Secondary battery

Abstract

The present invention relates to a secondary battery and, more particularly, to a rechargeable secondary battery. The secondary battery according to an embodiment of the present invention may comprise: an electrode assembly: a pouch-type outer case having an inner space for accommodating the electrode assembly and an outer case opening for communicating the inner space with the outside; a cover member inserted into the outer case opening to seal the inner space; and a gas pocket formed in the pouch-type outer case to collect gas generated in 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. 10-2023-0183578, filed December 15, 2023, and Korean Patent Application No. 10-2024-0178695, filed December 4, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a secondary battery, and more particularly, to a secondary battery capable of being charged and discharged.

[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] Secondary batteries can be classified into various types depending on the type of outer packaging material that houses the electrode assembly. For example, secondary batteries can be classified into square secondary batteries in which the electrode assembly is housed inside a square metal can, cylindrical secondary batteries in which the electrode assembly is housed inside a cylindrical metal can, and pouch-type secondary batteries in which the electrode assembly is housed inside a pouch case.

[0007] Such pouch-type secondary batteries can be manufactured by joining a pouch-type case with a formed cup portion. Fig. 1 is a drawing showing an example of a pouch-type secondary battery. The secondary battery (1) of Fig. 1 may include a pouch-type case (2) that accommodates an electrode assembly and electrode leads (3) protruding from both sides of the pouch-type case (2). At this time, a cup portion is formed in the pouch-type case (2), and the electrode assembly can be accommodated inside the formed cup portion.

[0008] Fig. 2 is a drawing showing a cup portion of a pouch-type secondary battery. Fig. 2 shows a pouch film (2) pressed downward. A concave cup portion (2') is formed in the pouch film (2). At this time, the molding depth of the cup portion (2') is limited due to the material properties of the pouch film (2). Therefore, it is difficult to mold the cup portion (2') sufficiently deep to increase the capacity of the secondary battery, and as the thickness of the pouch film (2) decreases during molding of the cup portion (2'), there is a problem in that defects such as cracks are likely to occur in the cup portion (2').

[0009] Meanwhile, as the charging and discharging of a pouch-type secondary battery is repeated, gas may be generated inside the pouch-type case. Fig. 3 is a drawing showing gas generation inside a pouch-type secondary battery. Fig. 3 illustrates that the pouch case (2) has expanded due to the repeated charging and discharging of the secondary battery (1). If this expansion continues, there are problems such as the pouch case (2) bursting, the electrolyte inside leaking out, and the high-pressure gas inside being released into the surrounding area.

[0010] The present invention has been conceived in recognition of the above problems, and the purpose of the present invention is to provide a secondary battery that can solve problems that occur in the process of forming a cup portion into a pouch.

[0011] In addition, an object of the present invention is to provide a secondary battery that can solve the problem of a pouch case being damaged by gas generated inside the pouch case during continuous charging and discharging of the secondary battery.

[0012] A secondary battery according to a first embodiment of the present invention may include: 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; a cover member inserted into the outer material opening to seal the internal space; and a gas pocket formed in the pouch-shaped outer material to capture gas generated in the internal space.

[0013] The above pouch-shaped outer material can be formed by rolling or folding the outer material sheet so that one end and the other end of the outer material sheet including the metal layer meet each other.

[0014] One end and the other end of the above outer sheet can be bonded or fused to each other.

[0015] The above gas pocket can be connected to the pouch-shaped outer material.

[0016] One end of the gas pocket may be connected to the pouch-shaped outer material, and the other end of the gas pocket may be connected to the cover member.

[0017] The other end of the above gas pocket can be bonded to the cover member by adhesive or fusion.

[0018] The above gas pocket can be connected to the internal space to form a gas collection space that collects gas generated in the internal space.

[0019] The above gas pocket may have a folded shape of an empty hexahedral box.

[0020] The gas pocket may include a first folding portion folded in one direction; and a second folding portion connected to the first folding portion and folded in a different direction from the first folding portion.

[0021] The secondary battery according to the first embodiment of the present invention may further include a pulling member that pulls the second folding part toward the cover member.

[0022] The above pulling member may include a tape having one end attached to the tip portion of the second folding member and the other end attached to the cover member.

[0023] The cover member may have a lead insertion hole formed into which an electrode lead electrically connected to the electrode assembly is inserted.

[0024] An electrolyte injection port for injecting an electrolyte into the internal space may be formed in the above cover member.

[0025] In a secondary battery according to a second embodiment of the present invention, a plurality of gas pockets may be formed in the pouch-shaped outer material.

[0026] The above cover member may have a rectangular block shape.

[0027] Each of the plurality of said gas pockets may be in contact with a different surface of the said cover member.

[0028] According to the secondary battery according to the present invention, since a pouch-shaped outer material can be prepared without forming a cup portion for accommodating an electrode assembly, the battery capacity can be increased by increasing the size of the pouch-shaped outer material, the material and thickness of the outer material sheet for manufacturing the pouch-shaped outer material can be freely selected, and there are advantageous effects of preventing defects such as cracks from occurring in the pouch-shaped outer material.

[0029] In addition, according to the secondary battery according to the present invention, a gas pocket is formed in the pouch-shaped outer material to capture gas generated in the internal space, which has the advantageous effect of delaying or preventing damage to the pouch due to internal pressure.

[0030] Figure 1 is a drawing showing an example of a pouch-type secondary battery.

[0031] Figure 2 is a drawing showing the cup portion of a pouch-type secondary battery.

[0032] Figure 3 is a drawing showing gas generated inside a pouch-type secondary battery.

[0033] Figure 4 is a perspective view of a secondary battery according to the first embodiment of the present invention.

[0034] Figure 5 is an exploded perspective view of the secondary battery according to Figure 4.

[0035] Figure 6 is an expanded view of an outer sheet constituting a secondary battery according to the first embodiment of the present invention.

[0036] FIG. 7 is a perspective view showing a secondary battery according to the first embodiment of the present invention, in which a second part of an outer sheet folded into a rectangular box shape is provided on the upper side of a cover member.

[0037] Figure 8 is a cross-sectional view taken in the XX' direction of Figure 7.

[0038] Fig. 9 is a cross-sectional view showing the gas pocket of Fig. 8 pressurized in the AA' direction.

[0039] Fig. 10 is a cross-sectional view showing the gas pocket of Fig. 9 folded.

[0040] Figure 11 is an enlarged view of part B of Figure 10.

[0041] FIG. 12 is a drawing for explaining a process in which gas in an internal space is captured into a gas pocket in a secondary battery according to the first embodiment of the present invention.

[0042] Fig. 13 is a cross-sectional view showing a secondary battery according to the first embodiment of the present invention, in which a pulling member is attached to a gas pocket.

[0043] Figure 14 is a front view of a secondary battery according to a second 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 drawing showing gas generated inside a pouch-type secondary battery, and Fig. 4 is a perspective view of a secondary battery according to the first embodiment of the present invention.

[0051] Referring to FIGS. 3 and 4, 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; a cover member (300) inserted into the outer material opening (210) to seal the internal space (220); and a gas pocket (230) formed in the pouch-shaped outer material (200) to capture gas generated in 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 pouch-shaped 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 outer casing 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 pouch-shaped outer casing (200) can be formed by rolling or folding the outer casing 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 outer casing 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. 5, 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 pouch-shaped outer material (200) of the secondary battery (10) according to the present invention is prepared by rolling or folding the outer material sheet (200a), the electrode assembly (100) can be accommodated in the internal space (220) of the pouch-shaped outer material (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 material is not applied, the capacity of the secondary battery (10) can be easily increased by increasing the size of the internal space (220). In addition, since the pouch-shaped outer material (200) prepared by rolling or folding the outer material sheet (200a) does not have a portion where the thickness is reduced, the occurrence of defects such as cracks in the pouch-shaped outer material (200) can be prevented.

[0063] For reference, the secondary battery (10) according to 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 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 pouch-shaped pouch-shaped outer sheet (200) without forming a separate cup portion.

[0064] Meanwhile, referring to FIGS. 4 and 5, the cover member (300) may be a member that is coupled to the pouch-shaped outer material (200) and blocks the outer material opening (210). The internal space (220) of the pouch-shaped 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 internal space (220) to prevent the electrolyte from leaking from the internal space (220).

[0065] Specifically, the cover member (300) inserted into the exterior opening (210) that connects the interior space (220) and the exterior is combined with the interior surface of the pouch-shaped exterior material (200) and the other end (232) of the gas pocket (230) described later, thereby sealing the interior space (220) and the gas collection space (S) described later. Here, the interior surface of the pouch-shaped exterior material (200) can be the second resin layer described above.

[0066] Meanwhile, the length of the portion of the cover member (300) inserted into the interior of the pouch-shaped outer material (200) may be formed in various ways. For example, as illustrated in FIGS. 4 and 5, only a portion of the cover member (300) may be inserted into the interior of the pouch-shaped outer material (200), and the remaining portion of the cover member (300) may be exposed to the exterior of the pouch-shaped outer material (200).

[0067] Additionally, the cover member (300) may be composed of a material that is not easily permeable to moisture. For example, 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] The cover member (300) may have various shapes. For example, the cover member (300) may be composed of a body (310) and a gasket (320) and may block the internal space (220) of the outer material (200). Specifically, a through hole (311) through which a gas lead (120) passes may be formed in the body (310). The gasket (320) is a member that surrounds the body (310) and may prevent electrolyte leakage between the outer material (200) and the body (310). In this case, the gasket (320) may also serve as a medium for a firm bond between the outer material (200) and the body (310).

[0069] The gasket (320) may have various shapes. For example, the gasket (320) may have a frame shape that surrounds a side surface of the outer surface of the body (310). In addition, the gasket (320) may be formed to surround both the inner and outer surfaces of the body (310).

[0070] Meanwhile, the cover member (300) can be combined with the inner surface of the pouch-shaped outer material (200) and the other end (232) of the gas pocket (230) in various ways. For example, the cover member (300) can be combined with the inner surface of the pouch-shaped outer material (200) and the other end (232) of the gas pocket (230) by an adhesive, or the cover member (300) can be heat-sealed with the inner surface of the pouch-shaped outer material (200) and the other end (232) of the gas pocket (230).

[0071] The gas pocket (230) captures gas generated in the internal space (220) due to charging and discharging of the secondary battery (10), and can be formed in the pouch-shaped outer material (200). In this case, the gas generated in the internal space (220) is captured in the gas pocket (230), so that even when gas is generated in the internal space (220), there is an advantageous effect of preventing swelling or tearing of the pouch-shaped outer material (200).

[0072] Meanwhile, the gas pocket (230) is composed of the same material as the pouch-shaped outer material (200) and can be connected to the pouch-shaped outer material (200). That is, the gas pocket (230) can be composed of a laminate sheet including a metal layer such as aluminum or stainless steel. At this time, a resin layer can be formed on each of the outer and inner surfaces of the metal layer.

[0073] A lead insertion hole (311) into which an electrode lead (120) electrically connected to an electrode assembly (100) is inserted may be formed in a body (310) of a cover member (300). The electrode lead (120) is connected to an electrode tab (110) connected to each electrode non-conductive portion of the electrodes stacked on 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 lead insertion hole (311) may have a shape corresponding to the shape of the electrode lead (120) into which it is inserted.

[0074] Meanwhile, a sealing member such as an O-ring may be interposed between the lead insertion port (311) and the electrode lead (120), or a sealant layer made of thermoplastic resin may be formed. In this case, it is possible to prevent the electrolyte injected into the internal space (220) from leaking through the lead insertion port (311).

[0075] An electrolyte injection port for injecting electrolyte into the internal space (220) may be formed in the cover member (300). Here, the electrolyte injection port may be a through hole penetrating the cover member (300).

[0076] Through these electrolyte injection ports, an electrolyte injection process can be performed to inject electrolyte into the internal space (220) of the secondary battery (10). For example, a user can inject electrolyte into the internal space (220) through the electrolyte injection port while arranging the secondary battery (10) so that the cover member (300) in which the electrolyte injection port is formed faces upward.

[0077] 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).

[0078] 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.

[0079] Meanwhile, conventional pouch-type secondary batteries have a gas pocket formed by rolling up a portion of the outer material, and the gas pocket is removed from the outer material after capturing the internal gas of the outer material. Therefore, there has been a problem in the past of repeatedly discarding a portion of the outer material. In this regard, the secondary battery (10) according to the present invention includes an electrolyte injection port formed in a 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 repeatedly discarding a portion of the outer material.

[0080] FIG. 6 is a development diagram of an outer shell sheet constituting a secondary battery according to a first embodiment of the present invention. Referring to FIG. 6, the outer shell sheet (200a) may be composed of a first portion (A) that is rolled or folded in one direction to form a pouch-shaped outer shell (200) and a second portion (B) that is folded into a rectangular box shape to form a gas pocket (230). At this time, as illustrated in FIG. 6, the first portion (A) and the second portion (B) may be connected to each other.

[0081] The second part (B) is folded into a rectangular box shape to form a gas pocket (230), and the gas collection space (S) inside the gas pocket (230) can be connected to the inner space (220) of the pouch-shaped outer material (200). To this end, when the second part (B) is folded into a rectangular box shape, the two corners (p, q) illustrated in FIG. 6 can be maintained in a state in which they are not connected to each other.

[0082] Specifically, when the second part (B) is folded into a rectangular box shape, the two corners (p, q) face each other, and here, the two corners (p, q) may not be joined to each other but may remain separated. The two corners (p, q) may become one end (231) and the other end (232) of a gas pocket (230) described below, respectively.

[0083] Meanwhile, FIG. 7 is a perspective view showing a secondary battery according to the first embodiment of the present invention, in which a second part of an outer sheet folded into a rectangular box shape is provided on the upper side of a cover member, and FIG. 8 is a cross-sectional view taken in the XX' direction of FIG. 7.

[0084] Referring to FIGS. 7 and 8, the second portion (B) described above may be folded to have a gas pocket (230) having a rectangular box shape. The gas pocket (230) is provided on the upper side of the cover member (300), and one end (231) and the other end (232) of the gas pocket (230) may be separated from each other. Here, one end (231) of the gas pocket (230) may be connected to the pouch-shaped outer material (200), and the other end (232) of the gas pocket (230) may be coupled to the cover member (300).

[0085] Specifically, one end (231) of the gas pocket (230) is supported by the other end (232) of the gas pocket (230), but the one end (231) and the other end (232) are not bonded to each other, so that when the internal pressure of the secondary battery (10) increases, the one end (231) can be separated from the other end (232). When the internal pressure of the secondary battery (10) increases, the internal gas of the secondary battery (10) can flow into the gas collection space (S) through the space between the one end (231) and the other end (232).

[0086] In this case, the gas collection space (S) formed inside the gas pocket (230) can be communicated with the internal space (220) formed by the pouch-shaped outer material (200). As the cover member (300) is coupled to the pouch-shaped outer material (200) and the gas pocket (230), the gas collection space (S) and the internal space (220) can be sealed from the outside. That is, the cover member (300) can be a sealing member that seals the gas collection space (S) and the internal space (220).

[0087] Meanwhile, the other end (232) of the gas pocket (230) can be coupled to the cover member (300) in various ways. For example, the other end (232) of the gas pocket (230) can be coupled to the cover member (300) by adhesive or fusion.

[0088] Meanwhile, Fig. 9 is a cross-sectional view showing the gas pocket of Fig. 8 being pressed in the AA' direction, and Fig. 10 is a cross-sectional view showing the gas pocket of Fig. 9 being folded. Referring to Figs. 8 to 10, the gas pocket (230) in the shape of an empty rectangular box is pressed flat from both sides and then folded in a zigzag shape to be provided on the upper side of the pouch-shaped outer material (200) and the cover member (300).

[0089] In this case, the gas pocket (230) is folded in a zigzag shape while being pressed flat, so that the volume occupied by the gas pocket (230) in the secondary battery (10) is reduced. That is, the overall volume of the secondary battery (10) is reduced, which has the advantageous effect of reconsidering the space utilization of the space in which the secondary battery (10) is installed (e.g., the internal space of a battery module, a battery pack, or an electronic device).

[0090] Meanwhile, Fig. 11 is an enlarged view of part B of Fig. 10. Fig. 11 illustrates a first folding portion (230a) and a second folding portion (230b). Specifically, the gas pocket (230) may include a first folding portion (230a) folded in one direction; and a second folding portion (230b) connected to the first folding portion (230a) and folded in a different direction from the first folding portion (230a).

[0091] The first folding portion (230a) is a portion folded from the upper side of the cover member (300) among the gas pockets (230) toward the upper side of the pouch-shaped outer material (200), and the first folding portion (230a) may include one end (231) and the other end (232) of the gas pocket (230). The second folding portion (230b) is a portion folded from the upper side of the pouch-shaped outer material (200) among the gas pockets (230) toward the upper side of the cover member (300), and the second folding portion (230b) may be connected to the first folding portion (230a).

[0092] That is, the gas pocket (230) can be folded in a zigzag shape and provided on the upper side of the pouch-shaped outer material (200) and the cover member (300). In this case, there is an advantageous effect of minimizing the volume of the gas pocket (230) without gas flowing into the gas collection space (S).

[0093] Meanwhile, Fig. 12 is a drawing for explaining the process of capturing gas in an internal space into a gas pocket in a secondary battery according to the first embodiment of the present invention. Fig. 12 illustrates that gas generated in an internal space (220) flows into a gas capture space (S) of a gas pocket (230) due to charging and discharging of the secondary battery (10).

[0094] Due to this, the gas pocket (230) in the folded state expands, and while the gas pocket (230) expands, the internal pressure of the internal space (220) is maintained constant, so that an increase in the pressure of the internal space (220) can be prevented or delayed. In this case, there is an advantageous effect of being able to prevent or delay the expansion or tearing of the pouch-shaped outer material (200) due to an increase in the pressure of the internal space (220).

[0095] Meanwhile, Fig. 13 is a cross-sectional view showing a secondary battery according to the first embodiment of the present invention, in which a pulling member is attached to a gas pocket. Referring to Fig. 13, the secondary battery (10) according to the first embodiment of the present invention may further include a pulling member (400) that pulls the second folding portion (230b) toward the cover member (300). The pulling member (400) pulls the second folding portion (230b) toward the cover member (300), thereby allowing the gas pocket (230) in a folded state to be pressed against the cover member (300). That is, the gas pocket (230) in which no gas is captured in the gas collection space (S) is pressed against the cover member (300), which has the advantageous effect of reducing the overall volume of the secondary battery (10).

[0096] The pulling member (400) may be a tape (410) having one end (411) attached to the tip portion (230b') of the second folding member (230b) and the other end (412) attached to the cover member (300). Here, the connection between one end (411) of the tape (410) and the tip portion (230b') of the second folding member (230b) may be released as gas is captured in the gas collection space (S). In addition, the connection between the other end (412) of the tape (410) and the cover member (300) may be released as gas is captured in the gas collection space (S).

[0097] Specifically, as gas generated in the internal space (220) flows into the gas collection space (S), the gas pocket (230) in the folded state can expand. When the gas pocket (230) expands and its volume increases, the tape (410) can no longer adhere the gas pocket (230) toward the cover member (300). That is, as the gas pocket (230) expands, the bond between one end (411) of the tape (410) and the tip portion (230b') of the second folding portion (230b) may be released, or the bond between the other end (412) of the tape (410) and the cover member (300) may be released.

[0098] In this case, when gas flows into the gas collection space (S), the adhesive bond of the tape (410) is released, so that the volume of the gas pocket (230) can be reduced by normally pressing the gas pocket (230) toward the cover member (300) without interfering with the gas collection in the gas collection space (S).

[0099]

[0100] Second Example

[0101] The secondary battery according to the second embodiment of the present invention differs from the first embodiment in that it includes multiple gas pockets. Commonalities with the first embodiment will be omitted as much as possible, and the second embodiment will be described with a focus on differences. It should be understood that any details not described in the second embodiment, if necessary, may be considered as those described in the first embodiment.

[0102] Fig. 14 is a front view of a secondary battery according to a second embodiment of the present invention. Fig. 14 illustrates a state in which a plurality of gas pockets (230a, 230b, 230c, 230d) are combined with a cover member (300). The secondary battery (10) according to the second 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; a cover member (300) inserted into the outer material opening (210) to seal the internal space (220); and a plurality of gas pockets (230a, 230b, 230c, 230d) formed in the pouch-shaped outer material (200) for capturing gas generated in the internal space (220). That is, a gas collection space for collecting gas generated in the internal space (220) can be formed in each of the plurality of gas pockets (230a, 230b, 230c, 230d).

[0103] At this time, one end of each of the plurality of gas pockets (230a, 230b, 230c, 230d) may be connected to the pouch-shaped outer material (200). That is, the pouch-shaped outer material (200) may have a plurality of gas pockets (230a, 230b, 230c, 230d). In this case, the secondary battery (10) has a plurality of free spaces formed therein that can capture gas generated in the internal space (220), so that even when a large amount of internal gas is generated, the pouch-shaped outer material (200) can be effectively prevented from being vented or torn.

[0104] Meanwhile, in the secondary battery (10) according to the second embodiment of the present invention, the cover member (300) may have a rectangular parallelepiped block shape. At this time, each of the plurality of gas pockets (230a, 230b, 230c, 230d) may be in contact with different surfaces of the cover member (300). Specifically, one end of each of the plurality of gas pockets (230a, 230b, 230c, 230d) may be coupled to different surfaces of the cover member (300). Here, one end of each of the plurality of gas pockets (230a, 230b, 230c, 230d) may be coupled to the cover member (300) by adhesive or fusion.

[0105] Each of the plurality of gas pockets (230a, 230b, 230c, 230d) may have a shape in which an empty hexahedral box is folded. Specifically, each of the plurality of gas pockets (230a, 230b, 230c, 230d) may include a first folding portion folded in one direction and a second folding portion folded in a direction different from the first folding portion.

[0106] In addition, the secondary battery (10) according to the second embodiment of the present invention may further include a pulling member that pulls each of the plurality of gas pockets (230a, 230b, 230c, 230d) toward the cover member (300). Here, the pulling member may include a plurality of tapes that are respectively attached to the plurality of gas pockets (230a, 230b, 230c, 230d). Specifically, one end of each tape may be attached to a tip portion of each of the plurality of gas pockets (230a, 230b, 230c, 230d), and the other end of each tape may be attached to the cover member (300).

[0107]

[0108] 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.

[0109]

[0110] [Explanation of symbols]

[0111] 10: Secondary battery 100: Electrode assembly

[0112] 110: Electrode tab 120: Electrode lead

[0113] 200: Exterior material 201: Pocket forming part

[0114] 202: Space formation section 200a: Exterior material sheet

[0115] 201a: Exterior sheet end 202a: Exterior sheet end

[0116] 210: Exterior opening 220: Interior space

[0117] 230: Gas pocket 230a: First folding section

[0118] 230b: Second folding part 300: Cover member

[0119] 310: Body 320: Gasket

[0120] 400: Pull member 410: Tape

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; A cover member inserted into the above outer material opening to seal the internal space; and A secondary battery including a gas pocket formed in the pouch-shaped outer shell and capturing gas generated in the internal space.

2. In claim 1, The above pouch-shaped outer material is, A secondary battery characterized in that the outer sheet including the metal layer is formed by rolling or folding the outer sheet so that one end and the other end of the outer sheet meet each other.

3. In claim 2, A secondary battery, characterized in that one end and the other end of the outer sheet are adhered or fused to each other.

4. In claim 1, A secondary battery characterized in that the gas pocket is connected to the pouch-shaped outer shell.

5. In claim 4, One end of the above gas pocket is connected to the pouch-shaped outer material, A secondary battery, characterized in that the other end of the gas pocket is coupled to the cover member.

6. In claim 5, A secondary battery, characterized in that the other end of the gas pocket is bonded to the cover member by adhesion or fusion.

7. In claim 1, The above gas pocket is, A secondary battery characterized in that it is connected to the internal space and forms a gas capturing space that captures gas generated in the internal space.

8. In claim 1, A secondary battery characterized in that the above gas pocket has a folded shape of an empty hexahedral box.

9. In claim 8, The above gas pocket is, a first folding portion folded in one direction; and A secondary battery characterized by including a second folding part connected to the first folding part and folded in a different direction from the first folding part.

10. In claim 9, A secondary battery characterized by further including a pulling member that pulls the second folding part toward the cover member.

11. In claim 10, The above pulling member is, A secondary battery characterized in that it includes a tape, one end of which is attached to a tip portion of the second folding portion and the other end is attached to the cover member.

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

13. In claim 1, A secondary battery characterized in that an electrolyte injection port for injecting electrolyte into the internal space is formed in the cover member.

14. In claim 1, A secondary battery characterized in that a plurality of gas pockets are formed in the pouch-shaped outer packaging material.

15. In claim 14, A secondary battery, characterized in that the above cover member has a rectangular block shape.

16. In claim 15, A secondary battery, characterized in that each of the plurality of gas pockets is in contact with a different surface of the cover member.

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