Pouch 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, which can minimize the ratio of dead space due to a sealing part of the pouch-type secondary battery while ensuring excellent sealing and insulation properties, and a sealing tool used in the method.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0132371 dated October 6, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a pouch sealing method for a pouch-type secondary battery and a main sealing tool used in the method. [Background technology]

[0003] Among rechargeable secondary batteries, lithium secondary batteries are attracting attention as a next-generation power source because of their high energy density, no memory effect, low self-discharge even when not in use, and light weight, making them widely used in portable electronic devices such as laptops, cameras, and mobile phones. Taking advantage of their high energy density, they are also increasingly being used in the defense industry, automation systems, automotive, and aviation industries, and are particularly widely used as motor drive sources for electric and hybrid vehicles.

[0004] These lithium secondary batteries can be generally classified into lithium ion batteries using liquid electrolytes and lithium polymer batteries using polymer electrolytes depending on the type of electrolytic solution. These secondary batteries are manufactured in various shapes and can be broadly classified into cylindrical, prismatic, and pouch types.

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

[0006] The pouch-type lithium secondary battery has a sealing portion formed on the edge of the exterior material to seal the pouch exterior material. This edge increases the dead space of the secondary battery, reducing the energy density per volume. Therefore, a technique is used to increase the energy density of the secondary battery by bending or folding the edge sealing portion.

[0007] In addition, a method is also applied in which a sealing portion having a predetermined width is formed at the edge of the exterior material as close as possible to the electrode assembly, thereby minimizing the proportion of dead space due to the sealing portion formed at the edge for exterior materials of the same size.

[0008] For example, Korean Patent No. 10-0883919 discloses a technique of folding the sealing portions of the left and right edges and cutting the corners where the left and right sealing portions intersect with the upper sealing portion in order to fold the sealing portion of the upper edge. However, cutting the corners where the sealing portions of both sides intersect with the upper sealing portion in this way can result in problems such as a deterioration in the sealing reliability of the exterior case, and bending the upper sealing portion along a bending line that is too close to the electrode assembly housed in the exterior case can cause problems such as damage to the connection of the tap-lead coupling portion inside the exterior case or the occurrence of a short circuit between the electrode assembly and the electrode tap. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Korean Patent No. 10-0883919 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been devised to solve the above-mentioned problems of the prior art, The present invention provides a pouch sealing method for a pouch-type secondary battery, which can minimize the proportion of dead space caused by the sealing part of the pouch-type secondary battery while ensuring excellent sealing and insulation properties, and a sealing tool used in the method. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention provides (a) performing degassing sealing including dead space; (b) carrying out the formation process; (c) performing a degassing process; and (d) performing a main sealing; The degassing sealing includes a horizontal sealing portion formed horizontally from the electrode terminal to the end of the dead space, and a horizontal sealing portion formed horizontally from the electrode terminal to the end of the dead space in the opposite direction to the horizontal sealing portion. Electrode assembly storage compartment The inclined sealing portion includes a sloped portion inclined toward the The main sealing performs parallel sealing in the overall length direction of the electrode assembly receiving portion, and also performs a function of correcting the horizontal sealing portion of the overall width sealing portion to be symmetrical with the inclined sealing portion in the opposite direction.

[0012] In one embodiment of the present invention, after the main sealing, a step of forming a sloped portion by removing a horizontal portion of an outer portion of the compensation portion symmetrically with the sloped sealing portion may be further performed.

[0013] In an embodiment of the present invention, the pouch-type secondary battery may have electrode terminals formed in only one direction or in both directions symmetrically.

[0014] In one embodiment of the present invention, the degassing sealing is widthDead space end of direction The length This can include sealing in a direction that is aligned with the direction.

[0015] In one embodiment of the present invention, the degassing sealing is Electrode assembly storage compartment All of width direction end The length or including sealing in a straight line in the direction Electrode assembly storage compartment All of width In the case where the end portion is sealed by the structure of the pouch case, the sealing may not be included.

[0016] In addition, the present invention provides a sealing tool used for the main sealing, Electrode assembly storage compartment and length a linear pressure unit that performs parallel sealing in a direction parallel to the sealing direction; and an inclined pressure unit that is connected to one end of the linear pressure unit so that the interior angle is greater than 90 degrees to 150 degrees, The inclined pressure unit provides a main sealing tool that performs a function of correcting the horizontal sealing unit of the full-width sealing unit so that it is symmetrical with the opposite inclined sealing unit.

[0017] In one embodiment of the present invention, the other end of the linear pressure section the inclined pressure unit; The inclined pressure portions connected in the same direction and at the same interior angle can further be connected.

[0018] In an embodiment of the present invention, the inclined pressure member may have a shape similar to a triangular prism or a square prism.

[0019] In an embodiment of the present invention, the main sealing tool may further include an extension portion in which the linear pressure portion is further extended outside the inclined pressure portion. [Effects of the Invention]

[0020] The pouch sealing method of the pouch-type secondary battery of the present invention minimizes the ratio of dead space due to the sealing portion and provides excellent sealing and insulating properties.

[0021] In addition, the pouch sealing tool used in the method effectively reduces the dead space ratio and provides the pouch case with excellent sealing and insulating properties. [Brief explanation of the drawings]

[0022] [Figure 1] Photograph of the shape of a pouch-type secondary battery with reduced dead space. [Figure 2] 2 is a diagram schematically illustrating a degassing sealing process performed in the process of manufacturing a pouch-type secondary battery having the same structure as that shown in FIG. 1; [Figure 3] 3 is a diagram showing the cause of deterioration in sealing and insulation properties caused by the degassing sealing of the same type as FIG. 2. [Figure 4] 1 is a view showing an embodiment of a degassing sealing among pouch sealings of a pouch-type secondary battery according to the present invention; [Figure 5] 1 is a view showing an embodiment of a main sealing of a pouch sealing of a pouch-type secondary battery according to the present invention; [Figure 6] 1 is an enlarged view of an embodiment of a main sealing of a pouch sealing of a pouch-type secondary battery according to the present invention; [Figure 7] 4 is a diagram illustrating the effect of a degassing sealing in the pouch sealing of the pouch-type secondary battery according to an embodiment of the present invention; [Figure 8] 1 is a perspective view showing an embodiment of a main sealing tool used for main sealing in the pouch sealing of a pouch-type secondary battery of the present invention; FIG. [Figure 9] 1 is a photograph showing the actual shape of a main sealing tool used for main sealing in the pouch sealing of the pouch-type secondary battery of the present invention, and a drawing showing its details. DETAILED DESCRIPTION OF THE INVENTION

[0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The present invention will now be described in detail with reference to the accompanying drawings so that those skilled in the art can easily understand the present invention. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein. The same reference numerals will be used throughout the specification to refer to similar parts.

[0024] When a component is said to be "connected to, provided with, or installed on" another component, it should be understood that it can be directly connected to or installed on the other component, but there can also be other components in between. On the other hand, when a component is said to be "directly connected to, provided with, or installed on" another component, it should be understood that there are no other components in between.

[0025] The present invention will be described below.

[0026] In order to reduce the dead space caused by the sealing portion where the electrode terminals are located in the prior art, a pouch-type secondary battery is manufactured as shown in Fig. 1. To manufacture such a pouch-type secondary battery, a sealing process as shown in Fig. 2 is performed during degassing sealing.

[0027] However, when this sealing structure is applied, the space between the corner of the electrode assembly where the electrode terminal is located and the sealing part is narrow (two parts), as shown in Figure 3. Therefore, when gas existing in the electrode assembly receiving part escapes into this narrow space during the cell pressing process after the formation process, a large pressure is generated, and this pressure damages the inclined sealing part on the dead space side, which also reduces the insulation performance of the sealing part.

[0028] FIG. 4 is a view showing an embodiment of a degassing sealing among pouch sealings of a pouch-type secondary battery of the present invention, and FIG. 5 is a view showing an embodiment of a main sealing among pouch sealings of a pouch-type secondary battery of the present invention.

[0029] The pouch sealing method for a pouch-type secondary battery of the present invention comprises: (a) performing degassing sealing including the dead space 1; (b) carrying out the formation process; (c) performing a degassing process; and (d) performing a main sealing; As shown in FIG. 4, the degassing sealing includes a full-width sealing portion 10 including an electrode terminal sealing portion 11, and a horizontal sealing portion 12 formed horizontally from the electrode terminal 2 to the end of the dead space 1. In the opposite direction of the horizontal sealing portion 12, a horizontal sealing portion 12 is formed between the electrode terminal 2 and the end. Electrode assembly storage compartment 3, and includes a sloped sealing portion 13 including a sloped portion inclined toward the The main sealing (forming the main sealing portion 20) is formed by the electrode assembly receiving portion 3 as shown in FIG. and length The method is characterized by the fact that it includes performing parallel sealing 21 (forming parallel sealing portion 21) parallel to the direction, and at the same time correcting 22 the horizontal sealing portion 12 of the full-width sealing portion so that it is symmetrical with the inclined sealing portion 13 in the opposite direction.

[0030] In the pouch sealing method for the pouch-type secondary battery of the present invention, as shown in FIG. 5(b), after the main sealing, the horizontal part of the outer part of the correcting part 22 is 12 The method may further include a process of forming a sloped portion (chamfering process) by removing the dead space 1 symmetrically with the sloped sealing portion 13. At this time, the dead space 1 may be cut and removed before or after the main sealing.

[0031] In one embodiment of the present invention, the main sealing can be performed using a main sealing tool 100 shown in FIGS.

[0032] As shown in FIGS. 8 and 9, the main sealing tool 100 is parallel to the electrode assembly receiving portion 3 in the entire length direction. Parallel sealing Execution (Parallel sealing part 21 and an inclined pressure unit 120 connected to one end of the linear pressure unit so that the interior angle is greater than 90 degrees to 150 degrees, more preferably 100 degrees to 130 degrees.

[0033] The inclined pressure section 120 is used to correct the horizontal sealing section 12 of the full-width sealing section 10 so that it is symmetrical with the opposite inclined sealing section 13 .

[0034] The other end of the linear pressure unit 110 is The inclined pressure unit 120 The inclined pressure portions 120' may be further connected in the same direction and at the same interior angle.

[0035] In one embodiment of the present invention, in the pouch sealing method for the pouch-type secondary battery, when the main sealing adjusts 22 the horizontal sealing portion 12 of the full-width sealing portion 10 so that it is symmetrical with the inclined sealing portion 13 in the opposite direction, as shown in FIG. 6, the inclined pressure unit 120 of the main sealing tool 100 can be applied only to the inclined portions other than the horizontal sealing portion 12 of the degassing sealing, or can be applied to the horizontal sealing portion 12 and the inclined portion simultaneously.

[0036] In one embodiment of the present invention, the pouch-type secondary battery may have electrode terminals 2 formed on only one side or on both sides symmetrically. When the electrode terminals are formed on both sides symmetrically, the full-width sealing portions 10 on both sides may be formed in the same shape and by the same method.

[0037] In one embodiment of the present invention, the degassing sealing is width End of direction The length Sealing in a straight line and lengthThis can include forming a degassing sealing portion 30 (FIG. 4, 30) in the direction.

[0038] In one embodiment of the present invention, the degassing sealing Electrode assembly storage compartment All of width Direction end (opposite direction of dead space) The length or including sealing in a straight line in the direction Electrode assembly storage compartment All of width In the case where the end portion is sealed by the structure of the pouch case (see FIG. 4), the sealing may not be included.

[0039] According to the pouch sealing method for a pouch-type secondary battery of the present invention, as shown in FIG. Electrode assembly storage compartment A sufficient flow path is formed from the nozzle 3 to the dead space 1. In addition, due to this degassing sealing configuration, as shown in FIG. 7(a), Electrode assembly storage compartment The cross-sectional area of the space where 3 is located is increased by 9.43%, and as shown in FIG. 7(b), the cross-sectional area of the dead space 1 is also increased by 3.99%.

[0040] In one embodiment of the present invention, the degassing sealing in step (a) is a step of sealing including dead space to perform a degassing process for removing gas generated after the formation process, and may be performed by a method known in the art, except for forming the horizontal sealing portion 12 described above. In addition, the formation process in step (b) and the degassing process in step (c) may be performed by a method known in the art.

[0041] The main sealing in step (d) can also be performed by a method known in the art, except for the step of forming the corrective inclined sealing portion 14 in FIG.

[0042] In the present invention, the term "formation process" refers to what is commonly referred to in the art as an activation process. Due to their characteristics, secondary batteries must undergo an activation process during the first cycle to activate the positive electrode active material and form a stable SEI (Solid Electrolyte Interface) layer at the negative electrode. However, this activation process generates a large amount of gas, which then resides within the battery casing. This gas must be removed through an opening or cutout formed in the gas pocket (dead space) of the battery casing, and the casing is then heat-sealed to form the final product (main sealing). The process of removing gas from the battery casing is called a degassing process.

[0043] FIG. 8 is a perspective view showing one embodiment of a main sealing tool 100 used for the main sealing of the pouch sealing of the pouch-type secondary battery of the present invention, and FIG. 9 is a photograph showing the actual shape of the main sealing tool and its details.

[0044] The main sealing tool of the present invention is an electrode assembly housing. and length It is characterized by comprising a linear pressure unit 110 that performs parallel sealing parallel to the direction (Figs. 5 and 20); and an inclined pressure unit 120 that is connected to one end of the linear pressure unit so that the interior angle is greater than 90 degrees to 150 degrees, more preferably 100 degrees to 130 degrees, and the inclined pressure unit 120 performs the function of correcting the horizontal sealing unit 12 of the full-width sealing unit 10 so that it is symmetrical with the inclined sealing unit 13 in the opposite direction.

[0045] In one embodiment of the present invention, the shape of the linear pressure unit 110 is not particularly limited as long as it is capable of performing parallel sealing 21 (forming parallel sealing unit 20), and may be, for example, a square prism shape.

[0046] In one embodiment of the present invention, the other end of the linear pressure unit 110 is The inclined pressure section 120The inclined pressure portions 120' may be further connected in the same direction and at the same interior angle.

[0047] In one embodiment of the present invention, the inclined pressurizing unit 120 is not particularly limited as long as it can form the corrective inclined sealing unit 14 as shown in Fig. 5, and may have a shape similar to a triangular prism, specifically a right-angled triangular prism, as shown in Fig. 8 and Fig. 9. However, the shape is not particularly limited because the corrective inclined sealing unit 14 can also be formed in the shape of a square prism.

[0048] 8 and 9, the main sealing tool 100 may further include an extension 130 that extends the linear pressure applying portion 110 outside the inclined pressure applying portion 120. The extension 130 may function to connect the main sealing tool 100 to a pressure applying device.

[0049] Although the present invention has been described in connection with the preferred embodiments mentioned above, Various modifications and variations can be made without departing from the spirit and scope of the invention, and it is intended that the appended claims cover all such modifications and variations as fall within the spirit and scope of the invention. [Explanation of symbols]

[0050] 1: Dead Space 2: Electrode terminal 3: Electrode assembly storage compartment 10: Full width sealing section 11: Electrode terminal sealing part 12: Horizontal sealing section 13: Inclined ceiling section 14: Correction inclined ceiling part 15:Horizontal part 20: Main ceiling section 21: Parallel sealing section 22: Correction section 30: lengthDegassing sealing part in the direction 100: Main ceiling tool 110: Linear pressure section 120: Inclined pressure section 130: Extension part

Claims

1. (a) performing degassing sealing including dead space; (b) performing a formation process; (c) performing a degassing process; and (d) performing a main sealing; The degassing sealing is performed such that the full-width sealing portion including the electrode terminal sealing portion includes a horizontal sealing portion formed horizontally from the electrode terminal to the end of the dead space, and an inclined sealing portion including an inclined portion inclined toward the electrode assembly receiving portion between the electrode terminal and the end on the opposite side of the horizontal sealing portion, The main sealing is parallel sealing that is parallel to the length direction of the electrode assembly receiving portion, and at the same time, a sealing that corrects the horizontal sealing portion of the full-width sealing portion to be symmetrical with an inclined sealing portion in the opposite direction.

2. 2. The pouch sealing method for a pouch-type secondary battery according to claim 1, wherein after the main sealing, a horizontal portion of an outer portion of the correction portion is removed symmetrically with the inclined sealing portion to form an inclined portion.

3. 2. The pouch sealing method of claim 1, wherein the electrode terminals of the pouch-type secondary battery are formed in one direction or in two directions symmetrically to each other.

4. 2. The pouch sealing method for a pouch-type secondary battery according to claim 1, wherein the degassing sealing comprises sealing a full-width end portion of the dead space in a straight line in the length direction, the end portion being an end in a direction parallel to the full-width sealing portion.

5. 2. The pouch sealing method for a pouch-type secondary battery according to claim 1, wherein the degassing sealing includes sealing an end portion of the electrode assembly receiving portion in a linear manner in the length direction, or does not include sealing an end portion of the electrode assembly receiving portion in a direction parallel to the end portion of the electrode assembly receiving portion in a width direction when the end portion is sealed by the structure of the pouch case.

6. A sealing tool used for the main sealing performed in the pouch sealing method for a pouch-type secondary battery according to claim 1 includes: a linear pressure unit that performs parallel sealing parallel to the length direction of the electrode assembly receiving unit; and an inclined pressure unit that is connected to one end of the linear pressure unit so that an interior angle between 90 degrees and 150 degrees is formed, The inclined pressure unit is a main sealing tool that performs the function of correcting the horizontal sealing unit of the full-width sealing unit so that it is symmetrical with the opposite inclined sealing unit.

7. 7. The main sealing tool according to claim 6, wherein an inclined pressure part is further connected to the other end of the linear pressure part in the same direction and at the same interior angle as the inclined pressure part.

8. The main sealing tool according to claim 6 or 7, wherein the inclined pressure portion has a triangular or quadrangular prism shape.

9. 8. The main sealing tool according to claim 6 or 7, wherein the main sealing tool further comprises an extension portion in which the linear pressure portion is further extended outside the inclined pressure portion.

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