Energy storage device and method for manufacturing an energy storage device

Abstract

To provide a power storage device capable of suppressing unevenness in the distribution of pressure applied to adjacent power storage devices when multiple power storage devices are stacked, and a method for manufacturing the power storage device.SOLUTION: A power storage device includes an electrode body and an exterior body. The exterior body seals the electrode body. The exterior body is made of a film-like exterior member. The exterior body includes a first sealing portion sealed by joining opposing surfaces together when wrapped around the electrode body. A base portion of the first sealing portion is formed at the boundary between the first surface and the second surface of the exterior body. The area of the first surface is larger than the area of the second surface. The first sealing portion does not overlap with the first surface in a plan view.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a power storage device and a method for manufacturing the power storage device.

Background Art

[0002] Japanese Patent No. 4509242 (Patent Document 1) discloses a secondary battery. In this secondary battery, an electrode body is sealed in a bag body composed of a laminate film (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the secondary battery disclosed in the above Patent Document 1, a seal portion of a laminate film is provided on a surface having a large area. Since the seal portion is an area where the films overlap, it is thicker than other areas. When another secondary battery is stacked on the surface provided with the seal portion, the upper secondary battery may tilt with the seal portion as a fulcrum. As a result, the unevenness of the pressure distribution applied to the lower secondary battery increases. Also, when a plurality of secondary batteries are arranged side by side such that the surface provided with the seal portion contacts an adjacent secondary battery, the unevenness of the pressure distribution applied from the adjacent secondary batteries increases.

[0005] The present invention has been made to solve such problems, and an object thereof is to provide a power storage device and a method for manufacturing the power storage device capable of suppressing unevenness in the pressure distribution applied to adjacent power storage devices when a plurality of power storage devices are stacked.

Means for Solving the Problems

[0006] An energy storage device according to a certain aspect of the present invention comprises an electrode body and an outer casing. The outer casing seals the electrode body. The outer casing is composed of a film-like outer casing member. The outer casing includes a first sealing portion, which is sealed by joining surfaces facing each other when the outer casing member is wrapped around the electrode body. The base portion of the first sealing portion is formed at the boundary between a first surface and a second surface in the outer casing. The area of ​​the first surface is larger than the area of ​​the second surface. In a plan view, the first sealing portion does not overlap with the first surface.

[0007] In this energy storage device, the first sealing portion does not overlap with the first surface, which has a larger area, in a plan view. That is, the first sealing portion does not exist on the first surface, which has a larger area. Therefore, even if other energy storage devices are placed on top of or next to the first surface, these other energy storage devices will not tilt. As a result, this energy storage device can suppress uneven pressure distribution between adjacent energy storage devices when multiple energy storage devices are stacked. Furthermore, in this energy storage device, the base portion of the first sealing portion is located on the boundary between the first and second surfaces of the outer casing. Therefore, with this energy storage device, when the first sealing portion is placed on the second surface, a wider bonding width can be secured at the first sealing portion compared to when the base portion of the first sealing portion is on the second surface.

[0008] In the above-described energy storage device, the first sealing portion may be bent so as to be in contact with the second surface.

[0009] In the above-described energy storage device, the first sealing portion may be bent so as to be in contact with the second surface, thereby covering substantially the entire second surface.

[0010] With this energy storage device, the first sealing portion covers substantially the entire second surface, thereby ensuring a wide bonding width in the first sealing portion.

[0011] The above-described energy storage device further comprises electrode terminals electrically connected to an electrode body, and the outer casing further includes a second sealing portion sealed with the electrode terminals sandwiched between them, with a portion of the electrode terminals located outside the outer casing, and the base portion of the portion may be located at approximately half the thickness of the energy storage device in the thickness direction of the energy storage device.

[0012] In this energy storage device, a portion of the electrode terminals that is on the outside of the outer casing is located at approximately half the thickness of the energy storage device in the thickness direction. Therefore, with this energy storage device, for example, compared to the case where the portion is located at approximately the same position as the first surface in the thickness direction of the energy storage device, the difference between the longest and shortest distances between each of the multiple electrodes included in the electrode body and the electrode terminal can be reduced.

[0013] In the above-described energy storage device, in the first sealing portion, regions where the bonding force between the surfaces is strong and regions where the bonding force between the surfaces is weak may be arranged along the boundary.

[0014] In the above-described energy storage device, the first sealing portion may have a thin region and a thick region arranged along the boundary.

[0015] The above-described energy storage device further includes electrode terminals electrically connected to the electrode body, and the first sealing portion may be sealed with the electrode terminals sandwiched between them.

[0016] The above-described energy storage device further comprises electrode terminals electrically connected to an electrode body and a cover body to which the electrode terminals are attached, and the outer casing may further include a second sealing portion sealed in a state joined to the cover body.

[0017] In the above-described energy storage device, the cover includes a first surface facing the electrode body and a second surface opposite to the first surface, and the second sealing portion may include a portion to which the outer casing and the second surface are joined.

[0018] In the above-described energy storage device, the device further comprises a lid, the outer casing further includes a second sealing portion sealed in a state joined to the lid, the lid includes a metal portion which is a portion in which a metal layer is exposed on the surface, or a portion which is made of a metal material, and the metal portion and the electrode body may be welded together.

[0019] The above-described energy storage device further comprises electrode terminals electrically connected to an electrode body, and the outer casing may further include an outwardly protruding portion and a second sealing portion that seals the electrode terminals while sandwiched between the protruding portion.

[0020] In the above-described energy storage device, the direction along the boundary may be perpendicular to the flow direction of the exterior material.

[0021] In this energy storage device, when the first sealing portion is bent along the boundary, the direction along the boundary is perpendicular to the flow direction of the outer casing member. Therefore, with this energy storage device, even if a fold is formed in a direction perpendicular to the flow direction of the outer casing member, the outer casing member is less likely to break, thus reducing the possibility of the first sealing portion breaking when it is bent.

[0022] A power storage device according to another aspect of the present invention comprises an electrode body, electrode terminals electrically connected to the electrode body, and an outer casing that seals the electrode body. The outer casing is made of a film-like outer casing member and includes a long side and a short side in a plan view. The electrode terminals are arranged along the long side.

[0023] A power storage device according to another aspect of the present invention includes an electrode body and an exterior body. The exterior body seals the electrode body. The exterior body is composed of a film-like exterior member. The exterior body includes a piece portion where the peripheries of the surfaces facing each other are joined together in a state of being wound around the electrode body. The base portion of the piece portion is formed at the boundary between the surfaces in the exterior body. A space where the surfaces facing each other are not joined is formed within the piece portion. In the piece portion, a region where the surfaces facing each other are joined and a region where the surfaces facing each other are not joined are arranged side by side near the boundary.

[0024] Gas can be generated inside the exterior body. In this power storage device, a space is formed within the piece portion, and a region where the surfaces facing each other are joined and a region where the surfaces facing each other are not joined are arranged side by side near the boundary. Therefore, according to this power storage device, by releasing the sealing state of the exterior body in the piece portion, the gas inside the exterior body can be discharged through the piece portion. Then, by sealing the exterior body again, a power storage device after degassing can be manufactured.

[0025] A method for manufacturing a power storage device according to another aspect of the present invention is a manufacturing method for manufacturing a power storage device from an unfinished product. The unfinished product includes an electrode body and an exterior body. The exterior body seals the electrode body. The exterior body is composed of a film-like exterior member. The exterior body includes a piece portion where the peripheries of the surfaces facing each other are joined together in a state of being wound around the electrode body. The base portion of the piece portion is formed at the boundary between the surfaces in the exterior body. A space where the surfaces facing each other are not joined is formed within the piece portion. In the piece portion, a region where the surfaces facing each other are joined and a region where the surfaces facing each other are not joined are arranged side by side near the boundary. The manufacturing method includes a step of releasing the sealing state of the exterior body in the piece portion and discharging the gas to the outside of the exterior body, and a step of resealing the exterior body by joining the surfaces facing each other in at least a part of the piece portion.

[0026] According to the method for manufacturing this power storage device, a power storage device after degassing can be manufactured by discharging gas through one part and then sealing the exterior body again.

Advantages of the Invention

[0027] According to the present invention, it is possible to provide a power storage device capable of suppressing unevenness in the distribution of pressure applied to a lower power storage device when a plurality of power storage devices are stacked, and a method for manufacturing the power storage device.

Brief Description of the Drawings

[0028] [Figure 1] It is a perspective view schematically showing a power storage device according to Embodiment 1. [Figure 2] It is a plan view schematically showing the power storage device. [Figure 3] It is a side view schematically showing the power storage device. [Figure 4] It is a view showing, from the side, the state in which an exterior member is wound around an electrode body during the manufacture of the power storage device according to Embodiment 1. [Figure 5] It is a view showing, from below, the state in which an exterior member is wound around an electrode body during the manufacture of the power storage device according to Embodiment 1. [Figure 6] It is a view schematically showing a part of the cross-section VI-VI of FIG. 2. [Figure 7] It is a view for explaining a method for forming the second sealing portion. [Figure 8] It is a flowchart showing the manufacturing procedure of the power storage device according to Embodiment 1. [Figure 9] It is a plan view schematically showing a power storage device according to Embodiment 2. [Figure 10] It is a side view schematically showing the power storage device. [Figure 11] It is a perspective view schematically showing a lid body. [Figure 12] It is a view showing a first example in which a lid body and an electrode terminal are integrally formed. [Figure 13]This figure shows a second example in which the cover and electrode terminals are integrally formed. [Figure 14] This is a flowchart showing the manufacturing procedure for an energy storage device according to Embodiment 2. [Figure 15] This flowchart shows another manufacturing procedure for an energy storage device according to Embodiment 2. [Figure 16] This diagram shows the electrode body with the outer covering wrapped around it, as viewed from the side, in Embodiment 3. [Figure 17] This figure shows, from below, the state in which the outer casing member is wrapped around the electrode body and the lid is attached to the outer casing member in Embodiment 3. [Figure 18] This is a flowchart showing the manufacturing procedure for an energy storage device according to Embodiment 3. [Figure 19] This is a schematic plan view showing an energy storage device according to Embodiment 4. [Figure 20] This is a schematic side view showing an energy storage device according to Embodiment 4. [Figure 21] This diagram shows a modified example, with the outer covering wrapped around the electrode body, viewed from the side. [Figure 22] This is a schematic perspective view showing a modified energy storage device. [Figure 23] This is a schematic perspective view showing a modified cover and electrode terminals attached to the cover. [Figure 24] Figure 23 is a schematic perspective view showing the energy storage device with the cover attached. [Figure 25] This is a schematic front view showing the lid of another modified example. [Figure 26] This is a schematic front view showing the lid of yet another modified example. [Figure 27] This is a schematic plan view showing another modified example of an energy storage device. [Modes for carrying out the invention]

[0029] Embodiments of the present invention will be described in detail below with reference to the drawings. In the drawings, identical or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.

[0030] [1. Embodiment 1] <1-1. Configuration of Energy Storage Devices> Figure 1 is a schematic perspective view showing an energy storage device 10 according to this embodiment 1. Figure 2 is a schematic plan view showing the energy storage device 10. Figure 3 is a schematic side view showing the energy storage device 10. In Figures 2 and 3, the arrow UD indicates the thickness direction of the energy storage device 10, and the arrow LR indicates the width direction of the energy storage device 10. The arrow FB indicates the depth direction of the energy storage device 10. The directions indicated by arrows UDLRFB are common to all subsequent figures.

[0031] Referring to Figures 1, 2, and 3, the energy storage device 10 includes an electrode body 200, an outer casing 100, and a plurality (two) of electrode terminals 300. The electrode body 200 includes electrodes (positive and negative electrodes) and separators that constitute an energy storage component such as a lithium-ion battery, capacitor, or all-solid-state battery. The shape of the electrode body 200 is approximately a rectangular parallelepiped. Note that "approximately a rectangular parallelepiped" includes not only a perfect rectangular parallelepiped but also a three-dimensional object that can be considered a rectangular parallelepiped by, for example, modifying the shape of a part of its outer surface.

[0032] The electrode terminal 300 is a metal terminal used for power input and output in the electrode body 200. One end of the electrode terminal 300 is electrically connected to an electrode (positive or negative electrode) contained in the electrode body 200, and the other end protrudes outward from the edge of the outer casing 100.

[0033] The metal materials that make up the electrode terminals 300 are, for example, aluminum, nickel, copper, etc. For example, if the electrode body 200 is a lithium-ion battery, the electrode terminals 300 connected to the positive electrode are usually made of aluminum, etc., and the electrode terminals 300 connected to the negative electrode are usually made of copper, nickel, etc.

[0034] The outer casing 100 is made up of a film-like outer casing member 101 (Figure 4, etc.) and seals the electrode body 200. In the energy storage device 10, the outer casing 100 is formed by wrapping the outer casing member 101 around the electrode body 200 and sealing the open portion.

[0035] For example, one method is to form a housing portion (recess) for housing the electrode body 200 in the exterior member 101 through cold forming. However, it is not always easy to form a deep housing portion by such a method. If one attempts to form a deep housing portion (recess) (for example, a forming depth of 15 mm) by cold forming, there is a high possibility that pinholes or cracks will occur in the exterior member, leading to a decrease in battery performance. On the other hand, the exterior member 100 seals the electrode body 200 by wrapping the exterior member 101 around the electrode body 200, so the electrode body 200 can be easily sealed regardless of the thickness of the electrode body 200. Furthermore, in order to reduce the dead space between the electrode body 200 and the exterior member 101 in order to improve the volumetric energy density of the energy storage device 10, it is preferable that the exterior member 101 is wrapped so as to be in contact with the outer surface of the electrode body 200. Furthermore, in all-solid-state batteries, it is necessary to apply high pressure uniformly from the outside of the battery in order to achieve optimal battery performance. Therefore, it is preferable that the outer casing member 101 is wrapped around the outer surface of the electrode body 200 so that it is in contact with the outer surface of the electrode body 200.

[0036] The exterior member 101 is, for example, a laminate (laminate film) having a base layer, a barrier layer, and a heat-sealable resin layer in that order. However, the exterior member 101 does not necessarily need to include all of these layers; for example, it may not include a barrier layer. That is, the exterior member 101 only needs to be made of a flexible and easily bendable material, such as a resin film. It is preferable that the exterior member 101 is heat-sealable.

[0037] The base layer included in the exterior member 101 is a layer that imparts heat resistance to the exterior member 101 and suppresses the occurrence of pinholes that may occur during processing or distribution. The base layer is composed of, for example, at least one stretched polyester resin layer and a stretched polyamide resin layer. For example, by including at least one stretched polyester resin layer and a stretched polyamide resin layer in the base layer, the barrier layer can be protected during processing of the exterior member 101, and the breakage of the exterior member 101 can be suppressed. Furthermore, from the viewpoint of increasing the tensile elongation of the exterior member 101, the stretched polyester resin layer is preferably a biaxially oriented polyester resin layer, and the stretched polyamide resin layer is preferably a biaxially oriented polyamide resin layer. Moreover, from the viewpoint of excellent puncture strength or impact strength, the stretched polyester resin layer is more preferably a biaxially oriented polyethylene terephthalate (PET) film, and the stretched polyamide resin layer is more preferably a biaxially oriented nylon (ONy) film. The base layer may also be composed of both the stretched polyester resin layer and the stretched polyamide resin layer. The thickness of the substrate layer is preferably, for example, 5 to 300 μm, and more preferably 20 to 150 μm, from the viewpoint of film strength.

[0038] Furthermore, the barrier layer included in the outer casing member 101 is made of, for example, aluminum foil, from the viewpoint of moisture resistance, processability such as ductility, and cost. The aluminum foil preferably contains iron from the viewpoint of packaging suitability and pinhole resistance when packaging the electrode body 200. The iron content in the aluminum foil is preferably 0.5 to 5.0 mass%, and more preferably 0.7 to 2.0 mass%. An iron content of 0.5 mass% or more provides packaging suitability, excellent pinhole resistance, and ductility of the outer casing member 101. An iron content of 5.0 mass% or less provides excellent flexibility of the outer casing member 101.

[0039] The thickness of the barrier layer is preferably 15 to 100 μm, and more preferably 30 to 80 μm, from the viewpoint of barrier properties, pinhole resistance, and packaging suitability. A barrier layer thickness of 15 μm or more makes it difficult for the outer packaging member 101 to break even when stress is applied during packaging. A barrier layer thickness of 100 μm or less reduces the mass increase of the outer packaging member 101 and suppresses the decrease in the gravimetric energy density of the energy storage device 10.

[0040] Furthermore, if the barrier layer is aluminum foil, it is preferable to have a corrosion-resistant coating on at least the side opposite to the base layer to prevent dissolution and corrosion. The barrier layer may also have a corrosion-resistant coating on both sides. Here, a corrosion-resistant coating refers to a thin film that provides the barrier layer with corrosion resistance (e.g., acid resistance, alkali resistance) by performing treatments such as hot water modification treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment with nickel or chromium, or corrosion prevention treatment by applying a coating agent to the surface of the barrier layer. Specifically, a corrosion-resistant coating means a coating that improves the acid resistance of the barrier layer (acid-resistant coating), a coating that improves the alkali resistance of the barrier layer (alkali-resistant coating), etc. One type of treatment may be performed to form the corrosion-resistant coating, or two or more types may be combined. In addition, it is possible to have multiple layers instead of just one. Furthermore, among these treatments, hot water modification treatment and anodizing treatment are treatments that dissolve the surface of the metal foil with a treatment agent and form a metal compound with excellent corrosion resistance. These treatments may also be included in the definition of chemical conversion treatment. Furthermore, if the barrier layer includes a corrosion-resistant coating, the barrier layer will include this coating.

[0041] The corrosion-resistant coating prevents delamination between the barrier layer (e.g., aluminum alloy foil) and the base layer during the molding of the exterior member 101, prevents dissolution and corrosion of the barrier layer surface due to hydrogen fluoride generated by the reaction of electrolyte and water, and in particular prevents the dissolution and corrosion of aluminum oxide present on the barrier layer surface when the barrier layer is aluminum alloy foil, and improves the adhesion (wettability) of the barrier layer surface, thereby preventing delamination between the base layer and the barrier layer during heat sealing and molding.

[0042] Furthermore, the heat-sealable resin layer included in the exterior member 101 is a layer that provides the exterior member 101 with heat-sealing sealing properties. Examples of heat-sealable resin layers include resin films made of polyolefin resin or acid-modified polyolefin resin obtained by graft-modifying a polyolefin resin with an acid such as maleic anhydride. The thickness of the heat-sealable resin layer is preferably, for example, 20 to 300 μm, and more preferably 40 to 150 μm, from the viewpoint of sealing properties and strength.

[0043] The exterior member 101 preferably has one or more layers having a buffering function (hereinafter referred to as "buffering layers") outside the heat-fusible resin layer, and more preferably outside the barrier layer. The buffering layers may be laminated on the outside of the base layer, or the base layer may also have the function of a buffering layer. If the exterior member 101 has multiple buffering layers, the multiple buffering layers may be adjacent to each other, or they may be laminated via a base layer or a barrier layer, etc.

[0044] The materials constituting the buffer layer can be arbitrarily selected from materials having cushioning properties. Examples of cushioning materials include rubber, nonwoven fabric, or foamed sheet. Examples of rubber include natural rubber, fluororubber, or silicone rubber. The rubber hardness is preferably around 20 to 90. The materials constituting the nonwoven fabric are preferably materials 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 still 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 still more preferably 3000 μm. The preferred thickness ranges for the buffer layer are 100 μm to 5000 μm, 100 μm to 3000 μm, 200 μm to 3000 μm, 1000 μm to 5000 μm, or 1000 μm to 3000 μm. Among these, the most preferred thickness range for the buffer layer is 1000 μm to 3000 μm.

[0045] When the buffer layer is made of rubber, the lower limit of the buffer layer thickness is preferably 0.5 mm. When the buffer layer is made of rubber, the upper limit of the buffer layer thickness is preferably 10 mm, more preferably 5 mm, and still more preferably 2 mm. When the buffer layer is made of rubber, the preferred range of the buffer layer thickness is 0.5 mm to 10 mm, 0.5 mm to 5 mm, or 0.5 mm to 2 mm.

[0046] If the exterior member 101 has a buffer layer, the buffer layer functions as a cushion, thus preventing damage to the exterior member 101 from impact when the energy storage device 10 is dropped or from handling during the manufacturing of the energy storage device 10.

[0047] Figure 4 is a side view showing the state in which the outer covering member 101 is wrapped around the electrode body 200 during the manufacturing process of the energy storage device 10. As shown in Figure 4, the outer covering member 101 is wrapped around the electrode body 200. In this case, the outermost layer of the electrode body 200 does not necessarily have to be an electrode; for example, it may be a protective tape or a separator. With the outer covering member 101 wrapped around the electrode body 200, the first sealing portion 110 is formed by heat sealing the opposing surfaces (heat-fusible resin layers) of the outer covering member 101 together.

[0048] The base portion of the first sealing portion 110 lies on edge 135 of the outer casing 100. Edge 135 is formed at the boundary between the first surface 130 and the second surface 140, which has a smaller area than the first surface 130. In other words, the base portion of the first sealing portion 110 is formed at the boundary between the first surface 130 and the second surface 140, and does not lie on either the first surface 130 or the second surface 140. In the energy storage device 10, the first sealing portion 110 is bent towards the second surface 140 with edge 135 as the center. In the energy storage device 10, the first sealing portion 110 is in contact with the second surface 140 and covers substantially the entire second surface 140. Note that "substantially the entire second surface 140" means the area occupying 75% or more of the area of ​​the second surface 140.

[0049] In other words, in the energy storage device 10, the first sealing portion 110 is not formed on the first surface 130, which has a large surface area. The first surface 130 is flatter than when a sealing portion such as the first sealing portion 110 is in contact with the first surface 130. Therefore, even if another energy storage device 10 is placed on the first surface 130, the other energy storage device 10 will not tilt. As a result, with the energy storage device 10, when multiple energy storage devices 10 are stacked, unevenness in the pressure distribution applied to the lower energy storage devices 10 can be suppressed. In other words, when multiple energy storage devices 10 are stacked to form a module, the first sealing portion 110 is not placed on the surface (first surface 130) adjacent to the adjacent energy storage device 10. Furthermore, in all-solid-state batteries, this configuration is preferable from the viewpoint that it is necessary to apply high pressure uniformly from the outside of the battery in order to achieve battery performance.

[0050] Furthermore, in the energy storage device 10, the base portion of the first sealing portion 110 is located on the edge 135 of the outer casing 100. Therefore, with the energy storage device 10, a wider bonding area can be secured in the first sealing portion 110 compared to when the base portion of the first sealing portion 110 is located on the second surface 140 (for example, the central portion of the second surface 140 in the direction of arrow UD). Note that the bonding area of ​​the first sealing portion 110 does not necessarily have to be the entire area of ​​the first sealing portion 110, but may be a part of the first sealing portion 110, such as only the vicinity of the base portion of the first sealing portion 110.

[0051] Furthermore, in the energy storage device 10, substantially the entire second surface 140 is covered by the first sealing portion 110. That is, in the energy storage device 10, for example, the length of the first sealing portion 110 in the direction of arrow UD is longer compared to a case where the first sealing portion 110 covers less than half of the area of ​​the second surface 140 (see Figure 3). Therefore, with the energy storage device 10, a wide bonding area can be secured in the first sealing portion 110. Also, because substantially the entire second surface 140 is covered by the first sealing portion 110, the energy storage device 10 remains stable even if it is positioned upright so that the second surface 140 is in contact with the mounting surface. That is, the energy storage device 10 is less likely to tilt relative to the mounting surface. Therefore, such a configuration is effective, for example, when multiple energy storage devices 10 are arranged side by side to form a module.

[0052] Figure 5 is a view from below showing the state in which the outer casing member 101 is wrapped around the electrode body 200 during the manufacturing process of the energy storage device 10. As shown in Figure 5, in the energy storage device 10, the direction along the edge 135 is the TD (Transverse Direction) of the outer casing member 101, and the direction perpendicular to the edge 135 is the MD (Machine Direction) of the outer casing member 101. In other words, the direction along the edge 135 is the direction (TD) perpendicular to the flow direction (MD) of the outer casing member 101.

[0053] In the energy storage device 10, the first sealing portion 110 is bent along the edge 135, and the direction along the edge 135 is perpendicular to the flow direction of the outer casing member 101. Therefore, with the energy storage device 10, even if a fold is formed in a direction perpendicular to the flow direction of the outer casing member 101, the outer casing member 101 is less likely to break, thus reducing the possibility of the first sealing portion 110 breaking due to bending.

[0054] The flow direction (MD) of the exterior member 101 corresponds to the rolling direction (RD) of the metal foil (aluminum alloy foil, etc.) of the barrier layer contained in the exterior member 101. The TD of the exterior member 101 corresponds to the TD of the metal foil. The rolling direction (RD) of the metal foil can be determined by the rolling pattern.

[0055] Furthermore, by observing multiple cross-sections of the heat-fusible resin layer of the exterior member 101 with an electron microscope to confirm the sea-island structure, the direction parallel to the cross-section where the average diameter of the islands in the direction perpendicular to the thickness direction of the heat-fusible resin layer (hereinafter also referred to as the "length direction of the heat-fusible resin layer") was maximum can be determined as the MD (Mass Distribution). This method can be used to identify the MD of the exterior member 101 when it cannot be identified by the rolling marks of the metal foil.

[0056] Specifically, the sea-island structure is confirmed by observing electron microscope images of each of the following cross-sections (a total of 10 cross-sections): a cross-section along the length of the heat-fusible resin layer, and cross-sections at 10-degree increments from a direction parallel to the length of the heat-fusible resin layer, up to a direction perpendicular to the length of the layer. Next, the diameter d of each island on each cross-section is measured by the straight-line distance connecting the two ends in a direction perpendicular to the thickness direction of the heat-fusible resin layer. Then, for each cross-section, the average of the top 20 island diameters d is calculated. Finally, the direction parallel to the cross-section with the largest average island diameter d is determined to be the MD (Mass Distribution).

[0057] Figure 6 is a schematic diagram showing a portion of the VI-VI cross-section in Figure 2. As shown in Figure 6, the second sealing portion 120 is sealed with the outer casing 100 sandwiching the electrode terminals 300.

[0058] Figure 7 is a diagram illustrating the method for forming the second sealing portion 120. As shown in Figure 7, the exterior member 101 is folded, and the second sealing portion 120 is formed by heat sealing the opposing surfaces (heat-fusible resin layers) of the exterior member 101 together. Although not shown in Figure 7, electrode terminals 300 are located between the opposing surfaces of the exterior member 101. An adhesive film that adheres to both metal and resin may be placed between the electrode terminals 300 and the exterior member 101.

[0059] Referring again to Figure 6, the electrode body 200 includes a plurality of electrodes 210 (positive and negative electrodes). Current collectors 215 extending from each electrode 210 are connected to electrode terminals 300. In the energy storage device 10, a portion of the electrode terminals 300 that is outside the outer casing 100 is located at approximately half the thickness of the energy storage device 10 in the thickness direction of the energy storage device 10. That is, length L2 is approximately half the length L1. Note that "approximately half the thickness of the energy storage device 10" means 35% to 65% of the thickness of the energy storage device 10.

[0060] Therefore, with the energy storage device 10, for example, compared to the case where the electrode terminal 300 is located at approximately the same position as the first surface 130 in the thickness direction of the energy storage device 10, the difference between the longest distance and the shortest distance between each of the multiple electrodes 210 and the electrode terminal 300 can be reduced.

[0061] <1-2. Manufacturing method of an energy storage device> Figure 8 is a flowchart showing the manufacturing procedure for the energy storage device 10. The steps shown in Figure 8 are performed, for example, by a manufacturing apparatus for the energy storage device 10.

[0062] The manufacturing apparatus wraps the outer casing member 101 around the electrode body 200 (step S100). The manufacturing apparatus forms the first sealing portion 110 by heat sealing the opposing surfaces (heat-fusible resin layers) of the outer casing member 101 together (step S110). This produces the unfinished product shown in Figures 4 and 5.

[0063] The manufacturing apparatus bends the first sealing portion 110 so that it contacts the second surface 140 (step S120). The manufacturing apparatus folds the outer casing member 101 with the electrode body 200 housed inside, and forms the second sealing portion 120 by heat sealing the opposing surfaces (heat-fusible resin layers) of the outer casing member 101 together (step S130). This completes the energy storage device 10.

[0064] <1-3. Features> As described above, in the energy storage device 10 according to this embodiment 1, the first sealing portion 110 is folded towards the second surface 140, which has a smaller area. That is, the first sealing portion 110 does not exist on the first surface 130, which has a larger area. Therefore, even if another energy storage device 10 is placed on the first surface 130, the other energy storage device 10 will not tilt. As a result, with the energy storage device 10, when multiple energy storage devices 10 are stacked, unevenness in the pressure distribution applied to the lower energy storage device 10 can be suppressed. Furthermore, when used in an all-solid-state battery, it is necessary to apply high pressure uniformly from the outside of the battery in order to achieve battery performance, so the packaging form of the present invention is preferred. In addition, in the energy storage device 10, the base portion of the first sealing portion 110 is located on the side 135 of the outer casing 100. Therefore, with the energy storage device 10, when the first sealing portion 110 is fitted onto the second surface 140, a wider bonding width can be secured in the first sealing portion 110 compared to when the base portion of the first sealing portion 110 is on the second surface 140.

[0065] [2. Embodiment 2] In the energy storage device 10 according to Embodiment 1 described above, the second sealing portion 120 is formed by folding the exterior member 101 and heat-sealing the opposing surfaces of the exterior member 101. However, the shape and formation method of the second sealing portion 120 are not limited thereto. In the following, we will mainly describe the parts that differ from Embodiment 1, and will omit the description of parts that are common to Embodiment 1.

[0066] <2-1. Configuration of Energy Storage Devices> Figure 9 is a schematic plan view showing the energy storage device 10X according to this second embodiment. Figure 10 is a schematic side view showing the energy storage device 10X. Figure 11 is a schematic perspective view showing the lid 400.

[0067] Referring to Figures 9, 10, and 11, the outer casing 100X is constructed by fitting a cover 400 into each of the openings at both ends of the outer casing member 101 that is wrapped around the electrode body 200. With the cover 400 fitted, the second sealing portion 120X is formed by heat sealing the outer casing member 101 and the cover 400.

[0068] The lid 400 is a bottomed tray-shaped member with a rectangular shape in plan view, and is formed by, for example, cold forming the exterior member 101. The lid 400 does not necessarily have to be made of the exterior member 101; it may be a metal molded product or a resin molded product. In the energy storage device 10X, the lid 400 is positioned such that its bottom surface is located inside the exterior member 100X. However, in the energy storage device 10X, the bottom surface of the lid 400 does not necessarily have to be located inside the exterior member 100X. In the energy storage device 10X, the bottom surface of the lid 400 may be located outside the exterior member 100X.

[0069] Furthermore, with the electrode body 200 housed, the electrode terminal 300 protrudes to the outside of the outer casing 100X through the gap between the cover 400 and the outer casing member 101. In other words, the cover 400 and the outer casing member 101 are heat-sealed with the electrode terminal 300 sandwiched between them. Note that in the energy storage device 10X, the position where the electrode terminal 300 protrudes to the outside does not necessarily have to be between the cover 400 and the outer casing member 101. For example, the electrode terminal 300 may protrude to the outside through a hole formed on any of the six surfaces of the outer casing 100X. In this case, the small gap between the outer casing 100X and the electrode terminal 300 is filled, for example, with resin.

[0070] Furthermore, in the energy storage device 10X, the cover 400 and the electrode terminals 300 are provided as separate components. However, the cover 400 and the electrode terminals 300 do not necessarily have to be provided as separate components. For example, the cover 400 and the electrode terminals 300 may be formed integrally.

[0071] Figure 12 shows a first example in which the lid 400 and the electrode terminals 300 are integrally formed. As shown in Figure 12, in the first example, the electrode terminals 300 are preheat-sealed to the side surface of the lid 400. If, for example, the lid 400 is made of an exterior member 101, an adhesive film that adheres to both metal and resin may be placed between the lid 400 and the electrode terminals 300.

[0072] Figure 13 shows a second example in which the lid 400 and the electrode terminal 300 are integrally formed. As shown in Figure 13, in the second example, the electrode terminal 300 passes through a hole formed in the bottom surface of the lid 400. The small gap in the hole in the bottom surface of the lid 400 is filled with, for example, resin.

[0073] Furthermore, in the energy storage device 10X, a gas valve may be installed in a hole formed in the second sealing portion 120X or in one of the six surfaces of the outer casing 100X. The gas valve is composed of, for example, a check valve or a break valve and is configured to reduce the pressure inside the outer casing 100X when the pressure inside the outer casing 100X rises due to gas generated inside the energy storage device 10X.

[0074] <2-2. Method for manufacturing energy storage devices> Figure 14 is a flowchart showing the manufacturing procedure for the energy storage device 10X. The steps shown in Figure 14 are performed, for example, by a manufacturing apparatus for the energy storage device 10X.

[0075] The manufacturing apparatus wraps the outer casing member 101 around the electrode body 200 (step S200). The manufacturing apparatus forms the first sealing portion 110 by heat sealing the opposing surfaces (heat-fusible resin layers) of the outer casing member 101 together (step S210). This produces the unfinished product shown in Figures 4 and 5.

[0076] The manufacturing apparatus bends the first sealing portion 110 so that it contacts the second surface 140 (step S220). The manufacturing apparatus places the electrode body 200 into the unfinished product created in step S220 and attaches the lids 400 to each of the openings at both ends (step S230). The manufacturing apparatus forms the second sealing portion 120X by heat sealing the exterior member 101 and the lids 400 (step S240). This completes the energy storage device 10X.

[0077] <2-3. Features> In the energy storage device 10X according to this second embodiment, the first sealing portion 110 is bent towards the second surface 140, which has a smaller area. Therefore, with the energy storage device 10X, when multiple energy storage devices 10X are stacked, unevenness in the pressure distribution applied to the lower energy storage device 10X can be suppressed.

[0078] <2-4. Other Features> In the energy storage device 10X according to this second embodiment, the first sealing portion 110 does not necessarily have to be folded toward the smaller area of ​​the second surface 140. For example, the first sealing portion 110 may be folded toward the larger area of ​​the first surface 130. Also, the base portion of the first sealing portion 110 does not necessarily have to be on the edge 135 of the outer casing 100X. The base portion of the first sealing portion 110 may be located on a surface other than the lid 400 of the outer casing 100X, for example. Even in this case, the energy storage device 10X according to this second embodiment includes, for example, the following features.

[0079] The energy storage device 10X comprises an electrode body (electrode body 200) and an outer casing (outer casing 100X) that seals the electrode body (electrode body 200). The outer casing (outer casing 100X) is wrapped around the electrode body (electrode body 200) and includes an outer casing member (outer casing member 101) with openings formed at both ends, and a lid (lid 400) that seals the openings.

[0080] In the energy storage device 10X, the second sealing portion 120X is not formed by heat sealing the opposing surfaces of the outer casing member 101 as in Embodiment 1 (see Figure 7). In the energy storage device 10X, the opening of the outer casing member 101 wrapped around the electrode body 200 is sealed by the cover 400. That is, the second sealing portion 120X is formed in the portion where the cover 400 and the outer casing member 101 overlap (see Figures 9 and 10). With this configuration, the area of ​​the second sealing portion 120X can be easily narrowed by adjusting the depth L3 of the cover 400 (Figure 11).

[0081] Furthermore, in the energy storage device 10X, at the position where the corner C1 of the electrode body 200 (Figures 9 and 10) is covered by the outer casing member 101, excessive load is not generated due to the corner C1 piercing the outer casing member 101. As described above, in the energy storage device 10X, the second sealing portion 120X is not formed by heat sealing the opposing surfaces of the outer casing member 101 as in Embodiment 1.

[0082] Furthermore, the manufacturing procedure for the energy storage device 10X is not limited to the procedure shown in the flowchart of Figure 14. For example, the energy storage device 10X may be manufactured using the procedure shown in the flowchart of Figure 15.

[0083] Figure 15 is a flowchart showing another manufacturing procedure for the energy storage device 10X according to Embodiment 2. The steps shown in Figure 15 are performed, for example, by a manufacturing apparatus for the energy storage device 10X. The manufacturing apparatus attaches a component in which the electrode terminals 300 and the cover 400 are integrated (for example, the component shown in Figures 12 and 13) to the electrode body 200 (step S250). For example, the electrode terminals 300 are welded to the electrode body 200. Then, the manufacturing apparatus wraps the outer casing member 101 around the electrode body 200 (step S260). The manufacturing apparatus forms a first sealing portion 110 by heat sealing the opposing surfaces (heat-fusible resin layers) of the outer casing member 101 together, and forms a second sealing portion 120X by heat sealing the outer casing member 101 and the cover 400 (step S270). This completes the energy storage device 10X. The energy storage device 10X may be manufactured by such a procedure.

[0084] [3. Embodiment 3] In the battery manufacturing process, it is common to age a temporarily sealed energy storage device in a predetermined temperature environment for a predetermined time (hereinafter referred to as the aging process) for purposes such as impregnating the electrode body with electrolyte. During the aging process, gas is generated from the electrode body 200, and it is necessary to discharge this gas to the outside of the battery. In the energy storage device 10X according to Embodiment 2 described above, there was no mechanism to remove the gas generated in the aging process at the final stage of manufacturing the energy storage device 10X. In the energy storage device 10Y according to Embodiment 3, a mechanism is provided to remove the gas generated from the electrode body 200 at the final stage of manufacturing the energy storage device 10Y. In the following, we will mainly describe the parts that differ from Embodiment 2, and will omit the explanation of parts that are common to Embodiment 2.

[0085] <3-1. Configuration of Energy Storage Devices> Figure 16 is a side view showing the state in which the outer casing member 101Y is wrapped around the electrode body 200 during the manufacturing process of the energy storage device 10Y. Figure 17 is a bottom view showing the state in which the outer casing member 101Y is wrapped around the electrode body 200 and the cover 400 is attached to the outer casing member 101Y during the manufacturing process of the energy storage device 10Y.

[0086] As shown in Figures 16 and 17, the piece 150 is formed with the outer covering member 101Y wrapped around the electrode body 200. The piece 150 is formed by joining opposing surfaces of the outer covering member 101Y with the outer covering member 101Y wrapped around the electrode body 200. More specifically, the piece 150 is formed by joining (heat sealing) the periphery of opposing surfaces of the outer covering member 101Y with the outer covering member 101Y wrapped around the electrode body 200. That is, a first sealing portion 154 is formed on the periphery of the piece 150.

[0087] Furthermore, in one section 150, a space 152 is formed where opposing surfaces of the exterior member 101Y are not joined. Near the edge 135, joined regions 151 where opposing surfaces of the exterior member 101Y are joined and unjoined regions 153 where opposing surfaces of the exterior member 101Y are not joined are arranged alternately. In other words, in one section 150, a pattern of joined regions 151 is formed along the edge 135.

[0088] The gas generated from the electrode body 200 is discharged to the outside of the outer casing 100Y by releasing the seal on the outer casing 100Y, for example, by cutting off a portion of the piece 150. Note that the gas discharged to the outside of the outer casing 100Y is not necessarily limited to the gas generated from the electrode body 200; it may also be air, water vapor, hydrogen sulfide, or other gases not generated from the electrode body 200.

[0089] Subsequently, the outer casing 100Y is sealed again by heat-sealing the area including the vicinity of edge 135 in a strip shape. This completes the energy storage device 10Y. In the completed energy storage device 10Y, areas with strong bonding forces between opposing surfaces of the outer casing member 101Y and areas with weak bonding forces are alternately arranged along edge 135. In other words, in the heat-sealed area near edge 135, thin and thick sections are alternately arranged along edge 135. This is because, when the area near edge 135 is heat-sealed again, the unjoined area 153 is single-sealed, while the joined area 151 is double-sealed.

[0090] <3-2. Method for manufacturing energy storage devices> Figure 18 is a flowchart showing the manufacturing procedure for the energy storage device 10Y. The steps shown in Figure 18 are performed, for example, by a manufacturing apparatus for the energy storage device 10Y.

[0091] The manufacturing apparatus wraps the outer casing member 101Y around the electrode body 200 (step S300). The manufacturing apparatus forms the first sealing portion 154 by heat sealing the periphery of the outer casing member 101Y's opposing surfaces (heat-fusible resin layer) (step S310). The manufacturing apparatus forms the pattern of the joining region 151 by heat sealing the opposing surfaces of the outer casing member 101Y near the edge 135 (step S320).

[0092] In step S320, the manufacturing apparatus attaches the lids 400 to each of the openings at both ends of the unfinished product with the electrode body 200 housed inside (step S330). The manufacturing apparatus then forms the second sealing portion 120X by heat sealing the outer casing member 101Y and the lid 400 (step S340). After that, it undergoes an aging process.

[0093] The manufacturing apparatus degassed the gas generated during the aging process by cutting off the piece 150 (step S350). The manufacturing apparatus resealed the outer casing 100Y by heat-sealing the portion of the piece 150 including the joining region 151 in a strip shape and removing the edges (step S360). After that, the piece 150 was bent towards the second surface 140 to complete the energy storage device 10Y.

[0094] <3-3. Features> In the energy storage device 10Y according to this third embodiment, the piece 150 including the first sealing portion 154 is folded towards the second surface 140, which has a smaller area. Therefore, with the energy storage device 10Y, when multiple energy storage devices 10Y are stacked, unevenness in the pressure distribution applied to the lower energy storage device 10Y can be suppressed. When used in all-solid-state batteries, it is necessary to apply high pressure uniformly from the outside of the battery in order to achieve battery performance, so the packaging form of the present invention is preferred.

[0095] [4. Embodiment 4] In the energy storage device 10X according to Embodiment 2 described above, the position where the electrode terminal 300 protrudes to the outside was between the cover 400 and the exterior member 101. However, the position where the electrode terminal 300 protrudes to the outside is not limited to this. In the following, we will mainly describe the parts that differ from Embodiment 2, and will omit the explanation of parts that are common to Embodiment 2.

[0096] <4-1. Configuration of Energy Storage Devices> Figure 19 is a schematic plan view showing an energy storage device 10XA according to this embodiment 4. Figure 20 is a schematic side view showing an energy storage device 10XA. The outer casing 100X of the energy storage device 10XA includes a pair of long sides 100XA and a pair of short sides 100XB in a plan view. The outer casing 100X is constructed by fitting a cover 400 into each of the openings along the long sides 100XA of the outer casing member 101 wrapped around the electrode body 200. With the cover 400 fitted, a second sealing portion 120X is formed by heat sealing the outer casing member 101 and the cover 400. Through holes (not shown) are formed in the cover 400. The two electrode terminals 300 protrude from the through holes in the cover 400 to the outside of the outer casing 100X. The two electrode terminals 300 are shaped to follow the long side 100XA of the outer casing 100X. The small gap between the through hole and the electrode terminal 300 is filled with, for example, resin. In this embodiment 4, the first sealing portion 110 is formed on one of the pair of short sides 100XB.

[0097] In the thickness direction (arrow UD direction) of the energy storage device 10XA, the position where the electrode terminals 300 protrude from the cover 400 can be arbitrarily selected. In this embodiment 4, as shown in Figure 20, the electrode terminals 300 protrude from approximately the center of the cover 400 to the outside of the outer casing 100X in the thickness direction of the energy storage device 10XA. The length of the electrode terminals 300 in the depth direction (arrow FB direction) of the energy storage device 10XA can be arbitrarily selected. In this embodiment 4, the length of the electrode terminals 300 in the depth direction (arrow FB direction) of the energy storage device 10XA is substantially the same as the length of the electrode body 200.

[0098] <4-2. Features> In the energy storage device 10XA according to this embodiment 4, the electrode terminals 300 are arranged along the longer side 100XA, which has a longer depth, so that larger electrode terminals 300 can be used. Therefore, a high-output energy storage device 10XA can be provided.

[0099] [5. Variant] Although Embodiments 1-4 have been described above, the present invention is not limited to Embodiments 1-4, and various modifications are possible without departing from the spirit of the invention. Modifications will be described below.

[0100] <5-1> In the above embodiments 1-4, one outer covering member was wrapped around the electrode body 200. However, the outer covering member wrapped around the electrode body 200 does not necessarily have to be just one. For example, two or more outer covering members may be wrapped around the electrode body 200.

[0101] Figure 21 is a side view showing the state in which the outer covering members 101Z1 and 101Z2 are wrapped around the electrode body 200 during the manufacturing process of a modified energy storage device. As shown in Figure 21, the electrode body 200 is surrounded by the outer covering members 101Z1 and 101Z2. The first sealing portion 110Z is formed by joining the opposing surfaces of the outer covering members 101Z1 and 101Z2. In this example, each first sealing portion 110Z is bent towards the second surface 140Z side, rather than towards the first surface 130Z side. Even with this configuration, it is possible to suppress uneven pressure distribution on the lower energy storage devices when multiple energy storage devices are stacked. When used in all-solid-state batteries, it is necessary to apply high pressure uniformly from the outside of the battery in order to achieve battery performance, so the packaging form of the present invention is preferred. In this example, each first sealing portion 110Z does not necessarily need to be bent. Furthermore, in this modified example, each sealing portion 110Z may be sealed while sandwiching a part of the electrode terminal 300. Moreover, in this modified example, each first sealing portion 110Z does not need to be formed on the edge 135Z, but may protrude outward from approximately the center of the second surface 140Z in the thickness direction of the energy storage device.

[0102] <5-2> Furthermore, in the above embodiments 1-4, the electrode body 200 was a so-called stack type, constructed by stacking a plurality of electrodes 210, but the form of the electrode body 200 is not limited to this. The electrode body 200 may be a so-called wound type, constructed, for example, by winding a positive electrode and a negative electrode via a separator. Alternatively, the electrode body 200 may be constructed by stacking a plurality of so-called wound type electrode bodies.

[0103] <5-3> Furthermore, in the above embodiments 1-4, the second surface 140 was a plane extending downward from the first surface 130 at approximately a right angle. However, the form of the second surface 140 is not limited to this. For example, consider the case where the electrode body 200 is a wound electrode body and a plane and a curved surface are formed on its outer circumference. Here, suppose the area of ​​the plane is larger than the area of ​​the curved surface, and the first surface 130 covers the plane of the electrode body, and the second surface 140 covers the curved surface of the electrode body. In this case, the second surface 140 may be composed of a curved surface. In this case, the boundary portion where the second surface 140 extends downward from the first surface 130 becomes the edge 135.

[0104] <5-4> Furthermore, in the above embodiment 3, four joining regions 151 were formed. However, the number of locations where joining regions 151 are formed is not limited to this. For example, the joining regions 151 may be formed at two locations near both ends along the edge 135, or at one location near the center of the edge 135, or they may be formed at five or more locations.

[0105] <5-5> Furthermore, in the above embodiment 1, the electrode terminal 300 is arranged in the second sealing portion 120, but the position in the outer casing 100 where the electrode terminal 300 is arranged is not limited to this. For example, as shown in Figure 22, the electrode terminal 300 can also be arranged in the first sealing portion 110. In other words, the first sealing portion 110 is sealed with the electrode terminal 300 sandwiched between them. In this modified example, at least one of the two electrode terminals 300 may be bent toward the second surface 140, or be bent toward the opposite side of the second surface 140, or may not be bent so as to protrude outward from the edge 135. In this modified example, the electrode terminal 300 and the first sealing portion 110 can be easily sealed, thereby improving the airtightness of the outer casing 100. Also, the electrode body 200 can be easily housed in the outer casing 100. In this modified example, for example, as in the above embodiment 2, a cover 400 is fitted into each of the openings at both ends of the outer casing member 101. With the lid 400 fitted in place, the second sealing portion 120 is formed by heat sealing the exterior member 101 and the lid 400.

[0106] <5-6> Furthermore, in the above embodiment 2, the configuration of the cover 400 can be arbitrarily changed. Figure 23 is a perspective view showing a modified cover 500 of the cover 400. The cover 500 is, for example, plate-shaped and includes a first surface 500A facing the electrode body 200 (see Figure 9), and a second surface 500B opposite to the first surface 500A. A hole 500C is formed in the center of the cover 500, penetrating the first surface 500A and the second surface 500B. The material constituting the cover 500 is, for example, resin. In this modified example, it is preferable that an adhesive film 530 is attached to a predetermined range of the electrode terminal 300, including the portion of the electrode terminal 300 that is joined to the cover 500, and to adhere to both the electrode terminal 300 and the cover 500. The lid 500 may be made up of a member divided into a first part 510 and a second part 520, and manufactured by joining the first part 510 and the second part 520 so as to sandwich the electrode terminal 300 and the adhesive film 530. Alternatively, the lid 500 may be manufactured by insert molding the lid 500 onto the electrode terminal 300 with the adhesive film 530 attached. In this modified version, it is preferable that a barrier layer is laminated on at least a part of the surface of the lid 500. Or, if the lid 500 has multiple layers, a barrier layer may be formed on any of the layers. The material constituting the barrier layer is, for example, aluminum. In this modified version, if a gap occurs between the adhesive film 530 and the hole 530C, it is preferable that this gap be filled with a resin material such as hot melt.

[0107] Furthermore, in this modified example, as shown in Figure 24, the exterior body 100X forms a second sealing portion 120X by joining the exterior member 101 and the second surface 500B of the lid 500 while the lid 500 is fitted into place. The means for joining the exterior member 101 and the second surface 500B of the lid 500 is, for example, heat sealing. In this modified example, the exterior member 101 is joined to a wider area of ​​the lid 500, thereby improving the airtightness of the exterior body 100X.

[0108] Figure 25 is a front view of a cover 600, another modified example of the cover 400 in the second embodiment described above. The cover 600 includes a metal portion 610, which is a part where metal is exposed on the surface, and the metal portion 610 and the electrode 210 of the electrode body 200 are welded together. The cover 600 may consist entirely of the metal portion 610, or the metal portion 610 may be partially formed. When the metal portion 610 is partially formed, the cover 600 is made of a multilayer material including a metal layer. When the cover 600 is made of a multilayer material with a metal layer as an intermediate layer, the metal portion 610 is a part in which layers other than the metal layer have been partially removed so that the metal layer is exposed. In the example shown in Figure 25, the metal portion 610 of the cover 600 functions as an electrode terminal, so no space is required between the cover 600 and the electrode 210. Therefore, the energy storage device 10X (see Figure 9) can be made smaller.

[0109] Figure 26 is a front view of a cover 700, another modified example of the cover 400 in the second embodiment described above. The cover 700 includes a metal part 710 made of a metal material, and a non-metal part 720 made of a resin material that is connected to the metal part 710. The metal part 710 is welded to the electrode 210 of the electrode body 200. In the example shown in Figure 26, the metal part 710 of the cover 700 functions as an electrode terminal, so no space is required between the cover 700 and the electrode 210. This allows the energy storage device 10X (see Figure 9) to be made smaller.

[0110] <5-7> Furthermore, in the above embodiment 1, the second sealing portion 120 was formed by folding the exterior member 101 and heat-sealing the heat-fusible resin layers of the exterior member 101. However, the method of forming the second sealing portion 120 is not limited to this. Figure 27 is a schematic plan view showing a modified energy storage device 10 having a second sealing portion 120Y. The exterior member 101 has an overhang portion 101X that extends outward from the exterior body 100, and the second sealing portion 120Y is formed by heat-sealing the heat-fusible resin layers of the overhang portion 101X. In the portion of the overhang portion 101X where the electrode terminals 300 are arranged, the heat-fusible resin layer of the overhang portion 101X and the electrode terminals 300 are heat-sealed. According to this modified example, the second sealing portion 120Y can be heat-sealed more firmly, thereby improving the airtightness of the exterior body 100. In this modified example, the portion of the protruding part 101X other than the part heat-sealed to the electrode terminal 300 may be cut off as needed. This modified example can also be applied to the modified example shown in Figure 22. [Explanation of symbols]

[0111] 10,10X,10XA,10Y,10Z Energy storage device, 100,100X,100Y Outer casing, 101,101Y,101Z1,101Z2 Outer casing member, 101X Protruding part, 110,110Z,154 First sealing part, 120,120X,120Y Second sealing part, 130,130Z First surface, 135,135Z Side, 140,140Z Second surface, 150 Piece part, 151 Joining area, 152 Space, 153 Unjoined area, 200 Electrode body, 210 Electrode, 215 Current collector, 300 Electrode terminal, 500A First surface, 500B Second surface, 400,500,700 Cover, 610,710 Metal part, C1 corner.

Claims

1. An electrode body and The electrode terminals connected to the electrode body, The electrode body is enclosed by an outer casing, The exterior body is, A film-like outer covering member enclosing the electrode body, A lid that seals the electrode body together with the exterior member, The exterior member includes a first sealing portion which is sealed by joining the surfaces of the exterior member that are facing each other while wrapped around the electrode body, The base portion of the first sealing part is formed at the boundary between the first surface and the second surface of the outer casing. The area of ​​the first surface is larger than the area of ​​the second surface. The first sealing portion does not overlap with the first surface in a plan view. The electrode terminals protrude to the outside of the outer casing through the gap between the cover and the outer casing member. Energy storage device.

2. The lid includes a barrier layer. The energy storage device according to claim 1.

3. The device further comprises an adhesive film that adheres to the electrode terminals and the cover, The adhesive film is attached to at least the portion of the electrode terminal that is joined to the cover, The electrode terminal and the cover are joined together via the adhesive film. The energy storage device according to claim 1 or 2.

4. The first sealing portion is bent so as to be in contact with the second surface. The energy storage device according to claim 1 or 2.

5. The first sealing portion, when folded to be in contact with the second surface, covers substantially the entire second surface. The energy storage device according to claim 4.

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