JP7319818B2 - Exterior material for power storage device and power storage device - Google Patents

Description

The present invention relates to batteries and capacitors used in mobile devices such as smartphones, tablets, and digital cameras, hybrid vehicles, electric vehicles, wind power generation, solar power generation, and power storage such as batteries and capacitors used for storing nighttime electricity. The present invention relates to an exterior material for a device and an electric storage device exteriorized with the exterior material.

Lithium ion secondary batteries are widely used as power sources for, for example, notebook computers, video cameras, mobile phones, and the like. As this lithium ion secondary battery, one having a configuration in which a battery main body (a main body including a positive electrode, a negative electrode, and an electrolyte) is surrounded by an exterior material is used. As such an exterior material, for example, one having a configuration in which an outer layer made of a stretched polyamide resin, a metal foil layer made of an aluminum foil or the like, and an inner layer made of a heat-fusible resin are laminated in this order is known. (See Patent Document 1).

The battery is constructed by sandwiching the battery main body between a pair of exterior materials and sealing the peripheral edges of the inner layers of the pair of exterior materials by heat sealing. ing.

JP-A-2001-93482

By the way, such a laminate-type battery is housed in a circuit or in a space inside a device, but since the battery is only housed and the battery is not fixed, it is difficult to use the device housing the battery. There is a risk that the battery will sometimes move and damage the circuit or the battery itself.

The present invention has been made in view of the above technical background, and provides an exterior material for an electrical storage device and an electrical storage device that enables an electrical storage device having a device main body covered with an exterior material to be fixed to a housing or the like. The purpose is to provide a device.

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

[1] An exterior material for an electric storage device, 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,
An exterior material for an electric storage device, wherein a heat-adhesive resin layer is laminated on at least a part of the outer surface of the heat-resistant resin layer.

[2] The electricity storage according to the preceding item 1, wherein the heat-adhesive resin constituting the heat-adhesive resin layer is a two-component curable heat-adhesive resin containing a main agent and a block isocyanate as a curing agent. Exterior material for devices.

[3] The exterior material for an electricity storage device according to the above item 2, wherein the two-liquid curable thermoadhesive resin contains a dissociation catalyst.

[4] The exterior material for an electricity storage device according to the above item 2 or 3, wherein the main agent is a resin having a hydroxyl group.

[5] The exterior material for an electric storage device according to any one of [2] to [4] above, wherein 80% or more of the blocked isocyanate blocking agent dissociates at a temperature lower than 220°C.

[6] An exterior case for an electricity storage device, comprising a molding of the exterior material according to any one of 1 to 5 above.

[7] an electricity storage device main body;
An exterior member comprising the exterior material according to any one of the preceding items 1 to 5 and/or the exterior case according to the preceding item 6,
An electricity storage device, wherein the electricity storage device main body is covered with the exterior member.

In the invention [1], since the heat-adhesive resin layer is laminated on at least a part of the outer surface of the heat-resistant resin layer, the heat-adhesive resin layer adheres the electricity storage device to the housing, circuit, device, or the like. However, since the power storage device can be fixed to a housing, a circuit, a device, or the like, the battery does not move within the housing during use, etc., and damage to the battery, the circuit, and the like can be prevented.

In the invention [2], the adhesive strength of the thermoadhesive resin layer can be improved.

In the invention [3], the reactivity of the thermoadhesive resin layer during thermal adhesion can be improved, and the adhesive force can be improved.

In the invention [4], the adhesive strength of the thermoadhesive resin layer can be further improved.

In the invention [5], the electric storage device can be fixed to the housing or the like without adversely affecting the heat-resistant resin layer (outer layer) of the exterior material.

In the invention [6], since the heat-adhesive resin layer is laminated on at least a part of the outer surface of the heat-resistant resin layer of the exterior case, the heat-adhesive resin layer forms the power storage device into a housing, a circuit, and an apparatus. Since the power storage device can be fixed to a housing, a circuit, a device, etc., the battery does not move within the housing during use, etc., and damage to the battery, the circuit, etc. can be prevented.

In the invention [7], the heat-adhesive resin layer is laminated on at least a part of the outer surface of the heat-resistant resin layer of the exterior material and/or the exterior case. Since it can be adhered to a body, circuit, device, etc., and the storage device can be fixed to the housing, circuit, device, etc., the battery does not move inside the housing during use, etc., preventing damage to the battery, circuit, etc. can do.

1 is a cross-sectional view showing an embodiment of an exterior material for an electricity storage device according to the present invention; FIG. FIG. 2 is a cross-sectional view showing the electricity storage device of the present invention in a state of being adhesively fixed in a housing; FIG. 3 is a perspective view showing an exterior material (planar one), an electricity storage device main body, and an exterior case (three-dimensional molded body) constituting the electricity storage device of FIG. 2 in a separated state before being heat-sealed. FIG. 3 is an explanatory diagram (a perspective view showing an exterior molded product) of a method for preparing a simulated battery.

FIG. 1 shows an embodiment of an exterior material 1 for an electric storage device according to the present invention. This exterior material 1 is used as an exterior material for a battery such as a lithium ion secondary battery. The exterior material 1 may be used as the exterior material 1 without being molded (see FIG. 3), or may be used as the molded case 10 after being subjected to molding such as deep drawing and stretch molding. (see FIG. 3).

The power storage device exterior material 1 is formed by laminating and integrating a heat-resistant resin layer (outer layer) 2 on one surface (upper surface) of a metal foil layer 4 with an outer adhesive layer (first adhesive layer) 5 interposed therebetween. At the same time, a heat-fusible resin layer (inner layer) 3 is laminated and integrated on the other surface (lower surface) of the metal foil layer 4 with an inner adhesive layer (second adhesive layer) 6 interposed therebetween. A thermally adhesive resin layer 8 is laminated on at least a part of the outer surface of a flexible resin layer (outer layer) 2 (see FIG. 1).

In the present invention, the outer layer 2 is made of a heat-resistant resin layer. As the heat-resistant resin forming the heat-resistant resin layer 2, a heat-resistant resin that does not melt at the heat-sealing temperature at which the exterior material 1 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 heat-fusible 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 than °C.

The heat-resistant resin layer (outer layer) 2 is a member that mainly plays the role of ensuring good moldability as the exterior material 1, that is, mainly plays the role of preventing breakage due to necking of the aluminum foil during molding. It is.

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, the heat-resistant resin layer 2 may be biaxially oriented polyamide film such as biaxially oriented nylon film, biaxially oriented polybutylene terephthalate (PBT) film, biaxially oriented polyethylene terephthalate (PET) film or biaxially oriented polyethylene film. It is particularly preferred to use phthalate (PEN) films, all of which have a hot water shrinkage of 1.5% to 12%. Moreover, as the heat-resistant resin 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 film layer 2 may be formed of a single layer (single stretched film), or may be, for example, a multilayer made of stretched polyester film/stretched polyamide film (stretched PET film/stretched nylon film). It may be formed of a multilayer film or the like).

The thickness of the heat-resistant resin layer 2 is preferably 5 μm to 50 μm. Sufficient strength as an exterior material can be ensured by setting the value to the preferred lower limit value or more, and by setting the value to the preferred upper limit value or less, the stress during stretch forming or draw forming can be reduced to improve formability. can be done.

The heat-resistant resin layer 2 may be formed of a resin film, or may be a resin coat layer formed by applying a resin. The resin forming the resin coating layer is not particularly limited, but examples thereof include urethane resin, acrylic resin, epoxy resin, and the like.

Examples of the second adhesive layer 5 include, but are not limited to, a two-liquid curing adhesive (such as a urethane-based adhesive) and a photocurable adhesive. The thickness of the second adhesive layer (outer adhesive layer) 5 is preferably 1 μm to 3 μm.

In the present invention, the metal foil layer 4 plays a role of imparting a gas barrier property to the exterior material 1 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, titanium foil, etc. Aluminum foil is generally used. In addition, clad foil and metal plated foil may be used. The thickness of the metal foil layer 4 is preferably 20 μm to 100 μm. When the thickness is 20 μm or more, it is possible to prevent the occurrence of pinholes during rolling when manufacturing the metal foil. be able to.

Preferably, at least the inner surface of the metal foil layer 4 (the surface on the inner adhesive layer 6 side) is subjected to a chemical conversion treatment. Such chemical conversion treatment can sufficiently prevent the corrosion of the metal foil surface due to the contents (electrolyte solution of the battery, 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) phosphoric acid;
chromic acid;
2) an aqueous solution of a mixture containing at least one compound selected from the group consisting of metal salts of fluoride and non-metal salts of fluoride;
at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins;
3) an aqueous solution of a mixture containing at least one compound selected from the group consisting of chromic acid and chromium (III) salts;
at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins;
at least one compound selected from the group consisting of chromic acid and chromium (III) salts;
An aqueous solution of a mixture containing at least one compound selected from the group consisting of a metal salt of fluoride and a non-metallic salt of fluoride After applying any of the aqueous solutions of 1) to 3) above, dry By doing so, chemical conversion treatment is performed.

The chemical conversion film preferably has a chromium adhesion amount (per side) of 0.1 mg/m ² to 50 mg/m ² , particularly preferably 2 mg/m ² to 20 mg/m ² .

The heat-sealable resin layer (inner layer) 3 provides excellent chemical resistance against highly corrosive electrolyte solutions used in lithium-ion secondary batteries and the like, and heat-sealing properties of the exterior material. It plays the role of giving

The resin constituting the heat-fusible resin layer 3 is not particularly limited, but examples include polyethylene, polypropylene, ionomer, ethylene ethyl acrylate (EEA), ethylene methyl acrylate (EAA), and ethylene methacryl. Methyl acid resin (EMMA), ethylene-vinyl acetate copolymer resin (EVA), maleic anhydride-modified polypropylene, maleic anhydride-modified polyethylene and the like can be mentioned.

The thickness of the heat-fusible resin layer 3 is preferably set to 15 μm to 100 μm. By setting the thickness to 15 μm or more, sufficient heat seal strength can be ensured, and setting the thickness to 100 μm or less contributes to thinning and weight reduction. Above all, it is more preferable to set the thickness of the heat-fusible resin layer 3 to 10 μm to 80 μm. The heat-fusible resin layer 3 is preferably formed of a heat-fusible resin unstretched film layer, and the heat-fusible resin layer 3 may be a single layer or multiple layers. It can be.

Examples of the first adhesive layer 6 include, but are not limited to, a thermosetting acrylic adhesive, a thermosetting acid-modified polypropylene adhesive, a thermosetting polyurethane adhesive, and the like. The thickness of the first adhesive layer (inner adhesive layer) 6 is preferably 1 μm to 5 μm.

In the present invention, the thermoadhesive resin layer 8 is a resin that develops adhesiveness when heated. When the melting point of the heat-fusible resin is "T1" and the melting point of the heat-bondable resin is "T2", it is preferable that a relationship of T1≤T2 is established.

The thermoadhesive resin constituting the thermoadhesive resin layer 8 is not particularly limited, but is a two-component curable thermoadhesive resin containing a main agent and a block isocyanate as a curing agent. is preferably used. For example, a liquid containing a main agent, a blocked isocyanate, a dissociation catalyst, and a solvent is applied to the surface (outer surface) of the heat-resistant resin layer 2 by a method such as a gravure roll method, and dried to achieve thermal adhesion. A flexible resin layer 8 is formed. The formation amount (solid content) of the thermoadhesive resin layer 8 is preferably set to 1 g/m ² to 10 g/m ² .

Examples of the main agent include, but are not limited to, carboxylic acid-modified olefin resins, carboxylic anhydride-modified olefin resins, polyols (trimethylolpropane, methylpentadiol, etc.), polyvinyl alcohol (PVA)-based resins, acrylic resins, system resin, pentaerythritol, bisphenol, allitol, dulcitol, inositol, dipentaerythritol, polyester polyol, and the like.

The blocked isocyanate is a compound that stabilizes the isocyanate group by masking the highly reactive isocyanate group with a blocking agent. , and exhibits high reactivity with compounds having active hydrogen.

Examples of the blocked isocyanate include, but are not particularly limited to, a compound obtained by masking a terminal isocyanate group of an isocyanate compound with a blocking agent. Examples of the isocyanate compound include organic diisocyanate, polymeric type polyisocyanate, isocyanate group-terminated polymer obtained by reacting organic diisocyanate with an active hydrogen group-containing compound, and modified isocyanurate.

Examples of the blocking agent include, but are not limited to, hydroxyl-terminated polyester resins, ammonium hydrogencarbonate, alcohols, phenols, ε-caprolactam, aromatic amines, oximes, MEKO (methyl ethyl ketoxime), and the like. . It is preferable that 80% or more of the blocking agent of the blocked isocyanate dissociate at a temperature lower than 220°C. The power storage device can be fixed to the housing or the like without the need.

It is preferable to add the dissociation catalyst, which can improve the reactivity of the thermoadhesive resin. Examples of the dissociation catalyst include, but are not limited to, dioctyltin dilaurate, dibutyltin dilaurate, and the like.

Examples of the solvent include, but are not limited to, toluene, methylcyclohexane, and butyl acetate.

Additives such as anti-blocking agents, waxes, and slip agents (lubricants) may be added to the thermoadhesive resin.

The heat-adhesive resin layer 8 is preferably formed on the entire outer surface of the heat-resistant resin layer 2 in the exterior material, but is not particularly limited to such a form. It may also be a portion that allows for adhesive fixation to.

An exterior case (battery case, etc.) 14 can be obtained by molding (deep drawing, stretch molding, etc.) the exterior material 1 for an electric storage device of the present invention (see FIGS. 2 and 3). The exterior material 1 of the present invention can be used as it is without being subjected to molding (see FIGS. 2 and 3).

FIG. 2 shows an embodiment of an electricity storage device 30 configured using the electricity storage device exterior material 1 of FIG. This power storage device 30 is a lithium ion secondary battery. In the present embodiment, as shown in FIGS. 2 and 3, an exterior member 15 is composed of an exterior case 14 obtained by molding the exterior member 1 and the planar exterior member 1 . Thus, a substantially rectangular parallelepiped electricity storage device main body (electrochemical element or the like) 31 is arranged in the housing recess of the exterior case 14 obtained by molding the exterior material 1 of the present invention, and the electricity storage device main body 31 The exterior material 1 of the present invention is placed on top of the planar exterior material 1 with the heat-adhesive resin layer 8 side facing outward (upper side) without being molded, and the heat-fusible resin layer 3 of the planar exterior material 1 The peripheral edge portion and the heat-sealing resin layer 3 of the flange portion (sealing peripheral edge portion) 29 of the exterior case 14 are heat-sealed and sealed, whereby the electric storage device 30 of the present invention is formed. (see FIGS. 2 and 3). The outer surface of the bottom wall of the accommodation recess of the exterior case 14 is a thermoadhesive resin layer 8 (see FIG. 3).

Thus, after the electric storage device 30 is formed, it is placed in a substantially rectangular parallelepiped housing 25 and heated to dissociate the blocked isocyanate blocking agent of the thermoadhesive resin layer 8 so that the isocyanate group is Reproduction causes a reaction to bond the thermoadhesive resin layer 8 to the inner surface of the housing 25 . In this electricity storage device 30, the electricity storage device 30 can be adhered to the inner surface of the housing 25 by the heat-adhesive resin layer 8, and the electricity storage device 30 can be fixed to the housing 25 (see FIG. 2). Even if external pressure (vibration, impact, etc.) is applied, the power storage device 30 will not move in the housing or the like, and damage to the power storage device, circuits, and the like can be prevented. In FIG. 2, the heat-adhesive resin layer 8 is provided on both upper and lower sides, but the heat-adhesive resin layer 8 may be provided only on one side.

In FIG. 2, reference numeral 39 denotes a heat-sealed portion where a peripheral edge portion of the exterior material 1 and a flange portion (sealing peripheral edge portion) 29 of the exterior case 14 are joined (welded). In addition, in the electricity storage device 30, the tip of the tab lead connected to the electricity storage device main body 31 is led out to the outside of the exterior member 15, but the illustration is omitted.

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.

In the above embodiment, the exterior member 15 is composed of the exterior case 14 obtained by molding the exterior member 1 and the planar exterior member 1 (see FIGS. 2 and 3). The combination is not particularly limited to such a combination. For example, the exterior member 15 may be composed of a pair of planar exterior materials 1, or may be composed of a pair of exterior cases 14. may

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

<Example 1>
After applying a chemical conversion treatment liquid consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol to both sides of an aluminum foil 4 having a thickness of 35 μm, it is dried at 180° C. , formed a chemical conversion film. The amount of chromium deposited on this chemical conversion film was 10 mg/m ² per side.

Next, a 15 μm thick biaxially oriented nylon film (outer layer) 2 is dried on one side of the chemically treated aluminum foil 4 via a two-component curable urethane adhesive (2 μm thick) 5. Laminated (pasted together).

Next, a non-stretched polypropylene film (inner layer) 3 with a thickness of 30 μm is attached to the other surface of the aluminum foil 4 after the dry lamination via a two-component curing type olefin adhesive (thickness of 2 μm) 6. After that, it was pressed between a rubber nip roll and a laminate roll heated to 100°C.

Next, 20 parts by mass of trimethylolethane, 5 parts by mass of blocked isocyanate, 0.1 part by mass of erucic acid amide (lubricant), and polyethylene wax (wax) were added to the surface (outer surface) of the biaxially oriented nylon film (outer layer) 2. After applying 2 g/m ² of a thermal adhesive resin containing 0.4 parts by mass, 0.5 parts by mass of silica (antiblocking agent), 40 parts by mass of toluene, and 34 parts by mass of methylcyclohexane, it is dried at 110°C. Drying was performed in an oven for 60 seconds.

After confirming that the heat-adhesive resin-applied surface had no stickiness, heat aging treatment was performed for 20 days in an environment of 40° C. to obtain the power storage device exterior material 1 shown in FIG. 1 .

In addition, the content of the above-mentioned blocked isocyanate is
• Hexamethylene diisocyanate • Blocking agent: ε-caprolactam • Dissociation catalyst: dibutyltin dilaurate • Solvent: butyl acetate.

Adhesive fixability of the electrical storage device exterior material obtained as described above was evaluated by the following method.

<Creating a simulated battery>
A molding base piece (80 mm × 160 mm) is cut out from each electric storage device exterior material, and this molding base piece is molded using a deep drawing mold and a trimming mold to obtain a width of 40 mm × length of 120 mm. An exterior molding (molding recess: short side 30 mm long side 55 mm x depth 4 mm) was obtained (see Fig. 4). A thermoadhesive resin layer 8 is formed on the lower surface of the planar portion (the right half in FIG. 4) of this exterior molding, and the thermoadhesive resin layer 8 is also formed on the lower surface of the bottom wall of the molding recess. (See Figure 4). Next, a simulated bare cell (width 29 mm×length 50 mm×thickness 4 mm) made by covering the surface of a polyethylene resin block with aluminum foil having a thickness of 20 μm is accommodated in the molding recess, and then an exterior molded product. After superimposing the planar part on the upper surface of the molded recess by folding the center of the center in the longitudinal direction, the superimposed three-sided peripheral flange (5 mm width) is heated and heat-sealed ( A simulated battery 30A was obtained by fusing and sealing the heat-fusible resin layers 3 to each other. The heat sealing was performed using a heat sealing bar whose surface was protected with a Teflon (registered trademark) film.

Next, the simulated battery 30A placed on an aluminum plate with a thickness of 1 mm was placed on a heater heated to 190° C. for 180 seconds, then taken out and allowed to stand at room temperature for 10 minutes. Then, when it was turned upside down and the aluminum plate was grabbed and lifted, the mock battery 30A did not drop (the mock battery was fixed to the aluminum plate). By performing heat treatment at 190° C. for 180 seconds in this way, the blocking agent is dissociated and the heat-adhesive resin layer of the exterior material is adhered to the aluminum plate, so that the simulated battery is made of the aluminum plate (corresponding to the “casing, etc.”). ) could be fixed.

Specific examples of the exterior material for an electricity storage device according to the present invention include, for example,
・It is used as an exterior material for various storage devices such as storage devices such as lithium secondary batteries (lithium ion batteries, lithium polymer batteries, etc.), lithium ion capacitors, and electric double layer capacitors. Further, the power storage device according to the present invention includes all-solid-state batteries in addition to the power storage devices exemplified above.

1... Exterior material for power storage device 2... Heat-resistant resin layer (outer layer)
3... Heat-fusible resin layer (inner layer)
4... Metal foil layer 8... Thermoadhesive resin layer 15... Exterior member 30... Power storage device 31... Power storage device main body

Claims (5)

An exterior material for a power storage device, 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,
A thermoadhesive resin layer is laminated on at least part of the outer surface of the heat-resistant resin layer ,
The thermoadhesive resin constituting the thermoadhesive resin layer is a two-liquid curable thermoadhesive resin containing a main agent and a block isocyanate as a curing agent,
80% or more of the blocking agent of the blocked isocyanate dissociates at a temperature lower than 220°C . 2. The exterior material for an electricity storage device according to claim 1 , wherein the two-liquid curable thermoadhesive resin contains a dissociation catalyst. The exterior material for an electricity storage device according to claim 1 or 2 , wherein the main agent is a resin having a hydroxyl group. An exterior case for an electricity storage device, comprising the molding of the exterior material according to any one of claims 1 to 3 . an electricity storage device main body;
An exterior member comprising the exterior material according to any one of claims 1 to 3 and / or the exterior case according to claim 4 ,
The electricity storage device main body is an electricity storage device that is covered with the exterior member,
An electricity storage device, wherein the electricity storage device is adhered to a housing through the heat-adhesive resin layer .

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