Secondary battery

Abstract

The present invention provides a secondary battery provided with a pouch, in which a seal portion formed on an edge of the secondary battery when an electrode assembly and an electrolyte are encapsulated is sealed, the secondary battery including: a valve installed on the seal portion such that one end of the valve is disposed inside the pouch and the other end of the valve is disposed outside the pouch and discharges a gas generated inside the pouch to the outside, in which the valve includes an inner tube filled with an adhesive and made of a material that deforms when swelling occurs, and when swelling occurs to increase the pressure inside the pouch, a gap is generated in the portion filled with the adhesive, and the gas inside the pouch is discharged to the outside through the gap. In the present invention having the above-described configuration, the adhesive can be filled in the inner tube to prevent leakage of the electrolyte and to prevent infiltration of external moisture, but the gap is generated to discharge the gas only when the pressure inside the pouch increases, thereby effectively preventing swelling from occurring.

Description

Technical Field

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2020-0072596, filed on June 15, 2020, the entire contents of which are incorporated herein by reference.

[0002] This invention relates to a secondary battery in which an electrode assembly and electrolyte are embedded in a pouch, and more specifically, to a pouch-type secondary battery having a valve that can discharge gas to the outside when gas is generated in the pouch. Background Technology

[0003] The demand for high-efficiency rechargeable batteries is rapidly increasing in the mobile device and electric vehicle sectors. Among these rechargeable batteries, lithium-ion batteries, which have high energy density, maintain high voltage, and have low self-discharge rates, are widely used commercially, and research and development to improve their performance are actively underway.

[0004] A secondary battery has an electrode assembly and electrolyte embedded in a casing, such as a hard shell or a soft case. The electrode assembly has a structure in which a positive electrode, a separator, and a negative electrode are repeatedly stacked. Generally, electrode assemblies can be divided into wound electrode assemblies in which the positive electrode, separator, and negative electrode are wound in a stacked state to be embedded in the casing, and stacked electrode assemblies in which the positive electrode, separator, and negative electrode are cut to predetermined sizes and stacked.

[0005] Because of their helical winding structure, wound electrode assemblies are suitable for mounting on cylindrical batteries, but they are disadvantageous in terms of space utilization for prismatic or pouch batteries. On the other hand, stacked electrode assemblies, whose dimensions are adjusted when cutting electrodes and separators, easily achieve prismatic shapes that match the casing, but the manufacturing process is more complex, and stacked electrode assemblies are relatively susceptible to external impacts. Furthermore, a stacking and folding method has been developed to combine the advantages of both wound and stacked types. In this method, C-type dual cells (dual cells with a stacked structure of positive electrode / separator / negative electrode / separator / positive electrode) and A-type dual cells (dual cells with a stacked structure of negative electrode / separator / positive electrode / separator / negative electrode) are placed on a folded separator to fold the dual cells, thereby manufacturing the electrode assembly.

[0006] The electrode assembly, manufactured in various ways as described above, is mounted in a housing, such as a hard case or a soft case.

[0007] Among these batteries, pouch cells have advantages such as higher energy density per unit weight and volume, the ability to form thinner and lighter batteries, and lower cost of external materials, and therefore have seen active development in recent years. The diagram shows the state with the electrode assembly 3 installed in the pouch 1 open.Figure 1 As shown, the pouch-type secondary battery is manufactured such that the electrode assembly 3 is placed inside the pouch 1 with the upper and lower parts separated from each other, and when electrolyte is injected, the sealing portions 2a and 2b formed at the edges of the upper and lower parts are sealed. Here, the end of the electrode lead 3a extending from the electrode assembly 3 is sealed in a state that is set to protrude outward.

[0008] The problem with pouch cells is that they expand during the manufacturing process and later when used as charging / discharging devices.

[0009] This expansion is caused by the evaporation of electrolyte, which generates gas inside the soft pack 1. This deforms the appearance of the soft pack 1 and degrades the charging / discharging performance of the secondary battery. In severe cases, there is a risk of explosion.

[0010] Therefore, when gas is generated inside the soft packaging, the gas must be removed. Summary of the Invention

[0011] Technical issues

[0012] To address the aforementioned problems, one object of the present invention is to provide a secondary battery having a valve that can discharge gas to the outside when gas is generated inside the soft package, causing an increase in internal pressure.

[0013] Technical solution

[0014] To achieve the above objectives, the present invention provides a secondary battery with a pouch, wherein when the electrode assembly and electrolyte are encapsulated, a sealing portion formed on the edge of the secondary battery is sealed. The secondary battery includes a valve mounted on the sealing portion, such that one end of the valve is disposed inside the pouch and the other end of the valve is disposed outside the pouch, thereby venting gas generated inside the pouch to the outside. The valve includes an inner tube filled with an adhesive and made of a material that deforms when it expands. When expansion increases the pressure inside the pouch, a gap is created in the adhesive-filled portion, and gas inside the pouch is vented to the outside through the gap.

[0015] The valve may include an outer tube mounted on a sealing portion, such that one end of the valve is located inside the soft housing and the other end of the valve is located outside the soft housing, and is mounted such that an inner tube is inserted into the outer tube in the longitudinal direction, the ends of the outer tube and the inner tube can be connected to each other for sealing, such that a chamber is formed between the outer tube and the inner tube, the chamber is a sealed space, and the inner tube can deform within the outer tube.

[0016] The outer tube can be made of a material that does not deform even when expansion occurs, and the inner tube can deform when expansion occurs to increase the pressure inside the soft package, causing the volume of the chamber to shrink.

[0017] The outer tube and the inner tube can be made of polypropylene, which is included as a material in the soft package. The outer tube can be manufactured to have lower flexibility and higher rigidity compared to the inner tube, and the inner tube can be manufactured to have higher flexibility and lower rigidity compared to the outer tube.

[0018] Gaseous nitrogen (N2) can be injected into the chamber, and other stable gases can be used instead of gaseous nitrogen (N2).

[0019] The outer tube and the inner tube can each have a circular cross-section or an elliptical cross-section, respectively.

[0020] The adhesive can be a material containing epoxy adhesives. The adhesive can also be a material containing acrylate adhesives.

[0021] Multiple hooks can be installed on one and another facing surfaces inside the inner tube, so that the hooks are physically connected to each other as hook-and-loop fasteners.

[0022] The gaps formed in the inner tube after the gas is discharged can be refilled.

[0023] The valve can be configured to be parallel to the electrode leads, which extend from the electrode assembly and protrude to the outside of the soft package.

[0024] The present invention may further provide a secondary battery module which is manufactured by connecting a plurality of secondary batteries having the above configuration to each other.

[0025] Beneficial effects

[0026] In the present invention with the above configuration, the adhesive can be filled in the inner tube to prevent electrolyte leakage and external moisture infiltration, but gaps are only created to release gas when the pressure inside the soft pack increases, thereby effectively preventing expansion.

[0027] By placing the inner tube inside the outer tube to deform the inner tube and increase its diameter, the inner tube can be protected from external impacts.

[0028] Gaseous nitrogen can be injected into the chamber formed between the inner and outer tubes to protect the inner tube, and the gaseous nitrogen will contract when the inner tube expands to promote the formation of gaps in the adhesive.

[0029] In addition, multiple hooks can be installed on one and another facing surfaces inside the inner tube, so that these hooks are physically connected to each other by hook and loop fasteners, in order to adjust the internal pressure standard within the soft pack that creates gaps in the adhesive, as well as the expansion rate of the gaps. Attached Figure Description

[0030] Figure 1 This is a perspective view showing the electrode assembly installed with the soft case open;

[0031] Figure 2 This is a diagram showing the state in which the valve according to the first embodiment of the present invention is installed in a pouch-type secondary battery;

[0032] Figure 3 This is a cross-sectional view of the valve according to the first embodiment of the present invention;

[0033] Figure 4 This is a cross-sectional view showing the state in which a gap g is generated in the adhesive in a valve according to a first embodiment of the present invention;

[0034] Figure 5 These are longitudinal cross-sectional views and cross-sectional views (left) when the valve according to the first embodiment of the present invention is in a normal state, and longitudinal cross-sectional views and cross-sectional views (right) when gas is generated inside the soft package and the internal pressure increases;

[0035] Figure 6 This is a cross-sectional view of a valve according to a second embodiment of the present invention. Detailed Implementation

[0036] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can readily implement the inventive concept. However, the present invention may be embodied in different forms and should not be construed as limited to the embodiments set forth herein.

[0037] For the sake of clarity in describing the invention, components that are not relevant to the description are omitted, and throughout the specification, the same reference numerals are assigned to the same or similar components.

[0038] Furthermore, the terms or words used in this specification and claims should not be construed as having their conventional or dictionary-based meanings, but rather should be understood as having meanings and concepts that are within the scope of this invention, based on the principle that the inventor can appropriately define the concepts of the terms in order to best describe and illustrate his or her invention.

[0039] This invention relates to a secondary battery with a pouch 1, wherein when the electrode assembly 3 and the electrolyte are encapsulated, sealing portions 2a and 2b formed on the edge 2 are sealed. More specifically, it relates to a secondary battery with a valve 10, which allows gas to be discharged to the outside when gas is generated inside the pouch 1, increasing the internal pressure. Embodiments according to the invention will now be described with reference to the accompanying drawings.

[0040] First Embodiment

[0041] Figure 2 This is a diagram showing the state in which the valve according to the first embodiment of the present invention is installed in a pouch-type secondary battery. Figure 3 This is a cross-sectional view of the valve according to the first embodiment of the present invention. Figure 4 This is a cross-sectional view showing the state in which a gap g is generated in the adhesive in a valve according to a first embodiment of the present invention.

[0042] Refer to the attached diagram, as follows Figure 2 As shown, the secondary battery according to this specification includes a valve 10. The valve 10 is mounted such that one end of the valve 10 is located inside the soft case and the other end of the valve 10 is located outside the soft case (more specifically, the valve 10 is mounted between seals that are bonded together). That is, the valve 10 is arranged parallel to the electrode lead 3a, which extends from the electrode assembly and protrudes outside the soft case at intervals.

[0043] The valve 10 has the function of discharging the gas generated inside the soft package 1 to the outside, and has the following structure: the channel formed in the tube 10 connecting the inside and outside of the soft package 1 is blocked by the adhesive 13 in the tube 10.

[0044] In other words, such as Figure 3 As shown, valve 10 includes: an inner tube 11 having one end disposed inside the soft package 1 and another end disposed outside the soft package 1, and filled with adhesive 13; and an outer tube 12, which is mounted on the sealing portion such that one end is disposed inside the soft package 1 and the other end is disposed outside the soft package 1, and is also mounted such that the inner tube 11 is inserted into the interior of the outer tube 12 in the longitudinal direction.

[0045] The inner tube 11 is made of a material that can deform when the pressure increases due to expansion within the soft pack. Therefore, when the internal pressure increases, a gap g is created in the portion filled with adhesive 13, and when the gap g opens the adhesive 13 along the longitudinal direction of the inner tube 11, the gas inside the soft pack is discharged to the outside through the gap g.

[0046] Here, the two ends of the outer tube 12 and the inner tube 11 are connected to each other and sealed, so that a chamber C is formed between the outer tube 12 and the inner tube 11, and the chamber C is a sealed space. The inner tube 11 can deform within the outer tube 12 in the direction of its diameter expansion.

[0047] The outer tube 12 is made of a material that does not deform even when expansion occurs. Therefore, when expansion occurs and the pressure inside the soft package 1 increases, the inner tube 11 deforms, causing the volume of the chamber C to shrink.

[0048] In other words, when the gas pressure acts on the end of the inner tube 11 inside the flexible package 1, stress acts on the surface of the adhesive 13, therefore, as Figure 4As shown, at least one or more gaps g (with) are generated. Figure 4 Different shapes can create a gap at the edge or center. That is, although in Figure 4 Multiple gaps g were formed in the middle, and Figure 5 The passage for gas is shown by a single arrow, but depending on the type or kind of adhesive, multiple gaps g or a single gap g can be formed. Furthermore, the gaps can have various sizes.

[0049] like Figure 5 As shown, it shows a longitudinal cross-sectional view and a cross-sectional view (upper and lower left) when the valve 10 is in the normal state, and a longitudinal cross-sectional view and a cross-sectional view (upper and lower right) when gas is generated inside the soft package and the internal pressure increases. Due to the continuous pressure applied to the gap g, the gap g expands in the length direction of the inner tube 11 and opens to the outside of the inner tube 11.

[0050] Therefore, the gas inside the soft package 1 is discharged to the outside along the channel opened by the gap g. As the gap g is formed and widened, the diameter of the inner tube 11 increases, causing the chamber C to contract.

[0051] Here, since the shape of the outer tube 12 does not deform, the contraction of the gas in chamber C and the expansion of the inner tube 11 can occur simultaneously. Because the contraction of the air inside chamber C and the increase in the diameter of the inner tube 11 occur simultaneously, the size of the gap g that allows the free volume of the adhesive 13 to increase will increase, thus forming a channel through which the gas is discharged.

[0052] Preferably, the outer tube 12 and the inner tube 11 are made of polypropylene, which is the material contained in the soft package so that the soft package 1 is sealed when sealed.

[0053] However, the outer tube 12 is manufactured to have lower flexibility and higher rigidity compared to the inner tube 11, and the inner tube 11 is manufactured to have higher flexibility and lower rigidity compared to the outer tube 12. Thus, flexibility and rigidity can be adjusted by controlling molding conditions or adding additives.

[0054] Alternatively, gaseous nitrogen (N2) can be injected into chamber C, or other stable gases can be injected instead of gaseous nitrogen.

[0055] Preferably, the outer tube 12 and the inner tube 11 have circular or elliptical cross-sections, respectively, so that the pressure applied in all directions is relatively uniform, but they can be manufactured with square or other polygonal cross-sections. Furthermore, the outer tube 12 and the inner tube 11 can be manufactured such that the portion inside the soft package 1 has a relatively large diameter, while the opposing portion has a relatively small diameter, in order to effectively apply gas pressure.

[0056] Additionally, the adhesive 13 can be a material containing an epoxy adhesive or a material containing an acrylic adhesive. The adhesive 13 can be selected from various materials that do not react with the electrolyte, and can be filled into the inner tube 11 in the form of a gel or a gel and a soft solid.

[0057] Furthermore, in this invention, the gap g formed in the inner tube 11 after gas discharge can be refilled. Therefore, the valve 10 according to the invention can repeatedly provide a sealing function after repeated gas discharge until the end of the secondary battery's life.

[0058] Second Embodiment

[0059] Figure 6 This is a cross-sectional view of a valve according to a second embodiment of the present invention. Similar to the first embodiment, the valve 10 according to this embodiment has an inner tube 11 disposed inside an outer tube 12 and the inner tube 11 filled with an adhesive 13. Furthermore, to increase physical bonding strength, such as... Figure 6 As shown, multiple hooks 14 are also installed.

[0060] In other words, the inner circumferential surface of the inner tube 11 is provided with a plurality of pairs of hooks 14 to increase the bonding force in a specific direction.

[0061] Since the hooks 14 are physically connected to each other by a hook and loop fastener method (i.e., a Velcro tape connection method), the pressure that creates the gap g and the rate at which the gap widens can be reduced.

[0062] In the present invention with the above configuration, the adhesive 13 can be filled in the inner tube 11 to prevent electrolyte leakage and external moisture infiltration, but gap g is only created to release gas when the pressure inside the soft pack increases, thereby effectively preventing expansion.

[0063] Since the inner tube 11 is placed inside the outer tube 12, the inner tube 11 is deformed to increase its diameter. Therefore, the inner tube 11 can be protected by the outer tube 12 from external impacts.

[0064] Gaseous nitrogen can be injected into the chamber C formed between the inner tube 11 and the outer tube 12 to protect (buffer) the inner tube 11, and the gaseous nitrogen can contract when the inner tube 11 expands to promote the creation of gaps in the adhesive.

[0065] In addition, multiple hooks 14 can be installed on one and another facing surfaces inside the inner tube 11, so that the hooks are physically connected to each other in the manner of hook and loop fasteners, in order to adjust the internal pressure standard inside the soft package that creates the gap g in the adhesive 13 and the expansion rate of the gap.

[0066] Although embodiments of the invention have been described with reference to specific examples, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the concept and scope of the invention as defined in the following claims.

[0067] [Figure Labels]

[0068] 10: Valve

[0069] 11: Inner tube

[0070] 12: External pipe

[0071] 13: Adhesive

[0072] 14: Hook

[0073] C: Chamber

[0074] g: gap

Claims

1. A secondary battery, wherein the secondary battery is provided with a soft pack, wherein, When the electrode assembly and electrolyte are encapsulated, a sealing portion formed at the edge of the secondary battery is sealed, the secondary battery comprising: A valve is mounted on the sealing portion such that one end of the valve is located inside the soft housing, and the other end of the valve is located outside the soft housing. The valve includes an inner tube filled with an adhesive and made of a material that deforms when it expands. When expansion occurs, increasing the pressure inside the flexible pack, gaps are created in the portion filled with the adhesive, and the gas inside the flexible pack is discharged to the outside through these gaps. The valve includes an outer tube mounted on the sealing portion, with one end of the outer tube positioned inside the flexible housing and the other end positioned outside the flexible housing. The outer tube is installed such that the inner tube is inserted into the outer tube in the longitudinal direction. The outer tube and the inner tube are connected at both ends to be sealed, forming a chamber between the outer tube and the inner tube. This chamber is a sealed space. The inner tube is deformed inside the outer tube.

2. The secondary battery according to claim 1, wherein, The outer tube is made of a material that does not deform even when expansion occurs, and When expansion occurs, increasing the pressure inside the soft package, the inner tube deforms to cause the volume of the chamber to shrink.

3. The secondary battery according to claim 2, wherein, The outer tube and the inner tube are both made of polypropylene, which is a material included in the soft package. The outer tube is manufactured to have lower flexibility and higher rigidity compared to the inner tube.

4. The secondary battery according to claim 1, wherein, Gaseous nitrogen (N2) is injected into the chamber.

5. The secondary battery according to claim 1, wherein, The outer tube and the inner tube each have a circular cross-section or an elliptical cross-section.

6. The secondary battery according to claim 1, wherein, The adhesive comprises an epoxy adhesive.

7. The secondary battery according to claim 1, wherein, The adhesive comprises an acrylic adhesive.

8. The secondary battery according to claim 1, wherein, Multiple hooks are respectively installed on one and another facing surfaces inside the inner tube, such that the hooks are physically connected to each other in the manner of hook and loop fasteners.

9. The secondary battery according to claim 1, wherein, The gap formed in the inner tube after the gas is discharged is refilled.

10. The secondary battery according to claim 1, wherein, The valve is configured to be parallel to the electrode leads, which extend from the electrode assembly and protrude to the outside of the soft package.

11. A secondary battery module manufactured by connecting a plurality of secondary batteries according to any one of claims 1 to 10 to each other.

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