KR102495134B1 - The Apparatus For Venting And The Method For Manufacturing Thereof - Google Patents

Abstract

A venting device according to an embodiment of the present invention for solving the above problems is a venting device inserted into at least one sealing part of a pouch of a secondary battery, wherein a passage communicating the inside and outside of the pouch is formed through, and the sealing part is formed. a body inserted between both sides of the unit, sealed together with the sealing unit, and made of metal having a surface treatment layer formed thereon; and an opening/closing control unit opening and closing the passage according to the internal pressure of the pouch.

Description

Venting device and its manufacturing method {The Apparatus For Venting And The Method For Manufacturing Thereof}

The present invention relates to a venting device and a method for manufacturing the same, and more particularly, to a venting device that is inserted into a sealing part of a pouch of a secondary battery so that when the internal pressure of the pouch increases, internal gas can be discharged to the outside to adjust the pressure. It relates to a venting device and a manufacturing method thereof.

In general, types of secondary batteries include nickel cadmium batteries, nickel hydrogen batteries, lithium ion batteries, and lithium ion polymer batteries. These secondary batteries are used not only for small products such as digital cameras, P-DVDs, MP3Ps, mobile phones, PDAs, portable game devices, power tools, and E-bikes, but also for large products that require high power, such as electric vehicles and hybrid vehicles, and surplus power generation. It is applied and used to a power storage device for storing power or renewable energy and a power storage device for backup.

Secondary batteries are classified into a pouch type and a can type according to the material of a case accommodating the electrode assembly. In the pouch type, an electrode assembly is accommodated in a pouch made of a soft polymer material. And, the can type accommodates the electrode assembly in a case made of a material such as metal or plastic.

On the other hand, secondary batteries are threatened with safety due to various problems such as internal short-circuit caused by external impact, overcharge, overdischarge, etc., and heat caused by this, electrolyte decomposition, and thermal runaway. In particular, when gas is generated due to electrolyte decomposition and the internal pressure of the secondary battery increases, the secondary battery explodes.

Specifically, when the secondary battery is repeatedly charged and discharged, gas is generated due to an electrochemical reaction between the electrolyte and the electrode active material. At this time, the generated gas increases the internal pressure of the secondary battery, causing problems such as weakening of the bonding force between parts, damage to the case of the secondary battery, early operation of the protection circuit, deformation of the electrode, internal short circuit, and explosion. Therefore, in the case of a can-type secondary battery, protection members such as a CID filter and a safety vent are provided to physically cut off the electrical connection when the pressure inside the case increases. However, in the case of a conventional pouch-type secondary battery, such a protective member is not sufficiently provided.

Korean Publication No. 2006-0011046

An object to be solved by the present invention is to provide a venting device that is inserted into at least one sealing part of a pouch of a secondary battery and can adjust the pressure by discharging internal gas to the outside when the internal pressure of the pouch increases, and a manufacturing method thereof. is to do

The tasks of the present invention are not limited to the tasks mentioned above, and other tasks not mentioned will be clearly understood by those skilled in the art from the following description.

A venting device according to an embodiment of the present invention for solving the above problems is a venting device inserted into at least one sealing part of a pouch of a secondary battery, wherein a passage communicating the inside and outside of the pouch is formed through, and the sealing part is formed. a body inserted between both sides of the unit, sealed together with the sealing unit, and made of metal having a surface treatment layer formed thereon; and an opening/closing control unit opening and closing the passage according to the internal pressure of the pouch.

In addition, a polymer layer may be further formed on at least a portion of an outer surface of the body.

In addition, the portion where the polymer layer is formed may include a portion sealed together with the sealing portion.

In addition, the polymer layer may include polypropylene (PP).

Also, the metal may include aluminum or stainless steel.

In addition, the surface treatment layer may include at least one of chromium, zirconium, and titanium.

In order to solve the above problems, a method for manufacturing a venting device according to an embodiment of the present invention is a method for manufacturing a venting device inserted into at least one sealing part of a pouch of a secondary battery, wherein the surface treatment layer is formed on the outer surface of a body made of metal. forming a; and forming a polymer layer on the surface-treated outer surface of the body.

In addition, the forming of the surface treatment layer may include degreasing the body; First washing with water; etching; Performing a second washing step; surface treatment; 3rd washing with water; And drying may be further included.

In addition, the surface treatment may be a step of performing at least one of chromate treatment, zirconia treatment, and titanium treatment.

In addition, the forming of the polymer layer may include contacting a polymer film to the surface-treated outer surface of the body; and fusing the polymer film.

In addition, in the step of contacting the polymer film, a pressure of 0.1 MPa to 0.3 Mpa may be applied for 0.4 seconds to 0.8 seconds under a temperature condition of 110° C. to 130° C.

In addition, the step of fusing the polymer film may be performed under a temperature condition of 140 °C to 220 °C.

In addition, the step of fusing the polymer film may be repeatedly performed at least three times.

In addition, in the step of fusing the polymer film, the final fusing temperature may be the highest.

In addition, the first fusion among the at least three times may be performed under a temperature condition of 150 ° C to 170 ° C.

In addition, the second fusion bonding among the at least three times may be performed at a temperature of 140° C. to 170° C.

In addition, the third fusion among the at least three times may be performed at a temperature of 210° C. to 220° C.

In addition, the polymer film may include polypropylene (PP).

Other specific details of the invention are included in the detailed description and drawings.

According to embodiments of the present invention, at least the following effects are provided.

Since surface treatment is performed on the outer surface of the body of the venting device to form a surface treatment layer, adhesion between the venting device and the sealant layer of the pouch is improved, so that gas inside the pouch can be easily discharged to the outside.

In addition, if the polymer film is further fused to the outer surface of the body to further form a polymer layer, the pouch may maintain insulation without becoming thicker.

Effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the present specification.

1 is an assembly view of a secondary battery including a venting device according to an embodiment of the present invention.
2 is a perspective view of the secondary battery of FIG. 1 that has been manufactured.
3 is a cross-sectional view of a battery case according to an embodiment of the present invention.
4 is a perspective view of a venting device according to an embodiment of the present invention.
5 is a flowchart of a method of manufacturing a venting device according to an embodiment of the present invention.
6 is a cross-sectional view showing a state in which a surface treatment layer is formed on an outer surface of a body of a venting device according to an embodiment of the present invention.
7 is a perspective view showing a state in which a polymer film is fused to the outer surface of a body of a venting device according to an embodiment of the present invention.
8 is a perspective view illustrating a state in which a polymer film is fused to an outer surface of a body of a venting device according to an embodiment of the present invention.
9 is a schematic diagram illustrating a state in which a venting device according to an embodiment of the present invention is inserted into a sealing part of a pouch of a secondary battery.
10 is a schematic diagram illustrating a state in which a venting device according to an embodiment of the present invention is sealed together with a sealing portion of a pouch of a secondary battery.

Advantages and features of the present invention, and methods of achieving them, will become clear with reference to the detailed description of the following embodiments taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments make the disclosure of the present invention complete, and common knowledge in the art to which the present invention belongs. It is provided to completely inform the person who has the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numbers designate like elements throughout the specification.

Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used in a meaning commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in commonly used dictionaries are not interpreted ideally or excessively unless explicitly specifically defined.

Terminology used herein is for describing the embodiments and is not intended to limit the present invention. In this specification, singular forms also include plural forms unless specifically stated otherwise in a phrase. As used herein, "comprises" and/or "comprising" does not exclude the presence or addition of one or more other elements other than the recited elements.

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

1 is an assembled view of a secondary battery 1 including a venting device according to an embodiment of the present invention, and FIG. 2 is a perspective view of the secondary battery 1 of FIG. 1 after manufacturing has been completed.

In order to manufacture the secondary battery 1 according to an embodiment of the present invention, first, a slurry in which an electrode active material, a binder, and a plasticizer are mixed is applied to a positive electrode current collector and a negative electrode current collector to prepare a positive electrode and a negative electrode, and a separator ( Separator) to form an electrode assembly 10 having a predetermined shape. Then, the electrode assembly 10 is accommodated in the battery case 13 and sealed after the electrolyte is injected.

As shown in FIG. 1 , the electrode assembly 10 includes an electrode tab 11 . The electrode tab 11 is connected to the positive electrode and the negative electrode of the electrode assembly 10, respectively, and protrudes out of the electrode assembly 10 to become a path through which electrons can move between the inside and outside of the electrode assembly 10. . The electrode current collector of the electrode assembly 10 is composed of a slurry-coated portion and an end portion to which the slurry is not applied, that is, a plain portion. In addition, the electrode tab 11 may be formed by cutting the uncoated portion or by connecting a separate conductive member to the uncoated portion by ultrasonic welding or the like. As shown in FIG. 1 , the electrode tabs 11 may protrude side by side in the same direction from one side of the electrode assembly 10, but may also protrude in different directions without being limited thereto.

An electrode lead 12 is connected to the electrode tab 11 of the electrode assembly 10 by spot welding or the like. A part of the electrode lead 12 is surrounded by an insulating portion 14 . The insulating part 14 is located and limited to the sealing part 134 where the upper pouch 131 and the lower pouch 132 of the battery case 13 are thermally fused, and the electrode lead 12 is attached to the battery case 13. to adhere In addition, electricity generated from the electrode assembly 10 is prevented from flowing to the battery case 13 through the electrode lead 12 and the sealing of the battery case 13 is maintained. Therefore, the insulator 14 is made of a non-conductive material that does not conduct electricity well. In general, as the insulating portion 14, an insulating tape that is easy to attach to the electrode lead 12 and has a relatively thin thickness is often used, but is not limited thereto, and various members can be used as long as the electrode lead 12 can be insulated. there is.

The electrode leads 12 may extend in the same direction or in opposite directions depending on where the positive electrode tab 111 and the negative electrode tab 112 are formed. The positive lead 121 and the negative lead 122 may have different materials. That is, the positive lead 121 may be made of the same aluminum (Al) material as the positive current collector, and the negative lead 122 may be made of the same copper (Cu) material as the negative current collector or a copper material coated with nickel (Ni). A part of the electrode lead 12 protruding to the outside of the battery case 13 becomes a terminal part and is electrically connected to an external terminal.

In the pouch-type secondary battery 1 according to an embodiment of the present invention, the battery case 13 is a pouch made of a soft material. Hereinafter, the battery case 13 will be described as being a pouch. The battery case 13 accommodates and seals the electrode assembly 10 so that a portion of the electrode lead 12, that is, a terminal portion is exposed. As shown in FIG. 1 , the battery case 13 includes an upper pouch 131 and a lower pouch 132 . In the lower pouch 132, a cup portion 133 having an accommodation space 1331 capable of accommodating the electrode assembly 10 is formed, and the upper pouch 131 has the electrode assembly 10 in the battery case 13. The receiving space 1331 is covered from the top so as not to escape to the outside. At this time, as shown in FIG. 1 , a cup portion 133 having an accommodating space 1331 may be formed in the upper pouch 131 to accommodate the electrode assembly 10 at the upper portion. As shown in FIG. 1 , the upper pouch 131 and the lower pouch 132 may be manufactured by connecting one side to each other, but are not limited thereto and may be manufactured in various ways such as being separated from each other and separately manufactured.

After the upper pouch 131 and the lower pouch 132 of the battery case 13 come into contact with each other, the sealing portion 134 formed on the rim is sealed. At this time, as shown in FIG. 1, according to one embodiment of the present invention, the venting device 15 is inserted between both sides of the sealing part 134 and sealed together, thereby being fixed within the sealing part 134. do. In addition, the venting device 15 includes a passage 153 that communicates the inside and outside of the battery case 13 with each other, and when the internal pressure of the battery case 13 increases, the internal gas is discharged to the outside to adjust the pressure. do. Details of the venting device 15 will be described later.

When the electrode lead 12 is connected to the electrode tab 11 of the electrode assembly 10 and the insulating portion 14 is formed on a portion of the electrode lead 12, the accommodation space 1331 provided in the lower pouch 132 The electrode assembly 10 is accommodated therein, and the upper pouch 131 covers the accommodation space 1331 from the top. Then, when the electrolyte solution is injected into the inside and the sealing parts 134 formed on the edges of the upper pouch 131 and the lower pouch 132 are sealed, the secondary battery 1 is manufactured as shown in FIG. 2 .

3 is a cross-sectional view of a battery case 13 according to an embodiment of the present invention.

The battery case 13 is manufactured by drawing and molding the pouch film 135 . That is, it is manufactured by stretching the pouch film 135 to form the cup portion 133 . As shown in FIG. 3 , the pouch film 135 includes a gas barrier layer 1351, a surface protection layer 1352, and a sealant layer 1353.

The gas barrier layer 1351 secures the mechanical strength of the battery case 13, blocks external gas or moisture from entering the secondary battery 1, and prevents leakage of electrolyte. In general, the gas barrier layer 1351 includes a metal, and an aluminum thin film (Al Foil) is mainly used. Aluminum can secure a mechanical strength of a predetermined level or more, but is light in weight and can secure complementary and heat dissipation properties for the electrochemical properties of the electrode assembly 10 and the electrolyte. However, it is not limited thereto and various materials may be included in the gas barrier layer 1351 . For example, it may be one or a mixture of two or more selected from the group consisting of iron (Fe), carbon (C), chromium (Cr), manganese (Mn), nickel (Ni), and aluminum (Al). At this time, when the gas barrier layer 1351 is made of a material containing iron, mechanical strength is improved, and when made of a material containing aluminum, flexibility is improved, so each characteristic may be considered.

The surface protective layer 1352 is made of a polymer and is located at the outermost layer to protect the secondary battery 1 from external friction and collision and electrically insulate the electrode assembly 10 from the outside. Here, the outermost layer refers to a direction opposite to the direction in which the electrode assembly 10 is located with respect to the gas barrier layer 1351, and refers to a direction toward the outside. The surface protective layer 1352 is polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polypara It may be made of one or more materials selected from the group consisting of phenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber. In particular, a polymer such as nylon resin or polyethylene terephthalate (PET) having wear resistance and heat resistance is mainly used. In addition, the surface protection layer 1352 may have a single film structure made of any one material or a composite film structure formed by forming two or more materials, respectively.

The sealant layer 1353 is made of a polymer and is positioned as the innermost layer to directly contact the electrode assembly 10 . The pouch-type battery case 13 is formed by drawing the pouch film 135 having a laminated structure as described above using a punch or the like, a portion of which is stretched, and a cup portion including a pocket-shaped accommodation space 1333 ( 133) is produced while forming. Then, when the electrode assembly 10 is accommodated in the accommodation space 1333, the electrolyte is injected. After that, when the upper pouch 131 and the lower pouch 132 are brought into contact with each other and thermal compression is applied to the sealing portion 134, the battery case 13 is sealed by bonding the sealant layers 1353 to each other. At this time, since the sealant layer 1353 directly contacts the electrode assembly 10, it must have insulating properties, and since it also contacts the electrolyte, it must have corrosion resistance. In addition, since the inside must be completely sealed to block the movement of materials between the inside and outside, it must have high sealing performance. That is, the sealing portion 134 bonded to each other of the sealant layers 1353 should have excellent thermal bonding strength. In general, the sealant layer 1353 includes polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, poly It may be made of one or more materials selected from the group consisting of paraphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber. In particular, polyolefin-based resins such as polypropylene (PP) or polyethylene (PE) are mainly used. Polypropylene (PP) has excellent mechanical properties such as tensile strength, stiffness, surface hardness, abrasion resistance, heat resistance, and chemical properties such as corrosion resistance, and is mainly used to manufacture the sealant layer 1353. Furthermore, it may be composed of unstretched polypropylene (Cated Polypropylene) or a polypropylene-butylene-ethylene terpolymer. In addition, the sealant layer 1353 may have a single film structure made of one material or a composite film structure formed of two or more materials each layered.

4 is a perspective view of a venting device 15 according to an embodiment of the present invention.

As described above, the secondary battery 1 according to an embodiment of the present invention further includes at least one venting device 15 . At least one venting device 15 is inserted into the sealing part 134 of the pouch of the secondary battery 1, and controls the pressure by discharging internal gas to the outside when the internal pressure of the pouch increases. To this end, the venting device 15 has a passage 153 that communicates the inside and outside of the pouch, is inserted between both sides of the sealing part 134, and is sealed together with the sealing part 134, a body 151 made of metal having a surface treatment layer 1511 formed thereon; and an opening/closing controller 152 opening/closing the passage 153 according to the internal pressure of the pouch. In addition, a polymer layer 154 may be further formed on at least a part of the outer surface of the body 151 .

The opening and closing control unit 152 controls the internal pressure by opening and closing the passage 153 according to the internal pressure of the pouch. Specifically, before the internal pressure of the pouch reaches a specific pressure, the opening/closing controller 152 closes the passage 153 by being in close contact with the exit sheet of the passage 153 . However, when the internal pressure of the pouch increases and reaches a specific pressure, the opening/closing controller 152 is detached from the exit sheet of the passage 153 and opens the passage 153 . By doing so, the gas inside the pouch can be released to the outside. Meanwhile, when the internal pressure of the pouch decreases again as the gas inside the pouch is released to the outside, the opening/closing controller 152 returns to the original position and closes the passage 153 . At this time, although not shown in the drawings, an elastic body that generates a restoring force to return the opening and closing control unit 152 to its original position, for example, a spring may be further included.

The body 151 may be made of metal, and in particular, may include aluminum (Al) or stainless steel (STS). At this time, as described above, since the body 151 is inserted between both surfaces of the sealing portion 134 and sealed together, it is fused with the inner surface of the sealing portion 134. However, the inner surface of the sealing part 134 is the sealant layer 1353, which is the innermost layer of the pouch film 135, and is made of a polymer, particularly polypropylene (PP). Accordingly, since the body 151 made of metal and the sealant layer 1353 made of polymer are different from each other, adhesion may be deteriorated. Therefore, the venting device 15 may separate from the sealing portion 134 and the sealing may be destroyed even before the internal pressure of the pouch reaches a specific pressure and the internal gas is released to the outside.

5 is a flowchart of a method of manufacturing a venting device 15 according to an embodiment of the present invention.

In order to solve the above problem, in the venting device 15 according to an embodiment of the present invention, a surface treatment layer 1511 is further formed on the outer surface of the body 151 . As a result, the adhesion between the venting device 15 and the inner surface of the sealing portion 134 is improved, thereby solving the problem of the venting device 15 separating from the sealing portion 134 before the internal pressure of the pouch reaches a specific pressure. It can be prevented.

To this end, the venting device 15 according to an embodiment of the present invention includes forming a surface treatment layer 1511 on an outer surface of a body 151 made of metal; and forming a polymer layer 154 on the surface-treated outer surface of the body 151.

Hereinafter, each step shown in the flowchart of FIG. 5 will be described with reference to FIGS. 6 to 8.

6 is a cross-sectional view showing a surface treatment layer 1511 formed on the outer surface of the body 151 of the venting device 15 according to an embodiment of the present invention.

In order to form the surface treatment layer 1511 on the outer surface of the body 151, the body 151 is first degreased (S501). In order to manufacture the body 151, various metal processing processes such as cutting, rolling, and injection may be performed. At this time, in order to reduce friction between the body 151 and a metal processing device, the outer surface of the body 151 Lubricating oil is applied. Therefore, when manufacturing of the body 151 is completed, the lubricating oil or dust and other impurities may exist on the outer surface of the body 151 . The degreasing process removes such lubricating oil or dust and other impurities so that the outer surface of the body 151 can be treated more efficiently.

After the degreasing process, the solution used for degreasing is washed by first washing with water (S502). Here, water washing is a process of washing and washing with water. At this time, it is preferable that the water is distilled water in which impurities are not dissolved in order to prevent adhesion of other impurities dissolved in the water while washing with water.

When metal is left in the air, it can oxidize to some extent and form oxidizing substances. In particular, if the body 151 is made of aluminum, an aluminum oxide film may be formed on the outer surface of the body 151. Therefore, an oxidized material formed on the outer surface of the body 151 is removed by etching (S503).

After the etching process, a second washing with water (S504) is performed to wash the solution used for etching. Then, surface treatment (S505) is performed on the outer surface of the body 151. Surface treatment is a process of changing the physical properties of a metal, such as improving corrosion resistance or wear resistance, by chemically treating the surface of a metal such as aluminum. Such surface treatment includes anodizing, chemical conversion coating treatment, and electroplating.

According to one embodiment of the present invention, the surface treatment may be a chromate treatment using chromium. Chromate treatment is a type of chemical conversion coating treatment, in which a thin film of insoluble chromate (chromate) containing chromium is formed on the surface of a metal. To this end, the body 151 is immersed in an aqueous solution containing chromium ions. Then, chromium ions undergo an oxidation reaction to generate insoluble chromium oxide on the outer surface of the body 151, thereby forming a chromate film. That is, according to an embodiment of the present invention, the surface treatment layer 1511 may be a chromate film containing chromium. Here, the chromium ion is not limited to a hexavalent ion or a trivalent ion, and may be various types of ions. And, as the aqueous solution containing chromium ions, various substances may be used without limitation, such as chromic anhydride, chromium nitrate, chromium sulfate, chromium acetate, and chromium chloride.

Meanwhile, surface treatment according to another embodiment of the present invention may be a non-chromate treatment using a material other than chromium. Here, the non-chromium material may be, for example, zirconium. If zirconia treatment is performed using zirconium, the body 151 is immersed in an aqueous solution containing zirconium ions. Then, zirconium ions undergo an oxidation reaction to generate zirconium oxide on the outer surface of the body 151, thereby forming a zirconia film. The non-chromate treatment is not limited thereto, and may include titanium treatment using titanium. That is, according to another embodiment of the present invention, the surface treatment layer 1511 may be a zirconia film containing zirconium or a titanium film containing titanium.

After the surface treatment (S505) process, the solution used for the surface treatment is washed by washing with water (S506) for the third time. And by drying (S507) the body 151, as shown in FIG. 6, a surface treatment layer 1511 is formed on the outer surface of the body 151, and an untreated layer 1512 is not surface-treated inside. ) remains as In this way, since the surface treatment layer 1511 is formed on the outer surface of the body 151, it is possible to secure corrosion resistance as well as fusion property in which a material of a polymer material can be well fused to the surface.

7 is a perspective view showing a state in which a polymer film 2 is fused to the outer surface of the body 151 of the venting device 15 according to an embodiment of the present invention, and FIG. 8 is a perspective view according to an embodiment of the present invention. It is a perspective view showing a state in which the polymer film 2 is fused to the outer surface of the body 151 of the venting device 15.

With only the surface treatment layer 1511 formed on the outer surface of the body 151 , the venting device 15 may be inserted into the sealing portion 134 of the pouch and sealed together with the sealing portion 134 . By doing so, the outer surface of the body 151 itself can be fused with the inner surface of the sealing part 134 .

However, the inner surface of the sealing part 134, that is, the sealant layer 1353 may be damaged due to the volume of the body 151 itself while performing the sealing. Then, the gas barrier layer of the pouch film 135 may come into contact with the body 151, causing insulation to be destroyed. If the thickness of the sealant layer 1353 is made thick in order to solve this problem, there is a problem in that the entire thickness of the pouch becomes thick.

Therefore, according to one embodiment of the present invention, as shown in FIG. 7 , the polymer film 2 is attached to at least a part of the outer surface of the body 151 on which the surface treatment layer 1511 is formed (S508). That is, before fusing the polymer film 2, the polymer film 2 is temporarily attached to the outer surface of the body 151. Thus, even when the body 151 moves along the process line, the polymer film 2 may not move from the outer surface of the body 151 . The process of attaching the polymer film 2 may be performed by applying a pressure of 0.1 MPa to 0.3 Mpa for 0.4 seconds to 0.8 seconds under a temperature condition of 110° C. to 130° C. Since tack welding is simply a process of temporarily attaching, it must be easily detached in order to perform a fusion process later. Therefore, if tack welding is performed at a temperature higher than 130° C., there is a problem of stronger adhesion. And, if tack welding is performed at a temperature lower than 110° C., there is a problem in that adhesion is not properly performed.

Then, by applying heat and pressure for a certain period of time, the polymer film 2 is fused (S509). Thus, as shown in FIG. 8 , a polymer layer 154 may be further formed on at least a part of the outer surface of the body 151 . Here, the portion where the polymer layer 154 is formed includes a portion that is sealed when the body 151 is inserted into the sealing portion 134 and sealed together. Thus, the polymer layer 154 of the venting device 15 is sealed together, and the adhesion between the venting device 15 and the inner surface of the sealing portion 134 may be improved. This fusion process may be performed under a temperature condition of 140 °C to 220 °C. In general, if the temperature is lower than 140° C., the polymer film 2, particularly the film containing polypropylene, may not be sufficiently melted, resulting in deterioration in adhesion. And, if the temperature is higher than 220° C., the polymer film 2 may be excessively melted and greatly deformed.

In addition, the process of fusing the polymer film 2 may be performed only once, or may be repeatedly performed a plurality of times. If performed repeatedly three times, the first fusion is to remove air bubbles between the outer surface of the body 151 and the polymer film 2, and the temperature condition is 150 ° C to 170 ° C, preferably 155 ° C to 165 ° C Under, it may be performed by applying a pressure of 0.1 MPa to 0.3 MPa for 2 seconds to 4 seconds. Since the first fusion is the first fusion, it is preferable to perform it at a temperature at least 10° C. higher than 140° C., which is the temperature of the lowest condition, in order to further improve the fusion. In addition, if the fusion temperature is excessively high in the state where the polymer film 2 is bonded to the outer surface of the body 151, it is not easy to converge when fusion is performed at the wrong location, so it is preferably less than 170°C. And, the second fusion is to secure airtightness between the outer surface of the body 151 and the polymer film 2, and under a temperature condition of 140 ° C to 170 ° C, preferably 145 ° C to 155 ° C, 0.1 MPa to 0.3 It may be performed by applying a pressure of MPa for 2 to 4 seconds. Since the second fusion is only for securing airtightness, it can be fused again at a temperature similar to that of the first fusion. At this time, since the second fusion is not the first fusion, it can be performed at a temperature greater than 140° C., which is the temperature of the minimum condition. And the third round of fusion performed at the very end is to enhance the fusion property of the polymer film 2, under a temperature condition of 210°C to 220°C, preferably 215°C to 220°C, and a pressure of 0.1 MPa to 0.3 MPa. It may be performed by applying for 2 to 4 seconds. That is, it is preferable that the temperature of the third fusion welding performed last is the highest. However, as described above, if the temperature is higher than 220° C., the polymer film 2 may be excessively melted and greatly deformed. Also, if the temperature is lower than 210° C., the adhesiveness may not be greatly enhanced compared to the adhesiveness after the second fusion.

9 is a schematic diagram showing a state in which the venting device 15 according to an embodiment of the present invention is inserted into the sealing portion 134 of the pouch of the secondary battery 1, and FIG. 10 is a view according to an embodiment of the present invention. It is a schematic diagram showing a state in which the venting device 15 is sealed together with the sealing portion 134 of the pouch of the secondary battery 1 .

As shown in FIG. 9, after the venting device 15 according to an embodiment of the present invention manufactured according to the above method is inserted between both sides of the sealing part 134, as shown in FIG. It can be sealed by applying heat and pressure. This sealing may be performed by applying a pressure of 0.1 MPa to 0.3 MPa for 2 seconds to 4 seconds under a temperature condition of 170°C to 190°C, preferably 175°C to 185°C. In this way, the secondary battery 1 according to an embodiment of the present invention can be manufactured.

Meanwhile, the polymer film 2 preferably includes the same polymer as the sealant layer 1353, which is the innermost layer of the pouch film 135. That is, if the sealant layer 1353 is made of polypropylene (PP), it is preferable that the polymer film 2 also includes polypropylene (PP). In particular, in order to improve adhesion with the body 151, an acid-treated polyolefin-based polymer may be included. For example, acid-treated polypropylene may be mixed with normal polypropylene, acid-treated polyethylene may be mixed, or acid-treated polypropylene may be simply used. Here, the acid-treated polypropylene may be MAH PP (maleic anhydride polypropylene). As a result, when the venting device 15 is inserted into the sealing portion 134 of the pouch and sealed together, the polymer layer 154 formed on the outer surface of the body 151 is not heterogeneous with the inner surface of the pouch, so that the adhesiveness is improved. can be further improved. In particular, when heat and pressure are applied during sealing, a portion of the polymer film 2 and a portion of the sealant layer 1353 may be melted. At this time, since the polymer film 2 and the sealant layer 1353 are made of the same material, the melted portion solidifies as the temperature drops again, so that the boundary between the polymer film 2 and the sealant layer 1353 is ambiguous. and adhesion may be further improved, and furthermore, as shown in FIG. 10, it may be formed as a single member. In this way, manufacturing of the venting device 15 according to an embodiment of the present invention is completed.

In the venting device 15 of the present invention manufactured through the above method, a passage 153 communicating the inside and outside of the pouch is formed through, and is inserted between both sides of the sealing part 134 to seal the A body 151 sealed with the portion 134 and made of metal having a surface treatment layer 1511 formed thereon; and an opening/closing controller 152 that opens and closes the passage 153 according to the internal pressure of the pouch, and at least one is inserted into the sealing portion 134 of the pouch of the secondary battery 1 . In addition, a polymer layer 154 may be further formed on at least a part of an outer surface of the body 151 .

In the venting device 15 of the present invention, surface treatment is performed on the outer surface of the body 151 to form the surface treatment layer 1511, so that the adhesion to the sealant layer 1353 of the pouch is improved to release gas inside the pouch. It can be easily discharged to the outside.

Further, if the polymer layer 154 is further formed by further fusing the polymer film 2, the pouch may maintain insulation without becoming thicker.

manufacturing example One

A body with a diameter of 5 mm and a height of 10 mm made _of aluminum (Al) is immersed for ₃₀ seconds under a temperature condition of 45 ° C. It was degreased. And after first washing with distilled water at 25℃ for 15 seconds, a solution of 200ml of sulfuric acid (H ₂ SO ₄ ), 200ml of ammonium fluoride (NH ₄ F), 200ml of Hexamine (C ₆ H ₁₂ N ₄ ) and 1L of distilled water was mixed. , The body was etched by dipping for 50 seconds under a temperature condition of 35°C. And after washing the second time with distilled water at 25℃ for 15 seconds, chromic anhydride (CrO ₃ ) 5%, bonfluoric acid (HBF ₄ ) 0.7%, zirconic hydrofluoric acid (Hexafluorozirconic acid, H ₂ ZrF ₆ ) 4.3% and H ₂ In a solution mixed with O (90%), the body was immersed for 1 minute under a temperature condition of 30 ° C. to treat the surface (chromate treatment). And after washing with distilled water at 25 ° C. for 10 seconds and distilled water at 45 ° C. for 5 seconds 3 times, drying was performed at 85 ° C. for 20 seconds and at 135 ° C. for 15 seconds.

Thereafter, under a temperature condition of 120° C., a 100 μm thick polymer film made of polypropylene (PP) was bonded by applying a pressure of 0.2 MPa for 0.6 seconds. And, under a temperature condition of 160 ° C, a pressure of 0.2 MPa was applied for 3 seconds to perform the first fusion, and under a temperature condition of 150 ° C, a pressure of 0.2 MPa was applied for 3 seconds to perform a second fusion, 220 ° C Under a temperature condition of , fusion was performed three times by applying a pressure of 0.2 MPa for 3 seconds.

manufacturing example 2

In the surface treatment step, the same method as in Preparation Example 1, except that the body was immersed in a mixture of 3H ₂ ZrF _{6 ,} 4H ₃ PO ₄ , and Resin Binder to treat the surface (non-chromate treatment). A venting device was prepared.

comparative example One

A venting device was manufactured in the same manner as in Preparation Example 1, except that no surface treatment was performed.

Physical properties of the venting devices manufactured in Preparation Example 1, Preparation Example 2, and Comparative Example 1 were measured in the following manner, and the measurement results are shown in Table 1 below.

Physical property measurement method

One. peel strength ( of the body Exterior and polymer of film adhesiveness )

The venting devices manufactured by Preparation Example 1, Preparation Example 2, and Comparative Example 1 were prepared by mixing 250 ml of electrolyte (lithium salt 　LiPF6 1 M, and ethylene carbonate (EC): ethylmethyl carbonate (EMC): dimethyl carbonate (DMC), respectively). prepared by melting at a ratio of 3: 3: 4). And after storage for 24 hours under a temperature condition of 80 ° C., each venting device was taken out and the electrolyte solution was removed. A cut is made in the polymer film fused to the outer surface of the body, and a part of the polymer film is peeled off to expose a part of the body. A portion of the peeled polymer film is fixed to an upper jig of a Universal Testing Machine (UTM), and the remaining portion of the venting device is fixed to a lower jig. Then, at a speed of 50 mm/min, the force required to peel the sealant layer and the gas barrier layer was measured, and this force was evaluated as peel strength.

2. sealing strength ( venting of the device polymer of film and pouch of sealant layer adhesiveness )

After manufacturing the venting devices of Preparation Example 1, Preparation Example 2, and Comparative Example 1, the venting devices were inserted into the sealing part of a pouch type secondary battery having a width of 55 mm, a width of 110 mm, and a height of 7 mm. Then, under a temperature condition of 180° C., a pressure of 0.2 MPa was applied for 3 seconds to seal with the sealing portion. In this way, each secondary battery was manufactured.

Thereafter, a region in which each venting device is sealed in the secondary battery is cut and sampled. Then, the pouch piece of the secondary battery is fixed to an upper jig of a universal testing machine (UTM), and a venting device is fixed to a lower jig. Then, at a speed of 50 mm/min, the force required to detach the pouch and the venting device was measured, and this force was evaluated as sealing strength.

[Table 1]

As shown in Table 1, the peel strength of the venting device of Preparation Example 1 was measured to be 10 N/cm. And, the peel strength of the venting device of Preparation Example 2 was measured to be 5 to 6 N/cm. On the other hand, since the venting device of Comparative Example 1 did not perform surface treatment on the outer surface of the body, the peel strength was not high enough to measure the peel strength by the above method. Therefore, since the venting devices of Manufacturing Examples 1 and 2 require a greater force to separate the outer surface of the body and the polymer film than the venting device of Comparative Example 1, the adhesion between the outer surface of the body and the polymer film is better. know the facts

In addition, the venting device of Preparation Example 1 had a sealing strength of 80 N/cm, the venting device of Preparation Example 2 had a sealing strength of 60 N/cm, and the venting device of Comparative Example 1 had a sealing strength of 30 N/cm. Accordingly, it can be seen that the venting devices of Preparation Examples 1 and 2 have better adhesion between the polymer film and the sealant layer of the pouch than the venting device of Comparative Example 1.

Those skilled in the art to which the present invention pertains will understand that the present invention can be embodied in other specific forms without changing its technical spirit or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. The scope of the present invention is indicated by the claims to be described later rather than the detailed description above, and various embodiments derived from the meaning and scope of the claims and equivalent concepts thereof should be construed as being included in the scope of the present invention.

1: secondary battery 2: polymer film
10: electrode assembly 11: electrode tab
12: electrode lead 13: battery case
14: insulator 15: venting device
111 positive tab 112 negative tab
121: positive lead 122: negative lead
131: upper pouch 132: lower pouch
133: cup part 134: sealing part
135: pouch film 151: body
152: opening and closing control unit 153: passage
154: polymer layer 1331: accommodation space
1351 gas barrier layer 1352 surface protective layer
1353: sealant layer 1511: surface treatment layer
1512: untreated layer

Claims (18)

In the venting device inserted into at least one sealing part of a pouch of a secondary battery,
a body made of metal having a passage communicating with the inside and outside of the pouch, being inserted between both sides of the sealing part and being sealed together with the sealing part, and having a surface treatment layer formed on an outer surface of the pouch; and
An opening and closing control unit for opening and closing the passage according to the internal pressure of the pouch,
the body,
A polymer layer is further formed on at least a part of the outer surface,
The polymer layer,
A venting device comprising the same polymer as the sealant layer, which is the innermost layer of the pouch. delete According to claim 1,
The part where the polymer layer is formed,
A venting device comprising a portion sealed together with the sealing portion. According to claim 1,
The polymer layer,
A venting device comprising polypropylene (PP). According to claim 1,
the metal,
A venting device comprising aluminum or stainless steel. According to claim 1,
The surface treatment layer,
A venting device comprising at least one of chromium, zirconium and titanium. A method of manufacturing a venting device inserted into at least one sealing portion of a pouch of a secondary battery,
Forming a surface treatment layer on the outer surface of the body made of metal; and
Forming a polymer layer on the outer surface of the body on which the surface treatment layer is formed,
Forming the polymer layer,
contacting a polymer film to the outer surface of the body on which the surface treatment layer is formed; and
Including the step of fusing the polymer film,
The polymer film,
A method of manufacturing a venting device comprising the same polymer as the sealant layer, which is the innermost layer of the pouch. According to claim 7,
Forming the surface treatment layer,
degreasing the body;
First washing with water;
etching;
Performing a second washing step;
surface treatment;
3rd washing with water; and
A method of manufacturing a venting device, further comprising drying. According to claim 8,
In the surface treatment step,
A step of performing at least one of chromate treatment, zirconia treatment, and titanium treatment, a method for manufacturing a venting device. delete According to claim 7,
In the step of attaching the polymer film,
A method for manufacturing a venting device, wherein a pressure of 0.1 MPa to 0.3 Mpa is applied for 0.4 seconds to 0.8 seconds under a temperature condition of 110° C. to 130° C. According to claim 7,
The step of fusing the polymer film,
A method for manufacturing a venting device, which is performed under a temperature condition of 140 ° C to 220 ° C. According to claim 7,
The step of fusing the polymer film,
A method for manufacturing a venting device, which is repeated at least three times. According to claim 13,
The step of fusing the polymer film,
A method of manufacturing a venting device in which the temperature of the last fusion is the highest. According to claim 14,
The first fusion of the at least three times,
A method for manufacturing a venting device, which is performed under a temperature condition of 150 ° C to 170 ° C. According to claim 15,
The second fusion of the at least three times,
A method for manufacturing a venting device, which is performed at a temperature of 140 ° C to 170 ° C. According to claim 14,
The third fusion of the at least three times,
A method for manufacturing a venting device, which is performed at a temperature of 210 ° C to 220 ° C. According to claim 7,
The polymer film,
A method of manufacturing a venting device comprising polypropylene (PP).

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