JP7240824B2 - Deep-drawn molded case for exterior of power storage device and power storage device - Google Patents

Description

For example, the present invention can be used for electric tools, vehicles, regenerative energy recovery, digital cameras, storage batteries (lithium ion secondary batteries, etc.), capacitors, all-solid batteries, etc. The present invention relates to a deep-drawn case used as an exterior material for an electric storage device.

In this specification and the scope of claims, the term "deep drawing" means "in the drawing of press forming, the corresponding part of the wrinkle suppressing surface on the outer periphery of the workpiece is also drawn into the hole of the die. It means "molding to".

In recent years, along with the thinning and weight reduction of mobile electric devices such as smartphones and tablet terminals, the demand for power storage devices such as lithium-ion secondary batteries, lithium-polymer secondary batteries, lithium-ion capacitors, and electric double layer capacitors mounted on these devices has increased. Instead of conventional metal cans, the exterior material is a laminate consisting of a heat-resistant resin layer (base layer) / outer adhesive layer / metal foil layer / inner adhesive layer / heat-fusible resin layer (inner layer). body is used (see Patent Document 1). In addition, power sources for electric vehicles, large power sources for power storage, capacitors, and the like are also increasingly being sheathed with the above-described laminated body (exterior material).

By subjecting the exterior material to stretch molding or deep drawing, the exterior material is molded into a three-dimensional shape such as a substantially rectangular parallelepiped shape. By molding into such a three-dimensional shape, it is possible to secure a housing space for housing the electricity storage device main body. Then, the power storage device main body is accommodated in the accommodation recess of the molding case molded into a three-dimensional shape, and the planar exterior material is overlaid with the inner layer side facing the molding case, and the inner side of the planar exterior material. A power storage device such as a battery is constructed by heat-sealing and sealing the peripheral edge portion of the layer and the inner layer of the sealing peripheral edge portion (flange portion) of the molding case.

JP 2003-288865 A

However, in an electric storage device that is covered with a molded case formed by deep-drawing the outer covering material having the above-described layer structure, the electrolyte may easily leak over time. The leakage of the electrolytic solution is mainly caused by the occurrence of pinholes or the like in the molded case after deep drawing. The present inventor has completed the present invention as a result of intensive research to solve the above-mentioned problems in such a deep-drawn case for exterior of an electric storage device.

The present invention has been made in view of the above technical background, and is a deep drawing for the exterior of an electricity storage device that is less likely to cause pinholes or the like in the molded case even with the passage of time and can prevent the occurrence of electrolyte leakage. It is an object of the present invention to provide a molded case and an electricity storage device.

In order to achieve the above object, the present invention provides the following means.

[1] A deep-drawn case for an exterior material comprising a heat-resistant resin layer as an outer layer, a heat-fusible resin layer as an inner layer, and a metal foil layer disposed between these layers, ,
The deep drawn case has a housing case capable of housing the electricity storage device main body, and a sealing peripheral edge portion extending outward in a substantially horizontal direction from the periphery of the opening on the lower surface of the housing case. It has a three-dimensional shape, and the top surface shape of the storage case is a substantially polygonal shape with a square or more,
In a cross-sectional view of the deep-drawn case cut along a vertical plane passing through any two non-adjacent corners of the top surface of the storage case, the thickness of the side surface of the deep-drawn case is "b ₁ " ( μm), the thickness of the first corner portion connecting the top surface and the side surface is “a ₁ ” (μm), and the thickness of the second corner portion connecting the sealing peripheral edge portion and the side surface is When "c ₁ " (μm),
b ₁ >c ₁ >a ₁ Formula (1)
c ₁ >b ₁ >a ₁ Formula (2)
_b1 = _c1 > _a1 ... Formula (3)
While satisfying any one of the three relational expressions of the above formulas (1), (2) and (3),
In a cross-sectional view of the storage case cut along a vertical plane passing through two non-adjacent corners of the top surface, the thickness of the metal foil layer forming the top surface is defined as "d ₃ " (μm). , wherein the value of _d3 / _e3 is 0.70 or more, where " _e3 " (μm) is the thickness of the metal foil layer forming the peripheral portion for sealing. Deep-drawn case for .

[2] A deep-drawn case for an exterior material comprising a heat-resistant resin layer as an outer layer, a heat-fusible resin layer as an inner layer, and a metal foil layer disposed between these layers, ,
The deep drawn case has a housing case capable of housing the electricity storage device main body, and a sealing peripheral edge portion extending outward in a substantially horizontal direction from the periphery of the opening on the lower surface of the housing case. It has a three-dimensional shape, and the top surface shape of the storage case is a substantially polygonal shape with a square or more,
A heat-sealable resin layer forming a side surface of the deep-drawn case in a cross-sectional view of the deep-drawn case cut along a vertical plane passing through any two corners that are not adjacent to each other on the top surface of the storage case. _The thickness of the heat-fusible resin layer constituting the first corner connecting the top surface and the side surface is "a ₂ " (μm), and the sealing When the thickness of the heat-fusible resin layer constituting the second corner portion connecting the fixing peripheral edge portion and the side surface is defined as "c ₂ " (μm),
b ₂ >c ₂ >a ₂ (4)
c ₂ >b ₂ >a ₂ (5)
_b2 = _c2 > _a2 ... Formula (6)
A deep-drawn case for an exterior of an electric storage device, characterized by satisfying any one of the three relational expressions of the above formulas (4), (5) and (6).

[3] A deep-drawn case for an exterior material comprising a heat-resistant resin layer as an outer layer, a heat-fusible resin layer as an inner layer, and a metal foil layer disposed between these layers, ,
The deep drawn case has a housing case capable of housing the electricity storage device main body, and a sealing peripheral edge portion extending outward in a substantially horizontal direction from the periphery of the opening on the lower surface of the housing case. It has a three-dimensional shape, and the top surface shape of the storage case is a substantially polygonal shape with a square or more,
Thickness of the metal foil layer forming the side surface of the deep-drawn case in a cross-sectional view of the deep-drawn case cut along a vertical plane passing through any two non-adjacent corners on the top surface of the storage case is “b ₃ ” (μm), the thickness of the metal foil layer constituting the first corner portion connecting the top surface and the side surface is “a ₃ ” (μm), and the sealing peripheral edge portion and the When the thickness of the metal foil layer constituting the second corner connecting the side surface is "c ₃ " (μm),
b ₃ >c ₃ >a ₃ (7)
c ₃ >b ₃ >a ₃ (8)
_b3 = _c3 > _a3 ... Formula (9)
A deep-drawn case for the exterior of an electric storage device, characterized by satisfying any one of the three relational expressions of the above formulas (7), (8) and (9).

[4] The deep-drawn case for exterior of an electric storage device according to any one of the preceding items 1 to 3, wherein the inner layer is formed of a plurality of heat-fusible resin layers.

[5] The deep-drawn case for exterior of an electric storage device according to any one of the preceding items 1 to 4, wherein the metal foil layer is made of aluminum foil.

[6] The deep-drawn case for exterior of an electric storage device according to any one of the preceding items 1 to 5, wherein a chemical conversion film layer is formed on at least the inner layer side surface of the metal foil layer.

[7] an electricity storage device main body;
An exterior member including the deep-drawn case for exterior of an electricity storage device according to any one of the preceding items 1 to 6,
An electricity storage device, wherein the electricity storage device main body is covered with the exterior member.

In the inventions [1] to [3], since no excessive strain is applied during deep drawing, pinholes and the like are less likely to occur in the molded case even after a lapse of time, and electrolyte leakage can be prevented.

In the invention [4], since the inner layer is formed of a plurality of heat-fusible resin layers, even if the deep-drawn case expands, the heat-fusible resin layer (inner layer) is torn. Hateful. In addition, by using a resin with good adhesiveness as the innermost heat-fusible resin layer of the plurality of heat-fusible resin layers constituting the inner layer, delamination is less likely to occur, and the electrolytic solution Leakage can be sufficiently prevented.

In the invention [5], since the metal foil layer is made of aluminum foil, the occurrence of pinholes and the like in the deep-drawn case can be sufficiently prevented.

In the invention [6], since the chemical conversion coating layer is formed on at least the inner layer side surface of the metal foil layer, it is possible to sufficiently prevent the occurrence of pinholes and the like in the metal foil layer caused by corrosion.

In the invention [7], since pinholes and the like are less likely to occur in the deep-drawn case, it is possible to provide an electricity storage device that can sufficiently prevent leakage of the electrolytic solution.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing one embodiment of a deep-drawn case for an electricity storage device according to the present invention; FIG. 4 is a cross-sectional view showing the exterior material before deep drawing. The deep-drawn case of FIG. 1 was cut along a vertical plane passing through any two non-adjacent corners on the top surface of the storage case (a vertical plane passing through two non-adjacent corners on the rectangular top surface). It is a sectional view. 1 is a cross-sectional view showing an embodiment of an electricity storage device according to the present invention; FIG.

The present invention will be described in detail below. A deep-drawn case 10 for an electricity storage device according to the present invention includes a heat-resistant resin layer 2 as an outer layer, a heat-fusible resin layer 3 as an inner layer, and a metal foil layer 4 disposed between these layers. It is a deep-drawn case (deep-drawn molded body) of an exterior material comprising: The deep drawn case 10 includes a housing case 28 capable of housing the electricity storage device main body 31 and a sealing opening extending outward in a substantially horizontal direction from the peripheral edge of the lower surface opening 28a of the housing case 28. The top surface 51 of the storage case 28 has a three-dimensional shape having a peripheral edge portion 53, and the shape of the top surface 51 of the storage case 28 is a substantially polygonal shape with a square or more (see FIG. 1).

In the embodiment shown in FIG. 1, the storage case 28 has a substantially rectangular parallelepiped shape, and has an open bottom surface to provide a bottom opening 28a (see FIG. 3). Thus, the deep drawn case 10 includes a top surface 51 extending in a substantially horizontal direction, a side surface 52 extending downward from the periphery of the top surface 51 via a first corner portion 55, and a sealing edge portion 53 extending outward in a substantially horizontal direction from the lower end of the side surface 52 via a second corner portion 56 (see FIGS. 1 and 3).

The first invention is a cross-sectional view (see FIG. 3) taken by cutting the deep drawn case 10 along a vertical plane passing through two arbitrary corners 41 and 42 that are not adjacent to each other on the top surface 51 of the housing case 28, Let the thickness of the side surface 52 connecting the top surface 51 and the sealing peripheral edge portion 53 be "b ₁ " (μm), and the thickness of the first corner portion 55 connecting the top surface 51 and the side surface 52 be When "a ₁ " (μm) and the thickness of the second corner portion 56 connecting the sealing edge portion 53 and the side surface 52 is "c ₁ " (μm),
b ₁ >c ₁ >a ₁ Formula (1)
c ₁ >b ₁ >a ₁ Formula (2)
_b1 = _c1 > _a1 ... Formula (3)
Any two of the three relational expressions of the above expressions (1), (2) and (3) are satisfied, and any two not adjacent to each other on the top surface 51 of the storage case 28 are satisfied. In the cross-sectional view (see FIG. 3) of the deep drawn case 10 cut along the vertical plane passing through the corners 41 and 42, the thickness of the metal foil layer forming the top surface 51 is assumed to be "d ₃ " (μm). A value of d ₃ /e ₃ is 0.70 or more, where "e ₃ " (μm) is the thickness of the metal foil layer forming the sealing edge portion 53 .

The second invention is a cross-sectional view (see FIG. 3) taken by cutting the deep drawn case 10 along a vertical plane passing through arbitrary two corners 41 and 42 that are not adjacent to each other on the top surface 51 of the housing case 28, The thickness of the heat-fusible resin layer constituting the side surface 52 that connects the top surface 51 and the sealing peripheral edge portion 53 is set to "b ₂ " (μm), and the top surface 51 and the side surface 52 are connected. The thickness of the heat-fusible resin layer forming the first corner portion 55 is set to “a ₂ ” (μm), and the thermal When the thickness of the fusible resin layer is “c ₂ ” (μm),
b ₂ >c ₂ >a ₂ (4)
c ₂ >b ₂ >a ₂ (5)
_b2 = _c2 > _a2 ... Formula (6)
It is characterized by satisfying any one of the above three relational expressions of formulas (4), (5) and (6).

The third invention is a cross-sectional view (see FIG. 3) taken by cutting the deep drawn case 10 along a vertical plane passing through arbitrary two corners 41 and 42 that are not adjacent to each other on the top surface 51 of the housing case 28, The thickness of the metal foil layer forming the side surface 52 that connects the top surface 51 and the sealing peripheral edge portion 53 is set to "b ₃ " (μm), and the first corner that connects the top surface 51 and the side surface 52 Let the thickness of the metal foil layer forming the portion 55 be "a ₃ " (μm), and the thickness of the metal foil layer forming the second corner portion 56 connecting the sealing peripheral edge portion 53 and the side surface 52 be When "c ₃ " (μm),
b ₃ >c ₃ >a ₃ (7)
c ₃ >b ₃ >a ₃ (8)
_b3 = _c3 > _a3 ... Formula (9)
It is characterized by satisfying any one of the above three relational expressions of formulas (7), (8) and (9).

In the above-mentioned first, second and third inventions, since no excessive strain is applied during deep drawing, pinholes and the like are less likely to occur in the molded case even with the passage of time. Leakage can be prevented. According to the first, second and third inventions, the leakage prevention effect of the electrolytic solution is particularly remarkable in a deep-drawn case which is deep-drawn to a depth of 2.0 mm or more.

In the first invention, when the thickness of the sealing peripheral portion 53 is "e ₁ " and the height of the side surface 52 of the molding case 10 (substantially equivalent to the molding depth) is "L", L is If it is 3.5 mm or more,
c ₁ >e ₁ >b ₁ >a ₁ Formula (10)
c ₁ >e ₁ >d ₁ >a ₁ Formula (11)
It is preferable that the structure satisfies the relational expressions of the above formulas (10) and (11). The occurrence can be sufficiently prevented.

In the third invention, when the thickness of the metal foil layer forming the sealing edge portion 53 is " _e3 " (μm), when _b3 ≧ _c3 , then _b3 ≧e ₃ , and when b ₃ <c ₃ , it is preferable that the configuration satisfies the relational expression b ₃ <e ₃ .

In the present invention, the shape of the top surface 51 of the housing case 28 is a substantially polygonal shape with a square or more. The substantially polygonal shape is not particularly limited, but includes, for example, a substantially quadrangular shape (see FIG. 1), a substantially hexagonal shape, a substantially octagonal shape, and the like.

The deep-drawn case 10 is a molded body obtained by deep-drawing the exterior material 1 (before molding). The exterior material 1 includes a heat-resistant resin layer 2 as an outer layer and a and a metal foil layer 4 disposed between the two layers (see FIG. 2).

The heat-resistant resin layer (outer layer) 2 is a member that mainly plays the role of ensuring good moldability as an exterior material, that is, plays the role of preventing breakage due to necking of the metal foil during molding. .

As the heat-resistant resin forming the heat-resistant resin layer (outer layer) 2, a heat-resistant resin that does not melt at the heat-sealing temperature at which the exterior material (deep-drawn case) is heat-sealed is used. As the heat-resistant resin, it is preferable to use a heat-resistant resin having a melting point higher than the melting point of the resin forming the heat-fusible resin layer 3 by 10° C. or more. It is particularly preferable to use a heat-resistant resin having a melting point higher by 20° C. or more than the above.

Examples of the heat-resistant resin layer (outer layer) 2 include, but are not limited to, a stretched polyamide film such as a stretched nylon film, and a stretched polyester film. Among them, as the heat-resistant resin stretched film layer 2, a biaxially stretched polyamide film such as a biaxially stretched nylon film, a biaxially stretched polybutylene terephthalate (PBT) film, a biaxially stretched polyethylene terephthalate (PET) film, or a biaxially stretched It is particularly preferred to use polyethylene naphthalate (PEN) films. As the heat-resistant resin stretched film layer 2, it is preferable to use a heat-resistant resin biaxially stretched film stretched by a simultaneous biaxial stretching method. Examples of the nylon include, but are not particularly limited to, 6 nylon, 6,6 nylon, MXD nylon, and the like. In addition, the heat-resistant resin layer 2 may be formed of a single layer (single stretched film), or may be a multilayer made of, for example, a stretched polyester film/stretched polyamide film (stretched PET film/stretched nylon film). It may be formed with a multilayer etc.).

The heat-resistant resin layer (outer layer) 2 may be a resin layer formed by applying a heat-resistant resin.

The thickness of the heat-resistant resin layer 2 is preferably 9 μm to 50 μm. By setting it to the preferred lower limit or more, sufficient strength can be secured as the exterior material 1, and by setting it to the preferred upper limit or less, the stress during deep drawing can be reduced, and formability can be improved. .

The heat-fusible resin layer (inner layer) 3 has excellent chemical resistance against highly corrosive electrolytic solutions used in lithium ion secondary batteries and the like, and is used as an exterior material (deep drawing It plays the role of imparting heat sealability to the case).

The heat-sealable resin is not particularly limited, but examples include polyethylene, polypropylene, ethylene ethyl acrylate (EEA), ethylene methyl acrylate (EAA), ethylene methyl methacrylate resin (EMMA), ethylene -Vinyl acetate copolymer resin (EVA), maleic anhydride-modified polypropylene, maleic anhydride-modified polyethylene, olefin resin ionomer, and the like.

Although the heat-fusible resin layer 3 is not particularly limited, it is preferably an unstretched thermoplastic resin film layer. The thermoplastic resin unstretched film layer 3 is not particularly limited, but at least one thermoplastic resin selected from the group consisting of polyethylene, polypropylene, olefinic copolymers, acid-modified products thereof, and ionomers. It is preferably composed of an unstretched film made of resin.

The thickness of the heat-fusible resin layer 3 is preferably set to 20 μm to 150 μm. By setting the thickness to 20 μm or more, it is possible to sufficiently prevent the occurrence of pinholes, and by setting the thickness to 150 μm or less, it is possible to reduce the amount of resin used, thereby reducing costs. Above all, it is particularly preferable to set the thickness of the heat-fusible resin layer 3 to 30 μm to 100 μm. The heat-fusible resin layer 3 may be a single layer or multiple layers.

A lubricant is usually added to the heat-fusible resin layer 3 . Addition of the lubricant can improve moldability during molding. The content of the lubricant in the heat-fusible resin layer 3 is preferably set within the range of 200 ppm to 5000 ppm.

Examples of the lubricant include, but are not limited to, 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. mentioned.

The metal foil layer 4 plays a role of imparting a gas barrier property to the exterior material (deep-drawn case) to prevent permeation of oxygen and moisture. Examples of the metal foil layer 4 include, but are not limited to, aluminum foil, copper foil, SUS foil, nickel foil, etc. Aluminum foil is generally used. The thickness of the metal foil layer 4 is preferably 15 μm to 150 μm. When the thickness is 15 μm or more, it is possible to prevent the occurrence of pinholes during rolling when manufacturing the metal foil, and when it is 150 μm or less, the stress during deep drawing can be reduced and formability can be improved. Above all, the thickness of the metal foil layer 4 is more preferably 20 μm to 100 μm.

Preferably, at least the inner surface 4a (the surface on the second adhesive layer 6 side) of the metal foil layer 4 is subjected to a chemical conversion treatment. Such chemical conversion treatment can sufficiently prevent corrosion of the metal foil surface due to contents (eg, battery electrolyte, food, pharmaceuticals, etc.). For example, the metal foil is chemically treated by the following treatment. That is, for example, on the surface of a metal foil that has been degreased,
1) Aqueous solution consisting of a mixture of metal salts of phosphoric acid, chromic acid and fluoride 2) Aqueous solution consisting of a mixture of phosphoric acid, chromic acid, fluoride metal salts and non-metal salts 3) Acrylic resin and/or phenolic resin or an aqueous solution consisting of a mixture of phosphoric acid, chromic acid, and a metal fluoride salt, and then dried to perform a chemical conversion treatment to form a chemical conversion film.

The first adhesive layer (outer adhesive layer) 5 is not particularly limited, but may be, for example, an adhesive layer formed of a two-liquid reactive adhesive. As the two-liquid reactive adhesive, for example, a first liquid consisting of one or more polyols selected from the group consisting of polyurethane-based polyols, polyester-based polyols and polyether-based polyols, and a first liquid consisting of polyisocyanate A two-liquid reactive adhesive composed of two liquids (curing agent) and the like can be mentioned. In the first adhesive layer 5, for example, an adhesive such as the two-liquid reactive adhesive is applied to the "upper surface of the metal foil layer 4" and/or to the "lower surface of the heat-resistant resin layer 2". , and is formed by coating with a method such as a gravure coating method.

The second adhesive layer (inner adhesive layer) 6 is not particularly limited, but examples include polyurethane adhesives, acrylic adhesives, epoxy adhesives, polyolefin adhesives, and elastomer adhesives. Adhesive layers formed of adhesives, fluorine-based adhesives, and the like can be used. Among them, a two-liquid reactive adhesive composed of a first liquid made of an acid-modified olefin resin (maleic anhydride-modified polypropylene, maleic anhydride-modified polyethylene, etc.) and a second liquid (curing agent) made of polyisocyanate. is preferably used, and in this case, the electrolytic solution resistance and water vapor barrier properties of the exterior material can be further improved.

In the above-described embodiment, the configuration in which the first adhesive layer 5 and the second adhesive layer 6 are provided is adopted. It is also possible to employ a configuration that does not provide.

Thus, by deep-drawing the exterior material (see FIG. 2) 1 having the above configuration, a deep-drawn case 10 for exterior of an electric storage device as shown in FIG. 1 can be obtained. The shape of the deep-drawn case 10 for the exterior of the electric storage device is not particularly limited, but includes, for example, a substantially rectangular parallelepiped shape with one open surface (lower surface; bottom surface) as shown in FIG.

Next, FIG. 4 shows an embodiment of the electricity storage device 30 according to the present invention. As shown in FIG. 4 , an electricity storage device main body 31 having a substantially rectangular parallelepiped shape is accommodated in an accommodation recess (accommodation case) of the deep-drawn case 10 for exterior of an electricity storage device according to the present invention. Below, the planar exterior material 1 (before molding) is arranged with the inner layer 3 side facing inward (upper side), and the peripheral edge portion of the inner layer 3 of the planar exterior material 1 and the deep draw molding The power storage device 30 of the present invention is configured by heat-sealing and sealing the inner layer 3 of the sealing edge portion (flange portion) 53 of the case 10 . In FIG. 4, reference numeral 39 denotes a heat-sealed portion where the peripheral portion of the exterior material 1 and the sealing peripheral portion (flange portion) 53 of the deep drawn case 10 are joined (welded).

The electricity storage device main body 31 is not particularly limited, but examples thereof include a battery main body, a capacitor main body, and a capacitor main body.

Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples.

<Example 1>
On both sides of a 30 μm thick aluminum foil (A8021H material specified in JIS H4160) (metal foil) 4, a chemical compound consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol After applying the treatment liquid, drying was performed at 180° C. to form a chemical conversion film. The amount of chromium deposited on this chemical conversion film was 2 mg/m ² per side.

Next, a 15 μm thick biaxially oriented nylon film (outer layer film ) 2 was dry-laminated (bonded together) to obtain a laminate.

Next, on the other surface of the aluminum foil 4 of the obtained laminate, a 25 μm thick unstretched polypropylene film (inner layer ) 3 was dry-laminated (bonded) and then aged (heated) at 40° C. for 8 days to obtain the exterior material 1 having the structure shown in FIG. The unstretched polypropylene film is a three-layer laminated film in which random polypropylene, block polypropylene, and random polypropylene are laminated in this order by coextrusion, and the random polypropylene serving as the outermost layer (outermost layer) contains erucamide as a lubricant. Contains 1000ppm.

Next, using a deep drawing tool manufactured by Amada Co., Ltd., the exterior material (exterior material cut into a size of 150 mm × 200 mm) is formed into a substantially rectangular parallelepiped shape of 50 mm long × 30 mm wide × 2.3 mm deep Deep drawing (press speed: 20 spm, wrinkle suppression pressure: 1.60 MPa) is performed on the (substantially rectangular parallelepiped shape with one side open) to obtain the deep drawn case 10 for the exterior of the electric storage device shown in FIGS. rice field. The obtained molded case had a size of 120 mm long×100 mm wide in plan view, and the width of each of the peripheral edge portions for sealing was 35 mm.

<Example 2>
As the deep drawing conditions, the deep drawing case for the exterior of the electric storage device shown in FIGS. Obtained.

< Reference example 4 >
As the deep drawing conditions, the deep drawing case for the exterior of the electric storage device shown in FIGS. Obtained.

< Reference example 5 >
In the same manner as in Example 1, except that an aluminum foil with a thickness of 40 μm was used instead of the aluminum foil with a thickness of 30 μm, the molding height was set to 4.4 mm, and the wrinkle suppression pressure was set to 0.80 MPa. 1 and 3 were obtained.

< Reference example 6 >
The same as in Example 1 except that an unstretched polypropylene film with a thickness of 40 μm was used instead of the unstretched polypropylene film with a thickness of 25 μm, the molding height was set to 4.4 mm, and the wrinkle suppression pressure was set to 0.40 MPa. As a result, the deep-drawn case for exterior of the electric storage device shown in FIGS. 1 and 3 was obtained.

< Reference example 1 >
A biaxially oriented polyethylene terephthalate (PET) film with a thickness of 15 μm was used instead of the biaxially oriented nylon film with a thickness of 15 μm. , in the same manner as in Example 1, a deep-drawn molded case for exterior of an electric storage device shown in FIGS. 1 and 3 was obtained.

< Reference example 2 >
Except that a biaxially oriented polybutylene terephthalate (PBT) film with a thickness of 15 μm was used instead of the biaxially oriented nylon film with a thickness of 15 μm, and the forming height was set to 3.5 mm, and the wrinkle suppression pressure was set to 0.40 MPa. In the same manner as in Example 1, a deep-drawn molded case for exterior of an electric storage device shown in FIGS. 1 and 3 was obtained.

< Reference example 3 >
Instead of the 15 μm-thick biaxially oriented nylon film, a laminated film (the nylon film is the outermost 1 and 3 in the same manner as in Example 1, except that the molding height was set to 3.5 mm and the wrinkle suppression pressure was set to 0.40 MPa. got

<Comparative Example 1>
A deep drawn case for exterior of an electric storage device was obtained in the same manner as in Example 1, except that the forming height was set to 5.7 mm and the wrinkle suppressing pressure was set to 1.20 MPa as the deep drawing forming conditions.

<Comparative Example 2>
A deep drawn case for exterior of an electric storage device was obtained in the same manner as in Example 1, except that the forming height was set to 6.5 mm and the wrinkle suppressing pressure was set to 1.20 MPa as the deep drawing forming conditions.

<Comparative Example 3>
In the same manner as in Example 1, except that a 15 μm thick biaxially oriented polyethylene terephthalate (PET) film was used instead of the 15 μm thick biaxially oriented nylon film, and the molding height was set to 3.5 mm. , a deep-drawn molded case for exterior of an electric storage device was obtained.

<Comparative Example 4>
A deep-drawn molded case for exterior of an electric storage device was obtained in the same manner as in Example 1, except that the molding height was set to 3.5 mm.

With respect to each of the deep-drawn cases for the exterior of an electric storage device obtained as described above, the thickness of each of the following portions of the formed case was measured as follows. Specifically, after solidifying the molded case with an acrylic resin, the molded case is cut along a vertical plane passing through two arbitrary corners that are not adjacent to each other on the top surface of the storage case of the molded case, and the cut surface is Cross-sectional observation was performed using a scanning electron microscope (SEM), and thicknesses b ₁ , a ₁ , c ₁ , d ₁ , and e ₁ at the following portions of the molded case 10 were measured by comparison with scale bars. Namely
“b ₁ ” … Thickness of the side surface of the molded case (thickness at the halfway point of the vertical height of the side surface; see FIG. 3)
"a ₁ " ... the thickness of the first corner connecting the top surface and the side surface (the first corner thickness; see Fig. 3)
“c ₁ ” … Thickness of the second corner portion connecting the sealing peripheral edge portion and the side surface (at the halfway position from one end to the other end of the curved portion of the second corner portion on the cut surface The thickness of the second corner of the; see Figure 3)
"d ₁ " ... thickness of the top surface of the molded case (thickness of the top surface at the intersection of two diagonal lines on the top surface)
“e ₁ ”: The thickness of the sealing peripheral portion (thickness at the midpoint of the bisected portion in the width direction of the sealing peripheral portion) was measured. Table 1 shows the measurement results of the thickness of each part.

In addition, the thickness of each of the following parts of the inner layer 3 of each of the obtained deep-drawn cases for electric storage devices was measured by cross-sectional observation of the cut surface with a scanning electron microscope (SEM) in the same manner as described above. Namely
“b ₂ ”: Thickness of the inner layer forming the side surface of the molded case (thickness of the inner layer at the midpoint of the vertical height on the side surface)
“a ₂ ” … Thickness of the inner layer that forms the first corner connecting the top surface and the side surface (the halfway point from one end to the other end of the curved portion of the first corner on the cut surface inner layer thickness at position)
“c ₂ ” … the thickness of the inner layer forming the second corner connecting the sealing peripheral portion and the side surface (the thickness of the inner layer from one end to the other end of the curved portion of the second corner on the cut surface) thickness of the inner layer at the intermediate position of the equal division)
“d ₂ ”: Thickness of the inner layer forming the top surface of the molded case (thickness of the inner layer at the intersection of two diagonal lines on the top surface)
“e ₂ ”: Thickness of the inner layer constituting the sealing peripheral edge (thickness of the inner layer at the midpoint of the widthwise bisector of the sealing peripheral edge)
were measured respectively. Table 2 shows the measurement results of the thickness of each part.

In addition, the thicknesses of the metal foil layer 4 at the following portions of each of the obtained deep-drawn cases for electric storage devices were measured by cross-sectional observation with a scanning electron microscope (SEM) in the same manner as described above. Namely
“b ₃ ”: Thickness of the metal foil layer forming the side surface of the molded case (thickness of the metal foil layer at the midpoint of the vertical height on the side surface)
“a ₃ ” … Thickness of the metal foil layer forming the first corner connecting the top surface and the side surface (bisected from one end to the other end of the curved part of the first corner on the cut surface thickness of the metal foil layer at the intermediate position)
“c ₃ ”: Thickness of the metal foil layer forming the second corner connecting the sealing peripheral portion and the side surface (the thickness from one end to the other end of the curved portion of the second corner on the cut surface thickness of the metal foil layer at the midpoint of the bisection)
“d ₃ ”: thickness of the metal foil layer forming the top surface of the molded case (thickness of the metal foil layer at the intersection of two diagonal lines on the top surface)
“e ₃ ”: Thickness of the metal foil layer forming the peripheral portion for sealing (thickness of the metal foil layer at the midpoint of the bisected portion in the width direction of the peripheral portion for sealing)
were measured respectively. Table 2 shows the measurement results of the thickness of each part.

In addition, the thickness of each of the following portions of the outer layer 2 of each obtained deep-drawn case for an electric storage device was measured by cross-sectional observation of the cut surface with a scanning electron microscope (SEM) in the same manner as described above. Namely
“b ₄ ”: Thickness of the outer layer forming the side surface of the molded case (thickness of the outer layer at the midpoint of the vertical height of the side surface)
“a ₄ ” … Thickness of the outer layer forming the first corner connecting the top surface and the side surface (halfway between one end and the other end of the curved portion of the first corner on the cut surface outer layer thickness at position)
“c ₄ ”: Thickness of the outer layer forming the second corner connecting the sealing peripheral edge and the side surface (the thickness of the outer layer from one end to the other end of the curved portion of the second corner on the cut surface) thickness of the outer layer at the intermediate position of the equal division)
“d ₄ ”: Thickness of the outer layer forming the top surface of the molded case (thickness of the outer layer at the intersection of two diagonal lines on the top surface)
“e ₄ ”: Thickness of the outer layer forming the peripheral portion for sealing (thickness of the outer layer at the midpoint of the bisected portion in the width direction of the peripheral portion for sealing)
were measured respectively. Table 3 shows the measurement results of the thickness of each part.

Furthermore, each of the obtained deep-drawn cases for electric storage devices was evaluated based on the following evaluation methods. Table 3 shows the results.

<Appearance evaluation method after molding>
The presence of pinholes and the presence of delamination (peeling) between layers in the obtained deep-drawn case for exterior of an electric storage device was examined, and the appearance was evaluated based on the following criteria.
(criterion)
"◯": No pinholes in the first and second corners and other parts, and no delamination (peeling) between layers was observed. "X": At the first corner and/or the second corner. A pinhole had occurred.
"XX": Delamination (peeling) was observed between the layers.

<Method for evaluating leakage prevention of electrolyte solution>
After putting 15 mL of the electrolytic solution into the obtained deep-drawn case 10 for exterior of the electric storage device, the same exterior material as the planar exterior material 1 described in Example 1 is placed on the inner layer 3 side of the molded case 10. After superimposing the inner layer 3 (120 mm long×100 mm wide), a simulated electricity storage device was obtained by heat-sealing the area of the peripheral edge portion for sealing with a sealing width of 5 mm at 170° C. for 6 seconds. After storing the simulated electricity storage device for 30 days under conditions of 100 ° C., the presence or absence of electrolyte leakage in the simulated electricity storage device and the appearance of the deep drawn case were examined. Appearance was evaluated.
(Judgment criteria for liquid leakage prevention)
“◯”: No electrolyte leakage was observed in the simulated electricity storage device “×”: Electrolyte leakage was observed in the simulated electricity storage device (appearance criteria)
"○": The exterior case of the simulated electricity storage device had a good appearance without any change from before the electrolyte was injected. was taken.

As is clear from the table, the deep-drawn cases for the exterior of the electric storage device of Examples 1 to 2 and Reference Examples 1 to 6 according to the present invention are less likely to have pinholes, etc., and the electrolytic solution in the electric storage device is less likely to form. Leakage can be prevented.
On the other hand, in the molded cases of Comparative Examples 1 to 4, which deviate from the specified range of the present invention, it was not possible to prevent the electrolyte from leaking from the electricity storage device. In addition, in the molded case of Comparative Example 2, pinholes had already occurred when the external appearance was evaluated after molding, so the leakage prevention property of the electrolytic solution was not evaluated.

Specific examples of the deep-drawn case for exterior of an electric storage device according to the present invention include, for example,
・Used as an exterior case for various storage devices such as storage devices such as lithium secondary batteries (lithium ion batteries, lithium polymer batteries, etc.), lithium ion capacitors, electric double layer capacitors, and all-solid-state batteries.

1 ... exterior material 2 ... heat-resistant resin layer (outer layer)
3... Heat-fusible resin layer (inner layer)
4... Metal foil layer 10... Deep drawn case 15... Exterior member 28... Housing case 28a... Lower surface opening 30... Electricity storage device 31... Electricity storage device main body 41... Top surface corner (corner part)
42 ... Corner part (corner part) of the top surface
51... Top surface 52... Side surface 53... Peripheral portion for sealing 55... First corner portion 56... Second corner portion

Claims (5)

A deep-drawn case for an exterior material comprising a heat-resistant resin layer as an outer layer, a heat-sealable resin layer as an inner layer, and a metal foil layer disposed between these layers,
The heat-resistant resin layer is formed of a stretched polyamide film single layer,
The deep drawn case has a housing case capable of housing the electricity storage device main body, and a sealing peripheral edge portion extending outward in a substantially horizontal direction from the periphery of the opening on the lower surface of the housing case. It has a three-dimensional shape, and the top surface shape of the storage case is a substantially polygonal shape with a square or more,
In a cross-sectional view of the deep-drawn case cut along a vertical plane passing through any two non-adjacent corners of the top surface of the storage case, the thickness of the side surface of the deep-drawn case is "b ₁ " ( μm), the thickness of the first corner portion connecting the top surface and the side surface is “a ₁ ” (μm), and the thickness of the second corner portion connecting the sealing peripheral edge portion and the side surface is When "c ₁ " (μm),
b ₁ >c ₁ >a ₁ Formula (1)
c ₁ >b ₁ >a ₁ Formula (2)
_b1 = _c1 > _a1 ... Formula (3)
While satisfying any one of the three relational expressions of the above formulas (1), (2) and (3),
In a cross-sectional view of the storage case cut along a vertical plane passing through two non-adjacent corners of the top surface, the thickness of the metal foil layer forming the top surface is defined as "d ₃ " (μm). , and the value of d ₃ /e ₃ is 0.00, where the thickness of the metal foil layer forming the sealing edge portion is "e ₃ " (μm). is 87 or more,
Furthermore, in the cross-sectional view of the deep-drawn case cut along the vertical plane, the thickness of the heat-fusible resin layer constituting the side surface of the deep-drawn case is defined as "b ₂ " (μm), The thickness of the heat-fusible resin layer constituting the first corner portion connecting the surface and the side surface is set to "a ₂ " (μm), and the second corner portion connecting the sealing peripheral portion and the side surface is When the thickness of the constituent heat-fusible resin layer is “c ₂ ” (μm),
b ₂ >c ₂ >a ₂ (4)
c ₂ >b ₂ >a ₂ (5)
_b2 = _c2 > _a2 ... Formula (6)
satisfies any one of the three relational expressions of the above formulas (4), (5) and (6),
Furthermore, in the cross-sectional view of the deep-drawn case cut along the vertical plane, the thickness of the metal foil layer forming the side surface of the deep-drawn case is defined as "b ₃ " (μm), and the top surface and the The thickness of the metal foil layer forming the first corner connecting the side surface is set to "a ₃ " (μm), and the thickness of the metal foil layer forming the second corner connecting the sealing peripheral portion and the side surface. When the thickness is “c ₃ ” (μm),
b ₃ >c ₃ >a ₃ (7)
c ₃ >b ₃ >a ₃ (8)
_b3 = _c3 > _a3 ... Formula (9)
A deep-drawn case for the exterior of an electric storage device, characterized by satisfying any one of the three relational expressions of the above formulas (7), (8) and (9). 2. The deep-drawn case for exterior of an electric storage device according to claim 1, wherein said inner layer is formed of a plurality of heat-sealable resin layers. 3. The deep-drawn case according to claim 1, wherein the metal foil layer is made of aluminum foil. 4. The deep-drawn case for exterior of an electric storage device according to claim 1, wherein a chemical conversion film layer is formed on at least the inner layer side surface of the metal foil layer. an electricity storage device main body;
An exterior member including the deep-drawn case for exterior of an electricity storage device according to any one of claims 1 to 4,
An electricity storage device, wherein the electricity storage device main body is covered with the exterior member.

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