Pouch-type battery cell sealing device including a pair of sealing rollers, sealing method using the same, and pouch-type battery cell manufactured thereby

Abstract

The present invention relates to a pouch-type battery cell sealing device that includes a pair of sealing rollers that roll while pressing an upper and lower part of a sealing portion of a pouch-type battery cell, the pair of sealing rollers including a first sealing roller and a second sealing roller that seal the sealing portion by moving from the inside to the outside of the sealing portion of the pouch-type battery cell, a sealing method using the same, and a pouch-type battery cell manufactured using the same, and the pouch-type battery cell can be easily vented even when the pouch-type battery cell is in a low internal pressure state.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0152306, filed November 15, 2022, and all contents disclosed in the Korean Patent Application are incorporated herein by reference.

[0002] The present invention relates to a pouch-type battery cell sealing device including a pair of sealing rollers, a sealing method using the same, and a pouch-type battery cell manufactured thereby. More specifically, the present invention relates to a pouch-type battery cell sealing device including a pair of sealing rollers that can quickly release gas when the internal pressure of a pouch-type battery cell increases, thereby preventing explosion, a sealing method using the same, and a pouch-type battery cell manufactured thereby. [Background technology]

[0003] Rechargeable lithium secondary batteries are widely used as energy sources for wireless mobile devices or wearable devices, as well as for electric vehicles and hybrid electric vehicles, which are presented as alternatives to existing gasoline and diesel vehicles that cause air pollution.

[0004] Lithium secondary batteries can be classified into prismatic and cylindrical battery cells having metal can-type cases, and pouch-type battery cells having cases formed from laminate sheets. Among these, pouch-type battery cells are widely used due to their advantages of being easily deformable and capable of increasing energy density when accommodated and stacked.

[0005] In the lithium secondary battery, side reactions occur between the surface of the electrodes and the electrolyte during repeated charge and discharge. If the gas generated during these reactions cannot be discharged from the inside of the battery case, the battery case may expand or deform.

[0006] In particular, unlike cylindrical battery cells that include safety vents, pouch-type battery cells do not include a separate venting structure, so venting can occur in areas of the heat-sealed outer periphery where gas concentrates or in areas where the heat-sealed bond is weak.

[0007] In general, a pouch-type battery cell is manufactured by forming a laminate sheet including an outer resin layer, a metal layer, and an inner adhesive layer into a pouch-type battery case, accommodating an electrode assembly inside the pouch-type battery case, and then sealing the pouch-type battery case.

[0008] The laminate sheet may have a more complex and diverse layer structure depending on the embodiment and application environment.

[0009] To seal the pouch-type battery case, the outer periphery of the pouch-type battery case is pressed with a heating block that provides heat and pressure, thereby melting the inner adhesive layer, and the inner resin layer of the upper case and the inner adhesive layer of the lower case, which are stacked together, are heat-sealed.

[0010] FIG. 1 is a front view of a pouch-type battery cell and its sealing device according to the prior art.

[0011] 1, a pouch-type battery case is made up of an upper case 110 and a lower case 120. The outer peripheries of the upper case 110 and the lower case 120 are placed between a pair of sealing tools 10, and then the upper case 110 and the lower case 120 are pressed and heated by the pair of sealing tools 10 to form a seal. The upper case 110 and the lower case 120 are made up of laminate sheets in which an outer resin layer, a metal layer, and an inner adhesive layer are sequentially laminated, and the inner adhesive layer of the upper case 110 and the inner adhesive layer of the lower case 120 are melted.

[0012] The pressure of the sealing tool 10 that heats and presses the sealing part causes the melted inner adhesive layer to be pressed inward and outward based on the sealing part, thereby forming an inner poly ball 101 and an outer poly ball 102 .

[0013] The pair of sealing tools 10 is configured to press the entire area of ​​the sealing portion at once, and since the inner adhesive layer moves more inward where the space is wider toward the electrode assembly receiving portion, the size of the inner poly ball 101 is formed larger than the size of the outer poly ball 102. If the size of the inner poly ball 101 is large, it is difficult to vent even when the internal pressure of the pouch-type battery cell increases, and the internal pressure of the pouch-type battery case gradually increases.

[0014] If an external impact is applied while the pouch-type battery case continues to expand, or if a chemical chain reaction such as thermal runaway occurs due to an electrical short circuit, the pouch-type battery cell may explode.

[0015] In this regard, Patent Document 1 relates to a battery cell including a battery case made of a laminate sheet having a structure in which a first resin layer, a metal layer, and a second resin layer are sequentially stacked, and the laminate sheet includes a first sheet portion and a second sheet portion that face each other to form a sealed excess portion, and at least a portion of the sealed excess portion includes a resin layer fusion portion formed by the first resin layer of the first sheet portion and the first resin layer of the second sheet portion, and a metal layer weld portion formed by the metal layer end of the first sheet portion and the metal layer end of the second sheet portion.

[0016] In addition, Patent Document 1 uses semicircular first and second sealing tools that bulge toward the first and second sheet portions, and a resin layer fusion portion is formed inside the sealing portion formed by the first and second sealing tools adjacent to the electrode assembly, thereby increasing the sealing force of the battery cell.

[0017] Therefore, there is a need to develop a pouch-type battery cell sealing device that has a structure that allows for easy venting by making the sealing pressure of the outer peripheral sealing portion of the pouch-type battery case uneven, a sealing method using the same, and a pouch-type battery cell manufactured using the same. [Prior art documents] [Patent documents]

[0018] [Patent Document 1] Korean Patent Publication No. 10-2016-0073097 Summary of the Invention [Problem to be solved by the invention]

[0019] The present invention has been made to solve the above problems, and aims to provide a pouch-type battery cell sealing device in which the inner adhesive layer of the sealing part is thinned to reduce the venting pressure of the sealing part of the pouch-type battery cell and facilitate venting, a sealing method using the same, and a pouch-type battery cell manufactured using the same. [Means for solving the problem]

[0020] To achieve this object, the pouch-type battery cell sealing device according to the present invention includes a pair of sealing rollers that roll while pressing the upper and lower parts of a sealing portion of a pouch-type battery cell, the pair of sealing rollers including a first sealing roller and a second sealing roller, and the pair of sealing rollers can seal the sealing portion by moving from the inside to the outside of the sealing portion of the pouch-type battery cell.

[0021] The first sealing roller may rotate in a first direction about a rotation axis, and the second sealing roller may rotate in a second direction opposite to the first direction about a rotation axis.

[0022] The first sealing roller and the second sealing roller may press the sealing portion in a heated state.

[0023] The heating temperature of the first sealing roller and the second sealing roller may be higher than the melting temperature of the inner adhesive layer of the laminate sheet that constitutes the pouch-type battery cell.

[0024] The diameters of the first and second sealing rollers may be configured to be 50% or less of the width of the sealing portion.

[0025] The method for sealing a pouch-type battery cell using the pouch-type battery cell sealing device includes: (a) disposing a sealing portion of the pouch-type battery cell between a pair of sealing rollers; and (b) moving the pair of sealing rollers from the inside to the outside of the sealing portion while independently rotating a first sealing roller and a second sealing roller constituting the pair of sealing rollers, wherein in step (b), the pair of sealing rollers may be moved while rotating in a heated state.

[0026] The first sealing roller and the second sealing roller may have the same rotation speed and movement speed, and the first sealing roller may move while rotating in a state of pressing downward based on the sealing unit, and the second sealing roller may move while rotating in a state of pressing upward based on the sealing unit.

[0027] The inner adhesive layer of the laminate sheet is melted inside the sealing part and can be moved toward the outside of the sealing part by the pair of sealing rollers.

[0028] The pair of sealing rollers may move from the inside to the outside of the sealing portion until the molten inner adhesive layer moves to the outer end of the sealing portion.

[0029] The pouch-type battery cell manufactured by the pouch-type battery cell sealing device includes a pouch-type battery case made of a laminate sheet including an outer resin layer, a metal layer, and an inner adhesive layer, and the pouch-type battery case has a sealing portion formed by heat-sealing the inner adhesive layer around the outer periphery of an upper case and a lower case, and the molten inner adhesive layer is extruded to the inside and outside of the sealing portion by a pair of sealing rollers of the pouch-type battery cell sealing device to form an inner poly ball and an outer poly ball, and the size of the outer poly ball may be larger than the size of the inner poly ball.

[0030] The outer poly ball may prevent an end surface of the metal layer of the pouch-type battery case from being exposed.

[0031] Furthermore, the present invention can also be provided in the form of various combinations of means for solving the above problems. [Effects of the Invention]

[0032] As described above, in the present invention, the inner adhesive layer of the laminate sheet in the sealing portion of the pouch-type battery cell is melted and moved to the outside of the sealing portion, so the outer poly ball formed outside the sealing portion is larger than the inner poly ball formed inside the sealing portion.

[0033] Therefore, venting can be easily performed even when the internal pressure of the pouch-type battery case is low, which prevents the pouch-type battery cells from expanding and deforming, and thus preventing the pouch-type battery cells from exploding. [Brief explanation of the drawings]

[0034] [Figure 1] FIG. 1 is a front view of a pouch-type battery cell and its sealing device according to the prior art. [Figure 2] 1A and 1B are a front view and an enlarged perspective view of a pouch-type battery cell according to the present invention; [Figure 3]1 is a process diagram of a sealing method for a pouch-type battery cell according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0035] 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 skilled 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.

[0036] 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.

[0037] Furthermore, descriptions that limit or add specific elements are applicable to all inventions and are not limited to a particular invention unless otherwise specified.

[0038] Furthermore, throughout the description of the present invention and the claims, the singular includes the plural unless otherwise stated.

[0039] Furthermore, throughout the description of the present invention and the claims, unless otherwise specified, "or" includes "and." Therefore, "including A or B" means three cases: including A, including B, or including both A and B.

[0040] The invention will now be explained with reference to the drawings and in conjunction with detailed embodiments.

[0041] The pouch-type battery cell includes a pouch-type battery case made of a laminate sheet including outer resin layers 111, 121, metal layers 112, 122, and inner adhesive layers 113, 123, and the pouch-type battery case is composed of an upper case 110 and a lower case 120. The upper case 110 and the lower case 120 may be formed as a single member connected at one outer periphery, or the upper case and the lower case may be separate from each other and joined by heat sealing to form a sealing portion.

[0042] The outer resin layer may comprise polyethylene terephthalate or oriented nylon, the metal layer may comprise aluminum or an aluminum alloy, and the inner adhesive layer may comprise polypropylene.

[0043] FIG. 2 is a front view and an enlarged perspective view of a pouch-type battery cell according to the present invention.

[0044] Referring to FIG. 2, the pouch-type battery cell sealing device according to the present invention includes a pair of sealing rollers 200 that roll while pressing the upper and lower portions of the sealing portion of the pouch-type battery cell, respectively. The pair of sealing rollers 200 includes a first sealing roller and a second sealing roller, and the pair of sealing rollers 200 seal the sealing portion by moving from the inside to the outside of the sealing portion of the pouch-type battery cell in direction A.

[0045] Here, the first sealing roller rotates in a first direction around a rotation axis, and the second sealing roller rotates in a second direction opposite to the first direction around a rotation axis. If the first direction is clockwise, the second direction is counterclockwise, and if the first direction is counterclockwise, the second direction is clockwise.

[0046] In the case of FIG. 2, the first sealing roller rotates clockwise and the second sealing roller rotates counterclockwise, and the first and second sealing rollers move in direction A while rotating clockwise and counterclockwise.

[0047] The first and second sealing rollers press the sealing portion in a heated state. The heating temperature of the first and second sealing rollers is higher than the melting temperature of the inner adhesive layers 113 and 123 of the laminate sheets that constitute the pouch-type battery cell. Generally, considering that polypropylene is used as a component of the inner adhesive layers, the temperature of the first and second sealing rollers may be 100°C to 200°C.

[0048] Therefore, when the laminate sheet is pressed and heated by the first and second sealing rollers, the inner adhesive layers 113, 123 melt, and are extruded in a molten state in direction A. As the inner adhesive layers melt and move while being pushed outward from the sealing portion, they solidify, forming a round, spherical mass. This round, spherical mass is formed by the melting and solidification of the inner adhesive layer, which contains a polymer material, and is therefore referred to as a "polyball" in this specification.

[0049] However, when the pair of sealing rollers first press the sealing portion, the molten inner adhesive layer moves inward and outward from the contact point of the pair of sealing rollers, and at least a portion of the inner adhesive layer 113, 123 may move in the direction opposite to direction A, toward the electrode assembly receiving portion.

[0050] Therefore, the molten material of the molten inner adhesive layers 113, 123 is extruded toward the inside and outside of the sealing portion by a pair of sealing rollers 200 of the pouch-type battery cell sealing device, forming an inner poly ball 101 and an outer poly ball 102. However, since the pair of sealing rollers 200 extrude the molten inner adhesive layers 113, 123 toward the outside of the sealing portion while moving in direction A, the outer poly ball 102 is formed to be larger than the inner poly ball 101.

[0051] Meanwhile, the pair of sealing rollers 200 move from the inside to the outside of the sealing portion until the molten inner adhesive layer moves to the outer edge of the sealing portion, so that the outer poly balls 102 protrude outward from the outer peripheral edges of the upper case 110 and the lower case 120 and are formed into round spherical shapes. Therefore, the outer poly balls 102 are attached to the end surfaces of the metal layers 112, 122. In this way, the end surfaces of the metal layers 112, 122 are not exposed, thereby preventing the metal layers 112, 122 from being exposed and corroding.

[0052] Meanwhile, in the pair of sealing rollers 200, the diameters of the first and second sealing rollers may be configured to be 50% or less of the width of the sealing portion.

[0053] FIG. 3 is a process diagram of the sealing method for a pouch-type battery cell according to the present invention.

[0054] Referring to FIG. 3, a method for sealing a pouch-type battery cell using a pouch-type battery cell sealing device according to the present invention includes the steps of: arranging an upper case 110 and a lower case 120 facing each other; and then (a) placing a sealing portion of the pouch-type battery cell between a pair of sealing rollers 200; and (b) independently rotating a first sealing roller and a second sealing roller constituting the pair of sealing rollers 200, thereby moving the pair of sealing rollers 200 from the inside to the outside of the sealing portion in direction A. In step (b), the pair of sealing rollers 200 may be rotated in a heated state.

[0055] 3 is a state in which the pair of sealing rollers 200 are not arranged, and the sealing portions of the upper case 110 and the lower case 120 are arranged to face each other. For the sake of convenience, FIG. 3 shows the upper case 110 and the lower case 120 as being spaced apart from each other, but they may also be in close contact with each other.

[0056] The first sealing roller and the second sealing roller have the same rotation speed and movement speed, and the first sealing roller moves while rotating in a state of pressing downward based on the sealing part, and the second sealing roller moves while rotating in a state of pressing upward based on the sealing part.

[0057] During this process, the inner adhesive layer of the laminate sheet melts inside the sealing part and is moved toward the outside of the sealing part by the pair of sealing rollers.

[0058] The first and second sealing rollers are arranged at the same vertical position and move toward each other in direction A while pressing the upper case 110 and the lower case 120, so that the inner adhesive layers 113 and 123 melt and become integrated in the areas pressed by the pair of sealing rollers 200, reducing their thickness. Therefore, when the sealing of the sealing portion is completed by the pair of sealing rollers 200, the molten material that makes up the inner adhesive layers 113 and 123 hardens at the outer end of the sealing portion to form the outer poly ball 102.

[0059] Here, since the internal adhesive layers 113, 123 are fused to each other, the thickness of the internal adhesive layers 113, 123 after fusion is less than the sum of the thicknesses of the internal adhesive layers 113, 123 before fusion, and only the reduced thickness of the internal adhesive layers 113, 123 forms a poly ball.

[0060] As such, the thickness of the inner adhesive layers 113, 123 becomes thinner after fusion, so the sealing force between the upper case 110 and the lower case 120 becomes relatively weaker.

[0061] In other words, the sealing force of a pouch-type battery case becomes stronger as the thickness of the internal adhesive layers 113, 123 increases and the size of the internal poly ball increases. Therefore, as in the present invention, not only is the thickness of the internal adhesive layers 113, 123 reduced, but the size of the external poly ball 102 is made larger than the size of the internal poly ball 101, thereby reducing the sealing force of the pouch-type battery case.

[0062] Therefore, when using a pouch-type battery cell such as that of the present invention, venting can be performed quickly even when the internal pressure of the pouch-type battery cell is low, thereby preventing problems such as explosion due to delayed venting of the pouch-type battery cell.

[0063] 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]

[0064] 10 sealing tools 101 Inner Polyball 102 outer polyball 110 Upper case 111, 121 outer resin layer 112, 122 metal layer 113, 123 Internal adhesive layer 120 Lower Case 200 pairs of sealing rollers

Claims

1. A pouch-type battery cell sealing device, a pair of sealing rollers that roll while pressing the upper and lower sealing portions of the pouch-type battery cell, The pair of sealing rollers includes a first sealing roller and a second sealing roller, The pair of sealing rollers seal the sealing portion of the pouch-type battery cell while moving from the inside to the outside of the sealing portion of the pouch-type battery cell.

2. 2. The pouch-type battery cell sealing device of claim 1, wherein the first sealing roller rotates in a first direction about a rotation axis, and the second sealing roller rotates in a second direction opposite to the first direction about the rotation axis.

3. The pouch-type battery cell sealing device of claim 1 , wherein the first sealing roller and the second sealing roller press the sealing portion in a heated state.

4. 4. The pouch-type battery cell sealing device according to claim 3, wherein the heating temperatures of the first sealing roller and the second sealing roller are higher than the melting temperature of the inner adhesive layer of the laminate sheet that constitutes the pouch-type battery cell.

5. The pouch-type battery cell sealing device of claim 1 , wherein the diameters of the first sealing roller and the second sealing roller are configured to be 50% or less of the width of the sealing portion.

6. A method for sealing a pouch-type battery cell using the pouch-type battery cell sealing device according to any one of claims 1 to 5, comprising: (a) placing a sealing portion of a pouch-shaped battery cell between a pair of sealing rollers; (b) moving the pair of sealing rollers from the inside to the outside of the sealing portion while independently rotating each of the first sealing roller and the second sealing roller constituting the pair of sealing rollers; Including, In the step (b), the pair of sealing rollers are heated and rotated while moving.

7. The rotation speed and the movement speed of the first sealing roller and the second sealing roller are the same, 7. The method of claim 6, wherein the first sealing roller rotates and moves in a state of pressing downward relative to the sealing portion, and the second sealing roller rotates and moves in a state of pressing upward relative to the sealing portion.

8. The method for sealing a pouch-type battery cell according to claim 6 , wherein an inner adhesive layer of the laminate sheet is melted inside the sealing portion and moved toward the outside of the sealing portion by the pair of sealing rollers.

9. The method of claim 8 , wherein the pair of sealing rollers move from the inside of the sealing portion to the outside until the molten inner adhesive layer moves to the outer edge of the sealing portion.

10. A pouch-type battery case comprising a laminate sheet including an outer resin layer, a metal layer, and an inner adhesive layer, The pouch-type battery case has a sealing portion formed by heat-sealing the inner adhesive layer at the outer periphery of the upper case and the lower case, An inner poly ball is provided inside the sealing portion, An outer poly ball is provided on the outside of the sealing part, A pouch-type battery cell, wherein the outer poly ball is larger in size than the inner poly ball.

11. The pouch-type battery cell according to claim 10 , wherein the outer poly ball does not expose an end surface of the metal layer of the pouch-type battery case.

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