Secondary battery case and secondary battery

Abstract

To eliminate a dead space occurring in a sealing part of a pouch-type secondary battery manufactured according to the related art, thereby increasing energy density of the secondary battery.SOLUTION: A secondary battery case and a secondary battery are provided. The secondary battery case includes: a recess part recessed downward and having a width W that corresponds to a thickness of the electrode assembly; and a sealing part formed around the recess part when the case is unfolded. At least portions of the sealing part are attached to each other to seal inner surfaces of the recess part against an outside.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0024845, filed March 4, 2019, and all contents disclosed in the documents of that Korean patent application 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, prismatic, pouch, 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 within a sheet-like pouch outer casing.

[0004] According to the prior art, to manufacture a pouch-type secondary battery, a forming process is performed in which a portion of a sheet-like pouch is compressed to an area corresponding to the area of ​​the electrode assembly to form a cup-shaped indentation, and then the electrode assembly is placed 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 portions of the pouches together, is formed by adhering portions that are not pressurized during the forming process. Therefore, due to a step between the unformed sealed portion and the formed cup, a portion of the sealed portion extends beyond the width of the cup. Figure 1 shows a pouch-type secondary battery 1 manufactured using conventional technology, where a portion of the sealed portion 3 formed at the top and bottom of a pouch 2 protrudes by a distance P beyond the width of the cup containing the electrode assembly.

[0006] Such a protruding region increases dead space in the secondary battery, which 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, the problem to be solved by 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 conventional technology. [Means for solving the problem]

[0008] According to one aspect of the present invention to achieve the above object, there is provided a secondary battery case capable of accommodating an electrode assembly having a structure in which electrodes and separators are alternately arranged, the secondary battery case including: a downwardly indented portion having a width W corresponding to a thickness of the electrode assembly; and a sealing portion formed around a periphery of the indented portion when the case is unfolded, wherein at least a portion of the sealing portion is attached to each other to seal an inner surface of the indented portion from the outside.

[0009] The case may further include an inclined portion provided adjacent to the indentation portion, and having a surface that slopes downward toward the outside in the opposite direction to the indentation portion when the case is unfolded, and the sealing portion may be formed to surround the indentation portion and the inclined portion when the case is unfolded.

[0010] The inclined portion may include a first inclined portion provided on one side of the indentation when the case is unfolded; and a second inclined portion provided on the other side of the indentation when the case is unfolded.

[0011] When the case is unfolded, the sum of the height D1 of the step between the first inclined portion and the sealing portion and the height D2 of the step between the second inclined portion and the sealing portion can correspond to the width W of the recessed portion.

[0012] The sealed portion has a fold line L formed thereon, which is a line along which the sealed portion is folded. The fold line L may include a first fold line L1 extending outward from a point where the first inclined portion, the indented portion, and the sealed portion meet one another; a second fold line L2 extending outward from a point where the second inclined portion, the indented portion, and the sealed portion meet one another and meeting the first fold line L1; and a third fold line L3 extending outward from a point where the first fold line L1 and the second fold line L2 meet one another.

[0013] The fold line L may further include a fourth fold line L4 extending from a point where the first fold line, the second fold line, and the third fold line meet along the first inclined portion and the second inclined portion.

[0014] The region of the sealed portion formed on the outer side of the fourth folding line L4 may be attached to another region of the sealed portion.

[0015] When the case is unfolded, a sealing indentation is formed in the sealing portion, indenting in the direction in which the indentation indentation indents, the sealing indentation is formed alongside the indentation, and the width W1 of the sealing indentation can correspond to the width W of the indentation.

[0016] The sealed indentation portion includes a first indentation surface and a second indentation surface respectively adjacent to the indentation portion, and the first indentation surface and the second indentation surface meet to form a V-shape. The sealed portion has a fold line L' along which the sealed portion is folded. The fold line L' may include a first fold line L'1 formed at the boundary between the first indentation surface and a region of the sealed portion adjacent to the first inclined portion; a second fold line L'2 formed at the boundary between the second indentation surface and a region of the sealed portion adjacent to the second inclined portion; and a third fold line L'3 formed at the boundary between the first indentation surface and the second indentation surface.

[0017] The fold line L' may further include a fourth fold line L'4 extending in both directions from a point on the third fold line L'3 along the first inclined portion and the second inclined portion.

[0018] The region of the sealed portion formed on the outside of the fourth folding line L'4 may be attached to another region of the sealed portion.

[0019] The sealing indentation may include a third indentation surface and a fourth indentation surface respectively adjacent to the indentation, the third indentation surface and the fourth indentation surface meeting each other to form a V-shape, the third indentation surface may include a first inclined indentation surface that is inclined downward from the indentation toward the fourth indentation surface and inclined upward toward an outer side of the sealing portion, and a second inclined indentation surface that is formed by extending flat outward from the first inclined indentation surface, the fourth indentation surface may include a third inclined indentation surface that is inclined upward from the indentation toward the third indentation surface and outward, and a fourth inclined indentation surface that is formed by extending outward from the third inclined indentation surface.

[0020] The sealed indentation portion has a fold line L" formed therein, which is a line along which the sealed portion is folded, and the fold line L" may include a first fold line L"1 formed at the boundary between the third indentation surface and a region of the sealed portion adjacent to the first inclined portion; a second fold line L"2 formed at the boundary between the fourth indentation surface and a region of the sealed portion adjacent to the second inclined portion; and a third fold line L"3 formed at the boundary between the third indentation surface and the fourth indentation surface.

[0021] The fold line L'' may further include a fourth fold line L''4 extending from a point on the third fold line L''3 along the first inclined portion and the second inclined portion.

[0022] The region of the sealed portion formed on the outside of the fourth fold line L''4 may be attached to another region of the sealed portion.

[0023] The inclined portion may be provided on one side of the indentation when the case is unfolded, and may further include a flat portion that is provided on the other side of the indentation when the case is unfolded, forming a flat surface.

[0024] The case may further include a flat portion that is provided between the inclined portion and the recessed portion and forms a flat surface when the case is unfolded.

[0025] According to another aspect of the present invention, there is provided a secondary battery including the electrode assembly and the secondary battery case. [Effects of the Invention]

[0026] According to the present invention, the dead space generated at the sealed portion of the pouch-type secondary battery can be eliminated, and therefore the energy density of the secondary battery can be increased. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a diagram showing the structure of a secondary battery manufactured by a conventional technique. [Figure 2] 1 is a perspective view showing the secondary battery case according to a first embodiment of the present invention when unfolded. FIG. [Figure 3] 3 is a cross-sectional view showing the appearance of the secondary battery case taken along line AA in FIG. 2. FIG. [Figure 4] 1 is a perspective view illustrating a sealing portion and its surroundings when the sealing portions are attached to each other in a secondary battery case according to a first embodiment of the present invention; [Figure 5] FIG. 10 is a perspective view showing the secondary battery case according to a second embodiment of the present invention when unfolded. [Figure 6] 6 is a cross-sectional view showing the appearance of the secondary battery case taken along line BB in FIG. 5. FIG. [Figure 7] 10 is a perspective view illustrating a sealing portion and its surroundings when the sealing portions are attached to each other in a secondary battery case according to a second embodiment of the present invention; FIG. [Figure 8] FIG. 10 is a perspective view showing the secondary battery case according to a third embodiment of the present invention when unfolded. [Figure 9]9 is a cross-sectional view showing the appearance of the secondary battery case taken along line CC in FIG. 8. FIG. [Figure 10] 10 is a perspective view illustrating a sealing portion and its surroundings when the sealing portions are attached to each other in a secondary battery case according to a third embodiment of the present invention; FIG. [Figure 11] FIG. 1 is a cross-sectional view showing a first modified example of a secondary battery case according to the present invention. [Figure 12] FIG. 10 is a cross-sectional view showing a second modified example of the secondary battery case according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, the structure of a secondary battery case and a secondary battery according to the present invention will be described with reference to the drawings.

[0029] (Case for secondary batteries) Fig. 2 is a perspective view showing the appearance of the secondary battery case according to the first embodiment of the present invention when unfolded, and Fig. 3 is a cross-sectional view showing the appearance of the secondary battery case taken along line AA in Fig. 2.

[0030] The secondary battery case 10 according to the present invention may be a sheet-like exterior material, and the secondary battery according to the present invention may be a pouch-type secondary battery.

[0031] As shown in FIG. 2, the secondary battery case 10 according to the first embodiment of the present invention may be configured to accommodate an electrode assembly (not shown) having a structure in which electrodes and separators are alternately arranged.

[0032] The secondary battery case 10 according to the first embodiment of the present invention may include an indentation 100 having a predetermined width W and indented downward. The predetermined width W of the indentation 100 may correspond to the thickness of the electrode assembly to be accommodated inside the case 10. The phrase "the predetermined width of the indentation corresponds to the thickness of the electrode assembly to be accommodated inside the case" may be interpreted as including not only the case where the width of the indentation 100 and the thickness of the electrode assembly are the same, but also the case where there is a difference in the extent to which the electrode assembly can be sandwiched between the indentation 100 of the case 10 in the thickness direction.

[0033] Referring now to FIG. 2, the case 10 according to the present invention may include a sealing portion 300. The sealing portion 300 may be attached to the case 10 of the secondary battery to seal the electrode assembly inside the case 10 from the outside. Alternatively, the sealing portion 300 may be attached to the case 10 to seal the inner surface of the indentation 100 from the outside. When the case 10 is unfolded, the sealing portion 300 may be formed around the periphery of the indentation 100. As shown in FIG. 2, when the unfolded case 10 is viewed from above, the sealing portion 300 may be formed to surround the periphery of the indentation 100. As shown in FIGS. 2 and 3, the vertical cross section of the indentation 100 in the unfolded case 10 may have an angular U-shape. However, the vertical cross section of the indentation 100 may have various shapes.

[0034] 2 and 3, the secondary battery case 10 according to the present invention may be formed with an inclined portion 200 that forms a downwardly inclined surface when the case 10 is unfolded. As shown in FIGS. 2 and 3, the inclined portion 200 may be provided adjacent to the indented portion 100.

[0035] 2 and 3, when the case 10 is unfolded, the inclined portion 200 may be formed to slope downward toward the outside in the direction opposite to the area adjacent to the indentation 100. Alternatively, the inclined portion 200 may be formed on both sides of the indentation 100. That is, when the case 10 is unfolded, the inclined portion 200 may include a first inclined portion 202 provided adjacent to one side of the indentation 100 and a second inclined portion 204 provided adjacent to the other side of the indentation 100, which is opposite to the one side.

[0036] When the case 10 according to the present invention is provided with the indentation portion 100 and the inclined portion 200, the sealing portion 300 may be formed to surround the peripheries of the indentation portion 100 and the inclined portion 200 when the case 10 is unfolded. That is, as shown in Fig. 2, the sealing portion 300 may be provided adjacent to the boundary of the indentation portion 100 and adjacent to the boundary of the inclined portion 200. Meanwhile, as described above, since the inclined portion 200 may be formed to slope downward, a step may be formed between the inclined portion 200 and the sealing portion 300.

[0037] Meanwhile, the secondary battery case 10 according to the present invention may have a predetermined thickness when the sealing portion 300 is attached to the case 10. In this case, the thickness of the case 10 may be the same as the width of the indentation 100. For this reason, if the inclined portions 200 are formed on both sides of the indentation 100 as shown in FIG. 3 , when the case 10 is unfolded, the sum of the height D1 of the step between the first inclined portion 202 and the sealing portion 300 and the height D2 of the step between the second inclined portion 204 and the sealing portion 300 may correspond to the width W of the indentation 100. For example, the sum of D1 and D2 may be the same as W. Alternatively, D1 and D2 may be the same as each other, in which case D1 and D2 may each be 0.5 times W.

[0038] FIG. 4 is a perspective view showing the sealing portion and the surrounding area of ​​the sealing portion when the sealing portions are attached to each other in the secondary battery case according to the first embodiment of the present invention.

[0039] 2 and 4, when the sealing portions 300 of the cases 10 according to the first embodiment of the present invention are attached to each other, a portion of the sealing portion 300 may be folded. When the sealing portions 300 of the cases 10 according to the first embodiment of the present invention are attached to each other, a folding line L, which is the area where the sealing portion 300 is folded, is shown by a dotted line.

[0040] The fold line L formed in the sealing portion 300 of the secondary battery case 10 according to the first embodiment of the present invention may include a first fold line L1 extending outward from a point where the first inclined portion 202, the indented portion 100, and the sealing portion 300 meet, and a second fold line L2 extending outward from a point where the second inclined portion 204, the indented portion 100, and the sealing portion 300 meet. In this case, as shown in Fig. 2, the first fold line L1 and the second fold line L2 may meet each other. The lengths of the first fold line L1 and the second fold line L2 may be the same.

[0041] 2, the fold line L of the secondary battery case 10 according to the first embodiment of the present invention may further include a third fold line L3 extending outward from a point where the first fold line L1 and the second fold line L2 meet. The fold line L may further include a fourth fold line L4 extending from a point where the first fold line L1, the second fold line L2, and the third fold line L3 meet along the first inclined portion 202 or the second inclined portion 204. FIG. 2 shows the case where the fourth fold line L4 extends along the first inclined portion 202 and the second inclined portion 204.

[0042] Meanwhile, according to the first embodiment of the present invention, the fold line L may further include a fifth fold line L5 extending from an end of the fourth fold line L4 toward the inclined portion 200. FIG. 2 shows a case where the fifth fold line L5 extends from an end of the fourth fold line L4 to a sharp corner point of the boundary between the sealed portion 300 and the inclined portion 200.

[0043] According to the first embodiment of the present invention, when the sealing parts 300 are attached to each other, the folding line L formed in the sealing parts of the cases 10 is folded. The appearance of the sealing parts and the surrounding area of ​​the sealing parts when the sealing parts 300 of the cases 10 are attached to each other according to the first embodiment of the present invention is shown in FIG.

[0044] 4, when the sealing portions 300 of the secondary battery case 10 according to the first embodiment of the present invention are attached to each other, the sealing portions 300 may be folded along fold lines L. According to the first embodiment of the present invention, the first fold line L1, the second fold line L2, the third fold line L3, and the fourth fold line L4 may meet at one point. Meanwhile, the first to fourth fold lines may be formed in a region of the sealing portion from which the electrode lead 20 protrudes. In addition, the fifth fold line L5 may extend inward from an end of the fourth fold line L4.

[0045] At this time, as shown in Fig. 4, the regions of the sealed portion formed outward from the fourth fold line L4 and the fifth fold line L5 may be attached to other regions of the sealed portion, and the electrode lead 20 may protrude through the attached regions.

[0046] On the other hand, as shown in Fig. 4, a region of the sealed portion formed inward from the fourth fold line L4 and the fifth fold line L5 may be spaced apart from other regions of the sealed portion. An empty space may be formed between the spaced apart regions. That is, as shown in Fig. 4, according to the first embodiment of the present invention, a region of the sealed portion 300 formed inward from the fourth fold line L4 and the fifth fold line L5 may form a space forming portion 400 in which an empty space is formed therein.

[0047] 2 to 4, in the case of the secondary battery case 10 manufactured according to the first embodiment of the present invention, the protrusion of the sealing portion in the width direction of the region where the electrode assembly is provided can be minimized. In particular, referring to FIG. 4, it can be seen that the points that protrude most in the width direction of the region where the electrode assembly is provided are formed at the points where the first to fourth fold lines (L1, L2, L3, L4) meet, and that even at these points, a distance I is provided inward in the width direction of the region where the electrode assembly is provided. Therefore, the generation of dead space that does not contribute to the capacity of the secondary battery can be minimized, resulting in an increase in the energy density of the secondary battery.

[0048] FIG. 5 is an oblique view showing the appearance of a secondary battery case according to a second embodiment of the present invention when unfolded, and FIG. 6 is a cross-sectional view showing the appearance of the secondary battery case cut along line BB in FIG. 5.

[0049] The details regarding the recessed portion, the inclined portion including the first inclined portion and the second inclined portion, and the sealing portion of the secondary battery case according to the first embodiment of the present invention can also be applied to the secondary battery case according to the second embodiment of the present invention. Below, the structure of the secondary battery case according to the second embodiment of the present invention will be described, focusing on the differences from the secondary battery case according to the first embodiment of the present invention. That is, the details regarding the secondary battery case according to the first embodiment of the present invention described above can also be applied to the secondary battery case according to the second embodiment of the present invention, to the extent that they do not contradict the details described below.

[0050] 5, when the secondary battery case 10 according to the second embodiment of the present invention is unfolded, the sealing portion 300 may have a sealing indentation 302 formed therein that is indented in the same direction as the indentation 100. In this case, as shown in FIG. 5, the sealing indentation 302 may be formed in a region of the sealing portion 300 adjacent to the indentation 100, or the sealing indentation 302 may be formed alongside the indentation 100.

[0051] 6, the sealing indentation 302 may have a predetermined width W1. In this case, the width W1 of the sealing indentation 302 may be defined as the width at the point where the sealing indentation 302 begins to indent downward (i.e., the uppermost end of the sealing indentation). Meanwhile, the width W1 of the sealing indentation 302 may correspond to the width W of the indentation 100 (see FIG. 3). For example, the width of the sealing indentation 302 may be the same as the width of the indentation 100.

[0052] 5 and 6, the sealing indentation 302 in the secondary battery case 10 according to the second embodiment of the present invention may include a first indentation surface 302a and a second indentation surface 302b. As shown in FIG. 5, the first indentation surface 302a and the second indentation surface 302b may be adjacent to the indentation 100, respectively.

[0053] The first indented surface 302a and the second indented surface 302b may be formed to slope downward toward each other. Therefore, the first indented surface 302a and the second indented surface 302b may meet at their lower ends to form a V-shape. That is, as shown in FIG. 6, according to the second embodiment of the present invention, the vertical cross section of the sealing indentation 302 may have a V-shape.

[0054] FIG. 7 is a perspective view showing the appearance of the sealing portion and the surrounding area of ​​the sealing portion when the sealing portions are attached to each other in the secondary battery case according to the second embodiment of the present invention.

[0055] As in the first embodiment of the present invention, in the second embodiment of the present invention, the sealing part 300 may be formed with a fold line L' along which the sealing part 300 is bent. That is, as shown in Figures 5 and 7, when the sealing parts 300 of the cases 10 according to the second embodiment of the present invention are attached to each other, a portion of the sealing part 300 may be bent. The fold line L', which is the area along which the sealing part 300 is bent when the sealing parts 300 of the cases 10 according to the second embodiment of the present invention are attached to each other, is shown by a dotted line.

[0056] 5, the fold line L' formed in the sealing portion 300 of the secondary battery case 10 according to the second embodiment of the present invention may include a first fold line L'1 formed at the boundary between the first indented surface 302a and a region of the sealing portion 300 adjacent to the first inclined portion 202, and a second fold line L'2 formed at the boundary between the second indented surface 302b and a region of the sealing portion 300 adjacent to the second inclined portion 204. Unlike the first embodiment of the present invention, in the second embodiment of the present invention, the first fold line L'1 and the second fold line L'2 may be spaced apart from each other, as shown in FIG.

[0057] Next, referring to FIG. 5, the fold line L' of the secondary battery case 10 according to the second embodiment of the present invention may further include a third fold line L'3 formed at the boundary between the first concave surface 302a and the second concave surface 302b.

[0058] In addition, the fold line L' may further include a fourth fold line L'4 extending in both directions from a point on the third fold line L'3 along the first inclined portion 202 and the second inclined portion 204. Figure 5 shows the case where the fourth fold line L'4 extends along the first inclined portion 202 and the second inclined portion 204.

[0059] Meanwhile, according to the second embodiment of the present invention, the fold line L' may further include a fifth fold line L'5 extending from an end of the fourth fold line L'4 toward the inclined portion 200. Fig. 5 shows a case where the fifth fold line L'5 extends from an end of the fourth fold line L'4 to a sharp corner point of the boundary between the sealed portion 300 and the inclined portion 200.

[0060] Similar to the first embodiment of the present invention, according to the second embodiment of the present invention, when the sealing portions 300 are attached to each other, the folding line L' formed on the sealing portions of the cases 10 is bent. The appearance of the sealing portions and the surrounding area of ​​the sealing portions when the sealing portions 300 of the cases 10 are attached to each other according to the second embodiment of the present invention is shown in FIG.

[0061] 7, when the sealing parts 300 of the secondary battery case 10 according to the second embodiment of the present invention are attached to each other, the sealing parts 300 may be folded along folding lines L', etc. According to the second embodiment of the present invention, the first folding line L'1 and the fourth folding line L'4 may meet at one point, the second folding line L'2 (not shown in FIG. 7) and the fourth folding line L4 may meet at one point, and the third folding line L'3 and the fourth folding line L'4 may also meet at one point.

[0062] Meanwhile, similar to the first embodiment of the present invention, in the second embodiment of the present invention, the first to fourth fold lines may be formed in the region of the sealed portion from which the electrode lead 20 protrudes. In addition, the fifth fold line L'5 may extend inward from the end of the fourth fold line L'4.

[0063] 7, regions of the sealed portion formed outward from the fourth fold line L'4 and the fifth fold line L'5 may be attached to other regions of the sealed portion, and the electrode leads 20 may protrude through the attached regions.

[0064] On the other hand, as shown in Fig. 7, a region of the sealed portion formed inward with respect to the fourth fold line L'4 and the fifth fold line L'5 may be spaced apart from other regions of the sealed portion. An empty space may be formed between the spaced apart regions. That is, as shown in Fig. 7, according to the second embodiment of the present invention, a region of the sealed portion 300 formed inward with respect to the fourth fold line L'4 and the fifth fold line L'5 may form a space forming portion 400 in which an empty space is formed.

[0065] 5 to 7, the secondary battery case 10 manufactured according to the second embodiment of the present invention can also minimize the protrusion of the sealing portion in the width direction of the region where the electrode assembly is provided. In particular, referring to FIG. 7, it can be seen that the point where the greatest protrusion in the width direction of the region where the electrode assembly is provided is formed at the point where the third fold line L'3 and the fourth fold line L'4 meet, and that this point is also located inward by I in the width direction of the region where the electrode assembly is provided. Therefore, the second embodiment of the present invention can also minimize the occurrence of dead space that does not contribute to the capacity of the secondary battery, thereby increasing the energy density of the secondary battery.

[0066] FIG. 8 is an oblique view showing the appearance of a secondary battery case according to a third embodiment of the present invention when unfolded, and FIG. 9 is a cross-sectional view showing the appearance of the secondary battery case cut along line CC in FIG. 8.

[0067] The details regarding the recessed portion, the inclined portion including the first inclined portion and the second inclined portion, and the sealing portion of the secondary battery case according to the first embodiment of the present invention can also be applied to the secondary battery case according to the third embodiment of the present invention. Below, the structure of the secondary battery case according to the third embodiment of the present invention will be described, focusing on the differences from the secondary battery case according to the first embodiment of the present invention. That is, the details regarding the secondary battery case according to the first embodiment of the present invention described above can also be applied to the secondary battery case according to the third embodiment of the present invention, to the extent that they do not contradict the details described below.

[0068] 8, when the secondary battery case 10 according to the third embodiment of the present invention is unfolded, the sealing portion 300 may have a sealing indentation 302 that is indented in the same direction as the indentation 100. In this case, as shown in FIG. 8, the sealing indentation 302 may be formed in a region of the sealing portion 300 adjacent to the indentation 100, or the sealing indentation 302 may be formed alongside the indentation 100.

[0069] 8 and 9, the sealing indentation 302 in the secondary battery case 10 according to the third embodiment of the present invention may include a third indentation surface 302c and a fourth indentation surface 302d. As shown in FIG. 8, the third indentation surface 302c and the fourth indentation surface 302d may be provided adjacent to the indentation 100, respectively.

[0070] Also, similar to the second embodiment of the present invention, in the third embodiment of the present invention, the third indented surface 302c and the fourth indented surface 302d may be formed to slope downward toward each other. Therefore, the third indented surface 302c and the fourth indented surface 302d may meet at their lower ends to form a V-shape. That is, similar to the second embodiment of the present invention, the vertical cross section of the sealing indentation 302 according to the third embodiment of the present invention may have a V-shape.

[0071] However, unlike the second embodiment of the present invention, in the third embodiment of the present invention, when the case is unfolded and then cut in the CC direction in Fig. 8, the sealing indentation 302 may be divided into an inclined region and a flat region. That is, as shown in Figs. 8 and 9, according to the third embodiment of the present invention, the third indentation surface 302c of the sealing indentation 302 may include a first inclined indentation surface 302c' that is inclined downward from the indentation 100 toward the fourth indentation surface 302d and inclined upward toward the outside of the sealing part 300, and a second inclined indentation surface 302c' that is inclined downward toward the fourth indentation surface 302d and extends flat from the first inclined indentation surface 302c' toward the outside of the sealing part 300. Furthermore, according to the third embodiment of the present invention, the fourth indentation surface 302d of the sealing indentation 302 may include a third inclined indentation surface that is inclined downward from the indentation 100 toward the third indentation surface 302c and inclined upward toward the outside of the sealing portion 300, and may further include a fourth inclined indentation surface that is inclined downward toward the third indentation surface 302c and extends flat from the third inclined indentation surface toward the outside of the sealing portion 300.

[0072] FIG. 10 is a perspective view showing the appearance of the sealing portion and the surrounding area of ​​the sealing portion when the sealing portions are attached to each other in the secondary battery case according to the third embodiment of the present invention.

[0073] As in the first embodiment of the present invention, in the third embodiment of the present invention, the sealing part 300 may be formed with a fold line L" along which the sealing part 300 is bent. That is, as shown in FIGS. 8 and 10, when the sealing parts 300 of the cases 10 according to the second embodiment of the present invention are attached to each other, a portion of the sealing part 300 may be bent. When the sealing parts 300 of the cases 10 according to the third embodiment of the present invention are attached to each other, the fold line L" along which the sealing part 300 is bent is shown by a dotted line.

[0074] As shown in FIG. 8, the fold line L″ formed in the sealing portion 300 of the secondary battery case 10 according to the third embodiment of the present invention may include a first fold line L″1 formed at the boundary between the third indented surface 302c and a region of the sealing portion 300 adjacent to the first inclined portion 202, and a second fold line L″2 formed at the boundary between the fourth indented surface 302d and a region of the sealing portion 300 adjacent to the second inclined portion 204. In this case, as in the case of the second embodiment of the present invention, in the third embodiment of the present invention, the first fold line L″1 and the second fold line L″2 may be spaced apart from each other as shown in FIG. 8.

[0075] Next, referring to FIG. 8, the fold line L″ of the secondary battery case 10 according to the third embodiment of the present invention may further include a third fold line L″3 formed at the boundary between the third concave surface 302c and the fourth concave surface 302d.

[0076] In addition, the fold line L" may further include a fourth fold line L"4 extending in both directions from a point on the third fold line L"3 along the first inclined portion 202 and the second inclined portion 204. FIG. 8 shows the case where the fourth fold line L"4 extends along the first inclined portion 202 and the second inclined portion 204.

[0077] Meanwhile, according to the third embodiment of the present invention, the fold line L" may further include a fifth fold line L"5 extending from an end of the fourth fold line L"4 toward the inclined portion 200. FIG. 8 shows a case where the fifth fold line L"5 extends from an end of the fourth fold line L"4 to a sharp corner point of the boundary between the sealed portion 300 and the inclined portion 200.

[0078] Similar to the first embodiment of the present invention, according to the third embodiment of the present invention, when the sealing parts 300 are attached to each other, the folding line L″ formed on the sealing parts of the cases 10 is folded. The appearance of the sealing parts and the surrounding area of ​​the sealing parts when the sealing parts 300 of the cases 10 are attached to each other according to the third embodiment of the present invention is shown in FIG.

[0079] As shown in FIG. 10, when the sealing portions 300 of the secondary battery case 10 according to the third embodiment of the present invention are attached to each other, the sealing portions 300 may be folded along fold lines L" and the like. According to the third embodiment of the present invention, the first fold line L"1 and the fourth fold line L"4 may meet at one point, the second fold line L"2 (not shown in FIG. 10) and the fourth fold line L"4 may meet at one point, and the third fold line L"3 and the fourth fold line L"4 may also meet at one point.

[0080] Meanwhile, similar to the first embodiment of the present invention, in the third embodiment of the present invention, the first to fourth fold lines may be formed in the region of the sealed portion from which the electrode lead 20 protrudes. In addition, the fifth fold line L"5 may extend inward from an end of the fourth fold line L"4.

[0081] At this time, as shown in FIG. 10, regions of the sealed portion formed outward from the fourth fold line L''4 and the fifth fold line L''5 may be attached to other regions of the sealed portion. At this time, as shown in FIG. 10, the electrode lead 20 may protrude through the attached regions.

[0082] On the other hand, as shown in FIG. 10, a region of the sealed portion formed inward from the fourth fold line L"4 and the fifth fold line L"5 may be spaced apart from other regions of the sealed portion. An empty space may be formed between the spaced apart regions. That is, as shown in FIG. 10, according to the third embodiment of the present invention, a region of the sealed portion 300 formed inward from the fourth fold line L"4 and the fifth fold line L"5 may form a space forming portion 400 in which an empty space is formed therein.

[0083] 8 to 10, the secondary battery case 10 manufactured according to the second embodiment of the present invention can also minimize the protrusion of the sealing portion in the width direction of the region where the electrode assembly is provided. In particular, referring to FIG. 10, the point where the most protrusion in the width direction of the region where the electrode assembly is provided is formed at the point where the third fold line L"3 and the fourth fold line L"4 meet, and it can be seen that this point is also located inward by I in the width direction of the region where the electrode assembly is provided. Therefore, the third embodiment of the present invention can also minimize the generation of dead space that does not contribute to the capacity of the secondary battery, thereby increasing the energy density of the secondary battery.

[0084] FIG. 11 is a cross-sectional view showing a first modified example of a secondary battery case according to the present invention.

[0085] In the secondary battery case 10 according to the present invention, the inclined portion 200 may be formed on only one side of the indentation 100. That is, according to a first modified example of the secondary battery case according to the present invention, when the case 10 is unfolded, the inclined portion 200 may be provided on one side of the indentation 100, and a flat portion 250 having a flat surface may be provided on the other side of the indentation 100. In this case, the height D of the step between the inclined portion 200 and the sealing portion 300 may correspond to the width W of the indentation 100. For example, D may be the same as W.

[0086] FIG. 12 is a cross-sectional view showing a second modified example of the secondary battery case according to the present invention.

[0087] According to a second modified example of the secondary battery case of the present invention, when the case 10 is unfolded, both sides of the indentation 100 may be formed with both an inclined region and a flat region. That is, as shown in Fig. 12, the secondary battery case 10 according to the second modified example of the present invention may be formed with an inclined region 200 on both sides of the indentation 100, and a flat region 250 provided between the inclined region 200 and the indentation 100 and forming a flat surface.

[0088] Meanwhile, the secondary battery according to the present invention may include an electrode assembly and a secondary battery case that accommodates the electrode assembly. The description of the secondary battery case is the same as that described above.

[0089] Although the present invention has been described above using limited embodiments and drawings, the present invention is not limited thereto, and it goes without saying that various implementations of the present invention are possible within the technical spirit of the present invention and the scope of the claims set forth below by a person having ordinary skill in the art to which the present invention pertains. [Explanation of symbols]

[0090] 1. Pouch-type secondary battery 2 pouches 3 Sealed part 10 cases 20 electrode leads 100 Bay 200 Slope 202 1st slope section 204 2nd slope part 250 Plane section 300 Sealed part 302 Sealed Bay 302a 1st bay entrance 302b 2nd Bay Entrance 302c 3rd bay entrance 302c' 1st inclined bay entrance 302c” 2nd sloping bay entrance 302d 4th bay entrance 400 Space formation part L' bending line L'1 1st folding line L'2 2nd folding curve L'3 3rd fold curve L'4 4th fold curve L1 1st folding line L2 2nd fold curve L3 3rd fold curve L4 4th fold curve W width W1 width

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 downwardly indented portion having a width W corresponding to the thickness of the electrode assembly; a sloped portion provided adjacent to the recessed portion, which forms a surface that slopes downward toward the outside in the opposite direction to the recessed portion when the case is unfolded; and a sealing portion formed around the periphery of the recessed portion and the inclined portion when the case is unfolded; The sealing portions are at least partially attached to each other to seal the inner surface of the recessed portion from the outside, The uppermost end of the inclined portion is connected to the inner surface of the indentation portion, The sealing portion has a plurality of folding lines formed by folding the sealing portion, A space forming portion is formed inside the bending of the plurality of bending lines, the space forming portion is a portion of the inside of the attached portions of the sealing portion, the portion being opposed to and spaced apart from one another, and forming a space between the adjacent regions; the space forming portion is formed between the inclined portion and the plurality of bending lines, The secondary battery case has a maximum protruding point of the sealing portion, the maximum protruding point being located inward by a predetermined length based on the width of the region where the electrode assembly is provided.

2. The inclined portion is a first inclined portion provided on one side of the recessed portion when the case is unfolded; and The secondary battery case according to claim 1 , further comprising: a second inclined portion provided on the other side of the recessed portion when the case is unfolded.

3. 3. The secondary battery case according to claim 2, wherein when the case is unfolded, a sum of a height D1 of a step between the first inclined portion and the sealing portion and a height D2 of a step between the second inclined portion and the sealing portion corresponds to a width W of the recessed portion.

4. The plurality of bending lines are a first fold line L1 extending outward from a point where the first inclined portion, the indented portion, and the sealed portion meet one another; a second fold line L2 extending outward from a point where the second inclined portion, the indented portion, and the sealed portion meet each other and meeting the first fold line L1; and The secondary battery case according to claim 2 or 3, further comprising a third fold line (L3) extending outward from a point where the first fold line (L1) and the second fold line (L2) meet each other.

5. The plurality of bending lines are 5. The secondary battery case according to claim 4, further comprising: a fourth fold line L4 extending from a point where the first fold line, the second fold line, and the third fold line meet along the first inclined portion and the second inclined portion.

6. The secondary battery case of claim 5 , wherein an outer region of the sealing portion formed on the basis of the fourth folding line (L4) is attached to another region of the sealing portion.

7. When the case is unfolded, a sealing indentation is formed in the sealing portion, the indentation indenting in the direction of the indentation, The sealing indentation is formed alongside the indentation, 7. The secondary battery case according to claim 2, wherein a width W1 of the sealing indentation corresponds to a width W of the indentation.

8. The sealing indentation is a first indentation surface and a second indentation surface provided adjacent to the indentation portion, respectively; the first indented surface and the second indented surface meet to form a V-shape; The plurality of bending lines are a first fold line L′1 formed at the boundary between the first indented surface and a region of the sealed portion adjacent to the first inclined portion; a second fold line L'2 formed at the boundary between the second indented surface and a region of the sealed portion adjacent to the second inclined portion; and The secondary battery case according to claim 7 , further comprising: a third fold line L′3 formed at a boundary between the first indented surface and the second indented surface.

9. The plurality of bending lines are The secondary battery case according to claim 8 , further comprising a fourth fold line L′4 extending in both directions from a point on the third fold line L′3 along the first inclined portion and the second inclined portion.

10. The secondary battery case of claim 9, wherein an outer region of the sealing part formed on the basis of the fourth folding line (L'4) is attached to another region of the sealing part.

11. The sealing indentation is a third indentation surface and a fourth indentation surface provided adjacent to the indentation portion, respectively; the third indented surface and the fourth indented surface meet to form a V-shape; The third bay surface is a first inclined indented surface that is inclined downward from the indented portion toward the fourth indented surface and inclined upward toward an outer side of the sealing portion; and a second inclined indented surface extending flatly outward from the first inclined indented surface; The fourth bay surface is a third inclined indentation surface formed so as to slope upward from the indentation portion toward the third indentation surface and outward; and 11. The secondary battery case according to claim 7, further comprising: a fourth inclined recessed surface formed by extending outward from the third inclined recessed surface.

12. The plurality of bending lines are a first fold line L″1 formed at the boundary between the third indented surface and a region of the sealing portion adjacent to the first inclined portion; a second fold line L″2 formed at the boundary between the fourth indented surface and a region of the sealed portion adjacent to the second inclined portion; and The secondary battery case according to claim 11 , further comprising a third fold line L″3 formed at a boundary between the third indented surface and the fourth indented surface.

13. The plurality of bending lines are The secondary battery case of claim 12 , further comprising: a fourth fold line L″4 extending from a point on the third fold line L″3 along the first inclined portion and the second inclined portion.

14. The secondary battery case of claim 13 , wherein an outer region of the sealing part formed on the basis of the fourth fold line L″4 is attached to another region of the sealing part.

15. an electrode assembly; and A secondary battery comprising the secondary battery case according to any one of claims 1 to 14.

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