KR101984889B1 - Cell pouch film for battery and method of the same - Google Patents

Abstract

The present invention relates to a battery cell pouch film and a manufacturing method thereof and, more specifically, to a battery cell pouch film which primer-coats a metal layer in an inline method and surface-treats the meatal layer after directly contact-heating the metal layer so as to increase an interlayer bonding force, thereby increasing quality of a battery cell and prolonging a lifetime of the battery cell, in a pouch film packing the battery cell, and a manufacturing method thereof. In addition, the battery cell pouch film comprises a basic material layer, an adhesive layer, a metal layer, and a protection layer.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery cell pouch film,

The present invention relates to a film for a pouch used for packaging a battery cell and a method of manufacturing the same.

Generally, a secondary battery, such as a lithium ion battery, is a battery that can be reused by charging. He has a long life, light weight and large capacity, and is widely used in various fields such as electric vehicles, robots, satellites, as well as portable electronic devices such as PCs, notebooks, smart phones and video cameras.

The secondary battery includes a battery cell and a cell pouch. The battery cell comprises an anode and a cathode, a separator and an electrolyte. The cell pouch is a covering material surrounding the battery cell, and is made of a multilayer film in which an aluminum layer is bonded to a substrate layer obtained by extruding a polymer resin.

At this time, a step of applying a primer coating agent separately to the aluminum layer and adhering it using an adhesive (adhesive resin) is performed in order to increase the adhesion strength between the substrate layer made of the polymer resin and the aluminum layer.

After applying the primer coating agent to the aluminum layer, hot air is applied to cure the primer coating agent. In such a conventional coating method, there is a problem that the primer coating agent is aggregated or unevenly coated on the metal surface.

Korean Patent No. 1530590 entitled " Cell pouch and its manufacturing method " (2015.06.16) "Aluminum pouch film for secondary battery, packaging material containing the same, secondary battery including the same, and manufacturing method thereof" of Korean Patent Registration No. 1454417 (Apr. 17, 2014)

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a battery cell pouch film and a method of manufacturing the battery cell pouch film.

Another object of the present invention is to provide a battery cell pouch film and a method of manufacturing the same that can smoothly perform a primer coating uniformly on a surface of a metal layer.

In order to achieve the above object, a battery cell pouch film according to a preferred embodiment of the present invention includes: a base layer formed to surround a battery cell; An adhesive layer adhered to the base layer to impart an adhesive force; A metal layer attached to the substrate layer through the adhesive layer to block gas and moisture from entering the substrate layer; And a protective layer coupled to the outside of the metal layer to protect the surface of the metal layer. The metal layer may be a film-shaped steel material which has been heated by direct contact heating with a heating roll and then subjected to a primer coating treatment.

In addition, a method of manufacturing a battery cell pouch film according to the present invention comprises the steps of: a) heating a surface of a metal film by directly contacting the heating roll, and then applying heat to the surface of the metal film, A metal surface treatment step of forming a metal layer by uniformly coating a coating agent; b) a primary dry laminating step of laminating a protective layer made of at least one of a nylon film and a polyester film on the outside of the metal layer, and aging the resultant at a temperature of 70 to 90 캜; And c) a second dry laminating step of laminating a base material layer made of a polymer resin through an adhesive layer made of a thermally adhesive resin on the inner side of the metal layer, and aging the resultant at a temperature of 140 to 180 캜.

As described above, according to the present invention, the primer coating agent can be uniformly applied by applying the primer coating agent after heating the surface of the steel material, thereby improving the quality of the battery cell.

1 is a cross-sectional view of a cell pouch film according to the present invention.
2 is a conceptual view schematically showing a process of surface-treating the metal layer of FIG.
FIG. 3 is a photograph of an experimental result showing a state in which a primer coating agent is applied to a surface of a metal layer according to an embodiment of the present invention.
FIG. 4 is a photograph of an experimental result showing a state in which a primer coating agent is applied to the surface of a metal layer according to a conventional method, as a comparative example in comparison with an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the technical idea of the present invention. The present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In describing the present invention, the respective polymer resins constituting the constitution of the present invention will be described by abbreviations. For example, polypropylene is referred to as PP, casting polypropylene as CPP, epoxy as EP, polyester as polyethylene terephthalate, and polyurethane as PU.

A. Battery cell pouch film

First, a battery cell pouch film according to the present invention comprises a substrate layer 10 made of PP resin and serving as a sealing material; An adhesive layer (20) made of an adhesive resin including a PP resin and a modified epoxy resin and giving an adhesive force to the base layer; And a metal layer 30 made of a surface-treated steel material and shielding the inflow of gas and moisture into the base layer.

This will be described in more detail.

(Substrate layer)

The base layer 10 is in contact with a battery cell located inside and serves as a sealing material for maintaining airtightness and watertightness at the junction with the battery cell, and a PP-based resin such as CPP resin is used as is well known.

The thickness of the substrate layer 10 can be adjusted according to the battery to be applied, and accordingly, the base layer 10 may be formed of a single layer structure made of PP resin, but more preferably, a multi-layer structure in which a CPP resin is laminated outside the PP resin .

(Adhesive layer)

The adhesive layer 20 is provided in contact with the base layer 10 in order to improve adhesion with the following metal layer. The adhesive layer 20 is a mixture of a PP resin and a modified EP resin.

(Metal layer)

The metal layer 30 contacts the substrate layer 10 via the adhesive layer so as to block transmission of gas and light from the outside and increase the mechanical strength. The metal layer 30 may be made of a steel material. Further, as the steel material, for example, stainless steel in film form may be used. However, an aluminum sheet may be used as the metal layer 30.

At this time, the surface of the steel material is heated and rolled to roll by a method selected from a corona treatment, a hot air heater, a ceramic heater, a plasma treatment, an infrared treatment and a high frequency heating so as to improve the bonding force between the metal layer and the substrate layer. , And a gravure or microgravure coating using a heater bar.

(Protective layer)

The protective layer 40 is laminated on the outside of the metal layer 30 to protect the surface of the metal layer. The nylon film or PET resin film having excellent impact resistance, scratch resistance and heat resistance is used as the protective layer 40 .

At this time, the protective layer 40 is bonded to the metal layer by the PU adhesive resin, thereby preventing intrusion or creasing of foreign matter.

B. Manufacturing Method of Battery Cell Pouch Film

A method of manufacturing a battery cell pouch film according to the present invention includes: a metal surface treatment step of forming a metal layer by heating a surface of a steel material made of stainless steel to form a metal layer; A first dry laminating step of laminating a protective layer made of at least one of a nylon film and a polyester film on the outside of the metal layer; And a second dry laminating step of laminating an adhesive layer made of a thermally adhesive resin on the inside of the metal layer.

This will be discussed in more detail in a step-by-step manner.

[1] metal surface treatment

Forming a metal layer 30 for processing the surface of a metal film made of a steel material.

In the present invention, it is preferable to use a stainless steel film in the form of a steel as the steel material. The surface of the stainless steel film S is treated by heating and primer coating.

That is, as shown in FIG. 2, the surface treatment of the stainless steel film (S) is performed in a heating zone (Z) within a heating zone (Z) with a stainless steel film having a thickness of 40 to 55 탆, Heated to -80 ° C and transferred into the heating room R, and heat is applied to the heating roll 100 at a temperature of 40 to 80 ° C. Here, the heating zone (Z) and the heating room (R) may refer to a closed space formed by a cover surrounding the stainless steel film (S). Alternatively, if the space in which the whole facility is disposed maintains the temperature, the heating zone Z and the heating room R may be conceptually separated by being open spaces.

At this time, when the heating temperature is set too low, since the thermal conductivity of the stainless steel is low, the heat transfer is not uniformly performed in the heating process, so that the primer coating agent described later is not uniformly applied. On the other hand, when the heating temperature is set too high, since the primer coating agent is water-soluble, the pre-curing phenomenon occurs in a state in which it is not uniformly applied during the gravure coating process, Lt; 0 > C.

At this time, in the heating zone Z, a corona process, a hot air heater, a ceramic heater, a plasma process, an infrared process, and a high-frequency heating process can be selectively performed in the heating method of the stainless steel film S. In contrast, in the heating chamber R, the heating roll 100 directly contacts and heats the stainless steel film S. At this time, the heating roll 100 is disposed below the stainless steel film S to structurally support the stainless steel film S. The heat transferred to the stainless steel film S from the heating roll 100 disposed below the stainless steel film S does not heat only the lower portion of the stainless steel film S. The heat is effectively heated even to the upper portion of the stainless steel film S by the rising property. The heating rolls 100 may be arranged in a plurality. Whereby the stainless steel film S can be effectively supported so as not to be sagged. Further, the heating temperatures of the plurality of heating rolls 100 may be different. For example, the heating temperature of the heating roll 100 may be increased toward the gravure coater 200, so that when the stainless steel film S reaches the gravure coater 200, .

It is not always necessary to heat the stainless steel film S in the heating room R when heating, but it is preferable to heat the stainless steel film S in the heating room to maintain the heating temperature uniformly. In the heating room R, a hot air heater or the like may be installed to properly maintain the air temperature.

The primer coating is performed by coating a primer coating on the surface of the stainless steel film S which has been heat treated by a roll-to-roll method using a gravure coater or a micro gravure coater 200. In this way, As soon as the steel film S passes through the heating section, the primer coating agent is applied. This is because the constitution for drying and the constitution for coating are continuously arranged, so that two processes can be performed in an in-line manner. As a result, the stainless steel film (S) receives the primer coating in a thermally prepared state (without loss of heat received in the heating step), so that the primer coating is uniform and smooth. 3, it can be confirmed that the primer coating agent applied by the gravure coater disposed inline on the metal layer directly heated by contact with the heating roll 100 of the present invention is uniformly dispersed. On the contrary, it can be confirmed that the primer coating agent is not uniformly dispersed in the metal layer which is not directly heated by contact with the metal layer by the heating roll 100 as in the prior art, but is gathered in various places. The uniform distribution of the primer coating agent improves the interlaminar bond strength between the metal layer 30 and the base layer 10 and between the metal layer 30 and the protective layer 40. Thereby, the waiting time between the two processes, the preparation time and the like become unnecessary, and the whole process time can be shortened.

[2] Primary dry laminating: metal layer and protective layer bonding

The protective layer 40 is laminated on the outer side of the metal layer 30 to protect the surface of the metal layer 30 formed in the step [1].

In this step, the PU adhesive resin can be applied to the outer surface of the metal layer 30 with a thickness of 1 to 6 m using a dry laminator. The nylon film and the PET film are successively joined to each other, and the adhesive resin is melted by heating at a temperature of 70 to 90 DEG C to join them together.

The film in which the metal layer 30 and the protective layer 40 are laminated is transferred to the aging chamber and aged for 3 to 31 days.

[3] Secondary dry laminating: metal layer and base layer bonding

In step [2], the base layer 10 is bonded to the inner layer of the metal layer 30 bonded to the protective layer via the adhesive layer 20.

The PP resin constituting the substrate layer 10 has a three-layer structure by a known co-extrusion or dry lamination.

In this step, an adhesive resin obtained by mixing a PP adhesive resin and a modified EP resin as the adhesive layer 20 can be applied to the inner surface of the metal layer to a thickness of 1 to 6 m. The CPP film is bonded thereto and heated at a temperature of 140 to 150 DEG C to melt the adhesive resin, thereby laminating them.

The film in which the metal layer 30 and the base layer 10 are laminated is transferred to the aging chamber and aged for 3 to 31 days.

A cell pouch film according to the present invention is obtained by laminating a base layer and a protective layer on the inside and outside of the metal layer 30 made of the surface-treated stainless steel film as described above.

Test Example

Test 1: Perforation strength test

Puncture strength tests were carried out five times each using a cell pouch (test piece) to which the cell pouch film obtained according to the present invention was applied and a cell pouch (control) to which a general aluminum film was applied, Respectively. For reference, this test was conducted according to JIS Z 1707 standard.

Test section 95.8 Control 22.3

According to Table 1 above, the control punches in the cell pouch when an average force of 22.3 N is applied. On the other hand, it was confirmed that the physical properties of the test group were significantly improved as the puncture occurred when an average force of 95.8 N corresponding to 4 times or more as compared with the control was applied.

Test 2: Electrolyte test

The electrolyte cell resistance test of the battery cell pouch film obtained according to the present invention was carried out, and the results are shown in Table 2 below. The test was conducted at a temperature of 85 ° C for 31 days using a thermo-hygrostat.

Evaluation period One 2 3 4 5 6 Peeling ○ ○ ○ ○ ○ ○ Evaluation period 7 15 20 25 30 31 Peeling ○ ○ ○  ▲  ▲  ▲ ○ peeling off ▲ partial peeling × peeling

According to the above Table 2, the cell pouch made using the pouch film obtained by the present invention showed no delamination even after 20 days passed, gradually peeling at 25 days, It can be seen that complete peeling does not occur. On the other hand, in the case of the cell pouch to which the aluminum film sold on the market was not described in Table 1, complete peeling occurred after 20 days passed.

The battery cell pouch film and the method of manufacturing the battery cell pouch film are not limited to the configuration and operation of the embodiments described above. The above embodiments may be configured so that all or some of the embodiments may be selectively combined to make various modifications.

10: base layer 20: adhesive layer
30: metal layer 40: protective layer
100: heating roll 200: gravure coater

Claims (8)

A base layer formed to surround the battery cell;
An adhesive layer adhered to the base layer to impart an adhesive force;
A metal layer attached to the substrate layer through the adhesive layer to block gas and moisture from entering the substrate layer; And
And a protective layer coupled to the outside of the metal layer to protect the surface of the metal layer,
The metal layer is a film-shaped steel material which is directly contact heated by a heating roll and then subjected to a primer coating treatment,
Wherein the metal layer is formed by direct heating of the steel material by the heating roll and a primer coating process by a roll-to-roll coater in an in-line manner to uniformly coat the primer coating material.
delete The method according to claim 1,
Wherein the steel material comprises stainless steel.
a) a metal surface treatment step of heating a surface of a metal film by directly contacting the heating roll and then coating the primer coating agent uniformly on the surface of the metal film using the heat held by the heated metal film to form a metal layer;
b) a primary dry laminating step of laminating a protective layer made of at least one of a nylon film and a polyester film on the outside of the metal layer, and aging the resultant at a temperature of 70 to 90 캜; And
c) a second dry laminating step of laminating a base material layer made of a polymer resin through an adhesive layer made of a thermally adhesive resin on the inner side of the metal layer, and aging after heating at a temperature of 140 to 180 ° C,
In the step a), the direct contact heating by the heating roll and the primer coating process by a roll-to-roll coater are successively performed on the metal film in an in-line manner to uniformly coat the primer coating agent. .
delete 5. The method of claim 4,
The step a)
And placing the heating roll on the lower side of the metal film so that the heating roll directly heats the metal film while supporting the metal film.
5. The method of claim 4,
The step a)
Wherein a plurality of heating rolls are disposed below the metal film and a temperature of the plurality of heating rolls is controlled such that a heating temperature of a heating roll nearest to the roll- .
5. The method of claim 4,
The step a)
Heating the metal film by a method selected from a corona process, a hot air heater, a ceramic heater, a plasma process, an infrared process, and a high-frequency process to form a heating atmosphere for assisting direct contact heating by the heating roll. (Method for manufacturing battery cell pouch film).

Images