Energy storage device and method for manufacturing an energy storage device

Abstract

To provide a power storage device which enables suppression of occurrence of unevenness in distribution of a pressure put on a power storage device located at a lower position when a plurality of power storage devices are stacked on each other and which has corrosion resistance, and a manufacturing method thereof.SOLUTION: A power storage device comprises an electrode body and an outer packaging body. The outer packaging body serves to seal in the electrode body. The outer packaging body is formed by a film-like exterior packaging member. The outer packaging body includes a first seal part where the electrode body is sealed in; the first seal part is formed by bonding together faces of the film-like exterior packaging member, which are opposed to each other in the state of being wound around the electrode body. A first face is larger than a second face in area. The first seal part does not overlap with the first face in plan view. The exterior packaging member is composed of a laminate having at least a base material layer, a barrier layer and a heat-fusable resin layer in this order. The barrier layer includes a piece of aluminum alloy foil which satisfies the following composition requirement: Fe is 0.2 mass% or more and 2.0 mass% or less, and Mg is 0.1 mass% or more and 5.0 mass% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to an energy storage device and a method for manufacturing an energy storage device. [Background technology]

[0002] Japanese Patent No. 4509242 (Patent Document 1) discloses a secondary battery. In this secondary battery, an electrode body is sealed inside a bag made of an outer material (laminate film) (see Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 4509242 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In the secondary battery disclosed in Patent Document 1, the sealing portion of the outer casing is provided on a large surface area. The sealing portion is thicker than other areas because it is a region where the outer casing overlaps. When other secondary batteries are stacked on the surface where the sealing portion is provided, the upper secondary battery may tilt with the sealing portion as a pivot point. As a result, the unevenness of the pressure distribution on the lower secondary battery increases.

[0005] Furthermore, if microscopic cracks or pinholes occur in the innermost heat-sealable resin layer at the bent portion of the energy storage device's exterior, and if the external terminal and the aluminum alloy foil of the energy storage device's exterior are in close proximity or in contact and short-circuit, current can flow between the aluminum alloy foil of the energy storage device's exterior and the external terminal via the electrolyte and electrolyte in contact with the heat-sealable resin layer, potentially causing alloy corrosion of the aluminum alloy foil with lithium ions in the electrolyte. In particular, if the aluminum alloy foil and the negative electrode terminal short-circuit via the electrolyte, the aluminum alloy foil is prone to corrosion. Corrosion of the aluminum alloy foil can lead to problems such as expansion of the aluminum alloy foil, resulting in a deterioration of the energy storage device's performance.

[0006] The present invention has been made to solve these problems, and its objective is to provide an energy storage device and a method for manufacturing the energy storage device that can suppress uneven pressure distribution between adjacent energy storage devices when multiple energy storage devices are stacked, and that is corrosion-resistant. [Means for solving the problem]

[0007] 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, a first surface, and a second surface, which are sealed by joining surfaces facing each other when the outer casing member is wrapped around the electrode body. 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. The outer casing member is composed of a laminate comprising at least a base layer, a barrier layer, and a heat-fusible resin layer in that order. The barrier layer contains aluminum alloy foil satisfying a composition of Fe: 0.2% to 2.0% by mass and Mg: 0.1% to 5.0% by mass.

[0008] 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, because the aluminum alloy foil of the exterior material has the above configuration, the aluminum alloy foil is less susceptible to corrosion.

[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.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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 between the first surface and the second surface.

[0015] In the above-described energy storage device, in the first sealing portion, regions with a small thickness and regions with a large thickness may be arranged along the boundary between the first surface and the second surface.

[0016] The above-described energy storage device may further include an electrode terminal electrically connected to the electrode body, and the first sealing portion may be sealed with the electrode terminal sandwiched therebetween.

[0017] The above-described energy storage device may further include an electrode terminal electrically connected to the electrode body and a lid body to which the electrode terminal is attached, and the exterior body may further include a second sealing portion sealed in a state of being joined to the lid body.

[0018] In the above-described energy storage device, the lid body includes a first surface facing the electrode body and a second surface on the opposite side of the first surface, and the second sealing portion may include a portion where the exterior body and the second surface are joined.

[0019] The above-described energy storage device further includes a lid body, the exterior body further includes a second sealing portion sealed in a state of being joined to the lid body, the lid body includes a metal portion that is a portion where a metal layer is exposed on the surface or a portion made of a metal material, and the metal portion and the electrode body may be welded.

[0020] The above-described energy storage device may further include an electrode terminal electrically connected to the electrode body, and the exterior body may further include a protruding portion protruding outward and a second sealing portion sealed with the electrode terminal sandwiched by the protruding portion.

[0021] In the above-described energy storage device, the direction along the boundary between the first surface and the second surface may be a direction perpendicular to the flow direction of the exterior member.

[0022] In this energy storage device, when the first sealing portion is bent along the boundary between the first and second surfaces, the direction along the boundary between the first and second surfaces 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.

[0023] 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.

[0024] A power storage device according to another 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 an outer casing member that is film-like. The outer casing includes a piece where the peripheral edges of opposing surfaces are joined together when wrapped around the electrode body. Within the piece, a space is formed where the opposing surfaces are not joined together. In the piece, near the boundary between the surfaces, there are regions where the opposing surfaces are joined and regions where the opposing surfaces are not joined. The outer casing member is composed of a laminate comprising at least a base layer, a barrier layer, and a heat-fusible resin layer in this order. The barrier layer contains aluminum alloy foil with a composition of Fe: 0.2% to 2.0% by mass and Mg: 0.1% to 5.0% by mass.

[0025] Gas can be generated inside the outer casing. In this energy storage device, a space is formed within one section, and near the boundary between surfaces, there are regions where the opposing surfaces are joined and regions where the opposing surfaces are not joined. Therefore, with this energy storage device, by releasing the sealing state of the outer casing at one section, the gas inside the outer casing can be discharged through that section. Then, by sealing the outer casing again, an energy storage device after degassing can be manufactured. In addition, because the aluminum alloy foil of the outer material has the above configuration, the aluminum alloy foil is less susceptible to corrosion.

[0026] In the above-described energy storage device, the composition of the aluminum alloy foil may satisfy the condition Si: 0.5% by mass or less.

[0027] In the above-described energy storage device, the composition of the aluminum alloy foil satisfies Mg: 0.1% by mass or more and 1.5% by mass or less, and at least one surface of the aluminum alloy foil contains 5.0 atomic percent or more of Mg, and at least one surface of the aluminum alloy foil may have an oxide film with a thickness of 80 Å or more.

[0028] In the above-described energy storage device, the composition of the aluminum alloy foil satisfies the requirement of Mg: 0.1% by mass or more and 1.5% by mass or less, and the aluminum alloy foil may have a tensile strength of 110 MPa or more and an elongation at break of 10% or more.

[0029] In the above-described energy storage device, the composition of the aluminum alloy foil satisfies the condition that Mg: greater than 1.5% by mass and 5.0% by mass or less, and that at least one surface of the aluminum alloy foil contains 15.0 atomic percent or more of Mg, and that at least one surface of the aluminum alloy foil has an oxide film with a thickness of 120 Å or more.

[0030] In the above-described energy storage device, the composition of the aluminum alloy foil satisfies the condition that Mg: greater than 1.5% by mass and 5.0% by mass or less, and the aluminum alloy foil may have a tensile strength of 180 MPa or more and an elongation at break of 15% or more.

[0031] In the above-described energy storage device, the aluminum alloy foil may have a texture density of 15 or less in both the Copper orientation and the R orientation.

[0032] In the above-described energy storage device, the aluminum alloy foil may have an average crystal grain size of 25 μm or less.

[0033] In the above energy storage device, the aluminum alloy foil contains Al and unavoidable impurities as the remainder, and the ratio of the length of the large-angle grain boundary L1 to the length of the small-angle grain boundary L2 per unit area, as measured by backscattered electron diffraction, may satisfy the relationship L1 / L2 > 3.0.

[0034] In the above-described energy storage device, the aluminum alloy foil may contain Mn: 0.1% by mass or less as an unavoidable impurity.

[0035] A method for manufacturing an energy storage device according to another aspect of the present invention is a method for manufacturing an energy storage device from an unfinished product. The unfinished product 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 piece where the peripheral edges of opposing surfaces are joined together when the outer casing member is wrapped around the electrode body. Within the piece, a space is formed where the opposing surfaces are not joined together. In the piece, near the boundary between the surfaces, there is a region where the opposing surfaces are joined together and a region where the opposing surfaces are not joined together. The outer casing member is composed of a laminate comprising at least a base layer, a barrier layer, and a heat-fusible resin layer in this order. The barrier layer contains aluminum alloy foil with a composition of Fe: 0.2% to 2.0% by mass and Mg: 0.1% to 5.0% by mass. The above manufacturing method includes the steps of releasing the sealing state of the outer casing in one part and discharging the gas to the outside of the outer casing, and resealing the outer casing by joining the opposing surfaces in at least one part of the one part.

[0036] According to this method for manufacturing energy storage devices, the energy storage device can be manufactured after degassing by venting the gas through one end and then resealing the outer casing. [Effects of the Invention]

[0037] According to the present invention, it is possible to provide an energy storage device and a method for manufacturing the energy storage device that can suppress uneven pressure distribution on lower energy storage devices when multiple energy storage devices are stacked, and that is corrosion-resistant. [Brief explanation of the drawing]

[0038] [Figure 1] This is a schematic perspective view showing an energy storage device according to Embodiment 1. [Figure 2] This is a schematic plan view illustrating an energy storage device. [Figure 3A] This is a schematic side view illustrating an energy storage device. [Figure 3B] A cross-sectional view showing an example of the layer structure of exterior components. [Figure 3C] A cross-sectional view showing an example of the layer structure of exterior components. [Figure 3D] A cross-sectional view showing an example of the layer structure of exterior components. [Figure 3E] A cross-sectional view showing an example of the layer structure of exterior components. [Figure 3F(A)] This is a micrograph showing the surface of an aluminum alloy foil used for evaluating corrosion resistance, specifically a micrograph showing a surface without corrosion. [Figure 3F(B)] This is a micrograph showing the surface of an aluminum alloy foil used for evaluating corrosion resistance, specifically a micrograph showing a corroded surface. [Figure 4] This diagram shows a side view of the electrode body with the outer casing wrapped around it during the manufacturing process of an energy storage device according to Embodiment 1. [Figure 5] This diagram shows, from below, the state in which the outer casing material is wrapped around the electrode body during the manufacturing process of the energy storage device according to Embodiment 1. [Figure 6] This figure schematically shows a portion of the VI-VI section in Figure 2. [Figure 7] This is a diagram illustrating the method for forming the second sealing portion. [Figure 8] This is a flowchart showing the manufacturing procedure for an energy storage device according to Embodiment 1. [Figure 9] This is a schematic plan view showing an energy storage device according to Embodiment 2. [Figure 10] This is a schematic side view illustrating an energy storage device. [Figure 11] This is a schematic perspective view of the lid. [Figure 12] This figure shows a first example in which the lid and electrode terminals 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]

[0039] Embodiments of the present invention will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated. In this specification, the numerical range indicated by "~" means "greater than or equal to" and "less than or equal to". For example, the notation 2~15mm means 2mm or more and 15mm or less.

[0040] [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 3A is a schematic side view showing the energy storage device 10. Figures 3B to 3E are cross-sectional views showing the layer structure of the exterior member 101 of the energy storage device 10. In Figures 2 and 3A, the direction of arrow UD indicates the thickness direction of the energy storage device 10, and the direction of arrow LR indicates the width direction of the energy storage device 10. The direction of arrow FB indicates the depth direction of the energy storage device 10. The directions indicated by arrows UDLRFB are common to all subsequent figures.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] The exterior member 101 is composed of a laminate comprising, for example, a base layer 101A, a barrier layer 101C, and a heat-fusible resin layer 101D in that order, as shown in Figures 3B to 3E. In the exterior member 101, the base layer 101A is the outermost layer, and the heat-fusible resin layer 101D is the innermost layer. When assembling the energy storage device using the exterior member 101 and the energy storage device element, the electrode body 200 is housed in a space formed by heat-fussing the peripheral edges of the heat-fusible resin layers 101D of the exterior member 101 with the layers facing each other.

[0047] The barrier layer 101C contains aluminum alloy foil. That is, the barrier layer 101C can be composed of aluminum alloy foil. The exterior member 101 of this embodiment, which uses aluminum alloy foil that satisfies predetermined composition and properties described later, exhibits excellent conformability of the exterior member at corners and other areas, effectively suppresses corrosion of the aluminum alloy foil, and further exhibits excellent mechanical strength.

[0048] The exterior member 101 may, for example, have an adhesive layer 101B between the base layer 101A and the barrier layer 101C, as needed, for the purpose of improving the adhesion between these layers, as shown in Figures 3B to 3E. Also, as shown in Figures 3D and 3E, for example, an adhesive layer 101E may be provided between the barrier layer 101C and the heat-fusible resin layer 101D, as needed, for the purpose of improving the adhesion between these layers. Furthermore, as shown in Figure 3E, a surface coating layer 101F or the like may be provided on the outside of the base layer 101A (opposite the heat-fusible resin layer 101D side), as needed.

[0049] The thickness of the laminate constituting the exterior member 101 is not particularly limited, but from the viewpoint of cost reduction and energy density improvement, for example, it can be 190 μm or less, preferably about 180 μm or less, about 155 μm or less, or about 120 μm or less. Furthermore, from the viewpoint of maintaining the function of the exterior member 101 in protecting the electrode body 200, the thickness of the laminate constituting the exterior member 101 can be preferably about 35 μm or more, about 45 μm or more, or about 60 μm or more. Furthermore, preferred ranges for the laminate constituting the exterior member 101 include, for example, approximately 35-190 μm, 35-180 μm, 35-155 μm, 35-120 μm, 45-190 μm, 45-180 μm, 45-155 μm, 45-120 μm, 60-190 μm, 60-180 μm, 60-155 μm, and 60-120 μm, with approximately 60-155 μm being particularly preferred.

[0050] In the exterior member 101, the ratio of the total thickness of the base layer 101A, the adhesive layer 101B (optionally provided), the barrier layer 101C, the adhesive layer 101E (optionally provided), the heat-fusible resin layer 101D, and the surface coating layer 101F (optionally provided) to the thickness (total thickness) of the laminate constituting the exterior member 101 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. For example, if the exterior member 101 includes a base layer 101A, an adhesive layer 101B, a barrier layer 101C, an adhesive layer 101E, and a heat-fusible resin layer 101D, the ratio of the total thickness of each of these layers to the thickness (total thickness) of the laminate constituting the exterior member 101 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0051] In the case of the exterior component 101, the Machine Direction (MD) and Transverse Direction (TD) of the barrier layer 101C, described later, can usually be determined during its manufacturing process. When the barrier layer 101C is made of aluminum alloy foil, linear lines called rolling marks are formed on the surface of the metal foil in the rolling direction (RD) of the metal foil. Since the rolling marks extend along the rolling direction, the rolling direction of the metal foil can be determined by observing the surface of the metal foil. In addition, during the manufacturing process of the laminate, the MD of the laminate and the RD of the metal foil usually coincide, so the MD of the laminate can be determined by observing the surface of the metal foil in the laminate and identifying the rolling direction (RD) of the metal foil. Furthermore, since the TD of the laminate is perpendicular to the MD of the laminate, the TD of the laminate can also be determined.

[0052] Furthermore, if the MD of the exterior member 101 cannot be identified due to the rolling marks of the aluminum alloy foil, it can be identified by the following method. One method for confirming the MD of the exterior member 101 is to observe the cross-section of the heat-fusible resin layer of the exterior member 101 with an electron microscope and confirm the sea-island structure. In this method, the direction parallel to the cross-section where the average diameter of the island shapes perpendicular to the thickness direction of the heat-fusible resin layer is maximum can be determined as the MD. Specifically, the sea-island structure is confirmed by observing each of the cross-sections (a total of 10 cross-sections) in the longitudinal direction of the heat-fusible resin layer, and each of the cross-sections perpendicular to the longitudinal direction, by changing the angle by 10 degrees from the direction parallel to the longitudinal cross-section. Next, the shape of each individual island is observed in each cross-section. For each island shape, the straight-line distance connecting the leftmost point perpendicular to the thickness direction of the heat-fusible resin layer and the rightmost point perpendicular to that point is defined as the diameter y. In each cross-section, the average of the top 20 diameters y of the island shapes, in descending order of diameter y, is calculated. The direction parallel to the cross-section where the average of the relevant diameter y of the island's shape was largest is determined to be the MD (Movement Direction).

[0053] <1-1-1. Base material layer> The base layer 101A is a layer provided for purposes such as enabling the exterior member 101 to function as a base material. The base layer 101A is located on the outer layer side of the exterior member 101.

[0054] The material forming the base layer 101A is not particularly limited, as long as it has the function of a base material, that is, at least insulating properties. The base layer 101A can be formed using, for example, a resin, and the resin may contain additives described later.

[0055] When the base layer 101A is formed of resin, the base layer 101A may be, for example, a resin film formed of resin, or a film formed by coating with resin. The resin film may be an unstretched film or a stretched film. Examples of stretched films include uniaxially stretched films and biaxially stretched films, with biaxially stretched films being preferred. Examples of stretching methods for forming a biaxially stretched film include sequential biaxial stretching, inflation stretching, and simultaneous biaxial stretching. Examples of resin coating methods include roll coating, gravure coating, and extrusion coating.

[0056] Examples of resins that form the base layer 101A include polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, phenolic resin, and modified versions of these resins. Furthermore, the resin forming the base layer 101A may be a copolymer of these resins, or a modified version of a copolymer. Moreover, it may be a mixture of these resins.

[0057] Among these, polyester and polyamide are preferred as resins for forming the base layer 101A.

[0058] Examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyesters. Examples of copolymerized polyesters include copolymerized polyesters with ethylene terephthalate as the main repeating unit. Specifically, examples include copolymerized polyesters polymerized with ethylene isophthalate using ethylene terephthalate as the main repeating unit (hereinafter abbreviated as polyethylene(terephthalate / isophthalate)), polyethylene(terephthalate / adipate), polyethylene(terephthalate / sodium sulfoisophthalate), polyethylene(terephthalate / sodium isophthalate), polyethylene(terephthalate / phenyl-dicarboxylate), and polyethylene(terephthalate / decanedicarboxylate). These polyesters may be used individually or in combination of two or more types.

[0059] Furthermore, examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (where I represents isophthalic acid and T represents terephthalic acid), which contain constituent units derived from terephthalic acid and / or isophthalic acid; aromatic polyamides such as polyamide MXD6 (polymetaxylylene adipamide); alicyclic polyamides such as polyamide PACM6 (polybis(4-aminocyclohexyl)methaneadipamide); polyamides copolymerized with lactam components or isocyanate components such as 4,4'-diphenylmethane-diisocyanate; polyesteramide copolymers and polyether esteramide copolymers, which are copolymers of copolymerized polyamides with polyester or polyalkylene ether glycol; and other polymers of these polyamides. These polyamides may be used individually or in combination of two or more types.

[0060] The base layer 101A preferably contains at least one of polyester film, polyamide film, and polyolefin film, preferably contains at least one of stretched polyester film, stretched polyamide film, and stretched polyolefin film, more preferably contains at least one of stretched polyethylene terephthalate film, stretched polybutylene terephthalate film, stretched nylon film, and stretched polypropylene film, and even more preferably contains at least one of biaxially oriented polyethylene terephthalate film, biaxially oriented polybutylene terephthalate film, biaxially oriented nylon film, and biaxially oriented polypropylene film.

[0061] The base layer 101A may be a single layer or may consist of two or more layers. If the base layer 101A consists of two or more layers, the base layer 101A may be a laminate formed by laminating resin films with an adhesive, or a laminate of resin films formed by co-extruding resin into two or more layers. Furthermore, the laminate of resin films formed by co-extruding resin into two or more layers may be used as the base layer 101A in its unstretched state, or it may be used as the base layer 101A after uniaxial stretching or biaxial stretching.

[0062] Specific examples of a laminate of two or more resin films in the base layer 101A include a laminate of polyester film and nylon film, a laminate of two or more nylon films, and a laminate of two or more polyester films. Preferably, a laminate of stretched nylon film and stretched polyester film, a laminate of two or more stretched nylon films, and a laminate of two or more stretched polyester films are preferred. For example, when the base layer 101A is a laminate of two resin films, a laminate of polyester resin film and polyester resin film, a laminate of polyamide resin film and polyamide resin film, or a laminate of polyester resin film and polyamide resin film is preferred, and a laminate of polyethylene terephthalate film and polyethylene terephthalate film, a laminate of nylon film and nylon film, or a laminate of polyethylene terephthalate film and nylon film is more preferred. Furthermore, since polyester resin is less likely to discolor when an electrolyte adheres to its surface, for example, when the base layer 101A is a laminate of two or more resin films, it is preferable that the polyester resin film is located in the outermost layer of the base layer 101A.

[0063] If the base layer 101A is a laminate of two or more resin films, the two or more resin films may be laminated with an adhesive in between. Preferred adhesives include those similar to those exemplified in the adhesive layer 101B described later. The method for laminating the two or more resin films is not particularly limited, and known methods can be used, such as dry lamination, sandwich lamination, extrusion lamination, and thermal lamination, with dry lamination being preferred. When lamination is performed by dry lamination, it is preferable to use a polyurethane adhesive. In this case, the thickness of the adhesive is, for example, about 2 to 5 μm. Alternatively, an anchor coat layer may be formed on the resin film before lamination. The anchor coat layer may be similar to the adhesive exemplified in the adhesive layer 101B described later. In this case, the thickness of the anchor coat layer is, for example, about 0.01 to 1.0 μm.

[0064] Furthermore, at least one of the surface and interior of the base layer 101A may contain additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents. Only one type of additive may be used, or two or more types may be mixed and used.

[0065] From the viewpoint of improving the conformability of the exterior member 101 at corners and other parts of the exterior member, it is preferable that a lubricant be present on the surface of the base layer 101A. The lubricant is not particularly limited, but amide lubricants are preferred. Specific examples of amide lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearate amide, N-stearyl oleic acid amide, N-oleyl stearate amide, and N-stearyl erucic acid amide. Specific examples of methylolamides include methylol stearate amide. Specific examples of saturated fatty acid bisamides include methylenebisstearate, ethylenebiscaprate, ethylenebislaurate, ethylenebisstearate, ethylenebishydroxystearate, ethylenebisbehenamide, hexamethylenebisstearate, hexamethylenebisbehenamide, hexamethylenehydroxystearate, N,N'-distearyladipamide, and N,N'-distearylsebacinamide. Specific examples of unsaturated fatty acid bisamides include ethylenebisoleamide, ethylenebiserucamide, hexamethylenebisoleamide, N,N'-dioleyladipamide, and N,N'-dioleylsebacinamide. Specific examples of fatty acid ester amides include stearamidoethylstearate. Specific examples of aromatic bisamides include m-xylylenebisstearate, m-xylylenebishydroxystearate, and N,N'-distearyl isophthalamide. The lubricant may be used alone or in combination of two or more types.

[0066] If a lubricant is present on the surface of the substrate layer 101A, the amount present is not particularly limited, but preferably about 3 mg / m². 2 More preferably 4-15 mg / m² 2 To a certain extent, more preferably 5-14 mg / m² 2 The degree can be described as follows.

[0067] The lubricant present on the surface of the base layer 101A may be a lubricant contained in the resin constituting the base layer 101A that has seeped out, or a lubricant may be applied to the surface of the base layer 101A.

[0068] The thickness of the base layer 101A is not particularly limited as long as it performs its function as a base material, but for example, it can be about 3 to 50 μm, preferably about 10 to 35 μm. If the base layer 101A is a laminate of two or more resin films, the thickness of each resin film constituting each layer can be preferably about 2 to 25 μm.

[0069] <1-1-2.Adhesive layer> In the exterior component 101, the adhesive layer 101B is a layer provided between the base material layer 101A and the barrier layer 101C as needed, with the aim of improving the adhesion between them.

[0070] The adhesive layer 101B is formed by an adhesive capable of bonding the substrate layer 101A and the barrier layer 101C. The adhesive used to form the adhesive layer 101B is not limited, but may be a chemical reaction type, solvent evaporation type, heat melt type, hot pressure type, etc. It may also be a two-component curing adhesive (two-part adhesive), a one-component curing adhesive (one-part adhesive), or a resin that does not undergo a curing reaction. Furthermore, the adhesive layer 101B may be a single layer or a multi-layer layer.

[0071] Specifically, adhesive components included in adhesives include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, copolymerized polyester; polyethers; polyurethanes; epoxy resins; phenolic resins; polyamides such as nylon 6, nylon 66, nylon 12, copolymerized polyamides; polyolefin resins such as polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins; polyvinyl acetate; cellulose; (meth)acrylic resins; polyimides; polycarbonates; amino resins such as urea resins and melamine resins; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; and silicone resins. These adhesive components may be used individually or in combination of two or more. Among these adhesive components, polyurethane adhesives are particularly preferred. Furthermore, the adhesive strength of these adhesive resins can be increased by using an appropriate curing agent. The curing agent is selected appropriately from polyisocyanates, polyfunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, etc., depending on the functional groups of the adhesive components.

[0072] Examples of polyurethane adhesives include polyurethane adhesives comprising a main component containing a polyol compound and a curing agent containing an isocyanate compound. Preferably, a two-component curing type polyurethane adhesive is used, in which a polyol such as polyester polyol, polyether polyol, and acrylic polyol is the main component and an aromatic or aliphatic polyisocyanate is the curing agent. Furthermore, as the polyol compound, it is preferable to use a polyester polyol that has hydroxyl groups not only at the ends of the repeating units but also in the side chains. Because the adhesive layer 101B is formed of polyurethane adhesive, the exterior member 101 is given excellent electrolyte resistance, and peeling of the base layer 101A is suppressed even if electrolyte adheres to the side surface.

[0073] Furthermore, the adhesive layer 101B may contain other components as long as they do not impair adhesion, and may contain colorants, thermoplastic elastomers, tackifiers, fillers, etc. The presence of a colorant in the adhesive layer 101B allows the exterior component 101 to be colored. Known colorants such as pigments and dyes can be used. Additionally, only one type of colorant may be used, or two or more types may be mixed.

[0074] The type of pigment is not particularly limited, as long as it does not impair the adhesion of the adhesive layer 101B. Examples of organic pigments include azo, phthalocyanine, quinacridone, anthraquinone, dioxazine, indigothioindigo, perinone-perylene, isoindorenine, and benzimidazolon pigments. Examples of inorganic pigments include carbon black, titanium dioxide, cadmium, lead, chromium oxide, and iron pigments. Other examples include fine mica powder and fish scale foil.

[0075] Among colorants, carbon black is preferred, for example, to give the exterior component 101 a black appearance.

[0076] The average particle size of the pigment is not particularly limited, but for example, it can be about 0.05 to 5 μm, preferably about 0.08 to 2 μm. The average particle size of the pigment is the median diameter measured by a laser diffraction / scattering particle size distribution analyzer.

[0077] The pigment content in the adhesive layer 101B is not particularly limited as long as the exterior member 101 is colored, and for example, it is about 5 to 60% by mass, preferably 10 to 40% by mass.

[0078] The thickness of the adhesive layer 101B is not particularly limited as long as it can bond the substrate layer 101A and the barrier layer 101C. For example, the lower limit can be about 1 μm or more, or about 2 μm or more, and the upper limit can be about 10 μm or less, or about 5 μm or less. Preferred ranges can be about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, or about 2 to 5 μm.

[0079] <1-1-3. Colored layer> The colored layer is a layer provided between the base layer 101A and the barrier layer 101C as needed (not shown in the figure). If an adhesive layer 101B is present, the colored layer may be provided between the base layer 101A and the adhesive layer 101B, and between the adhesive layer 101B and the barrier layer 101C. Alternatively, the colored layer may be provided on the outside of the base layer 101A. By providing the colored layer, the exterior member 101 can be colored.

[0080] The colored layer can be formed, for example, by applying an ink containing a coloring agent to the surface of the substrate layer 101A, the adhesive layer 101B, or the barrier layer 101C. Known coloring agents such as pigments and dyes can be used. In addition, only one type of coloring agent may be used, or two or more types may be mixed and used.

[0081] Specific examples of colorants included in the colored layer are the same as those exemplified in the adhesive layer 101B.

[0082] <1-1-4. Barrier Layer> In the exterior component 101, the barrier layer 101C is a layer that at least prevents the intrusion of moisture.

[0083] The barrier layer 101C of the exterior component 101 contains aluminum alloy foil. The characteristics of the aluminum alloy foil are described below.

[0084] ·Fe: 0.2 mass% or more and 2.0 mass% or less Fe crystallizes as Al-Fe intermetallic compounds during casting, and if the size of these compounds is large, they become recrystallization sites during annealing, thus having the effect of refining the recrystallized grains. If the Fe content falls below the lower limit, the distribution density of coarse intermetallic compounds decreases, the effect of grain refinement is reduced, and the final grain size distribution becomes non-uniform. If the content exceeds the upper limit, the effect of grain refinement saturates or even decreases, and the size of the Al-Fe intermetallic compounds generated during casting becomes very large, reducing the elongation and rollability of the foil. For this reason, the Fe content is set within the above range. For the same reason, it is preferable to set the Fe content to a lower limit of 0.5 mass%, and for the same reason, it is even more preferable to set the Fe content to a lower limit of 1.0 mass% and an upper limit of 1.8 mass%.

[0085] ·Mg: 0.1 mass% or more and 5.0 mass% or less Mg dissolves in aluminum, and solid solution strengthening can increase the strength of soft foils. Furthermore, because Mg readily dissolves in aluminum, even when included with Fe, there is little risk of intermetallic compound coarsening and a decrease in the conformability and rollability of exterior components at corners, etc. If the Mg content falls below the lower limit, the improvement in strength will be insufficient, and if the Mg content exceeds the upper limit, the aluminum alloy foil will become hard, leading to a decrease in rollability and formability. The particularly preferable range for Mg content is 0.5% by mass or more and 5.0% by mass or less.

[0086] It was also confirmed that adding Mg improves the corrosion resistance of lithium-ion secondary batteries to the electrolyte. Although the detailed mechanism is not clear, the more Mg added, the less likely the aluminum alloy foil is to react with lithium in the electrolyte, thereby suppressing the pulverization of the aluminum alloy foil and the formation of through-holes. While the conformability of the exterior components at corners and other areas is slightly reduced, it is desirable to set the lower limit of the Mg content to 0.5 mass% when a particularly clear improvement in corrosion resistance is expected.

[0087] Preferably, Si: 0.5% by mass or less In small amounts, silicon (Si) may be added to increase the strength of the foil. In this embodiment, the composition of the aluminum alloy foil has a Si content of 0.5 mass% or less. As a result, the size of the Al-Fe-Si intermetallic compounds formed during casting is reduced, improving the elongation of the foil and the conformability of the exterior components at corners and other areas. Furthermore, even when the foil thickness is thin, fracture originating from the intermetallic compounds is less likely to occur, and the rollability is also good. In addition, by not adding a large amount of Si, the amount of Mg-Si precipitates formed is reduced, making it less likely for the rollability and solid solution amount of Mg to decrease, thus reducing the likelihood of a decrease in strength. For similar reasons, it is desirable to keep the Si content to 0.2 mass% or less. The lower the Si content, the better the conformability of the exterior components at corners and other areas, the rollability, the degree of grain refinement, and the ductility tend to be.

[0088] • Inevitable impurities In addition, aluminum alloy foil may contain unavoidable impurities such as Cu and Mn. It is desirable that the amount of each of these unavoidable elements be 0.1% by mass or less. However, in this embodiment, the upper limit of the content of the aforementioned unavoidable impurities is not limited to the above values.

[0089] However, since Mn does not readily dissolve in aluminum, unlike Mg, it cannot be expected to significantly increase the strength of soft foil through solid solution strengthening. Furthermore, adding large amounts of Mn to alloys with a high Fe content increases the risk of coarsening of intermetallic compounds and the formation of large Al-Fe-Mn intermetallic compounds, which may lead to a decrease in rollability and the conformability of exterior components at corners and other areas. For this reason, it is desirable to keep the Mn content to 0.1% by mass or less.

[0090] • The azimuthal density of the Copper and R directions of the collective organization is 15 or less. The texture significantly affects the mechanical properties of the foil and the conformability of the exterior material at corners and other areas. If the density of either the Copper or R orientation exceeds 15, there is a concern that uniform deformation cannot be achieved during molding, leading to a decrease in the conformability of the exterior material at corners and other areas. To obtain good conformability of the exterior material at corners and other areas, it is desirable to keep the density of both the Copper and R orientations below 15. More preferably, the density of each orientation should be 10 or less.

[0091] • Surface Mg concentration of 5.0 atomic percent or more, and oxide film thickness of 80 Å or more (when Mg: 0.1% by mass or more and 1.5% by mass or less) Although the detailed mechanism is not clear, it has been confirmed that the Mg concentration on the foil surface and the thickness of the oxide film contribute to the corrosion resistance of lithium-ion secondary batteries to the electrolyte. Corrosion resistance is improved when the Mg concentration on the foil surface is high and a thick oxide film is formed. For this reason, when the Mg content is between 0.1% by mass and 1.5% by mass, it is desirable to have an Mg concentration of 5.0 atomic percent or more on the aluminum foil surface and an oxide film thickness of 80 Å or more. More preferably, the surface Mg concentration is 15.0 atomic percent or more and the oxide film thickness is 200 Å or more. Even more preferably, the surface Mg concentration is 20.0 atomic percent or more. Here, the surface Mg concentration is the Mg concentration of the surface portion from the outermost surface to a depth of 8 nm, and the Mg concentration is the amount relative to 100 atomic percent of the total of all elements.

[0092] • Surface Mg concentration of 15.0 atomic percent or more, and oxide film thickness of 120 Å or more (when Mg: greater than 1.5 mass% and 5.0 mass% or less) As mentioned above, although the details of the mechanism are not clear, it has been confirmed that the Mg concentration on the foil surface and the thickness of the oxide film contribute to the corrosion resistance of lithium-ion secondary batteries to the electrolyte. Corrosion resistance is improved when the Mg concentration on the foil surface is high and a thick oxide film is formed. For this reason, when the Mg: greater than 1.5 mass% and less than or equal to 5.0 mass%, it is desirable to have an Mg concentration of 15.0 atomic percent or more on the aluminum foil surface and an oxide film thickness of 120 Å or more. More preferably, the surface Mg concentration is 20.0 atomic percent or more and the oxide film thickness is 220 Å or more. Even more preferably, the surface Mg concentration is 25.0 atomic percent or more.

[0093] When L1 is the length of the large-angle grain boundary per unit area measured by backscattered electron diffraction, and L2 is the length of the small-angle grain boundary, then L1 / L2 > 3.0 The ratio of high-angle grain boundaries (HAGB) to low-angle grain boundaries (LAGB) in the recrystallized grain structure after annealing affects the elongation of the foil and the conformability of the exterior material at corners and other areas. If the proportion of LAGB is high in the recrystallized grain structure after final annealing, deformation localization is more likely to occur, reducing elongation and the conformability of the exterior material at corners and other areas. Therefore, by increasing the proportion of HAGB by setting L1 / L2 > 3.0, high elongation and good conformability of the exterior material at corners and other areas can be expected. More preferably, L1 / L2 > 5.0.

[0094] • Tensile strength: 110 MPa to 180 MPa (when Mg: 0.1% by mass to 1.5% by mass) When the Mg content is between 0.1% and 1.5% by mass, a tensile strength of 110 MPa or higher is required to dramatically improve impact resistance and puncture resistance compared to existing foils such as JIS A8079 and 8021. In particular, to ensure good conformability of exterior components at corners and other areas, a tensile strength of 180 MPa or lower is preferable. Tensile strength can be achieved by selecting the composition and optimizing the crystal grain size.

[0095] • Tensile strength: 180 MPa or higher (when Mg: greater than 1.5% by mass and less than or equal to 5.0% by mass) When the Mg content is between 1.5% and 5.0% by mass, a tensile strength of 180 MPa or higher is preferable to dramatically improve impact resistance and puncture resistance compared to existing foils such as JIS A8079 and 8021. For the same reason, a tensile strength of 200 MPa or higher is desirable. However, the conformability of exterior components at corners and other areas decreases as the tensile strength increases, so if conformability is important, it is better to keep the tensile strength lower. As mentioned above, tensile strength can be achieved by selecting the composition and optimizing the crystal grain size.

[0096] • Elongation at break: 10% or more (when Mg: 0.1% by mass or more and 1.5% by mass or less) The effect of elongation on the conformability of exterior components at corners and other areas varies greatly depending on the molding method, and elongation alone does not determine the conformability of exterior components at corners and other areas. In the bulging process commonly used for aluminum packaging materials, the higher the elongation of the aluminum alloy foil, the more advantageous the conformability of the exterior components at corners and other areas. When the Mg content is between 0.1% and 1.5% by mass, an elongation of 10% or more is desirable. The elongation characteristics can be achieved by selecting the composition and refining the crystal grain size.

[0097] • Elongation: 15% or more (when Mg: greater than 1.5% by mass and less than or equal to 5.0% by mass) As mentioned above, the effect of elongation on the conformability of exterior components at corners and other areas varies greatly depending on the molding method, and elongation alone does not determine the conformability of exterior components at corners and other areas. However, in the bulging process commonly used for aluminum packaging materials, the higher the elongation of the aluminum alloy foil, the more advantageous the conformability. When Mg: greater than 1.5% by mass and less than or equal to 5.0% by mass, it is desirable to have an elongation of 15% or more. As mentioned above, the elongation characteristics can be achieved by selecting the composition and refining the crystal grain size.

[0098] ·Average grain size: 25μm or less Soft aluminum alloy foil, with its fine grain size, suppresses surface roughness during deformation, resulting in high elongation and the resulting conformability to exterior components, especially at high corners. The effect of grain size becomes greater as the foil thickness decreases. To achieve high elongation and the resulting conformability to exterior components at high corners, an average grain size of 25 μm or less is desirable. This average grain size can be achieved through careful composition selection and optimized manufacturing conditions, including homogenization treatment and cold rolling ratio.

[0099] The following describes the method for preparing aluminum alloy foil. Aluminum alloy ingots are cast using conventional methods such as semi-continuous casting. The aluminum alloy ingots have a composition containing Fe: 0.2% to 2.0% by mass, Mg: 0.1% to 5.0% by mass, with the remainder being Al and unavoidable impurities, and optionally Mn: 0.1% by mass or less. The resulting ingots are subjected to a homogenization treatment at 480 to 550°C for 6 to 12 hours.

[0100] • Homogenization process: 450~550℃ Homogenization treatment aims to eliminate microsegregation within the ingot and adjust the distribution of intermetallic compounds, and is a crucial process for ultimately obtaining the desired grain structure. Generally, homogenization of aluminum materials is performed at 400-600°C for a long period of time, but in this invention, it is necessary to consider grain refinement by adding Fe. In the homogenization process, at temperatures below 450°C, Fe precipitation is insufficient, raising concerns about grain coarsening during final annealing. Furthermore, an increase in the proportion of in-situ recrystallization leads to a higher proportion of LAGB, raising concerns about a decrease in L1 / L2. Additionally, an increase in the density of each orientation (Copper and R) raises concerns about reduced conformability of the exterior material at corners and other areas. At temperatures above 550°C, crystallized material grows significantly, leading to grain coarsening during final annealing and reduced conformability of the exterior material at corners and other areas. The homogenization process must be conducted for at least 3 hours. Less than 3 hours results in insufficient precipitation and a decrease in the density of fine intermetallic compounds. Ideally, the temperature should be between 480 and 520°C for at least 5 hours.

[0101] After homogenization treatment, hot rolling is performed to obtain an aluminum alloy sheet of the desired thickness. Hot rolling can be carried out by conventional methods, but it is desirable that the coiling temperature during hot rolling be above the recrystallization temperature, specifically above 300°C. Below 300°C, fine Al-Fe intermetallic compounds of 0.3 μm or less will precipitate. Furthermore, after hot rolling, recrystallized grains and fiber grains may be mixed, leading to concerns that the grain size will become non-uniform after intermediate and final annealing, resulting in a decrease in elongation properties, which is undesirable.

[0102] After hot rolling, cold rolling, intermediate annealing, and final cold rolling are performed to obtain the aluminum alloy foil of the present invention, with a thickness of 5 to 100 μm. There are two methods for intermediate annealing: batch annealing, in which coils are placed in a furnace and held for a certain period of time, and continuous annealing line (CAL annealing), which rapidly heats and cools the material. When applying intermediate annealing, either method is acceptable, but CAL annealing is preferable when the goal is to refine the crystal grains and increase strength. However, after CAL annealing, the texture develops after the final cold rolling and final annealing, and there is a concern that the density of copper and R orientations will increase, reducing the conformability of exterior components at corners and other areas. For this reason, batch annealing is preferable if conformability of exterior components at corners and other areas is a priority.

[0103] For example, in batch annealing, conditions of 300-400°C for 3 hours or more can be used. In CAL annealing, conditions such as heating rate: 10-250°C / second, heating temperature: 400-550°C, holding time: none or holding time: 5 seconds or less, and cooling rate: 20-200°C / second can be used. However, the present invention is not limited to specific conditions regarding the presence or absence of intermediate annealing, or the conditions under which intermediate annealing is performed.

[0104] • Final cold rolling ratio: 84.0% to 97.0% The higher the final cold rolling ratio from intermediate annealing to the final thickness, the greater the amount of strain accumulated in the material, resulting in finer recrystallized grains after final annealing. It also has the effect of suppressing in-situ recrystallization, and an improvement in the conformability of exterior components at corners, etc., due to the increase in L1 / L2, can be expected. Specifically, it is desirable to set the final cold rolling ratio to 84.0% or higher. However, if the final cold rolling ratio is too high, there is a concern that the conformability of exterior components at corners, etc., will decrease due to an increase in the density of each orientation, Copper orientation and R orientation, even after final annealing. As a result, a decrease in L1 / L2 will also occur, so specifically, it is desirable to set the final cold rolling ratio to 97.0% or lower. Furthermore, if the final cold rolling ratio is too low, there is a concern that the grain coarsening and the conformability of exterior components at corners, etc., due to a decrease in L1 / L2, will decrease. For similar reasons, an even more desirable range for the final cold rolling ratio is 90.0% to 93.0%.

[0105] After foil rolling, a final annealing is performed to create a soft foil. Generally, the final annealing after foil rolling can be carried out at 250°C to 400°C. However, to enhance the corrosion resistance effect of Mg, it is desirable to hold the foil at a high temperature of 300°C or higher for 5 hours or more, and a temperature of 350°C to 400°C is even more desirable. If the final annealing temperature is too low, softening will be insufficient, raising concerns about a decrease in L1 / L2 ratio and an increase in density in both the copper and R orientations. Furthermore, insufficient concentration of Mg on the foil surface and insufficient growth of the oxide film may lead to reduced corrosion resistance. Above 400°C, excessive concentration of Mg on the foil surface may cause discoloration, alter the properties of the oxide film, and create microscopic cracks, resulting in reduced corrosion resistance. A final annealing time of less than 5 hours is insufficient for effective annealing.

[0106] The resulting aluminum alloy foil, at room temperature, exhibits, for example, a tensile strength of 110 MPa to 180 MPa and an elongation of 10% or more when the Mg content is between 0.1% and 1.5% by mass. When the Mg content is between 1.5% and 5.0% by mass, it exhibits, for example, a tensile strength of 180 MPa or more and an elongation of 15% or more. Furthermore, the average grain size is 25 μm or less. The average grain size can be determined by the cutting method specified in JIS G0551.

[0107] The thickness of the aluminum alloy foil in the exterior component 101 should at least function as a barrier layer that prevents moisture from entering, with a lower limit of approximately 9 μm or more and an upper limit of approximately 200 μm or less. From the viewpoint of reducing the thickness of the exterior member 101, the thickness of the aluminum alloy foil can be, for example, preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 45 μm or less, and particularly preferably about 40 μm or less as an upper limit, and preferably about 10 μm or more, even more preferably about 20 μm or more, and more preferably about 25 μm or more as a lower limit, and a preferred range for the thickness can be about 10 to 85 μm, about 10 to 50 μm, about 10 to 45 μm, about 10 to 40 μm, about 20 to 85 μm, about 20 to 50 μm, about 20 to 45 μm, about 20 to 40 μm, about 25 to 85 μm, about 25 to 50 μm, about 25 to 45 μm, and about 25 to 40 μm.

[0108] Furthermore, it is preferable that the aluminum alloy foil has a corrosion-resistant coating on at least one side to suppress the dissolution and corrosion of the aluminum alloy foil. The aluminum alloy foil may also have a corrosion-resistant coating on both sides. Here, a corrosion-resistant coating refers to a thin film that provides corrosion resistance to the aluminum alloy foil by performing treatments on the surface of the aluminum alloy foil, such as hydrothermal modification treatments like boehmite treatment, chemical conversion treatments, anodizing treatments, plating treatments with nickel or chromium, or corrosion prevention treatments such as coating agents. 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 rather than just one layer. Furthermore, among these treatments, hydrothermal 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. Note that these treatments may also be included in the definition of chemical conversion treatment. Also, if the aluminum alloy foil has a corrosion-resistant coating, the aluminum alloy foil includes the corrosion-resistant coating.

[0109] The corrosion-resistant coating prevents delamination between the aluminum alloy foil and the base layer during the molding of the exterior component 101, prevents dissolution and corrosion of the aluminum alloy foil surface due to hydrogen fluoride generated by the reaction of electrolyte and water, prevents dissolution and corrosion of aluminum oxide present on the aluminum alloy foil surface, improves the adhesion (wettability) of the aluminum alloy foil surface, and exhibits the effect of preventing delamination between the base layer and the aluminum alloy foil during heat sealing and molding.

[0110] Various corrosion-resistant coatings are known to be formed by chemical conversion treatments, mainly including corrosion-resistant coatings containing at least one of the following: phosphates, chromates, fluorides, triazinethiol compounds, and rare earth oxides. Examples of chemical conversion treatments using phosphates and chromates include chromate treatment, phosphate chromate treatment, phosphate-chromate treatment, and chromate treatment. Examples of chromium compounds used in these treatments include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, acetyl acetate chromate, chromium chloride, and potassium chromium sulfate. Examples of phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphate. Examples of chromate treatments include etching chromate treatment, electrolytic chromate treatment, and coating-type chromate treatment, with coating-type chromate treatment being preferred. This coating-type chromate treatment involves first degreasing at least the inner surface of a barrier layer (e.g., aluminum alloy foil) using a well-known treatment method such as alkaline immersion, electrolytic cleaning, acid cleaning, electrolytic acid cleaning, or acid activation. Then, a treatment solution mainly composed of metal phosphate salts such as chromium phosphate, titanium phosphate, zirconium phosphate, and zinc phosphate, or mixtures thereof, or a treatment solution mainly composed of nonmetallic phosphates and mixtures thereof, or a treatment solution consisting of a mixture of these with synthetic resins, etc., is applied to the degreased surface using a well-known coating method such as roll coating, gravure printing, or immersion, and then dried. Various solvents can be used as the treatment solution, such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Furthermore, examples of resin components used in this process include polymers such as phenolic resins and acrylic resins, and examples of chromate treatment using an amination phenol polymer having repeating units represented by the following general formulas (1) to (4). In this amination phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be included individually or in any combination of two or more types.The acrylic resin is preferably polyacrylic acid, acrylate methacrylate copolymer, acrylate maleic acid copolymer, acrylate styrene copolymer, or derivatives thereof such as sodium salts, ammonium salts, or amine salts. Derivatives of polyacrylic acid, such as ammonium salts, sodium salts, or amine salts of polyacrylic acid, are particularly preferred. In this embodiment, polyacrylic acid refers to a polymer of acrylic acid. Furthermore, the acrylic resin is also preferably a copolymer of acrylic acid and a dicarboxylic acid or dicarboxylic acid anhydride, and also preferably an ammonium salt, sodium salt, or amine salt of a copolymer of acrylic acid and a dicarboxylic acid or dicarboxylic acid anhydride. Only one type of acrylic resin may be used, or two or more types may be mixed and used.

[0111] [ka]

[0112] [ka]

[0113] [ka]

[0114] [ka]

[0115] In general formulas (1) to (4), X represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group, or a benzyl group. Also, R 1 and R 2 Each of these represents a hydroxyl group, an alkyl group, or a hydroxyalkyl group, either identical or different. In general formulas (1) to (4), X and R 1 and R 2Examples of the alkyl group represented by [alkyl group] include linear or branched alkyl groups having 1 to 4 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, etc. Also, X, R 1 and R 2 Examples of the hydroxyalkyl group represented by [hydroxyalkyl group] include linear or branched alkyl groups having 1 to 4 carbon atoms substituted with 1 hydroxy group such as hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group, etc. In General Formulas (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, R 1 and R 2 may be the same or different from each other. In General Formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group or a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer having the repeating units represented by General Formulas (1) to (4) is preferably about 500 to 1,000,000, and more preferably about 1,000 to 20,000. The aminated phenol polymer is produced, for example, by polycondensing a phenol compound or a naphthol compound and formaldehyde to produce a polymer composed of the repeating units represented by the above General Formula (1) or General Formula (3), and then introducing a functional group (-CH2NR 1 R 2 ) into the polymer obtained above using formaldehyde and an amine (R 1 R 2 ). The aminated phenol polymer is used alone or in combination of two or more.

[0116] Another example of a corrosion-resistant coating is a thin film formed by a coating-type corrosion prevention treatment, which involves applying a coating agent containing at least one selected from the group consisting of rare earth element oxide sols, anionic polymers, and cationic polymers. The coating agent may further contain phosphoric acid or phosphate, and a crosslinking agent for crosslinking the polymer. In the rare earth element oxide sol, fine particles of rare earth element oxides (for example, particles with an average particle size of 100 nm or less) are dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, with cerium oxide being preferred from the viewpoint of further improving adhesion. The rare earth element oxides contained in the corrosion-resistant coating can be used individually or in combination of two or more. Various solvents can be used as the liquid dispersion medium for the rare earth element oxide sol, such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Preferred cationic polymers include, for example, polyethyleneimine, ionic polymer complexes comprising polyethyleneimine and a polymer having a carboxylic acid, primary amine-grafted acrylic resins obtained by graft polymerization of a primary amine onto an acrylic main skeleton, polyallylamine or its derivatives, and amination phenols. Preferred anionic polymers are poly(meth)acrylic acid or its salts, or copolymers mainly composed of (meth)acrylic acid or its salts. Furthermore, the crosslinking agent is preferably at least one selected from the group consisting of a compound having one of the functional groups of isocyanate, glycidyl, carboxyl, or oxazoline, and a silane coupling agent. Additionally, the phosphoric acid or phosphate is preferably condensed phosphoric acid or condensed phosphate.

[0117] One example of a corrosion-resistant coating is one formed by dispersing metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide, or fine particles of barium sulfate, in phosphoric acid, applying this mixture to the surface of a barrier layer, and then baking it at a temperature of 150°C or higher.

[0118] The corrosion-resistant coating may, if necessary, be a laminated structure in which at least one of a cationic polymer and an anionic polymer is further laminated. Examples of cationic and anionic polymers include those mentioned above.

[0119] Furthermore, the composition of the corrosion-resistant coating can be analyzed, for example, using time-of-flight secondary ion mass spectrometry.

[0120] There are no particular restrictions on the amount of corrosion-resistant coating formed on the surface of the aluminum alloy foil during chemical conversion treatment, but for example, in the case of coating-type chromate treatment, the amount of coating applied to the surface of the aluminum alloy foil is 1 m 2 It is desirable that the product contains, for example, about 0.5 to 50 mg of chromium-based chromium, preferably about 1.0 to 40 mg of phosphorus-based chromium

[0121] The thickness of the corrosion-resistant coating is not particularly limited, but from the viewpoint of the cohesive force of the coating and the adhesion force with the barrier layer and the heat-fusible resin layer, it is preferably about 1 nm to 20 μm, more preferably about 1 nm to 100 nm, and even more preferably about 1 nm to 50 nm. The thickness of the corrosion-resistant coating can be measured by observation with a transmission electron microscope, or by a combination of observation with a transmission electron microscope and energy-dispersive X-ray spectroscopy or electron beam energy loss spectroscopy. By analyzing the composition of the corrosion-resistant coating using time-of-flight secondary ion mass spectrometry, for example, secondary ions consisting of Ce, P, and O (e.g., Ce2PO4) can be identified. + CePO4 - (at least one of the above), or, for example, a secondary ion consisting of Cr, P, and O (e.g., CrPO2) + , CrPO4 - Peaks originating from at least one of the following are detected.

[0122] The chemical conversion treatment is carried out by applying a solution containing compounds used to form a corrosion-resistant film to the surface of the aluminum alloy foil using methods such as bar coating, roll coating, gravure coating, or immersion, and then heating the aluminum alloy foil to a temperature of approximately 70-200°C. Alternatively, before applying the chemical conversion treatment to the aluminum alloy foil, it may be subjected to a degreasing treatment using methods such as alkaline immersion, electrolytic cleaning, acid cleaning, or electrolytic acid cleaning. This degreasing treatment makes it possible to perform the chemical conversion treatment on the surface of the aluminum alloy foil more efficiently. Furthermore, by using an acid degreasing agent, which is a fluorine-containing compound dissolved in an inorganic acid, it is possible to not only degrease the metal foil but also form a fluoride of the passive metal; in such cases, only the degreasing treatment may be performed.

[0123] <1-1-5. Heat-fusible resin layer> In the exterior component 101, the heat-sealable resin layer 101D is the innermost layer and is a layer (sealant layer) that performs the function of sealing the electrode body 200 by heat-sealing the heat-sealable resin layers 101D together during the assembly of the energy storage device 10.

[0124] The resin constituting the heat-fusible resin layer 101D is not particularly limited as long as it is heat-fusible, but resins containing a polyolefin backbone, such as polyolefins and acid-modified polyolefins, are preferred. The presence of a polyolefin backbone in the resin constituting the heat-fusible resin layer 101D can be analyzed, for example, by infrared spectroscopy or gas chromatography-mass spectrometry. Furthermore, when the resin constituting the heat-fusible resin layer 101D is analyzed by infrared spectroscopy, it is preferable that peaks originating from maleic anhydride are detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, peaks originating from maleic anhydride are detected around wavenumbers 1760 cm⁻¹ and 1780 cm⁻¹. If the heat-fusible resin layer 101D is a layer composed of maleic anhydride-modified polyolefin, peaks originating from maleic anhydride will be detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peaks may become small and not be detected. In that case, analysis can be performed by nuclear magnetic resonance spectroscopy.

[0125] Examples of polyolefins include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymer of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymer of propylene and ethylene); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. Among these, polypropylene is preferred. When polyolefin resins are copolymers, they may be block copolymers or random copolymers. These polyolefin resins may be used individually or in combination of two or more.

[0126] Furthermore, the polyolefin may be a cyclic polyolefin. A cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of olefins that are constituent monomers of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, isoprene, and the like. Examples of cyclic monomers that are constituent monomers of the cyclic polyolefin include cyclic alkenes such as norbornene; and cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, norbornadiene, and the like. Among these, cyclic alkenes are preferred, and norbornene is more preferred.

[0127] Acid-modified polyolefins are polymers obtained by modifying polyolefins through block polymerization or graft polymerization with an acid component. Examples of polyolefins that can be acid-modified include the aforementioned... Polyolefins, copolymers obtained by copolymerizing the aforementioned polyolefins with polar molecules such as acrylic acid or methacrylic acid, or polymers such as crosslinked polyolefins can also be used. Examples of acid components used for acid modification include carboxylic acids or their anhydrides, such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

[0128] Acid-modified polyolefins may also be acid-modified cyclic polyolefins. Acid-modified cyclic polyolefins are polymers obtained by copolymerizing a portion of the monomers constituting a cyclic polyolefin with an acid component, or by block polymerization or graft polymerization of an acid component to a cyclic polyolefin. The cyclic polyolefin to be acid-modified is the same as described above. Furthermore, the acid component used for acid modification is the same as the acid component used for modifying the polyolefin described above.

[0129] Preferred acid-modified polyolefins include polyolefins modified with carboxylic acids or their anhydrides, polypropylenes modified with carboxylic acids or their anhydrides, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

[0130] The heat-sealable resin layer 101D may be formed by a single resin or by a blended polymer of two or more resins. Furthermore, the heat-sealable resin layer 101D may be formed as a single layer or as two or more layers of the same or different resins.

[0131] Furthermore, the heat-fusible resin layer 101D may contain a lubricant or the like as needed. When the heat-fusible resin layer 101D contains a lubricant, the conformability of the exterior member 101 at corners and other parts of the exterior member can be improved. The lubricant is not particularly limited, and known lubricants can be used. The lubricant may be used alone or in combination of two or more types.

[0132] The lubricant is not particularly limited, but amide-based lubricants are preferred. Specific examples of lubricants include those exemplified in the substrate layer 101A. The lubricant may be used alone or in combination of two or more types.

[0133] When a lubricant is present on the surface of the heat-fusible resin layer 101D, the amount present is not particularly limited, but from the viewpoint of improving the conformability of the exterior member 101 at corners and other parts of the exterior member, it is preferably about 10 to 50 mg / m2, and more preferably about 15 to 40 mg / m2.

[0134] The lubricant present on the surface of the heat-fusible resin layer 101D may be a lubricant contained in the resin constituting the heat-fusible resin layer 101D that has seeped out, or a lubricant may be applied to the surface of the heat-fusible resin layer 101D.

[0135] Furthermore, the thickness of the heat-fusible resin layer 101D is not particularly limited as long as the heat-fusible resin layers heat-fuse together to seal the energy storage device element, but for example, it can be about 100 μm or less, preferably about 85 μm or less, and more preferably about 15 to 85 μm. For example, if the thickness of the adhesive layer 101E described later is 10 μm or more, the thickness of the heat-fusible resin layer 101D can be preferably about 85 μm or less, and more preferably about 15 to 45 μm. For example, if the thickness of the adhesive layer 101E described later is less than 10 μm or if the adhesive layer 101E is not provided, the thickness of the heat-fusible resin layer 101D can be preferably about 20 μm or more, and more preferably about 35 to 85 μm.

[0136] <1-1-6.Adhesive layer> In the exterior component 101, the adhesive layer 101E is a layer provided as needed between the barrier layer 101C (or acid-resistant coating) and the heat-fusible resin layer 101D in order to firmly bond them together.

[0137] The adhesive layer 101E is formed of a resin capable of bonding the barrier layer 101C and the heat-fusible resin layer 101D. Preferably, the adhesive layer 101E is formed of a cured product of a resin composition containing a curable resin. A curable resin refers to a resin that has curability, such as a thermosetting resin or an ionizing radiation curable resin, and is, for example, one that does not have a clear melting peak temperature after curing. As the resin used to form the adhesive layer 101E, for example, the same type of adhesive as exemplified in the adhesive layer 101B can be used. Preferably, the resin used to form the adhesive layer 101E contains a polyolefin skeleton, and examples include the polyolefin and acid-modified polyolefin exemplified in the heat-fusible resin layer 101D mentioned above. Whether the resin constituting the adhesive layer 101E contains a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy or gas chromatography-mass spectrometry, and the analytical method is not particularly limited. Furthermore, when the resin constituting the adhesive layer 101E is analyzed by infrared spectroscopy, it is preferable that a peak originating from maleic anhydride is detected. For example, when measuring maleic anhydride-modified polyolefins using infrared spectroscopy, at a wavenumber of 1760 cm⁻¹-1 Nearby wave frequency 1780cm -1 A peak originating from maleic anhydride is detected in the vicinity. However, if the degree of acid denaturation is low, the peak may become small and not be detected. In that case, analysis is possible by nuclear magnetic resonance spectroscopy.

[0138] From the viewpoint of firmly bonding the barrier layer 101C and the heat-fusible resin layer 101D, the adhesive layer 101E preferably contains an acid-modified polyolefin. Particularly preferred as the acid-modified polyolefin are polyolefins modified with a carboxylic acid or its anhydride, polypropylenes modified with a carboxylic acid or its anhydride, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

[0139] Furthermore, from the viewpoint of reducing the thickness of the exterior member 101 while providing an exterior member 101 with excellent shape stability after molding, it is more preferable that the adhesive layer 101E is a cured product of a resin composition containing acid-modified polyolefin and a curing agent. In this case, the acid-modified polyolefin and the curing agent constitute the curable resin. Preferably, the above-mentioned products can be used as examples of acid-modified polyolefins.

[0140] Furthermore, the adhesive layer 101E is preferably a cured product of a resin composition comprising an acid-modified polyolefin and at least one selected from the group consisting of compounds having isocyanate groups, compounds having oxazoline groups, and compounds having epoxy groups, and is particularly preferably a cured product of a resin composition comprising an acid-modified polyolefin and at least one selected from the group consisting of compounds having isocyanate groups and compounds having epoxy groups. Furthermore, the adhesive layer 101E preferably contains at least one selected from the group consisting of polyurethane, polyester, and epoxy resin, and more preferably contains polyurethane and epoxy resin. As polyester, for example, amide ester resin is preferred. Amide ester resin is generally produced by the reaction of a carboxyl group and an oxazoline group. The adhesive layer 101E is more preferably a cured product of a resin composition comprising at least one of these resins and the acid-modified polyolefin. Furthermore, if unreacted compounds containing isocyanate groups, compounds containing oxazoline groups, or curing agents such as epoxy resin remain in the adhesive layer 101E, the presence of these unreacted compounds can be confirmed by methods selected from, for example, infrared spectroscopy, Raman spectroscopy, or time-of-flight secondary ion mass spectrometry (TOF-SIMS).

[0141] Furthermore, from the viewpoint of further improving the adhesion between the barrier layer 101C and the adhesive layer 101E, it is preferable that the adhesive layer 101E is a cured product of a resin composition containing a curing agent having at least one selected from the group consisting of oxygen atoms, heterocyclic rings, C=N bonds, and COC bonds. Examples of curing agents having heterocyclic rings include curing agents having oxazoline groups and curing agents having epoxy groups. Examples of curing agents having C=N bonds include curing agents having oxazoline groups and curing agents having isocyanate groups. Examples of curing agents having COC bonds include curing agents having oxazoline groups, curing agents having epoxy groups, and polyurethane. The fact that the adhesive layer 101E is a cured product of a resin composition containing these curing agents can be confirmed by methods such as gas chromatography-mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and X-ray photoelectron spectroscopy (XPS).

[0142] While there are no particular limitations on the compound having an isocyanate group, polyfunctional isocyanate compounds are preferred from the viewpoint of effectively improving the adhesion between the barrier layer 101C and the adhesive layer 101E. The polyfunctional isocyanate compound is not particularly limited as long as it has two or more isocyanate groups. Specific examples of polyfunctional isocyanate curing agents include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymerized or nurated versions thereof, mixtures thereof, and copolymers with other polymers. Adducts, burettes, and isocyanurates are also examples.

[0143] The content of the compound having an isocyanate group in the adhesive layer 101E is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition constituting the adhesive layer 101E. This effectively enhances the adhesion between the barrier layer 101C and the adhesive layer 101E.

[0144] Compounds containing an oxazoline group are not particularly limited as long as they have an oxazoline skeleton. Specific examples of compounds containing an oxazoline group include those with a polystyrene main chain and those with an acrylic main chain. Commercially available examples include the Epocross series manufactured by Nippon Shokubai Co., Ltd.

[0145] The proportion of the compound having an oxazoline group in the adhesive layer 101E is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition constituting the adhesive layer 101E. This effectively enhances the adhesion between the barrier layer 101C and the adhesive layer 101E.

[0146] Examples of compounds having epoxy groups include epoxy resins. The epoxy resin is not particularly limited as long as it is capable of forming a crosslinked structure by the epoxy groups present in the molecule; known epoxy resins can be used. The weight-average molecular weight of the epoxy resin is preferably around 50 to 2000, more preferably around 100 to 1000, and even more preferably around 200 to 800. In the first disclosure, the weight-average molecular weight of the epoxy resin is the value measured by gel permeation chromatography (GPC) under conditions using polystyrene as a standard sample.

[0147] Specific examples of epoxy resins include glycidyl ether derivatives of trimethylolpropane, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, and polyglycerin polyglycidyl ether. Epoxy resins may be used individually or in combination of two or more types.

[0148] The proportion of epoxy resin in the adhesive layer 101E is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition constituting the adhesive layer 101E. This effectively enhances the adhesion between the barrier layer 101C and the adhesive layer 101E.

[0149] The polyurethane is not particularly limited, and any known polyurethane can be used. The adhesive layer 101E may be, for example, a cured product of a two-component polyurethane.

[0150] The proportion of polyurethane in the adhesive layer 101E is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition constituting the adhesive layer 101E. This effectively enhances the adhesion between the barrier layer 101C and the adhesive layer 101E in an atmosphere where components that induce corrosion of the barrier layer, such as electrolytes, are present.

[0151] Furthermore, if the adhesive layer 101E is a cured product of a resin composition containing at least one compound selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and an epoxy resin, and the acid-modified polyolefin, the acid-modified polyolefin functions as the main agent, and the compound having an isocyanate group, the compound having an oxazoline group, and the compound having an epoxy group each function as a curing agent.

[0152] The thickness of the adhesive layer 101E is preferably about 50 μm or less, about 40 μm or less, about 30 μm or less, about 20 μm or less, and about 5 μm or less for the upper limit, and preferably about 0.1 μm or more and about 0.5 μm or more for the lower limit, and the range of the thickness is preferably about 0.1 to 50 μm, about 0.1 to 40 μm, about 0.1 to 30 μm, about 0.1 to 20 μm, about 0.1 to 5 μm, about 0.5 to 50 μm, about 0.5 to 40 μm, about 0.5 to 30 μm, about 0.5 to 20 μm, and about 0.5 to 5 μm. More specifically, in the case of the adhesive exemplified in adhesive layer 101B or the cured product of acid-modified polyolefin and curing agent, it is preferably about 1 to 10 μm, more preferably about 1 to 5 μm. Furthermore, when using the resin exemplified in the heat-fusible resin layer 101D, the thickness is preferably about 2 to 50 μm, more preferably about 10 to 40 μm. Note that if the adhesive layer 101E is an adhesive exemplified in the adhesive layer 101B, or a cured product of a resin composition containing an acid-modified polyolefin and a curing agent, the adhesive layer 101E can be formed, for example, by applying the resin composition and curing it by heating. Also, when using the resin exemplified in the heat-fusible resin layer 101D, it can be formed, for example, by extrusion molding of the heat-fusible resin layer 101D and the adhesive layer 101E.

[0153] <1-1-7.Surface coating layer 101F> The exterior member 101 may, if necessary, have a surface coating layer 101F on top of the base layer 101A (on the opposite side of the barrier layer 101C of the base layer 101A) for the purpose of improving at least one of the following: aesthetics, electrolyte resistance, scratch resistance, and conformability of the exterior member at corners, etc. The surface coating layer 101F is the outermost layer of the exterior member 101 when the energy storage device is assembled using the exterior member 101.

[0154] The surface coating layer 101F can be formed from a resin such as polyvinylidene chloride, polyester, polyurethane, acrylic resin, or epoxy resin.

[0155] If the resin forming the surface coating layer 101F is a curable resin, it may be either a one-component curable resin or a two-component curable resin, but is preferably a two-component curable resin. Examples of two-component curable resins include two-component curable polyurethane, two-component curable polyester, and two-component curable epoxy resin. Among these, two-component curable polyurethane is preferred.

[0156] Examples of two-component curable polyurethanes include polyurethanes comprising a main component containing a polyol compound and a curing agent containing an isocyanate compound. Preferably, two-component curable polyurethanes are used, with a polyol such as polyester polyol, polyether polyol, and acrylic polyol as the main component and an aromatic or aliphatic polyisocyanate as the curing agent. Furthermore, it is preferable to use a polyester polyol as the polyol compound, which has hydroxyl groups not only at the terminals of the repeating units but also in the side chains. The surface coating layer 101F is formed of polyurethane, which provides the exterior member 101 with excellent electrolyte resistance.

[0157] The surface coating layer 101F may contain, as necessary, additives such as the aforementioned lubricants, antiblocking agents, matting agents, flame retardants, antioxidants, tackifiers, and antistatic agents in at least one of its surface and interior, depending on the functionality to be provided to the surface coating layer 101F and its surface. Examples of additives include fine particles with an average particle size of about 0.5 nm to 5 μm. The average particle size of the additive is the median diameter measured by a laser diffraction / scattering particle size distribution analyzer.

[0158] The additive may be an inorganic or organic substance. Furthermore, there are no particular restrictions on the shape of the additive; examples include spherical, fibrous, plate-like, amorphous, or flaky forms.

[0159] Specific examples of additives include talc, silica, graphite, kaolin, montmorillonite, mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, high-melting-point nylon, acrylate resin, cross-linked acrylic, cross-linked styrene, cross-linked polyethylene, benzoguanamine, gold, aluminum, copper, and nickel. Additives may be used individually or in combination of two or more. Among these additives, silica, barium sulfate, and titanium oxide are preferred from the viewpoint of dispersion stability and cost. In addition, various surface treatments such as insulation treatment and high-dispersibility treatment may be applied to the surface of the additives.

[0160] The method for forming the surface coating layer 101F is not particularly limited, and one example is to apply a resin to form the surface coating layer 101F. If an additive is to be incorporated into the surface coating layer 101F, the resin mixed with the additive may be applied.

[0161] The thickness of the surface coating layer 101F is not particularly limited as long as it performs the above-mentioned functions as a surface coating layer 101F, and for example, it can be about 0.5 to 10 μm, preferably about 1 to 5 μm.

[0162] <1-1-8. Manufacturing method for exterior components> The method for manufacturing the exterior member 101 is not particularly limited, as long as a laminate is obtained by stacking the layers of the exterior member 101 of this embodiment. At a minimum, a method can be used that includes the step of stacking the base layer 101A, the barrier layer 101C, and the heat-fusible resin layer 101D in that order. As described above, an aluminum alloy foil satisfying the predetermined composition described above can be used as the barrier layer 101C.

[0163] An example of a method for manufacturing the exterior member 101 of this embodiment is as follows. First, a laminate (hereinafter sometimes referred to as "laminated body A") is formed by sequentially laminating a base material layer 101A, an adhesive layer 101B, and a barrier layer 101C. Specifically, laminate A can be formed by a dry lamination method in which the adhesive used to form the adhesive layer 101B is applied to the base material layer 101A or, if necessary, the surface of the barrier layer 101C which has been chemically treated, using a coating method such as gravure coating or roll coating, and after drying, the barrier layer 101C or base material layer 101A is laminated and the adhesive layer 101B is cured.

[0164] Next, a heat-fusible resin layer 101D is laminated onto the barrier layer 101C of laminate A. When directly laminating the heat-fusible resin layer 101D onto the barrier layer 101C, the heat-fusible resin layer 101D can be laminated onto the barrier layer 101C of laminate A by methods such as thermal lamination or extrusion lamination. Furthermore, when an adhesive layer 101E is provided between the barrier layer 101C and the heat-fusible resin layer 101D, for example, (1) a method of laminating by extruding the adhesive layer 101E and the heat-fusible resin layer 101D onto the barrier layer 101C of laminate A (co-extrusion lamination method, tandem lamination method), (2) a method of separately forming a laminate in which the adhesive layer 101E and the heat-fusible resin layer 101D are laminated, and then laminating this onto the barrier layer 101C of laminate A by thermal lamination, or a method of forming a laminate in which the adhesive layer 101E is laminated onto the barrier layer 101C of laminate A, and then laminating this onto the heat-fusible resin layer 101D and thermal lamination. Examples of lamination methods include (3) a method of laminating by a lamination method, in which a molten adhesive layer 101E is poured between the barrier layer 101C of the laminate A and a heat-fusible resin layer 101D that has been previously formed into a sheet, thereby bonding the laminate A and the heat-fusible resin layer 101D via the adhesive layer 101E (sandwich lamination method), and (4) a method of laminating by solution coating the barrier layer 101C of the laminate A with an adhesive to form the adhesive layer 101E, drying it, or even baking it, and then laminating the heat-fusible resin layer 101D that has been previously formed into a sheet on top of the adhesive layer 101E.

[0165] When a surface coating layer 101F is provided, the surface coating layer 101F is laminated on the surface of the base layer 101A opposite to the barrier layer 101C. The surface coating layer 101F can be formed, for example, by applying the resin used to form the surface coating layer 101F to the surface of the base layer 101A. The order of the steps of laminating the barrier layer 101C to the surface of the base layer 101A and laminating the surface coating layer 101F to the surface of the base layer 101A is not particularly limited. For example, the surface coating layer 101F may be formed on the surface of the base layer 101A, and then the barrier layer 101C may be formed on the surface of the base layer 101A opposite to the surface coating layer 101F.

[0166] As described above, a laminate is formed comprising, as necessary, a surface coating layer 101F, a base layer 101A, an adhesive layer 101B as necessary, a barrier layer 101C, an adhesive layer 101E as necessary, and a heat-fusible resin layer 101D in this order. In order to strengthen the adhesion of the adhesive layer 101B and the adhesive layer 101E as necessary, the laminate may be subjected to further heat treatment.

[0167] In the exterior component 101, each layer constituting the laminate may be subjected to surface activation treatments such as corona treatment, blast treatment, oxidation treatment, or ozone treatment as needed to improve processability. For example, by applying corona treatment to the surface of the base material layer 101A opposite to the barrier layer 101C, the printability of ink on the surface of the base material layer 101A can be improved.

[0168] 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 101D, and more preferably outside the barrier layer 101C. The buffering layers may be laminated on the outside of the base layer 101A, or the base layer 101A 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 the base layer 101A or the barrier layer 101C, etc.

[0169] 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.

[0170] 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.

[0171] 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.

[0172] 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.

[0173] In this embodiment, the base portion of the first sealing portion 110 is located on the edge 135 of the outer casing 100. The 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. That is, 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 exist on either the first surface 130 or the second surface 140. However, the base portion of the first sealing portion 110 may also be located on the second surface 140. In the energy storage device 10, the first sealing portion 110 is bent towards the second surface 140 with the 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.

[0174] 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.

[0175] Furthermore, in the energy storage device 10 of this embodiment, 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, 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.

[0176] 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.

[0177] 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.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] 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).

[0182] 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.

[0183] 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.

[0184] 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.

[0185] 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.

[0186] <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.

[0187] 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.

[0188] 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.

[0189] <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.

[0190] [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.

[0191] <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.

[0192] 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.

[0193] 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.

[0194] 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.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] 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.

[0199] <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.

[0200] 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.

[0201] 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.

[0202] <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.

[0203] <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.

[0204] 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.

[0205] 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).

[0206] 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.

[0207] 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.

[0208] 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.

[0209] [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.

[0210] <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.

[0211] 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.

[0212] 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.

[0213] 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.

[0214] 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.

[0215] <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.

[0216] 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).

[0217] 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.

[0218] 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.

[0219] <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.

[0220] [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.

[0221] <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.

[0222] 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.

[0223] <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. [Examples]

[0224] The embodiment will be described in detail below with reference to examples and comparative examples of energy storage devices. However, this embodiment is not limited to these examples.

[0225] Aluminum alloy ingots were prepared with the compositions shown in Tables 1 and 2 (the remainder being Al and other unavoidable impurities). Homogenization treatment was performed under the conditions shown in Tables 1 and 2, and then hot rolling was performed at a finishing temperature of 330°C to produce 3 mm thick plates. Subsequently, aluminum alloy foil samples with a thickness of 40 μm and a width of 1200 mm were prepared through cold rolling, intermediate annealing, final cold rolling, and final annealing. The conditions for intermediate and final annealing are shown in Tables 1 and 2. In Example 11, CAL annealing was performed as intermediate annealing. CAL was performed under the conditions of heating rate: 70°C / sec, heating temperature: 420°C, holding time: 0 seconds, and cooling rate: 50°C / sec. The cold rolling column in Tables 1 and 2 shows the plate thickness immediately before intermediate annealing and the cold rolling ratio up to that plate thickness. The following tests or measurements were performed on the exterior components containing the prepared aluminum alloy foil, and the results are shown in Tables 1 to 4.

[0226] • Tensile strength, elongation at break Both tensile strength and elongation at break were measured by tensile testing. The tensile testing was conducted in accordance with JIS Z2241, using JIS No. 5 test specimens taken from the sample to measure elongation in the 0° direction relative to the rolling direction. The tests were performed on a universal tensile testing machine (Shimadzu Corporation AGS-X 10kN) at a tensile speed of 2 mm / min.

[0227] The elongation was the elongation at fracture and was calculated using the following method. First, before the test, two lines were marked perpendicular to the length of the specimen at a distance of 50 mm from the center of the specimen. After the test, the fracture surfaces of the aluminum alloy foil were joined together and the distance between the marks was measured. The elongation (mm) was calculated by subtracting the gauge length (50 mm) from the distance between the marks, and the elongation (%) was obtained by dividing the elongation by the gauge length (50 mm).

[0228] ·Average grain size The surface of an aluminum alloy foil was electropolished using a mixed solution of 20% perchloric acid and 80% ethanol at a voltage of 20V. Subsequently, it was anodized in Barker's solution at a voltage of 30V. The crystal grains of the treated specimens were observed using an optical microscope. The average crystal grain size was calculated from the photographs taken using the sectioning method specified in JIS G0551.

[0229] L1 (HAGB length) / L2 (LAGB length) The foil surface was electropolished, and then the crystal orientation was analyzed using a SEM-EBSD apparatus to observe large-angle grain boundaries (HAGBs) with an orientation difference of 15° or more, and small-angle grain boundaries (LAGBs) with an orientation difference of 2° or more and less than 15°. Four fields of view were measured at a magnification of ×500 with a field of view size of 170 × 340 μm. The length of HAGBs (L1) and LAGBs (L2) per unit area within the field of view were determined, and their ratio was calculated. The calculated ratios, L1 / L2, are shown in Tables 3 and 4.

[0230] • Crystal orientation Copper direction is {112} <111> The R direction is {123} <634> The following orientations were designated as representative orientations. The orientation densities for each orientation were obtained by the following method: Incomplete pole figures for {111}, {200}, and {220} were measured by X-ray diffraction. Using these results, the crystal orientation distribution function (ODF) was determined, and the orientation densities for the Copper orientation and the R orientation were obtained.

[0231] ·Surface analysis The Mg concentration on the foil surface was estimated using XPS (X-ray Photoelectron Spectroscopy). Narrow spectra obtained from narrow-scan measurements in the surface region from the outermost surface to a depth of 8 nm were separated by waveform analysis, and the atomic concentrations of each element were quantified. For the quantification of Mg, the Mg2p spectrum was used. Details of the analytical conditions are as follows. Measurement device: ULVAC-FI PHI5000-VersaProbeIII Incident X-ray: Al Kα monochromatic X-ray, hν=1486.6ev X-ray source output: 100W, 20kV, 5.8mA Pass energy: 26 eV Step: 0.05eV Analysis area (beam diameter): 100μm x 1.4mm Detection angle: 45° Photoelectron capture angle: 45 degrees Measurement area: 100 μm in diameter, 1.4 mm in the X direction. Peak shift correction: Correction is performed so that the CC peak is 285.0 eV at the C1s peak. Charge neutralization: Charge neutralization using a dual beam of Ar ions and electron beams.

[0232] • Measurement of oxide film thickness The oxide film thickness was measured using an FE-EPMA (Electron Probe Micro Analyzer) instrument. The oxide film thickness of the sample was calculated using a calibration curve of X-ray intensity obtained from an oxide film sample with a known thickness. The FE-EPMA instrument used was a JEOL JXA-8530F. The analysis conditions were an acceleration voltage of 10kV, an irradiation current of 100nA, and a beam diameter of 50μm.

[0233] • Puncture strength of aluminum alloy foil For exterior components containing 40 μm thick aluminum alloy foil, a needle with a diameter of 1.0 mm and a tip radius of 0.5 mm was pierced at a speed of 50 mm / min. The maximum load (N) until the needle penetrated the foil was measured as the puncture strength. Here, a puncture strength of 9.0 N or higher was judged to be good puncture resistance and is indicated as "A" in Tables 3 and 4. A puncture strength of less than 9.0 N was judged to be poor puncture resistance and is indicated as "C" in Tables 3 and 4.

[0234] • Evaluation of corrosiveness to electrolyte Each aluminum alloy foil used in the examples and comparative examples was cut into a rectangle with a length of 45 mm × a width of 15 mm. Next, a rectangular polyethylene film with a length of 50 mm × a width of 20 mm was overlapped on the front and back surfaces of the aluminum alloy foil and heat-sealed and attached and coated so that an exposed portion with a diameter of 1 cm was formed on one of the front and back surfaces of the aluminum alloy foil, and a test sample was obtained. In addition, the evaluation of the corrosion resistance in the test sample was performed at the 1 cmφ portion where the aluminum alloy foil AL was exposed, and the end portion that was not immersed in the electrolytic solution of the test sample was exposed for connection to the working electrode. Next, the test sample AL was set as the working electrode, and metallic lithium Li (in the shape of a disk with a diameter of 15 mm × a thickness of 0.35 mm) was set as the counter electrode, and it was immersed in an electrolytic solution (composed of 1 mol / l of LiPF6 and a mixed solution of ethylene carbonate, diethyl carbonate, and dimethyl carbonate (volume ratio 1:1:1)). In this state, after applying a voltage of 0.1 V for 1 hour in an environment at 20°C, the surface of the aluminum alloy foil was observed. As shown in Fig. 3F(B), those with a corroded surface were evaluated as C, and as shown in Fig. 3F(A), those with no change were evaluated as A, and the results are shown in Tables 3 and 4. On the corroded surface of the aluminum alloy foil, a compound with lithium was generated, and it was observed that the surface swelled due to volume expansion.

[0235] · Corrosion resistance of aluminum alloy foil against all-solid electrolytes Inside the glove box, a solid electrolyte (Li2S-P2S5 (75:25)) with a thickness of 800 μm and a diameter of φ10 mm was prepared by compacting powder. Next, indium foils (thickness 0.3 mm·φ9 mm), lithium foils (thickness 0.2 mm·φ8 mm), and indium foils (thickness 0.1 mm·φ9 mm) were stacked on the solid electrolyte with the indium foil of 0.1 mm thickness facing the solid electrolyte side, constrained, and left overnight. Then, after releasing the constraint, each aluminum alloy foil used in the examples and comparative examples was punched out to φ9 mm and laminated on the solid electrolyte on the side opposite to the foil. The obtained laminate was constrained and encapsulated in a glass cell with leads. The laminate was taken out of the glove box and left for 1 hour to be stabilized. In this state, after applying a voltage of -0.53 V for 3 hours or 10 hours at 25°C, the electric charge per unit area was calculated. When the electric charge was less than 4 C / cm 2 it was evaluated as A, when it was 4 C / cm 2 it was evaluated as B, and when it exceeded 4 C / cm 2 it was evaluated as C. The results are shown in Tables 3 and 4.

[0236] · Evaluation of the followability of the exterior member Each exterior member obtained above was cut into a square with a length (MD) of 100 mm × width (TD) of 100 mm to make a test sample. This test sample was folded in two so that the heat-sealing resin layer was on the inside at the center in the width direction, and a rectangular double-folded sample with a length (MD) of 100 mm × width (TD) of 50 mm was created. This double-folded sample was sandwiched between two metal plates with a width of 200 mm × length of 200 mm × thickness of 15 mm, parallel to the width (TD) direction at the center in the length (MD) direction. The sandwiched sample was bent back and forth around 180°C, and the number of reciprocating folds until cracks appeared in the aluminum was measured. The cracks were confirmed by shining the light of an LED lamp. The evaluation was performed N = 5 times and the average value was calculated. When the number of occurrences of cracks was 10 or more, it was evaluated as A, and when it was less than 10, it was evaluated as C. The results are shown in Tables 3 and 4.

[0237] · Puncturing strength of the exterior member For each of the exterior components obtained above, the puncture strength was measured from the base material layer side using a method compliant with JIS Z1707:1997. Specifically, in a measurement environment of 23±2℃ and relative humidity (50±5)%, the test specimen was fixed with a 115mm diameter stand and a clamping plate with a 15mm opening in the center, and a semicircular needle with a diameter of 1.0mm and a tip radius of 0.5mm was inserted at a speed of 50±5mm per minute, and the maximum stress until the needle penetrated was measured. Five test specimens were used, and the average value was calculated. If there were not enough test specimens to measure five, the number of measurable specimens was measured, and the average value was calculated. The puncture strength measuring device used was the ZP-50N (force gauge) and MX2-500N (measuring stand) manufactured by IMADA Corporation. The results are shown in Tables 3 and 4. A puncture strength of 30N or higher was evaluated as A, and a puncture strength of 30N or lower was evaluated as C. The results are shown in Tables 3 and 4.

[0238] [Table 1]

[0239] [Table 2]

[0240] [Table 3]

[0241] [Table 4]

[0242] <Manufacturing of exterior components> A laminated film was prepared by sequentially laminating a polyethylene terephthalate film (12 μm) as the base layer, an adhesive layer (two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound), 3 μm thick), and a biaxially oriented nylon film (15 μm thick). Next, a barrier layer made of the aforementioned aluminum alloy foil (having the composition shown in Tables 1 and 2 and the properties shown in Tables 3 and 4, and 40 μm thick) with acid-resistant coatings formed on both sides was laminated on the biaxially oriented nylon film (15 μm thick) of the base layer by dry lamination. Specifically, the coatings on both sides were acid-resistant (a coating formed by chromate treatment, with a chromium content of 30 mg / m²). 2 A two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to one side of an aluminum alloy foil that had a frosted surface formed on it, forming an adhesive layer (3 μm thick after curing) on ​​the aluminum alloy foil. Next, a laminate of a base layer / adhesive layer / barrier layer was fabricated by laminating the adhesive layer on the aluminum alloy foil with a biaxially oriented nylon film and then performing an aging treatment. Next, a laminate of a base layer / adhesive layer / barrier layer was fabricated by co-extruding maleic anhydride-modified polypropylene (40 μm thick) as an adhesive layer and polypropylene (40 μm thick) as a heat-fusible resin layer onto the barrier layer of the obtained laminate. Next, the obtained laminate was aged and heated to obtain an exterior component in which polyethylene terephthalate film (12 μm) / adhesive layer (3 μm) / biaxially oriented nylon film (15 μm) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (40 μm) / heat-fusible resin layer (40 μm) were laminated in this order.

[0243] Furthermore, erucic acid amide was present as a lubricant on both sides of the exterior component to form a lubricant layer.

[0244] The exterior components of the energy storage devices in Examples 1-15 and 22-40 are each composed of a laminate comprising at least a base layer, a barrier layer, and a heat-fusible resin layer in that order, and the barrier layer contains aluminum alloy foil satisfying a composition of Fe: 0.2% to 2.0% by mass and Mg: 0.1% to 5.0% by mass. The exterior components of Examples 1-15 and 22-40 exhibit excellent conformability of the exterior component at corners and other areas, effectively suppress corrosion of the aluminum alloy foil when current is applied while electrolyte is present, and also possess high mechanical strength.

[0245] [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.

[0246] <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.

[0247] 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.

[0248] <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.

[0249] <5-3> In the above-described Embodiments 1-4, the second surface 140 is a plane that extends downward from the first surface 130 at a substantially right angle. However, the form of the second surface 140 is not limited to this. For example, consider a case where the electrode body 200 is a wound electrode body and a plane and a curved surface are formed on the outer periphery. Here, assume that the area of the plane is larger than the area of the curved surface, 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 constituted by a curved surface. In this case, the boundary portion where the second surface 140 extends downward from the first surface 130 will be the side 135.

[0250] <5-4> In the above-described Embodiment 3, the bonding regions 151 are formed at four locations. However, the number of locations where the bonding regions 151 are formed is not limited to this. For example, the bonding regions 151 may be formed only at two locations near both ends along the side 135, or at one location near the center of the side 135, or may be formed at five or more locations.

[0251] <5-5> In the above-described Embodiment 1, the electrode terminal 300 is disposed in the second sealing portion 120. However, in the exterior body 100, the position where the electrode terminal 300 is disposed is not limited to this. For example, as shown in FIG. 22, the electrode terminal 300 can also be disposed in the first sealing portion 110. In other words, the first sealing portion 110 is sealed in a state sandwiching the electrode terminal 300. In this modification, at least one of the two electrode terminals 300 may be bent toward the second surface 140 side, may be bent to the side opposite to the second surface 140, or may not be bent so as to protrude outward from the side 135. In this modification, since the electrode terminal 300 and the first sealing portion 110 can be easily sealed, the sealing property of the exterior body 100 is enhanced. Also, the electrode body 200 can be easily accommodated in the exterior body 100. In this modification, for example, as in the above-described Embodiment 2, the lid body 400 is fitted into each of the openings at both ends of the exterior member 101. The second sealing portion 120 is formed by heat-sealing the exterior member 101 and the lid body 400 in a state where the lid body 400 is fitted.

[0252] <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 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.

[0253] 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.

[0254] 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.

[0255] 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.

[0256] <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]

[0257] 10,10X,10XA,10Y,10Z Energy storage device, 100,100X,100Y Outer casing, 101,101Y,101Z1,101Z2 Outer casing member, 101A Base layer, 101C Barrier layer, 101D Heat-fusible resin layer, 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, 151 Joining area, 152 Space, 153 Unjoined area, 200 Electrode body, 210 Electrode, 215 Current collector, 300 Electrode terminal, 500A First surface, 500B 2nd side, 400,500,700 lid body, 610,710 metal part, C1 corner.

Claims

1. An exterior component for an energy storage device, The aforementioned energy storage device is Electrode body and The electrode body is enclosed by an outer casing, The exterior body is composed of the film-like exterior member, The outer casing includes a first sealing portion, a first surface, and a second surface, which are sealed by joining together surfaces that face each other when the outer casing member is wrapped around the electrode 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. The exterior component is composed of a laminate comprising, at least, a base layer, a barrier layer, and a heat-fusible resin layer in this order. The barrier layer comprises an aluminum alloy foil satisfying the composition of Fe: 0.2% by mass or more and 2.0% by mass or less, and Mg: 0.1% by mass or more and 5.0% by mass or less. The aluminum alloy foil is an exterior component in which the orientation density of the Copper orientation and R orientation of the texture is 15 or less.

2. The exterior member according to claim 1, wherein the aluminum alloy foil contains Mn: 0.10% by mass or less as an unavoidable impurity.

3. The exterior member according to claim 1 or 2, wherein the aluminum alloy foil contains Cu: 0.10% by mass or less as an unavoidable impurity.

4. The exterior member according to claim 1 or 2, wherein the composition of the aluminum alloy foil satisfies Mg: greater than 1.5% by mass and less than or equal to 5.0% by mass.

5. The exterior member according to claim 1 or 2, wherein the aluminum alloy foil contains aluminum and unavoidable impurities with respect to Fe and Mg, and the content of unavoidable impurities other than Fe, Mg, and Al in the aluminum alloy foil is 0.10% by mass or less individually and 0.40% by mass or less in total.

6. The remainder further contains Si, in addition to the unavoidable impurities. The exterior member according to claim 5, wherein the composition of the aluminum alloy foil satisfies a composition of Si: 0.5% by mass or less.

7. The exterior member according to claim 1 or 2, wherein the aluminum alloy foil has an average crystal grain size of 25 μm or less.

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