Electricity storage device, electricity storage device manufacturing kit, and method for manufacturing electricity storage device

Abstract

This electricity storage device is provided with an electrode body and an exterior body that seals the electrode body. The electrode body includes: a first end portion; a second end portion disposed at a distance from the first end portion; and an intermediate portion continuously extending between the first end portion and the second end portion. The exterior body includes: an exterior film covering the intermediate portion; and a cover body disposed on at least one of the first end portion side and the second end portion side, the cover body having a joining surface joined to the exterior film. The outer periphery of the intermediate portion is smaller than the outer periphery of the joining surface.

Description

Energy storage devices, energy storage device manufacturing kits, and methods for manufacturing energy storage devices Technical Field

[0001] This invention relates to energy storage devices, energy storage device manufacturing kits, and methods for manufacturing energy storage devices. Background Technology

[0002] Patent Document 1 discloses an example of an energy storage device. The energy storage device includes an electrode body and an outer casing that seals the electrode body. The outer casing includes: an outer film covering the electrode body in a manner forming an opening; and a cover disposed at the opening. The outer film and the cover are joined together.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent document 1: Japanese Patent Application Publication No. 2022-123686. Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In the manufacturing of the aforementioned energy storage devices, to cover the electrode body, methods such as winding an outer film around the outer periphery of the electrode body and the cover are sometimes used. After achieving the winding state of the outer film around the outer periphery of the electrode body and the cover, a process of joining the outer film to the outer periphery of the cover is performed. In this winding state of the outer film, if there is a gap between the outer film and the cover, it will lead to poor bonding between the outer film and the cover, requiring subsequent repair work on the poorly bonded parts, which is therefore not preferred. However, since the outer film is elastic, it is difficult to achieve a winding state that prevents it from loosening around the outer periphery of the cover. Even so, if the tension applied to the outer film is increased during the winding process to achieve the above-mentioned winding state, unnecessary pressure will be applied to the electrode body, thereby posing a risk of collapse of the electrode foil and other laminated structures of the electrode body, which will have an adverse effect on the electrode body. Therefore, a technology is needed to suppress poor bonding between the outer film and the cover while eliminating the impact on the electrode body.

[0008] The purpose of this invention is to provide a storage device, a storage device manufacturing kit, and a method for manufacturing a storage device that can appropriately suppress poor bonding between the outer film and the cover.

[0009] Technical means for solving problems

[0010] The energy storage device of the first aspect of the present invention includes an electrode body and an outer casing sealing the electrode body. In this energy storage device, the electrode body includes: a first end portion; a second end portion disposed at a distance from the first end portion; and an intermediate portion extending continuously between the first end portion and the second end portion. The outer casing includes: an outer casing film covering the intermediate portion; and a cover disposed on at least one side of the first end portion and the second end portion, the cover having a mating surface that engages with the outer casing film. The outer perimeter of the intermediate portion is smaller than the outer perimeter of the mating surface.

[0011] The energy storage device of the second aspect of the present invention is the energy storage device of the first aspect, wherein the difference between the outer periphery of the middle portion and the outer periphery of the joint surface is 1 mm or more.

[0012] The energy storage device of the third aspect of the present invention is an energy storage device of the first or second aspect, wherein the intermediate portion has one or more corner portions with R-shaped surfaces, and the mating surface has one or more corner portions with R-shaped surfaces. The radius of curvature of the one or more corner portions of the intermediate portion is greater than the radius of curvature of the one or more corner portions of the mating surface.

[0013] The fourth aspect of this invention provides a battery storage device manufacturing kit for manufacturing a battery storage device including an electrode body and an outer casing for sealing the electrode body. The electrode body includes: a first end portion; a second end portion disposed at a distance from the first end portion; and an intermediate portion extending continuously between the first end portion and the second end portion. The outer casing includes: an outer casing film for covering the intermediate portion; and a cover for being disposed on at least one side of the first end portion and the second end portion, the cover having a mating surface for engaging with the outer casing film. The outer perimeter of the intermediate portion is smaller than the outer perimeter of the mating surface.

[0014] The energy storage device manufacturing kit of the fifth aspect of the present invention is the energy storage device manufacturing kit of the fourth aspect, wherein the difference between the outer periphery of the middle part and the outer periphery of the mating surface is 1 mm or more.

[0015] The energy storage device manufacturing kit of the sixth aspect of the present invention is an energy storage device manufacturing kit of the fourth or fifth aspect, wherein the intermediate portion has one or more corner portions with R-shaped surfaces, and the mating surface has one or more corner portions with R-shaped surfaces. The radius of curvature of the one or more corner portions of the intermediate portion is greater than the radius of curvature of the one or more corner portions of the mating surface.

[0016] The seventh aspect of this invention discloses an intermediate body for manufacturing an energy storage device comprising an electrode body and a sealing electrode body. In the intermediate body, the electrode body includes: a first end portion; a second end portion disposed at a distance from the first end portion; and an intermediate portion extending continuously between the first end portion and the second end portion. The outer body includes: an outer film covering the intermediate portion; and a cover disposed on at least one side of the first end portion and the second end portion, the cover having a mating surface that engages with the outer film. The intermediate body of the energy storage device includes: the electrode body; and the outer film and the cover joined together to accommodate the electrode body, wherein the outer perimeter of the intermediate portion is smaller than the outer perimeter of the mating surface. The intermediate body of the energy storage device does not contain an electrolyte.

[0017] The eighth aspect of the present invention discloses a method for manufacturing an energy storage device comprising an electrode body and an outer casing sealing the electrode body. The electrode body includes: a first end portion; a second end portion disposed at a distance from the first end portion; and an intermediate portion extending continuously between the first end portion and the second end portion. The outer casing includes: an outer casing film; and a cover having a mating surface to be engaged with the outer casing film. The manufacturing method includes the following steps.

[0018] The step of configuring the cover and the electrode body such that the cover is located on at least one side of the first end side and the second end side.

[0019] The steps include: making the outer film wrapped around the cover and the electrode body in such a way that it covers the joint surface of the cover and the middle portion of the electrode body; and making an intermediate body of an energy storage device in which the electrode body is housed within the cover and the outer film by joining the joint surface to the outer film, wherein the intermediate body of the energy storage device does not contain electrolyte.

[0020] Furthermore, in the intermediate body of the energy storage device, the outer periphery of the intermediate portion is smaller than the outer periphery of the mating surface.

[0021] The method for manufacturing an energy storage device according to the ninth aspect of the present invention is the method for manufacturing an energy storage device according to the eighth aspect, wherein the method further includes the step of injecting the electrolyte into the interior of the joined cover and the outer membrane.

[0022] The tenth aspect of this invention discloses a method for manufacturing an energy storage device comprising an electrode body and an outer casing sealing the electrode body. The electrode body includes: a first end portion; a second end portion disposed at a distance from the first end portion; and an intermediate portion extending continuously between the first end portion and the second end portion. The outer casing includes: an outer casing film; and a cover having a mating surface to be engaged with the outer casing film. The outer perimeter of the intermediate portion is smaller than the outer perimeter of the mating surface. The manufacturing method includes the following steps.

[0023] The step of configuring the cover and the electrode body such that the cover is located on at least one side of the first end side and the second end side.

[0024] The step of making the outer film so that it is wound around the cover and the electrode body in such a way that it covers the joint surface of the cover and the middle part of the electrode body.

[0025] The step of joining the bonding surface to the outer film.

[0026] The eleventh aspect of the present invention discloses a method for manufacturing an energy storage device comprising an electrode body and an outer casing sealing the electrode body. The electrode body includes: a first end portion; a second end portion disposed at a distance from the first end portion; and an intermediate portion extending continuously between the first end portion and the second end portion. The outer casing includes: an outer casing film; and a cover having a mating surface to be engaged with the outer casing film. The manufacturing method includes the following steps.

[0027] The step of configuring the cover and the electrode body such that the cover is located on at least one side of the first end side and the second end side.

[0028] The step of making the outer film so that it is wound around the cover and the electrode body in such a way that it covers the joint surface of the cover and the middle part of the electrode body.

[0029] The step of joining the bonding surface to the outer film.

[0030] Furthermore, the step of making the outer film wound around the cover and the electrode body includes making the outer film wound around the cover and the electrode body in such a way that the pressure applied from the outer film to the joint surface is greater than the pressure applied from the outer film to the middle portion.

[0031] Invention Effects

[0032] According to the present invention, the energy storage device, the energy storage device manufacturing kit, and the method for manufacturing the energy storage device can suppress poor bonding between the outer film and the cover without adversely affecting the electrode body. Attached Figure Description

[0033] Figure 1 is a perspective view of an energy storage device according to one embodiment.

[0034] Figure 2 is a three-dimensional view of the electrode body of the energy storage device in Figure 1.

[0035] Figure 3 is a cross-sectional view showing the layer structure of the outer membrane of the energy storage device in Figure 1.

[0036] Figure 4 is a perspective view of the cover of the energy storage device in Figure 1.

[0037] Figure 5 is a diagram illustrating the method for determining the outer periphery of the mating surface of the energy storage device in Figure 1.

[0038] Figure 6 is a diagram illustrating an example of the manufacturing process of a storage device using a storage device manufacturing kit according to one embodiment.

[0039] Figure 7 is a flowchart illustrating an example of a method for manufacturing the energy storage device of Figure 1.

[0040] Figure 8 is a diagram illustrating the size relationship between the mating surface and the outer periphery of the middle part.

[0041] Figure 9 is a top view of an intermediate body of a storage device manufactured by a storage device manufacturing method.

[0042] Figure 10A is a diagram illustrating the structure of the cover and electrode body in the modified example.

[0043] Figure 10B is a diagram illustrating the structure of the cover and electrode body in another modified example.

[0044] Figure 11 is a schematic cross-sectional view of a wound electrode body housed in the outer casing of a modified energy storage device. Detailed Implementation

[0045] Hereinafter, with reference to the accompanying drawings, a method for manufacturing an energy storage device, an energy storage device manufacturing kit, and an embodiment of the present invention will be described. In this specification, the numerical range indicated by "~" means "above" or "below". For example, the expression 2 to 15 mm means 2 mm or more and 15 mm or less. Furthermore, in this specification, corners include not only right-angled corners but also corners with an R-face (chamfered surface).

[0046] <1. Structure of Energy Storage Devices>

[0047] Figure 1 is a perspective view schematically showing the energy storage device 10 of this embodiment. Figure 2 is a perspective view of the electrode body 20 of the energy storage device of Figure 1A. Figure 3 is a cross-sectional view showing the layer structure of the outer film 50 of the energy storage device 10 of Figure 1. Figure 4 is a perspective view of the cover 60 of the energy storage device 10 of Figure 1. In Figure 1, the arrow UD indicates the thickness direction of the energy storage device 10, the arrow LR indicates the width direction of the energy storage device 10, and the arrow FB indicates the depth direction of the energy storage device 10. The directions indicated by arrows UD, LR, and FB are also common in the following figures.

[0048] The energy storage device 10 includes an electrode body 20, electrode terminals 30, and an outer casing 40. The electrode body 20 includes, for example, 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-state battery, pseudo-solid-state battery, polymer battery, all-resin battery, lead-acid battery, nickel-metal hydride battery, nickel-cadmium battery, nickel-iron battery, nickel-zinc battery, silver-zinc oxide battery, metal-air battery, multivalent cation battery, or capacitor. In this embodiment, the electrode body 20 is a generally rectangular cuboid formed by stacking multiple layers of rectangular flat electrode foil and separator in the UD direction. The term "generally rectangular cuboid" includes not only a perfect cuboid but also, for example, a three-dimensional shape that can be considered a cuboid by modifying the shape of a portion of the outer surface. The shape of the electrode body 20 can be, for example, a cylinder or a polygonal prism.

[0049] 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 the electrode body 20. One end of the electrode terminal 30 is electrically connected to an electrode (positive or negative) contained in the electrode body 20. The other end of the electrode terminal 30 protrudes outward from, for example, the edge of the outer casing 40. Alternatively, as long as the electrode terminal 30 can perform power input and output to the electrode body 20, it may not protrude from the outer casing 40. When the cover 60, described later, is made of metal, for example, the cover 60 sometimes also functions as the electrode terminals 30. In this case, the cover 60, which functions as electrode terminals, may or may not protrude from the outer casing 40.

[0050] As shown in Figure 2, in this embodiment, the electrode body 20 has a front surface 21, a back surface 22, an upper surface 23, a lower surface 24, a first side surface 25, and a second side surface 26. The front surface 21 faces a cover 60 (cover 60A). The back surface 22 faces another cover 60 (cover 60B). The upper surface 23, the lower surface 24, the first side surface 25, and the second side surface 26 respectively constitute the upper surface 41, the lower surface 42, the first side surface 43, and the second side surface 44 of the outer casing 40 described later. Furthermore, the front surface 21, the back surface 22, the first side surface 25, and the second side surface 26 are imaginary surfaces when the laminated body is considered to be approximately a cuboid, based on the upper surface 23 and the lower surface 24 formed by the above-described laminated body. The front surface 21 and the back surface 22 respectively constitute the first end 201 and the second end 202 of the electrode body 20, which are spaced apart from each other in the FB direction. Furthermore, the upper surface 23, the lower surface 24, the first side surface 25, and the second side surface 26 form the middle portion 203 of the electrode body 20, which extends continuously between the first end 201 and the second end 202. In addition to the front surface 21, the first end 201 may also include a component protruding from the front surface 21 toward the cover 60A side (in the direction of arrow F). Similarly, in addition to the back surface 22, the second end 202 may also include a component protruding from the back surface 22 toward the cover 60B side (in the direction of arrow B).

[0051] The electrode body 20 has corner portions 20A, 20B, 20C, and 20D. Corner portion 20A is formed at the boundary between the upper surface 23 and the first side surface 25. Corner portion 20B is formed at the boundary between the upper surface 23 and the second side surface 26. Corner portion 20C is formed at the boundary between the first side surface 25 and the lower surface 24. Corner portion 20D is formed at the boundary between the second side surface 26 and the lower surface 24. Furthermore, at least one of corner portions 20A to 20D may have an R-surface. Examples of corner portions 20A to 20D having R-surfaces will be described later.

[0052] Here, the outer periphery of the intermediate portion 203 is designated as L1 and L1'. The outer periphery L1 is the outer periphery of the intermediate portion 203 of the electrode body 20 constituting the energy storage device manufacturing kit 100 or the intermediate body 10A of the energy storage device. The energy storage device manufacturing kit 100 (see Figure 6) and the intermediate body 10A of the energy storage device (see Figure 9) will be described later. The outer periphery L1' is the outer periphery of the intermediate portion 203 constituting the electrode body 20 of the energy storage device 10. More specifically, the outer peripheries L1 and L1' are the lengths of the outer periphery of the intermediate portion 203 passing through the plane orthogonal to the FB direction between the front side 21 and the back side 22. The measurements of the outer perimeters L1 and L1' are performed using a Class 1 measuring tape conforming to JIS B 7522:2018, at an ambient temperature of 20°C ± 2°C, with tension indicated on a portion of the measuring tape (for measuring tapes without specified tension, the tension is 5N for nominal sizes under 2m and 50N for widths over 50mm). As described later, the outer perimeter L1 is smaller than the outer perimeter L2 of the mating surface 63 of the cover 60 before it is formed into the energy storage device 10 and in a state not yet bonded to the outer film 50. That is, in the energy storage device manufacturing kit 100 described later, L1 < L2. Furthermore, the outer perimeter L1 is smaller than the outer perimeter L3 of the mating surface 63 of the cover 60 before it is formed into the energy storage device 10 and in a state bonded to the outer film 50. That is, in the intermediate body 10A of the energy storage device 10 described later, L1 < L3. Furthermore, regarding an energy storage device in which the outer periphery L1' is smaller than the outer periphery L3 of the mating surface of the cover 60 constituting the energy storage device, i.e., L1' < L3, in the energy storage device manufacturing kit used to manufacture the energy storage device, L1 < L2, or in the intermediate body of the energy storage device, L1 < L3.

[0053] As described above, energy storage devices where L1' < L3 are true are included within the scope of this invention. Furthermore, if the energy storage device manufacturing kit 100 is L1 < L2, then the energy storage device 10 manufactured using it is included within the scope of this invention even if L1' ≥ L3, or even if L1 ≥ L3 in the intermediate body 10A of the energy storage device manufactured using the energy storage device manufacturing kit 100. Moreover, if the intermediate body 10A is L1 < L3, then the energy storage device 10 manufactured via the intermediate body 10A is included within the scope of this invention even if L1' ≥ L3.

[0054] The metallic material constituting the electrode terminal 30 is, for example, aluminum, nickel, or copper. 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, and the electrode terminal 30 connected to the negative electrode is usually made of copper, nickel, or the like. In addition, the outermost layer of the electrode body 20 does not necessarily have to be an electrode; for example, it can be a protective tape or a separator.

[0055] The outer casing 40 seals the electrode body 20. In this embodiment, the outer casing 40 includes an outer film 50 and a pair of covers 60. The outer film 50 covers the electrode body 20 in a manner that surrounds the entire middle portion 203 from the outside. In this embodiment, the outer film 50 is wound around the electrode body 20 with openings at the first end 201 and the second end 202. The pair of covers 60 are respectively disposed at the first end 201 and the second end 202 of the electrode body 20 to close the openings. In the winding process of the manufacturing method of the energy storage device 10 described later, the outer film 50, with tension (pull force), is wound around the pair of covers 60 and the electrode body 20 in this manner (hereinafter, this state is also referred to as the "winding state"). Furthermore, the aforementioned winding state can be achieved by: rolling the outer film 50 into a cylindrical shape to form a pair of openings, or rolling it into a cylindrical shape and at least partially temporarily fixing it to maintain this state; then housing the electrode body 20 inside the cylinder; subsequently, placing caps 60 at each of the pair of openings; and then applying tension to the outer film 50. Alternatively, it can be achieved by: preparing an assembly in advance to attach a pair of caps 60 to the first end 201 and the second end 202 of the electrode body 20, housing it inside the rolled-up outer film 50, or rolling it into a cylindrical shape and at least partially temporarily fixing it to maintain this state; and then applying tension to the outer film 50. In summary, as long as the outer film 50 (with a certain degree of tension) is wound around a pair of caps 60 and the electrode body 20, the electrode body 20 can be sealed by closing a pair of openings by attaching the pair of caps 60 to the outer film 50.

[0056] From the viewpoint of ensuring good adhesion to the cover 60, it is preferable to have an adhesive film 31 bonded to the electrode terminal 30. The adhesive film 31 can be any thin film capable of bonding the metal electrode terminal 30 and the resin cover 60. The adhesive film 31 can be, for example, a polyolefin resin such as polyethylene resin or polypropylene resin, a cyclic polyolefin resin, or an acid-modified polyolefin resin obtained by grafting these polyolefin resins with an acid such as maleic anhydride. The adhesive film 31 can be a single layer or two or more layers of these materials. In this embodiment, the adhesive film 31 is bonded to approximately the entire portion of the electrode terminal 30 covered by the cover 60.

[0057] For example, there is a method of forming a receiving portion (recess) for housing the electrode body 20 in the outer film 50 by cold forming. However, it is not easy to form a deep receiving portion by such a method. If the receiving portion (recess) is formed deep (e.g., forming depth 15 mm) by cold forming, pinholes or cracks may be generated in the outer film 50, which increases the possibility of reduced battery performance. On the other hand, the outer body 40 seals the electrode body 20 by winding the outer film 50 around the electrode body 20, so the electrode body 20 can be easily sealed regardless of its thickness. Furthermore, in order to reduce the ineffective area between the electrode body 20 and the outer film 50 to improve the volumetric energy density of the energy storage device 10, the outer film 50 is preferably in a state where it covers the electrode body 20 in contact with or close to the outer surface of the intermediate portion 203. In addition, in all-solid-state batteries, from the viewpoint that a high pressure needs to be uniformly applied to the outer surface of the battery in order to maximize battery performance, it is also necessary to eliminate the space between the electrode body 20 and the outer film 50. Therefore, it is preferable that the outer film 50 is wound in a manner that contacts the outer surface of the electrode body 20.

[0058] As shown in Figure 3, the outer film 50 is, for example, a laminate (laminated film) having a substrate layer 51, a barrier layer 52, and a heat-welding resin layer 53 in sequence. Furthermore, the outer film 50 does not necessarily include all of these layers; for example, it may omit the barrier layer 52. That is, the outer film 50 only needs to be flexible and made of a bendable material, such as a resin film. Additionally, the outer film 50 is preferably weldable by methods such as heat sealing, ultrasonic sealing, and high-frequency sealing.

[0059] The outer film 50 may also be composed of a laminate comprising at least a barrier layer 52 and a heat-melting resin layer 53 in sequence. In this laminate, the substrate layer 51 is a layer that can be provided as needed, the side opposite to the heat-melting resin layer 53 side of the barrier layer 52 is the outermost layer side, and the heat-melting resin layer 53 is the innermost layer.

[0060] The overall thickness of the outer film 50 can be arbitrarily selected. From a strength point of view, the thickness of the outer film 50 is preferably 50 μm or more. From a formability or conformability point of view, the thickness of the outer film 50 is preferably 1200 μm or less. The thickness of the outer film 50 is preferably contained in the range of 50 μm or more and 1200 μm or less.

[0061] The substrate layer 51 included in the outer packaging film 50 is a layer used to impart heat resistance to the outer packaging film 50 and suppress the formation of pinholes that may occur during processing or distribution. The substrate layer 51 is configured to include at least one layer of stretched polyester resin and stretched polyamide resin. For example, by including at least one layer of stretched polyester resin and stretched polyamide resin in the substrate layer 51, the barrier layer 52 can be protected during the processing of the outer packaging film 50, and breakage of the outer packaging film 50 can be suppressed. Furthermore, from the viewpoint of increasing the elongation at break of the outer packaging 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. Further, from the viewpoint of excellent puncture strength or impact strength, the stretched polyester resin layer is more preferably a biaxially stretched polyethylene terephthalate (PET) film, and the stretched polyamide resin layer is more preferably a biaxially stretched nylon (ONy) film. Additionally, the substrate layer 51 may be configured to include both a stretched polyester resin layer and a stretched polyamide resin layer. From the viewpoint of film strength, the thickness of the substrate layer 51 is preferably 5 to 300 μm, and more preferably 5 to 150 μm.

[0062] The barrier layer 52 is a layer that at least inhibits the penetration of moisture. The barrier layer 52 is bonded to the substrate layer 51, for example, via an adhesive layer 54. Examples of barrier layers 52 include barrier-resistant metal foils, vapor-deposited films, and resin layers. Examples of vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Examples of resin layers include polyvinylidene chloride, polymers with trifluorochloroethylene (CTFE) as the main component, polymers with tetrafluoroethylene (TFE) as the main component, polymers containing fluoroalkyl groups, and polymers with fluoroalkyl units as the main component, as well as fluoropolymers such as ethylene-vinyl alcohol copolymers. Furthermore, examples of barrier layers 52 include resin films having at least one of these vapor-deposited films and resin layers. Multiple layers of the barrier layer 52 may also be provided. The barrier layer 52 preferably includes a layer made of a metallic material. Specifically, the metal material constituting the barrier layer 52 can be aluminum alloy, stainless steel, titanium steel, steel plate, etc. When used as a metal foil, it is preferred to include at least one of aluminum alloy foil and stainless steel foil.

[0063] In the barrier layer 52, the layer composed of the aforementioned metallic material may also contain recycled metallic materials. Examples of recycled metallic materials include aluminum alloys, stainless steel, titanium steel, or recycled steel plates. These recycled materials can be obtained using known methods. For example, recycled aluminum alloys can be obtained using the manufacturing method described in International Publication No. 2022 / 092231. The barrier layer 52 may be composed solely of recycled materials or a mixture of recycled and virgin materials. Here, recycled metallic materials refer to metallic materials that have been recycled, separated, and refined from various products used in the market and waste from manufacturing processes to become reusable. Furthermore, virgin metallic materials refer to newly refined metallic materials derived from natural metallic resources (raw materials), and are not recycled materials.

[0064] From the viewpoint of improving the formability or conformability of the outer film 50, the aluminum alloy foil is more preferably a soft aluminum alloy foil, such as one made of annealed aluminum alloy. From the viewpoint of further improving formability or conformability, an iron-containing aluminum alloy foil is preferred. In the iron-containing aluminum alloy foil (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, more preferably 0.5 to 2.0% by mass. By making the iron content 0.1% by mass or more, an outer film 50 with better formability can be obtained. By making the iron content 9.0% by mass or less, an outer film 50 with better flexibility can be obtained. In addition, silicon, magnesium, copper, manganese, etc., may be added to the aluminum alloy foil as needed. Furthermore, softening can be performed by annealing or the like. From the viewpoint of improving the mechanical strength of the outer film 50, the aluminum alloy foil is more preferably a hard aluminum alloy foil, such as one made of processed and cured aluminum alloy. Examples of hard aluminum alloy foils include those with compositions specified in JIS H4160:1994A8021H-H18, JIS H4160:1994A8079H-H18, JIS H4000:2014A8021P-H14, or JIS H4000:2014A8079P-H14. From the viewpoint of improving the mechanical strength of the outer film 50, the aluminum alloy foil is preferably a magnesium-containing aluminum alloy foil. In the magnesium-containing aluminum alloy foil (100% by mass), the magnesium content is preferably 0.2 to 5.6% by mass, more preferably 0.2 to 3.0% by mass. Examples of magnesium-containing aluminum alloy foils include those with the composition specified in JIS H4000:2017 A5005P-O, JIS H4000:2017 A5050P-O, and JIS H4000:2017 A5052P-O.

[0065] Furthermore, examples of stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardening stainless steel foils. Moreover, from the viewpoint of providing an outer film 50 with excellent formability, the stainless steel foil is preferably made of austenitic stainless steel.

[0066] Specific examples of stainless steels that constitute the austenitic system of stainless steel foil include SUS 304, SUS 301, and SUS316 L, among which SUS 304 is particularly preferred.

[0067] In the case of a metal foil, the thickness of the barrier layer 52 is sufficient to at least function as a barrier layer to inhibit moisture penetration; for example, a thickness of about 5 to 1000 μm is acceptable. The thickness of the barrier layer 52 is preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, and particularly preferably about 35 μm or less. Furthermore, the thickness of the barrier layer 52 is preferably about 9.0 μm or more, even more preferably about 20 μm or more, and even more preferably about 25 μm or more. Furthermore, preferred ranges for the thickness of the barrier layer 52 include approximately 9.0–1000 μm, approximately 9.0–1000 μm, approximately 9.0–1000 μm, approximately 9.0–1000 μm, approximately 9.0–85 μm, approximately 9.0–50 μm, approximately 9.0–40 μm, approximately 9.0–35 μm, approximately 20–85 μm, approximately 20–50 μm, approximately 20–40 μm, approximately 20–35 μm, approximately 25–85 μm, approximately 25–50 μm, approximately 25–40 μm, and approximately 25–35 μm. When the barrier layer 52 is made of aluminum alloy foil, the above-mentioned ranges are particularly preferred. Furthermore, from the viewpoint of imparting high formability and high rigidity to the outer film 50, the thickness of the barrier layer 52 is preferably about 35 μm or more, more preferably about 45 μm or more, further preferably about 50 μm or more, and even more preferably about 55 μm or more. It is also preferably about 200 μm or less, more preferably about 85 μm or less, further preferably about 75 μm or less, and even more preferably about 70 μm or less. The preferred range is 35 to 200 μm. The outer film 50 has high formability, making deep drawing easier and contributing to the increase in capacity of the energy storage device. Furthermore, while the weight of the energy storage device increases with increasing capacity, improving the rigidity of the outer film 50 also contributes to its high sealing performance. Furthermore, especially 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. Additionally, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more.In addition, preferred ranges for the thickness of stainless steel foil include approximately 10–60 μm, approximately 10–50 μm, approximately 10–40 μm, approximately 10–30 μm, approximately 10–25 μm, approximately 15–60 μm, approximately 15–50 μm, approximately 15–40 μm, approximately 15–30 μm, and approximately 15–25 μm.

[0068] Furthermore, when the barrier layer 52 is aluminum foil, to prevent dissolution, corrosion, etc., it is preferable to have a corrosion-resistant coating on at least the side opposite to the substrate layer 51. The barrier layer 52 may have a corrosion-resistant coating on both sides. Here, the corrosion-resistant coating refers to a thin film that gives the barrier layer 52 corrosion resistance (e.g., acid resistance, alkali resistance, etc.) by performing hot water conversion treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, nickel or chromium plating treatment, or anti-corrosion treatment by applying a coating agent on the surface of the barrier layer 52. 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. One treatment or a combination of two or more treatments can be performed to form the corrosion-resistant coating. In addition, it can be not only one layer, but also multiple layers. Furthermore, among these treatments, hot water conversion treatment and anodizing treatment are treatments that dissolve the surface of the metal foil with a treatment agent to form a metal compound with excellent corrosion resistance. Furthermore, these treatments are sometimes included in the definition of chemical conversion treatment. Additionally, when the barrier layer 52 has a corrosion-resistant coating, the layer containing the corrosion-resistant coating is considered the barrier layer 52.

[0069] The corrosion-resistant coating has the following effects: during the forming of the outer film 50, it prevents delamination between the barrier layer 52 (e.g., aluminum alloy foil) and the substrate layer 51, prevents the surface of the barrier layer 52 from dissolving and corroding due to hydrogen fluoride generated by the reaction of electrolytes and moisture, especially when the barrier layer 52 is aluminum alloy foil, prevents the dissolution and corrosion of alumina present on the surface of the barrier layer 52, and improves the adhesion (wetting) of the surface of the barrier layer 52, prevents delamination between the substrate layer 51 and the barrier layer 52 during heat sealing and other welding, and prevents delamination between the substrate layer 51 and the barrier layer 52 during forming.

[0070] The heat-weldable resin layer 53 is bonded to the barrier layer 52, for example, via the adhesive layer 55. The heat-weldable resin layer 53 included in the outer casing film 50 is a layer that imparts a sealing property to the outer casing film 50 based on heat sealing or other welding processes. Examples of heat-weldable resin layers 53 include resin films composed 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 grafting these polyolefin resins with acids such as maleic anhydride. From the viewpoint of sealing and strength, the thickness of the heat-weldable resin layer 53 is preferably, for example, 20 to 300 μm, more preferably 40 to 150 μm.

[0071] The outer film 50 preferably has one or more buffering layers (hereinafter referred to as "buffer layers") located on the outer side of the heat-bonding resin layer 53, and more preferably on the outer side of the barrier layer 52. The buffer layers may be stacked on the outer side of the substrate layer 51, and the substrate layer 51 may also function as a buffer layer. When the outer film 50 has multiple buffer layers, the multiple buffer layers may be adjacent to each other or stacked with the substrate layer 51 or the barrier layer 52 in between.

[0072] The material constituting the buffer layer can be arbitrarily selected from materials with cushioning properties. Examples of cushioning materials include rubber, nonwoven fabric, or foam sheets. Examples of rubber include natural rubber, fluororubber, or silicone rubber. The rubber hardness is preferably around 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 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 thickness is preferably 5000 μm, and even more preferably 3000 μm. The preferred range for the thickness of the buffer layer is 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. The preferred thickness range for the buffer layer is 1000μm to 3000μm.

[0073] When the buffer layer is made of rubber, the lower limit of the buffer layer thickness is preferably 1 mm, more preferably 0.5 mm. When the buffer layer is made of rubber, the upper limit of the buffer layer thickness is preferably 10 mm, more preferably 5 mm, and even more preferably 2 mm. When the buffer layer is made of rubber, the preferred range of the buffer layer thickness is 1 mm to 10 mm, 1 mm to 5 mm, 1 mm to 2 mm, 0.5 mm to 10 mm, 0.5 mm to 5 mm, and 0.5 mm to 2 mm.

[0074] When the outer film 50 has a buffer layer, the buffer layer functions as a buffer, thus suppressing damage to the outer film 50 caused by the impact of the energy storage device 10 falling or by the operation during the manufacturing of the energy storage device 10.

[0075] As shown in Figure 4, the cover 60 is, for example, a cuboid shape, and may be a resin molded article made of resin material. Alternatively, the cover 60 may be formed by cold forming, for example, the outer film 50, or it may be a metal molded article. The material constituting the cover 60 may include at least two of the following: metal oxides, carbon materials, and rubber materials. Furthermore, to distinguish between a pair of covers 60, in the FB direction, the cover 60 disposed on the first end 201 side of the electrode body 20 is referred to as cover 60A, and the cover disposed on the second end 202 side is referred to as cover 60B. In this embodiment, since cover 60A and cover 60B have the same structure, they are collectively referred to as cover 60 unless there is a specific need to distinguish them.

[0076] The cover 60 has a first surface 61, a second surface 62, and a mating surface 63. The first surface 61 faces the electrode body 20. The second surface 62 is the surface opposite to the first surface 61. The mating surface 63 connects the first surface 61 and the second surface 62 and is mated to the heat-weldable resin layer 53 of the outer film 50. In this embodiment, the mating surface 63 is mated to the heat-weldable resin layer 53 by heat sealing. The mating surface 63 and the outer film 50 can also be mated by any method other than heat sealing, such as welding. The specific welding method can be any method such as laser welding or ultrasonic welding. Alternatively, the cover 60 can also be integrally composed of a component constituting the mating surface 63 (hereinafter also referred to as the "matting surface") and a component constituting at least one part other than the mating surface 63 (hereinafter also referred to as the "cover body"). In this case, the cover body and the mating surface can be made of the same material or different materials. For example, the main body of the cover can be made of a generally plate-shaped metal, and the mating surface can be a frame-shaped resin component that surrounds the main body of the cover, formed by injection molding. The mating surface 63 will be described below.

[0077] The mating surface 63 includes a first sealing surface 63A, a second sealing surface 63B, a third sealing surface 63C, and a fourth sealing surface 63D. The first sealing surface 63A forms the upper surface of the cover 60. In the energy storage device 10, the first sealing surface 63A extends along a first direction (LR direction in this embodiment). The second sealing surface 63B and the third sealing surface 63C are connected to the first sealing surface 63A, forming the side surfaces of the cover 60. In the energy storage device 10, the second sealing surface 63B and the third sealing surface 63C extend along a second direction (UD direction in this embodiment) that intersects the first direction. In this embodiment, the first direction and the second direction are orthogonal. However, the first direction and the second direction may not be orthogonal. The fourth sealing surface 63D forms the lower surface of the cover 60. In the energy storage device 10, the fourth sealing surface 63D extends along the first direction (LR direction in this embodiment).

[0078] When the cover 60 is plate-shaped, even when the energy storage devices 10 are arranged in an overlapping configuration, the cover 60 preferably has a certain thickness in order to suppress deformation of the outer casing 40. In another viewpoint, when the cover 60 is plate-shaped, in order to properly heat-seal the mating surface 63 of the cover 60 to the outer casing film 50 when forming the second sealing portion 80 (described later), the mating surface 63 of the cover 60 preferably has a certain thickness. The minimum thickness of the cover 60 is, for example, 1.0 mm, more preferably 3.0 mm, and even more preferably 4.0 mm. The maximum thickness of the cover 60 is, for example, 20 mm, more preferably 15 mm, and even more preferably 10 mm. The maximum thickness of the cover 60 can also be 20 mm or more. The preferred thickness range for the material constituting the cover 60 is 1.0mm to 20mm, 1.0mm to 15mm, 1.0mm to 10mm, 3.0mm to 20mm, 3.0mm to 15mm, 3.0mm to 10mm, 4.0mm to 20mm, 4.0mm to 15mm, and 4.0mm to 10mm. In this embodiment, when the cover 60 is plate-shaped, it does not consist solely of a film as specified in the [Packaging Terminology] specifications of JIS (Japanese Industrial Standards). Furthermore, the thickness of the cover 60 can vary depending on its location. When the thickness of the cover 60 varies depending on its location, the thickness of the cover 60 is the thickness of the thickest part.

[0079] The cover 60 further includes corner portions 64, 65, 66, and 67. Corner portion 64 is the boundary between the first sealing surface 63A and the second sealing surface 63B. Corner portion 65 is the boundary between the first sealing surface 63A and the third sealing surface 63C. Corner portion 66 is the boundary between the fourth sealing surface 63D and the second sealing surface 63B. Corner portion 67 is the boundary between the fourth sealing surface 63D and the third sealing surface 63C. At least one of the corner portions 64 to 67 may be an angle, or it may be rounded, in other words, it may be rounded by forming an R-surface. In this embodiment, corner portions 64 to 67 are angles. Examples of forming R-surfaces in corner portions 64 to 67 will be described later.

[0080] Here, the outer perimeter of the mating surface 63 is defined as L2. As described above, the outer perimeter L2 is the outer perimeter of the mating surface 63 in the state where it is not mated with the outer film 50. The outer perimeter L2 is determined by converting the pixel dimensions corresponding to the outline of the cover 60A or cover 60B, as determined in step (V), into actual dimensions based on image data of the cover 60A or cover 60B unit taken under conditions (I) to (IV), as explained in the measurement of the outer perimeter L3 described later. As described above, in cover 60A and cover 60B, the outer perimeter L2 of the mating surface 63 is larger than the outer perimeter L1 of the electrode body 20. Furthermore, the difference between the outer perimeter L2 and the outer perimeter L1 is preferably 1 mm or more.

[0081] Furthermore, the outer perimeter of the bonding surface 63, where the cover 60 constitutes the energy storage device 10 or the intermediate body 10A of the energy storage device, and the bonding surface 63 is bonded to the outer film 50, is defined as L3. In the energy storage device 10, when the outer perimeter L3 of the bonding surface 63 of the cover 60A and the cover 60B is larger than the outer perimeter L1' of the electrode body 20, the difference between the outer perimeter L3 and the outer perimeter L1' is preferably 1 mm or more. Furthermore, in the intermediate body 10A of the energy storage device, the outer perimeter L3 of the bonding surface 63 of the cover 60A and the cover 60B is larger than the outer perimeter L1 of the electrode body 20. Additionally, the difference between the outer perimeter L3 and the outer perimeter L1 is preferably 1 mm or more. The outer perimeter L3 is determined by: in image data of the entire cover 60A or cover 60B, determining the number of pixels corresponding to the outer periphery of the second surface 62 of the cover 60A or cover 60B, and converting the pixel number into an actual size. The correspondence between pixels and actual length in image data is predetermined. The conditions for acquiring image data are as follows:

[0082] (I) With the lower surface 42 of the energy storage device 10 facing down, or with the surface of the intermediate body 10A of the energy storage device corresponding to the lower surface 42 facing down, the second surface 62 of the cover 60A or cover 60B is aligned with the lens of the digital camera, and the energy storage device 10 or the intermediate body 10A of the energy storage device is arranged on a horizontal plane in a manner orthogonal to the optical axis of the lens. The digital camera, for example, uses the WG-40 manufactured by RICOH Co., Ltd., which includes an autofocus function, a CMOS image sensor, and an optical zoom of 5x or more.

[0083] (II) The background during shooting is a solid color that is not of the same color as the energy storage device 10 containing the cover 60 or the intermediate body 10A of the energy storage device. Shooting is performed using the autofocus function of a digital camera.

[0084] (III) The number of pixels in the image data output from the image sensor of the digital camera is 4608×3456 (pixels), and the number of recorded pixels is also the same.

[0085] (IV) Of the above recorded pixels, the number of pixels corresponding to cover 60A or cover 60B is more than 30%.

[0086] The outer periphery L3 based on the above image data is determined by the following method.

[0087] (V) From the image data, extract the contour of the end face in a plane orthogonal to the FB direction of the energy storage device 10 or the intermediate body 10A of the energy storage device. The contour extraction is performed using the image processing software ImageJ (National Institutes of Health). First, the image data is denoised. Then, the contour of the end face of the energy storage device 10 or the intermediate body 10A of the energy storage device is extracted by edge detection.

[0088] (VI) Pixels corresponding to the outer film 50 are excluded from the area surrounded by the extracted contours. Here, the outer film 50 forms a first sealing portion 70 in the energy storage device 10. The first sealing portion 70 is formed by joining the end edges of the outer film 50 together. In this embodiment, the root portion 70X of the first sealing portion 70 exists at the boundary between the upper surface 41 and the first side surface 43 of the outer body 40. In the image data, the area corresponding to the first sealing portion 70 is distinguished by an imaginary line C1 extending the contour line of the first side surface 43 of the outer body 40 in the UD direction (see FIG5). Thus, pixels corresponding to the first sealing portion 70 can be excluded from the area surrounded by the extracted contours. In addition, in the intermediate body 10A of the energy storage device, pixels corresponding to the portion of the outer film 50 that forms the first sealing portion 70 and the root portion 70X are determined in the same way as in the energy storage device 10, and are excluded from the area surrounded by the extracted contours.

[0089] (VII) From the outer periphery of the area thus retained, pixels corresponding to the thickness of the outer film 50 are further excluded to determine the pixels corresponding to the outer periphery of the second surface 62 of the cover 60A or cover 60B. The thickness of the outer film 50 is determined by using a laser microscope (e.g., a combination controller VK-X3000 and a head VK-X3050 (manufactured by KEYENCE)) to analyze image data obtained by capturing a cross-section of the outer film 50 contained in the energy storage device 10 or the intermediate body 10A of the energy storage device at any point without processing such as joining or sealing with other components, and using an image analysis program (e.g., a multi-file analysis application VK-X3050, manufactured by KEYENCE). The observation magnification of the head described above is 20x objective lens and 480x total magnification. In the image analysis program, the thickness of the outermost layer (substrate layer 51 in this embodiment) to the innermost layer (thermowelable resin layer 53 in this embodiment) of the outer casing 50, which can be determined from the above image data, is measured.

[0090] In this embodiment, the cover 60 is constructed using a resin material. Here, "constructed using a resin material" means that, when the total material constituting the cover 60 is set to 100% by mass, the resin material content 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. That is, the material constituting the cover 60 may contain materials other than resin material.

[0091] Specific examples of resins include thermoplastic resins such as polyester, polyolefin, polyamide, epoxy resin, acrylic resin, fluoropolymer, polyurethane, silicone resin, and phenolic resin, as well as modified versions of these resins. Additionally, the resin material can be a mixture of these resins, a copolymer, or a modified version of a copolymer. Preferably, the resin material is a thermoplastic resin such as polyester or polyolefin, and more preferably a polyolefin. When the resin material is resin, the cover 60 can be formed by any molding method.

[0092] The resin material contained in the material constituting the cover 60 is preferably an olefin-based random copolymer, more preferably a resin containing a polyolefin backbone as a main component, more preferably a polyolefin as a main component, and even more preferably a polypropylene as a main component. The polyolefin may also be an acid-modified polyolefin. The resin material contained in the material constituting the cover 60 preferably contains a variety of amide-based lubricants. In addition, the resin material contained in the material constituting the cover 60 preferably contains not only saturated fatty acid amides, but also a variety of amide lubricants and unsaturated fatty acid amides. The resin material contained in the material constituting the coating 90 may also be a polyolefin resin with added acrylic elastomers having a melting point higher than 150°C.

[0093] Specifically, examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolyesters. Furthermore, examples of copolyesters include copolyesters whose main body is composed of polyethylene terephthalate as a repeating unit. Specifically, examples include copolymer polyesters polymerized with polyethylene isophthalate as the main repeating unit (hereinafter referred to as poly(terephthalic acid / isophthalic acid) glycol ester), poly(terephthalic acid / adipic acid) glycol ester, poly(terephthalic acid / sodium sulfonate isophthalate) glycol ester, poly(terephthalic acid / sodium isophthalate) glycol ester, poly(terephthalic acid / phenyl dicarboxylic acid) glycol ester, and poly(terephthalic acid / sebacic acid) glycol ester. Among these, from the viewpoint of improving heat resistance and pressure resistance, polybutylene terephthalate is preferred as the resin material.

[0094] In addition, examples of polyolefins include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and other polyethylenes; ethylene-α-olefin copolymers; homopolymer polypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene), propylene-α-olefin copolymers, and terpolymers of ethylene-butene-propylene. Polyolefin resins that are copolymers can be either block copolymers or random copolymers. Among these, polypropylene is preferred from the perspective of excellent heat-melting properties and electrolyte resistance.

[0095] The resin used as the above-mentioned resin material may contain fillers as needed. Specific examples of fillers include glass beads, graphite, glass fiber, and carbon fiber. By containing the above-mentioned fillers in the resin used as the resin material, the resistance of the cover 60 to deformation due to temperature changes can be improved.

[0096] The melt flow rate of the resin material contained in the material constituting the cover 60 is preferably in the range of 1 g / 10 min to 100 g / 10 min, more preferably in the range of 5 g / 10 min to 80 g / 10 min. The melt flow rate is measured based on JIS K7210-1:2014. The melt flow rate is measured at 230°C.

[0097] In another example, the cover 60 may be constructed using a metallic material. Here, "constructed using a metallic material" means that when the total material constituting the cover 60 is 100% by mass, the content of the metallic 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. That is, the material constituting the cover 60 may contain materials other than metallic materials. The metallic material constituting the cover 60 can be chosen arbitrarily. Examples of metallic materials constituting the cover 60 include aluminum, aluminum alloys, nickel, copper, or copper alloys. For example, when the electrode body 20 is a lithium-ion battery, the cover 60 connected to the positive electrode is preferably made of aluminum or an aluminum alloy. The cover 60 connected to the negative electrode is preferably made of nickel, copper, or a copper alloy. The material constituting the cover 60 connected to the negative electrode may also be a material that has been nickel-plated onto copper. The material constituting the cover 60 may also contain recycled metallic materials.

[0098] In this embodiment, a through hole 60X is formed in the cover 60 for inserting the power supply terminal 30. The through hole 60X penetrates the first surface 61 and the second surface 62. With the electrode body 20 covered by the outer film 50, the electrode terminal 30 protrudes to the outside of the outer body 40 through the through hole 60X formed in the cover 60. The small gap between the through hole 60X of the cover 60 and the electrode terminal 30 is filled with resin, for example. Furthermore, in the energy storage device 10, the position where the electrode terminal 30 protrudes to the outside can be arbitrarily selected. For example, the electrode terminal 30 can protrude to the outside from a hole formed on any of the six surfaces of the outer body 40. In this case, the small gap between the outer body 40 and the electrode terminal 30 is filled with resin, for example. In another example, the electrode terminal 30 can also protrude to the outside of the outer body 40 from between the mating surface 63 of the cover 60 and the outer film 50. In this case, the through hole 60X may not be formed in the cover 60. In the energy storage device 10, the cover 60 and the electrode terminal 30 are separately provided, but the cover 60 and the electrode terminal 30 can also be formed integrally. In addition, if the electrode terminal 30 does not protrude from the end edge of the outer body 40, the through hole 60X may not be formed in the cover 60.

[0099] In this embodiment, with the outer film 50 wound around the middle portion 203 of the electrode body 20 and the joint surface 63 of a pair of cover bodies 60, the opposing surfaces of the outer film 50 (thermal fusion resin layers 53) are joined by heat sealing to form a first sealing portion 70.

[0100] The first sealing portion 70 extends along the length direction (FB direction) of the outer casing 40. The location of the first sealing portion 70 within the outer casing 40 can be arbitrarily chosen. In this embodiment, the root portion 70X of the first sealing portion 70 is located at the boundary between the upper surface 41 and the first side surface 43 of the outer casing 40. The area of ​​the upper surface 41 is larger than that of the first side surface 43. The root portion 70X of the first sealing portion 70 can also be located on any surface of the outer casing 40. In this embodiment, the first sealing portion 70 extends further outward than the electrode body 20 when viewed from above. The first sealing portion 70 can be folded towards the upper surface 41 or the first side surface 43 of the outer casing 40, but when determining the outer perimeter L3, it is preferable to extend along either the upper surface 41 or the first side surface 43.

[0101] In this embodiment, the heat-sealing resin layer 53 of the outer film 50 and the mating surface 63 of the cover 60 are heat-sealed to form a second sealing part 80.

[0102] <2. Energy Storage Device Manufacturing Kit>

[0103] The electrode body 20, outer film 50, and a pair of covers 60 described above constitute a battery storage device manufacturing kit 100 for manufacturing the battery storage device 10 of the above embodiment (see FIG6). In this battery storage device manufacturing kit 100, the outer perimeter L1 of the middle portion 203 of the electrode body 20 is smaller than the outer perimeter L2 of the mating surface 63 of the pair of covers 60. As a result, in the winding process of the outer film 50 in the battery storage device manufacturing method described later, unnecessary pressure on the electrode body 20 can be avoided, and at the same time, loosening or wrinkling of the outer film 50 can be prevented on the mating surface 63 of the pair of covers 60, thus achieving a wound state. In addition to the electrode body 20, outer film 50, and pair of covers 60, the battery storage device manufacturing kit 100 may also include, for example, at least one of an electrode terminal 30 and an adhesive film 31.

[0104] <3. Manufacturing Method of Energy Storage Devices>

[0105] Figure 7 is a flowchart illustrating an example of a method for manufacturing a storage device 10 using a storage device manufacturing kit 100. The manufacturing method for the storage device 10 includes, for example, a first step, a second step, a third step, a fourth step, a fifth step, a sixth step, a seventh step, and an eighth step. Steps one through eight are performed, for example, using a manufacturing apparatus for the storage device 10. Furthermore, steps one through eight are designated for ease of explanation of the manufacturing method of the storage device 10 and do not necessarily imply the order of the steps. The order of the following steps can be arbitrarily changed.

[0106] In the first step of step S11 (cover unit manufacturing step), the manufacturing apparatus connects a pair of cover bodies 60 to each of the two electrode terminals 30. By completing the first step, a pair of cover units with electrode terminals 30 connected to the cover bodies 60 are manufactured.

[0107] The second step (electrode placement step) of step S12 is performed in parallel with the first step or after the first step. In the second step, the manufacturing apparatus places the electrode 20 onto the heat-welding resin layer 53 of the outer film 50. Markings may be provided on the outer film 50 to position the electrode 20 appropriately relative to the outer film 50.

[0108] The third step (cover unit configuration step) of step S13 is performed in parallel with the second step or after the second step. In the third step, the manufacturing apparatus configures the pair of cover units produced in step S11 on the first end 201 side and the second end 202 side of the electrode body 20, respectively, and connects the electrode terminals 30 to the electrode body 20. Thus, the outer film 50, the electrode body 20, and the pair of cover units are in the state shown in FIG. 6. Marks may be provided on the outer film 50 to properly position the pair of cover units relative to the outer film 50. Alternatively, as a manufacturing method for the energy storage device 10, the first and third steps may be substituted, and a step may be performed in which the electrode body 20 is pre-connected to the two electrode terminals 30, and then a pair of cover bodies 60 are configured on the first end 201 side and the second end 202 side, respectively, and the pair of cover bodies 60 are connected to the pair of electrode terminals. Furthermore, in the manufacturing method of the energy storage device 10, after arranging a pair of cover bodies 60 or a pair of cover units spaced apart from each other, the electrode body 20 may be arranged between the pair of cover bodies 60 or the pair of cover units, such that the pair of cover bodies 60 or the pair of cover units are respectively arranged on the first end 201 side and the second end 202 side of the electrode body 20. That is, the cover unit arrangement step may also be performed before the electrode body arrangement step.

[0109] The fourth step (winding step) of step S14 is performed after the third step. In the fourth step, the manufacturing apparatus winds the outer film 50 onto the electrode body 20 and the cover unit containing a pair of cover bodies 60. In the fourth step, the manufacturing apparatus bends the outer film 50 at a predetermined position while covering the electrode body 20 and the pair of cover units with the outer film 50 in a manner that surrounds the middle portion 203 and the pair of mating surfaces 63 from the outside. In the fourth step, the manufacturing apparatus winds the outer film 50 onto the electrode body 20 and the pair of cover units while applying tension to the outer film 50, while restricting the movement of the electrode body 20 and the pair of cover units using a limiting member. The limiting member is, for example, a groove for fitting the electrode body 20 and the pair of cover bodies 60. The limiting member can also be a device that applies external force to the electrode body 20 and the pair of cover bodies 60 to prevent the electrode body 20 and the pair of cover bodies 60 from moving. The limiting member can also be a device that applies a force to the electrode body 20 and the cover bodies 60 in the opposite direction to the direction of pulling the outer film 50. Additionally, to eliminate wrinkles in the outer film 50, the limiting component may include a roller that travels on the outer film 50 when it is being pulled. Furthermore, in the winding process, the steps for achieving the winding state are not limited to the winding method described above. For example, as described above, the electrode body 20 may be housed inside the outer film 50 rolled into a cylindrical shape, or at least temporarily fixed in a cylindrical shape to maintain that state, and then the cover 60 may be disposed at each of the pair of openings, followed by applying tension to the outer film 50. Alternatively, an assembly with a pair of cover 60 respectively joined to the first end 201 and the second end 202 of the electrode body 20 may be housed inside the outer film 50 rolled into a cylindrical shape, or at least temporarily fixed in a cylindrical shape to maintain that state, and then tension may be applied to the outer film 50.

[0110] As described above, the outer perimeter L1 of the intermediate portion 203 is smaller than the outer perimeter L2 of the mating surface 63. Therefore, in the fourth process, the pressure generated by the tensioned outer film 50 is mainly applied to the pair of caps 60, and almost not to the electrode body 20. Therefore, when the fourth process is completed, the mating surface 63, the intermediate portion 203, and the outer film 50 are in the relationship shown in FIG. 8, with less pressure applied from the outer film 50 to the intermediate portion 203 compared to the pressure applied from the outer film 50 to the mating surface 63. Furthermore, FIG. 8 is an exaggerated depiction for ease of explanation and does not necessarily reflect actual dimensions.

[0111] The fifth step (first sealing step) of step S15 is performed after the fourth step. In the fifth step, the manufacturing apparatus forms a first sealing portion (hereinafter referred to as the "temporary first sealing portion") having an unsealed portion for injecting electrolyte in a part. In the temporary first sealing portion, the opposing heat-fusible resin layers 53 of the outer casing 50 are bonded. In addition, when the energy storage device 10 is, for example, an all-solid-state battery, the electrolyte injection step is not required, so in the fifth step, the manufacturing apparatus forms the first sealing portion 70.

[0112] The sixth step (second sealing step) of step S16 is performed after the fifth step. In the sixth step, the manufacturing apparatus forms the second sealing portion 80 by joining the heat-melting resin layer 53 constituting the inner surface of the outer casing 50 with the mating surfaces 63 of the pair of caps 60 opposite to it. In this embodiment, the joining of the heat-melting resin layer 53 and the mating surfaces 63 is performed by heat sealing. However, in addition to or instead of the above-mentioned joining method, it can also be performed by ultrasonic sealing, high-frequency sealing or adhesive-based bonding. Through the second sealing step, an intermediate body 10A of the energy storage device (see FIG. 9) is produced, in which the electrode bodies 20 are joined to each other and the pair of caps 60 and the outer casing 50 are housed. The intermediate body 10A of the energy storage device does not contain electrolyte. In the intermediate body 10A of the energy storage device in this embodiment, the outer perimeter L1 of the intermediate portion 203 is smaller than the outer perimeter L3 of the mating surface 63. Therefore, even in the intermediate body 10A of the energy storage device, adverse effects such as the collapse of the stacked structure of the electrode body 20 due to applying unnecessary pressure to the electrode body 20 can be avoided.

[0113] The seventh step (electrolyte injection step) of step S17 is performed after the sixth step. In the seventh step, the manufacturing apparatus injects electrolyte from the unsealed portion formed in the temporary first seal.

[0114] The eighth step (first sealing part formation step) of step S18 is performed after the seventh step. In the eighth step, the manufacturing apparatus forms the first sealing part 70 by heat-sealing a portion of the unsealed part containing the temporary first sealing part. Furthermore, when the energy storage device 10 is, for example, an all-solid-state battery, the seventh and eighth steps are omitted.

[0115] <4. Characteristics>

[0116] According to the above-described energy storage device manufacturing kit 100 and energy storage device manufacturing method, the outer film 50 can be wound seamlessly onto a pair of cover bodies 60, and situations such as collapse of the stacked structure of the electrode body 20 due to unnecessary pressure applied to the electrode body 20 can be avoided. As a result, the possibility of poor bonding between the outer film 50 and the mating surface 63 (in this embodiment, poor sealing of the second sealing portion 80) is reduced. Therefore, the work of repairing poorly bonded parts of the manufactured energy storage device can be omitted. Furthermore, in the energy storage device 10, wrinkles and the like in the second sealing portion 80 are suppressed, ensuring sufficient sealing strength.

[0117] Furthermore, based on the aforementioned energy storage device manufacturing kit 100 and energy storage device manufacturing method, even if the size of the energy storage device 10 changes, the tension in the winding process of the outer film 50 can be significantly altered to achieve the aforementioned effect.

[0118] Furthermore, in the example of implementing the above-described method for manufacturing the energy storage device, it can be verified that the pressure applied from the outer film 50 to the intermediate portion 203 is less than the pressure applied from the outer film 50 to the mating surface 63. In the first step, two electrode terminals 30 are respectively joined to each of a pair of cover bodies 60 of the energy storage device manufacturing kit 100 to create a pair of cover units. In the second and third steps, the electrode body 20 and the pair of cover units are arranged on the outer film 50, with the cover units located on the first end 201 side and the second end 202 side, respectively. Then, the electrode body 20 is joined to the two electrode terminals 30. Here, the pressure-sensitive sheet is arranged to cover the entire mating surface 63 of the electrode body 20 and the pair of cover bodies from above. In the fourth step, while restricting the movement of the electrode body 20 and the pair of cover units, the outer film 50 and the pressure-sensitive sheet are wound around the electrode body 20 and the pair of cover units. At this time, tension is applied to the outer film 50 and the pressure-sensitive sheet in a way that prevents them from shifting. After the outer film 50 and the pressure-sensitive plate are wound around the middle portion 203 and the mating surface 63, the outer film 50 and the pressure-sensitive plate are unwound, and the pressure distribution recorded by the pressure-sensitive plate is verified. Alternatively, the pressure distribution can be verified using analysis software that visualizes the pressure of the pressure-sensitive plate when the outer film 50 and the pressure-sensitive plate are in the wound state. In this case, if there is a region where the gravity of the electrode body 20 is sensed due to the arrangement of the electrode body 20, the pressure distribution in that region is excluded.

[0119] <5. Variations>

[0120] The above embodiments illustrate the possible ways in which the energy storage device and the method for manufacturing the energy storage device of the present invention can be adopted, and are not intended to limit the methods. The energy storage device and the method for manufacturing the energy storage device of the present invention can be adopted in ways different from those illustrated in the embodiments. One example is a way in which a part of the structure of the embodiment is replaced, modified, or omitted, or a new structure is added to the embodiment. Several examples of modifications to the embodiments are shown below. In addition, the following modifications can be combined with each other as long as they are not technically contradictory.

[0121] <5-1>

[0122] In the above embodiment, corners 20A to 20D of the electrode body 20 do not have an R-surface, but at least one of corners 20A to 20D may have an R-surface. In this case, as shown in FIG10A, the outer perimeter L1 or L1' can be adjusted so that the outer perimeter L1 or L1' is smaller than the outer perimeter L2 or L3. That is, the circumscribed quadrilateral of the cross-sectional shape in the cut surface of the middle portion 203 orthogonal to the FB direction is consistent with the circumscribed quadrilateral of the cross-sectional shape in the cut surface of the joint surface 63 orthogonal to the FB direction, but by forming an R-surface in corners 20A to 20D, the outer perimeter L1 or L1' can be made smaller than the outer perimeter L2 or L3. In addition, at least one of the corners 64 to 67 of the pair of cover bodies 60 may have an R-surface. In this case, for example as shown in Figure 10B, by making the radius of curvature of corner portions 20A to 20D greater than the radius of curvature of corner portions 64 to 67, it is possible to make the outer perimeter L1 or outer perimeter L1' smaller than the outer perimeter L2 or outer perimeter L3. Furthermore, while Figures 10A and 10B are explained using cover 60B as an example, the same applies to cover 60A.

[0123] <5-2>

[0124] In the above embodiment, the outer casing 50 of the energy storage device 10 can extend outward in the FB direction beyond at least one of the two covers 60. The electrode body 20 is encapsulated by sealing the portion of the outer casing 50 that extends outward beyond the covers 60. The portion of the outer casing 50 that extends outward beyond the covers 60 can be folded inward like a gable-top container, such that the outer surfaces of the outer casing 50 are in contact with each other, or it can be folded towards any side of the outer casing 40 like a brick pack container.

[0125] <5-3>

[0126] In the above embodiment, the outer casing 40 of the energy storage device 10 and the energy storage device manufacturing kit 100 may not have one of the pair of covers 60. In this variation, in the FB direction, the portion of the outer casing 40 where the cover 60 is omitted is sealed by closing the portion of the outer casing 50 that extends outward beyond the electrode body 20, thereby encapsulating the electrode body 20. The portion of the outer casing 50 that extends outward beyond the electrode body 20 can be folded like a gable-top type container or like a brick-shaped container.

[0127] <5-4>

[0128] In the above embodiment, the outer shape of the outer body 40 can be arbitrarily changed. The outer shape of the outer body 40 can be a cylinder, a prism, or a cube. For example, the electrode body 20 can be formed into a roughly cylindrical shape with the cross-sectional shape of the middle portion 203 of the electrode body 20 being circular, and the cover 60 can be formed into a circular plate shape. In this case, it is only necessary to configure the outer diameter (outer perimeter) L1 or the outer perimeter L1' of the middle portion 203 to be smaller than the outer diameter (outer perimeter) L2 or L3 of the cover 60.

[0129] <5-5>

[0130] In the above embodiment, the pair of cover bodies 60 are formed in a plate shape. However, at least one of the pair of cover bodies 60 may also have a frame-shaped portion extending from the outer periphery of the first surface 61 in the FB direction. Inside the area surrounded by the frame-shaped portion, at least one of the first end 201 and the second end 202 of the electrode body 20 may be at least partially received.

[0131] <5-6>

[0132] In the above embodiment, the entire area between the first surface 61 and the second surface 62 of the cover 60 is designated as the mating surface 63, but it is not necessary for all surfaces connected to the first surface 61 and the second surface 62 to be designated as the mating surface 63. In addition, when the cover 60 has the above-mentioned frame-shaped portion, it is sufficient that at least a portion of the frame-shaped portion in the FB direction is a mating surface.

[0133] <5-7>

[0134] The mating surface of the cover 60 can be an adhesive film integrally bonded to the cover body. The bonding method between the cover body and the mating surface (adhesive film) is not particularly limited; it can be bonding, welding, sealing, etc. The adhesive film is not particularly limited; for example, when the mating surface is formed of metal, it is preferable to use the same film as the adhesive film 31 described above. Alternatively, the adhesive film is preferably a laminated film having at least a heat-melting resin layer, a heat-resistant substrate layer, and a heat-melting resin layer in sequence. In this case, the specifications of the heat-melting resin layer of the adhesive film can be applied to the specifications of the heat-melting resin layer 53. The materials of the two heat-melting resin layers constituting the adhesive film can be the same or different materials, appropriately selected according to the materials of the heat-melting resin layer 53 constituting the outer film 50 and the material constituting the cover body. The material constituting the heat-melting resin layer on the bonding side of the adhesive film to the cover body is preferably an acid-modified polyolefin resin grafted with an acid such as maleic anhydride. The heat-melting resin layer in the adhesive film that adheres to the outer film 50 is preferably made of the same material as the heat-melting resin layer 53 constituting the outer film 50.

[0135] As the heat-resistant substrate layer, any film composed of a heat-resistant resin can be used, such as non-stretch or stretched films made of polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polymethylpentene (registered trademark), polyacetal cyclic polyolefins, polyethylene, polypropylene, etc. Furthermore, polyethylene terephthalate is particularly preferred due to its low cost and high strength.

[0136] <5-8>

[0137] In the above embodiment, the electrode body 20 adopts a so-called stacked type, but the shape of the electrode body 20 is not limited to this. For example, the electrode body 20 can also be configured as a so-called wound type formed by winding the positive and negative electrodes through a diaphragm. In addition, the electrode body 20 can also be configured by stacking multiple wound electrode bodies.

[0138] Figure 11 is a schematic cross-sectional view of a wound electrode 20X housed in the outer casing 40. In the example shown in Figure 11, the number of wound electrode 20s housed in the outer casing 40 is two. The number of wound electrode 20s housed in the outer casing 40 can be one or more. The outer peripheries L1 and L1' of the wound electrode 20X are the sum of the tangents S1 to S4 of the electrode 20X in the cross-sectional view.

[0139] <5-9>

[0140] In the above embodiment, the outer casing 50 of the energy storage device 10 can extend outward in the FB direction to at least one of the two covers 60. The portion of the outer casing 50 extending outward to the cover 60 is closed, thereby encapsulating the electrode body 20. The portion of the outer casing 50 extending beyond the cover 60 can be folded like a gable-roofed bag or a brick-shaped bag. The length of the electrode terminals in the FB direction is preferably a length that allows them to be exposed from the portion of the outer casing 50 extending outward beyond the cover 60.

[0141] <5-10>

[0142] In the above embodiment, the outer casing 40 may also omit one of the two covers 60. In this variation, in the FB direction, the portion of the outer casing 40 without the cover 60 is encapsulated by closing the portion of the outer casing film 50 that extends outward from the electrode body 20. The portion of the outer casing film 50 that extends outward from the electrode body 20 can be folded like a gable-roofed bag or a brick-shaped bag.

[0143] <5-11>

[0144] In the above embodiments, the outer shape of the outer body 40 can be arbitrarily changed. The outer shape of the outer body 40 can be a cylinder, a prism, or a cube, etc.

[0145] Explanation of reference numerals in the attached figures

[0146] 10: Energy storage devices

[0147] 20: Electrode body

[0148] 20A, 20B, 20C, 20D: Corners

[0149] 40: Exterior body

[0150] 50: Exterior film

[0151] 60: Cover

[0152] 64~67: Corner

[0153] 100: Energy Storage Device Manufacturing Kit

[0154] L1: Outer perimeter of the middle section

[0155] L1´: Outer periphery of the middle part

[0156] L2: Outer periphery of the mating surface

[0157] L3: Outer periphery of the mating surface.

Claims

1. An energy storage device, comprising an electrode body and an outer casing sealing the electrode body, characterized in that, The electrode body includes: a first end; a second end disposed at a distance from the first end; and a middle portion extending continuously between the first end and the second end. The outer body includes: an outer film covering the middle portion; and a cover disposed on at least one side of the first end side and the second end side, the cover having a mating surface that engages with the outer film, the outer perimeter of the middle portion being smaller than the outer perimeter of the mating surface.

2. The energy storage device as described in claim 1, characterized in that, The difference between the outer periphery of the middle portion and the outer periphery of the mating surface is 1 mm or more.

3. The energy storage device as described in claim 1 or 2, characterized in that, The intermediate portion has one or more corners with R-shaped surfaces, and the mating surface has one or more corners with R-shaped surfaces. The radius of curvature of one or more corners of the intermediate portion is greater than the radius of curvature of one or more corners of the mating surface.

4. A battery storage device manufacturing kit for manufacturing a battery storage device including an electrode body and an outer casing sealing the electrode body, characterized in that, The electrode body includes: a first end; a second end disposed at a distance from the first end; and a middle portion extending continuously between the first end and the second end. The outer body includes: an outer film for covering the middle portion; and a cover disposed on at least one side of the first end side and the second end side, the cover having a mating surface for engaging with the outer film, the outer perimeter of the middle portion being smaller than the outer perimeter of the mating surface.

5. The energy storage device manufacturing kit as described in claim 4, characterized in that, The difference between the outer periphery of the middle portion and the outer periphery of the mating surface is 1 mm or more.

6. The energy storage device manufacturing kit as described in claim 4 or 5, characterized in that, The intermediate portion has one or more corners with R-shaped surfaces, and the mating surface has one or more corners with R-shaped surfaces. The radius of curvature of one or more corners of the intermediate portion is greater than the radius of curvature of one or more corners of the mating surface.

7. An intermediate for an energy storage device, used in manufacturing an energy storage device comprising an electrode body and an outer casing sealing the electrode body, characterized in that, The electrode body includes: a first end; a second end spaced apart from the first end; and a middle portion extending continuously between the first end and the second end. The outer casing includes: an outer casing film covering the middle portion; and a cover disposed on at least one side of the first end side and the second end side, the cover having a mating surface that engages with the outer casing film. The intermediate body of the energy storage device includes: the electrode body; and the outer casing film and the cover joined together in a manner that accommodates the electrode body. The outer perimeter of the middle portion is smaller than the outer perimeter of the mating surface. The intermediate body of the energy storage device does not contain electrolyte.

8. A method for manufacturing an energy storage device, the energy storage device comprising an electrode body and an outer casing sealing the electrode body, characterized in that, The electrode body includes: a first end; a second end spaced apart from the first end; and a middle portion extending continuously between the first end and the second end. The outer casing includes: an outer film; and a cover having a mating surface to be mated with the outer film. The manufacturing method includes: arranging the cover and the electrode body such that the cover is located on at least one side of the first end and the second end; forming the outer film to be wound around the cover and the electrode body such that it covers the mating surface of the cover and the middle portion of the electrode body; and forming an intermediate body of a storage device in which the electrode body is housed within the cover and the outer film by mating the mating surface with the outer film, wherein the intermediate body of the storage device does not contain an electrolyte, and in the intermediate body of the storage device, the outer perimeter of the middle portion is smaller than the outer perimeter of the mating surface.

9. The method for manufacturing the energy storage device as described in claim 8, characterized in that, It also includes the step of injecting the electrolyte into the interior of the joined cap and outer membrane.

10. A method for manufacturing an energy storage device, the energy storage device comprising an electrode body and an outer casing sealing the electrode body, characterized in that, The electrode body includes: a first end portion; a second end portion disposed at a distance from the first end portion; and a middle portion extending continuously between the first end portion and the second end portion. The outer casing includes: an outer casing film; and a cover having a mating surface to be engaged with the outer casing film, wherein the outer perimeter of the middle portion is smaller than the outer perimeter of the mating surface. The manufacturing method includes: arranging the cover and the electrode body such that the cover is located on at least one side of the first end portion and the second end portion; forming a state in which the outer casing film is wound around the cover and the electrode body such that it covers the mating surface of the cover and the middle portion of the electrode body; and engaging the mating surface with the outer casing film.

11. A method for manufacturing an energy storage device, the energy storage device comprising an electrode body and an outer casing sealing the electrode body, characterized in that, The electrode body includes: a first end portion; a second end portion disposed at a distance from the first end portion; and a middle portion extending continuously between the first end portion and the second end portion. The outer casing includes: an outer casing film; and a cover having a mating surface to be mated with the outer casing film. The manufacturing method includes: arranging the cover and the electrode body such that the cover is located on at least one side of the first end portion and the second end portion; forming a state in which the outer casing film is wound around the cover and the electrode body such that it covers the mating surface of the cover and the middle portion of the electrode body; and mating the mating surface with the outer casing film. The step of forming a state in which the outer casing film is wound around the cover and the electrode body includes forming a state in which the pressure applied from the outer casing film to the mating surface is greater than the pressure applied from the outer casing film to the middle portion.

Images