Secondary batteries

Abstract

The present invention relates to a secondary battery, and more specifically, the present invention provides a secondary battery including: an electrode assembly in which a positive electrode, a negative electrode, and a separator are stacked; a first case that houses the electrode assembly and breaks when an internal pressure exceeds a predetermined pressure; and a second case that houses the first case in an internal space under negative pressure and collects gas discharged from the first case.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0183715 filed on December 23, 2022 and Korean Patent Application No. 10-2023-0115741 filed on August 31, 2023, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a secondary battery, and more particularly to a secondary battery capable of adjusting its internal pressure by collecting gas therein. [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 easily chargeable and dischargeable due to their minimal memory effect compared to nickel-based secondary batteries, their extremely low self-discharge rate, and their 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- and 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 housing an electrode assembly and then sealing the pouch housing. 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 above a predetermined level due to gas generated from an electrode assembly. [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 first case that houses the electrode assembly and breaks when an internal pressure exceeds a predetermined pressure; and a second case that houses the first case in an internal space under negative pressure and collects gas discharged from the first case.

[0007] The second case has a collection space for collecting gas between the inner surface of the second case and the outer surface of the first case.

[0008] Furthermore, the first case of the collection unit may be provided with a cut line for inducing breakage.

[0009] Furthermore, the second case may be made of metal or plastic material so as to be able to support the external shape.

[0010] The battery may further include a first electrode lead protruding from one surface of the first case and electrically connected to the electrode assembly, the first electrode lead passing through one surface of the second case.

[0011] Furthermore, a lead film may be attached to the area where the first electrode lead passes through the second case so as to seal the second case.

[0012] Furthermore, the lead film may be heat-sealed to seal the second case.

[0013] Furthermore, the second case may be provided with an exhaust hole through which gas can be discharged from the internal space.

[0014] Furthermore, the second case may include an opening / closing unit that opens and closes the exhaust hole.

[0015] Furthermore, the second case may further include a position fixing unit that fixes the position of the first case.

[0016] 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 first case accommodating the electrode assembly, and a second case having a negative pressure inside and accommodating the first case, wherein the second case collects gas discharged from the first case. [Effects of the Invention]

[0017] When the internal pressure of a secondary battery increases above a predetermined level due to gas generated from an electrode assembly, the present invention can slow the increase in internal pressure by collecting gas inside the secondary battery, thereby improving the lifespan of the secondary battery. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view showing the external shape of a secondary battery according to a first embodiment of the present invention. [Figure 2] FIG. 3 is an exploded view showing the cover frame and the storage frame separated to show the interior of the second case in the first embodiment of the present invention. [Figure 3] FIG. 2 is an exploded view showing an electrode assembly housed in a first case in the first embodiment of the present invention. [Figure 4] 3 is a cross-sectional view showing the state of a cross section of the first case taken along line AA' in FIG. 2 in the first embodiment of the present invention. FIG. [Figure 5]10 is a cross-sectional view showing a state in which a floating portion in the discharge unit of the present invention closes a discharge hole. FIG. [Figure 6] 10 is a cross-sectional view showing a state in which a floating portion in the discharge unit of the present invention opens a discharge hole. FIG. [Figure 7] 2 is an enlarged perspective view of part "A" in FIG. 1, showing the process in which the exhaust hole is opened and closed by the opening and closing unit. FIG. [Figure 8] FIG. 2 is a plan view showing the state of a storage frame in the first embodiment of the present invention. [Figure 9] FIG. 10 is a diagram showing a configuration in which a plurality of first cases are housed in a second case. DETAILED DESCRIPTION OF THE INVENTION

[0019] 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.

[0020] 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 explain his or her invention.

[0021] First embodiment Referring to FIGS. 1 and 2, as a first embodiment of the present invention, a secondary battery 10 of the present invention may include an electrode assembly 100, a first case 200, and a second case 300.

[0022] 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 electrical insulating material and disposed between the positive electrode current collector and the negative electrode current collector to prevent contact between collectors of opposite polarities.

[0023] The electrode assembly 100 may be a stacked electrode assembly, a stack-folded electrode assembly, or a jelly roll electrode assembly.

[0024] 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.

[0025] Referring to FIG. 3, 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.

[0026] 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 from one surface of the first case 200. The first electrode tabs 110 may be bonded to the first electrode lead 120 by welding.

[0027] 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.

[0028] 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 .

[0029] The plurality of second electrode tabs 130 may be joined to one or both surfaces of the second electrode lead 140, and at least a portion of the second electrode lead 140 may protrude from the other surface of the first case 200. The second electrode tabs 130 may be joined to the second electrode lead 140 by welding.

[0030] The first electrode lead 120 and the second electrode lead 140 may protrude in opposite directions.

[0031] The first 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 resin layer and the second resin layer.

[0032] The first resin layer is an insulating layer made of a polymer material that must have excellent resistance to the external environment in order to protect the battery from the outside, and therefore 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. These materials can be used alone or in combination of two or more, and polyethylene terephthalate, polyethylene naphthalate, etc. are preferably used.

[0033] 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.

[0034] The second resin layer may be formed of a polyolefin-based resin material, such as polyolefin-based resins, such as chlorinated polypropylene, polyethylene, ethylene-propylene copolymers, polyethylene-acrylic acid copolymers, and polypropylene-acrylic acid copolymers, but is not limited to these materials.

[0035] The first case 200 may have a recessed receiving portion 210 formed therein to receive the electrode assembly 100. The receiving portion 210 may have a predetermined width and depth sufficient to receive the electrode assembly 100.

[0036] The first case 200 may be damaged if the internal pressure exceeds a predetermined pressure due to gas generated by continuous and repeated charging and discharging of the electrode assembly 100.

[0037] The first case 200 may be formed with a cut line 220 that induces breakage when the internal pressure of the first case 200 exceeds a predetermined pressure.

[0038] The incision line 220 may be formed on the outer surface or inner surface of the first case 200, or a plurality of incision lines 220 may be formed on the outer surface or inner surface of the first case 200. The plurality of incision lines 220 may be arranged in a predetermined arrangement.

[0039] When the internal pressure of the first case 200 increases due to gas generated from the electrode assembly 100, the pressure applied to the incision line 220 can induce the outer surface of the first case 200 to break along the incision line 220. When the outer surface of the first case 200 breaks along the incision line 220, gas discharged from the first case 200 can be collected in the internal space of the second case 300 that houses the first case 200.

[0040] Referring to FIG. 4, the cross-sectional shape of the incision line 220 may be a notch shape, or may be a straight line shape with opposite slopes on both sides of the notch centered on the apex so that stress is concentrated at the apex. The cross-sectional shape of the incision line 220 can induce the incision line 220 to break first even when pressure is uniformly applied to the inner surface of the first case 200 on which the incision line 220 is formed. This can improve the predictability of internal pressure changes caused by repeated charging and discharging of the secondary battery 10. Furthermore, even when the secondary battery 10 is continuously and repeatedly charged and discharged, changes in internal pressure of the secondary battery 10 can be buffered, reducing the possibility of damage to the secondary battery 10 and thereby improving the lifespan of the secondary battery 10.

[0041] The incision line 220 may be formed in a linear or curved line, or in a shape such as a circle or a square, but is not limited thereto.

[0042] The position where the incision line 220 is formed may be a position adjacent to the collection space 330 of the second case 300, but is not limited thereto.

[0043] The first case 200 may further include a discharge unit 230 and a discharge hole 221 .

[0044] The discharge hole 221 may be a hole formed on one surface of the first case 200 so as to penetrate the first case 200 .

[0045] Referring to FIG. 5, a discharge unit 230 is coupled to the discharge hole 221, and the discharge unit 230 may open or close the discharge hole 221 depending on the difference in internal pressure between the first case 200 and the second case 300.

[0046] The discharge unit 230 may include a support portion 231 and a floating portion 232 .

[0047] The support part 231 may be coupled to one surface of the first case 200 along the edge of the discharge hole 221 formed in the first case 200 .

[0048] The support part 231 is formed to protrude outward from one surface of the first case 200, and may have a hollow penetrating the center so that the inside of the first case 200 and the inside of the second case 300 can communicate with each other.

[0049] A floating portion 232 may be disposed in the hollow that passes through the center of the support portion 231 .

[0050] The floating part 232 may be disposed such that one surface faces the discharge hole 221 and the other surface faces the internal space of the second case 300, so that one surface of the floating part 232 is pressurized by the internal pressure of the first case 200 via the discharge hole 221, and the other surface is pressurized by the internal pressure of the second case 300. Therefore, the floating part 232 can move in the longitudinal direction of the support part 231 within the hollow of the support part 231 due to the difference in internal pressure between the first case 200 and the second case 300.

[0051] A connecting hole 231a may be formed on the side surface of the support portion 231, penetrating the side surface of the support portion 231. The connecting hole 231a may be open or closed depending on the position of the loose portion 232 in the hollow of the support portion 231.

[0052] For example, when the internal pressure of the first case 200 is lower than the internal pressure of the second case 300, the floating part 232 is positioned to closely contact the discharge hole 221 due to the difference between the pressure applied to one side and the pressure applied to the other side, and one side of the floating part 232 can close the discharge hole 221. At this time, the side of the floating part 232 can closely contact the connecting hole 231a formed on the inner side of the support part 231 to close the connecting hole 231a.

[0053] 6, when the internal pressure of first case 200 is greater than the internal pressure of second case 300, floating part 232 can move away from exhaust hole 221 due to the difference in pressure between one side and the other side of support part 231. At this time, floating part 232 can open exhaust hole 221 and connecting hole 231a, and gas inside first case 200 can be exhausted to the internal space of second case 300 through exhaust hole 221 and connecting hole 231a.

[0054] The inner end of the support portion 231 may be formed with a locking step portion 231b that protrudes from the inner surface so as to limit the range of movement of the floating portion 232.

[0055] The second case 300 may have a hollow interior space, and negative pressure may be generated in the hollow interior space to accommodate the first case 200. Here, the negative pressure may refer to a state in which the pressure in the hollow interior space of the second case 300 is lower than the pressure outside the second case 300.

[0056] The internal space of the second case 300 is at a negative pressure, so the pressure is lower than the pressure inside the first case 200. When the internal space of the first case 200 and the internal space of the second case 300 are connected by forming a hole in the first case 200, for example, gas generated in the internal space of the first case 200 flows into the internal space of the second case 300 due to the pressure difference.

[0057] The second case 300 may have a collection space 330 formed in a space between the inner surface of the second case 300 and the outer surface of the first case 200. The collection space 330 may collect gas discharged from the first case 200.

[0058] The second case 300 may be formed of a rigid metal or plastic material to maintain its external shape. For example, the second case 300 may be formed of a plastic material such as polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), polyamides (PA), polyester (PES), polyvinyl chloride (PVC), polyurethane (PU), polycarbonate (PC), polyvinylidene chloride (PVDC), phenolic resin, melamine resin, silicone resin, urea resin, amino resin, or epoxy resin, or a metal such as aluminum, copper, lead, zinc, tin, iron, stainless steel, tungsten, chromium, or nickel, or an alloy of two or more of these metals. As a result, the second case 300 can maintain its shape without deformation even when the internal pressure increases due to gas discharged from the first case 200.

[0059] The widest surface of the outer surface of the second case 300 is flat and formed in a smooth shape, so that a plurality of second cases 300 can be effectively stacked.

[0060] The second case 300 may include a cover frame 310 and a receiving frame 320 .

[0061] The receiving frame 320 has one open side so as to receive the first case 200, and can communicate with the internal space receiving the first case 200 through the open side.

[0062] The shape of the accommodation frame 320 may be, for example, a hexahedron or a cylinder, but is not limited to these.

[0063] The receiving frame 320 may be formed in a structure in which the other sides except for one open side are closed.

[0064] The receiving frame 320 may have a coupling groove 321 formed therein to which the first electrode lead 120 can be coupled.

[0065] The coupling groove 321 may be formed as a recess with a predetermined depth and width in an edge region facing the cover frame 310. A plurality of coupling grooves 321 may be formed on one edge and the other edge of the receiving frame 320.

[0066] The coupling groove 321 may be formed in a central region of the edge or in a region offset in one direction along the edge depending on the position where the first case 200 is disposed inside the second case 300.

[0067] The cover frame 310 may be coupled to the open side of the receiving frame 320 to seal the second case 300 .

[0068] The cover frame 310 may be formed with a pressure unit 313 protruding from a surface facing the receiving frame 320. The pressure unit 313 may be formed at a position corresponding to the coupling groove 321. The pressure unit 313 may be inserted into the coupling groove 321 when the cover frame 310 and the receiving frame 320 are coupled together.

[0069] The protruding height of the pressure unit 313 may be shorter than the depth of the coupling groove 321 .

[0070] The first electrode lead 120 may penetrate one surface of the second case 300, and the second electrode lead 140 may penetrate the other surface of the second case 300. Here, the first electrode lead 120 and the second electrode lead 140 may be attached to coupling grooves 321 formed on one and the other edges of the receiving frame 320.

[0071] Lead films 400, 410 may be attached to an area where the first electrode lead 120 penetrates the second case 300 to seal the second case 300. The first electrode lead 120 and the second electrode lead 140 are attached to a coupling groove 321 to penetrate the second case 300, and gas may enter the inside of the second case 300 from the outside through a gap formed between the coupling groove 321 and the first electrode lead 120 or between the coupling groove 321 and the second electrode lead 140, so lead films 400, 410 may be attached to seal the gas.

[0072] The lead film comprises an electrically insulating material, which may be, for example, but is not limited to, polypropylene, polyethylene, or other materials.

[0073] The lead films 400, 410 may surround the first electrode lead 120 and the second electrode lead 140 and be installed in the coupling groove 321. The lead films 400, 410 may include a first lead film 400 and a second lead film 410, where the first lead film 400 may be a film that surrounds the first electrode lead 120 and is installed in the coupling groove 321, and the second lead film 410 may be a film that surrounds the second electrode lead 140 and is installed in the coupling groove 321.

[0074] The lead films 400, 410 are melted by heat, and the melted lead films 400, 410 can be adhered to the coupling groove 321 and the first electrode lead 120 or the coupling groove 321 and the second electrode lead 140 by pressure, and can be cooled in this adhered state to seal the second case 300.

[0075] The pressure unit 313 formed on the cover frame 310 is formed at a position corresponding to the coupling groove 321 and protrudes toward the coupling groove 321, so that when the cover frame 310 and the receiving frame 320 are coupled together, the pressure can be applied to the molten lead films 400, 410. The lead films 400, 410 compressed by the pressure unit 313 can be brought into close contact with the coupling groove 321 and the first electrode lead 120 or the coupling groove 321 and the second electrode lead 140, and can be cooled in this tight contact state to seal the second case 300.

[0076] The second case 300 may have an exhaust hole 311 formed therein to exhaust gas from the interior space. More specifically, the cover frame 310 may have an exhaust hole 311 formed therein to exhaust gas from the interior space of the second case 300.

[0077] The second case 300 may be formed with a hole unit 311a that forms the exhaust hole 311. A threaded surface may be formed on the outer surface of the hole unit 311a so as to protrude.

[0078] 7, the cover frame 310 may further include an opening / closing unit 312 that can open and close the exhaust hole 311. The opening / closing unit 312 can be attached to and detached from the hole unit 311a. When the opening / closing unit 312 is attached to the hole unit 311a, the exhaust hole 311 is closed, preventing gas from flowing into or out of the second case 300 through the exhaust hole 311. When the opening / closing unit 312 is detached from the hole unit 311a, the exhaust hole 311 is opened, allowing gas to flow into or out of the second case 300 through the exhaust hole 311.

[0079] The opening / closing unit 312 may have an inner surface formed with a threaded surface corresponding to the threaded surface of the hole unit 311a, so that the opening / closing unit 312 and the hole unit 311a are screwed together.

[0080] When the opening-closing unit 312 is completely coupled to the hole unit 311a, the opening-closing unit 312 may be formed so as not to protrude from the outermost side surface of the cover frame 310. When stacking secondary batteries 10, if the opening-closing unit 312 protrudes from the outermost side surface of the cover frame 310, it becomes difficult to stack the secondary batteries 10 and the volume increases unnecessarily. Therefore, the opening-closing unit 312 may be formed so as not to protrude from the outermost side surface of the cover frame 310 even when completely coupled to the hole unit 311a.

[0081] As a first embodiment of a method for creating a negative pressure state in the internal space of the second case 300, the method may include a first case sealing step and a second case sealing step. The first case sealing step may include a step of discharging gas from the inside of the first case 200 to create a negative pressure, and a step of sealing the first case 200 with the negative pressure created inside. If negative pressure were created only inside the second case 300, the first case 200 may expand due to the difference in internal pressure between the first case 200 and the second case 300, which may result in damage to the first case 200. Therefore, the first case sealing step can create a negative pressure inside the first case 200. The second case sealing step may be a step of sealing the first case 200 containing the electrode assembly after it is housed in the second case 300, and may further include a step of discharging gas from the sealed second case 300 to create a negative pressure inside the second case 300. During the process of creating a negative pressure inside the second case 300, the internal pressure of the second case 300 decreases, which may cause the first case 200 disposed inside the second case 300 to expand. However, to minimize expansion of the first case 200, the internal pressure of the second case 300 and the internal pressure of the first case 200 may be set to the same or similar pressure. For example, after the first case sealing step is performed at a pressure of 0.04 MPa to seal the first case, the second case sealing step may also be performed at a pressure of 0.04 MPa.

[0082] As a second example of a method for creating a negative pressure in the internal space of second case 300, when gas inside second case 300 is exhausted through exhaust hole 311 by an inhalation device (not shown) during the process of creating a negative pressure inside second case 300, the internal pressure of the second case decreases, creating a difference between the internal pressures of first case 200 and second case 300. At this time, first case 200 may expand, potentially damaging first case 200. Therefore, to prevent damage to first case 200, first case 200 may further include exhaust unit 230. When gas inside second case 300 is sucked through exhaust hole 311 to create a negative pressure inside second case 300, the gas inside first case 200 can be exhausted through exhaust unit 230, thereby preventing first case 200 from expanding and being damaged.

[0083] The receiving frame 320 may have a position fixing unit 322 formed thereon.

[0084] Referring to FIG. 8, the position fixing unit 322 may be formed on the bottom surface inside the accommodating frame 320 and configured to fix the position of the first case 200 attached inside the accommodating frame 320.

[0085] The position fixing unit 322 may be formed to protrude upward from the bottom surface of the interior of the accommodating frame 320, and may be formed at a position corresponding to the position of each vertex of the bottom surface of the first case 200 facing the bottom surface of the interior of the accommodating frame 320.

[0086] Each vertex of the bottom surface of the first case 200 may be fitted into a position fixing unit 322, and the position of the first case 200 may be fixed so that it does not move freely in a direction horizontal to the bottom surface inside the receiving frame 320.

[0087] The position fixing unit 322 may be formed to include a folded shape, and the first case 200 may be arranged so that the apex of the first case 200 is located in the folded inner region of the position fixing unit 322.

[0088] A plurality of position fixing units 322 may be formed, and the plurality of position fixing units 322 may be arranged at positions corresponding to the four vertices of the bottom surface of the first case 200. Since the positions of the four vertices of the first case 200 are fixed by the position fixing units 322, the position of the first case 200 is stably fixed so as not to move freely in a direction horizontal to the bottom surface inside the receiving frame 320.

[0089] 9, a secondary battery can be manufactured in such a manner that a plurality of first cases 200 are housed in a second case 300. In this case, a larger battery capacity can be realized.

[0090] The second case 300 may also function as a type of battery module. That is, the first case 200, which houses an electrode assembly in which a positive electrode, a negative electrode, and a separator are stacked and breaks when the internal pressure exceeds a predetermined pressure, may function as a single secondary battery. A plurality of such first cases 200 may be housed inside the second case 300, and the first cases 200 may be electrically connected to each other. The first cases 200 may also be housed in the second case 300, electrically connected and managed in this manner. In this case, the second case 300 housing the plurality of first cases 200 therein may function as a single battery module as a whole.

[0091] In this case, the second case 300 can also be configured to house the first case 200 in an internal space where a negative pressure is created, and to collect gas discharged from the first case 200.

[0092] 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 plurality of secondary batteries 10 may include an electrode assembly 100 in which a positive electrode, a negative electrode, and a separator are stacked, a first case 200 that houses the electrode assembly 100, and a second case 300 that has a negative pressure formed in its internal space and houses the first case 200. Details of the electrode assembly 100, the first case 200, and the second case 300 will be described above.

[0093] 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]

[0094] 10 Secondary battery 100 electrode assembly 110 First electrode tab 120 First electrode lead 130 Second electrode tab 140 Second electrode lead 200 Case 1 210 Storage unit 220 Incision Line 300 Case 2 310 Cover Frame 311 Exhaust vent 311a hole unit 312 Opening and closing unit 313 Pressurizing Unit 320 Storage Frame 321 Connection groove 322 Position Fixation Unit 330 Collection space 400 First Lead Film 410 Second Lead Film

Claims

1. an electrode assembly in which a positive electrode, a negative electrode, and a separator are stacked; a first case that houses the electrode assembly and that breaks when an internal pressure of the first case exceeds a predetermined pressure; a second case that houses the first case in an internal space under negative pressure and collects gas discharged from the first case.

2. The secondary battery according to claim 1 , wherein the second case has a collection space for collecting gas between an inner surface of the second case and an outer surface of the first case.

3. The secondary battery according to claim 1 , wherein the first case is provided with a cut line for inducing breakage.

4. The secondary battery according to claim 1 , wherein the second case is made of a metal or plastic material so as to support the outer shape of the second case.

5. a first electrode lead protruding from one surface of the first case and electrically connected to the electrode assembly; The secondary battery according to claim 1 , wherein the first electrode lead penetrates one surface of the second case.

6. The secondary battery according to claim 5 , wherein a lead film is attached to a region where the first electrode lead passes through the second case so as to seal the second case.

7. The secondary battery according to claim 6 , wherein the lead film is heat-sealed to seal the second case.

8. The secondary battery according to claim 1 , wherein the second case is provided with an exhaust hole for discharging gas from the internal space.

9. The secondary battery according to claim 8 , wherein the second case includes an opening / closing unit that opens and closes the exhaust hole.

10. The secondary battery according to claim 1 , wherein the second case further includes a position fixing unit that fixes the position of the first case.

11. the first case includes a discharge hole and a discharge unit; the discharge hole is provided on one surface of the first case so as to penetrate the first case, The secondary battery of claim 1 , wherein the exhaust unit is coupled to the exhaust hole and configured to open or close the exhaust hole according to a pressure difference between an internal pressure of the first case and an internal pressure of the second case.

12. The discharge unit includes a support portion and a floating portion, the support portion is coupled to the discharge hole and has a hollow passing through the center of the support portion; The secondary battery according to claim 11 , wherein the floating portion is disposed in the hollow of the support portion and configured to move in response to the pressure difference to open or close the discharge hole.

13. The secondary battery according to claim 1 , wherein the second case accommodates a plurality of the first cases.

14. an electrode assembly in which a positive electrode, a negative electrode, and a separator are stacked; a first case that houses the electrode assembly and that breaks when an internal pressure of the first case exceeds a predetermined pressure; a second case that houses the first case in a negative pressure internal space and collects gas discharged from the first case, The second case accommodates a plurality of the first cases.

15. A plurality of secondary batteries; a module case that houses the plurality of secondary batteries; Each secondary battery is an electrode assembly in which a positive electrode, a negative electrode, and a separator are stacked; a first case that accommodates the electrode assembly; a second case that houses the first case in a negative pressure internal space, The second case collects gas discharged from the first case.

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