Bag sealing method for pouch-type secondary battery and main sealing tool used in the method

Abstract

The present invention provides a pouch sealing method for a pouch-type secondary battery and a sealing tool used in the method, which can ensure excellent sealing and insulation properties while minimizing the proportion of dead space due to the sealing portion of the pouch-type secondary battery.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0132371, filed on October 6, 2021, the entire contents of which are incorporated herein by reference.

[0002] This invention relates to a bag sealing method for pouch-type secondary batteries and a main sealing tool used in the method. Background Technology

[0003] Lithium-ion batteries, among rechargeable secondary batteries, are attracting attention as a next-generation power source due to their high energy density, lack of memory effect, low self-discharge even when not in use, and very light weight. Therefore, lithium-ion batteries are frequently used in portable electronic devices such as laptops, cameras, and mobile phones. Furthermore, due to their high energy density, lithium-ion batteries are increasingly used in the defense industry, automation systems, automotive, and aerospace industries, and are widely commercially available as motor drive sources for electric and hybrid vehicles.

[0004] Based on the type of electrolyte, lithium-ion batteries can generally be divided into lithium-ion batteries that use liquid electrolytes and lithium-polymer batteries that use polymer electrolytes. Furthermore, secondary batteries are manufactured in various shapes and can be broadly categorized as cylindrical, prismatic, and pouch-type.

[0005] In particular, pouch-type lithium secondary batteries have a casing made of pouch-encapsulating material that is significantly lighter and more flexible than aluminum casings, and pouch-type lithium secondary batteries can have a higher energy density than prismatic lithium secondary batteries.

[0006] In pouch-type lithium secondary batteries, a sealing portion is formed at the edge of the casing material to seal the pouch casing material. Since this edge increases the dead zone of the secondary battery and leads to a decrease in energy density per unit volume, a technique is used to increase the energy density of the secondary battery by bending or folding this edge sealing portion.

[0007] In addition, a method is applied that minimizes the proportion of dead zones caused by forming a seal of a predetermined width as close as possible to the electrode assembly at the edge of the housing material compared to housing materials of the same size.

[0008] For example, Korean Patent Publication No. 10-0883919 discloses a technique where the corner where the left and right sealing portions intersect with the upper sealing portion is cut to fold the sealing portions at the left and right edges and the sealing portion at the upper edge. However, when the corner where the two sealing portions intersect with the upper sealing portion is cut in this manner, there is a problem of deterioration in the sealing reliability of the housing material. Furthermore, when the upper sealing portion is bent along a bend line that is too close to the electrode assembly housed in the housing material, there is a possibility that the connection of the tab-lead joint inside the housing material may be damaged or a short circuit may occur between the electrode assembly and the electrode tab.

[0009] [Existing Technical Documents]

[0010] Korean Patent Publication No. 10-0883919 Summary of the Invention

[0011] Technical issues

[0012] This invention is designed to solve the aforementioned problems in the related art.

[0013] The object of the present invention is to provide a bag sealing method for a pouch-type secondary battery that can ensure excellent sealing and insulation properties while minimizing the proportion of dead zones caused by the sealing portion of the pouch-type secondary battery, and a sealing tool used in the method.

[0014] Technical solution

[0015] To achieve the above objectives, the present invention provides a bag sealing method for pouch-type secondary batteries, the method comprising:

[0016] (a) Perform a degassing and sealing procedure that includes a dead zone;

[0017] (b) Performing the formation process steps;

[0018] (c) The steps of performing the degassing process; and

[0019] (d) Perform the main sealing procedure.

[0020] The degassing seal is performed such that the full-width seal, including the electrode terminal seal, comprises: a horizontal seal formed in the horizontal direction from the electrode terminal to the end of the dead zone, and an inclined seal in the opposite direction to the horizontal seal, wherein the inclined seal includes an inclined portion inclined towards the electrode assembly receiving portion between the electrode terminal and the end.

[0021] The main seal includes: a parallel seal parallel to the entire length of the electrode assembly receiving portion, and a seal that modifies the horizontal sealing portion of the full-width sealing portion to be symmetrical to the inclined sealing portion in the opposite direction.

[0022] In an embodiment of the invention, after the main seal, the correction portion and the horizontal portion outside the inclined seal portion can be symmetrically removed to form the inclined portion.

[0023] In embodiments of the present invention, the electrode terminals of the pouch-type secondary battery may be formed in only one direction or in two directions that are symmetrical to each other.

[0024] In an embodiment of the present invention, the degassing seal may include sealing the end of the dead zone in the full width direction in a straight line along the full length direction.

[0025] In embodiments of the present invention, the degassing seal may include sealing the end of the electrode assembly receiving portion in the full width direction in a straight line along the full length direction; or when the end of the electrode assembly receiving portion in the full width direction is sealed by the bag housing structure, the sealing of that end is not included.

[0026] Furthermore, the present invention provides a main sealing tool for a main seal, the main sealing tool comprising:

[0027] A linear pressing part that performs a parallel seal along the entire length of the electrode assembly receiving portion; and

[0028] An inclined pressing portion is attached to one end of the linear pressing portion, and the interior angle between the inclined pressing portion and the linear pressing portion is greater than 90 degrees and up to 150 degrees.

[0029] The inclined pressing portion performs the function of correcting the horizontal sealing portion of the full-width sealing portion to be symmetrical with the inclined sealing portion in the opposite direction.

[0030] In an embodiment of the present invention, the other end of the straight pressing part may also be combined with an inclined pressing part in the same direction and at the same internal angle as the inclined pressing part.

[0031] In embodiments of the present invention, the inclined pressing portion may have a shape similar to a triangular prism or a quadrangular prism.

[0032] In an embodiment of the present invention, the main sealing tool may further include an extension portion that extends further outward from the inclined pressing portion.

[0033] Beneficial effects

[0034] The bag sealing method for pouch-type secondary batteries of the present invention provides excellent sealing and insulation properties while minimizing the proportion of dead zones in the sealing portion.

[0035] Furthermore, the bag sealing tool used in the above method effectively reduces the proportion of dead zone and provides excellent sealing and insulation properties for the bag shell. Attached Figure Description

[0036] Figure 1 It is a photograph of a pouch-type secondary battery with a reduced dead zone.

[0037] Figure 2 It is an illustrative representation of the manufacturing process with Figure 1 A diagram illustrating the degassing and sealing process performed during the manufacturing of a pouch-type secondary battery of the form shown.

[0038] Figure 3 It is shown by Figure 2 A diagram illustrating the causes of deterioration in sealing and insulation properties due to degassing seals of the type shown.

[0039] Figure 4 This is a diagram illustrating an embodiment of the degassing seal in the bag seal of the pouch-type secondary battery of the present invention.

[0040] Figure 5 This is a diagram illustrating an embodiment of the main seal in the bag seal of the pouch-type secondary battery of the present invention.

[0041] Figure 6 This is an enlarged view of an embodiment of the main seal in the bag seal of the pouch-type secondary battery of the present invention.

[0042] Figure 7 This is a diagram illustrating the effect of an embodiment of the degassing seal in the bag seal of the pouch-type secondary battery of the present invention.

[0043] Figure 8 This is a perspective view illustrating an embodiment of the main sealing tool used in the main seal of the pouch seal of the pouch-type secondary battery of the present invention.

[0044] Figure 9 This is a photograph and a diagram showing the actual shape of the main sealing tool used in the main seal of the pouch seal of the pouch-type secondary battery of the present invention, and its specifications. Detailed Implementation

[0045] The invention will now be described in detail with reference to the accompanying drawings, enabling those skilled in the art to readily implement it. However, the invention can be embodied in many different forms and is not limited to the embodiments described herein.

[0046] When a component is described as "connected to another component, placed in another component, or installed in another component," the component may be directly connected to or installed in the other component; however, it should be understood that other components may exist between them. On the other hand, when a component is described as "directly connected to another component, directly placed in another component, or directly installed in another component," it should be understood that there are no other components between them.

[0047] The present invention will now be described.

[0048] In related technologies, manufacturing having such Figure 1 The pouch-type secondary battery shown is designed to reduce the dead zone caused by the sealing portion on the side where the electrode terminals are located. To manufacture the pouch-type secondary battery as described above, the degassing and sealing process is performed... Figure 2 The seal is of the form shown.

[0049] However, when this sealing structure is applied, such as Figure 3 As shown, the space between the edge of the electrode assembly on the side where the electrode terminal is located and the seal is formed to be relatively narrow. Therefore, after the formation process, when the gas present in the electrode assembly housing escapes from this narrow space during the battery pressing process, a large pressure is generated, and the inclined seal on the dead zone side is damaged by this pressure. As a result, the insulation properties of the seal are also deteriorated.

[0050] Figure 4 This is a diagram illustrating an embodiment of the degassing seal in the bag seal of the pouch-type secondary battery of the present invention. Figure 5 This is a diagram illustrating an embodiment of the main seal in the bag seal of the pouch-type secondary battery of the present invention.

[0051] The bag sealing method for the bag-type secondary battery of the present invention includes:

[0052] (a) Perform the degassing and sealing steps, including dead zone 1;

[0053] (b) Performing the formation process steps;

[0054] (c) The steps of performing the degassing process; and

[0055] (d) Perform the main seal procedure.

[0056] like Figure 4 As shown, a degassing seal is performed such that the full-width seal portion 10, including the electrode terminal seal portion 11, includes: a horizontal seal portion 12 formed in the horizontal direction from the electrode terminal 2 to the end of the dead zone 1, and an inclined seal portion 13 in the opposite direction to the horizontal seal portion 12, wherein the inclined seal portion 13 includes an inclined portion inclined towards the electrode assembly receiving portion 3 between the electrode terminal 2 and the end.

[0057] like Figure 5 As shown, performing the main seal includes performing a parallel seal that is parallel to the entire length of the electrode assembly receiving portion 3, and performing a correction such that the horizontal sealing portion 12 of the full-width sealing portion is symmetrical to the inclined sealing portion 13 in the opposite direction.

[0058] like Figure 5 As shown in (b), the bag sealing method for pouch-type secondary batteries according to the present invention may further include a step (beveling step) of forming the inclined portion by symmetrically removing the horizontal portions 12 and 15 outside the inclined sealing portion 13 after the main seal. At this time, the dead zone 1 may be removed by cutting before or after the main seal.

[0059] In embodiments of the present invention, the following methods may be used: Figure 8 and Figure 9 The main sealing tool 100 shown is used to perform the main sealing.

[0060] like Figure 8 and Figure 9 As shown, the main sealing tool 100 may include: a linear pressing portion 110 that performs a parallel seal (forming a parallel sealing portion 21) parallel to the entire length of the electrode assembly receiving portion 3; and an inclined pressing portion 120 coupled to one end of the linear pressing portion, wherein the inner angle between the inclined pressing portion and the linear pressing portion is greater than 90 degrees to 150 degrees, more preferably 100 degrees to 130 degrees.

[0061] The inclined pressing part 120 is used to correct the horizontal sealing part 12 of the full-width sealing part 10 to be symmetrical with the inclined sealing part 13 in the opposite direction.

[0062] The other end of the straight pressing part 110 may also be combined with an inclined pressing part 120', wherein the inclined pressing part 120' is combined with the inclined pressing part 120 in the same direction and with the same interior angle.

[0063] In an embodiment of the present invention, in a bag sealing method for a pouch-type secondary battery, when the main seal is modified such that the horizontal sealing portion 12 of the full-width sealing portion 10 is symmetrical to the inclined sealing portion 13 in the opposite direction, as... Figure 6 As shown, the inclined pressing portion 120 of the main sealing tool 100 can be applied only to the remaining inclined portion other than the horizontal sealing portion 12 used for degassing sealing, or it can be applied to both the horizontal sealing portion 12 and the inclined portion.

[0064] In embodiments of the present invention, in a pouch-type secondary battery, the electrode terminals 2 may be formed in only one direction, or may exist in two directions symmetrical to each other. When the electrode terminals exist in two directions symmetrical to each other, the full-width sealing portions 10 on both sides may be formed in the same form and in the same manner.

[0065] In embodiments of the present invention, the degassing seal may include: sealing the end of the dead zone 1 in a straight line along its entire length in the full width direction to form a full-length degassing seal portion. Figure 4 (30).

[0066] In embodiments of the present invention, the degassing seal may include: sealing the end of the electrode assembly housing in the full width direction (opposite to the dead zone) in a straight line along its entire length. This is possible if the end of the electrode assembly housing in the full width direction is sealed by the bag housing structure (see...). Figure 4 If the seal is not included, then it may not be included.

[0067] The bag sealing method for pouch-type secondary batteries according to the present invention, such as Figure 7 As shown, a sufficient flow path is formed, allowing gas to escape from the electrode assembly housing 3 to the dead zone 1 during the degassing process. Furthermore, this degassing sealing method provides the following effects: Figure 7 As shown in (a), the cross-sectional area of ​​the space where the electrode assembly housing 3 is located increases by 9.43%, and as... Figure 7 As shown in (b), the cross-sectional area of ​​dead zone 1 also increases by 3.99%.

[0068] In an embodiment of the present invention, the degassing seal in step (a) is to seal the dead zone to perform a degassing process for removing gases generated after the formation process, and can be performed by methods known in the art, except for forming the horizontal seal portion 12 as described above. Furthermore, the formation process in step (b) and the degassing process in step (c) can be performed by methods known in the art.

[0069] Even in the case of the main seal in step (d) above, in addition to forming Figure 5 In addition to the process of modifying the inclined sealing part 14, it can also be performed by methods known in the art.

[0070] The formation process in this invention refers to the process also known in the field as the activation process. Due to the characteristics of secondary batteries, an activation process is required before the initial cycle to activate the anode active material and form a stable solid electrolyte interface (SEI) film at the cathode. However, the activation process generates a large amount of gas that exists inside the casing material. This gas needs to be removed by openings or cuts formed in the gas pockets (dead zones) of the casing material, and the casing material is then thermally welded and sealed to form the final product shape (main seal). The process of removing the gas inside the secondary battery in this way is called the degassing process.

[0071] Figure 8 This is a perspective view illustrating an embodiment of the main sealing tool 100 used in the main seal of the pouch seal of the pouch-type secondary battery of the present invention. Figure 9 It is a photograph showing the actual shape of the main sealing tool and a diagram illustrating its specifications.

[0072] The main sealing tool of the present invention includes: a linear pressing portion 110 that performs a parallel seal parallel to the entire length of the electrode assembly receiving portion; and an inclined pressing portion 120 coupled to one end of the linear pressing portion, wherein the interior angle between the inclined pressing portion and the linear pressing portion is greater than 90 degrees to 150 degrees, more preferably 100 degrees to 130 degrees. The inclined pressing portion 120 performs the function of correcting the horizontal sealing portion 12 of the full-width sealing portion 10 to be symmetrical with the inclined sealing portion 13 in the opposite direction.

[0073] In embodiments of the present invention, although the shape of the linear pressing part 110 is not particularly limited, as long as it is a shape that can perform parallel sealing (forming parallel sealing part 21), it may have a quadrangular prism shape.

[0074] In an embodiment of the present invention, the other end of the straight pressing part 110 may also be combined with the inclined pressing part 120' in the same direction and at the same internal angle as the inclined pressing part 120.

[0075] In embodiments of the present invention, although the tilting pressing portion 120 is not particularly limited, as long as it has the ability to form such a Figure 5 The shape of the modified inclined sealing part 14 shown is acceptable, but as Figure 8 and 9 As shown, it can be in a shape similar to a triangular prism, especially a right-angled triangular prism. However, since a modified inclined sealing portion 14 can be formed even in the case of a quadrangular prism shape, the shape is not particularly limited.

[0076] In embodiments of the present invention, the main sealing tool 100 may further include an extension 130 extending outward from the inclined pressing portion 120 from the straight pressing portion 110, such as... Figure 8 and Figure 9 As shown. The extension 130 can perform the function of connecting the main sealing tool 100 to the pressing device.

[0077] Although the invention has been described in conjunction with the preferred embodiments above, various modifications and variations may be made without departing from the spirit and scope of the invention. Therefore, the appended claims should encompass these modifications or variations, provided they fall within the spirit of the invention.

[0078] [Explanation of reference markers]

[0079] 1: Dead zone 2: Electrode terminal

[0080] 3. Electrode assembly receiving part 10: Full-width sealing part

[0081] 11: Electrode terminal sealing part; 12: Horizontal sealing part

[0082] 13: Inclined sealing part 14: Modified inclined sealing part

[0083] 15: Horizontal section; 20: Main sealing section

[0084] 21: Parallel sealing part; 22: Correction part

[0085] 30: Degassing seal along the entire length

[0086] 100: Main sealing tool; 110: Linear pressing part

[0087] 120, 120': Inclined pressing part; 130, 130': Extension part.

Claims

1. A method for sealing a pouch-type secondary battery, the method comprising: (a) Perform a degassing and sealing procedure that includes a dead zone; (b) Performing the formation process steps; (c) The steps for performing the degassing process; as well as (d) Perform the main sealing procedure. The degassing seal is performed such that the full-width seal, including the electrode terminal seal, comprises: a horizontal seal formed in the horizontal direction from the electrode terminal to the end of the dead zone, and an inclined seal in the opposite direction to the horizontal seal, wherein the inclined seal includes an inclined portion inclined towards the electrode assembly receiving portion between the electrode terminal and the end. The main seal includes: a parallel seal parallel to the entire length of the electrode assembly receiving portion, and a seal that modifies the horizontal sealing portion of the full-width sealing portion to be symmetrical to the inclined sealing portion in the opposite direction.

2. The bag sealing method for a pouch-type secondary battery according to claim 1, wherein after the main seal, the correction portion and the horizontal portion outside the inclined seal portion are symmetrically removed to form the inclined portion.

3. The bag sealing method for a pouch-type secondary battery according to claim 1, wherein the electrode terminals of the pouch-type secondary battery are formed only in one direction or in two directions symmetrical to each other.

4. The bag sealing method for a pouch-type secondary battery according to claim 1, wherein the degassing seal comprises sealing the end of the dead zone in the full width direction along the full length direction in a straight line.

5. The bag sealing method for a pouch-type secondary battery according to claim 1, wherein the degassing seal includes sealing the end of the electrode assembly receiving portion in the full width direction along the full length direction in a straight line; or, when the end of the electrode assembly receiving portion in the full width direction is sealed by the bag housing structure, excluding the sealing of that end.

6. A primary sealing tool for the primary seal in the bag sealing method according to claim 1, comprising: A linear pressing part that performs a parallel seal along the entire length of the electrode assembly receiving part; as well as An inclined pressing portion is attached to one end of the linear pressing portion, and the interior angle between the inclined pressing portion and the linear pressing portion is greater than 90 degrees and up to 150 degrees. The inclined pressing portion performs the function of correcting the horizontal sealing portion of the full-width sealing portion to be symmetrical with the inclined sealing portion in the opposite direction.

7. The main sealing tool according to claim 6, wherein the other end of the straight pressing portion is also joined with an inclined pressing portion in the same direction and at the same internal angle as the inclined pressing portion.

8. The main sealing tool according to any one of claims 6 and 7, wherein the inclined pressing portion has a shape similar to a triangular prism or a quadrangular prism.

9. The main sealing tool according to any one of claims 6 and 7, wherein the main sealing tool further comprises an extension of the straight pressing portion extending further outward from the inclined pressing portion.

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