JP2016004656A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery capable of improving steam barrier properties while securing insulation properties.SOLUTION: A secondary battery 10 includes: a metal foil laminated film 20 formed by laminating a metal foil layer and a heat-fusion resin layer; a non-conducting laminated film 30 formed by laminating a non-conducting barrier layer and a heat-fusion resin layer; a battery element housed between the metal foil laminated film 20 and the non-conducting laminated film 30; a positive electrode lead and a negative electrode lead 42 which extend from the battery element toward the outside of the battery; and a tab sealant 44 provided only between the positive electrode lead and the metal foil laminated film 20 and between the negative electrode lead 42 and the metal foil laminated film 20.

Description

  The present invention relates to a secondary battery.

  In recent years, mobile devices such as mobile phones, smartphones, and music playback devices, and automobiles such as hybrid electric vehicles and electric vehicles have been widely used. Secondary batteries typified by nickel metal hydride batteries and lithium ion batteries are used as batteries for supplying electricity as power sources and power sources. Secondary batteries for portable devices are required to be lighter and more compact, and in-vehicle secondary batteries, in addition to being lighter and more compact, they can also be arranged in parallel or in series with higher energy or higher output. Corresponding to the multilayering is required. In secondary batteries, metal cans and laminate film exterior materials are properly used depending on the application and usage environment, but laminate film exterior materials are attracting attention from the viewpoints of weight reduction and shape flexibility.

  In such a secondary battery, if moisture penetrates into the inside, the desired battery performance may not be satisfied due to heat generation of the lithium salt that is an electrolyte. When a laminate film exterior material is used, an aluminum foil is used as a water vapor barrier layer. Metal foil such as is used. By using an exterior material including a metal foil, moisture permeation from the film surface is suitably suppressed. By the way, in order to supply electric power from the battery element inside the battery to the outside, the secondary battery is provided with a metal lead, and this lead is connected to the end of the exterior material via a tab sealant that is a resin film. The part is bonded and fixed with a predetermined adhesiveness and sealing property. This tab sealant for fixing the lead not only provides the above-mentioned functions such as adhesiveness and sealing performance, but also provides the function of ensuring the insulation between the metal foil exposed at the end of the exterior material and the lead. . However, in order to sufficiently perform the above-described functions such as adhesion and insulation, it is necessary to increase the thickness of the metal terminal portion including the lead and the tab sealant, and moisture enters the battery from the thick metal terminal portion. In some cases. Therefore, for example, Patent Document 1 proposes a method of adjusting the film thickness in the peripheral portion of the lead to suppress the intrusion of moisture from the metal terminal portion.

Japanese Patent Laid-Open No. 10-289698

  However, the method described in Patent Document 1 is intended to suppress the ingress of moisture into the battery, and is not sufficient to ensure the insulation between the metal foil in the exterior material and the lead. It was. As described above, in the conventional technology, it is possible to suppress the deterioration of the water vapor barrier property by increasing the film thickness of the tab sealant to some extent. On the other hand, if the tab sealant is too thin, the metal foil and the lead in the exterior material can be prevented. As a result, it is difficult to achieve both the suppression of moisture permeation from the metal terminal portion and the insulation between the metal foil of the exterior material and the leads.

  Therefore, an object of the present invention is to provide a secondary battery that can prevent a short circuit between a barrier layer of an exterior material and a lead to ensure insulation and further improve water vapor barrier properties.

  The secondary battery according to the present invention includes, as one aspect thereof, a metal foil laminate film formed by laminating at least a metal foil barrier layer including a metal foil and a first sealant layer, a non-conductive barrier layer, A non-conductive laminate film formed by laminating at least a second sealant layer that is fusion-bonded to at least a part of one sealant layer, an electrolyte, and a metal foil laminate film and a non-conductive laminate A battery element housed between the film, a positive electrode lead and a negative electrode lead extending from the battery element toward the outside of the battery, and a tab sealant provided between the positive electrode lead, the negative electrode lead and the metal foil laminate film It is characterized by having.

  In the secondary battery described above, the exterior material is composed of two laminate films, one is a metal foil laminate film, and the other is a non-conductive laminate film, which is necessary between the metal terminal portion and the laminate film. The tab sealant can be provided with an extremely thin one only on the metal foil laminate film side or on the non-conductive laminate film side, and the total thickness of the tab sealant can be reduced. In this case, the infiltration of moisture from the metal terminal portion can be suppressed, and the water vapor barrier property can be improved. Moreover, since the other laminate film is a non-conductive laminate film, even if no tab sealant is provided on the non-conductive laminate film side, or an extremely thin film is provided, it is a non-conductive barrier for exterior materials. Since a short circuit does not occur between the layer and the lead, insulation can be easily ensured. As described above, according to the secondary battery of the present invention, it is possible to achieve both insulation and improvement of the water vapor barrier property.

  In the above secondary battery, the tab sealant is preferably provided only between the positive electrode lead and the negative electrode lead and the metal foil laminate film. In the above secondary battery, it is preferable that the second sealant layer of the non-conductive laminate film is directly bonded to the positive electrode lead and the negative electrode lead. In these cases, since the metal terminal portion can be made thinner, it is possible to further improve the water vapor barrier property while ensuring insulation.

  In the above secondary battery, the second sealant layer of the non-conductive laminate film is preferably an acid-modified polyolefin resin layer. In this case, the positive electrode lead, the negative electrode lead, and the non-conductive laminate film can be bonded more firmly without arranging the tab sealant.

  In the above secondary battery, the nonconductive barrier layer may be a barrier layer containing an inorganic oxide. In this case, a high water vapor barrier property can be ensured.

  In the above secondary battery, at least a part of the metal foil laminate film may have a concave shape. Although the film can be formed into a concave shape by molding or the like on the laminate film, the volume of the battery element to be accommodated can be increased by processing into such a shape. In the case of a metal foil laminate film, since the stretchability is good, the barrier layer is often difficult to break even if it is molded. As a result, it is possible to easily increase the depth of molding, that is, increase the volume of the included battery element without impairing the water vapor barrier property.

  ADVANTAGE OF THE INVENTION According to this invention, water vapor | steam barrier property can be improved, preventing the short circuit with the barrier layer of an exterior material, and a lead, and ensuring insulation.

1 is a perspective view showing a secondary battery according to an embodiment of the present invention. It is sectional drawing along the II-II line of the secondary battery shown in FIG. It is sectional drawing which shows the layer structure of the metal foil laminated film which comprises the secondary battery shown in FIG. It is sectional drawing which shows the layer structure of the nonelectroconductive laminate film which comprises the secondary battery shown in FIG. It is a typical perspective view which shows the state at the time of manufacturing the secondary battery shown in FIG.

  Hereinafter, embodiments of a secondary battery according to the present invention will be described in detail with reference to the drawings. In the description, the same reference numerals may be used for the same elements or elements having the same function, and redundant description is omitted.

  FIG. 1 is a perspective view showing a secondary battery according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II of the secondary battery shown in FIG. FIG. 3 is a cross-sectional view showing a layer structure of a metal foil laminate film constituting a secondary battery, and FIG. 4 is a cross-sectional view showing a layer structure of a non-conductive laminate film constituting a secondary battery. The secondary battery 10 is, for example, a lithium ion secondary battery, and as shown in FIGS. 1 to 4, a metal foil layer 24 (metal foil barrier layer), a heat-sealing resin layer 27 (first sealant layer), and the like. A non-conductive laminate film 30 formed by laminating a metal foil laminate film 20 formed by laminating a non-conductive barrier layer 32 and a heat-sealing resin layer 34 (second sealant layer), and the like. A battery element 40 including an electrolyte (see FIG. 4), a positive electrode lead and a negative electrode lead 42 extending from the battery element 40 toward the outside of the battery, a positive electrode lead and a negative electrode lead 42, and the metal foil laminate film 20 And a tab sealant 44 provided therebetween.

  The battery element 40 is made of, for example, an aprotic solvent such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, or ethyl methyl carbonate together with a separator for preventing contact between the positive electrode material and the negative electrode material and the electrodes. And an electrolyte layer made of an electrolyte solution in which an electrolyte (lithium salt) is dissolved or a polymer gel impregnated with the electrolyte solution. The battery element 40 is accommodated between the metal foil laminate film 20 and the non-conductive laminate film 30 in which the surfaces 20b and 30b of the heat sealing resin layers 27 and 34 are opposed to each other (see FIG. 5). In the secondary battery 10, the metal foil laminate film 20 containing the battery element 40 and the nonconductive laminate film 30 are bonded together by heat sealing, and the peripheral ends thereof are heat-sealed. Thereby, the airtightness inside a battery is ensured.

  The positive electrode lead and the negative electrode lead 42 are metal members extending from the battery element 40 accommodated in the secondary battery 10 toward the outside of the battery (see FIG. 5). The positive electrode lead and the negative electrode lead 42 can supply electric power from the battery element 40 to the outside. As shown in FIG. 2, a tab sealant 44 is disposed on the positive electrode lead and the negative electrode lead 42 on the metal foil laminate film 20 (heat-sealing resin layer 27) side. And the metal foil laminate film 20 are more securely adhered and bonded. On the other hand, in the secondary battery 10, the tab sealant 44 is not disposed on the non-conductive laminate film 30 side of the positive electrode lead and the negative electrode lead 42, and the heat-sealing resin layer 34 of the non-conductive laminate film 30 is the positive electrode lead. And directly bonded to the negative electrode lead 42. In the secondary battery 10 shown in the present embodiment, the tab sealant 44 is provided only between the lead 42 and the metal foil laminate film 20, but an extremely thin tab sealant is provided on the non-conductive laminate film 30 side. It may be provided to improve the adhesion between them.

  The tab sealant 44 is preferably a resin excellent in adhesion / adhesion between the lead 42 and the heat-sealing resin layer 27. For example, an acid-modified polyolefin resin obtained by graft-modifying maleic anhydride or the like on a polyolefin resin. Is preferably used. The tab sealant 44 may be a single layer of an acid-modified polyolefin resin, or may be a laminate of a heat-resistant resin such as PET on an acid-modified polyolefin resin. The material is not particularly limited as long as it can provide predetermined adhesion and the like. The total thickness of the tab sealant 44 is preferably 60 μm or more and 150 μm or less, and more preferably 80 μm or more and 100 μm or less in order to obtain good adhesion between the lead 42 and the metal foil laminate film 20. .

[Metal foil laminate film 20]
Here, the configuration of the metal foil laminate film 20 which is one exterior material constituting the secondary battery 10 will be described in more detail with reference to FIG.

  The metal foil laminate film 20 is formed by sequentially laminating a corrosion prevention treatment layer 25, an adhesive layer 26 and a heat-sealing resin layer 27 on one surface (lower side in the drawing) of the sheet-like metal foil layer 24. This is a laminate in which a base material layer 21 is laminated on the other surface (upper side in the drawing) side of the layer 24 via an adhesive layer 22. A corrosion prevention treatment layer 23 may be further provided between the metal foil layer 24 and the adhesive layer 22. In such a metal foil laminate film 20, the base material layer 21 is the outermost layer and the heat-sealing resin layer 27 is the innermost layer. That is, the metal foil laminate film 20 is used with the base material layer 21 on the outer side of the secondary battery 10 and the heat-sealing resin layer 27 on the inner side of the secondary battery 10, and the surface 20a of the metal foil laminate film 20 is The outer surface of the secondary battery 10 is constituted, and the surface 20 b constitutes the inner surface of the secondary battery 10 and the bonding surface with the nonconductive laminate film 30.

  The metal foil laminate film 20 can be produced by a known dry lamination method, extrusion sand lamination method, co-extrusion lamination method, or the like, but the construction method is not particularly limited. Note that the metal foil laminate film 20 shown in FIG. 3 is a film produced by, for example, a dry lamination method.

  Next, the detail of each layer which comprises the metal foil laminated film 20 is demonstrated.

(Base material layer 21)
The base material layer 21 is formed on the metal foil layer 24 via the adhesive layer 22. The base material layer 21 provides the metal foil laminate film 20 with heat resistance in the heat sealing process when the secondary battery 10 is manufactured, and also suppresses the occurrence of pinhole defects that may occur during processing and distribution. Fulfill. In addition, it plays a role of preventing breakage of the metal foil layer 24 at the time of embossing molding and insulating properties for preventing contact between the metal foil layer 24 and other metals. As the base material layer 21, for example, a stretched or unstretched film such as a polyester resin, a polyamide resin, or a polyolefin resin can be used. Among these resins, it is preferable to use a biaxially stretched polyamide film or a biaxially stretched polyester film as the substrate layer 21 from the viewpoint of improving moldability, heat resistance, puncture resistance, and insulation. The base material layer 21 may be comprised from the single film which is one film, and may be comprised from the composite film which bonded two or more films together.

  The base material layer 21 may be internally dispersed or coated with an additive such as a flame retardant, slip agent, anti-blocking agent, antioxidant, light stabilizer, tackifier, or antistatic agent. . Examples of the slip agent include fatty acid amides (for example, oleic acid amide, erucic acid amide, stearic acid amide, behenic acid amide, ethylene bisoleic acid amide, or ethylene biserucic acid amide). As the antiblocking agent, it is preferable to use various filler-based antiblocking agents such as silica. An additive may be used individually by 1 type and may use 2 or more types together.

  The thickness of the base material layer 21 is preferably 6 μm or more from the viewpoint of puncture resistance and insulation, is preferably 50 μm or less from the viewpoint of embossability, and more preferably is 10 μm or more and 40 μm or less. An uneven shape may be formed on the surface of the base material layer 21 in order to improve scratch resistance and slipperiness.

(Adhesive layer 22)
The adhesive layer 22 is formed between the base material layer 21 and the metal foil layer 24. The adhesive layer 22 not only has an adhesive force necessary to firmly bond the base material layer 21 and the metal foil layer 24, but also protects the metal foil layer 24 from being broken by the base material layer 21 during emboss molding. In order to do so, it has following ability. As the adhesive layer 22, a two-component curable adhesive using a polyester polyol, a polyether polyol, an acrylic polyol, or the like as a main agent and an aromatic or aliphatic isocyanate as a curing agent can be used. A thermoplastic elastomer, a tackifier, a filler, a pigment, a dye, or the like can be added to the adhesive layer 22. The thickness of the adhesive layer 22 is preferably 0.5 μm or more from the viewpoint of adhesive strength or followability, preferably 10 μm or less, more preferably 1 μm or more and 5 μm or less from the viewpoint of workability.

(Metal foil layer 24)
The metal foil layer 24 is formed between the adhesive layer 22 and the adhesive layer 26. The metal foil layer 24 has a high water vapor barrier property in order to prevent moisture (water vapor) from entering the battery, and also has a high stretchability in order to suppress breakage and the like during molding. doing. As the metal foil layer 24, various metal foils such as aluminum, stainless steel, or copper can be used. From the viewpoint of weight (specific gravity), moisture resistance and cost, it is preferable to use an aluminum foil. As the aluminum foil used as the metal foil layer 24, a known soft aluminum foil can be used, and it is preferable to use an aluminum foil containing iron from the viewpoint of pinhole resistance and extensibility at the time of molding. The iron content in the aluminum foil is preferably 0.1% by mass or more and 9.0% by mass or less, and more preferably 0.5% by mass or more and 2.0% by mass or less. When the iron content is 0.1% by mass or more, pinhole resistance and stretchability are improved, and when it is 9.0% by mass or less, flexibility is improved. The thickness of the metal foil layer 24 is preferably 10 μm or more from the viewpoint of barrier properties and pinhole resistance, preferably 100 μm or less from the viewpoint of workability, and more preferably 15 μm or more and 80 μm or less. preferable.

(Corrosion prevention treatment layers 23, 25)
The corrosion prevention treatment layer 25 is formed on the heat sealing resin layer 27 side of the metal foil layer 24. For example, in a lithium ion secondary battery, the corrosion prevention treatment layer 25 is formed on the heat sealing resin layer 27 side in order to prevent surface corrosion of the metal foil layer 24 due to hydrofluoric acid generated by the reaction between the electrolyte and moisture. Since the surface of the metal foil layer 24 on the base material layer 21 side may corrode due to adhesion of the electrolytic solution or the like, the corrosion prevention treatment layer 23 is formed on the base material layer 21 side, that is, corrosion prevention is performed on both surfaces of the metal foil layer 24. More preferably, the treatment layers 23 and 25 are formed. The corrosion prevention treatment layers 23 and 25 function not only as a corrosion prevention function but also as an anchor layer with the adhesive layers 22 and 26. As the corrosion prevention treatment layers 23 and 25, for example, chromate treatment which is a corrosion prevention treatment agent composed of chromate, phosphate, fluoride and various thermosetting resins, cerium oxide which is an oxide of rare earth elements, A ceria sol treatment, which is a corrosion prevention treatment agent composed of phosphate and various thermosetting resins, can be used. The corrosion prevention treatment layers 23 and 25 are not limited to the coating film formed by the above treatment as long as the coating satisfies the corrosion resistance of the metal foil layer 24. For example, phosphate treatment or boehmite treatment is used. Also good. Further, the corrosion prevention treatment layers 23 and 25 are not limited to a single layer, and a structure having corrosion resistance with two or more layers such as coating a resin as an overcoat agent on a coating film having a corrosion prevention function is adopted. May be.

  The thickness of the corrosion prevention treatment layers 23 and 25 is not particularly limited, but is preferably 5 nm to 11 μm, for example, and more preferably 10 nm to 200 nm. When the thickness is less than 5 nm, the corrosion prevention function may be lowered. When the thickness exceeds 11 μm, the cohesive force is lowered, and there is a possibility that strength properties when used as a packaging material for a lithium ion battery are lowered.

(Adhesive layer 26)
The adhesive layer 26 is formed between the heat sealing resin layer 27 and the corrosion prevention treatment layer 25. As the adhesive layer 26, a two-component curable adhesive having a polyester polyol, a polyether polyol, an acrylic polyol, a polyolefin or the like as a main agent and an aromatic or aliphatic isocyanate as a curing agent can be used. . The film thickness of the adhesive layer 26 is preferably 1 μm or more and 5 μm or less. When the film thickness of the adhesive layer 26 is less than 1 μm, the adhesive strength is reduced, and thus a predetermined laminate strength cannot be obtained. On the other hand, in the case where the film thickness of the adhesive layer 26 exceeds 5 μm, the film becomes thick, and film cracking may occur.

(Heat-fusion resin layer 27)
The heat sealing resin layer 27 is formed on the corrosion prevention treatment layer 25 via the adhesive layer 26. By laminating the heat fusion resin layer 27 on the adhesive layer 26, the heat fusion resin layer 27 of the metal foil laminate film 20 and the heat fusion resin layer 34 of the non-conductive laminate film 30 are opposed to each other. By heat-sealing at a temperature equal to or higher than the melting temperature of the heat-sealing resin layer 27 and the heat-sealing resin layer 34, both can be sealed. As the heat sealing resin layer 27, a polyolefin resin can be used. Examples of the polyolefin resin include low density, medium density or high density polyethylene, homo, block or random polypropylene. In addition, a copolymer obtained by copolymerizing a polar molecule such as acrylic acid or methacrylic acid with the above-described resin, a polymer such as a crosslinked polyolefin, and the like can be used. These polyolefin resins may be used alone or in combination of two or more. From the viewpoint of heat resistance, the heat sealing resin layer 27 is preferably polypropylene rather than polyethylene as the polyolefin resin to be used. The heat-sealing resin layer 27 may contain various additives such as a slip agent, an anti-blocking agent, an antistatic agent, a nucleating agent, a pigment or a dye. These additives may be used alone or in combination of two or more.

  The thickness of the heat-sealing resin layer 27 is preferably 20 μm or more and 90 μm or less. When the thickness of the heat-sealing resin layer 27 is less than 20 μm, there is a possibility that the heat sealability and insulation properties may be lowered, and when the thickness of the heat-sealing resin layer 27 exceeds 90 μm, lithium ion When a packaging material for a battery is used, the moisture barrier property at the end may be lowered.

Next, a method for manufacturing the metal foil laminate film 20 will be described by showing an example of the embodiment. Examples of the method for producing the metal foil laminate film 20 include the following steps (I) to (III).
(I) Corrosion prevention treatment layers 23 and 25 are formed on both surfaces of the metal foil layer 24 by gravure coating.
(II) Subsequently, the base material layer 21 is bonded to the surface of the corrosion prevention treatment layer 23 of the metal foil layer 24 via the adhesive layer 22 using the dry lamination method, and the base material layer 21 and the adhesive layer 22 are bonded. Then, a laminate including the corrosion prevention treatment layer 23, the metal foil layer 24, and the corrosion prevention treatment layer 25 is formed.
(III) On the surface opposite to the base material layer 21 of the metal foil layer 24 of the laminate formed in (II), a heat-sealing resin layer 27 is used via an adhesive layer 26, and a dry lamination method is used. To form a metal foil laminate film 20.

  In addition, in the example of the manufacturing method of the metal foil laminate film 20 described above, the manufacturing method by the dry laminating method is shown. However, other manufacturing methods such as an extrusion sand laminating method or a coextrusion laminating method are known methods. It may also be formed by a combination of methods, and the method is not particularly limited.

[Non-conductive laminate film 30]
Next, the configuration of the non-conductive laminate film 30 which is the other exterior material constituting the secondary battery 10 will be described with reference to FIG.

  As shown in FIG. 4, the nonconductive laminate film 30 is formed by laminating a nonconductive barrier layer 32 on one surface (lower side in the drawing) of the base material layer 31, and an adhesive layer 33 and a heat-sealing resin layer 34 are formed. It is the laminated body laminated | stacked in order. In the non-conductive laminate film 30, the base material layer 31 is the outermost layer, and the heat-sealing resin layer 34 is the innermost layer. That is, the nonconductive laminate film 30 is used with the base material layer 31 on the outer side of the secondary battery 10 and the heat sealing resin layer 34 on the inner side of the secondary battery 10, and the surface of the nonconductive laminate film 30 is used. 30a constitutes the outer surface of the secondary battery 10, and the surface 30b constitutes the inner surface of the secondary battery 10 and the bonding surface with the metal foil laminate film 20. A coating layer may be further added to the outer surface of the base material layer 31 according to desired characteristics.

(Base material layer 31)
The base material layer 31 is not particularly limited, and a known material can be used. For example, a polyester film (polyethylene terephthalate, polyethylene naphthalate, etc.), a polyamide film (nylon-6, nylon-66, etc.). ), Polystyrene film, polyvinyl chloride film, polyimide film, polycarbonate film, polyethersulfone film, acrylic film, cellulose film (triacetyl cellulose, diacetyl cellulose, etc.), and the like. . The material of the base material layer 31 is not particularly limited, but is preferably a film having a low thermal shrinkage, and among them, a film excellent in chemical resistance is preferable. As the base material layer 31, it is preferable to use a material having high gas barrier properties such as polyethylene terephthalate, polyimides, or polyethersulfone. Moreover, the film thickness of the base material layer 31 is not specifically limited. The base material layer 31 may be subjected to various pretreatments such as corona treatment, plasma treatment, or frame treatment as long as the barrier property is not impaired, and various coating layers such as an easy adhesion layer and an anchor coating layer. May be provided.

(Non-conductive barrier layer 32)
As the non-conductive barrier layer 32, aluminum oxide (AlO _x ), silicon oxide (SiO _x ), magnesium fluoride (MgF ₂ ), magnesium oxide (MgO), or indium-tin oxide ( ITO) or the like can be used and can be formed by vapor deposition. As the nonconductive barrier layer 32, it is preferable to use aluminum oxide or silicon oxide which is an inorganic oxide from the viewpoint of material cost, barrier performance and transparency. A gas barrier layer may be coated on the vapor-deposited thin film layer for the purpose of improving barrier properties and scratch resistance, and may be subjected to corrosion prevention treatment for the purpose of improving chemical resistance. If the thickness of the non-conductive barrier layer 32 is less than 10 nm, there may be a problem in the continuity of the thin film. If the thickness exceeds 300 nm, curling and cracks are likely to occur, adversely affecting the barrier properties, and flexibility is reduced. May end up. For this reason, the thickness of the non-conductive barrier layer 32 is preferably 10 nm or more and 300 nm or less, and more preferably 20 nm or more and 200 nm or less.

  The non-conductive barrier layer 32 is preferably formed by vacuum from the viewpoint of barrier performance and film uniformity. As a method for forming the non-conductive barrier layer 32, a known method such as a vacuum deposition method, a sputtering method, or a chemical vapor deposition method (CVD method) can be applied. Since it is high, it is preferable to use a vacuum vapor deposition method, and it is particularly preferable to use a film forming means by electron beam heating of a film forming material.

(Adhesive layer 33)
The adhesive layer 33 is a layer for adhering the base material layer 31 and the heat-sealing resin layer 34 via the non-conductive barrier layer 32, and is a polyurethane resin, an acrylic resin, a polyester resin, or an epoxy resin. Any adhesive made of a resin, a polyolefin-based resin, or a copolymer resin of these resins can be used. The adhesive layer 33 can be bonded to the base material layer 31 and the heat-sealing resin layer 34 by a known method such as a so-called known dry lamination method or non-solvent lamination method. As long as the adhesive strength by the adhesive layer 33 is sufficient, the adhesive layer 33 is not particularly limited in its construction method.

  The film thickness of the adhesive layer 33 is preferably 1 μm or more and 5 μm or less. When the film thickness of the adhesive layer 33 is less than 1 μm, the adhesive strength is reduced, so that it is difficult to obtain a required laminate strength. On the other hand, when the film thickness of the adhesive layer 33 exceeds 5 μm, the film becomes thick, so that the film cracking of the barrier layer is likely to occur.

(Heat-fusion resin layer 34)
The heat sealing resin layer 34 is formed on the non-conductive barrier layer 32 via the adhesive layer 33. By laminating the heat fusion resin layer 34 on the adhesive layer 33, the heat fusion resin layer 27 of the metal foil laminate film 20 and the heat fusion resin layer 34 of the non-conductive laminate film 30 are opposed to each other. By performing heat sealing at a temperature equal to or higher than the melting temperature of the heat-sealing resin layer 27 and the heat-sealing resin layer 34, both the films 20 and 30 can be hermetically sealed. As the heat sealing resin layer 34, a polyolefin resin can be used. Examples of the polyolefin resin include low density, medium density, or high density polyethylene, homo, block, or random polypropylene. Examples of the heat-sealing resin layer 34 include a copolymer obtained by copolymerizing a polar molecule such as acrylic acid or methacrylic acid with these polyolefin resins, a polymer such as a crosslinked polyolefin, and the like, and dispersion or copolymerization was performed. Resin can be applied. These polyolefin resins may be used individually by 1 type, and may use 2 or more types together.

  The polyolefin resin used for the heat-sealing resin layer 34 is preferably polypropylene rather than polyethylene from the viewpoint of heat resistance. In order to further strengthen the adhesion to the lead 42 described later, it is more preferable to use an acid-modified polyolefin resin obtained by graft-modifying a polyolefin resin with maleic anhydride or the like as the heat-sealing resin layer 34. The heat-sealing resin layer 34 may contain various additives such as a slip agent, an antiblocking agent, an antistatic agent, a nucleating agent, a pigment, or a dye. These additives may be used individually by 1 type, and may use 2 or more types together.

Next, a method for manufacturing the non-conductive laminate film 30 will be described by showing an example of the embodiment. As a manufacturing method of the nonelectroconductive laminate film 30, the method of the following process (I) to (III) is mentioned, for example.
(I) A vapor-deposited thin film layer (non-conductive barrier layer 32) is formed on one surface of the base material layer 31 by vacuum film formation. For vacuum film formation, there are known methods such as vacuum vapor deposition, sputtering, or chemical vapor deposition (CVD), but vacuum vapor deposition is preferred because the film formation rate is high and productivity is high. A film forming means by electron beam heating of the film forming material is more preferable.
(II) On the vapor-deposited thin film layer (non-conductive barrier layer 32), a heat-sealing resin layer 34 is bonded using an adhesive layer 33 using a dry laminating method to produce a non-conductive laminate film 30. .

  In the above example of the method for producing the non-conductive laminate film 30, the production method by the dry lamination method is shown, but other production methods such as an extrusion sand lamination method or a co-extrusion lamination method are known methods. Or may be formed by a combination of methods, and the method is not particularly limited.

  Next, a method for manufacturing the secondary battery 10 will be described with reference to FIG.

  First, a metal foil laminate film 20 and a nonconductive laminate film 30 having the above-described configuration are prepared. In addition, a member 40a (for example, a positive electrode material, a negative electrode material, a separator, or the like) that constitutes the battery element 40, an electrolyte, a positive electrode and negative electrode lead 42, a pair of tab sealants 44, and the like are prepared.

  Subsequently, a molding recess 20c that can accommodate the battery element 40 is formed in the central portion of the metal foil laminate film 20 that is one of the exterior materials constituting the secondary battery 10 by cold molding or the like. Then, the member 40a which comprises the battery element 40 is accommodated in this shaping | molding recessed part 20c. In this accommodation, the metal foil laminate film 20, the positive electrode tab, the negative electrode lead 42, and the tab are arranged so that each tab sealant 44 is positioned between the positive electrode lead and the negative electrode lead 42 and the metal foil laminate film 20 (surface 20b). A sealant 44 is disposed.

  Subsequently, the metal foil laminate film 20 and the metal foil laminate film 20 are arranged so that the surface 30b of the non-conductive laminate film 30 faces the metal foil laminate film 20 (surface 20b) in which the member 40a constituting the battery element 40 is accommodated. The non-conductive laminate film 30 is aligned. Thereafter, the three sides of the overlapped films 20 and 30 are heat-sealed with a predetermined width and sealed. One of the three sides to be heat-sealed includes the side where the lead 42 and the tab sealant are disposed, but is heat-sealed and sealed in the same manner as the other two sides.

  Thereafter, an electrolytic solution (electrolyte) is injected into the battery from the remaining one side that is not heat-sealed. Then, the remaining one side that is not heat-sealed is similarly heat-sealed, whereby the secondary battery 10 is completed.

  Thus, in the secondary battery 10 according to the present embodiment, one of the exterior materials is the metal foil laminate film 20 and the other is the non-conductive laminate film 30, which is necessary between the lead 42 and the laminate film. The tab sealant 44 is provided only on the metal foil laminate film 20 side. For this reason, the total thickness of the metal terminal portion including the tab sealant can be reduced, the intrusion of moisture from the metal terminal portion can be suppressed, and the water vapor barrier property of the secondary battery 10 can be improved. In addition, since the other laminate film is the non-conductive laminate film 30, even if no tab sealant is provided on the non-conductive laminate film 30 side, between the barrier layer and the lead of the non-conductive exterior material. Since a short circuit does not occur, insulation can be easily ensured. As described above, according to the secondary battery 10, it is possible to achieve both insulation and improvement of the water vapor barrier property.

  In the secondary battery 10, the heat-sealing resin layer 34 of the nonconductive laminate film 30 may be an acid-modified polyolefin resin layer. In this case, the positive and negative electrode leads 42 and the non-conductive laminate film 30 can be bonded more firmly without disposing the tab sealant 44 on the non-conductive laminate film 30 side.

  In the secondary battery 10, the non-conductive barrier layer may be a barrier layer containing an inorganic oxide. In this case, a high water vapor barrier property can be ensured.

  In the secondary battery 10, the metal foil laminate film 20 has a concave shape at the center due to molding or the like. Since the secondary battery 10 has such a molded recess 20c, the volume of the battery element to be accommodated can be increased. In the case of the metal foil laminate film 20, since the stretchability is good, the metal foil layer 24 is often difficult to be damaged even if it is molded. As a result, it is possible to easily increase the depth of molding, that is, increase the volume of the included battery element without impairing the water vapor barrier property.

  The present invention is not limited to the above embodiment, and can be modified as appropriate without departing from the spirit of the present invention.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples.

  First, the following exterior materials A-1 to A-4 were prepared. The packaging material A-1 was an aluminum laminate film, and the packaging materials A-2 to A-4 were non-conductive laminate films.

Exterior Material A-1: Aluminum Laminate Film The layer structure of the exterior material A-1 is the base material layer 21, the adhesive layer 22, the metal foil layer 24, the corrosion prevention treatment layer 25, and the adhesive layer in the laminate shown in FIG. 26, corresponding to the heat-sealing resin layer 27, and laminated in the following order. The values in parentheses are the thickness of each layer, and so on.
Nylon film (25 μm) / Urethane adhesive (3 μm) / Aluminum foil (40 μm) / Corrosion prevention film / Polyolefin adhesive (3 μm) / Polypropylene film (40 μm)

Exterior Material A-2: Non-conductive Laminate Film The layer structure of the exterior material A-2 is the base material layer 31, the non-conductive barrier layer 32, the adhesive layer 33, and the heat-sealing resin layer in the laminate shown in FIG. 34, and were laminated in the following order.
PET (25 μm) / alumina deposited film (60 nm) / polyolefin adhesive (3 μm) / acid-modified polypropylene film (80 μm)

Exterior Material A-3: Non-conductive Laminate Film The layer structure of the exterior material A-3 is the base material layer 31, the non-conductive barrier layer 32, the adhesive layer 33, and the heat-sealing resin layer in the laminate shown in FIG. 34, and were laminated in the following order.
PET (25 μm) / polyvinylidene chloride (1 μm) / polyolefin adhesive (3 μm) / acid-modified polypropylene film (80 μm)

Exterior Material A-4: Non-conductive Laminate Film The layer structure of the exterior material A-4 is the base material layer 31, the non-conductive barrier layer 32, the adhesive layer 33, and the heat-sealing resin layer in the laminate shown in FIG. 34, and were laminated in the following order.
PET (25 μm) / Alumina deposited film (60 nm) / Polyolefin adhesive (3 μm) / Polypropylene film (80 μm)

  Also, a lead and a tab sealant were prepared. The positive electrode lead was made of aluminum, the negative electrode lead was made of nickel, and the thickness was 100 μm. The tab sealant was composed of an acid-modified polyolefin resin and had a thickness of 100 μm.

  Subsequently, as a secondary battery according to Example 1, a secondary battery having the same configuration as that of the secondary battery 10 illustrated in FIG. 1 was produced. Specifically, first, as one laminate type film exterior material S1 constituting the secondary battery, the exterior material A-1 is cut into a blank shape of 150 mm × 190 mm, and the dew point temperature is −35 ° C. (temperature 23 ° C.). The molding process was performed so that the molding depth was 5 mm under the molding environment. As a result, a recess having a depth of 5 mm for accommodating the battery element was formed. In addition, as a punch used for molding, the shape is 100 mm × 150 mm, the punch corner R (RCP) is 1.5 mm, the punch shoulder R (RP) is 0.75 mm, and the die shoulder R (RD) is 0.75 mm. It was used.

  Subsequently, the molded film exterior material S1 (exterior material A-1) is further cut out to 110 mm × 160 mm, an electrode member (battery element) is accommodated in the molded portion, and a tab sealant is thermocompression-bonded on one side, It arrange | positioned so that film exterior material S1 and tub sealant may contact | connect. That is, it arrange | positioned so that a tab sealant might be located between film exterior material S1 and a lead | read | reed. Thereafter, the heat-sealing resin layer of the laminate-type film exterior material S2 (exterior material A-2) cut out to 110 mm × 160 mm and the film exterior material S1 are overlapped, and 3 sides including the side having the lead are 5 mm wide. And heat sealed. In addition, said heat sealing was implemented without arrange | positioning a tab sealant between film exterior material S2 and a lead | read | reed. Then, the electrolyte solution was poured from the remaining one side which was not heat-sealed, and the secondary battery 10 was obtained by heat-sealing with a width of 5 mm.

  Subsequently, a secondary battery according to Example 2 was produced in the same manner as Example 1. In the secondary battery according to Example 2, the exterior material A-1 was used as the film exterior material S1, and the exterior material A-3 was used as the film exterior material S2. Further, in the secondary battery according to Example 2, as in Example 1, although the tab sealant is disposed on the film exterior material S1 side, heat sealing is performed without the tab sealant disposed on the film exterior material S2 side. went.

  Moreover, the secondary battery which concerns on Comparative Examples 1-5 was also produced like Example 1 grade | etc.,. In the secondary battery according to Comparative Example 1, the exterior material A-1 was used as the film exterior material S1, and the exterior material A-2 was used as the film exterior material S2. Also, in the secondary battery according to Comparative Example 1, unlike Example 1, heat sealing was performed by arranging tab sealants on both the film exterior material S1 side and the film exterior material S2 side.

  In the secondary battery according to Comparative Example 2, the exterior material A-1 was used as the film exterior material S1, and the exterior material A-1 was used as the film exterior material S2. In the secondary battery according to Comparative Example 2, similarly to Comparative Example 1, heat sealing was performed by arranging tab sealants on both the film exterior material S1 side and the film exterior material S2 side.

  In the secondary battery according to Comparative Example 3, the exterior material A-1 was used as the film exterior material S1, and the exterior material A-4 was used as the film exterior material S2. Further, in the secondary battery according to Comparative Example 3, as in Example 1, although the tab sealant is disposed on the film exterior material S1 side, heat sealing is performed without the tab sealant disposed on the film exterior material S2 side. went.

  In the secondary battery according to Comparative Example 4, the exterior material A-2 was used as the film exterior material S1, and the exterior material A-2 was used as the film exterior material S2. Further, in the secondary battery according to Comparative Example 4, as in Comparative Example 3, although the tab sealant is disposed on the film exterior material S1 side, heat sealing is performed without the tab sealant disposed on the film exterior material S2 side. went.

  In the secondary battery according to Comparative Example 5, the exterior material A-1 was used as the film exterior material S1, and the exterior material A-2 was used as the film exterior material S2. Further, in the secondary battery according to Comparative Example 5, unlike Example 1 and the like, heat sealing was performed without arranging the tab sealant on either the film exterior material S1 side or the film exterior material S2 side.

Table 1 below summarizes the film configurations of the secondary batteries of Examples 1 and 2 and Comparative Examples 1 to 5 and the presence or absence of the arrangement of the tab sealant.

  Subsequently, the secondary battery according to Examples 1 and 2 and Comparative Examples 1 to 5 obtained in this way were evaluated for insulation and moisture permeation. Specific evaluation methods and evaluation criteria were as follows.

[Insulation evaluation method]
The ends of the opposite sides of the obtained secondary battery were connected to a tester (manufactured by Kikusui Electronics Co., Ltd., “electrode for pressure tester (SPEC 80216)”), and the electrical resistance value was measured. At that time, a voltage of 25 V was applied for 5 seconds to measure the resistance, and the insulation was evaluated according to the following criteria.
“◎”: 99.9 GΩ or more.
“X”: Less than 99.9 GΩ.

[Evaluation method of moisture permeation]
The obtained secondary battery was stored in an environment of 60 ° C. and 95% RH for 4 weeks, and the water content contained in the electrolyte after storage was measured by Karl Fischer moisture meter (Hiranuma Sangyo Co., Ltd. (AQ-2100) ”), and this measured value was used as an evaluation of the amount of moisture permeation into the battery of the secondary battery. Evaluation criteria were performed according to the following.
“◎”: Water permeation amount is 10 ⁻² g / day · m ² or less.
“◯”: Water permeation amount is 10 ⁻¹ g / day · m ² or less.
“X”: The moisture permeation amount is larger than 10 ⁻¹ g / day · m ² .

[Evaluation results]
Table 2 below shows the evaluation results of the insulation and the moisture permeation amount in the secondary batteries according to Examples 1 and 2 and the secondary batteries according to Comparative Examples 1 to 5.

  As shown in Table 2 above, the film exterior material S1 is an aluminum laminate film, the film exterior material S2 is a non-conductive laminate film, and the tab sealant is not provided on the film exterior material S2 side. Despite the thin film thickness of the metal terminal part containing the sealant, it showed excellent insulation and excellent moisture barrier properties. Further, as shown in Table 2, in the secondary battery according to Example 2 in which the barrier layer of the non-conductive laminate film used for the film exterior material S2 was changed to polyvinylidene chloride, the moisture barrier was compared with Example 1. Although the performance was slightly reduced, it still showed good moisture barrier properties and excellent insulating properties.

  On the other hand, the film exterior material S1 is an aluminum laminate film, and the film exterior material S2 is a non-conductive laminate film, but the tab sealant is provided on both the lead surfaces on the film exterior material S1 side and the film exterior material S2 side. In the secondary battery according to the present invention, although excellent insulation was exhibited, moisture permeation from the end portion was increased and moisture barrier properties were decreased. Further, in Comparative Example 2 in which the film exterior material S1 and the film exterior material S2 are both made of an aluminum laminate film and the tab sealant is provided on both the lead surfaces on the film exterior material S1 side and the film exterior material S2 side, as in Comparative Example 1. Although it showed excellent insulating properties, moisture passed through the tub sealant, resulting in reduced moisture barrier properties.

  Further, the film exterior material S1 is an aluminum laminate film, and the film exterior material S2 is a non-conductive laminate film. However, the film exterior material S2 is a non-acid-modified polypropylene film, and the film exterior material S2 In Comparative Example 3 in which no tab sealant is provided on the side, the adhesive force between the lead and the heat-sealing resin layer of the film exterior material S2 becomes insufficient, so that moisture permeation from the end portion increases, which is compared with Example 1. As a result, the moisture barrier property decreased.

  Further, in the secondary battery according to Comparative Example 4 in which the film exterior material S1 and the film exterior material S2 are both non-conductive laminate films, although excellent insulation was exhibited, the barrier layer of the film exterior material S1 was formed by molding. Cracking occurred and the moisture barrier property was lowered. In the secondary battery according to Comparative Example 5 in which the film sheathing material S1 is an aluminum laminate film and the film sheathing material S2 is a non-conductive laminate film, but no tab sealant is provided on either side of the lead, Since the adhesive force of the heat sealing resin layer of the film exterior material S1 became insufficient, the moisture permeation from the end portion increased, and the moisture barrier property was lowered as compared with Example 1. Further, the insulation between the aluminum foil of the film exterior material S1 and the leads was lowered.

  From the above, the film exterior material S1 is an aluminum laminate film, the film exterior material S2 is a non-conductive laminate film, and no tab sealant is provided on the film exterior material S2 side, thereby ensuring excellent insulation. It was found that a secondary battery having a moisture barrier property can be obtained.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery, 20 ... Metal foil laminated film, 24 ... Metal foil layer, 27 ... Heat-fusion resin layer, 30 ... Non-conductive laminate film, 32 ... Non-conductive barrier layer, 34 ... Heat-fusion resin layer 40 ... Battery element, 42 ... Lead, 44 ... Tab sealant.

Claims (6)

A metal foil laminate film formed by laminating at least a metal foil barrier layer containing a metal foil and a first sealant layer;
A non-conductive laminate film formed by laminating at least a non-conductive barrier layer and a second sealant layer fused and bonded to at least a part of the first sealant layer;
A battery element configured to contain an electrolyte and accommodated between the metal foil laminate film and the non-conductive laminate film;
A positive electrode lead and a negative electrode lead extending from the battery element toward the outside of the battery;
A tab sealant provided between the positive electrode lead and the negative electrode lead and the metal foil laminate film;
A secondary battery comprising:   The secondary battery according to claim 1, wherein the tab sealant is provided only between the positive and negative electrode leads and the metal foil laminate film.   The secondary battery according to claim 2, wherein the second sealant layer of the non-conductive laminate film is directly bonded to the positive electrode lead and the negative electrode lead.   The secondary battery according to any one of claims 1 to 3, wherein the second sealant layer of the non-conductive laminate film is an acid-modified polyolefin resin layer.   The secondary battery according to claim 1, wherein the non-conductive barrier layer is a barrier layer containing an inorganic oxide. The secondary battery according to claim 1, wherein at least a part of the metal foil laminate film has a concave shape.