Sealing block for preventing cracks in pouch-type battery cases, method for sealing pouch-type battery cases using the same, and pouch-type secondary battery manufactured using the same

Abstract

The present invention relates to a sealing block for preventing cracks in a pouch-type battery case, a sealing method for a pouch-type battery case using the same, and a pouch-type secondary battery manufactured using the same. The sealing block according to the present invention is formed in an inclined shape so that it can perform R-sealing while minimizing the influence on the electrode assembly, specifically the separator.

Description

[Technical Field]

[0001] The present invention relates to a sealing block for preventing cracks in a pouch-type battery case, a method for sealing a pouch-type battery case using the sealing block, and a pouch-type secondary battery manufactured using the sealing block. [Background technology]

[0002] Lithium secondary batteries are classified into cylindrical batteries, prismatic batteries, and pouch batteries depending on the shape of the case. Cylindrical and prismatic batteries are batteries with an electrode assembly mounted in a metal can, while pouch batteries are batteries with an electrode assembly mounted in a pouch-type battery case, typically made of an aluminum laminate sheet. Pouch batteries have the advantages of being able to be stacked at a high density, having a high energy density per weight, being inexpensive, and being easily deformable.

[0003] Pouch-type battery cases can be classified into separate battery cases in which the upper and lower cases are separate, and integrated battery cases in which the upper and lower cases are connected to each other. Regardless of whether the upper and lower cases are separable, they can also be classified into one-cavity battery cells in which one electrode assembly receiving portion is formed, and two-cavity battery cells in which two electrode assembly receiving portions are formed in the upper and lower cases.

[0004] Pouch-type battery cells are typically sealed by heat sealing, but in the case of a separate battery case, the outer periphery of the electrode assembly receiving portion is uniformly heat sealed, so there is no problem with the sealing portion being pressed.

[0005] When sealing the sealing part adjacent to the folded part of the one-piece battery case, the sealing layer of the laminate sheet is subjected to pressure and pushed towards the folded part. The part of the sealing layer that extends outwards from the folded part is called a bat ear because it resembles a bat's ear.

[0006] Since the butt ear causes deformation of the battery case, bending the corresponding area or the surrounding area can cause stress concentration, resulting in damage to the battery case.When assembling a battery module or battery pack, a specific area of ​​the terrace area including the electrode lead is bent, which can cause damage to the butt ear around the area.

[0007] In order to solve the butt ear problem, Patent Document 1 uses a two-stage sealing method in which, with the upper and lower cases facing each other, only the area adjacent to the bend is sealed first, and the remaining area is sealed second. By sealing only the area adjacent to the bend, it is possible to reduce the pressing phenomenon of the sealing layer.

[0008] The pouch-type battery used in the examples of Patent Document 1 is an integrated battery case in which an upper case and a lower case are connected to each other, and is a one-cavity battery cell in which only the lower case has a space for accommodating an electrode assembly. The positive and negative terminals protrude in the same direction, and the protruding direction of the positive and negative terminals is opposite to the direction in which the bent portion of the battery case is formed.

[0009] Patent Document 2 configures an "R sealing portion" that is formed within a predetermined distance from the peripheral corner of the electrode assembly receiving portion.

[0010] The pouch-type battery used in the examples of Patent Document 2 is an integrated battery case in which an upper case and a lower case are connected to each other. The positive and negative terminals protrude upward and downward, respectively, and the bent portion of the battery case is located between the surfaces from which the positive and negative terminals protrude (the left side in the drawing).

[0011] Referring to FIG. 8 of Patent Document 2, Patent Document 2 also performs two-stage sealing. The area where the positive and negative terminals are provided is sealed first, and then the R sealing area is separately sealed.

[0012] The inventors of the present invention discovered that despite the application of R-sealing as in Patent Document 2, cracks easily occur when the electrode assembly is thicker than a certain thickness, especially in the case of a single-cavity battery cell where stress is concentrated on one side. In a single-cavity battery cell with an electrode assembly thickness of 8 mm or more, cracks occur when the radius (R) of the R-sealing exceeds 2 mm. Patent Document 2 does not specify a lower limit but gives an example of 5 mm or less, but this may be changed depending on the shape and thickness of the electrode assembly.

[0013] Patent Document 2 also has the following problems. If the radius of the R sealing is reduced too much, for example to 0 mm, the separator may be damaged, but the patent does not appear to recognize this. The electrode assembly housed in a pouch-type battery is composed of alternately stacked electrodes and separators, and the separator is usually manufactured larger than the electrodes to prevent electrical shorts between the positive and negative electrodes. In the case of a one-cavity battery cell, the separator located at the outermost exposed portion of the electrode assembly housed in the electrode assembly housing may extend beyond the electrode assembly housing and into the sealing area. During heat sealing using a sealing block, the separator may melt or be damaged.

[0014] When additional R-sealing is performed as in Patent Document 2, an overlapping area between the sealing block and the separator may occur, which may result in damage to the separator or an electrical short circuit. Since it is difficult to precisely identify the boundary of the electrode assembly receiving portion and the position of the electrode assembly placed in the electrode assembly receiving portion, R-sealing is performed in millimeters, and performing additional R-sealing as in Patent Document 2 may lead to a larger accident due to damage to the separator. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] Korean Patent No. 10-2367387

[0016] [Patent Document 2] Korean Patent Publication No. 10-2022-0099905 Summary of the Invention [Problem to be solved by the invention]

[0017] The present invention has been made to solve the above problems, and aims to provide a sealing block for preventing cracks in a pouch-type battery case, which can minimize damage to a separator regardless of the radius of R-sealing in R-sealing to prevent cracks due to bending of a pouch-type battery cell, a sealing method for a pouch-type battery case using the sealing block, and a pouch-type secondary battery manufactured using the sealing block. [Means for solving the problem]

[0018] In order to solve the above problems, the present invention provides a sealing block for sealing a pouch-type battery case, the sealing block including: a flat-shaped main body that heats and presses the outer periphery of the pouch-type battery case to seal it; and an extension that is continuously connected to the main body and has a shape in which the pressing force decreases toward a receiving portion that receives an electrode assembly.

[0019] Here, the direction of the receiving portion may specifically be the direction of one vertex of the receiving portion.

[0020] The planar shape is such that the sealing surface and the outer surface of the pouch-type battery case are parallel to each other.

[0021] The shape in which the pressing force decreases toward the receiving portion in which the electrode assembly is received may be a shape in which the sealing surface and the outer surface of the pouch-type battery case are gradually spaced apart toward the receiving portion in which the electrode assembly is received.

[0022] The separation may be performed only along the lateral direction of the receiving portion, only along the longitudinal direction of the receiving portion, or along both the lateral and longitudinal directions of the receiving portion.

[0023] The receiving portion has a rectangular shape, and the electrode leads are led out in the horizontal direction of the receiving portion, and a bent portion is formed in the vertical direction of the receiving portion, i.e., the electrode leads are led out to the upper and / or lower sides.

[0024] The sealing block according to the present invention can be applied to one-cavity and one-piece battery cases in which the thickness of the electrode assembly is 8 mm or more. In this case, the electrode assembly receiving portion has a rectangular shape and is provided in only one of the upper case or the lower case, with electrodes protruding from the top and / or bottom of the electrode assembly receiving portion and a bent portion on one side where the upper case and the lower case are connected.

[0025] The spacing can be gradual or stepwise.

[0026] The extension may be formed within a predetermined distance from at least one apex of the receiving portion in which the electrode assembly is received, and an example of the predetermined distance may be within 5 mm.

[0027] The extension portion may be provided only at the bent portion of the pouch-type battery case.

[0028] The extension may be formed within 2 mm from the boundary surface of the receiving portion in which the electrode assembly is received toward the inside of the receiving portion and within 5 mm from the boundary surface of the receiving portion in the outside of the receiving portion.

[0029] The present invention also provides a method for sealing a pouch-type battery case using the sealing block, wherein the sealing can be performed simultaneously on the main body and the extension.

[0030] The present invention also provides a pouch-type secondary battery including: an electrode assembly in which electrodes and a separator are stacked one on top of the other; and a pouch-type case having a recessed receiving portion formed to receive the electrode assembly, wherein the pouch-type case has a sealing portion formed on at least one surface of the outer surface of the electrode assembly, and the sealing portion includes an extended sealing portion that is sealed by a pressure that decreases toward the receiving portion in which the electrode assembly is received.

[0031] The pouch-type secondary battery according to the present invention may be applied to one-cavity and integrated pouch-type battery cases in which the thickness of the electrode assembly is 8 mm or more. In this case, the electrode assembly receiving portion has a rectangular shape and is provided in only one of the upper case and the lower case, and electrodes are led out from the top and / or bottom surfaces of the electrode assembly receiving portion. One side of the electrode assembly receiving portion is provided with a bent portion connecting the upper case and the lower case.

[0032] The sealing by the decreasing pressure may be a pressure decreasing only along the horizontal direction of the receiving portion, a pressure decreasing only along the vertical direction of the receiving portion, or a pressure decreasing both along the horizontal and vertical directions of the receiving portion. Here, the receiving portion has a rectangular shape, and the electrode leads are led out in the horizontal direction of the receiving portion, and a bent portion is formed in the vertical direction of the receiving portion. That is, the electrode leads are led out to the upper and / or lower sides.

[0033] The pressure may be reduced gradually or in steps.

[0034] The extended sealing portion may be formed within a predetermined distance from at least one apex of the receiving portion in which the electrode assembly is received, and an example of the predetermined distance may be within 5 mm.

[0035] The extended sealing portion may be formed within 2 mm from the boundary surface of the receiving portion in which the electrode assembly is received toward the inside of the receiving portion and within 5 mm from the boundary surface of the receiving portion in the outside of the receiving portion.

[0036] Furthermore, the present invention can also provide a configuration in which the means for solving the above problems are combined in any desired manner. [Effects of the Invention]

[0037] As described above, the present invention provides a sealing block for preventing cracks in a pouch-type battery case, which can minimize damage to a separator regardless of the radius of R-sealing in R-sealing to prevent cracks due to bending of a pouch-type battery cell, a sealing method for a pouch-type battery case using the sealing block, and a pouch-type secondary battery manufactured using the sealing block.

[0038] It has been confirmed that the present invention does not cause cracks at the bent portion even after hundreds of experiments, and furthermore, the extended sealing portion does not damage the separator of the electrode assembly.

[0039] In addition, it was confirmed that the present invention does not cause cracks at the bent portion even in a one-cavity battery cell with a thickness of 8 mm or more, and furthermore, the extended sealing portion does not damage the separator of the electrode assembly. [Brief explanation of the drawings]

[0040] [Figure 1] 1 is a schematic diagram of a pouch-type battery cell according to a first embodiment of the present invention.

[0041] [Figure 2] 3 is a schematic view showing a pouch-type battery cell according to a first embodiment of the present invention being sealed with a sealing block; FIG.

[0042] [Figure 3] 1 is a schematic diagram of a sealing block according to a first embodiment of the present invention;

[0043] [Figure 4] 1 is an enlarged view of a sealing block according to a first embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0044] Hereinafter, with reference to the accompanying drawings, a detailed description will be given of an embodiment of the present invention that will enable a person of ordinary skill in the art to easily carry out the present invention. However, in describing the operation principle of the preferred embodiment of the present invention in detail, detailed description of related well-known functions or configurations will be omitted if it is determined that such detailed description may unnecessarily obscure the gist of the present invention.

[0045] Furthermore, the same reference numerals are used throughout the drawings for parts having similar functions and actions. Throughout the specification, when a part is said to be connected to another part, this includes not only a direct connection but also an indirect connection via another element therebetween. Furthermore, unless otherwise specified, "including a certain element" does not mean that other elements are excluded, but that other elements may also be included.

[0046] FIG. 1 is a schematic diagram of a pouch-type battery cell according to a first embodiment of the present invention, FIG. 2 is a schematic diagram of sealing the pouch-type battery cell according to the first embodiment of the present invention with a sealing block, FIG. 3 is a schematic diagram of the sealing block according to the first embodiment of the present invention, and FIG. 4 is an enlarged view of the sealing block according to the first embodiment of the present invention.

[0047] The invention will now be described in detail with reference to the accompanying drawings.

[0048] 3 and 4 show an example of a sealing block 1000 according to the present invention. The sealing block 1000 includes a flat body 1010 that heats and presses the outer periphery of a pouch-type battery case to seal it, and an extension 1020 that is continuously connected to the body 1010 and has a shape in which the pressing force decreases toward the receiving portion in which the electrode assembly 100 is received. The sealing block 1000 according to the present invention includes an electrode terrace 1030 that provides insufficient sealing at the portion where the electrode tabs and electrode leads are located, but this is not essential. The linear body 1010 may extend and be continuously connected to the extension 1020. In this case, the electrode terrace 1030 may be omitted.

[0049] The planar shape may be a shape in which the sealing surface and the outer surface of the pouch-type battery case are parallel to each other, and the shape in which the pressing force decreases toward the receiving portion in which the electrode assembly is received may be a shape in which the sealing surface and the outer surface of the pouch-type battery case are gradually spaced apart toward the receiving portion in which the electrode assembly is received.

[0050] The spacing may be along the horizontal direction of the receiving portion only, along the vertical direction of the receiving portion only, or along both the horizontal and vertical directions of the receiving portion. Here, the horizontal direction is the x direction and the vertical direction is the y direction. Figure 4 shows extensions spaced along the vertical direction, i.e., the -y direction. Bend reference lines AA, BB, and CC indicate the spacing in the horizontal, vertical, horizontal, and vertical directions, respectively. Figure 4 shows a gradually spaced shape.

[0051] 3 and 4, the plane where the sealing block and the pouch-shaped case meet corresponds to the xy plane. In Fig. 4, when the extension 1020 is spaced apart from the folding reference line BB in the vertical direction, i.e., the -y direction, its inclination angle, i.e., the angle D formed by the extension 1020 and the xy plane when the extension 1020 is folded in the z-axis direction, is preferably 0.1 to 5 degrees. If the angle is less than 0.1 degrees, heat from the sealing block may be transferred to the separator, potentially damaging the separator. If the angle is more than 5 degrees, the effect of the R-sealing according to the present invention will not be achieved.

[0052] 1 and 2 show a pouch-type battery sealed by a sealing block 1000 according to the present invention.

[0053] In the pouch-type battery cell of FIG. 1, electrode leads 100A and 100B protrude upward and downward, and a folded portion 200 of the pouch-type battery case is provided on the left side. The sealing portion 300 is formed by the main body 1010, and the extended sealing portion 310 is formed by the extension portion 1020. The R sealing is formed within a radius R based on the folded portion apex LC of the electrode assembly receiving portion L that receives the electrode assembly 100. An example of R may be 5 mm or less. While the distance between the folded portion 200 and the electrode assembly receiving portion L is exaggerated in FIG. 1, it is actually very short, less than 5 mm. In FIG. 1, the right side is not yet sealed and is in an open state. It will be sealed separately after undergoing steps such as electrolyte injection and activation.

[0054] FIG. 2 is an enlarged view of the extended sealing portion of FIG. 1. FIG. 2 shows the sealing block 1000 in place. The electrode assembly 100 accommodated in the electrode assembly receiving portion L has electrodes and separators alternately stacked, and the separator 110 is typically larger than the electrodes to prevent electrical shorting between the positive and negative electrodes. In the case of a one-cavity battery cell, the separator 110, which is located at the outermost exposed portion of the electrode assembly accommodated in the electrode assembly receiving portion L, extends beyond the electrode assembly receiving portion L to the extended portion 1020 of the sealing block 1000. An overlapping portion S between the extended portion 1020 and the separator 110 may occur, and the heat from the extended portion 1020 of the sealing block 1000 may damage the separator 110. In the overlapping portion S, poly balls formed by the fusion of the sealing layers may cause more damage to the separator than simple fusion of the separator. The present invention reduces the sealing pressure and damage to the separation membrane by folding the extension 1020. The generation of poly balls can be reduced, thereby preventing damage to the separation membrane. The maximum horizontal and vertical lengths of the overlapping portion S are denoted by x and y, respectively.

[0055] Unlike R sealing, it is possible to set an area that can reduce damage caused by bending by using x and y. If there is terrace bending in the area where the electrode protrudes, it was found that x and y need to be at least 1.5 mm.

[0056] Pouch-type battery cells use a laminate sheet with an adhesive layer (sealing layer) formed inside as a battery case, and the outer periphery of the battery case is sealed by heat sealing. When the laminate sheet is heated and pressed, the adhesive layer melts, bonding the upper case and the sealing portion of the lower case. This forms a portion where the resin in the adhesive layer inside the bonding portion hardens. This is commonly called a poly ball (polymer ball). While the heat of such poly balls can damage the separator, using the sealing block of the present invention minimizes damage to the separator.

[0057] The sealing method for a pouch-type battery case using the sealing block 1000 of the present invention is performed in one step using a single sealing block. Unlike Patent Document 2, the present invention can perform sealing in one step without the need for two additional sealing steps because the extension portion of the present invention is inclined as shown in FIG.

[0058] The present invention also provides a pouch-type secondary battery including: an electrode assembly in which electrodes and separators are alternately stacked; and a pouch-type case having a recessed receiving portion formed to receive the electrode assembly, wherein the pouch-type case has a sealing portion formed on at least one surface of the outer surface of the electrode assembly, and the sealing portion includes an extended sealing portion that is sealed by a pressure that decreases toward the receiving portion in which the electrode assembly is received.

[0059] Those skilled in the art will be able to make various applications and modifications within the scope of the present invention based on the above content. [Explanation of symbols]

[0060] 10 Pouch-type battery cells 100 electrode assembly 110 Separation membrane 100A, 100B electrode leads 200 Bent part of pouch-type battery case 300 sealing part 310 Extended ceiling section 1000 Sealing Blocks 1010 Main body 1020 Extension 1030 Electrode terrace L Electrode assembly housing LC electrode assembly housing top D Tilt angle S Separation membrane overlapping section x Length of the separation membrane overlapping section y Width of the separation membrane overlapping section AA, BB, CC Extended ceiling bending reference line

Claims

1. A sealing block for sealing a pouch-type battery case, comprising: a flat main body that heats and presses the outer periphery of the pouch-shaped battery case to seal it; an extension portion continuously connected to the body portion and having a shape such that a pressing force decreases toward the receiving portion in which the electrode assembly is received; Including, sealing block.

2. the planar shape is such that the sealing surface and the outer surface of the pouch-type battery case are parallel to each other; 2. The sealing block according to claim 1, wherein the shape in which the pressing force decreases toward the receiving portion in which the electrode assembly is received is a shape in which the sealing surface and the outer surface of the pouch-type battery case are gradually spaced apart toward the receiving portion in which the electrode assembly is received.

3. The sealing block according to claim 2 , wherein the spacing is only along the lateral direction of the receiving portion, only along the longitudinal direction of the receiving portion, or both along the lateral and longitudinal directions of the receiving portion.

4. 3. The sealing block of claim 2, wherein the spacing is gradual or stepwise.

5. The sealing block according to claim 1 , wherein the extension is formed within a predetermined distance from at least one apex of the receiving portion in which the electrode assembly is received.

6. The sealing block according to claim 1 , wherein the extension is provided only on the bent portion of the pouch-type battery case.

7. 2. The sealing block according to claim 1, wherein the extension portion is formed within 2 mm from a boundary surface of the receiving portion in which the electrode assembly is received toward the inside of the receiving portion and within 5 mm from a boundary surface of the receiving portion in a direction toward the outside of the receiving portion.

8. A method for sealing a pouch-type battery case, using the sealing block according to any one of claims 1 to 7.

9. The method for sealing a pouch-type battery case according to claim 8 , wherein the sealing is performed simultaneously on the main body and the extension.

10. an electrode assembly in which electrodes and separators are stacked one on top of the other; a pouch-type case having a recessed receiving portion formed therein to receive the electrode assembly, The pouch-type case has a sealing portion formed on at least one surface of the outer surface of the electrode assembly, The pouch-type secondary battery includes an extended sealing portion, the sealing portion being sealed by a pressure that decreases toward the receiving portion in which the electrode assembly is received.

11. 11. The pouch-type secondary battery according to claim 10, wherein the sealing by the weakening pressure is performed by weakening the pressure only along the horizontal direction of the accommodating portion, weakening the pressure only along the vertical direction of the accommodating portion, or weakening the pressure both along the horizontal and vertical directions of the accommodating portion.

12. The pouch-type secondary battery according to claim 10 , wherein the pressure is weakened gradually or in steps.

13. The pouch-type secondary battery of claim 10 , wherein the extended sealing portion is formed within a predetermined distance from at least one apex of the receiving portion in which the electrode assembly is received.

14. 14. The pouch-type secondary battery of claim 10, wherein the extended sealing portion is formed within 2 mm from a boundary surface of the receiving portion in a direction toward the inside of the receiving portion and within 5 mm from a boundary surface of the receiving portion in a direction toward the outside of the receiving portion.

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