JP7816658B2 - Lid, electricity storage device, lid kit, lid unit, base part, first covering part, second covering part, and method for manufacturing electricity storage device - Google Patents

Description

The present invention relates to a lid body, an electricity storage device, a lid body kit, a lid unit, a base part, a first covering part, a second covering part, and a method for manufacturing an electricity storage device.

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 has an exterior film that encases the electrode assembly and a lid that is joined to the exterior film. The lid is made of a metal material.

Japanese Patent Application Laid-Open No. 2022-123686

In the above-mentioned energy storage device, in order to properly bond the exterior film and the lid, it is conceivable to cover the lid with a covering made of a resin material and then bond the covering to the exterior film. However, if the resin material is injection molded onto the lid, for example, there is a risk that the lid may deform. If the lid deforms, there is a risk, for example, that the sealing ability of the exterior body may be reduced.

The present invention aims to provide a lid body that is suppressed from deforming, an energy storage device equipped with this lid body, a lid body kit, a lid unit, a base part, a first covering part, a second covering part, and a method for manufacturing an energy storage device.

The lid body according to a first aspect of the present invention is a lid body used for the exterior of an energy storage device, and comprises a base part containing a conductive material and including a first surface and a second surface opposite the first surface, a first covering part containing a resin material and covering at least a portion of the first surface of the base part, and a second covering part containing a resin material and covering at least a portion of the second surface of the base part.

The lid body according to the second aspect of the present invention is a lid body according to the first aspect, which includes a portion where the first covering part and the second covering part come into contact.

The lid body according to the third aspect of the present invention is a lid body according to the first aspect, wherein the edge of the base part is sandwiched between the first covering part and the second covering part.

A lid body according to a fourth aspect of the present invention is a lid body according to any one of the first to third aspects, wherein the base part has a main portion, a wall portion protruding from the main portion, and an internal space defined by the wall portion, and the first covering part includes a storage portion that is housed in the internal space.

The lid body according to the fifth aspect of the present invention is a lid body according to any one of the first to fourth aspects, wherein the thickness of the base part is 5.0 mm or less.

The sixth aspect of the present invention relates to an energy storage device comprising an electrode body and an exterior body that seals the electrode body. The exterior body has an exterior film that wraps the electrode body and a lid that, together with the exterior film, seals the electrode body. The lid has a base part that includes a conductive material and has a first surface and a second surface opposite to the first surface, a first covering part that includes a resin material and covers at least a portion of the first surface of the base part, and a second covering part that includes a resin material and covers at least a portion of the second surface of the base part.

The lid kit according to the seventh aspect of the present invention is a lid kit for forming a lid to be used in the exterior of an energy storage device, and includes a base part containing a conductive material and including a first surface and a second surface opposite the first surface, a first covering part containing a resin material and covering at least a portion of the first surface of the base part, and a second covering part containing a resin material and covering at least a portion of the second surface of the base part.

The lid unit according to the eighth aspect of the present invention is a lid unit constituting a lid body used in the exterior of an energy storage device, and includes a base part containing a conductive material and including a first surface and a second surface opposite the first surface, and a first covering part containing a resin material and covering at least a portion of the first surface of the base part.

The lid unit according to the ninth aspect of the present invention is a lid unit constituting a lid body used in the exterior of an energy storage device, and includes a base part containing a conductive material and including a first surface and a second surface opposite the first surface, and a second covering part containing a resin material and covering at least a portion of the second surface of the base part.

The base part according to the tenth aspect of the present invention is a base part constituting a lid body used in the exterior of an energy storage device, the base part comprising a conductive material and having a first surface at least partially covered by a first covering part comprising a resin material, and a second surface opposite the first surface at least partially covered by a second covering part comprising a resin material.

The first covering part according to the eleventh aspect of the present invention is a first covering part constituting a lid body used in the exterior of an energy storage device, the lid body being constructed to include a conductive material and having a base part including a first surface and a second surface opposite the first surface, and the first covering part being constructed to include a resin material and configured to cover at least a portion of the first surface of the lid body.

The second covering part according to the twelfth aspect of the present invention is a second covering part constituting a lid body used in the exterior of an energy storage device, the lid body being constructed to include a conductive material and having a base part including a first surface and a second surface opposite the first surface, and the second covering part being constructed to include a resin material and configured to cover at least a portion of the second surface of the lid body.

A thirteenth aspect of the present invention relates to a method for manufacturing an electricity storage device, comprising: an electrode assembly; and an exterior body sealing the electrode assembly, wherein the exterior body has an exterior film wrapping the electrode assembly; and a lid body sealing the electrode assembly together with the exterior film, wherein the lid body includes a base part comprising a conductive material and including a first surface and a second surface opposite the first surface; a first covering part comprising a resin material and covering at least a portion of the first surface of the base part; and a second covering part comprising a resin material and covering at least a portion of the second surface of the base part. The method for manufacturing the electricity storage device includes a step of placing the lid body on the electrode assembly.

The lid body, electricity storage device, lid body kit, lid unit, base part, first covering part, second covering part, and method for manufacturing an electricity storage device related to the present invention can prevent the lid body from deforming.

FIG. 1 is a perspective view of an electricity storage device according to an embodiment. 1B is a diagram showing a method for measuring the seal strength of the second sealing portion of the electricity storage device of FIG. 1A. FIG. 1B is a cross-sectional view showing the layer structure of an exterior film included in the electricity storage device of FIG. 1A. FIG. 1B is a diagram showing a state in which an exterior film provided on the electricity storage device of FIG. 1A is unfolded. FIG. 1B is a perspective view of a base part of a lid body included in the electricity storage device of FIG. 1A. FIG. 1B is a perspective view of a first covering part of a lid provided in the electricity storage device of FIG. 1A. FIG. 1B is a perspective view of a second covering part of the lid provided in the electricity storage device of FIG. 1A. 1B is a cross-sectional view taken along line D7-D7 in FIG. 1A. FIG. 1B is a cross-sectional view of a lid unit constituting the lid body of FIG. 1A. FIG. 1B is a cross-sectional view of another lid unit that constitutes the lid body of FIG. 1A. 1B is a flowchart showing an example of a method for manufacturing the electricity storage device of FIG. 1A. FIG. 10 is a cross-sectional view of a lid according to a first modified example. FIG. 10 is a cross-sectional view of a lid according to a second modified example. FIG. 10 is a cross-sectional view of a lid according to a third modified example.

The following describes an energy storage device according to an embodiment of the present invention, with reference to the drawings. Note that in this specification, numerical ranges indicated by "to" mean "greater than or equal to" or "less than or equal to." For example, the expression "2 to 15 mm" means 2 mm or greater and 15 mm or less.

[Embodiment]
<1-1. Configuration of the electricity storage device>
FIG. 1A is a perspective view schematically illustrating an electricity storage device 10 according to an embodiment. FIG. 1B is a diagram illustrating a method for measuring the seal strength of a second sealed portion 100B of the electricity storage device 10 of FIG. 1A. FIG. 2 is a cross-sectional view illustrating the layer structure of an exterior film 50 included in the electricity storage device 10 of FIG. 1A. FIG. 3 is a diagram illustrating the exterior film 50 included in the electricity storage device 10 of FIG. 1A in an unfolded state. FIG. 4 is a perspective view of a base part 70 of a lid body 60 included in the electricity storage device 10 of FIG. 1A. FIG. 5 is a perspective view of a first covering part 80 of the lid body 60 included in the electricity storage device 10 of FIG. 1A. FIG. 6 is a perspective view of a second covering part 90 of the lid body 60 included in the electricity storage device 10 of FIG. 1A. FIG. 7 is a cross-sectional view taken along line D7-D7 in FIG. 1A. 1A, the direction of the arrow UD indicates the thickness direction of the power storage device 10, the direction of the arrow LR indicates the width direction of the power storage device 10, and the direction of the arrow FB indicates the depth direction of the power storage device 10. The directions indicated by the arrows UDLRFB are the same in the subsequent figures.

The energy 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) and a separator constituting an energy storage component such as a lithium-ion battery, capacitor, all-solid-state battery, semi-solid battery, quasi-solid battery, polymer battery, all-resin battery, lead-acid battery, nickel-metal hydride battery, nickel-cadmium battery, nickel-iron battery, nickel-zinc battery, silver oxide-zinc battery, metal-air battery, polyvalent cation battery, or capacitor. In this embodiment, the electrode body 20 has a substantially rectangular parallelepiped shape. Note that "substantially rectangular parallelepiped" includes not only a perfect rectangular parallelepiped, but also a solid that can be considered a rectangular parallelepiped by modifying the shape of a portion of its outer surface, for example. The electrode body 20 may have a cylindrical or polygonal prism shape, for example.

In this embodiment, the energy storage device 10 includes two electrode terminals 30. The electrode terminals 30 are metal terminals used for inputting and outputting power to and from the electrode body 20. The shape of the electrode terminals 30 can be selected arbitrarily. In the example shown in FIG. 1A, etc., the electrode terminals 30 are cylindrical. The electrode terminals 30 may also be rectangular prisms or plates. One end of the electrode terminals 30 is electrically connected to an electrode (positive or negative) included in the electrode body 20. The other end of the electrode terminals 30 protrudes outward from, for example, an edge of the outer casing 40. Note that the electrode terminals 30 only need to be capable of inputting and outputting power to and from the electrode body 20, and may not, for example, protrude from the outer casing 40. When the lid 60 described below is made of, for example, metal, the lid 60 may also function as the electrode terminals 30. In this case, the lid 60, which functions as an electrode terminal, may or may not protrude from the outer casing 40.

The metal material constituting the electrode terminal 30 is, for example, aluminum, nickel, or copper. For example, if the electrode body 20 is a lithium-ion battery, the electrode terminal 30 connected to the positive electrode is typically made of aluminum, and the electrode terminal 30 connected to the negative electrode is typically made of copper, nickel, or the like. Note that 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.

The exterior body 40 seals the electrode body 20. The exterior body 40 has an exterior film 50 and a lid body 60. The exterior film 50 encases the electrode body 20. In this embodiment, the exterior film 50 is wrapped around the electrode body 20. The lid body 60 is disposed to the side of the electrode body 20 in the FB direction. In another example, the electrode body 20 may be housed inside an exterior film 50 configured in a cylindrical shape so that openings are formed at both ends in the FB direction, and the openings may be closed by the lid body 60. In yet another example, the electrode body 20 connected to the lid body 60 may be housed inside an exterior film 50 configured in a cylindrical shape so that openings are formed, and the openings may be closed by the lid body 60.

For example, one method involves cold-forming the exterior film 50 to form a storage section (recess) for accommodating the electrode assembly 20. However, forming a deep storage section using this method is not necessarily easy. Attempting to form a deep storage section (recess) using cold-forming (e.g., a molding depth of 15 mm) increases the likelihood of pinholes or cracks occurring in the exterior film 50, resulting in reduced battery performance. On the other hand, the exterior body 40 seals the electrode assembly 20 by wrapping the exterior film 50 around the electrode assembly 20, making it easy to seal the electrode assembly 20 regardless of its thickness. To reduce the dead space between the electrode assembly 20 and the exterior film 50 and improve the volumetric energy density of the energy storage device 10, it is preferable for the exterior film 50 to be wrapped so that it contacts the outer surface of the electrode assembly 20. Furthermore, in all-solid-state batteries, it is necessary to apply high pressure uniformly from the exterior surface of the battery to maximize battery performance. Therefore, it is necessary to eliminate the space between the electrode assembly 20 and the exterior film 50. Therefore, it is preferable for the exterior film 50 to be wrapped so that it contacts the outer surface of the electrode assembly 20.

As shown in FIG. 2, the exterior film 50 is a laminate (laminate film) having, for example, a base material layer 51, a barrier layer 52, and a heat-sealable resin layer 53 in this order. It is not necessary for the exterior film 50 to include all of these layers; for example, it may not include the barrier layer 52. That is, the exterior film 50 may be made of any flexible, easily bendable material, such as a resin film. It is preferable that the exterior film 50 be heat-sealable. The innermost and outermost layers of the exterior film 50 may be heat-sealable resin layers 53. In this case, the exterior film 50 may encase the electrode body 20 and the lid body 60 by joining the outermost and innermost layers.

The exterior film 50 may be composed of a laminate having at least a barrier layer 52 and a heat-sealable resin layer 53 in this order. In this laminate, the base layer 51 is an optional layer, and the side of the barrier layer 52 opposite the heat-sealable resin layer 53 is the outermost layer, and the heat-sealable resin layer 53 is the innermost layer.

The overall thickness of the exterior film 50 can be selected as desired. From the standpoint of strength, it is preferable that the thickness of the exterior film 50 be 50 μm or more. From the standpoint of formability or conformability, it is preferable that the thickness of the exterior film 50 be 1200 μm or less. It is preferable that the thickness of the exterior film 50 be in the range of 50 μm or more and 1200 μm or less.

The substrate layer 51 included in the exterior film 50 provides heat resistance to the exterior film 50 and prevents pinholes from forming during processing or distribution. The substrate layer 51 may be composed of, for example, at least one layer of a stretched polyester resin layer and a stretched polyamide resin layer. For example, the substrate layer 51 may include at least one layer of a stretched polyester resin layer and a stretched polyamide resin layer, thereby protecting the barrier layer 52 during processing of the exterior film 50 and preventing breakage of the exterior film 50. Furthermore, from the perspective 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, from the perspective of achieving 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 substrate layer 51 may also be composed of both a stretched polyester resin layer and a stretched polyamide resin layer. From the viewpoint of film strength, the thickness of the substrate layer 51 is preferably, for example, 5 to 300 μm, and more preferably 5 to 150 μm.

The barrier layer 52 is a layer that at least prevents moisture penetration. The barrier layer 52 is bonded to the substrate layer 51 via, for example, an adhesive layer 54. Examples of the barrier layer 52 include metal foil, vapor-deposited films, and resin layers with barrier properties. Vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Resin layers include fluorine-containing resins such as polyvinylidene chloride, polymers based on chlorotrifluoroethylene (CTFE), polymers based on tetrafluoroethylene (TFE), polymers containing fluoroalkyl groups, and polymers based on fluoroalkyl units, as well as ethylene-vinyl alcohol copolymers. The barrier layer 52 can also be a resin film comprising at least one of these vapor-deposited films and resin layers. The barrier layer 52 may be formed of multiple layers. Preferably, the barrier layer 52 includes a layer composed 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 metal material contains at least one of an aluminum alloy foil and a stainless steel foil.

In the barrier layer 52, layers made of the aforementioned metallic materials may contain recycled metallic materials. Examples of recycled metallic materials include recycled aluminum alloys, stainless steel, titanium steel, and steel plate. These recycled materials can be obtained by known methods. Recycled aluminum alloys can be obtained, for example, by the manufacturing method described in International Publication No. 2022/092231. The barrier layer 52 may be made entirely of recycled materials, or may be made of a mixture of recycled and virgin materials. Note that recycled metallic materials refer to metallic materials that have been made reusable by collecting, isolating, and refining various products used in the market or waste from manufacturing processes. Furthermore, virgin metallic materials refer to new metallic materials refined from natural metallic resources (raw materials) and are not recycled materials.

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. From the viewpoint of further improving formability or conformability, it is preferable that the aluminum alloy foil be an iron-containing aluminum alloy foil. In the iron-containing aluminum alloy foil (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. An iron content of 0.1% by mass or more can result in an exterior film 50 with better formability. An iron content of 9.0% by mass or less can result in an exterior film 50 with better flexibility. Examples of soft aluminum alloy foils include aluminum alloy foils having a composition specified in JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Silicon, magnesium, copper, manganese, and the like may also be added as needed. Softening can be achieved by annealing or other methods. From the perspective of improving the mechanical strength of the exterior film 50, the aluminum alloy foil is preferably a hard aluminum alloy foil made of, for example, a work-hardened aluminum alloy. Examples of hard aluminum alloy foils include aluminum alloy foils having a composition specified in JIS H4160:1994 A8021H-H18, JIS H4160:1994 A8079H-H18, JIS H4000:2014 A8021P-H14, or JIS H4000:2014 A8079P-H14. From the viewpoint of improving the mechanical strength of the exterior film 50, the aluminum alloy foil is preferably an aluminum alloy foil containing magnesium. In the aluminum alloy foil containing magnesium (100% by mass), the magnesium content is preferably 0.2 to 5.6% by mass, and more preferably 0.2 to 3.0% by mass. Examples of aluminum alloy foils containing magnesium include aluminum alloy foils having compositions specified in JIS H4000:2017 A5005P-O, JIS H4000:2017 A5050P-O, and JIS H4000:2017 A5052P-O. The aluminum alloy foil is also preferably an aluminum alloy foil containing manganese. In the aluminum alloy foil containing manganese (100% by mass), the manganese content is preferably 0.3 to 1.5% by mass, and more preferably 1.0 to 1.5% by mass. Examples of aluminum alloy foils containing manganese include aluminum alloy foils having compositions defined by JIS H4000: 2017 A3003P-O, JIS H4000: 2017 A3103P-O, JIS H4000: 2017 A3004P-O, and JIS H4000: 2017 A3104P-O.

Furthermore, examples of stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation hardened stainless steel foils. Furthermore, from the viewpoint of providing an exterior film 50 with excellent formability, it is preferable that the stainless steel foil be made of austenitic stainless steel.

Specific examples of austenitic stainless steels that make up the stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred.

In the case of metal foil, the thickness of the barrier layer 52 should be sufficient to at least function as a barrier layer that prevents moisture penetration, and can be, for example, approximately 5 to 1000 μm. The thickness of the barrier layer 52 is preferably approximately 85 μm or less, more preferably approximately 50 μm or less, even more preferably approximately 40 μm or less, and particularly preferably approximately 35 μm or less. The thickness of the barrier layer 52 is preferably approximately 9.0 μm or more, more preferably approximately 20 μm or more, and more preferably approximately 25 μm or more. Preferred ranges for the thickness of the barrier layer 52 include about 9.0 to 1000 μm, about 9.0 to 1000 μm, about 9.0 to 1000 μm, about 9.0 to 1000 μm, 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 aluminum alloy foil, the above-mentioned ranges are particularly preferred. 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. Preferred ranges are approximately 35 to 200 μm, approximately 35 to 85 μm, approximately 35 to 75 μm, approximately 35 to 70 μm, approximately 45 to 200 μm, approximately 45 to 85 μm, approximately 45 to 75 μm, approximately 45 to 70 μm, approximately 50 to 200 μm, approximately 50 to 85 μm, approximately 50 to 75 μm, approximately 50 to 70 μm, approximately 55 to 200 μm, approximately 55 to 85 μm, approximately 55 to 75 μm, and approximately 55 to 70 μm. The high formability of the exterior film 50 facilitates deep drawing, which can contribute to increasing the capacity of the electricity storage device. Furthermore, while increasing the capacity of the electricity storage device increases the weight of the electricity storage device, increasing the rigidity of the exterior film 50 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.

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

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

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 provides heat-sealing properties to the exterior film 50. Examples of the heat-sealable resin layer 53 include resin films made of polyester resins such as polyethylene terephthalate resin and polybutylene terephthalate resin, polyolefin resins such as polyethylene resin and polypropylene resin, or acid-modified polyolefin resins obtained by graft-modifying these polyolefin resins with an acid such as maleic anhydride. From the standpoint of sealability and strength, the thickness of the heat-sealable resin layer 53 is preferably, for example, 20 to 1000 μm, and more preferably 40 to 150 μm.

The exterior film 50 preferably has one or more layers with buffering properties (hereinafter referred to as "buffer layers") 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 layer 51, or the base 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 layer 51, the barrier layer 52, etc.

The material constituting the buffer layer can be selected from any material with cushioning properties. Examples of materials with cushioning properties include rubber, nonwoven fabric, and foam sheets. Examples of rubber include natural rubber, fluororubber, and silicone rubber. The rubber hardness is preferably approximately 20 to 90. The material constituting the nonwoven fabric is preferably a material with excellent heat resistance. When the buffer layer is made of nonwoven fabric, the lower limit of the buffer layer's thickness is preferably 100 μm, more preferably 200 μm, and even more preferably 1000 μm. When the buffer layer is made of nonwoven fabric, the upper limit of the buffer layer's thickness is preferably 5000 μm, and even more preferably 3000 μm. The thickness of the buffer layer is preferably in the range of 100 μm to 5000 μm, 100 μm to 3000 μm, 200 μm to 5000 μm, 200 μm to 3000 μm, 1000 μm to 5000 μm, or 1000 μm to 3000 μm, with the most preferred range being 1000 μm to 3000 μm.

When the buffer layer is made of rubber, the lower limit of the buffer layer thickness is preferably 0.5 mm, more preferably 1.0 mm. When the buffer layer is made of rubber, the upper limit of the buffer layer thickness is preferably 10 mm, more preferably 5.0 mm, and even more preferably 2.0 mm. When the buffer layer is made of rubber, the preferred ranges of the buffer layer thickness are 1.0 mm to 2.0 mm, 1.0 mm to 5.0 mm, 1.0 mm to 10 mm, 0.5 mm to 2.0 mm, 0.5 mm to 5.0 mm, and 0.5 mm to 10 mm.

If the exterior film 50 has a buffer layer, the buffer layer acts as a cushion, preventing the exterior film 50 from being damaged by impact when the energy storage device 10 is dropped or by handling during manufacturing of the energy storage device 10.

The lid body 60 has a base part 70, a first covering part 80, and a second covering part 90.

The base part 70 is composed of a conductive material. "Composed of a conductive material" means that, when the entire material constituting the base part 70 is taken as 100% by mass, the content of the conductive material is 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. In other words, the material constituting the base part 70 can contain materials other than the conductive material in addition to the conductive material. It is preferable that the base part 70 composed of a conductive material has the corrosion-resistant coating described for the barrier layer 52.

The conductive material constituting the base part 70 is, for example, a metal material. The metal material constituting the base part 70 is, for example, aluminum, aluminum alloy, nickel, copper, or a copper alloy. For example, if the electrode body 20 is a lithium-ion battery, the base part 70 connected to the positive electrode is preferably made of aluminum or an aluminum alloy. The base part 70 connected to the negative electrode is preferably made of nickel, copper, or a copper alloy. The material constituting the base part 70 connected to the negative electrode may be nickel-plated copper. The material constituting the base part 70 may also include recycled metal materials.

The base part 70 may be a film or a metal molded product. When the base part 70 is described as a metal molded product, this does not include an embodiment in which the base part 70 is composed solely of a film as defined by the JIS (Japanese Industrial Standards) [Packaging Terminology] standard.

The base part 70 has a main portion 71, a wall portion 72, and an internal space 73.

The outer shape of the main portion 71 can be selected arbitrarily as long as it can seal the electrode body 20. In the example shown in Figure 4, etc., the outer shape of the main portion 71 is rectangular. The outer shape of the main portion 71 may also be circular, elliptical, square, triangular, or a polygon with pentagons or more sides. The main portion 71 has a first surface 71A and a second surface 71B. The first surface 71A faces the electrode body 20 via the first covering part 80. The second surface 71B is the surface opposite the first surface 71A in the FB direction. The second surface 71B faces the external space via the second covering part 90. The lid body 60 may be positioned so that the first surface 71A faces the external space, in other words, so that the second surface 71B faces the second covering part 90.

The main portion 71 has a hole 71Z formed through the first surface 71A and the second surface 71B. An electrode terminal 30 is inserted into the hole 71Z. To prevent electrical conduction between the main portion 71 and the electrode terminal 30, it is preferable to place an insulating member 110 (see Figure 7) in at least the hole 71Z.

The wall portion 72 protrudes from the outer peripheral edge of the main portion 71. The direction in which the wall portion 72 protrudes can be selected arbitrarily. In the example shown in Figure 4, etc., the wall portion 72 protrudes from the outer peripheral edge of the main portion 71 toward the electrode body 20 in the FB direction. The wall portion 72 may also protrude from the outer peripheral edge of the main portion 71 in the opposite direction to the electrode body 20, in other words, toward the external space, in the FB direction. The wall portion 72 may also protrude from the outer peripheral edge of the main portion 71 in a direction intersecting the FB direction when viewed from the side of the lid body 60.

The wall portion 72 has a first wall surface 72X and a second wall surface 72Y. The first wall surface 72X is the surface covered by the second covering part 90. The second wall surface 72Y is the surface opposite the first wall surface 72X. The second wall surface 72Y is the surface covered by the first covering part 80.

The wall portion 72 includes a first wall portion 72A, a second wall portion 72B, a third wall portion 72C, and a fourth wall portion 72D. The first wall portion 72A extends in a first direction (in this embodiment, the LR direction) when the lid body 60 is viewed from the front. The second wall portion 72B and the third wall portion 72C are connected to the first wall portion 72A and the fourth wall portion 72D. The second wall portion 72B and the third wall portion 72C extend in a second direction (in this embodiment, the UD direction) that intersects with the first direction when the lid body 60 is viewed from the front. In this embodiment, the first direction and the second direction are orthogonal when the lid body 60 is viewed from the front. The first direction and the second direction do not have to be orthogonal when the lid body 60 is viewed from the front. The fourth wall portion 72D extends in a first direction (LR direction in this embodiment) when the cover body 60 is viewed from the front.

In this embodiment, the thicknesses of the first to fourth wall portions 72A to 72D are substantially constant in the FB direction. The thicknesses of the first to fourth wall portions 72A to 72D may vary in the FB direction. For example, at least one of the first to fourth wall portions 72A to 72D may have a tapered shape in which the thickness increases or decreases in the FB direction as the wall portion approaches the electrode assembly 20. If the first to fourth wall portions 72A to 72D have a tapered shape, the tapered shape preferably increases in thickness as the wall portion approaches the electrode assembly 20, from the viewpoint of suppressing an increase in the internal pressure of the exterior body 40. From the viewpoint of suppressing a decrease in the strength of the lid body 60, it is preferable that the first and fourth wall portions 72A and 72D, which are longer in the LR direction, have a constant thickness in the FB direction, in other words, do not have a tapered shape.

The wall portion 72 further includes boundaries 72E, 72F, 72G, and 72H. Boundary 72E is the boundary between the first wall portion 72A and the second wall portion 72B. Boundary 72F is the boundary between the first wall portion 72A and the third wall portion 72C. Boundary 72G is the boundary between the fourth wall portion 72D and the second wall portion 72B. Boundary 72H is the boundary between the fourth wall portion 72D and the third wall portion 72C. The shapes of the boundaries 72E to 72H may be angular, or may be rounded by applying a rounded edge. In this embodiment, the boundaries 72E to 72H are angular. If the shapes of the boundaries 72E to 72H are rounded, it is preferable that the radius of curvature of the boundaries 72E to 72H be in the range of 0 mm to 2.0 mm.

The internal space 73 is defined by the first surface 71A of the main portion 71 and the second wall surface 72Y of the wall portion 72. A portion of the first covering part 80 is accommodated in the internal space 73.

The thickness of the base part 70 can be selected arbitrarily. If the base part 70 is a film, the thickness of the base part 70 is preferably 9 μm or more from the viewpoint of preventing damage to the base part 70 or preventing the occurrence of pinholes. If the base part 70 is a film, the thickness of the base part 70 is preferably 0.2 mm or less from the viewpoint of suitable molding. If the base part 70 is a film, the preferred range for the thickness of the base part 70 is 9.0 μm or more and 0.2 mm or less. The thicknesses of the first wall portion 72A and the fourth wall portion 72D are measured in the UD direction. The thicknesses of the second wall portion 72B and the third wall portion 72C are measured in the LR direction. The thickness of the main portion 71 is measured in the FB direction.

When the base part 70 is a metal molded product, from the viewpoint of preventing deformation of the lid body 60 when an external force is applied to the lid body 60, the thickness of the base part 70 is preferably 0.2 mm or more, and more preferably 0.5 mm or more. When the base part 70 is a metal molded product, from the viewpoint of reducing the weight of the lid body 60, the thickness of the base part 70 is preferably 5.0 mm or less, and more preferably 2.0 mm or less. When the base part 70 is a metal molded product, the preferred range of the thickness of the base part 70 is 0.2 mm or more to 5.0 mm or less, 0.2 mm or more to 2.0 mm or less, 0.5 mm or more to 5.0 mm or less, or 0.5 mm or more to 2.0 mm or less. Note that if the thickness of the base part 70 varies depending on the portion, the thickness of the base part 70 is the thickness of the thickest portion. From the viewpoint of reducing the weight of the lid body 60, the thickness of the base part 70 is preferably thinner than at least one of the thicknesses of the first covering part 80 and the second covering part 90. It is further preferable that the thickness of the base part 70 is thinner than the thickness of the first covering part 80 and the thickness of the second covering part 90. The thicknesses of the first wall portion 72A and the fourth wall portion 72D are measured in the UD direction. The thicknesses of the second wall portion 72B and the third wall portion 72C are measured in the LR direction. The thickness of the main portion 71 is measured in the FB direction.

The width of the base part 70 in the LR direction can be selected arbitrarily. If the base part 70 is a film, it is preferable that the width of the base part 70 in the LR direction be 10 mm or more. If the base part 70 is a film, it is preferable that the width of the base part 70 in the LR direction be 500 mm or less. If the base part 70 is a film, the preferred range for the width of the base part 70 in the LR direction is 10 mm or more and 500 mm or less.

The UD height of the base part 70 can be selected arbitrarily. If the base part 70 is a film, it is preferable that the UD height of the base part 70 be 10 mm or more. If the base part 70 is a film, it is preferable that the UD height of the base part 70 be 500 mm or less. If the base part 70 is a film, the preferred range for the UD height of the base part 70 is 10 mm or more and 500 mm or less.

The first covering part 80 covers at least a portion of the first surface 71A of the base part 70. In this embodiment, the first covering part 80 covers the entire first surface 71A.

The first covering part 80 is composed of a resin material. Here, "composed of a resin material" means that, when the total mass of the materials constituting the first covering part 80 is taken as 100 mass%, the resin material content is 50 mass% or more, preferably 80 mass% or more, more preferably 90 mass% or more, and even more preferably 95 mass% or more. In other words, the material constituting the first covering part 80 can contain materials other than resin materials in addition to resin materials.

Specific examples of resins include thermoplastic resins such as polyester, polyolefin, polyamide, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenolic resin, as well as modified versions of these resins. The resin material may also be a mixture of these resins, a copolymer, or a modified copolymer. Among these, heat-sealable resins such as polyester and polyolefin are preferred, with polyolefin being more preferred. When the resin material is resin, the first covering part 80 may be molded using any molding method or manufactured by cutting.

The resin material contained in the material constituting the first covering part 80 is preferably an olefin-based random copolymer, more preferably a resin containing a polyolefin skeleton as its main component, even more preferably a polyolefin as its main component, and even more preferably a polypropylene as its main component. The polyolefin may be an acid-modified polyolefin. The resin material contained in the material constituting the first covering part 80 preferably contains multiple types of amide-based lubricants. Furthermore, the resin material contained in the material constituting the first covering part 80 preferably contains, in addition to saturated fatty acid amides, multiple types of amide-based lubricants that further contain unsaturated fatty acid amides. The resin material contained in the material constituting the first covering part 80 may be a polyolefin resin to which a propylene-based elastomer having a melting point higher than 150°C has been added. Note that a "main component" refers to a material that accounts for, for example, 35% by weight or more, 50% by weight or more, 90% by weight or more, or 95% by weight or more of the materials contained in the constituent elements.

Specific examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyesters. Copolymer polyesters include those in which ethylene terephthalate is the predominant repeating unit. Specific examples include copolymer polyesters in which ethylene terephthalate is the predominant repeating unit polymerized with ethylene isophthalate (hereinafter abbreviated as polyethylene (terephthalate/isophthalate)), polyethylene (terephthalate/adipate), polyethylene (terephthalate/sodium sulfoisophthalate), polyethylene (terephthalate/sodium isophthalate), polyethylene (terephthalate/phenyl dicarboxylate), and polyethylene (terephthalate/decane dicarboxylate). Among these, polybutylene terephthalate is preferred as the resin material, due to its enhanced heat resistance and pressure resistance.

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, polypropylene block copolymers (e.g., block copolymers of propylene and ethylene), and polypropylene random copolymers (e.g., random copolymers of propylene and ethylene); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. When polyolefin resins are copolymers, they may be block copolymers or random copolymers. Among these, polypropylene is preferred as the resin material due to its excellent heat-sealing properties and electrolyte resistance.

The resin used as the resin material may contain a filler as needed. Specific examples of fillers include glass beads, graphite, glass fiber, and carbon fiber. By including the filler in the resin used as the resin material, the first coated part 80 can be made more resistant to deformation due to temperature changes.

The melt mass flow rate of the resin material contained in the material constituting the first coated part 80 is preferably in the range of 1 g/10 min to 100 g/10 min, and more preferably in the range of 5 g/10 min to 80 g/10 min. The melt mass flow rate is measured in accordance with JIS K7210-1:2014. The melt mass flow rate is measured at 230°C.

The first covering part 80 may be a film or a resin molded product. When the first covering part 80 is described as a resin molded product, this does not include a case in which the first covering part 80 is composed solely of a film as defined by the JIS (Japanese Industrial Standards) [Packaging Terminology] standard.

The first covering part 80 includes a storage portion 80A and a flange portion 80B. The storage portion 80A is stored in the internal space 73 of the base part 70. The storage portion 80A has a main portion 81, a wall portion 82, and an internal space 83. The first covering part 80 may or may not be joined to the base part 70. The first covering part 80 may omit the flange portion 80B. In other words, the first covering part 80 may be composed of only the storage portion 80A.

The outer shape of the main portion 81 can be selected arbitrarily as long as it can cover at least a portion of the first surface 71A of the base part 70. In the example shown in Figure 5, etc., the outer shape of the main portion 81 is rectangular. The outer shape of the main portion 81 may be circular, elliptical, square, triangular, or a polygon with pentagons or more sides. The main portion 81 has a first surface 81A and a second surface 81B. The first surface 81A faces the electrode body 20. The second surface 81B is the surface opposite the first surface 81A in the FB direction. The second surface 81B faces the first surface 71A of the base part 70. The main portion 81 has a hole 81Z that penetrates the first surface 81A and the second surface 81B. The electrode terminal 30 is inserted into the hole 81Z.

The wall portion 82 protrudes from the outer peripheral edge of the main portion 81. In the example shown in Figure 5 etc., the wall portion 82 protrudes from the outer peripheral edge of the main portion 81 toward the electrode body 20 in the FB direction. The wall portion 82 has a first wall surface 82X and a second wall surface 82Y. The first wall surface 82X is the surface that contacts the second wall surface 72Y of the base part 70. The second wall surface 82Y is the surface opposite the first wall surface 82X.

The wall portion 82 includes a first wall portion 82A, a second wall portion 82B, a third wall portion 82C, and a fourth wall portion 82D. The first wall portion 82A extends along the first wall portion 72A. The second wall portion 82B and the third wall portion 82C are connected to the first wall portion 82A and the fourth wall portion 82D. The second wall portion 82B extends along the second wall portion 72B. The third wall portion 82C extends along the third wall portion 72C. The fourth wall portion 82D extends along the fourth wall portion 72D.

In this embodiment, the thicknesses of the first to fourth wall portions 82A to 82D are substantially constant in the FB direction. The thicknesses of the first to fourth wall portions 82A to 82D may vary in the FB direction. For example, at least one of the first to fourth wall portions 82A to 82D may have a tapered shape in which the thickness increases or decreases in the FB direction as the wall portion approaches the electrode assembly 20. If the first to fourth wall portions 82A to 82D have a tapered shape, the tapered shape preferably increases in thickness as the wall portion approaches the electrode assembly 20, from the viewpoint of suppressing an increase in internal pressure of the exterior body 40. From the viewpoint of suppressing a decrease in the strength of the lid body 60, it is preferable that the first and fourth wall portions 82A and 82D, which are longer in the LR direction, have a constant thickness in the FB direction, in other words, do not have a tapered shape. The thicknesses of the first wall portion 82A and the fourth wall portion 82D are measured in the UD direction, and the thicknesses of the second wall portion 82B and the third wall portion 82C are measured in the LR direction.

The wall portion 82 further includes boundaries 82E, 82F, 82G, and 82H. Boundary 82E is the boundary between the first wall portion 82A and the second wall portion 82B. Boundary 82F is the boundary between the first wall portion 82A and the third wall portion 82C. Boundary 82G is the boundary between the fourth wall portion 82D and the second wall portion 82B. Boundary 82H is the boundary between the fourth wall portion 82D and the third wall portion 82C. The shapes of the boundaries 82E-82H may be angular, or may be rounded by applying a rounded edge. In this embodiment, the boundaries 82E-82H are angular. If the shapes of the boundaries 82E-82H are rounded, it is preferable that the radius of curvature of the boundaries 82E-82H be in the range of more than 0 mm and not more than 2.0 mm.

The internal space 83 is defined by the first surface 81A of the main portion 81 and the second wall surface 82Y of the wall portion 82.

The flange portion 80B protrudes from the end face of the wall portion 82 opposite the main portion 81 in the FB direction. The flange portion 80B covers the end face of the wall portion 72 of the base part 70 opposite the main portion 71 in the FB direction.

The thickness of the first covering part 80 can be selected arbitrarily. If the first covering part 80 is a film, it is preferable that the thickness of the first covering part 80 be 0.3 mm or more from the viewpoint of preventing damage to the first covering part 80 or preventing the occurrence of pinholes. If the first covering part 80 is a film, it is preferable that the thickness of the first covering part 80 be 3.0 mm or less from the viewpoint of formability. If the first covering part 80 is a film, the preferred range for the thickness of the first covering part 80 is 0.3 mm or more and 3.0 mm or less. The thicknesses of the first wall portion 82A and the fourth wall portion 82D are the thickness in the UD direction. The thicknesses of the second wall portion 82B and the third wall portion 82C are the thickness in the LR direction. The thickness of the main portion 81 and the flange portion 80B are the thickness in the FB direction.

When the first covering part 80 is a resin molded product, the thickness of the first covering part 80 is preferably 1.0 mm or more, from the viewpoint of preventing deformation of the lid body 60 when an external force is applied to the lid body 60. When the first covering part 80 is a resin molded product, the thickness of the first covering part 80 is preferably 3.0 mm or less, from the viewpoint of reducing the weight of the lid body 60. When the first covering part 80 is a resin molded product, the preferred range of the thickness of the first covering part 80 is 1.0 mm or more and 3.0 mm or less. Note that when the thickness of the first covering part 80 varies depending on the portion, the thickness of the first covering part 80 is the thickness of the thickest portion. The thicknesses of the first wall portion 82A and the fourth wall portion 82D are the thickness in the UD direction. The thicknesses of the second wall portion 82B and the third wall portion 82C are the thickness in the LR direction. The thickness of the main portion 81 and the flange portion 80B are the thickness in the FB direction.

The second covering part 90 covers at least a portion of the second surface 71B of the base part 70. In this embodiment, the second covering part 90 covers the entire second surface 71B. The second covering part 90 is joined to the base part 70.

The second covering part 90 is composed of a resin material. The definition of "composed of a resin material" for the second covering part 90 is the same as for the first covering part 80. The specifications of the resin material contained in the material constituting the second covering part 90 are the same as those of the resin material contained in the material constituting the first covering part 80. The second covering part 90 may be a film or a resin molded product. When the second covering part 90 is referred to as a resin molded product, this does not include a case in which the second covering part 90 is composed solely of a film as defined by the JIS (Japanese Industrial Standards) "Packaging Terminology" standard. Note that the resin material contained in the material constituting the first covering part 80 and the resin material contained in the material constituting the second covering part 90 may be the same or different. When the resin material constituting the second covering part 90 is resin, the second covering part 90 may be molded using any molding method or may be manufactured by cutting.

The second covering part 90 has a shape similar to the base part 70. The second covering part 90 has a main portion 91, a wall portion 92, and an internal space 93.

The outer shape of the main portion 91 can be selected arbitrarily as long as it can cover at least a portion of the second surface 71B of the base part 70. In the example shown in FIG. 6 etc., the outer shape of the main portion 91 is rectangular. The outer shape of the main portion 91 may also be circular, elliptical, square, triangular, or a polygon with pentagons or more sides. The main portion 91 has a first surface 91A and a second surface 91B. The first surface 91A faces the second surface 71B of the base part 70. The second surface 91B is the surface opposite the first surface 91A in the FB direction. The second surface 91B faces the external space. The lid body 60 may be positioned so that the first surface 91A faces the external space, in other words, so that the second surface 91B faces the electrode body 20. The main portion 91 has a hole 91Z formed through the first surface 91A and the second surface 91B. The electrode terminal 30 is inserted into the hole 91Z.

The wall portion 92 protrudes from the outer peripheral edge of the main portion 91 so as to cover the first wall surface 72X of the wall portion 72 of the base part 70. The wall portion 92 has a first wall surface 92X and a second wall surface 92Y. The first wall surface 92X is the surface that is joined to the heat-sealable resin layer 53 of the exterior film 50. The second wall surface 92Y is the surface opposite the first wall surface 92X. The second wall surface 92Y covers the second wall surface 72Y of the wall portion 72 of the base part 70.

The wall portion 92 includes a first wall portion 92A, a second wall portion 92B, a third wall portion 92C, and a fourth wall portion 92D. The first wall portion 92A forms the top surface of the lid body 60. The first wall portion 92A extends along the first wall portion 72A of the base part 70. The second wall portion 92B and the third wall portion 92C are connected to the first wall portion 92A and the fourth wall portion 92D, and form the side surfaces of the lid body 60. The second wall portion 92B extends along the second wall portion 72B of the base part 70. The third wall portion 93C extends along the third wall portion 72C of the base part 70. The fourth wall portion 92D extends along the fourth wall portion 72D of the base part 70.

In this embodiment, the thicknesses of the first to fourth wall portions 92A to 92D are substantially constant in the FB direction. The thicknesses of the first to fourth wall portions 92A to 92D may vary in the FB direction. For example, at least one of the first to fourth wall portions 92A to 92D may have a tapered shape in which the thickness increases or decreases in the FB direction as the wall portion approaches the electrode body 20. If the first to fourth wall portions 92A to 92D have a tapered shape, the tapered shape preferably increases in thickness as the wall portion approaches the electrode body 20, from the viewpoint of suppressing an increase in internal pressure of the exterior body 40. From the viewpoint of suppressing a decrease in the strength of the lid body 60, it is preferable that the first and fourth wall portions 92A and 92D, which are longer in the LR direction, have a constant thickness in the FB direction, in other words, do not have a tapered shape. The thicknesses of the first wall portion 92A and the fourth wall portion 92D are measured in the UD direction, and the thicknesses of the second wall portion 92B and the third wall portion 92C are measured in the LR direction.

The wall portion 92 further includes boundaries 92E, 92F, 92G, and 92H. The boundary 92E is the boundary between the first wall portion 92A and the second wall portion 92B. The boundary 92F is the boundary between the first wall portion 92A and the third wall portion 92C. The boundary 92G is the boundary between the fourth wall portion 92D and the second wall portion 92B. The boundary 92H is the boundary between the fourth wall portion 92D and the third wall portion 92C. The shapes of the boundaries 92E-92H may be angular, or may be rounded by applying a rounded edge. In this embodiment, the boundaries 92E-92H are angular. If the shapes of the boundaries 92E-92H are rounded, it is preferable that the radius of curvature of the boundaries 92E-92H be in the range of more than 0 mm and not more than 2.0 mm.

The end face of the wall portion 92 opposite the main portion 91 in the FB direction contacts the flange portion 80B of the first covering part 80. Therefore, the boundary 60X between the first covering part 80 and the second covering part 90 can be confirmed in the lid body 60. The boundary 60X can be observed using a scanning electron microscope or a scanning transmission electron microscope. Even if the resin material contained in the material constituting the first covering part 80 and the resin material contained in the material constituting the second covering part 90 are the same material, the boundary 60X is observed using a scanning electron microscope or a scanning transmission electron microscope because the sea-island shape or lamellar shape at the boundary 60X is different. Note that "different sea-island shapes" includes cases where the sea-island shapes differ only due to differences in the vertical or horizontal dimensions of the sea-island shapes, even if the components are the same. "Different lamellar shapes" also includes cases where the lamellae are discontinuous or have different orientations, even if the dimensions such as thinness and length of the lamellae are the same.

The internal space 93 is defined by the first surface 91A of the main portion 91 and the second wall surface 92Y of the wall portion 92. The internal space 93 accommodates the entire base part 70 and a portion of the first covering part 80. The flange portion 80B of the first covering part 80 is exposed from the internal space 93.

The thickness of the second covering part 90 can be selected arbitrarily. Whether the second covering part is a film or a resin molded product, the thickness of the second covering part 90 is preferably 50 μm or more from the viewpoint of properly bonding with the exterior film 50. Whether the second covering part is a film or a resin molded product, the thickness of the second covering part 90 is preferably 2.0 mm or less from the viewpoint of reducing the weight of the lid body 60. The preferred range of the thickness of the second covering part 90 is 50 μm or more and 2.0 mm or less. Note that if the thickness of the second covering part 90 varies depending on the portion, the thickness of the second covering part 90 is the thickness of the thickest portion. The thicknesses of the first wall portion 92A and the fourth wall portion 92D are the thickness in the UD direction. The thicknesses of the second wall portion 92B and the third wall portion 92C are the thickness in the LR direction. The thickness of the main portion 91 is the thickness in the FB direction.

The manufacturing method of the lid body 60 can be selected arbitrarily. Below, an example of a manufacturing method of the lid body 60 is described.

In the first example, the manufacturing method for the lid body 60 includes a first injection molding process and a second injection molding process. In the first injection molding process, a first covering part 80 is injection molded onto a base part 70. The object in which the first covering part 80 is injection molded onto the base part 70 corresponds to the lid unit 130. In the second injection molding process, a second covering part 90 is injection molded onto the lid unit 130. In the first example, the amount of resin used in the first injection molding process is smaller than when the first covering part 80 and the second covering part 90 are injection molded onto the base part 70 at the same time. Therefore, even if the thickness of the base part 70 is thin, deformation of the base part 70 is suppressed in the first injection molding process and the second injection molding process. In particular, if the thickness of the base part 70 is 2.0 mm or less, it is preferable to manufacture the lid body 60 using the manufacturing method in the first example. Furthermore, in the first example, in the first injection molding process, the base part 70, which is easily deformed by resin pressure, is held down by a mold, so deformation of the base part 70 is suppressed even when the first covering part 80 is injection molded.

In the first example, after the first injection molding process is completed, a burr 100X (see FIG. 8A) may be formed in the portion of the flange portion 80B of the first covering part 80 that does not cover the end face of the wall portion 72 of the base part 70. In the second injection molding process, the burr 100X is covered by or integrated with the second covering part 90. This prevents the burr 100 from coming into contact with elements such as the electrode body 20 located inside the exterior body 40.

In the second example, the manufacturing method for the lid body 60 includes a first injection molding process and a second injection molding process. In the first injection molding process, the second covering part 90 is injection molded onto the base part 70. Note that the object in which the second covering part 90 is injection molded onto the base part 70 corresponds to the lid unit 230 (see Figure 8B). In the second injection molding process, the first covering part 80 is injection molded onto the lid unit 230. In the second example, the amount of resin used in the first injection molding process is smaller than when the first covering part 80 and the second covering part 90 are injection molded onto the base part 70 at the same time. Therefore, even if the thickness of the base part 70 is thin, deformation of the base part 70 is suppressed in the first injection molding process and the second injection molding process. In particular, if the thickness of the base part 70 is 2.0 mm or less, it is preferable to manufacture the lid body 60 using the manufacturing method in the second example. In addition, in the second example, in the first injection molding process, the base part 70, which is easily deformed by resin pressure, is held down by a mold, so that deformation of the base part 70 is suppressed even when the second covering part 90 is injection molded.

In a third example, the base part 70, the first covering part 80, and the second covering part 90 are manufactured separately and then combined. In the third example, the first covering part 80 and the second covering part 90 may be manufactured in the same molding machine. In the third example, the first covering part 80 and the second covering part 90 are not injection molded onto the base part 70, thereby suppressing deformation of the base part 70 during the manufacturing process of the lid body 60. In particular, when the thickness of the base part 70 is 2.0 mm or less, it is preferable that the lid body 60 be manufactured using the manufacturing method in the third example. The base part 70, the first covering part 80, and the second covering part 90, which are manufactured separately, correspond to a lid body kit 140 (see Figures 4 to 6).

In this embodiment, the first sealing portion 100A is formed by wrapping the exterior film 50 around the electrode body 20 and heat-sealing the opposing surfaces of the exterior film 50 (thermally adhesive resin layer 53).

The first sealed portion 100A 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 100A extends in the longitudinal direction of the exterior body 40. The position on the exterior body 40 where the first sealed portion 100A is formed can be selected arbitrarily. In this embodiment, the base 100AX of the first sealed portion 100A is preferably located on the edge 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 100AX of the first sealed portion 100A may be located on any surface of the exterior body 40. In this embodiment, the first sealed portion 100A protrudes outward beyond the electrode body 20 in a plan view. The first sealing portion 100A may be folded toward the second surface 42 of the exterior body 40, or toward the first surface 41, for example.

In this embodiment, the second sealing portion 100B is formed by heat-sealing the heat-sealable resin layer 53 of the exterior film 50 and the first wall surface 92X of the second covering part 90. Hereinafter, the seal strength between the heat-sealable resin layer 53 of the exterior film 50 and the first wall surface 92X of the second covering part 90 may be referred to as the seal strength (bonding strength) of the second sealing portion 100B. Note that the seal strength of the second sealing portion 100B is the seal strength between the heat-sealable resin layer 53 and the lid body 60 at the long side portion of the first wall surface 92X, i.e., the first wall surface 92X extending in the LR (width) direction in FIG. 1A.

The seal strength of the second sealing portion 100B is measured as follows. First, a slit is made in the portion of the exterior film 50 that constitutes the first surface 41 of the exterior body 40, forming three strip-shaped members 41X, 41Y, and 41Z aligned in the LR direction (see the two-dot chain lines in Figure 1B). 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 100B. The length of the lid body 60 in the LR direction is 45 mm or more. Next, the end of each of the strip-shaped members 41X, 41Y, and 41Z opposite the end joined to the lid body 60 is pulled upward in the UD direction (away from the first surface 41B), thereby measuring the seal strength of each of the strip-shaped members 41X, 41Y, and 41Z. The distance between the zippers in the UD direction is 50 mm. The seal strengths of the strip-shaped members 41X, 41Y, and 41Z are the peak values of their respective seal strengths. In this embodiment, the seal strength of the second sealing portion 100B is the average value of the seal strengths of the strip-shaped members 41X, 41Y, and 41Z. When the LR length of the lid body 60 is less than 45 mm, three strip-shaped members with an arbitrary width X mm, less than 15 mm, are formed, and the seal strengths of the three strip-shaped members are measured using the same method as when the LR length of the lid body 60 is 45 mm or more. The obtained seal strengths are each divided by the arbitrary width X mm and multiplied by 15 to convert them to the seal strengths of the three strip-shaped members at a 15 mm width. The seal strength of the second sealing portion 100B is the average value of the seal strengths of the three strip-shaped members converted to a 15 mm width. In addition, when the lid body 60 is divided into multiple parts including long sides and short sides, the sealing strength of the second sealing portion 100B is the sealing strength of the long side portion of the first wall surface 92X of the multiple parts.

From the viewpoint of maintaining the electrode assembly 20 in a sealed state by the outer casing 40, the seal strength of the second sealing portion 100B is preferably 40 N/15 mm or more, more preferably 50 N/15 mm or more, even more preferably 60 N/15 mm or more, even more preferably 70 N/15 mm or more, and even more preferably 85 N/15 mm or more. When the seal strength of the second sealing portion 100B is 40 N/15 mm or more, the electrode assembly 20 is maintained in a sealed state by the outer casing 40 even after the energy storage device 10 has been used for, for example, several years (less than 10 years). When the seal strength of the second sealing portion 100B is 85 N/15 mm or more, the electrode assembly 20 is maintained in a sealed state by the outer casing 40 even after the energy storage device 10 has been used for, for example, 10 years or more. The seal strength of the second sealing portion 100B is preferably 300 N/15 mm or less. A preferred range of the seal strength of the second sealing portion 100B 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.

<1-2. Manufacturing method of electricity storage device>
9 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, a fourth step, and a fifth step. The first step to the fifth step are performed, for example, by a manufacturing apparatus for the power storage device 10. At least some of the first step to the fifth step may be performed by an operator. Note that the first step to the fifth step are names of the steps in the method for manufacturing the power storage device 10 specified for convenience, and do not necessarily refer to the order of the steps. The order of the first step to the fifth step can be changed as desired as long as it is not technically inconsistent.

In the first step of step S11, the manufacturing equipment places a pair of lid bodies 60 on either side of the electrode body 20 in the FB direction.

The second step of step S12 is performed after the first step. In the second step, the manufacturing equipment joins the electrode terminal 30 connected to the electrode body 20 to the lid body 60. Note that the lid body 60 with the electrode terminal 30 joined thereto may be placed in the first step, and the electrode terminal 30 and electrode body 20 may be connected in the second step.

The third step of step S13 is performed after the second step. In the third step, the manufacturing apparatus wraps 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 using a 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 to prevent the electrode body 20 and the lid body 60 from moving. The restricting means may be a device that applies a force to the electrode body 20 and the lid body 60 in a direction opposite to the direction in which the exterior film 50 is pulled. The restricting means may include a roller that runs over the exterior film 50 while the exterior film 50 is being pulled, in order to remove wrinkles in the exterior film 50. The electrode body 20 with the electrode terminals 30 connected thereto may be housed inside the exterior film 50 configured in a cylindrical shape so that openings are formed at both ends in the FB direction, and after the electrode body 20 and the lid 60 are joined together, the opening may be closed by the lid 60. In yet another example, the electrode body 20 with the lid 60 connected via the electrode terminals 30 may be housed inside the exterior film 50 configured in a cylindrical shape so that openings are formed at both ends in the FB direction, and the opening may be closed by the lid 60.

The fourth step of step S14 is performed after the third step. In the fourth step, the manufacturing apparatus forms the second sealed portion 110B by heat-sealing the exterior film 50 and the first wall surface 82X of the lid body 60.

The fifth step of step S15 is performed before or after the fourth step. In the fifth step, the manufacturing apparatus forms the first sealing portion 100A by heat-sealing the heat-sealable resin layer 53 in the portion including the first edge 50A of the exterior film 50 and the heat-sealable resin layer 53 in the portion including the second edge 50B while applying tension to the exterior film 50 while restricting the movement of the electrode body 20 and the lid body 60.

<1-3. Actions and Effects of the Electricity Storage Device>
The lid body 60 includes a base part 70, a first covering part 80, and a second covering part 90. Because the first covering part 80 and the second covering part 90 are separate parts, the first covering part 80 and the second covering part 90 are not simultaneously injection molded onto the base part 70 during the manufacturing process of the lid body 60. This prevents the lid body 60 from being deformed during the manufacturing process of the lid body 60.

2. Modifications
The above-described embodiments are examples of possible forms of the lid, electricity storage device, lid kit, lid unit, base part, first covering part, second covering part, and electricity storage device manufacturing method of the present invention, and are not intended to limit the forms. The lid, electricity storage device, lid kit, lid unit, base part, first covering part, second covering part, and electricity storage device manufacturing method of the present invention may take forms different from those exemplified in the embodiments. Examples include forms in which part of the configuration of the embodiments is replaced, modified, or omitted, or forms in which new configurations are added to the embodiments. Some examples of modified embodiments are shown below. Note that the following modified forms can be combined with each other as long as there is no technical contradiction.

<2-1. First Modified Example>
In the above embodiment, the configuration of lid 60 can be modified. Fig. 10 is a cross-sectional view of lid 160 of a first modified example. As shown in Fig. 10, main portion 91 of second covering part 90 does not have to cover a portion of second surface 71B of base part 70.

<2-2. Second Modified Example>
FIG. 11 is a cross-sectional view of a cover body 260 of a second modified example. As shown in FIG. 11 , the main portion 81 of the first covering part 80 may not cover a portion of the first surface 71A of the base part 70. The main portion 91 of the second covering part 90 may not cover a portion of the second surface 71B of the base part 70. In the example shown in FIG. 11 , the first surface 71A and the second surface 71B of the base part 70 are exposed. The exposed portion of the first surface 71A of the base part 70 may be connected to the electrode body 20. The exposed portion of the second surface 71B of the base part 70 may be connected to an external device. In the second modified example, current can be output from the base part 70. In other words, the base part 70 also functions as the electrode terminal 30, so the electrode terminal 30 can be omitted. Note that in the second modified example, the electrode terminal 30 may be joined to the portion of the second surface 71B that is not covered by the second covering part 90.

<2-3. Third Modified Example>
12 is a cross-sectional view of a lid 360 of a third modified example. The base part 70 may have a flange part 74 that connects to the wall part 72. An edge 74A of the flange part 74 may be sandwiched between the first covering part 80 and the second covering part 90. In the third modified example, the first covering part 80 and the second covering part 90 do not contact each other.

<2-4. Fourth Modified Example>
In the above embodiment, the electrode terminal 30 may protrude outside the exterior body 40 from between the first wall surface 91X of the second covering part 90 and the exterior film 50. In the fourth modified example, an adhesive film that can be suitably bonded to metal and resin is preferably disposed between the first wall surface 91X and the electrode terminal 30 and between the electrode terminal 30 and the exterior film 50. In the fourth modified example, from the viewpoint of sealing performance, the electrode terminal 30 is preferably plate-shaped. In the fourth modified example, the hole 71Z of the base part 70, the hole 81Z of the first covering part 80, and the hole 91Z of the second covering part 90 may be omitted. The fourth modified example can be similarly applied to the first to third modified examples.

<2-5. Fifth Modification>
In the above embodiment, the shape of the base part 70 can be changed as desired. The base part 70 may be, for example, cylindrical. When the base part 70 is cylindrical, for example, one side of an imaginary line that coincides with the radius of the circle of the end face can be defined as a first surface, and the other side can be defined as a second surface.

<2-6. Sixth Modification>
In the above embodiment, the exterior film 50 of the power storage device 10 may protrude outward in the FB direction beyond at least one of the two lid bodies 60. 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 inward so that the outer surfaces of the exterior film 50 come into contact with each other, as in a Goebel-top container, or may be folded toward any surface of the exterior body 40, as in a brick container.

<2-7. Seventh 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 the portion of the exterior body 40 where the lid body 60 is omitted, the electrode body 20 is sealed by closing the portion of the exterior film 50 that protrudes outward beyond the electrode body 20. As in the sixth modification, the portion of the exterior film 50 that protrudes outward beyond the electrode body 20 may be folded like a Goebel-top container or a brick-type container.

<2-8. Eighth Modification>
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.

<2-9. Ninth Modification>
In the above embodiment, the electrode body 20 is wrapped in one exterior film 50 , but it may be wrapped in two or more exterior films 50 .

10: Electricity storage device 20: Electrode body 40: Exterior body 50: Exterior film 60, 260, 360: Lid body 70: Base part 71: Main part 71A: First surface 71B: Second surface 72: Wall part 73: Internal space 74A: Edge 80: First covering part 80A: Storage part 90: Second covering part 130, 230: Lid unit 140: Lid body kit

Claims (10)

A lid used for an exterior body of an electricity storage device,
a base part comprising a conductive material and including a first surface and a second surface opposite the first surface;
a first covering part including a resin material and covering at least a portion of the first surface of the base part;
a second covering part that contains a resin material and covers at least a portion of the second surface of the base part,
The first covering part and the second covering part are resin molded parts. The lid according to claim 1 , further comprising a portion where the first covering part and the second covering part come into contact with each other. The lid according to claim 1 , wherein an edge of the base part is sandwiched between the first covering part and the second covering part. The base part comprises:
The main part and
a wall portion protruding from the main portion;
an interior space defined by the wall portion;
The cover body according to any one of claims 1 to 3, wherein the first covering part includes a housing portion that is housed in the internal space. The lid according to any one of claims 1 to 3, wherein the thickness of the base part is 5.0 mm or less. An electrode body;
an exterior body that seals the electrode body,
The exterior body is
an exterior film that wraps the electrode body;
a lid that seals the electrode body together with the exterior film,
The lid body is
a base part including a conductive material and including a first surface facing the electrode body and a second surface opposite the first surface;
a first covering part including a resin material and covering at least a portion of the first surface of the base part;
a second covering part that contains a resin material and covers at least a portion of the second surface of the base part,
the first covering part is disposed apart from the electrode body,
The power storage device, wherein the base part is a metal molded product having a thickness of 0.5 mm or more . A lid kit for constituting a lid to be used for an exterior body of an electricity storage device,
a base part comprising a conductive material and including a first surface and a second surface opposite the first surface;
a first covering part including a resin material and covering at least a portion of the first surface of the base part;
a second covering part that contains a resin material and covers at least a portion of the second surface of the base part,
The lid kit, wherein the first covering part and the second covering part are resin molded parts. A lid unit constituting a lid body used in an exterior body of an electricity storage device,
a base part comprising a conductive material and including a first surface and a second surface opposite the first surface;
a first covering part containing a resin material and covering at least a portion of the first surface of the base part; and a second covering part containing a resin material and covering at least a portion of the second surface of the base part,
The lid unit, wherein the first covering part and the second covering part are resin molded parts. A first covering part constituting a lid used in an exterior body of an electricity storage device,
the lid body includes a base part including a conductive material and including a first surface facing an electrode body of the power storage device and a second surface opposite to the first surface;
The first covering part is a resin molded product that includes a resin material and is configured to cover at least a portion of the first surface of the lid. A method for manufacturing an electricity storage device, comprising:
The electricity storage device is
An electrode body;
an exterior body that seals the electrode body,
The exterior body is
an exterior film that wraps the electrode body;
a lid that seals the electrode body together with the exterior film,
The lid body is
a base part including a conductive material and including a first surface facing the electrode body and a second surface opposite the first surface;
a first covering part including a resin material and covering at least a portion of the first surface of the base part;
a second covering part that contains a resin material and covers at least a portion of the second surface of the base part,
the first covering part is disposed apart from the electrode body,
the base part is a metal molded product having a thickness of 0.5 mm or more ;
The method for manufacturing the electricity storage device includes:
A method for manufacturing an electricity storage device, comprising: placing the lid body on the electrode body.