Secondary battery

Abstract

A secondary battery according to an embodiment of the present disclosure may include: an electrode assembly; a frame surrounding a periphery of the electrode assembly to accommodate the electrode assembly, and including an insulating material; and a pair of outer sheets sealed with the frame at both sides of the frame, respectively, to cover the electrode assembly. A groove facing an exterior of the frame may be defined in the frame such that a sealing surface area between the exterior sheet and the frame increases.

Description

Technical Field

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of priority of 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 disclosures of which are incorporated herein by reference. Technical Field

[0004] The present disclosure relates to a secondary battery including an electrode assembly and an exterior sheet. Background Art

[0005] Generally, types of secondary batteries include nickel - cadmium batteries, nickel - metal hydride batteries, lithium - ion batteries, lithium - ion polymer batteries, etc. These secondary batteries are applied and used not only in small products such as digital cameras, P - DVDs, MP3Ps, mobile phones, PDAs, portable game devices, power tools, and electric bicycles, but also in large products such as electric vehicles and hybrid vehicles that require high output, energy storage systems for storing surplus generated electricity or new renewable energy, and backup energy storage systems.

[0006] To manufacture these secondary batteries, first, a positive electrode current collector and a negative electrode current collector are coated with an electrode active material slurry to manufacture a positive electrode and a negative electrode, and then the positive electrode and the negative electrode are disposed on both sides of a separator to provide an electrode assembly having a predetermined shape. Then, a battery case houses the electrode assembly, and after injecting an electrolyte, the battery case is sealed.

[0007] According to the material of the case housing the electrode assembly, secondary batteries are classified into a pouch type, a can type, etc. In the pouch type, the electrode assembly is housed in a pouch made of a flexible polymer material. In the can type, the electrode assembly is housed in a case made of a material such as metal or plastic.

[0008] Generally, a pouch - type battery case is manufactured by performing a pressing process on a flexible laminated sheet to form a cup portion. When forming the cup portion, the electrode assembly is housed inside the cup portion, and its sides are sealed to manufacture a secondary battery.

[0009] This pressing process is performed by stretch - forming the laminated sheet by inserting it into a molding device such as a pressing device, and the laminated sheet is stretched by applying pressure to the laminated sheet using a punch.

[0010] However, as the thickness of the electrode assembly increases, the depth of the molded cup portion in the laminate increases. Therefore, there is a concern that the cup portion is overstretched, resulting in cracks in the laminate (especially at the corners of the cup portion), and there is a problem that the cracks cause the metal layer of the laminate to be exposed, thereby reducing the life of the battery. That is, according to the related art, the depth of the cup portion is limited, resulting in a limitation in the increase in the thickness of the electrode assembly.

[0011] In addition, in the laminate, the platforms around the cup portion are sealed to each other to form a sealing portion, and a double-sided fold (DSF) is performed on a part of the sealing portion to form a wing fold portion, thereby increasing the energy density of the secondary battery. However, there is a limit to increasing the surface area of the sealing portion, and there is a problem that the innermost resin layer of the laminate is broken in the wing fold portion. SUMMARY OF THE INVENTION

[0012] TECHNICAL PROBLEM

[0013] In order to solve the above problems, an object of the present disclosure is to provide a secondary battery that has no limitation on the thickness of the electrode assembly and does not require a separate molding of the cup portion.

[0014] TECHNICAL SOLUTION

[0015] A secondary battery according to an embodiment of the present disclosure may include: an electrode assembly; a frame that surrounds the periphery of the electrode assembly to accommodate the electrode assembly, and the frame includes an insulating material; and a pair of outer sheets that are respectively sealed to the frame on both sides of the frame to cover the electrode assembly. A groove is defined in the frame facing the outside of the frame, so that the sealing surface area between the outer sheet and the frame is increased.

[0016] The height of the electrode assembly and the height of the frame may correspond to each other.

[0017] The groove may extend along the frame.

[0018] The grooves may be provided in multiple rows parallel to each other.

[0019] An opening may be defined in the frame, and an electrode lead connected to the electrode assembly passes through the opening.

[0020] An insulating member surrounding a part of the electrode lead may be sealed between the pair of outer sheets outside the opening.

[0021] At least one exhaust hole may be defined in the frame, and the at least one exhaust hole is provided on a side other than the side where the opening is defined.

[0022] The frame may include: an inner peripheral surface facing the electrode assembly; an outer peripheral surface provided on the opposite side of the inner peripheral surface; and a connecting surface connecting the inner peripheral surface and the outer peripheral surface to each other.

[0023] The thickness between the outer peripheral surface and the inner peripheral surface can be less than the height of the frame.

[0024] Each outer sheet may include: a lid region that covers the electrode assembly; and an edge region that is provided to surround the lid region and is sealed to the connection surface.

[0025] The lid region and the edge region may be coplanar.

[0026] At least one of the pair of outer sheets may further include a folding region that folds from the edge region and is sealed to the outer peripheral surface.

[0027] The folding regions of the pair of outer sheets may not overlap each other.

[0028] At least one exhaust hole covered by the folding region may be defined in the frame.

[0029] The outer sheet may further include a sealing region connected to the edge region, and the sealing regions of the pair of outer sheets may be sealed to each other.

[0030] An opening may be defined in the frame, an electrode lead connected to the electrode assembly passes through the opening, and the sealing region may cover the opening.

[0031] The sealing region of at least one of the pair of outer sheets may include: a first folding portion that folds from the edge region toward the outer peripheral surface; and a second folding portion that folds from the first folding portion in a direction opposite to the folding direction of the first folding portion.

[0032] The first folding portion may be sealed to the outer peripheral surface.

[0033] Advantageous Effects

[0034] According to a preferred embodiment of the present disclosure, since there is no need to mold a cup portion in the outer sheet, there is an advantage that there is no need to worry about cracks in the outer sheet and there is no limitation on the thickness of the electrode assembly.

[0035] In addition, a large sealing surface area between the frame and the outer sheet can be ensured to increase the sealing strength between the frame and the outer sheet.

[0036] In addition, the appearance quality of the secondary battery can be improved.

[0037] In addition, since there is no need to perform DSF on the sealing portion to form a wing folding portion, there is no need to worry about cracking of the innermost resin layer of the outer sheet.

[0038] In addition, the frame may be defined with exhaust holes, enabling more freedom in the design of the formation position, size, quantity, etc. of the exhaust holes. Therefore, the gases and flames generated due to fire or the like in the secondary battery can be discharged to a desired position and in a desired direction, and the spread of flames between secondary batteries or the occurrence of thermal runaway in the secondary battery can be delayed.

[0039] In addition, effects that can be easily predicted by those of ordinary skill in the art from the configurations of the preferred embodiments according to the present disclosure may be included. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The following drawings attached to this specification illustrate the preferred embodiments of the present disclosure and are used to further understand the technical spirit of the present disclosure and the detailed description of the present disclosure. The present disclosure should not be construed as being limited to the drawings.

[0041] Figure 1 is a perspective view showing the appearance of a secondary battery according to an embodiment of the present disclosure.

[0042] Figure 2 is an exploded perspective view of a secondary battery according to an embodiment of the present disclosure.

[0043] Figure 3 is a cross-sectional view taken along line A-A' in Figure 1 .

[0044] Figure 4 is a cross-sectional view taken along line B-B' in Figure 1 .

[0045] Figure 5 is a plan view of a frame according to another embodiment of the present disclosure.

[0046] Figure 6 is a side view of a frame according to another embodiment of the present disclosure.

[0047] Figure 7 is a cross-sectional view taken along line C-C' in Figure 5 . DETAILED DESCRIPTION

[0048] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the drawings, enabling those skilled in the art to which the present disclosure pertains to easily implement the present disclosure. However, the present disclosure can be implemented in different forms and should not be construed as being limited by the embodiments set forth herein.

[0049] To clearly describe the present disclosure, detailed descriptions of parts irrelevant to the description or related well-known technologies that may unnecessarily obscure the subject matter of the present disclosure will be excluded. Throughout the specification, the same reference numerals denote the same elements.

[0050] In addition, terms or words used in the specification and claims should not be construed restrictively in accordance with their ordinary or dictionary meanings, but rather should be interpreted, based on the principle that the inventor can appropriately define the concept of the terms, as meanings and concepts that conform to the scope of the present disclosure, so as to best describe and explain his or her invention.

[0051] Figure 1 is a perspective view showing the appearance of a secondary battery according to an embodiment of the present disclosure. Figure 2 is an exploded perspective view of a secondary battery according to an embodiment of the present disclosure. Figure 3 is along Figure 1 a cross-sectional view taken along line A-A' in Figure 4 is along Figure 1 a cross-sectional view taken along line B-B' in

[0052] A secondary battery 1 according to an embodiment of the present disclosure may include an electrode assembly 10, a frame 20 surrounding the periphery of the electrode assembly 10 to accommodate the electrode assembly 10, and a pair of exterior sheets 30 respectively sealed to the frame 20 on both sides of the frame 20 to cover the electrode assembly 10.

[0053] The electrode assembly 10 may include a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode to insulate the positive electrode and the negative electrode from each other.

[0054] The type of the electrode assembly 10 is not limited. As an example, the electrode assembly 10 may be a stacked electrode assembly, in which the positive electrode and the negative electrode are alternately stacked, and the separator is located between the positive electrode and the negative electrode. As another example, the electrode assembly 10 may be a wound electrode assembly, in which a sheet-shaped positive electrode and a sheet-shaped negative electrode are wound together, and the separator is located between the positive electrode and the negative electrode.

[0055] 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.

[0056] An electrode lead 12 may be connected to the electrode assembly 10. More specifically, the electrode lead 12 may be connected to the electrode tab of the electrode assembly 10. For example, the electrode lead 12 may be welded to the electrode tab. The electrode lead 12 may be provided as a pair, and the pair of electrode leads 12 may include a positive electrode lead connected to the positive electrode tab and a negative electrode lead connected to the negative electrode tab.

[0057] An insulating member 13 may surround a part of the electrode lead 12. For example, the insulating member 13 may include an insulating tape. The insulating member 13 may insulate the electrode lead 12 and the exterior sheet 30 from each other.

[0058] As Figure 2As shown, a pair of electrode leads 12 may extend from one end of the electrode assembly 10 and be parallel to each other. However, the present disclosure is not limited thereto, and a pair of electrode leads 12 may extend from two ends of the electrode assembly 10 in opposite directions from each other.

[0059] The frame 20 may include an insulating material. For example, the frame 20 may include a plastic material. Thus, insulation between the electrode assembly 10 and the frame 20 can be maintained.

[0060] The frame 20 may have a higher stiffness than the outer sheet 30.

[0061] The frame 20 may have a closed loop extending along the periphery of the electrode assembly 10. That is, the frame 20 may define an internal space for accommodating the electrode assembly 10, and the internal space may be open to both sides in the height direction of the electrode assembly 10 (e.g., a direction parallel to the Z-axis direction).

[0062] The frame 20 may have a generally rectangular frame shape. More specifically, the frame 20 may have a pair of long sides parallel to the entire length direction of the electrode assembly 10 (e.g., a direction parallel to the Y-axis direction) and a pair of short sides parallel to the entire width direction of the electrode assembly 10 (e.g., a direction parallel to the X-axis direction). That is, the frame 20 may have four sides.

[0063] The frame 20 may be provided integrally, but is not limited thereto.

[0064] The height of the electrode assembly 10 and the height 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.

[0065] The cross-section of the frame 20 may be rectangular. More specifically, the frame 20 may include an inner peripheral surface 21 facing the electrode assembly 10, an outer peripheral surface 22 provided on the opposite side of the inner peripheral surface 21, and a connecting surface 23 connecting the inner peripheral surface 21 and the outer peripheral surface 22 to each other. The connecting surface 23 may be each of the top surface and the bottom surface of the frame 20.

[0066] In the frame 20, the thickness t between the inner peripheral surface 21 and the outer peripheral surface 22 may be less than the height h of the frame 20. That is, the cross-section of the frame 20 may have a generally vertically elongated rectangle. Thus, the volume unnecessarily occupied by the frame 20 can be reduced, and a decrease in the energy density of the secondary battery 1 due to the frame 20 can be minimized.

[0067] An opening 24 may be defined in the frame 20, and the electrode lead 12 passes through the opening 24. The opening 24 may penetrate from the inner peripheral surface 21 of the frame 20 to the outer peripheral surface 22. As Figure 2As shown, the opening 24 may open to one side (e.g., the lower side) of the frame 20 in the height direction, but is not limited thereto.

[0068] A pair of electrode leads 12 may pass through a single opening 24. However, the present disclosure is not limited thereto. For example, a pair of openings 24 spaced apart from each other may be defined in the frame 20 such that a pair of electrode leads 12 pass therethrough.

[0069] As Figure 1 and Figure 2 shown, when a pair of electrode leads 12 extend from one end of the electrode assembly 10 and are parallel to each other, the opening 24 may be defined in one of the four sides of the frame 20.

[0070] Alternatively, when the electrode leads 12 extend from two ends of the electrode assembly 10 in opposite directions, the opening 24 may be defined in each of the two opposite sides of the four sides of the frame 20.

[0071] An insulating member 13 surrounding a part of the electrode lead 12 may be sealed between a pair of outer sheets 30 outside the opening 24. More specifically, a pair of outer sheets 30 may be sealed to each other outside the side of the four sides of the frame 20 where the opening 24 is defined, and a part thereof may be sealed to the insulating member 13.

[0072] The outer sheet 30 may be heat-sealed to the frame 20 on both sides in the height direction of the frame 20. The outer sheet 30 may be provided as a pair. More specifically, a pair of outer sheets 30 may include a first outer sheet 30a sealed at one side (e.g., the upper side) of the frame 20 and a second outer sheet 30b sealed at the other side (e.g., the lower side) of the frame 20.

[0073] The outer sheet 30 may be a laminated sheet including a first resin layer 41, a second resin layer 42, and a metal layer 43.

[0074] The first resin layer 41 may be the outermost layer of the outer sheet 30. The first resin layer 41 may electrically insulate the electrode assembly 10 from the outside while protecting the secondary battery 1 from friction and collision with the outside. For example, the first resin layer 41 may contain a polyethylene terephthalate (PET) material.

[0075] The second resin layer 42 can be the innermost layer of the outer sheet 30. The second resin layer 42 can be sealed with the frame 20 and can be in contact with or adjacent to the electrode assembly 10. Therefore, the second resin layer 42 needs to have insulating properties, and since the second resin layer 42 is also in contact with the electrolyte, it needs to have corrosion resistance. In addition, since the interior needs to be completely sealed to block the movement of substances between the interior and the exterior, high sealing performance must be achieved. That is to say, the second resin layer 42 and the frame 20 need to have excellent thermal bonding strength. For example, the second resin layer 42 can include a polypropylene (PP) or polyethylene (PE) material.

[0076] The metal layer 43 can be disposed between the first resin layer 41 and the second resin layer 42. The metal layer 43 can ensure the mechanical strength of the outer sheet 30, block the entry of gases, moisture, etc. from outside the secondary battery 1, and prevent the leakage of the electrolyte. For example, the metal layer 43 can include an aluminum (AL) material or a stainless steel (STS) material.

[0077] However, the materials of each of the layers 41, 42, and 43 of the outer sheet 30 are not limited to the foregoing examples and can be appropriately selected.

[0078] In a conventional pouch of a secondary battery, stretch forming is performed on a laminated sheet to mold a cup portion that houses the electrode assembly. However, in the outer sheet 30 according to an embodiment of the present disclosure, no cup portion is provided. Therefore, the present disclosure has the advantages of not requiring a process of molding a cup portion, not stretching the laminated sheet, thus not worrying about cracks occurring, having no limitation on the thickness of the electrode assembly 10, and improving the appearance quality of the secondary battery 1.

[0079] Each outer sheet 30 can include a lid region 31 that covers the electrode assembly 10 and an edge region 32 that is provided to surround the lid region 31 and is sealed with the edge of the connection surface 23 of the frame 20.

[0080] The lid region 31 and the edge region 32 can be coplanar. The lid region 31 and the edge region 32 can be provided to be flat.

[0081] The lid region 31 can overlap the electrode assembly 10 in the height direction of the secondary battery 1. The lid region 31 can cover the region that is open in the frame 20. The lid region 31 can be in contact with or adjacent to the electrode assembly 10.

[0082] The edge region 32 can extend from the lid region 31. The edge region 32 can overlap the frame 20 in the height direction of the secondary battery 1. The edge region 32 can be joined and sealed with the frame 20, more specifically, joined and sealed with the connection surface 23.

[0083] At least one of the pair of outer sheets 30 may also include being folded from the edge region 32 and sealed to the folded region 33 of the outer peripheral surface 22 of the frame 20.

[0084] The folded region 33 may be folded from the edge region 32 toward the outer peripheral surface 22 of the frame 20. The folded region 33 may be folded relative to the edge region 32 by approximately 90 degrees. Accordingly, when compared with the case where the sealing portion of a pouch for a secondary battery according to the related art is folded by double-sided folding (DSF) by approximately 180 degrees, the concern about the rupture of the innermost layer of the laminated sheet (i.e., the second resin layer 42) can be reduced.

[0085] The folded region 33 may be joined and sealed to the frame 20, more specifically, joined and sealed to the outer peripheral surface 22. Accordingly, the energy density of the secondary battery 1 is hardly reduced, and the sealing strength between the outer sheet 30 and the frame 20 can also be significantly increased.

[0086] The folded region 33 may be folded from a part of the periphery of the edge region 32. More specifically, the folded region 33 may be sealed by being folded toward the outer peripheral surface 22 of the side of the frame 20 that does not define the opening 24.

[0087] As an example, as Figure 2 shown, when the opening 24 is defined in one of the four sides of the frame 20, the folded region 33 may be sealed by being folded toward at least one of the other three sides of the frame 20.

[0088] As another example, when the opening 24 is defined in each of two of the four sides of the frame 20, the folded region 33 may be sealed by being folded toward at least one of the other two sides of the frame 20.

[0089] When each outer sheet 30 includes the folded region 33, the folded regions 33 of the pair of outer sheets 30 may not overlap each other. More specifically, the folded region 33 of the first outer sheet 30a may be sealed to a part at the upper side of the outer peripheral surface 22 of the frame 20, and the folded region 33 of the second outer sheet 30b may be sealed to a part at the lower side of the outer peripheral surface 22 of the frame 20. That is, the end of the folded region 33 of the first outer sheet 30a and the end of the folded region 33 of the second outer sheet 30b may be spaced apart from each other by a predetermined distance or may be in contact with each other. Accordingly, the outer sheet 30 does not need to have an unnecessarily large size, so that the manufacturing cost is reduced.

[0090] However, when necessary, the folded region 33 of the first outer sheet 30a and the folded region 33 of the second outer sheet 30b may partially overlap and be sealed to each other.

[0091] Each outer sheet 30 may also include a sealing region 34 connected to the edge region 32.

[0092] In each outer sheet 30, the folding region 33 may be folded from a part of the periphery of the edge region 32, and the sealing region 34 may be connected to another part of the periphery of the edge region 32. More specifically, the sealing region 34 may be provided to correspond to the side of the frame 20 that defines the opening 24.

[0093] As an example, as Figure 2 shown, when an opening 24 is defined in one of the four sides of the frame 20, the sealing region 34 may be provided to correspond to that one side.

[0094] As an example, when an opening 24 is defined in each of two of the four sides of the frame 20, the sealing region 34 may be provided to correspond to each of the two sides.

[0095] The sealing regions 34 of a pair of outer sheets 30 may be sealed to each other. The electrode lead 12 may protrude to the outside through the gap between the sealing regions 34 of the pair of outer sheets 30. The insulating member 13 attached to the electrode lead 12 may be sealed between the sealing regions 34 of the pair of outer sheets 30.

[0096] At least one sealing region 34 of a pair of outer sheets 30 may be folded twice. More specifically, at least one sealing region 34 of a pair of outer sheets 30 may include a first folded portion 34a folded from the edge region 32 toward the outer peripheral surface 22 of the frame 20 and a second folded portion 34b folded from the first folded portion 34a in a direction opposite to the folding direction of the first folded portion 34a.

[0097] As an example, as Figure 2 and Figure 4 shown, each sealing region 34 of a pair of outer sheets 30 may be folded twice. In this case, the value obtained by adding the heights of the first folded portions 34a of the pair of sealing regions 34 may correspond to the height of the frame 20. In addition, the second folded portions 34b of the pair of sealing regions 34 may be sealed to each other. The electrode lead 12 may protrude to the outside through the gap between the pair of second folded portions 34b, and the insulating member 13 may be sealed between the pair of second folded portions 34b.

[0098] As another example, the sealing area 34 of the first outer sheet 30a of a pair of outer sheets 30 may be folded twice, and the sealing area 34 of the second outer sheet 30b may be coplanar with the edge area 32 to be flat. In this case, the height of the first folding portion 34a of the sealing area 34 of the first outer sheet 30a may correspond to the height of the frame 20. Additionally, the second folding portion 34b of the sealing area 34 of the first outer sheet 30a may be sealed to the sealing area 34 of the second outer sheet 30b. The electrode lead 12 may protrude to the outside through the gap between the second folding portion 34b of the first outer sheet 30a and the sealing area 34 of the second outer sheet 30b, and the insulating member 13 may be sealed between the second folding portion 34b of the first outer sheet 30a and the sealing area 34 of the second outer sheet 30b.

[0099] The sealing area 34 (more specifically, the first folding portion 34a) may cover the opening 24 defined in the frame 20.

[0100] The first folding portion 34a of the sealing area 34 may be sealed to the outer peripheral surface 22 of the frame 20. Thus, the sealing strength between the outer sheet 30 and the frame 20 may be further increased. However, the present disclosure is not limited thereto.

[0101] Figure 5 is a plan view of a frame according to another embodiment of the present disclosure. Figure 6 is a side view of a frame according to another embodiment of the present disclosure. Figure 7 is along Figure 5 a cross-sectional view taken along line C-C' in

[0102] Hereinafter, another embodiment will be described by applying the same content as above, and differences will be focused on.

[0103] In a frame 20' according to another embodiment of the present disclosure, a groove 25 facing the outside of the frame 20' may be defined to increase the sealing surface area with the outer sheet 30.

[0104] The groove 25 may extend along the frame 20'. More specifically, the groove 25 may extend in the peripheral direction of the frame 20'. However, the present disclosure is not limited thereto, and the groove 25 may be defined to be inclined such that the groove 25 has a predetermined angle with respect to the extending direction of the frame 20'.

[0105] The grooves 25 may be provided in multiple rows parallel to each other.

[0106] Even when a plurality of protrusions are provided on the frame 20', the portions between the plurality of protrusions may be interpreted as the grooves 25.

[0107] The groove 25 can face the outside of the frame 20'. More specifically, the groove 25 can be defined on the connection surface 23 and / or the outer peripheral surface 22 of the frame. Therefore, the groove 25 facing the outside of the frame 20' can be easily covered from the outside by the outer sheet 30.

[0108] The groove 25 can be defined in the connection surface 23 of the frame 20'. The groove 25 defined in the connection surface 23 can be sealed with the edge region 32 of the outer sheet 30.

[0109] The groove 25 can be defined in the outer peripheral surface 22 of the frame 20'. The groove 25 defined in the outer peripheral surface 22 can be sealed with the folding region 33 of the outer sheet 30, or sealed with the first folding portion 34a of the sealing region 34.

[0110] As the sealing surface area increases due to the groove 25, the sealing strength between the frame 20 and the outer sheet 30 can be further increased.

[0111] At least one exhaust hole 26 can be defined in the frame 20', and at least one exhaust hole 26 is provided on a side other than the side where the opening 24 is defined (see Figure 2 ).

[0112] The exhaust hole 26 can penetrate from the inner peripheral surface 21 of the frame 20 to the outer peripheral surface 22. The exhaust hole 26 can be covered by the folding region 33 of the outer sheet 30.

[0113] The peripheral portion of the exhaust hole 26 on the outer peripheral surface 22 of the frame 20 can be sealed with the folding region 33 of the outer sheet 30. Therefore, during the normal operation of the secondary battery 1, the exhaust hole 26 can be in a closed state.

[0114] However, when a flame or gas is generated in the electrode assembly 10 due to the abnormal operation of the secondary battery 1, the internal pressure of the secondary battery 1 may increase due to the gas, and the seal of the peripheral portion of the exhaust hole 26 can be released first. Therefore, the gas can be easily discharged to the outside of the secondary battery 1 through the exhaust hole 26.

[0115] For this purpose, a part of the folding region 33 of the outer sheet 30 that is sealed with the peripheral portion of the exhaust hole 26 can include a weak seal portion or a non-seal portion. Alternatively, the distance between the end of the folding region 33 and the exhaust hole 26 can be reduced to reduce the sealing surface area. However, the present disclosure is not limited thereto, and this configuration is not limited as long as the seal of the peripheral portion of the exhaust hole 26 can be released first.

[0116] Since the exhaust hole 26 is defined on a side other than the side where the opening 24 is defined (see Figure 2) the side other than the side, so that the discharge of the gas including dust and the flame to the side of the electrode lead 12 can be delayed. Therefore, the flame spread or thermal runaway can be prevented from occurring in the battery module or battery pack including a plurality of secondary batteries 1.

[0117] The description of the present disclosure is intended to be illustrative, and various changes and modifications can be made by those of ordinary skill in the art to which the present disclosure pertains without departing from the spirit and scope of the present disclosure defined by the appended claims.

[0118] Therefore, the embodiments described herein are used to describe the technical spirit of the present disclosure rather than to limit it. The scope of the technical spirit of the present disclosure is not limited by the embodiments.

[0119] In addition, the protection scope of the present disclosure should be determined by a reasonable interpretation of the appended claims, and all technical concepts falling within the equivalent scope of the present application should be interpreted as being within the scope of the claims of the present application.

[0120] [Description of Reference Numerals]

[0121] 1: Secondary battery 10: Electrode assembly

[0122] 12: Electrode lead 13: Insulating member

[0123] 20: Frame 21: Inner peripheral surface

[0124] 22: Outer peripheral surface 23: Connecting surface

[0125] 24: Opening 25: Groove

[0126] 26: Exhaust hole 30: External sheet

[0127] 31: Cover area 32: Edge area

[0128] 33: Folding area 34: Sealing area

[0129] 41: First resin layer 42: Second resin layer

[0130] 43: Metal layer

Claims

1. A secondary battery, comprising: An electrode assembly; A frame configured to surround the periphery of the electrode assembly to accommodate the electrode assembly, and the frame contains an insulating material; And A pair of outer sheets, the pair of outer sheets being sealed to the frame on both sides of the frame respectively to cover the electrode assembly, Wherein, a groove is defined in the frame facing the outside of the frame, so that the sealing surface area between the outer sheet and the frame is increased.

2. The secondary battery according to 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 grooves are arranged in multiple rows parallel to each other.

5. The secondary battery according to claim 1, wherein, An opening is defined in the frame, and an electrode lead connected to the electrode assembly passes through the opening.

6. The secondary battery according to claim 5, wherein, An insulating member configured to surround a part of the electrode lead is sealed between the pair of outer sheets outside the opening.

7. The secondary battery according to claim 5, wherein, At least one exhaust hole is defined in the frame, and the at least one exhaust hole is provided on a side other than the side where the opening is defined.

8. The secondary battery according to claim 1, wherein, The frame includes: An inner peripheral surface facing the electrode assembly; An outer peripheral surface provided on the side opposite to the inner peripheral surface; and A connecting surface configured to connect the inner peripheral surface and the outer peripheral surface to each other.

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

10. The secondary battery according to claim 8, wherein, Each of the outer sheets includes: A cover region configured to cover the electrode assembly; and An edge region provided at the periphery of the cover region and sealed to the connecting surface.

11. The secondary battery according to claim 10, wherein, The cover region and the edge region are coplanar.

12. The secondary battery according to claim 10, wherein, At least one of the pair of outer sheets further includes a folding region that folds from the edge region and is sealed to the outer peripheral surface.

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

14. The secondary battery according to claim 12, wherein, At least one exhaust hole covered by the folding region is defined in the frame.

15. The secondary battery according to claim 10, wherein, The outer sheet further includes a sealing region connected to the edge region, Wherein, the sealing regions of the pair of outer sheets are sealed to each other.

16. The secondary battery according to claim 15, wherein, An opening is defined in the frame, and an electrode lead connected to the electrode assembly passes through the opening, Wherein, the sealing region covers the opening.

17. The secondary battery according to claim 15, wherein, The sealing region of at least one of the pair of outer sheets includes: A first folding portion that folds from the edge region toward the outer peripheral surface; and A second folding portion that folds from the first folding portion in a direction opposite to the folding direction of the first folding portion.

18. The secondary battery according to claim 15, wherein, The first folding portion is sealed to the outer peripheral surface.

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