Secondary battery case and secondary battery

Abstract

To disclose a case for a secondary battery, and the secondary battery.SOLUTION: According to an aspect of the present invention, a case for a secondary battery contains: first and second half-circle parts each having a half-circle shape; an outer peripheral part that surrounds a circumference of the first and second half-circle parts when expanding the case; and a coupling part that is provided between the first and second half-circle parts, and couples the first and second half-circle parts. When expanding the case, the coupling part contains; a first coupling surface that is formed so as to be inclined to an upper direction from one end part of the first half-circle part; and a second coupling surface that is formed so as to be inclined to the upper direction from the one end part of the second half-circle part.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0169262 filed on December 17, 2019, and Korean Patent Application No. 10-2020-0176713 filed on December 16, 2020, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a case for a secondary battery and a secondary battery, and more particularly to a case for a secondary battery and a secondary battery having a structure that can reduce the volume occupied by the secondary battery compared to conventional cases. [Background technology]

[0003] Secondary batteries capable of repeated charging and discharging can be classified into cylindrical, rectangular, pouch-type, etc., depending on their manufacturing method or structure. Among these, pouch-type secondary batteries generally have a structure in which an electrode assembly having electrodes and separators 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 compressed by an area corresponding to the area of ​​the electrode assembly to form a cup having a concave shape, and then the electrode assembly is mounted in the cup formed in the pouch, and then the portions of the pouch are attached to each other to form a sealed portion.

[0005] The sealed portion formed by adhering some areas of the pouches together is formed by adhering the areas that are not pressurized in the molding process together. Therefore, some areas of the sealed portion deviate from the width of the cup due to a step between the unmolded sealed portion and the molded cup. Figure 1 shows a shape in which some areas of the sealed portion 3 formed at the top and bottom of a pouch 2 of a pouch-type secondary battery 1 manufactured by the conventional technology are protruded by P beyond the width of the cup in which the electrode assembly is housed.

[0006] Such a protruding region is generally called a "bat-ear." The bat-ear increases dead space that does not contribute to the capacity of the secondary battery, resulting in a problem of reduced energy density of the secondary battery. Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, an object of the present invention is to increase the energy density of a secondary battery by eliminating the dead space generated in the sealed portion of a pouch-type secondary battery manufactured by the conventional technology. [Means for solving the problem]

[0008] According to a first aspect of the present invention to achieve the above object, there is provided a case for a secondary battery capable of accommodating an electrode assembly having a structure in which electrodes and separators are alternately arranged, the case including: a first indentation having a concave shape; a second indentation provided on one side of the first indentation and also having a concave shape; an outer circumferential portion surrounding the first indentation and the second indentation when the case is unfolded; and a connecting portion provided between the first indentation and the second indentation and connecting the first indentation and the second indentation; wherein when the case is unfolded, the connecting portion includes a first connecting surface formed to slope upward from one end of the first indentation; and a second connecting surface formed to slope upward from one end of the second indentation.

[0009] An upper end of the first connecting surface and an upper end of the second connecting surface may be connected to each other at an upper end of the connecting portion.

[0010] The outer periphery may include a first outer periphery formed around the first indentation; and a second outer periphery formed around the second indentation.

[0011] When the case is unfolded, the first indentation and the second indentation may have shapes symmetrical to each other with respect to the connecting portion.

[0012] When the case is unfolded, the case may be bent in a V shape at the area where the first outer periphery and the second outer periphery intersect so that an indented space A1 formed by the first indentation portion and an indented space A2 formed by the second indentation portion face each other.

[0013] When the case is unfolded, the first connecting surface may be formed to extend from a lower surface of the first indentation and incline upward, and the second connecting surface may be formed to extend from a lower surface of the second indentation and incline upward.

[0014] When the case is unfolded, a region where the first indentation and the connecting portion are connected and a region where the second indentation and the connecting portion are connected may be formed by curved surfaces.

[0015] When the case is unfolded, a region where the first connecting surface and the second connecting surface are connected may be formed by a curved surface.

[0016] The angle between the first outer periphery and the second outer periphery may be greater than or equal to 80 degrees and less than or equal to 160 degrees.

[0017] When the case is unfolded, the region where the first indentation and the first connecting surface are connected and the region where the second indentation and the second connecting surface are connected are formed by curved surfaces, the region where the first connecting surface and the second connecting surface are connected are formed by curved surfaces, and a radius of curvature R1 of the region where the first indentation and the first connecting surface are connected by the curved surface and a radius of curvature R2 of the region where the second indentation and the second connecting surface are connected by the curved surface may be larger than a radius of curvature R3 of the region where the first outer periphery and the second outer periphery are connected by the curved surface and a radius of curvature R4 of the region where the first connecting surface and the second connecting surface are connected by the curved surface.

[0018] An angle α formed by an area where an inner surface of the first indentation, which is formed on the opposite side of the connecting portion, intersects with the first outer periphery portion may be an obtuse angle.

[0019] According to a second aspect of the present invention for achieving the above object, there is provided a case for a secondary battery capable of accommodating an electrode assembly having a structure in which electrodes and separators are alternately arranged, the case comprising: a first indentation portion having an indented shape; a second indentation portion having an indented shape and provided on one side of the first indentation portion; and a connecting portion provided between the first indentation portion and the second indentation portion and connecting the first indentation portion and the second indentation portion; when the case is unfolded, the connecting portion comprises a first connecting surface formed to slope upward from one end of the first indentation portion; and a second connecting surface formed to slope upward from one end of the second indentation portion; and the case is bent in a V shape at a region where the first outer periphery and the second outer periphery intersect such that an indented space A1 formed by the first indentation portion and an indented space A2 formed by the second indentation portion face each other when the case is unfolded.

[0020] According to a third aspect of the present invention for achieving the above object, there is provided a secondary battery including: an electrode assembly having a structure in which electrodes and separators are alternately arranged; and a case for the secondary battery. Effect of the Invention

[0021] According to the present invention, it is possible to minimize or eliminate butt ears that occur in a case for a secondary battery manufactured by a conventional technology, and thus to increase the energy density of the secondary battery by eliminating dead space that occurs in a sealed portion of a pouch-type secondary battery manufactured by a conventional technology. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram showing the structure of a secondary battery manufactured by a conventional technique. [Diagram 2] 1 is a plan view illustrating a secondary battery case according to an embodiment of the present invention in an unfolded state; [Diagram 3] 1 is a vertical cross-sectional view illustrating a secondary battery case according to an embodiment of the present invention in an unfolded state; [Figure 4]4 is an enlarged view of the bent portion, the connecting portion, and the surrounding area shown in FIG. 3. FIG. [Diagram 5] 2 is a view illustrating a secondary battery case according to an embodiment of the present invention in an unfolded state; FIG. [Figure 6] 4 is a vertical cross-sectional view illustrating a state in which a secondary battery case according to an embodiment of the present invention is expanded by an external force; [Figure 7] 4 is a view illustrating a state in which a secondary battery case according to an embodiment of the present invention is expanded by an external force; [Figure 8] 4 is a perspective view illustrating a manner in which an electrode assembly is accommodated in a secondary battery case according to an embodiment of the present invention; FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, the structures of a secondary battery case and a secondary battery according to the present invention will be described with reference to the drawings.

[0024] FIG. 2 is a plan view illustrating a secondary battery case according to an embodiment of the present invention in an expanded state, and FIG. 3 is a vertical cross-sectional view illustrating a secondary battery case according to an embodiment of the present invention in an expanded state.

[0025] On the other hand, in this specification, "the appearance of the case when unfolded" may mean the appearance of the case when the case is unfolded by releasing a specific adhesion that was present in the case, but is left as it is without applying any artificial force to the case.

[0026] 2 and 3, a secondary battery case 10 (hereinafter referred to as "case") according to the present invention may be configured to accommodate an electrode assembly having a structure in which electrodes and separators are alternately arranged.

[0027] 2 and 3, the case 10 may include an indentation 100 having an indented shape. A pair of indentations 100 may be provided spaced apart from each other. More specifically, the indentation 100 may include a first indentation 110 and a second indentation 120 provided on one side of the first indentation 110.

[0028] As described above, the indentation portion 100 may have an indented shape. Therefore, an internal space may be formed in the indentation portion 100. That is, as shown in Fig. 2 and Fig. 3, an indentation space A1 defined by the first indentation portion 110 and an indentation space A2 defined by the second indentation portion 120 may be formed in the case 10.

[0029] Furthermore, the case 10 according to the present invention may further include an outer circumferential portion 300 that folds and surrounds the periphery of the first indentation portion 110 and the second indentation portion 120 when the case 10 is unfolded.

[0030] In this case, the outer periphery 300 may include a first outer periphery 310 formed around the first indentation 110 and a second outer periphery 320 formed around the second indentation 120. As shown in Figures 2 and 3, the first outer periphery 310 and the second outer periphery 320 may intersect with each other. That is, when the case 10 is unfolded, the first outer periphery 310 and the second outer periphery 320 may be connected to each other.

[0031] In addition, the case 10 according to the present invention may further include a connecting part 150 connecting the first indentation part 110 and the second indentation part 120. As shown in Fig. 2 and Fig. 3, the connecting part 150 may be provided between the first indentation part 110 and the second indentation part 120. As shown in Fig. 3, the connecting part 150 may be open to the first indentation part 110 and the second indentation part 120. Thus, the connecting part 150 may allow the indentation space A1 of the first indentation part 110 and the indentation space A2 of the second indentation part 120 to communicate with each other.

[0032] 3, when the case 10 is unfolded, the connecting portion 150 may include a first connecting surface 152 formed to slope upward from one end of the first indentation portion 110 and a second connecting surface 154 formed to slope upward from one end of the second indentation portion 120. More specifically, the first connecting surface 152 may be formed to slope upward from one end of the bottom surface 111 of the first indentation portion 110, and the second connecting surface 154 may be formed to slope upward from one end of the bottom surface 121 of the second indentation portion 120.

[0033] Meanwhile, as shown in FIG. 3, at the upper end of the connection part 150, the upper end of the first connection surface 152 and the upper end of the second connection surface 154 may be connected to each other.

[0034] More specifically, the indentation space A1 of the first indentation portion 110 may be defined by a bottom surface 111 of the first indentation portion 110, outer peripheral surfaces 112, 113 (see FIG. 5) of the first indentation portion 110, and the first connecting surface 152. The indentation space A2 of the second indentation portion 120 may be defined by a bottom surface 121 of the second indentation portion 120, outer peripheral surfaces 122, 123 (see FIG. 5) of the second indentation portion 120, and the second connecting surface 154.

[0035] The outer peripheral surfaces 112, 113 of the first recess 110 may include one surface 112 located opposite the first connecting surface 152, and a pair of side surfaces 113 (see FIG. 5) connecting the one surface 112 and the first connecting surface 152.

[0036] The outer peripheral surfaces 122, 123 of the second recess 120 may include one surface 122 located opposite the second connecting surface 154, and a pair of side surfaces 123 (see FIG. 5) connecting the one surface 122 and the second connecting surface 154.

[0037] Meanwhile, when the case 10 is unfolded, the first connecting surface 152 may be formed to extend from the lower surface of the first indentation 110 and incline upward, and the second connecting surface 154 may be formed to extend from the lower surface of the second indentation 120 and incline upward. That is, the pair of connecting surfaces 152, 154 included in the connecting portion 150 may be formed to incline in a direction approaching each other as they go upward.

[0038] Therefore, according to the present invention, the vertical cross sections of the first indentation 110 and the second indentation 120 may have a roughly L-shape, as shown in FIG.

[0039] Meanwhile, according to the present invention, when the case 10 is unfolded, the case 10 may be bent in a V-shape in a region where the first outer periphery 310 and the second outer periphery 320 intersect. Fig. 3 illustrates a V-shaped bent portion 200 in a region where the first outer periphery 310 and the second outer periphery 320 intersect. Thus, as illustrated in Fig. 3, when the case 10 is unfolded, the indented space A1 defined by the first indented portion 110 and the indented space A2 defined by the second indented portion 120 may face each other.

[0040] According to conventional technology, in order to manufacture a pouch-type secondary battery, a process is performed in which a portion of a sheet-type casing material having a planar shape is compressed to form an indentation in the sheet-type casing material, and then the sheet-type casing material is folded.

[0041] However, according to the conventional technology, the sheet-type exterior material has a flat shape except for the area where the indentation is formed based on the folded area before folding, so a process of folding the sheet-type exterior material 180 degrees is required. However, in this case, since the angle at which the sheet-type exterior material is folded is large, the shape of the sheet-type exterior material is changed significantly before and after the folding process, which results in a large amount of dead space that does not contribute to improving the capacity of the secondary battery, and a problem occurs in that the appearance of the sheet-type exterior material is significantly deformed.

[0042] However, according to the present invention, the area where the sheet-type exterior material (i.e., the case) is folded has a V-shape, so the angle at which the sheet-type exterior material is folded during the folding process is reduced compared to the conventional case. This makes it possible to minimize changes in the shape of the sheet-type exterior material before and after the folding process, thereby reducing dead space that does not contribute to improving the capacity of the secondary battery, and minimizing deformation of the appearance of the sheet-type exterior material.

[0043] FIG. 4 is an enlarged view of the folding portion, the connecting portion, and the surroundings shown in FIG. 3, and FIG. 5 is a view showing a state in which the secondary battery case according to an embodiment of the present invention is unfolded.

[0044] The first indentation portion 110 and the second indentation portion 120 may be indented by a predetermined depth from the first outer periphery portion 310 and the second outer periphery portion 320, respectively. Fig. 4 illustrates an embodiment in which the first indentation portion 110 is indented by a predetermined depth W1 from the first outer periphery portion 310, and the second indentation portion 120 is indented by a predetermined depth W2 from the second outer periphery portion 320.

[0045] Meanwhile, when the case 10 is unfolded, the first indentation portion 110 and the second indentation portion 120 may have shapes symmetrical to each other with respect to the connecting portion 150. Therefore, referring to FIG. 4, according to one embodiment of the present invention, the depth W1 at which the first indentation portion 110 indents from the first outer periphery portion 310 and the depth W2 at which the second indentation portion 120 indents from the second outer periphery portion 320 may be the same. However, differently, the first indentation portion 110 and the second indentation portion 120 may have shapes asymmetrical to each other. Therefore, according to another embodiment of the present invention, the depth W1 at which the first indentation portion 110 indents from the first outer periphery portion 310 and the depth W2 at which the second indentation portion 120 indents from the second outer periphery portion 320 may be different from each other.

[0046] As described above, the connecting portion 150 may include a first connecting surface 152 formed so as to be inclined upward from one end of the first indentation portion 110, and a second connecting surface 154 formed so as to be inclined upward from one end of the second indentation portion 120. Further referring to FIG. 3, the case 10 according to the present invention may be V-shaped in an area where the first outer periphery portion 310 and the second outer periphery portion 320 intersect when the case 10 is unfolded. Therefore, a bent portion 200 may be formed in the area where the first outer periphery portion 310 and the second outer periphery portion 320 intersect, and the bent portion 200 may have a predetermined angle θ1. The angle θ1 may have a value of 80 degrees to 160 degrees. More specifically, the angle θ1 may be 80 degrees or more and 160 degrees or less.

[0047] 3, one side 112 formed on the opposite side of the connecting portion 150 of the outer circumferential surfaces 112, 113 of the first indentation 110 and the first outer circumferential portion 310 may intersect with each other at a predetermined angle α. In this case, the angle α may be an obtuse angle. Similarly, a predetermined obtuse angle may be formed in an area where one side 122 formed on the opposite side of the connecting portion 150 of the outer circumferential surfaces 122, 123 of the second indentation 120 and the second outer circumferential portion 320 intersect with each other.

[0048] A portion of the indentation space A1 defined by the first indentation portion 110 adjacent to the one side 112 of the first indentation portion 110 and a portion of the indentation space A2 defined by the second indentation portion 120 adjacent to the one side 122 of the second indentation portion 120 may form a void space V1 that is not occupied by the electrode assembly 20 (see FIG. 8) when the case 10 is sealed.

[0049] During the molding process of case 10, the excess space V1 can be reduced by increasing the angle θ1 of folding portion 200 and reducing the clearance between an upper punch (not shown) and a lower die (not shown). However, if the angle θ1 of folding portion 200 is too large, bat-ears may occur when case 10 is sealed or excessive wrinkles may occur around folding portion 200. Therefore, it is important to appropriately design the angle θ1 of folding portion 200.

[0050] Meanwhile, when the case 10 is unfolded, the region 152a where the first indentation 110 and the connecting portion 150 are connected and the region 154a where the second indentation 120 and the connecting portion 150 are connected may be formed with a curved surface. That is, as shown in Fig. 4, the region 152a where the bottom surface 111 of the first indentation 110 and the first connecting surface 152 are connected may be formed with a curved surface having a predetermined radius of curvature R1. Similarly, the region where the bottom surface 121 of the second indentation 120 and the second connecting surface 154 are connected may be formed with a curved surface having a predetermined radius of curvature R2.

[0051] Furthermore, when case 10 is unfolded, the region where first outer periphery 310 and second outer periphery 320 are connected (i.e., bent portion 200) may be formed with a curved surface. Fig. 4 illustrates an embodiment in which region 200 where first outer periphery 310 and second outer periphery 320 are connected is formed with a curved surface having a predetermined radius of curvature R3.

[0052] Furthermore, when case 10 is unfolded, region 150a where first connecting surface 152 and second connecting surface 154 are connected may also be formed with a curved surface. Fig. 4 illustrates an embodiment in which region 150a where first connecting surface 152 and second connecting surface 154 are connected is formed with a curved surface having a predetermined radius of curvature R4.

[0053] For convenience, the regions 152a, 154a where the bottom surfaces 111, 121 of each indentation 110, 120 are connected to each connecting surface 152, 154 may be named the first region, the region 200 where the first outer periphery 310 and the second outer periphery 320 are connected may be named the second region, and the region where the first connecting surface 152 and the second connecting surface 154 are connected to each other may be named the third region.

[0054] The first regions 152a, 154a and the second region 200 may be curved surfaces that are convex downward, and the third region 150a may be curved surfaces that are convex upward.

[0055] The second region 200 and the third region 150a may form a predetermined step t in the vertical direction. The step t may be called a foaming depth.

[0056] In order to reduce the occurrence of bat-ears when sealing the case 10, the step t may be changed according to the angle θ1 of the bent portion 200. However, if the step t is excessively increased, wrinkles may occur around the second region 200 and / or the third region 150a when sealing the case 10, so it is important to appropriately design the angle θ1 of the bent portion 200 and the step t.

[0057] In this case, according to the present invention, when the case 10 is deployed, the radii of curvature R1, R2 of the first regions 152a, 154a may be greater than the radius of curvature R3 of the second region 200 and the radius of curvature R4 of the third region 150a.

[0058] Meanwhile, the regions 152b, 154b where the outer circumferential surfaces of the indentations 110, 120 and the connecting portion 150 are connected may be formed as curved surfaces having a predetermined radius of curvature (eg, within or outside 2 mm).

[0059] More specifically, region 152b where side surface 113 of first indentation 110 and first connecting surface 152 are connected may be formed of a curved surface having a predetermined radius of curvature. Also, region 154b where side surface 123 of second indentation 120 and second connecting surface 154 are connected may be formed of a curved surface having a predetermined radius of curvature. Thus, wrinkles that occur around connecting portion 150 when case 10 is sealed can be alleviated.

[0060] FIG. 6 is a vertical cross-sectional view illustrating a state in which a secondary battery case according to an embodiment of the present invention is unfolded by an external force, and FIG. 7 is a view illustrating a state in which a secondary battery case according to an embodiment of the present invention is unfolded by an external force.

[0061] The state in which case 10 is unfolded by an external force may refer to a state in which, when case 10 is unfolded, an external force acts in a direction in which first outer circumferential portion 310 and second outer circumferential portion 320 are unfolded.

[0062] More specifically, when case 10 is unfolded by an external force, the angle θ2 formed between the portion of first outer periphery 310 located on the opposite side of connecting portion 150 and the portion of second outer periphery 320 located on the opposite side of connecting portion 150 may be greater than the angle θ1 (see Figure 3) formed by incision portion 200 when case 10 is unfolded.

[0063] When case 10 is in a state in which it is deployed by an external force, outer circumferential portion 300 may be formed with deformable portion 330 having a downwardly convex curved shape.

[0064] The deformed portion 330 may have a curved shape that is bent so as to incline downward.

[0065] The deformation portion 330 may be connected to an end of the connection portion 150 in the longitudinal direction of the connection portion 150. That is, a pair of deformation portions 330 connected to both ends of the connection portion 150 may be provided.

[0066] Each deformation portion 330 may be formed across an area from an end of the connecting portion 150 to an end of the outer circumferential portion 300. Each deformation portion 330 may be formed so that its height decreases as it moves from the connecting portion 150 to the end of the outer circumferential portion 300. Also, the width of each deformation portion 330 may increase as it moves toward the end of the outer circumferential portion 300.

[0067] A part of the deformation portion 330 may be located in the first outer periphery 310, and another part may be located in the second outer periphery 320. Thus, each deformation portion 330 may include a region where the first outer periphery 310 and the second outer periphery 320 intersect.

[0068] In addition, the deformation portion 330 may have the lowest height in the region where the first outer periphery portion 310 and the second outer periphery portion 320 intersect, and may become higher as it approaches the sub-deformation portions 310a and 320a described below. That is, each deformation portion 330 may be formed to have the lowest height in the center and to become higher on both sides.

[0069] In this manner, when an external force is applied so that first outer circumferential portion 310 and second outer circumferential portion 320 are expanded while case 10 is in an unfolded state, deformation portion 330 may be formed. Therefore, when an external force is applied so that first outer circumferential portion 310 and second outer circumferential portion 320 are brought close to each other while case 10 is in an unfolded state, a region in outer circumferential portion 300 corresponding to deformation portion 330 may be bent concavely in the opposite direction to deformation portion 330.

[0070] Therefore, when the case 10 is sealed, it is possible to minimize or prevent a phenomenon in which the area of ​​the outer periphery 300 corresponding to the deformation portion 330 protrudes outward from the indentation 100. In other words, it is possible to eliminate or minimize the butt-ear.

[0071] On the other hand, when case 10 is in a state in which it is deployed by an external force, outer circumferential portion 300 may further be formed with sub-deformation portions 310a, 320a having an upwardly convex curved shape.

[0072] The sub-deformation portions 310a and 320a may have a curved shape that is bent so as to incline upward.

[0073] The sub-deformation portions 310a, 320a may include a first sub-deformation portion 310a and a second sub-deformation portion 320a located on both sides of the deformation portion 330. The first sub-deformation portion 310a may be located on one side of the deformation portion 330, in the first outer periphery portion 310. The second sub-deformation portion 320a may be located on the other side of the deformation portion 330, in the second outer periphery portion 320.

[0074] The first sub-deformation portion 310a may be formed over the area from the end of the first indentation portion 110 to the end of the outer circumferential portion 300, and the second sub-deformation portion 320a may be formed over the area from the end of the second indentation portion 120 to the end of the outer circumferential portion 300.

[0075] Unlike the deformation portion 330, the first and second sub-deformation portions 310a and 320a may be formed to have heights that decrease toward both sides.

[0076] Therefore, when an external force acts to bring first outer periphery 310 and second outer periphery 320 closer to each other while case 10 is unfolded, the area in outer periphery 300 corresponding to deformation portion 330 may be bent further concavely in the opposite direction to deformation portion 330, thereby further reducing or eliminating the bat-ear.

[0077] FIG. 8 is a perspective view illustrating a manner in which an electrode assembly is accommodated in a secondary battery case according to the present invention.

[0078] 8, the secondary battery according to the present invention may include an electrode assembly 20 having a structure in which electrodes and separators are alternately arranged, and a case 10. The contents regarding the case 10 are the same as those described above.

[0079] As shown in FIG. 8, the secondary battery according to the present invention can be manufactured by (i) accommodating the electrode assembly 20 in the first indentation 110 (see FIG. 3, etc.) and the second indentation 120 (see FIG. 3, etc.) when the case 10 is unfolded, (ii) folding the area in which the first indentation and the first outer periphery are formed and the area in which the second indentation and the second outer periphery are formed together, and (iii) attaching the first outer periphery and the second outer periphery to each other.

[0080] Although the present invention has been described above using limited embodiments and drawings, the present invention is not limited thereto, and it is of course possible for a person having ordinary knowledge in the technical field to which the present invention pertains to implement various aspects of the present invention within the scope of the technical concept of the present invention and the equivalent scope of the claims described below. [Explanation of symbols]

[0081] 10 Cases 20 Electrode assembly 100 Bay 110 First Bay 120 Second Bay 150 Connection section 152 1st connection surface 154 2nd connection surface 200 Bending part 300 Outer periphery 310 First outer periphery 320 Second outer periphery 330 Deformation Part A1 Indented space formed by the first indentation A2: Indented space formed by the second indentation W1 Depth of the first inlet W2 Depth of the second inlet R1 Radius of curvature of the connecting area between the first indentation and the first connecting surface R2 Radius of curvature of the connecting area between the second indentation and the second connecting surface R3 Radius of curvature of the connecting area between the first and second perimeters R4 Radius of curvature of the connection area between the first and second connection surfaces

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, A first indentation having an indented shape; a second indentation provided on one side of the first indentation and having an indented shape; an outer circumferential portion that surrounds the first indentation portion and the second indentation portion when the case is unfolded; A connecting portion provided between the first indentation portion and the second indentation portion and connecting the first indentation portion and the second indentation portion, When the case is unfolded, the connecting portion is a first connection surface formed to be inclined upward from one end of the first recess; a second connection surface formed to be inclined upward from one end of the second recess, The outer periphery is a first outer circumferential portion formed around the first indentation; A second outer circumferential portion formed around the second indentation, When the above case is developed, a bent portion having a predetermined angle formed by the first outer periphery and the second outer periphery is formed in a region where the first outer periphery and the second outer periphery intersect, The predetermined angle formed by the bent portion has a value of 80 degrees or more and 160 degrees or less, The connecting portion is located between the two folded portions in the longitudinal direction of the connecting portion.

2. At the upper end of the connecting portion, The secondary battery case according to claim 1 , wherein an upper end of the first connecting surface and an upper end of the second connecting surface are connected to each other.

3. When the above case is developed, The secondary battery case according to claim 1 , wherein the first indentation and the second indentation have shapes symmetrical to each other with the connecting portion as the center.

4. When the above case is developed, The secondary battery case according to claim 1 , wherein the indented space A1 formed by the first indentation portion and the indented space A2 formed by the second indentation portion face each other.

5. When the above case is developed, The first connection surface is formed to extend from a lower surface of the first recess and to be inclined upward, The secondary battery case of claim 1 , wherein the second connecting surface is extended from a lower surface of the second recess and inclines upward.

6. When the above case is developed, The secondary battery case according to claim 1 , wherein a region where the first indentation and the connecting portion are connected and a region where the second indentation and the connecting portion are connected are formed with curved surfaces.

7. When the above case is developed, The secondary battery case according to claim 2 , wherein a region where the first connecting surface and the second connecting surface are connected is formed as a curved surface.

8. The secondary battery case according to claim 1 , wherein the bent portion is formed with a curved surface.

9. When the above case is developed, a region where the first indentation and the first connecting surface are connected and a region where the second indentation and the second connecting surface are connected are formed by curved surfaces, A region where the first connecting surface and the second connecting surface are connected is formed by a curved surface, 9. The secondary battery case according to claim 8, wherein a radius of curvature R1 of a region where the first indentation and the first connecting surface are connected by a curved surface and a radius of curvature R2 of a region where the second indentation and the second connecting surface are connected by a curved surface are greater than a radius of curvature R3 of the bent portion and a radius of curvature R4 of a region where the first connecting surface and the second connecting surface are connected by a curved surface.

10. 2 . The secondary battery case according to claim 1 , wherein an angle α formed between an inner surface of the first recessed portion formed on an opposite side of the connecting portion and a region where the first outer periphery intersects with each other is an obtuse angle.

11. an electrode assembly having a structure in which electrodes and separators are alternately arranged; A secondary battery comprising: the secondary battery case according to claim 1 .

12. When an external force acts in a direction in which the first outer circumferential portion and the second outer circumferential portion are deployed in the deployed state of the case, The secondary battery case according to claim 1 , wherein the connecting portion is formed with a deformed portion having a downwardly convex curved shape, the height of which decreases toward an end of the outer periphery.

13. The secondary battery case according to claim 12 , wherein a width of the deformation portion increases toward an end of the outer periphery.

14. The secondary battery case according to claim 12 , wherein the deformation portion includes a region where the first outer periphery and the second outer periphery intersect.

15. When an external force acts in a direction in which the first outer circumferential portion and the second outer circumferential portion are deployed in a deployed state of the case, a first sub-deformation portion located on one side of the deformation portion, having an upward convex shape, and located on the first outer periphery; The secondary battery case according to claim 14 , further comprising a second sub-deformation portion located on the other side of the deformation portion, having an upward convex shape, and located at the second outer periphery.

16. 2. The secondary battery case according to claim 1, wherein a region where an outer peripheral surface of the first indentation portion and the first connecting surface are connected and a region where an outer peripheral surface of the second indentation portion and the second connecting surface are connected are formed by curved surfaces.

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