Secondary batteries

Abstract

The present invention relates to a secondary battery, and more particularly, to a secondary battery including: an electrode assembly including a stack of a positive electrode, a negative electrode, and a separator; a collection unit having a negative pressure formed therein and disposed adjacent to the electrode assembly; and a battery case accommodating the electrode assembly and the collection unit, wherein the collection unit breaks when the internal pressure of the battery case exceeds a predetermined pressure, and collects gas to regulate the internal pressure.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0183714 filed on December 23, 2022, and Korean Patent Application No. 10-2023-0115683 filed on August 31, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a secondary battery, and more particularly to a secondary battery capable of regulating internal pressure by collecting gas generated inside the secondary battery. [Background technology]

[0003] Currently commercially available secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium secondary batteries. Among these, lithium secondary batteries have attracted attention due to their advantages of being free to charge and discharge due to the almost complete absence of memory effect compared to nickel-based secondary batteries, a very low self-discharge rate, and high energy density. In recent years, secondary batteries have been widely used not only in small devices such as portable electronic devices but also in medium- to large-sized devices such as automobiles and energy storage devices. Such battery packs can electrically connect multiple secondary batteries to increase capacity and output. Pouch-type secondary batteries are becoming increasingly popular due to their advantages of easy stacking and light weight. Pouch-type secondary batteries are typically manufactured by injecting an electrolyte solution into a pouch exterior with an electrode assembly housed in the pouch exterior, and then sealing the pouch exterior. Repeated charging and discharging of secondary batteries can generate gas inside.

[0004] The generated gas increases the internal pressure of the secondary battery, causing the battery case to expand. In severe cases, the increased internal pressure can cause holes in the battery case, resulting in rapid deterioration of the secondary battery. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made to solve the above problems by providing a secondary battery that can adjust the internal pressure by collecting gas inside the secondary battery when the internal pressure of the secondary battery increases to within a predetermined pressure range due to gas generated from an electrode assembly, thereby slowing down the volumetric expansion of the secondary battery. [Means for solving the problem]

[0006] According to a first embodiment of the present invention, there is provided a secondary battery including: an electrode assembly in which a positive electrode, a negative electrode, and a separator are stacked; a collection unit having a negative pressure formed therein and disposed adjacent to the electrode assembly; and a battery case accommodating the electrode assembly and the collection unit, wherein the collection unit breaks when the internal pressure of the battery case reaches a predetermined pressure, and collects gas to adjust the internal pressure.

[0007] Also, an incision line for inducing breakage may be formed on the outer surface of the collection unit. Furthermore, the collection unit may be broken when the internal pressure of the battery case is 0.1 MPa or more and 4 MPa or less.

[0008] Furthermore, the collection unit may be made of plastic or metal material.

[0009] Furthermore, the electrode assembly may have a plurality of electrode tabs formed on one surface thereof, and the collecting unit may be disposed opposite the surface on which the electrode tabs are formed.

[0010] Furthermore, the collection unit may include first collection units disposed on both sides of the electrode tab.

[0011] The collecting unit may further include a second collecting unit facing the electrode tab at an upper or lower portion of the electrode tab and having an inclined surface formed thereon corresponding to the inclination formed on the electrode tab.

[0012] Furthermore, the collection unit may include third collection units disposed above and below the electrode tabs so that the electrode tabs can be disposed in the spaces therebetween.

[0013] Furthermore, the collection unit may include a fourth collection unit disposed on one side of the electrode assembly in the longitudinal direction of the electrode assembly.

[0014] Furthermore, the collection unit may include a fifth collection unit formed in the longitudinal direction of the electrode assembly and arranged to be stacked on the upper or lower part of the electrode assembly.

[0015] According to a second embodiment of the present invention, there is provided a secondary battery module including a plurality of secondary batteries and a module case accommodating the plurality of secondary batteries, wherein the secondary batteries include an electrode assembly in which a positive electrode, a negative electrode, and a separator are stacked, a collecting unit having a negative pressure formed therein and disposed adjacent to the electrode assembly, and a battery case accommodating the electrode assembly and the collecting unit, wherein the collecting unit breaks when the internal pressure of the battery case reaches a predetermined pressure, and collects gas to adjust the internal pressure. [Effects of the Invention]

[0016] When the internal pressure of a secondary battery increases to within a predetermined range due to gas generated from an electrode assembly, the present invention can slow the increase in internal pressure and the volume expansion of the secondary battery by collecting the gas inside the secondary battery, thereby improving the lifespan of the secondary battery. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is an exploded view showing a secondary battery in which a first collection unit is housed in a first embodiment of the present invention. FIG. [Figure 2] 1(a) to 1(c) are perspective views showing embodiments of the collection unit of the present invention, including a first collection unit, a second collection unit, and a third collection unit. [Figure 3] 3 is a cross-sectional view showing the cross section of the first collection unit taken along line AA' in FIG. 2(b). FIG. [Figure 4] FIG. 3 is an exploded view showing a secondary battery in which a fourth collection unit is housed according to the first embodiment of the present invention. [Figure 5] FIG. 3 is an exploded view showing a secondary battery in which a fifth collection unit is housed in the first embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described in more detail below with reference to the drawings. However, the drawings are provided to facilitate understanding of the present invention, and are merely one embodiment of the present invention. The scope of the present invention is not limited to the scope described in the drawings. In addition, in the drawings, the same reference numerals indicate the same components, and some components may be exaggerated, reduced, or omitted to facilitate understanding of the invention.

[0019] Furthermore, the terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, based on the principle that an inventor can appropriately define the concept of a term in order to best describe his or her invention.

[0020] First embodiment Referring to FIG. 1, as one embodiment of the present invention, a secondary battery 10 may include an electrode assembly 100, a battery case 200, and a collection unit 300.

[0021] The electrode assembly 100 may have a structure in which a positive electrode current collector / positive electrode active material layer / separator / negative electrode active material layer / negative electrode current collector are stacked in this order. The positive electrode current collector includes an area coated with a positive electrode active material layer and an uncoated positive electrode uncoated area, and the positive electrode uncoated area may serve as a positive electrode tab. The negative electrode current collector includes an area coated with a negative electrode active material layer and an uncoated negative electrode uncoated area, and the negative electrode uncoated area may serve as a negative electrode tab. The separator may be formed of an electrically insulating material and disposed between the positive electrode current collector and the negative electrode current collector to prevent contact between current collectors of opposite polarities.

[0022] The electrode assembly 100 may be a stacked electrode assembly, a stack-folded electrode assembly, or a jelly roll electrode assembly.

[0023] The first electrode tab 110 may be either a positive electrode uncoated portion or a negative electrode uncoated portion of the electrode assembly 100, and may protrude and extend in one direction from one surface of the electrode assembly 100.

[0024] The first electrode tab 110 may be provided in plurality by protruding in one direction from each layer of the positive electrode uncoated portion or the negative electrode uncoated portion of the electrode assembly 100 .

[0025] The plurality of first electrode tabs 110 may be bonded to one or both surfaces of the first electrode lead 120, and at least a portion of the first electrode lead 120 may protrude outward from one side of the battery case 200. The first electrode tabs 110 may be bonded to the first electrode lead 120 by welding.

[0026] The second electrode tab 130 may be one of the positive electrode uncoated portions and the negative electrode uncoated portion, which has an opposite polarity to that of the first electrode tab 110. The second electrode tab 130 may extend from the electrode assembly 100 in another direction.

[0027] The second electrode tab 130 may be provided in plural and protrude in other directions from each layer of the positive electrode uncoated portion or the negative electrode uncoated portion of the electrode assembly 100 .

[0028] The plurality of second electrode tabs 130 may be bonded to one or both surfaces of the second electrode lead 140, and at least a portion of the second electrode lead 140 may protrude outward from the other side of the battery case 200. The second electrode tabs 130 may be bonded to the second electrode lead 140 by welding.

[0029] The first electrode lead 120 and the second electrode lead 140 may protrude in opposite directions.

[0030] The battery case 200 may include a laminated structure of a first resin layer disposed on the outer surface, a second resin layer disposed on the inner surface, and a metal layer disposed between the first and second resin layers.

[0031] Regarding the first resin layer, the insulating layer made of a polymer material must have excellent resistance to the external environment in order to protect the battery from the outside, so it is required to have excellent tensile strength and weather resistance relative to its thickness. For example, polyester-based resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin-based resins such as polyethylene and polypropylene, polystyrene-based resins such as polystyrene, polyvinyl chloride-based resins, polyvinylidene chloride-based resins, etc. can be used. These materials can be used alone or in combination of two or more, and polyethylene terephthalate, polyethylene naphthalate, etc. are preferably used.

[0032] The metal layer serves as a substrate that maintains mechanical strength and a barrier layer that prevents the penetration of moisture and oxygen. Aluminum or an aluminum alloy can be used to prevent the inflow and leakage of foreign substances such as gas and moisture, as well as to improve the strength of the battery case. Examples of aluminum alloys include alloy numbers 8079, 1N30, 8021, 3003, 3004, 3005, 3104, and 3105, which can be used alone or in combination. Of these, 8079, 1N30, 8021, and 3004 are particularly preferred for use as barrier layers.

[0033] The region of the second resin layer that is thermally fused can form a seal at the edge of the battery case 200, and the region that is not thermally fused can form the inner surface of the battery case 200. The second resin layer may be formed of a polyolefin-based resin material. CPP (Casted Polypropylene) is often used as the polyolefin-based resin layer. The second resin layer may also be formed of a material selected from the group consisting of polyolefin-based resins such as chlorinated polypropylene, polyethylene, ethylene-propylene copolymer, polyethylene-acrylic acid copolymer, and polypropylene-acrylic acid copolymer, but is not limited to these materials.

[0034] The battery case 200 may have a recessed receiving portion 210 formed therein to receive the electrode assembly 100 and the collecting unit 300. The receiving portion 210 may have a predetermined width and depth sufficient to receive the electrode assembly 100 and the collecting unit 300.

[0035] The collecting unit 300 may be configured to break when the internal pressure of the battery case 200 reaches a predetermined pressure due to gas generated by continuous and repeated charging and discharging of the electrode assembly 100. The collecting unit 300 has a negative pressure formed in its internal space. When the internal pressure of the battery case 200 reaches the predetermined pressure and breaks, gas flows into the internal space of the collecting unit 300 due to the pressure difference between the outside and inside of the collecting unit 300, thereby adjusting the internal pressure of the battery case 200. More specifically, the predetermined pressure may refer to a state in which the internal pressure of the battery case 200 is between 0.1 MPa and 4 MPa. Here, the negative pressure may refer to a state in which the internal pressure of the collecting unit 300 is lower than the internal pressure of the battery case 200.

[0036] The collection unit 300 may be disposed adjacent to the electrode assembly 100 so that a negative pressure is formed inside the collection unit 300 and the collection unit 300 is immediately damaged when the internal pressure of the battery case 200 increases due to gas generated from the electrode assembly 100.

[0037] Breakage-inducing incision lines 311, 321, 331, 341, and 351 may be formed on the outer surface of collection unit 300. Incision lines 311, 321, 331, 341, and 351 may be formed in a shape that induces breakage of collection unit 300 so that the inside and outside of collection unit 300 are in communication with each other, and may be formed in a linear shape or a geometric shape such as a circle or a square, for example, but not limited to, the shape.

[0038] The collection unit 300 may be made of a plastic material or a metal material, including, but not limited to, a plastic material such as polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), polyamides (PA), polyester (PES), polyvinyl chloride (PVC), polyurethanes (PU), polycarbonate (PC), or polyvinylidene chloride (PVDC), or a metal material such as aluminum, copper, lead, zinc, tin, iron, stainless steel, tungsten, chromium, or nickel, or an alloy of two or more of these metals.

[0039] When the internal pressure of the battery case 200 increases due to gas generated from the electrode assembly 100, the gas contained inside the battery case 200 applies pressure to the incision lines 311, 321, 331, 341, 351, which can induce the outer surface of the collection unit 300 to break along the incision lines 311, 321, 331, 341, 351.

[0040] The incision lines 311, 321, 331, 341, and 351 may be formed on the outer surface of the collection unit 300 to have a notch-shaped cross section, and the incision lines 311, 321, 331, 341, and 351 may be formed with opposite slope directions and abrupt changes so that stress is concentrated at the central apex of the notch shape. The incision lines 311, 321, 331, 341, and 351 may be induced to break first even when the same or similar pressure is applied across the entire surface of the collection unit 300 on which the incision lines 311, 321, 331, 341, and 351 are formed, by concentrating stress at the apex formed along the center in the longitudinal direction. This improves the predictability of internal pressure changes caused by repeated charging and discharging of the secondary battery 10. Furthermore, even if the secondary battery 10 is continuously and repeatedly charged and discharged, the change in the internal pressure of the secondary battery 10 can be buffered and the amount of change in the internal pressure can be reduced, thereby reducing the possibility that the battery case 200 will be damaged by the internal pressure, thereby improving the life of the secondary battery 10.

[0041] The incision lines 311, 321, 331, 341, and 351 may be formed on the outer surface of the collecting unit 300 facing the electrode assembly 100 so that when the internal pressure of the battery case 200 increases due to gas generated from the electrode assembly 100 and reaches a predetermined pressure, the incision lines 311, 321, 331, 341, and 351 are immediately broken to allow the collecting unit 300 to collect the gas. More specifically, the predetermined pressure may refer to the internal pressure of the battery case 200 being 0.1 MPa or more and 4 MPa or less.

[0042] A plurality of incision lines 311, 321, 331, 341, 351 may be formed in the collection unit 300, and the plurality of incision lines 311, 321, 331, 341, 351 may be arranged in a predetermined arrangement.

[0043] The collection unit 300 may include, as an embodiment of the collection unit 300, a first collection unit 310, a second collection unit 320, a third collection unit 330, a fourth collection unit 340, and a fifth collection unit 350. The above description of the collection unit 300 can be commonly applied to the first collection unit 310, the second collection unit 320, the third collection unit 330, the fourth collection unit 340, and the fifth collection unit 350.

[0044] Referring to (a) of FIG. 2, in a first embodiment of the collection unit 300, the first collection unit 310 may be disposed opposite the surface of the electrode assembly 100 on which the electrode tabs are formed, or may be disposed on both sides of the electrode tabs.

[0045] The first collecting units 310 may be disposed on both sides of an electrode tab protruding from one surface of the electrode assembly 100 and disposed in a space between one surface of the electrode assembly 100 and the inner surface of the battery case 200 .

[0046] The first collecting unit 310 may have a hollow space formed therein, and a negative pressure may be created in the hollow space formed therein.

[0047] The shape of the first collecting unit 310 may be, for example, a hexahedron, but is not limited thereto, and the shape of the first collecting unit 310 may be formed on both sides of the electrode tab of the electrode assembly 100 in a shape corresponding to the shape of the space formed between one surface of the electrode assembly 100 and the inner surface of the battery case 200, or in a shape similar thereto.

[0048] A first incision line 311 for inducing breakage of the first collecting unit 310 may be formed on the outer surface of the first collecting unit 310. More specifically, the first incision line 311 may be formed on the surface facing the electrode assembly 100.

[0049] When the internal pressure of the battery case 200 increases due to gas generated from the electrode assembly 100 and reaches a predetermined pressure range, the first incision line 311 may cause the first collecting unit 310 to break along the first incision line 311, thereby opening the interior of the first collecting unit 310. With the interior opened, the first collecting unit 310 may allow gas to flow into the first collecting unit 310, which is under negative pressure, thereby adjusting the average internal pressure of the battery case 200 to decrease.

[0050] The first incision line 311 may be formed in a linear or curved line, or in a shape such as a circle or a rectangle, but is not limited thereto.

[0051] 3, the cross-sectional shape of the first incision line 311 may be a notch shape, or may be a straight shape with opposite slopes on both sides of the apex so that stress is concentrated at the central apex of the notch shape. The cross-sectional shape of the first incision line 311 may induce the first incision line 311 to break first even when pressure is uniformly applied to the surface of the first collecting unit 310 on which the first incision line 311 is formed.

[0052] Referring to FIG. 2( b ), as a second embodiment of the collecting unit 300 , a second collecting unit 320 may be disposed above or below the electrode tab of the electrode assembly 100 .

[0053] In the case of a stacked or stack-folded electrode assembly 100, multiple electrode tabs protrude from one surface of the electrode assembly 100. Therefore, height differences occur between the electrode tabs depending on the thickness of the electrode assembly 100. When multiple electrode tabs are attached to one surface of an electrode lead, the electrode tabs may be inclined. The electrode tab attached to the outermost side of the electrode lead may have the steepest inclination. Therefore, the second collecting unit 320 may have an inclined surface on its upper or lower surface facing the electrode tabs, corresponding to the inclination of the outermost electrode tab, allowing the second collecting unit 320 to stably support the electrode tabs.

[0054] The second collection unit 320 may have a hollow space formed therein, and a negative pressure may be created in the hollow space formed therein.

[0055] The first collection unit 310 and the second collection unit 320 may be arranged adjacent to the electrode assembly 100 in cooperation with each other.

[0056] A second incision line 321 for inducing breakage of the second collecting unit 320 may be formed on the outer surface of the second collecting unit 320. More specifically, the second incision line 321 may be formed on the inclined surface facing the electrode tab.

[0057] The second incision line 321 may be formed in a linear or curved line, or in a shape such as a circle or a rectangle, but is not limited thereto.

[0058] The cross-sectional shape of the second incision line 321 may be a notch shape, or may be a straight shape with opposite slopes on both sides of the apex so that stress is concentrated at the central apex of the notch shape. The cross-sectional shape of the second incision line 321 may induce the second incision line 321 to break first even when pressure is uniformly applied to the surface of the second collecting unit 320 on which the second incision line 321 is formed.

[0059] Referring to (c) of FIG. 2, as a third embodiment of the collection unit 300, the third collection unit 330 may be arranged at the top and bottom so that the electrode tabs of the electrode assembly 100 can be placed in the space between the third collection units 330.

[0060] A plurality of third collecting units 330 may be provided, and the plurality of third collecting units 330 may be spaced apart by a predetermined distance in the stacking direction of the electrode assembly 100, and an electrode tab may be inserted into the space formed by the spacing.

[0061] The third collection unit 330 may have a hollow space formed therein, and a negative pressure may be created in the hollow space formed therein.

[0062] The shape of the third collection unit 330 may be, for example, a hexahedron, but is not limited thereto, and the shape of the third collection unit 330 may be formed in a shape corresponding to the upper and lower electrode tabs of the electrode assembly 100 depending on the arrangement and angle of the electrode tabs.

[0063] A third incision line 331 for inducing breakage of the third collecting unit 330 may be formed on the outer surface of the third collecting unit 330. More specifically, the third incision line 331 may be formed on the surface facing the electrode assembly 100.

[0064] The third incision line 331 may be formed in a linear or curved line, or in a shape such as a circle or a rectangle, but is not limited thereto.

[0065] The cross-sectional shape of the third incision line 331 may be a notch shape, or may be a straight shape with opposite slopes on both sides of the apex so that stress is concentrated at the central apex of the notch shape. The cross-sectional shape of the third incision line 331 may induce the third incision line 331 to break first even when pressure is uniformly applied to the surface of the third collecting unit 330 on which the third incision line 331 is formed.

[0066] Referring to FIG. 4, as a fourth embodiment of the collection unit 300, a fourth collection unit 340 may be disposed on one side of the electrode assembly 100 in the longitudinal direction of the electrode assembly 100.

[0067] The fourth collection unit 340 may have a hollow space formed therein, and a negative pressure may be created in the hollow space formed therein.

[0068] The shape of the fourth collection unit 340 may be, for example, a cylindrical or rectangular prism shape, but is not limited thereto, and the shape of the fourth collection unit 340 may be formed to correspond to the shape of the space formed between one side of the electrode assembly 100 and the inner surface of the battery case 200.

[0069] A plurality of fourth collection units 340 may be provided, and may be arranged on both sides of the electrode assembly 100 in the longitudinal direction of the electrode assembly 100.

[0070] A fourth incision line 341 for inducing breakage of the fourth collection unit 340 may be formed on the outer surface of the fourth collection unit 340. More specifically, the fourth incision line 341 may be formed on the surface facing the electrode assembly 100.

[0071] The fourth incision line 341 may be formed in a linear or curved line, or in a geometric shape such as a circle or a rectangle, but is not limited thereto.

[0072] The cross-sectional shape of the fourth incision line 341 may be a notch shape, or may be a straight shape with opposite slopes on both sides of the apex so that stress is concentrated at the central apex of the notch shape. The cross-sectional shape of the fourth incision line 341 may induce the fourth incision line 341 to break first even when pressure is uniformly applied to the surface of the fourth collecting unit 340 on which the fourth incision line 341 is formed.

[0073] Referring to FIG. 5, as a fifth embodiment of the collection unit 300, a fifth collection unit 350 may be arranged to be stacked on the upper or lower part of the electrode assembly 100 in the longitudinal direction of the electrode assembly 100.

[0074] The fifth collection unit 350 may have a hollow space formed therein, and a negative pressure may be created in the hollow space formed therein.

[0075] The shape of the fifth collection unit 350 may be, for example, a rectangular prism, etc. However, the shape is not limited thereto, and the shape of the fifth collection unit 350 may be formed to correspond to the shape of the space formed between the upper or lower part of the electrode assembly 100 and the inner surface of the battery case 200.

[0076] A plurality of fifth collection units 350 may be provided, and the plurality of fifth collection units 350 may be arranged at the top and bottom of the electrode assembly 100.

[0077] A fifth incision line 351 for inducing breakage of the fifth collection unit 350 may be formed on the outer surface of the fifth collection unit 350. More specifically, the fifth incision line 351 may be formed on the surface facing the electrode assembly 100.

[0078] The fifth incision line 351 may be formed in a linear or curved line, or in a geometric shape such as a circle or a rectangle, but is not limited thereto.

[0079] The cross-sectional shape of the fifth incision line 351 may be a notch shape, or may be a straight shape with opposite slopes on both sides of the apex so that stress is concentrated at the central apex of the notch shape. The cross-sectional shape of the fifth incision line 351 may induce the fifth incision line 351 to break first even when pressure is uniformly applied to the surface of the fifth collecting unit 350 on which the fifth incision line 351 is formed.

[0080] Second embodiment As a second embodiment of the present invention, a secondary battery module (not shown) of the present invention may include a plurality of secondary batteries 10 and a module case (not shown) that houses the plurality of secondary batteries 10. The secondary battery 10 may include an electrode assembly 100 in which a positive electrode, a negative electrode, and a separator are stacked, a battery case 200 that houses the electrode assembly 100 and a collecting unit 300, and a collecting unit 300 that has a negative pressure formed therein and is disposed adjacent to the electrode assembly 100. Details of the electrode assembly 100, the battery case 200, and the collecting unit 300 will be described above.

[0081] Although the present technology has been described above using the embodiments, the present technology is not limited thereto. The above embodiments can be modified or changed within the spirit and scope of the present technology, and those skilled in the art will understand that such modifications and changes also belong to the present technology. [Explanation of symbols]

[0082] 10 Secondary battery 100 electrode assembly 110 First electrode tab 120 First electrode lead 130 Second electrode tab 140 Second electrode lead 200 Battery Case 210 Storage unit 300 Collection Unit 310 First Collection Unit 311 First incision line 320 Second Collection Unit 321 Second incision line 330 Third Collection Unit 331 Third incision line 340 4th Collection Unit 341 4th incision line 350 5th Collection Unit 351 5th incision line

Claims

1. an electrode assembly in which a positive electrode, a negative electrode, and a separator are stacked; a collection unit in which a negative pressure is generated and which is disposed adjacent to the electrode assembly; a battery case that houses the electrode assembly and the collection unit, The collection unit comprises: The secondary battery breaks when the internal pressure of the battery case reaches a predetermined pressure, and collects gas to adjust the internal pressure.

2. The secondary battery according to claim 1 , wherein an outer surface of the collection unit is formed with a cut line for inducing breakage.

3. The collection unit comprises: The secondary battery according to claim 1 , which is broken when the internal pressure of the battery case is 0.1 MPa or more and 4 MPa or less.

4. The secondary battery according to claim 1 , wherein the collection unit is made of a plastic or metal material.

5. The electrode assembly is Multiple electrode tabs are formed on one surface. The collection unit comprises: The secondary battery according to claim 1 , wherein the electrode tab is disposed opposite to the surface on which the electrode tab is formed.

6. The collection unit comprises: The secondary battery according to claim 5 , further comprising first collection units disposed on both sides of the electrode tab.

7. The collection unit comprises: The secondary battery of claim 6 , further comprising: a second collection unit facing the electrode tab at an upper or lower portion of the electrode tab, the second collection unit having an inclined surface formed thereon corresponding to the inclination formed on the electrode tab.

8. The collection unit comprises: The secondary battery according to claim 6 , further comprising third collection units disposed above and below the electrode tabs so that the electrode tabs can be disposed in the spaces therebetween.

9. The collection unit comprises: The secondary battery according to claim 1 , further comprising a fourth collection unit disposed on one side of the electrode assembly in the longitudinal direction of the electrode assembly.

10. The collection unit comprises: The secondary battery of claim 1 , further comprising: a fifth collection unit formed in a longitudinal direction of the electrode assembly and stacked on an upper or lower portion of the electrode assembly.

11. A plurality of secondary batteries; a module case that houses the plurality of secondary batteries; The secondary battery is an electrode assembly in which a positive electrode, a negative electrode, and a separator are stacked; a collection unit in which a negative pressure is generated and which is disposed adjacent to the electrode assembly; a battery case that houses the electrode assembly and the collection unit, The collection unit comprises: The secondary battery module is configured to break when the internal pressure of the battery case reaches a predetermined pressure, and to collect gas to adjust the internal pressure.

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