Secondary battery

Abstract

The present invention provides a secondary battery in which an electrode assembly is inserted into a pouch and an electrolyte is injected into the pouch, and an edge of the pouch is sealed to form a sealed portion, the secondary battery comprising: a valve fixed to the sealed portion so that one end of the valve faces an inside of the pouch and the other end of the valve faces an outside of the pouch, wherein the valve comprises: a main body formed with a passage having one end portion open to the inside of the pouch, and provided with a chamber connected to the passage, wherein a discharge hole communicating with the outside is formed in the chamber; a gate on a hook-shaped protrusion forming a boundary between the passage and the chamber to open or close the passage; and a spring installed to apply an elastic force in a direction in which the gate is closed, wherein when gas is generated in the inside of the pouch, a pressure of the gas overcomes the elastic force of the spring, the gate is opened to discharge the gas through the discharge hole. In the present invention having the above configuration, when gas is generated in the inside of the pouch and the pressure of the gas overcomes the elastic force of the spring, the gate can be opened to be discharged to the discharge hole, thereby effectively preventing swelling from occurring, and preventing moisture and foreign matter from being introduced from the outside of the valve.

Description

TECHNICAL FIELD

[0001] This application claims the benefit of priority of Korean Patent Application No. 10-2020-0072597, filed on June 15, 2020, the entire contents of which are incorporated into this specification by reference.

[0002] The present application relates to a secondary battery in which an electrode assembly and an electrolyte are embedded in a soft pack, and more particularly, to a soft pack type secondary battery having a valve capable of discharging gas to the outside when the gas is generated in the soft pack. BACKGROUND

[0003] In the field of mobile devices and electric vehicles, the demand for high-efficiency secondary batteries is rapidly increasing. Among these secondary batteries, lithium secondary batteries having high energy density, maintaining a high voltage, and having a low self-discharge rate are widely used in commerce, and research and development to improve their performance are actively being conducted.

[0004] A secondary battery has a structure in which an electrode assembly and an electrolyte are embedded in a case such as a can or a soft pack. The electrode assembly has a structure in which a positive electrode, a separator, and a negative electrode are repeatedly stacked. In general, the electrode assembly can be classified into a jelly-roll type electrode assembly in which the positive electrode, the separator, and the negative electrode in a stacked state are wound to be embedded in the case and a stacked type (stacked) electrode assembly in which the positive electrode, the separator, and the negative electrode are cut into predetermined sizes, respectively, and stacked.

[0005] Since the jelly-roll type electrode assembly has a spiral winding structure, the jelly-roll type electrode assembly is suitable for installation on a cylindrical battery, but has a disadvantage in terms of space utilization for prismatic or soft pack type batteries. On the other hand, since the size of the stacked type electrode assembly is adjusted when the electrode and the separator are cut, it is easy to obtain a prismatic shape that matches the case, but the manufacturing process is relatively complex, and the stacked type electrode assembly is relatively vulnerable to external impact. In addition, a stack folding method has been developed to combine the advantages of the jelly-roll type and the stacked type. In the stack folding method, a C-type double battery (a double battery having a stacked structure of a positive electrode / separator / negative electrode / separator / positive electrode) and an A-type double battery (a double battery having a stacked structure of a negative electrode / separator / positive electrode / separator / negative electrode) are placed on a folding separator to fold the double batteries, thereby manufacturing an electrode assembly.

[0006] The electrode assembly manufactured in various ways as described above is installed in a case such as a can or a soft pack.

[0007] Among these batteries, the soft pack type battery has advantages such as higher energy density per unit weight and volume, the ability to form a thinner and lighter battery, and lower cost of outer packaging materials, and thus has been actively developed in recent years. As shown in a state in which the soft pack 1 is opened and the electrode assembly 3 is installed in the opened state,Figure 1 As shown in FIG. 1, a soft-pack type secondary battery is manufactured such that the electrode assembly 3 is disposed in the soft-pack 1 in a state in which the upper and lower portions of the soft-pack 1 are separated from each other, and when the electrolyte is injected, the sealing portions 2a and 2b formed at the edges of the upper and lower portions are sealed. Here, the end portions of the electrode leads 3a, which are drawn from the electrode assembly 3, are sealed in a state in which they are provided to protrude to the outside.

[0008] A problem of the soft-pack type battery is that swelling occurs during the manufacturing process and during the process of being used as a charging / discharging device after the manufacturing.

[0009] This swelling is due to the generation of gas inside the soft-pack 1 due to evaporation of the electrolyte, thereby deforming the appearance of the soft-pack 1 and deteriorating the charging / discharging performance of the secondary battery, and in a severe case, there is a risk of explosion.

[0010] Therefore, when gas is generated inside the soft-pack, the gas must be removed. SUMMARY

[0011] TECHNICAL PROBLEM

[0012] To solve the above problem, an object of the present application is to provide a secondary battery having a valve capable of discharging gas to the outside when the internal pressure increases due to the generation of gas inside the soft-pack.

[0013] TECHNICAL SOLUTION

[0014] To achieve the above object, the present application provides a secondary battery in which an electrode assembly is inserted into a soft-pack and an electrolyte is injected into the soft-pack, and the edges of the soft-pack are sealed to form sealing portions, the secondary battery comprising: a valve fixed to the sealing portions such that one end of the valve faces the inside of the soft-pack and the other end of the valve faces the outside of the soft-pack, wherein the valve comprises: a main body formed with a passage having one end portion open to the inside of the soft-pack, and provided with a chamber connected to the passage, wherein a discharge hole communicating with the outside is formed in the chamber; a gate on a hook-shaped protrusion forming a boundary between the passage and the chamber to open or close the passage; and a spring installed to apply an elastic force in a direction in which the gate is closed, wherein when gas is generated inside the soft-pack, the pressure of the gas overcomes the elastic force of the spring, the gate is opened to discharge the gas through the discharge hole.

[0015] An O-ring can be installed at a position of the hook-shaped protrusion at which the gate is provided, such that sealing is achieved when the gate is closed.

[0016] A barrier film for preventing the penetration of the electrolyte can be installed on the inlet side of the passage of the main body, and when gas is generated inside the soft-pack to increase the internal pressure, the barrier film can be torn or separated from the installation position.

[0017] The blocking film can be made of a material that does not cause a chemical reaction with the electrolyte. The blocking film can be manufactured as a thin film made of polypropylene or polytetrafluoroethylene.

[0018] The blocking film can be adhered to the main body by using a pressure-sensitive adhesive.

[0019] An auxiliary discharge hole can be formed so that air in the chamber is discharged when the gate slides in the chamber, wherein the auxiliary discharge hole can be formed on the opposite side of the discharge hole, between which the gate is located.

[0020] The gate can include a main body located on the hook-shaped protrusion, and a post extending from the main body and protruding to be inserted into the passage, wherein a ring-shaped gasket can be fitted on the outer peripheral surface of the post to seal a gap between the outer peripheral surface of the post and the inner peripheral surface of the passage.

[0021] An inclined surface can be formed along the circumference of the post so that gas is gradually introduced into the chamber as the post slides.

[0022] The valve can be disposed in parallel with an electrode lead wire that is drawn out from the electrode assembly and protrudes to the outside of the pouch.

[0023] The present application can additionally provide a secondary battery module manufactured by connecting a plurality of secondary batteries having the above-described configuration to each other.

[0024] Advantageous Effects

[0025] In the present application having the above-described configuration, when gas is generated inside the pouch and the pressure of the gas overcomes the elastic force of the spring, the gate can be opened to be discharged to the discharge hole, thereby effectively preventing swelling from occurring, and preventing moisture and foreign matter from being introduced from the outside of the valve.

[0026] An O-ring can be installed at a position of the hook-shaped protrusion where the gate is provided to prevent leakage of the electrolyte.

[0027] Further, a blocking film can be installed on the inlet side of the passage, thereby fundamentally blocking the introduction of the electrolyte into the valve when the pressure inside the pouch is within a normal range.

[0028] The blocking film can be made of a material that does not cause a chemical reaction with the electrolyte, to prevent deterioration of the performance of the electrolyte.

[0029] In the valve according to the present application, an auxiliary discharge hole can be formed on the opposite side of the discharge hole to prevent air resistance from adversely affecting the sliding of the valve.

[0030] Further, a gasket can be fitted in the gate to prevent leakage of gas, and an inclined surface can be formed on the post to gradually discharge the gas. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a perspective view showing a state in which the electrode assembly is installed in a state in which the pouch is opened;

[0032] Figure 2 is a view showing a state in which the valve is installed in the secondary battery according to the first embodiment of the present application,

[0033] Figure 3 is a cross-sectional view showing a state in which the gate is closed before gas is generated in the pouch according to the first embodiment of the present application (left), and a cross-sectional view showing a state in which gas is generated in the pouch to open the gate by the pressure of the gas (right);

[0034] Figure 4 is a view more clearly showing the installation state of the gasket in Figure 2 ;

[0035] Figure 5 is a cross-sectional view showing a state in which the blocking film is installed at the inlet side of the passage according to the second embodiment of the present application (left), and a cross-sectional view showing a state in which the blocking film is separated from the installation position (right). DETAILED DESCRIPTION

[0036] Hereinafter, preferred embodiments of the present application will be described in detail with reference to the accompanying drawings so that one of ordinary skill in the art to which the present application pertains can easily practice the technical idea of the present application. However, the present application can be embodied in different forms and should not be construed as being limited to the embodiments set forth herein.

[0037] In order to clearly describe the present application, components irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification.

[0038] In addition, the terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, but should be interpreted as concepts that the inventor can appropriately define in order to best describe and explain his or her application in the art. Accordingly, the terms and words should be interpreted based on the meaning and concept of the inventor's application within the scope of the present application.

[0039] The present application relates to a secondary battery in which an electrode assembly and an electrolyte are inserted into a pouch, and edges of the pouch are sealed to form a sealed portion. Hereinafter, embodiments of the present application will be described in more detail with reference to the accompanying drawings.

[0040] First Embodiment

[0041] Figure 2 is a view showing a state in which the valve is installed in the secondary battery according to the first embodiment of the present application, Figure 3is a cross-sectional view (left) showing a state in which the gate is closed before gas is generated in the pouch according to a first embodiment of the present application, and a cross-sectional view (right) showing a state in which gas is generated in the pouch to open the gate by the pressure of the gas, Figure 4 is a view more clearly showing the installation state of the gasket in Figure 2 .

[0042] Referring to the drawings, a secondary battery according to this embodiment includes a valve 100 fixedly installed such that one end of the valve 100 faces the inside of a pouch 1 and the other end of the valve 100 faces the outside of the pouch 1. Here, the valve 100 is disposed in parallel to an electrode lead 3a drawn from an electrode assembly and protruding a distance outside the pouch 1.

[0043] The valve 100 has a structure in which a gate 20 is fixed to a sealing portion and installed inside a main body 10 in which a passage is formed such that gas can go in and out.

[0044] That is, as shown in more detail in Figure 3 , the main body 10 has a passage having one end portion open toward the inside of the pouch 1 and extending in a longitudinal direction from the one end to the other end on the other side, and the passage 11 is open to a chamber 12.

[0045] The chamber 12 has a structure in which the end portion opposite the end portion of the passage 11 is blocked, and a discharge hole 13 is formed to communicate with the outside in a portion of a side wall. The valve 100 is fixed to the sealing portion in a state in which the discharge hole 13 is exposed to the outside. The main body 10 is made of a metal, ceramic, synthetic resin, etc. having excellent chemical resistance.

[0046] In addition, the gate 20 is located on a hook-shaped protrusion formed at a boundary between the passage 11 and the chamber 12 to open or close the passage 11. The hook-shaped protrusion is a boundary point formed by the difference between the inner diameter of the passage 11 and the inner diameter of the chamber 12, and the gate 20 is installed to shield the hook-shaped protrusion in the chamber 12.

[0047] The gate 20 is connected with a spring 30 such that an elastic force acts in a direction in which the gate 20 is closed. The spring 30 is a compression spring against a compression force, and has one end fixed to a wall surface (disposed on the opposite side of the passage) of the chamber 12 and the other end fixed to the gate 20.

[0048] Therefore, the gate 20 is opened only when a force overcoming the elastic force of the spring 30 is applied.

[0049] In addition, an O-ring 15 is installed at a position of the hook-shaped protrusion where the shutter 20 is provided, such that sealing is achieved when the shutter 20 is closed. When the shutter 20 is closed, the O-ring 15 is pressed by the elastic force of the spring 30, thereby elastically deformed to seal a gap that occurs between the shutter 20 and the main body 10.

[0050] In addition, an auxiliary discharge hole 16 is additionally formed, such that air in the chamber 12 is discharged when the shutter 20 slides inside the chamber 12. Since the auxiliary discharge hole 16 is formed at opposite sides of the discharge hole 13, between which the shutter 20 is located, when the space where the spring 30 is provided is compressed, air can be discharged to the outside before being compressed, to prevent the sliding of the shutter 20 from being disturbed by air resistance.

[0051] The shutter 20 according to this embodiment includes a disc-shaped body 21 located on the hook-shaped protrusion, and a cylindrical pillar 22 extending from the disc-shaped body 21 and protruding to be inserted into the passage 11.

[0052] When the shutter 20 is in a closed state, the disc-shaped body 21 shields a gap between the passage 11 and the chamber 12, and the pillar 22 extends from the disc-shaped body 21 to be inserted into the passage 11, thereby guiding the sliding of the disc-shaped body 21.

[0053] In addition, the pillar 22 has an inclined surface 22a along a circumference of the pillar 22, such that gas is gradually introduced into the chamber 12 as the pillar 22 slides, and the contact area increases as the gas is introduced into the passage 11, to concentrate pressure. The inclined surface 22a can be formed as a plane inclined at a predetermined angle, or can be formed as a convexly rounded curved surface along the circumference of the pillar 22.

[0054] In addition, as Figure 4 more clearly shown in FIG. 2, a plurality of annular gaskets 23 can be fitted on an outer circumferential surface of the pillar 11, to seal the outer circumferential surface of the pillar 11 from an inner circumferential surface of the passage 11.

[0055] Thus, when gas is in a normal pressure range before gas is generated inside the pouch 1, the shutter 20 shields the passage 11 due to the elastic force of the spring 30, as shown in the left drawing of FIG. 3. Figure 3

[0056] And, when gas is generated inside the pouch 1 to increase the pressure inside the pouch 1, the air pressure overcomes the elastic force of the spring 30 to push the shutter 20 out, whereby, as shown in the right drawing of FIG. 3, gas is introduced into the chamber 12, and then discharged to the outside through the discharge hole 13. Here, the opening pressure of the shutter 20, at which the shutter opens, can be variously set by adjusting the elastic force of the spring 30. Figure 3

[0057] ​​In addition, when the gate 20 is opened by the frictional force generated between the gate 20 and the main body 10 and the frictional force generated between the gasket 23 and the main body 10, even if the pressure is slightly lower than the applied pressure, the open state can be maintained to effectively discharge the gas (for example, when the gas pressure is 0.1 Mpa, if the gate is opened, the gas is discharged to the outside to reduce the gas pressure, and thus the gate is set not to be closed even when the gas pressure is 0.1 Mpa, but to be closed at a pressure of about 0.05 Mpa).

[0058] In addition, a lubricant and a vacuum lubricant can be additionally applied to the contact portion between the main body 10 and the gate 20 to reduce the sealing performance and the frictional force, and the lubricant and the vacuum lubricant can be selected from materials that do not react with the electrolyte.

[0059] Second Embodiment

[0060] In this embodiment, the valve is additionally attached with a blocking film 40 that shields the passage 11 in the main body 10 of the valve 100 according to the first embodiment.

[0061] Figure 5 is a cross-sectional view showing a state in which the blocking film is installed at the inlet side of the passage according to the second embodiment of the present application (left), and a cross-sectional view showing a state in which the blocking film is separated from the installation position (right).

[0062] Reference Figure 5 The blocking film 40 for preventing the penetration of the electrolyte can be installed at the inlet side of the passage 11 in the main body 10.

[0063] The blocking film 40 is provided to prevent the unnecessary introduction of the gas and the electrolyte into the passage 11 before the internal pressure of the soft pack 1 is increased.

[0064] The blocking film 40 can be configured to be torn or separated from the installation position when the gas is generated inside the soft pack 1 to increase the internal pressure.

[0065] The blocking film 40 is not limited to a specific material as long as the material does not cause a chemical reaction with the electrolyte, but a material that can be easily torn according to a change in pressure is preferred. Alternatively, even if the material is not sensitive to a change in pressure, the blocking film 40 can be installed by adjusting the sensitivity of the adhesive 41 to which the blocking film 40 is adhered to prevent the blocking film 40 from being separated.

[0066] The blocking film 40 according to the present application is manufactured as a thin film made of polypropylene or polytetrafluoroethylene.

[0067] In addition, a pressure-sensitive adhesive can be used as the adhesive 41 adhered to the blocking film.

[0068] In the present application having the above configuration, when gas is generated inside the pouch 1 and the pressure of the gas overcomes the elastic force of the spring 30, the gate 20 can be opened to be discharged to the discharge hole 13, thereby effectively preventing swelling from occurring and preventing moisture and foreign substances from being introduced from the outside of the valve 100.

[0069] The O-ring 15 can be installed at the position of the hook-shaped protrusion where the gate 20 is provided, to prevent leakage of the electrolyte.

[0070] Further, the blocking film 40 can be installed on the inlet side of the passage 11, thereby fundamentally blocking introduction of the electrolyte into the valve 100 when the pressure inside the pouch 1 is within a normal range.

[0071] The blocking film 40 can be made of a material that does not cause a chemical reaction with the electrolyte, to prevent deterioration of the performance of the electrolyte.

[0072] In the valve 100 of the present application, the auxiliary discharge hole 16 can be formed at the opposite side of the discharge hole 13, to prevent air resistance from adversely affecting sliding of the valve 100.

[0073] Further, the gasket 23 can be fitted in the gate 20 to prevent leakage of gas, and an inclined surface 22a can be formed on the post 22 to gradually discharge the gas.

[0074] Although embodiments of the present application have been described with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made thereto without departing from the spirit and scope of the application as defined in the following claims.

[0075] [REFERENCE NUMERALS] 10: main body

[0076] 11: passage

[0077] 12: chamber

[0078] 13: discharge hole

[0079] 14: gasket

[0080] 15: O-ring

[0081] 16: auxiliary discharge hole

[0082] 20: gate

[0083] 21: disc-shaped body

[0084] 22: post

[0085] 30: spring

[0086] 40: blocking film

[0087] 100: valve

Claims

1. A secondary battery in which an electrode assembly is inserted into a pouch and an electrolyte is injected into the pouch, and an edge of the pouch is sealed to form a sealed portion, the secondary battery comprising: a valve fixed to the sealed portion such that one end of the valve faces an inside of the pouch and the other end of the valve faces an outside of the pouch, wherein the valve comprises: a main body formed with a passage having one end portion that is open to the inside of the pouch, and provided with a chamber connected to the passage, wherein a discharge hole that communicates with the outside is formed in the chamber; a gate on a hook-shaped protrusion that forms a boundary between the passage and the chamber to open or close the passage; and a spring installed to exert an elastic force in a direction in which the gate is closed, wherein when gas is generated in the inside of the pouch, a pressure of the gas overcomes the elastic force of the spring, the gate is opened to discharge the gas through the discharge hole, wherein an auxiliary discharge hole is formed such that air in the chamber is discharged when the gate slides in the chamber, and wherein the auxiliary discharge hole is formed on an opposite side of the discharge hole, and the gate is located between the auxiliary discharge hole and the discharge hole.

2. The secondary battery according to claim 1, wherein An O-ring is installed at a position of the hook-shaped protrusion where the gate is provided, such that sealing is achieved when the gate is closed.

3. The secondary battery according to claim 1, wherein A barrier film for preventing penetration of the electrolyte is installed on an inlet side of the passage of the main body, and when gas is generated in the inside of the pouch to increase internal pressure, the barrier film is torn or separated from the installation position.

4. The secondary battery according to claim 3, wherein The barrier film is made of a material that does not cause a chemical reaction with the electrolyte.

5. The secondary battery according to claim 4, wherein The barrier film is manufactured as a thin film made of polypropylene or polytetrafluoroethylene.

6. The secondary battery according to claim 3, wherein The barrier film is adhered to the main body by using a pressure-sensitive adhesive.

7. The secondary battery according to claim 1, wherein The gate comprises a main body on the hook-shaped protrusion, and a post extending from the main body and protruding to be inserted into the passage, wherein a gasket having a ring shape is fitted to an outer peripheral surface of the post to seal a gap between the outer peripheral surface of the post and an inner peripheral surface of the passage.

8. The secondary battery according to claim 7, wherein An inclined surface is formed along a circumference of the post.

9. The secondary battery according to claim 1, wherein The valve is disposed in parallel to an electrode lead wire drawn from the electrode assembly and protruding to the outside of the pouch. 10.A secondary battery module manufactured by connecting a plurality of secondary batteries according to any one of claims 1 to 9 to each other.

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