JP2012203982A - Exterior material for lithium ion battery and lithium ion battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exterior material for a lithium ion battery which can suppress an occurrence of damage on a heat seal part even when the pressure in a battery increases persistently, and to provide a lithium ion battery equipped with the exterior material for a lithium ion battery.SOLUTION: An exterior material 1 for a lithium ion battery has a heat seal part 1a formed by laminating a base material layer 11, a molding enhancement layer 12, a metal foil layer 13, a corrosion protection processing layer 14, an adhesive resin layer 15, and a sealant layer 16 sequentially and then heat sealing and fusing the sealant layers 16. At least one of the adhesive resin layer 15 and the sealant layer 16 has a laminar cleavage induction part where the stress at the time of cleavage is smaller than that on the fusion surface of the sealant layers 16. A lithium ion battery equipped with the exterior material 1 for a lithium ion battery is also provided.

Description

  The present invention relates to a packaging material for a lithium ion battery and a lithium ion battery.

  As secondary batteries, lithium ion batteries, which have a high energy density and can be reduced in weight, are often used as mobile devices such as mobile phones and notebook computers are downsized. As a packaging material for lithium ion batteries (hereinafter, sometimes simply referred to as “packaging material”), in particular, for secondary battery applications for large-sized devices, unlike a can type that has been conventionally used, Laminate-type exterior materials (for example, a structure such as a base material layer / adhesive layer / aluminum foil layer / adhesive resin layer / sealant layer) that are superior in terms of thinning, weight reduction, and heat dissipation are attracting attention ( For example, Patent Document 1).

  As a lithium ion battery using a laminate-type exterior material, (1) a bag is formed so that one side is open, and the battery contents such as a positive electrode, a negative electrode, a separator, and an electrolytic solution are housed therein and sealed. Forms such as three-side seal type, four-side seal type, pillow pouch type, etc. (2) Embossed type forms that form a recess by cold molding the exterior material and seal the battery contents after storing the battery contents in the recess . In any of the forms (1) and (2), sealing is performed by joining the sealant layers of the exterior material together and fusing the edge portions by heat sealing.

On the other hand, in a lithium ion battery, LiPF ₆ or LiBF _{4 as} an electrolyte reacts with moisture that has entered the battery to generate hydrofluoric acid, or charging due to overvoltage or discharging with an excessive current causes the pressure in the battery to decrease. May rise continuously. Sealing by sealing the sealant layer is excellent in instantaneous pressure resistance, but the continuous pressure resistance is inferior to a can-type exterior material. Therefore, in a lithium ion battery using a laminate-type exterior material, in some cases, a portion where the exterior material is fused (hereinafter referred to as “heat seal portion”) due to a continuous increase in pressure in the battery is easy. Or the exterior material may be broken before the heat seal part. The electrolyte that is the battery contents is flammable, and particularly a fully charged battery stores a large amount of electrical energy. Therefore, in order to prevent ignition, it is important to prevent the heat seal portion of the exterior material from being easily cleaved or to prevent the exterior material from being broken before the heat seal portion.

JP 2001-202927 A

  The present invention is for a lithium ion battery in which even when the pressure in the battery continuously rises, the heat seal part can be easily cleaved or the exterior material can be prevented from breaking in front of the heat seal part. An object is to provide an exterior material and a lithium ion battery including the exterior material for a lithium ion battery.

The present invention employs the following configuration in order to solve the above problems.
[1] A heat seal portion in which at least a metal foil layer, a corrosion prevention treatment layer, an adhesive resin layer, and a sealant layer are sequentially laminated on one surface side of the base material layer, and the sealant layers are heat-sealed and fused. A lithium ion battery exterior material having
An exterior material for a lithium ion battery, wherein at least one of the adhesive resin layer and the sealant layer has a layered cleavage inducing portion described below.
(Cleavage induction part)
A portion where the stress at the time of cleavage is smaller than the stress at the time of cleavage of the fused surface between the sealant layers in the heat seal portion.
[2] The external packaging material for a lithium ion battery according to [1], wherein the adhesive resin layer includes a plurality of layers, and an outermost layer on the sealant layer side of the adhesive resin layer is the cleavage induction portion.
[3] The outer packaging material for a lithium ion battery according to [1], wherein the sealant layer includes a plurality of layers, and any one of the layers in the sealant layer is the cleavage induction portion.
[4] The exterior packaging material for a lithium ion battery according to [1], wherein the adhesive resin layer is a single layer, and the adhesive resin layer itself is the cleavage induction portion.
[5] The lithium ion battery exterior material according to [1], wherein the sealant layer is a single layer, and the sealant layer itself is the cleavage induction portion.
[6] The exterior packaging material for a lithium ion battery according to any one of [1] to [5], wherein a corrosion prevention treatment layer is also formed on the surface of the metal foil layer on the base material layer side.
[7] The exterior packaging material for a lithium ion battery according to any one of [1] to [6], wherein the corrosion prevention treatment layer is a layer formed of a corrosion prevention treatment agent containing trivalent chromium.
[8] The exterior packaging material for a lithium ion battery according to any one of [1] to [7], wherein the adhesive resin layer contains at least one of an acid-modified elastomer resin and an acid-modified polyolefin resin.
[9] The exterior packaging material for a lithium ion battery according to any one of [1] to [8], wherein both the adhesive resin layer and the sealant layer contain a thermoplastic resin.
[10] The external packaging material for a lithium ion battery according to any one of [1] to [9], wherein a molding improvement layer is formed between the base material layer and the metal foil layer.
[11] A lithium ion battery comprising the outer packaging material for a lithium ion battery according to any one of [1] to [10].

Even if the pressure in the battery is continuously increased, the lithium ion battery exterior material of the present invention suppresses the heat seal portion from being cracked at low stress or the exterior material from being broken before the heat seal portion. it can.
In addition, since the lithium ion battery of the present invention includes the outer packaging material for the lithium ion battery of the present invention, even when the pressure in the battery is continuously increased, the heat seal portion is cracked at low stress. Or, it is difficult for the exterior material to break before the heat seal portion.

It is sectional drawing which showed an example of the exterior material for lithium ion batteries of this invention. It is sectional drawing which showed an example of the peeling form of the exterior material for lithium ion batteries of FIG. It is sectional drawing which showed the other example of the exterior material for lithium ion batteries of this invention. It is sectional drawing which showed an example of the conventional exterior material for lithium ion batteries. It is sectional drawing which showed an example of the peeling form of the exterior material for lithium ion batteries of FIG.

Hereinafter, an example of an embodiment of the outer packaging material for a lithium ion battery of the present invention will be shown and described in detail.
[First Embodiment]
As shown in FIG. 1, an exterior material 1 for a lithium ion battery according to the present embodiment (hereinafter referred to as “exterior material 1”) has a molding improvement layer 12 and a metal foil layer 13 on one surface of a base material layer 11. The corrosion prevention treatment layer 14, the adhesive resin layer 15, and the sealant layer 16 are sequentially laminated, and the heat seal portion 1 a is formed by heat-sealing and sealing the sealant layers 16 to each other. The heat seal portion 1a is a portion formed by heat sealing performed to seal the battery when a lithium ion battery of a three-side seal type, a four-side seal type, a pillow pouch type, an emboss type, or the like is used.

(Base material layer 11)
The base material layer 11 provides heat resistance in a sealing process when manufacturing a lithium ion battery, and plays a role of suppressing generation of pinholes that may occur during processing and distribution.
As the base material layer 11, a resin layer having insulating properties is preferable. Specific examples include stretched or unstretched films such as polyester resins, polyamide resins, and polyolefin resins. Of these, a stretched polyamide film and a stretched polyester film are preferred from the viewpoint of improving moldability, heat resistance, pinhole resistance, and insulation.

The base material layer 11 may be a single layer film or a laminated film in which two or more layers are laminated. When the base material layer 11 is a single layer film, either a biaxially stretched polyester film or a biaxially stretched polyamide film is preferable. When the base material layer 11 is a laminated film, a laminated film of a biaxially stretched polyester film and a biaxially stretched polyamide film is preferable, and a laminated film in which a biaxially stretched polyester film and a biaxially stretched polyamide film are laminated in order from the outside is more preferable. preferable.
6-40 micrometers is preferable and, as for the thickness of the base material layer 11, 10-25 micrometers is more preferable.

Additives such as a flame retardant, slip agent, anti-blocking agent, antioxidant, light stabilizer, and tackifier may be dispersed or coated on the surface of the base material layer 11.
Examples of the slip agent include fatty acid amides (oleic acid amide, erucic acid amide, stearic acid amide, behenic acid amide, ethylene bisoleic acid amide, ethylene biserucic acid amide, etc.) and the like.
As the anti-blocking agent, various filler-based anti-blocking agents such as silica are preferable.
An additive may be used individually by 1 type and may use 2 or more types together.

(Molding improvement layer 12)
The molding improvement layer 12 plays a role of improving the adhesion between the base material layer 11 and the metal foil layer 13 and improving the moldability of the exterior material 1. By providing the molding improvement layer 12, it becomes easy to suppress the occurrence of cracks and pinholes in the metal foil layer 13 that may occur during molding. Examples of the molding improving layer 12 include a layer containing at least one of the following resin (A) and coupling agent (B).
Resin (A): Polyolefin resin, polyether resin, polyester resin, polyurethane resin, polyvinyl resin, polystyrene resin, polyacrylic resin, polyamide resin, phenolic resin, melamine resin, epoxy resin One or more heat-sealable resins selected from the group consisting of unsaturated polyester resins, silicone resins, polysulfone resins, polycarbonate resins, polyallyl resins, and ionomer resins.
Coupling agent (B): One or more coupling agents selected from the group consisting of silane coupling agents, titanate coupling agents, aluminate coupling agents, and zirconate coupling agents.
The molding improvement layer 12 may be a layer containing either the resin (A) or the coupling agent (B), or a layer containing both the resin (A) and the coupling agent (B). Also good.

Examples of the polyolefin resin used for the molding improvement layer 12 include polyethylene, polypropylene, polybutene, α-polyolefin, and polymethylpentene.
Examples of polyether resins include polyether ketone and polyether ether ketone.
Examples of the polyester resin include polyethylene terephthalate, polyethylene naphthalate, polytrimethylene terephthalate, polybutylene terephthalate, and polybutylene naphthalate.
Examples of the polyurethane resin include poly-n-butyl isocyanate, poly-n-hexyl isocyanate, and 2-6-polyurethane.
Examples of the polyvinyl resin include ethylene / vinyl acetate copolymer, polyvinyl chloride, styrene vinyl, and vinyl acetate.
Examples of polystyrene resins include styrene / acrylonitrile copolymers, acrylonitrile / butadiene / styrene resins, and impact-resistant polystyrene.
Examples of the polyacrylic resin include polymethyl methacrylate, ethylene / methyl methacrylate copolymer, and polycarboxylic acid.
Examples of the phenolic resin include random novolak type, high ortho novolak type, alkali resol type, ammonia resol type, benzyl ether resol type resin and the like.
Examples of the polyamide resin include nylon 6, nylon 11, nylon 12, nylon 66, nylon 610, nylon 612, and the like.
Examples of melamine resins include guanamine and aniline.
Examples of the epoxy resin include resins of glycidyl ester type, glycidyl amine type, and cycloaliphatic type.
Examples of the unsaturated polyester resin include orthophthalic acid, isophthalic acid, terephthalic acid, dicyclo, fatty saturated acid, and bisphenol resins.
Examples of the silicone resin include polydimethylsiloxane, polydiethylsiloxane, and polymethylphenylsiloxane.
Examples of the polysulfone-based resin include polyether sulfone, polysulfone, polyallyl sulfone, and allyl polyphenyl sulfone.
Polycarbonate resins include polytetramethylene carbonate, polypentamethylene carbonate, polyhexamethylene carbonate, and the like.
Examples of polyallyl resins include polyallylamine, polyallylamide, polyallyl ether, polyallyl ether ketone, and the like.
Examples of the ionomer resin include those obtained by polymerizing an ethylene-based, styrene-based or elastomer-based resin or an ethylene carboxylic acid copolymer with an ion source such as Na, K, Li, or Zn.

Examples of the silane coupling agent used for the molding improvement layer 12 include trimethoxysilane, tetramethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, and glycidoxypropyltrimethoxysilane.
Examples of titanate coupling agents include trimethoxy titanate, tetramethoxy titanate, tetrapropoxy titanate, chlorotrimethoxy titanate, methyl triethoxy titanate, diethyl diethoxy titanate, and phenyl trimethoxy titanate.
Examples of the aluminate coupling agent include trimethoxy aluminate, triethoxy aluminate, tripropoxy aluminate, and tetraethoxy aluminate.
Examples of the zirconate coupling agent include trimethoxy zirconate, tetramethoxy zirconate, tetrapropoxy zirconate, chlorotriethoxy zirconate, ethyl trimethoxy zirconate, and phenyl trimethoxy zirconate.

The exterior material 1 is provided with the molding improvement layer 12 between the base material layer 11 and the metal foil layer 13, thereby increasing the adhesion strength between the base material layer 11 and the metal foil layer 13. Even when a tensile and compressive stress is applied to the exterior material 1 at this time, it becomes easy to ensure sufficient adhesion between the base material layer 11 and the metal foil layer 13. Thereby, the moldability of the exterior material 1 improves. That is, since it becomes easy to suppress peeling of the base material layer 11 and the metal foil layer 13, it is easy to suppress that the metal foil layer 13 fractures | ruptures from that part or a pinhole arises.
The molding improvement layer 12 also functions as a buffer layer between the base material layer 11 and the metal foil layer 13. That is, the molding improving layer 12 can relieve stress applied during molding and suppress the metal foil layer 13 from being broken during molding, so that moldability is improved. In particular, when the molding improvement layer 12 is formed of the resin (A), the effect as a buffer layer at the time of molding is more satisfactorily exhibited.

The molding improvement layer 12 in this example also serves as an adhesive layer. As a form which makes the shaping | molding improvement layer 12 serve as an adhesive bond layer, for example, among resin (A), the form using heat-adhesive resin, such as polyolefin resin and polyester resin, and an adhesive agent are included. A form is mentioned.
As the adhesive contained in the molding improving layer 12, a two-component curable polyurethane in which a bifunctional or higher functional aromatic or aliphatic isocyanate is allowed to act as a curing agent on a main component such as polyester polyol, polyether polyol, acrylic polyol, or the like. System adhesives are preferred.
1-10 are preferable and, as for the molar ratio (NCO / OH) of the isocyanate group which the hardening | curing agent has with respect to the hydroxyl group which a main ingredient has, 2-5 are more preferable.

In the case of the coupling agent (B) and a relatively hard resin (polyvinyl resin, polystyrene resin, epoxy resin, etc.), the thickness of the molding improvement layer 12 is preferably 20 nm to 500 nm, more preferably 20 to 100 nm. . If the thickness of the molding improvement layer 12 is 20 nm or more, it is easy to suppress the occurrence of film peeling and unevenness, and a sufficient adhesion strength can be easily obtained. If the thickness of the molding improvement layer 12 is 500 nm or less, it is easy to suppress the molding improvement layer 12 from becoming too hard, and excellent moldability is easily obtained.
Moreover, when using the component (polyurethane-type resin, silicone resin, etc.) rich in elasticity for the shaping | molding improvement layer 12, and providing the function to relieve stress, the thickness of the shaping | molding improvement layer 12 has preferable 500 nm-50 micrometers. . If the thickness of the molding improvement layer 12 is 20 nm or more, sufficient adhesion strength can be easily obtained. Even if the thickness of the molding improvement layer 12 exceeds 50 μm, the effect of relaxing the stress does not change so much, which is disadvantageous in terms of cost.
The molding improvement layer 12 may be a single layer or two or more layers.

(Metal foil layer 13)
As the metal foil layer 13, various metal foils such as aluminum and stainless steel can be used, and aluminum foil is preferable from the viewpoint of workability such as moisture resistance and spreadability and cost.
As the aluminum foil, for example, a known soft aluminum foil can be used, and an aluminum foil containing iron is preferable from the viewpoint of pinhole resistance and spreadability at the time of molding. 0.1-9.0 mass% is preferable and, as for content of iron in aluminum foil (100 mass%), 0.5-2.0 mass% is more preferable. If the iron content is at least the lower limit, pinhole resistance and spreadability are improved. If the iron content is less than or equal to the upper limit, flexibility is improved.

  The thickness of the metal foil layer 13 is preferably 9 to 200 μm, more preferably 15 to 200 μm, from the viewpoint of barrier properties, pinhole resistance, and workability.

An untreated aluminum foil may be used for the metal foil layer 13, but an aluminum foil subjected to a degreasing treatment is preferable. The degreasing treatment is roughly classified into a wet type and a dry type.
Examples of the wet type degreasing treatment include acid degreasing and alkali degreasing. Examples of the acid used for acid degreasing include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, and hydrofluoric acid. These acids may be used individually by 1 type, and may use 2 or more types together. Moreover, you may mix | blend various metal salts used as supply sources, such as an iron ion, as needed from the point which the etching effect of aluminum foil improves. As an alkali used for alkali degreasing, sodium hydroxide etc. are mentioned as a thing with a high etching effect, for example. Moreover, what mix | blended weak alkali type and surfactant is mentioned. The wet type degreasing treatment is performed by an immersion method or a spray method.
Examples of the dry type degreasing treatment include a method of performing a degreasing treatment by increasing the treatment time in the step of annealing the aluminum foil. In addition to the degreasing treatment, frame treatment, corona treatment and the like can be mentioned. Furthermore, a degreasing process in which contaminants are oxidatively decomposed and removed by active oxygen generated by irradiation with ultraviolet rays having a specific wavelength may be employed.

(Corrosion prevention treatment layer 14)
The corrosion prevention treatment layer 14 serves to prevent the metal foil layer 13 from being corroded by hydrofluoric acid generated by the reaction between the electrolytic solution and moisture, and to improve the wettability and improve the adhesion to the adhesive resin layer 15. Fulfill.
The corrosion prevention treatment layer 14 can be formed by, for example, chromium-based chemical conversion treatment such as phosphoric acid chromate treatment or coating-type chromate treatment, or non-chromate chemical conversion treatment such as zirconium or titanium. Among these, a layer formed by coating-type chromate treatment is preferable from the viewpoint of waste liquid treatment, and being particularly excellent in the effect. Also, the chromate treatment with a corrosion inhibitor containing trivalent chromium is preferable in that the environmental load is small compared to the case of using hexavalent chromium which is an environmentally destructive substance.
The corrosion prevention treatment layer 14 is not limited to the coating film formed by the above treatment as long as the corrosion resistance of the metal foil layer 13 is sufficiently obtained. For example, you may form by a phosphate process, a boehmite process, etc.

The corrosion prevention treatment layer 14 may be a single layer or a plurality of layers.
The thickness of the corrosion prevention treatment layer 14 is preferably 10 nm to 5 μm, more preferably 20 nm to 500 nm, from the viewpoint of the corrosion prevention function and the function as an anchor.

(Adhesive resin layer 15)
The adhesive resin layer 15 is a layer that bonds the sealant layer 16 and the metal foil layer 13 on which the corrosion prevention treatment layer 14 is formed.
The resin constituting the adhesive resin layer 15 is preferably a thermoplastic resin. Specifically, for example, polyolefin resins, elastomer resins, acid-modified polyolefin resins obtained by graft-modifying acids such as maleic anhydride to polyolefin resins, and acids such as maleic anhydride are graft-modified to elastomer resins. Examples include acid-modified elastomer resins. Especially, at least one of an acid-modified elastomer resin and an acid-modified polyolefin resin is preferable, and an acid-modified polyolefin resin is more preferable because of excellent adhesiveness to the metal foil layer 13.

Examples of the polyolefin resin include low density, medium density, and high density polyethylene; ethylene-α olefin copolymer, homo, block or random polypropylene, propylene-α olefin copolymer, and the like. These polyolefin resin may be used individually by 1 type, and may use 2 or more types together. The polyolefin-based resin and the acid-modified polyolefin-based resin are more excellent in resistance to contents such as an electrolytic solution, and easily suppress a decrease in adhesion due to deterioration of the adhesive resin even when hydrofluoric acid is generated.
Examples of the elastomer resin include styrene-based or olefin-based thermoplastic elastomers.

The adhesive resin layer 15 may be a single layer or a plurality of layers.
1-40 micrometers is preferable and, as for the thickness of the adhesive resin layer 15, 5-20 micrometers is more preferable. If the thickness of the adhesive resin layer 15 is 1 μm or more, sufficient adhesive strength is easily obtained. If the thickness of the adhesive resin layer 15 is 40 μm or less, it is easy to reduce the amount of moisture that permeates into the battery from the seal end face.

(Sealant layer 16)
The sealant layer 16 is an inner layer of the exterior material 1 and is a layer that is heat-sealed at the time of battery assembly. That is, the sealant layer 16 is a layer formed of a heat-fusible film. By sealing the sealant layers 16 of the exterior material 1 facing each other and heat-sealing at a temperature equal to or higher than the melting temperature of the sealant layer 16, the lithium ion battery can be sealed.
The resin constituting the sealant layer 16 is preferably a thermoplastic resin, and more preferably a polyolefin resin such as polyethylene or polypropylene, from the viewpoint that a lithium ion battery excellent in impact resistance and heat sealability can be easily obtained.
Polypropylene includes homo, block or random polypropylene.

The sealant layer 16 may be a layer made of a single layer film or a layer made of a multilayer film. For example, for the purpose of imparting moisture resistance, a multilayer film in which a resin such as an ethylene-cyclic olefin copolymer or polymethylpentene is interposed may be used.
The thickness of the sealant layer 16 is preferably 25 to 100 μm. When the thickness of the sealant layer 16 is 25 μm or more, excellent heat sealability is easily obtained. If the thickness of the sealant layer 16 is 100 μm or less, it is easy to reduce the amount of moisture that permeates from the seal end surface into the battery.
The sealant layer 16 may be blended or coated with a flame retardant, slip agent, antioxidant, light stabilizer, tackifier and the like. These may be used alone or in combination of two or more.

  In the exterior material 1, it is preferable that both the adhesive resin layer 15 and the sealant layer 16 contain a thermoplastic resin. Thereby, the impact resistance and heat sealability of the exterior material 1 are improved.

(Cleavage induction part)
The present inventor has examined in detail the occurrence of the low-stress cleavage in the heat-sealed portion of the laminate-type exterior material or the occurrence of the fracture of the exterior material before the heat-sealed portion.
As the peeling form in the laminated film such as the exterior material of the present invention, when the layer having adhesiveness and the layer having adhesiveness are laminated with each other, interfacial peeling in which the cleavage proceeds at the interface between the other layer and those other layers is laminated. There are three types, delamination in which cleavage proceeds between the layers, and agglomerated delamination in which cleavage proceeds inside the adhesive layer. About these peeling forms, there is the following relationship when compared with the stress at the time of cleavage and the contaminant sealing property.
Interfacial delamination <delamination <cohesive delamination.
Interfacial debonding generally has a small stress at the time of cleavage, and the cleavage is likely to proceed. In addition, since cohesive delamination proceeds in the same kind of component having high compatibility, the stress at the time of the cleavage may be larger than delamination where delamination proceeds between layers of different components.

In the heat seal part of a laminate-type exterior material in a lithium-ion battery, when an occurrence of peeling occurs on the fusion surface of the sealant layer, the cleavage shifts to the interface between the adhesive resin layer and the corrosion prevention treatment layer, and from there the interface peeling In this form, the cleavage proceeds to lower the cleavage stress. FIG. 4 shows a conventional lithium ion battery exterior material 101 (hereinafter referred to as “exterior material 101”), which will be specifically described.
The exterior material 101 is a multilayer film in which a molding improvement layer 112, a metal foil layer 113, a corrosion prevention treatment layer 114, an adhesive resin layer 115, and a sealant layer 116 are sequentially laminated on one surface of the base material layer 111. It has a heat seal part 101a in which the sealant layers 16 are heat sealed and fused together. The exterior material 101 can accommodate the battery contents therein by forming a heat seal portion 101a. In such a conventional exterior material 101, the internal pressure rises due to the generation of hydrofluoric acid or the like, and an occurrence of peeling occurs at the inner edge portion 116b of the fusion surface 116a between the sealant layers 116 in the heat seal portion 101. Even in such a case, the stress at the time of tearing in or between the adhesive resin layer 115 and the sealant layer 116 is made equal to the stress at the time of tearing of the fusion surface 116a of the sealant layers 116 so that the tearing does not proceed easily. It is set high. However, in the conventional exterior material 101, as shown in FIG. 5, in the vicinity of the inside of the heat seal portion 101 a, the cleavage moves to the interface between the adhesive resin layer 115 and the corrosion prevention treatment layer 114, and the separation of the interface peeling occurs therefrom. It was found that the cracking progressed in the form, resulting in the cracking with low stress and the required strength could not be obtained.

  The packaging material 1 of the present invention is characterized in that at least one of the adhesive resin layer 15 and the sealant layer 16 has a layered cleavage induction portion. The cleavage induction portion is a portion where the stress at the time of cleavage is smaller than the stress at the time of cleavage of the fusion surface 16a between the sealant layers 16 in the heat seal portion 1a. In the packaging material 1 in which at least one of the adhesive resin layer 15 and the sealant layer 16 has a cleavage inducing portion, the progress of the cleavage occurs when the peeling portion occurs at the inner edge portion 16b of the fusion surface 16a between the sealant layers 16. Is induced in the cleavage induction part. For example, in the case where the sealant layer 16 is used as a cleavage induction portion, as shown in FIG. 2, when peeling occurs at the edge portion 16 b on the inner side of the fusion surface 16 a between the sealant layers 16, the progress of the cleavage is broken. It is guided to the sealant layer 16 serving as a guide portion. As a result, it is possible to prevent the crack from being transferred to the interface between the adhesive resin layer 15 and the corrosion prevention treatment layer 14 in the vicinity of the inside of the heat seal portion 1a, and to prevent the peeling form from becoming the interface peeling. In addition, it becomes difficult for the exterior material 1 to be cracked and broken at low stress.

At least one of the adhesive resin layer 15 and the sealant layer 16 has the cleavage induction portion. Examples of the form of the cleavage induction part include the following forms (a) to (c).
(A) A form in which only the adhesive resin layer 15 has a cleavage induction portion.
(B) A form in which only the sealant layer 16 has a cleavage inducing portion.
(C) A form in which both the adhesive resin layer 15 and the sealant layer 16 have a cleavage induction portion.

Examples of the form (a) include the following forms (a1) and (a2).
(A1) The adhesive resin layer 15 is a single layer, and the adhesive resin layer 15 itself is a cleavage induction portion.
(A2) The adhesive resin layer 15 includes a plurality of layers, and any one of the adhesive resin layers 15 is a cleavage induction portion.

Form (a1):
As the form (a1), for example, the single-layer adhesive resin layer 15 is bonded with one or more selected from various additives such as an incompatible thermoplastic resin, an antiblocking agent, and a filler. The form (a11) which uses resin layer 15 itself as a cleavage induction part is mentioned. By blending the components, the fusion area of the same kind of resin portion in the adhesive resin layer 15 is reduced, and the stress at the time of cleavage in the adhesive resin layer 15 can be reduced. In the form (a11), the cleavage is induced between the adhesive resin layer 15 and the sealant layer 16 or inside the adhesive resin layer 15, and the peeling form is induced by delamination or cohesive peeling.
In the form (a1), the thicker the cleavage inducing portion, the more easily the stringing is promoted when the cleavage proceeds, so that the exterior material 1 is more difficult to peel off.

  The incompatible thermoplastic resin means a resin dispersed in a base resin with a dispersion diameter of 1 to 100 μm. The dispersion diameter is measured by the following method. A sample piece of a predetermined size is cut out from the exterior material, and the sample piece embedded in resin is cut in a cross section with an ultramicrotome. After that, dyeing with ruthenium tetroxide at 70 ° C. for 2 to 4 hours, cutting the section again with an ultramicrotome, and performing platinum deposition (conduction treatment) on the dyed section, scanning electron microscope (SEM) or transmission type The maximum diameter observed and measured with an electron microscope (TEM) is taken as the dispersion diameter.

  Specific examples of the incompatible thermoplastic resin include, for example, polystyrene, natural rubber, and thermoplastic elastomer when the base resin is a polyolefin resin. Among these, a thermoplastic elastomer is preferable and a styrene-based elastomer is more preferable from the viewpoint of high heat seal strength. The styrene elastomer is preferably at least one of a styrene / ethylene / butylene / styrene copolymer and a styrene / ethylene / propylene / styrene copolymer.

  Examples of the anti-blocking agent include fine silica, zeolite, talc and the like. Of these, fine silica is preferred from the standpoint of high heat seal strength.

When the incompatible thermoplastic resin is blended with the adhesive resin layer 15 in the form (a11), the blending amount in the adhesive resin layer 15 (100% by mass) is 5 to 40% by mass, and 10 to 25% by mass. Is preferred. When the blending amount exceeds 40% by mass, the progress of the cleavage is caused to occur at the cleavage inducing portion when a trigger for peeling occurs at the inner edge portion 16b of the fusion surface 16a between the sealant layers 16 in the heat seal portion 1a. It is easy to induce, but the heat seal strength decreases. When the blending amount is less than 5% by mass, cleavage is not stable and induction is insufficient.
When the said additive is mix | blended with the adhesive resin layer 15 in a form (a11), the compounding quantity in the adhesive resin layer 15 (100 mass%) is 5-50 mass%, and 10-30 mass% is preferable. If the blending amount exceeds 50% by mass, the progress of the cleavage is caused to occur in the cleavage-inducing portion when a trigger for peeling occurs at the inner edge portion 16b of the fusion surface 16a of the sealant layers 16 in the heat seal portion 1a. It is easy to induce, but the heat seal strength decreases. When the blending amount is less than 5% by mass, cleavage is not stable and induction is insufficient.

Form (a2):
In the form (a2), the layer serving as the cleavage induction portion in the plurality of adhesive resin layers 15 may be one layer or two or more layers. In the form (a2), a form in which the outermost layer on the sealant layer 16 side in the plurality of adhesive resin layers 15 is used as a cleavage induction part is preferable.
As the form (a2), for example, by adding various additives such as an incompatible thermoplastic resin, an anti-blocking agent, or a filler to any one of the plurality of adhesive resin layers 15, adhesion is achieved. The form (a21) which made any layer in the resin layer 15 the cleavage induction part is mentioned. By mix | blending the said component, the fusion | melting area of the same kind resin part of either layer in the adhesive resin layer 15 can be made small, and the stress at the time of cleavage can be made small. In the form (a21), cleavage is induced inside the layer serving as the cleavage induction part in the adhesive resin layer 15 or between the layer that is the cleavage induction part in the adhesive resin layer 15 and the layer that is not the cleavage induction part. Becomes delamination or cohesive peeling. Further, when the outermost layer on the sealant layer 16 side in the plurality of adhesive resin layers 15 is used as a cleavage inducing portion, cleavage is induced inside the outermost layer or between the outermost layer and the sealant layer 16, and the peeling form is Induced by delamination or cohesive delamination.

Examples of the incompatible thermoplastic resin include the same ones as mentioned in the above-mentioned form (a11), and preferred forms are also the same.
As an additive, the same thing as the thing quoted by the said form (a11) is mentioned, A preferable form is also the same.

In the case where an incompatible thermoplastic resin is blended in the form (a21), the blending amount with respect to the total mass (100% by mass) of the layer to be blended in the adhesive resin layer 15 is 5 to 40% by mass, and 10 to 25% by mass. % Is preferred. When the blending amount exceeds 40% by mass, the progress of the cleavage is caused to occur at the cleavage inducing portion when a trigger for peeling occurs at the inner edge portion 16b of the fusion surface 16a between the sealant layers 16 in the heat seal portion 1a. It is easy to induce, but the heat seal strength decreases. When the blending amount is less than 5% by mass, cleavage is not stable and induction is insufficient.
When adding an additive in form (a21), the compounding quantity with respect to the total mass (100 mass%) of the layer to mix | blend in the adhesive resin layer 15 is 5-50 mass%, and 10-30 mass% is preferable. If the blending amount exceeds 50% by mass, the progress of the cleavage is caused to occur in the cleavage-inducing portion when a trigger for peeling occurs at the inner edge portion 16b of the fusion surface 16a of the sealant layers 16 in the heat seal portion 1a. It is easy to induce, but the heat seal strength decreases. When the blending amount is less than 5% by mass, cleavage is not stable and induction is insufficient.

Examples of the form (b) include the following forms (b1) and (b2).
(B1) The sealant layer 16 is a single layer, and the sealant layer 16 itself is a cleavage induction portion.
(B2) The sealant layer 16 includes a plurality of layers, and any one of the sealant layers 16 is a cleavage induction portion.

As the form (b1), for example, the sealant layer 16 is blended with a single sealant layer 16 by adding at least one selected from various additives such as an incompatible thermoplastic resin, an antiblocking agent, and a filler. The form (b11) which makes 16 itself the cleavage induction part is mentioned. By blending the above components, the fusion area of the same kind of resin portion in the sealant layer 16 is reduced, and the stress at the time of cleavage in the sealant layer 16 can be reduced. In the form (b11), the cleavage is induced between the adhesive resin layer 15 and the sealant layer 16 or inside the sealant layer 16, and the peeling form is induced by delamination or cohesive peeling.
As for the incompatible thermoplastic resin and additive, the same ones as mentioned in the above-mentioned form (a11) can be mentioned, and preferred forms are also the same.
In the form (b1), as the thickness of the cleavage inducing portion is larger, the stringing is more easily promoted when the cleavage proceeds, so that the exterior material 1 is more difficult to peel off.

When the incompatible thermoplastic resin is blended with the sealant layer 16 in the form (b11), the blending amount in the sealant layer 16 (100% by mass) is 5 to 50% by mass, and preferably 10 to 25% by mass. . If the blending amount exceeds 50% by mass, the progress of the cleavage is caused to occur in the cleavage-inducing portion when a trigger for peeling occurs at the inner edge portion 16b of the fusion surface 16a of the sealant layers 16 in the heat seal portion 1a. It is easy to induce, but the heat seal strength decreases. When the blending amount is less than 5% by mass, cleavage is not stable and induction is insufficient.
When mix | blending the said additive with the sealant layer 16, the compounding quantity in the sealant layer 16 (100 mass%) is 5-50 mass%, and 10-30 mass% is preferable. If the blending amount exceeds 50% by mass, the progress of the cleavage is caused to occur in the cleavage-inducing portion when a trigger for peeling occurs at the inner edge portion 16b of the fusion surface 16a of the sealant layers 16 in the heat seal portion 1a. It is easy to induce, but the heat seal strength decreases. When the blending amount is less than 5% by mass, cleavage is not stable and induction is insufficient.

Form (b2):
In the form (b2), the layer serving as the cleavage induction portion in the plurality of sealant layers 16 may be one layer or two or more layers. In the form (b2), a form in which at least one of the outermost layer on the adhesive resin layer 15 side and the outermost layer on the fusion surface 16a side in the plurality of sealant layers 16 is used as a cleavage induction part is preferable.
As the form (b2), for example, in any one of the plurality of sealant layers 16, various additives such as an incompatible thermoplastic resin, an anti-blocking agent, or a filler are blended, so that the sealant layer The form (b21) which made any layer in 16 the cleavage induction part is mentioned. By mix | blending the said component, the fusion | melting area of the same kind resin part of either layer in the sealant layer 16 can be made small, and the stress at the time of cleavage can be made small. In the form (a21), the cleavage is induced in the sealant layer 16 in the layer serving as the crack induction part or between the layer that is the crack induction part in the sealant layer 16 and the layer that is not the crack induction part. Induced by exfoliation or cohesive exfoliation. Further, when the outermost layer on the adhesive resin layer 15 side in the plurality of sealant layers 16 is used as a cleavage induction part, the cleavage is induced inside the outermost layer or between the outermost layer and the sealant layer 16, and the peeling form is Induced by delamination or cohesive delamination.
About an incompatible type thermoplastic resin and additive, the same thing as the thing quoted by the said form (a21) is mentioned, A preferable form is also the same.

When the incompatible thermoplastic resin is blended in the form (b21), the blending amount with respect to the total mass (100% by mass) of the layer to be blended in the sealant layer 16 is 5 to 50% by mass, and 10 to 25% by mass. Is preferred. If the blending amount exceeds 50% by mass, the progress of the cleavage is caused to occur in the cleavage-inducing portion when a trigger for peeling occurs at the inner edge portion 16b of the fusion surface 16a of the sealant layers 16 in the heat seal portion 1a. It is easy to induce, but the heat seal strength decreases. When the blending amount is less than 5% by mass, cleavage is not stable and induction is insufficient.
When mix | blending an additive in a form (b21), the compounding quantity with respect to the total mass (100 mass%) of the layer to mix | blend in the sealant layer 16 is 5-50 mass%, and 10-30 mass% is preferable. If the blending amount exceeds 50% by mass, the progress of the cleavage is caused to occur in the cleavage-inducing portion when a trigger for peeling occurs at the inner edge portion 16b of the fusion surface 16a of the sealant layers 16 in the heat seal portion 1a. It is easy to induce, but the heat seal strength decreases. When the blending amount is less than 5% by mass, cleavage is not stable and induction is insufficient.

  As the form (c), for example, the form (c1) in which the form (a11) and the form (b11) are combined, the form (c2) in which the form (a11) and the form (b21) are combined, and the form (a21). And the form (c3) combining the form (b11), the form (c4) combining the form (a21) and the form (b21), and the like.

  In the exterior material 1, the adhesive resin layer 15 and the sealant layer 16 can be formed as a single layer or a plurality of layers, and the position where the cleavage induction portion is provided, that is, the separation surface can be controlled. It is preferable that the cleavage induction portion is close to the fusion surface 16 a of the sealant layer 16. That is, it is preferably formed in the sealant layer 16 rather than the adhesive resin layer 15, and when the sealant layer 16 is composed of a plurality of layers, it is preferable that the layer on the fusion surface 16 a side is a cleavage induction portion. Thereby, it becomes easy to suppress that the separation reaches the interface between the adhesive resin layer 15 and the corrosion prevention treatment layer 14 and the interface peeling occurs, and a high peeling strength can be obtained more stably.

The peel strength required for an exterior material in a lithium-ion battery using a laminate-type exterior material includes a peel strength immediately after the start of cleavage (hereinafter referred to as “burst strength”) and a continuous progress of cleavage. There are two types of peel strength (hereinafter referred to as “seal strength”).
The sealing strength of the exterior material 1 is preferably 30 N / 15 mm or more, and more preferably 40 N / 15 mm or more.
The burst strength of the exterior material 1 is preferably 5 N / 15 mm or more higher than the seal strength, and more preferably 10 N / 15 mm or more higher than the seal strength.
The burst strength and seal strength are obtained by cutting out a strip-shaped sample piece measuring 100 mm in length and 15 mm in width from an exterior material in which the sealant layers are overlapped and heat-sealed to form a heat-sealed portion, and the sample piece is in accordance with JIS Z1713. It is a value measured in accordance with a tensile speed of 300 mm / min.

(Production method)
Hereinafter, the manufacturing method of the exterior material 1 is demonstrated. However, the manufacturing method of the exterior material 1 is not limited to the method described below.
As a manufacturing method of the exterior material 1, the method which has the following process (I)-(IV) is mentioned, for example.
(I) A step of forming a corrosion prevention treatment layer 14 on the metal foil layer 13.
(II) A step of bonding the base material layer 11 to the side of the metal foil layer 13 opposite to the side on which the anticorrosion treatment layer 14 is formed via the molding improvement layer 12 that also serves as an adhesive layer.
(III) A step of bonding the sealant layer 16 to the corrosion prevention treatment layer 14 side of the metal foil layer 13 through the adhesive resin layer 15.
(IV) A step of heat-sealing the obtained laminate so that the sealant layers 16 face each other to form the heat-sealed portion 1a.

Step (I):
For example, a corrosion prevention treatment agent composed of a metal compound, a phosphorus compound, a binder resin, and a cross-linking agent is applied to one surface of the metal foil layer 13 and dried and cured to form the corrosion prevention treatment layer 14. .
As a coating method, a known method can be adopted, and examples thereof include a gravure coater, a gravure reverse coater, a roll coater, a reverse roll coater, a die coater, a bar coater, a kiss coater, and a comma coater.
As described above, the metal foil layer 13 may be an untreated metal foil, or may be a metal foil that has been wet-type or dry-type pretreated.

Process (II):
For example, using a mixture containing an adhesive such as a polyurethane-based adhesive and at least one of the resin (A) and the coupling agent (B) forming the molding improving layer 12, dry lamination and non-solvent lamination The base material layer 11 is bonded to the side of the metal foil layer 13 opposite to the side on which the corrosion prevention treatment layer 14 is formed by a technique such as wet lamination. Moreover, when using resin (A) which has heat sealing property, the adhesive resin layer 15 may be formed by methods, such as extrusion, and the base material layer 11 may be bonded together by thermal lamination.

Step (III):
For example, the sealant layer 16 is laminated on the corrosion prevention treatment layer 14 side of the laminate obtained in the step (II) using an adhesive resin that forms the adhesive resin layer 15.
Examples of the lamination method include wet lamination, extrusion lamination, dry lamination, hot melt lamination, non-solvent lamination, heat lamination and the like. Thereafter, for the purpose of improving the adhesion between the corrosion prevention treatment layer 14 and the adhesive resin layer 15, it is preferable to perform heat treatment (aging treatment, thermal lamination, etc.).
Alternatively, a multilayer film may be prepared by co-extrusion of the resin that forms the adhesive resin layer 15 and the sealant layer 16, and the laminated film may be laminated on the corrosion prevention treatment layer 14 of the laminated body by thermal lamination.

Process (IV):
For example, the sealant layers 16 of the obtained laminate are stacked so as to face each other, and the edge portion is heat sealed to form the heat seal portion 1a. Known conditions can be appropriately adopted as the heat sealing conditions.
The form of the exterior material 1 in which the heat seal part is formed is not limited to a specific shape. For example, a three-sided seal, a four-sided seal, a pillow pouch type, and the like, and an embossed type in which a concave portion for storing battery contents is formed by cold forming, etc.

The exterior material 1 is obtained by the steps (I) to (IV) described above.
In addition, the manufacturing method of the exterior material 1 is not limited to the method of implementing the said process (I)-(IV) sequentially. For example, step (I) may be performed after performing step (II). Moreover, you may provide a corrosion prevention process layer on both surfaces of a metal foil layer. Moreover, you may perform process (II) after performing process (III). Further, the formation of the corrosion prevention treatment layer 14 may be performed in-line at the time of extrusion lamination for laminating the sealant layer 16.

  The exterior material of the present invention described above has a cleavage inducing portion to suppress the occurrence of interfacial delamination induced by delamination or cohesive delamination even if the occurrence of delamination occurs on the fusion surface of the heat seal portion. Since it can do, even if it is a case where the pressure in a battery rises continuously, it can suppress that a heat seal part breaks.

The exterior material of the present invention is not limited to the exterior material 1. For example, in the packaging material 1, the corrosion prevention treatment layer 14 is provided on the adhesive resin layer 15 side of the metal foil layer 13, that is, on the side that may come into contact with hydrofluoric acid generated by the reaction between the electrolytic solution and moisture. If necessary, a corrosion prevention treatment layer may also be provided on the base material layer 11 side of the metal foil layer 13. Specifically, it may be a lithium ion battery exterior material 2 (hereinafter referred to as “exterior material 2”) having the laminated structure illustrated in FIG. 3.
In the exterior material 2, a molding improvement layer 12, a corrosion prevention treatment layer 14, a metal foil layer 13, a corrosion prevention treatment layer 14, an adhesive resin layer 15, and a sealant layer 16 are sequentially laminated on one surface of the base material layer 11. It is the exterior material which has the laminated structure.

  Further, an adhesive layer formed with an adhesive for dry lamination may be provided between the base material layer and the metal foil layer instead of the molding improvement layer. Moreover, both the shaping | molding improvement layer and the said adhesive bond layer may be provided between the base material layer and the metal foil layer. In this case, the lamination structure of the adhesive layer and the molding improvement layer may be a lamination order of molding improvement layer / adhesive layer from the base material layer side, or a lamination order of adhesive layer / molding improvement layer. Alternatively, the stacking order of adhesive layer / molding improvement layer / adhesive layer may be used. When the molding improvement layer is provided separately from the adhesive layer, the components of the molding improvement layer are appropriately diluted with a solvent such as water or a solvent, and the molding improvement layer is formed by a known method such as coating, dipping, or spraying. It may be formed.

<Lithium ion battery>
The lithium ion battery of the present invention is a lithium ion battery provided with the exterior material of the present invention.
The lithium ion battery of the present invention can adopt a known form except that the exterior material for a lithium ion battery of the present invention is used.
For example, a three-side seal type in which exterior materials are stacked so that the sealant layers face each other, the edge portions of the exterior materials are heat sealed to form a bag, the battery contents are stored inside, and sealed by heat sealing , A four-side seal type, a pillow pouch type, and an emboss type in which an exterior material is cold-molded to form a recess, and the battery contents are stored in the recess and sealed by heat sealing.

The manufacturing method of the lithium ion battery of this invention can employ | adopt a well-known method except using the exterior material of this invention. For example, if it is an embossed type, the following method is mentioned.
The exterior material of the present invention is cold-molded to form a recess, and a positive electrode, a separator, and a negative electrode are accommodated in the recess, and the tab is led out from the recess. Laminate to face each other and heat seal leaving one side. Thereafter, an electrolytic solution is injected from the opened one side, and the remaining one side is heat-sealed and sealed in a vacuum environment to obtain a lithium ion battery.
Since the lithium ion battery of the present invention includes the outer packaging material of the present invention, even if the pressure in the battery is continuously increased, the heat seal portion is hardly damaged and has excellent long-term reliability. Yes.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by the following description.
<Formation of cleavage-inducing part by incompatible thermoplastic resin>
[Materials used]
The materials used in this example are shown below.
(Base material layer 11)
Base film A-1: Biaxially stretched polyamide film (thickness 25 μm).

(Molding improvement layer 12)
Mixture B-1: A mixture of a silane coupling agent (trade name “KBM-403”, manufactured by Shin-Etsu Silicone) and a polyurethane adhesive (trade name “A525 / A50”, manufactured by Mitsui Chemicals Polyurethanes).

(Metal foil layer 13)
Metal foil C-1: Soft aluminum foil 8079 material (thickness 40 μm).

(Corrosion prevention treatment layer 14)
Treatment agent D-1: Treatment agent for coating chromate treatment comprising a mixed solvent prepared by mixing chromium fluoride (III), phosphoric acid and acrylic resin at a solid content ratio of 40:20:40.

(Adhesive resin layer 15)
Adhesive resin E-1: Maleic anhydride-modified polypropylene resin (trade name “Admer”, manufactured by Mitsui Chemicals, Inc.).
Adhesive resin E-2: Maleic anhydride-modified polypropylene resin (trade name “Admer” manufactured by Mitsui Chemicals) and styrene elastomer (trade name “Tough Tech” manufactured by Asahi Kasei Co., Ltd.) that is an incompatible thermoplastic resin. Adhesive resin dispersed so as to be 15% by mass.
Adhesive resin E-3: An adhesive resin in which an incompatible thermoplastic resin (same as above) is dispersed in maleic anhydride-modified polypropylene resin (same as above) so as to be 2% by mass.
Adhesive resin E-4: An adhesive resin in which an incompatible thermoplastic resin (same as above) is dispersed in maleic anhydride-modified polypropylene resin (same as above) so as to be 50% by mass.

(Sealant layer 16)
Film F-1: Unstretched polypropylene film (thickness 40 μm).
Film F-2: An unstretched polypropylene film (thickness 40 μm) in which an incompatible thermoplastic resin is dispersed in a polypropylene resin so as to be 25% by mass.
Film F-3: An unstretched polypropylene film (thickness 40 μm) in which an incompatible thermoplastic resin is dispersed in polypropylene resin so as to be 2% by mass.
Film F-4: An unstretched polypropylene film (thickness 40 μm) in which an incompatible thermoplastic resin is dispersed in a polypropylene resin so as to be 60% by mass.

[Creating exterior materials]
The coating agent D-1 is applied to one surface of the metal foil C-1 by microgravure, and subjected to a baking treatment at 150 to 250 ° C. in a drying unit, whereby the corrosion prevention treatment is performed on the metal foil layer 13. Layer 14 was laminated. Next, the base film A-1 is bonded to the surface of the metal foil layer 13 opposite to the corrosion prevention treatment layer 14 by dry lamination using the mixture B-1, and the base material is passed through the moldability improving layer 17. Layer 11 was laminated. Next, the adhesive resin layer 15 was laminated by extruding the adhesive resin with an extrusion laminator on the corrosion prevention treatment layer 14 of the obtained laminate. Then, the film | membrane which forms the sealant layer 16 was heat-laminated, and the exterior material of the structure illustrated in FIG. 1 was obtained.

[Evaluation]
Two exterior materials obtained in each example were overlapped so that the sealant layers 16 face each other, and the edge portions of the exterior materials were sandwiched from above and below by a heat seal bar, temperature 190 ° C., pressure 1.0 MPa, time 3 Gap is provided so as to have each remaining film thickness under the condition of seconds, and the post-sealing lamination is performed with respect to the film thickness of the laminated portion A (adhesive resin layer 15 / sealant layer 16 / sealant layer 16 / adhesive resin layer 15) before sealing. Heat sealing was performed so that the rate of change in the thickness of the portion A became the value shown in Table 1. Thereafter, a strip-shaped sample piece having a length of 100 mm and a width of 15 mm was cut out from the heat-sealed exterior material. About this sample piece, according to JISZ1713, the heat seal part was peeled from the one end toward the other end at a tensile speed of 300 mm / min, and the seal strength and burst strength were measured. In the peeling mode, the peeled surface was visually confirmed.
The evaluation criteria are as follows.
As for the seal strength, 40N / 15 mm or more was evaluated as “◯ (good)”, and less than 40 N / 15 mm as “× (defective)”. As for the burst strength, a value larger than the seal strength by 10 N / 15 mm or more was designated as “◯ (good)”, and a value less than that was designated as “x (defective)”. In addition, as for the peeling mode, the case of delamination or cohesive peeling was designated as “◯ (good)”, and the case of interface peeling as “x (defective)”.

[Examples 1 to 6 and Comparative Example 10]
By the above-described production method, the exterior material having the configuration shown in Table 1 with the adhesive resin layer 15 and the sealant layer 16 was produced, and the peeling mode, burst strength, and seal strength were evaluated.

As shown in Table 1, in Examples 1 and 2 in which an adhesive resin layer 15 is blended with an incompatible thermoplastic resin to form a cleavage induction part, the peeling mode can be led to delamination or cohesive peeling, and stable High peel strength was obtained. Further, in Examples 3 to 6 in which a sealant layer 16 is blended with an incompatible thermoplastic resin to form a cleavage induction part, the peeling mode can be led to delamination or cohesive peeling, and a stable high peel strength is obtained. It was.
On the other hand, in Comparative Examples 1 to 10 in which the cleavage induction part of the present invention was not formed in the adhesive resin layer 15 and the sealant layer 16, sufficient peel strength was not obtained.

DESCRIPTION OF SYMBOLS 1 Lithium ion battery exterior material 11 Base material layer 12 Molding improvement layer 13 Metal foil layer 14 Corrosion prevention treatment layer 15 Adhesive resin layer 16 Sealant layer 16a Fusion surface of sealant layers

Claims (11)

Lithium having a heat seal part in which at least a metal foil layer, a corrosion prevention treatment layer, an adhesive resin layer, and a sealant layer are sequentially laminated on one surface side of the base material layer, and the sealant layers are heat sealed and fused together. An ion battery exterior material,
An exterior material for a lithium ion battery, wherein at least one of the adhesive resin layer and the sealant layer has a layered cleavage inducing portion described below.
(Cleavage induction part)
A portion where the stress at the time of cleavage is smaller than the stress at the time of cleavage of the fused surface between the sealant layers in the heat seal portion.   The exterior material for a lithium ion battery according to claim 1, wherein the adhesive resin layer includes a plurality of layers, and the outermost layer on the sealant layer side of the adhesive resin layer is the cleavage induction portion.   The exterior material for a lithium ion battery according to claim 1, wherein the sealant layer includes a plurality of layers, and any one of the layers in the sealant layer is the cleavage induction portion.   The exterior material for a lithium ion battery according to claim 1, wherein the adhesive resin layer is a single layer, and the adhesive resin layer itself is the cleavage induction portion.   The exterior material for a lithium ion battery according to claim 1, wherein the sealant layer is a single layer, and the sealant layer itself is the cleavage induction portion.   The packaging material for a lithium ion battery according to any one of claims 1 to 5, wherein a corrosion prevention treatment layer is also formed on a surface of the metal foil layer on the base material layer side.   The said corrosion prevention processing layer is a layer formed with the corrosion prevention processing agent containing a trivalent chromium, The exterior material for lithium ion batteries as described in any one of Claims 1-6.   The exterior material for a lithium ion battery according to any one of claims 1 to 7, wherein the adhesive resin layer contains at least one of an acid-modified elastomer resin and an acid-modified polyolefin resin.   The exterior material for a lithium ion battery according to any one of 1 to 8, wherein both the adhesive resin layer and the sealant layer contain a thermoplastic resin.   The external packaging material for lithium ion batteries as described in any one of Claims 1-9 in which the shaping | molding improvement layer is formed between the said base material layer and metal foil layer.   The lithium ion battery provided with the exterior material for lithium ion batteries as described in any one of Claims 1-10.

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