Lid body, power storage device, and manufacturing method of power storage device

Abstract

To provide a power storage device which enables an electrode body to be preferably sealed with an exterior casing, and to provide a lid body used in the power storage device and a manufacturing method of the power storage device.SOLUTION: A lid body is used in an exterior casing of a power storage device. The exterior casing includes an exterior packing film wound around an electrode body so as to have an opening. The lid body includes: a lid seal part which is disposed at the opening and is sealed with the exterior packing film; and a protruding part protruding from the lid seal part.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a lid, an electricity storage device, and a method for manufacturing an electricity storage device. [Background technology]

[0002] Patent Document 1 discloses an all-solid-state battery as an example of an electricity storage device. This all-solid-state battery includes an electrode body and an exterior body that seals the electrode body. The exterior body includes an exterior film that is wrapped around the electrode body to have an opening, and a lid body that is placed on the opening. The exterior film and the outer peripheral surface of the lid body are heat-sealed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-153504 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned electricity storage device, a gap may be formed between the lid and the exterior film, for example, between a corner of the lid and the exterior film, leaving room for improvement in terms of suitably sealing the electrode assembly with the exterior body.

[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 method for manufacturing the electricity storage device. [Means for solving the problem]

[0006] The lid body according to a first aspect of the present invention is a lid body used as an exterior body for an electricity storage device, the exterior body including an exterior film that is wrapped around an electrode body so as to have an opening, the lid body including a lid seal portion that is disposed in the opening and sealed to the exterior film, and a protrusion that protrudes from the lid seal portion.

[0007] A lid according to a second aspect of the present invention is the lid according to the first aspect, wherein the protruding portion tapers away from the lid seal portion.

[0008] A lid body according to a third aspect of the present invention is a lid body according to the first or second aspect, wherein the lid sealing portion includes a first sealing surface extending in a first direction in a front view of the lid body and a second sealing surface extending in a second direction intersecting the first direction in a front view of the lid body, and the protrusion is formed at the boundary between the first sealing surface and the second sealing surface.

[0009] A lid body according to a fourth aspect of the present invention is the lid body according to the third aspect, wherein the protrusion extends in the first direction or the second direction in a front view of the lid body.

[0010] A lid according to a fifth aspect of the present invention is the lid according to the third aspect, wherein the protrusion extends in a third direction intersecting the first direction and the second direction in a front view of the lid.

[0011] An energy storage device according to a sixth aspect of the present invention comprises an electrode body and an exterior body that seals the electrode body, wherein the exterior body includes an exterior film that is wrapped around the electrode body to have an opening, a lid body that is placed in the opening, a first sealing portion in which facing surfaces of the exterior film are sealed, and a second sealing portion in which facing surfaces of the lid body and the exterior film are sealed, wherein the lid body includes a lid seal portion that is sealed to the exterior film and a protrusion that protrudes from the lid seal portion, and the first sealing portion is formed by sealing the facing surfaces of the exterior film with the protrusion sandwiched between them.

[0012] A manufacturing method for an electricity storage device according to a seventh aspect of the present invention is a manufacturing method for an electricity storage device comprising an electrode body and an exterior body that seals the electrode body, wherein the exterior body includes an exterior film that is wrapped around the electrode body to have an opening, a lid body that is placed in the opening, a first sealing portion in which facing surfaces of the exterior film are sealed, and a second sealing portion in which facing surfaces of the lid body and the exterior film are sealed, and the lid body includes a lid seal portion that is sealed with the exterior film and a protrusion that protrudes from the lid seal portion, and the manufacturing method for the electricity storage device includes a step of forming the first sealing portion, and in the step of forming the first sealing portion, the facing surfaces of the exterior film are sealed with the protrusion sandwiched between them. Effect of the Invention

[0013] According to the electricity storage device, the lid, and the method for manufacturing the electricity storage device of the present invention, the electrode assembly can be suitably sealed by the exterior assembly. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view of an electricity storage device according to an embodiment. [Diagram 2] 2 is a cross-sectional view showing a layer structure of an exterior film included in the electricity storage device of FIG. 1. [Diagram 3] FIG. 2 is a diagram showing the exterior film of the power storage device in FIG. 1 in an unfolded state. [Figure 4] Cross-sectional view taken along line D4-D4 in Figure 1. [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] 4 is a flowchart showing an example of a manufacturing process for the electricity storage device in FIG. [Figure 8] FIG. 11 is a cross-sectional view of a lid provided in an electricity storage device according to a modified example. [Figure 9] FIG. 13 is a cross-sectional view of a lid provided in an electricity storage device according to another modified example. [Figure 10] Table showing test results. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 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.

[0016] [1. First embodiment] <1-1. Configuration of the power storage device> FIG. 1 is a plan view that typically illustrates an electricity storage device 10 of a first embodiment. FIG. 2 is a cross-sectional view showing a layer structure of an exterior film 50 included in the electricity storage device 10 of FIG. 1. FIG. 3 is a view showing an exterior film 50 included in the electricity storage device 10 of FIG. 1 in an unfolded state. FIG. 4 is a cross-sectional view taken along line D4-D4 in FIG. 1. FIG. 5 is a side view of a lid body 60 included in the electricity storage device 10 of FIG. 1. FIG. 6 is a plan view of the lid body 60 of FIG. 5. In FIG. 1, FIG. 4 to FIG. 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 indicated by the arrows UDLRFB are common to the subsequent figures.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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 is wrapped around the electrode body 20 so as to have an opening 40A, and the lid body 60 is disposed on the side of the electrode body 20 so as to close the opening 40A.

[0021] 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.

[0022] The exterior film 50 is, for example, a laminate (laminate film) having a base layer 51, a barrier layer 52, and a heat-sealable resin layer 53 in this order. Note that the exterior film 50 does not need to include all of these layers, and for example, the barrier layer 52 may not be included. That is, the exterior film 50 may be made of any material that is flexible and easily bendable, and may be made of, for example, a resin film. Note that the exterior film 50 is preferably heat-sealable.

[0023] 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 20 to 150 μm, from the viewpoint of film strength.

[0024] The barrier layer 52 is bonded to the base layer 51 via, for example, an adhesive layer 54. The barrier layer 52 included in the exterior film 50 is made of, for example, aluminum foil from the viewpoints of processability such as moisture resistance and extensibility, and cost. The aluminum foil preferably contains iron from the viewpoints of packaging suitability and pinhole resistance when packaging the electrode body 20. The iron content in the aluminum foil is preferably 0.5 to 5.0 mass%, and more preferably 0.7 to 2.0 mass%. When the iron content is 0.5 mass% or more, the exterior film 50 can obtain packaging suitability, excellent pinhole resistance, and extensibility. In addition, when the iron content is 5.0 mass% or less, the exterior film 50 can obtain excellent flexibility. The barrier layer 52 may include a metal foil, a vapor deposition film, and a resin layer having barrier properties. Examples of the metal foil include aluminum alloy, stainless steel, titanium steel, and steel plate.

[0025] From the viewpoints of barrier properties, pinhole resistance, and packaging suitability, the thickness of the barrier layer 52 is, for example, preferably 15 to 100 μm, and more preferably 30 to 80 μm. When the thickness of the barrier layer 52 is 15 μm or more, the exterior film 50 is less likely to break even when stress is applied during packaging processing. When the thickness of the barrier layer 52 is 100 μm or less, the increase in mass of the exterior film 50 can be reduced, and a decrease in the weight energy density of the electricity storage device 10 can be suppressed.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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. 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 form 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 the first direction in a front view of the lid body 60. In this embodiment, the first direction and the second direction are perpendicular to each other in a front view of the lid body 60. The first direction and the second direction do not have to be perpendicular to each other in a front view of the lid body 60. The fourth seal surface 63D forms 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] In this embodiment, the second sealing portion 80 is formed by heat-sealing the heat-sealing 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-sealing 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-sealing resin layer 53 and the lid body 60 at the long side portion of the lid seal portion 63, that is, the lid seal portion 63 extending in the LR (width) direction in FIG. 1. The seal strength of the second sealing portion 80 is measured based on the distance of the second sealing portion 80 in the FB (depth) direction by pulling the exterior film 50 in the UD (up-down) direction in FIG. 1 relative to the lid body 60. The seal strength of the second sealing portion 80 in the case where the lid body 60 is divided into a plurality of parts including long sides and short sides is the seal strength at the long side portion of the lid seal portion 63 of the plurality of parts.

[0040] 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 150N / 15mm or less. A preferred range of the seal strength of the second sealing portion 80 is 40N / 15mm to 150N / 15mm, 50N / 15mm to 150N / 15mm, 60N / 15mm to 150N / 15mm, 70N / 15mm to 150N / 15mm, or 85N / 15mm to 150N / 15mm.

[0041] In this embodiment, the lid body 60 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, it is preferable that the protruding portion 68 is 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.

[0042] 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.

[0043] 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).

[0044] 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.

[0045] <1-2. Method for manufacturing 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.

[0046] 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. By completing the first step, the electrode terminals 30 and the electrodes of the electrode body 20 are electrically connected to each other.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] <1-3. Actions and Effects of Electricity Storage Devices> According to the electricity storage device 10, since the protrusion 68 is formed in the lid seal portion 63 of the lid body 60, a gap is unlikely to be formed between the exterior film 50 and the lid body 60 in the step of forming the first sealing portion 70. Therefore, the electrode body 20 can be suitably sealed by the exterior body 40.

[0051] [2. Modifications] The above-mentioned embodiments are examples of possible forms of the electricity storage device, the lid, and the manufacturing method of the electricity storage device according to the present invention, and are not intended to limit the forms. The electricity storage device, the lid, and the manufacturing method of the electricity storage device according to the present invention may take forms different from those exemplified in the embodiments. 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, some examples of modified embodiments are shown. Note that the following modified examples can be combined with each other as long as there is no technical contradiction.

[0052] <2-1> 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.

[0053] <2-2> In the electricity storage device 10 of the above embodiment, the configuration of the lid body 60 can be arbitrarily modified. As shown in FIG. 9, the lid body 60 may include a frame 60B that covers the lid body 60A. In this modification, for example, the material constituting the lid body 60A can be any material such as metal or resin. The material constituting the frame 60B is, for example, a resin that can be suitably sealed with the heat-sealable resin layer 53 of the exterior film 50. In this modification, the lid seal portion 63 and the protrusion 68 of the lid body 60 are formed in the frame 60B.

[0054] <2-3> 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.

[0055] <2-4> The electricity storage device 10 of the above embodiment may have an adhesive film disposed between the exterior film 50 and the lid body 60 in order to favorably bond the exterior film 50 and the lid body 60. In this modification, for example, the lid body 60 with the adhesive film attached 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 adhesive film is 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 adhesive film is configured to be wider than the lid seal portion 63 of the lid body 60 as a whole. In this case, the adhesive film can be easily bonded to the lid body 60. Furthermore, since the boundaries 64 to 67 of the lid seal portion 63 are covered by the adhesive film, the adhesion between the lid body 60 and the adhesive film is enhanced.

[0056] The adhesive film can be selected arbitrarily as long as it can bond the exterior film 50 and the lid 60. The adhesive film is preferably a laminate (laminate film) having at least a heat-sealable resin layer, a heat-resistant base layer, and a heat-sealable resin layer in this order. The specifications of the heat-sealable resin layer of the adhesive film can be the same as those of the heat-sealable resin layer 53. The materials constituting the heat-sealable resin layers on both sides of the adhesive film may be the same or different materials, and are appropriately selected according to the materials constituting the heat-sealable resin layer 53 of the exterior film 50 and the materials constituting the lid 60. The material constituting the heat-sealable resin layer of the adhesive film on the side bonded to the lid 60 is preferably an acid-modified polyolefin resin graft-modified with an acid such as maleic anhydride. The heat-sealable resin layer of the adhesive film on the side bonded to the exterior film 50 is preferably the same material as the material constituting the heat-sealable resin layer 53 of the exterior film 50.

[0057] The heat-resistant base layer may be any film made of a heat-resistant resin, such as a non-stretched or stretched film of polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polymethylpentene (registered trademark), polyacetal cyclic polyolefin, polyethylene, polypropylene, etc. Polyethylene terephthalate is particularly preferred because it is inexpensive and has high strength.

[0058] The adhesive film preferably has adhesiveness. When the second sealing portion 80 is formed with the adhesive film disposed between the exterior film 50 and the lid 60, the adhesive film is unlikely to be misaligned with respect to the lid 60 and the exterior film 50. By incorporating a tackifier resin into the heat-sealable resin layer of the adhesive film, the adhesive film 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.

[0059] <2-5> 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 .

[0060] 3. Working Examples The inventors of the present application conducted a test to confirm the sealing property of the electrode assembly by the exterior body for the electricity storage devices of the examples and the comparative examples. Note that, for the sake of convenience, the following description will be given with the same reference numerals as in the embodiment to the elements constituting the electricity storage devices of the examples and the comparative examples that are the same as in the embodiment.

[0061] In the test, the electricity storage devices of Examples 1 and 2 and the comparative example were manufactured, a part of the exterior body 40 was cut open, Ageless Seal Check Spray (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was sprayed onto the inside of the exterior body 40, and after about 5 minutes, the presence or absence of leakage of the check liquid from the second sealing portion 80 was visually confirmed. The specifications of the electricity storage devices of Examples 1 and 2 and the electricity storage device of the comparative example were as follows.

[0062] The electricity storage device of Example 1 has one protrusion 68 at boundary 64 of lid body 60. The electricity storage device of Example 1 does not have any protrusion 68 other than boundary 64 of lid body 60. The electricity storage device of Example 2 has one protrusion 68 at each of boundary 64, boundary 65, boundary 66, and boundary 67 of lid body 60. The electricity storage device of Example 2 does not have any protrusion 68 other than boundary 64, boundary 65, boundary 66, and boundary 67 of lid body 60. In the electricity storage device of the comparative example, lid body 60 does not have any protrusion 68.

[0063] The sealing conditions for the first sealed portion 70 of the electricity storage devices of Examples 1 and 2 and the comparative example were a temperature of 210°C, a time of 5 seconds, and a pressure of 0.5 MPa. The sealing conditions for the second sealed portion 80 of the electricity storage devices of Examples 1 and 2 and the comparative example were a temperature of 220°C, a time of 5 seconds, and a pressure of 0.4 MPa.

[0064] FIG. 10 is a table showing the test results. In the electricity storage devices of Examples 1 and 2, leakage of the check solution was not confirmed. That is, in the electricity storage devices of Examples 1 and 2, it was confirmed that no gap was formed between the exterior body 40 and the lid body 60. This is considered to be because the protrusion 68 is formed on the lid body 60 in the electricity storage devices of Examples 1 and 2. On the other hand, in the electricity storage device of the comparative example, leakage of the check solution was confirmed from the gap between the boundary 64 of the lid body 60 in the second sealing portion 80 and the first sealing portion 70 in particular. That is, it was confirmed that a gap was formed between the exterior body 40 and the lid body 60 in the electricity storage device of the comparative example. [Explanation of symbols]

[0065] 10: Energy storage device 20: Electrode body 40: Exterior body 40A: Opening 50: Exterior film 60: Lid 63: Lid seal part 63A: First seal surface 63B: Second seal surface 64 :Boundary 68: Protrusion

Claims

1. A lid used for an exterior body of an electricity storage device, the exterior body includes an exterior film that wraps the electrode body so as to have an opening, the lid body has a lid seal portion that is disposed at the opening and is sealed with the exterior film, The outer casing is a first sealing portion formed by sealing opposing surfaces of the exterior film; a second sealing portion formed by sealing an inner surface of the opening of the exterior film with the lid seal portion of the lid body facing the inner surface of the opening of the exterior film, The lid body is The lid sealing portion is provided with an adhesive film in advance, and the second sealing portion is sealed to the exterior film via the adhesive film, The first sealing portion has a protrusion at a position sandwiched between the opposing surfaces of the exterior film. Lid body.

2. The lid seal portion is a first sealing surface extending in a first direction in a front view of the lid; a second sealing surface extending in a second direction intersecting the first direction in a front view of the lid; a third sealing surface extending in the second direction in a front view of the lid; a fourth sealing surface extending in the first direction in a front view of the lid body. The lid according to claim 1 .

3. The protrusion is formed at the boundary between the first seal surface and the second seal surface. The lid according to claim 2.

4. The protrusion extends in the first direction or the second direction in a front view of the lid. The lid according to claim 3.

5. The protrusion extends in a third direction intersecting the first direction and the second direction in a front view of the lid. The lid according to claim 3.

6. An electrode body; an exterior body that seals the electrode body, The outer casing is an exterior film that wraps the electrode body so as to have an opening; a lid body having a lid seal portion disposed at the opening and sealed with the exterior film; a first sealing portion formed by sealing opposing surfaces of the exterior film; a second sealing portion formed by sealing an inner surface of the opening of the exterior film with the lid seal portion of the lid body facing the inner surface of the opening of the exterior film, The lid body is the lid seal portion is provided with an adhesive film in advance, and the second seal portion is sealed to the exterior film via the adhesive film and includes a protruding portion protruding from the lid seal portion; The first sealing portion is formed by sealing the facing surfaces of the exterior film with the protruding portion sandwiched between them. Energy storage device.

7. A method for manufacturing an electricity storage device including an electrode body and an exterior body that seals the electrode body, The outer casing is an exterior film that wraps the electrode body so as to have an opening; a lid body having a lid seal portion disposed at the opening and sealed with the exterior film; a first sealing portion formed by sealing opposing surfaces of the exterior film; a second sealing portion formed by sealing an inner surface of the opening of the exterior film with the lid seal portion of the lid body facing the inner surface of the opening of the exterior film, The lid body is the lid seal portion is provided with an adhesive film in advance, and the second seal portion is sealed to the exterior film via the adhesive film and includes a protruding portion protruding from the lid seal portion; The method for manufacturing the electricity storage device includes: forming the first sealing portion; In the step of forming the first sealing portion, the facing surfaces of the exterior film are sealed together with the protruding portion sandwiched therebetween. A method for manufacturing an electricity storage device.

8. A step of forming the second sealing portion, In the step of forming the second sealing portion, the lid body, to which the adhesive film has been previously adhered, is attached to the opening of the exterior body, and then the inner surfaces of the opening of the exterior film and the lid seal portion of the lid body, which face each other, are sealed with the adhesive film sandwiched between them. The method for manufacturing the electricity storage device according to claim 7 .

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