KR20200001052A - The Apparatus And The Method For Venting And The Secondary Battery - Google Patents

Abstract

An objective of the present invention is to provide a venting device capable of adjusting the pressure by discharging a gas to the outside when the internal pressure of a pouch is increased. According to an embodiment of the present invention for solving the objective, the venting device inserted into a sealing unit of a pouch of a secondary battery comprises: a housing inserted into a gap between both surfaces of a sealing unit, sealed with the sealing unit, and having a path communicating the inside with the outside of the pouch through the housing; and a sealing film fusing the housing and sealing unit each other. The sealing film includes a first fusing unit fused to an outer surface of the housing, a second fusing unit having both surfaces fused to each other while closing an entrance of the path formed at end of the housing, and a nonfusing unit formed at one end toward the pouch and having both surfaces not fused to each other.

Description

Venting device, venting method and secondary battery {The Apparatus And The Method For Venting And The Secondary Battery}

The present invention relates to a venting apparatus, a venting method, and a secondary battery, and more particularly, is inserted into at least one sealing portion of a pouch of a secondary battery, and when the internal pressure of the pouch increases, the internal gas is discharged to the outside to adjust the pressure. It relates to a venting device, a venting method and a secondary battery that can be.

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

Secondary batteries are classified into a pouch type and a can type according to the material of a case accommodating the electrode assembly. The pouch type houses the electrode assembly in a pouch made of soft polymer material. In addition, the can type (Can Type) accommodates the electrode assembly in a case made of a material such as metal or plastic.

On the other hand, the secondary battery may generate gas due to internal short circuit, overcharge, overdischarge due to external shock. Alternatively, when stored or stored at a high temperature, a high temperature may accelerate the electrochemical reaction of the electrolyte and the electrode active material to generate gas.

At this time, the generated gas raises the internal pressure of the secondary battery, causing problems such as weakening of the bonding force between components, case breakage of the secondary battery, premature operation of the protection circuit, deformation of the electrode, internal short circuit, and explosion. In order to prevent this, in the case of a can type secondary battery, a protective member such as a CID filter and a safety vent is provided. Therefore, when the pressure inside the case increases, the electrical connection is physically blocked. However, in the case of the conventional pouch type secondary battery, such a protection member was not fully provided.

Korean Laid-Open Publication No. 2005-0010001

The problem to be solved by the present invention is a venting device, a venting method and a secondary battery that is inserted into at least one of the sealing portion of the pouch of the secondary battery, the internal pressure of the pouch to increase the pressure by discharging the gas inside to the outside To provide.

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

Venting apparatus according to an embodiment of the present invention for solving the above problems is inserted into the sealing portion of the pouch of the secondary battery, inserted between both sides of the sealing portion is sealed with the sealing portion, the pouch A housing through which a passage communicating with the inside and outside of the housing is formed; And a sealing film for fusion bonding the housing and the sealing portion, wherein the sealing film comprises: a first fusion portion fused to an outer surface of the housing; A second welding part of which both surfaces are fused to each other while closing an inlet of the passage formed at an end of the housing; And an unfused portion formed at one end facing the pouch so that both surfaces thereof are not fused to each other.

In addition, the sealing film, at least a portion of the outer surface of the unfused portion may be fused to both surfaces of the sealing portion, respectively.

In addition, the sealing film, the entire outer surface of the unfused portion may be fused on both sides of the sealing portion, respectively.

In addition, the sheet is formed inside the housing, made of a polymer, the passage is formed through; A ball for contacting or spaced apart from the seat and opening and closing the passage at an outlet side of the passage; And it is formed surrounding the seat and the ball, and has an elastic force to open and close the passage in accordance with the internal pressure of the pouch, it may further comprise a leaf spring made of metal.

In addition, the seat, the inner peripheral edge of the exit side surface of the passage may be chamfered or fillet to face the ball.

In addition, the seat, the outer peripheral edge of the exit side surface of the passage may be chamfered or filleted.

In addition, the leaf spring has a cap shape in which one side is convex outward, and an insertion space into which the sheet and the ball are inserted may be formed therein.

In addition, the leaf spring may be bent toward the seat, the other end is inserted into the insertion space.

In addition, the leaf spring, the center formed in the center; And a periphery extending in an outward direction from the center, and the gas exhaust hole may be perforated in the periphery.

In addition, the housing may include an upper housing and a lower housing different in shape or size from each other.

In addition, the lower housing may have a width smaller than the width of the upper housing.

The upper housing may have a circular cylinder shape, and the lower housing may have an elliptical cylinder shape.

In addition, the sealing film may be formed in the lower housing.

Venting method according to an embodiment of the present invention for solving the above problems is the gas generated inside the pouch of the secondary battery, the step of increasing the internal pressure of the pouch; In a sealing film formed at one end of the venting device inserted into the sealing part of the pouch, a fusion part of which both surfaces are fused to each other while closing the inlet of the passage formed at the end of the housing of the venting device; The internal pressure of the pouch exceeds a certain pressure; A step of detaching the welded portion from the unbonded portion formed at one end of the sealing film facing the pouch and not fused to each other; Introducing the gas into an inlet of the passage; The gas pushing out the ball of the venting device; Opening the exit of the passageway as the ball is pushed; And discharging the gas to the outside through the passage.

A secondary battery according to an embodiment of the present invention for solving the above problems is a pouch for receiving an electrode assembly formed by stacking a positive electrode and a negative electrode on both sides of the separator therein; And a venting device inserted into the sealing part of the pouch, wherein the venting device is inserted between both sides of the sealing part to be sealed together with the sealing part, and a passage communicating with the inside and the outside of the pouch is formed through. housing; And a sealing film for fusion bonding the housing and the sealing portion, wherein the sealing film comprises: a first fusion portion fused to an outer surface of the housing; A second welding part of which both surfaces are fused to each other while closing an inlet of the passage formed at an end of the housing; And an unfused portion formed at one end facing the pouch so that both surfaces thereof are not fused to each other.

In addition, the sealing film, at least a portion of the outer surface of the unfused portion may be fused to both surfaces of the sealing portion, respectively.

In addition, the sealing film, the entire outer surface of the unfused portion may be fused on both sides of the sealing portion, respectively.

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

According to embodiments of the present invention has at least the following effects.

At least one venting device is inserted into the sealing portion of the pouch of the secondary battery, and when the internal pressure of the pouch increases, the internal gas may be discharged to the outside to adjust the pressure.

In addition, since both surfaces of the sealing film are fused to each other, the inlet of the passage of the venting device may be closed to prevent penetration of moisture or other foreign matter from the outside.

The 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 rechargeable battery of FIG.
3 is a partial cross-sectional view of a battery case according to an exemplary embodiment of the present invention.
4 is a perspective view of a venting device in which the sealing film does not close the end of the housing in which the inlet of the passage is formed.
5 is a perspective view showing a state in which the venting device of FIG. 4 is inserted between both surfaces of the sealing part.
6 is a perspective view of a venting device according to an embodiment of the present invention.
7 is a perspective view showing a state in which the venting device is inserted between both sides of the sealing portion according to an embodiment of the present invention.
Figure 8 is a side cross-sectional view of the venting device according to an embodiment of the present invention.
Figure 9 is a side cross-sectional view showing a state in which the venting device is inserted between both sides of the sealing portion according to an embodiment of the present invention.
FIG. 10 is a side cross-sectional view illustrating a distance between two sides of the pouch due to an increase in internal pressure of the pouch according to an exemplary embodiment of the present invention.
11 is a side cross-sectional view showing a state in which the sealing film is detached from each other in accordance with an embodiment of the present invention to open the passage.
12 is a side sectional view showing a vent device inserted between both surfaces of a sealing part according to another exemplary embodiment of the present invention.
FIG. 13 is a side cross-sectional view illustrating a distance between two sides of the pouch due to an increase in internal pressure of the pouch according to another exemplary embodiment of the present invention.

Advantages and features of the present invention, and methods for achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and the general knowledge in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used in a sense that can be commonly understood by those skilled in the art. In addition, the terms defined in the commonly used dictionaries are not ideally or excessively interpreted unless they are specifically defined clearly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In this specification, the singular also includes the plural unless specifically stated otherwise in the phrase. As used herein, "comprises" and / or "comprising" does not exclude the presence or addition of one or more other components in addition to the mentioned components.

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

1 is an assembly view of a secondary battery 1 including a venting device according to an embodiment of the present invention, Figure 2 is a perspective view of the secondary battery 1 of Figure 1 is completed.

In order to manufacture the secondary battery 1 according to an embodiment of the present invention, first, an electrode active material slurry is applied to a positive electrode current collector and a negative electrode current collector to prepare a positive electrode and a negative electrode, and stacked on both sides of a separator. As a result, the electrode assembly 10 having a predetermined shape is formed. Then, the electrode assembly 10 is accommodated in the battery case 13 and the electrolyte is injected and then sealed.

The electrode assembly 10 includes an electrode tab 11, as shown in FIG. 1. 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 the outside of the electrode assembly 10. . The electrode current collector of the electrode assembly 10 is composed of a portion to which the slurry is applied and a terminal 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 an additional 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 are not limited thereto and may protrude in different directions.

Electrode leads 12 are connected to electrode tabs 11 of the electrode assembly 10 by spot welding. A part of the electrode lead 12 is surrounded by the insulating portion 14. The insulating part 14 is positioned to be limited to the sealing part 134 in which the upper pouch 131 and the lower pouch 132 of the battery case 13 are heat-sealed, and the electrode lead 12 is placed on the battery case 13. Glue. Then, the 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, this insulation portion 14 is made of a non-conductive non-conductor that is not very good electricity. In general, the insulating part 14 may be easily attached to the electrode lead 12 and a relatively thin insulating tape is used, but various members may be used as long as the insulating lead 14 may be insulated. have.

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

In the pouch type secondary battery 1 according to the exemplary 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 part of the electrode lead 12, that is, the terminal part, is exposed. As shown in FIG. 1, the battery case 13 includes an upper pouch 131 and a lower pouch 132. The lower pouch 132 is formed with a cup part 133 provided with an accommodating space 1331 for accommodating the electrode assembly 10, and the upper pouch 131 has the electrode assembly 10 of the battery case 13. The accommodation space 1331 is covered from the top so as not to be separated to the outside. In this case, as illustrated in FIG. 1, the cup part 133 having the accommodation space 1331 is formed in the upper pouch 131, and the electrode assembly 10 may be accommodated therein. As illustrated in FIG. 1, the upper pouch 131 and the lower pouch 132 may be manufactured by being connected to each other, but are not limited thereto and may be manufactured separately from each other.

After the upper pouch 131 and the lower pouch 132 of the battery case 13 contact each other, the sealing part 134 formed at the edge is sealed. At this time, as shown in Figure 1, according to an embodiment of the present invention, the venting device 15 is inserted between both sides of the sealing portion 134 and sealed together, thereby fixing in the sealing portion 134 do. In addition, the venting device 15 includes a passage 154 that communicates the inside and the outside of the battery case 13, 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 in a portion of the electrode lead 12, the accommodation space 1331 provided in the lower pouch 132 is provided. The electrode assembly 10 is accommodated therein, and an upper pouch 131 covers the accommodation space 1331 at the top. In addition, when the electrolyte is injected into the inside and the sealing part 134 formed at the edges of the upper pouch 131 and the lower pouch 132 is sealed, the secondary battery 1 is manufactured as shown in FIG. 2.

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

The battery case 13 is manufactured by drawing a pouch film 135. In other words, the pouch film 135 is stretched 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 the entry of gas or moisture outside the secondary battery 1, and prevents leakage of the electrolyte solution. 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 more than a predetermined level while being light in weight, and can secure complementary and heat dissipating properties such as electrochemical properties by the electrode assembly 10 and the electrolyte. However, the present invention 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). In this case, when the gas barrier layer 1351 is made of a material containing iron, mechanical strength is improved, and when the material containing aluminum is improved, flexibility may be used in consideration of respective characteristics.

The surface protective layer 1352 is made of a polymer and is positioned at the outermost layer to electrically insulate the electrode assembly 10 from the outside, while protecting the secondary battery 1 from friction and collision with the outside. Here, the outermost layer refers to a direction toward the outside in a direction opposite to the direction in which the electrode assembly 10 is positioned with respect to the gas barrier layer 1351. The surface protective layer 1352 is made of 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 phenylene benzobisoxazole, polyarylate, teflon, and glass fibers. In particular, a polymer such as nylon (Nylon) resin or polyethylene terephthalate (PET) having mainly wear resistance and heat resistance is used. The surface protective layer 1352 may have a single film structure made of any one material, or may have a composite film structure in which two or more materials are formed in layers.

The sealant layer 1353 is made of a polymer and is located in the innermost layer to make direct contact with the electrode assembly 10. When the pouch-type battery case 13 is formed by drawing the pouch film 135 having the laminated structure as described above using a punch or the like, a part of the pouch-type battery case 13 is drawn to include a cup part including a bag-shaped accommodation space 1331 ( 133 is formed. When the electrode assembly 10 is accommodated in the accommodation space 1331, the electrolyte is injected. After that, when the upper pouch 131 and the lower pouch 132 are brought into contact with each other and thermally compressed to the sealing part 134, the sealant layers 1353 are adhered to each other to seal the battery case 13. In this case, the sealant layer 1353 is in direct contact with the electrode assembly 10 and thus has to be insulative. In addition, the sealant layer 1353 is in contact with the electrolyte and thus has corrosion resistance. In addition, since the inside must be completely sealed to block material movement between the inside and the outside, it must have a high sealing property. That is, the sealing portion 134 bonded to the sealant layers 1353 should have excellent thermal adhesive strength. Generally, the sealant layer 1353 includes polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, poly Paraphenylenebenzobisoxazole, polyarylate, teflon, and glass fibers. In particular, polyolefin resins such as polypropylene (PP) or polyethylene (PE) are mainly used. Polypropylene (PP) has excellent mechanical properties such as tensile strength, rigidity, surface hardness, abrasion resistance, heat resistance, and chemical properties such as corrosion resistance, and is mainly used for manufacturing the sealant layer 1353. Furthermore, it may be composed of unstretched polypropylene or polypropylene-butylene-ethylene terpolymer. In addition, the sealant layer 1353 may have a single film structure made of any one material, or may have a composite film structure in which two or more materials are formed in layers.

4 is a perspective view of the venting device 5 in which the sealing film 55 does not close the end of the housing 51 where the inlet 542 of the passage 54 is formed, and FIG. 5 is the venting device 5 of FIG. 4. ) Is a perspective view showing a state inserted between both sides of the sealing portion 134.

In order for the venting device 5 to be easily fused to the sealing portion 134 of the pouch of the secondary battery 1, as shown in FIG. 4, the sealing film 55 is disposed on at least a portion of an outer surface of the venting device 5. This can be further formed. Thus, as shown in FIG. 5, after the sealing film 55 of the venting device 5 is inserted into the sealing part 134, the venting device 5 may also be sealed if both surfaces of the sealing part 134 are sealed to each other. Sealed together, the adhesion of the inner surface of the venting device 5 and the sealing portion 134 can be improved.

In the venting device 5, the leaf spring 53 is exposed in the outward direction of the pouch. In addition, a gas exhaust hole 533 is formed in the leaf spring 53, and a ball 156 (shown in FIG. 8) and a seat 152 (shown in FIG. 8) come into contact with the inside of the leaf spring 53. have. The sheet 152 is formed through the center of the passage 154 so that the inside and the outside of the pouch communicate with each other. Since each of these components is separately manufactured and then assembled, gaps may actually occur due to design errors or assembly tolerances. In addition, when the secondary battery 1 is not manufactured and used for the first time, a negative pressure in which an internal pressure is smaller than an external pressure may be formed. Therefore, external moisture and other foreign matter can penetrate into the inside of the pouch through the gas exhaust hole 533 of the leaf spring 53 or the clearances of the respective components by the negative pressure, thereby the performance of the secondary battery 1 And energy efficiency may be lowered.

6 is a perspective view of the venting device 15 according to an embodiment of the present invention, Figure 7 is a venting device 15 according to an embodiment of the present invention inserted between both sides of the sealing portion 134 Is a perspective view.

Venting device 15 according to an embodiment of the present invention is inserted into at least one of the sealing portion 134 of the pouch of the secondary battery 1, when the internal pressure of the pouch increases, the internal gas is discharged to the outside to increase the pressure Adjust To this end, the venting device 15 is inserted between both surfaces of the sealing part 134 and sealed together with the sealing part 134, and a housing through which a passage 154 communicating with the inside and outside of the pouch is formed through. (151); And a sealing film 155 for welding the housing 151 and the sealing part 134 to each other, wherein the sealing film 155 is first fusion welded to the outer surface of the housing 151. ); A second fusion unit 1552 in which both surfaces thereof are fused to each other while closing the inlet 1542 of the passage 154 formed at the end of the housing 151; And an unfused portion 1553 formed at one end facing the pouch so that both surfaces thereof are not fused to each other.

The housing 151 is inserted between both surfaces of the sealing part 134 and sealed together with the sealing part 134. When the housing 151 is inserted into both surfaces of the sealing part 134, the sealant layer 1353, which is the innermost layer of the sealing part 134, contacts the housing 151. In addition, when heat and pressure are applied, the sealant layer 1353 of the sealing unit 134 may be fused and sealed together with the housing 151. As shown in FIG. 6, the housing 151 includes an upper housing 1511 and a lower housing 1512, and a step may be formed between the upper housing 1511 and the lower housing 1512. Such a step may be formed because the upper housing 1511 and the lower housing 1512 are different in shape or size from each other. For example, the upper housing 1511 may have a circular cylinder shape with a cross section, and the lower housing 1512 may have an elliptical cylinder shape with an ellipse cross section. Alternatively, the width of the lower housing 1512 may be smaller than the width of the upper housing 1511. Therefore, since the lower housing 1512 is inserted between both surfaces of the sealing part 134 and sealed together, the lower housing 1512 may be fused with the inner surface of the sealing part 134, and the upper housing 1511 may protrude out of the pouch.

At this time, if the width of the lower housing 1512 is excessively large, since the sealing part 134 should also be greatly deformed, the sealing of the sealing part 134 is likely to be broken. Accordingly, the lower housing 1512 may have a width smaller than the thickness of the sealing portion 134, and in particular, the long axis of the cross section may be 6 mm or less. In addition, as described above, the lower housing 1512 has an elliptical cylinder shape having an elliptical cross section so that the lower housing 1512 is easily sealed to the sealing portion 134 so that the sealing can be maintained without breaking for a long time. have.

In addition, if the upper housing 1511 is excessively large, the upper housing 1511 protruding out of the pouch may interfere with other secondary batteries 1 in the vicinity. Thus, assembling the package or module of the secondary battery 1 may not be easy. Therefore, the width of the upper housing 1511 may also be smaller than the thickness of the sealing portion 134, and particularly preferably the diameter of the cross section is 8 mm or less. However, the present disclosure is not limited thereto, and the housing 151 may have various shapes such as one cylinder shape without being divided into the upper housing 1511 and the lower housing 1512.

A sheet 152 (shown in FIG. 8) is formed inside the housing 151 and is made of polymer. In addition, a passage 154 communicating with the inside and the outside of the pouch is formed in the sheet 152 through the center. Details of the sheet 152 will be described later.

The leaf spring 153 is made of metal to open and close the passage 154 formed in the sheet 152 according to the internal pressure of the pouch. In particular, when the internal pressure of the pouch is less than a certain pressure, the leaf spring 153 contacts the seat 152 to close the outlet 1541 of the passage 154 (shown in FIG. 11). Then, when the internal pressure of the pouch is gradually increased to exceed a certain pressure, the leaf spring 153 opens the outlet 1541 of the passage 154 while a part is spaced apart from the seat 152. As shown in FIG. 6, the leaf spring 153 includes a central portion 1531, a peripheral portion 1532, and a gas exhaust hole 1533. Detailed description of the leaf spring 153 will be described later.

Conventionally, the passage 154 is opened and closed using a coil spring. However, the venting device 15 should be miniaturized in order to be inserted into the sealing part 134 of the secondary battery 1. However, if the coil spring is used as in the prior art, the structure of the venting device 15 is complicated and there is a limit to miniaturization. Therefore, according to one embodiment of the present invention, by using the leaf spring 153, it can be miniaturized so that the structure can be simplified and inserted into the sealing portion 134 of the secondary battery (1).

The sealing film 155 may be further formed on at least a portion of the outer surface of the venting device 15. At this time, the sealing film 155 closes the inlet 1542 of the passage 154 formed at the end of the housing 151. The portion where the sealing film 155 is formed may include a portion to be sealed when the housing 151 of the venting device 15 is inserted into the sealing portion 134 and sealed together. Therefore, as shown in FIG. 7, after the sealing film 155 of the venting device 15 is inserted into the sealing part 134, when both sides of the sealing part 134 are sealed with each other, the venting device 15 is also included. Sealing, the adhesion between the venting device 15 and the inner surface of the sealing portion 134 may be improved. If the housing 151 includes the upper housing 1511 and the lower housing 1512, the inlet 1542 of the passage 154 is formed at the end of the lower housing 1512, so that the sealing film 155 is the lower housing. It is preferably formed at 1512. As a result, the sealing film 155 can easily close the inlet 1542 of the passage 154.

Meanwhile, the sealing film 155 may be made of the same or similar material as the inner surface of the sealing portion 134, that is, the sealant layer 1353, in order to further improve adhesion to the inner surface of the sealing portion 134. desirable. That is, if the sealant layer 1353 includes a polyolefin resin such as polypropylene (PP) or polyethylene (PE), the sealing film 155 also includes polyolefin resin such as polypropylene (PP) or polyethylene (PE). It is preferable to be made of a material to be.

8 is a side cross-sectional view of the venting device 15 according to an embodiment of the present invention.

As shown in FIG. 8, the venting device 15 according to an embodiment of the present invention is formed in the housing 151, is made of polymer, and has a sheet 152 through which the passage 154 is formed. ); A ball 156 at the outlet 1541 side of the passage 154, contacting or spaced from the seat 152 and opening and closing the passage 154; And the ball 156 and the seat 152 formed to surround and open and close the passage 154 according to the internal pressure of the pouch due to the elastic force, and further comprises a leaf spring 153 made of metal. Include.

The seat 152 is formed inside the housing 151 and the passage 154 is formed through. And, although it may be made of a metal, it is preferable that it is made of a polymer in order to prevent the generation of gaps between components. In particular, the polymer may include a polyolefin-based polymer such as polypropylene (PP). As shown in FIG. 8, the seat 152 is chamfered or filleted with an inner circumferential edge of the side surface of the outlet 1541 of the passage 154. As a result, the ball 156 may face the chamfered or filleted surface 1521 of the seat 152, and the ball 156 may be in close contact with each other.

The ball 156 has a spherical shape and is disposed between the leaf spring 153 and the seat 152. Then, at the exit 1541 side of the passage 154 formed in the sheet 152, the passage 154 is opened and closed while contacting or spaced apart from the sheet 152. The ball 156 may be made of a polymer to further improve adhesion to the sheet 152, but is preferably made of metal to improve the durability of the ball 156.

To facilitate seating on one side 1521 of sheet 152, ball 156 is smaller than the widest of one side 1521 of the sheet 152 and wider than the narrowest. When the ball 156 is seated, it is preferable that the highest point of the ball 156 is formed higher than the highest point of the sheet 152. As a result, the ball 156 and the leaf spring 153 easily contact each other, and the elastic force of the leaf spring 153 can be efficiently applied to the ball 156 so that the ball 156 can be brought into close contact with the seat 152. .

The leaf spring 153 may be manufactured by molding a metal sheet. The metal sheet has a wide thin plate-like shape, is made of metal, and may in particular comprise aluminum (Al) or stainless steel (STS). In order to manufacture the leaf spring 153, the metal sheet may be molded by a drawing process by stretching the metal sheet with a punch. Specifically, drawing molding may be performed by seating the metal sheet on a die, the stripper fixing the metal sheet, and stretching the sheet with a punch. As illustrated in FIG. 8, the leaf spring 153 manufactured as described above has a cap shape in which one side portion 1530 is convex outward, and an insertion space into which the sheet 152 is inserted is formed. One side portion 1530 of the leaf spring 153 may mean a ceiling in the cap shape, as shown in FIG.

The leaf spring 153 is formed surrounding the seat 152 and the ball 156. That is, when the leaf spring 153 is manufactured through the drawing molding, an insertion space is formed, and the seat 152 and the ball 156 are seated on the one surface 1521 of the seat 152. Is inserted into the insertion space. Thereby, the leaf spring 153 can surround the seat 152 and the periphery of the ball 156. When the seat 152 and the ball 156 are inserted into the insertion space, it is preferable that the outlet 1541 side of the passage 154 faces the one side 1530 of the leaf spring 153. Thus, the ball 156 and the leaf spring 153 can easily open and close the passage 154 formed in the seat 152.

The leaf spring 153 also opens and closes the passage 154 with the ball 156 according to the internal pressure of the pouch due to the elastic force. To this end, it is preferable that the gas exhaust hole 1533 is perforated in one side 1530 of the leaf spring 153. In this case, one side 1530 of the leaf spring 153 includes a central portion 1531 formed at the center and a peripheral portion 1532 extending outwardly from the central portion 1531. In the central portion 1530, the lower surface of the central portion 1153 contacts the ball 156 and closes the passage 154 formed in the sheet 152, so that a gas exhaust hole 1533 is formed in the central portion 1531. It is not perforated. Accordingly, the gas exhaust hole 1533 may be perforated in the peripheral portion 1532 of one side 1530 of the leaf spring 153.

When gas is generated inside the pouch and the internal pressure increases, the gas inside the pouch pushes the ball 156 outward, and as the ball 156 is pushed, one side 1530 of the leaf spring 153 is also outward. Pushed away. The passage 154 then opens, and the gas flows out through the outlet 1541 of the passage 154. At this time, the outflowed gas should be discharged to the outside through the gas exhaust hole 1533. Accordingly, the seat 152 may be chamfered or filleted at the outer circumferential edge of the side of the exit 1541 of the passage 154. Thereby, the gas can be guided to the gas exhaust hole 1533, and the peripheral portion 1532 of one side 1530 of the leaf spring 153 is pushed outward while the one side 1530 of the leaf spring 153 is pushed outward. ) Is provided with a space for moving inward.

The leaf spring 153 is preferably firmly fixed to the seat 152. Therefore, when the gas inside the pouch pushes out one side 1530 of the leaf spring 153 through the ball 156, the leaf spring 153 moves the one side 1530 outward. When the leaf spring 153 does not slide as a whole, only one side 1530 of the leaf spring 153 is deformed and moved. If the leaf spring 153 is in a sliding motion, the leaf spring 153 may leave the venting device 15. In particular, only the central portion 1531 of the one side portion 1530 is pushed outward, and the peripheral portion 1532 of the one side portion 1530 may move inward. Therefore, gas inside the pouch may be discharged to the outside through the passage 154.

To this end, according to one embodiment of the invention, after the seat 152 and the ball 156 is inserted into the insertion space 1534, the other end of the leaf spring 153 is seated, as shown in FIG. Bend toward (152). Thus, even if the gas inside the pouch pushes out one side 1530 of the leaf spring 153 to the outside, the leaf spring 153 prevents detachment (separation) from the seat 152 so that the venting device 15 Can be fixed without leaving.

The leaf spring 153 into which the seat 152 is inserted is inserted into the housing 151. In this case, if the housing 151 includes the upper housing 1511 and the lower housing 1512, the leaf spring 153 and the seat 152 are preferably included in the upper housing 1511. 8, one side 1530 of the leaf spring 153 may face the open end 1513 of the upper housing 1511. Therefore, the gas may be discharged to the outside through the gas exhaust hole 1533 formed in the one side 1530. In addition, as described above, the leaf spring 153 does not slide as a whole, but only one side portion 1530 is deformed in a fixed state. Therefore, when the leaf spring 153 is inserted into the housing 151 so that the friction force acts largely between the outer circumferential surface of the leaf spring 153 and the inner circumferential surface of the housing 151, the leaf spring 153 is interposed between the housing 151 and the housing 151. It is desirable that the gap of is minimized. However, the present invention is not limited thereto, and the friction coefficient may be increased by increasing the surface roughness of the outer circumferential surface of the leaf spring 153 or the inner circumferential surface of the housing 151. Furthermore, a separate adhesive may be applied between the leaf spring 153 and the housing 151, or a protrusion may protrude from one of the leaf spring 153 and the housing 151, and a groove may be formed and coupled to the other. The leaf spring 153 may be fixed to the housing 151 in various ways.

As illustrated in FIG. 8, the sealing film 155 formed in the housing 151 may include a first fusion unit 1551 and the housing fused to an outer surface of the housing 151. And a second fusion portion 1552 of which both surfaces are fused to each other while closing the inlet 1542 of the passage 154 formed at the end of 151. Accordingly, the first fusion unit 1551 easily welds the housing 151 and the sealing unit 134 to each other. The second fusion unit 1552 is configured to penetrate the inside of the pouch even if external moisture or other foreign matter penetrates through the gas exhaust hole 1533 of the leaf spring 153 and the gaps between the respective components by the negative pressure. You can prevent it.

On the other hand, the sealing film 155 includes not only the first and second fusion portions 1552 described above, but also an unfused portion 1553 formed at one end facing the pouch so that both surfaces thereof are not fused to each other. Detailed description of the unfused portion 1553 of the sealing film 155 will be described later.

9 is a side cross-sectional view showing a state in which the venting device 15 is inserted between both surfaces of the sealing portion 134 according to an embodiment of the present invention, Figure 10 is an interior of the pouch according to an embodiment of the present invention This is a side cross-sectional view showing the distance between the two sides of the pouch due to increased pressure.

Venting device 15 according to an embodiment of the present invention, is inserted between both sides of the sealing portion 134 of the pouch as shown in FIG. At this time, as described above, the portion where the sealing film 155 is formed is, as shown in Figure 9, when the housing 151 of the venting device 15 is inserted into the sealing portion 134 and sealed together, It may include a portion to be sealed. Therefore, after the sealing film 155 of the venting device 15 is inserted into the sealing part 134, when both surfaces of the sealing part 134 are sealed with each other, the venting device 15 is also sealed together, so that the venting device 15 And the adhesion of the inner surface of the sealing portion 134 can be improved.

Venting method using the venting device 15 according to an embodiment of the present invention, the gas generated inside the pouch of the secondary battery, the step of increasing the internal pressure of the pouch; In a sealing film formed at one end of the venting device inserted into the sealing part of the pouch, a fusion part of which both surfaces are fused to each other while closing the inlet of the passage formed at the end of the housing of the venting device; The internal pressure of the pouch exceeds a certain pressure; A step of detaching the welded portion from the unbonded portion formed at one end of the sealing film facing the pouch and not fused to each other; Introducing the gas into an inlet of the passage; The gas pushing out the ball of the venting device; Opening the exit of the passageway as the ball is pushed; And discharging the gas to the outside through the passage. Hereinafter, the content of each step will be described in detail.

As described above, when the secondary battery 1 is stored or stored in a high temperature state, a high temperature rapidly promotes the electrochemical reaction of the electrolyte and the electrode active material, and gas may be generated therein. Thereby, as the internal pressure of the pouch of the secondary battery 1 increases and the volume of the pouch increases, as shown in FIG. 10, the distance between opposite sides of the pouch becomes farther. At this time, as described above, the sealing film 155 includes an unfused portion 1553 which is formed at one end facing the pouch so that both surfaces thereof are not fused to each other. Therefore, when gas continues to generate in the pouch of the secondary battery 1 and the internal pressure also increases continuously, the second fusion portion 1552 of the sealing film 155 receives a force. When the internal pressure of the pouch exceeds a specific pressure, the second welded portions 1552 of the sealing film 155 are gradually detached (separated) from each other around the unfused portions 1553.

However, as described above, the sealing film 155 is preferably made of the same or similar material as the sealant layer 1353, that is, a material containing a polyolefin resin such as polypropylene (PP). Therefore, the welding force between the sealing film 155 and the sealing part 134 and the welding force of the second welding part 1552 of the sealing film 155 may be similar to each other. Then, when the internal pressure of the pouch increases, the second fusion unit 1552 is not detached around the unfused portion 1553 of the sealing film 155, and the sealing film 155 and the sealing unit 134 are not detached. May be detached first.

Therefore, according to the exemplary embodiment of the present invention, a part of the outer surface of the unsealed portion 1553 of the sealing film 155 is fused to both surfaces of the sealing portion 134, respectively. As a result, when the internal pressure of the pouch increases and the two opposite surfaces of the pouch are separated, the second fusion portion 1552 of the sealing film 155 becomes more than the space between the sealing film 155 and the sealing portion 134. Receive more power. Therefore, the second fusion portion 1552 of the sealing film 155 may gradually be detached from each other with respect to the unfused portion 1553.

11 is a side cross-sectional view illustrating a state in which the sealing film 155 is detached from each other and the passage 154 is opened according to an embodiment of the present invention.

When the internal pressure of the pouch is smaller than the specific pressure, the second fusion portion 1552 is still fused. The leaf spring 153 and the ball 156 contact the seat 152 at the exit 1541 side of the passage 154 formed in the seat 152 to close the exit 1541. In addition, when gas is continuously generated in the pouch of the secondary battery 1 and the internal pressure of the pouch is gradually increased to exceed the specific pressure, as illustrated in FIG. 11, the second fusion portion of the sealing film 155 ( 1552 is eventually detached and gas enters the inlet 1542 of the passage 154 of the venting device 15. Then, the gas pushes the ball 156 outward, and as the ball 156 is pushed, one side 1530 of the leaf spring 153 is pushed outward. The leaf spring 153 is spaced apart from the seat 152 so that the ball 156 may be separated from the seat 152 to open the outlet 1541 of the passage 154, and the gas inside the pouch may pass through the passage 154. Can be discharged to the outside.

When the gas inside the pouch is sufficiently discharged to the outside, the internal pressure of the pouch decreases again. Then, the pressure of the gas which pushes the leaf spring 153 decreases. However, the leaf spring 153 is made of metal and has elasticity. Therefore, when the gas inside the pouch is sufficiently discharged to the outside and the internal pressure of the pouch becomes smaller than the specific pressure again, the pressure of the gas pushing the leaf spring 153 decreases. And the leaf spring 153 returns to an original position by elastic force, and pushes the ball 156 back inside. Then, the leaf spring 153 again contacts the seat 152 at the outlet 1541 side of the passage 154, and the ball 156 comes into close contact with the seat 152 and the outlet 154 of the passage 154. 1541).

At this time, since the second welded portion 1552 of the sealing film 155 is once detached, it is not welded again so that the inlet 1542 of the passage 154 of the venting device 15 is not closed. However, since gas has already been generated inside the pouch, no negative pressure is formed later. Therefore, external moisture and other foreign matter do not penetrate into the inside of the pouch.

On the other hand, the specific pressure is a reference of the pressure inside the pouch in which the venting device 15 operates. This specific pressure is proportional to the welding force of the second welding unit 1552. Therefore, by adjusting the area of the second fusion unit 1552, the specific pressure can be adjusted.

12 is a side cross-sectional view showing the venting device 15 is inserted between both sides of the sealing portion 134 according to another embodiment of the present invention, Figure 13 is an interior of the pouch according to another embodiment of the present invention This is a side cross-sectional view showing the distance between the two sides of the pouch due to increased pressure.

According to one embodiment of the present invention, the sealing film 155 is a portion of the outer surface of the unfused portion 1553, the both surfaces of the sealing portion 134 are fused. By the way, according to the ratio of the area fused to both surfaces of the sealing portion 134, when the internal pressure of the pouch increases, the force applied between the sealing film 155 and the sealing portion 134, and the sealing film ( The ratio of the force applied to the unfused portion 1553 of 155 may also be different from each other.

However, if the remaining part that is not fused to both surfaces of the sealing part 134 is left as it is on the outer surface of the unsealed part 1553, both surfaces of the sealing part 134 due to flow, corrosion, and aging of the electrolyte solution. A portion of the outer surface of the unfused portion 1553 that has been fused may gradually be detached. Then, the ratio of the area fused to both surfaces of the sealing portion 134 may gradually decrease.

If the area welded to both sides of the sealing part 134 gradually decreases at the outer surface of the unfused part 1553, the magnitude of the force received by the second weld part 1552 of the sealing film 155 decreases. Relatively, the magnitude of the force received between the sealing film 155 and the sealing portion 134 increases. Therefore, when the internal pressure of the pouch increases, the second fusion portion 1552 is not detached around the unfused portion 1553 of the sealing film 155, but the sealing film 155 and the sealing portion 134 are not detached. May be detached first.

Therefore, according to another embodiment of the present invention, as shown in FIG. 12, the entire outer surface of the unsealed portion 1553a is fused to both surfaces of the sealing portion 134, respectively. do. Therefore, there is no portion of the outer surface of the unfused portion 1553a that is not fused to both surfaces of the sealing portion 134. As a result, when the internal pressure of the pouch increases as shown in FIG. 13, the second fusion portion 1552 of the sealing film 155a becomes even more than between the sealing film 155a and the sealing portion 134. Receives a lot of power. And it can be reliably prevented that the sealing film 155a and the sealing part 134 are detached first.

Those skilled in the art will appreciate that the present invention can be embodied in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive. The scope of the present invention is shown by the following claims rather than the above detailed description, and it should be construed that various embodiments derived from the meaning and scope of the claims and equivalent concepts thereof are included in the scope of the present invention.

1: Secondary Battery 10: Electrode Assembly
11: electrode tab 12: electrode lead
13: battery case 14: insulation
15: venting device 111: anode tab
112: negative electrode tab 121: positive electrode lead
122: negative electrode lead 131: upper pouch
132: lower pouch 133: cup portion
134: sealing portion 135: pouch film
151: housing 152: sheet
153: leaf spring 154: passage
155: sealing film 156: ball
1331: accommodation space 1351: gas barrier layer
1352: surface protective layer 1353: sealant layer
1511: upper housing 1512: lower housing
1521: 1 page 1530: One side
1531: Central 1532: Peripheral
1533: gas exhaust hole 1541: exit
1542 inlet 1551 first fusion
1552: second welded portion 1553: unfused portion

Claims (17)

In the venting device inserted into the sealing portion of the pouch of the secondary battery,
A housing inserted between both surfaces of the sealing part and sealed together with the sealing part, the housing having a passage communicating with the inside and the outside of the pouch; And
It includes a sealing film for fusion bonding the housing and the sealing portion,
The sealing film,
A first fusion unit fused to an outer surface of the housing;
A second welding part of which both surfaces are fused to each other while closing an inlet of the passage formed at an end of the housing; And
Venting device is formed at one end facing the pouch, the non-fused portion that both sides are not fused to each other. The method of claim 1,
The sealing film,
At least a portion of an outer surface of the unfused portion is fused to both surfaces of the sealing portion, respectively. The method of claim 2,
The sealing film,
Venting device, the entire outer surface of the unfused portion is fused to both sides of the sealing portion, respectively. The method of claim 1,
A sheet formed inside the housing, made of a polymer, and through which the passage is formed;
A ball for contacting or spaced apart from the seat and opening and closing the passage at an outlet side of the passage; And
And surrounding the seat and the ball and opening and closing the passage according to the internal pressure of the pouch due to the elastic force, further comprising a leaf spring made of metal. The method of claim 4, wherein
The sheet,
And an inner circumferential edge of the exit side surface of the passage chamfered or filleted to face the ball. The method of claim 4, wherein
The sheet,
Venting device, wherein the outer peripheral edge of the exit side of the passage is chamfered or filleted. The method of claim 4, wherein
The leaf spring is,
Venting device having a cap shape in which one side is convex outward, the insertion space is formed therein is inserted into the sheet and the ball. The method of claim 7, wherein
The leaf spring is,
And the other end is bent toward the sheet inserted in the insertion space. The method of claim 4, wherein
The leaf spring is,
A central portion formed in the center; And
It includes a peripheral portion extending in the outward direction from the center,
Venting device is perforated in the peripheral portion. The method of claim 1,
The housing,
A venting device comprising an upper housing and a lower housing different in shape or size from each other. The method of claim 10,
The lower housing,
A venting device, the width of which is less than the width of the upper housing. The method of claim 10,
The upper housing,
Has a circular cylinder shape,
The lower housing,
Venting device having an elliptical cylinder shape. The method of claim 10,
The sealing film,
The venting device is formed in the lower housing. Generating gas inside the pouch of the secondary battery to increase the internal pressure of the pouch;
In the sealing film formed at one end of the venting device inserted into the sealing part of the pouch, receiving a fusion part of which both surfaces are fused to each other while closing the inlet of the passage formed at the end of the housing of the venting device;
The internal pressure of the pouch exceeds a certain pressure;
A step of detaching the welded portion from the unbonded portion formed at one end of the sealing film facing the pouch and not fused to each other;
Introducing the gas into an inlet of the passage;
The gas pushing out the ball of the venting device;
Opening the exit of the passageway as the ball is pushed; And
Venting the gas to the outside through the passage. A pouch for accommodating an electrode assembly formed by stacking an anode and a cathode on both sides of the separator;
Including a venting device is inserted into the sealing portion of the pouch,
The venting device,
A housing inserted between both surfaces of the sealing part and sealed together with the sealing part, the housing having a passage communicating with the inside and the outside of the pouch; And
It includes a sealing film for fusion bonding the housing and the sealing portion,
The sealing film,
A first fusion unit fused to an outer surface of the housing;
A second welding part of which both surfaces are fused to each other while closing an inlet of the passage formed at an end of the housing; And
The secondary battery is formed at one end facing the pouch, and comprises a non-fused portion that both surfaces are not fused to each other. The method of claim 15,
The sealing film,
At least a portion of an outer surface of the unfused portion is fused to both surfaces of the sealing portion, respectively. The method of claim 16,
The sealing film,
A secondary battery, wherein the entire outer surface of the unfused portion is fused to both sides of the sealing portion, respectively.

Images