JP2012238514A - Manufacturing method of sheath material for battery and secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a sheath material for a battery which manufactures a sheath material for a battery with a small number of scratches, rubbed areas, wrinkles, and thermal wrinkles, and to provide a secondary battery having the sheath material for the battery with a small number of the scratches, the rubbed areas, the wrinkles, and the thermal wrinkles.SOLUTION: In a manufacturing method of a sheath material for a battery 10 of this invention, an outer layer 11, reinforcing a barrier layer 13, is provided on one surface in the thickness direction of the barrier layer 13 preventing the intrusion of liquid components, and a corrosion prevention layer 14 having corrosion resistance is formed on a surface of the barrier layer 13 which is the opposite side of the surface where the outer layer 11 is provided. An inner layer 16 is fixed to a surface of the corrosion prevention layer 14 which is the opposite side of the surface that contacts with the barrier layer 13.

Description

  The present invention relates to a method for manufacturing a battery case and a secondary battery having the battery case.

  Lithium ion batteries that can be made ultra-thin and miniaturized have been actively developed as batteries used in personal digital assistants such as personal computers and mobile phones, video cameras, and satellites. As a battery exterior material used for a lithium ion battery, for example, a multilayer film in which an aluminum foil layer, a heat-sealing film, or the like is laminated is generally used. By adopting a multilayer film as a battery exterior material, unlike a conventional metal can, the battery shape can be freely selected with light weight.

  The lithium ion battery has a positive electrode material, a negative electrode material, and an electrolyte layer inside the exterior material. The electrolyte layer provided in the lithium ion battery includes an electrolytic solution in which an electrolyte (lithium salt) is dissolved in an aprotic solvent having penetrating power, or a polymer gel in which the electrolytic solution is impregnated. Examples of the aprotic solvent having penetrating power include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

  As the lithium salt that is an electrolyte, a salt such as LiPF6 or LiBF4 is used. These salts generate hydrofluoric acid by a hydrolysis reaction with moisture. The hydrofluoric acid corrodes the metal surface of the aluminum foil layer and reduces the adhesive strength between the layers of the multilayer film.

  The aluminum foil layer provided on the exterior material functions as a barrier layer that blocks moisture from entering from the outside to the inside of the lithium ion battery and prevents hydrolysis reaction between the lithium salt and moisture. At the peripheral edge of the multilayer film, the cut surface of the multilayer film is exposed, and there is a possibility that liquid enters and exits from the gaps between the layers on the cut surface of the multilayer film. When the solvent of the electrolytic solution passes through the heat-fusible film layer, the adhesive strength between the aluminum foil layer and the heat-fusible film layer is lowered, and there is a possibility that the electrolytic solution may eventually leak. For this reason, by increasing the interlayer adhesion strength between the conventional aluminum foil layer and the heat-fusible film, it is possible to prevent the electrolyte from leaking or fluoric acid from being generated and the exterior material being corroded.

  In some cases, a corrosion prevention layer is formed on the inner surface of the exterior material for the purpose of preventing corrosion of the exterior material. Examples of the method for forming the corrosion prevention layer include chemical conversion treatment and anodization. From the viewpoint of the cost for forming the corrosion prevention layer, chemical conversion treatment is often used as a method for forming the corrosion prevention layer. Furthermore, as a chemical conversion treatment method, there are an immersion type and a coating type. In general, a coating type chemical conversion treatment is employed because the chemical solution is easily managed and the quality of the corrosion prevention layer is easily stabilized.

  Patent Document 1 discloses a method for producing a polymer battery packaging material used as a packaging material for a secondary battery. The packaging material for a polymer battery described in Patent Document 1 is formed by subjecting one surface of aluminum to a chemical conversion treatment, laminating the surface of the aluminum subjected to chemical conversion treatment and a base material, and an untreated surface not subjected to chemical conversion treatment in aluminum. It is manufactured by subjecting to a chemical conversion treatment, and heat-sealing (thermal laminating) a heat seal layer on the surface opposite to the surface on which the substrate is laminated. According to the manufacturing method described in Patent Document 1, it is possible to suppress generation of thermal wrinkles in aluminum due to heat applied when the chemical conversion treatment is performed.

JP 2001-176461 A

The manufacturing method described in Patent Document 1 has two steps of chemical conversion treatment for one surface of aluminum and chemical conversion treatment for the other surface of aluminum. Thereby, according to the manufacturing method of patent document 1, generation | occurrence | production of a heat wrinkle is suppressed when performing the chemical conversion treatment with respect to the said other surface. However, in the step of performing the chemical conversion treatment on the one surface, the aluminum foil is conveyed alone and the chemical conversion treatment film is formed at a temperature of 170 ° C. to 200 ° C. There is.
Furthermore, in order to perform the chemical conversion treatment on the one surface of the aluminum, since the aluminum is transported alone, there is a possibility that scratches, creases, other wrinkles, etc. may occur in addition to the thermal wrinkles.

  For this reason, in the manufacturing method described in Patent Document 1, although generation of heat wrinkles can be partially mitigated, there is still a possibility that heat wrinkles may still be generated in aluminum serving as a barrier layer. Furthermore, with the manufacturing method described in Patent Document 1, it has been difficult to alleviate wrinkles other than scratches and cosmetics on the barrier layer and thermal wrinkles on the barrier layer.

  The present invention has been made in view of the above-described circumstances, and the object thereof is a method for manufacturing a battery outer packaging material capable of manufacturing a battery outer packaging material with few scratches, scratches, wrinkles, and heat wrinkles, and It is an object of the present invention to provide a secondary battery having a battery exterior material with few scratches, scratches, wrinkles, and heat wrinkles.

In order to solve the above problems, the present invention proposes the following means.
According to the method of manufacturing the battery outer packaging material of the present invention, an outer layer that reinforces the barrier layer is provided on one surface in the thickness direction of the barrier layer that prevents intrusion of a liquid component, and the outer layer is provided in the barrier layer. A corrosion prevention layer having corrosion resistance is formed on a surface opposite to the side, and an inner layer is fixed to a surface opposite to the side in contact with the barrier layer in the corrosion prevention layer. It is a manufacturing method.

According to the present invention, after the barrier layer on which the corrosion prevention layer is not formed and the outer layer are laminated, the corrosion prevention layer is formed on the surface of the barrier layer on which the outer layer is not laminated. As a result, the barrier layer is reinforced by the outer layer before the corrosion prevention layer is formed, and is protected from scratches and cosmetics. Thereby, scratches, creases and wrinkles can be suppressed as compared with the case where the barrier layer is conveyed alone.
Furthermore, since the step of drying the corrosion prevention layer to form the corrosion prevention layer on the barrier layer is performed after the outer layer is laminated on the barrier layer, the barrier layer is supported by the outer layer during the drying of the corrosion prevention layer. Yes. For this reason, generation | occurrence | production of a heat wrinkle can be suppressed in a barrier layer.

The corrosion prevention layer preferably contains a fluorine component.
The corrosion prevention layer may be formed by applying a liquid containing a component resistant to hydrofluoric acid to the opposite surface of the barrier layer, and applying the liquid applied to the opposite surface to 200 ° C. or less. It is preferably formed by drying at a temperature of 5 to form a film.

  The outer layer is preferably made of a biaxially stretched polyamide film having a thickness of 6 μm to 40 μm.

  The barrier layer is preferably made of a soft aluminum foil having a thickness of 10 μm to 150 μm. The soft aluminum foil may contain iron.

  The secondary battery of this invention is a secondary battery characterized by having the battery exterior material manufactured by the manufacturing method of the battery exterior material of this invention.

According to the method for manufacturing the battery outer packaging material of the present invention, since the corrosion prevention layer is formed on the barrier layer after the outer layer is laminated on the barrier layer, the barrier layer can be reinforced by the outer layer. -Wrinkles and heat wrinkles can be reduced.
In addition, according to the battery packaging material and the secondary battery of the present invention, scratches, wrinkles, and wrinkles in the barrier layer and heat wrinkles are reduced, so that the possibility of electrolyte leakage can be further reduced.

It is sectional drawing which shows the battery exterior material of one Embodiment of this invention. It is a flowchart which shows the manufacturing method of the battery cladding | exterior_material of one Embodiment of this invention. (A) thru | or (d) is a figure for demonstrating the manufacturing process in the manufacturing method.

(Configuration of battery exterior materials)
The structure of the battery exterior material of one embodiment of the present invention will be described.
FIG. 1 is a cross-sectional view showing the battery exterior material of the present embodiment.
1 is a laminate in which an adhesive layer X12, a barrier layer 13, a corrosion prevention layer 14, an adhesive layer Y15, and an inner layer 16 are laminated on one surface of an outer layer 11 in this order.

<Outer layer 11>
The outer layer 11 imparts heat resistance in a sealing process at the time of manufacturing a lithium ion battery or the like, and further serves to suppress the generation of pinholes that may occur during processing or distribution of the lithium ion battery or the like. As the outer layer 11, it is preferable to use an insulating resin. Examples of the resin layer having insulating properties include stretched or unstretched films such as polyester film, polyamide film, and polypropylene film. When a stretched polyamide film or a stretched polyester film is used as the outer layer 11, the moldability of the outer layer 11 is good, and the molded outer layer 11 is excellent in heat resistance, pinhole resistance, and insulation. Furthermore, the biaxially stretched polyamide film is particularly preferable as a material for the outer layer 11 because mechanical properties such as tensile strength and elongation contribute to improvement of moldability.
The outer layer 11 may contain various additives such as a flame retardant, slip agent, anti-blocking agent, antioxidant, light stabilizer, and tackifier.

The outer layer 11 may be a single layer film or a laminated film in which two or more layers are laminated. The outer layer 11 may be a layer in which a resin such as polyethylene terephthalate (PET) that is insoluble in the electrolytic solution is laminated on the resin having the insulating property. Further, the outer layer 11 may be a layer in which a resin component insoluble in the electrolytic solution is coated with the insulating resin. The outer layer 11 thus laminated or coated can suitably prevent the electrolyte from leaking to the outside when the electrolyte is attached.
The thickness of the outer layer 11 is preferably 6 to 40 μm, and more preferably 10 to 25 μm. When the thickness of the outer layer 11 is less than 6 μm, the anti-pinhole property and the insulating property are lowered, and further, the effect of preventing the barrier layer 13 from being broken at the time of molding becomes insufficient. On the other hand, when the thickness of the outer layer 11 exceeds 40 μm, the load on the molding machine increases when the outer layer 11 is molded, and the amount of resin used increases.

<Adhesive layer X>
The adhesive layer X12 is a layer that bonds the outer layer 11 and the barrier layer 13 together.
The adhesive layer X12 on the outer layer 11 side is preferably a polyurethane adhesive mainly composed of polyester polyol, polyether polyol, or acrylic polyol. 1-10 micrometers is preferable and, as for the thickness of the contact bonding layer X12, 3-7 micrometers is more preferable.

<Barrier layer>
The barrier layer 13 is a layer that prevents moisture and other liquid components from entering and exiting from the outside of a lithium ion battery or the like. The barrier layer 13 is preferably a metal foil such as an aluminum or stainless steel row. Specifically, an aluminum foil is more preferable as the material of the barrier layer 13 in terms of specific gravity, specific strength, and spreadability. When the barrier layer 13 is formed of an aluminum foil, the battery outer packaging material 10 is lighter and stronger because the specific gravity is small and the specific strength is large.
Further, since the aluminum foil has a high spreadability, if the barrier layer 13 is formed using the aluminum foil, pinholes or the like hardly occur when the barrier layer 13 is formed.

As aluminum used as the material of the barrier layer 13, a soft aluminum foil is preferable. As a specific material of aluminum used as the material of the barrier layer 13, an aluminum foil tempered to be soft (O material) in an annealing process or the like can be given.
In addition, it is particularly preferable that an aluminum alloy containing iron is adopted as the material of the barrier layer 13 because pinholes hardly occur and the extensibility during molding is high. In this case, the content of iron in the aluminum foil (100% by mass) is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. When the iron content is 0.1% by mass or more, pinhole property and ductility are improved. If the iron content is 9.0% by mass or less, flexibility is improved.

  The thickness of the barrier layer 13 is preferably 10 to 150 μm. If the thickness of the barrier layer 13 is 10 μm or more, it is easy to suppress the occurrence of pinholes and the like during molding. If the thickness of the barrier layer 13 is 150 μm or less, the stress at the time of molding can be further reduced and the burden on the molding machine can be reduced, so that productivity is improved. Furthermore, the thinner the barrier layer 13 is, the smaller the mass of the battery outer packaging material 10 is, and the mass energy density of the entire battery is improved.

<Corrosion prevention layer>
The corrosion prevention layer 14 is provided on the inner layer 16 side of the barrier layer 13 and is in close contact with the barrier layer 13 and the adhesive layer Y15. The corrosion prevention layer 14 serves to protect the barrier layer 13 from hydrofluoric acid generated by the reaction between the salt in the electrolyte and the moisture that has entered the electrolyte.
The formation of the corrosion prevention layer 14 is preferably performed by chemical conversion treatment or anodic oxidation. A method for forming the corrosion prevention layer 14 will be described later.

The coating weight of the corrosion prevention layer 14 is preferably 5 to 1000 mg / m ² . When the coating weight is less than 5 mg / m ^2, it becomes difficult to uniformly cover the surface of the aluminum foil with the corrosion prevention layer 14. For this reason, the film thickness uniformity is lowered, the adhesion and hydrofluoric acid resistance are locally impaired, and pinholes and the like are likely to occur when stretched during molding. On the other hand, when the coating weight of the corrosion prevention layer 14 exceeds 1000 mg / m ² , drying tends to be insufficient, and the performance in the thickness direction is biased within the coating, and adhesion and hydrofluoric acid resistance are impaired.

<Adhesive layer Y>
The adhesive layer Y15 is a layer that bonds the corrosion prevention layer 14 and the inner layer 16 together. The thickness of the adhesive layer Y15 is preferably 1 to 40 um. The component of the adhesive layer Y15 is preferably a polyolefin resin or an acid-modified polyolefin resin.
Examples of the polyolefin resin include low density, medium density, and high density polyethylene; ethylene-α olefin copolymer; homo, block, or random polypropylene; propylene-α olefin copolymer. These polyolefin resin may be used individually by 1 type, and may use 2 or more types together.

In the present specification, the acid-modified polyolefin resin means a polyolefin resin modified by graft polymerization of an acid. The acid-modified polyolefin resin is preferably a maleic anhydride-modified polyolefin resin modified by graft polymerization of maleic anhydride to the polyolefin resin.
The polyolefin resin or acid-modified polyolefin resin used as the material for the adhesive layer Y15 may be a dispersion type dispersed in an organic solvent. In this case, various additives effective for adhesion, an isocyanate compound or a derivative thereof, and a silane coupling material may be blended.
In addition, the adhesive layer Y15 is formed by curing a two-component curing type polyurethane adhesive in which a bifunctional or higher aromatic or aliphatic isocyanate is allowed to act as a curing agent on a main component such as polyester polyol, polyether polyol, or acrylic polyol. It may be a layer.

<Inner layer>
The inner layer 16 is a layer that is thermally welded by heat sealing in the battery outer packaging material 10 and functions as a sealant. Examples of the material of the inner layer 16 include a polyolefin resin and a film made of an acid-modified polyolefin resin obtained by modifying a polyolefin resin by graft polymerization of maleic anhydride or the like. Among these, a film made of an acid-modified polyolefin resin is preferable, and a film made of a maleic anhydride-modified polyolefin resin modified by graft polymerization of maleic anhydride is more preferable.

  Examples of the polyolefin resin include low density, medium density, and high density polyethylene; ethylene-α olefin copolymer; homo, block, or random polypropylene; propylene-α olefin copolymer. These polyolefin resin may be used individually by 1 type, and may use 2 or more types together.

  The inner layer 16 may be a single layer film or a multilayer film, and can be appropriately selected according to the function required for the inner layer 16. For example, when moisture resistance is important as a function of the inner layer 16, a multilayer film in which a resin such as an ethylene-cycloolefin copolymer or polymethylpentene is interposed can be used. The inner layer 16 may contain various additives such as a flame retardant, slip agent, anti-blocking agent, antioxidant, light stabilizer, and tackifier. 10-100 micrometers is preferable and, as for the thickness of the inner layer 16, 20-50 micrometers is more preferable.

(Method for producing battery exterior material)
Next, the method for manufacturing the battery outer packaging material of the present embodiment will be described by taking the case of manufacturing the above-described battery outer packaging material 10 as an example. FIG. 2 is a flowchart showing a method for manufacturing the battery outer packaging material of the present embodiment. FIG. 3A to FIG. 3D are process explanatory views for explaining a manufacturing process of the battery exterior material of the present embodiment.

(Lamination of outer layer and barrier layer)
In the present embodiment, first, the outer layer 11 is provided on the barrier layer 13 by bonding the barrier layer 13 and the outer layer 11 (step S1 shown in FIG. 2).
As shown in FIG. 3A, the barrier layer 13 and the outer layer 11 are bonded together by an adhesive layer X12. As a method of bonding the barrier layer 13 and the outer layer 11, methods such as dry lamination, non-solvent lamination, wet lamination, and the like can be used. In this case, it is preferable to bond them together with a polyurethane-based adhesive mainly composed of polyester polyol, polyether polyol, and acrylic polyol.

  In the present embodiment, an adhesive is applied to the outer layer 11, the adhesive applied to the outer layer 11 is dried, and then the barrier layer 13 is laminated so as to sandwich the adhesive therebetween. Thereby, as shown in FIG.3 (b), the laminated body which consists of the outer layer 11, the contact bonding layer X12, and the barrier layer 13 is formed. The laminated body that has been laminated is wound into a roll, for example, and sent to the next step.

  Which of the outer layer 11 and the barrier layer 13 is applied with an adhesive can be selected as appropriate. When the adhesive is applied to the outer layer 11, it is not the barrier layer 13 but the outer layer 11 that is transported to dry the adhesive, so that the number of steps for moving the barrier layer 13 is small. For this reason, when an adhesive is applied to the outer layer 11, the possibility of scratches, creases and wrinkles occurring in the barrier layer 13 can be kept low.

  Moreover, in order to dry an adhesive agent, it is necessary to apply heat, but when an adhesive agent is applied to the outer layer 11, the barrier layer 13 is not heated in the step of drying the adhesive agent. For this reason, in the process of laminating | stacking the outer layer 11 and the barrier layer 13, possibility that a thermal wrinkle will generate | occur | produce in the barrier layer 13 can be suppressed low. Further, no thermal wrinkle is generated in the barrier layer 13 at a temperature (about 60 ° C.) applied by dry lamination described later.

(Corrosion prevention layer formation on the barrier layer)
Subsequently, as shown in FIG. 3C, the corrosion prevention layer 14 is formed on the surface of the barrier layer 13 opposite to the surface on which the outer layer 11 is provided (step S2 shown in FIG. 2).
In order to form the corrosion prevention layer 14, a chemical conversion treatment or the like can be performed. As the chemical conversion treatment, for example, a general system in which a fluoride, a phosphoric acid compound, a resin or the like is added to a corrosion-resistant element such as Cr, Zr, Ti, or Ce can be used. When the corrosion prevention layer 14 is formed by the chemical conversion treatment, corrosion of the barrier layer 13 due to hydrofluoric acid is suppressed, and good hydrofluoric acid resistance is obtained.
Examples of the formation method of the corrosion prevention layer 14 by chemical conversion include immersion type (dip method), spray method, coating type (coating method) and the like. Among these, the coating type chemical conversion treatment is preferable as a method for forming the corrosion prevention layer 14 because the treatment liquid can be easily adjusted and maintained.

  The chemical conversion treatment is preferably a treatment using a highly volatile fluorine component. In the chemical conversion treatment, the fluorine component acts to remove the surface oxide of the aluminum foil, which is the material of the barrier layer 13, by etching. Thereby, the process of dropping the surface oxide of the aluminum foil and the process of forming the corrosion prevention layer 14 can be performed in the same process, and the corrosion prevention layer 14 having good adhesion and corrosion resistance can be obtained.

  In addition, before forming the corrosion prevention layer 14, you may perform the pretreatment which degreases the surface of an aluminum foil or removes a surface oxide film from the surface of an aluminum foil. In this case, if the immersion type (dip method) is adopted, the pretreatment can be performed without requiring a large-scale change of the equipment for forming the corrosion prevention layer 14 only by adding a chemical bath for the pretreatment. It can be a production line.

  When the chemical conversion treatment is performed, first, a chemical conversion treatment liquid is applied to the surface of the barrier layer 13 opposite to the side on which the outer layer 11 is formed. As a method for applying the chemical conversion solution, 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.

  Next, the applied chemical conversion liquid is dried. The temperature and time for drying the chemical conversion liquid are set to the optimum temperature and time according to the type of chemical conversion liquid. In this embodiment, the volatile component at the time of drying does not adhere to the back surface of the barrier layer 13 (non-processed surface opposite to the surface coated with the chemical conversion liquid). For this reason, there is no adhesion of foreign matter or the like on the back surface of the barrier layer 13, and the adhesion is maintained high.

Further, the barrier layer 13 is reinforced by the outer layer 11 and supported by the outer layer 11 until the chemical conversion treatment liquid is applied and dried. For this reason, the outer layer 11 protects the barrier layer 13 from scratches, scratches, and wrinkles.
Furthermore, even if heat is applied to the barrier layer 13 in order to dry the chemical conversion treatment solution applied to the barrier layer 13, the barrier layer 13 is reinforced by the outer layer 11, so that the possibility of thermal wrinkles is low.

Further, when the corrosion prevention layer 14 contains a fluorine component, the fluorine component may volatilize when the film that becomes the corrosion prevention layer 14 is dried. When the production method of the present invention is not used, the volatilized fluorine component may be scattered in a drying furnace for drying the film to be the corrosion prevention layer 14 and adhere to the barrier layer 13. In the case where the barrier layer 13 is made of aluminum, the aluminum to which the fluorine component is attached becomes aluminum fluoride, which causes a reduction in the adhesive strength of the adhesive layer X12 and the like on the outer layer 11 side.
However, when the manufacturing method of this embodiment is used, the surface of the barrier layer 13 where the corrosion prevention layer 14 is not formed is already protected by the outer layer 11 before the corrosion prevention layer 14 is formed. The fluorine component does not adhere to the barrier layer 13.

  The temperature for drying the corrosion prevention layer 14 is preferably 200 ° C. or less. In this embodiment, since the corrosion prevention layer 14 is dried after the outer layer 11 is laminated, the outer layer 11 is also heated at the same time when the corrosion prevention layer 14 is dried.

  In order to employ a biaxially stretched polyamide film as the outer layer 11, it is preferable to dry the corrosion prevention layer 14 at a temperature equal to or lower than the melting temperature of the biaxially stretched polyamide film. Specifically, when nylon 6 is employed as the biaxially stretched polyamide film that is the material of the outer layer 11, the melting temperature of nylon 6 is 225 ° C., so the corrosion prevention layer 14 is formed at a temperature lower than 225 ° C. It is preferable to dry. In order to suppress the outer layer 11 from being deteriorated by heat, it is more preferable to dry the corrosion prevention layer 14 at a temperature 20 degrees or more lower than the melting temperature of the biaxially stretched polyamide film. For example, when nylon 6 is adopted as the material of the outer layer 11, the drying temperature of the corrosion prevention layer 14 is more preferably 40 ° C. or higher and 200 ° C. or lower, and further preferably 50 ° C. or higher and 170 ° C. or lower.

  In the step of forming the corrosion prevention layer 14, two or more kinds of treatments can be selected and combined as appropriate from chemical conversion treatment, anodization, corrosion-resistant resin coating, and the like.

(Inner layer lamination process)
Subsequently, as shown in FIG. 3D, the inner layer 16 is laminated via the adhesive layer Y15 on the laminate on which the corrosion prevention layer 14 has been formed by the chemical conversion treatment, and fixed (step S3 shown in FIG. 2). ). Examples of the method of laminating the inner layer 16 include a method of extruding a resin, a method of coating as a dispersion, and a method of bonding using an adhesive.
When the resin is extruded and used, the adhesive layer Y15 is extruded and laminated on the corrosion prevention layer 14, and the inner layer 16 obtained by an inflation method or a cast method is further laminated on the adhesive layer Y15.

  When coating as a dispersion, an acid-modified polyolefin resin dispersion is prepared and coated on the corrosion prevention layer 14. Thereafter, the solvent is volatilized at a temperature equal to or higher than the melting point of the acid-modified polyolefin resin, and the acid-modified polyolefin resin is melt-softened and baked. Further, the inner layer 16 is laminated by a heat treatment such as thermal lamination.

Moreover, when laminating | stacking using an adhesive agent, the material similar to the material used at the process of bonding the outer layer 11 and the barrier layer 13 can be used. As a method for applying the adhesive, a method similar to the method for applying the chemical conversion treatment liquid exemplified above in the description of the step of laminating the corrosion prevention layer 14 on the barrier layer 13 can be employed.
The battery outer packaging material 10 is manufactured through the series of steps described above.

  As described above, according to the method for manufacturing the battery exterior material of this embodiment, after the outer layer 11 is laminated on the barrier layer 13 on which the corrosion prevention layer 14 is not formed, the outer layer 11 is laminated on the barrier layer 13. A corrosion prevention layer 14 is formed on the surface opposite to the opposite side. As a result, the barrier layer 13 is reinforced by the outer layer 11 before the corrosion prevention layer 14 is formed, and is protected from scratches and cosmetics. Thereby, compared with the case where the barrier layer 13 is conveyed alone, scratches, creases and wrinkles can be suppressed.

Further, since the corrosion prevention layer 14 contains a fluorine component, the oxide on the surface of the barrier layer 13 can be removed.
In addition, since the chemical conversion solution is dried at a temperature of 200 ° C. or lower in the step of forming the corrosion prevention layer 14, the barrier layer 13 and the outer layer 11 are deteriorated by the heat applied to the barrier layer 13 and the outer layer 11. While being suppressed, a film of the corrosion prevention layer 14 can be formed on the barrier layer 13.

  Moreover, the battery exterior material manufactured by the manufacturing method of this embodiment is sealed by heat welding (heat seal) after the electrolyte layer containing the electrolytic solution, the positive electrode material, and the negative electrode material are disposed inside. Thereby, it becomes a secondary battery by which electrolyte solution was hold | maintained inside the exterior material for batteries.

Next, based on each Example shown below, it demonstrates in detail about the manufacturing method of the battery cladding | exterior_material of this invention.
Example 1
In this example, a biaxially stretched nylon film (Idemitsu Petrochemical Co., Ltd. G100) was used as the outer layer 11. Further, as the adhesive layer X12, a polyurethane-based adhesive (manufactured by Mitsui Chemicals Polyurethanes: A525 / A50) was used. As the barrier layer 13, a soft aluminum foil 8079 material (40 μm) that was annealed (300 ° C., 4 days) was used. No special degreasing was performed on the barrier layer 13 except that annealing degreasing was performed. As the adhesive layer Y15, maleic anhydride-modified polypropylene resin (manufactured by Mitsui Chemicals: Admer) was used. As the inner layer 16, an unstretched polypropylene film (manufactured by Nimura Chemical Industry: FCZK) was used.

As the chemical conversion treatment liquid for forming the corrosion prevention layer, a coating type chromate treatment liquid mainly composed of chromium (III) fluoride, phosphoric acid, and acrylic resin was used. The coating amount was 50 mg / m ² .

  In the manufacturing method of this example, first, the outer layer 11 was provided on one surface of the barrier layer 13 using the adhesive layer X12 by a dry lamination technique. As a dry laminating method, a known laminator was used, the outer layer 11 was installed as the first paper feed of the laminator, and the aluminum foil as the barrier layer 13 was installed as the second paper feed of the laminator.

  Subsequently, a dry laminate adhesive to be the adhesive layer X12 was applied to the outer layer 11 by a direct gravure method and dried at 60 ° C. for 20 seconds. The temperature of the laminate roll was 60 ° C. Thereafter, the adhesive was cured by aging at 50 ° C. for 5 days to form an adhesive layer X12.

Next, a corrosion prevention layer 14 was formed on the surface of the barrier layer 13 opposite to the surface on which the outer layer 11 was fixed, by a microgravure method reversal coating. The drying temperature of the corrosion prevention layer 14 was 150 ° C., and the drying time of the corrosion prevention layer 14 was 18 seconds.
Further, a laminate composed of the outer layer 11, the adhesive layer X12, the barrier layer 13, and the corrosion prevention layer 14 is set in the unwinding portion of the extrusion laminating machine, and the inner layer 16 is set in the sand base material portion to become the adhesive layer Y15. The adhesive was sand-laminated at a processing condition of 290 ° C., 80 m / min and a thickness of 20 μm. Thus, the inner layer 16 was laminated on the corrosion prevention layer 14 via the adhesive layer Y15.
Thereafter, thermocompression bonding (heat treatment) was performed to obtain a battery exterior material.

(Comparative Example 1)
In the same manner as in Example 1 described above, after forming a corrosion prevention layer on the barrier layer, the outer layer was bonded through an adhesive layer. The material constituting the battery exterior material was the same as in Example 1 above.

(Comparative Example 2)
The chromium (III) fluoride in the chemical conversion solution of Comparative Example 1 was changed to chromium (III) acetate hexahydrate. That is, in Comparative Example 2, no fluorine component is used in the chemical conversion treatment. The conditions were the same as in Comparative Example 1 except for the composition of the chemical conversion treatment liquid.

<Evaluation>
The following evaluations were performed on the battery exterior materials manufactured according to Example 1, Comparative Example 1, and Comparative Example 2.
(Evaluation of scratches, cosmetics and wrinkles)
Before the inner layer 16 was attached, the surface of the battery exterior material was observed visually and with a stereomicroscope to determine the presence or absence of scratches, cosmetics, and wrinkles. Evaluations were made with “◯” (good) indicating that there were almost no scratches, cosmetics, or wrinkles, “△” (normal) indicating what could be partially confirmed, and “×” (defect) indicating frequent occurrence.
(Evaluation of heat wrinkles)
Immediately after the step of drying the corrosion prevention layer 14, the state of heat wrinkles was confirmed. Those with no heat wrinkle were rated as “◯” (good), and those with heat wrinkle were “x” (bad).
(Evaluation of adhesion on the outer layer side)
The adhesion strength between the barrier layer 13 and the outer layer 11 of the obtained battery exterior material was measured under the following conditions.
Sample width 15 mm, T-type peeling, peeling speed 300 mm / min.
“O” (good) when the peel strength is 20 N / 15 mm or more, or when the adhesion strength between the barrier layer 13 and the outer layer 11 exceeds the strength of the outer layer 11 and the outer layer 11 breaks when measured, the peel strength is 10 N / 15 mm or more was evaluated as “Δ” (normal), and peeling strength of less than 10 N / 15 mm was determined as “x” (defect).

<Evaluation results>
Table 1 shows a list of evaluation results.

In Example 1 of the present invention, there was no generation of scratches, creases, wrinkles and thermal wrinkles on the barrier layer, and adhesion on the outer layer side was obtained, and a good battery packaging material could be obtained.
On the other hand, in Comparative Example 1, scratches, cosmetics, and wrinkles occurred in part, and the amount of heat wrinkles generated was large. Further, the adhesion on the outer layer side was also significantly reduced, and peeling progressed at the interface between the barrier layer and the adhesive layer. Since the corrosion prevention treatment containing the fluorine component was performed prior to the lamination of the outer layer, the fluorine component adhered to the back surface of the barrier layer (the surface facing the outer layer side), and the adhesion to the adhesive layer on the outer layer side was reduced. It is thought that. Specifically, since aluminum is employed as the material of the barrier layer in Example 1, aluminum fluoride is formed on the barrier layer when the corrosion prevention layer containing a fluorine component is formed, and the adhesive layer X12 It is thought that the adhesiveness with was lowered.
In Comparative Example 2, since the hydrofluoric acid component was not included in the corrosion prevention layer, the outer layer adhesion was not deteriorated, but scratches, wrinkles, and wrinkles were generated in the same manner as in Comparative Example 1.

  As shown in Example 1, by forming an anticorrosion layer on the barrier layer after providing the outer layer on the barrier layer, the anticorrosion layer is formed only on the inner layer side, and only on one side in the thickness direction of the barrier layer. When the corrosion prevention layer is formed, the adhesion between the layers is hardly lowered. Thereby, since the corrosion prevention layer can be formed only on the side where corrosion resistance is desired, the cost for manufacturing the battery outer packaging material can be reduced.

Next, the battery exterior material manufactured in Example 1 and the battery exterior material manufactured in Comparative Example 1 were each cold-formed under the following conditions. As a result, the battery exterior material manufactured in Comparative Example 1 was broken at a molding depth of 3 mm. On the other hand, the battery exterior material manufactured in Example 1 could be molded with a molding depth of 5 mm or more.
Sample size: 300mm x 190mm
Punch shape: 100mm x 150mm
Punch corner R (R _CP ): 1.5mm
Punch shoulder _{R (R} P): 0.75mm
Die shoulder R (R _D ): 0.75 mm

  Conventionally, for the purpose of further increasing the energy density of a lithium ion battery, a method is known in which a multilayer film is cold-molded to form a recess to accommodate more battery contents such as an electrolyte layer. However, conventionally, it has been known that the concave portions of the multilayer film are easily broken at the time of molding at the sides and corners, which are portions having a high stretch ratio by cold molding. For this reason, it has been difficult in the past to increase the volume of the recess while suitably maintaining the function as a sealant.

  On the other hand, as shown in Example 1 described above, the battery exterior material manufactured by the manufacturing method of the present embodiment can form a deeper recess than the conventional one without breaking. For this reason, more battery contents, such as an electrolyte layer, can be accommodated.

  As can be seen from the above Example 1, Comparative Example 1 and Comparative Example 2, the battery exterior material of the present invention is suppressed from scratches, wrinkles, wrinkles and thermal wrinkles in the barrier layer, and further to a corrosion prevention layer. Adhesiveness can be maintained even if a fluorine component is contained.

As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.
For example, the corrosion prevention layer 14 may be provided on the barrier layer 13 in-line during extrusion lamination in the step of laminating the inner layer 16. In addition, a multilayer film is formed with the adhesive layer Y15 and the inner layer 16 by an inflation method or a cast method, and the multilayer film is formed on the laminate in which the corrosion prevention layer 14 is formed on the outer layer 11, the adhesive layer X12, and the barrier layer 13. Can be laminated by thermal lamination.

10 Battery Exterior Material 11 Outer Layer 12 Adhesive Layer X
13 Barrier layer 14 Corrosion prevention layer 15 Adhesive layer Y
16 Inner layer

Claims (7)

  An outer layer that reinforces the barrier layer is provided on one surface in the thickness direction of the barrier layer that prevents the intrusion of the liquid component, and the surface of the barrier layer opposite to the side on which the outer layer is provided has corrosion resistance. A method for producing a battery exterior material, comprising: forming a corrosion prevention layer, and fixing an inner layer to a surface of the corrosion prevention layer opposite to a side in contact with the barrier layer. It is a manufacturing method of the battery exterior material according to claim 1,
The said corrosion prevention layer contains a fluorine component, The manufacturing method of the battery exterior material characterized by the above-mentioned. It is a manufacturing method of the battery exterior material according to claim 1,
The corrosion prevention layer is formed by applying a liquid containing a component resistant to hydrofluoric acid to the opposite surface of the barrier layer, and applying the liquid applied to the opposite surface to a temperature of 200 ° C. or less. A method for producing an outer packaging material for a battery, characterized in that it is formed by drying the film to form a film. It is a manufacturing method of the exterior material for batteries according to any one of claims 1 to 3,
The outer layer is made of a biaxially stretched polyamide film having a thickness of 6 µm or more and 40 µm or less. It is a manufacturing method of the exterior material for batteries according to any one of claims 1 to 4,
The said barrier layer consists of soft aluminum foil whose thickness is 10 micrometers or more and 150 micrometers or less, The manufacturing method of the battery exterior material characterized by the above-mentioned. It is a manufacturing method of the battery exterior material according to claim 5,
The method for producing a battery outer packaging material, wherein the soft aluminum foil contains iron.   The secondary battery which has the battery exterior material manufactured by the manufacturing method as described in any one of Claim 1 to 6.

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