Secondary battery

Abstract

The present invention relates to a secondary battery, and more particularly, to a secondary battery comprising: an electrode assembly including a positive electrode, a negative electrode, and a separator stacked together; a first case in which the electrode assembly is accommodated, and which breaks when an internal pressure of the first case is a predetermined pressure or higher; and a second housing having an internal space in which a negative pressure is formed, the second housing accommodating the first housing in the internal space, and collecting gas discharged from the first housing.

Description

Technical Field

[0001] Cross - Reference to Related Applications

[0002] This application claims the priority of 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, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to a secondary battery, and more particularly, to a secondary battery capable of capturing gas to adjust the internal pressure. Background Art

[0004] Currently, commercially available secondary batteries include nickel - cadmium batteries, nickel - metal hydride batteries, nickel - zinc batteries, and lithium secondary batteries. Among these secondary batteries, lithium secondary batteries have attracted attention due to advantages such as free charge and discharge, extremely low self - discharge rate, and high energy density because they have almost no memory effect compared to nickel - based secondary batteries. Recently, secondary batteries are widely used not only in small devices such as portable electronic devices but also in medium - to - large - sized devices such as vehicles and energy storage devices. A large number of secondary batteries can be electrically connected to each other to form a battery pack to increase capacity and output. Here, pouch - type secondary batteries are becoming more and more widely used due to advantages such as easy stacking and light weight. A pouch - type secondary battery can generally be manufactured by the following process: injecting an electrolyte while accommodating an electrode assembly in a battery case and sealing the battery case. When charging and discharging are repeated, gas may be generated inside the secondary battery.

[0005] Here, there is a problem that the generated gas increases the internal pressure of the secondary battery and causes the battery case to expand, and in severe cases, a hole is generated in the battery case due to the increased internal pressure, resulting in rapid deterioration of the secondary battery. Summary of the Invention

[0006] Technical Problem

[0007] The present invention aims to solve the above problems and provide a secondary battery that captures gas inside the secondary battery to adjust the internal pressure when the internal pressure of the secondary battery increases to a predetermined level or higher due to gas generated in the electrode assembly.

[0008] Technical Solution

[0009] According to a first embodiment of the present invention, there is provided a secondary battery, the secondary battery comprising: an electrode assembly in which a positive electrode, a negative electrode, and a separator are stacked; a first case configured to accommodate the electrode assembly and break when an internal pressure of the first case increases to a predetermined pressure or higher; and a second case configured to accommodate the first case in an internal space having a negative pressure and capture gas discharged from the first case.

[0010] In addition, a capture space may be provided in the second case, in which the gas is captured between an inner surface of the second case and an outer surface of the first case.

[0011] In addition, a cutting line for inducing breakage may be defined on the first case.

[0012] In addition, the second case may be made of a metal or plastic material to support its outer shape.

[0013] In addition, the secondary battery may further include a first electrode lead protruding from one surface of the first case and electrically connected to the electrode assembly, wherein the first electrode lead may pass through one surface of the second case.

[0014] In addition, a lead film may be attached to the following area to seal the second case: the area where the first electrode lead passes through the second case.

[0015] In addition, the lead film may be heat-melted to seal the second case.

[0016] In addition, an exhaust hole may be defined in the second case, and the gas in the internal space is discharged through the exhaust hole.

[0017] In addition, an opening / closing unit configured to open and close the exhaust hole may be provided in the second case.

[0018] In addition, the second case may further include a position fixing unit configured to fix the position of the first case.

[0019] According to a second embodiment of the present invention, a secondary battery module includes: a plurality of secondary batteries; and a module case configured to accommodate the plurality of secondary batteries, wherein each of the secondary batteries includes: an electrode assembly in which a positive electrode, a negative electrode, and a separator are stacked; a first case configured to accommodate the electrode assembly; and a second case in which a negative pressure is generated in an internal space, and the second case accommodates the first case, wherein the second case is configured to capture gas discharged from the first case.

[0020] Advantageous effects

[0021] According to the present invention, when the internal pressure of the secondary battery increases to a predetermined level or higher due to the gas generated in the electrode assembly, the gas can be trapped in the secondary battery to delay the increase in the internal pressure, thereby improving the lifespan of the secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a perspective view showing the appearance of a secondary battery according to a first embodiment of the present invention.

[0023] Figure 2 is an exploded view showing a state in which the cover frame and the accommodation frame are separated from each other to show the inside of the second housing according to the first embodiment of the present invention.

[0024] Figure 3 is an exploded view of an electrode assembly accommodated in a first housing according to a first embodiment of the present invention.

[0025] Figure 4 is taken along line AA' according to the first embodiment of the present invention Figure 2 sectional view of the first housing shown.

[0026] Figure 5 is a sectional view showing a state in which a movable part closes a discharge hole in the discharge unit of the present invention.

[0027] Figure 6 is a sectional view showing a state in which a movable part opens a discharge hole in the discharge unit of the present invention. Figure 7 is Figure 1 an enlarged view of part "A" of Figure 7 is a perspective view showing a process of opening a discharge hole through an opening / closing unit.

[0028] Figure 8 is a plan view showing the structure of an accommodation frame according to a first embodiment of the present invention.

[0029] Figure 9 is a view showing a structure in which a plurality of first housings are accommodated in a second housing. DETAILED DESCRIPTION

[0030] Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. However, the following drawings are intended to facilitate the understanding of the present invention and are only one embodiment of the present invention, and the scope of the present invention is not limited to the scope described in the drawings. In addition, in the following drawings, the same reference numerals denote the same components, and for easier understanding of the present invention, some components may be exaggerated, miniaturized, or omitted.

[0031] Furthermore, the terms or words used in this specification and claims should not be construed restrictively as ordinary meanings or dictionary-based meanings, but should be construed as meanings and concepts that conform to the scope of the present invention based on the concepts where the inventor can appropriately define the terms in order to best describe and explain the principles of his or her invention.

[0032] First Embodiment

[0033] Reference Figure 1 and Figure 2 and, the secondary battery 10 according to the first embodiment of the present invention may include an electrode assembly 100, a first case 200, and a second case 300.

[0034] The electrode assembly 100 may have a structure in which a positive electrode current collector / a positive electrode active material layer / a separator / a negative electrode active material layer / a negative electrode current collector are sequentially stacked. The positive electrode current collector may include a region coated with the positive electrode active material layer and a positive electrode uncoated portion region not coated with the positive electrode active material, and the positive electrode uncoated portion region may be a positive electrode tab. The negative electrode current collector may include a region coated with the negative electrode active material layer and a negative electrode uncoated portion region not coated with the negative electrode active material, and the negative electrode uncoated portion region may be a negative electrode tab. The separator may include an electrically insulating material and may be disposed between the positive electrode current collector and the negative electrode current collector to prevent current collectors of different polarities from contacting each other.

[0035] The electrode assembly 100 may be a stacked electrode assembly, a stacked-folded electrode assembly, or a jelly roll electrode assembly.

[0036] The first electrode tab 110 may be the positive electrode uncoated portion or the negative electrode uncoated portion of the electrode assembly 100, and the first electrode tab 110 may protrude from one surface of the electrode assembly 100 along one direction.

[0037] When described with reference Figure 3 to, since the first electrode tab 110 protrudes from the electrode assembly 100 along one direction, a plurality of the first electrode tabs 110 may be provided.

[0038] The plurality of first electrode tabs 110 may be coupled to one surface or two 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 tab 110 may be coupled to the first electrode lead 120 by welding.

[0039] The second electrode tab 130 can be such an uncoated portion that its polarity is opposite to that of the positive electrode uncoated portion or the negative electrode uncoated portion which is opposite to the polarity of the first electrode tab 110. The second electrode tab 130 can protrude in another direction extending from the electrode assembly 100.

[0040] Since the second electrode tab 130 protrudes from the electrode assembly 100 in another direction, a plurality of the second electrode tabs 130 can be provided.

[0041] The plurality of second electrode tabs 130 can be bonded to one surface or two surfaces of the second electrode lead 140, and at least a part of the second electrode lead 140 can protrude from another surface of the first housing 200. The second electrode tab 130 can be bonded to the second electrode lead 140 by welding.

[0042] The first electrode lead 120 and the second electrode lead 140 can protrude in opposite directions.

[0043] The first housing 200 can include a stacked structure composed of a first resin layer, a second resin layer, and a metal layer. The first resin layer is disposed on the outer surface of the stacked structure, the second resin layer is disposed on the inner surface of the stacked structure, and the metal layer is disposed between the first resin layer and the second resin layer.

[0044] The first resin layer is an insulating layer made of a polymer material, which must have excellent resistance to the external environment to protect the battery from external influences. Therefore, the insulating layer requires excellent tensile strength and weather resistance with respect to its thickness. For example, the insulating layer can be made of 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, and polyvinylidene chloride-based resins. The materials can be used alone or in combination of two or more materials, and polyethylene terephthalate, polyethylene naphthalate, etc. are preferably used.

[0045] The metal layer can be used as a substrate for maintaining mechanical strength and a barrier layer for preventing the penetration of moisture and oxygen. Aluminum or an aluminum alloy can be used, which, in addition to having the function of preventing gases, moisture, etc. from being introduced or discharged, also exhibits the function of enhancing the strength of the battery case. Examples of aluminum alloys can include alloy numbers 8079, 1N30, 8021, 3003, 3004, 3005, 3104, and 3105, and the alloys can be used alone or in combination of two or more alloys. Among the aluminum alloys, alloy numbers 8079, 1N30, 8021, and 3004 can be particularly preferably used as the barrier layer.

[0046] The melted area in the second resin layer can form a sealing portion on the edge area of the first case 200, and the non-melted area can form the internal space of the first case 200. The second resin layer can be made of a polyolefin-based resin material. Cast polypropylene commonly used can be used for the polyolefin-based resin layer. In addition, the second resin layer can be made of materials selected from polyolefin-based resins such as chlorinated polypropylene, polyethylene, ethylene-propylene copolymer, polyethylene and acrylic acid copolymer, and polypropylene and acrylic acid copolymer, but is not limited to the above materials.

[0047] A concave accommodating portion 210 can be provided in the first case 200 to accommodate the electrode assembly 100. The accommodating portion 210 can be set to have a predetermined width and depth to accommodate the electrode assembly 100.

[0048] When the internal pressure of the first case 200 increases to a predetermined pressure or higher due to gas generated as the electrode assembly 100 is continuously and repeatedly charged and discharged, the first case 200 may be damaged.

[0049] A cutting line 220 can be defined on the first case 200 to induce damage when the internal pressure of the first case 200 increases to a predetermined pressure or higher.

[0050] The cutting line 220 can be placed on the outer surface or the inner surface of the first case 200, and multiple cutting lines can be provided. The multiple cutting lines 220 can be arranged according to a predetermined layout.

[0051] When the internal pressure of the first case 200 increases due to gas generated from the electrode assembly 100, the cutting line 220 can induce the outer surface of the first case 200 to be damaged along the cutting line 220 by the pressure applied to the cutting line 220. If the outer surface of the first case 200 is damaged along the cutting line 220, the gas discharged from the first case 200 can be trapped in the internal space of the second case 300 that houses the first case 200.

[0052] Reference Figure 4 ,The cross-sectional shape of the cutting line 220 may be set to a notch shape, and in order to concentrate stress at the vertex of the center portion of the notch shape, the inclination directions at both sides centered on the vertex may be opposite to each other and set to be straight lines. The cross-sectional shape of the cutting line 220 may be configured such that even if pressure is uniformly applied to the inner surface of the first housing 200 on which the cutting line 220 is defined, the cutting line 220 may be first induced to break. Therefore, the predictability of the internal pressure that changes with the repeated charging and discharging of the secondary battery 10 can be improved. In addition, 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 reduced to lower the possibility of breakage of the secondary battery 10, thereby increasing the lifespan of the secondary battery 10.

[0053] Although not limited thereto, the cutting line 220 may be set to, for example, a straight line shape or a curved line shape, or set to a shape such as a circle or a square.

[0054] The position defining the cutting line 220 is not limited thereto, but may be placed at a position adjacent to the trapping space 330 of the second housing 300.

[0055] The first housing 200 may further include a discharge unit 230 and a discharge hole 221.

[0056] The discharge hole 221 may be a hole defined in one surface of the first housing 200 to penetrate the first housing 200.

[0057] Reference Figure 5 ,The discharge unit 230 is coupled to the discharge hole 221, and the discharge unit 230 may open or close the discharge hole 221 according to the pressure difference between the internal pressure of the first housing 200 and the internal pressure of the second housing 300.

[0058] The discharge unit 230 may include a support portion 231 and a movable portion 232.

[0059] The support portion 231 may be coupled to one surface of the first housing 200 along the edge of the discharge hole 221 defined in the first housing 200.

[0060] The support portion 231 may be set to protrude outward from one surface of the first housing 200, and may have a hollow portion passing through the center of the support portion to allow the interior of the first housing 200 and the interior of the second housing 300 to communicate with each other.

[0061] The movable part 232 can be placed in the hollow part passing through the center of the support part 231.

[0062] Since the movable part 232 is placed such that one surface thereof faces the discharge hole 221 and the other surface faces the inner space of the second housing 300, one surface of the movable part 232 can be pressed by the internal pressure of the first housing 200 through the discharge hole 221, and the other surface of the movable part 232 can be pressed by the internal pressure of the second housing 300. Therefore, the movable part 232 can move along the hollow part of the support part 231 in the longitudinal direction of the support part 231 according to the pressure difference between the internal pressure of the first housing 200 and the internal pressure of the second housing 300.

[0063] A connection hole 231a is defined in one surface of the support part 231, and the connection hole 231a penetrates the surface of the support part 231. The connection hole 231a can be opened or closed according to the position where the movable part 232 is placed in the hollow part of the support part 231.

[0064] For example, when the internal pressure of the first housing 200 is less than the internal pressure of the second housing 300, the movable part 232 can be placed in close contact with the discharge hole 221 according to the pressure difference applied to one surface and the other surface. Therefore, one surface of the movable part 232 can close the discharge hole 221. Here, the surface of the movable part 232 can be in close contact with the connection hole 231a defined in the inner space of the support part 231 to close the connection hole 231a.

[0065] Reference Figure 6 , when the internal pressure of the first housing 200 is greater than the internal pressure of the second housing 300, due to the pressure difference applied to one surface and the other surface, the movable part 232 can move in the hollow part of the support part 231 in a direction away from the discharge hole 221. Here, the movable part 232 can open the discharge hole 221 and the connection hole 231a, and the gas in the first housing 200 can be discharged into the inner space of the second housing 300 through the discharge hole 221 and the connection hole 231a.

[0066] A locking projection 231b protruding from the inner surface can be provided at the inner end of the support part 231 to limit the movement range of the movable part 232.

[0067] The second housing 300 may have a hollow portion defined in an inner space, the hollow portion defined in the inner space may have a negative pressure, and the first housing 200 may be received in the inner space. Here, the negative pressure may mean a state where the pressure of the hollow portion defined in the inner space of the second housing 300 is less than the external pressure of the second housing 300.

[0068] Since the inner space of the second housing 300 has a negative pressure, the pressure in the inner space of the second housing 300 may be less than the inner pressure of the first housing 200. A hole may be defined in the first housing 200 to allow the inner spaces of the first housing 200 and the second housing 300 to communicate with each other, and the gas generated in the inner space of the first housing 200 may be introduced into the inner space of the second housing 300 due to the pressure difference.

[0069] In the second housing 300, a trapping space 330 may be defined in a space between the inner surface of the second housing 300 and the outer surface of the first housing 200. The gas discharged from the first housing 200 may be trapped in the trapping space 330.

[0070] The second housing 300 may be made of a hard metal or plastic material to support the external shape. The trapping unit 300 may be made of plastic materials such as polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), polyamide (PA), polyester (PES), polyvinyl chloride (PVC), polyurethane (PU), polycarbonate (PC), and polyvinylidene chloride (PVDC), metals such as aluminum, copper, lead, zinc, tin, iron, stainless steel, tungsten, chromium, and nickel, or alloy materials of two or more of the above materials. Therefore, even if the internal pressure of the second housing 30 increases due to the gas discharged from the first housing 200, the second housing 300 may maintain its shape without deformation.

[0071] Since the widest outer surface of the second housing 300 is flat and has a smooth shape, a plurality of the second housings 300 can be stacked efficiently.

[0072] The second housing 300 may include a cover frame 310 and a receiving frame 320.

[0073] One surface of the receiving frame 320 may be opened to receive the first housing 200, and the receiving frame 320 may communicate with the inner space for receiving the first housing 200 through the opened surface.

[0074] The shape of the accommodation frame 320 is not limited thereto, but may be set to, for example, a hexahedron or a cylinder.

[0075] The accommodation frame 320 may be set to such a structure that all surfaces except the one open surface described above are closed.

[0076] A connection groove 321 may be defined in the accommodation frame 320, and the first electrode lead 120 is connected to the connection groove 321.

[0077] The connection groove 321 may be defined as a concave shape with a predetermined depth and width in the edge region facing the cover frame 310. The connection groove 321 may be provided in a plurality, and the plurality of connection grooves 321 may be defined in one edge and another edge of the accommodation frame 320.

[0078] The connection groove 321 may be defined in the central edge region or in a region offset in one direction along the edge according to the position where the first housing 200 is placed inside the second housing 300.

[0079] The cover frame 310 may be connected to the one open surface of the accommodation frame 320 to seal the second housing 300.

[0080] The cover frame 310 may be set such that the pressing unit 313 protrudes from the surface facing the accommodation frame 320. The pressing unit 313 may be placed at a position corresponding to the connection groove 321. When the cover frame 310 and the accommodation frame 320 are connected to each other, the pressing unit 313 may be inserted into the connection groove 321.

[0081] The protruding height of the pressing unit 313 may be less than the depth of the connection groove 321.

[0082] The first electrode lead 120 may pass through one surface of the second housing 300, and the second electrode lead 140 may pass through another surface of the second housing 300. Here, the first electrode lead 120 and the second electrode lead 140 may be respectively arranged in the connection grooves 321 defined in one edge and another edge of the accommodation frame 320.

[0083] The lead films 400 and 410 may be attached to the following areas to seal the second housing 300: the first electrode lead 120 passes through the second housing 300 in the area. The first electrode lead 120 and the second electrode lead 140 may be disposed in the connection groove 321 to pass through the second housing 300, and gas may be introduced into the second housing 300 from the outside through a gap defined between the connection groove 321 and the first electrode lead 120 or a gap defined between the connection groove 321 and the second electrode lead 140.

[0084] Each lead film may include an electrically insulating material, but is not limited thereto, and may be a material such as polypropylene or polyethylene.

[0085] The lead films 400 and 410 may surround the first electrode lead 120 and the second electrode lead 140 and be attached to the connection groove 321. The lead films 400 and 410 may include a first lead film 400 and a second lead film 410. Here, the first lead film 400 may be a film that surrounds the first electrode lead 120 and is attached to the connection groove 321, and the second lead film 410 may be a film that surrounds the second electrode lead 140 and is attached to the connection groove 321.

[0086] The lead films 400 and 410 may be melted by heating, and the melted lead films 400 and 410 may be in close contact with the connection groove 321 and the first electrode lead 120 or in close contact with the connection groove 321 and the second electrode lead 140 by pressure. In this state, the melted lead films 400 and 410 may be cooled to seal the second housing 300.

[0087] The pressing unit 313 placed on the cover frame 310 may be placed at a position corresponding to the connection groove 321 to protrude toward the connection groove 321. Therefore, when the cover frame 310 and the accommodation frame 320 are coupled to each other, the melted lead films 400 and 410 may be pressed. The lead films 400 and 410 pressed by the pressing unit 313 may be in close contact with the first electrode lead 120 and the connection groove 321 or the second electrode lead 140 and the connection groove 321, and in this state, the melted lead films 400 and 410 may be cooled to seal the second housing 300.

[0088] An exhaust hole 311 may be defined in the second housing 300, and the exhaust hole 311 discharges gas in the internal space. More specifically, the exhaust hole 311 may be defined in the cover frame 310 to discharge gas in the second housing 300.

[0089] The hole unit 311a that defines the exhaust hole 311 may be provided in the second housing 300. A threaded surface may be provided to protrude on the outer surface of the hole unit 311a.

[0090] When described with reference to Figure 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 may be coupled to and separated from the hole unit 311a. When the opening / closing unit 312 is coupled to the hole unit 311a, the exhaust hole 311 may be closed, and thus, gas may not flow into or out of the second housing 300 through the exhaust hole 311. When the opening / closing unit 312 is separated from the hole unit 311a, the exhaust hole 311 may be opened, and thus, gas may flow into or out of the second housing 300 through the exhaust hole 311.

[0091] A threaded surface corresponding to the threaded surface of the hole unit 311a may be provided on the inner surface of the opening / closing unit 312, so that the opening / closing unit 312 and the hole unit 311a may be threadedly coupled to each other.

[0092] When the opening / closing unit 312 is fully coupled to the hole unit 311a, the opening / closing unit 312 may be arranged not to protrude beyond the outermost surface of the cover frame 310. When stacking the secondary batteries 10, if the opening / closing unit 312 protrudes beyond the outermost surface of the cover frame 310, it is difficult to stack the secondary batteries 10, and the volume will be unnecessarily increased. Therefore, even when the opening / closing unit 312 is fully coupled to the hole unit 311a, the opening / closing unit 312 may be arranged not to protrude beyond the outermost surface of the cover frame 310.

[0093] As a first exemplary embodiment of a method for forming the interior space of the second housing 300 into a negative pressure state, the method may include a first housing sealing process and a second housing sealing process. The first housing sealing process may include the following processes: forming a negative pressure by discharging the gas inside the first housing 200; and sealing the first housing 200 by using the negative pressure formed inside the first housing 200. When only the interior of the second housing 300 is formed with a negative pressure, due to the pressure difference between the internal pressure of the first housing 200 and the internal pressure of the second housing 300, the first housing 200 may expand, and thus, the first housing 200 may be damaged. Therefore, the internal pressure of the first housing 200 may be formed into a negative pressure by the first housing sealing process. The second housing sealing process may be a process of accommodating and sealing the first housing 200 in which the electrode assembly is accommodated in the second housing 300, and the second housing sealing process may further include a process of discharging the internal gas from the sealed second housing 300 to form the interior of the second housing 300 into a negative pressure. During the process of forming the interior of the second housing 300 into a negative pressure, the internal pressure of the second housing 300 may be reduced. Therefore, as the internal pressure of the second housing 300 decreases, the first housing 200 placed inside the second housing 300 may expand. However, in order to minimize the expansion of the first housing 200, the pressure inside the second housing 300 and the pressure inside the first housing 200 may be set to the same or similar pressures. For example, the first housing sealing process may be performed at a pressure of 0.04 Mpa to seal the first housing, and then the second housing sealing process may also be performed at a pressure of 0.04 Mpa.

[0094] As a second exemplary embodiment of a method for forming the interior space of the second housing 300 into a negative pressure state, in the process of forming the interior of the second housing 300 into a negative pressure state, when the gas inside the second housing 300 is discharged through the exhaust hole 311 by using a suction device (not shown), a pressure difference may be generated between the internal pressure of the first housing 200 and the internal pressure of the second housing 300 due to the reduction of the internal pressure of the second housing. Here, as the first housing 200 expands, the first housing 200 may be damaged. Therefore, the discharge unit 230 may be further provided in the first housing 200 to prevent the first housing 200 from being damaged. When the gas inside the second housing 300 is sucked through the exhaust hole 311 to generate a negative pressure in the second housing 300, the gas inside the first housing 200 may be discharged through the discharge unit 230 to prevent the first housing 200 from expanding and being damaged.

[0095] A position fixing unit 322 may be provided on the accommodation frame 320.

[0096] Reference Figure 8 , the position fixing unit 322 may be configured to be provided on the inner bottom surface of the accommodation frame 320 and to fix the position of the first housing 200 disposed inside the accommodation frame 320.

[0097] The position fixing unit 322 may be placed to protrude upward from the inner bottom surface of the accommodation frame 320 and may be placed at positions corresponding to each vertex of the bottom surface of the first housing 200 facing the inner bottom surface of the accommodation frame 320.

[0098] Each vertex of the bottom surface of the first housing 200 may be fitted into the position fixing unit 322, and the first housing 200 may be fixed in place so as not to move in a direction parallel to the inner bottom surface of the accommodation frame 320.

[0099] The position fixing unit 322 may be provided with a curved shape, and the first housing 200 may be placed such that the vertices of the bottom surface of the first housing 200 are placed on the curved inner region of the position fixing unit 322.

[0100] The position fixing unit 322 may be provided in a plurality, and the plurality of position fixing units 322 may be placed at positions corresponding to the four vertices of the bottom surface of the first housing 200. Since each vertex of the four vertices of the first housing 200 is fixed in place by the position fixing unit 322, the first housing 200 may be stably fixed in place so as not to move in a direction parallel to the inner bottom surface of the accommodation frame 320.

[0101] Reference Figure 9 , a secondary battery may be manufactured in such a way that a plurality of first housings 200 are accommodated in a second housing 300. In this case, a larger battery capacity may be achieved.

[0102] In addition, the second housing 300 may function as a type of battery module. That is, the first housing 200 may be similar to a secondary battery. The first housing 200 houses an electrode assembly in which a positive electrode, a negative electrode, and a separator are stacked, and breaks when the internal pressure increases to a predetermined pressure or higher. A plurality of the first housings 200 may be accommodated in the second housing 300, and the first housings 200 may be electrically connected to each other. In addition, as described above, the first housings 200 may be electrically connected to each other and be managed and accommodated in the second housing 300. In this case, the second housing 300 in which the plurality of first housings 200 are accommodated may integrally become a battery module.

[0103] In this case, the second housing 300 may also be configured to accommodate the first housing 200 in an internal space having a negative pressure to trap gas discharged from the first housing 200.

[0104] Second Embodiment

[0105] According to a second embodiment of the present invention, a secondary battery module (not shown) according to the present invention may include a plurality of secondary batteries 10 and a module housing (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 housing 200 that houses the electrode assembly 100; and a second housing 300 in which a negative pressure is generated in an internal space and the second housing 300 houses the first housing 200. The detailed description of the electrode assembly 100, the first housing 200, and the second housing 300 may be replaced by the above content.

[0106] Although the present technology has been described by the above examples, the present technology is not limited thereto. Modifications or changes may be made to the above embodiments without departing from the spirit and scope of the present technology, and those skilled in the art will recognize that such modifications and changes also belong to the present technology.

[0107] List of Reference Numerals

[0108] 10: Secondary battery

[0109] 100: Electrode assembly

[0110] 110: First electrode tab

[0111] 120: First electrode lead

[0112] 130: Second electrode tab

[0113] 140: Second electrode lead

[0114] 200: First housing

[0115] 210: Accommodating part

[0116] 220: Cutting line

[0117] 300: Second housing

[0118] 310: Cover frame

[0119] 311: Exhaust hole

[0120] 311a: Hole unit

[0121] 312: Opening / closing unit

[0122] 313: Pressurizing unit

[0123] 320: Accommodating frame

[0124] 321: Connecting groove

[0125] 322: Position fixing unit

[0126] 330: Trapping space

[0127] 400: First lead film

[0128] 410: Second lead film

Claims

1. A secondary battery, comprising: An electrode assembly in which a positive electrode, a negative electrode, and a separator are stacked; A first case configured to accommodate the electrode assembly and break when the internal pressure of the first case increases to a predetermined pressure or higher; And A second case configured to accommodate the first case in an internal space having a negative pressure and capture gas discharged from the first case.

2. The secondary battery according to claim 1, wherein, A capture space is provided in the second case, in which the gas is captured between the inner surface of the second case and the outer surface of the first case.

3. The secondary battery according to claim 1, wherein A cutting line for inducing breakage is defined on the first case.

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

5. The secondary battery according to claim 1, further comprising a first electrode lead wire protruding from one surface of the first case and electrically connected to the electrode assembly, Among them, The first electrode lead wire passes through one surface of the second case.

6. The secondary battery according to claim 5, wherein, A lead film is attached to the following area to seal the second case: the area where the first electrode lead wire passes through the second case.

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

8. The secondary battery according to claim 1, wherein An exhaust hole is defined in the second case, and the gas in the internal space is discharged through the exhaust hole.

9. The secondary battery according to claim 8, wherein, An opening / closing unit is provided in the second case, and the opening / closing unit is configured to open and close the exhaust hole.

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

11. The secondary battery according to claim 1, wherein, The first case includes a discharge hole and a discharge unit, Wherein, the discharge hole is defined in one surface of the first case to penetrate the first case, and The discharge unit is coupled to the discharge hole to open or close the discharge hole according to the pressure difference between the internal pressure of the first case and the internal pressure of the second case.

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

13. The secondary battery according to claim 1, wherein, A plurality of first cases are accommodated in the second case.

14. A battery module, comprising: An electrode assembly in which a positive electrode, a negative electrode, and a separator are stacked; A first case configured to accommodate the electrode assembly and break when the internal pressure of the first case increases to a predetermined pressure or higher; And A second case configured to accommodate the first case in an internal space having a negative pressure and capture gas discharged from the first case, Wherein, a plurality of first cases are accommodated in the second case.

15. A secondary battery module, comprising: A plurality of secondary batteries; And A module case configured to accommodate the plurality of secondary batteries, Wherein, each of the secondary batteries includes: An electrode assembly in which a positive electrode, a negative electrode, and a separator are stacked; A first housing configured to accommodate the electrode assembly; and A second housing, wherein a negative pressure is generated in the internal space of the second housing, and the second housing accommodates the first housing, wherein the second housing is configured to capture gas discharged from the first housing.

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