KR101858790B1 - Pouch type secondary battery - Google Patents

Abstract

A secondary battery is provided which can maintain a sealing adhesive force capable of blocking the inside and the outside of a secondary battery and easily discharge the external force to the outside when an internal pressure equal to or higher than a proper level is generated. A secondary battery according to the present invention includes: an electrode assembly having an electrode terminal; And a pouch case in which the electrode assembly is mounted in an internal space formed between an upper sheet and a lower sheet such that a part of the electrode terminal is exposed, wherein the upper sheet and the lower sheet have a sealing part sealed at an outer periphery excluding the electrode terminal And a holding member fixed to upper and lower ends of the sealing portion and having a predetermined curvature at a groove entrance edge toward the electrode assembly.

Description

[0001] The present invention relates to a pouch type secondary battery,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pouch type secondary battery, and more particularly, to a pouch type secondary battery capable of controlling a pouch type secondary battery even if an internal pressure of an appropriate level or higher is generated by improving a sealing part.

Secondary batteries having high electrical properties such as high energy density and high ease of application according to the product group are widely used not only in portable devices but also in electric vehicles (EVs) or hybrid vehicles (HVs) driven by electric driving sources Has been applied.

Such a secondary battery is not only a primary advantage that the use of fossil fuel can be drastically reduced, but also produces no by-products resulting from the use of energy, and thus is attracting attention as a new energy source for enhancing environmental friendliness and energy efficiency.

2. Description of the Related Art [0002] With the recent miniaturization of a mobile device, a secondary battery (cell) can be classified into various types including a can type battery in which internal elements are constituted by a hard case such as a metallic case, The demand for pouch-type batteries is increasing. Particularly, there is a high interest in a pouch type battery which is easily deformed in shape, low in manufacturing cost, and small in weight. In addition, pouch-type batteries are being developed and commercialized as a power source for a battery automobile or a hybrid electric automobile which requires a high output large capacity.

However, the pouch-type secondary battery is advantageous in that it can be made lighter and smaller than a cylindrical or prismatic battery using a metal can as a casing, has a comparative advantage in terms of manufacturing cost, and is simple in structure and excellent in safety. However, the pouch type secondary battery is disadvantageous in that the barrier characteristic is lower than that of a square or cylindrical battery.

FIG. 1 is a schematic view of a conventional pouch-type secondary battery, and FIG. 2 is a cross-sectional view taken along line II-II 'of FIG.

1 and 2, a conventional pouch-type secondary battery 1 includes a battery case 3, an electrode assembly 5 accommodated in the battery case 3, and an anode and a cathode of the electrode assembly 5, And a positive electrode and a negative electrode terminal 7 connected to the negative electrode and protruding to the outside of the battery case 3, respectively.

The battery case 3 is manufactured by a laminate upper sheet 3a and a lower sheet 3b in the form of a pouch and the upper and lower sheets 3a and 3b of the laminate are respectively made of an outer resin layer, . The electrode assembly 5 has a positive electrode / separator / negative electrode structure and is embedded in the battery case 3 together with the electrolytic solution. The rectangular or square-shaped battery case 3 has sealing portions 9 that are mutually fused at four edges of the upper and lower sheets 3a, 3b of the laminate.

Meanwhile, in a secondary battery manufactured through the above-described structure and process, a carbon-based material is generally used for a negative electrode, a lithium-based oxide is used for a positive electrode, and an organic solvent electrolyte is used for an electrolyte. If a sudden change or the like occurs, electrolytic solution decomposition occurs at the anode and precipitation of lithium metal may occur at the cathode. If such a phenomenon occurs, the performance of the secondary battery may be deteriorated, The gas can be generated by the heat generated by the gas.

In addition, a solvent such as ethylene carbonate or propylene carbonate is used for the electrolytic solution. Such a solvent decomposes at a high temperature to generate gas, and a swelling phenomenon may occur due to an increase in pressure. Such a swelling phenomenon may cause electrical short-circuiting. In addition, if an external impact is applied in a swollen state, sparks may be generated and may be ignited, which may be dangerous. In a hybrid electric vehicle or an electric vehicle, In an environment where the drive must be maintained, this risk is higher.

The conventional pouch type secondary battery 1 is manufactured by sealing and applying heat and pressure to the four edges of the upper and lower sheets 3a and 3b of the laminate and is able to withstand a certain degree of pressure. The sealing strength of the secondary battery 1 is reached, and the sealing of the pouch type secondary battery 1 is separated, thereby causing a vent phenomenon in which the interior is exposed. When the pouch-type secondary battery 1 is vented, if moisture and oxygen in the air come into contact with the charged electrode, an exothermic reaction occurs, which may deteriorate the safety of the lithium secondary battery.

As the internal pressure between the two sealed upper and lower sheets 3a and 3b rises and is pulled in a direction perpendicular to the sealing portion (the direction of the arrow in Fig. 3), the pore size of the pouch type secondary battery 1 The limit strength at which the sealing portion is bonded is lowered and the sealing portion is easily separated. In the conventional pouch-type secondary battery 1, when the pouch is inflated, there is no device in the sealing part, so that the sealing part receives a force in the vertical direction and the resistance to the pressure resistance is low. In addition, there is a disadvantage that the vent phenomenon can not be controlled.

That is, there is a need to realize a pouch-type secondary battery which can effectively satisfy all the conditions that the sealing adhesion capable of shutting off the inside and the outside of the secondary battery is maintained, and when the internal pressure is higher than the proper level, This is big.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pouch-type secondary battery which can control the internal pressure even when an internal pressure of a proper level or higher is generated by improving a sealing part.

According to an aspect of the present invention, there is provided a secondary battery including: an electrode assembly having an electrode terminal; And a pouch case in which the electrode assembly is mounted in an internal space formed between an upper sheet and a lower sheet such that a part of the electrode terminal is exposed, wherein the upper sheet and the lower sheet have a sealing part sealed at an outer periphery excluding the electrode terminal And a holding member fixed to upper and lower ends of the sealing portion and having a predetermined curvature at a groove entrance edge toward the electrode assembly.

The holding member guides the sealing member of the secondary battery at an angle to the sealing member when the internal pressure of the secondary battery rises.

The holding member prevents or restricts the venting phenomenon when the internal pressure of the secondary battery rises.

The holding member may be in surface contact with the upper and lower surfaces of the sealing portion through the groove.

When the internal pressure of the secondary battery rises, the holding member may disperse a force transmitted to the sealing portion of the secondary battery through a curved surface to adjust an angle at which the sealing portion is pulled.

The position of the groove entrance edge of the holding member having the curvature is fixed so as to maintain a constant position from the inner edge of the sealing part toward the inside of the electrode assembly.

The holding member may extend from the groove entrance edge and extend to the upper sheet and the lower sheet perpendicular to the groove depth direction.

Preferably, the holding member is a rigid block-like structure.

Instead, the holding member may be a clip for bending the sealing portion on both sides, and the clip inlet edge may be machined to have a certain curvature.

The holding member is preferably made of an insulating material.

The holding member may be applied to the entire sealing part of the pouch or may be applied to a part of the sealing part of the pouch and cause a venting phenomenon through the sealing part to which the holding member is not applied.

The holding member may be fixed to the upper and lower ends of the sealing portion so that a groove entrance edge, which is an inner direction of the secondary battery, forms an inclined surface. The inclined surface may have various inclination angles.

The holding member may pressurize the sealing portion to be in close contact with the sealing member.

The holding member may be such that the sealing portion can penetrate the other surface in a direction in which the sealing portion is inserted into the groove.

According to the present invention, a block type or clip-type holding member having rigidity at the upper and lower ends of the sealing portion of the pouch corner can be mounted to secure the resistance against pulling of the pouch sealing portion in the vertical direction even when the internal pressure of the secondary battery rises.

The sealing portion of the corner of the pouch is compressed by using a holding member so that volume expansion of the secondary battery can be suppressed during charge and discharge of the secondary battery. As a result, detachment and deterioration of the electrode active material can be prevented, Can be prevented.

The holding member can distribute the force at a certain angle to the sealing portion so that the sealing portion is not vertically applied to the sealing portion and the sealing portion is not opened. Therefore, even if the same sealing portion is formed, there is an advantage that a higher internal pressure can be maintained compared with the conventional sealing portion.

As described above, according to the present invention, even when the internal pressure of the secondary battery rises, the venting phenomenon can be prevented or limited by restraining the internal pressure, and the venting direction can be predicted by constantly predicting the venting direction in a direction in which the holding member is not formed There is a manageable effect. Accordingly, when the internal pressure of the secondary battery is maintained to a level higher than the proper level, the sealing adhesive force can be easily released to the outside.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments of the invention and, together with the description of the invention, It should not be construed as limited.
FIG. 1 is a schematic view of a conventional pouch-type secondary battery, and FIG. 2 is a cross-sectional view taken along line II-II 'of FIG.
Fig. 3 is a cross-sectional view of the pouch type secondary battery of Fig. 2 when the internal pressure is increased. Fig.
FIG. 4 is a schematic view of a pouch type secondary battery according to an embodiment of the present invention, and FIG. 5 is a cross-sectional view taken along line VV 'of FIG.
6 is a perspective view of a holding member according to an embodiment of the present invention.
Fig. 7 is a cross-sectional view of the pouch type secondary battery of Fig. 5 when the internal pressure is increased. Fig.
8 is a cross-sectional view of a holding member according to another embodiment of the present invention.
9 is a sectional view of a holding member according to another embodiment of the present invention.
10 is a modification of the holding member shown in Fig.
11 is a schematic view illustrating a pouch type secondary battery according to another embodiment of the present invention.
12 is a sectional view of a holding member according to another embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It is provided to let you know. The shape of the elements and the like in the drawings are exaggerated in order to emphasize a clearer description, and the same reference numerals denote the same elements.

FIG. 4 is a schematic view of a pouch type secondary battery according to an embodiment of the present invention, and FIG. 5 is a cross-sectional view taken along line V-V 'of FIG.

4 and 5, a pouch type secondary battery 11 according to an embodiment of the present invention includes a battery case 13, an electrode assembly 15 housed in the battery case 13, And a positive electrode and a negative electrode terminal 17 connected to the positive and negative electrodes of the battery case 15 and protruding from the outside of the battery case 13, respectively.

Although not shown in detail for the sake of convenience of the drawings, the electrode assembly 15 is configured in such a manner that at least one positive electrode plate and at least one negative electrode plate are disposed with a separator interposed therebetween, and is housed in the battery case 13. At this time, the electrode assembly 15 may be housed in the battery case 13 in a state where a plurality of positive and negative plates are laminated, or may be housed in the battery case 13 in a state where one positive electrode plate and the negative electrode plate are wound.

The electrode plates of the electrode assembly 15 are formed of a structure in which an active material slurry is coated on a current collector made of aluminum (Al) or copper (Cu). The slurry is usually used in a granular active material, auxiliary conductor, binder, May be added while stirring. Each of the electrode plates may have an uncoated portion to which no slurry is applied, and an electrode tab corresponding to each electrode plate may be formed on the uncoated portion.

The cathode active material may be a chalcogenide compound so that lithium ions can intercalate / deintercalate. For example, LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , LiNi _{1 -x} Co _x O ₂ (0 < x < 1), LiMnO _2, or the like. The negative electrode active material may be a carbonaceous material, silicon (Si), tin (Sn), tin oxide, tin alloy composite, transition metal oxide, lithium metal nitride Or a lithium metal oxide or the like.

The separation membrane is interposed between the positive and negative electrode plates to prevent a short circuit between the positive and negative electrode plates, and only the lithium ion can move due to the separation membrane. The separation membrane may be formed of a thermoplastic resin such as polyethylene (PE) or polypropylene (PP), and the surface of the separation membrane may be a porous membrane structure.

The electrode tabs (not shown) are constituted by, for example, a positive electrode tab and a negative electrode tab, and are formed so as to protrude from the electrode assembly 15, respectively. That is, the positive electrode tab is formed so as to protrude from the positive electrode plate of the electrode assembly 15, and the negative electrode tab is formed to protrude from the negative electrode plate of the electrode assembly 15. At this time, the positive electrode tab or the negative electrode tab may protrude in a form attached to the positive electrode plate or the negative electrode plate, and may be made of the same material as the positive electrode collector or the negative electrode collector, respectively.

The plurality of electrode tabs may be provided in one electrode assembly. For example, a plurality of positive electrode tabs may be provided on the positive electrode plate, and a plurality of negative electrode tabs may be provided on the negative electrode plate. In this case, the plurality of positive electrode tabs may be connected to one positive electrode terminal, and the plurality of negative electrode tabs may be connected to one negative electrode terminal. However, the present invention is not necessarily limited to these embodiments, and one positive electrode tab and one negative electrode tab may be provided in one electrode assembly.

In this embodiment, the positive electrode tab and the negative electrode tab are protruded in the same direction with respect to the electrode assembly 15, and a unidirectional battery in which the electrode terminal 17 protrudes in one direction is taken as an example. However, the present invention is also applicable to a so-called bi-directional battery in which the positive electrode tab and the negative electrode tab protrude in the opposite direction with respect to the electrode assembly 15 and the electrode terminals 17 protrude in opposite directions.

The battery case 13 is manufactured by a laminate upper sheet 13a and a lower sheet 13b in the form of a pouch and the laminate upper sheet and the lower sheets 13a and 13b are respectively made of an outer resin layer, . The electrode assembly 15 has a positive electrode / separator / negative electrode structure and is embedded in the battery case 13 together with the electrolytic solution. The rectangular or square-shaped battery case 13 has sealing portions 19 that are mutually fused at four edges of the laminated upper and lower sheets 13a and 13b.

The battery case 13 has a concave inner space. The electrode assembly 15 is accommodated in the inner space, and an electrolyte (not shown) such as a liquid, a solid or a gel is filled depending on the type of the secondary battery. The space in which the electrode assembly 15 can be housed can be formed in either the upper sheet and the lower sheet 13a or 13b or both the upper sheet and the lower sheet 13a and 13b. The upper and lower sheets 13a and 13b are adhered to each other by thermal fusion or the like to form a sealing portion 19 when the electrode assembly 15 is accommodated in the accommodating space of the upper sheet and the lower sheet 13a and 13b.

Since the outer resin layer plays a role of protecting the battery from the outside and a substrate, it is required to have excellent tensile strength and weather resistance compared to the thickness, and to protect the electrode assembly 15 accommodated in the inside from the external impact can do. The outer resin layer may be formed of a resin material such as stretched nylon (ONy) or polyethylene terephthalate (PET), but is not limited thereto.

The barrier metal layer may serve as a barrier layer for preventing permeation of moisture and oxygen and a substrate that maintains mechanical strength. Air, moisture, and the like into the inside of the battery. In general, aluminum (Al) is widely used.

The inner resin layer is thermally fused to each other by heat and pressure applied in a state in which the electrode assembly 15 is embedded, and is also called an adhesive layer or a heat-sealable layer. In general, it may be formed of a polyolefin resin material. Commonly used as a polyolefin-based resin layer is CPP (Casted Polypropylene). The inner resin layer may be formed of a material selected from the group consisting of a polyolefin resin such as chlorinated polypropylene, polyethylene, an ethylene propylene copolymer, a polyethylene and an acrylic acid copolymer, and a copolymer of polypropylene and acrylic acid. But is not limited to materials.

The battery case 13 having such a multilayer laminate structure has a structure in which the inner resin layers face each other in the sealing portion, and these inner resin layers are bonded to each other by heat fusion.

The upper sheet and the lower sheet 13a and 13b form a sealing portion 19 sealed at the outer circumferential portion excluding the electrode terminal 17. The secondary battery (11) according to the present invention further includes a holding member (20).

5, the holding member 20 is formed with a groove H for inserting the sealing portion 19, and is fixed to the upper and lower ends of the sealing portion 19. As shown in FIG. And has a certain curvature at an inlet edge (C) of the groove (H) in the direction toward the electrode assembly (15). In this embodiment, the sealing portion 19 is accommodated in the groove H so that the sealing portion 19 is not exposed to the outside. As a result, the inflow of foreign matter such as outside air, moisture, and the like is blocked, so that deterioration of each corner portion does not occur.

On the other hand, the surface of the holding member 20 may be the same as or protruded from the surface of the battery case 13. The holding member 20 protruding from the battery case 13 receives the external force first so that the electrode assembly 15 in the battery case 13 is damaged. It is also possible to prevent it.

6 is a perspective view of a holding member according to an embodiment of the present invention. Preferably, the holding member 20 is a rigid block-like structure. The holding member 20 can be in surface contact with the upper and lower surfaces of the sealing portion 19 through the groove H. [ The size of the groove H is formed in consideration of the size of the sealing portion 19 so that the pressure can be applied so that the sealing portion 19 can be closely contacted with the groove H although the sealing portion 19 can be accommodated.

When the size of the groove H is larger than the sealing portion 19, the sealing portion 19 is accommodated in the groove H with sufficient space. When the size of the groove H is smaller than the sealing portion 19, the sealing portion 19 is received in the groove H by interference fit, and in this case, the sealing portion 19 is pressurized.

The holding member 20 may extend from the edge H of the inlet H and may extend perpendicular to the depth direction of the groove H to extend toward the upper and lower sheets 13a and 13b . The holding member 20 is preferably made of an insulating material. According to such a holding member 20, the insulating characteristic of the sealing portion 19 is ensured, so that the secondary battery 11 can have excellent insulating characteristics. The holding member 20 must be rigid so as to be able to accommodate the deformation of the upper and lower sheets 13a and 13b without deformation. Thus, at least the surface S extending from the inlet edge C and the inlet edge C of the groove H and extending toward the upper and lower sheets 13a and 13b has rigidity . And the remaining portion may be made of a highly elastic material so as to absorb the shock when an external force is applied, or to relieve the impact to other portions.

The holding member 20 guides the sealing member 19 of the secondary battery 11 so that the sealing member 19 can be applied at an angle to the sealing member 19 when the internal pressure of the secondary battery 11 rises. This will be described in detail as follows.

In the case where the internal pressure of the secondary battery 11 is less than a predetermined size, that is, in a normal state, there is a gap of a predetermined size between the edge C and the upper and lower sheets 13a and 13b as shown in FIG. 5 .

Fig. 7 is a cross-sectional view of the pouch type secondary battery of Fig. 5 when the internal pressure is increased. Fig.

As the internal pressure of the secondary battery 11 increases, the two sheets of upper and lower sheets 13a and 13b of the laminate are spread. In the present invention, when the holding member 20 exists between them, The sheet and the lower sheets 13a and 13b are brought into contact with the entrance edge C of the groove H of the holding member 20. [ Therefore, the force is not applied to the sealing portion 19 in the direction close to the vertical direction but is applied in the oblique direction (arrow direction in Fig. 7). The holding member 20 disperses the force transmitted to the sealing portion 19 of the secondary battery 11 through the curved surface when the internal pressure of the secondary battery 11 rises and the sealing portion 19 is pulled It is possible to adjust the angle of retraction.

The position of the inlet edge C of the groove H of the holding member 20 should be fixed so as to maintain a constant position from the inner edge of the sealing portion 19 toward the inside of the electrode assembly 15 . When the position of the inlet edge C of the groove H of the holding member 20 is within the sealing portion 19, it may be difficult to exert its function. In order to fix the position of the holding member 20, for example, a method of forming a holding member 20 by a method such as injection molding in a module housing cell fixing housing can be used.

As described above, the holding member 20 restricts the sealing portion 19 and disperses the force even when the internal pressure of the secondary battery 11 rises, thereby preventing a phenomenon in which the bonding portion of the sealing portion 19 is separated due to the concentration of force . In addition, since it can increase the time to vent, it also has the effect of limiting the vent.

8 is a cross-sectional view of a holding member according to another embodiment of the present invention.

The holding member 21 shown in FIG. 8 is substantially the same as the holding member 20 described above except that the sealing member 19 can be inserted through the groove H and penetrate the other surface . According to this configuration, it is easy to fix the holding member 21 at a desired position by fitting the holding member 21 into the sealing portion 19 regardless of the width of the sealing portion 19. [

9 is a sectional view of a holding member according to another embodiment of the present invention.

The holding member 22 shown in Fig. 9 is substantially the same as the above-described holding member 21 except that the groove H 'of the groove H forms an inclined surface. On the other hand, as a modification of the holding member 22, a structure may be adopted in which the sealing member 19 is received in the groove H while the entrance edge C 'of the groove H forms an inclined surface and is not exposed to the outside. The holding member 22 extends from the entrance edge C 'of the groove H and a surface S extending toward the upper and lower sheets 13a and 13b is perpendicular to the depth direction of the groove H.

As a modification of this holding member 22, a holding member 23 as shown in FIG. 10 is also possible, which is almost the same as the holding member 22 described above except that the edge H of the inlet H is inclined And extends to the surface of the holding member 22 in a different manner. The inclined surface may have various inclination angles. 10 shows an example in which the entrance H 'inlet edge C' is formed at a constant inclination angle. However, in order to distribute the force in various directions, the inclination angle of the entrance H 'inlet edge C' It may be changing.

In the case of the holding members 22 and 23 of Figures 9 and 10 in which the groove H inlet edge C 'forms an inclined surface, in the previous embodiments the groove H inlet edge C forms a curved surface It is possible to prevent the force in the vertical direction of the sealing portion 19 from being applied to the sealing portion 19 in the same way as to prevent or limit the venting phenomenon.

4, the holding member 20 is applied to a portion of the sealing portion 19 of the secondary battery 11 where the electrode terminal 17 is not formed. In this case, the venting phenomenon may occur through the sealing portion on the side of the electrode terminal 19 to which the holding member 20 is not applied, thereby inducing the vent in a certain direction.

Depending on the design of the secondary battery, it is also possible to apply the holding member 20 to the entire sealing portion 19 of the secondary battery. FIG. 11 is a schematic view of a pouch type secondary battery according to another embodiment of the present invention, for example, showing a bi-directional secondary battery 11 ' As shown in Fig. When the holding member 20 is applied to the remainder of the secondary battery 11 'except for a sealing portion having a predetermined area, the direction of the vent can be artificially adjusted.

In the previous embodiments, the holding members 20, 21, 22, 23 are block-shaped structures. In the present invention, the block-shaped structure may be defined as a structure having a box-shaped body having a lump shape and a groove (H) having a thickness smaller than the thickness of the body. The holding member 24 according to another embodiment is a clip for bending the sealing portion 19 on both sides as shown in the sectional view of FIG. 12, and the clip inlet edge O is machined to have a certain curvature .

The clip-type holding member 24 grips and fixes the sealing portion 19 from the outside. The force applied to the sealing portion 19 when the internal pressure of the secondary battery rises through the clip inlet edge O processed to have a certain curvature is prevented You can constrain the vent to be distributed in multiple directions. The clip-type holding member 24 may have one or a plurality of structures, and one or a plurality of the clip-type holding members 24 may be fitted in the sealing portion 19. According to this configuration, expansion of the sealing portion 19 can be suppressed.

As described above, according to the present invention, when the internal pressure of the pouch type secondary battery is increased, resistance against pulling of the sealing portion in the vertical direction is secured through the holding member, and the safety of the secondary battery is improved by restraining or restricting the vent. You can. A holding member including a groove entrance edge having a predetermined curvature is fixed to the upper and lower ends of the sealing part, and a force is applied to the sealing part at a certain angle so that the same sealing part can withstand a higher internal pressure than the conventional sealing part.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but many variations and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims. It will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the appended claims.

11, 11 ': Pouch type secondary battery 13: Battery case
13a: upper sheet 13b: lower sheet
15: electrode assembly 17: electrode terminal
19: sealing part 20, 21, 22, 23, 24: holding member
H: Home C, C ', O: Corner

Claims (20)

An electrode assembly having an electrode terminal formed therein; And
And a pouch case on which the electrode assembly is mounted in an internal space formed between an upper sheet and a lower sheet such that a part of the electrode terminal is exposed,
The upper sheet and the lower sheet form a sealed portion sealed at an outer circumferential portion excluding the electrode terminal,
Further comprising a holding member having a groove formed therein for inserting the sealing portion and fixed at the upper and lower ends of the sealing portion and having a predetermined curvature at a groove entrance edge toward the electrode assembly,
Wherein the holding member disperses a force transmitted to a sealing portion of the secondary battery through a curved surface to adjust an angle at which the sealing portion is pulled when the internal pressure of the secondary battery rises,
Wherein when the pressure of the secondary battery is increased, a gap between the groove entrance edge of the holding member and the upper sheet and the lower sheet is increased, So that the holding member can resist the pulling force of the sealing portion in the vertical direction even when the internal pressure of the secondary battery rises and the internal pressure rises. However,
Wherein the holding member is a block-like structure having a box-shaped body having a lump shape and a thickness smaller than the thickness of the body, the holding member being extended from the groove entrance edge and the holding member, Wherein a surface extending toward the lower sheet is rigid so that the internal pressure of the secondary battery is increased without deformation and the upper and lower sheet deformation can be accommodated even when the secondary battery is inflated, and the remaining portion is a material having high elasticity. delete The secondary battery according to claim 1, wherein the holding member prevents or restricts a vent phenomenon when an internal pressure of the secondary battery rises. The secondary battery according to claim 1, wherein the holding member is in surface contact with the upper and lower surfaces of the sealing portion through the groove. delete The secondary battery according to claim 1, wherein a position of a groove entrance edge of the holding member having the curvature is fixed so as to maintain a predetermined position from the inner edge of the sealing part toward the inside of the electrode assembly. The secondary battery according to claim 1, wherein the holding member extends from a corner of the groove entrance and extends toward the upper sheet and the lower sheet perpendicular to the groove depth direction. delete delete delete delete The secondary battery according to claim 1, wherein the holding member is made of an insulating material. The secondary battery according to claim 1, wherein the holding member is applied to the entire sealing portion of the pouch. The secondary battery according to claim 1, wherein the holding member is applied to a part of a sealing part of the pouch and a venting phenomenon occurs through a sealing part to which the holding member is not applied. delete delete The secondary battery according to claim 1, wherein the holding member applies pressure so that the sealing portion is in close contact with the holding member. The secondary battery according to claim 1, wherein the holding member is capable of penetrating the other surface in a direction in which the sealing portion is inserted and inserted into the groove. The secondary battery according to claim 1, wherein the sealing portion is accommodated in the groove of the holding member so that the sealing portion is not exposed to the outside. The secondary battery according to claim 1, wherein the surface of the holding member is the same or more than the surface of the battery case.

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