Secondary batteries

Abstract

A secondary battery according to an embodiment of the present invention may include an electrode assembly, a frame made of an insulating material surrounding a periphery of the electrode assembly to accommodate the electrode assembly, and a pair of exterior sheets sealed to the frame on both sides of the frame to cover the electrode assembly. The frame may have a groove formed therein facing outward to increase a sealing area between the exterior sheets and the frame.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0166857 filed on December 5, 2022, and Korean Patent Application No. 10-2023-0170861 filed on November 30, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a secondary battery including an electrode assembly and an exterior sheet. [Background technology]

[0003] Generally, types of secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, lithium-ion polymer batteries, etc. Such secondary batteries are used not only in small products such as digital cameras, DVD players, MP3 players, mobile phones, PDAs, portable game devices, power tools, and e-bikes, but also in large products that require high output such as electric vehicles and hybrid vehicles, as well as in power storage devices and backup power storage devices that store surplus generated power and new renewable energy.

[0004] To manufacture such a secondary battery, an electrode active material slurry is first applied to a positive electrode current collector and a negative electrode current collector to form a positive electrode and a negative electrode, which are then arranged on either side of a separator to form an electrode assembly of a predetermined shape, and the electrode assembly is then housed in a battery case, filled with an electrolyte, and sealed.

[0005] Secondary batteries are classified into pouch types and can types depending on the material of the case that houses the electrode assembly. Pouch types house the electrode assembly in a pouch made of flexible polymer material, while can types house the electrode assembly in a case made of metal or plastic.

[0006] Generally, a pouch-type battery case is manufactured by pressing a flexible laminate sheet to form a cup portion, and then, after the cup portion is formed, an electrode assembly is placed inside the cup portion and the sides are sealed to manufacture a secondary battery.

[0007] In such press working, drawing is performed by inserting a laminate sheet into a molding device such as a press, and applying pressure to the laminate sheet with a punch to stretch the laminate sheet.

[0008] However, as the electrode assembly becomes thicker, the cup portion formed in the laminate sheet becomes deeper, and excessive stretching of the cup portion can cause cracks in the laminate sheet, especially at the corners of the cup portion, which can expose the metal layer of the laminate sheet and reduce the battery life. That is, in the past, there was a limit to the depth of the cup portion, which limited how much the thickness of the electrode assembly could be increased.

[0009] In addition, terraces around the cup portion of the laminate sheet are sealed to form a seal, and a wing folding portion is formed by double-side folding (DSF) a portion of the seal to increase the energy density of the secondary battery. However, there is a limit to how much the seal area can be increased, and there is a problem that the innermost resin layer of the laminate sheet breaks at the wing folding portion. Summary of the Invention [Problem to be solved by the invention]

[0010] One problem to be solved by the present invention is to provide a secondary battery that is not restricted by the thickness of the electrode assembly and does not require the formation of a separate cup portion. [Means for solving the problem]

[0011] A secondary battery according to an embodiment of the present invention may include an electrode assembly, a frame made of an insulating material surrounding a periphery of the electrode assembly to accommodate the electrode assembly, and a pair of exterior sheets sealed to the frame on both sides of the frame to cover the electrode assembly. The frame may have a groove formed therein facing outward to increase a sealing area between the exterior sheets and the frame.

[0012] The height of the electrode assembly and the height of the frame may correspond to each other.

[0013] The groove may extend along the frame.

[0014] The groove may be formed of a plurality of lines parallel to one another.

[0015] The frame may have an opening through which an electrode lead connected to the electrode assembly passes.

[0016] An insulating member surrounding a portion of the electrode lead may be sealed between the pair of exterior sheets outside the opening.

[0017] The frame may have at least one vent hole formed on a side different from the side on which the opening is formed.

[0018] The frame may include an inner circumferential surface facing the electrode assembly, an outer circumferential surface opposite the inner circumferential surface, and a connecting surface connecting the inner circumferential surface and the outer circumferential surface.

[0019] The thickness between the outer peripheral surface and the inner peripheral surface may be smaller than the height of the frame.

[0020] The exterior sheet may include a cover region that covers the electrode assembly, and an edge region that is located around the cover region and is sealed to the connecting surface.

[0021] The cover region and the border region may be coplanar.

[0022] At least one of the pair of exterior sheets may further include a folding region that is folded from the edge region and sealed to the outer circumferential surface.

[0023] The folding regions of the pair of exterior sheets may not overlap each other.

[0024] The frame may be formed with at least one vent hole that is covered by the folding region.

[0025] The outer sheet may further include a seal area connected to the edge area, and the seal areas of the pair of outer sheets may be sealed to each other.

[0026] The frame may have an opening through which an electrode lead connected to the electrode assembly passes, and the sealing area may cover the opening.

[0027] At least one of the sealing regions of the pair of exterior sheets may include a first folding portion folded from the edge region toward the outer circumferential surface, and a second folding portion folded from the first folding portion in a direction opposite to the folding direction of the first folding portion.

[0028] The first folding portion may be sealed to the outer circumferential surface. [Effects of the Invention]

[0029] According to a preferred embodiment of the present invention, there is no need to form a cup portion in the exterior sheet, which has the advantage that there is no risk of cracks occurring in the exterior sheet and there is no restriction on the thickness of the electrode assembly.

[0030] Furthermore, a wide sealing area can be secured between the frame and the exterior sheet, and the sealing force between the frame and the exterior sheet can be strengthened.

[0031] Furthermore, the appearance quality of the secondary battery can be improved.

[0032] Furthermore, since there is no need to DSF the seal portion to form a wing folding portion, there is no risk of the innermost resin layer of the exterior sheet being torn.

[0033] Furthermore, since vent holes can be formed in the frame, more freedom can be given to the design regarding the position, size, number, etc. of the vent holes. Therefore, gas and flames generated by ignition or the like in the secondary battery can be vented to the intended position and direction, and the propagation of flames between secondary batteries or the occurrence of thermal runaway can be delayed.

[0034] Other effects may be included that can be easily predicted by a person skilled in the art from the configuration according to the preferred embodiment of the present invention. [Brief explanation of the drawings]

[0035] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited solely to the matters depicted in such drawings.

[0036] [Figure 1] 1 is a perspective view showing the appearance of a secondary battery according to an embodiment of the present invention; [Figure 2] 1 is an exploded perspective view of a secondary battery according to an embodiment of the present invention; [Figure 3] FIG. 2 is a cross-sectional view taken along line AA' in FIG. [Figure 4] FIG. 2 is a cross-sectional view taken along line BB' in FIG. [Figure 5] FIG. 10 is a plan view of a frame according to another embodiment of the present invention. [Figure 6] FIG. 10 is a side view of a frame according to another embodiment of the present invention. [Figure 7] FIG. 6 is a partial cross-sectional view taken along the line CC' in FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0037] The present invention will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily understand the preferred embodiments of the present invention. However, the present invention can be realized in various different forms and is not limited to the following embodiments.

[0038] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the explanation or related known technologies that may obscure the gist of the present invention will be omitted, and when assigning reference symbols to components in each drawing in this specification, the same or similar reference symbols will be assigned to the same or similar components throughout the specification.

[0039] 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, in accordance with the principle that an inventor can appropriately define the concept of a term in order to best explain his or her invention.

[0040] FIG. 1 is a perspective view showing the appearance of a secondary battery according to one embodiment of the present invention, FIG. 2 is an exploded perspective view of a secondary battery according to one embodiment of the present invention, FIG. 3 is a cross-sectional view taken along line A-A' in FIG. 1, and FIG. 4 is a cross-sectional view taken along line B-B' in FIG. 1.

[0041] A secondary battery 1 according to one embodiment of the present invention may include an electrode assembly 10, a frame 20 surrounding the periphery of the electrode assembly 10 to house the electrode assembly 10, and a pair of exterior sheets 30 sealed to the frame 20 on both sides of the frame 20 to cover the electrode assembly 10.

[0042] The electrode assembly 10 may include a positive electrode, a negative electrode, and a separator interposed between the positive electrode plate and the negative electrode plate to insulate them.

[0043] The type of electrode assembly 10 is not limited. For example, the electrode assembly 10 may be a stack-type electrode assembly in which positive electrodes and negative electrodes are alternately stacked with a separator interposed therebetween. For another example, the electrode assembly 10 may be a jelly-roll-type electrode assembly in which sheet-shaped positive electrodes and negative electrodes are wound together with a separator interposed therebetween.

[0044] The electrode assembly 10 may be provided with electrode tabs protruding in the longitudinal direction thereof. The electrode tabs may include a positive electrode tab connected to the positive electrode and a negative electrode tab connected to the negative electrode.

[0045] The electrode lead 12 may be connected to the electrode assembly 10. More specifically, the electrode lead 12 may be connected to the electrode tabs of the electrode assembly 10. For example, the electrode lead 12 may be welded to the electrode tabs. The electrode leads 12 may be provided in pairs, and the pair of electrode leads 12 may include a positive electrode lead connected to a positive electrode tab and a negative electrode lead connected to a negative electrode tab.

[0046] The insulating member 13 may surround a portion of the electrode lead 12. For example, the insulating member 13 may include an insulating tape. The insulating member 13 can insulate the electrode lead 12 from the exterior sheet 30.

[0047] 2, the pair of electrode leads 12 may extend parallel to each other from one end of the electrode assembly 10. However, this is not limiting, and the pair of electrode leads 12 may extend in opposite directions from both ends of the electrode assembly 10.

[0048] The frame 20 may be made of an insulating material, for example, a plastic material, so that the electrode assembly 10 and the frame 20 can maintain insulation from each other.

[0049] The frame 20 may have higher rigidity than the exterior sheet 30 .

[0050] The frame 20 may have a closed loop shape extending along the periphery of the electrode assembly 10. That is, the frame 20 may form an internal space in which the electrode assembly 10 is housed, and the internal space may be open on both sides in the height direction of the electrode assembly 10 (e.g., a direction parallel to the Z-axis direction).

[0051] The frame 20 may have a substantially rectangular frame shape. More specifically, the frame 20 may include a pair of long sides parallel to the length direction of the electrode assembly 10 (e.g., a direction parallel to the Y axis) and a pair of short sides parallel to the width direction of the electrode assembly 10 (e.g., a direction parallel to the X axis). That is, the frame 20 may include four sides.

[0052] The frame 20 is preferably, but not limited to, being integrally formed.

[0053] The height of the electrode assembly 10 and the height h of the frame 20 may correspond to each other. More specifically, the height of the electrode assembly 10 and the height h of the frame 20 may be the same or similar to each other.

[0054] The cross section of the frame 20 may have a rectangular shape. More specifically, the frame 20 may include an inner circumferential surface 21 facing the electrode assembly 10, an outer circumferential surface 22 located on the opposite side of the inner circumferential surface 21, and a connecting surface 23 connecting the inner circumferential surface 21 and the outer circumferential surface 22. The connecting surface 21 may be the top and bottom surfaces of the frame 20.

[0055] In frame 20, thickness t between inner circumferential surface 21 and outer circumferential surface 22 may be smaller than height h of frame 20. That is, the cross section of frame 20 may be a substantially rectangular shape that is long vertically. This makes it possible to reduce the volume occupied by frame 20 more than necessary, and minimize the reduction in energy density of secondary battery 1 caused by frame 20.

[0056] The frame 20 may have an opening 24 through which the electrode lead 12 passes. The opening 24 may extend from the inner peripheral surface 21 to the outer peripheral surface 22 of the frame 20. As shown in FIG. 2 , the opening 24 may be open to one side (e.g., the lower side) in the height direction of the frame 20, but is not limited thereto.

[0057] The pair of electrode leads 12 may pass through a single opening 24. However, this is not limitative, and it goes without saying that a pair of openings 24 spaced apart from each other may be formed in the frame 20 so that the pair of electrode leads 12 pass through.

[0058] As shown in Figures 1 and 2, when a pair of electrode leads 12 extend parallel to each other from one end of the electrode assembly 10, the opening 24 may be formed on any one of the four sides of the frame 20.

[0059] On the other hand, when the electrode leads 12 extend in opposite directions from both ends of the electrode assembly 10, the openings 24 may be formed on both opposing sides of the four sides of the frame 20.

[0060] The insulating member 13 surrounding a portion of the electrode lead 12 may be sealed between a pair of exterior sheets 30 outside the opening 24. More specifically, the pair of exterior sheets 30 may be sealed to each other outside the side where the opening 24 is formed among the four sides of the frame 20, and a portion of the sheet may be sealed to the insulating member 13.

[0061] The exterior sheet 30 may be heat-sealed to the frame 20 on both sides in the height direction of the frame 20. A pair of exterior sheets 30 may be provided. More specifically, the pair of exterior sheets 30 may include a first exterior sheet 30a sealed to one side (e.g., the upper side) of the frame 20 and a second exterior sheet 30b sealed to the other side (e.g., the lower side) of the frame 20.

[0062] The exterior sheet 30 may be a laminate sheet including a first resin layer 41, a second resin layer 42, and a metal layer 43.

[0063] The first resin layer 41 may be the outermost layer of the exterior sheet 30. The first resin layer 41 can protect the secondary battery 1 from external friction and impact and electrically insulate the electrode assembly 10 from the outside. For example, the first resin layer 41 may include a polyethylene terephthalate (PET) material.

[0064] The second resin layer 42 may be the innermost layer of the exterior sheet 30. The second resin layer 42 may be sealed to the frame 20, or may be in contact with or adjacent to the electrode assembly 10. Therefore, the second resin layer 42 must have insulating properties, and since it also comes into contact with the electrolyte, it must be corrosion-resistant. Furthermore, since it must completely seal the interior and prevent the transfer of substances between the interior and the exterior, it must have high sealing properties. That is, the second resin layer 42 and the frame 20 must have excellent thermal adhesive strength. For example, the second resin layer 42 may include a polypropylene (PP) or polyethylene (PE) material.

[0065] The metal layer 43 may be located between the first resin layer 41 and the second resin layer 42. The metal layer 43 ensures the mechanical strength of the exterior sheet 30, blocks the entry and exit of gases and moisture to and from the exterior of the secondary battery 1, and prevents electrolyte leakage. For example, the metal layer 43 may include an aluminum (AL) material or a stainless steel (STS) material.

[0066] However, the materials of the layers 41, 42, and 43 of the exterior sheet 30 are not limited to the above examples, and can be selected as appropriate.

[0067] In the case of a typical pouch for a secondary battery, a cup portion for accommodating an electrode assembly is formed by drawing and molding the laminate sheet. However, the exterior sheet 30 according to an embodiment of the present invention does not have a cup portion. Therefore, there are advantages in that the cup portion forming process is not required, there is no risk of cracks occurring because the laminate sheet is not stretched, there are no restrictions on the thickness of the electrode assembly 10, and the appearance quality of the secondary battery 1 is improved.

[0068] Meanwhile, each exterior sheet 30 may include a cover region 31 that covers the electrode assembly 10 and an edge region 32 that is located around the periphery of the cover region 31 and is sealed with the connecting surface 23 of the frame 20 .

[0069] The cover area 31 and the edge area 32 may be flush with each other. The cover area 31 and the edge area 32 may be formed flat.

[0070] The cover area 31 may overlap the electrode assembly 10 in the height direction of the secondary battery 1. The cover area 31 may cover an open area in the frame 20. The cover area 31 may contact or be adjacent to the electrode assembly 10.

[0071] The edge region 32 may extend from the cover region 31. The edge region 32 may overlap the frame 20 in the height direction of the secondary battery 1. The edge region 32 may be joined and sealed to the frame 20, more specifically, to the connecting surface 23.

[0072] At least one of the pair of exterior sheets 30 may further include a folding region 33 that is folded from the edge region 32 and sealed to the outer peripheral surface 22 of the frame 20 .

[0073] The folding region 33 may be folded from the edge region 32 toward the outer peripheral surface 22 of the frame 20. The folding region 33 may be folded at approximately 90 degrees relative to the edge region 32. This reduces the risk of tearing the innermost layer of the laminate sheet, i.e., the second resin layer 42, compared to when the seal portion of a conventional secondary battery pouch is folded nearly 180 degrees by double side folding (DSF).

[0074] The folding region 33 may be joined and sealed to the frame 20, more specifically, to the outer peripheral surface 22. This significantly increases the sealing strength between the exterior sheet 30 and the frame 20 without substantially reducing the energy density of the secondary battery 1.

[0075] The folding region 33 may be folded from a portion of the periphery of the edge region 32. More specifically, the folding region 33 may be folded toward and sealed to the outer periphery 22 of the side of the frame 20 where the opening 24 is not formed.

[0076] As an example, as shown in FIG. 2, if an opening 24 is formed on one of the four sides of the frame 20, the folding area 33 may be folded toward at least one of the other three sides of the frame 20 and sealed.

[0077] As another example, if openings 24 are formed on two of the four sides of frame 20, folding area 33 may be folded toward at least one of the other two sides of frame 20 and sealed.

[0078] When each exterior sheet 30 includes a folding region 33, the folding regions 33 of the pair of exterior sheets 30 do not need to overlap each other. More specifically, the folding region 33 of the first exterior sheet 30a may be sealed to an upper portion of the outer peripheral surface 22 of the frame 20, and the folding region 33 of the second exterior sheet 30b may be sealed to a lower portion of the outer peripheral surface 22 of the frame 20. That is, the ends of the folding regions 33 of the first exterior sheet 30a and the second exterior sheet 30b may be spaced apart from each other or may abut each other. This eliminates the need to form the exterior sheets 30 larger than necessary, thereby reducing manufacturing costs.

[0079] However, if necessary, the folding region 33 of the first exterior sheet 30a and the folding region 33 of the second exterior sheet 30b may overlap and be sealed to each other.

[0080] Each exterior sheet 30 may further include a seal region 34 connected to the edge region 32 .

[0081] In each exterior sheet 30, the folding region 33 may be folded from a portion of the periphery of the edge region 32, and the sealing region 34 may be connected to another portion of the periphery of the edge region 32. More specifically, the sealing region 34 may be formed corresponding to the side of the frame 20 where the opening 24 is formed.

[0082] For example, as shown in FIG. 2, if the opening 24 is formed on one of the four sides of the frame 20, the sealing area 34 may be formed corresponding to the one side.

[0083] As another example, if the openings 24 are formed on two of the four sides of the frame 20, the sealing areas 34 may be formed corresponding to the two sides.

[0084] The sealing areas 34 of the pair of exterior sheets 30 may be sealed to each other. The electrode lead 12 may protrude to the outside between the sealing areas 34 of the pair of exterior sheets 30. The insulating member 13 attached to the electrode lead 12 may be sealed between the sealing areas 34 of the pair of exterior sheets 30.

[0085] At least one sealing region 34 of the pair of exterior sheets 30 may be folded twice. More specifically, at least one sealing region 34 of the pair of exterior sheets 30 may include a first folding portion 34a folded from the edge region 32 toward the outer peripheral surface 22 of the frame 20, and a second folding portion 34b folded from the first folding portion 34a in a direction opposite to the folding direction of the first folding portion 34a.

[0086] 2 and 4, each of the sealing regions 34 of the pair of exterior sheets 30 may be folded twice. In this case, the sum of the heights of the first folding portions 34a of the pair of sealing regions 34 may correspond to the height of the frame 20. Also, the second folding portions 34b of the pair of sealing regions 34 may be sealed together. The electrode lead 12 may protrude outward between the pair of second folding portions 34b, and the insulating member 13 may be sealed between the pair of second folding portions 34b.

[0087] As another example, of the pair of exterior sheets 30, the sealing region 34 of the first exterior sheet 30a may be folded twice, and the sealing region 34 of the second exterior sheet 30b may be formed flat and flush with the edge region 32. In this case, the height of the first folded portion 34a of the sealing region 34 of the first exterior sheet 30a may correspond to the height of the frame 20. Furthermore, the second folded portion 34b of the sealing region 34 of the first exterior sheet 30a may be sealed to the sealing region 34 of the second exterior sheet 30b. The electrode lead 12 may protrude outward between the second folded portion 34b of the first exterior sheet 30a and the sealing region 34 of the second exterior sheet 30b, and the insulating member 13 may be sealed between the second folded portion 34b of the first exterior sheet 30a and the sealing region 34 of the second exterior sheet 30b.

[0088] The sealing area 34 , more particularly the first folding portion 34 a , may cover the opening 24 formed in the frame 20 .

[0089] The first folding portion 34a of the sealing region 34 may be sealed to the outer peripheral surface 22 of the frame 20. This can further strengthen the sealing force between the exterior sheet 30 and the frame 20. However, this is not limitative.

[0090] 5 is a plan view of a frame according to another embodiment of the present invention, FIG. 6 is a side view of a frame according to another embodiment of the present invention, and FIG. 7 is a partial cross-sectional view taken along line CC' in FIG.

[0091] Below, the overlapping content with the above content will be cited, and the differences will be mainly explained.

[0092] In the frame 20' of the secondary battery according to another embodiment of the present invention, a groove 25 facing outward from the frame 20' may be formed so that the sealing area with the exterior sheet 30 increases.

[0093] The groove 25 may extend along the frame 20'. More specifically, the groove 25 may extend in the circumferential direction of the frame 20'. However, the groove 25 is not limited to this, and the groove 25 may be formed obliquely so as to form a predetermined angle with the extension direction of the frame 20'.

[0094] The grooves 25 may be formed in a plurality of lines parallel to each other.

[0095] Even when a plurality of protrusions are formed on the frame 20 ′, the portions between the plurality of protrusions can be considered as grooves 25 .

[0096] The grooves 25 may face the outside of the frame 20'. More specifically, the grooves 25 may be formed in the connecting surface 23 and / or the outer peripheral surface 22 of the frame. Therefore, the exterior sheet 30 can easily cover the grooves 25 facing the outside of the frame 20' from the outside.

[0097] The groove 25 may be formed in the connecting surface 23 of the frame 20'. The groove 25 formed in the connecting surface 23 may be sealed with the edge region 32 of the exterior sheet 30.

[0098] The groove 25 may be formed in the outer peripheral surface 22 of the frame 20′. The groove 25 formed in the outer peripheral surface 22 may be sealed to the folding region 33 of the exterior sheet 30 or to the first folding portion 34a of the sealing region 34.

[0099] The grooves 25 increase the sealing area, so that the sealing force between the frame 20 and the exterior sheet 30 can be further strengthened.

[0100] On the other hand, the frame 20' may have at least one vent hole 26 formed on a side different from the side on which the open portion 24 (see FIG. 2) is formed.

[0101] The vent hole 26 may be formed penetrating from the inner peripheral surface 21 to the outer peripheral surface 22 of the frame 20. The vent hole 26 may be covered by a folding region 33 of the exterior sheet 30.

[0102] The area of ​​the outer peripheral surface 22 of the frame 20 around the vent hole 26 may be sealed with the folding region 33 of the exterior sheet 30. Therefore, during normal operation of the secondary battery 1, the vent hole 26 may be in a closed state.

[0103] On the other hand, if a fire or gas occurs in the electrode assembly 10 due to abnormal operation of the secondary battery 1, the gas increases the internal pressure of the secondary battery 1, and the seal around the vent hole 26 is released first. Therefore, the gas can be easily vented to the outside of the secondary battery 1 through the vent hole 26.

[0104] For this purpose, the portion of the folding region 33 of the exterior sheet 30 that is sealed around the vent hole 26 may include a weakly sealed portion or an unsealed portion. Alternatively, the gap between the end of the folding region 33 and the vent hole 26 can be narrowed to reduce the sealed area. However, this is not limiting, and any configuration is possible as long as the seal around the vent hole 26 is released first.

[0105] By forming the vent hole 26 on a side different from the side on which the open portion 24 (see FIG. 2) is formed, it is possible to delay the venting of the dust-containing gas and flame on the electrode lead 12 side. This makes it possible to prevent the spread of fire and the occurrence of thermal runaway in a battery module or battery pack including a plurality of secondary batteries 1.

[0106] The above description merely exemplifies the technical concept of the present invention, and various modifications and variations may be made by a person having ordinary knowledge in the technical field to which the present invention pertains without departing from the essential characteristics of the present invention.

[0107] Therefore, the embodiments disclosed in the present invention are for illustrative purposes only and are not intended to limit the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by such embodiments.

[0108] The scope of protection of the present invention should be interpreted by the appended claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention. [Explanation of symbols]

[0109] 1 Secondary battery 10 Electrode assembly 12 electrode leads 13 Insulating material 20 frames 21 Inner surface 22 Outer surface 23 Connecting surface 24 Open area 25 groove 26 Vent hole 30 Exterior Sheet 31 Coverage Area 32 Edge region 33 folding regions 34 Sealing Area 41 1st resin layer 42 Second resin layer 43 Metal layer

Claims

1. an electrode assembly; a frame having an insulating material and surrounding a periphery of the electrode assembly to accommodate the electrode assembly; a pair of exterior sheets sealed to the frame on both sides of the frame to cover the electrode assembly; The secondary battery, wherein the frame has a groove formed therein that faces outward from the frame so as to increase the sealing area between the exterior sheet and the frame.

2. The secondary battery of claim 1 , wherein the height of the electrode assembly and the height of the frame correspond to each other.

3. The secondary battery according to claim 1 , wherein the groove extends along the frame.

4. The secondary battery according to claim 3 , wherein the groove is formed of a plurality of lines parallel to each other.

5. The secondary battery according to claim 1 , wherein the frame has an opening through which an electrode lead connected to the electrode assembly passes.

6. The secondary battery according to claim 5 , wherein the insulating member surrounding a portion of the electrode lead is sealed between the pair of exterior sheets outside the opening.

7. The secondary battery according to claim 5 , wherein the frame has at least one vent hole formed on a side different from the side on which the open portion is formed.

8. The frame is an inner circumferential surface facing the electrode assembly; an outer circumferential surface located opposite the inner circumferential surface; The secondary battery according to claim 1 , further comprising a connecting surface connecting the inner circumferential surface and the outer circumferential surface.

9. The secondary battery according to claim 8 , wherein a thickness between the outer peripheral surface and the inner peripheral surface is smaller than a height of the frame.

10. The exterior sheet is a cover region covering the electrode assembly; The secondary battery according to claim 8 , further comprising an edge area located on the periphery of the cover area and sealed with the connecting surface.

11. The secondary battery according to claim 10 , wherein the cover area and the edge area are flush with each other.

12. At least one of the pair of exterior sheets is The secondary battery according to claim 10 , further comprising a folding region that is folded from the edge region and sealed to the outer circumferential surface.

13. The secondary battery according to claim 12 , wherein the folding regions of the pair of exterior sheets do not overlap each other.

14. The secondary battery according to claim 12 , wherein the frame has at least one vent hole formed therein and the vent hole is covered by the folding region.

15. the exterior sheet further includes a seal region connected to the edge region; The secondary battery according to claim 10 , wherein the sealing areas of the pair of exterior sheets are sealed to each other.

16. The frame has an opening through which an electrode lead connected to the electrode assembly passes, The secondary battery according to claim 15 , wherein the sealing area covers the opening.

17. The sealing area of ​​at least one of the pair of exterior sheets is a first folding portion folded from the edge region toward the outer circumferential surface; The secondary battery of claim 15 , further comprising: a second folding portion folded from the first folding portion in a direction opposite to the folding direction of the first folding portion.

18. The secondary battery of claim 17 , wherein the first folding portion is sealed to the outer circumferential surface.

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