JP5834483B2 - Power storage device exterior materials - Google Patents

Description

  The present invention relates to an exterior material for housing battery components of an electricity storage device.

  BACKGROUND ART Lithium ion batteries that can be made ultra-thin and miniaturized have been actively developed as batteries for use in mobile terminal devices such as mobile phones and laptop computers, video cameras, satellites, and electric vehicles. Capacitors such as lithium ion capacitors, which are capable of rapid charge and discharge and are particularly suitable for energy regeneration applications, are combined with instantaneous voltage drop compensators and lithium ion batteries, taking advantage of the characteristics that can instantly obtain large energy. Therefore, it has been actively developed to be used as a power storage device such as a solar battery. For the exterior materials of these electricity storage devices, a metal can type that is formed by pressing a metal plate or the like and processed into a cylindrical shape or a box shape, and a laminated film (for example, a base layer / There are two types of aluminum foil layer / sealant layer type). When a metal can type is used for the battery exterior material, there are many restrictions on the shape of the electricity storage device itself. On the other hand, when a laminate film type exterior material using an aluminum foil is used, the shape of the electricity storage device itself can be freely selected, and further weight reduction can be achieved.

  In a laminate film type exterior material using an aluminum foil, in order to accommodate contents such as a positive electrode, a separator, a negative electrode, an electrolyte, and a tab, first, the exterior material is cold-molded to form a recess. Each battery component is housed in the recess, and the edges of the exterior material are heat-sealed so that a part of the tab as an electrode terminal is exposed to the outside of the exterior material, thereby assembling as an electricity storage device.

  Conventionally, in a laminate film using an aluminum foil, a polyamide film such as a nylon film has been used as a base material layer as in Patent Document 1 or 2, and a polyolefin film such as polypropylene has been used as a sealant layer.

  In recent years, exterior materials are required to have heat resistance in order to operate an electricity storage device at a higher temperature. In particular, with the miniaturization of power storage devices, these power storage devices are required to have heat resistance that can cope with the reflow temperature so that they can be mounted by reflow using solder in the same manner as electronic components. As for solder reflow, since lead-free solder has become mainstream in recent years, the solder reflow temperature is higher than that of conventional tin-lead solder.

  Here, in the conventional laminate film, a polyamide film such as a nylon film is used as a base material layer, and a polyolefin film such as polypropylene is used as a sealant layer. Therefore, there is a problem that the reflow temperature of lead-free solder, 250 ° C. to 260 ° C., exceeds the melting point of the polypropylene film as the heat seal layer, and the heat seal portion is opened.

JP 2000-334891 A JP 2001-93482 A

  The present invention has been made in view of the problems of the related art, and the purpose thereof is to provide a heat-seal portion even when a laminate film type power storage device exterior material using a metal foil is in a high temperature state during solder reflow or the like. It is an object of the present invention to provide a means capable of maintaining the function as the exterior of the electricity storage device without causing any trouble.

As means for solving the above problems, an exterior device for an electricity storage device according to the present invention is an exterior material for an electricity storage device for housing battery components of an electricity storage device mounted by solder reflow, and is freely deformable. A metal foil layer capable of being laminated, an adhesive layer made of a thermosetting adhesive having at least an epoxy curing component in the system, and laminated on one surface side of the metal foil layer via the adhesive layer , 260 A base material layer made of a heat-resistant resin having a melting point higher than ° C. , and a sealant layer laminated on the other surface side of the metal foil layer and made of a thermoplastic resin having a melting point higher than 260 ° C. Features.
By having both the base material layer and the sealant layer have a melting point higher than the reflow temperature as described above, it is possible to maintain a state as an exterior of the electricity storage device even during solder reflow. Furthermore, even when lead-free solder reflow is considered to require the highest temperature resistance, it is possible to maintain the state of the electricity storage device as an exterior.

Further, in the exterior device for an electricity storage device according to the present invention, the base layer is made of a polyimide resin formed by imidization by reacting an acid anhydride with an amine, and the acid anhydride is pyromellitic acid anhydride. , Biphthalic anhydride, benzophenonetetracarboxylic anhydride, oxydiphthalic anhydride, and hydrofurandiphthalic anhydride, wherein the amine is methoxydiaminobenzene, 4,4′-oxydianiline 3,4′-oxydianiline, 3,3′-oxydianiline, bisdianilinomethane, 3,3′-diaminozenzophenone, p, p-aminophenoxybenzene, p, m-aminophenoxybenzene, m, p-aminophenoxybenzene, m, m-amiophenoxybenzene, chloro-m-aminophenoxybenzene, p-pi Lysine aminophenoxybenzene, m-pyridineaminophenoxybenzene, p-aminophenoxybiphenyl, m-aminophenoxybiphenyl, p-bisaminophenoxybenzodisulfone, m-bisaminophenoxybenzodisulfone, p-bisaminophenoxybenzylketone, m- Bisaminophenoxybenzyl ketone, p-bisaminophenoxybenzylhexafluoropropane, m-bisaminophenoxybenzylhexafluoropropane, m-bisaminophenoxybenzylhexafluoropropane, p-bisaminophenoxybenzylpropane, o-bisaminophenoxybenzyl Propane, m-bisaminophenoxybenzylpropane, p-diaminophenoxybenzylthioether, m-diaminophenoxybenzylthio Ether, characterized in that it comprises indane diamine, spiro busy amine, and at least one diketone diamine.
As mentioned above, there are few heat resistant resins with a melting point higher than 260 ° C. Among them, the use of the above polyimide resin makes it possible to take advantage of the features such as high heat resistance, high insulation, and low thermal expansion, and to satisfy the required characteristics. It becomes possible to provide the material.

Further, in the exterior material for an electricity storage device according to the present invention, the adhesive layer includes an adhesive containing an epoxy curing component in an acrylic material, an adhesive containing an epoxy curing component in a polyimide material, and a rubber material. It includes at least one of an adhesive containing an epoxy curing component .

Further, for an electricity storage device exterior material according to the present invention, the sealant layer, characterized in that consisting of at least one of polyphenylene sulfide and polyamide imide.
As described above, the thermoplastic resin having a melting point higher than 260 ° C. is few among various resins classified as super engineering plastics, but by using the above resin, there is an exterior material that can withstand the temperature during solder reflow. Can be provided.

Further, for an electricity storage device exterior material according to the present invention, the metal foil layer, characterized by comprising a 0.1 wt% to 9.0 wt% of iron content from including a soft aluminum foil.
As described above, the metal foil layer is preferably aluminum in terms of workability such as moisture resistance and spreadability, and cost. Also, aluminum that has been tempered to be soft (O material) in annealing or the like is suitable because it is easily stretched.

Further, for an electricity storage device exterior material according to the present invention, between the sealant layer and the metal foil layer, the corrosion prevention layer for preventing corrosion of the metal foil layer has a that you intervention.
Due to the hydrofluoric acid generated by the hydrolysis reaction between the lithium salt (LiPF6, LiBF4) that is an electrolyte and moisture by performing the above corrosion prevention treatment, the metal foil surface is corroded and the laminate strength between the metal layer films is reduced. Can improve.

  According to the present invention, a laminate film type power storage device exterior material using a metal foil has a function as an exterior of a power storage device without causing a problem in the heat seal portion even in a high temperature state during solder reflow or the like. Can be maintained.

It is sectional drawing which shows embodiment of the exterior material for electrical storage devices which concerns on this invention.

Hereinafter, an example of an embodiment of an exterior material for an electricity storage device of the present invention will be shown and described in detail.
FIG. 1 is a cross-sectional view showing an embodiment of an exterior material for an electricity storage device according to the present invention. 1 is a heat-resistant resin in which a base material layer 10 has a melting point higher than 260 ° C., and is laminated on a metal foil layer 12 with an adhesive layer 11 interposed therebetween. And the corrosion prevention layer 13 is formed on the metal foil layer 12, and the thermoplastic resin which has melting | fusing point higher than 260 degreeC is laminated | stacked as the sealant layer 14 one by one.

(Base material layer)
The base material layer 10 imparts heat resistance in a sealing process when manufacturing the electricity storage device, and plays a role of suppressing the occurrence of pinholes in the metal foil layer 12 during molding processing and distribution. Moreover, the base material layer 10 plays the role which maintains the close_contact | adherence with the metal foil layer 12 also at the high temperature state at the time of solder reflow etc., and maintains the function as an exterior of an electrical storage device.

  As the resin used for the base material layer 10, it can be suitably used as long as it has a melting point higher than 260 ° C. in order to withstand the solder reflow, and in particular, a polyimide having characteristics such as high insulation, chemical resistance, and low thermal expansion can be used. preferable.

  As specific examples of polyimide, polyimide films that are commercially available as trade names such as Kapton (registered trademark), Upilex (registered trademark), and Apical (registered trademark) can be effectively used. Furthermore, a polyimide formed by reacting an acid anhydride with an amine and imidizing can also be effectively used in the present invention. Here, examples of the acid anhydride include pyromellitic acid anhydride, biphthalic acid anhydride, benzophenone tetracarboxylic acid anhydride, oxydiphthalic acid anhydride, hydrofurandiphthalic acid anhydride, and the like. On the other hand, amines include methoxydiaminobenzene, 4,4′-oxydianiline, 3,4′-oxydianiline, 3,3′-oxydianiline, bisdianilinomethane, and 3,3′-diaminozenzo. Phenone, p, p-aminophenoxybenzene, p, m-aminophenoxybenzene, m, p-aminophenoxybenzene, m, m-amiophenoxybenzene, chloro-m-aminophenoxybenzene, p-pyridineaminophenoxybenzene, m -Pyridineaminophenoxybenzene, p-aminophenoxybiphenyl, m-aminophenoxybiphenyl, p-bisaminophenoxybenzidisulfone, m-bisaminophenoxybenzodisulfone, p-bisaminophenoxybenzylketone, m-bisaminophenoxybenzylketone, p Bisaminophenoxybenzylhexafluoropropane, m-bisaminophenoxybenzylhexafluoropropane, m-bisaminophenoxybenzylhexafluoropropane, p-bisaminophenoxybenzylpropane, o-bisaminophenoxybenzylpropane, m-bisaminophenoxybenzyl Examples include propane, p-diaminophenoxybenzylthioether, m-diaminophenoxybenzylthioether, indanediamine, spirobidiamine, and diketonediamine. Moreover, the polyimide film may be formed from the several polyimide layer containing layers, such as a curvature prevention layer and an adhesive bond layer.

(Adhesive layer)
The adhesive layer 11 is not particularly limited as long as it has heat resistance, but an epoxy adhesive, a rubber adhesive, a polyimide adhesive, a polyolefin adhesive, an acrylic adhesive, or the like is used. be able to. Among these, a thermosetting adhesive having at least an epoxy curing component in the system is particularly desirable. This is because the thermoplastic adhesive shows plasticity again at a processing temperature equal to or higher than the melting point, whereas the thermosetting adhesive having an epoxy curing component in the system has a heat resistance by thermosetting after lamination. This is because a cured product that can be improved and has excellent reliability can be provided. As an adhesive containing at least an epoxy curing component, not only an epoxy adhesive, but also an adhesive containing an epoxy curing component in an acrylic material, an adhesive containing an epoxy curing component in a polyimide material, and a rubber material Examples thereof include an adhesive containing an epoxy curing component. Further, it may be modified such as acrylic modification or siloxane modification. However, it is not limited to these, and any adhesive may be used as long as it contains an epoxy curing component even a little.

  The epoxy curing component in the present invention means all curing systems that react with an epoxy compound, for example, a curing reaction between an epoxy compound and an amine, a curing reaction between an epoxy compound and a carboxylic acid, an epoxy compound and a polyamide resin, The curing reaction of the epoxy compound by the latent curing agent, the curing reaction by a combination thereof, and the like can be exemplified, but it is not limited thereto. As thickness of the adhesive bond layer 11 used for this invention, 1-10 micrometers is preferable and 3-7 micrometers is especially preferable.

(Metal foil layer)
As the metal foil layer 12, various metals such as aluminum and stainless steel can be used, and aluminum foil is preferable from the viewpoints of workability such as moisture resistance and spreadability, and cost.
As the aluminum foil, for example, a known aluminum foil can be used, and an aluminum foil containing iron is preferably used from the viewpoint of pinhole resistance and spreadability at the time of molding. 0.1-9.0 mass% is preferable and, as for content of iron of 100 mass% of aluminum foil, 0.5-2.0 mass% is especially preferable. When the iron content is 0.1% by mass or more, pinhole resistance and spreadability are improved. If the iron content is 9.0% by mass or less, flexibility is improved.
Moreover, as an aluminum foil, the soft aluminum foil which performed annealing treatment from the point which can provide the extensibility at the time of shaping | molding is further more preferable.

The thickness of the metal foil layer 12 is preferably 9 to 200 μm, particularly preferably 15 to 100 μm, from the viewpoint of barrier properties, pinhole resistance, and workability.
A particularly preferable metal foil layer 12 is a soft aluminum foil having a thickness of 15 to 150 μm and subjected to an annealing treatment. Specifically, 8021-0 material and 8079-0 material are preferable in the JIS standard.

The aluminum foil used for the metal foil layer 12 is preferably an aluminum foil that has been subjected to a degreasing treatment from the viewpoint of resistance to electrolytic solution. In addition, an aluminum foil whose surface is etched by degreasing treatment may be used, but from the viewpoint of simplifying the manufacturing process, it is preferable to use an aluminum foil whose surface is not etched.
The degreasing treatment is roughly classified into a wet type and a dry type, and the dry type is preferable from the viewpoint of simplifying the manufacturing process.

  Examples of the dry type degreasing treatment include a method of performing a degreasing treatment by increasing the treatment time in the step of annealing the aluminum foil. In addition to the degreasing treatment, frame treatment, corona treatment and the like can be mentioned. Furthermore, a degreasing treatment in which pollutants are oxidatively decomposed and removed by active oxygen generated by irradiating ultraviolet rays having a specific wavelength is also included.

  Examples of the wet type degreasing treatment include acid degreasing and alkali degreasing. Examples of the acid used for acid degreasing include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, and hydrofluoric acid. These acids may be used alone or in combination of two or more. As an alkali used for alkali degreasing, sodium hydroxide etc. are mentioned as a thing with a high etching effect, for example. Moreover, what mixed the weak alkali type | system | group and surfactant is mentioned as an alkali. The wet type degreasing treatment is performed by an immersion method or a spray method.

  In the present invention, the wet type degreasing process or the process up to the etching level is performed, and the dry type degreasing process is performed to obtain sufficient electrolytic solution resistance. That is, in the annealing process performed to soften the aluminum foil, sufficient electrolytic solution resistance can be obtained even with a degreasing process performed simultaneously.

(Corrosion prevention layer)
The corrosion prevention layer 13 serves to firmly adhere the metal foil layer 12 and the sealant layer 14 and to protect the metal foil layer 12 from an electrolytic solution and hydrofluoric acid generated from the electrolytic solution.
The corrosion prevention layer 13 can be formed by, for example, a hydrothermal conversion treatment, an anodizing treatment, a chemical conversion treatment, or a combination of these treatments.
Examples of the hydrothermal modification treatment include boehmite treatment in which an aluminum foil is immersed in boiling water to which triethanolamine is added. Examples of the anodizing treatment include alumite treatment. Examples of the chemical conversion treatment include a chromate treatment, a zirconium treatment, a titanium treatment, a vanadium treatment, a molybdenum treatment, a calcium phosphate treatment, a strontium hydroxide treatment, a cerium treatment, a ruthenium treatment, and various chemical conversion treatments composed of these mixed phases. Further, these chemical conversion treatments are not limited to wet types, and coating types in which these treatment agents are mixed with resin components can also be applied.
As described above, among these corrosion prevention treatments, the effect is the highest, and the coating type chromate treatment is most preferable from the viewpoint of waste liquid treatment.

  In addition to the chemical conversion treatment described above, the corrosion prevention layer 13 can be formed only by a pure coating technique. This method uses a sol of a rare earth element-based oxide such as cerium oxide having an average particle size of 100 nm or less as a material that has an aluminum corrosion prevention effect (inhibitor effect) and is also suitable from an environmental viewpoint. is there. By using this method, it is possible to impart a corrosion prevention effect to a metal foil such as an aluminum foil even by a general coating method.

(Sealant layer)
The sealant layer 14 is a layer made of a heat-welding film constituting the inner layer of the electricity storage device exterior material 1, and the sealant layers 14 are thermally welded together when the electricity storage device is assembled.
The component constituting the sealant layer 14 is a resin having a melting point higher than 260 ° C. capable of withstanding the solder reflow temperature, and further needs to be a thermoplastic resin, not a thermosetting resin, in order to perform heat sealing. . As such a resin, it is preferable to use at least one of polyphenylene sulfide (PPS), polyamide imide (PAI), and thermoplastic polyimide, which are classified as super engineering plastics but are more resistant to high temperatures. .

<Method for manufacturing exterior material for power storage device>
Next, although the manufacturing method of the exterior | packing material 1 for electrical storage devices of this invention shown in FIG. 1 is described, it is not limited to this manufacturing method.

(Lamination process of corrosion prevention layer on metal foil layer)
The corrosion prevention layer 13 is formed by applying a coating-type chromate treatment liquid to at least the sealant layer 14 side of the metal foil layer 12 and performing drying, curing, and baking.
As a coating method, a known method is used, and examples thereof include a gravure coater, a gravure reverse coater, a roll coater, a reverse roll coater, a die coater, a bar coater, a kiss coater, and a comma coater.
In addition, although the metal foil layer 12 can fully satisfy | fill a function even if it uses an untreated metal foil, you may use the metal foil which performed the degreasing | defatting or oxide removal process by the wet type or the dry type.
The corrosion prevention layer 13 is indispensable for providing the electrolyte solution resistance on the sealant layer 14 side, but the base layer 10 side may not be coated.

(Bonding process of base material layer and metal foil layer)
In the method of laminating a heat-resistant resin having a melting point higher than 260 ° C. that becomes the base material layer 10, the base material layer 10 is laminated on the metal foil layer 12 on which the corrosion prevention layer 13 is laminated via the adhesive layer 11.
As a bonding method, the adhesive exemplified as the adhesive layer 11 is used and laminated by various lamination methods such as dry lamination.

(Lamination process of sealant layer)
A sealant layer 14 is laminated on a laminate composed of the base material layer 10, the adhesive layer 11, the metal foil layer 12, and the corrosion prevention layer 13. The sealant layer 14 can be laminated by itself without using a new adhesive layer by using a thermoplastic resin whose material itself is adhesive. As a method of laminating the sealant layer 14, there are a method of extruding a thermoplastic resin and a method of laminating, and a method of forming a thermoplastic resin in advance and performing a heat lamination.
In addition, as a method for laminating the sealant layer 14, the material of the adhesive layer 11 used for adhesion of the base material layer 10 and the metal foil layer 12 can be used to laminate by a method such as dry lamination.

  Although the test example of this invention is shown below, it is not necessarily limited to this test.

[Materials used]
Common materials used in the following test examples are as follows.
<Base material layer>
Polyimide film (25 μm).
<Adhesive layer>
Epoxy thermosetting adhesive <metal foil layer>
An annealed soft aluminum foil 8079 material (40 μm).
<Aluminum protective layer>
Coating type chromate treatment <sealant layer>
Thermoplastic polyimide film (50μm)

[Creation of energy storage device exterior materials (lithium ion battery exterior materials)]
<Example 1>
In this example, an exterior material for an electricity storage device was prepared as follows.
First, a coating-type chromate treatment liquid was applied on an aluminum foil by microgravure coating, and a corrosion treatment layer was laminated on the aluminum foil coil by performing a baking treatment at 150 to 250 ° C. in a drying unit.
Subsequently, the base material layer was laminated | stacked on the surface on the opposite side to the corrosion prevention layer of an aluminum foil with the epoxy-type thermosetting adhesive by the dry lamination method. The laminated body which laminated | stacked these base material layers, and the thermoplastic polyimide film were heat-laminated by the lamination temperature of 300 degreeC, and the exterior material for electrical storage devices was created.
<Comparative Example 1>

Lamination was performed using nylon as the base material layer of Example 1 and using a urethane-based adhesive as the adhesive layer. Further, polypropylene was used for the sealant layer, and heat lamination was performed via maleic acid-modified polypropylene.
<Evaluation>

  The following evaluation was performed with respect to the obtained exterior material for an electricity storage device.

(Solder reflow evaluation)
The obtained power storage device exterior material was folded and heat-sealed to create a pouch shape. Subsequently, it was put into a conveyor-type reflow furnace for 10 seconds under a temperature condition of 260 ° C. for performing solder reflow, and then the opening of the heat seal portion and strength deterioration were confirmed.

  As a result of making and evaluating Example 1 and Comparative Example 1, the exterior material for the electricity storage device of Example 1 is in a good state with no change in appearance even when it is put into solder reflow and without opening the heat seal part. Met. On the other hand, the exterior material for an electricity storage device of Comparative Example 1 was in a state where both the nylon film and the polypropylene film were dissolved by the high heat during solder reflow, and the heat seal part was opened, so that it could not be used as an electricity storage device.

  As described above, according to the present invention, in the laminate film type power storage device exterior material using the metal foil, there is a problem that the heat seal portion of the exterior material is opened even in a high temperature state such as during solder reflow. Therefore, it is possible to provide a power storage device exterior material that can maintain the function of the power storage device as an exterior.

1: External packaging material for electricity storage device 10: Base material layer 11: Adhesive layer 12: Metal foil layer 13: Corrosion prevention layer 14: Sealant layer

Claims (6)

An exterior material for an electricity storage device for storing battery components of the electricity storage device mounted by solder reflow,
A metal foil layer that can be freely deformed,
An adhesive layer comprising a thermosetting adhesive having at least an epoxy curing component in the system;
A base material layer made of a heat-resistant resin laminated on one surface side of the metal foil layer via the adhesive layer and having a melting point higher than 260 ° C;
A sealant layer, which is laminated on the other surface side of the metal foil layer and made of a thermoplastic resin having a melting point higher than 260 ° C .;
An exterior material for an electricity storage device, comprising: The base material layer comprises a polyimide resin formed by reacting an acid anhydride and an amine to imidize,
The acid anhydride includes at least one of pyromellitic acid anhydride, biphthalic acid anhydride, benzophenone tetracarboxylic acid anhydride, oxydiphthalic acid anhydride, and hydrofurandiphthalic acid anhydride,
The amine is methoxydiaminobenzene, 4,4′-oxydianiline, 3,4′-oxydianiline, 3,3′-oxydianiline, bisdianilinomethane, 3,3′-diaminozenzophenone, p, p-aminophenoxybenzene, p, m-aminophenoxybenzene, m, p-aminophenoxybenzene, m, m-amiophenoxybenzene, chloro-m-aminophenoxybenzene, p-pyridineaminophenoxybenzene, m-pyridine Aminophenoxybenzene, p-aminophenoxybiphenyl, m-aminophenoxybiphenyl, p-bisaminophenoxybenzidisulfone, m-bisaminophenoxybenzodisulfone, p-bisaminophenoxybenzylketone, m-bisaminophenoxybenzylketone, p- Bisaminoph Enoxybenzyl hexafluoropropane, m-bisaminophenoxybenzyl hexafluoropropane, m-bisaminophenoxybenzyl hexafluoropropane, p-bisaminophenoxybenzylpropane, o-bisaminophenoxybenzylpropane, m-bisaminophenoxybenzyl The exterior material for an electrical storage device according to claim 1, comprising at least one of propane, p-diaminophenoxybenzylthioether, m-diaminophenoxybenzylthioether, indanediamine, spirobidiamine, and diketonediamine. The adhesive layer includes at least one of an adhesive containing an epoxy curing component in an acrylic material, an adhesive containing an epoxy curing component in a polyimide material, and an adhesive containing an epoxy curing component in a rubber material. The exterior material for an electricity storage device according to claim 1 or 2, characterized in that   The said sealant layer consists of at least any one of polyphenylene sulfide and polyamideimide, The exterior | packing material for electrical storage devices as described in any one of Claim 1 to 3 characterized by the above-mentioned. The metal foil layer is, power storage according to any one of claims 1 4, characterized by comprising a 0.1 wt% to 9.0 wt% of iron content from including a soft aluminum foil Device exterior materials. Between the sealant layer and the metal foil layer, for an electricity storage device according to any one of claims 1 to 5 corrosion prevention layer for preventing corrosion of the metal foil layer is characterized that you mediated Exterior material.

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