JP5343991B2 - Polymer battery packaging materials - Google Patents

Description

  The present invention relates to a polymer battery packaging material having a solid organic electrolyte (polymeric polymer electrolyte) having moisture resistance, content resistance, and moldability, and a method for producing the same.

  The polymer battery is also referred to as a lithium secondary battery, and is a battery that has a polymer electrolyte and generates a current by the movement of lithium ions, and includes a positive electrode / negative electrode active material made of a polymer. The structure of the lithium secondary battery is as follows: positive electrode current collector (aluminum, nickel) / positive electrode active material layer (polymeric positive electrode material such as metal oxide, carbon black, metal sulfide, electrolyte, polyacrylonitrile) / electrolyte layer (propylene) Carbonate, ethylene carbonate, dimethyl carbonate, ethylene methyl carbonate and other carbonate solid electrolytes, inorganic solid electrolytes and gel electrolytes composed of lithium salts, negative electrode active materials (lithium metals, alloys, carbon, electrolytes, polyacrylonitrile and other polymer negative electrodes Material) / negative electrode current collector (copper, nickel, stainless steel) and an outer package for packaging them. The polymer battery is used for personal computers, portable terminal devices (cell phones, PDAs, etc.), video cameras, electric vehicles, energy storage batteries, robots, satellites, and the like. As the exterior body of the polymer battery, a metal can formed by pressing a metal into a cylindrical or rectangular parallelepiped container, or a laminate made of a base material layer / aluminum / sealant layer in a bag shape Was used.

  However, there have been the following problems as the outer package of the polymer battery. In a metal can, since the outer wall of the container is rigid, the shape of the battery itself is determined. Therefore, since the hardware side is designed to match the battery, the size of the hardware using the battery is determined by the battery, and the degree of freedom in shape is reduced. In view of this, a pouch type has been developed in which the laminated body is made into a bag shape and the polymer battery body is accommodated, or an embossed type in which the laminated body is press-molded to form a recess and the polymer battery is accommodated in the recess. The embossed type can provide a more compact package than the pouch type. In any type of exterior body, strength, insulation, etc., such as moisture resistance or puncture resistance as a polymer battery are indispensable as an exterior body of a polymer battery. For the laminate to be used, suitability in the press molding is important. For example, as an emboss type polymer battery packaging material, a laminate comprising nylon / adhesive layer / aluminum / adhesive layer / cast polypropylene can be specifically mentioned. And, even when using the dry laminating method in which the adhesive layer stably obtains a high adhesion strength, when embossing, when the polymer battery is housed in a packaging material and its peripheral portion is heat sealed, Delamination sometimes occurred between nylon and aluminum. In addition, delamination may occur between aluminum and cast polypropylene due to hydrogen fluoride generated by the reaction between the electrolyte component of the polymer battery and moisture. An object of the present invention is to provide a material excellent in molding processability as well as protective physical properties of a polymer battery as a material used for embossed polymer battery packaging.

The present invention is a laminate for forming an embossed type exterior body, and at least a base material layer, an adhesive layer, a chemical conversion treatment layer, aluminum, a chemical conversion treatment layer, an acid-modified PP film layer, and an innermost layer are configured in this order . Ri laminate der, the base layer is made of a laminate of a polyester film and nylon film, the innermost layer is a packaging material for a polymer battery is a cast polypropylene film layer, the chemical conversion treatment is a phosphoric acid chromate treatment it is, the adhesive layer contains a that is formed by dry lamination.

  The chemical conversion treatment performed on both sides of aluminum in the polymer battery packaging material of the present invention can prevent delamination between the base material layer and aluminum during embossing and heat sealing, and In addition, since the corrosion of the aluminum surface due to hydrogen fluoride generated by the reaction between the electrolyte of the polymer battery and moisture can be prevented, it is possible to prevent the delamination between the aluminum and the content-side layer.

It is layer structure sectional drawing which shows the Example of the packaging material for polymer batteries of this invention. Explain the packaging type of an embossed type polymer battery, (a) perspective view of single-sided embossed type, (b), (c) perspective view of double-sided embossed type, (d) structural explanatory diagram of single-sided embossed type, (e) a X ₁ -X ₁ part cross-sectional view. It is (a) perspective view, (b) embossed exterior body, (c) X ₂ -X ₂ part sectional view, (d) Y ₁ part enlarged view for explaining molding in the embossed type. BRIEF DESCRIPTION OF THE DRAWINGS It is the conceptual diagram of an apparatus explaining the thermal lamination used for lamination | stacking of the packaging material for polymer batteries of this invention, (b) The enlarged view of the Y section. It is a perspective view explaining the mounting method of the adhesive film in adhesion | attachment with the packaging material for polymer batteries, and a tab.

The packaging material for a polymer battery of the present invention is an embossed type exterior body that is characterized by forming a recess for housing the polymer battery body. The present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a layer structure showing an embodiment of the packaging material for polymer battery of the present invention. FIGS. 2A and 2B illustrate a packaging type of an embossed type polymer battery, (a) a perspective view of a single-sided embossed type, (b) and (c) a perspective view of a double-sided embossed type, and ( d ) a single-sided embossed type. structure illustration, a (e) X ₁ -X ₁ part cross-sectional view. Figure 3 illustrates the molding in embossed type, (a) a perspective view, (b) embossing the molded outer body, (c) X ₂ -X ₂ parts cross-sectional view, with (d) Y ₁ part enlarged view is there. FIG. 4 is (a) a conceptual diagram of the apparatus and (b) an enlarged view of a Y portion for explaining a thermal laminate used for laminating the polymer battery packaging material of the present invention. FIG. 5 is a perspective view for explaining a method for attaching an adhesive film in adhesion between a polymer battery packaging material and a tab.

As shown in FIG. 2 (a) or FIG. 2 (b), the embossed type polymer battery is formed by pressing a laminated body of polymer battery packaging material by press molding or the like in a recess for housing the polymer battery main body. FIG. 2B and FIG. 2C are both double-sided embossed types, but are different in peripheral seals and show a four-side seal and a three-side seal. Then, as shown in FIG. 2 (d), the polymer battery stores the polymer battery main body in the recess 7 formed in the outer body main body, covers the outer body lid body, and heat seals the peripheral seal portion. To complete. At this time, it is desirable that the side wall portion 8 to be molded is erected as much as possible so that the battery main body is tightly accommodated. Therefore, the laminate must have good extensibility in press molding, that is, good moldability. . When the packaging material is made of, for example, nylon / adhesive layer / aluminum / adhesive layer / cast polypropylene, and the adhesive layer is formed by a dry laminate method, in press molding, between the aluminum and the base material layer in the side wall portion. In many cases, delamination that peels off occurs, and delamination also occurs in a portion where the polymer battery body is housed in an exterior body and its periphery is heat sealed. Moreover, the hydrofluoric acid produced | generated by reaction with the electrolyte which is a component of a battery, and a water | moisture content may attack the inner surface side of aluminum, and may cause delamination.

  Therefore, the present inventors have intensively studied a packaging material that is a laminated body that does not cause delamination during emboss molding and heat sealing, and that can be satisfied as an exterior body for a polymer battery having content resistance. As a result, a chemical conversion treatment is performed on both sides of the aluminum, and an acid-modified PP (hereinafter sometimes referred to as PPa) such as unsaturated carboxylic acid grafted random propylene on the chemical conversion treatment surface on the aluminum content side. By coating and baking, cast polypropylene, which is a heat seal layer, can be heat-laminated, and the obtained laminated adhesive portion is found to be stable, and the present invention has been completed.

  As shown in FIG. 1, the layer structure of the polymer battery packaging material of the present invention includes at least a base material layer 11, an adhesive layer 15 (1), a chemical conversion treatment layer 14 (1), aluminum 12, and a chemical conversion treatment layer 14 (2 ), A laminate composed of the acid-modified PP film layer 13 and the heat seal layer 14, and is characterized by a chemical conversion treatment applied to both surfaces of the aluminum.

  The base material layer 11 of the polymer battery packaging material in the present invention is made of polyester or nylon film. At this time, as the polyester resin, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymerized polyester are used. And polycarbonate. Examples of nylon include polyamide resin, that is, nylon 6, nylon 6,6, a copolymer of nylon 6 and nylon 6,6, nylon 6,10, polymetaxylylene adipamide (MXD6), and the like.

  When the base material layer 11 is used as a polymer battery, the base material layer 11 is a part that is in direct contact with the hardware. Considering the existence of pinholes in the film alone and the occurrence of pinholes during processing, the base material layer needs to have a thickness of 6 μm or more, and preferably 12 to 25 μm.

In the present invention, the base material layer can be laminated in order to improve the pinhole resistance and the insulation with the hardware when used as a battery outer package. When laminating the base material layer, the base material layer includes at least one resin layer of two or more, and the thickness of each layer is 6 μm or more, preferably 12 to 25 μm. Examples of laminating the base material layer include the following 1) to 7), although not shown.
1) Polyethylene terephthalate / nylon 2) Nylon / polyethylene terephthalate In addition, mechanical properties of packaging materials (stability of conveyance in processing machines and packaging machines), surface protection (heat resistance, electrolyte resistance), secondary processing As an exterior body for polymer batteries, when embossed, the base material layer is multilayered for the purpose of reducing the frictional resistance between the mold and the base material layer during embossing. It is preferable to provide a resin, an acrylic resin, a silicone resin, or the like. For example,
3) Fluorine resin / polyethylene terephthalate (Fluorine resin is a film or formed by drying after liquid coating)
4) Silicone-based resin / polyethylene terephthalate (Silicone-based resin is a film-like material or formed by drying after liquid coating)
5) Fluororesin / Polyethylene terephthalate / Nylon (Fluororesin is a film or formed by drying after liquid coating)
6) Silicone resin / Polyethylene terephthalate / Nylon 7) Acrylic resin / Nylon (Acrylic resin is formed into a film or dried after liquid coating)

  The base material layer is bonded to the barrier layer using a dry laminating method.

  The barrier layer is a layer for preventing water vapor from entering the inside of the polymer battery from the outside, stabilizing the pinhole and processability (pouching, embossing formability) of the barrier layer alone, and being resistant to resistance. In order to have a pinhole, a metal such as aluminum having a thickness of 15 μm or more, nickel, or a film on which an inorganic compound such as silicon oxide or alumina is deposited may be used. The barrier layer is preferably 20 to 80 μm in aluminum. And In order to further improve the generation of pinholes and to make the outer case of the polymer battery an embossed type, in order to prevent the occurrence of cracks or the like in the embossed portion, the present inventors have made the use of aluminum used as a barrier layer. When the material has an iron content of 0.3 to 9.0% by weight, and preferably 0.7 to 2.0% by weight, the ductility of aluminum is improved compared to aluminum that does not contain iron. It has been found that the occurrence of pinholes caused by bending does not occur easily in the laminate, and that the side wall can be easily formed when the embossed type exterior body is embossed. When the iron content is less than 0.3% by weight, effects such as prevention of pinholes and improvement of embossing formability are not observed, and the iron content of the aluminum exceeds 9.0% by weight. In such a case, the flexibility as aluminum is hindered, and the bag-making property is deteriorated as a laminate.

  In addition, aluminum produced by cold rolling changes its flexibility, waist strength and hardness under annealing (so-called annealing treatment) conditions, but the aluminum used in the present invention is harder than the non-annealed hard-treated product. Aluminum which tends to be soft with some or complete annealing is preferred. The degree of flexibility, waist strength, and hardness of aluminum, that is, the conditions for annealing, may be appropriately selected in accordance with processability (pouching, embossing). For example, in order to prevent wrinkles and pinholes at the time of emboss molding, annealed soft aluminum according to the degree of molding can be used.

As a result of diligent research, the inventors of the present invention, as a result of diligent research, have obtained a laminate that can be satisfied as the packaging material by subjecting the aluminum surface, which is a barrier layer of the polymer battery packaging material, to a chemical conversion treatment on the back surface. We were able to. Specifically, the chemical conversion treatment is a subject of the present invention by performing chemical conversion treatment with phosphate, chromate, fluoride, triazine thiol compound, etc. to form an acid-resistant film. And dehydration between the substrate and the base material layer, and the hydrogen fluoride produced by the reaction between the electrolyte and moisture of the polymer battery dissolves and corrodes the aluminum surface, especially the aluminum oxide present on the aluminum surface dissolves and corrodes. It has been found that it is effective for the problem of preventing adhesion and stabilizing the adhesive force between aluminum and the innermost layer. As a result of conducting a chemical conversion treatment on the aluminum surface using various substances and studying the effect thereof, among the acid-resistant film forming substances, an aqueous solution composed of phenol resin, chromium fluoride (■) compound, phosphoric acid 4 The phosphoric acid chromate treatment using what was comprised from the component was favorable.

  In the polymer battery packaging material of the present invention, an acid-modified PP layer is provided on the chemical conversion treatment surface on the aluminum content side. Providing the acid-modified PP layer has the effect of preventing corrosion of aluminum and stabilizing the adhesion of CPP, which is a heat seal layer, when a polymer battery is formed.

  The innermost layer 13 in the polymer battery packaging material of the present invention is a cast polypropylene (hereinafter referred to as CPP) in which the innermost layers 13 have heat-sealing properties and have necessary physical properties such as heat resistance, moisture resistance and press formability. ) Is desirable.

  In the polymer battery packaging material of the present invention, the innermost CPP is laminated to the acid-modified PP layer by a heat laminating method.

  In addition to the base material layer, the barrier layer, and the innermost layer (CPP), an intermediate layer may be provided between the barrier layer and the innermost layer as the laminate of the polymer battery packaging material of the present invention. The intermediate layer may be laminated for the purpose of improving the strength as a packaging material for polymer batteries, improving and stabilizing the barrier property, or the like.

  Next, the manufacturing method of the packaging material for polymer batteries of this invention is demonstrated. The polymer battery packaging material of the present invention is formed by laminating a base layer, a barrier layer, an acid-modified PP layer and an innermost CPP.

  In the present invention, a chemical conversion treatment is performed on the surface of aluminum before the laminating step for producing a laminate of polymer battery packaging material. The chemical conversion treatment is performed separately on the front surface and the back surface. In the chemical conversion treatment, an aqueous solution or dispersion of the aforementioned substance is applied to the aluminum surface by a method such as roll coating, and a film is formed under the condition that the aluminum surface temperature reaches 170 to 200 ° C. or higher.

Next, a chemical conversion treatment is performed on both surfaces of the aluminum. As the chemical conversion treatment, for example, the phosphoric acid chromate treatment is performed, and an emulsion of an acid-modified polypropylene resin is applied and dried on one side of the obtained chemical conversion treatment surface using a method such as roll coating, and an reached temperature of 170 to 200 ° C. A film (hereinafter referred to as PPa) is formed by heating under conditions. The coating amount is ² to 5 g / m ² as a dry weight. Next, the other phosphate chromate-treated surface of the aluminum and the base material are laminated using a dry laminating method. Next, the cast polypropylene film serving as the innermost layer and the PPa surface are bonded to each other by using a heat laminating method. For example, as shown in FIG. 4A, the thermal laminating method includes an intermediate laminate 24 of the base material layer / adhesive layer / chemical conversion treatment / aluminum / chemical conversion treatment / PPa between the dielectric roll 21 and the pressure roll 22. The PPa surface and the cast polypropylene film 25 are inserted so as to face each other and laminated by thermocompression bonding.

  Examples of the adhesive used for dry lamination of the base material 11 and the phosphoric acid chromate-treated surface of the aluminum 12 include polyester-based, polyethyleneimine-based, polyether-based, polyether-urethane-based, polyester-urethane-based, and epoxy-based adhesives. Among them, polyether urethane type, polyester urethane type and the like are preferably used.

  When forming a laminated body of packaging materials for polymer batteries to form an embossed type exterior body, it can be performed by press molding with a male type and a female type. The embossed type includes a single-sided embossed type and a double-sided embossed type, and the single-sided embossed type needs to be molded deeper.

  As shown in FIG. 2 (a) or FIG. 2 (b), the embossed type polymer battery is formed by pressing a laminated body of polymer battery packaging material by press molding or the like in a recess for housing the polymer battery main body. Then, as shown in FIG. 2 (c), the polymer battery houses the polymer battery body 2 in the recess 7 formed in the exterior body body, covers the exterior body cover body, and heat seals the peripheral seal portion 9 To complete. At this time, it is desirable that the side wall portion 8 to be molded is erected as much as possible so that the polymer battery main body 2 is tightly accommodated. For this reason, the laminate has good extensibility in press molding, that is, good moldability. There must be.

  CPP is suitably used for the innermost layer of the laminate in the polymer battery packaging material of the present invention. CPP is used for the innermost layer because it has good heat-sealability between CPPs, and has the required protective properties as the innermost layer of polymer battery packaging materials, such as moisture resistance and heat resistance, and is also laminated. It is a desirable material due to its good properties and good embossing formability. However, since the CPP has no heat seal against the metal, when the polymer battery tab portion is heat sealed, as shown in FIGS. 5 (a), 5 (b) and 5 (c), the tab 4 is laminated. By interposing the adhesive film 6 having heat sealability with respect to both the metal and the CPP between the innermost layer of the body 10, the sealing performance at the tab portion is also ensured. The adhesive film 6 may be wound around a predetermined position of the tab 4 as shown in FIGS. 5 (d), 5 (e) and 5 (f).

The polymer battery packaging material of the present invention will be described more specifically with reference to examples. In both Examples and Comparative Examples, the base material layer was nylon 25 μm, the barrier layer was aluminum 40 μm, and the heat seal layer was cast polypropylene 30 μm. In each of the chemical conversion treatments, an aqueous solution composed of a phenol resin, a chromium fluoride (■) compound, and phosphoric acid was used as a treatment solution, and the coating was applied by a roll coating method and baked under a condition where the film temperature was 180 ° C. or higher. The application amount of chromium is 10 mg / m ² (dry weight). The acid-modified PP was applied by a roll coating method and baked under conditions where the aluminum temperature was 180 ° C. or higher. The coating amount of the acid-modified PP was 3 g / m ² (dry weight). Further, the embossing was a single-sided embossing type, and the shape of the concave portion (cavity) of the mold was 30 mm × 50 mm, and the depth was 3.5 mm, and the moldability was evaluated. In each example, an unsaturated carboxylic acid grafted random propylene film having a thickness of 20 μm was wound around the seal portion of the tab as a bonding film and heat-sealed.

  A chemical conversion treatment is performed on both surfaces of aluminum, and a base material is bonded to one chemical conversion treatment surface by a dry laminating method, and acid-modified PP is applied and baked to the other chemical conversion treatment surface by a roll coating method to form an acid-modified PP surface. Sample 1 was obtained by laminating cast polypropylene by a thermal laminating method.

[Comparative Example 1]
A base material is bonded to one surface of aluminum by a dry laminating method, and acid-modified PP is applied and baked to the other surface of aluminum by a roll coating method, and cast polypropylene is applied to the acid-modified PP surface by a heat laminating method. Lamination was performed to obtain Sample Comparative Example 1.

<Embossing and packaging>
Each obtained specimen was press-molded, the polymer battery body was packaged, and the following evaluation was performed.

<Evaluation method>
1) Delamination at molding Immediately after molding, the presence or absence of delamination between aluminum and the base material layer was confirmed.
2) Content resistance property As a storage condition, each specimen was stored in a thermostat at 60 ° C. and 90% RH for 7 days, and then the presence or absence of delamination between aluminum and cast polypropylene was confirmed.
3) Delamination during heat sealing Immediately after heat sealing, the presence or absence of delamination between the base material layer and aluminum was confirmed.

<Result>
In the laminate of Example 1, there was no problem during molding and heat sealing, and no delamination between the base material layer and aluminum was observed. Moreover, there was no delamination of content resistance. However, in the comparative example, delamination was observed in 45 samples out of 100 samples at each stage of molding and heat sealing. Regarding the content resistance, delamination was observed in all of the 100 samples.

1 Polymer Battery 2 Polymer Battery Body 3 Cell (Power Storage Unit)
4 Tab (electrode)
5 Exterior body 6 Adhesive film (tab part)
7 Concave portion 8 Side wall portion 9 Seal portion 10 Laminated body (polymer battery packaging material)
11 Base material layer 12 Aluminum (barrier layer)
DESCRIPTION OF SYMBOLS 13 Acid-modified PP film layer 14 Innermost layer 15 Chemical conversion treatment layer 16 Adhesive layer 20 Thermal laminating device 21 Dielectric heating roll 22 Rubber roll 23 Cooling roll 24 Laminated intermediate 25 CPP film 26 Laminated body

Claims (3)

A laminate that forms an embossed type exterior body, and is a laminate in which at least a base material layer, an adhesive layer, a chemical conversion treatment layer, aluminum, a chemical conversion treatment layer, an acid-modified PP coating layer, and an innermost layer are configured in this order. The base material layer is a laminate of a polyester film and a nylon film, and the innermost layer is a cast polypropylene film layer . The polymer battery packaging material according to claim 1, wherein the chemical conversion treatment is a phosphoric acid chromate treatment . The polymer battery packaging material according to claim 1, wherein the adhesive layer is formed by a dry lamination method .

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