JP5569065B2 - Lithium ion battery container, lithium ion battery equipped with the same, and method for producing lithium ion battery container - Google Patents

Description

  The present invention relates to a container for a lithium ion battery, a lithium ion battery including the same, and a method for manufacturing a container for a lithium ion battery.

  Conventionally, lead-acid batteries and nickel-metal hydride batteries have been widely used as secondary batteries. However, with the miniaturization of portable devices such as mobile phones and notebook computers, lithium that can be made lighter with higher energy density. Many ion secondary batteries are used. In recent years, in particular, laminated lithium-ion batteries, which have advantages in freedom of shape, thickness reduction, weight reduction, and heat dissipation, are different from the can type that has been used as a conventional packaging material for batteries. It is actively developed as a secondary battery.

  Laminate type lithium ion battery container has a three-side seal, four-side seal, pillow pouch type, and battery case material, in which a battery case is made to open on one side and a lithium ion battery is stored inside There is an embossed type in which a recess is formed by press molding and a lithium ion battery is accommodated in the recess. In any container, the container edge is sealed by thermal bonding of the sealant layer.

  By the way, lithium salt such as LiPF6 and LiBF4 is used as the electrolyte for the contents of the lithium ion battery. These salts hydrolyze and react with moisture to generate hydrofluoric acid. Therefore, when water permeates into the lithium ion battery, hydrofluoric acid is generated in the battery, and there are problems such as corrosion of the metal surface in the exterior material and a decrease in laminate strength between the layers of the multilayer film.

Therefore, the exterior material used for the laminate-type lithium ion battery container uses, for example, an aluminum foil for a part of a multilayer film in which a base material layer, an adhesive layer, an aluminum foil layer, an adhesive resin layer, and a sealant layer are sequentially laminated. Thus, moisture intrusion from the surface of the multilayer film is blocked. However, since the end surfaces of the adhesive resin layer and the sealant layer are present on the seal end surface of the battery container edge portion, the end surfaces of the adhesive resin layer and the sealant layer pass through these layers without passing through the aluminum foil layer. It was difficult to completely block the ingress of moisture into the battery container.
In view of this, studies have been made to suppress the intrusion of moisture from the end face of the heat seal portion.

  Patent Documents 1 and 2 disclose a battery container that suppresses intrusion of moisture from a seal end surface by thinning an adhesive resin layer and a sealant layer in a heat seal portion. Patent Document 1 describes a battery container in which moisture permeability is suppressed by thinning a sealant layer in the heat seal portion. However, thinning of the heat seal portion by compression promotes the formation of poly balls (resin leakage) outside the seal edge and causes bag breakage. Further, there is a possibility that the seal strength cannot be maintained by reducing the thickness of the sealant layer.

  Patent Document 2 discloses a heat seal method that secures a sealing strength against the intrusion of moisture from the outside and the internal pressure of the container by changing the thickness of the sealant layer at the center portion of the seal width, and is produced by the method. A battery container is described. However, by providing the step, an edge, that is, a deformed portion that is recessed in a square shape is generated on the surface of the seal portion, and the thickness of the adhesive resin layer and the sealant layer is rapidly changed. As a result, a large stress is easily applied to the edge portion, which causes edge breakage due to an external load.

JP 2001-176466 A JP 2001-199413 A

  Then, in view of the problem of a prior art, this invention aims at providing the battery container which has the heat seal part without a level | step difference which can prevent bag breaking, and can suppress moisture permeation | transmission and can ensure sealing intensity | strength. .

As a means for solving the above problems, the invention according to claim 1 is a film in which at least an adhesive layer, an aluminum foil layer, an adhesive resin layer, and a sealant layer are sequentially laminated on one surface of a base material layer. In the lithium ion battery container formed by heat-sealing the edge part of the laminated film so that the sealant layers are adhered to each other, the thickness of the inner seal edge part is the same as the inner battery container equal thickness, except those to produce the total difference in thickness of the inner side of the seal edge portion and the outer side of the seal edge portion or sealing edges adhesive resin layer and the sealant layer of by providing the step, the adhesive resin layer And the total thickness of the sealant layer continuously decreases from the inner side to the outer side of the battery container, and the seal edge portion or seal on the outer side rather than the seal edge portion on the inner side. Decreased total thickness of the adhesive resin layer and the sealant layer of Le edge portion, that it has a heat-sealed portion without steps, formation of polymer bead in the container cell during heat sealing, and suppress the occurrence of cracks This is a container for a lithium ion battery.

The invention according to claim 2 is the lithium ion battery container according to claim 1 , wherein the total thickness of the adhesive resin layer and the sealant layer of the seal edge portion on the inner side is larger than 40 μm. In this invention, a seal edge part means the part which deform | transformed between the heat seal part formed of the edge part of a seal bar, and the laminated film adjacent to this. Moreover, a seal edge part means the cut part at the time of cutting the heat seal part between an inner side seal edge part and an outer side seal edge part.

The invention according to claim 3 is the lithium ion battery container according to any one of claims 1 and 2, wherein the sealant layer is a resin having thermoplasticity.
According to a fourth aspect of the present invention, the sealant layer is made of polypropylene, and the polypropylene layer is a single layer of homopolypropylene, random polypropylene, or block polypropylene, or a laminate composed of a plurality selected from these layers. It is formed, The container for lithium ion batteries of any one of Claims 1-3 characterized by the above-mentioned.

Moreover, the invention according to claim 5 is characterized in that the adhesive resin layer is formed of an acid-modified elastomer resin, a single layer of acid-modified polyolefin resin, or a composite layer of both. The container for a lithium ion battery according to any one of the above.
The invention according to claim 6 is the lithium ion battery container according to any one of claims 1 to 5, wherein at least one surface of the aluminum foil layer is subjected to chemical conversion treatment.
The invention according to claim 7 is the lithium ion battery container according to claim 6, wherein the chemical conversion treatment is a chemical conversion treatment containing trivalent chromium.
The invention according to claim 8 is a lithium ion battery comprising the container for a lithium ion battery according to any one of claims 1 to 7.

The invention according to claim 9 is an edge portion of two laminated films obtained by sequentially laminating at least an adhesive layer, an aluminum foil layer, an adhesive resin layer, and a sealant layer on one surface of a base material layer. When manufacturing a lithium ion battery container by heat-sealing so that the sealant layers adhere to each other, the thickness of the seal edge portion on the inner side is made equal to the thickness of the battery container on the inner side. It does not cause a difference in the total thickness of the adhesive resin layer and sealant layer of the seal edge part on the inner side and the seal edge part or the seal edge part on the outer side by providing, and it adheres in the heat seal part of the laminated film As a pair of seal bars that heat and press across the edge so as to continuously reduce the total thickness of the resin layer and sealant layer from the inner side to the outer side of the battery container, By using a slant so that the space between the parts that press the edge continuously narrows from the inner side to the outer side of the battery container, the seal edge part on the outer side or the seal edge part on the outer side, By reducing the total thickness of the adhesive resin layer and sealant layer at the seal edge and forming a heat-sealed part with no steps, formation of poly balls in the battery container during heat sealing and generation of cracks It is a manufacturing method of the container for lithium ion batteries characterized by suppressing .

According to the configuration of the first aspect of the present invention, the total thickness of the adhesive resin layer and the sealant layer in the heat seal portion is continuously changed from the inside to the outside of the battery container, By suppressing the formation of poly balls and the occurrence of cracks, it is possible to provide a battery container having high impact resistance.
Further, according to the configuration of the second aspect of the present invention, by reducing the total thickness of the adhesive resin layer and the sealant layer on the outer seal edge portion or the seal end edge portion rather than the inner seal edge portion, It is possible to provide a battery container capable of suppressing the moisture permeation of the battery and ensuring the sealing strength against the internal pressure of the container.

Moreover, according to the structure of Claim 3 of this invention, it is possible to provide the battery container excellent in impact resistance and heat-sealing property.
Further, according to the configuration of claim 4 of the present invention, since the fusion temperature and hardness can be selected, it is possible to provide a battery container capable of selecting impact resistance and heat sealability according to the purpose. .
Moreover, according to the structure of Claim 5 of this invention, it is possible to provide the battery container which is excellent in content-proof property, such as electrolyte solution, and does not have the fall of adhesive force by degradation of adhesive resin at the time of hydrofluoric acid generation | occurrence | production. .
Moreover, according to the structure of Claim 6 of this invention, it is possible to provide the battery container which is excellent in content-proof property, such as electrolyte solution, and does not have a fall of adhesion | attachment with an adhesive agent at the time of hydrofluoric acid generation | occurence | production.

Moreover, according to the structure of Claim 7 of this invention, it is possible to provide the container for batteries excellent in long-term reliability which has especially hydrofluoric acid resistance.
Moreover, according to the structure of Claim 8 of this invention, it is possible to provide the lithium ion battery excellent in long-term reliability by providing the said container for lithium ion batteries.
Moreover, according to the structure of Claim 9 of this invention, by using the thing which the part which presses the edge part of a laminated | multilayer film inclines from the inner side to the outer side of a battery container among a pair of seal bars, it uses in a prior art. In comparison, the battery container according to any one of claims 1 to 8 can be manufactured without increasing the manufacturing process of the battery container.

It is sectional drawing which showed an example of embodiment of the laminated | multilayer film for lithium ion batteries used for this invention. An example of the sealing method of the laminated film for lithium ion batteries used for this invention is shown. The other example of the sealing method of the laminated | multilayer film for lithium ion batteries used for this invention is shown.

Hereinafter, an embodiment of a container for a lithium ion battery according to the present invention and an example of a method for heat sealing a laminated film for forming a container for a lithium ion battery will be described in detail.
A laminated film 1 for a lithium ion battery is an exterior material of the battery. As shown in FIG. 1, an adhesive layer 10, an aluminum foil layer 15, and a chemical conversion treatment layer 20 are formed on one surface of a base material layer 5. The adhesive resin layer 25 and the sealant layer 30 are sequentially laminated.

  The laminated film 1 is embossed to house the positive electrode, the separator, and the negative electrode, the tab is led out from the inside of the container, and then the laminated film is overlaid so that the sealant layer 30 faces, leaving one side. Heat seal. Thereafter, an electrolytic solution is injected from the opened one side, the remaining one side is heat-sealed in a vacuum environment, and the inside is sealed, thereby producing a lithium ion battery. At this time, as shown in FIG. 2, the total thickness of the adhesive resin layer 25 and the sealant layer 30 continuously changes from the inside to the outside of the battery container, and the sealing edge on the outer side rather than the sealing edge portion on the inner side. The edge portion of the exterior material is heat-sealed so that the total thickness of the adhesive resin layer and the sealant layer at the portion or the seal edge portion is reduced. This provides a battery container capable of suppressing the formation of poly beads in the battery container during heat sealing, the generation of cracks, the suppression of moisture permeation from the outside, and the sealing strength against the internal pressure of the container. Is possible.

<Base material layer>
The base material layer 5 is provided for the purpose of imparting heat resistance in a sealing process during the manufacture of a lithium ion battery, and for preventing pinholes that may occur during processing and distribution, and uses a resin layer having insulating properties. As such a resin layer, for example, a stretched or unstretched film such as a polyester film, a polyamide film, and a polypropylene film can be used, or a single layer or a laminated film of two or more layers can be used. A stretched polyamide film or a stretched polyester film is preferable in terms of improving pinhole resistance and insulation. Further, the thickness of the base material layer 5 is preferably 6 to 40 μm, more preferably 10 to 25 μm in consideration of pinhole resistance and workability. Furthermore, the base material layer 5 may contain or apply additives such as slip agents and antiblocking agents.

<Adhesive layer>
As the adhesive layer 10, a two-component curable polyurethane adhesive using a polyester polyol, a polyether polyol or an acrylic polyol as a main agent and an aromatic or aliphatic isocyanate as a curing agent is preferable. By performing the aging after coating at 40 ° C. for 4 days or longer, the reaction between the OH group and the NCO group proceeds and the films on both sides are firmly bonded. In general, the molar ratio [NCO / OH] of the curing agent NCO to OH of the main agent is preferably about 1 to 10, more preferably 2 to 5. In addition, the thickness of the adhesive layer 10 is preferably 1 to 10 μm, more preferably 3 to 7 μm in consideration of adhesive strength, followability, workability, and the like.

<Aluminum foil layer>
As a material of the aluminum foil layer 15, a general soft aluminum foil can be used, but it is desirable to use an aluminum foil containing iron for the purpose of imparting further pinhole resistance and extensibility during molding. 0.1-9.0 mass% is preferable in 100 mass% of aluminum foil, and, as for content of iron, 0.5-2.0 mass% is more preferable. If the lower limit value of the iron content is less than the above value, sufficient pinhole resistance and ductility cannot be imparted. On the other hand, if the upper limit value is more than the above value, flexibility is impaired. The thickness of the aluminum foil layer 15 is preferably 9 to 200 μm and more preferably 15 to 100 μm in view of barrier properties, pinhole resistance and workability.

  Although the untreated aluminum foil may be used for the aluminum foil layer 15, it is preferable to use a degreased aluminum foil. The degreasing treatment is roughly classified into a wet type and a dry type. In the wet type, acid degreasing, alkali degreasing and the like can be mentioned. 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 alone or in combination of two or more. Moreover, you may mix | blend various metal salts used as supply sources, such as Fe ion, as needed from a viewpoint of improving the etching effect of aluminum foil.

  Examples of the alkali used for alkali degreasing include a strong etching type such as sodium hydroxide. Moreover, you may use what mix | blended weak alkali type and surfactant. Such degreasing is performed by a dipping method or a spray method. As one of the dry type methods, there is a method in which degreasing treatment is performed by extending the treatment time in the step of annealing aluminum. In addition to the above, examples of the degreasing treatment include a frame treatment and a corona treatment. Furthermore, a degreasing treatment in which pollutants are oxidatively decomposed and removed by active oxygen generated by irradiating with ultraviolet rays having a specific wavelength is also included.

<Chemical conversion treatment layer>
The chemical conversion treatment layer 20 is desirably applied to at least one side of the aluminum foil layer 15, and particularly preferably applied to the adhesive resin layer 25 side. This is provided for the purpose of preventing corrosion of the aluminum foil layer 15 due to hydrofluoric acid generated by the reaction between the electrolytic solution and moisture, and improving wettability and adhesion to the adhesive resin layer 25. A coating film can be formed using an immersion-type anticorrosion treatment agent. For example, by performing a chromate treatment containing trivalent chromium, an environment-friendly chromate treatment that does not contain hexavalent chromium, which is an environmentally destructive substance, can be performed.

  In addition to the above treatment, any coating film satisfying the corrosion resistance of the aluminum foil layer 15 can be used. The thickness of the chemical conversion treatment layer 20 is preferably 10 nm or more and 5 μm or less, more preferably 20 nm or more and 500 nm or less in consideration of the corrosion prevention function and the function as an anchor. Moreover, by providing a chemical conversion treatment layer on both surfaces, corrosion of not only the sealant layer 30 but also the aluminum foil layer 15 from the base material layer 5 side can be prevented.

<Adhesive resin layer>
The adhesive resin layer 25 is a layer that adheres the sealant layer 30 and the aluminum foil layer 15 on which the chemical conversion treatment layer 20 is formed. The resin constituting the adhesive resin layer 25 is preferably an acid-modified polyolefin resin or an acid-modified elastomer resin obtained by graft-modifying maleic anhydride or the like to a polyolefin resin or an elastomer resin. Examples of the polyolefin resin include low density, medium density, and high density polyethylene; ethylene-α olefin copolymer, homo-block, random polypropylene, and propylene-α olefin copolymer. These polyolefin resins may be used individually by 1 type, and may use 2 or more types together.
As a result, it is possible to provide a battery container that has excellent resistance to contents such as an electrolytic solution and does not have a decrease in adhesion due to deterioration of the adhesive resin even when hydrofluoric acid is generated. At this time, the thickness of the adhesive resin layer 25 is preferably 1 to 40 μm, and more preferably 5 to 20 μm. This is because if the adhesive resin layer is thinner than 1 μm, the adhesive strength cannot be maintained, and if it is thicker than 40 μm, moisture permeation becomes high.

<Sealant layer>
The resin constituting the sealant layer 30 is preferably a thermoplastic resin, and examples of the component include polyolefin resins such as polyethylene and polypropylene. Thereby, a battery excellent in impact resistance and heat sealability can be provided. Examples of the polypropylene include homopolypropylene, random polypropylene, and block polypropylene. These may be a single layer film or a film in which a plurality of layers are laminated.

This makes it possible to select the fusing temperature and hardness, and to select impact resistance and heat seal according to the purpose. At this time, the thickness of the sealant layer 30 is preferably 25 to 100 μm. This is because if the sealant layer is thinner than 25 μm, the sealing strength cannot be maintained, and if it is thicker than 100 μm, the moisture permeation becomes high. The sealant layer 30 may be blended or coated with various additives such as a flame retardant, slip agent, anti-blocking agent, antioxidant, light stabilizer, and tackifier.

<Method for producing a container for a lithium ion battery>
Next, although the manufacturing method of the container for lithium ion batteries of this invention shown in FIG. 1 is described, it is not limited to this.
<Lamination process of chemical conversion treatment layer to aluminum foil layer>
A chemical conversion treatment liquid composed of a metal compound, a phosphorus compound, a binder resin, and a crosslinking agent is applied to the aluminum foil layer 15, dried and cured, and the chemical conversion treatment layer 20 is formed. As a coating method, a known method is used, and examples thereof include a gravure coater, a gravure reverse coater, a roll coater, a reverse roll coater, a die coater, a bar coater, a kiss coater, and a comma coater. As described above, the aluminum foil layer 15 may be an untreated aluminum foil, or may be an aluminum foil that has been pretreated by a wet type or a dry type. It is also possible to form the chemical conversion treatment layer 20 on both surfaces of the aluminum foil.

<Bonding process of base material layer and aluminum foil layer>
The aluminum foil layer 15 on which the chemical conversion treatment layer 20 is formed and the base material layer 5 are bonded together. As a method of bonding, dry lamination, non-solvent lamination, wet lamination, and the like are used, and both are bonded with a polyurethane adhesive mainly composed of polyester polyol, polyether polyol, and acrylic polyol, and the base material layer 5 A laminate composed of / adhesive layer 10 / aluminum foil layer 15 / chemical conversion treatment layer 20 is produced.

<Lamination process of sealant layer>
A sealant layer 30 is laminated on the laminate. Examples of the lamination method include wet lamination, extrusion lamination, dry lamination, hot melt lamination, non-solvent lamination, heat lamination, and the like. In the case of extrusion lamination, the adhesive resin layer 25 is extrusion-laminated on the chemical conversion treatment layer 20 of the laminate, and the sealant layer 30 is laminated to produce a laminated film 1 for a lithium ion battery container. The chemical conversion treatment layer 20 may be provided in-line during the extrusion lamination. Thereafter, for the purpose of improving the adhesion between the chemical conversion treatment layer 20 and the adhesive resin layer 25, heat treatment (aging treatment, thermal lamination, etc.) is performed. It is also possible to create a multilayer film with the adhesive resin layer 25 and the sealant layer 30 and to laminate the laminate on the laminate by thermal lamination.

<Heat sealing process>
The laminated film 1 for a lithium ion battery is overlaid so that the sealant layers 30 face each other, and heat sealed as follows to make a lithium ion battery container. The total thickness of the superimposed adhesive resin layer 25 and sealant layer 30 continuously changes from the inside to the outside of the battery container, and the seal edge portion or the seal edge portion on the outer side rather than the seal edge portion on the inner side. The edge of the laminated film 1 is heat sealed so that the total thickness of the adhesive resin layer 25 and the sealant layer 30 is reduced.

  For example, in the heat sealing device, the upper and lower seal bars 2 are inclined to cause a difference in the total thickness of the adhesive resin layer 25 and the sealant layer 30 on the inner seal edge and the outer seal edge or seal edge. It is possible to make it. As for the inclination of the seal bar 2, the interval between the seal bars corresponding to the portion from the seal edge portion on the inner side to the seal edge portion or the seal end edge portion on the outer side is continuously larger on the inner side than on the outer side. The seal bar 2 may be inclined. For this reason, this inclination may exist in both seal bars, and may be attached only to one seal bar. Further, even when both the seal bars are inclined, both the inclinations may be symmetric, and as a result, the interval between the upper and lower seal bars is continuously outward as described above. Any change may be used as long as it changes.

Moreover, it is preferable that the total thickness of the adhesive resin layer 25 and the sealant layer 30 in the inner seal edge portion is thicker than 40 μm. This is because the sealing strength cannot be maintained when the total thickness of the adhesive resin layer 25 and the sealant layer 30 is 40 μm or less. However, in the case of the present invention, the difference between the total thickness of the adhesive resin layer 25 and the sealant layer 30 at the inner seal edge portion and the outer seal edge portion or the seal edge portion by providing a step is excluded. . This is because, by providing a step, an edge, that is, a deformed portion that is recessed in a square shape is generated in the seal portion, and the film thickness of the adhesive resin layer 25 and the sealant layer 30 changes abruptly. This is because it tends to be applied and causes edge breakage due to an external load.
The form of the battery container produced by such a heat sealing method is not limited to a specific shape. For example, a three-sided seal, a four-sided seal, a pillow pouch type bag-like container, and a battery laminated film It may be a concave container such as an embossed type in which a recess is formed by press molding and a battery is accommodated in the recess.

Although the Example of this invention is shown below, it is not necessarily limited to this.
[Materials used]
The materials used in the following test examples are as follows.
<Base material layer>
Nylon (25μm)
<Adhesive layer>
Polyurethane adhesive (4μm)

<Aluminum foil layer>
Soft aluminum foil 8079 material (40μm)
<Chemical conversion treatment layer>
Chromate treatment <Adhesive resin layer>
Maleic anhydride-modified polypropylene resin <sealant layer>
Unstretched polypropylene resin

[Production of laminated film for lithium ion batteries]
First, a chemical conversion treatment solution containing trivalent chromium is applied on an aluminum foil by microgravure coating, and is baked at 150 ° C. or more and 250 ° C. or less in a drying unit, and a chemical conversion treatment layer is formed on the aluminum foil coil. Were laminated. Next, a base material layer was provided on the surface of the aluminum foil layer opposite to the chemical conversion treatment layer using a polyurethane adhesive by a dry laminating technique. These were extruded with an extrusion laminating machine, an adhesive resin layer made of maleic acid-modified polypropylene and maleic acid-modified elastomer adhesive, and the adhesive resin layer was laminated on the chemical conversion treatment layer. Thereafter, a polypropylene resin layer was thermally laminated with the laminate to prepare a laminated film for a lithium ion battery. [Production of containers for lithium-ion batteries]

  FIG. 2 shows an example of a method for sealing a laminated film for a lithium ion battery according to the present invention, in which a seal bar of a heat sealing device and a heat sealing portion of the laminated film for a lithium ion battery are enlarged. . As a heat sealing method, an edge portion of a laminated film laminated so that sealant layers face each other was sandwiched between upper and lower seal bars, and heat-pressed at a predetermined temperature, a predetermined time, and a predetermined pressure. At this time, the upper and lower seal bars are inclined so that the total thickness H1 of the adhesive resin layer and sealant layer on the inner seal edge portion is greater than the total thickness H1 of the seal edge portion or seal edge portion on the outer side. The edge part of the exterior material was heat-sealed so that the total thickness H2 of the film was reduced.

[Evaluation]
<Seal strength evaluation>
Using the heat sealing method, the sealant layers are stacked so that the sealant layers face each other and heat-sealed, then cut into a strip of 100 × 15 mm size, and the seal edge portion or seal end on the outer side from the seal edge portion on the inner side The seal strength was measured over the edge at a tensile speed of 300 m / min. In addition, let the result whose seal strength is 40 N / 15 mm or more be acceptable.

<Evaluation of moisture permeability>
Using the heat sealing method, a laminated film for a lithium ion battery having a size of 120 mm × 110 mm is overlapped so that the sealant layers face each other, folded to an outer dimension of 120 mm × 55 mm, and both edges are heated to a width of 10 mm. By sealing, a bag having one side opened was produced. Thereafter, 5 ml of an electrolytic solution in which ethylene carbonate, dimethyl carbonate, and diethyl carbonate as the battery contents were mixed at a ratio of 1: 1: 1 was injected, and the remaining one side was heat-sealed with a width of 3 mm. Note that the 10 mm seal part was regarded as having almost no moisture permeation, and the 3 mm seal part was used as a measurement target. The produced battery container was stored for 4 weeks in an environment of 60 ° C. and 95% RH, the amount of water contained in the electrolyte after storage was measured with a Karl Fischer, and the result with a water permeability of 100 ppm or less was passed. did.

[Examples 1 and 2 Comparative Example 1]
In Examples 1 and 2 and Comparative Examples 1 and 2, as shown below, the total thickness of the adhesive resin layer and the sealant layer in the seal edge portion on the inner side and the seal edge portion on the outer side is changed, and the seal strength is evaluated. Went. The results are shown in Table 1.
<Example 1>
Total thickness of the adhesive resin layer and sealant layer on the inner seal edge 80 μm
Total thickness of the adhesive resin layer and sealant layer at the outer seal edge 40 μm
<Example 2>
Total thickness of adhesive resin layer and sealant layer on the inner seal edge 60μm
Total thickness of the adhesive resin layer and sealant layer at the outer seal edge 40 μm

<Comparative Example 1>
Total thickness of the adhesive resin layer and sealant layer on the inner seal edge 80 μm
Total thickness of the adhesive resin layer and sealant layer at the outer seal edge 80 μm
<Comparative example 2>
Total thickness of the adhesive resin layer and sealant layer on the inner seal edge 40 μm
Total thickness of the adhesive resin layer and sealant layer at the outer seal edge 40 μm

  As can be seen from the results of the above sealing strength, when the total thickness of the adhesive resin layer and the sealant layer on the inner seal edge portion is larger than 40 μm, it is possible to maintain 40 N / 15 mm or more, and the adhesive resin on the inner seal edge portion. When the total thickness of the layer and the sealant layer is 40 μm or less, 40 N / 15 mm or more cannot be maintained. Further, from the result of the moisture permeability, it was found that the moisture permeability could be suppressed to 100 ppm or less by reducing the total thickness of the adhesive resin layer and the sealant layer at the seal edge. Also, the increase in moisture permeability can be suppressed by making the total thickness of the adhesive resin layer and sealant layer at the seal edge portion thinner than the total thickness of the adhesive resin layer and sealant layer at the inner seal edge portion. all right.

From the above results, it is possible to maintain the sealing strength by making the total thickness of the adhesive resin layer and the sealant layer on the inner seal edge portion larger than 40 μm, and the adhesive resin layer on the inner seal edge portion. In addition, the moisture permeability is suppressed by heat-sealing the edge of the exterior material so that the total thickness of the adhesive resin layer and the sealant layer at the outer seal edge is smaller than the total thickness of the sealant layer. It becomes possible.
As described above, according to the present invention, by continuously changing the total thickness of the adhesive resin layer and the sealant layer in the heat seal portion from the inner side to the outer side of the battery container, moisture permeation is suppressed and the seal strength is increased. It is possible to provide a battery container that can be easily secured and that is difficult to break, and a lithium ion battery including the same.

DESCRIPTION OF SYMBOLS 1 Laminated film for lithium ion batteries 2 Seal bar 3 Inner seal edge part 4 Outer seal edge part 5 Base material layer 10 Adhesive layer 15 Aluminum foil layer 20 Chemical conversion treatment layer 25 Adhesive resin layer 30 Sealant layer H1 Internal seal edge H2 External edge

Claims (9)

A laminated film in which at least an adhesive layer, an aluminum foil layer, an adhesive resin layer, and a sealant layer are sequentially laminated on one surface of the base material layer is used, and an edge of the laminated film is adhered so that the sealant layers adhere to each other. In the lithium ion battery container formed by heat sealing the part,
The thickness of the seal edge part on the inner side is equal to the thickness of the battery container on the inner side,
Except those causing the total difference in thickness of the adhesive resin layer and the sealant layer of the seal edge portion of the seal edge portion and the outer side of the inner side or the seal edge portion by providing the step, the said adhesive resin layer Sealant The total thickness of the layer continuously decreases from the inner side to the outer side of the battery container, and the adhesive resin layer on the outer side seal edge portion or the seal edge portion rather than the inner side seal edge portion. Lithium ion is characterized in that the total thickness of the sealant layer is reduced and a heat seal portion having no step is provided, thereby suppressing the formation of poly balls in the battery container during heat sealing and the generation of cracks. Battery container. 2. The lithium ion battery container according to claim 1 , wherein the total thickness of the adhesive resin layer and the sealant layer in the inner seal edge portion is greater than 40 μm.   The container for a lithium ion battery according to claim 1, wherein the sealant layer is a resin having thermoplasticity.   The sealant layer is made of polypropylene, and the polypropylene layer is formed of a single layer of homopolypropylene, random polypropylene, or block polypropylene, or a laminate composed of a plurality selected from these layers. The container for lithium ion batteries of any one of 1-3.   5. The lithium ion battery according to claim 1, wherein the adhesive resin layer is formed of an acid-modified elastomer resin, a single layer of an acid-modified polyolefin resin, or a composite layer of both. Container.   The lithium ion battery container according to claim 1, wherein at least one surface of the aluminum foil layer is subjected to chemical conversion treatment.   The lithium ion battery container according to claim 6, wherein the chemical conversion treatment is a chemical conversion treatment containing trivalent chromium.   The lithium ion battery provided with the container for lithium ion batteries of any one of Claims 1-7. At least one adhesive layer, an aluminum foil layer, an adhesive resin layer, and a sealant layer are sequentially laminated on one surface of the base material layer so that the edge portions of two laminated films are adhered to each other. upon manufacturing a container for a lithium ion battery was heat sealed, the thickness of the seal edge portion of the inner side, on which is equal to the thickness of the battery container inner side, the inner side of the seal edge portion by providing a step The total thickness of the adhesive resin layer and the sealant layer at the seal edge portion or the seal edge portion on the outer side and the seal edge portion is not changed, and the total thickness of the adhesive resin layer and the sealant layer is set on the inner side of the battery container. As a pair of seal bars that are heated and pressed across the end edge portion so as to continuously decrease from the outer side to the outer side, the space between the portions pressing the end edge portion of the laminated film is the battery capacity. By using a slant that is continuously narrowed from the inner side to the outer side, the adhesive resin layer and the sealant layer on the outer side seal edge part or the seal edge part rather than the inner side seal edge part. Lithium-ion battery container characterized by suppressing the formation of poly balls and cracks in the battery container during heat sealing by reducing the total thickness and forming a heat-seal part without steps Manufacturing method.

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