plurality of resin components, the melting point Tm1 can be calculated by determining the melting points of the respective resins as described above and averaging them weighted by mass ratio.

[0086] The softening point Ts1 of the thermally adhesive resin layer 60Z is a value measured by a thermo-mechanical analyzer (TMA). When the thermally adhesive resin layer 60Z is made of a blended resin containing a plurality of resin components, the softening point Ts1 can be calculated by determining the softening points of the respective resins as described above and averaging them weighted by mass ratio.

[0087] The number average molecular weight (Mn) of the resin constituting the heat-sealable resin layer 60Z is preferably 70,000 or more and 80,000 or less, the weight average molecular weight (Mw) is preferably 320,000 or more and 370,000 or less, and the dispersity (Mw / Mn) is preferably 4.5 or more and 5.5 or less.

[0088] In addition, the number average molecular weight (Mn) and weight average molecular weight (Mw) of the resin constituting the heat-sealable resin layer 60Z are within the above ranges, and the details of the mechanism by which the lid 60 can be given high insulating properties and heat sealability are not necessarily clear, but for example, it can be considered as follows. That is, if the number average molecular weight (Mn) is smaller than 70,000, the amount of low molecular weight components is large, so that the amount of crushing due to pressure during heat sealing increases, and the insulating properties decrease. If the number average molecular weight (Mn) is larger than 80,000, the amount of low molecular weight components is small, so that there is a concern that the MFR will decrease, and there is a risk of film-forming properties being impaired. Furthermore, if the weight average molecular weight (Mw) is smaller than 320,000, the overall amount of high molecular weight components is small, so that the amount of crushing due to pressure during heat sealing increases, and the insulating properties decrease. If the weight average molecular weight (Mw) is larger than 370,000, the overall amount of high molecular weight components is large, so that there is a concern that the MFR will decrease, and there is a risk of film-forming properties being impaired. Furthermore, the details of the mechanism by which the polydispersity (Mw / Mn) of the resin constituting the heat-fusible resin layer 60Z falls within the above range can impart high insulating properties and heat-sealing properties to the lid 60 are not necessarily clear, but can be considered as follows, for example. That is, if the polydispersity (Mw / Mn) is less than 4.5, the molecular weight distribution is narrow, and there is a risk of necking-in during extrusion, which may cause a decrease in film formability. On the other hand, if the polydispersity (Mw / Mn) is more than 5.5, the molecular weight distribution becomes broad and the amount of low molecular weight components increases, so that the amount of crushing due to pressure during heat sealing increases, and insulating properties decrease.

[0089] In this embodiment, the lid body 60 is formed with a through hole 60X into which the electrode terminal 30 is inserted. The through hole 60X penetrates the first surface 61 and the second surface 62. When the electrode body 20 is stored, the electrode terminal 30 protrudes to the outside of the exterior body 40 through the through hole 60X formed in the lid body 60. A small gap between the through hole 60X of the lid body 60 and the electrode terminal 30 is filled with, for example, resin. Note that, in the electricity storage device 10, the position from which the electrode terminal 30 protrudes to the outside can be arbitrarily selected. For example, the electrode terminal 30 may protrude to the outside from a hole formed in any one of the six surfaces of the exterior body 40. In this case, a small gap between the exterior body 40 and the electrode terminal 30 is filled with, for example, resin. In the electricity storage device 10, the lid body 60 and the electrode terminal 30 are provided as separate bodies, but the lid body 60 and the electrode terminal 30 may be formed integrally. If the electrode terminals 30 do not protrude from the edge of the exterior body 40, the lid body 60 does not need to have the through-holes 60X formed therein.

[0090] In this embodiment, with the exterior film 50 wrapped around the electrode body 20 so as to have an opening 40A, the facing surfaces of the exterior film 50 (heat-fusible resin layer 53) are heat-sealed to form the first sealing portion 70.

[0091] The first sealed portion 70 is formed by heat-sealing a portion including the first edge 50A and a portion including the second edge 50B of the exterior film 50 shown in FIG. 3. The first sealed portion 70 extends in the longitudinal direction of the exterior body 40. The position at which the first sealed portion 70 is formed in the exterior body 40 can be selected arbitrarily. In this embodiment, the base 70X of the first sealed portion 70 is preferably located on the side 43 at the boundary between the first surface 41 and the second surface 42 of the exterior body 40. The first surface 41 has a larger area than the second surface 42. The base 70X of the first sealed portion 70 may be located on any surface of the exterior body 40. In this embodiment, the first sealed portion 70 protrudes outward from the electrode body 20 in a plan view. The first sealed portion 70 may be folded, for example, toward the second surface 42 of the exterior body 40, or toward the first surface 41.

[0092] In this embodiment, the second sealing portion 80 is formed by heat-sealing the heat-fusible resin layer 53 of the exterior film 50 and the lid seal portion 63 of the lid body 60. Hereinafter, the seal strength between the heat-fusible resin layer 53 of the exterior film 50 and the lid seal portion 63 of the lid body 60 may be referred to as the seal strength of the second sealing portion 80. The seal strength of the second sealing portion 80 is the seal strength between the heat-fusible resin layer 53 and the lid body 60 at the long side portion of the lid seal portion 63, i.e., the lid seal portion 63 extending in the LR (width) direction in FIG. 1A.

[0093] The seal strength of the second sealing portion 80 is measured as follows. First, a cut is made in a portion of the exterior film 50 that constitutes the first surface 41 of the exterior body 40, and three strip-shaped members 41X, 41Y, and 41Z (see the two-dot chain line in FIG. 1B) arranged in the LR direction are formed. The width of the three strip-shaped members 41X, 41Y, and 41Z in the LR direction is 15 mm. The ends of the strip-shaped members 41X, 41Y, and 41Z are joined to the lid body 60 at the second sealing portion 80. The length of the lid body 60 in the LR direction is 45 mm or more. Next, the end of the strip-shaped members 41X, 41Y, and 41Z opposite to the end joined to the lid body 60 is pulled upward in the UD direction (the direction opposite to the first surface 41B) to measure the seal strength of each of the strip-shaped members 41X, 41Y, and 41Z. In this embodiment, the seal strength of the second sealing portion 80 is the average value of the seal strengths of the strip members 41X, 41Y, and 41Z. When the length of the lid body 60 in the LR direction is less than 45 mm, three strip members of an arbitrary width X mm less than 15 mm are formed, and the seal strengths of the three strip members are measured in the same manner as when the length of the lid body 60 in the LR direction is 45 mm or more. The obtained seal strengths are divided by the arbitrary width X mm and multiplied by 15 to convert them into the seal strengths of the three strip members in a width of 15 mm. The seal strength of the second sealing portion 80 is the average value of the seal strengths of the three strip members converted into a width of 15 mm. In addition, when the lid body 60 is divided into multiple parts including long sides and short sides, the seal strength of the second sealing portion 80 is the seal strength of the long side portion of the lid seal portion 63 of the multiple parts.

[0094] From the viewpoint of suitably maintaining the state in which the electrode body 20 is sealed by the exterior body 40, the seal strength of the second sealing portion 80 is preferably 40N / 15mm or more, more preferably 50N / 15mm or more, more preferably 60N / 15mm or more, more preferably 70N / 15mm or more, and more preferably 85N / 15mm or more. When the seal strength of the second sealing portion 80 is 40N / 15mm or more, the state in which the electrode body 20 is sealed by the exterior body 40 is suitably maintained even if the electricity storage device 10 is used for, for example, several years (less than 10 years). When the seal strength of the second sealing portion 80 is 85N / 15mm or more, the state in which the electrode body 20 is sealed by the exterior body 40 is suitably maintained even if the electricity storage device 10 is used for, for example, 10 years or more. The seal strength of the second sealing portion 80 is preferably 300N / 15mm or less. A preferred range of the seal strength of the second sealing portion 80 is 40N / 15mm to 300N / 15mm, 50N / 15mm to 300N / 15mm, 60N / 15mm to 300N / 15mm, 70N / 15mm to 300N / 15mm, or 85N / 15mm to 300N / 15mm.

[0095] In this embodiment, the lid body 60 preferably has a protruding portion 68 protruding from the lid seal portion 63 so that a gap is unlikely to be formed between the exterior film 50 and the lid body 60. The protruding portion 68 may be formed integrally with the lid body 60A, or may be formed separately from the lid body 60A and joined to the lid body 60A. In this embodiment, the protruding portion 68 is formed integrally with the lid body 60A. The position at which the protruding portion 68 is formed in the lid seal portion 63 can be selected arbitrarily. A gap between the exterior film 50 and the lid body 60 is likely to be formed, for example, between the base 70X of the first sealing portion 70 and the lid body 60. In particular, when the base 70X of the first sealing portion 70 is located at the boundary 64 to the boundary 67 of the lid body 60, the resin filling property between the base 70X of the first sealing portion 70 and the lid body 60 is likely to decrease. For this reason, the protruding portion 68 is preferably formed at the location where the base 70X of the first sealing portion 70 is located in the lid seal portion 63. In this embodiment, the root 70X of the first sealing portion 70 is located at the boundary 64 of the lid body 60. For this reason, the protruding portion 68 is preferably formed at the boundary 64 in the lid seal portion 63. In this embodiment, the first sealing portion 70 is sealed with the protruding portion 68 sandwiched between them. Note that the protruding portion 68 may be formed on at least one of the first seal surface 63A, the second seal surface 63B, the third seal surface 63C, the fourth seal surface 63D, the boundary 65, the boundary 66, and the boundary 67.

[0096] The shape of the protrusion 68 can be selected arbitrarily. In this embodiment, the shape of the protrusion 68 is plate-like. The thickness of the protrusion 68 can be selected arbitrarily. In this embodiment, the thickness of the protrusion 68 becomes thinner as it moves away from the boundary 64. In other words, the protrusion 68 has a tapered shape as it moves away from the boundary 64. The thickness of the protrusion 68 may be constant, or may become thicker as it moves away from the boundary 64.

[0097] The direction in which the protrusion 68 extends can be selected arbitrarily. In this embodiment, the protrusion 68 extends along a first direction (in this embodiment, the LR direction). The protrusion 68 may extend along a second direction (in this embodiment, the UD direction).

[0098] The length of the protrusion 68 can be selected arbitrarily within a range equal to or less than the length of the first sealing portion 70. For example, the length of the protrusion 68 may be substantially equal to the length of the first sealing portion 70, or may be 30% to 50% of the length of the first sealing portion 70.

[0099] <1-2. Manufacturing method of electricity storage device> 7 is a flowchart showing an example of a method for manufacturing the power storage device 10. The method for manufacturing the power storage device 10 includes, for example, a first step, a second step, a third step, and a fourth step. The first step to the fourth step are performed by, for example, a manufacturing apparatus for the power storage device 10.

[0100] In the first step of step S11, the manufacturing equipment places the lid body 60 with the electrode terminals 30 attached to both ends of the electrode body 20. Completion of the first step electrically connects the electrode terminals 30 and the electrodes of the electrode body 20. Note that in the first step, the lid body 60 may be connected to the electrode terminals 30 that are electrically connected to the electrode body 20.

[0101] The second step of step S12 is performed after the first step. In the second step, the manufacturing device winds the exterior film 50 around the electrode body 20 and the lid body 60 while tension is applied to the exterior film 50, while restricting the movement of the electrode body 20 and the lid body 60 by the restricting means. The restricting means is, for example, a groove into which the electrode body 20 and the lid body 60 are fitted. The restricting means may be a device that applies an external force to the electrode body 20 and the lid body 60 so that the electrode body 20 and the lid body 60 do not move. The restricting means may be a device that applies a force to the electrode body 20 and the lid body 60 in the opposite direction to the direction in which the exterior film 50 is pulled. The restricting means may include a roller that runs on the exterior film 50 while the exterior film 50 is being pulled in order to remove wrinkles in the exterior film 50.

[0102] The third step of step S13 is performed after the second step. In the third step, the manufacturing device forms a first sealing portion 70 by heat-sealing the heat-sealable resin layer 53 of the portion including the first edge 50A of the exterior film 50 and the heat-sealable resin layer 53 of the portion including the second edge 50B while restricting the movement of the electrode body 20 and the cover body 60 and applying tension to the exterior film 50 so that the protruding portion 68 of the cover body 60 is sandwiched by the exterior film 50. The third step corresponds to a step of forming the first sealing portion 70.

[0103] The fourth step of step S14 is carried out after the third step. The manufacturing apparatus forms the second sealed portion 80 by heat-sealing the exterior film 50 and the lid body 60 together.

[0104] <1-3. Actions and Effects of Electricity Storage Devices> In the electricity storage device 10, the lid 60 is formed of the heat-sealable resin layer 60Z and is therefore suitably heat-sealed to the heat-sealable resin layer 53 of the exterior film 50. Therefore, the electrode body 20 can be suitably sealed by the exterior body 40.

[0105] [2. Modifications] The above-mentioned embodiment is an example of the form that the lid, the electricity storage device, and the peripheral member related to the present invention can take, and is not intended to limit the form. The lid, the electricity storage device, and the peripheral member related to the present invention can take a form different from the form exemplified in the embodiment. One example is a form in which a part of the configuration of the embodiment is replaced, changed, or omitted, or a form in which a new configuration is added to the embodiment. Below, several examples of modified embodiments are shown. Note that the following modified embodiments can be combined with each other as long as there is no technical contradiction.

[0106] <2-1. First modified example> In the electricity storage device 10 of the above embodiment, the lid 60 does not have to have the protrusion 68. The first modification can also be similarly applied to the following second to fourteenth modifications.

[0107] <2-2. Second modified example> In the electricity storage device 10 of the above embodiment, the direction in which the protrusion 68 extends can be changed as desired. For example, as shown in Fig. 8, the protrusion 68 may extend in a third direction intersecting the first direction (in the embodiment, the LR direction) and the second direction (in the embodiment, the UD direction) in a front view of the lid body 60.

[0108] <2-3.Third modified example> In the electric storage device 10 of the above embodiment, the configuration of the lid body 60 can be arbitrarily changed. As shown in FIG. 9, the lid body 60 may include a peripheral member 60B joined to at least a part of the peripheral portion of the lid main body 60A. In the third modification, the peripheral member 60B is a frame body that covers the entire peripheral portion of the lid main body 60A. In this modification, for example, the material constituting the lid main body 60A can be any material such as metal or resin. The material constituting the peripheral member 60B is a heat-sealable resin layer 60BZ. The specifications of the heat-sealable resin layer 60BZ can be applied to the specifications of the heat-sealable resin layer 60Z. In the third modification, the lid seal portion 63 and the protruding portion 68 of the lid body 60 are formed in the peripheral member 60B. In the third modification, the lid main body 60A and the peripheral member 60B may be formed as separate bodies and joined to each other. In the third modified example, the lid main body 60A and the peripheral member 60B may be integrally formed by two-color molding or insert molding.

[0109] In the third modification, the electricity storage device 10 may include at least one of an adhesive film and an adhesive layer between the lid main body 60A and the peripheral member 60B for suitably bonding the two. The adhesive film or adhesive layer may be a single layer or a multilayer, and preferably contains at least a resin material having a polar group. The adhesive layer can be formed by dip coating, a dispenser, an inkjet, a spray, or screen printing. From the viewpoint of suitably bonding the lid main body 60A and the peripheral member 60B, it is preferable that at least the surface of the lid seal portion 63 of the lid main body 60A is subjected to a roughening treatment.

[0110] In the third modified example, even when the power storage devices 10 are arranged in a stacked manner, it is preferable that the lid seal portion 63 of the peripheral member 60B has a certain degree of thickness so that the deformation of the exterior body 40 is suppressed. From another viewpoint, it is preferable that the lid seal portion 63 of the peripheral member 60B has a certain degree of thickness so that the lid seal portion 63 of the peripheral member 60B and the exterior film 50 can be suitably heat-sealed when the second sealing portion 80 is formed. The minimum value of the thickness of the lid seal portion 63 of the peripheral member 60B is, for example, 1.0 mm, more preferably 3.0 mm, and even more preferably 4.0 mm. The maximum value of the thickness of the lid seal portion 63 of the peripheral member 60B is, for example, 20 mm, more preferably 15 mm, and even more preferably 10 mm. The maximum value of the thickness of the lid seal portion 63 of the peripheral member 60B may be 20 mm or more. Preferred ranges for the thickness of the lid seal portion 63 of the peripheral member 60B are 1.0 mm to 20 mm, 1.0 mm to 15 mm, 1.0 mm to 10 mm, 3.0 mm to 20 mm, 3.0 mm to 15 mm, 3.0 mm to 10 mm, 4.0 mm to 20 mm, 4.0 mm to 15 mm, and 4.0 mm to 10 mm.

[0111] <2-4. Fourth modified example> In the electricity storage device 10 of the above embodiment, the specific method of forming the protrusion 68 of the lid body 60 can be changed as desired. For example, the protrusion 68 may be formed by an adhesive film or the like that is bonded to the lid seal portion 63 of the lid main body 60A. In this modification, for example, the protrusion 68 may be formed by bonding a plurality of adhesive films to the lid seal portion 63 in an overlapping manner, or the protrusion 68 may be formed by bonding an adhesive film to the lid seal portion 63 in a flap shape.

[0112] <2-5. Fifth Modification> The electricity storage device 10 of the above embodiment may have a peripheral member 60C disposed between the exterior film 50 and the lid body 60A as shown in FIG. 10 in order to suitably bond the exterior film 50 and the lid body 60. In the fifth modified example, the peripheral member 60C is an adhesive film bonded to the peripheral portion (lid seal portion 63) of the lid body 60A. In the fifth modified example, for example, the material constituting the lid body 60A may be any material such as metal or resin. In the fifth modified example, the peripheral member 60C is bonded to substantially the entire lid seal portion 63 of the lid body 60A. Note that the peripheral member 60C may be bonded to at least a part of the first surface 61 and at least a part of the second surface 62 of the lid body 60.

[0113] In the fifth modified example, for example, the lid body 60 with the peripheral member 60C adhered thereto is attached to the openings 40A at both ends of the exterior body 40, and then the second sealing portion 80 is formed. For example, the peripheral member 60C may be wrapped around the lid body 60 so as to cover the entire surface of the lid seal portion 63 of the lid body 60. It is preferable that the peripheral member 60C is configured to be wider than the lid seal portion 63 of the lid body 60 as a whole. In this case, the peripheral member 60C can be easily adhered to the lid body 60. Furthermore, since the boundaries 64 to 67 of the lid seal portion 63 are covered by the peripheral member 60C, the adhesion between the lid body 60 and the peripheral member 60C is enhanced.

[0114] FIG. 11 is a cross-sectional view showing an example of the layer structure of the peripheral member 60C. The peripheral member 60C is a film capable of bonding the exterior film 50 and the lid body 60. The peripheral member 60C preferably has a heat-sealable resin layer 60CA at least in a portion to be joined to the heat-sealable resin layer 53 of the exterior film 50. In the example shown in FIG. 11, the peripheral member 60C is a laminate (laminate film) having at least a heat-sealable resin layer 60CA, a barrier layer 60CB, and a heat-sealable resin layer 60CC in this order. The peripheral member 60C may have a single layer structure of the heat-sealable resin layer 60CA. The specifications of the heat-sealable resin layers 60CA and 60CC of the peripheral member 60C can be applied to the specifications of the heat-sealable resin layer 60Z. The specifications of the barrier layer 60CB can be applied to the specifications of the barrier layer 52 of the exterior film 50. The peripheral member 60C may have a heat-sealing resin layer instead of the heat-sealing resin layer 60CC on the side of the peripheral member 60C that is bonded to the lid body 60. The material constituting the heat-sealing resin layer is preferably an acid-modified polyolefin resin graft-modified with an acid such as maleic anhydride. The material constituting the heat-sealing resin layer 60CC of the peripheral member 60C can be arbitrarily selected as long as it can be bonded to the lid body 60A.

[0115] The peripheral member 60C may have a heat-resistant base layer instead of or in addition to the barrier layer 60CB. The heat-resistant base layer may be a film made of a heat-resistant resin, and may be, for example, a non-stretched or stretched film of polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polymethylpentene (registered trademark), polyacetal cyclic polyolefin, polyethylene, polypropylene, or the like. Polyethylene terephthalate is particularly preferable because it is inexpensive and has high strength.

[0116] The peripheral member 60C is preferably adhesive. When the peripheral member 60C is adhesive, the peripheral member 60C is less likely to be displaced relative to the lid 60 and the exterior film 50 when the second sealing portion 80 is formed with the peripheral member 60C disposed between the exterior film 50 and the lid 60. By incorporating a tackifier resin into the heat-sealable resin layers 60CA and 60CC of the peripheral member 60C, the peripheral member 60C can be given adhesiveness. Examples of the tackifier resin include amorphous polyolefins. Examples of the amorphous polyolefins include amorphous polypropylene and copolymers of amorphous propylene and other α-olefins. The content of the tackifier resin in the base material constituting the heat-sealable resin is preferably 10 to 20% by weight or less.

[0117] <2-6. Sixth Modification> In the above embodiment, it is possible to arbitrarily select the position where the electrode terminal 30 is arranged. For example, the electrode terminal 30 may protrude from the first sealing portion .

[0118] <2-7. Seventh Variation> In the above embodiment, the exterior film 50 of the electricity storage device 10 may protrude outward beyond at least one of the two lid bodies 60 in the FB direction. The electrode body 20 is sealed by closing the portion of the exterior film 50 that protrudes outward beyond the lid body 60. The portion of the exterior film 50 that protrudes beyond the lid body 60 may be folded like a Gabeltop pouch or a brick pouch.

[0119] <2-8. Eighth Modification> In the above embodiment, the exterior body 40 may not have one of the two lid bodies 60. In this modification, in the FB direction, in a portion of the exterior body 40 where the lid body 60 is omitted, the electrode body 20 is sealed by closing a portion of the exterior film 50 that protrudes outward beyond the electrode body 20. In this modification, the portion of the exterior film 50 that protrudes outward beyond the electrode body 20 may be folded like a Gabeltop pouch or a brick pouch.

[0120] <2-9. 9th Variation> In the above embodiment, the outer shape of the exterior body 40 can be changed as desired. The outer shape of the exterior body 40 may be a cylinder, a prism, or a cube.

[0121] <2-10. 10th Variation> In the above embodiment, the cover 60 may be configured to include a heat-sealable resin layer 160Z as shown in FIG. 12, instead of the heat-sealable resin layer 60Z shown in FIG. 4. In a third modified example, the peripheral member 60B may be configured to include a heat-sealable resin layer 160ZB as shown in FIG. 13, instead of the heat-sealable resin layer 60BZ shown in FIG. 9. In a fifth modified example, the peripheral member 60C may be configured to include a heat-sealable resin layer 160CA as shown in FIG. 14, instead of the heat-sealable resin layer 60CA shown in FIG. 11. Hereinafter, when the heat-sealable resin layer 160Z, the heat-sealable resin layer 160ZB, and the heat-sealable resin layer 160CA are not particularly distinguished from each other, they may be simply referred to as heat-sealable resin layers.

[0122] In the tenth variant, the heat-sealable resin layer is characterized in that, when the temperature difference T1 and the temperature difference T2 are measured by the following method, the value obtained by dividing the temperature difference T2 by the temperature difference T1 (ratio T2 / T1) is 0.60 or more.

[0123] (Measurement of temperature difference T1) A DSC curve is obtained for the heat-sealable resin layer by differential scanning calorimetry (DSC) in accordance with the provisions of JIS K7121:2012. From the obtained DSC curve, the temperature difference T1 between the extrapolated melting start temperature and the extrapolated melting end temperature of the melting peak temperature of the heat-sealable resin layer is measured. Note that the measurement of the temperature difference T1 differs from the measurement of the temperature difference T2 described below, in that the measurement object is a heat-sealable resin layer that has not been subjected to any treatment such as immersion in an electrolyte.

[0124] (Measurement of temperature difference T2) In an environment of 85°C, the heat-sealable resin layer is left to stand for 72 hours in an electrolyte solution in which the concentration of lithium hexafluorophosphate is 1 mol / l and the volume ratio of ethylene carbonate, diethyl carbonate, and dimethyl carbonate is 1:1:1, and then dried. Next, in accordance with the provisions of JIS K7121:2012, a DSC curve is obtained for the heat-sealable resin layer after drying by differential scanning calorimetry (DSC). From the obtained DSC curve, the temperature difference T2 between the melting peak temperature (extrapolated melting start temperature) and the extrapolated melting end temperature of the heat-sealable resin layer is measured.

[0125] The resin component used in the heat-sealable resin layer is not particularly limited as long as it is heat-sealable, and examples thereof include polyolefin, cyclic polyolefin, acid-modified polyolefin, and acid-modified cyclic polyolefin. That is, the heat-sealable resin layer may contain a polyolefin skeleton, and preferably contains a polyolefin skeleton. The presence of a polyolefin skeleton in the heat-sealable resin layer can be analyzed by, for example, infrared spectroscopy, gas chromatography mass spectrometry, and the like, and the analysis method is not particularly limited. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, it is found that the maleic anhydride-modified polyolefin has a wavelength of 1760 cm. -1 Nearby and wave number 1780cm -1 A peak derived from maleic anhydride is detected around this peak. However, if the degree of acid modification is low, the peak may be small and not detectable. In that case, analysis can be performed using nuclear magnetic resonance spectroscopy.

[0126] Specific examples of the polyolefin include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferable.

[0127] The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefins that are constituent monomers of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of the cyclic monomers that are constituent monomers of the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, preferred are cyclic alkenes, and more preferred are norbornene.

[0128] The acid-modified polyolefin is a polymer modified by block polymerization or graft polymerization of the polyolefin with an acid component such as a carboxylic acid. Examples of the acid component used for modification include carboxylic acids and anhydrides thereof, such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

[0129] The acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin by replacing them with an α,β-unsaturated carboxylic acid or its anhydride, or by block-polymerizing or graft-polymerizing an α,β-unsaturated carboxylic acid or its anhydride to the cyclic polyolefin. The cyclic polyolefin to be modified with a carboxylic acid is the same as described above. The carboxylic acid used for the modification is the same as the acid component used for the modification of the polyolefin.

[0130] Among these resin components, preferred are polyolefins such as polypropylene and carboxylic acid-modified polyolefins; more preferred are polypropylene and acid-modified polypropylene.

[0131] The heat-fusible resin layer may be formed of one type of resin component alone, or may be formed of a blend polymer of two or more types of resin components. Furthermore, the heat-fusible resin layer may be formed of only one layer, or may be formed of two or more layers of the same or different resin components.

[0132] The heat-fusible resin layer may contain a lubricant. The lubricant present on the surface of the heat-fusible resin layer may be a lubricant exuded from the resin constituting the heat-fusible resin layer, or a lubricant applied to the surface of the heat-fusible resin layer.

[0133] More specifically, as can be understood from the measurement contents of the temperature differences T1 and T2 below, the closer the ratio T2 / T1 is to the upper limit value of 1.0, the smaller the change in the width of the start point (extrapolated melting start temperature) and end point (extrapolated melting end temperature) of the melting peak before and after the heat-sealable resin layer comes into contact with the electrolyte. That is, the value of the temperature difference T2 is usually equal to or less than the value of the temperature difference T1. The reason for the large change in the width of the extrapolated melting start temperature and the extrapolated melting end temperature of the melting peak is that the low molecular weight resin contained in the resin constituting the heat-sealable resin layer is dissolved in the electrolyte by contacting with the electrolyte, and the width of the extrapolated melting start temperature and the extrapolated melting end temperature of the melting peak of the heat-sealable resin layer after contacting with the electrolyte becomes smaller than that before contacting with the electrolyte. One method for reducing the change in the width of the extrapolated melting start temperature and the extrapolated melting end temperature of the melting peak is to adjust the proportion of the low molecular weight resin contained in the resin constituting the heat-sealable resin layer.

[0134] In measuring the extrapolated melting start temperature and the extrapolated melting end temperature of the melting peak temperature, a commercially available differential scanning calorimeter can be used. In addition, as the DSC curve, the test sample is held at -50°C for 10 minutes, then heated to 200°C at a heating rate of 10°C / min (first time), held at 200°C for 10 minutes, cooled to -50°C at a heating rate of -10°C / min, held at -50°C for 10 minutes, heated to 200°C at a heating rate of 10°C / min (second time), held at 200°C for 10 minutes, and heated to 200°C for the second time. In addition, when measuring the temperature difference T1 and the temperature difference T2, the melting peak that has the largest difference in thermal energy input is analyzed among the melting peaks that appear in the range of 120 to 160°C in each DSC curve. Even if two or more overlapping peaks exist, analysis is performed only for the melting peak with the largest difference in thermal energy input.

[0135] The extrapolated melting onset temperature means the start point of the melting peak temperature, and is the temperature at the intersection of a straight line extending the baseline on the low temperature side (65-75°C) to the high temperature side and a tangent drawn at the maximum gradient on the curve on the low temperature side of the melting peak where the difference in thermal energy input is maximum. The extrapolated melting end temperature means the end point of the melting peak temperature, and is the temperature at the intersection of a straight line extending the baseline on the high temperature side (170°C) to the low temperature side and a tangent drawn at the maximum gradient on the curve on the high temperature side of the melting peak where the difference in thermal energy input is maximum.

[0136] Even when the electrolytic solution contacts the heat-sealable resin layer in a high-temperature environment and the heat-sealable resin layers are heat-sealed together with the electrolytic solution attached to the heat-sealable resin layer, the value obtained by dividing the temperature difference T2 by the temperature difference T1 (ratio T2 / T1) is preferably 0.70 or more, more preferably 0.75 or more, and the preferred range is about 0.70 to 1.0, about 0.75 to 1.0. The upper limit is, for example, 1.0. In order to set such a ratio T2 / T1, for example, the type, composition, molecular weight, etc. of the resin constituting the heat-sealable resin layer are adjusted.

[0137] <2-11. 11th Variation> In the fifth modification, the peripheral member 60C may include a heat-sealable resin layer 260CA as shown in FIG. 15, instead of the heat-sealable resin layer 60CA shown in FIG. 11. That is, in the eleventh modification, the peripheral member 60C is configured from a laminate including at least a barrier layer 60CB and a heat-sealable resin layer 260CA in this order from the inside (the lid body 60 side) to the outside (the exterior film 50 side). The peripheral member 60C is only required to include at least the heat-sealable resin layer 260CA. The peripheral member 60C includes a peripheral member seal portion that is sealed with the exterior film 50 that constitutes the exterior body 40. In the eleventh modification, a sea-island structure is observed in a cross-sectional image obtained by using a field emission scanning electron microscope for a cross section in the thickness direction of the peripheral member seal portion, and the area ratio of the island portions of the sea-island structure in the cross-sectional image is 0.1% or more and 50% or less. The thermally adhesive resin layer 260CA corresponds to the peripheral member seal portion. In the cross-sectional image, the area ratio RA of the island portions of the sea-island structure is preferably 5% or more and 50% or less, more preferably 10% or more and 50% or less, and even more preferably 25% or more and 35% or less.

[0138] The main material constituting the heat-sealing resin layer 260CA can be selected arbitrarily as long as the ratio RA is 5% or more and 50% or less. The main material constituting the heat-sealing resin layer 260CA is preferably an olefin-based copolymer, and more preferably an olefin-based random copolymer. In the eleventh modified example, when the cross section cut by a plane perpendicular to the FB direction and the cross section cut by a plane perpendicular to the LR direction of the heat-sealing resin layer 260CA arranged on the first seal surface 63A or the fourth seal surface 63D are observed using a scanning electron microscope, the cross section in the TD direction is the one in which the average aspect ratio of the island shape is closer to 1. When the cross section cut by a plane perpendicular to the FB direction and the cross section cut by a plane perpendicular to the UD direction of the heat-sealing resin layer 260CA arranged on the second seal surface 63B or the third seal surface 63C are observed using a scanning electron microscope, the cross section in the TD direction is the one in which the average aspect ratio of the island shape is closer to 1.

[0139] The sea-island structure is observed in the cross-sectional image when a sea part (sea part) and an island part (island part) are observed in the cross-sectional image. When a small amount of polyethylene is added to polypropylene and a heat-sealable resin layer is formed by melt extrusion molding, a sea-island structure is formed in which the polyethylene island parts are dispersed in the sea part of the polypropylene. In order to observe the sea-island structure, as described later, the cross section of the heat-sealable resin layer is stained with ruthenium tetroxide or the like, and a cross-sectional image is obtained and observed using a scanning electron microscope. The specifications related to the eleventh modified example can be similarly applied to the peripheral member 60B (frame body) shown in FIG. 9. The part of the peripheral member 60B including the lid seal part 63 corresponds to the peripheral member seal part.

[0140] <2-12. 12th modified example> In the above embodiment, the lid 60 may be configured to include a heat-sealable resin layer 260Z as shown in FIG. 16, instead of the heat-sealable resin layer 60Z shown in FIG. 4. In the lid 60, a sea-island structure is observed in a cross-section image of the lid seal portion 63 in the thickness direction, obtained by using a field emission scanning electron microscope, and the area ratio RB of the island portion of the sea-island structure in the cross-section image is 0.1% to 50%, preferably 5% to 50%, more preferably 10% to 50%, and even more preferably 25% to 35%. In the twelfth modification, at least a portion of the lid 60 including the lid seal portion 63 may be configured by the heat-sealable resin layer 260Z. The main material constituting the heat-sealable resin layer 260Z may be selected arbitrarily as long as the ratio RB is 0.1% to 50%. The main material constituting the thermally adhesive resin layer 260Z is preferably an olefin-based copolymer, and more preferably an olefin-based random copolymer.

[0141] The sea-island structure observed in the cross-sectional image means that a sea part (sea part) and an island part (island part) are observed in the cross-sectional image. When a small amount of polyethylene is added to polypropylene and a heat-sealable resin layer is formed by melt extrusion molding, a sea-island structure is formed in which the polyethylene island parts are dispersed in the sea part of the polypropylene. To observe the sea-island structure, the cross-section of the heat-sealable resin layer 260Z is stained with ruthenium tetroxide or the like, and a cross-sectional image is obtained and observed using a scanning electron microscope.

[0142] <2-13. 13th Variation> In the fifth modification, the peripheral member 60C serving as an adhesive film may be made of cast polypropylene having necessary physical properties such as heat resistance and moisture resistance.

[0143] <2-14. 14th Variation> Fig. 17 is a cross-sectional view of an electricity accumulation device 10 of a fourteenth modification. Fig. 18 is a cross-sectional view of the lid 60 and its periphery in Fig. 17. As shown in FIG. 17 and FIG. 18, the barrier film 90 may be bonded to the lid 60 from the viewpoint of suppressing the intrusion of at least one of moisture and gas into the interior of the exterior body 40. In this embodiment, the barrier film 90 suppresses the intrusion of moisture and gas into the interior of the exterior body 40. The barrier film 90 may be bonded to a position of the lid 60 where it can be bonded to the exterior film 50. In the example shown in FIG. 17 and FIG. 18, the barrier film 90 covers the entire lid seal portion 63, the second surface 62, and the inside of the through hole 60X of the lid 60. The barrier film 90 may cover the boundaries 64 to 67. Since the barrier film 90 covers the lid seal portion 63 and the boundaries 64 to 67, as well as the second surface 62 and the inside of the through hole 60X, the intrusion of moisture into the interior of the exterior body 40 from between the electrode terminal 30 and the through hole 60X is suppressed. The barrier film 90 may be formed of a single film, or, for example, the portion covering the lid seal portion 63 and the portion covering the second surface 62 may be formed separately. In other words, the barrier film 90 may be a plurality of divided films.

[0144] The position of the end 90A of the portion of the barrier film 90 covering the lid seal portion 63 and the position of the end 90B of the portion covering the inside of the through-hole 60X of the lid body 60 can be selected arbitrarily. When the electricity storage device 10 is a battery containing an electrolyte solution, such as a lithium ion battery, the ends 90A and 90B of the barrier film 90 may come into contact with gas, such as hydrogen fluoride, generated from the electrolyte solution, which may corrode a barrier layer 91 provided in the barrier film 90, which will be described later.

[0145] For this reason, from the viewpoint of suppressing corrosion of the barrier layer 91, it is preferable that the end 90A is located closer to the second surface 62 than the boundary between the lid seal portion 63 and the first surface 61. From the same viewpoint, it is preferable that the end 90B is located closer to the opening of the through-hole 60X on the second surface 62 side than the opening of the through-hole 60X on the first surface 61 side. The end 90A may be located at the boundary between the lid seal portion 63 and the first surface 61, or may extend to a position closer to the electrode body 20 than the lid body 60. The end 90B may be located in the vicinity of the opening of the through-hole 60X on the first surface 61 side, or may extend to a position closer to the electrode body 20 than the lid body 60.

[0146] 19 and 20 are cross-sectional views showing an example of the layer structure of the barrier film 90. As shown in FIG. 19, a barrier film 90 may include a barrier layer 91 and a heat-sealable resin layer 92 laminated on the surface of the barrier layer 91 opposite to the surface bonded to the lid 60. The specifications of the barrier layer 91 can be the same as those of the barrier layer 52.

[0147] The heat-sealable resin layer 92 is heat-sealed to the heat-sealable resin layer 53 of the exterior film 50. The specifications of the heat-sealable resin layer 92 may be the same as those of the heat-sealable resin layers 60Z, 60BZ, 60CA, 60CC, 160Z, 160BZ, 160CA, 260CA, and 260Z. The heat-sealable resin layer 92 may be thinner than the heat-sealable resin layer 53. The thickness of the heat-sealable resin layer 92 may be, for example, 5 to 20 μm.

[0148] As shown in FIG. 20, the barrier film 90 may include a heat-sealable resin layer 93 laminated on the surface of the barrier layer 91 that is to be bonded to the lid 60. The specifications of the heat-sealable resin layer 93 are the same as those of the heat-sealable resin layer 92. The heat-sealable resin layer 93 may be thinner than the heat-sealable resin layer 53. The thickness of the heat-sealable resin layer 93 may be, for example, 5 to 20 μm. When the barrier film 90 includes the heat-sealable resin layer 93, the barrier film 90 and the lid 60 can be suitably bonded together by heat fusion. The barrier layer 91 and the heat-sealable resin layer 93 may be bonded together by an adhesive layer 55.

[0149] In the fourteenth modification, the barrier film 90 may be bonded to only at least a part of the second surface 62 of the lid 60. In this configuration, as in the seventh modification, the electrode body 20 may be sealed by heat sealing the heat-fusible resin layer 53 of the portion of the exterior film 50 that protrudes outward beyond the lid 60 and the heat-fusible resin layer 92 of the barrier film 90.

[0150] The fourteenth variant discloses the following technical idea. (A) A lid for use in an exterior body of an electricity storage device, The lid body is The lid body and a barrier film joined to the lid body at a position where the barrier film can be joined to the exterior film constituting the exterior body, The barrier film includes a heat-sealable resin layer whose main material is an olefin copolymer. Lid body.

[0151] (B) an electrode body; and an exterior body that seals the electrode body, The exterior body is An exterior film that wraps the electrode body; A lid body joined to the exterior film, The lid body is The lid body and a barrier film joined to the lid body at a position where the barrier film can be joined to the exterior film constituting the exterior body, The barrier film includes a heat-sealable resin layer whose main material is an olefin copolymer. Energy storage device.

[0152] (C) A barrier film constituting a lid used for an exterior body of an electricity storage device, The lid body is The lid body and a barrier film joined to the lid body at a position where the barrier film can be joined to the exterior film constituting the exterior body, The barrier film includes a heat-sealable resin layer whose main material is an olefin copolymer. Barrier film.

[0153] (D) A barrier film constituting a lid used for an exterior body of an electricity storage device, The lid body is The lid body and the barrier film is joined to the lid body at a position where it can be joined to an exterior film constituting the exterior body, The barrier film includes a heat-sealable resin layer, The thermally adhesive resin layer is a barrier film, wherein a temperature difference T1 and a temperature difference T2 are measured by the following method, and the value obtained by dividing the temperature difference T2 by the temperature difference T1 is 0.60 or more. (Measurement of temperature difference T1) A temperature difference T1 between the extrapolated melting start temperature and the extrapolated melting end temperature of the melting peak temperature of the heat-fusible resin layer is measured by differential scanning calorimetry. (Measurement of temperature difference T2) The heat-sealable resin layer is left to stand for 72 hours in an electrolyte solution containing lithium hexafluorophosphate at a concentration of 1 mol / l and ethylene carbonate, diethyl carbonate, and dimethyl carbonate at a volume ratio of 1:1:1 in an environment at a temperature of 85° C., and then dried. The temperature difference T2 between the extrapolated melting start temperature and the extrapolated melting end temperature of the melting peak temperature of the heat-sealable resin layer after drying is measured by differential scanning calorimetry.

[0154] (E) A barrier film constituting a lid used for an exterior body of an electricity storage device, The lid body is The lid body and the barrier film is joined to the lid body at a position where it can be joined to an exterior film constituting the exterior body, the barrier film includes a heat-sealable resin layer that is sealed to the exterior film, a sea-island structure is observed in a cross-sectional image of the thermal adhesive resin layer in the thickness direction, the cross-sectional image being obtained using a field emission scanning electron microscope; In the cross-sectional image, the area ratio of the islands in the sea-island structure is 0.1% or more and 50% or less, preferably 5% or more and 50% or less, more preferably 10% or more and 50% or less, and even more preferably 25% or more and 35% or less. [Explanation of symbols]

[0155] 10: Energy storage device 20: Electrode body 40: Exterior body 50: Exterior film 60: Lid 60B: Peripheral member (frame) 60C: Peripheral member (adhesive film) 60Z, 60BZ, 60CA, 60CC, 160Z, 160BZ, 160CA, 260CA, 260Z: Heat-fusible resin layer 60CB: Barrier layer

Claims

1. A lid body used for an exterior body of an electricity storage device, The lid body is The lid body and a peripheral member joined to at least a portion of the peripheral portion of the lid body; The peripheral member is The thermal adhesive resin layer is made of an olefin copolymer as a main material. A frame body joined to the lid body, the frame is a resin molded product having a lid seal portion with a thickness sufficient to be joined to an exterior film constituting the exterior body, The lid sealing portion has a plurality of sealing surfaces that are sealed to the exterior film, and boundaries of the plurality of sealing surfaces; a protrusion protruding from at least one of the plurality of sealing surfaces and the boundaries; The protrusion is configured to fill a gap between the exterior film and the lid. Lid body.

2. A lid body used for an exterior body of an electricity storage device, The lid body is The thermal adhesive resin layer is made of an olefin copolymer as a main material. A lid seal part is provided which is sealed with an exterior film constituting the exterior body, The lid sealing portion has a plurality of sealing surfaces that are sealed to the exterior film, and boundaries of the plurality of sealing surfaces; a protrusion protruding from at least one of the plurality of sealing surfaces and the boundaries; The protrusion is configured to fill a gap between the exterior film and the lid. Lid body.

3. The olefin copolymer is an olefin random copolymer. The lid according to claim 1 or 2.

4. The heat-sealable resin layer contains a fatty acid amide-based lubricant. The lid according to claim 1 or 2.

5. There are multiple types of fatty acid amide lubricants, At least one of the fatty acid amide-based lubricants is a saturated fatty acid amide. The lid according to claim 4.

6. The plurality of fatty acid amide-based lubricants further include an unsaturated fatty acid amide. The lid according to claim 5.

7. The saturated fatty acid amide has 18 or more carbon atoms. The lid according to claim 5.

8. The saturated fatty acid amide is behenic acid amide. The lid according to claim 5.

9. The unsaturated fatty acid amide is erucic acid amide. The lid according to claim 6.

10. The heat-sealable resin layer is made of any one of an acid-modified polyolefin resin, an unsaturated carboxylic acid-grafted polyolefin resin, a polypropylene resin, a metal ion-crosslinked polyethylene, a copolymer of ethylene and an acrylic acid derivative, and a copolymer of ethylene and a methacrylic acid derivative. The lid according to claim 1 or 2.

11. The heat-sealable resin layer contains a propylene-based elastomer resin having a melting point of more than 150° C. The lid according to claim 1 or 2.

12. An electrode body; and an exterior body that seals the electrode body, The exterior body is An exterior film that wraps the electrode body; A lid body joined to the exterior film, The lid body is The lid body and a peripheral member joined to at least a portion of the peripheral portion of the lid body; The peripheral member is The thermal adhesive resin layer is made of an olefin copolymer as a main material. A frame body joined to the lid body, the frame is a resin molded product having a lid seal portion with a thickness sufficient to be joined to the exterior film, The lid sealing portion has a plurality of sealing surfaces that are sealed to the exterior film, and boundaries of the plurality of sealing surfaces; a protrusion protruding from at least one of the plurality of sealing surfaces and the boundaries; The protrusion is configured to fill a gap between the exterior film and the lid. Energy storage device.

13. An electrode body; and an exterior body that seals the electrode body, The exterior body is An exterior film that wraps the electrode body; A lid body joined to the exterior film, The lid body is The thermal adhesive resin layer is made of an olefin copolymer as a main material. A lid seal portion is provided which is sealed with the exterior film, The lid sealing portion has a plurality of sealing surfaces that are sealed to the exterior film, and boundaries of the plurality of sealing surfaces; a protrusion protruding from at least one of the plurality of sealing surfaces and the boundaries; The protrusion is configured to fill a gap between the exterior film and the lid. Energy storage device.

14. A peripheral member constituting a lid used for an exterior body of an electricity storage device, The lid body is The lid body and The peripheral member is joined to at least a portion of the peripheral portion of the lid body, the peripheral member includes a heat-sealable resin layer whose main material is an olefin-based copolymer, a resin molded frame having a lid seal portion joined to the lid body and having a thickness sufficient to be joined to an exterior film constituting the exterior body; The lid sealing portion has a plurality of sealing surfaces that are sealed to the exterior film, and boundaries of the plurality of sealing surfaces; a protrusion protruding from at least one of the plurality of sealing surfaces and the boundaries; The protrusion is configured to fill a gap between the exterior film and the lid. Peripheral parts.

15. A lid body used for an exterior body of an electricity storage device, A resin molded product including a heat-sealable resin layer and a lid seal portion having a thickness sufficient to be bonded to an exterior film constituting the exterior body, The lid sealing portion has a plurality of sealing surfaces that are sealed to the exterior film, and boundaries of the plurality of sealing surfaces; a protrusion protruding from at least one of the plurality of sealing surfaces and the boundaries; The protrusion is configured to fill a gap between the exterior film and the lid, The heat-sealable resin layer has a temperature difference T1 and a temperature difference T2 measured by the following method, and the value obtained by dividing the temperature difference T2 by the temperature difference T1 is 0.60 or more. (Measurement of temperature difference T1) A temperature difference T1 between the extrapolated melting start temperature and the extrapolated melting end temperature of the melting peak temperature of the heat-fusible resin layer is measured by differential scanning calorimetry. (Measurement of temperature difference T2) The heat-sealable resin layer is left to stand for 72 hours in an electrolyte solution having a lithium hexafluorophosphate concentration of 1 mol / L and a volume ratio of ethylene carbonate, diethyl carbonate, and dimethyl carbonate of 1:1:1 in an environment at a temperature of 85° C., and then dried. The temperature difference T2 between the extrapolated melting start temperature and the extrapolated melting end temperature of the melting peak temperature of the heat-sealable resin layer after drying is measured by differential scanning calorimetry.

16. A lid body used for an exterior body of an electricity storage device, A resin molded product including a heat-sealable resin layer and a lid seal portion having a thickness sufficient to be bonded to an exterior film constituting the exterior body, The lid sealing portion has a plurality of sealing surfaces that are sealed to the exterior film, and boundaries of the plurality of sealing surfaces; a protrusion protruding from at least one of the plurality of sealing surfaces and the boundaries; The protrusion is configured to fill a gap between the exterior film and the lid, A sea-island structure is observed in a cross-sectional image of a cross section in the thickness direction of the lid seal portion obtained using a field emission scanning electron microscope, and the area ratio of the island portions of the sea-island structure in the cross-sectional image is 0.1% or more and 50% or less. Lid body.

17. A peripheral member constituting a lid used for an exterior body of an electricity storage device, The lid body is The lid body and The peripheral member is joined to at least a portion of the peripheral portion of the lid body, the peripheral member is a resin molded frame including a heat-sealable resin layer, joined to the lid body, and having a lid seal portion having a thickness sufficient to be joined to an exterior film constituting the exterior body; The lid sealing portion has a plurality of sealing surfaces that are sealed to the exterior film, and boundaries of the plurality of sealing surfaces; a protrusion protruding from at least one of the plurality of sealing surfaces and the boundaries; The protrusion is configured to fill a gap between the exterior film and the lid. The heat-sealable resin layer has a temperature difference T1 and a temperature difference T2 measured by the following method, and the value obtained by dividing the temperature difference T2 by the temperature difference T1 is 0.60 or more. (Measurement of temperature difference T1) A temperature difference T1 between the extrapolated melting start temperature and the extrapolated melting end temperature of the melting peak temperature of the heat-fusible resin layer is measured by differential scanning calorimetry. (Measurement of temperature difference T2) The heat-sealable resin layer is left to stand for 72 hours in an electrolyte solution having a lithium hexafluorophosphate concentration of 1 mol / L and a volume ratio of ethylene carbonate, diethyl carbonate, and dimethyl carbonate of 1:1:1 in an environment at a temperature of 85° C., and then dried. The temperature difference T2 between the extrapolated melting start temperature and the extrapolated melting end temperature of the melting peak temperature of the heat-sealable resin layer after drying is measured by differential scanning calorimetry.

18. A peripheral member constituting a lid used for an exterior body of an electricity storage device, The lid body is The lid body and The peripheral member is joined to at least a portion of the peripheral portion of the lid body, the peripheral member is a resin molded frame body that is joined to the lid body and has a lid seal portion that is thick enough to be joined to an exterior film that constitutes the exterior body, The lid sealing portion has a plurality of sealing surfaces that are sealed to the exterior film, and boundaries of the plurality of sealing surfaces; a protrusion protruding from at least one of the plurality of sealing surfaces and the boundaries; The protrusion is configured to fill a gap between the exterior film and the lid. A sea-island structure is observed in a cross-sectional image of a cross section in the thickness direction of the lid seal portion obtained using a field emission scanning electron microscope, and the area ratio of the island portions of the sea-island structure in the cross-sectional image is 0.1% or more and 50% or less. Peripheral parts.

Images