Power storage device and method for manufacturing power storage device

Abstract

Provided is a power storage device capable of preventing external short circuit and a method for manufacturing the power storage device. The power storage device includes an exterior body. The exterior body is a pair of laminate structures configured to sandwich a power storage layer stack from both sides in a thickness direction, the pair of laminate structures being composed of a first sealing substrate, a first aluminum member, and a first resin member, at least one of the first resin member and the first sealing substrate being composed of two or more resin layers, an inner resin layer closer to the first aluminum member having a higher melting point than an outer resin layer farther from the first aluminum member, and the first aluminum member in an end portion of the exterior body being covered by the inner resin layer.

Description

Technical Field

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

[0002] Patent Document 1 discloses a bipolar battery technology having a pair of sheet-like structures configured to hold an energy storage module from both sides in the thickness direction within an internally housed outer casing. In this technology, the sheet-like structures have metal sheets electrically connected to the energy storage module and laminates whose inner surfaces are joined to the sides of the metal sheets in a manner that surrounds the metal sheets. The outer peripheries of the laminates are directly or indirectly connected to each other.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2024-42569 Summary of the Invention

[0004] In Patent Document 1, the metal sheet of the barrier layer is exposed at the end of the laminate, thus posing a potential risk of external short circuit through the exposed portion of the metal sheet, and there is room for improvement. In particular, in bipolar batteries, the voltage of the energy storage module is higher, so countermeasures against external short circuits are important.

[0005] The present invention was made in view of the above circumstances, and its object is to provide an energy storage device and a method for manufacturing the energy storage device that can prevent external short circuits.

[0006] The present invention relates to an energy storage device comprising: an energy storage laminate module having a plurality of electrodes laminated along a first direction; and an outer casing housing the energy storage laminate module, wherein the outer casing is a pair of laminated structures configured to clamp the energy storage laminate module from both sides in the thickness direction, the pair of laminated structures comprising a substrate layer, a barrier layer, and a sealing layer, wherein at least one of the substrate layer and the sealing layer comprises two or more resin layers, the melting point of the inner resin layer near the barrier layer is higher than the melting point of the outer resin layer away from the barrier layer, and the barrier layer at the end of the outer casing is covered by the inner resin layer.

[0007] Furthermore, the present invention relates to a method for manufacturing an energy storage device, the energy storage device comprising: an energy storage laminate module having a plurality of electrodes laminated along a first direction; and an outer casing for accommodating the energy storage laminate module, wherein the outer casing is a laminated structure configured to clamp the energy storage laminate module from both sides in the thickness direction, the laminated structure comprising a substrate layer, a barrier layer, and a sealing layer, at least one of the substrate layer and the sealing layer being composed of two or more resin layers, the melting point of the inner resin layer near the barrier layer being higher than the melting point of the outer resin layer away from the barrier layer, the method for manufacturing the energy storage device comprising the following steps: a first step of hot-pressing the end of the outer casing at a melting point above the inner resin layer; and a second step of hot-compressing the outer casing at a melting point above the outer resin layer and below the melting point of the inner resin layer when accommodating the energy storage laminate module.

[0008] Invention Effects

[0009] According to the present invention, it can prevent external short circuits. Attached Figure Description

[0010] Figure 1 This is a cross-sectional view showing the schematic structure of an energy storage device module according to an embodiment of the present invention.

[0011] Figure 2 It is magnification Figure 1 An enlarged view of the cross-section at the end of region D1.

[0012] Figure 3 This is a schematic diagram illustrating a manufacturing method for pre-welding in the end of a first outer casing according to an embodiment of the present invention.

[0013] Figure 4 This is a schematic diagram illustrating a manufacturing method for welding at the end of an outer casing according to an embodiment of the present invention. Detailed Implementation

[0014] Hereinafter, the energy storage device and its manufacturing method according to embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, the drawings referred to in the following description only schematically show the shape, size, and positional relationships to a degree sufficient for understanding the content of the present invention. That is, the present invention is not limited to the shapes, sizes, and positional relationships illustrated in the drawings. In addition, in the description of the drawings, the same parts are labeled with the same symbols. Each drawing includes an X-axis, Y-axis, and Z-axis.

[0015] [Overview of Energy Storage Lamination Module]

[0016] Figure 1This is a cross-sectional view showing the schematic structure of a battery storage stacked module according to an embodiment of the present invention. Figure 1 The energy storage device 1 shown is used, for example, in batteries for various vehicles such as forklifts, hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs). The energy storage device 1 is, for example, a nickel-metal hydride secondary battery or a lithium-ion secondary battery. Alternatively, the energy storage device 1 can be an electric double-layer capacitor or an all-solid-state battery. The following description explains the application of the energy storage device 1 to a lithium-ion secondary battery.

[0017] The energy storage device 1 includes: an energy storage stacked module 3, on which a plurality of electrode bodies 2 are stacked along a first direction; and an outer casing 4, which houses the energy storage stacked module 3 inside by clamping the energy storage stacked module 3 from both sides of the first direction.

[0018] [Structure of the energy storage cascade module]

[0019] First, the structure of the energy storage stacked module 3 will be explained.

[0020] The energy storage stacked module 3 includes: a stacked body 5, formed by stacking multiple electrode bodies 2 (energy storage units) along the stacking direction, i.e., the first direction (Z direction); and a sealing part 6, which seals the periphery of the stacked body 5. Figure 1 In this text, the stacking direction of electrode body 2 is described as the Z direction. Furthermore, in... Figure 1 In this document, the direction of the plane orthogonal to the stacking direction of electrode body 2 will be used as the X-axis direction and Y-axis direction for explanation.

[0021] [Structure of laminated bodies]

[0022] First, the structure of the laminate 5 will be described. The laminate 5 is composed of multiple electrode bodies 2 stacked together, which function as a bipolar battery. Each electrode body 2 includes a current collector 21, a positive electrode 22, a negative electrode 23, and a separator 24.

[0023] The current collector 21 (electrode plate) is, for example, a rectangular sheet shape. The current collector 21 is a chemically inert conductor used to continuously allow current to flow through the positive electrode 22 and negative electrode 23 (described later) during the discharge or charging of the lithium-ion secondary battery. Materials constituting the current collector 21 can include, for example, metallic materials, conductive resin materials, and conductive inorganic materials. Examples of conductive resin materials include resins in which conductive or non-conductive polymer materials have conductive fillers added as needed. The current collector 21 can be composed of one or more layers containing the aforementioned metallic material or conductive resin material. The surface of the current collector 21 can be covered with a known protective layer, for example, by a known method such as electroplating. Furthermore, the current collector 21 can be, for example, a foil, sheet, film, wire, rod, mesh, or covering material. In addition to aluminum foil and copper foil, the current collector 21 can also be, for example, a metal foil such as nickel foil, titanium foil, or stainless steel foil. In this case, from the viewpoint of ensuring mechanical strength, stainless steel foil is preferably used for the current collector 21. Of course, the current collector 21 can be a metal alloy foil or a foil comprising a substrate covered with an aluminum film. Alternatively, in one embodiment, the current collector 21 will be described as an aluminum foil or a copper foil. When using a foil-shaped current collector 21, the thickness of the current collector 21 is preferably in the range of 1 μm to 100 μm.

[0024] The positive electrode 22 is a layer of positive electrode active material disposed on one side (back side) of the current collector 21 along the first direction. The positive electrode 22 is, for example, a rectangular electrode.

[0025] The negative electrode 23 is a layer of negative electrode active material disposed along the first direction on the other side (surface) of the current collector 21. The negative electrode 23 is, for example, a rectangular electrode. Furthermore, the negative electrode 23 is formed to be slightly larger than the positive electrode 22, so that the entire formation area of ​​the positive electrode 22 is located on top of it when viewed from above. In a single laminate 5, the negative electrode 23 (negative electrode active material layer) and the positive electrode 22 (positive electrode active material layer) are laminated via a separator 24 in a manner where the negative electrode 23 (negative electrode active material layer) and the positive electrode 22 (positive electrode active material layer) are opposite each other. The lamination direction of the negative electrode 23 and the positive electrode 22 is consistent with the lamination direction of the laminate 5 (Z-axis direction). Hereinafter, the lamination direction of the laminate 5 and the lamination directions of the positive electrode 22 and the negative electrode 23 will be simply referred to as the "lamination direction" for explanation.

[0026] The laminated body 5 thus constructed is formed by stacking multiple electrode bodies 2 in the stacking direction, such that the positive electrode 22 (positive electrode active material layer) of one electrode body 2 overlaps with the other side of the negative electrode 23 (negative electrode active material layer) of another electrode body 2 adjacent in the stacking direction via a separator 24. Therefore, the multiple electrode bodies 2 in the laminated body 5 are electrically connected in series. That is, the laminated body 5 forms a simulated bipolar battery by forming positive electrodes 22 and negative electrodes 23 in contact with each other on adjacent electrode bodies 2 in the stacking direction. Furthermore, the laminated body 5 has a positive terminal electrode 25 at one end (upper side) in the stacking direction, which is a terminal electrode of the energy storage stacked module 3 and has a negative terminal electrode 26 at the other end (lower side) in the stacking direction, which is a terminal electrode of the energy storage stacked module 3 and has a negative terminal electrode 26. The positive terminal electrode 25 and the negative terminal electrode 26 are formed by stacking them on the electrode bodies 2 via separators 24.

[0027] Furthermore, the positive electrode active material layer used in the positive electrode 22 contains an active material capable of absorbing and releasing charge carriers such as lithium ions. As the positive electrode active material layer, materials suitable for lithium-ion secondary batteries, such as lithium composite metal oxides with a layered rock salt structure, spinel-structured metal oxides, and polyanionic compounds, can be used. Moreover, the positive electrode active material layer can use two or more materials. In one embodiment, the positive electrode active material layer may contain olivine-type lithium iron phosphate as a composite oxide.

[0028] Furthermore, the negative electrode active material layer used in the negative electrode 23 can be a monomer, alloy, or compound capable of absorbing and releasing charge carriers such as lithium ions. For example, as the negative electrode active material layer, Li, carbon, metal compounds, elements or compounds capable of alloying with lithium can be used. As carbon, natural graphite, artificial graphite, hard carbon (difficult-to-graphitize carbon), or soft carbon (easily-graphitize carbon) can be used. Furthermore, as artificial graphite, highly oriented graphite, mesophase carbon microspheres, etc., can be used. As elements capable of alloying with lithium, silicon (Si) and tin can be used. In addition, in one embodiment, the negative electrode active material layer may include graphite as a carbon-based material.

[0029] The positive electrode active material layer and the negative electrode active material layer (hereinafter referred to as "active material layer") may, as needed, include conductive additives, binders, electrolytes (polymer matrix, ion-conducting polymer, electrolyte, etc.), and electrolyte support salts (lithium salts) for improving ion conductivity. The components contained in the active material, their proportions, and the thickness of the active material are not particularly limited, and conventional knowledge regarding lithium-ion secondary batteries can be appropriately used. The thickness of the layer formed by the active material is, for example, 2 to 150 μm. Conventional methods such as roll-to-roll coating can be used to form the active material layer on the surface of the electrode plate. To improve the thermal stability of the positive electrode 22 or the negative electrode 23, a heat-resistant layer may be provided on the surface of the electrode plate (one side or both sides) or on the surface of the active material layer. This heat-resistant layer may, for example, contain inorganic particles and binders, and may also contain additives such as thickeners.

[0030] Conductive additives are added to the positive electrode 22 or the negative electrode 23 to improve their conductivity. Therefore, conductive additives can be added arbitrarily if the conductivity of the positive electrode 22 or the negative electrode 23 is insufficient, or they can be omitted if the conductivity of the positive electrode 22 or the negative electrode 23 is sufficiently excellent. Examples of conductive additives include acetylene black, carbon black, and graphite.

[0031] The binder serves to fix active materials or conductive additives to the surface of the electrode plate. As binders, fluorinated resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber; thermoplastic resins such as polypropylene and polyethylene; imide resins such as polyimide and polyamide-imide; alkoxysilyl resins; acrylic resins containing monomer units such as acrylic acid or methacrylic acid; styrene-butadiene rubber (SBR); carboxymethyl cellulose; alginates such as sodium alginate and ammonium alginate; water-soluble cellulose ester crosslinkers; and starch-acrylic acid graft polymers can be used. These binders can be used alone or in combination. Solvents such as water and N-methyl-2-pyrrolidone (NMP) can also be used.

[0032] The separator 24 isolates the positive electrode 22 and the negative electrode 23, preventing short circuits due to contact between the two electrodes, while allowing charge carriers such as lithium ions to pass through. The separator 24 is disposed between the positive electrode 22 and the negative electrode 23 in one electrode body 2. Furthermore, when the electrode bodies 2 are stacked along the stacking direction, the separator 24 prevents short circuits between adjacent bipolar cells in the stacking direction.

[0033] The diaphragm 24 can be constructed, for example, using a porous sheet or nonwoven fabric containing a polymer that absorbs and retains the electrolyte. As a material constituting the diaphragm 24, a porous membrane made of polypropylene (PP) can be used, for example. Alternatively, the material constituting the diaphragm 24 can be a woven or nonwoven fabric made of polypropylene or methylcellulose. Furthermore, the diaphragm 24 can be a single-layer or multi-layer structure. A multi-layer structure can be, for example, a ceramic layer as a heat-resistant layer. In addition, the diaphragm 24 can be impregnated with an electrolyte. The diaphragm 24 itself can also be composed of an all-solid electrolyte (polymer solid electrolyte, inorganic solid electrolyte, etc.).

[0034] As the electrolyte impregnated in the diaphragm 24, conventionally known materials can be used, such as liquid electrolytes (electrolytes) and polymeric gel electrolytes. Electrolytes comprise a non-aqueous solvent and an electrolyte dissolved in the non-aqueous solvent. Polymeric gel electrolytes comprise an electrolyte retained within a polymer matrix.

[0035] The electrolyte comprises a non-aqueous solvent and an electrolyte dissolved in the non-aqueous solvent. As the non-aqueous solvent, known solvents such as cyclic carbonates, cyclic esters, chain carbonates, chain esters, and ethers can be used. Furthermore, these materials can be used alone or in combination of two or more. As the electrolyte, known lithium salts can be used.

[0036] [Structure of the sealing part]

[0037] Next, the structure of the sealing part 6 will be described. The sealing part 6 includes a spacer 61, a sealing member 62, and a welding part 63.

[0038] Spacer 61 is disposed between each of the plurality of sealing members 62 and is joined or fixed to diaphragm 24. Spacer 61 contains insulating material to prevent short circuits by insulating the positive electrode 22 and the negative electrode 23. Spacer 61 is a frame formed to surround the positive electrode 22 and the negative electrode 23 when viewed from the stacking direction. Furthermore, spacer 61 functions as part of a sealing portion 6 that seals the space between the positive electrode 22 and the negative electrode 23. In one embodiment, spacer 61 is disposed between a pair of current collectors 21 and between sealing members 62. Specifically, spacer 61 has: a portion disposed between a pair of electrode plates; and a portion extending outward beyond the edges of the pair of electrode plates and disposed between sealing members 62.

[0039] The spacer 61 is constructed using polyethylene (PE) as a resin as an insulating material. In addition to polyethylene (PE), polystyrene, ABS resin, modified polypropylene (modified PP), and acrylonitrile styrene (AS) resin can also be used as the resin material constituting the spacer 61.

[0040] The sealing member 62 seals the periphery of the laminate 5. The sealing member 62 is disposed on the outer peripheral surface of the laminate 5. The sealing member 62 is formed by clamping at least one of the positive electrode 22 and the negative electrode 23 from the lamination direction. The sealing member 62 is constructed using an insulating component. Specifically, the sealing member 62 can be made of silicone rubber, polyolefin, or polyurethane rubber, etc.

[0041] The welded portion 63 is formed by welding and fixing the spacer 61 and the sealing member 62 from the stacking direction by means of a hot press head or the like. For example, the welded portion 63 is formed by welding and fixing a predetermined length from the outer edge of the spacer 61 and the sealing member 62 toward the inner side.

[0042] In the energy storage module 3 thus constructed, the electrolyte (electrolyte) impregnated in the diaphragm 24 is contained within the space formed by the positive electrode 22, the negative electrode 23, the diaphragm 24, and the sealing portion 6. That is, the energy storage module 3 seals the space between the positive electrode 22 and the negative electrode 23 by the sealing portion 6, preventing electrolyte leakage and preventing moisture from entering the space between the positive electrode 22 and the negative electrode 23.

[0043] [Structure of the outer casing]

[0044] Next, the outer casing 4 will be described in detail. The outer casing 4 has: a first outer casing 41 and a second outer casing 42, which are arranged to clamp the energy storage laminate 3 from both sides in the first direction and house the energy storage laminate 3 inside; and an end portion 43, which is formed by joining the first outer casing 41 and the second outer casing 42. That is, the end portion 43 is formed by joining the peripheral portion of the first outer casing 41 and the peripheral portion of the second outer casing 42 using heat pressing or the like, as described later.

[0045] The first outer casing 41 includes: a first conductive plate 411; a first lower insulating component 412; a first sealing substrate 413 (sealing layer); a first aluminum component 414 (barrier layer); a first resin component 415 (substrate layer); and a first upper insulating component 416. Furthermore, the first outer casing 41 is constructed using a laminated sheet with a laminated structure consisting of the first sealing substrate 413, the first aluminum component 414, and the first resin component 415. That is, the first outer casing 41 is a laminated sheet constructed by sequentially stacking the first resin component 415, the first aluminum component 414, and the first sealing substrate 413.

[0046] The first conductive plate 411 is stacked in contact with the outermost positive terminal electrode 25 disposed in the first direction of the energy storage stack module 3, and is electrically connected to the energy storage stack module 3. The first conductive plate 411 is in direct contact with the surface of the current collector 21 where no active material layer is formed, and is thus conductive to extract current from the energy storage stack module 3. Furthermore, when multiple energy storage devices 1 are stacked along the first direction to form a battery pack, the first conductive plate 411 electrically connects the multiple energy storage devices 1 by distributing a conductive plate or conductive adhesive between two adjacent energy storage devices 1 along the first direction.

[0047] The first lower insulating component 412 extends further inward than the first resin component 415 (substrate layer) into the energy storage device 1 and is bonded to the first conductive plate 411. The first lower insulating component 412 is made of a weldable resin. The first lower insulating component 412 is made of an acid-modified resin, such as an acid-modified polyolefin resin.

[0048] The first sealing substrate 413, the first aluminum component 414 and the first resin component 415 are respectively formed in an L-shape to cover the energy storage laminate module 3 via the first conductive plate 411 and the first insulating lower component 412, and extend along the direction of the plane orthogonal to the first direction (X direction) to form a part of the end 43.

[0049] The first sealing substrate 413 is constructed using resin components with different melting points. For example, the first sealing substrate 413 may be constructed using resin components with different melting points, such as acid-modified polyolefin or other resins such as polyolefin and nylon. The first aluminum component 414 is constructed using aluminum foil. The first resin component 415 is constructed using resin components with different melting points. For example, the first resin component 415 may be constructed using resin components with different melting points, such as acid-modified polyolefin or other resins such as polyolefin and nylon.

[0050] The first upper insulating component 416 is bonded to the first sealing substrate 413 (sealing layer) and the first lower insulating component 412, and is formed to cover the other ends of the first sealing substrate 413 (sealing layer), the first aluminum component 414 (barrier layer), and the first resin component 415 (substrate layer) that are different from the end 43. That is, the first upper insulating component 416, the first sealing substrate 413, the first aluminum component 414, and the first resin component 415 are bonded to the first conductive plate 411 via the first lower insulating component 412. Furthermore, the first upper insulating component 416 is made of a weldable resin. The first upper insulating component 416 is made of an acid-modified resin, such as an acid-modified polyolefin resin.

[0051] The second outer casing 42 includes: a second conductive plate 421; a second lower insulating component 422; a second sealing substrate 423 (sealing layer); a second aluminum component 424 (barrier layer); a second resin component 425 (substrate layer); and a second upper insulating component 426. Furthermore, the second outer casing 42 is constructed using a laminated sheet with a laminated structure consisting of the second sealing substrate 423, the second aluminum component 424, and the second resin component 425. That is, the second outer casing 42 is a laminated sheet constructed by sequentially stacking the second resin component 425, the second aluminum component 424, and the second sealing substrate 423.

[0052] The second conductive plate 421 is stacked in contact with the outermost negative terminal electrode 26 disposed in the first direction of the energy storage stack module 3, and is electrically connected to the energy storage stack module 3. The second conductive plate 421 is in direct contact with the surface of the current collector 21 where no active material layer is formed, and is thus conductive to extract current from the energy storage stack module 3. Furthermore, when multiple energy storage devices 1 are stacked along the first direction to form a battery pack, the second conductive plate 421 electrically connects the multiple energy storage devices 1 by distributing a conductive plate or conductive adhesive between two adjacent energy storage devices 1 along the first direction.

[0053] The second lower insulating component 422 extends further inward than the second resin component 425 (substrate layer) into the energy storage device 1 and is bonded to the second conductive plate 421. The second lower insulating component 422 is made of a weldable resin. The second lower insulating component 422 is made of an acid-modified resin, such as an acid-modified polyolefin resin.

[0054] The second sealing substrate 423, the second aluminum component 424 and the second resin component 425 are respectively formed in an L-shape to cover the energy storage laminate module 3 via the second conductive plate 421 and the second insulating lower component 422, and extend along the direction of the plane orthogonal to the first direction (X direction) to form a part of the end 43.

[0055] The second sealing substrate 423 is constructed using resin components with different melting points. For example, the second sealing substrate 423 may be constructed using resin components with different melting points, such as acid-modified polyolefin or other resins like polyolefin and nylon. The second aluminum component 424 is constructed using aluminum foil. The second resin component 425 is constructed using resin components with different melting points. For example, the second resin component 425 may be constructed using resin components with different melting points, such as acid-modified polyolefin or other resins like polyolefin and nylon.

[0056] The second upper insulating component 426 is bonded to the second sealing substrate 423 (sealing layer) and the second lower insulating component 422, and is formed to cover the other ends of the second sealing substrate 423 (sealing layer), the second aluminum component 424 (barrier layer), and the second resin component 425 (substrate layer) that are different from the end 43. That is, the second upper insulating component 426, the second sealing substrate 423, the second aluminum component 424, and the second resin component 425 are respectively bonded to the second conductive plate 421 via the second lower insulating component 422. Furthermore, the second upper insulating component 426 is made of a weldable resin. The second upper insulating component 426 is made of an acid-modified resin, such as an acid-modified polyolefin resin.

[0057] In the end 43, the first aluminum component 414 and the second aluminum component 424, which serve as a barrier layer, are covered by the first resin component 415 and the second resin component 425, which serve as an inner resin layer.

[0058] [Intersection at the end]

[0059] Here, the cross-section of end 43 will be described in detail. Figure 2 It is magnification Figure 1 An enlarged view of the cross section at end 43 in region D1.

[0060] like Figure 2 As shown, the first sealing substrate 413 and the first resin component 415 are composed of two or more resin layers. Specifically, the first sealing substrate 413 has a first layer 413a and a second layer 413b. A resin component is used, in which the first layer 413a, which functions as an inner resin layer near the first aluminum component 414 (serving as a barrier layer), has a higher melting point than the second layer 413b, which functions as an outer resin layer away from the first aluminum component 414. Similarly, the first resin component 415 has a first layer 415a and a second layer 415b. A resin component is used, in which the first layer 415a, which functions as an inner resin layer near the first aluminum component 414 (serving as a barrier layer), has a higher melting point than the second layer 415b, which functions as an outer resin layer away from the first aluminum component 414. Here, the first layer 413a and the first layer 415a are constructed using resin components of polyethylene or polypropylene, and the second layer 413b and the second layer 415b are constructed using resin components such as nylon.

[0061] And, as Figure 2As shown, the second sealing substrate 423 and the second resin component 425 are composed of two or more resin layers. Specifically, the second sealing substrate 423 has a first layer 423a and a second layer 423b. A resin component is used, in which the first layer 423a, which functions as an inner resin layer near the second aluminum component 424 (serving as a barrier layer), has a higher melting point than the second layer 423b, which functions as an outer resin layer away from the second aluminum component 424. Similarly, the second resin component 425 has a first layer 425a and a second layer 425b. A resin component is used, in which the first layer 425a, which functions as an inner resin layer near the second aluminum component 424 (serving as a barrier layer), has a higher melting point than the second layer 425b, which functions as an outer resin layer away from the second aluminum component 424. Here, the first layer 423a and the first layer 425a are constructed using resin components of polyethylene or polypropylene, and the second layer 423b and the second layer 425b are constructed using resin components such as nylon.

[0062] In the end portion 43 thus configured, the first aluminum component 414 and the second aluminum component 424, which serve as barrier layers, are covered by covering portions 417 and 427 formed by the first layer 413a, the first layer 415a, the first layer 423a, and the first layer 425a, which serve as inner resin layers, through a heat-pressing process described later. Furthermore, in the end portion 43, the second layer 415b of the first resin component 415 and the second layer 425b of the second resin component 425 are integrally formed through a heat-pressing process described later, serving as a joint portion 44 for joining the first outer casing 41 and the second outer casing 42. Thus, in the energy storage device 1, the first resin component 415 and the second resin component 425, which serve as insulators, cover the first aluminum component 414 and the second aluminum component 424, which serve as barrier layers, thereby preventing external short circuits.

[0063] [Manufacturing method of the end portion in the outer casing]

[0064] Next, the manufacturing method of the outer casing 4 (hereinafter referred to as "this manufacturing method") will be described. Furthermore, while the energy storage device 1 is manufactured using conventionally known techniques, the manufacturing method of the end portion 43 in the outer casing 4 is different. Therefore, the manufacturing method of the end portion 43 in the outer casing 4 will be described below.

[0065] Figure 3 This is a schematic diagram illustrating the outline of a manufacturing method for pre-welding in the end 43 of the first outer casing 41. Additionally, in Figure 3 The end 43 of the first outer body 41 will be described in detail, but the end 43 of the second outer body 42 is also manufactured using the same method, so detailed description is omitted.

[0066] like Figure 3As shown, in this manufacturing method, the first step is performed where, with the first resin component 415, the first aluminum component 414, and the first sealing substrate 413 stacked, the end 43 (region D2) is hot-pressed with the first layer 413a and the first layer 415a (which are inner resin layers) at a melting point above the high melting point to form a covering portion 417 covering the end of the first aluminum component 414. Figure 3 (a) → Figure 3 (b) Thus, the end of the first aluminum component 414 can be covered by the covering part 417.

[0067] Next, the welding of the first outer casing 41 and the second outer casing 42 will be described. Figure 4 This is a schematic diagram illustrating the outline of the manufacturing method of welding at the end 43 of the outer body 4.

[0068] like Figure 4 As shown, in this manufacturing method, a second step is performed to heat-press the ends 43 (region D3) of the first outer body 41 and the second outer body 42 with a melting point above the low melting point of the second layer 415b and the second layer 425b, and a melting point below the high melting point of the first layer 413a and the first layer 415a. Figure 4 (a) → Figure 4 (b) Thus, the first outer casing 41 and the second outer casing 42 are integrally formed into a joint 44. This allows the first outer casing 41 and the second outer casing 42 to be welded together without exposing the ends of the pre-welded and covered first aluminum component 414 and second aluminum component 424. Furthermore, while the energy storage device 1 with a bipolar battery requires a higher resistance at the end 43 than conventional batteries, the thickness of the protective film at the end 43 can be easily adjusted by changing the thickness in the first direction of the first layer 413a and 415a, and the first layer 423a and 425a, which serve as inner resin layers.

[0069] According to one embodiment described above, in the end 43, the first aluminum component 414 and the second aluminum component 424, which serve as a barrier layer, are covered by the covering portions 417 and 427 formed by the first layer 413a, the first layer 415a, the first layer 423a and the first layer 425a, which serve as inner resin layers, by heat pressing, thereby preventing external short circuits.

[0070] (Other implementation methods)

[0071] Further effects or variations can be readily derived by those skilled in the art. The invention is not limited to the specific details and representative embodiments described above. Therefore, various modifications can be made without departing from the spirit or scope of the general invention as defined by the appended claims and their equivalents.

[0072] The above description, based on the accompanying drawings, details several embodiments of the present application. However, these are merely illustrative examples. Based on the methods described in the disclosure section of this invention, various modifications and improvements can be implemented in other ways based on the knowledge of those skilled in the art.

[0073] Symbol Explanation

[0074] 1-Energy storage device, 2-Electrode body, 3-Energy storage stacked module, 4-Outer body, 5-Laminated body, 6-Sealing part, 41-First outer body, 42-Second outer body, 43-End, 44-Joint part, 411-First conductive plate, 412-First lower insulating component, 413-First sealing substrate, 414-First aluminum component, 415-First resin component, 416-First upper insulating component, 417-Covering part, 421-Second conductive plate, 422-Second lower insulating component, 423-Second sealing substrate, 424-Second aluminum component, 425-Second resin component, 426-Second upper insulating component, 427-Covering part.

Claims

1. An energy storage device, comprising: A battery storage module having multiple electrodes stacked along a first direction; and The outer casing houses the energy storage stack-up module. The energy storage device is characterized in that... The outer casing is a pair of laminated structures configured to clamp the energy storage module from both sides in the thickness direction. The pair of laminated structures consists of a substrate layer, a barrier layer, and a sealing layer. At least one of the substrate layer and the sealing layer is composed of two or more resin layers. The melting point of the inner resin layer closer to the barrier layer is higher than that of the outer resin layer farther from the barrier layer. The barrier layer at the end of the outer casing is formed by the inner resin layer.

2. The energy storage device according to claim 1, characterized in that, The pair of laminated structures have a joint, which is joined by thermoforming the sealing layer at the end of the outer body.

3. A method for manufacturing an energy storage device, the energy storage device comprising: A battery storage module having multiple electrodes stacked along a first direction; and The outer casing houses the energy storage stack-up module. The method for manufacturing the energy storage device is characterized by the following: The outer casing is a laminated structure configured to clamp the energy storage module from both sides in the thickness direction. The laminated structure consists of a substrate layer, a barrier layer, and a sealing layer. At least one of the substrate layer and the sealing layer is composed of two or more resin layers. The melting point of the inner resin layer near the barrier layer is higher than that of the outer resin layer far from the barrier layer. The manufacturing method of the energy storage device includes the following steps: In the first step, the ends of the outer casing are heat-pressed together at a point above the melting point of the inner resin layer; and In the second step, when accommodating the energy storage stacked module, the outer casing is thermally compressed at a temperature above the melting point of the outer resin layer and below the melting point of the inner resin layer.

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