Secondary battery

Abstract

The present invention relates to a rechargeable secondary battery which comprises: an electrode assembly; a pouch-type exterior material provided with an inner space which accommodates the electrode assembly, and exterior material openings which communicate the inner space with the outside; and cover members which are inserted in the exterior material openings, wherein the cover members may comprise body units blocking the exterior material openings, and leg units extending from the corners of the body units toward the inner space.

Description

secondary battery

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0147154, filed October 30, 2023, and Korean Patent Application No. 10-2024-0149724, filed October 29, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a rechargeable secondary battery.

[0005] Unlike primary batteries, which are non-rechargeable, secondary batteries (rechargeable batteries) are rechargeable and dischargeable. Small secondary batteries are used in portable electronic devices such as cell phones, laptops, and camcorders, while medium- or large-sized secondary batteries are widely used as power sources for motors in hybrid vehicles and other vehicles.

[0006] These secondary batteries can be classified into various types depending on the type of outer packaging material that accommodates the electrode assembly. For example, the secondary batteries can be classified into square secondary batteries in which the electrode assembly is accommodated inside a square metal can, cylindrical secondary batteries in which the electrode assembly is accommodated inside a cylindrical metal can, and pouch-type secondary batteries in which the electrode assembly is accommodated inside a pouch made of a laminate sheet.

[0007] Meanwhile, a pouch-type secondary battery can be manufactured by accommodating an electrode assembly in a cup portion within a pouch and then sealing the pouch. However, the molding depth of the cup portion is limited depending on the material properties of the pouch, and there was a problem in that the cup portion could not be molded deep enough to increase the capacity of the secondary battery.

[0008] To solve this problem, there was an attempt to manufacture a pouch-type secondary battery by placing an electrode assembly in a pouch-type outer material, then folding or rolling the outer material to form an internal space for accommodating the electrode assembly, inserting a cover member into an open area communicating with the internal space, and then sealing the outer material and the cover member.

[0009] Fig. 1 is a drawing showing an example of such a pouch-type secondary battery, and Fig. 1 is a drawing schematically showing a front view of such a pouch-type secondary battery. The pouch-type secondary battery (1) includes a pouch-type outer case (3) that accommodates an electrode assembly therein, and a cover member (2) that is inserted into an open area of ​​the outer case (3) and is combined with an inner surface of the outer case (3) to seal the inner space of the outer case (3). The outer case (3) is composed of a metal layer and a resin layer formed on both surfaces of the metal layer, and the cover member (2) can be heat-sealed with an inner resin layer formed on the inner surface of the outer case (3) to seal the inner space of the outer case (3).

[0010] Meanwhile, Fig. 2 is a drawing showing an example of a sealing system for sealing the pouch-type secondary battery of Fig. 1. In order to thermally fuse the outer covering material (3) and the cover member (2), a process of pressing the cover member (2) and the outer covering material (3) with a high-temperature sealing block (4) must be followed. Specifically, when the high-temperature sealing block (4) presses the upper surface (1a) and the lower surface (1b) of the secondary battery (1), the outer covering material (3) can be thermally fused to the upper surface and the lower surface of the cover member (2), respectively. In addition, when the high-temperature sealing block (4) presses the left and right sides (1c, 1d) of the secondary battery (1), the outer covering material (3) can be thermally fused to the left and right sides of the cover member (2), respectively.

[0011] However, when the cover member (2) and the exterior material (3) are heat-sealed in this manner, the heat and pressure by the sealing block (4) are not effectively transmitted to the corner portion (2a) of the cover member (2), so the bonding performance between the corner portion (2a) and the exterior material (3) is reduced, and there is a problem that the internal space of the exterior material (3) is not sealed.

[0012] The present invention has been conceived in recognition of the above problems, and an object of the present invention is to provide a secondary battery capable of effectively sealing the internal space of the outer material by improving the bonding performance of the cover member and the outer material.

[0013] A secondary battery according to a first embodiment of the present invention comprises: an electrode assembly; a pouch-shaped outer material having an internal space for accommodating the electrode assembly and an outer material opening for communicating the internal space with the outside; and a cover member inserted into the outer material opening, wherein the cover member comprises: a body portion blocking the outer material opening; and a leg portion extending from the body portion toward the internal space, wherein the body portion and the leg portion are coupled to an inner surface of the outer material to seal the internal space.

[0014] The above leg portion may extend from a corner of the body portion toward the internal space.

[0015] The above-mentioned exterior material can be formed by rolling or folding the exterior material sheet so that one end and the other end of the exterior material sheet, which includes a metal layer and a resin layer formed on both sides of the metal layer, meet each other.

[0016] One end and the other end of the above outer sheet can be bonded or fused to each other.

[0017] The above body portion and leg portion can be bonded to the inner surface of the outer material by adhesion or fusion.

[0018] The above leg portion can extend from the body portion to the electrode assembly.

[0019] The above body portion may have a rectangular parallelepiped box shape, and the above leg portion may have a rectangular parallelepiped rod shape.

[0020] The above leg portions can be formed one at each of the four corners of the body portion.

[0021] The cover member may have a through hole formed therein into which an electrode lead electrically connected to the electrode assembly is inserted.

[0022] An electrolyte injection port may be formed in the above cover member for injecting an electrolyte into the internal space of the outer material in which the electrode assembly is accommodated.

[0023] Meanwhile, the secondary battery according to the second embodiment of the present invention may include a reinforcing member interposed between the body portion and the leg portion to support the leg portion.

[0024] The above reinforcing member may be spaced a predetermined distance from the electrode assembly and the electrode tab connected to the electrode assembly.

[0025] The above reinforcing member can be bonded to the body portion and the leg portion by adhesion or fusion.

[0026] The above reinforcing member can be installed at an edge formed by the body portion and the leg portion.

[0027] Meanwhile, in the secondary battery according to the third embodiment of the present invention, the leg portion may include a first portion located close to a corner of the body portion and having a relatively thick thickness; and a second portion extending from the first portion toward the internal space and having a relatively thin thickness.

[0028] A convexly protruding streamlined protrusion can be formed in the above first part.

[0029] A concave, streamlined curved portion can be formed in the second portion.

[0030] A secondary battery according to a first embodiment of the present invention includes a cover member having a body portion and a leg portion installed on the body portion, thereby improving the bonding performance of a pouch-shaped outer material and the cover member, thereby effectively sealing the internal space of the outer material.

[0031] A secondary battery according to a second embodiment of the present invention includes a reinforcing member interposed between a body portion and a leg portion, thereby preventing the leg portion from being damaged by an external force applied to the leg portion when sealing the secondary battery.

[0032] Figure 1 is a drawing showing an example of a pouch-type secondary battery.

[0033] FIG. 2 is a drawing showing an example of a sealing system for sealing the pouch-type secondary battery of FIG. 1.

[0034] Figure 3 is a perspective view of a secondary battery according to the first embodiment of the present invention.

[0035] Figure 4 is an exploded perspective view of a secondary battery according to the first embodiment of the present invention.

[0036] Figure 5 is a cross-sectional view taken along the AA' direction of Figure 3.

[0037] Figure 6 is an enlarged view of part A of Figure 5.

[0038] FIG. 7 is a drawing for explaining the length relationship between the electrode tab and the leg portion in a secondary battery according to the first embodiment of the present invention.

[0039] Figure 8 is a perspective view of a secondary battery according to a second embodiment of the present invention.

[0040] Figure 9 is a cross-sectional view taken along the BB' direction of Figure 8.

[0041] FIG. 10 is a drawing showing a secondary battery according to a second embodiment of the present invention in which a reinforcing member is installed between a body portion and a leg portion.

[0042] FIG. 11 is a drawing showing a secondary battery according to a second embodiment of the present invention, in which a reinforcing member is installed between each body portion and leg portion.

[0043] Fig. 12 is a cross-sectional view for explaining the leg structure of a secondary battery according to a third embodiment of the present invention.

[0044] Hereinafter, with reference to the attached drawings, preferred embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited or restricted by the following examples.

[0045] In order to clearly explain the present invention, a detailed description of a part that is irrelevant to the description or a related known technology that may unnecessarily obscure the gist of the present invention has been omitted, and when adding reference signs to components of each drawing in this specification, the same or similar reference signs are attached to the same or similar components throughout the specification.

[0046] In addition, terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0047] Hereinafter, a secondary battery according to the present invention will be described with reference to the drawings.

[0048]

[0049] Example 1

[0050] Fig. 3 is a perspective view of a secondary battery (10) according to a first embodiment of the present invention, and Fig. 4 is an exploded perspective view of a secondary battery (10) according to the first embodiment of the present invention. Fig. 5 is a cross-sectional view taken along the line AA' of Fig. 3.

[0051] Referring to FIGS. 3 to 5, a secondary battery (10) according to a first embodiment of the present invention may include an electrode assembly (100); a pouch-shaped outer material (200) having an internal space (220) for accommodating the electrode assembly (100) and an outer material opening (210) for communicating the internal space (220) with the outside; and a cover member (300) inserted into the outer material opening (210). The cover member (300) includes a body portion (310) that blocks the outer material opening (210); and a leg portion (320) that extends from the body portion (310) toward the internal space (220), and the body portion (310) and the leg portion (320) may be combined with an inner surface (230) of the outer material (200) to seal the internal space (220).

[0052] The electrode assembly (100) is a laminate including an anode, a cathode, and a separator, and may have various structures. For example, the electrode assembly may be a stacked electrode assembly in which the anode, the cathode, and the separator are laminated in one direction, or a stack-folded electrode assembly in which the anode, the cathode, and the separator are laminated in one direction and then folded.

[0053] Here, the positive electrode may include a positive electrode current collector and a positive electrode active material coated on the positive electrode current collector, and the negative electrode may include a negative electrode current collector and a negative electrode active material coated on the negative electrode current collector. The separator is a membrane of an insulating material interposed between the positive electrode and the negative electrode to block contact between the positive electrode and the negative electrode, and a plurality of pores through which positive ions pass may be formed in the separator.

[0054] The outer material (200) is formed by winding an outer material sheet (200a) in one direction, and an internal space (220) for accommodating an electrode assembly (100) can be formed inside the wound outer material sheet (200a). In addition, both sides of the internal space (220) can be connected to the outside.

[0055] Specifically, the exterior sheet (200a) is a sheet having one end (201a) and another end (202a) spaced apart from the one end (201a) in a predetermined direction, and the exterior sheet (200) can be formed by rolling or folding the exterior sheet (200a) so that the one end (201a) and the other end (202a) meet. The one end (201a) and the other end (202a) of the exterior sheet (200a) can be joined to each other in various ways. For example, the one end (201a) and the other end (202a) can be bonded to each other with an adhesive, or the one end (201a) and the other end (202a) can be heat-fused to each other by receiving heat and pressure.

[0056] One end (201a) of the exterior sheet (200a) can be joined to the inner surface or outer surface of the other end (202a). As illustrated in FIG. 4, the outer surface of one end (201a) of the exterior sheet (200a) can be joined to the inner surface of the other end (202a). Additionally, the inner surface of one end (201a) of the exterior sheet (200a) can also be joined to the inner surface of the other end (202a).

[0057] Meanwhile, the exterior sheet (200a) may be a laminate sheet including a metal layer such as aluminum or stainless steel. At this time, a resin layer may be formed on each of the outer and inner surfaces of the metal layer.

[0058] The metal layer can serve as a substrate that maintains mechanical strength and a barrier layer that prevents the infiltration of moisture and oxygen. In addition to preventing the inflow or leakage of foreign substances such as gas and moisture, the metal layer can be composed of aluminum or an aluminum alloy to enhance the strength of the battery case. Examples of aluminum alloys that can be used include alloy numbers 8079, 1N30, 8021, 3003, 3004, 3005, 3104, and 3105, and these can be used alone or in combination.

[0059] The first resin layer coated on the outer surface of the metal layer must have excellent resistance to the external environment in order to protect the electrode assembly from the outside. Therefore, the first resin layer is required to have excellent tensile strength and corrosion resistance relative to its thickness. For the first resin layer, a polyester resin such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), a polyolefin resin such as polyethylene or polypropylene, etc. can be used.

[0060] The second resin layer coated on the inner surface of the metal layer can be combined with a cover member (300) described later to seal the internal space (220), and the second resin layer can be composed of a polyolefin series resin. For example, CPP (Casted Polypropylene), chlorinated polypropylene, polyethylene, ethylene propylene copolymer, polyethylene and acrylic acid copolymer, and polypropylene and acrylic acid copolymer can be used for the second resin layer.

[0061] Conventionally, a pouch-type secondary battery has been manufactured by forming a cup portion on a pouch film, inserting an electrode assembly into the cup portion, and then sealing the pouch film with the formed cup portion with another pouch film. However, due to the material properties of the pouch film, there was a limit to the forming depth of the cup portion, making it impossible to form the cup portion deeply to increase the capacity of the secondary battery. Furthermore, during the forming process of the cup portion, the thickness of the pouch film was reduced, which caused problems such as cracks to occur in the pouch film.

[0062] On the other hand, since the outer covering (200) of the secondary battery (10) according to the first embodiment of the present invention is prepared by rolling or folding the outer covering sheet (200a), the electrode assembly (100) can be accommodated in the inner space (220) of the outer covering (200) without a separate cup portion forming. In this case, since the conventional limitation due to the formation of the cup portion in the outer covering is not applied, the capacity of the secondary battery (10) can be easily increased by increasing the size of the inner space (220). In addition, since the outer covering (200) prepared by rolling or folding the outer covering sheet (200a) does not have a portion where the thickness is reduced, the occurrence of defects such as cracks in the outer covering (200) can be prevented.

[0063] For reference, the secondary battery (10) according to the first embodiment of the present invention can be formed by placing the electrode assembly (100) on the upper surface of the outer sheet (200a) in an unfolded state, and then rolling or folding the outer sheet (200a). In addition, the secondary battery (10) according to the first embodiment of the present invention can be formed by rolling or folding the outer sheet (200a) to form an internal space (220) and an outer opening (210), and then inserting the electrode assembly (100) into the outer opening (210). In both of the above cases, the electrode assembly (100) can be accommodated inside the outer sheet (200) without forming a separate cup portion.

[0064] Meanwhile, the cover member (300) may be a member that is coupled to the outer material (200) and blocks the outer material opening (210). The inner space (220) of the outer material (200) in which the electrode assembly (100) is accommodated may be filled with an electrolyte, and the cover member (300) may seal the inner space (220) to prevent the electrolyte from leaking from the inner space (220). Specifically, the cover member (300) inserted into the outer material opening (210) that connects the inner space (220) and the outside may be coupled to the inner surface (230) of the outer material (200) to seal the inner space (220). Here, the inner surface (230) of the outer material (200) may be the second resin layer described above.

[0065] The cover member (300) may include a body portion (310) that blocks the exterior opening (210) and a leg portion (320) that extends from the body portion (310) toward the interior space (220). At this time, the body portion (310) and the leg portion (320) may be combined with the inner surface (230) of the exterior material (200) to seal the interior space (220). In this case, the inner surface of the exterior material (200) is combined with the body portion (310) and the leg portion (320) formed on the body portion (310), thereby improving the bonding strength between the cover member (300) and the exterior material (200), thereby effectively sealing the interior space (220).

[0066] In particular, the leg portion (320) may extend from a corner of the body portion (310) toward the internal space (220). At this time, the leg portion (320) may be formed at one or more of a plurality of corners formed in the body portion (310). In this case, the inner surface of the exterior material (200) is combined with the body portion (310) and the leg portion (320) formed at the corner of the body portion (310), so that there is an advantageous effect of improving the bonding strength between the corner portion of the cover member (300) and the exterior material (200).

[0067] In addition, the cover member (300) may be formed of a material that is not easily permeable to moisture in order to seal the internal space (220) of the exterior material (200) by being combined with the inner surface (230) of the exterior material (200). For example, the body portion (310) and the leg portion (320) constituting the cover member (300) may be obtained from metal or resin, or may be obtained from a laminate sheet in which a resin layer is formed on both sides of a metal layer.

[0068] Meanwhile, as illustrated in FIGS. 3 and 4, the body portion (310) may have a rectangular box shape. In this case, the four side surfaces of the body portion (310) inserted into the outer material opening (210) face the inner surface (230) of the outer material (200). Since all four side surfaces of the body portion (310) are formed as flat planes, the four side surfaces of the body portion (310) are firmly combined with the inner surface (230) of the outer material (200), so that the inner space (220) of the outer material (200) can be effectively sealed.

[0069] At this time, the body part (310) can be joined to the inner surface (230) of the exterior material (200) by a heat-fusion method to seal the inner space (220) of the exterior material (200). Specifically, the body part (310) and the exterior material (200) can be heat-fused to each other by being pressed by a sealing block in a high temperature state or by receiving heat and pressure simultaneously by the sealing block. Here, the body part (310) has a rectangular parallelepiped box shape, and the sealing block can pressurize each of the four flat surfaces of the body part (310) and the portion where the exterior material (200) meets.

[0070] Here, since there are no protruding or dug-out portions in each of the four areas where the sealing block presses the exterior material (200) and the body part (310), the sealing block can transmit uniform pressure to the pressurized exterior material (200) and the body part (310). In this case, the inner surface (230) of the exterior material (200) can be uniformly heat-sealed to each of the four surfaces of the body part (310).

[0071] In addition, the body part (310) can be bonded to the inner surface (230) of the exterior material (200) in an adhesive manner to seal the inner space (220) of the exterior material (200). At this time, the body part (310) has a rectangular box shape, so a flat adhesive layer can be formed between the four surfaces of the body part (310) and the portions where the inner surface (230) of the exterior material (200) face each other.

[0072] Meanwhile, as illustrated in FIGS. 3 and 4, the leg portion (320) has a rectangular parallelepiped rod shape, and the leg portions (320) can be formed one at each of the four corners of the body portion (310) having a rectangular parallelepiped box shape. Specifically, FIG. 3 illustrates a state in which the leg portions (320) formed one at each of the four corners of the body portion (310) are inserted into the interior of the outer material (200), and FIG. 4 illustrates a cover member (300) composed of the body portion (310) and the leg portions (320) formed at each of the four corners of the body portion (310).

[0073] At this time, each of the leg parts (320) formed at the four corners of the body part (310) can be joined to the inner surface (230) of the exterior material (200) by a heat-fusion method to seal the inner space (220) of the exterior material (200). At this time, the leg parts (320) and the exterior material (200) can be pressurized with a sealing block at a high temperature, or can be heat-fused to each other by receiving heat and pressure simultaneously from the sealing block. The leg parts (320) have a rectangular rod shape, and thus, the part of the exterior material (200) facing the flat surface of the leg parts (320) can be pressed with the sealing block. That is, there is no protruding or dug area in the portion where the sealing block presses the outer material (200) and the leg portion (320), so that the inner surface (230) of the outer material (200) can be uniformly heat-sealed to each of the leg portions (320).

[0074] Meanwhile, Fig. 5 is a cross-sectional view taken along the line AA' of Fig. 3, and Fig. 6 is an enlarged view of part A of Fig. 5. Figs. 5 and 6 illustrate a state in which a cover member (300) and an inner surface (230) of an exterior material (200) are joined by heat fusion. The cover member (300), which is composed of a body portion (310) and a leg portion (320), may be inserted into the exterior material (200) and heat fused with the inner surface (230) of the exterior material (200). At this time, a first heat fusion surface (240) may be formed on a portion of the inner surface (230) of the exterior material (200) that faces the cover member (300), and a second heat fusion surface (350) may be formed on the surface of the cover member (300) to be heat fused with the first heat fusion surface (240).

[0075] The second heat-sealing surface (350) can be formed in various ways on the body portion (310) and the leg portion (320). For example, the second heat-sealing surface (350) can be formed on the surface of the portion of the body portion (310) inserted into the exterior material (200) and the entire portion of the leg portion (320).

[0076] Meanwhile, the leg portion (320) can be bonded to the inner surface (230) of the outer material (200) by adhesive means. At this time, the leg portion (320) has a rectangular rod shape, so a flat adhesive layer can be formed between the portion where the flat surface of the leg portion (320) and the inner surface (230) of the outer material (200) face each other.

[0077] As described above, the leg portions (320) are formed at each of the four corners of the body portion (310) in the shape of a rectangular parallelepiped box and can be bonded to the inner surface (230) of the exterior material (200) by fusion or adhesive means. That is, the leg portions (320) connected to each corner of the body portion (310) are bonded to the inner surface (230) of the exterior material (200), so that the leg portions (320) can effectively seal the inner space (220) of the exterior material (200) by enhancing the bonding force between the corner portions of the body portion (310) and the exterior material (200).

[0078] Meanwhile, as illustrated in FIGS. 3 and 4, an electrolyte injection port may be formed in the cover member (300) for injecting an electrolyte into the internal space (220) of the outer material (200) in which the electrode assembly (100) is accommodated. The electrolyte injection port may be a through hole penetrating the body portion (310) of the cover member (300).

[0079] An electrolyte injection process can be performed to inject electrolyte into the internal space (220) through the electrolyte injection port. For example, a user can place the secondary battery (10) so that the body portion (310) in which the electrolyte injection port is formed faces upward, and then inject the electrolyte into the internal space (220) of the outer material (200) through the electrolyte injection port.

[0080] Additionally, a degassing process can be performed through the electrolyte inlet to discharge gases generated during activation of the secondary battery (10) to the outside. For example, a user can open the electrolyte inlet to induce the discharge of gases in the internal space (220).

[0081] After the electrolyte injection process or degassing process, the electrolyte injection port can be sealed or welded to seal the internal space (220). In addition, it is also possible to install an openable valve in the electrolyte injection port so that the electrolyte injection port can be opened only when necessary.

[0082] Meanwhile, conventional pouch-type secondary batteries were equipped with a gas pocket formed by rolling up a portion of the outer material. The gas pocket was removed from the outer material after capturing the internal gas of the outer material. Therefore, conventionally, there was a problem in that a portion of the outer material was repeatedly discarded.

[0083] In this regard, the secondary battery (10) according to the first embodiment of the present invention includes an electrolyte injection port formed in the cover member (300), and a user can inject electrolyte into the internal space (220) and discharge gas from the internal space (220) to the outside through the electrolyte injection port, thereby solving the conventional problem of a portion of the outer material being repeatedly discarded.

[0084] Meanwhile, as illustrated in FIGS. 3 to 5, a through hole (330) may be formed in the cover member (300) into which an electrode lead (120) electrically connected to the electrode assembly (100) is inserted. The electrode lead (120) is connected to an electrode tab (110) connected to each electrode non-conductive portion of the electrodes stacked in the electrode assembly (100), and a portion of the electrode lead (120) may be exposed to the outside of the secondary battery (10). Here, the through hole (330) may be formed in the body portion (310) of the cover member (300), and the through hole (330) may have a shape corresponding to the shape of the electrode lead (120) into which it is inserted.

[0085] The electrode lead (120) is configured to electrically connect the electrode assembly (100) to another device and may have various shapes. For example, the electrode lead (120) is provided to penetrate the cover member (300) and may be formed in an I-shape so as not to be easily detached from the cover member (300). In addition, electrode tabs (110) may be coupled to one surface of the electrode lead (120).

[0086] Additionally, a sealing member such as an O-ring may be interposed between the through hole (330) and the electrode lead (120), or a sealant layer made of thermoplastic resin may be formed. In this case, the electrolyte injected into the internal space (220) can be prevented from leaking through the through hole (330).

[0087] Meanwhile, Fig. 7 is a drawing for explaining the length relationship between the electrode tab (110) and the leg portion (320). Referring to Fig. 7, the leg portion (320) may be provided in a free volume formed within the outer material (200). Here, the leg portion (320) may be spaced apart from the electrode tab (110) by a predetermined distance. In this case, the leg portion (320) does not interfere with the electrode tab (110) connected to the electrode assembly (100), thereby preventing the electrode tab (110) from being damaged by the leg portion (320).

[0088] In addition, since the leg portion (320) cannot extend through the electrode assembly (100) inside the outer material (200), the length (a) by which the leg portion (320) extends from the body portion (310) must be less than or equal to the length (b) of the space between the body portion (310) and the electrode assembly (100). That is, since the length (a) by which the leg portion (320) extends cannot be longer than the length (b) of the space between the body portion (310) and the electrode assembly (100), when the leg portion (320) has a maximum length, the leg portion (320) can extend from the body portion (310) to the electrode assembly (100). At this time, the portion where the leg portion (320) and the inner surface (230) of the outer material (200) are joined has the maximum length, so that the bonding force between the leg portion (320) and the outer material (200) is strengthened, thereby effectively sealing the inner space (220) of the outer material (200).

[0089]

[0090] Second Example

[0091] The secondary battery according to the second embodiment of the present invention differs from the first embodiment in that it includes a reinforcing member interposed between the body and the leg portion to support the leg portion. The commonalities with the first embodiment will be omitted as much as possible, and the second embodiment will be described focusing on the differences. In other words, it should be understood that any details not described in the second embodiment, if necessary, may be considered as those of the first embodiment.

[0092] Fig. 8 is a perspective view of a secondary battery (10) according to a second embodiment of the present invention. Referring to Fig. 8, the secondary battery (10) according to the second embodiment of the present invention may include a reinforcing member (400) interposed between the body part (310) and the leg part (320) to support the leg part (320). As described above, the sealing block simultaneously presses the outer material (200) and the cover part (300) to seal the internal space (220), and the reinforcing member (400) may be formed on the opposite side of the pressing portion where the sealing block presses the leg part (320) of the cover part (300).

[0093] Accordingly, the reinforcing member (400) supports the leg portion (320) while the sealing block presses the leg portion (320), thereby preventing the leg portion (320) from being bent or damaged toward the inner space (220) of the outer material (200) while sealing the secondary battery (10).

[0094] Meanwhile, FIG. 9 is a cross-sectional view taken along the line BB' of FIG. 8, and FIG. 10 is a drawing showing a state in which a reinforcing member (400) is installed between a body portion (310) and a leg portion (320). As shown in FIGS. 9 and 10, the reinforcing member (400) can be spaced apart from the electrode assembly (100) and the electrode tab (110) connected to the electrode assembly (100) by a predetermined distance. In this case, the reinforcing member (400) does not interfere with the electrode assembly (100) and the electrode tab (110), thereby preventing the electrode assembly (100) and the electrode tab (110) from being damaged by the reinforcing member (400).

[0095] The reinforcing member (400) may be composed of various materials. For example, the reinforcing member (400) may be obtained from a resin, or may be obtained from a laminate sheet having resin layers formed on both sides of a metal layer. In this case, the reinforcing member (400) may be bonded to the body portion (310) and the leg portion (320) by adhesive or thermal fusion. In addition, the reinforcing member (400) may be composed of a metal such as aluminum. In this case, the reinforcing member (400) may be bonded to the body portion (310) and the leg portion (320) by adhesive.

[0096] Meanwhile, the body portion (310) may have a rectangular parallelepiped box shape, and the leg portion (320) may have a rectangular parallelepiped rod shape extending from a corner of the body portion (310) toward the internal space (220) of the exterior material (200). Here, the reinforcing member (400) may be interposed in an edge portion formed between the body portion (310) and the leg portion (320). In this case, as illustrated in FIGS. 8 to 10, the reinforcing member (400) may have a triangular prism shape that is in contact with the body portion (310) and the leg portion (320) at the same time.

[0097] FIG. 11 is a drawing showing a state in which a reinforcing member (400) is installed between each of the body portion (310) and the leg portion (320). Referring to FIG. 11, the leg portions (320) are installed at every corner of the inner surface of the body portion (310), and the reinforcing member (400) can be installed at every edge formed by the body portion (310) and the leg portions (320). Specifically, the leg portions (320) having a rectangular rod shape are respectively installed at four corners of the body portion (310) having a rectangular box shape, and the reinforcing member (400) can be installed at every edge formed by the inner surface of the body portion (310) and one surface of the leg portion (320). In this case, each of the plurality of reinforcing members (400) supports the leg part (320) while the sealing block presses the leg part (320), thereby effectively preventing the leg part (320) from being bent or damaged toward the inner space (220) of the outer material (200) while sealing the secondary battery (10).

[0098]

[0099] Third Example

[0100] The secondary battery according to the third embodiment of the present invention differs from the first and second embodiments in that the leg portions have non-uniform thicknesses. Commonalities with the first and second embodiments will be omitted as much as possible, and the third embodiment will be described with a focus on differences. In other words, it should be understood that any details not described in the third embodiment, if necessary, may be considered as those described in the first and second embodiments.

[0101] Fig. 12 is a cross-sectional view for explaining the leg structure of a secondary battery according to a third embodiment of the present invention.

[0102] Referring to Fig. 12, the leg portion (320) may be composed of a first portion (321) having a relatively thick thickness and a second portion (322) having a relatively thin thickness. Since the leg portion (320) is manufactured by an injection molding process, the first portion (321) and the second portion (322) may be connected integrally.

[0103] The first portion (321) is positioned close to a corner portion of the body portion (310), and the second portion (322) is connected to the first portion (321) and can extend into the internal space (220) of the outer material (200). Here, the second portion (322) can extend toward the internal space (220) until it touches the electrode assembly (100).

[0104] When the leg portion (320) is composed of a relatively thick first portion (321) and a relatively thin second portion (322), the thick first portion (321) is located in a portion where stress is concentrated when sealing the secondary battery (10), so that the leg portion (320) can be prevented from being damaged by the sealing.

[0105] In addition, the second part (322) where stress is relatively not concentrated when sealing the secondary battery (10) is formed thinly, so that the weight of the secondary battery (10) can be reduced to some extent, and the overall energy density of the secondary battery (10) can be improved compared to the case where the entire leg part (320) is formed thickly.

[0106] The leg portion (320) may have a streamlined shape. Specifically, a convexly protruding streamlined protrusion may be formed in the first portion (321), and a concavely dug streamlined curved portion may be formed in the second portion (322).

[0107] At this time, the instantaneous rate of change at the point where the protrusion and the curved portion meet is the same, so that sharp protrusions may not be formed at the point where the protrusion and the curved portion meet. In this case, since there is no point where stress is concentrated in the leg portion (320), even when the secondary battery (10) is strongly sealed, the leg portion (320) can be prevented from being damaged.

[0108]

[0109] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and various embodiments are possible within the scope equivalent to the technical idea of ​​the present invention and the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0110]

[0111] [Explanation of symbols]

[0112] 10: Secondary battery 100: Electrode assembly

[0113] 110: Electrode tab 120: Electrode lead

[0114] 200: Exterior material 200a: Exterior material sheet

[0115] 201a: One end of the exterior sheet 202a: The other end of the exterior sheet

[0116] 210: Exterior opening 220: Interior space

[0117] 230: Inner surface of exterior material 240: Sealing surface of exterior material

[0118] 300: Cover member 310: Body part

[0119] 320: Leg 321: Part 1

[0120] 322: Part 2 330: Penetration

[0121] 350: Cover member sealing surface 400: Reinforcing member

Claims

1. Electrode assembly; A pouch-shaped outer material having an internal space for accommodating the electrode assembly and an outer material opening for communicating the internal space with the outside; and Including a cover member inserted into the above outer material opening, The above cover member, A body part blocking the above-mentioned exterior opening; and It includes a leg portion extending from the above body portion toward the above internal space, A secondary battery in which the body and leg portions are combined with the inner surface of the outer material to seal the inner space.

2. In claim 1, A secondary battery in which the leg portion extends from a corner of the body portion toward the internal space.

3. In claim 1, The above exterior material is, A secondary battery characterized in that the outer sheet is formed by rolling or folding so that one end and the other end of the outer sheet, which includes a metal layer and a resin layer formed on both sides of the metal layer, meet each other.

4. In claim 3, A secondary battery characterized in that one end and the other end of the outer sheet are bonded or fused to each other.

5. In claim 1, A secondary battery characterized in that the body portion and the leg portion are bonded to the inner surface of the outer material by adhesion or fusion.

6. In claim 1, A secondary battery characterized in that the leg portion extends from the body portion to the electrode assembly.

7. In claim 2, The above body part has a rectangular box shape, A secondary battery characterized in that the leg portion has a rectangular rod shape.

8. In claim 7, A secondary battery characterized in that the leg portion is formed one at each of the four corners of the body portion.

9. In claim 1, A secondary battery characterized in that the cover member has a through hole formed therein into which an electrode lead electrically connected to the electrode assembly is inserted.

10. In claim 1, A secondary battery characterized in that an electrolyte injection port is formed in the cover member for injecting an electrolyte into the internal space of the outer material in which the electrode assembly is accommodated.

11. In claim 2, A secondary battery characterized in that it further includes a reinforcing member interposed between the body portion and the leg portion to support the leg portion.

12. In claim 11, A secondary battery, characterized in that the reinforcing member is spaced a predetermined distance from the electrode assembly and the electrode tab connected to the electrode assembly.

13. In claim 11, A secondary battery characterized in that the reinforcing member is bonded to the body and leg portions by adhesion or fusion.

14. In claim 11, A secondary battery characterized in that the reinforcing member is installed at an edge formed by the body portion and the leg portion.

15. In claim 2, The above leg part, A first part located close to a corner of the above body part and having a relatively thick thickness; and A secondary battery characterized in that it includes a second portion extending toward the internal space from the first portion and having a relatively thin thickness.

16. In claim 15, A secondary battery characterized in that a convexly protruding streamlined protrusion is formed in the first portion.

17. In claim 15, A secondary battery characterized in that a streamlined, concave curved portion is formed in the second portion.

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