Sealing block for preventing cracks in pouch-shaped battery case, method for sealing pouch-shaped battery case using same, and pouch-shaped secondary battery manufactured using same

Abstract

The present invention relates to a sealing block for preventing cracks in a pouch-shaped battery case, a method for sealing a pouch-shaped battery case using the same, and a pouch-shaped secondary battery manufactured using the same. The sealing block according to the present invention has an inclined shape, thereby minimizing the influence on an electrode assembly, in particular a diaphragm, while performing R-sealing.

Description

Technical Field

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

[0002] Lithium secondary batteries are classified into cylindrical, prismatic, and pouch-shaped batteries based on the shape of their housings. Cylindrical and prismatic batteries each have an electrode assembly mounted within a metal can, while pouch-shaped batteries have an electrode assembly mounted within a pouch-shaped battery housing typically made of aluminum laminate. Pouch-shaped batteries offer advantages such as high stacking density, high energy density per weight, low cost, and ease of deformation.

[0003] Pouch-shaped battery cases can be divided into separable battery cases in which the upper and lower cases are separated from each other 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 separated from each other, pouch-shaped batteries can also be divided into single-chamber battery cells with one electrode assembly receiving portion or dual-chamber battery cells with two electrode assembly receiving portions formed in the upper and lower cases, respectively.

[0004] The pouch-shaped battery cell is generally sealed by heat fusion. In the case of a detachable battery case, uniform heat fusion is performed around the outer periphery of the electrode assembly receiving portion, thereby preventing problems such as a seal portion push phenomenon from occurring.

[0005] In the case of a one-piece battery case, when sealing the seal adjacent to the bend, the seal layer of the laminate sheet is subjected to pressure and pushed toward the bend. The portion of the seal layer extending toward the outside of the bend is called a bat ear because of its resemblance to a bat's ear.

[0006] Bat ears cause deformation of the battery case, and when the relevant area or its periphery is bent, stress concentrates, thereby damaging the battery case. When assembling battery modules or battery packs, the platform area including the electrode leads is bent to a certain extent, and damage occurs at the bat ears around the relevant area.

[0007] Patent Document 1 discloses a two-step sealing method to address the bat ear problem. This method involves sealing only the area adjacent to the bend in a primary manner, and then sealing the remaining area in a secondary manner with the upper and lower shells facing each other. Because only the area adjacent to the bend is sealed, the phenomenon of pushing the sealing layer can be reduced.

[0008] The pouch-shaped battery cell used as an embodiment of Patent Document 1 is a single-chamber battery cell comprising an integral battery case in which an upper case and a lower case are connected to each other, with only the lower case being provided with a space configured to accommodate an electrode assembly. The positive and negative electrode 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 discloses an "R seal" portion formed within a predetermined distance from a corner portion of an electrode assembly receiving portion.

[0010] The pouch-shaped battery used as an embodiment of Patent Document 2 includes an integrated battery case in which an upper case and a lower case are connected to each other. The positive and negative electrode terminals protrude in opposite upward and downward directions, respectively, and a bent portion of the battery case is provided between the surfaces from which the positive and negative terminals protrude (left side in the figure).

[0011] 8 of Patent Document 2, two-step sealing is also performed in Patent Document 2. The area where the positive electrode terminal and the negative electrode terminal are provided is sealed at once, and only the R sealing portion is sealed separately.

[0012] The inventors of this application have found that, particularly in the case of a single-chamber battery cell where stress is concentrated on one side, cracks are likely to occur when the thickness of the electrode assembly exceeds a certain value, despite the application of an R seal as in Patent Document 2. For single-chamber battery cells with an electrode assembly thickness of 8 mm or greater, cracks occur when the radius R of the R seal exceeds 2 mm. Patent Document 2 does not provide a lower limit, but suggests 5 mm or less as an example, but this will vary depending on the shape and thickness of the electrode assembly.

[0013] Patent document 2 is also problematic in the following points. If the radius of the R seal is extremely reduced to, for example, 0 mm, the diaphragm may be damaged, however this does not seem to be recognized. The electrode assembly housed in the pouch-shaped battery is constructed so that the electrodes and the diaphragm are alternately stacked and the diaphragm is generally larger than the electrode to prevent an electrical short circuit between the positive and negative electrodes. In the case of a single-chamber battery cell, the diaphragm of the electrode assembly housed in the electrode assembly housing, which is provided at its outermost exposed portion, may be provided as a sealing area extending outside the electrode assembly housing. During thermal fusion using a sealing block, the diaphragm may be melted or damaged.

[0014] If additional R-sealing is performed as in Patent Document 2, an area where the sealing block and the diaphragm overlap may be generated, thereby damaging the diaphragm and causing an electrical short circuit. Since it is difficult to accurately specify the boundary of the electrode assembly receiving portion and the position of the electrode assembly disposed therein, and since R-sealing is performed in units of mm, additional R-sealing such as in Patent Document 2 may cause a greater accident due to damage to the diaphragm.

[0015] (“Patent Document 1”) Korean Registered Patent Publication No. 2367387

[0016] (“Patent Document 2”) Korean Patent Application Publication No. 2022-0099905 Summary of the Invention

[0017] Technical issues

[0018] The present invention has been made in view of the above problems. An object of the present invention is to provide a sealing block for preventing cracks in a pouch-shaped battery case, a method for sealing a pouch-shaped battery case using the sealing block, and a pouch-shaped secondary battery manufactured using the sealing block. In the R seal for preventing cracks caused by bending of the pouch-shaped battery cell, the sealing block can minimize damage to the diaphragm regardless of the radius of the R seal.

[0019] Technical Solution

[0020] In order to solve the above problems, the present invention provides a sealing block for sealing a pouch-shaped battery case, the sealing block comprising: a main body portion with a planar shape, the main body portion being configured to heat and press the outer periphery of the pouch-shaped battery case to seal the pouch-shaped battery case; and an extension portion continuously connected to the main body portion, the extension portion having a shape in which the pressing pressure gradually decreases in a direction toward a accommodating portion configured to accommodate an electrode assembly.

[0021] Specifically, the direction toward the accommodation portion may be a direction toward any vertex of the accommodation portion.

[0022] The planar shape may be a shape in which a sealing surface and an outer surface of the pouch-shaped battery case are parallel to each other.

[0023] The shape in which the pressing pressure gradually decreases in a direction toward a receiving portion configured to receive an electrode assembly may be a shape in which the sealing surface and the outer surface of the pouch-shaped battery case are further spaced apart from each other in a direction toward the receiving portion configured to receive the electrode assembly.

[0024] The interval may be an interval only in the horizontal direction of the accommodation portion, an interval only in the vertical direction of the accommodation portion, or an interval in both the horizontal and vertical directions of the accommodation portion.

[0025] Here, the receiving portion may have a rectangular shape, the electrode lead may be led out in the horizontal direction of the receiving portion, and a bend may be formed in the vertical direction of the receiving portion. That is, the electrode lead may be led out upward and / or downward.

[0026] The sealing block according to the present invention can be applied to a single-chamber, one-piece battery case having an electrode assembly having a thickness of 8 mm or greater. In this case, the electrode assembly receiving portion may have a rectangular shape and may be provided in only one of the upper case and the lower case. The electrodes may be led out from the upper and / or lower surfaces of the electrode assembly receiving portion, and a bent portion where the upper and lower cases are connected to each other may be provided on one side.

[0027] The intervals may be gradual intervals or stepped intervals.

[0028] The extension portion may be formed within a predetermined distance from at least one vertex of the receiving portion configured to receive the electrode assembly. An example of the predetermined distance may be less than 5 mm.

[0029] The extension portion may be provided only at a bent portion of the pouch-shaped battery case.

[0030] The extension portion may be within 2 mm in a direction toward an inner side of the receiving portion and within 5 mm in a direction toward an outer side of the receiving portion from a boundary of the receiving portion configured to receive the electrode assembly.

[0031] In addition, the present invention provides a method for sealing a pouch-shaped battery case using the sealing block, wherein the sealing can be performed simultaneously on the main body portion and the extension portion.

[0032] In addition, the present invention provides a pouch-shaped secondary battery, which includes: an electrode assembly having electrodes and separators stacked alternately; and a pouch-shaped shell, which is formed with a concave-shaped accommodating portion configured to accommodate the electrode assembly, wherein the pouch-shaped shell has a sealing portion located on at least one of the outer surfaces of the electrode assembly, and the sealing portion includes an extended sealing portion, which is sealed by pressure that becomes increasingly weaker in a direction toward the accommodating portion configured to accommodate the electrode assembly.

[0033] The pouch-shaped secondary battery according to the present invention may include a single-chamber, one-piece battery case having an electrode assembly having a thickness of 8 mm or greater. In this case, the electrode assembly receiving portion may have a rectangular shape and may be provided in only one of the upper case and the lower case. The electrodes may be drawn from the upper and / or lower surfaces of the electrode assembly receiving portion, and a bent portion may be provided on one side where the upper and lower cases are connected to each other.

[0034] The sealing by the gradually weakening pressure can be achieved by weakening pressure only in the horizontal direction of the accommodating portion, weakening pressure only in the vertical direction of the accommodating portion, or weakening pressure in both the horizontal and vertical directions of the accommodating portion. Here, the accommodating portion can have a rectangular shape, the electrode lead can be led out in the horizontal direction of the accommodating portion, and a bend can be formed in the vertical direction of the accommodating portion. That is, the electrode lead can be led out upward and / or downward.

[0035] The pressure may be gradually weakened or gradually weakened.

[0036] The extended sealing portion may be formed within a predetermined distance from at least one vertex of the receiving portion configured to receive the electrode assembly. An example of the predetermined distance may be less than 5 mm.

[0037] The extended sealing portion may be within 2 mm in a direction toward an inner side of the receiving portion and within 5 mm in a direction toward an outer side of the receiving portion from a boundary of the receiving portion configured to receive the electrode assembly.

[0038] Furthermore, the present invention may provide any possible combination of the above solutions.

[0039] Beneficial effects

[0040] As is apparent from the above description, the present invention can provide a sealing block for preventing cracks in a pouch-shaped battery case, a method for sealing a pouch-shaped battery case using the sealing block, and a pouch-shaped secondary battery manufactured using the sealing block, wherein in an R seal for preventing cracks caused by bending of a pouch-shaped battery cell, the sealing block can minimize damage to the diaphragm regardless of the radius of the R seal.

[0041] The present inventors confirmed that even in experiments exceeding several hundred times, cracks did not occur in the bent portion, and the separator of the electrode assembly was not damaged by the extended sealing portion.

[0042] The present invention also confirmed that even for a single-chamber battery cell having a thickness of 8 mm or more, cracks did not occur in the bent portion, and the separator of the electrode assembly was not damaged by the extended sealing portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a schematic diagram of a pouch-shaped battery cell according to a first embodiment of the present invention.

[0044] Figure 2 FIG. 1 is a schematic diagram of sealing a pouch-shaped battery cell according to a first embodiment of the present invention using a sealing block.

[0045] Figure 3is a schematic diagram of a sealing block according to a first embodiment of the present invention.

[0046] Figure 4 is an enlarged view of the sealing block according to the first embodiment of the present invention. DETAILED DESCRIPTION

[0047] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that the preferred embodiments of the present invention can be easily implemented by those skilled in the art. However, when describing the working principles of the preferred embodiments of the present invention in detail, if the detailed description of known functions and structures incorporated herein may obscure the subject matter of the present invention, such detailed description will be omitted.

[0048] In addition, the same reference numerals will be used throughout the drawings to refer to components that perform similar functions or operations. In the case where a part is referred to as being connected to another part throughout the application, not only can the part be directly connected to the other part, but the part can also be indirectly connected to the other part via another part. In addition, including a certain element does not mean that other elements are not included, but rather that such elements may be further included, unless otherwise specified.

[0049] Figure 1 is a schematic diagram of a pouch-shaped battery cell according to a first embodiment of the present invention, Figure 2 is a schematic diagram of using a sealing block to seal a pouch-shaped battery cell according to a first embodiment of the present invention, Figure 3 is a schematic diagram of a sealing block according to a first embodiment of the present invention, Figure 4 is an enlarged view of the sealing block according to the first embodiment of the present invention.

[0050] Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0051] Figure 3 and Figure 4 The sealing block 1000 according to the present invention is illustrated. The sealing block 1000 includes: a main body portion 1010 in a planar shape, the main body portion 1010 being configured to heat and press the outer periphery of a pouch-shaped battery case to seal the pouch-shaped battery case; and an extension portion 1020 continuously connected to the main body portion 1010, the extension portion 1020 having a shape in which the pressing pressure decreases increasingly in a direction toward a receiving portion configured to receive the electrode assembly 100. The sealing block 1000 according to the present invention has an electrode platform portion 1030, which is configured to allow a portion having an electrode tab and an electrode lead to be less sealed, but the portion is not necessary. The straight main body portion 1010 may be extended and may be continuously connected to the extension portion 1020, in which case the electrode platform portion 1030 may be omitted.

[0052] The planar shape may be a shape in which the sealing surface and the outer surface of the pouch-shaped battery case are parallel to each other, and the shape in which the pressing pressure decreases increasingly in the direction toward the accommodating portion configured to accommodate the electrode assembly may be a shape in which the sealing surface and the outer surface of the pouch-shaped battery case are further spaced apart from each other in the direction toward the accommodating portion configured to accommodate the electrode assembly.

[0053] The spacing may be spacing only in the horizontal direction of the receiving portion, spacing only in the vertical direction of the receiving portion, or spacing in 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 The extensions are shown with spacing in the vertical direction, ie, the -y direction. Bending reference lines AA, BB, and CC represent spacing in the horizontal direction, spacing in the vertical direction, and spacing in both the horizontal and vertical directions, respectively. Figure 4 A progressively spaced shape is shown.

[0054] exist Figure 3 and Figure 4 In the embodiment, the plane where the sealing block and the bag-shaped housing are joined to each other corresponds to the xy plane. Figure 4 In the embodiment, when extension portion 1020 is spaced apart from bending reference line BB in the vertical direction, i.e., the -y direction, its inclination angle, i.e., the angle D formed between extension portion 1020 and the xy plane when extension portion 1020 is bent 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 diaphragm, thereby damaging the diaphragm. If the angle is greater than 5 degrees, the R-seal effect of the present invention cannot be achieved.

[0055] Figure 1 and Figure 2 A pouch-shaped battery sealed by a sealing block 1000 according to the present invention is shown.

[0056] Figure 1 The pouch-shaped battery cell is constructed so that the electrode leads 100A and 100B protrude upward and downward, respectively, and a bending portion 200 is provided on the left side of the pouch-shaped battery case. The sealing portion 300 is formed by the main body portion 1010, and the extended sealing portion 310 is formed by the extension portion 1020. Based on the vertex LC at the bending portion of the electrode assembly accommodating portion L configured to accommodate the electrode assembly, an R seal is formed within a radius R. An example of R may be within 5 mm. Figure 1 In FIG, the distance between the bent portion 200 and the electrode assembly receiving portion L is exaggerated, but in reality it does not exceed 5 mm, which is very short. Figure 1 , the right side is in an open state because sealing has not yet been performed, and substantially after the electrolyte injection step, the activation step, etc., the right side alone is finally sealed.

[0057] Figure 2 yes Figure 1 An enlarged view of the extended seal portion. Figure 2 The sealing block 1000 is shown to be placed. The electrode assembly 100 accommodated in the electrode assembly accommodating portion L is constructed so that the electrodes and the separators are alternately stacked, and the separator 110 is generally larger than the electrodes to prevent electrical short circuits between the positive and negative electrodes. In the case of a single-chamber battery cell, the separator 110 provided at the outermost exposed portion of the electrode assembly accommodated in the electrode assembly accommodating portion L is provided as an extension 1020 of the sealing block 1000 extending outside the electrode assembly accommodating portion L. At this time, an overlapping portion S is generated in which the extension 1020 and the separator 110 overlap each other, and the separator 110 may be damaged by the heat from the extension 1020 of the sealing block 1000. In the overlapping portion S, the balling caused by the fusion of the sealing layer may cause more damage to the separator 110 than the simple fusion of the separator. In the present invention, the sealing pressure can be reduced by bending the extension 1020, thereby reducing damage to the separator. Damage to the separator can be prevented by reducing the generation of balling. The maximum horizontal length and vertical length of the overlapping portion S are denoted by x and y, respectively.

[0058] Unlike R seals, the area that can reduce damage due to bending can also be set by x and y. It was found that the minimum value of each of x and y for the bending of the platform where the electrode protrudes is 1.5 mm.

[0059] In pouch-shaped battery cells, a laminate sheet with an adhesive layer (sealant layer) is used as the battery case, and the outer periphery of the battery case is sealed by heat fusion. When the laminate sheet is heated and pressed, the adhesive layer melts, and the seals of the upper and lower cases are bonded to each other. This creates a region where the resin of the adhesive layer in the bonded area aggregates, commonly known as a poly ball (polymer ball). The heat from the poly ball can damage the separator, but using the sealing block according to the present invention minimizes this damage.

[0060] The method of sealing a pouch-shaped battery case using the sealing block 1000 according to the present invention is performed at one time using one sealing block. Figure 3 As shown in , the extension portion is inclined, so unlike Patent Document 2, sealing can be performed at one time without requiring two separate sealings.

[0061] In addition, the present invention provides a pouch-shaped secondary battery, which includes: an electrode assembly, the electrode assembly having electrodes and separators stacked alternately; and a pouch-shaped shell, the pouch-shaped shell forming a concave-shaped accommodating portion configured to accommodate the electrode assembly, wherein the pouch-shaped shell has a sealing portion located on at least one of the outer surfaces of the electrode assembly, and the sealing portion includes an extended sealing portion that is sealed by pressure that becomes increasingly weaker in a direction toward the accommodating portion configured to accommodate the electrode assembly.

[0062] Those skilled in the art to which the present invention pertains will appreciate that various applications and modifications can be made within the scope of the present invention based on the above description.

[0063] (Explanation of reference numbers)

[0064] 10: Pouch battery cell

[0065] 100: Electrode assembly

[0066] 110: Diaphragm

[0067] 100A, 100B: Electrode leads

[0068] 200: Bending part of the pouch-shaped battery case

[0069] 300: Sealing part

[0070] 310: Extended seal

[0071] 1000: Sealing block

[0072] 1010: Main body

[0073] 1020: Extension

[0074] 1030: Electrode platform

[0075] L: Boundary of the electrode assembly housing

[0076] LC: Vertex of the electrode assembly housing

[0077] D: Tilt angle

[0078] S: Diaphragm overlap

[0079] x: vertical length of the overlapping part of the diaphragm

[0080] y: horizontal length of the overlapping part of the diaphragm

[0081] AA, BB, CC: Bend reference lines of the extended seal.

Claims

1. A sealing block for sealing a pouch-shaped battery housing, the sealing block comprising: a main body portion having a planar shape, the main body portion being configured to heat and press an outer periphery of the pouch-shaped battery case to seal the pouch-shaped battery case; as well as The extension portion is continuously connected to the main body portion, and has a shape in which a pressing pressure gradually decreases in a direction toward a receiving portion configured to receive the electrode assembly.

2. The sealing block according to claim 1, wherein The planar shape is a shape in which a sealing surface and an outer surface of the pouch-shaped battery case are parallel to each other, and The shape in which the pressing pressure gradually decreases in a direction toward a receiving portion configured to receive an electrode assembly is a shape in which the sealing surface and the outer surface of the pouch-shaped battery case are further spaced apart from each other in a direction toward the receiving portion configured to receive the electrode assembly. 3 . The sealing block according to claim 2 , wherein the interval is an interval only in the horizontal direction of the accommodation portion, an interval only in the vertical direction of the accommodation portion, or an interval in both the horizontal and vertical directions of the accommodation portion. The sealing block according to claim 2 , wherein the intervals are gradual intervals or stepped intervals. 5 . The sealing block according to claim 1 , wherein the extension portion is formed within a predetermined distance from at least one vertex of the receiving portion configured to receive the electrode assembly. The sealing block according to claim 1 , wherein the extension portion is provided only at a bent portion of the pouch-shaped battery case. 7 . The sealing block according to claim 1 , wherein the extension portion is within 2 mm in a direction toward an inner side of the accommodation portion and within 5 mm in a direction toward an outer side of the accommodation portion from a boundary of the accommodation portion configured to accommodate the electrode assembly. 8 . A method of sealing a pouch-shaped battery case using the sealing block according to claim 1 .

9. The method of claim 7, wherein the sealing is performed simultaneously on the main body portion and the extension portion.

10. A pouch-shaped secondary battery, comprising: an electrode assembly having electrodes and separators stacked alternately; as well as A pouch-shaped case is formed with a concave-shaped receiving portion configured to receive the electrode assembly, wherein The pouch-shaped case has a sealing portion on at least one of the outer surfaces of the electrode assembly, and The sealing portion includes an extended sealing portion that seals by a pressure that becomes increasingly weaker in a direction toward the receiving portion configured to receive the electrode assembly.

11. The pouch-shaped secondary battery according to claim 10, wherein the sealing by the increasingly weakening pressure is sealing by a pressure that weakens only in the horizontal direction of the accommodating portion, a pressure that weakens only in the vertical direction of the accommodating portion, or a pressure that weakens in both the horizontal and vertical directions of the accommodating portion. 12 . The pouch-shaped secondary battery according to claim 10 , wherein the pressure weakens gradually or stepwise. 13 . The pouch-shaped secondary battery of claim 10 , wherein the extended sealing portion is formed within a predetermined distance from at least one vertex of the receiving portion configured to receive the electrode assembly. The pouch-shaped secondary battery according to claim 10 , wherein the extended sealing portion is within 2 mm in a direction toward an inner side of the receiving portion configured to receive the electrode assembly and within 5 mm in a direction toward an outer side of the receiving portion from a boundary of the receiving portion.

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