Secondary battery case and secondary battery

Abstract

The case for a secondary battery according to the present invention is a case for a secondary battery capable of accommodating an electrode assembly having a structure in which electrodes and separators are alternately arranged, and includes a first cup having an indented shape; a second cup having an indented shape provided on one side of the first cup; and a first peripheral portion surrounding the periphery of the first cup and a second peripheral portion surrounding the periphery of the second cup when the case is unfolded, the first peripheral portion including a first cup-corresponding peripheral portion that is a portion corresponding to the width of the first cup, the second peripheral portion including a second cup-corresponding peripheral portion that is a portion corresponding to the second cup, and the width of the first cup is longer than the length of the first cup-corresponding peripheral portion.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0002204, filed on January 7, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a secondary battery case and a secondary battery, and relates to a secondary battery case and a secondary battery that can reduce dead space that does not contribute to capacity in a secondary battery by reducing parts that protrude or deform unnecessarily from the exterior of the secondary battery case and reducing the space occupied by the secondary battery, thereby improving energy density, improving inaccurate overall width measurement of a cell, preventing crack risks, improving assembly in a battery module, and reducing the cost of thermal resin for cooling the cells. [Background technology]

[0003] Secondary batteries capable of repeated charging and discharging can be classified into cylindrical, square, pouch, etc. types depending on their manufacturing method or structure. Among these, pouch-type secondary batteries generally have a structure in which an electrode assembly having a structure in which electrodes and separators are alternately arranged is housed in a sheet-like pouch exterior material.

[0004] According to the prior art, in order to manufacture a pouch-type secondary battery, a forming process is performed in which a portion of a sheet-like pouch is pressed by an area corresponding to the area of ​​an electrode assembly to form a cup 5 having a concave shape, and then the electrode assembly is mounted in the cup 5 formed in the pouch. Then, portions of a peripheral portion 3 formed on the periphery of the cup 5 in the pouch region are attached to each other to form a sealing portion 4. The sealing portion formed by portions of the peripheral portions of the pouch cup being attached to each other and the peripheral portion other than the sealing portion are not pressurized in the forming process.

[0005] Here, due to the step between the peripheral portion and the sealing portion where forming pressure is not applied and the cup where forming has been performed, during the folding and degassing operations during the production of the secondary battery with a pouch design, some areas of the peripheral portion and the sealing portion deviate from the width of the cup.

[0006] FIG. 1 shows that a portion of the peripheral portion 3 and the sealing portion 4 formed at the upper and lower portions of a pouch 2 of a pouch-type secondary battery 1 manufactured by conventional technology protrudes beyond the width P of a cup in which an electrode assembly is housed.

[0007] Such a protruding region may be called a bat-ear. The bat-ear is a portion that protrudes or deforms unnecessarily from the exterior of a secondary battery case, and acts as a cause of an increase in dead space that does not contribute to the capacity of the secondary battery, resulting in a problem of a decrease in the energy density of the secondary battery. In addition, the bat-ear causes problems such as inaccurate measurement of the overall width of the cell, the risk of cracks, a decrease in the ease of assembly in a battery module, and an increase in the cost of thermal resin for cooling the cell.

[0008] Meanwhile, referring to Fig. 1, the butt ears can be divided into the cup edge butt ear portion 6 and the end butt ear portion 7, and it is necessary to reduce both the cup edge butt ear portion 6 and the end butt ear portion 7, and the above-mentioned problems cannot be solved by removing only one of the two. Therefore, a method for removing both the cup edge butt ear portion 6 and the end butt ear portion 7 has been researched. Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been devised to solve the above problems, and an object of the present invention is to provide a secondary battery case and a secondary battery which can reduce dead space that does not contribute to the capacity of the secondary battery by reducing parts that protrude or deform unnecessarily from the exterior of the secondary battery case and reducing the space occupied by the secondary battery, thereby improving the energy density, improving inaccurate overall width measurement of the cell, preventing crack risks, improving assembly in a battery module, and reducing the cost of thermal resin for cooling the cells. [Means for solving the problem]

[0010] The secondary battery case according to the present invention is a secondary battery case capable of accommodating an electrode assembly having a structure in which electrodes and separators are alternately arranged, and includes a first cup having an indented shape; a second cup having an indented shape provided on one side of the first cup; and a first peripheral portion surrounding the peripheral edge of the first cup and a second peripheral portion surrounding the peripheral edge of the second cup when the secondary battery case is unfolded, the first peripheral portion including a first cup-corresponding peripheral portion that is a portion corresponding to the width of the first cup, the second peripheral portion including a second cup-corresponding peripheral portion that is a portion corresponding to the width of the second cup, and the width of the first cup is longer than the length of the first cup-corresponding peripheral portion.

[0011] The width of the first cup may be the distance from the left side wall of the first cup to a first reference vertical line that passes through the upper end point of the right side wall of the first cup and is perpendicular to the first peripheral portion, and the length of the first cup corresponding peripheral portion may be the length from the peripheral connection point where the first peripheral portion and the second peripheral portion abut to a point on the first peripheral portion that corresponds to the upper end point of the right side wall of the first cup.

[0012] The portion where the first peripheral portion and the second peripheral portion are connected is formed in a rounded shape to have a predetermined radius of curvature (R1), and the first cup-corresponding peripheral portion may include a first curved portion formed by a portion of the rounded shape, and a first straight portion having a straight shape as the portion excluding the first curved portion.

[0013] The first cup width length (A) may be greater than the sum of the first curved portion length (B) and the first straight portion length (C).

[0014] The first cup-corresponding peripheral portion and the second cup-corresponding peripheral portion may be formed at a predetermined angle (θ) with each other to form a V-shape.

[0015] The predetermined angle (θ) may be between 130 degrees and 170 degrees.

[0016] The distance (D) between the peripheral connection point, where the first peripheral portion meets the second peripheral portion, and the bridge connection point, where the left side wall of the first cup meets the right side wall of the second cup, may be 1 mm or less.

[0017] The portion where the left side wall of the first cup and the right side wall of the second cup are connected is rounded to have a predetermined radius of curvature (R2), and the predetermined radius of curvature (R2) may be smaller than 2 mm.

[0018] The width of the second cup may be greater than the length of the second cup corresponding periphery.

[0019] The width of the second cup may be the distance from the right side wall of the second cup to a second reference vertical line that passes through the upper end point of the left side wall of the second cup and is perpendicular to the second periphery, and the length of the second cup corresponding periphery may be the length from the periphery connection point, which is the point where the first periphery and the second periphery abut, to a point on the second periphery that corresponds to the upper end point of the left side wall of the second cup.

[0020] The portion where the first peripheral portion and the second peripheral portion are connected is formed in a rounded shape to have a predetermined radius of curvature (R1), and the second cup-corresponding peripheral portion may include a second curved portion formed by a portion of the rounded shape and a second straight portion having a straight shape as the portion excluding the second curved portion.

[0021] The width of the second cup may be greater than the sum of the length of the second curved portion and the length of the second straight portion.

[0022] The secondary battery according to the present invention includes the secondary battery case according to the present invention; an electrode assembly inserted into the secondary battery case; and an electrolyte solution contained in the secondary battery case together with the electrode assembly. Effect of the Invention

[0023] The secondary battery case and secondary battery according to the present invention reduce parts that protrude or are deformed unnecessarily from the exterior of the secondary battery case and reduce the space occupied by the secondary battery, thereby reducing dead space that does not contribute to the capacity of the secondary battery and improving the energy density, and can also improve inaccurate overall width measurement of cells, prevent crack risks, improve assembly in battery modules, and reduce the cost of thermal resin for cooling cells. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a plan view showing the structure of a secondary battery manufactured by a conventional technique. [Diagram 2] 1 is a conceptual perspective view showing a secondary battery in which an electrode assembly is accommodated in a secondary battery case according to an embodiment of the present invention; [Diagram 3] FIG. 1 is a cross-sectional view showing a secondary battery case according to a first embodiment of the present invention. [Figure 4] FIG. 4 is an enlarged cross-sectional view of the cross-sectional view shown in FIG. 3, in which the width of the first cup is shown in detail. [Diagram 5]1 is a perspective view showing a secondary battery case according to a first embodiment of the present invention before being folded. [Figure 6] 6 is a diagram showing the secondary battery case according to the first embodiment of the present invention shown in FIG. 5 after being folded. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. However, the present invention may be embodied in various different forms and should not be construed as being limited to the following embodiments.

[0026] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the description or related known technologies that unnecessarily obscure the gist of the present invention will be omitted, and when adding reference symbols to components in each drawing in this specification, the same or similar reference symbols will be used for the same or similar components throughout the specification.

[0027] Furthermore, the terms and words used in this specification and the claims should not be interpreted limited to their ordinary and dictionary meanings, but should be interpreted in a way that is consistent with the technical ideas of the present invention, based on the principle that the inventor himself / herself can appropriately define the concepts of terms in order to explain the invention in the best possible manner.

[0028] Example 1 FIG 2 is a conceptual perspective view showing a secondary battery in which an electrode assembly is accommodated in a secondary battery case according to an embodiment of the present invention. FIG 3 is a cross-sectional view showing a secondary battery case according to a first embodiment of the present invention. FIG 4 is an enlarged cross-sectional view showing the cross-sectional view shown in FIG 3 in order to show the width of a first cup in detail. FIG 5 is a perspective view showing the secondary battery case according to the first embodiment of the present invention before it is folded. FIG 6 is a view showing the secondary battery case according to the first embodiment of the present invention shown in FIG 5 after it has been folded.

[0029] 2 to 4, the secondary battery case 100 according to the first embodiment of the present invention may be a secondary battery case 100 capable of accommodating an electrode assembly having a structure in which electrodes and separators are alternately arranged. In particular, it may be a pouch case for a pouch-type secondary battery 1000. The secondary battery case 100 according to the first embodiment of the present invention may include a first cup 110, a second cup 120, a first peripheral portion 130, and a second peripheral portion 140.

[0030] The first cup 110 and the second cup 120 may be recessed portions formed in the pouch. The second cup 120 may be provided on one side of the first cup 110. When the case is folded, the first cup 110 and the second cup 120 may be combined to form an internal space, and the electrode assembly 500 may be housed in the internal space (see FIG. 2).

[0031] In the secondary battery case 100, the first peripheral portion 130 may be a portion that surrounds the peripheral edge of the first cup 110 when the case is unfolded. The second peripheral portion 140 may be a portion that surrounds the peripheral edge of the second cup 120. As shown in Figures 2 and 3, the first peripheral portion 130 and the second peripheral portion 140 may abut against each other at the position of the peripheral connection point O.

[0032] In this specification, "when the case is unfolded" may mean the case when the case unfolds by releasing a specific adhesive that was present in the case and is left as it is without any artificial force being applied to the case.

[0033] The first peripheral portion 130 may include a first cup corresponding peripheral portion 131 that is a portion corresponding to the width of the first cup 110. The second peripheral portion 140 may include a second cup corresponding peripheral portion 141 that is a portion corresponding to the width of the second cup 120.

[0034] In this case, based on the cross-sectional view showing the widths of the first cup 110 and the second cup 120, as in Figure 3 or Figure 4, the secondary battery case 100 according to Example 1 of the present invention may have a width (A) of the first cup that is longer than the length of the first cup-corresponding peripheral portion 131.

[0035] Specifically, the width of the first cup 110 may be the distance from the left sidewall 111 of the first cup to a first reference vertical line I1 that passes through the upper end point of the right sidewall 112 of the first cup and is perpendicular to the first rim 130. The width of the first cup 110 may be the length shown as A in FIG.

[0036] The length of the first cup-corresponding rim 131 may be the length from the rim connection point (O) where the first rim 130 and the second rim 140 meet to a point (U1) on the first rim 130 that corresponds to the upper end point of the right side wall 112 of the first cup. The length of the first cup-corresponding rim 131 may be the length of the route along the first rim 130 from O to U1 in FIG. 3 or FIG. 4.

[0037] The first cup-compatible peripheral portion 131 may include a curved portion and a straight portion. Specifically, referring to FIG. 4, the portion where the first peripheral portion 130 and the second peripheral portion 140 are connected may be formed in a round shape to have a predetermined radius of curvature (R1), and the first cup-compatible peripheral portion 131 may include a first curved portion 132 formed by a part of the round shape and a first straight portion 133 having a straight shape as a portion other than the first curved portion 132. The length of the first curved portion 132 may be the length shown as B in FIG. 4. The length of the first straight portion 133 may be the length shown as C in FIG. 4. In this case, the length of the first cup-compatible peripheral portion 131 may be the sum of the length (B) of the first curved portion 132 and the length (C) of the first straight portion 133.

[0038] Therefore, in the secondary battery case 100 according to the first embodiment of the present invention, the width of the first cup (A) may be greater than the sum of the length (B) of the first curved portion 132 and the length (C) of the first straight portion 133. This may mean that the sum of the length (B) of the first curved portion 132 and the length (C) of the first straight portion 133 is less than the width of the first cup (A).

[0039] By having such a configuration, the present invention can reduce the butt ears, which are parts that unnecessarily protrude or are deformed from the appearance of the secondary battery case 100, and reduce the space occupied by the secondary battery 1000, thereby reducing dead space in the secondary battery 1000 that does not contribute to capacity, and improving the energy density.

[0040] FIG. 5 is a diagram showing the secondary battery case 100 according to the present invention before it is folded, and FIG. 6 is a diagram showing the secondary battery case 100 according to the present invention after it has been folded.

[0041] A secondary battery case 100 in which the width of the first cup (A) is greater than the sum of the length (B) of the first curved portion 132 and the length (C) of the first straight portion 133 may mean that the sum of the length (B) of the first curved portion 132 and the length (C) of the first straight portion 133 is smaller than the width of the first cup (A). In this case, as shown in FIG. 6, the B+C portion can be inside the outer boundary of the cup portion (to the right in FIG. 6), so that the butt ear can be reduced. That is, the effect of the periphery being pulled tightly inward is produced, so that the butt ear is reduced or eliminated.

[0042] In particular, in this case, the effect of reducing or eliminating the end butt ear portion 7 can be significant (see FIG. 1 for the end butt ear portion 7). Eliminating the butt ear not only reduces the dead space and improves the energy density as described above, but also improves the inaccurate overall width measurement of the cell, prevents the risk of cracks, improves assembly in the battery module, and reduces the cost of thermal resin for cooling the cells.

[0043] In the secondary battery case 100 according to the first embodiment of the present invention, the configuration shown on the first cup 110 and first peripheral portion 130 side may also be applied to the second cup 120 and second peripheral portion 140 side.

[0044] Specifically, based on a cross-sectional view showing the widths of the first cup 110 and the second cup 120, the length of the width of the second cup 120 may be longer than the length of the second cup corresponding rim portion 141.

[0045] Here, the width of the second cup 120 may be the distance from the right side wall 122 of the second cup to a second reference vertical line I2 that passes through the upper end point of the left side wall 121 of the second cup and is perpendicular to the second peripheral portion 140.

[0046] The length of the second cup-corresponding peripheral portion 141 may be the length from the peripheral connection point (O), which is the point where the first peripheral portion 130 and the second peripheral portion 140 abut, to a point (U2) of the second peripheral portion 140 that corresponds to the upper end point of the left side wall portion 121 of the second cup.

[0047] The portion where the first peripheral portion 130 and the second peripheral portion 140 are connected may be rounded to have a predetermined radius of curvature (R1), and the second cup-corresponding peripheral portion 141 may include a second curved portion 142 formed by a part of this rounded shape and a second straight portion 143 having a straight shape as a portion other than the second curved portion 142. In the secondary battery case 100 according to the first embodiment of the present invention, in particular, the width of the second cup 120 may be greater than the sum of the length of the second curved portion 142 and the length of the second straight portion 143. This may mean that the sum of the length of the second curved portion 142 and the length of the second straight portion 143 is smaller than the width of the second cup 120.

[0048] When formed in this configuration, as described above, it is possible to reduce the portions that protrude unnecessarily or are deformed from the exterior of the secondary battery case 100, thereby improving the energy density.

[0049] In the present invention, the shape shown on the first cup 110 and first peripheral portion 130 side and the shape shown on the second cup 120 and second peripheral portion 140 side may be symmetrical to each other based on the central vertical axis (M), but the present invention is not limited to this, and it goes without saying that the contents of the present invention can be applied even in cases where they are not symmetrical.

[0050] Example 2 Example 2 of the present invention differs from Example 1 in that an additional structure capable of reducing butt ears is added to the secondary battery case.

[0051] The contents common to the embodiment 1 will be omitted as much as possible, and the differences will be mainly described in the embodiment 2. In other words, if contents not described in the embodiment 2 are necessary, it is self-evident that they will be regarded as contents of the embodiment 1.

[0052] 3, in the cross-sectional view of the secondary battery case 100 according to the second embodiment of the present invention, the first cup-corresponding peripheral portion 131 and the second cup-corresponding peripheral portion 141 may be formed in a V-shape by forming a predetermined angle (θ) with each other. The predetermined angle (θ) may be 130 degrees to 170 degrees. For reference, in this case, the angle between the first peripheral portion 130 and the second peripheral portion 140 may also be θ.

[0053] The smaller the angle between first cup-corresponding peripheral portion 131 and second cup-corresponding peripheral portion 141, the better the effect of reducing butt ears. Normally, during folding, some areas of the peripheral portion and the sealing portion deviate from the width of the cup to form butt ears, and as θ becomes smaller, the amount of folding decreases, so the amount of butt ears can be reduced.

[0054] However, if θ is reduced to 130 degrees or less, the angle between the right side wall 112 of the first cup and the bottom of the first cup 110 will become large, and dead space may increase in the outer region of the cup. That is, as the dead space increases due to the inclination of the right side wall 112 of the first cup, space may be wasted.

[0055] Furthermore, if θ is greater than 170 degrees, the length (B) of the first curved portion 132 becomes excessively large, which may result in an increase in the butt ears. In particular, the degree of protrusion of the end butt ear portion 7 may increase. Therefore, the angle (θ) between the first cup-compatible peripheral portion 131 and the second cup-compatible peripheral portion 141 may be 130 degrees to 170 degrees.

[0056] 4, in the cross-sectional view of the secondary battery case 100 according to the second embodiment of the present invention, the distance (D) between the peripheral connection point (O) where the first peripheral portion 130 and the second peripheral portion 140 come into contact and the bridge connection point where the left side wall portion 111 of the first cup and the right side wall portion 122 of the second cup are connected may be 1 mm or less. Since the greater the distance D, the greater the degree of protrusion of the cup edge butt ear portion 6 may be, the distance D is preferably 1 mm or less. When D is 0 mm, the cup edge butt ear portion 6 may be removed. That is, when D is 0 mm, the cup edge butt ear portion 6 may not be generated.

[0057] 4, in the cross-sectional view of the secondary battery case 100 according to the second embodiment of the present invention, a portion where the left side wall 111 of the first cup and the right side wall 122 of the second cup are connected may be rounded to have a predetermined radius of curvature (R2). In this case, the predetermined radius of curvature (R2) may be smaller than 2 mm.

[0058] As the radius of curvature R2 increases, the distance D increases, whereas as the radius of curvature R2 decreases, the distance D decreases. Therefore, as the radius of curvature R2 increases, the degree of protrusion of the cup edge butt ear portion 6 increases, so R2 is formed to be smaller than 2 mm, thereby reducing the amount of protrusion of the cup edge butt ear portion 6.

[0059] When the protrusion amount of the cup edge butt ear portion 6 is reduced, the portion that protrudes or is deformed unnecessarily from the exterior of the secondary battery case 100 is reduced, thereby reducing the dead space that does not contribute to the capacity of the secondary battery 1000 and improving the energy density. In addition, the effects of improving inaccurate overall width measurement of the cell, preventing crack risks, improving assembly in the battery module, and reducing the cost of thermal resin for cooling the cells can be obtained.

[0060] Example 3 FIG. 2 is a conceptual perspective view showing a secondary battery in which an electrode assembly is accommodated in a secondary battery case according to an embodiment of the present invention.

[0061] The third embodiment of the present invention differs from the first and second embodiments in that it discloses a secondary battery 1000 manufactured using the secondary battery case 100 described in the first and second embodiments.

[0062] The contents common to the first and second embodiments will be omitted as much as possible, and the differences will be mainly described in the third embodiment. In other words, if contents not described in the third embodiment are necessary, they will obviously be regarded as contents of the first and second embodiments.

[0063] 2 and 3, a secondary battery 1000 according to the third embodiment of the present invention may include a secondary battery case 100, an electrode assembly 500, and an electrolyte (not shown). Here, the secondary battery case 100 may be the secondary battery case 100 described in the first and second embodiments.

[0064] The electrode assembly 500 may be inserted into the secondary battery case 100, and the electrode assembly 500 may be housed in the secondary battery case 100 together with an electrolyte. After the electrode assembly 500 and the electrolyte are housed in the case, the case may be folded so that the first cup 110 and the second cup 120 face each other, and then the first periphery 130 and the second periphery 140 may be sealed to manufacture the secondary battery 1000.

[0065] In the secondary battery 1000 according to the third embodiment of the present invention, the butt ears may be reduced or may not occur. Specifically, both the cup edge butt ear portion 6 and the end butt ear portion 7 may be reduced or may not occur, or either one of the cup edge butt ear portion 6 and the end butt ear portion 7 may be reduced or may not occur.

[0066] As a result, it is possible to reduce parts that protrude or are deformed unnecessarily from the outside of the secondary battery 1000, and to reduce dead space in the secondary battery 1000 that does not contribute to the capacity, thereby improving the energy density.

[0067] Although the present invention has been described above using limited examples and drawings, the present invention is not limited thereto, and various implementations are possible within the technical spirit of the present invention and the equivalent scope of the claims described below by a person having ordinary skill in the art to which the present invention pertains. [Explanation of symbols]

[0068] 100 Secondary battery case 110 First Cup 111 Left side wall of first cup 112 Right side wall of first cup 120 The Second Cup 121 Left side wall of second cup 122 Right side wall of second cup 130 First periphery 131 First cup rim 132 First curve 133 First Straight Section 140 Second Periphery 141 Second cup rim 142 Second curve 143 2nd straight section 500 electrode assembly 1000 secondary battery I1 First reference vertical line I2 Second reference vertical line

Claims

1. A case for a secondary battery capable of accommodating an electrode assembly having a structure in which electrodes and separators are alternately arranged, When the secondary battery case is unfolded, the secondary battery case includes a first cup located to the right of a folded position and having an indented shape, a second cup provided on one side of the first cup and located to the left of the folded position and having an indented shape, a first peripheral portion surrounding a peripheral edge of the first cup, and a second peripheral portion surrounding a peripheral edge of the second cup, the first cup and the second cup are recessed in a quadrangular shape with respect to a plane of the sheet of the secondary battery case, The first peripheral portion includes a first cup-corresponding peripheral portion extending in a width direction of the first cup, and the second peripheral portion includes a second cup-corresponding peripheral portion extending in a width direction of the second cup, The width of the first cup is longer than the length of the first cup corresponding peripheral portion; a width of the first cup is a distance from a left side wall of the first cup that is close to a folding position to a first reference vertical line I1 that passes through an upper end point of a right side wall of the first cup that is far from the folding position and is perpendicular to the first peripheral edge when the secondary battery case is unfolded; A secondary battery case, characterized in that the length of the first cup-corresponding peripheral portion is the length from a peripheral connection point (O) where the first peripheral portion and the second peripheral portion abut to a point (U1) of the first peripheral portion where the upper end point of the right side wall portion of the first cup is located when the secondary battery case is unfolded.

2. A portion where the first peripheral portion and the second peripheral portion are connected is formed in a round shape so as to have a predetermined radius of curvature (R1), 2. The secondary battery case according to claim 1, wherein the first cup-corresponding peripheral portion includes a first curved portion formed by a portion of the rounded shape and a first straight portion having a straight shape as a portion excluding the first curved portion.

3. 3. The secondary battery case according to claim 2, wherein a width (A) of the first cup is greater than a sum of a length (B) of the first curved portion and a length (C) of the first straight portion.

4. 4. The secondary battery case according to claim 1, wherein the first cup-corresponding peripheral portion and the second cup-corresponding peripheral portion are formed at a predetermined angle (θ) with each other to have a V-shape.

5. 5. The secondary battery case according to claim 4, wherein the predetermined angle (θ) is 130 degrees to 170 degrees.

6. 2. The secondary battery case according to claim 1, wherein a distance (D) between a peripheral connection point (O) where the first peripheral portion and the second peripheral portion abut and a bridge connection point where a left side wall of the first cup and a right side wall of the second cup are connected is 1 mm or less.

7. a portion where the left side wall of the first cup and the right side wall of the second cup are connected is formed in a round shape having a predetermined radius of curvature (R2); The secondary battery case according to claim 1 , wherein the predetermined radius of curvature (R2) is smaller than 2 mm.

8. The secondary battery case according to claim 1 , wherein a width of the second cup is longer than a length of the second cup-corresponding peripheral portion.

9. the width of the second cup is the distance from a right side wall of the second cup that is close to the folding position to a second reference vertical line (I1) that passes through an upper end point of a left side wall of the second cup that is far from the folding position and is perpendicular to the second peripheral edge when the secondary battery case is unfolded; 9. The secondary battery case according to claim 8, wherein the length of the second cup-corresponding peripheral portion is a length from a peripheral connection point (O) where the first peripheral portion and the second peripheral portion abut to a point (U2) of the second peripheral portion where an upper end point of the left side wall portion of the second cup is located when the secondary battery case is unfolded.

10. A portion where the first peripheral portion and the second peripheral portion are connected is formed in a round shape so as to have a predetermined radius of curvature (R1), 10. The secondary battery case according to claim 8, wherein the second cup-corresponding peripheral portion includes a second curved portion formed by a portion of the rounded shape and a second straight portion having a straight shape as a portion excluding the second curved portion.

11. The secondary battery case according to claim 10 , wherein a width of the second cup is greater than a sum of a length of the second curved portion and a length of the second straight portion.

12. A secondary battery case according to any one of claims 1 to 11, an electrode assembly inserted into the secondary battery case; and an electrolyte contained in the secondary battery case together with the electrode assembly.

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