WO2017094957A2 - Packaging material for electrochemical cell containing self-healing substances - Google Patents

Abstract

The present invention relates to a packaging material for an electrochemical cell containing self-healing substances, and the purpose of present invention is to improve reliability and stability by self-healing micro-cracks which may occur in a resin film when the packaging material is press-molded into a receiving space for an electrode structure. To this end, the packaging material for an electrochemical cell according to the present invention comprises a multilayer film having a structure in which a substrate layer formed as the outermost layer and made of a resin film , a barrier layer made of a metal foil , and a sealant layer for thermal bonding, formed as the innermost layer, are sequentially laminated, wherein the sealant layer contains self-healing substances .

Description

Packaging materials for electrochemical cells containing self-healing substances

The present invention relates to a packaging material for an electrochemical cell containing a self-healing material, and more particularly, a micro-crack that may occur in a resin film during press molding into a storage space of an electrode structure. The present invention relates to a packaging material for an electrochemical cell containing self-healing materials that improve the reliability and stability by allowing the self to heal itself.

As technology development and demand for mobile devices and electric vehicles increase, the demand for secondary batteries as an energy source is increasing.

Accordingly, researches on lithium ion secondary batteries having high energy density and discharge voltage among secondary batteries have been actively conducted.

Such lithium secondary batteries can be broadly classified into cylindrical batteries, rectangular batteries, pouch-type batteries, and the like according to their appearance.

Recently, due to the miniaturization of mobile devices, there is an increasing demand for thin rectangular batteries and pouch-type batteries, and in particular, interest in pouch-type batteries, which are easily deformed, inexpensive to manufacture, and light in weight, is increasing. .

The pouch-type battery has a structure in which an electrode assembly having a positive electrode, a separator, and a negative electrode structure is built in a battery case in which a laminate sheet including a resin layer and a metal layer is formed in a pouch type.

As a packaging material of such a pouch-type battery, a film having a multilayer structure in which a base material layer as an outermost layer, a barrier layer and a heat bonding layer as an innermost layer are sequentially stacked is used. Heat Seal).

The packaging material for electrochemical cells thus formed is molded by a press to form a rectangular storage space.

By the way, according to the conventional packaging material for electrochemical cells, there is a problem that micro-crack occurs in the resin film during press molding in order to secure the storage space of the electrode structure.

Accordingly, there is a problem that the reliability and safety of the product is lowered, the breakdown of the insulation and the leakage of the electrolyte occurs.

The present invention is to solve the above problems of the prior art, the purpose of the self-healing microcracks generated in the resin film when pressing the packaging material into the storage space of the electrode structure to improve the reliability of the product.

Another object of the present invention is to provide an electrochemical cell packaging material containing self-healing materials capable of increasing insulation and safety and preventing electrolyte leakage.

Packaging material for an electrochemical cell containing the self-healing material of the present invention for achieving the above object is a packaging material for an electrochemical cell, a base layer made of a resin film as the outermost layer; A barrier layer made of metal foil; Sealant layer that is heat-sealed as the innermost layer; a multilayer film having a structure laminated in this order, characterized in that the sealant layer contains a self-healing material.

In addition, the self-healing material is made of isocyanate is characterized in that the phase is embedded in the capsule.

In addition, the isocyanate is toluene di-isocyanate (TDI), isophorone di-isocyanate (IPDI), hexamethylene di-isocyanate (HDI), hexamethylene biuret (Hexamethylene Biuret) , And hexamethylene trimer (Hexamethylene Trimer) is characterized in that at least one selected from the group consisting of.

In addition, the capsule is characterized in that at least one selected from the group consisting of poly urea formaldehyde (Poly Urea Formaldehyde, PUF), polyurethane (Polyurethane, PU), epoxy amine (Epoxy Amine).

In addition, the capsules are characterized in that they are prepared by emulsification, layer-by-layer (LBL), coacervation or internal phase separation methods.

In addition, the self-healing material is characterized in that it contains 0.01 to 10% by weight based on the total weight of the sealant layer.

In addition, the sealant layer is characterized in that made of polypropylene or polyethylene.

In addition, the sealant layer, the skin layer; It consists of a homo layer (Homo) layer laminated between the skin layer, characterized in that the self-healing material is included in the skin layer.

In addition, the skin layer is characterized in that made of polypropylene or polyethylene.

According to the present invention, the self-healing material is included in the sealant layer, thereby self-healing the microcracks generated in the resin film when press molding the packaging material into the storage space of the electrode structure, thereby improving the reliability of the product.

In addition, there is an effect that can increase the insulation and safety and prevent leakage of the electrolyte.

1 is a cross-sectional view showing the structure of a packaging material for an electrochemical cell containing a self-healing material according to Example 1 of the present invention.

Figure 2 is a cross-sectional view showing the structure of the packaging material for an electrochemical cell containing a self-healing material according to a second embodiment of the present invention.

3 is a cross-sectional view showing another structure of a packaging material for an electrochemical cell containing a self-healing material according to Example 2 of the present invention.

Figure 4 is a cross-sectional view showing another structure of a packaging material for an electrochemical cell containing a self-healing material according to a second embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Example 1>

Packaging material for an electrochemical cell containing a self-healing material according to the first embodiment of the present invention, as shown in Figure 1, the substrate layer 10, barrier layer 20, sealant layer ( 30), the adhesive layer 40 and the self-healing material (C) for bonding between the layers.

The base layer 10 is made of a resin film, which gives a lithium ion battery package high piercing resistance (pinhole resistance), insulation, workability, and absorbs shock from the outside.

As for the said base material layer 10, it is preferable to use resin films, such as a stretched polyester resin or a stretched nylon resin.

Examples of the polyester resins include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymerized polyester, polycarbonate, and the like.

Moreover, as an example of the said nylon resin, a polyamide resin, ie, a nylon 6, nylon 6.6, a copolymer of nylon 6 and nylon 6.6, nylon 6.10, polymethyylene adipamide (MXD6), etc. are mentioned.

The barrier layer 20 is made of metal foil, and prevents water vapor from entering the lithium ion battery from the outside.

The barrier layer 20 preferably uses an aluminum alloy having a thickness of 15 μm or more in order to stabilize its own pinhole and press molding and to provide pinhole resistance.

In addition, the aluminum alloy preferably contains 0.3 to 9.0% by weight of iron, more preferably 0.7 to 2.0% by weight.

Thus, when aluminum contains iron, compared with aluminum which does not contain iron, the malleability of aluminum becomes good and the generation | occurrence | production of a pinhole becomes small at the time of bending.

When iron content is less than 0.3 weight% in said aluminum, effects, such as pinhole generation prevention and formability improvement, cannot be expected.

Moreover, when the said iron content exceeds 9.0 weight%, the softness | flexibility as aluminum will fall and the press formability as a packaging material will worsen.

The sealant layer 30 is disposed as the innermost layer of the packaging material and is formed of a heat adhesive resin for fusion bonding of the packaging materials facing each other.

In addition, different resin species are used for the sealant layer 30 depending on whether the tab film is interposed between the sealant layer 30 and the positive electrode tab or the negative electrode tab.

In the case of interposing the tab film, it is preferable to use a film made of olefin resin alone or a mixture thereof, and in the case of not interposing the tab film, acid-modified by graft-modification with unsaturated carboxylic acid. Preference is given to using films consisting of polyolefins.

The sealant layer 30 may be a single layer or multilayer of polypropylene, linear low density polyethylene, medium density polyethylene, or a single layer or multilayer film made of a blend resin of linear low density polyethylene and medium density polyethylene.

In addition, any type of polypropylene may be used for the sealant layer 30, and examples thereof include random propylene, homopropylene, block propylene, and the like.

Moreover, you may add the polymer which consists of a low crystalline ethylene butene copolymer, a low crystalline propylene butene copolymer, or the three-component copolymer of ethylene butene propylene to linear low density polyethylene and a medium density polyethylene.

Moreover, you may add anti-blocking agent (made by AB), such as a silica, a zeolite, and acrylic resin beads, and a slip agent of fatty acid amide system to these resin.

The sealant layer 30 includes a self-healing material as described below.

* The said adhesive layer 40 is a resin layer which adhere | attaches the said base material layer 10, the barrier layer 20, the barrier layer 20, and the said sealant layer 30 firmly.

The adhesive layer 40 may be formed by a method such as a dry laminate method, an extrusion laminate method, a coextrusion laminate method, a thermal laminate method, or the like. The substrate layer 10, the barrier layer 20, and the barrier layer ( 20) and the sealant layer 30 is bonded.

When performing adhesion by the dry lamination method, polyester, polyethylene amine, polyether, cyanoacrylate, urethane, organic titanium, polyether urethane, epoxy, polyester urethane, imide, Isocyanate type, polyolefin type, or silicone type adhesive agent can be used.

Further, other layers may be interposed between adjacent layers of the layers.

On the other hand, the self-healing material (C) is included in the sealant layer 30, when the sealant layer 30 is thermally fused to each other, to heal microcracks generated in the sealant layer 30.

The self-healing material (C) is made of isocyanate and embedded in the capsule, and solidifies by reacting with water (H ₂ O) in the air.

Examples of the isocyanate include toluene di-isocyanate (TDI), isophorone di-isocyanate (IPDI), hexamethylene di-isocyanate (HDI), hexamethylene biuret (Hexamethylene biuret) And, and hexamethylene trimer (Hexamethylene Trimer) consists of one or more selected from the group consisting of.

When the isocyanate is micro-cracked in the sealant layer 30 during press molding of the packaging material, the capsules are broken together, thereby reacting with air to coagulate and heal the microcracks.

The capsule is made of one or more selected from the group consisting of poly urea formaldehyde (Poly Uurea Formaldehyde, PUF), polyurethane (Polyurethane, PU), epoxy amine (Epoxy Amine).

And the capsule is prepared by emulsification, layer-by-layer (LBL) assembly, coacervation or internal phase separation method.

The capsule includes the self-healing material (C) in a phase-separated state from the sealant layer (30), and when the microcracks occur in the sealant layer (30), the self-healing material (C) is broken together. Release to the outside to heal microcracks.

Such self-healing material (C) is. It is preferably contained in an amount of 0.01 to 10% by weight, and more preferably in an amount of 0.1 to 3% by weight based on the total weight of the sealant layer 30.

When the amount of self-healing material (C) contained in the sealant layer 30 is less than 0.01% by weight, it is difficult to cure the microcracks, and when the amount exceeds 10% by weight, the heat adhesiveness of the sealant layer 30 is increased. Degrades.

<Example 2>

Packaging material for an electrochemical cell containing a self-healing material according to the second embodiment of the present invention, as shown in Figure 2, the base layer 10, barrier layer 20, sealant layer 30, between each layer It comprises an adhesive layer 40 and a self-healing material (C) for bonding the.

In the second embodiment, the sealant layer 30 is different from the first embodiment, and the rest of the configuration is the same.

The sealant layer 30 includes a skin layer 31 and a homo layer 32 stacked between the skin layers 31.

Since the skin layer 31 is made of the same material as the sealant layer 30 of the above-described embodiment 1, duplicated description will be omitted.

As shown in FIG. 2, the skin layer 31 is stacked above and below the homo layer 32 and includes a self-healing material (C).

In addition, as a modification of the second embodiment, as shown in FIG. 3, the self-healing material C may be included only in the skin layer 31 stacked with the barrier layer 20.

In addition, as shown in FIG. 4, the self-healing material C may be included only in the skin layer 31 disposed on the innermost layer.

The self-healing material (C) included in this way heals the microcracks generated in the skin layer 31 during press molding of the packaging material.

As described above, exemplary embodiments of the present invention have been described by way of example, and the scope of the present invention is not limited to the above-described specific embodiments. Those skilled in the art will understand that various changes and modifications can be made without departing from the scope of the present invention.

Claims (9)

1. As a packaging material for electrochemical cells,

   Base material layer 10 which consists of a resin film as outermost layer;

   A barrier layer 20 made of metal foil;

   Sealant layer 30 to be heat-sealed as the innermost layer; is a multilayer film having a structure stacked in this order,

   The sealant layer 30, the packaging material for an electrochemical cell containing a self-healing material, characterized in that it contains a self-healing material (C).
2. The method according to claim 1,

   The self-healing material (C) is a packaging material for an electrochemical cell containing a self-healing material, characterized in that the isocyanate is embedded in the capsule is separated.
3. The method according to claim 2,

   The isocyanate is, toluene di-isocyanate (TDI), isophorone di-isocyanate (IPDI), hexamethylene di-isocyanate (HDI), hexamethylene biuret (Hexamethylene Biuret), And hexamethylene trimer (Hexamethylene Trimer) packaging material for an electrochemical cell containing a self-healing material, characterized in that at least one selected from the group consisting of.
4. The method according to claim 2,

   The capsule is an electric containing self-healing material, characterized in that at least one selected from the group consisting of poly urea formaldehyde (Poly Urea Formaldehyde, PUF), polyurethane (Polyurethane, PU), epoxy amine (Epoxy Amine) Packaging materials for chemical cells.
5. The method according to claim 2,

   The capsule is a packaging material for an electrochemical cell containing a self-healing material, characterized in that it is prepared by emulsification, layer-by-layer (LBL), coacervation or internal phase separation method. .
6. The method according to claim 1,

   The self-healing material (C), the packaging material for an electrochemical cell containing a self-healing material, characterized in that it contains 0.01 to 10% by weight relative to the total weight of the sealant layer (30).
7. The method according to claim 1,

   The sealant layer 30 is a packaging material for an electrochemical cell containing a self-healing material, characterized in that made of polypropylene or polyethylene.
8. The method according to any one of claims 1 to 6,

   The sealant layer 30,

   A skin layer 31;

   It consists of a homo layer 32 which is laminated between the skin layer 31,

   The self-healing material (C) is a packaging material for an electrochemical cell containing a self-healing material, characterized in that included in the skin layer (31).
9. The method according to claim 8,

   The skin layer 31 is a packaging material for an electrochemical cell containing a self-healing material, characterized in that made of polypropylene or polyethylene.

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