Secondary battery and battery pack comprising same

Abstract

The invention relates to a secondary battery and a battery pack including the same. A secondary battery according to one aspect of the present invention comprises: an electrode assembly extending in one direction; an outer film covering a portion of the electrode assembly; and a cap covering a remaining portion of the electrode assembly, in which the cap may include: a covering portion covering one side portion of the electrode assembly in the extending direction; a connection portion including a coupling portion disposed on an outer surface of the cover portion and coupled to the outer film; and a terminal portion at least partially exposed to an outer surface of the cover portion and electrically connected to the electrode assembly, in which a coupling portion of the connection portion may include a first layer including a first resin, and a second layer including a second resin. And has an outer surface allowing coupling with an inner surface of the outer film and an inner surface allowing coupling with an outer surface of the cover portion.

Description

Technical Field

[0001] This invention relates to secondary batteries and battery packs including the secondary batteries. Background Technology

[0002] In recent years, due to the consumption of fossil fuels, rising energy prices, and increased concern about environmental pollution, the demand for eco-friendly alternative energy sources is becoming an indispensable factor in future life. Therefore, research on various power generation technologies such as solar, wind, and tidal power continues, and energy storage devices such as batteries for more efficient use of generated electricity are also receiving significant attention.

[0003] Furthermore, with technological advancements and the increasing demand for battery-powered electronic mobile devices and electric vehicles, the demand for batteries as an energy source is rapidly increasing. Consequently, extensive research has been conducted on batteries capable of meeting diverse needs.

[0004] Batteries that store electrical energy can generally be divided into primary batteries and secondary batteries. Primary batteries are disposable, consumable batteries. Secondary batteries, on the other hand, are rechargeable batteries made using materials in which oxidation and reduction processes between current and materials are repeatable. That is, the power source is charged when a reduction reaction is performed on the material by an electric current, and discharged when an oxidation reaction is performed on the material by an electric current. This charge-discharge cycle is repeated to generate electricity.

[0005] Secondary batteries can be classified into cylindrical batteries, pouch batteries, and prismatic batteries based on their shape. Among them, pouch batteries are manufactured by accommodating electrode assemblies, which are stacked in the form of positive electrodes, negative electrodes, and separators, inside a pouch-shaped component and then sealing the outer part of the pouch-shaped component.

[0006] Secondary batteries can be classified into cylindrical batteries, pouch batteries, and prismatic batteries based on their shape. Among them, pouch batteries are manufactured by housing an electrode assembly in the form of a stack of positive electrodes, negative electrodes, separators, etc., inside a pouch-shaped component and then sealing the outer part of the pouch-shaped component.

[0007] According to existing technology, pouch-type batteries may have limitations in the molding process of the pouch film, which can lead to cracks, and the film may be discarded after the degassing process. Furthermore, the molding depth is limited due to the material properties of the pouch film, thus limiting the increase in battery capacity. Additionally, since existing pouch-type batteries are constructed by cup-molding the upper and lower boxes with a pouch film and sealing the external parts of the two boxes together, there are limitations in controlling or predicting the direction of battery venting in the event of increased internal pressure or explosion due to abnormal battery behavior.

[0008] Therefore, there is a need for a secondary battery whose shape can increase battery capacity while having relatively few restrictions on shape, and in addition, there is a need for a secondary battery that can control the direction of gas discharge when gas ejection and flame generation occur inside the battery. Summary of the Invention

[0009] Technical issues

[0010] The object of the present invention is to provide a secondary battery that has improved capacity while having relatively few shape constraints, reduced water permeation from the outside, and improved structural stability.

[0011] The purpose of this invention is to provide a secondary battery that has improved reliability due to its excellent sealing strength and can withstand high levels of internal pressure caused by gas generated inside the secondary battery.

[0012] The purpose of this invention is to provide a secondary battery that improves safety by controlling the direction of gas or flame ejection generated inside the secondary battery.

[0013] Technical solution

[0014] [1] According to one aspect of the present invention, a secondary battery is provided, comprising: an electrode assembly extending in one direction; an outer membrane surrounding a portion of the electrode assembly; and a cover covering the remainder of the electrode assembly, wherein the cover comprises: a covering portion covering a side portion of the electrode assembly in the extending direction; a connecting portion including a connecting portion disposed on an outer surface of the covering portion and connected to the outer membrane; and a terminal portion at least a portion exposed outside the covering portion and electrically connected to the electrode assembly, wherein the connecting portion of the connecting portion includes a first layer comprising a first resin and having an outer surface allowing connection to an inner surface of the outer membrane and an inner surface allowing connection to an outer surface of the covering portion.

[0015] [2] In paragraph [1], the first resin may include resins selected from the group consisting of: melting point (T) m The resin has a melting point of 135°C to 150°C, a melt flow rate (MFR) of 4 g / 10 min to 10 g / 10 min at 230°C, and a melting point (T). m The resin is a resin with a melt flow rate (MFR) of 4 g / 10 min to 10 g / 10 min at 135°C to 150°C and at 230°C.

[0016] [3] In paragraphs [1] and / or [2], the first resin may include a modified polyolefin-based resin.

[0017] [4] In at least one of paragraphs [1] to [3], the connecting portion of the connector may include: a first layer comprising a first resin and allowing connection to the outer surface of the cover; and a second layer comprising a second resin, stacked on the outer surface of the first layer and allowing connection to the inner surface of the outer membrane.

[0018] [5] In paragraph [4], the first resin may include resins selected from the group consisting of: melting point (T) m The resin has a melting point of 135°C to 150°C, a melt flow rate (MFR) of 4 g / 10 min to 10 g / 10 min at 230°C, and a melting point (T). m The first layer is a resin with a melting point of 135°C to 150°C and a melt flow rate (MFR) of 4 g / 10 min to 10 g / 10 min at 230°C, and the second layer may include a resin selected from the group consisting of: a resin with a melting point of 120°C to 145°C, a resin with a melt flow rate (MFR) of 5 g / 10 min to 18 g / 10 min at 230°C, and a resin with a melting point (T... m The resin is a resin with a melt flow rate (MFR) of 5 g / 10 min to 18 g / 10 min at 120°C to 145°C and at 230°C.

[0019] [6] In paragraphs [4] and / or [5], the first resin and the second resin satisfy at least one of the following equations 1 and 2:

[0020] [Equation 1]

[0021] T m2 > T m1

[0022] In Equation 1 above, T m1 It is the melting point of the first resin in °C, and T m2 It is the melting point of the second resin in °C.

[0023] [Equation 2]

[0024] MFR2>MFR1

[0025] In Equation 2 above, MFR1 is the melt flow rate of the first resin in g / 10 min, and MFR2 is the melt flow rate of the second resin in g / 10 min.

[0026] [7] In at least one of paragraphs [4] to [6], the first resin may include a modified polyolefin-based resin and the second resin may include an unstretched polypropylene-based resin.

[0027] [8] In at least one of paragraphs [1] to [7], the connecting portion of the connector may include: a first layer comprising a first resin and allowing connection to the outer surface of the cover; a second layer comprising a second resin and allowing connection to the inner surface of the outer membrane; and a third layer comprising a third resin and disposed between the first layer and the second layer.

[0028] [9] In paragraph [8], the first resin may include resins selected from the group consisting of: melting point (T) m The resin has a melting point of 135°C to 150°C, a melt flow rate (MFR) of 4 g / 10 min to 10 g / 10 min at 230°C, and a melting point (T). m The first resin has a melting point of 135°C to 150°C and a melt flow rate (MFR) of 4 g / 10 min to 10 g / 10 min at 230°C. The second resin includes resins selected from the group consisting of: resins with a melting point of 120°C to 145°C, resins with a melt flow rate (MFR) of 5 g / 10 min to 18 g / 10 min at 230°C, and resins with a melting point (T... m The third resin comprises a resin having a melting point of 120°C to 145°C and a melt flow rate (MFR) of 5 g / 10 min to 18 g / 10 min at 230°C, and the third resin comprises a resin selected from the group consisting of: a resin having a melting point of 145°C to 170°C, a resin having a melt flow rate (MFR) of 2 g / 10 min to 4 g / 10 min at 230°C, and a resin having a melting point (T... m The resin is a resin with a melt flow rate (MFR) of 2 g / 10 min to 4 g / 10 min at 145°C to 170°C and at 230°C.

[0029]

[10] In paragraphs [8] and / or [9], the first resin, the second resin, and the third resin satisfy at least one of the following equations 3 and 4:

[0030] [Equation 3]

[0031] T m3 > T m2 > T m1

[0032] In equation 3 above, T m1 It is the melting point of the first resin in °C, Tm2 It is the melting point of the second resin in °C, and T m3 It is the melting point of the third resin in °C.

[0033] [Equation 4]

[0034] MFR2 > MFR1 > MFR3

[0035] In Equation 4 above, MFR1 is the melt flow rate of the first resin in g / 10 min, MFR2 is the melt flow rate of the second resin in g / 10 min, and MFR3 is the melt flow rate of the third resin in g / 10 min.

[0036]

[11] In at least one of paragraphs [8] to

[10] , the first resin may include a modified polyolefin-based resin, the second resin may include an unstretched polypropylene-based resin, and the third resin may include a homopolymer-olefin-based resin.

[0037]

[12] In at least one of paragraphs [1] to

[11] , the connecting portion may include a connecting portion disposed on the surface of the cover portion, wherein the connecting portion may also be disposed on at least one surface of the cover portion other than the outer surface of the cover portion on which the connecting portion is disposed.

[0038]

[13] In paragraph

[12] , the connecting portion of the connector may include a first layer comprising a first resin and having an inner surface that allows engagement with the surface of the cover.

[0039]

[14] In paragraphs

[12] and / or

[13] , the connecting portion of the connector may include: a first layer comprising a first resin and allowing connection to the surface of the cover; and a second layer comprising a second resin and stacked on the outer surface of the first layer.

[0040]

[15] In at least one of paragraphs

[12] to

[14] , the connecting portion of the connector may include: a first layer comprising a first resin and allowing connection to the surface of the cover; a second layer comprising a second resin and disposed on the outermost side; and a third layer comprising a third resin and disposed between the first layer and the second layer.

[0041]

[16] In at least one of paragraphs [1] to

[15] , the outer peripheral surface of the cover may extend along the circumferential direction of the electrode assembly, and the connecting portion may be disposed on the outer peripheral surface of the cover.

[0042]

[17] In at least one of paragraphs [1] to

[16] , the cover may include: a cover portion having an outward surface facing the outside of the electrode assembly; and an extension portion extending from the cover portion toward the electrode assembly, wherein a connecting portion may be disposed on the outer surface of the extension portion.

[0043]

[18] In paragraph

[17] , the covering portion may have a plate shape and the extension portion may extend from the edge of the covering portion.

[0044]

[19] In at least one of paragraphs [1] to

[18] , the outer membrane may have a predetermined flexibility to be able to bend.

[0045]

[20] According to another aspect of the invention, a method for manufacturing a secondary battery includes: providing an electrode assembly including a positive electrode and a negative electrode and extending in one direction; surrounding a portion of the electrode assembly with an outer membrane; and covering the remainder of the electrode assembly with a cover, wherein the cover includes: a cover portion configured to cover a side portion of the electrode assembly in the direction of extension; a connection portion including a coupling portion disposed on an outer surface of the cover portion and coupled to the outer membrane; and a terminal portion, at least a portion of the terminal portion being exposed outside the cover portion and electrically connected to the electrode assembly, wherein the coupling portion of the connection portion includes a first layer comprising a first resin and having an outer surface that allows coupling with an inner surface of the outer membrane and an inner surface that allows coupling with an outer surface of the cover portion.

[0046]

[21] According to another aspect of the invention, a battery pack includes: a secondary battery; and a package that houses the secondary battery, wherein the secondary battery includes: an electrode assembly extending in one direction; an outer film surrounding a portion of the electrode assembly; and a cover covering the remainder of the electrode assembly, wherein the cover includes a cover portion, a connecting portion, and a terminal portion, the cover portion covering a side portion of the electrode assembly in the extending direction, the connecting portion including a connecting portion disposed on an outer surface of the cover portion and connected to the outer film, at least a portion of the terminal portion being exposed to the outside of the cover portion and electrically connected to the electrode assembly, wherein the connecting portion of the connecting portion includes a first layer comprising a first resin and having an outer surface that allows connection to an inner surface of the outer film and an inner surface that allows connection to an outer surface of the cover portion.

[0047] Beneficial effects

[0048] In the secondary battery according to an example of the invention, since there is no process for molding an outer membrane, the limitations on the form in which the outer membrane houses the electrode assembly can be small, and the possibility of defects such as cracks in the outer membrane can be reduced to improve battery capacity.

[0049] In addition, it can reduce the degree of moisture penetration from the outside of the secondary battery into the secondary battery, thereby improving the safety of the secondary battery.

[0050] In addition, due to its excellent sealing strength, it can withstand high levels of internal pressure caused by gas generated inside the secondary battery, thereby improving the durability of the secondary battery.

[0051] In addition, the terminal section and busbar can be electrically connected to the electrode assembly in various forms.

[0052] Furthermore, the connection relationship and arrangement of the connecting part and the cover part can improve the structural stability of the secondary battery, and thereby control the problem of venting to the cover part in the event of explosive increase in internal pressure or flame ejection.

[0053] In addition, the secondary battery can be effectively electrically connected to the outside through the terminal portion passing through the connector.

[0054] In addition, the outer part of the connecting part can protect the covered part of the covering part from external pollution or impact.

[0055] In addition, the external part and the connecting part can be connected to improve the connection between the connecting part and the cover.

[0056] In addition, since the cover is covered by the external part, the insulation between the cover and other components can be improved, and heat transfer can be suppressed in the event of thermal runaway.

[0057] In addition, since the cover is completely surrounded by the connecting part, the cap can be easily manufactured by inserting an injection process.

[0058] The effects of the present invention are not limited to those described above, and therefore, this specification relates to many more variations of the effects. Attached Figure Description

[0059] Figure 1 This is a three-dimensional plan view of a battery pack according to an example of the present invention. Here, the package is indicated by dashed lines, and the configuration seen through the package is indicated by solid lines.

[0060] Figure 2 This is a three-dimensional plan view of a secondary battery according to a first example of the present invention.

[0061] Figure 3 yes Figure 2 An exploded 3D view of a secondary battery.

[0062] Figure 4 It is illustrated in the diagram. Figure 3 An exploded perspective view showing the connection and covering parts of the structure being connected to each other.

[0063] Figure 5 It is along Figure 2 A partial cross-sectional view taken from line A-A'.

[0064] Figure 6 It is along Figure 2 A partial cross-sectional view taken from line B-B'.

[0065] Figure 7 This is a three-dimensional plan view of a secondary battery according to a second example of the present invention.

[0066] Figure 8 yes Figure 7 An exploded 3D view of a secondary battery.

[0067] Figure 9 It is along Figure 7 A partial cross-sectional view taken from line C-C'.

[0068] Figure 10 It is along Figure 7 A partial cross-sectional view of the secondary battery according to the third example of the present invention, taken by line C-C'.

[0069] Figure 11 It is along Figure 7 A partial cross-sectional view of a secondary battery (a first modified example of the connecting portion) according to the fourth example of the present invention, taken by line C-C'.

[0070] Figure 12 It is along Figure 7 A partial cross-sectional view of a secondary battery (a second modified example of the connecting portion) according to the fourth example of the present invention, taken by line C-C'.

[0071] Figure 13 It is along Figure 7 A partial cross-sectional view of a secondary battery (a third modified example of the connecting portion) according to the fourth example of the present invention, taken by line C-C'. Detailed Implementation

[0072] In the following description, preferred embodiments of the invention will be given with reference to the accompanying drawings, enabling those skilled in the art to readily implement the invention. However, the invention may be implemented in several different forms and is not limited to or construed as described below.

[0073] To clearly explain the invention, detailed descriptions of irrelevant parts or related known technologies that may unnecessarily obscure the spirit of the invention have been omitted, and reference numerals have been added to components in each figure. In this case, the same or similar reference numerals are assigned to the same or similar elements throughout the specification.

[0074] Furthermore, the terms or words used in this specification and claims should not be construed as having a general meaning or a dictionary-based meaning, but should be interpreted as meanings and concepts that are within the scope of the invention, based on the principle that the inventor can appropriately define the concepts of the terms in order to best describe and explain his or her invention.

[0075] Figure 1 This is a three-dimensional plan view of a battery pack according to an example of the present invention. Here, the package is indicated by dashed lines, and the configuration seen through the package is indicated by solid lines.

[0076] exist Figure 1 The present invention discloses an example of a battery pack. (See also...) Figure 1 According to an example of the present invention, the battery pack 1 can be a battery pack for charging and releasing electrical energy.

[0077] The battery pack 1 according to an example of the present invention may include secondary batteries 3. Here, there may be multiple secondary batteries 3. The battery pack 1 may include a package 2 therein for housing multiple secondary batteries 3. The package 2 may be configured to protect the secondary batteries 3 from external impacts or contamination.

[0078] In this example, package 2 can be configured as a box-shaped structure. Package 2 can be made of metal or plastic with a certain degree of rigidity. Package 2 can have a structure in which multiple plates are connected.

[0079] However, the shape or structure of the package 2 can be modified as needed. For example, at least a portion of the package 2 can have a curved shape. In addition, the package 2 may also include other components. For example, the package 2 may be provided with busbars electrically connected to a plurality of secondary batteries 3 and / or venting components connecting the interior and exterior of the package 2 to each other.

[0080] Hereinafter, an example of a secondary battery according to the present invention is described.

[0081] Example 1

[0082] Figure 2 This is a three-dimensional plan view of a secondary battery according to a first example of the present invention. Figure 3 yes Figure 2 An exploded 3D view of a secondary battery. Figure 4 It is illustrated in the diagram. Figure 3 An exploded perspective view showing the connection and covering parts of the structure being connected to each other. Figure 5 It is along Figure 2 A partial cross-sectional view taken from line A-A'. Figure 6 It is along Figure 2A partial cross-sectional view taken from line B-B'.

[0083] Reference Figures 2 to 6 The secondary battery 3 according to Example 1 of the present invention may include an electrode assembly 10, an outer membrane 20, and a cover 30. Each configuration of the secondary battery 3 will be described in more detail below. For reference, the content of Example 1 can also be applied to other examples described later, unless otherwise specified.

[0084] Electrode assembly

[0085] The electrode assembly 10 of the secondary battery 3 may include a positive electrode, a negative electrode, and a separator. Here, the separator may be disposed between the positive and negative electrodes to physically separate them. The electrode assembly 10 may be configured such that the positive electrode, negative electrode, and separator are stacked, or configured such that the positive electrode, negative electrode, and separator are wound. There are no particular limitations on the type or structure of the electrode assembly 10. The electrode assembly 10 may extend in one direction (X-axis direction) and have a predetermined length.

[0086] The electrode assembly 10 may include electrode contacts 11 connected to the electrodes. The electrode contacts 11 may be provided separately or may be incorporated into a current collector constituting the electrodes. For reference, if the electrode assembly 10 is an all-solid-state battery, a solid electrolyte may be provided instead of a separator.

[0087] external membrane

[0088] Reference Figures 1 to 6 The secondary battery 3 according to a first example of the present invention may include an outer membrane 20. The outer membrane 20 of the secondary battery 3 may be configured to surround a portion of the electrode assembly 10. Specifically, the outer membrane 20 may be configured to surround the electrode assembly 10 and a cover 30, which will be described later. More specifically, the outer membrane 20 may be coupled to the cover 30 to define an internal space, and the electrode assembly 10 may be accommodated within the internal space.

[0089] As illustrated, in this example, the outer membrane 20 may surround the electrode assembly 10 in a circumferential direction. Here, the circumferential direction may be a direction about an axis (X-axis) parallel to the extension direction of the electrode assembly 10. The outer membrane 20 may be made of a material that can deform into a shape that can surround the electrode assembly 10. For example, the outer membrane 20 may have a predetermined flexibility such that it can be bent by an external force.

[0090] Additionally, the outer membrane 20 can be made of a non-elastic material. In related technologies, the bag membrane is molded to define a space in which the electrode assembly is housed. However, since the outer membrane 20 does not need to be molded to deform its shape, it can be made of a non-elastic material. That is, the outer membrane 20 may not be elastic. Alternatively, the outer membrane 20 may have a certain degree of elasticity as needed.

[0091] The outer membrane 20 of the secondary battery 3 may have a shape in which a sheet or membrane is wound along the side surface of the electrode assembly 10. That is, the outer membrane 20 may be configured to surround the side portion of the electrode assembly 10. Here, one end and the other end of the outer membrane 20 may be configured to be in contact with each other and surround the electrode assembly 10. Regarding the shape in which one end and the other end of the outer membrane 20 are in contact with each other, one surface of one end and the other surface of the other end may be joined together to contact each other (see...). Figure 2 This is just an example, and the form in which one end of the outer membrane 20 is joined to define the space for accommodating the electrode assembly 10 can be varied.

[0092] Regarding the method of connecting one end and the other end of the outer membrane 20 to each other, one end and the other end of the outer membrane 20 can be connected to each other by sealing by heating or by sealing by heating and pressure. That is, the outer membrane 20 may include a material that has sealing properties by heating.

[0093] As an example of the structure of the outer membrane 20, the outer membrane 20 can be provided in the form of a membrane. Specifically, the outer membrane 20 can be configured as multiple layers including a sealant layer, a barrier layer, and an insulating layer. More specifically, the outer membrane 20 can be disposed from the interior near the electrode assembly 10 in the order of sealant layer, barrier layer, and insulating layer.

[0094] The sealant layer may comprise a material with sealing properties that, when heated, bonds one end of the outer membrane 20 to the other. For example, the sealant layer of the outer membrane 20 may comprise at least one or more materials selected from the group consisting of: polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylate polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, poly(p-benzodioxazole), polyarylate, polytetrafluoroethylene, and glass fiber. Polyolefin-based resins such as polypropylene (PP) or polyethylene (PE) can be primarily used. In particular, polypropylene (PP) can be excellent in mechanical properties, such as tensile strength, rigidity, surface hardness, abrasion resistance, and heat resistance, as well as chemical properties, such as corrosion resistance.

[0095] The barrier layer may include a metal. For example, the metal of the barrier layer may be made of one or more materials selected from the group consisting of Fe, C, Cr, Mn, Ni, and Al. For example, the barrier layer may include stainless steel (STS). Alternatively, the barrier layer may be made of an alloy such as an aluminum alloy.

[0096] The insulating layer may include an insulating material. That is, the electrode assembly 10 can be insulated from the outside through the insulating layer. Therefore, the insulating layer can prevent short circuits in the outer membrane 20. For example, the insulating layer may include at least one or more materials selected from the group consisting of: polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylate polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, poly(p-benzodioxazole), polyarylate, polytetrafluoroethylene, and glass fiber. Polymers with abrasion resistance and heat resistance, such as nylon resin or polyethylene terephthalate (PET), can be primarily used.

[0097] The outer membrane 20 may be configured to surround a portion of the electrode assembly 10, and the cover 30 may be configured to surround the remainder of the electrode assembly 10. Specifically, when the outer membrane 20 is configured to surround the electrode assembly 10 along its side surface (outer peripheral surface), an opening may be defined at each of the two ends of the electrode assembly 10, the opening being defined as an edge of the outer membrane 20. Here, the opening may be located at each of the two sides of the electrode assembly 10 in its extending direction (X-axis direction).

[0098] The cover 30 of the secondary battery 3 can be connected to the outer membrane 20 in the form of openings covering the two sides of the electrode assembly 10. In addition, the electrode assembly 10 can be housed in the internal space defined by the outer membrane 20 and the cover 30.

[0099] The outer membrane 20 can be attached to the cover 30. As an example of a method of attaching the cover 30 to the outer membrane 20, the cover 30 and the outer membrane 20 can be attached to each other by welding. Specifically, the connection portion 40, described later, can include a metallic material, and the outer membrane 20 can include a metal layer that can be attached to the connection portion 40 by welding at the portion facing the connection portion 40.

[0100] As another example of a method for attaching the cover 30 to the outer membrane 20, the cover 30 and the outer membrane 20 can be joined together by a seal. Specifically, the connecting portion 40 may include a resin material that has adhesive properties when heated, and the outer membrane 20 may include a resin layer that can be joined to the connecting portion 40 by heating and pressure at the portion facing the connecting portion 40. Here, the resin layer may include a material that has sealing properties when heated, as described above.

[0101] In existing pouch cells, the cup-shaped portion housing the electrode assembly 10 can be molded from a sheet or film. During the molding process of the cup-shaped portion, the depth that can be molded may be limited depending on the material properties of the sheet or film, and the capacity of housing the electrode assembly 10 may also be limited. Furthermore, when molding the sheet or film, the thickness is thinnest at the corners, which typically leads to defects such as cracks. Additionally, existing pouch cells may require a gas collection section to collect gas during the degassing process to remove gas accumulated inside the pouch, and most of the gas collection section can be removed and discarded after the degassing process.

[0102] On the other hand, in the secondary battery 3 according to the first example of the present invention, the outer membrane 20 can be used to match the volume of the electrode assembly 10, and therefore, there is no limitation on the capacity of accommodating the electrode assembly 10. Furthermore, since it is not necessary to mold the cup-shaped portion, defects such as cracks in the outer membrane 20 can be prevented, and the material and thickness of the outer membrane 20 can be chosen relatively freely. Additionally, since the electrolyte injection and degassing processes are performed through the cap 30, the economic efficiency of the process can be improved because no discarded outer membrane 20 is produced.

[0103] build

[0104] Reference Figure 2 and Figure 6 According to a first example of the present invention, the cover 30 of the secondary battery 3 may include a connecting portion 40, a covering portion 50, and a terminal portion 60. In this example, the cover 30 may seal the electrode assembly 10 together with the outer membrane 20. Therefore, the discharge of gas or flame due to abnormal internal behavior may be directed (or concentrated) towards the outer membrane 20, and thus, the stability of the secondary battery 3 can be improved.

[0105] The connecting portion 40 of the cover 30 can be connected to the outer membrane 20. Additionally, the covering portion 50 of the cover 30 can be connected to the connecting portion 40 and can be partially exposed to the outside of the connecting portion 40. Specifically, one surface of the covering portion 50 can be exposed to the outside of the connecting portion 40.

[0106] Here, the interior of the connecting portion 40 may refer to a portion of the interior space defined by the cover 30 and the outer membrane 20, and the exterior of the connecting portion 40 may refer to the exterior space of the cover 30 and the outer membrane 20.

[0107] Additionally, one surface of the cover 50 exposed to the outside of the connection portion 40 may be an outward-facing surface 51a. The outward-facing surface 51a may be provided on the cover portion 51 of the cover 50, which will be described later. The surface facing the outward-facing surface 51a of the cover portion 51 may be referred to as an inward-facing surface 51b. The inward-facing surface 51b may be a surface facing the electrode assembly 10.

[0108] Reference Figures 2 to 6 In this example, the connecting portion 40 may include a connecting portion 41. The connecting portion 41 may be the portion that directly connects the cover portion 50 to the outer membrane 20, which will be described later. As needed, the connecting portion 41 may be configured as multiple layers, including a single layer containing one material, a single layer containing different materials from each other, multiple layers each containing different materials from each other, or multiple layers each containing different materials.

[0109] In this example, the connecting portion 41 may be disposed on the outer surface 54a of the extension portion 54 in the cover portion 50. Here, the outer surface 54a of the extension portion 54 may be an outward-facing surface (or an outer peripheral surface). The connecting portion 41 may be disposed between the extension portion 54 and the outer membrane 20 to connect the extension portion 54 to the outer membrane 20.

[0110] In this example, the connecting portion 41 may be disposed along the outer surface 54a (or outer peripheral surface) of the extension portion 54. As will be described in detail later, in this example, since the extension portion 54 has an annular shape, the connecting portion 41 may also have an annular shape corresponding to the extension portion 54. Here, the annular shape may be the shape viewed along the longitudinal direction (X-axis direction) of the electrode assembly 10. The shape of the connecting portion 41 may be appropriately modified according to the structure of the cover portion 50.

[0111] Additionally, in this example, the connecting portion 40 may include an inner portion 43. The inner portion 43 may be disposed on the inner surface 51b of the covering portion 51. The inner portion 43 may cover the entire inner surface 51b. The inner portion 43 may have a plate shape with a predetermined thickness. Therefore, heat transfer or moisture penetration through the covering portion 51 can be effectively suppressed. A terminal hole 43a may be disposed in the inner portion 43. The terminal hole 43a may be a hole through which the terminal portion 60, described later, passes.

[0112] In this example, the connecting portion 40 may include an extension side portion 44. The extension side portion 44 may be disposed on the inner surface 54b (or inner peripheral surface) of the extension portion 54 in the cover portion 50, which will be described later. Here, the inner surface 54b of the extension portion 54 may be a surface facing the outer surface 54a. The inner surface 54b may be an inward-facing surface.

[0113] In this example, the extension side portion 44 can be provided along the inner surface 54b (or inner peripheral surface) of the extension portion 54. Here, since the extension portion 54 has an annular shape, the extension side portion 44 can also have an annular shape corresponding to the extension portion 54. Here, the annular shape can be the shape viewed along the longitudinal direction (X-axis direction) of the electrode assembly 10. The shape of the extension portion 44 can be appropriately modified according to the structure of the cover portion 50.

[0114] Here, the extension side portion 44 and the inner portion 43 can be connected to each other. In other words, the extension side portion 44 can extend from the inner portion 43. The extension side portion 44 can extend from the edge portion of the inner portion 43. Therefore, the connection portion 40 can improve the rigidity enhancement, water penetration prevention, and heat transfer inhibition effect of the cover 30.

[0115] As an example of a configuration for external electrical connection, the cover 30 of the secondary battery 3 according to a first example of the invention may include a terminal portion 60. The terminal portion 60 may pass through the connecting portion 40 and the covering portion 50, and be exposed both outside and inside the connecting portion 40. The portion of the terminal portion 60 exposed inside the connecting portion 40 may be electrically connected to the electrode assembly 10. Here, the electrical connection may include a direct connection between the terminal portion 60 and the electrode assembly 10, and an indirect connection via another conductive member. The portion of the terminal portion 60 exposed outside the connecting portion 40 may be electrically connected to the outside.

[0116] For the electrical connection between the electrode assembly 10 and the outside, the terminal portion 60 may include a conductive material. The terminal portion 60 may be configured to protrude outward from the connection portion 40 (see [link]). Figure 2 Therefore, the secondary battery 3 can be electrically connected to the outside in many different forms and can effectively provide electrical energy to the outside.

[0117] The configuration of the terminal portion 60 will be described in more detail below. According to the first example of the invention, the terminal portion 60 of the cover 30 can extend from the interior to the exterior of the connecting portion 40. Here, the terminal portion 60 can be configured to have a constant cross-sectional area in the longitudinal direction. For example, the terminal portion 60 can have a cylindrical or cuboid shape. Here, a cuboid-shaped terminal portion 60 will be described as an example. A terminal portion 60 having a constant cross-sectional area in the longitudinal direction can be manufactured relatively easily.

[0118] The electrode assembly 10 may include parallel-stacked electrodes and spacers. Here, the terminal portion 60 may have one surface and another surface disposed at two ends of a portion exposed inside the connection portion 40, said one surface and said other surface being flat based on the stacking direction of the electrodes and spacers. (Refer to...) Figure 4One surface and the other surface located at the two ends of the terminal portion 60 can be surfaces that contact the electrode contacts 11 of the electrode assembly 10. With this shape, the terminal portion 60 can be connected to the electrode contacts 11 more effectively.

[0119] Furthermore, when the secondary battery 3 includes multiple electrode assemblies 10, the electrode contacts 11 of the multiple electrode assemblies 10 can be electrically connected to one side and the other side of the terminal portion 60, respectively. Therefore, the secondary battery 3 can be effectively improved in terms of battery capacity.

[0120] In addition to the shape described in the first example of the invention, the terminal portion 60 may also have various shapes for effective electrical connection. Although not specifically shown in the drawings, a predetermined gasket may be provided on the outer peripheral portion of the terminal portion 60. The gasket may be configured to prevent electrolyte leakage. The gasket may be placed between the outer peripheral portion of the terminal portion 60 and the cover portion 50. The gasket may be made of a polymer material, such as plastic or rubber.

[0121] The structure of the cover 50 will be described in more detail below.

[0122] As an example of a configuration that improves the structural stability of the cover 30, at least a portion of the covering portion 50 of the cover 30 according to the first example of the invention can be embedded in the connecting portion 40. In this respect, the covering portion 50 of the cover 30 may include a covering portion 51 and an extension portion 54.

[0123] The covering portion 51 of the covering portion 50 can be disposed on one side of the electrode assembly 10 in the longitudinal direction (X-axis direction). The covering portion 51 can cover one side of the electrode assembly 10. The covering portion 51 can have a square plate shape, but the shape of the covering portion 51 is not particularly limited, as long as it partially covers the electrode assembly 10.

[0124] The outward surface 51a of the cover portion 51 may be configured to expose the exterior of the connector 40. Here, the outward surface 51a may be the outer surface of the cover portion 51 facing the exterior of the electrode assembly 10. Here, the outward surface 51a of the cover portion 51 may be located on the same surface as one surface of the connector 40. More specifically, the outward surface 51a may be located on the same surface as one surface of the connecting portion 41 of the connector 40, which will be described later. Alternatively, the outward surface 51a may be configured to extend further outward than one surface of the connecting portion 41.

[0125] This configuration improves space utilization when arranging multiple secondary batteries 3. Here, based on... Figure 6The outward surface 51a can refer to the surface facing forward (positive direction of the X-axis) from the covering portion 51, and a surface of the connecting portion 41 can refer to the end surface facing forward (positive direction of the X-axis).

[0126] The extension portion 54 of the cover portion 50 can extend toward the electrode assembly 10. That is, the extension portion 54 can extend from the cover portion 51 toward the electrode assembly 10. Specifically, the extension portion 54 can be configured such that the end surface 54c located on one side of the electrode assembly 10 is exposed to the interior of the connecting portion 40. Here, the extension portion 54 can extend from the edge of the cover portion 51.

[0127] Reference Figure 5 and Figure 6 The extension portion 54 of the cover portion 50 may be provided in multiple ways. Here, at least one extension portion 54 may be configured such that the end surface 54c located on one side of the electrode assembly 10 is exposed to the interior of the connecting portion 40. Specifically, among the multiple extension portions 54 extending from the cover portion 51 toward the electrode assembly 10, a portion of the extension portion may be embedded in the connecting portion 40, and another portion may be exposed to the interior of the connecting portion 40.

[0128] However, in the first example of the present invention, an example is given in which all of the plurality of extension portions 54 are exposed inside the connecting portion 40. Specifically, the plurality of extension portions 54 may include a first extension portion 55 to a fourth extension portion 58.

[0129] Reference Figure 5 and Figure 6 The first extension portion 55 and the second extension portion 56 can extend parallel to each other from two sides of the cover portion 51 in the width direction (Y-axis direction). The first extension portion 55 and the second extension portion 56 can be set at a predetermined distance in the width direction. Here, the width direction (Y-axis direction) can be a direction perpendicular to the direction of electrode and separator stacking (Z-axis direction). Each of the first extension portion 55 and the second extension portion 56 can have a separator wall (or plate) shape with a predetermined thickness.

[0130] The third extension portion 57 and the fourth extension portion 58 can extend parallel to each other from two sides of the cover portion 51 in the height direction (Z-axis direction). The third extension portion 57 and the fourth extension portion 58 can be set at a predetermined distance in the height direction. Here, the height direction (Z-axis direction) can be parallel to the direction of the electrode and separator stack (Z-axis direction). Each of the third extension portion 57 and the fourth extension portion 58 can have a separator wall (or plate) shape with a predetermined thickness.

[0131] Here, the first extension portion 55 to the fourth extension portion 58 can be connected to each other. Therefore, when viewed along the longitudinal direction (X-axis direction) of the electrode assembly 10, the first extension portion 55 to the fourth extension portion 58 can have an overall annular shape. In other words, each of the first extension portion 55 to the fourth extension portion 58 can have an annular shape along the circumferential direction of the electrode assembly 10. Here, the annular shape can be the shape viewed along the longitudinal direction (X-axis direction) of the electrode assembly 10.

[0132] Reference Figure 5 The end surface 54c of the extension portion 54 exposed inside the connecting portion 40 can be positioned at a predetermined distance from the electrode assembly 10. Therefore, damage to the electrode assembly 10 by the extension portion 54 can be prevented.

[0133] In this example, the extension 54 has been described as being composed of the first extension 55 to the fourth extension 58. However, if desired, the extension 54 may be configured to include only some of the extensions from the first extension 55 to the fourth extension 58. For example, the extension 54 may be composed of the first extension 55 and the second extension 56, and configured to be open in the height direction (Z-axis direction).

[0134] Reference Figures 2 to 6 The extension 54 can be embedded in the connecting portion 40 in the form of fitting into a recess defined in the connecting portion 40. Some of the covering portions 51 and the extension portions 54 can be fitted into the connecting portion 40, and thus the connecting portion 40 and the covering portion 50 can be connected to each other (see See). Figures 2 to 6 Here, the connecting portion 40 and the extension portion 54 can be adhered to each other by heat sealing. Alternatively, the connecting portion 40 and the extension portion 54 can be adhered to each other by an adhesive applied between the connecting portion 40 and the extension portion 54. Here, the type and application form of the adhesive used for adhesion between the connecting portion 40 and the extension portion 54 can vary. The adhesive can be made of a material with relatively high hydrophobicity.

[0135] When the connecting portion 40 and the extension portion 54 are joined together by a seal, the connecting portion 40 may include a resin material that has adhesive properties due to heat. That is, the resin material of the connecting portion 40 with adhesive properties can be melted by heat, and the connecting portion 40 can be adhered to the extension portion 54 by pressure. In this way, the connecting portion 40 and the covering portion 50 can be joined together.

[0136] Although not described in detail in this invention, the cover 30 may also include an electrolyte injection port for injecting electrolyte or a gas discharge port for discharging gas during the degassing process.

[0137] In the cover 30 of the secondary battery 3 according to a first example of the present invention, the connecting portion 40 and the covering portion 50, at least a portion of which is embedded in the connecting portion 40, can cover the electrode assembly 10. Depending on the material of the connecting portion 40, moisture outside the connecting portion 40 can penetrate into the connecting portion 40. Moisture penetration may lead to defects in the secondary battery 3.

[0138] In the cover 30 of the secondary battery 3 according to the first example of the present invention, a cover portion 50 comprising a material with excellent water resistance, such as metal, can cover the electrode assembly 10 together with the connecting portion 40. Therefore, the area through which moisture permeates in the connecting portion 40 of the cover 30 can be reduced. Furthermore, since at least a portion of the cover portion 50 is configured to be embedded in the connecting portion 40, moisture may have difficulty permeating between the cover portion 50 and the connecting portion 40. Therefore, the secondary battery 3 according to the first example of the present invention can reduce the amount of moisture permeating into the secondary battery, thereby reducing performance limitations of the secondary battery 3.

[0139] Furthermore, the cover 30 of the secondary battery 3 according to the first example of the present invention can be configured such that the extension portion 54 of the cover portion 50 is embedded in the connecting portion 40. Therefore, since the connecting portion 40 restricts the movement of the cover portion 50 to prevent the cover portion 50 from separating, the structural stability of the secondary battery 3 can be improved.

[0140] Furthermore, since the cover 30 of the secondary battery 3 includes a terminal portion 60, the cover 30 can be effectively electrically connected to the outside. In addition, the terminal portion 60 can be connected to various types of electrode assemblies 10 by changing its shape and arrangement, and can be effectively connected to the electrode contacts 11 even when the number of electrode contacts 11 increases.

[0141] Although not described in detail in the first example of the invention, the cover 30 may also include a gas venting member (not shown) for venting gas inside the secondary battery 3 or an exhaust member (not shown) for causing exhaust in a particular direction.

[0142] Example 2

[0143] Figure 7 This is a three-dimensional plan view of a secondary battery according to a second example of the present invention. Figure 8 yes Figure 7 An exploded 3D view of a secondary battery. Figure 9 It is along Figure 7 A partial cross-sectional view taken from the midline C-C'.

[0144] The secondary battery 3 according to the first example of the present invention will be omitted below (e.g. Figure 2 A detailed description of the configuration identical to that shown in the example, and a specific description of the differences between the first and second examples.

[0145] Reference Figures 7 to 9 The secondary battery 103 according to the second example of the present invention may differ from the secondary battery 3 according to the first example in terms of the shape of the connecting portion 140, the shape of the terminal portion 160, the presence or absence of the busbar 170, the connection method of the configuration, etc. Figure 2 (As shown) The secondary battery 103 according to the second example of the present invention may include an electrode assembly 10, an outer membrane 20, and a cover 130.

[0146] Here, the outer membrane 20 of the secondary battery 103 can have the shape of a sheet or film rolled up along the side surface of the electrode assembly 10. That is, the outer membrane 20 can be arranged to surround the side of the electrode assembly 10. Here, one end and the other end of the outer membrane 20 can be arranged to be connected to each other and surround the electrode assembly 10. Regarding the form in which one end and the other end of the outer membrane 20 are connected to each other, a surface of one end and a surface of the other end can be joined together to contact each other (see...). Figure 7 This is just an example, and the form in which one end of the outer membrane 20 is joined to define a space for accommodating the electrode assembly 10 can vary.

[0147] Reference Figures 7 to 9 The cover 130 of the secondary battery 103 may include a connecting portion 140, a covering portion 50, and a terminal portion 160. The connecting portion 140 of the cover 130 may be connected to the outer membrane 20, and the covering portion 50 of the cover 130 may be connected to the connecting portion 140, such that a portion of the covering portion 50 is exposed to the outside of the connecting portion 140. The terminal portion 160 of the cover 130 may be configured to pass through the connecting portion 140 and the covering portion 50. In addition, one end and the other end of the terminal portion 160 may be exposed to the outside and inside of the connecting portion 140, respectively.

[0148] The following sections will describe each configuration of the Gai 130 in more detail.

[0149] In this example, the cover 50 may be constructed in the same manner as the cover of the secondary battery according to the first example. Specifically, the cover 50 may include a cover portion 51 and an extension portion 54. One surface of the cover portion 51 may be configured to expose the exterior of the connection portion 140. Hereinafter, one surface is referred to as the outward surface 51a, and the surface opposite to the outward surface 51a is referred to as the inward surface 51b. The inward surface 51b may be the surface facing the electrode assembly 10.

[0150] In this example, the extension portion 54 can be embedded in the connecting portion 140. That is, one end of the extension portion 54 may not be exposed inside the connecting portion 140. For this purpose, the connecting portion 140 may include an end-side portion 145 disposed on one side of one end of the extension portion 54 to connect the extension-side portion 44 to the connecting portion 41. The end-side portion 145 may be a portion that covers the end surface 54c of the extension portion 54.

[0151] This structure not only ensures the structural stability of the cover 30, but also the stability of the connection portion 41 where the cover 30 and the outer membrane 20 are sealed. In particular, the advantage of being able to control the ventilation direction can be expected. With the extension portion 54 fully embedded in the connecting portion 140 and therefore no exposed portion inside the connecting portion 140, the possibility of the connecting portion 41 separating from the extension portion 54 of the cover portion 50 can be eliminated.

[0152] In other words, in the event of a rapid increase in internal pressure of the secondary battery 3 causing an explosive release of internal gas, or in the event of a fire causing flames to escape to the outside, since there is no crack through which flames or gas can escape in the direction of the cover 30, venting can be controlled to prevent venting in the direction of the cover 30. Therefore, it is advantageous to solve the following heat transfer phenomenon that may occur due to venting in the direction of the cover 30 when the cover 30 is assembled into the battery pack.

[0153] In this example, the end portion 145 may have an annular shape corresponding to the shape of the extension portion 54. The annular shape may be the shape viewed along the extension direction (X-axis direction) of the electrode assembly 10.

[0154] In this example, the end-side portion 145 can be connected to each of the connecting portion 41 and the extension-side portion 44. Therefore, the extension portion 54 can be fully embedded in the connecting portion 140. Due to this configuration, moisture penetration into the space accommodating the electrode assembly 10 can be further suppressed. This is because a predetermined gap for moisture penetration exists at the junction between the outer surface 54a of the extension portion 54 and the connecting portion 41, and this gap is blocked by the end-side portion 145.

[0155] Furthermore, due to the above configuration, in abnormal situations such as increased internal pressure or explosion, gas or flame may be directed toward the outer membrane 20 for discharge. This is because the gap between the outer surface 54a of the extension 54 and the connecting portion 41 is blocked by the end side portion 145, and thus gas or flame is suppressed from being discharged through the cover 130.

[0156] As described above, in the second example of the present invention, since the extension portion 54 is provided in a manner that is fully embedded in the connecting portion 140, the structural stability of the cover 30 can be improved, and the emission direction of the gas or flame can also be effectively controlled. Furthermore, there is no protruding shape on the other surface of the connecting portion 140 facing the electrode assembly. A portion of the busbar 170, which will be described later, can be provided on this portion.

[0157] Regarding the structure of the terminal portion 160 of the cover 130, the terminal portion 160 may include a body portion 161, an outer portion 162, and an inner portion 163. Specifically, the outer portion 162 may be connected to one end of the body portion 161, and the inner portion 163 may be connected to the other end.

[0158] The body portion 161 of the terminal portion 160 can be configured to pass through the connecting portion 140 and the covering portion 50. That is, the outer peripheral surface of the body portion 161 can contact the connecting portion 140 and the covering portion 50. A predetermined gasket for preventing electrolyte leakage can be provided around the outer side of the body portion 161.

[0159] The exterior 162 of the terminal portion 160 can be exposed to the exterior of the connection portion 140. Therefore, when the secondary battery 103 is electrically connected to the outside to provide electrical power, the exterior 162 can be connected to the outside. The interior 163 of the terminal portion 160 can be exposed to the interior of the connection portion 140. Therefore, the interior 163 can be electrically connected to the electrode assembly 10.

[0160] In the second example according to the invention, the cross-sectional area of ​​each of the outer 162 and inner 163 of the terminal portion 160 is larger than the cross-sectional area of ​​the body portion 161. (See reference...) Figure 9 The terminal portion 160 can be assembled into the connecting portion 140 and the cover portion 50 via the outer portion 162 and the inner portion 163. Therefore, the terminal portion 160 can be prevented from separating, thereby improving the structural stability of the cover 130.

[0161] In the second example of the invention, each of the body portion 161, the outer portion 162, and the inner portion 163 of the terminal portion 160 may have a generally cylindrical shape. That is, each of the body portion 161, the outer portion 162, and the inner portion 163 may have a generally circular cross-section. This is merely an example, and the body portion 161, the outer portion 162, and the inner portion 163 may have different cross-sections from each other.

[0162] As previously described, the interior 163 of the terminal portion 160 extending into the connection portion 140 can be electrically connected to the electrode assembly 10. Here, the electrical connection can include a direct connection between the interior 163 and the electrode assembly 10, as well as an indirect connection via another conductive member.

[0163] When the internal 163 and the electrode assembly 10 are directly connected to each other, the electrode contacts 11 of the electrode assembly 10 can be connected to the internal 163. Alternatively, when the internal 163 and the electrode assembly 10 are indirectly connected to each other, the secondary battery 103 may include a busbar 170, which serves as an example of a conductive member acting as a medium.

[0164] Busbar 170 may be disposed between connector 140 and electrode assembly 10 to connect one end of interior 163 exposed inside connector 140 to electrode assembly 10. Busbar 170 may be made of conductive metal. In addition, busbar 170 may be configured in various shapes depending on the length of interior 163.

[0165] An example of a configuration for efficient arrangement, according to a second example of the invention, the busbar 170 may include a first metal portion 171, a second metal portion 172, a third metal portion 173, and a fourth metal portion 174.

[0166] Reference Figure 9 The first metal portion 171 can contact the connecting portion 140 and the interior 163. One surface of the first metal portion 171 facing the connecting portion 140 can be configured to contact the connecting portion 140. Additionally, another surface of the first metal portion 171 facing the interior 163 can be configured to contact the interior 163. In this respect, the first metal portion 171 can have a generally plate-shaped form and can define a hole at its center. The body portion 161 of the terminal portion 160 can pass through the hole in the first metal portion 171, and the other surface of the first metal portion 171 facing the interior 163 can contact the interior 163. That is, the first metal portion 171 of the busbar 170 can be configured to hook onto the interior 163, such that movement in the direction toward the electrode assembly 10 is restricted by the interior 163. Therefore, effective fixation of the busbar 170 is possible. The terminal portion 160 can include a metallic material, and the interior 163 of the terminal portion 160 and the first metal portion 171 can be joined together by welding.

[0167] The second metal portion 172 can extend from the first metal portion 171 toward the electrode assembly 10. Here, the second metal portion 172 can extend in a direction substantially perpendicular to the direction in which the first metal portion 171 extends. In addition, a surface of the second metal portion 172 facing the connecting portion 140 can contact the connecting portion 140.

[0168] The third metal portion 173 can extend from the second metal portion 172 toward the outer membrane 20. Here, the third metal portion 173 can extend in a direction substantially perpendicular to the direction in which the second metal portion 172 extends. Specifically, the third metal portion 173 can extend in a direction away from the interior 163. In addition, a surface of the third metal portion 173 facing the connecting portion 140 can contact the connecting portion 140.

[0169] The fourth metal portion 174 can extend from the third metal portion 173 toward the electrode assembly 10. In addition, one surface of the fourth metal portion 174 facing the outer membrane 20 can contact the outer membrane 20.

[0170] One end of the fourth metal portion 174 can be connected to the electrode assembly 10. Specifically, one end of the fourth metal portion 174 can be connected to the electrode tab 11 of the electrode assembly 10. In this respect, each of the second metal portion 172, the third metal portion 173, and the fourth metal portion 174 can be arranged in pairs. Here, each of the plurality of electrode tabs 11 of the electrode assembly 10 can be connected to the relatively close fourth metal portion 174. Therefore, even when the secondary battery 103 includes a plurality of electrode assemblies 10 and the number of electrode tabs 11 increases, the fourth metal portion 174 can be effectively connected to the electrode tabs 11.

[0171] According to the second example of the invention, the busbar 170 can be configured to contact the outer membrane 20 or the cover 130. Therefore, the structural stability of the secondary battery 103 can be improved. In addition, since the busbar 170 includes a first metal portion 171, a second metal portion 172, a third metal portion 173, and a fourth metal portion 174, the secondary battery can have various shapes depending on the number, arrangement, and shape of the electrode assemblies 10.

[0172] The form of the busbar 170 described in this invention is merely a preferred example. Therefore, the shape and arrangement of the busbar 170 can vary.

[0173] Example 3

[0174] Figure 10 It is along the third example of the secondary battery according to the present invention. Figure 7 A partial cross-sectional view taken from line C-C'.

[0175] The electrode assembly, outer membrane, cover portion, terminal portion, and busbar of the secondary battery 203 according to the third example of the present invention can be used with the electrode assembly, outer membrane, cover portion, terminal portion, and busbar of the secondary battery 103 according to the second example of the present invention (e.g., Figures 7 to 9 (As shown) is constructed in the same way.

[0176] Reference Figure 10 In the secondary battery 203 according to the third example of the present invention, the connecting portion 240 of the cover 230 may further include an outer portion 242. The outer portion 242 may be configured to cover the outward surface 51a of the cover portion 51 facing the outside of the electrode assembly 10. Therefore, the cover portion 51 may have an outward surface 51a and an inward surface 51b, which are covered by the outer portion 242 and the inner portion 43, respectively. That is, the cover portion 51 may be completely embedded in the connecting portion 240.

[0177] In this example, the outer portion 242 can have a plate-like shape that completely covers the outer surface 51a. Therefore, the cover 50 can be protected from external impacts and contamination. However, the shape of the outer portion 242 is not particularly limited, as long as it covers the outer surface 51a.

[0178] In this example, the edge portion of the outer portion 242 can be connected to the connecting portion 41. The outer portion 242 can be integral with the connecting portion 41. The outer portion 242 and the connecting portion 41 can be made of the same material.

[0179] Therefore, the cover portion 50 can be completely surrounded by the connecting portion 240, and thus the connection between the connecting portion 240 and the cover portion 50 can be improved. In addition, since the gap between the connecting portion 41 and the outer surface 54a of the extension portion 54 is blocked by the outer portion 242, moisture penetration into the space accommodating the electrode assembly 10 can also be very effectively suppressed.

[0180] In this example, the body portion 161 of the terminal portion 160 can pass through the cover portion 50 and the inner portion 43 to pass through the outer portion 242. The outer portion 162 of the terminal portion 160 can be provided at the end of the body portion 161. Here, the end of the body portion 161 can be the portion facing the outer portion 242.

[0181] Here, the cross-sectional area of ​​the outer portion 162 can be larger than the cross-sectional area of ​​the body portion 161. Therefore, one side of the outer portion 162 can be hooked onto the outer portion 242, and thus, the movement (or separation) of the terminal portion 160 can be restricted.

[0182] As described above, in this example, since the outer surface 51a of the cover 50 is covered by the outer portion 242, not only are durability and connection performance improved, but insulation performance between the terminal portion 160 and other components is also improved. Furthermore, in the event of thermal runaway, the outer portion 242 can suppress heat transfer.

[0183] Furthermore, in this example, since the cover 50, made of metal, is surrounded by the connecting portion 240, the cover 230 can be easily manufactured via an injection molding process. Therefore, the productivity of secondary batteries can be increased, the manufacturing process can be simplified, and manufacturing costs can be reduced.

[0184] Example 4

[0185] Figure 11 It is along the fourth example of the secondary battery according to the present invention. Figure 7 A partial cross-sectional view taken along line C-C'. (Refer to...) Figure 11 The electrode assembly 10, outer membrane 20, cover portion 50, terminal portion 160 and busbar 170 of the secondary battery 303 according to the fourth example of the present invention can be constructed in the same manner as the electrode assembly, outer membrane, cover portion, terminal portion and busbar of the secondary battery according to the second example.

[0186] Here, the connecting portion 340 in the cover 330 of the secondary battery 303 according to the fourth example of the present invention may include a connecting portion 41. In addition, the outward surface 51a and inward surface 51b of the covering portion 51, as well as the inner surface 54b and end surface 54c of the extension portion 54, may not be covered by the connecting portion 340.

[0187] In other words, the outward surface 51a, the inward surface 51b, the inner surface 54b, and the end surface 54c can be exposed. Alternatively, if desired, the inward surface 51b, the inner surface 54b, and / or the end surface 54c can be at least partially covered by the busbar 170.

[0188] In this example, the connecting portion 340 may have an annular shape that surrounds the outer surface 54a (or outer peripheral surface) of the extension portion 54. As described above, in this example, the connecting portion 340 may be simply and compactly constructed to have only the connecting portion 41. Therefore, the secondary battery 303 can be made lightweight while achieving rigidity enhancement through the cover portion 50.

[0189] Connections 40, 140, 240, and 340 in Examples 1 to 4

[0190] Modifications to the connecting portions 40, 140, 240, and 340 according to Examples 1 to 4 of the present invention will be described in more detail, such as a modification to the connecting portion 41 of the connecting portion 40. The description of the modified examples can be applied to all examples 1 to 4 according to the present invention and may include modifications that are possible to those skilled in the art. Hereinafter, Example 4 is described as a representative example.

[0191] First, refer to Figure 11According to the first example of the invention, the connecting portion 41 of the connecting portion 340 may include a first layer 41a as a first modification example. The first layer 41a includes a first resin and has an outer surface that allows connection with the inner surface of the outer membrane 20 and an inner surface that allows connection with the outer surface of the cover portion 50.

[0192] The first resin disposed in the first layer 41a can be readily applied to the bonding between the cover portion 50 and the outer film 20. For example, the first resin may include a resin selected from the group consisting of: melting point (T) m The resin has a melting point of 135°C to 150°C, a melt flow rate (MFR) of 4 g / 10 min to 10 g / 10 min at 230°C, and a melting point (T). m The resin is a resin with a melt flow rate (MFR) of 4 g / 10 min to 10 g / 10 min at 135°C to 150°C and at 230°C. When the first resin having the aforementioned physical properties is applied to the first layer 41a, the heat resistance can be excellent, such that even when hot fusion is performed at high temperatures, the first layer 41a can withstand the heat without altering its appearance, thus sufficiently ensuring excellent sealing strength, and can have excellent durability against the increase in internal pressure caused by gases generated inside the secondary battery.

[0193] For example, the first resin may include a modified polyolefin resin. The first layer may include more than 50 wt%, preferably 70 wt% or more, 80 wt% or more, or 90 wt% or more of the first resin. The first resin may be applied alone, and when mixed with the first resin, the residue may include a suitable resin, such as other polyolefin-based resins.

[0194] The modified polyolefin resin can be modified by acid or siloxane, preferably by acid, and more preferably by a polyolefin copolymerized with an acrylic-containing monomer or post-treated with acid. For example, the modified polyolefin resin can be acid-modified polypropylene or acid-modified polyethylene, and can be plasma-treated polypropylene or polyethylene; more preferably, the modified polyolefin resin can include acid-modified polypropylene. When using modified polyolefins, the functional groups introduced through modification can improve the adhesion to the metal surface, and thus facilitate the adhesion between the metal and the resin. Considering that the metal is used as the material for the cover 50, the resin, such as the described resin, can be applied to the connecting portion 40.

[0195] Reference Figure 12As a second modification example, the connecting portion 41 of the connecting portion 340 may include: a first layer 41a, which includes a first resin and allows connection to the outer surface of the cover portion 50; and a second layer 41b, which includes a second resin, is stacked on the outer surface of the first layer and allows connection to the inner surface of the outer membrane 20.

[0196] For example, the first resin disposed in the first layer 41a can be as described above, and the second resin disposed in the second layer 41b can include a resin selected from the group consisting of: melting point (T) m The resin has a melting point of 120°C to 145°C, a melt flow rate (MFR) of 5 g / 10 min to 18 g / 10 min at 230°C, and a melting point (T). m The resin is a resin with a melt flow rate (MFR) of 5 g / 10 min to 18 g / 10 min at 120°C to 145°C and at 230°C.

[0197] In another example, the first resin and the second resin may satisfy at least one of the following equations 1 and 2.

[0198] [Equation 1]

[0199] T m2 > T m1

[0200] In Equation 1, T m1 It is the melting point of the first resin in °C, and T m2 It is the melting point of the second resin in °C.

[0201] [Equation 2]

[0202] MFR2 > MFR1

[0203] In Equation 2, MFR1 is the melt flow rate of the first resin in g / 10 min, and MFR2 is the melt flow rate of the second resin in g / 10 min.

[0204] Compared to the case where the connecting portion 340 is a single layer, when the connecting portion 340 is a double layer, the bonding force with the covering portion 50 and the bonding force with the outer membrane 20 can be further improved, and the sealing strength can be further improved. In particular, when the second layer includes a resin with a higher melting point or a higher melt flow rate than the first resin applied to the first layer, the physical properties can be more similar to the physical properties of the outer membrane 20, which can lead to improved not only sealing processability but also improved bonding force due to thermal fusion. Therefore, the sealing strength can be increased, and thus, the durability against increased internal pressure can be significantly improved.

[0205] For example, the first resin disposed in the first layer 41a can be the same as the first resin described above, and the second resin disposed in the second layer 41b can be, for example, a polyolefin-based resin. The polyolefin-based resin can differ from the first resin in whether or not it incorporates modifying groups. The second resin can be an unmodified polyolefin-based resin, which may include, for example, polypropylene or polyethylene, and can be a homopolymer thereof, or a random copolymer or block copolymer copolymerized with a small amount of comonomer. When the second resin is included in the second layer, the amount of the second resin can be the same as the amount of the first resin when the first resin is included in the first layer.

[0206] The polyolefin-based resin can be, for example, an unstretched polyolefin resin. Unstretched polyolefin resins can be manufactured by casting without being stretched in a particular direction during manufacturing or processing, and are more flexible than stretched polyolefin resins, do not have the problem of tearing in a particular direction, and are relatively easy to process. However, since the connecting portion 40 can be manufactured together with the cover portion 50 by insertion injection, and since the characteristics of the cover 30 may require a certain or higher stiffness, the unstretched polyolefin resin and the stretched polyolefin resin can be appropriately selected according to the required degree by taking into account the physical properties of each resin.

[0207] Reference Figure 13 As a third modification example, the connecting portion 41 of the connecting portion 340 may include: a first layer 41a, which includes a first resin and allows connection to the outer surface of the cover portion 50; a second layer 41b, which includes a second resin and allows connection to the inner surface of the outer membrane 20; and a third layer 41c, which includes a third resin and is disposed between the first layer 41a and the second layer 41b.

[0208] For example, the first and second resins can be as described above, and the third resin can include resins selected from the group consisting of: melting point (T) mThe resin has a melting point of 145°C to 170°C, a melt flow rate (MFR) of 2 g / 10 min to 4 g / 10 min at 230°C, and a melting point (T). m The resin is a resin with a melt flow rate (MFR) of 2 g / 10 min to 4 g / 10 min at 145°C to 170°C and at 230°C.

[0209] In another example, the first resin, the second resin, and the third resin may satisfy at least one of the following equations 3 and 4.

[0210] [Equation 3]

[0211] T m3 > T m2 > T m1

[0212] In equation 3 above, T m1 It is the melting point of the first resin in °C, T m2 It is the melting point of the second resin in °C, and T m3 It is the melting point of the third resin in °C.

[0213] [Equation 4]

[0214] MFR2 > MFR1 > MFR3

[0215] In Equation 4 above, MFR1 is the melt flow rate of the first resin in g / 10 min, MFR2 is the melt flow rate of the second resin in g / 10 min, and MFR3 is the melt flow rate of the third resin in g / 10 min.

[0216] When the connection portion 340 is configured with three layers, the third layer 41c, located between the first layer 41a and the second layer 41b, can be selected from layers whose melting point is higher than that of the other layers and whose melt flow rate is lower than that of the other layers. In this case, the deformation of the connection portion 40 due to heat can be minimized, so as to ensure not only the sealing strength but also the insulation performance.

[0217] The third resin that can be applied to the third layer 41c can be, for example, a resin that meets the above-mentioned melting point and melt flow rate range within the same type of resin as the second resin, and the third resin can be selected as a homopolymer olefin-based resin as a single polymer.

[0218] According to Examples 1 to 4 of the present invention, connecting portions 40, 140, 240 and 340 may be disposed on one surface of the covering portion 50, and may include connecting portions 242, 43, 44 and 145. The connecting portions 242, 43, 44 and 145 are disposed on at least one surface of the covering portion 50 other than the surface of the covering portion 50 where the connecting portion 41 is disposed (e.g., the outer surface 54a) (e.g., the connecting portions 242, 43, 44 and 145 are disposed on the inner surface 54b, the end surface 54c, the outward surface 51a and the inward surface 51b).

[0219] As a first modification example of the connecting portion 41, the connecting portions 242, 43, 44 and 145 of the connecting portions 40, 140, 240 and 340 may include a first layer comprising a first resin and having an inner surface that allows engagement with one surface of the cover portion.

[0220] Additionally, the connecting portions 242, 43, 44, and 145 of the connecting portions 40, 140, 240, and 340 may include: a first layer comprising a first resin and allowing connection to a surface of the cover; and a second layer comprising a second resin and stacked on the outer surface of the first layer.

[0221] Additionally, the connecting portions 242, 43, 44, and 145 of the connecting portions 40, 140, 240, and 340 may include: a first layer comprising a first resin and allowing connection to a surface of the cover; a second layer comprising a second resin and disposed on the outermost side; and a third layer comprising a third resin and disposed between the first and second layers.

[0222] More specifically, in addition to the connecting portion 41, the connecting portion 40 may also include a connecting portion that covers one side of the covering portion 50, and as in Figure 5 In Example 1, the connecting portion may include: an inner portion 43 disposed on the inward surface 51b of the cover portion 51 of the cover portion 50; and an extension side portion 44 disposed on the inner surface 54b (or inner circumferential surface) of the extension portion 54 of the cover portion 50. The inner portion 43 and the extension side portion 44 may be applied independently of the connecting portion 41 with modifications that are the same as or different from the first to third modification examples of the connecting portion 41, and generally, the same modification example manufactured by insert injection of the cover 30 may be applied.

[0223] As another example, in addition to the connecting portion 41, the connecting portion 40 may also include a connecting portion that covers one side of the covering portion 50, and as in Figure 9In Example 2, the connecting portion may include: an inner portion 43 disposed on the inward surface 51b of the covering portion 51 of the covering portion 50; an extension-side portion 44 disposed on the inner surface 54b (or inner peripheral surface) of the extension portion 54 of the covering portion 50; and an end-side portion 145 covering the end surface 54c of the extension portion 54 of the covering portion 50. The inner portion 43, the extension-side portion 44, and the end-side portion 145 may be applied independently of the connecting portion 41 with modifications that are the same as or different from the first to third modification examples of the connecting portion 41, and generally, the same modification example manufactured by insert injection of the cap 30 may be applied.

[0224] As another example, in addition to the connecting portion 41, the connecting portion 40 may also include a connecting portion that covers one side of the covering portion 50, and as in Figure 10 Example 3, the connecting portion may include: an inner portion 43 disposed on the inward surface 51b of the cover portion 51 of the cover portion 50; an extension-side portion 44 disposed on the inner surface 54b (or inner peripheral surface) of the extension portion 54 of the cover portion 50; an end-side portion 145 covering the end surface 54c of the extension portion 54 of the cover portion 50; and an outer portion 242 covering the outward surface 51a facing the electrode assembly 10 on the outer surface of the cover portion 51 of the cover portion 50. The inner portion 43, the extension-side portion 44, the end-side portion 145, and the outer portion 242 may be applied independently of the connecting portion 41 with modifications that are the same as or different from the first to third modification examples of the connecting portion 41, and generally, the same modification example manufactured by insertion injection may be applied to the cap 30.

[0225] Evaluation Example

[0226] The following text describes in detail... Figures 11 to 13 The evaluation example of the connecting portion 41 of the connecting portion 340 illustrated allows those skilled in the art to easily perform the evaluation. However, the invention can be implemented in different forms and should not be construed as limited to the evaluation example set forth herein.

[0227] Evaluation Example 1

[0228] An outer membrane with a polyethylene terephthalate (PET) film (266 mm wide, 50 m long, and 12 μm thick) and a nylon film (266 mm wide, 50 m long, and 25 μm thick) are stacked on one side of an aluminum alloy film (266 mm wide, 50 m long, and 60 μm thick), and a polypropylene film (266 mm wide, 50 μm long, and 80 μm thick) is stacked on the other side of the aluminum alloy film to prepare an outer membrane with a structure of PET / nylon / aluminum alloy film / polypropylene film. Here, the PET and nylon films are the base material layers, the aluminum alloy film is the gas barrier layer, and the polypropylene film is the sealant layer.

[0229] Next, aluminum metal plates with a thickness of 1 mm and maleic anhydride-modified acid-modified polypropylene resin (T) with a thickness of 2 mm were used respectively. m 135°C, MFR 6 g / 10 min), shape and... Figure 11 The connecting portions 41 and 41a of the cover portion 50 and the connecting portion 340 are identical in shape.

[0230] Electrode assemblies are fabricated by stacking negative electrodes, positive electrodes, and porous polyethylene separators, and then, after encapsulating the electrode assemblies with an external film, components with coverings and connectors are used to create an assembly having... Figure 2 The secondary battery is shown in the diagram. Here, the sealing of the outer membrane and the connection is performed for 5 seconds at 240°C and 0.3 MPa.

[0231] Evaluation Example 2

[0232] When the cover portion 50 and the connecting portion 340 are manufactured by injection molding, unstretched polypropylene resin (cPP, T) randomly copolymerized with ethylene is used. m 140°C, MFR 10 g / 10 min) and acid-modified polypropylene resin with maleic anhydride (PPa, T m 135°C, MFR 6 g / 10 min) as the material for the connector 340, using heterogeneous insertion injection, therefore, in addition to such Figure 12 The secondary battery is manufactured using the same method as in Evaluation Example 1, except that an acid-modified polypropylene resin layer (first layer 41a, 1 mm) is formed at the location in contact with the cover 50 and an ethylene copolymer polypropylene resin layer (second layer 41b, 1 mm) is formed at the location in contact with the inner surface of the outer membrane.

[0233] Experimental Example 1: Evaluation of Sealing Strength

[0234] For each secondary battery manufactured in the evaluation example, the following method is used to evaluate the seal strength.

[0235] After cutting the connecting portion of the connector and the outer membrane at 15 mm intervals, the connector is attached to the lower clamp of the UTM, and the outer membrane is attached to the upper clamp. Then, the low-speed sealing strength is calculated by calculating the average value of the 8 mm portion starting from the point exceeding 4.5 N / 15 mm in the sealing strength graph measured at room temperature and 60°C by pulling at a speed of 5 mm / min in a 180° direction.

[0236] [Table 1]

[0237] Room temperature sealing strength (N / 15mm) fracture area Sealing strength at 60°C (N / 15mm) fracture area Evaluation Example 1 78.08 External membrane - connector 30.80 External membrane - connector Evaluation Example 2 141.59 external membrane 121.97 external membrane

[0238] Referring to Table 1 above, in the case of evaluation example 1, the sealing strength of the connecting part manufactured according to the first modified example is evaluated, and when the room temperature sealing strength and the high temperature sealing strength are confirmed, it is confirmed that the required sealing strength level is exceeded. Therefore, it is confirmed that when the connecting part of the connection is made of a resin having the above characteristics, the minimum sealing strength for withstanding internal pressure can be ensured.

[0239] Furthermore, in the case of evaluation example 2, the connecting part of the connector was manufactured according to the second modified example, and due to the strong sealing strength, it was confirmed that the sealing strength was excellent even when the connecting part of the connector did not peel off, but the outer membrane was torn. Moreover, when the structure is double-layered, it was confirmed that the sealing strength was excellent even at high temperatures, similar to the sealing strength at room temperature.

[0240] Although examples of the invention have been described with reference to specific examples, it will be apparent to those skilled in the art that various modifications and alterations can be made without departing from the spirit and scope of the invention as defined in the appended claims.

[0241] [Description of reference numerals in the attached figures]

[0242] 1: Battery pack 2: Package

[0243] 3, 103, 203, 303: Secondary battery; 10: Electrode assembly

[0244] 11: Electrode contacts 20: External film

[0245] 30, 130, 230, 330: Cover; 40, 140, 240: Connecting part

[0246] 41: Connecting part 41a: First layer

[0247] 41b: Second layer; 41c: Third layer

[0248] 242: External Part

[0249] 43: Internal part; 44: Extended part / side part

[0250] 145: End side portion; 50: Covering portion

[0251] 51: Covering portion 51a: Outer surface

[0252] 51b: Inward surface 54: Extension portion

[0253] 54a: Outer surface; 54b: Inner surface

[0254] 54c: End surface; 55: First extension portion

[0255] 56: Second extension 57: Third extension

[0256] 58: Fourth extension portion; 60, 160: Terminal portion

[0257] 161: Main body 162: External

[0258] 163: Internal; 170: Busbar

[0259] 171: First metal part; 172: Second metal part

[0260] 173: Third Metal Section 174: Fourth Metal Section

Claims

1. A secondary battery, comprising: An electrode assembly that extends in one direction; An outer membrane surrounds a portion of the electrode assembly; as well as A cover that covers the remainder of the electrode assembly. The cover includes: A cover portion that covers one side of the electrode assembly in the extending direction; A connecting portion, comprising a connecting part disposed on the outer surface of the cover and connected to the outer membrane; and A terminal portion, at least a portion of which is exposed outside the cover portion, and which is electrically connected to the electrode assembly. The connecting portion of the connecting part includes a first layer comprising a first resin, and has an outer surface that allows connection with the inner surface of the outer membrane and an inner surface that allows connection with the outer surface of the covering part.

2. The secondary battery according to claim 1, wherein, The first resin comprises resins selected from the group consisting of: melting point (T) m The resin has a melting point of 135°C to 150°C, a melt flow rate (MFR) of 4 g / 10 min to 10 g / 10 min at 230°C, and a melting point (T). m The resin is a resin with a melt flow rate (MFR) of 4 g / 10 min to 10 g / 10 min at 135°C to 150°C and at 230°C.

3. The secondary battery according to claim 1, wherein, The first resin includes a modified polyolefin-based resin.

4. The secondary battery according to claim 1, wherein, The connecting portion of the connecting part includes: A first layer, the first layer comprising a first resin and allowing attachment to the outer surface of the cover; and The second layer, comprising a second resin, is stacked on the outer surface of the first layer and allows for bonding to the inner surface of the outer membrane.

5. The secondary battery according to claim 4, wherein, The first resin comprises resins selected from the group consisting of: melting point (T) m The resin has a melting point of 135°C to 150°C, a melt flow rate (MFR) of 4 g / 10 min to 10 g / 10 min at 230°C, and a melting point (T). m The resin is a resin with a melt flow rate (MFR) of 4 g / 10 min to 10 g / 10 min at 135°C to 150°C and at 230°C. The second resin comprises resins selected from the group consisting of: melting point (T) m The resin has a melting point of 120°C to 145°C, a melt flow rate (MFR) of 5 g / 10 min to 18 g / 10 min at 230°C, and a melting point (T). m The resin is a resin with a melt flow rate (MFR) of 5 g / 10 min to 18 g / 10 min at 120°C to 145°C and at 230°C.

6. The secondary battery according to claim 4, wherein, The first resin and the second resin satisfy at least one of the following equations 1 and 2: [Equation 1] T m2 > T m1 Among them, T m1 It is the melting point of the first resin in °C, and T m2 It is the melting point of the second resin in °C. [Equation 2] MFR2 > MFR1 Wherein, MFR1 is the melt flow rate of the first resin in g / 10 min, and MFR2 is the melt flow rate of the second resin in g / 10 min.

7. The secondary battery according to claim 4, wherein, The first resin comprises a modified polyolefin-based resin, and The second resin comprises unstretched polypropylene-based resin.

8. The secondary battery according to claim 1, wherein, The connecting portion of the connecting part includes: A first layer, the first layer comprising the first resin and allowing attachment to the outer surface of the cover; A second layer, comprising a second resin and allowing attachment to the inner surface of the outer membrane; and The third layer comprises a third resin and is disposed between the first layer and the second layer.

9. The secondary battery according to claim 8, wherein, The first resin comprises resins selected from the group consisting of: melting point (T) m The resin has a melting point of 135°C to 150°C, a melt flow rate (MFR) of 4 g / 10 min to 10 g / 10 min at 230°C, and a melting point (T). m The resin is a resin with a melt flow rate (MFR) of 4 g / 10 min to 10 g / 10 min at 135°C to 150°C and at 230°C. The second resin comprises resins selected from the group consisting of: melting point (T) m The resin has a melting point of 120°C to 145°C, a melt flow rate (MFR) of 5 g / 10 min to 18 g / 10 min at 230°C, and a melting point (T). m The resin is a resin with a melt flow rate (MFR) of 5 g / 10 min to 18 g / 10 min at 120°C to 145°C and at 230°C. The third resin includes resins selected from the group consisting of: melting point (T) m The resin has a temperature range of 145°C to 170°C, a melt flow rate (MFR) of 2 g / 10 min to 4 g / 10 min at 230°C, and a melting point (T). m The resin is a resin with a melt flow rate (MFR) of 2 g / 10 min to 4 g / 10 min at 145°C to 170°C and at 230°C.

10. The secondary battery according to claim 8, wherein, The first resin, the second resin, and the third resin satisfy at least one of the following equations 3 and 4: [Equation 3] T m3 >T m2 > T m1 Among them, T m1 It is the melting point of the first resin in °C, T m2 It is the melting point of the second resin in °C, and T m3 It is the melting point of the third resin in °C. [Equation 4] MFR2 > MFR1 > MFR3 Wherein, MFR1 is the melt flow rate of the first resin in g / 10 min, MFR2 is the melt flow rate of the second resin in g / 10 min, and MFR3 is the melt flow rate of the third resin in g / 10 min.

11. The secondary battery according to claim 8, wherein, The first resin includes a modified polyolefin-based resin. The second resin comprises unstretched polypropylene-based resin, and The third resin includes a homopolymer olefin-based resin.

12. The secondary battery according to claim 1, wherein, The connecting portion includes a connecting part disposed on the surface of the covering portion, wherein the connecting part is disposed on at least one surface of the covering portion other than the outer surface of the covering portion on which the connecting part is disposed.

13. The secondary battery according to claim 12, wherein, The connecting portion of the connecting part includes a first layer comprising the first resin and having an inner surface that allows it to be coupled to the surface of the covering part.

14. The secondary battery according to claim 12, wherein, The connecting portion of the connecting part includes: A first layer, the first layer comprising the first resin and allowing attachment to the surface of the cover; and The second layer comprises a second resin and is stacked on the outer surface of the first layer.

15. The secondary battery according to claim 12, wherein, The connecting portion of the connecting part includes: A first layer, the first layer comprising the first resin and allowing attachment to the surface of the cover; The second layer, comprising a second resin and disposed on the outermost side; and The third layer comprises a third resin and is disposed between the first layer and the second layer.

16. The secondary battery according to claim 1, wherein, The outer peripheral surface of the cover extends in the circumferential direction of the electrode assembly, and The connecting portion is disposed on the outer peripheral surface of the cover.

17. The secondary battery according to claim 1, wherein, The covering portion includes: The covering portion has an outwardly facing surface toward the outside of the electrode assembly; and The extension portion extends from the cover portion toward the electrode assembly. The connecting portion is disposed on the outer surface of the extension portion.

18. The secondary battery according to claim 17, wherein, The covering portion has a plate-like shape, and The extension portion extends from the edge of the covered portion.

19. The secondary battery according to claim 1, wherein, The outer membrane has a predetermined flexibility to be bent.

20. A battery pack, comprising: Secondary batteries; as well as Package containing the secondary battery The secondary battery includes: An electrode assembly that extends in one direction; An outer membrane, the outer membrane surrounding a portion of the electrode assembly; and A cover that covers the remainder of the electrode assembly. The cover includes: A cover portion that covers one side of the electrode assembly in the extending direction; A connecting portion, comprising a connecting part disposed on the outer surface of the cover and connected to the outer membrane; and A terminal portion, at least a portion of which is exposed outside the cover portion, and which is electrically connected to the electrode assembly. The connecting portion of the connecting part includes a first layer comprising a first resin, and has an outer surface that allows connection with the inner surface of the outer membrane and an inner surface that allows connection with the outer surface of the covering part.

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