Battery case and secondary battery comprising same

Abstract

According to an aspect of the present invention, this battery case may comprise: an electrode assembly accommodation part in which an electrode assembly, in which an electrode and a separator are stacked, is accommodated; and a lead tab accommodation part which is positioned at one side of the electrode assembly accommodation part and in which a lead tab coupling part, in which an electrode tab formed on the electrode and an electrode lead extending to the outside are coupled to each other, is accommodated, wherein the lead tab accommodation part comprises a bump area in which the lead tab coupling part is positioned and which is formed protrudingly, and a flat area which is positioned at one side of the bump area along the width direction of the electrode assembly and has a height lower than the bump area; and the bump area has a shape corresponding to each other with reference to the electrode lead withdrawn to the outside.

Description

Battery case and secondary battery including the same

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2025-0003197 dated January 9, 2025 and Korean Patent Application No. 10-2026-0001423 dated January 5, 2026, and all contents disclosed in the documents of said Korean patent applications are incorporated herein as part of this specification.

[0002] The present invention relates to a battery case and a secondary battery including the same, and more specifically, to a pouch-type battery case and a pouch-type secondary battery that can increase energy density relative to volume and have high durability.

[0003] Recently, as the demand for portable electronic products such as laptops, video cameras, and mobile phones has increased rapidly, and the development of electric vehicles, energy storage batteries, robots, and satellites has accelerated, research on high-performance secondary batteries capable of repeated charging and discharging is actively underway.

[0004] Currently commercialized rechargeable batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium-ion batteries. Among these, lithium-ion batteries are gaining attention for their advantages, such as the ability to freely charge and discharge with almost no memory effect compared to nickel-based batteries, a very low self-discharge rate, and high energy density.

[0005] These lithium secondary batteries primarily use lithium-based oxides and carbon materials as the positive and negative active materials, respectively. Additionally, the lithium secondary battery comprises a positive plate and a negative plate coated with these positive and negative active materials, respectively; an electrode assembly in which the positive and negative plates are arranged with a separator in between; and an outer casing that seals and encloses the electrode assembly together with an electrolyte.

[0006] Meanwhile, lithium secondary batteries can be classified according to the shape of the battery case into can-type secondary batteries, in which the electrode assembly is embedded in a metal can, and pouch-type secondary batteries, in which the electrode assembly is embedded in a pouch of aluminum laminate sheets. Furthermore, can-type secondary batteries can be further classified into cylindrical batteries and prismatic batteries depending on the shape of the metal can.

[0007] A pouch, which is a case for a pouch-type secondary battery, is manufactured by performing press processing on a flexible pouch film to form a cup portion. Then, once the cup portion is formed, an electrode assembly is housed in the receiving space of the cup portion and the sides are sealed to manufacture a secondary battery.

[0008] In the cup portion of the pouch, the space excluding the area accommodating the electrode assembly is utilized for the connection of the electrode tab and electrode lead. However, since this space for the connection of the electrode tab and electrode lead is occupied by components other than the electrode assembly, it poses a problem that reduces the energy density of the secondary battery.

[0009] To solve the above problem, the objective of the present invention is to provide a battery case capable of increasing energy density per unit volume by reducing the space occupied by electrode tabs and electrode leads inside the pouch, and a secondary battery including the same.

[0010] Another objective of the present invention is to provide a battery case capable of preventing damage to the battery case by contact with an electrode tab and an electrode lead within a pouch, and a secondary battery including the same.

[0011] A battery case according to one aspect of the present invention comprises an electrode assembly receiving portion in which an electrode assembly, wherein an electrode and a separator are laminated and formed, is received, and a lead tab receiving portion located on one side of the electrode assembly receiving portion and in which an electrode tab formed on the electrode and an electrode lead extending outwardly are coupled, wherein the lead tab receiving portion includes a protruding bump region in which the lead tab connecting portion is located and a flat region located on one side of the bump region along the width direction of the electrode assembly and having a height smaller than that of the bump region, and wherein the bump region may have a shape corresponding to each other centered on the electrode lead extending outwardly.

[0012] The bump region may be symmetrical with respect to the electrode lead as the center in the thickness direction, which is the stacking direction of the electrode assembly intersecting the width direction.

[0013] In the bump region, the main outer surface parallel to the electrode and the separator and the main bump surface facing the end of the electrode assembly meet to form a first radius of curvature, and the extraction surface and the main bump surface meet to form a second radius of curvature, and the first radius of curvature may be equal to or greater than the second radius of curvature.

[0014] The first radius of curvature above may be 1 mm to 3 mm.

[0015] The above second radius of curvature may be 0.5 mm to 1.5 mm.

[0016] The angle formed by the main bump surface and the main outer surface may be 91 to 99 degrees.

[0017] In the above bump region, the main bump surface and the inclined bump surface extending to the flat region meet to form a third radius of curvature, the inclined bump surface and the flat region meet to form a fourth radius of curvature, and the third radius of curvature may be equal to the fourth radius of curvature.

[0018] The third radius of curvature and the fourth radius of curvature may be 2 mm to 5 mm.

[0019] Along the width direction, the distance between the inclined bump surface and the flat area may be 3 mm to 8 mm.

[0020] The height of the bump area may be 4 mm to 6 mm.

[0021] The height of the flat area above may be 2 mm to 3 mm.

[0022] A secondary battery according to one aspect of the present invention comprises an electrode assembly in which an electrode and a separator are laminated and formed, an electrode tab formed on one side of the electrode, an electrode lead coupled to the electrode tab and extending outwardly, an electrode assembly receiving portion in which the electrode assembly is received, and a battery case including a lead tab receiving portion located on one side of the electrode assembly receiving portion and in which a lead tab coupling portion, to which the electrode tab and the electrode lead are coupled, is received. The lead tab receiving portion includes a protruding bump region where the lead tab coupling portion is located and a flat region located on one side of the bump region along the width direction of the electrode assembly and having a height smaller than that of the bump region, and the bump region may have a shape corresponding to each other centered on the electrode lead that is drawn out outward.

[0023] The bump region may be symmetrical with respect to the electrode lead in the thickness direction, which is the stacking direction of the electrode assembly intersecting the width direction.

[0024] In the bump region, the main outer surface parallel to the electrode and the separator and the main bump surface facing the end of the electrode assembly meet to form a first radius of curvature, and the lead surface parallel to the electrode lead and the main bump surface meet to form a second radius of curvature, and the first radius of curvature may be equal to or greater than the second radius of curvature.

[0025] The first radius of curvature above may be 1 mm to 3 mm.

[0026] The above second radius of curvature may be 0.5 mm to 1.5 mm.

[0027] The angle formed by the bump surface and the main outer surface may be 91 to 99 degrees.

[0028] In the above bump region, the main bump surface and the inclined bump surface extending to the flat region meet to form a third radius of curvature, the inclined bump surface and the flat region meet to form a fourth radius of curvature, and the third radius of curvature may be equal to the fourth radius of curvature.

[0029] The third radius of curvature and the fourth radius of curvature may be 2 mm to 5 mm.

[0030] Along the width direction, the distance between the inclined bump surface and the flat area may be 3 mm to 8 mm.

[0031] The height of the bump area may be 4 mm to 6 mm.

[0032] The height of the flat area above may be 2 mm to 3 mm.

[0033] In the lead tab coupling portion above, the electrode tab and the electrode lead can be bent and coupled to each other.

[0034] The lead tab coupling portion may face the end of the electrode assembly.

[0035] The electrode lead may be located at the center of the electrode assembly along the thickness direction of the electrode assembly, which is the stacking direction of the electrode.

[0036] The bump area may be located at the center of the battery case along the width direction of the electrode assembly.

[0037] The lead tab receiving portion may be formed at each of the two ends of the receiving portion of the electrode assembly.

[0038] The above battery case may be a pouch type.

[0039] As described above, according to one aspect of the present invention, the energy density per unit volume can be increased by reducing the space occupied by the electrode tab and electrode lead inside the pouch.

[0040] In addition, according to one aspect of the present invention, damage to the battery case caused by contact between the electrode tab and the electrode lead within the pouch can be prevented.

[0041] FIG. 1 is an assembly diagram of a secondary battery according to one embodiment of the present invention.

[0042] FIG. 2 is a perspective view illustrating a secondary battery according to one embodiment of the present invention.

[0043] FIG. 3 is a side view showing a battery case according to one embodiment of the present invention in a folded state.

[0044] Figure 4 is an assembly diagram of a modified example of the secondary battery of Figure 1.

[0045] FIG. 5 is a drawing illustrating the process of folding a battery case according to one embodiment of the present invention.

[0046] FIG. 6 is a drawing showing a battery case in a folded state according to one embodiment of the present invention.

[0047] FIGS. 7 and 8 are drawings illustrating a lead tab coupling portion disposed within a lead tab receiving portion of a secondary battery according to an embodiment of the present invention.

[0048] FIG. 9 is a diagram illustrating the state in which an electrode tab and an electrode lead of a secondary battery are combined according to one embodiment of the present invention.

[0049] FIGS. 10 and FIGS. 11 are enlarged views illustrating a lead tab receiving portion of a secondary battery according to one embodiment of the present invention.

[0050] Figure 12 is a cross-sectional view taken along line AA of Figure 11.

[0051] Figure 13 is a cross-sectional view taken along line BB of Figure 11.

[0052] FIG. 14 is a drawing showing a molding apparatus for molding a battery case according to one embodiment of the present invention.

[0053] FIG. 15 is an enlarged plan view of a lead tab receiving portion of a secondary battery according to one embodiment of the present invention.

[0054] Figure 16 is an enlarged view of the bump area and flat area of ​​Figure 15.

[0055] FIG. 17 is a drawing showing the state in which the third radius of curvature and the fourth radius of curvature of FIG. 16 are identical to each other.

[0056] FIG. 18 is a diagram illustrating a state where the third radius of curvature and the fourth radius of curvature of FIG. 16 are different from each other.

[0057] FIGS. 19 and 20 are drawings illustrating the process of an electrode lead and an electrode tab of a secondary battery being bent and joined together according to an embodiment of the present invention.

[0058] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0059] The terms used in this invention are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this invention, terms such as "comprising" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0060] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that in the accompanying drawings, identical components are indicated by the same reference numerals whenever possible. Furthermore, detailed descriptions of known functions and configurations that may obscure the essence of the present invention will be omitted. For the same reason, some components in the accompanying drawings may be exaggerated, omitted, or schematically depicted.

[0061]

[0062] Hereinafter, a secondary battery according to one embodiment of the present invention will be described.

[0063] FIG. 1 is an assembly drawing of a secondary battery according to an embodiment of the present invention, and FIG. 2 is a perspective view illustrating a secondary battery according to an embodiment of the present invention. FIG. 3 is a side view showing a battery case folded according to an embodiment of the present invention, and FIG. 4 is an assembly drawing of a modified example of the secondary battery of FIG. 1. FIG. 5 is a drawing illustrating the process of folding a battery case according to an embodiment of the present invention, and FIG. 6 is a drawing showing the state in which the battery case according to an embodiment of the present invention is folded.

[0064] Referring to FIGS. 1 to 3, a secondary battery (10) according to one embodiment of the present invention includes a battery case (300) comprising a first case (310) and a second case (330), and an electrode assembly (100) in which a separator (115) is interposed between a first electrode (110) and a second electrode (130).

[0065] In an electrode assembly (100), a separator (115) may be formed between a first electrode (110) and a second electrode (130) that are alternately arranged. That is, the separator (115) may be positioned between the first electrode (110) and the second electrode (130), and the electrode assembly (100) may be formed by alternately stacking the first electrode (110), the separator (115), the second electrode (130), the separator (115)... in that order. Here, the first electrode (110) and the second electrode (130) may be electrodes of different polarities, respectively, and may be a positive electrode and a negative electrode.

[0066] The first electrode (110) and the second electrode (130) may include an electrode active portion (111, 131), which is an area where an active material is applied to a thin plate formed of a metal foil, and an electrode tab (112, 132), which is an area where an active material is not applied.

[0067] The first electrode active part (111) may have an active material such as a transition metal oxide coated on a metal foil such as aluminum, and the second electrode active part (131) may have an active material such as graphite or carbon coated on a metal foil such as copper or nickel.

[0068] The first electrode tab (112) may protrude to one side of the first electrode active portion (111), and the second electrode tab (132) may protrude to one side of the second electrode active portion (131). In this embodiment, the first electrode tab (112) and the second electrode tab (132) may protrude in different directions, that is, at each end of the electrode assembly (100). In this embodiment, the first electrode tab (112) and the second electrode tab (132) are described as protruding in different directions, but are not necessarily limited thereto, and the first electrode tab (112) and the second electrode tab (132) may protrude in the same direction (see FIG. 4).

[0069] The first electrode tab (112) and the second electrode tab (132) are formed by cutting so as to protrude from the metal foil, and can be formed integrally with the metal foil of the first electrode active part (111) and the second electrode active part (131). In this embodiment, the first electrode tab (112) and the second electrode tab (132) are described as being formed integrally with the first electrode active part (111) and the second electrode active part (131), but are not necessarily limited thereto and may be formed by connecting a separate conductive member to the first electrode active part (111) and the second electrode active part (131) respectively using ultrasonic welding or the like.

[0070] Each of the first electrode tab (112) and the second electrode tab (132) is formed by overlapping a plurality of thin films, and can be connected so that the thin films come into contact with each other using ultrasonic welding, laser welding, etc., to facilitate the movement of current.

[0071] The separator (115) is positioned between the first electrode (110) and the second electrode (130), more specifically between the first electrode active portion (111) and the second electrode active portion (131), to prevent short circuits between them and to enable the movement of ions. For example, the separator (115) may be made of various materials such as polyethylene, polypropylene, or a composite film thereof.

[0072] In this embodiment, the electrode assembly (100) may be formed by winding the first electrode (110), the separator (115), and the second electrode (130) (wound type), or by overlapping the first electrode (110), the separator (115), and the second electrode (130) in parallel with each other (stack type, stack and folding type).

[0073] An electrode lead (150) that supplies electricity to the outside of the secondary battery (10) is connected to the electrode tabs (112, 132) of the electrode assembly (100) by spot welding or the like. Specifically, a first electrode lead (151) is connected to the first electrode tab (112) and extends outward, and a second electrode lead (153) is connected to the second electrode tab (132) and extends outward.

[0074] A portion of the electrode lead (150) is wrapped by an insulating portion (170). The insulating portion (170) is located at the side (314) where the first case (310) and the second case (330) are heat-fused, thereby adhering the electrode lead (150) to the battery case (300). By doing so, the insulating portion (170) prevents electricity generated from the electrode assembly (100) from flowing through the electrode lead (150) to the battery case (300) and can maintain the sealing of the battery case (300). The insulating portion (170) mainly uses insulating tape that is easy to attach to the electrode lead (150) and has a relatively thin thickness, but is not limited to this and can use various materials capable of insulating the electrode lead (150).

[0075] One end of the electrode lead (150) is connected to the electrode tab (112, 132), and the other end extends to the outside of the battery case (300). Specifically, the electrode lead (150) includes a first electrode lead (151) and a second electrode lead (153), and one end of the first electrode lead (151) is connected to the first electrode tab (112), which is the positive electrode, and the other end extends to the outside of the battery case (300) in the direction in which the first electrode tab (112) protrudes. One end of the second electrode lead (153) is connected to the second electrode tab (132), which is the negative electrode, and the other end extends to the outside of the battery case (300) in the direction in which the second electrode tab (132) protrudes.

[0076] Meanwhile, as shown in FIGS. 1 and 2, the first electrode lead (151) and the second electrode lead (153) may be extended in different directions, and as shown in FIG. 4, the first electrode lead (151) and the second electrode lead (153) may be extended in the same direction.

[0077] The first electrode lead (151) and the second electrode lead (153) may have different materials. That is, the first electrode lead (151) may be made of the same aluminum material as the first electrode (110), which is the positive electrode, and the second electrode lead (153) may be made of the same copper material as the second electrode (130), which is the negative electrode, or nickel-coated copper material. Additionally, a portion of the electrode leads (151, 153) that extend outside the battery case (300) may be electrically connected to an external terminal.

[0078] The battery case (300) is a pouch manufactured by forming a pouch film having a flexible material that accommodates an electrode assembly (100) inside. In the following description, the battery case (300) is described as a pouch. When a flexible pouch film (P) is drawn using a punch (510, see FIG. 14) and a die (530, see FIG. 14), a portion is stretched to form an electrode assembly receiving portion (340) and a lead tab receiving portion (350) that include a pocket-shaped receiving space, thereby manufacturing the battery case (300). In this embodiment, the electrode assembly receiving portion (340) and the lead tab receiving portion (350) form a single receiving space connected to each other.

[0079] The battery case (300) accommodates and seals the electrode assembly (100) so that a portion of the electrode lead (150) is exposed to the outside. As illustrated in FIG. 1, the battery case (300) includes a first case (310) and a second case (330). The first case (310) has an electrode assembly receiving portion (340) and a lead tab receiving portion (350) formed therein to provide a receiving space capable of accommodating the electrode assembly (100). The second case (330) is formed in the same way as the first case (310) and covers the electrode assembly receiving portion (340) and the lead tab receiving portion (350) so that the electrode assembly (100) does not escape from the outside of the battery case (300). As illustrated in FIG. 1, the first case (310) and the second case (330) may be manufactured with one side connected to the other, but are not limited thereto and may be manufactured in various ways, such as being separated from each other and manufactured separately.

[0080] When forming an electrode assembly receiving portion (340) and a lead tab receiving portion (350) on a pouch film (P), only one electrode assembly receiving portion (340) and a lead tab receiving portion (350) may be formed on a single pouch film, but is not limited thereto, and two electrode assembly receiving portions (340) and lead tab receiving portions (350) may be formed adjacent to each other on a single pouch film. As shown in FIG. 1, an electrode assembly receiving portion (340) and a lead tab receiving portion (350) are formed on the first case (310) and the second case (330), respectively. At this time, the electrode assembly receiving portion (340) and the lead tab receiving portion (350) formed on the first case (310) and the second case (330) may have the same depth, but are not limited thereto, and may have different depths.

[0081] In this embodiment, the depth of the electrode assembly receiving portion (340) and the lead tab receiving portion (350) may be 7 mm to 15 mm. Accordingly, the electrode assembly receiving portion (340) and the lead tab receiving portion (350) of this embodiment can accommodate an electrode assembly (100) having a large electrode capacity compared to a typical small battery.

[0082] Referring to FIGS. 5 and 6, after the electrode assembly (100) and the lead tab coupling part (190) are received in the electrode assembly receiving part (340) formed in the first case (310), the second case (330) can be folded around the bridge (361) so that the two electrode assembly receiving parts (340) face each other. By doing so, the electrode assembly receiving part (340) of the second case (330) can receive the electrode assembly (100) from above. Therefore, since the electrode assembly receiving parts (340) facing each other receive one electrode assembly (100), the electrode assembly (100) with a thicker thickness than when there is only one electrode assembly receiving part (340) can be received. In addition, since the first case (310) and the second case (330) are connected integrally with each other around the bridge (361), the number of sides (314) to be sealed can be reduced when performing the sealing process later. Therefore, the process speed can be improved and the number of sealing processes can be reduced.

[0083] Meanwhile, the battery case (300) may include a degassing section (315) formed on the side of the electrode assembly receiving section (340) that accommodates the electrode assembly (100) and discharges gas generated inside the electrode assembly receiving section (340) through a degassing hole (not shown). After housing the electrode assembly (100) in the electrode assembly receiving section (340) of the battery case (300) and injecting an electrolyte, an activation process is performed, and gas is generated inside the battery case (300), and a degassing process is performed to discharge this gas to the outside through the degassing section (315).

[0084] When the degassing process is completed, the degassing portion (315) protruding to the side is removed, and the remaining side (314) is folded at least once and fixed to the side of the battery case (300) with tape (T) (see FIG. 3).

[0085]

[0086] FIGS. 7 and 8 are drawings illustrating a lead tab coupling portion disposed within a lead tab receiving portion of a secondary battery according to one embodiment of the present invention, and FIG. 9 is a drawing illustrating a state in which an electrode tab and an electrode lead of a secondary battery are coupled according to one embodiment of the present invention.

[0087] Referring to FIGS. 7 to 9, according to the present embodiment, a lead tab coupling portion (190) in which electrode tabs (112, 132) and electrode leads (150) are bent and joined together is disposed within a lead tab receiving portion (350). At this time, the lead tab coupling portion (190) may be disposed to face the end of the electrode assembly (100).

[0088] A plurality of first electrode tabs (112) protrude from the electrode assembly (100) toward the lead tab receiving portion (350). By doing so, a plurality of first electrode tabs (112) are located within the lead tab receiving portion (350). Here, the first electrode tabs (112) and the first electrode lead (151) are described as examples, and since the combined structure of the overlapping second electrode tabs (132) and second electrode leads (153) is identical, a description thereof is omitted.

[0089] A plurality of first electrode tabs (112) extend from the electrode assembly (100), and the ends of the first electrode tabs (112) can be joined together to form a first tab connecting portion (112a). At this time, the first tab connecting portion (112a) can be formed by joining the ends of a plurality of first electrode tabs (112) together by welding or the like.

[0090] The first tab connecting portion (112a) may be bent to face the end of the electrode assembly (100). Specifically, one side of the first tab connecting portion (112a) may be bent so that it is parallel to the end surface of the electrode assembly (100). At this time, being bent to face may include not only the one side of the first tab connecting portion (112a) being positioned parallel to the end surface of the electrode assembly (100), but also the one side of the first tab connecting portion (112a) and the end surface facing each other while positioned obliquely.

[0091] At this time, the first tab connecting portion (112a) is formed by welding the ends of the first electrode tab (112) together before or after bending so as to face the end of the electrode assembly (100).

[0092] The first electrode lead (151) includes a first lead extension portion (151b) extending to the outside of the battery case (300) and a first lead connection portion (151a), and the first lead connection portion (151a) is formed by bending relative to the first lead extension portion (151b). Specifically, the first lead connection portion (151a) may be bent at an angle of approximately 90 degrees relative to the first lead extension portion (151b). However, the angle formed by the first lead connection portion (151a) and the first lead extension portion (151b) is not limited to this and may be approximately 86 to 94 degrees.

[0093] The first lead connection part (151a) is coupled with the first tab connection part (112a), which is bent to face the electrode assembly (100). At this time, the first lead connection part (151a) and the first tab connection part (112a) can make surface contact with each other. The first lead connection part (151a) and the first tab connection part (112a) can be joined to each other by welding or the like.

[0094] The first lead connection portion (151a) is joined with the first tab connection portion (112a) to form a lead tab coupling portion (190), and the lead tab coupling portion (190) is located within the lead tab receiving portion (350) inside the battery case (300).

[0095] The first lead extension (151b) is oriented perpendicular to the end surface of the electrode assembly (100), that is, in the longitudinal direction (x-direction) of the electrode assembly (100). In other words, the first lead extension (151b) can extend outward from the battery case (300) along the longitudinal direction (x-direction) of the electrode assembly (100). At this time, the first lead extension (151b) can be positioned at the center of the thickness direction (z-direction) of the electrode assembly (100). Accordingly, the first electrode lead (151) can extend outward from the battery case (300) at the center of the thickness direction (z-direction) of the electrode assembly (100).

[0096] According to the present embodiment, the lead tab coupling portion (190) is bent and arranged parallel to the end of the electrode assembly (100), thereby reducing the space of the lead tab receiving portion (350) that accommodates the lead tab coupling portion (190). Conventionally, the lead tab coupling portion (190) was not bent parallel to the end of the electrode assembly (100) but was arranged parallel to the length direction (x direction) of the electrode assembly (100). That is, conventionally, the lead tab coupling portion (190) is arranged perpendicular to the end surface of the electrode assembly (100), and accordingly, the lead tab receiving portion (350) that accommodates the lead tab coupling portion (190) becomes larger. In contrast, in the present embodiment, as the lead tab coupling portion (190) is arranged in a bent state, the lead tab receiving portion (350) becomes smaller and unnecessary space within the battery case (300) can be reduced, thereby increasing the energy density of the secondary battery.

[0097]

[0098] FIGS. 10 and FIGS. 11 are enlarged views illustrating a lead tab receiving portion of a secondary battery according to an embodiment of the present invention, FIG. 12 is a cross-sectional view taken along line AA of FIG. 11, and FIG. 13 is a cross-sectional view taken along line BB of FIG. 11.

[0099] Referring to FIGS. 10 to 13, according to the present embodiment, the lead tab receiving portion (350) of the battery case (300) may include a protruding bump area (BA) and a flat area (FA) having a height smaller than that of the bump area (BA).

[0100] The bump area (BA) is located in the center of the lead tab receiving portion (350), and flat areas (FA) may be located on each side of the bump area (BA). The bump area (BA) and the flat area (FA) may be arranged along the width direction (y direction) of the electrode assembly.

[0101] A lead tab coupling portion (190) is located inside the bump area (BA), and a lead tab coupling portion (190) is not located inside the flat area (FA). As a result, the height (H2) of the flat area (FA) is lower than the height (H1) of the bump area (BA). That is, in the lead tab receiving portion (350), the heights of the area where the lead tab coupling portion (190) is located and the area where it is not located can be formed differently. Due to the structure of the lead tab coupling portion (190) described above, the size of the lead tab receiving portion (350) can be reduced compared to the conventional method, and additionally, the size of the flat area (FA) where the lead tab coupling portion (190) is not located can be further reduced. As a result, the overall size of the lead tab receiving portion (350) can be further reduced.

[0102] At this time, the height (H1) of the bump region (BA) may be 4 mm to 6 mm, and the height (H2) of the flat region (FA) may be 2 mm to 3 mm. The height (H1) of the bump region (BA) may be about 1.33 to 3 times larger than the height (H2) of the flat region (FA). Here, the heights of the bump region (BA) and the flat region (FA) represent the distance between the end surface of the electrode assembly (100) and the upper surface of the bump region (BA) and the flat region (FA).

[0103] In the lead tab receiving portion (350), the flat area (FA) may have a roughly flat flat surface (377), and the bump area (BA) may have an inclined bump surface (373) and a roughly flat main bump surface (371). Specifically, in the lead tab receiving portion (350), the flat surface (377), the inclined bump surface (373), the main bump surface (371), the inclined bump surface (373), and the flat surface (377) are arranged in order along the width direction (y direction) of the electrode assembly (100). That is, the lead tab receiving portion (350) may have a shape in which the center protrudes more than the periphery.

[0104] As illustrated in FIG. 12, the bump region (BA) may have corresponding shapes centered on the electrode lead (150) that is drawn out externally. Here, the corresponding shapes may include not only perfect mirror symmetry but also interlocking or similar structures on both sides. For example, in the bump region (BA), the lead tab receiving portion (350) in the first case (310) located at the bottom of the battery case (300) and the lead tab receiving portion (350) in the second case (330) located at the top of the battery case (300) may be symmetrical or substantially symmetrical with respect to the electrode lead (150). That is, in the bump region (BA), the lead tab receiving portion (350) where the bent lead tab receiving portion (350) is located and the lead tab receiving portion (350) where the lead tab receiving portion (350) is not located may be symmetrical with respect to the electrode lead (150). As used in this specification, the terms 'symmetry' or 'substantially symmetric' should be interpreted to include not only perfect geometric symmetry but also manufacturing errors, assembly tolerances, or minor design variations.

[0105] In the bump region (BA), the punch edge (371a) where the main outer surface (311) and the main bump surface (371) meet can be formed rounded with a first radius of curvature (R1). Here, the main outer surface (311) represents the outer surface of the battery case (300) parallel to the electrode (110, 130) and separator (115) of the electrode assembly (100), and the main bump surface (371, see FIG. 10, 12) represents the surface facing the end surface of the electrode assembly (100). Additionally, when a pouch film (P) is pressed into a molding space (561) formed in a die (530) by a punch (510) of a molding device (500, see FIG. 14), an electrode assembly receiving portion (340) is formed in a battery case (300), and the edge of the electrode assembly receiving portion (340) formed in correspondence with the shape of the punch edge (511) is the punch edge (371a).

[0106] The first radius of curvature (R1) may be 1 mm to 3 mm. As the first radius of curvature (R1) increases, the height (H1) becomes smaller, increasing the likelihood of contact between the main bump surface (371) and the lead tab coupling part (190), which may cause damage to the battery case (300) or the lead tab coupling part (190). Meanwhile, as the first radius of curvature (R1) decreases, the angle of the punch edge (371a) becomes 90 degrees or close to 90 degrees, and cracks may occur in the punch edge (371a) portion during or after the forming process. Therefore, if the first radius of curvature (R1) is within the above range, the aforementioned damage or cracks can be prevented.

[0107] The die edge (379a) where the extraction surface (379) and the main bump surface (371) meet can be formed rounded with a second radius of curvature (R2). Here, the extraction surface (379) is located on the terrace portion (317) formed by the sides (314) of the battery case (300) being in close contact with each other, and represents a surface that directly faces the electrode lead (150) extending outward. Additionally, when the pouch film (P) is pressed into the molding space (561) formed in the die (530) by the punch (510) of the molding device (500, see FIG. 14), an electrode assembly receiving portion (340) is formed in the battery case (300), and the edge of the electrode assembly receiving portion (340) formed corresponding to the shape of the die edge (531) is the die edge (379a).

[0108] The second radius of curvature (R2) may be 0.5 mm to 1.5 mm. As the second radius of curvature (R2) increases, the likelihood of contact between the main bump surface (371) and the lead tab coupling portion (190) increases, which may cause damage to the battery case (300) or the lead tab coupling portion (190). As the second radius of curvature (R2) decreases, the height (H1) increases, the lead tab receiving portion (350) increases, and the energy density of the secondary battery may decrease. Therefore, if the second radius of curvature (R2) is within the above range, the aforementioned damage or decrease in energy density can be prevented.

[0109] Meanwhile, the first radius of curvature (R1) may be equal to or greater than the second radius of curvature (R2). The radius of curvature (R1) of the punch edge (371a) may be formed to be equal to or greater than the radius of curvature (R2) of the die edge (379a). By doing so, the shape may have a gentler curved surface on the punch edge (371a) side than on the die edge (379a) side.

[0110] Additionally, the angle (AG) formed by the main bump surface (371) and the main outer surface (311) may be 91 to 99 degrees. As the angle (AG) increases, the size of the lead tab receiving portion (350) increases, and the energy density decreases; as the angle (AG) decreases, the punch edge (371a) approaches 90 degrees, and cracks may occur during or after the molding process. Therefore, if the angle (AG) is within the above range, the aforementioned damage or decrease in energy density can be prevented.

[0111] In this embodiment, the bump region (BA) is formed symmetrically around the electrode lead (150), and the electrode lead (150) is located at the center of the thickness direction (z direction) of the electrode assembly (100). Accordingly, the lead tab coupling portion (190) is bent and positioned to face the end surface of the electrode assembly (100), so that the extension portion (151b) of the electrode lead (150) can extend outward from the center of the electrode assembly (100). That is, the extension portion (151b) of the electrode lead (150) is located in the center of the electrode assembly (100).

[0112] As illustrated in FIG. 13, the flat area (FA) is a space within the lead tab receiving portion (350) where the lead tab coupling portion (190) is not located, and the height (H2) of the flat area (FA) can be formed to be smaller than the height (H1) of the bump area (BA). The flat area (FA) can be symmetrical with respect to the terrace portion (317) in the same way as the bump area (BA).

[0113]

[0114] FIG. 15 is an enlarged plan view of a lead tab receiving portion of a secondary battery according to an embodiment of the present invention, and FIG. 16 is an enlarged view of the bump area and flat area of ​​FIG. 15. FIG. 17 is a view showing the state in which the third radius of curvature and the fourth radius of curvature of FIG. 16 are the same as each other, and FIG. 18 is a view showing the state in which the third radius of curvature and the fourth radius of curvature of FIG. 16 are different from each other.

[0115] Referring to FIGS. 15 to 17, the edge where the main bump surface (371) and the inclined bump surface (373) meet in the bump region (BA) can be formed rounded with a third radius of curvature (R3). Here, the inclined bump surface (373) is an inclined surface connecting the main bump surface (371) and the flat surface (377) of the flat region (FA).

[0116] At the edge where the inclined bump surface (373) and the flat surface (377) meet, it can be formed rounded with a fourth radius of curvature (R4).

[0117] The third radius of curvature (R3) and the fourth radius of curvature (R4) may be the same. That is, the main bump surface (371) and the flat surface (377) are connected to the inclined pump surface (373), and at each edge meeting the inclined pump surface (373), they may have a rounded shape with the same radius of curvature.

[0118] In this embodiment, the third radius of curvature (R3) and the fourth radius of curvature (R4) may be 2 mm to 5 mm. If the third radius of curvature (R3) and the fourth radius of curvature (R4) are too small, cracks may occur at the edge, and if the third radius of curvature (R3) and the fourth radius of curvature (R4) are too large, there is no difference in height between the bump area (BA) and the flat area (FA), so the flat area (FA) becomes larger and the energy density may decrease.

[0119] At this time, the separation distance (W) in the width direction (y direction) between the inclined bump surface (373) and the flat surface (377) may be 3 mm to 8 mm. As described above, in the same state as the third radius of curvature (R3) and the fourth radius of curvature (R4), if the separation distance (W) is too small, cracks may occur at the edge, and if the separation distance (W) is large, there is no difference in height between the bump area (BA) and the flat area (FA), so the energy density may decrease.

[0120] In this embodiment, the third radius of curvature (R3) and the fourth radius of curvature (R4) are described as being the same, but as shown in FIG. 18, the third radius of curvature (R3) and the fourth radius of curvature (R4) may be formed differently. For example, the third radius of curvature (R3) may be formed to be smaller than the fourth radius of curvature (R4). By doing so, under conditions where the length of the inclined bump surface (373) is the same as in FIG. 17, the target height difference between the bump area (BA) and the flat area (FA) can be maintained without the need to increase the length in the width direction (y direction) of the battery case (300).

[0121]

[0122] FIGS. 19 and 20 are drawings illustrating the process of an electrode lead and an electrode tab of a secondary battery being bent and joined together according to an embodiment of the present invention.

[0123] With reference to FIGS. 19 and 20, the process of bending the first electrode tab (112) and the first electrode lead (151) together in this embodiment so that the lead tab coupling portion (190) is positioned parallel to the end surface of the electrode assembly (100) is described. Additionally, the process of the first lead extension portion (151b) extending outward from the center of the electrode assembly (100) is described together.

[0124] Referring to FIG. 19, the ends of a plurality of first electrode tabs (112) extending from the electrode assembly (100) are joined together to form a first tab connecting portion (112a). The first tab connecting portion (112a) is arranged parallel to the length direction (x direction), which is the extension direction of the electrode assembly (100).

[0125] At this time, the first tab connecting portion (112a), to which a plurality of first electrode tabs (112) are combined, is positioned offset to one side from the center of the thickness direction (z direction) of the electrode assembly (100). The position of the first tab connecting portion (112a) is positioned closer to the upper surface of the electrode assembly (100). Specifically, the distance (L1) from the upper surface of the electrode assembly (100) to the first tab connecting portion (112a) is positioned to be smaller than the distance (L2) from the lower surface of the electrode assembly (100) to the first tab connecting portion (112a). Here, the upper surface of the electrode assembly (100) represents the upper part of the electrode assembly (100) exposed as seen in FIGS. 19 and FIGS. 20, and the lower surface of the electrode assembly (100) represents the hidden lower part opposite to the upper surface of the electrode assembly (100).

[0126] Afterward, the first lead connection portion (151a) of the bent first electrode lead (151) is brought into surface contact with the first tab connection portion (112a). At this time, the first lead extension portion (151b) is positioned parallel to the end surface of the electrode assembly (100).

[0127] The first lead connection part (151a) and the first tab connection part (112a) can be joined together by welding or the like. The first lead connection part (151a) and the first tab connection part (112a) are joined together to form a lead tab joint part (190). At this time, the end of the first lead connection part (151a) and the end of the first tab connection part (112a) are joined so that they face the same direction. The ends of the first lead connection part (151a) and the first tab connection part (112a) face the outside of the electrode assembly (100) along the longitudinal direction (x-direction).

[0128] Referring to FIG. 20, the lead tab coupling portion (190) is then bent approximately 90 degrees toward the lower surface of the electrode assembly (100) so that the lead tab coupling portion (190) is positioned parallel to the end surface of the electrode assembly (100). As a result, the first lead extension portion (151b), which was parallel to the end surface of the electrode assembly (100), is rotated 90 degrees so that the first lead extension portion (151b) faces the outside of the electrode assembly (100).

[0129] At this time, the first lead extension (151b) is positioned at the center of the electrode assembly (100). That is, after rotation, the distance between the first lead extension (151b) and the upper and lower surfaces of the electrode assembly (100) becomes equal to L3. This is because when the first tab connection (112a), which is joined with a plurality of first electrode tabs (112) overlapping, has a constant thickness and is positioned closer to the upper surface of the electrode assembly (100), and is rotated in the aforementioned direction, the first electrode lead (151) in surface contact with the first tab connection (112a) is positioned at the center of the electrode assembly (100).

[0130] Although an embodiment of the present invention has been described above, those skilled in the art may modify and change the present invention in various ways by adding, changing, deleting, or adding components, etc., without departing from the spirit of the present invention as described in the claims, and such modifications and changes are also to be included within the scope of the rights of the present invention.

Claims

1. A battery case comprising: an electrode assembly receiving portion for receiving an electrode assembly in which an electrode and a separator are laminated and formed; and a lead tab receiving portion located on one side of the electrode assembly receiving portion, wherein a lead tab coupling portion is received for which an electrode tab formed on the electrode and an electrode lead extending outwardly are coupled. The above lead tab receiving portion is, The above lead tab coupling part is located, and a protruding bump area and It includes a flat region located on one side of the bump region along the width direction of the electrode assembly and having a height smaller than that of the bump region, A battery case having a bump area having a shape corresponding to each other centered on an electrode lead drawn out to the outside.

2. In Paragraph 1, The above bump area is, A battery case that is symmetrical with respect to each other with respect to the electrode leads in the thickness direction, which is the stacking direction of the electrode assembly intersecting the width direction.

3. In Paragraph 2, In the above bump area, A main outer surface parallel to the electrode and the separator and a main bump surface facing the end of the electrode assembly meet to form a first radius of curvature, The above extraction surface and the above main bump surface meet to form a second radius of curvature, and A battery case in which the first radius of curvature is equal to or greater than the second radius of curvature.

4. In Paragraph 3, A battery case having a first radius of curvature of 1 mm to 3 mm.

5. In Paragraph 3, A battery case having a second radius of curvature of 0.5 mm to 1.5 mm.

6. In Paragraph 3, A battery case in which the angle formed by the main bump surface and the main outer surface is 91 to 99 degrees.

7. In Paragraph 3, In the above bump area, The above main bump surface and the inclined bump surface extending to the above flat area meet to form a third radius of curvature, and The above inclined bump surface and the above flat area meet to form a fourth radius of curvature, and A battery case in which the third radius of curvature is the same as the fourth radius of curvature.

8. In Paragraph 7, A battery case in which the third radius of curvature and the fourth radius of curvature are 2 mm to 5 mm.

9. In Paragraph 8, A battery case in which, along the width direction, the distance between the inclined bump surface and the flat area is 3 mm to 8 mm.

10. In Paragraph 1, A battery case having a bump area height of 4 mm to 6 mm.

11. In Paragraph 1, A battery case having a flat area with a height of 2 mm to 3 mm.

12. Electrode assembly in which electrodes and separators are laminated: An electrode tab formed on one side of the above electrode; An electrode lead that is coupled to the above electrode tab and extends outward, and A battery case comprising an electrode assembly receiving portion for receiving the electrode assembly and a lead tab receiving portion located on one side of the electrode assembly receiving portion for receiving a lead tab coupling portion for coupling the electrode tab and the electrode lead, wherein the electrode tab and the electrode lead are coupled, The above lead tab receiving portion is, The above lead tab coupling part is located, and a protruding bump area and It includes a flat region located on one side of the bump region along the width direction of the electrode assembly and having a height smaller than that of the bump region, A secondary battery in which the above bump regions have mutually corresponding shapes centered on the electrode leads drawn out to the outside.

13. In Paragraph 12, The above bump area is, A battery case that is symmetrical with respect to each other with respect to the electrode leads in the thickness direction, which is the stacking direction of the electrode assembly intersecting the width direction.

14. In Paragraph 13, In the above bump area, A main outer surface parallel to the electrode and the separator and a main bump surface facing the end of the electrode assembly meet to form a first radius of curvature, The lead surface parallel to the electrode lead and the main bump surface meet to form a second radius of curvature, and A secondary battery in which the first radius of curvature is equal to or greater than the second radius of curvature.

15. In Paragraph 14, A secondary battery having a first radius of curvature of 1 mm to 3 mm.

16. In Paragraph 14, A secondary battery having a second radius of curvature of 0.5 mm to 1.5 mm.

17. In Paragraph 14, A secondary battery in which the angle formed by the bump surface and the main outer surface is 91 to 99 degrees.

18. In Paragraph 14, In the above bump area, The above main bump surface and the inclined bump surface extending to the above flat area meet to form a third radius of curvature, and The above inclined bump surface and the above flat area meet to form a fourth radius of curvature, and A secondary battery in which the third radius of curvature is the same as the fourth radius of curvature.

19. In Paragraph 18, A secondary battery in which the third radius of curvature and the fourth radius of curvature are 2 mm to 5 mm.

20. In Paragraph 19, A secondary battery, wherein the distance between the inclined bump surface and the flat area along the width direction is 3 mm to 8 mm.

21. In Paragraph 12, A secondary battery having a bump area height of 4 mm to 6 mm.

22. In Paragraph 12, A secondary battery having a flat area of ​​2 mm to 3 mm in height.

23. In Paragraph 12, In the lead tab coupling portion above, the electrode tab and the electrode lead are bent and coupled to each other, and the secondary battery.

24. In Paragraph 23, The above lead tab coupling portion faces the end of the electrode assembly, a secondary battery.

25. In Paragraph 23, A secondary battery in which the electrode lead is located at the center of the electrode assembly along the thickness direction of the electrode assembly, which is the stacking direction of the electrode.

26. In Paragraph 12, The above bump area is located in the center of the battery case along the width direction of the electrode assembly, a secondary battery.

27. In Paragraph 12, A secondary battery in which the lead tab receiving portion is formed at each of the two ends of the receiving portion of the electrode assembly.

28. In Paragraph 12, The above battery case is a pouch-type secondary battery.

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