JP2015201387A - Sheath material for secondary battery, secondary battery, and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheath material for a secondary battery excellent in insulation property and steam barrier property, having excellent adhesion between the sheath material and a lead even without using a tab sealant.SOLUTION: The sheath material for a secondary battery includes: a base material layer; a barrier layer formed on one surface of the base material layer; and a heat fusion resin layer formed on an opposite side of the base material layer of the barrier layer. The barrier layer is composed of an electrical insulating material. Melt mass flow rate of the heat fusion resin layer is equal to or higher than 10 g/10 minutes and equal to or less than 30 g/10 minutes at a temperature of 230°C and a load of 2.16 kg.

Description

  The present invention relates to a secondary battery exterior material, a secondary battery including the secondary battery exterior material as a container, and a method of manufacturing the secondary battery.

  2. Description of the Related Art In recent years, secondary batteries that can be ultra-thin or miniaturized have been developed as power storage devices used in personal digital assistants such as personal computers and mobile phones, video cameras, satellites, and vehicles. As an exterior material used for this secondary battery, a laminate exterior material composed of a multilayer film (for example, a base material layer, a first adhesive layer, a metal foil layer, a second adhesive layer, and a heat-sealing resin layer are laminated in this order). Is known). The laminate exterior material is configured to include a metal foil layer, and this metal foil layer suppresses the intrusion of moisture (water vapor) from the outside to the inside of the exterior material so that the battery performance is not deteriorated. .

  On the other hand, in order to take out electric power from a secondary battery using an exterior material, metal terminal members called tabs connected to the positive electrode and the negative electrode are necessary. This tab is generally composed of a lead that is a metal terminal and a tab sealant that is a resin film that covers the lead, and a resinous tab sea land is filled between the lead and the exterior material without any gaps so that they are in close contact with each other. This prevents moisture from entering from the gap between the lead and the exterior material and leakage of the contents, and fixes the lead and the exterior material so as not to peel off. However, there is also moisture that permeates the tab sea land itself and enters the inside. Therefore, in Patent Document 1, for example, a polyethylene naphthalate film having a relatively high water vapor barrier property is used for the tab sealant, and a polyolefin layer is provided on both sides thereof, thereby ensuring the adhesion of water vapor from the tab portion. Internal penetration is suppressed.

Japanese Patent No. 4900418

  However, the use of a tab sealant increases the thickness of the outer edge of the outer packaging material when it is melted to form a secondary battery container, so that the penetration of moisture from the outer edge of the outer packaging material can be sufficiently blocked. I could not say. Moreover, in patent document 1, electroconductive metal foil is exposed to the end surface of an exterior material edge part, and there exists a possibility that it may short-circuit when a lead is bent or when a plurality of secondary batteries are used side by side. there were.

  Therefore, the present invention, while ensuring excellent adhesion with the lead, a secondary battery exterior material having excellent insulation and water vapor barrier properties, a secondary battery comprising the secondary battery exterior material as a container, And it aims at providing the manufacturing method of the said secondary battery.

  In order to achieve the above object, a packaging material for a secondary battery according to the present invention includes a base material layer, a barrier layer formed on one surface of the base material layer, and the base material layer of the barrier layer. And a heat-sealing resin layer formed on the opposite surface. In this secondary battery exterior material, the barrier layer is made of an electrically insulating substance, and the melt mass flow rate of the heat-sealing resin layer is 10 g / 10 min or more and 30 g / 10 at a temperature of 230 ° C. and a load of 2.16 kg. Is less than a minute.

  In the secondary battery exterior material, an electrically insulating material is used as the barrier layer. For this reason, according to the secondary battery exterior material, since insulation can be easily ensured as compared with the case of using a metal foil layer as the barrier layer, the melting conditions of the exterior material can be set without much consideration of insulation. Can be set. And in this exterior material, by providing the melt mass flow rate of the heat-sealing resin layer within the above range, excellent adhesion and filling properties are provided between the exterior material and the lead without using a tab sealant. In addition, by reducing the thickness of the fusion bonding end portion of the exterior material, it is possible to suppress the intrusion of moisture from the exterior material end portion. Therefore, according to the packaging material for a secondary battery, it is possible to improve insulation and water vapor barrier properties while ensuring excellent adhesion to the leads.

  The melting point of the resin of the heat sealing resin layer is preferably 100 ° C. or higher and 150 ° C. or lower. When the melting point is 100 ° C. or higher, the strength can be maintained even in a high temperature environment. Moreover, since melting | fusing point is 150 degrees C or less, high temperature is not required for heat fusion, the load to a barrier layer can be reduced, and the outstanding water vapor | steam barrier property can be maintained.

  The thickness of the heat sealing resin layer is preferably 20 μm or more and 90 μm or less. When the thickness is 20 μm or more, sufficient heat seal strength can be obtained. In addition, when the thickness is 90 μm or less, it is possible to sufficiently block moisture from entering from the edge of the exterior material and suppress deterioration of the water vapor barrier property.

  The heat sealing resin layer preferably contains an acid-modified polyolefin resin. By using an acid-modified polyolefin resin for the heat-sealing resin layer, the adhesion between the exterior material and the leads can be further improved.

  The barrier layer is preferably made of an inorganic oxide or an organic barrier film. In particular, when the barrier layer is an inorganic oxide, the water vapor barrier property can be increased.

  The present invention also relates to a secondary battery as another aspect. The secondary battery includes a battery element including an electrolytic solution and an electrode, a lead extending from the electrode, and a container that accommodates the battery element, and the container includes the heat from the secondary battery exterior material. The fusion resin layer is formed on the inner side. In this secondary battery, the lead is sandwiched by the exterior material that forms the container with the heat-sealing resin layer inside. In this case as well, the insulating property and water vapor barrier property of the secondary battery can be improved while ensuring excellent adhesion to the lead, as in the case of the secondary battery exterior material.

  In the secondary battery, it is preferable that the lead is sandwiched by the exterior material in a state where the heat-sealing resin layer is in direct contact with the lead. Since the lead and the heat-sealing resin layer are in direct contact without using a tab sealant, the thickness of the end portion of the outer packaging material in the secondary battery can be reduced, and moisture from the end of the outer packaging material can be reduced. The amount of infiltration can be further reduced, and excellent water vapor barrier properties can be maintained. Moreover, since it is not necessary to use a tab sea land, manufacturing can also be simplified by reducing the number of members.

  In the secondary battery, the container has a lead heat fusion part thermally fused together with the lead, and the length L of the lead heat fusion part in the extension direction of the lead is 3 mm or more and 20 mm or less. It is preferable. When the length of the lead heat fusion part is 3 mm or more, the amount of moisture permeating from the end of the exterior material can be sufficiently reduced, and the length of the lead heat fusion part is 20 mm or less. Thus, the installation area of the secondary battery can be reduced.

  Moreover, this invention relates to the manufacturing method of a secondary battery as another side surface. The secondary battery manufacturing method includes the steps of preparing a secondary battery exterior material, a battery element including an electrolyte and an electrode, and a lead extending from the electrode, and the heat-fusible resin layer on the inside. In this state, the battery element and a part of the lead are disposed between the exterior materials, and the leads are sandwiched by the exterior material having the heat-fusible resin layer disposed inside. And heat-sealing the peripheral edge of the exterior material.

  In the method for manufacturing a secondary battery, it is preferable that the thickness of the heat sealing resin layer before heat sealing is 40% or more and 80% or less with respect to the thickness of the lead. When the thickness of the heat-sealing resin layer is 40% or more with respect to the thickness of the lead, sufficient fillability can be obtained. When the thickness of the heat sealing resin layer is 80% or less with respect to the thickness of the lead, it is possible to suppress the end from becoming thicker and to further reduce the amount of moisture entering from the end of the exterior material. Can be made.

  According to the present invention, while ensuring excellent adhesion with the lead, a secondary battery exterior material having excellent insulation and water vapor barrier properties, a secondary battery comprising the secondary battery exterior material as a container, And the manufacturing method of the said secondary battery can be provided.

It is a schematic sectional drawing of the exterior material for secondary batteries which concerns on one Embodiment of this invention. It is a schematic sectional drawing of the exterior material for secondary batteries which concerns on another embodiment of this invention. It is a perspective view which shows the process of manufacturing a secondary battery using the exterior material for secondary batteries which concerns on one Embodiment of this invention, (a) shows the state which prepared the exterior material for secondary batteries, b) shows a state in which an exterior material for a secondary battery processed into an embossed type and a battery element are prepared, and (c) shows a state in which a part of the exterior material for a secondary battery is folded and the end is melted. (D) shows a state where both sides of the folded portion are folded upward.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, this invention is not limited to the following embodiment.

(Exterior material 10 for secondary battery)
First, the secondary battery exterior material 10 according to the present embodiment (hereinafter also simply referred to as “exterior material 10”) will be described. The exterior material 10 covers battery elements such as a positive electrode, a separator, a negative electrode, and an electrolytic solution, and prevents moisture from entering the battery, or a substance generated inside (for example, hydrofluoric acid generated by moisture penetration) ) Is a packaging material for preventing leakage to the outside. As shown in FIG. 1, such an exterior material 10 is opposite to the base material layer 11, the barrier layer 12 formed on one surface of the base material layer 11, and the base material layer 11 of the barrier layer 12. And a heat-sealing resin layer 14 formed on the side surface. As shown in FIG. 1, the exterior material 10 has an adhesive resin layer 13 disposed between a barrier layer 12 and a heat-sealing resin layer 14. The secondary battery exterior material may be an exterior material 10a in which the heat-sealing resin layer 14 is directly disposed on the barrier layer 12, as shown in FIG.

  Next, each layer constituting the exterior material 10 will be described in more detail.

[Base material layer 11]
The base material layer 11 imparts heat resistance to the exterior material 10 in a pressurization thermal fusion process, which will be described later when manufacturing a secondary battery, to suppress the generation of pinholes that may occur during processing or distribution. Is a layer. Examples of the base material layer 11 include films of polyester resin, polyamide resin, polyolefin resin, polyimide resin or polycarbonate resin. These films may be stretched films or unstretched films. . From the viewpoint of improving heat resistance, puncture resistance or insulation, the base material layer 11 is preferably a biaxially stretched polyamide film or a biaxially stretched polyester film, and is biaxially stretched polyethylene terephthalate film or biaxially stretched nylon. More preferably a film. The base material layer 11 may be comprised from one layer, and may be comprised from the composite layer which bonded together the several layer by the dry laminate through the adhesive agent.

  For example, the thickness of the base material layer 11 is preferably 6 μm or more and 100 μm or less, and more preferably 10 μm or more and 40 μm or less. When the thickness of the base material layer 11 is equal to or more than the above lower limit value, the pinhole resistance or the insulation becomes better. When the thickness of the base material layer 11 is equal to or less than the above upper limit value, it is possible to suppress a load on the barrier layer due to heat shrinkage. In addition, the thickness of the base material layer 11 is a thing after lamination | stacking, and is the same also about the barrier layer 12, the adhesive resin layer 13, and the heat-fusion resin layer 14 mentioned later. In this specification, it is assumed that at least the thickness of the base material layer 11, the barrier layer 12, and the heat-sealing resin layer 14 before lamination is equal to the thickness after lamination.

  In the base material layer 11, additives such as a flame retardant, slip agent, anti-blocking agent, antioxidant, light stabilizer, tackifier and antistatic material may be dispersed inside, and these additions An agent may be applied to the surface of the base material layer 11.

[Barrier layer 12]
The barrier layer 12 is a layer that imparts a water vapor barrier property to the exterior material 10 and is made of an electrically insulating material. As an electrical insulating substance which comprises the barrier layer 12, an inorganic oxide or an organic barrier film is preferable, and it is more preferable that it is an inorganic oxide from the point of water vapor | steam barrier property. As the inorganic oxide, aluminum oxide, silicon oxide, or the like can be used. By using an electrically insulating material such as an inorganic oxide for the barrier layer 12, the barrier layer 12 becomes nonconductive, and it is not necessary to ensure insulation between the exterior material 10 and the lead 2.

  For example, when the barrier layer 12 is formed by vapor deposition, the thickness is preferably 10 nm or more and 300 nm or less, and more preferably 20 nm or more and 200 nm or less. When the thickness of the barrier layer 12 is 10 nm or more, the barrier layer 12 can be continuously formed, and when it is 300 nm or less, the occurrence of warpage or cracks is suppressed, and flexibility is improved. improves.

  In addition, a protective layer may be provided on the barrier layer 12 for the purpose of improving water vapor barrier properties, scratch resistance, or chemical resistance.

[Adhesive resin layer 13]
The adhesive resin layer 13 is a layer that bonds the barrier layer 12 and the heat-sealing resin layer 14 together. The packaging material 10 is divided into a thermal laminate configuration and a dry laminate configuration depending on an adhesive component that forms the adhesive resin layer 13.

  Examples of the adhesive component that constitutes the adhesive resin layer 13 in the thermal laminate configuration include acid-modified polyolefin resins. Examples of the polyolefin resin include low density, medium density and high density polyethylene; ethylene-α olefin copolymer; polypropylene; and propylene-α olefin copolymer. In the case of the copolymer, the polyolefin resin may be a block copolymer or a random copolymer.

  The modification rate of the polyolefin resin by acid (for example, the mass of the portion derived from maleic anhydride relative to the total mass of maleic anhydride-modified polypropylene) is preferably 0.1 to 20% by mass, and 0.3 to 5 More preferably, it is mass%.

  Examples of the acid modification method in the polyolefin resin include a method of graft modification with an acid and a method of copolymerizing a monomer having an acid. The acid for modifying the polyolefin resin is preferably an unsaturated carboxylic acid or an acid anhydride thereof. Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, and itaconic acid. The unsaturated carboxylic acid or acid anhydride thereof is preferably acrylic acid, methacrylic acid, maleic acid or maleic anhydride, and more preferably maleic anhydride. The unsaturated carboxylic acid or acid anhydride thereof may be an unsaturated carboxylic acid derivative to which an ester group, an amide group, an imide group, or the like is bonded. The acid which modifies | denatures polyolefin resin may be used individually by 1 type, and may use 2 or more types together.

  The adhesive component constituting the adhesive resin layer 13 in the dry laminate configuration includes 2 main ingredients such as polyester polyol, polyether polyol, acrylic polyol and polyolefin polyol, and a curing agent such as aromatic or aliphatic isocyanate. A liquid curable polyurethane adhesive can be used. In the adhesive, the molar ratio (NCO / OH) or (NCO / COOH) of the NCO group of the curing agent to the OH group (or COOH group) of the main agent is preferably 1 or more and 10 or less, and preferably 2 or more and 5 or less. It is more preferable that

  In the case of a thermal laminate configuration, the thickness of the adhesive resin layer 13 is preferably 8 μm or more and 30 μm or less, and more preferably 10 μm or more and 20 μm or less. When the thickness of the adhesive resin layer 13 is 8 μm or more, sufficient adhesive strength between the barrier layer 12 and the heat-sealing resin layer 14 can be easily obtained. It is possible to easily reduce the amount of moisture that enters the element. The thickness of the adhesive resin layer 13 is preferably 1 μm or more and 5 μm or less in the case of a dry laminate configuration. When the thickness of the adhesive resin layer 13 is 1 μm or more, sufficient adhesive strength between the barrier layer 12 and the heat-sealing resin layer 14 is easily obtained, and when the thickness is 5 μm or less, the adhesive resin layer 13 is not cracked. Occurrence can be suppressed.

[Heat-fusion resin layer 14]
The heat-sealing resin layer 14 is formed on the barrier layer 12 via the adhesive resin layer 13 as necessary. For example, the heat sealing resin layers 14 of the two outer packaging materials 10 face each other, and the heat sealing resin layer 14 together with the two outer packaging materials 10 is subjected to pressure thermal fusion at or above its melting temperature, whereby the battery element Can be sealed (contained). In addition, it is good also as a container by folding the one exterior | packing material 10 and making the heat sealing | fusion resin layer 14 face each other, and carrying out pressure heat sealing | fusion.

  The melt mass flow rate (MFR) of the heat-sealing resin layer 14 is preferably 10 g / 10 min or more and 30 g / 10 min or less at a temperature of 230 ° C. and a load of 2.16 kg, and 15 g / 10 min or more and 25 g / 10 min. The following is more preferable. When the MFR of the heat-sealing resin layer 14 is 10 g / 10 min or more, the lead end can be filled without a tab sealant, and leakage of the battery element or moisture intrusion from the end of the exterior material can be suppressed. be able to. On the other hand, when the MFR of the heat-sealing resin layer 14 is 30 g / 10 min or less, it is possible to suppress a decrease in adhesion with the lead 2 due to excessive flow during pressure heat-sealing. The MFR of the heat sealing resin layer 14 is calculated according to the method described in JIS K 7210.

  The melting point of the resin of the heat-sealing resin layer 14 is preferably 100 ° C. or higher and 150 ° C. or lower, and more preferably 110 ° C. or higher and 140 ° C. or lower. When the melting point is equal to or higher than the lower limit value, it can have excellent strength (heat resistance) even in a high temperature environment, and when the melting point is equal to or lower than the upper limit value, a high amount of heat is not applied at the time of pressure heat fusion. Since it can fuse | melt, the load to the barrier layer 12 can be reduced and a high water vapor | steam barrier property can be maintained.

  Examples of the heat-sealing resin layer 14 include a polyolefin resin and an acid-modified polyolefin resin. From the viewpoint of improving the adhesion to the lead 2, it is preferable to include an acid-modified polyolefin resin.

  Examples of the polyolefin resin include low density, medium density and high density polyethylene; ethylene-α olefin copolymer; polypropylene; and propylene-α olefin copolymer. The polyolefin resin in the case of a copolymer may be a block copolymer or a random copolymer. The weight average molecular weight of the polyolefin resin is selected so that the melt mass flow rate of the heat sealing resin layer 14 can be adjusted to a desired range.

  The modification rate of the polyolefin resin by acid (for example, the mass of the portion derived from maleic anhydride relative to the total mass of maleic anhydride-modified polypropylene) is preferably 0.1 to 20% by mass, and 0.3 to 5% by mass. % Is more preferable.

  Examples of the acid modification method in the polyolefin resin include a method of graft modification with an acid and a method of copolymerizing a monomer having an acid. The acid for modifying the polyolefin resin is preferably an unsaturated carboxylic acid or an acid anhydride thereof. Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, and itaconic acid. The unsaturated carboxylic acid or acid anhydride thereof is preferably acrylic acid, methacrylic acid, maleic acid or maleic anhydride, and more preferably maleic anhydride. The unsaturated carboxylic acid or acid anhydride thereof may be an unsaturated carboxylic acid derivative to which an ester group, an amide group, an imide group, or the like is bonded. The acid which modifies | denatures polyolefin resin may be used individually by 1 type, and may use 2 or more types together.

  The thickness of the heat-sealing resin layer 14 is preferably 20 μm or more and 90 μm or less, and more preferably 25 μm or more and 60 μm or less. When the thickness of the heat-sealing resin layer 14 is 20 μm or more, sufficient heat seal strength can be obtained, and when it is 90 μm or less, the amount of water vapor entering from the edge of the exterior material can be reduced. it can.

  The heat sealing resin layer 14 may contain various additives such as a slip agent, an antiblocking agent, an antistatic agent, a nucleating agent, a pigment, and a dye. These additives may be used individually by 1 type, and may use 2 or more types together.

(Method for manufacturing exterior material 10)
Next, the manufacturing method of the exterior material 10 provided with the structure mentioned above is demonstrated. In addition, the manufacturing method of the exterior material 10 is not limited to the following method.

As a manufacturing method of an exterior material, the method of following process S11-S12 is mentioned, for example.
Step S11: A step of forming the barrier layer 12 on one surface of the base material layer 11.
Step S12: A step of forming the heat-sealing resin layer 14 on the surface of the barrier layer 12 opposite to the base material layer 11 through the adhesive resin layer 13 as necessary.

[Step S11]
The barrier layer 12 is formed on one surface of the base material layer 11 by, for example, vacuum film formation. Examples of the vacuum film forming method include known methods such as a vacuum vapor deposition method, a sputtering method, and a chemical vapor deposition method (CVD method). The vacuum film formation method is preferably a vacuum vapor deposition method from the viewpoint of productivity such as water vapor barrier properties, thickness uniformity, and film formation speed, and more preferably a film formation method by electron beam heating. preferable.

[Step S12]
In step S12, the heat-sealing resin layer 14 is formed on the surface of the barrier layer 12 opposite to the base material layer 11. The heat sealing resin layer 14 is formed by a method in which the exterior material 10 has a heat laminate configuration, a case in which the exterior material 10 has a dry laminate configuration, and a configuration in which the exterior material 10 has an exterior material 10a (having an adhesive resin layer 13). In the case of having a configuration that does not).

  When the exterior material 10 has a heat laminate configuration, examples of the method for forming the heat-sealing resin layer 14 include a dry process and a wet process. In the case of the dry process, an adhesive resin is extruded and laminated on the barrier layer 12, and a film that forms the heat-sealing resin layer 14 obtained by an inflation method or a T-die extrusion method is laminated. Thereafter, for the purpose of improving the adhesion between the barrier layer 12 and the adhesive resin layer 13, heat treatment (aging or thermal lamination) may be performed. In addition, a multilayer film in which the adhesive resin layer 13 and the heat-sealing resin layer 14 are laminated by an inflation method or a cast method, and the multilayer film is laminated on the barrier layer 12 by thermal lamination, thereby bonding. A heat-sealing resin layer 14 may be formed through the resin layer 13.

  In the case of a wet process, a dispersion of an adhesive resin such as an acid-modified polyolefin resin is applied onto the barrier layer 12, and the adhesive resin is melted and softened while volatilizing the dispersion medium at a temperature equal to or higher than the melting point of the adhesive resin. After baking, the heat-fusion resin layer 14 is formed by heat treatment such as thermal lamination.

  When the exterior material 10 has a dry laminate configuration, examples of the method for forming the heat-sealing resin layer 14 include the following methods. An adhesive resin solution is applied onto the barrier layer 12 and the solvent is dried in an oven. Thereafter, the heat-sealing resin layer 14 is formed through the adhesive resin layer 13 by thermocompression bonding by dry lamination.

  The method for applying the adhesive resin solution is not particularly limited, and examples thereof include gravure coating, gravure reverse coating, roll coating, reverse roll coating, die coating, bar coating, kiss coating, and comma coating. In step S12, after forming the heat-sealing resin layer 14, an aging treatment (curing) may be performed at a temperature of 20 ° C. or higher and 100 ° C. or lower for 3 to 20 days in order to accelerate the curing reaction or stabilize the crystal. preferable.

  When the exterior material has the configuration of the exterior material 10a, examples of a method for forming the heat-sealing resin layer 14 include a method in which the heat-sealing resin layer 14 is formed on the barrier layer 12 by extrusion lamination.

(Secondary battery 30)
Next, the secondary battery 30 provided with the exterior material 10 according to the present embodiment as a container will be described (see FIG. 3). The secondary battery 30 includes a battery element 1 including an electrolytic solution and an electrode, a lead 2 extending from the electrode, and a container for housing the battery element 1, and the container is formed from a secondary battery exterior material 10. Is done. The direction in which the lead 2 extends is a direction in which the lead 2 extends from the electrode toward the outside of the container. The container may be obtained by stacking two exterior materials with the heat-sealing resin layers 14 facing each other, and heat-sealing the peripheral edge of the overlapped exterior material 10, or one exterior material. May be obtained by folding and overlapping, and similarly heat-sealing the peripheral edge of the outer packaging material 10. Examples of the secondary battery 30 include a lithium ion battery, a nickel metal hydride battery, and a lead storage battery.

  The lead 2 is a metal terminal that takes out electricity from the inside of the secondary battery 30, and the peripheral portion of the lead 2 needs to be in close contact with the exterior material 10 in order to prevent leakage of contents. The material of the lead 2 is preferably selected according to the material of the current collector in the secondary battery to be connected. For example, in the case of a lithium ion battery, since aluminum is used for the current collector of the positive electrode, the material of the lead 2 of the positive electrode is preferably aluminum, and the purity of 1N30 or the like from the viewpoint of corrosion resistance to the electrolytic solution More preferably, the aluminum is 97% or more. In the case where the heat-sealed portion between the lead 2 and the outer packaging material 10 is bent after manufacturing the secondary battery, the positive electrode material of the lead 2 is more preferably an O material tempered by annealing from the viewpoint of flexibility. Moreover, since copper is used for the current collector on the negative electrode side, the material of the lead 2 on the negative electrode side is preferably copper. The lead 2 preferably has a nickel plating layer on the surface from the viewpoint of corrosion resistance.

  The thickness of the lead 2 is selected according to the size or capacity of the battery, and is about 50 μm to 100 μm for a small size, and about 100 μm to 500 μm for a power storage / in-vehicle use. From the viewpoint of reducing the electrical resistance of the lead 2, the lead 2 having a greater thickness may be used.

  The container includes a lead heat fusion part 31 that is formed from the outer packaging material 10 for the secondary battery so that the heat fusion resin layer 14 is on the inner side and is thermally fused together with the leads 2. The length L of the lead heat fusion part 31 in the extending direction of the lead 2 is preferably 3 mm or more and 20 mm or less, and more preferably 5 mm or more and 15 mm or less. When the length L of the lead heat fusion part 31 is 3 mm or more, the amount of moisture permeated from the end of the exterior material can be reduced, and when it is 20 mm or less, the installation area of the entire secondary battery 30 is reduced. Can be reduced.

  The lead 2 is sandwiched and sealed by an exterior material 10 that forms a container with the heat-sealing resin layer 14 inside. It is preferable that the lead 2 is sandwiched in a state where the heat-sealing resin layer 14 is in direct contact with the lead 2 without using a tab sealant. Since the lead 2 and the heat sealing resin layer 14 are in direct contact and no tab sealant is used, the thickness of the lead heat sealing part 31 can be reduced in the secondary battery 30, and the exterior material The amount of moisture permeating from the end can be reduced.

(Method for manufacturing secondary battery 30)
Next, a method of manufacturing the secondary battery 30 using the above-described secondary battery exterior material 10 will be described. Here, a case where an embossed type exterior material is used will be described as an example. (A)-(d) of FIG. 3 is a perspective view which shows the manufacturing process of the one side molded process battery using the exterior material 10 for secondary batteries which concerns on this embodiment. The secondary battery 30 is a double-sided molded battery that is manufactured by bonding two exterior materials such as the embossed-type exterior material 20 and bonding the exterior materials together while adjusting the alignment. Also good.

The secondary battery 30 that is a one-side molded battery can be manufactured, for example, by the following steps S21 to S25.
Step S21: A step of preparing a secondary battery exterior member 10, a battery element 1 including an electrolyte and an electrode, and a lead 2 extending from the electrode.
Step S22: A step of forming a recess 22 for disposing the battery element 1 on one side of the exterior material 10 (see FIGS. 3A and 3B).
Step S23: The battery element 1 is arranged in the molding processing area (recess 22) of the embossed type exterior member 20, and the embossed type exterior member 20 is folded over and overlapped so that the lid 24 covers the recess 22 and extends from the battery element 1. A step of pressurizing and heat-bonding one side of the embossed type exterior member 20 so as to sandwich the lead 2 to be held (see FIGS. 3B and 3C).
Step S24: Leave one side other than the side sandwiching the lead 2 and pressurize and melt the other side, then inject the electrolyte from the remaining side and pressurize and heat-bond the remaining side in a vacuum state Step (see FIG. 3C).
Step S25: A step of cutting the end of the press-fusing side other than the side sandwiching the lead 2 and bending it to the side of the molding area (recess 22) (see FIG. 3D).

[Step S22]
In step S <b> 22, the recess 22 for arranging the battery element 1 is formed on the heat sealing resin layer 14 side of the exterior material 10. Examples of the method for forming the recess 22 include a molding process using a mold (deep drawing molding). As a molding method, a female mold and a male mold disposed so as to have a gap larger than the thickness of the exterior material 10 are used, and the male mold is pushed into the female mold together with the exterior material 10. Is mentioned. By adjusting the pushing amount of the male mold, the depth (depth drawing amount) of the recess 22 can be adjusted to a desired amount. The embossed type exterior material 20 is obtained by forming the recess 22 in the exterior material 10. Step S22 may be omitted as necessary.

[Step S23]
In step S23, the battery element 1 including the positive electrode, the separator, the negative electrode, and the like is disposed in the molding area (recess 22) of the embossed type exterior material 20, and extends from the battery element 1, and the positive electrode and the negative electrode The leads 2 respectively joined to are drawn out from the molding area (recess 22). Thereafter, the embossed-type exterior member 20 is folded back at the approximate center in the longitudinal direction, and the heat-bonding resin layers 14 are overlapped with each other so that one side sandwiching the lead 2 of the embossed-type exterior member 20 is pressurized heat. Fused. The pressure heat fusion is controlled by three conditions of temperature, pressure, and time, and the temperature of the pressure heat fusion is appropriately set above the temperature at which the heat fusion resin layer 14 is melted.

  Note that the thickness of the heat-sealing resin layer 14 before heat-sealing is preferably 40% or more and 80% or less with respect to the thickness of the lead 2. When the thickness of the heat-sealing resin layer 14 is equal to or greater than the lower limit value, the heat-sealing resin tends to sufficiently fill the end of the lead 2, and when the thickness is equal to or less than the upper limit value, The thickness of the end portion of the exterior material 10 can be moderately suppressed, and the amount of moisture intrusion from the end portion of the exterior material 10 can be reduced.

[Step S24]
In step S24, one side other than the side sandwiching the lead 2 is left and the other side is subjected to pressure heat fusion. Thereafter, an electrolytic solution is injected from the remaining side, and the remaining side is pressurized and heat-sealed in a vacuum state. The conditions for the pressure heat fusion are the same as in step S23.

[Step S25]
The peripheral pressurization heat fusion side edge part other than the edge | side which pinches | pinches the lead 2 is cut, and the heat sealing resin layer 14 which protruded from the edge part is removed. Then, the secondary battery 30 is obtained by folding the peripheral pressure heat-sealed portion toward the molding area 22 and forming the folded portion 32.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the scope of the present invention is not limited to these examples.

[Materials used]
The materials used to form the base material layer, the barrier layer, the adhesive resin layer, and the heat-sealing resin layer of the exterior materials according to the examples and comparative examples are shown below. In addition, the structure of the exterior material which concerns on an Example and a comparative example is the same as that of the structure shown in FIG.

(Base material layer 11)
Base material A-1: Biaxially stretched polyethylene terephthalate film (thickness: 25 μm)

(Barrier layer 12)
Barrier layer B-1: Silicon oxide vapor deposition film (thickness: 80 nm)
Barrier layer B-2: Aluminum foil (thickness: 40 μm)

(Adhesive resin layer 13)
Adhesive C-1: Maleic anhydride-modified polypropylene

(Heat-fusion resin layer 14)
Thermal fusion resin D-1: Polypropylene film (MFR: 10 g / 10 min, melting point: 150 ° C.)
Thermal fusion resin D-2: Polypropylene film (MFR: 30 g / 10 min, melting point: 125 ° C.)
Thermal fusion resin D-3: Polypropylene film (MFR: 14 g / 10 min, melting point: 105 ° C.)
Thermal fusion resin D-4: Polypropylene film (MFR: 20 g / 10 min, melting point: 135 ° C.)
Thermal fusion resin D-5: Polypropylene film (MFR: 20 g / 10 min, melting point: 158 ° C.)
Thermal fusion resin D-6: Maleic anhydride-modified polypropylene film (MFR: 23 g / 10 min, melting point: 126 ° C.)
Thermal fusion resin D-7: Polypropylene film (MFR: 50 g / 10 min, melting point: 90 ° C.)
Thermal fusion resin D-8: Polypropylene film (MFR: 4 g / 10 min, melting point: 146 ° C.)

(Lead 2)
Lead E-1: Aluminum metal terminal (thickness: 50 μm, width: 12 mm, length: 50 mm)

[Preparation of exterior material 10]
(Example 1)
A barrier layer B-1 (80 nm) was formed on the substrate A-1 by a vacuum deposition method. Next, the adhesive C-1 is coated on the surface of the barrier layer opposite to the base material so that the thickness after lamination is 3 μm, and heat fusion is performed on the coated adhesive C-1. Overlaying resin D-1 (thickness: 40 μm) was laminated by dry lamination at 100 ° C. Thereafter, aging was performed to prepare an exterior material. Next, the exterior material was cut into a size of 240 mm × 70 mm and folded at the midpoint of the long side. The lead E-1 is sandwiched between the short sides of the folded outer packaging material, the fusion temperature is 160 ° C., the fusion surface pressure is 0.5 MPa, the fusion time is 3 seconds, and the lead is thermally fused in the direction in which the lead extends. A sample for evaluation was prepared by heat and pressure welding under the condition that the length of the part was 10 mm.

(Examples 2-7 and 9 and Comparative Examples 1-2)
Examples 2 to 7 and 9 and Comparative Examples were the same as Example 1 except that the materials used for forming the heat-sealing resin layer 14 and the layer thicknesses were changed as shown in Table 1. Samples for evaluation 1 or 2 were produced.

(Example 8)
A sample for evaluation was prepared in the same manner as in Example 1 except that the heat-sealing resin D-5 (thickness: 40 μm) was used to form the heat-sealing resin layer, and the fusing temperature was changed to 170 ° C. .

(Comparative Example 3)
The barrier layer B-2 is coated with a two-component curable polyester urethane adhesive so that the thickness after lamination is 4 μm, and the substrate A- is coated on the two-component curable polyester urethane adhesive after coating. 1 were stacked, and these were laminated by dry lamination at 40 ° C. Next, the adhesive C-1 is coated on the surface of the barrier layer opposite to the base material so that the thickness after lamination is 3 μm, and the coated adhesive C-1 is heated on the surface. Fusing resin D-1 (thickness: 40 μm) was stacked and laminated by dry lamination at 100 ° C. Thereafter, aging was performed to prepare an exterior material. The obtained exterior material was processed in the same manner as in Example 1 to prepare an evaluation sample.

[Sample Evaluation]
(Fillability)
The end of the exterior material in the lead heat-sealed part of the sample for evaluation prepared in Examples and Comparative Examples was immersed in a highly permeable dyeing solution (manufactured by Taiho Kozai Co., Ltd., Microcheck) at room temperature (23 ° C.) for 60 minutes. . The edge part of the exterior packaging material after immersion was observed with the naked eye, and it was judged that the dye penetrated with the staining solution was stained. And it was judged that what was judged not to be dyed was sufficiently filled with the lead, and what was dyed was judged to be not sufficiently filled with the lead. Fillability was evaluated according to the following criteria.
A: Out of 50 samples, 0 samples were dyed by permeation of the high-permeability dyeing solution into the edge of the exterior material.
B: Among 50 samples, one or more samples were dyed by permeation of the high-permeability dyeing solution into the edge of the exterior material.

(Adhesion)
The adhesion between the lead of the evaluation sample prepared in the example and the comparative example and the exterior material was measured according to the following criteria by measuring the peel strength between the exterior material and the lead. The peel strength was measured by peeling the exterior material from the lead using a tensile tester, and the measurement conditions were a measurement width of 12 mm, a tensile speed of 100 mm / min, and a T-type peel.
A: Compared to the peel strength of the sample of Example 1, the peel strength is 120% or more.
B: Compared with the peel strength of the sample of Example 1, the peel strength is 80% or more and less than 120%.
C: Compared to the peel strength of the sample of Example 1, the peel strength is less than 80%.

(Heat-resistant)
The outer packaging material including the peripheral pressure heat-sealed portion of the sample for evaluation produced in Examples and Comparative Examples that does not include the lead was cut into a size of 100 mm × 15 mm to obtain a sample for heat resistance evaluation. After the sample for heat resistance evaluation was allowed to stand at 90 ° C. for 5 minutes in the atmosphere, the peel strength at the peripheral pressure heat-sealed portion between the exterior materials was measured by T-type peel at 90 ° C. in the air at a pulling rate of 100 mm / min. The heat resistance of the peripheral pressurization heat fusion part was evaluated according to the following criteria based on the obtained peel strength.
A: Compared to the peel strength of the sample of Example 1, the peel strength is 80% or more.
B: Compared with the peel strength of the sample of Example 1, the peel strength is less than 80%.

(Insulation)
The presence or absence of a short circuit between the lead of the sample for evaluation produced in the example and the comparative example and the barrier layer of the exterior material was confirmed by a tester. Insulation was evaluated according to the following criteria.
A: 0 out of 10 samples.
B: One or more short-circuited samples out of 10 samples.

(Water vapor barrier property)
The exterior material cut into a size of 240 mm × 70 mm obtained in the example and the comparative example is folded back at the middle point of the long side, and the ends of the two sides of the folded long side are 5 mm in width and are the same as the respective examples and comparative examples. Under the conditions of pressure and heat fusion. Next, ethylene carbonate (EC), dimethyl carbonate (DMC) and diethyl carbonate (DEC) are mixed at a weight ratio (1: 1: 1) from the short side which is not heat-sealed under pressure, and the water content is adjusted. 3 mg of electrolyte solution suppressed to 20 ppm or less was injected in a dry atmosphere. Thereafter, similarly, the end of the short side that was not pressure-heat bonded was pressure-heat bonded with a width of 10 mm to produce a 120 mm × 70 mm water vapor barrier property evaluation sample. The produced water vapor barrier property evaluation sample was stored in an environment of 60 ° C. and 90% RH for 4 weeks, and the water content in the electrolyte after storage was measured with a Karl Fischer tester. The water vapor barrier property was evaluated according to the following criteria based on the obtained water content.
A: Compared with the moisture content of the sample of Example 1, the moisture content is less than 75%.
B: Compared with the moisture content of the sample of Example 1, the moisture content is 75% or more and less than 100%.
C: Compared with the moisture content of the sample of Example 1, the moisture content is 100% or more and less than 125%.
D: Compared with the moisture content of the sample of Example 1, the moisture content is 125% or more.

(Heat seal strength)
In the peripheral pressurization heat fusion part of the part not including the lead of the sample for evaluation prepared in Examples and Comparative Examples, the peel strength when the other exterior material is peeled off from the other exterior material is determined by a tensile tester. It was measured by a measurement width of 15 mm, a tensile speed of 100 mm / min, and T-type peeling. The heat seal strength was evaluated according to the following criteria based on the obtained peel strength.
A: Compared to the peel strength of the sample of Example 1, the peel strength is 120% or more.
B: Compared with the peel strength of the sample of Example 1, the peel strength is 80% or more and less than 120%.
C: Compared to the peel strength of the sample of Example 1, the peel strength is less than 80%.

  Table 2 shows the evaluation results of fillability, adhesion, heat resistance, insulation, water vapor barrier properties, and heat seal strength.

  Comparing the evaluation results of the fillability, the fillability was obtained in Examples 1 to 9 and Comparative Examples 1 and 3, whereas the fillability was not obtained in Comparative Example 2. In Comparative Example 2, it is considered that the melt mass flow rate of the heat-sealing resin layer was low and the lead end portion was not filled.

  When the evaluation results of the adhesion were compared, the adhesion was obtained in Examples 1 to 9 and Comparative Examples 2 to 3, whereas in Comparative Example 1, sufficient adhesion was not obtained. In Comparative Example 1, it is considered that the strength was not obtained because the heat-sealing resin layer flowed excessively at the time of pressure heat-sealing.

  When the evaluation results of heat resistance were compared, in Examples 1-9 and Comparative Examples 2-3, peel strength was obtained even under high temperature conditions, whereas in Comparative Example 1, sufficient strength was not obtained. . In Comparative Example 1, it is considered that the melting point of the resin of the heat-sealing resin layer was low and started to melt at a high temperature.

  When comparing the evaluation results of the insulating properties, in Examples 1 to 9 and Comparative Examples 1 and 2, insulating properties were obtained, whereas in Comparative Example 3, a short circuit occurred between the exterior material and the leads. In Comparative Example 3, a conductive aluminum foil was used for the barrier layer, and the heat-sealing resin layer had high fluidity. It is considered that the film became thinner, the aluminum foil and the lead were electrically connected, and a short circuit occurred.

  When the evaluation results of the water vapor barrier properties were compared, the water vapor barrier properties were obtained in Examples 1 to 9 and Comparative Examples 1 and 3, whereas the water vapor barrier properties were not obtained in Comparative Example 2. In Comparative Example 2, it is considered that the lead filling was not sufficient and the amount of water vapor entered was increased.

  When the evaluation results of the heat seal strength were compared, in Examples 1 to 9 and Comparative Examples 1 to 3, the heat seal strength was obtained.

DESCRIPTION OF SYMBOLS 1 ... Battery element, 2 ... Lead 10, 10a ... Exterior material (exterior material for secondary batteries), 11 ... Base material layer, 12 ... Barrier layer, 13 ... Adhesive resin layer, 14 ... Thermal fusion resin layer, 20 DESCRIPTION OF SYMBOLS ... Embossing type exterior material, 22 ... Molding process area (concave part), 24 ... Cover part, 30 ... Secondary battery, 31 ... Lead heat fusion part, L ... Lead heat fusion part length.

Claims (10)

A base material layer, a barrier layer formed on one surface of the base material layer, and a heat-sealing resin layer formed on the surface of the barrier layer opposite to the base material layer. A secondary battery exterior material,
The barrier layer is made of an electrically insulating material,
The exterior material for secondary batteries whose melt mass flow rate of the said heat-fusion resin layer is 10 g / 10min or more and 30 g / 10min or less in the temperature of 230 degreeC and a load of 2.16kg.   The packaging material for a secondary battery according to claim 1, wherein the melting point of the resin of the heat-sealing resin layer is 100 ° C. or higher and 150 ° C. or lower.   The packaging material for a secondary battery according to claim 1 or 2, wherein a thickness of the heat sealing resin layer is 20 µm or more and 90 µm or less.   The exterior material for secondary batteries according to any one of claims 1 to 3, wherein the heat-sealing resin layer contains an acid-modified polyolefin resin.   The said barrier layer is an exterior material for secondary batteries as described in any one of Claims 1-4 which consists of an inorganic oxide or an organic barrier film. A battery element including an electrolytic solution and an electrode, a lead extending from the electrode, and a container containing the battery element,
The container is formed from the secondary battery exterior material according to any one of claims 1 to 5 such that the heat-sealing resin layer is inside,
The lead is a secondary battery that is sandwiched by the exterior material forming the container with the heat-sealing resin layer as an inner side.   The secondary battery according to claim 6, wherein the lead is sandwiched by the exterior material in a state where the heat-sealing resin layer is in direct contact with the lead. The container has a lead heat fusion part heat-sealed together with the lead,
The secondary battery according to claim 6 or 7, wherein a length of the heat-sealing portion in the extending direction of the leads is 3 mm or more and 20 mm or less. A step of preparing a packaging material for a secondary battery according to any one of claims 1 to 5, a battery element including an electrolytic solution and an electrode, and a lead extending from the electrode;
Arranging the battery element and a part of the lead between the exterior materials with the heat-sealing resin layer inside;
Heat-sealing the periphery of the exterior material such that the lead is sandwiched by the exterior material with the heat-sealing resin layer disposed inside;
A method for manufacturing a secondary battery.   10. The method of manufacturing a secondary battery according to claim 9, wherein a thickness of the heat sealing resin layer before heat sealing is 40% or more and 80% or less with respect to a thickness of the lead.

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