KR102322332B1 - A film for lead tab and integrated cell pouch comprising the same - Google Patents

Abstract

Homo propylene resin herein; and a random polypropylene resin graft copolymerized with dicarboxylic acid or an acid anhydride thereof.

Description

Film for lead tab and integrated cell pouch including same {A FILM FOR LEAD TAB AND INTEGRATED CELL POUCH COMPRISING THE SAME}

The present specification discloses a film for a lead tab, a film for a lead tab having excellent thermal adhesion to both a metal and an exterior material, and an integrated cell pouch including the same.

In line with the trend of miniaturization and weight reduction of electronic devices, the demand for batteries with smaller and thinner batteries is also increasing. Although miniaturization and thinning of the single cell are required, the capacity of the cell is being developed in the direction of developing a cell with the existing capacity or an improved capacity.

However, the limited physical properties of the pouch, which cannot be further reduced in thickness, are emerging. Here, if the sealant film for the lead tab can be removed or the thickness can be reduced, as much space is created and a battery with a larger capacity can be manufactured even for a battery of the same thickness.

The conventional sealant film for lead tab has been used as a film for sealing and bonding the lead tab, which is a metal terminal, and the sealant layer of the pouch with heat and pressure (FIG. 1). It is characterized in that it must secure thermal adhesion to the

Accordingly, as a film for lead tabs having excellent thermal adhesion to both metal and exterior materials, there is a need for a film for lead tabs that can improve battery stability and battery efficiency.

In embodiments of the present invention, it is an object to provide a cell pouch having a thin thickness while maintaining physical properties such as battery capacity. To this end, a conventional cell pouch is provided with both a sealant film and a lead tab film in order to have thermal bonding performance with both an exterior material and a metal lead tab, thereby solving the problem of having a thick thickness.

In one embodiment according to the present invention in order to achieve the above object, a homo polypropylene resin; and a random polypropylene resin graft copolymerized with dicarboxylic acid or an acid anhydride thereof.

In an exemplary embodiment, the random polypropylene resin is one in which one or more polar groups selected from the group consisting of maleic acid, maleic anhydride, fumaric acid, maleimide, maleimide anhydride, itaconic acid, itaconic anhydride and derivatives thereof are introduced. can

In an exemplary embodiment, the random polypropylene resin may be a polypropylene-based resin grafted with maleic anhydride.

In an exemplary embodiment, the random polypropylene resin may have a melting point of 140° C. or higher.

In an exemplary embodiment, the random polypropylene-based resin may have a melt index (MI) of 4 to 9 (g/10min) as measured according to ASTM D1238.

In an exemplary embodiment, the lead tab film may further include at least one selected from the group consisting of an elastomer and a nucleating agent.

In an exemplary embodiment, the nucleating agent may include at least one selected from the group consisting of a transparent nucleating agent and a rigid nucleating agent.

In an exemplary embodiment, the transparent nucleating agent is a phosphate ester salt, sodium benzoate, lithium benzoate, aluminum hydroxy dipara t-butyl benzoate (Al-PTBBA) and a group consisting of talc Including one or more selected from, the rigid nucleating agent may include one or more selected from the group consisting of a sorbitol-based nucleating agent, a nonitol-based nucleating agent, and a para-t-butylphenol-sodium (PTBP-Na) complex.

In an exemplary embodiment, the nucleating agent may include both a transparent nucleating agent and a rigid nucleating agent, and the rigid nucleating agent and the transparent nucleating agent may be included in a weight ratio of 3:7 to 7:3.

In an exemplary embodiment, the nucleating agent may be included in a weight ratio of 2 to 10% by weight based on the total weight of the film for lead tabs, and the elastomer may be included in a weight ratio of 10 to 30% by weight based on the total weight of the film for lead tabs. have.

In an exemplary embodiment, the lead tab film may have a single-layer structure.

In an exemplary embodiment, the lead tab film may have a thickness of 10 to 50 μm.

In addition, in one embodiment according to the present invention, the above-described film for the lead tab; a core layer positioned on the lead tab film; and an outer layer positioned on the core layer.

In an exemplary embodiment, the core layer may include at least one metal having moisture barrier properties and gas barrier properties.

In an exemplary embodiment, the outer layer may include at least one selected from a polyamide-based resin and a polyester-based resin.

In an exemplary embodiment, the polyamide-based resin may be nylon, and the polyester-based resin may be polybutylene terephthalate (PBT) or polyethylene terephthalate (PET).

According to exemplary embodiments of the present invention, as a film for a lead tab having a single layer structure, it may have thermal adhesion to both a metal as a lead tab material and a polymer film as a pouch sealant layer.

In addition, since a separate sealing film is not required, the thickness of the film for the lead tab can be reduced, and the resulting space can be used as the battery capacity, so that a battery having a larger capacity can be implemented even for a battery of the same thickness.

1 shows a configuration diagram showing a laminated structure of a conventional AL pouch.
2 is a block diagram showing a conventional lead tab film having a multi-layer structure.
3 is a block diagram illustrating a laminated structure of an integrated cell pouch including a film for a lead tab according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in more detail.

The embodiments of the present invention disclosed in the text are illustrated for the purpose of explanation only, and the embodiments of the present invention may be embodied in various forms and should not be construed as being limited to the embodiments described in the text. .

The present invention is not intended to limit the present invention to a specific disclosed form, but is not intended to limit the present invention to a specific disclosed form, as various changes may be made and may have various forms, and all changes, equivalents or substitutes included in the spirit and scope of the present invention should be understood as including

The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate that a feature, number, step, operation, component, part, or a combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

As used herein, the term “lead tap” refers to a portion exposed outside the outer packaging material among electrode terminals (tabs) drawn out from the electrode group of the secondary battery.

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

film for lead tab

In one embodiment according to the present invention in order to achieve the above object, a homo polypropylene resin; and a random polypropylene resin graft copolymerized with dicarboxylic acid or an acid anhydride thereof. For example, the film for a lead tab may be a film for a lead tab of a secondary battery.

First, the homo polypropylene resin included in the film for lead tabs may improve physical stability and increase heat resistance, and a high melting point and high stiffness may be used. Accordingly, it may include a homo polypropylene resin having a melting point of 160° C. or higher, and specifically may include a non-polar homo polypropylene resin.

In one embodiment, the homo polypropylene resin may be included in a weight ratio of 60 to 80% by weight based on the total weight of the film for lead tabs. When included in less than 60% by weight, physical properties such as thermal bonding workability may be deteriorated, and when included in more than 80% by weight, physical properties such as sealing properties may be deteriorated.

In one embodiment, the random polypropylene resin included in the film for the lead tab may be well sealed with the lead tab metal, and specifically, it may be a random polypropylene resin in which dicarboxylic acid or an acid anhydride thereof is graft copolymerized. have.

In one embodiment, the random polypropylene resin may be one in which one or more polar groups selected from the group consisting of maleic acid, maleic anhydride, fumaric acid, maleimide, maleimide anhydride, itaconic acid, itaconic anhydride and derivatives thereof are introduced. have. Preferably, the random polypropylene resin may be a polypropylene-based resin grafted with maleic anhydride.

In one embodiment, the random polypropylene resin may have a melting point of 140° C. or higher, and this is due to the low crystallinity of the random polypropylene resin having a melting point of less than 140° C. The moisture permeability can also improve the poor physical properties. Specifically, the random polypropylene resin has a melting point of 150° C. or higher, so that sealing between the lead tab and the sealing film and sealing between the aluminum (Al) metal used in the pouch and the sealing film can be performed well.

In one embodiment, the random polypropylene resin may have a melt index (MI) of 4 to 9 (g/10min) as measured according to ASTM D1238. When the melt index of the random polypropylene resin is less than 4 g/10min, workability may be poor, and when it exceeds 9 g/10min, workability may be poor.

In one embodiment, the lead tab film may further include one or more selected from the group consisting of an elastomer and a nucleating agent.

Specifically, it may further include an elastomer in order to improve heat resistance, for example, it may further include a thermoplastic elastomer. Although it does not restrict|limit especially as said thermoplastic elastomer, For example, an olefin type thermoplastic elastomer, a styrene type elastomer, hydrogenated styrene type elastomer, etc. are mentioned.

In one embodiment, the olefin-based thermoplastic elastomer is not particularly limited, but may include, for example, an ethylene-α-olefin copolymer. For example, as said alpha-olefin, propylene, 1-butene, 1-hexane etc. are mentioned, for example. On the other hand, the styrene-based elastomer and the hydrogenated styrene-based elastomer are not particularly limited, but for example, a styrene-ethylene butylene-styrene copolymer, a styrene-ethylene propylene-styrene copolymer, a styrene-ethylene butylene-styrene hydrogenated copolymer, A styrene-ethylene propylene-styrene hydrogenated copolymer etc. are mentioned. Among them, it may be preferable to use one or more thermoplastic elastomers selected from the group consisting of ethylene-propylene rubber (EPR) and ethylene-propylene-butene rubber (EPBR) as the thermoplastic elastomer.

On the other hand, it may be preferable that the melting point of the elastomer is 80° C. or less, and by using the elastomer having a melting point of 80° C. or less, it can have the advantage of sufficiently securing adhesion to the tab surface during sealing bonding. In addition, it is preferred that the elastomer has a melt flow index (MFR) of 5 g/10 min or less.

In one embodiment, the gel fraction of the elastomer is preferably 20 to 90%. When the gel fraction is less than 20%, the degree of crosslinking is insufficient, and the amount of melting of the elastomer at the time of thermal fusion becomes excessively large. When the gel fraction exceeds 90%, the degree of crosslinking is too large, and adhesion may deteriorate.

In one embodiment, the elastomer may be included in a weight ratio of 10 to 30% by weight based on the total weight of the film for lead tabs. When included in less than 10% by weight, the sealing property of the sealing film is reduced, and when it exceeds 30% by weight, heat resistance may be reduced.

In addition, a nucleating agent may be further included to improve thermal curing properties, and the nucleating agent may include at least one selected from the group consisting of a transparent nucleating agent and a rigid nucleating agent.

The conventional film for a lead tab for a secondary battery that does not contain a nucleating agent has a lower thermal curing degree of the film, so that the barrier properties from external moisture or air and the barrier properties for preventing air permeation/moisture permeation from the electrolyte inside the battery are significantly deteriorated. The film for a lead tab according to an embodiment of the present invention may further include a nucleating agent in order to compensate for this, and thus the thermal curing degree of the film is improved, so that the barrier property may be increased, and thermal adhesiveness, sealing property, etc. are improved can be

In one embodiment, the transparent nucleating agent can impart transparency and flexibility, and phosphate ester salts, sodium benzoate, lithium benzoate, aluminum hydroxy dipara t-butyl benzoate (Aluminum hydroxy dipara t-butyl benzoate, Al- PTBBA) and may include one or more selected from the group consisting of talc.

The rigid nucleating agent may accelerate the crystallization rate of the polymer and increase the crystallization rate by refining the size of the crystal, and a group consisting of a sorbitol-based nucleating agent, a nonitol-based nucleating agent, and a para-t-butylphenol-sodium (PTBP-Na) complex. It may include one or more selected from. The sorbitol-based nucleating agent may include at least one selected from the group consisting of benzylidenesorbitol, methylbenzylidenesorbitol, ethylbenzylidenesorbitol, and 3,4-dimethylbenzylidenesorbitol, and the nonitol-based nucleating agent is 1,2,3- trideoxy-4,6:5,7-bis-0-[(4-propylphenyl)methylene]-nonitol.

In one embodiment, the transparent nucleating agent is from the group consisting of phosphate ester salts, sodium benzoate, lithium benzoate, aluminum hydroxy dipara t-butyl benzoate (Al-PTBBA) and talc. and at least one selected from the group consisting of, the rigid nucleating agent may include at least one selected from the group consisting of a sorbitol-based nucleating agent, a nonitol-based nucleating agent, and a para-t-butylphenol-sodium (PTBP-Na) complex.

In one embodiment, the film for the lead tab may preferably include both a rigid nucleating agent and a transparent nucleating agent. In this case, the rigid nucleating agent and the transparent nucleating agent may be included in a weight ratio of 3:7 to 7:3. For example, the rigid nucleating agent and the transparent nucleating agent may be included in a weight ratio of 1:1. If it is less than 3:7, the water vapor permeability properties may be reduced, and if it exceeds 7:3, the physical properties of thermal bonding workability may be deteriorated.

In one embodiment, the nucleating agent may be included in a weight ratio of 2 to 10% by weight based on the total weight of the film for lead tabs. When included in more than 10% by weight, heat resistance may decrease, and when included in less than 2% by weight, adhesiveness may decrease.

In one embodiment, the lead tab film may have a single-layer structure. Although the conventional lead tab film required two or more polymer layers in order to secure thermal adhesion to both the metal as the lead tab material and the polymer film as the pouch sealant layer (FIG. 2), the lead tab film according to the embodiment of the present invention Silver has a single-layer structure, and thus the thickness of the lead tab film can be reduced, and thus, when applied to a battery, a battery having a larger capacity can be realized even for a battery of the same thickness.

In an embodiment, the lead tab film may have a thickness of 10 to 50 μm, for example, a thickness of 20 to 40 μm or a thickness of 20 to 30 μm. Preferably, the lead tab film may have a thickness of 25 to 30 μm. When the thickness of the lead tab film is less than 10 μm, thermal adhesiveness may be reduced, and when the thickness of the lead tab film is more than 50 μm, the effect on battery capacity improvement due to the decrease in the thickness of the lead tab film may be insignificant.

Meanwhile, in another embodiment of the present invention, as a method for manufacturing a film for a lead tab for a secondary battery, a random polypropylene resin in which homopolypropylene, dicarboxylic acid, or an acid anhydride thereof is graft-copolymerized is co-extruded to prepare a film for lead tabs A manufacturing method is provided.

As described above, the film for a lead tab according to an embodiment of the present invention may have excellent battery stability and battery efficiency while maintaining dimensional stability and excellent thermal adhesion with metal and exterior materials.

All-in-one cell pouch

In addition, in one embodiment according to the present invention, the above-described film for the lead tab; a core layer positioned on the lead tab film; and an outer layer positioned on the core layer. Hereinafter, it will be described with reference to FIG. 3 .

In one embodiment, the core layer may include at least one metal having moisture barrier properties and gas barrier properties. The material of the core layer is not limited as long as it is a metal having moisture barrier properties and gas barrier properties. In addition, the core layer may block the ingress of external moisture or air, and gas generated therein.

The core layer may include at least one selected from a metal thin film and a metal deposition layer. For example, the metal thin film may use a metal foil, etc., and the metal deposition layer is a separate plastic film, for example, polyethylene terephthalate (PET), polyethylene (PE) or polypropylene (PP), etc. It may be formed by vacuum deposition on a film of

For example, the metal constituting the core layer, specifically the metal constituting the metal thin film or the metal deposition layer, is, for example, aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), tin ( Sn), zinc (Zn), indium (In), and at least one selected from the group consisting of tungsten (W) (a single metal or a mixture of single metals), or an alloy of two or more selected from these, for example can Preferably, the metal may be selected from aluminum (Al) or an aluminum alloy (Al alloy). In addition, the core layer may be surface-treated with phosphoric acid or chromium for corrosion resistance.

In one embodiment, the core layer may have a thickness of 15 μm or less, preferably 9 to 15 μm. When the thickness of the core layer is 9 μm or less, it may not be easy to implement as a cell pouch for a secondary battery.

In one embodiment, the outer layer may protect the core layer. Preferably, the outer layer has abrasion resistance and, for example, heat resistance, cold resistance, pinhole resistance, insulation, solvent resistance, and/or moldability (shape retention when processing a flexible cell pouch into a predetermined shape (box, etc.)). It may include a resin having a.

In one embodiment, the outer layer may include at least one selected from a polyamide-based resin and a polyester-based resin. Specifically, the polyamide-based resin may be nylon, and the polyester-based resin may be polybutylene terephthalate (PBT) or polyethylene terephthalate (PET).

In one embodiment, the thickness of the outer layer is not particularly limited, but may have a thickness of, for example, 10 μm to 50 μm, preferably 5 μm to 30 μm, more preferably 10 μm to 25 μm. have.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, and it will be apparent to those of ordinary skill in the art that the scope of the present invention is not to be construed as being limited by these examples.

Example

Example 1: Preparation of film for lead tab

A film for a lead tab was manufactured by a die-casting extrusion method using a co-extruder. The composition ratio of the lead tab film is 70% maleic anhydride-grafted random polypropylene resin, 20% homo polypropylene resin, 5% elastomer (EPDM ELASTOMER, Samjin Polymer) 5% nucleating agent (2.5% rigid nucleating agent and transparent) based on weight ratio nucleating agent 2.5%). The melting point of the prepared lead tab film was 150° C. or higher, and a Melting index value of 5 was measured.

Here, as the rigid nucleating agent, a sorbitol-based nucleating agent (Adeka NA-27 product) was used, and as the transparent nucleating agent, a phosphate ester salt product (Adeca NA-21 product) was used.

Example 2: Manufacture of Integral Cell Pouches

The lead tab film of Example 1 prepared by the die-casting extrusion method is laminated with the aluminum side and the solvent dry lamination method using an adhesive on the substrate in which the aluminum and the outer layer are laminated.

Comparative Example 1: Conventional AL cell pouch manufacturing

A cell pouch was prepared in the same manner as in Example 2, except that a general CPP film, not a lead tab film, was used to prepare the laminated paper.

Experimental Example: Evaluation of cell pouch properties

The physical properties of the cell pouches of Example 2 and Comparative Example 1 were comparatively evaluated, and the results are shown in Table 1 below. Here, excellent (◎), good (○), average (△) and dissatisfied (X) are respectively.

Comparative Example 1
(NY15//AL35//PP30) Example 2
(NY15//AL35//PP30 (lead tab film)) battery capacity △ ◎ Insulation Resistance △ ○ Thermal adhesion (AL//PP) ◎ ○ Thermal adhesion (AL//Lead Tab) X ◎ moisture permeability ○ ◎

1) The battery capacity was measured using a charge/discharge tester of an 8-channel battery cycler (WBCSSIF) model manufactured by One-A-Tech Co., Ltd., Korea, by manufacturing a small battery using each pouch in Comparative Example Examples. As a result of the measurement, it was confirmed that Example 2 to which the film for lead tabs was applied had an excellent battery capacity compared to Comparative Example 1.

2) Insulation resistance was measured with an insulation resistance measuring device of IR4051-10 model manufactured by Hioki, Japan, by fabricating each dummy cell in Comparative Example Examples. It was also confirmed that the insulation resistance of Example 2 to which the lead tab film was applied was superior to Comparative Example 1.

3) Thermal adhesion was measured using an adhesive strength measuring instrument of AGS-1kNX model manufactured by SHIMADZU, Japan. Here, 'AL//PP' denotes thermal adhesiveness with the polymer film, which is the pouch sealant layer, and 'AL//Lead Tab' denotes thermal adhesiveness with aluminum, the lead tab material.

In particular, in relation to the thermal adhesion (AL//PP) properties of the polymer film, which is the pouch sealant layer, Comparative Example 1 has better thermal adhesion than Example 1, but the thermal adhesion (AL//PP) with aluminum, the lead tab material. /Lead Tab) evaluation result Comparative Example 1 was able to confirm the unsatisfactory result. Accordingly, Comparative Example 1 must use a lead tab film or a sealing film when bonding the lead tab and the Al pouch.

4) The water vapor permeability of each film in Comparative Examples Examples USA. The moisture permeability of MOCON's PERMATRAN_W 3/33 MA model was measured using the equipment. As a result of the measurement, it was confirmed that Example 2, in which the film for lead tab was applied, was superior to that of Comparative Example 1 in barrier properties from external moisture or air and barrier properties for preventing air permeation/moisture permeation from the electrolyte inside the battery.

The embodiments of the present invention described above should not be construed as limiting the technical spirit of the present invention. The protection scope of the present invention is limited only by the matters described in the claims, and those skilled in the art can improve and change the technical idea of the present invention in various forms. Accordingly, such improvements and modifications will fall within the protection scope of the present invention as long as they are apparent to those of ordinary skill in the art.

Claims (16)

homo propylene resin; and a random polypropylene resin graft copolymerized with dicarboxylic acid or an acid anhydride thereof, and has a single-layer structure,
The random polypropylene resin has a melting point of 150 ℃ or more, a film for a lead tab. According to claim 1,
The random polypropylene resin is characterized in that at least one polar group selected from the group consisting of maleic acid, maleic anhydride, fumaric acid, maleimide, maleimide anhydride, itaconic acid, itaconic anhydride and derivatives thereof is introduced, for lead tabs film. 3. The method of claim 2,
The random polypropylene resin is a film for lead tabs, characterized in that the maleic anhydride graft polypropylene resin. delete According to claim 1,
The random polypropylene resin is characterized in that it shows a melt index (MI) of 4 to 9 (g/10min) when measured according to ASTM D1238, a film for a lead tab. According to claim 1,
The lead tab film further comprises at least one selected from the group consisting of an elastomer and a nucleating agent, a film for a lead tab. 7. The method of claim 6,
The nucleating agent, characterized in that it comprises at least one selected from the group consisting of a transparent nucleating agent and a rigid nucleating agent, a film for a lead tab. 8. The method of claim 7,
The transparent nucleating agent includes at least one selected from the group consisting of phosphate ester salts, sodium benzoate, lithium benzoate, aluminum hydroxy dipara t-butyl benzoate (Al-PTBBA) and talc. do,
The rigid nucleating agent, characterized in that it comprises at least one selected from the group consisting of a sorbitol-based nucleating agent, a nonitol-based nucleating agent, and a para-t-butylphenol-sodium (PTBP-Na) complex. 7. The method of claim 6,
The nucleating agent includes both a transparent nucleating agent and a rigid nucleating agent,
A film for a lead tab, characterized in that the rigid nucleating agent and the transparent nucleating agent are included in a weight ratio of 3:7 to 7:3. 7. The method of claim 6,
The nucleating agent is included in a weight ratio of 2 to 10% by weight based on the total weight of the film for the lead tab, and the elastomer is included in a weight ratio of 10 to 30% by weight based on the total weight of the film for the lead tab. Lead, film for tabs. delete According to claim 1,
The lead tab film is characterized in that it has a thickness of 10 to 50 ㎛, a film for a lead tab. Claims 1 to 3, claims 5 to 10, and any one of claims 12 for the lead tab film;
a core layer positioned on the lead tab film; and
An integrated cell pouch comprising; an outer layer positioned on the core layer. 14. The method of claim 13,
The core layer is characterized in that it comprises at least one metal having a moisture barrier property and a gas barrier property, an integrated cell pouch. 14. The method of claim 13,
Wherein the outer layer comprises at least one selected from a polyamide-based resin and a polyester-based resin, the integrated cell pouch. 16. The method of claim 15,
The polyamide-based resin is nylon,
The polyester-based resin is polybutylene terephthalate (PBT) or polyethylene terephthalate (polyethylene terephthalate, PET), characterized in that the integrated cell pouch.

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