Pouch type battery case and secondary battery including the same

Abstract

A pouch-type battery case according to an embodiment of the present invention may include a pair of cup portions; a sealing portion located around the perimeter of the cup portions; and a side folding portion formed by folding a portion of the sealing portions. The side folding portion may include a first folding portion folded in a rotational direction; and a connecting portion connecting the cup portions and the first folding portion, and inclined in a rotational direction opposite to the rotational direction with respect to the cup portions.

Description

Technology Field

[0001] The present invention relates to a pouch-type battery case accommodating an electrode assembly and a secondary battery including the same. Background Technology

[0002] As technological development and demand for mobile devices, electric vehicles, hybrid vehicles, power storage devices, and uninterruptible power supplies increase, the demand for secondary batteries as an energy source is rapidly rising, and accordingly, much research is being conducted on batteries capable of meeting various requirements.

[0003] Secondary batteries are classified into pouch, cylindrical, and prismatic types depending on the type of outer casing. Among these, pouch-type secondary batteries have the advantages of being easy to manufacture, having low production costs, and making it easy to configure high-capacity battery packs by connecting multiple unit cells in series and / or parallel.

[0004] A pouch-type battery case is configured with an aluminum thin film interposed therein to protect the electrolyte and cell assembly introduced into the interior through a subsequent process, and to improve the electrochemical properties of the battery cell and heat dissipation. In order to ensure insulation or isolation between the battery cell and the outside, an insulating layer coated with an insulating material such as polyethylene terephthalate (PET) resin or nylon resin may be formed on the outside of the aluminum thin film.

[0005] As devices become lighter and smaller, it is important to increase the energy density of the secondary batteries used in them. The problem to be solved

[0006] The problem that the present invention aims to solve is to provide a pouch-type battery case having high energy density and improved assembly, and a secondary battery including the same. means of solving the problem

[0007] A pouch-type battery case according to one embodiment of the present invention may include a pair of cup portions; a sealing portion located around the perimeter of the cup portions; and a side folding portion formed by folding a portion of the sealing portions. The side folding portion may include a first folding portion folded in a rotational direction; and a connecting portion connecting the cup portions and the first folding portion, and inclined in a rotational direction opposite to the rotational direction with respect to the cup portions.

[0008] The above side folding portion may further include a second folding portion that is folded in the direction of rotation at an outer side of the first folding portion.

[0009] The angle formed by the connecting part with respect to the cup part in the opposite rotational direction may be greater than 90 degrees and less than or equal to 150 degrees.

[0010] The angle formed by the connecting part with respect to the cup part in the opposite rotational direction may be greater than 90 degrees and less than or equal to 130 degrees.

[0011] When the width of the side folding portion is w and the angle that the connecting portion makes with respect to the cup portion in the opposite rotational direction is θ, the relationship w=2.1-(θ-90) / 25 can be satisfied.

[0012] The width of the above-mentioned side folding portion may be smaller than 2.1 mm.

[0013] The above side folding portion can have a margin of 0.3 mm or more with respect to the height direction of the cup portion and the bottom surface of the cup portion.

[0014] For every 5 degrees the angle formed by the connecting part with respect to the cup part in the opposite rotational direction, the margin may increase by 0.15 mm.

[0015] With respect to the full length or full width direction of the cup portion, a part of the side folding portion may overlap with either one of the pair of cup portions, and another part of the side folding portion may overlap with the other of the pair of cup portions.

[0016] A pouch-type battery case according to another embodiment of the present invention may include: a first cup portion; a second cup portion formed deeper than the first cup portion; a sealing portion connected to the periphery of the first cup portion and the second cup portion; and a side folding portion in which a part of the sealing portion is folded at least once toward the periphery of the second cup portion. The ratio of the depth of the first cup portion to the depth of the second cup portion may be 0.36:0.64 to 0.47:0.53. Effects of the invention

[0017] According to a preferred embodiment of the present invention, the margin between the side folding portion and the bottom surface of the cup portion can be formed to be sufficiently large. As a result, when the secondary battery is assembled into a battery module, the assemblability of the secondary battery can be improved and the energy density of the secondary battery can be increased. Brief explanation of the drawing

[0018] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. FIG. 1 is an exploded perspective view of a secondary battery according to one embodiment of the present invention. FIG. 2 is a plan view of a secondary battery according to one embodiment of the present invention. FIG. 3 is a side view of a secondary battery according to one embodiment of the present invention. Figure 4 is a side view of a secondary battery according to a comparative example. FIG. 5 is a side view of a secondary battery according to another embodiment of the present invention. Specific details for implementing the invention

[0019] Hereinafter, preferred embodiments of the present invention are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in various different forms and is not limited or restricted by the following embodiments.

[0020] In order to clearly explain the present invention, detailed descriptions of related prior art that are irrelevant to the explanation or that may unnecessarily obscure the essence of the invention have been omitted. Furthermore, when assigning reference numerals to the components of each drawing in this specification, identical or similar reference numerals are assigned to identical or similar components throughout the entire specification.

[0021] Furthermore, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0022] FIG. 1 is an exploded perspective view of a secondary battery according to one embodiment of the present invention, and FIG. 2 is a plan view of a secondary battery according to one embodiment of the present invention.

[0023] A secondary battery (1) according to one embodiment of the present invention may include an electrode assembly (10) and a pouch-type battery case (20) (hereinafter referred to as 'pouch').

[0024] The electrode assembly (10) may be formed by alternately stacking positive and negative electrodes with a separator in between. That is, the electrode assembly (10) may include a plurality of electrodes and a separator interposed between the plurality of electrodes to insulate the plurality of electrodes from each other. The electrode assembly (10) may be contained together with an electrolyte in a pouch (20), more specifically in a pair of cup portions (22) to be described later.

[0025] The electrode assembly (10) may be stacked, jelly roll, stacked and folding type, etc., and is not limited thereto.

[0026] The electrode assembly (10) may include an electrode tab (11). The electrode tab (11) is connected to the positive and negative electrodes of the electrode assembly (10), respectively, and protrudes outward from the electrode assembly (10) to serve as a path through which electrons can move between the inside and outside of the electrode assembly (10).

[0027] The electrode tab (11) can be formed by cutting the unpaired portion of the electrode current collector or by connecting a separate conductive member to the unpaired portion using ultrasonic welding or the like.

[0028] The electrode tab (11) may include an anode tab (111) connected to an anode and a cathode tab (112) connected to a cathode. The anode tab (111) and the cathode tab (112) may protrude in different directions from the electrode assembly (10), but are not limited thereto and may be formed to protrude in various directions, such as protruding in the same direction from one side.

[0029] An electrode lead (12) that supplies electricity to the outside of the secondary battery (1) can be connected to the electrode tab (11) of the electrode assembly (10) by spot welding or the like. Additionally, a portion of the electrode lead (12) can be surrounded by an insulating portion (14). The insulating portion (14) can be located in a limited area (24)(25) where the first case (21) and the second case (22) of the pouch (20) are heat-fused. Thus, the insulating portion (14) can insulate the electrode lead (12) from the pouch (20) and maintain the sealing of the pouch (20). Generally, insulating tape that is easy to attach to the electrode lead (12) and has a relatively thin thickness is often used as the insulating portion (14), but it is not limited to this, and various materials can be used as long as they can insulate the electrode lead (12).

[0030] One end of the electrode lead (12) may be connected to the electrode tab (11) and the other end may protrude outside the battery case (13). The electrode lead (12) may include a positive lead (121) connected to the positive tab (111) and a negative lead (122) connected to the negative tab (112).

[0031] The electrode lead (12) can electrically connect the electrode assembly (10) to the outside. Additionally, since the positive tab (111) and the negative tab (112) are formed to protrude in various directions, the positive lead (121) and the negative lead (122) can also extend in various directions.

[0032] The pouch (20) can accommodate the electrode assembly (10) inside and can be formed by molding a laminate sheet. More specifically, the pouch (20) can be manufactured by drawing a flexible laminate sheet using a die and a punch, etc., so that a portion thereof is stretched to form a cup portion (23) having a pocket-shaped receiving space (231).

[0033] The pouch (20) may accommodate and seal the electrode assembly (10) so that a portion of the electrode lead (12) is exposed. This pouch (20) may include a pair of cases (21)(22), more specifically, a first case (21) and a second case (22).

[0034] Hereinafter, the first case (131) and the second case (132) are described with the example of a case where one side is connected to the other as shown in FIG. 1. However, this is not limited thereto, and it is also possible for the first case (131) and the second case (132) to be separated from each other and manufactured separately.

[0035] In each case (21)(22), a cup portion (23) may be formed to provide a receiving space (231) capable of accommodating an electrode assembly (10). The cup portion (23) may have a recessed shape. The cup portion (23) may include a bottom surface (231) and a perimeter surface (232).

[0036] The cup portions (23) of a pair of cases (21)(22) are arranged to face each other so as to accommodate an electrode assembly (10) together. Thus, compared to the case where a cup portion (23) is formed in only one of the pair of cases (21)(22), the pouch (20) can accommodate a thick and high-capacity electrode assembly (10).

[0037] The first case (131) and the second case (132) can be connected by a bridge (26). The bridge (26) can be formed between a pair of cup portions (23). The bridge (26) can be extended parallel to the full length or full width direction of the electrode assembly (10). When the bridge (26) is folded, the cup portion (23) of the first case (21) and the cup portion (23) of the second case (22) can face each other.

[0038] Each case (21)(22) may include a terrace section (24)(25) located around the perimeter of the cup section (23). More specifically, the terrace section (24)(25) may include a first terrace section (24) parallel to either the full length or full width of the electrode assembly (10), and a second terrace section (25) parallel to the other.

[0039] For example, the second terrace section (25) can be located on the opposite side of the bridge (26) based on the cup section (23), and the first terrace section (24) can connect the second terrace section (25) and the bridge (26) at both ends.

[0040] When the bridge (26) is folded, the terrace portions (24)(25) of the first case (21) and the second case (22) can come into contact with each other. At this time, the insulating portion (14) of the electrode assembly (10) can be located between the terrace portions (24)(25) of the pair of cases (21)(22). For example, the insulating portion (14) can be located between the first terrace portions (24) of the pair of cases (21)(22).

[0041] The terrace portions (24)(25) of the first case (21) and the second case (22) may be sealed together while in contact with each other to form a sealing portion. The sealing portion may include a first sealing portion formed by sealing the first terrace portions (24) together and a second sealing portion formed by sealing the second terrace portions (25) together. For convenience of explanation, the first sealing portion is indicated by the reference numeral '24', which is the same as the first terrace portion (24), and the second sealing portion is indicated by the reference numeral '25', which is the same as the second terrace portion (25). That is, the pouch (20) may include sealing portions (24)(25) located around the perimeter of the cup portion (22).

[0042] The pouch (20) may include a side folding portion (30) formed by folding a portion of the sealing portion (24)(25). More specifically, a portion of the sealing portion (24)(25) where the electrode lead (12) is not protruding may be folded to form the side folding portion (30). For example, as shown in FIG. 2, when the electrode lead (12) protrudes to the outside of the pouch (20) through the first sealing portion (24), the second sealing portion (25) may be folded to form the side folding portion (30).

[0043] By means of the side folding portion (30), the space occupied by the secondary battery (1) within the battery module or battery pack can be reduced, so the energy density of the secondary battery (1) can be increased.

[0044] FIG. 3 is a side view of a secondary battery according to one embodiment of the present invention.

[0045] The side folding portion (30) may not protrude beyond the bottom surface (231) of the cup portion (23) in the height direction (up and down direction based on FIG. 3) of the cup portion (23).

[0046] The side folding section (30) may include a first folding section (31) and a connecting section (33). The side folding section may further include a second folding section (32).

[0047] The first folding part (31) and the second folding part (32) can be folded in one rotational direction (e.g., counterclockwise with respect to FIG. 3). That is, the first folding part (31) and the second folding part (32) can be folded in the same rotational direction. The first folding part (31) and the second folding part (32) can be formed in a double side folding (DSF) manner.

[0048] The second folding part (32) can be folded further outward than the first folding part (31). That is, the first folding part (31) can be formed at a position relatively closer to the cup part (23) compared to the second folding part (32). Therefore, after the sealing part (24)(25) is folded once based on the first folding part (31), the sealing part (24)(25) can be folded a second time based on the second folding part (32).

[0049] The second folding part (32) may be located on the side of either of the pair of cup parts (23) with respect to the full length direction or full width direction (e.g., horizontal direction based on FIG. 3) of the cup part (23). Below, as illustrated in FIG. 3, the case in which the second folding part (32) is located on the side of the cup part (23) of the second case (22) will be described as an example.

[0050] The connecting portion (33) can connect the cup portion (23) and the first folding portion (31). That is, the connecting portion (33) can be located inside the first folding portion (31) in the sealing portion (24)(25).

[0051] The connecting portion (33) may be tilted in a rotational direction opposite to the one rotational direction with respect to the cup portion (23) (e.g., clockwise with respect to FIG. 3). By the configuration of this connecting portion (33), with respect to the full length direction or full width direction (e.g., horizontal direction with respect to FIG. 3) of the cup portion (23), a part of the side folding portion (30) may overlap with either of the pair of cup portions (23), and the other part of the side folding portion (30) may overlap with the other of the pair of cup portions (23).

[0052] The angle (θ) that the connecting part (33) makes with respect to the cup part (23) in the opposite rotational direction may be greater than 90 degrees and less than or equal to 150 degrees, and preferably less than or equal to 130 degrees.

[0053] The above angle (θ) may be the angle formed by the virtual line connecting the starting point and the ending point of the connecting part (33) with the cup part (23). The starting point of the connecting part (33) may be the point where the connecting part (33) begins to tilt, and the ending point of the connecting part (33) may be the point where the connecting part (33) and the first folding part (31) are connected.

[0054] More specifically, the angle (θ) formed by the cup portion (23) located on the side of the second folding portion (32) among a pair of cup portions (23) and the connecting portion (33) may be greater than 90 degrees and less than or equal to 150 degrees, and preferably less than or equal to 130 degrees. For example, the angle (θ) formed by the cup portion (23) and the connecting portion (33) of the second case (22) may be greater than 90 degrees and less than or equal to 150 degrees, and preferably less than or equal to 130 degrees.

[0055] By forming the above angle (θ) to be greater than 90 degrees and less than or equal to 150 degrees, preferably less than or equal to 130 degrees, the margin (a) formed between the side folding part (30) and the bottom surface (231) of the cup part (23) can be sufficiently large.

[0056] If the angle (θ) is 90 degrees or less, the margin (a) may become excessively small or the side folding portion (130) may protrude beyond the bottom surface (231) of the cup portion (23), which may reduce the assembly quality of the secondary battery (1) and reduce the energy density. Conversely, if the angle (θ) is greater than 150 degrees, the connection portion (33) and the first folding portion (31) may bend excessively, which may cause wrinkles or cracks.

[0057] The side folding portion (30) can form a margin (a) of 0.3 mm or more with respect to the height direction of the cup portion (23) and the bottom surface (231) of the cup portion (23). More specifically, the side folding portion (30) can form a margin of 0.3 mm or more with respect to the more adjacent bottom surface (231) of a pair of bottom surfaces (231) of the cup portion (23). Additionally, the margin (a) can increase by 0.15 mm for every 5 degrees increase in the angle (θ).

[0058] Thus, when the secondary battery (1) is assembled into a battery module, the assembly of the secondary battery (1) can be improved and the energy density of the secondary battery (1) can be increased.

[0059] Additionally, the width (w) of the side folding portion (30) can be formed smaller in the full length direction or full width direction (e.g., horizontal direction based on FIG. 3) of the cup portion (23) by means of the connecting portion (33). If the width (w0) of the secondary battery (1) is constant, the width (w1) of the cup portion (23) can be increased by the amount that the width (w) of the side folding portion (30) becomes smaller.

[0060] Thus, in addition to reducing the space occupied by the side folding part (30), the width of the electrode assembly (10) housed in the cup part (23) can be increased, so the energy density of the secondary battery (1) can be further increased.

[0061] More specifically, the width (w) of the side folding portion (30) may be smaller than 2.1 mm. Additionally, when the width of the side folding portion (30) is w and the angle that the connecting portion (30) makes with respect to the cup portion (23) in the opposite rotational direction is θ, the relationship w = 2.1 - (θ - 90) / 25 can be satisfied. That is, the width (w) of the side folding portion (30) may decrease by 0.2 mm for every 5-degree increase in the angle (θ). That is, if the width (w0) of the secondary battery (1) is constant, the width (w1) of the cup portion (23) may be increased by 0.2 mm for every 5-degree increase in the angle (θ).

[0062] Meanwhile, the side folding portion (30) can be fixed by a fixing member (40), such as a tape. More specifically, the central part of the fixing member (40) is attached to the side folding portion (30), more specifically to the first folding portion (31), and both ends can be attached to a pair of cup portions (23). Both ends of the fixing member (40) can be attached to the bottom surface (231) of a pair of cup portions (23), as shown in FIG. 3.

[0063] However, unlike as illustrated in FIG. 3, both ends of the fixing member (40) may be attached to the circumferential surface (232) of the cup portion (23). This configuration may be possible by forming the margin (a) between the side folding portion (30) and the bottom surface (231) of the cup portion (23) sufficiently large, such that it is 0.3 mm or larger, as previously explained. In this case, since the thickness of the secondary battery (1) is prevented by the fixing member (40), the energy density of the secondary battery (1) can be maintained at a high level and the appearance can be made aesthetically pleasing.

[0064] Figure 4 is a side view of a secondary battery according to a comparative example.

[0065] Unlike the side folding portion (30) of the secondary battery (1a) according to the comparative example, the connecting portion (33a) of the secondary battery (1) according to one embodiment of the present invention may be tilted in the same rotational direction as the first folding portion (31) and the second folding portion (32) (e.g., counterclockwise direction based on FIG. 4).

[0066] By means of this connecting part (33a), the width (w) of the side folding part (30a) a ) can be formed relatively large. If the width (w0) of the secondary battery (1) is constant, the width (w) of the side folding part (30) a As ) increases, the width (w1) of the cup portion (23) a) can be reduced. Therefore, as the space occupied by the side folding part (30a) increases, the width of the electrode assembly (10) housed in the cup part (23) can be reduced, so there is a concern that the energy density of the secondary battery (1) may decrease.

[0067] Additionally, due to the connecting portion (33a), the side folding portion (30) may overlap with one of the pair of cup portions (23) in the full length direction or full width direction (e.g., horizontal direction based on FIG. 3) of the cup portion (23) and may not overlap with the other of the pair of cup portions (23). Also, the angle (θ) formed by the connecting portion (33a) and the cup portion (23) located on the side of the second folding portion (32) of the pair of cup portions (23) may be 90 degrees or less. As a result, the margin (a') formed between the side folding portion (30a) and the bottom surface (231) of the cup portion (23) may become excessively small. Therefore, when the secondary battery (1) is assembled into a battery module, the assemblability of the secondary battery (1) is reduced, and there is a concern that the energy density of the secondary battery (1) may decrease.

[0068] Additionally, since the margin (a') is not sufficiently large, it may be difficult for both ends of the fixing member (40) to be attached to the circumferential surface (232) of the cup portion (23). In this case, there is a concern that the thickness of the secondary battery (1) may increase due to the fixing member (40).

[0069] On the other hand, unlike the secondary battery (1a) according to this comparative example, the secondary battery (1) according to one embodiment of the present invention can resolve these series of concerns.

[0070] FIG. 5 is a side view of a secondary battery according to another embodiment of the present invention.

[0071] In another embodiment of the present invention, a secondary battery (1') may have a pair of cup portions (23) formed asymmetrically at different depths, and a side sealing portion (30') may be folded at least once toward the cup portion (23) formed deeper among the pair of cup portions (23).

[0072] More specifically, the cup portion (23) of the second case (22) may be formed deeper than the cup portion (23) of the first case (21). The cup portion (23) of the first case (21) may be named the first cup portion, and the cup portion (23) of the second case (22) may be named the second cup portion. Also, the side sealing portion (30') may be formed by folding a part of the sealing portion (24)(25) at least once toward the circumference of the second cup portion (23).

[0073] The connecting portion (33') of the side sealing portion (30') may be tilted in the same rotational direction as the first folding portion (31) and the second folding portion (32) (e.g., counterclockwise direction with respect to FIG. 5). This is similar to the comparative example described above, but unlike the secondary battery (1a) according to the comparative example, the connecting portion (33') of the secondary battery (1') according to another embodiment of the present invention may be tilted toward the deeper cup portion (23) of the pair of cup portions (23).

[0074] Accordingly, while maintaining a constant overall thickness of the secondary battery (1'), the margin (a) formed between the side folding portion (30') and the bottom surface (231) of the cup portion (23) can be sufficiently increased. As a result, when the secondary battery (1) is assembled into a battery module, the assemblability of the secondary battery (1) can be improved and the energy density of the secondary battery (1) can be increased.

[0075] In particular, the ratio of the depth (d1) of the cup portion (23) of the first case (21) to the depth (d2) of the cup portion (23) of the second case (22) may be 0.36:0.64 to 0.47:0.53.

[0076] If the depth ratio of a pair of cup portions (23) is asymmetrical to 0.36:0.64, wrinkles may occur in the cup portion (23) formed shallower among the pair of cup portions (23), and cracks may occur in the cup portion (23) formed deeper due to excessive elongation. Conversely, if the depth ratio of a pair of cup portions (23) is symmetrical to 0.36:0.64, the margin (a) becomes excessively small, which may reduce the assembly quality of the secondary battery (1) and reduce the energy density.

[0077] That is, by forming the depth ratio of a pair of cup portions (23) to 0.36:0.64 to 0.47:0.53, wrinkles or cracks can be prevented from occurring in the cup portions (23), and the margin (a) can be formed sufficiently large.

[0078] The above description is merely an illustrative explanation of the technical concept of the present invention, and those skilled in the art to which the present invention pertains will be able to make various modifications and variations within the scope of the essential characteristics of the present invention.

[0079] Accordingly, the embodiments disclosed in this invention are intended to explain, not limit, the technical concept of the invention, and the scope of the technical concept of the invention is not limited by these embodiments.

[0080] The scope of protection of the present invention shall be interpreted by the claims below, and all technical ideas within an equivalent scope shall be interpreted as being included within the scope of rights of the present invention. Explanation of the symbols

[0081] 1: Secondary battery 10: Electrode assembly 20: Pouch-type battery case 21: First case 22; Case 23: Cup part 231: Bottom surface (of the cup) 232: Circumference surface (of the cup) 24: 1st sealing section 25: 2nd sealing section 26: Bridge 30: Side folding section 31: 1st folding section 32: 2nd folding section 33: Connecting part 40; Fixing member

Claims

Claim 1 A pouch-type battery case comprising: a pair of cup portions; a sealing portion located around the perimeter of the cup portions; and a side folding portion formed by folding a portion of the sealing portion, wherein the side folding portion comprises: a first folding portion folded in a rotational direction; and a connecting portion connecting the cup portion and the first folding portion and inclined in a rotational direction opposite to the rotational direction with respect to the cup portion, wherein, with respect to the full length direction or full width direction of the cup portions, a portion of the side folding portion overlaps with one of the pair of cup portions, and another portion of the side folding portion overlaps with the other of the pair of cup portions. Claim 2 A pouch-type battery case according to claim 1, wherein the side folding portion further comprises a second folding portion folded in the direction of rotation from the outer side of the first folding portion. Claim 3 A pouch-type battery case according to claim 1, wherein the angle formed by the connecting part with respect to the cup part in the opposite rotational direction is greater than 90 degrees and less than or equal to 150 degrees. Claim 4 A pouch-type battery case according to claim 1, wherein the angle formed by the connecting part with respect to the cup part in the opposite rotational direction is greater than 90 degrees and less than or equal to 130 degrees. Claim 5 A pouch-type battery case according to claim 3, satisfying the relationship w = 2.1 - (θ - 90) / 25, where w is the width of the side folding portion and θ is the angle formed by the connecting portion with respect to the cup portion in the opposite rotational direction. Claim 6 In claim 1, the width of the side folding portion is smaller than 2.1 mm, for a pouch-type battery case. Claim 7 A pouch-type battery case according to claim 1, wherein the side folding portion forms a margin of 0.3 mm or more with respect to the height direction of the cup portion with respect to the bottom surface of the cup portion. Claim 8 A pouch-type battery case according to claim 7, wherein the margin increases by 0.15 mm for every 5 degrees the angle formed by the connecting part with respect to the cup part in the opposite rotational direction. Claim 9 delete Claim 10 A secondary battery comprising a pouch-type battery case according to any one of claims 1 to 8; and an electrode assembly accommodated within a pair of cup portions. Claim 11 delete Claim 12 delete

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