Sealing device and pouch-type secondary battery sealed thereby

Abstract

A sealing device according to one embodiment of the present invention can seal a pouch-type battery case including a housing portion in which an electrode assembly is housed and a terrace portion located on the periphery of the housing portion. The sealing device may include a pair of sealing tools facing each other across the terrace portion and configured such that the distance between them is adjustable. Each sealing tool may include a protrusion protruding toward the terrace portion and a recess formed to have a step relative to the protrusion. When the pair of sealing tools press the terrace portion, the distance between the protrusions of the pair of sealing tools may be adjusted to be 68% to 82% of the initial thickness of the terrace portion.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0182074 filed on December 22, 2022 and Korean Patent Application No. 10-2023-0188447 filed on December 21, 2023, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a sealing device for sealing terrace portions of a pouch-type battery case, and to a pouch-type secondary battery sealed thereby. [Background technology]

[0003] Lithium secondary batteries are generally manufactured by coating a positive electrode active material slurry on a positive electrode current collector and a negative electrode current collector to form a positive electrode and a negative electrode, laminating them on both sides of a separator to form an electrode assembly of a predetermined shape, and then placing the electrode assembly in a pouch and injecting an electrolyte solution into it.

[0004] Secondary batteries are classified into pouch types, can types, etc. depending on the material of the case that houses the electrode assembly. Among them, pouch-type secondary batteries are generally manufactured by forming a housing portion in a flexible pouch film, housing the electrode assembly in the housing portion, injecting an electrolyte solution, and then sealing the terrace portion around the housing portion.

[0005] Conventionally, in pouch-type secondary batteries, when sealing terrace portions including gas pocket portions, a flat pattern is used to form the seal portion.

[0006] However, due to insufficient seal strength at the seal, especially at the area where the innermost layers of the battery case are sealed together, venting occurs earlier than intended by the designer. More specifically, gas generated during high-temperature storage and charge / discharge cycles of the secondary battery increases pressure on the terrace area. Once the innermost layer of the battery case begins to rupture at the seal, the flat pattern seal has no part to prevent the rupture, so the ruptured area increases rapidly over time, eventually causing venting.

[0007] Therefore, there is a need to increase the seal strength at the portion where the innermost layers of the battery case are sealed together and to delay abnormal venting. Summary of the Invention [Problem to be solved by the invention]

[0008] One problem to be solved by the present invention is to provide a sealing device that forms a seal portion having high sealing strength and a rupture delay effect.

[0009] Another problem to be solved by the present invention is to provide a pouch-type secondary battery including a seal portion having high seal strength and a rupture delay effect. [Means for solving the problem]

[0010] A sealing device according to one embodiment of the present invention can seal a pouch-type battery case including a housing portion in which an electrode assembly is housed and a terrace portion located on the periphery of the housing portion. The sealing device may include a pair of sealing tools facing each other across the terrace portion and configured such that the distance between them is adjustable. Each sealing tool may include a protrusion protruding toward the terrace portion and a recess formed to have a step relative to the protrusion. When the pair of sealing tools press the terrace portion, the distance between the protrusions of the pair of sealing tools may be adjusted to be 68% to 82% of the initial thickness of the terrace portion.

[0011] The protrusion may be located at the innermost portion of the sealing tool.

[0012] The protrusions and depressions may be arranged alternately across the width of the sealing tool.

[0013] When the pair of sealing tools pressurize the terrace portions, the distance between the recesses of the pair of sealing tools may be adjusted to be 86% to 99% of the initial thickness of the terrace portions.

[0014] The plurality of protrusions may include a first protrusion and a second protrusion positioned outward from the first protrusion and having a width narrower than that of the first protrusion.

[0015] The width of the recess may be narrower than the width of the innermost protrusion.

[0016] The plurality of protrusions may have a width that is wider as they are positioned more inward in the width direction of the sealing tool.

[0017] The single protrusion may be located inwardly of the recess.

[0018] When the pair of sealing tools pressurize the terrace portions, the distance between the recesses of the pair of sealing tools may be adjusted to be 78% to 92% of the initial thickness of the terrace portions.

[0019] Each sealing tool may include a first pressure region that seals the inner surfaces of the terrace portions with an insulating member surrounding an electrode lead connected to the electrode assembly, and a second pressure region that seals the inner surfaces of the terrace portions with each other. The protrusion and depression may be included in the second pressure region.

[0020] A pouch-type secondary battery according to an embodiment of the present invention may include an electrode assembly, a pouch-type battery case having a housing that houses the electrode assembly, and a terrace portion located on the periphery of the housing. The terrace portion may include a seal portion and a gas pocket portion located between the seal portion and the housing. The seal portion may include a thin portion extending along the edge of the seal portion and a thick portion extending parallel to the thin portion and thicker than the thin portion. The thickness of the thin portion may be 68% to 82% of the thickness of the gas pocket portion.

[0021] The thin portion may be located at the innermost side of the sealed portion.

[0022] The thin portions and thick portions may be formed alternately in the width direction of the seal portion.

[0023] The thickness of the thick portion may be 86% to 99% of the thickness of the gas pocket portion.

[0024] The plurality of thin portions may include a first thin portion and a second thin portion located outside the first thin portion and having a width narrower than that of the first thin portion.

[0025] The width of the thick portion may be narrower than the width of the innermost thin portion.

[0026] The thinner portions may have a wider width as they are positioned more inward in the width direction of the seal portion.

[0027] The single thin portion may be located more inward than the thick portion in the width direction of the seal portion.

[0028] The thickness of the thick portion may be 78% to 92% of the thickness of the gas pocket portion.

[0029] The pouch-type secondary battery may further include an electrode lead connected to the electrode assembly and protruding outside the terrace portion, and an insulating member that insulates the electrode lead from the battery case. The sealing portion may include a first sealing region where the inner surfaces of the terrace portion are sealed to the insulating member, and a second sealing region where the inner surfaces of the terrace portions are sealed to each other. The thin portion and the thick portion may be included in the second sealing region. [Effects of the Invention]

[0030] According to a preferred embodiment of the present invention, the seal strength of the seal portion formed in the pouch-type battery case is increased, thereby making it possible to prevent or delay the occurrence of abnormal venting.

[0031] Other effects may be included that can be easily predicted by a person skilled in the art from the configuration according to the preferred embodiment of the present invention.

[0032] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited solely to the matters depicted in such drawings. [Brief explanation of the drawings]

[0033] [Figure 1] 1 is an assembly diagram of a pouch-type secondary battery according to an embodiment of the present invention. [Figure 2] 1 is a plan view of a pouch-type secondary battery according to an embodiment of the present invention; [Figure 3] 1 is a perspective view of a sealing device according to an embodiment of the present invention; [Figure 4a] 4 is an enlarged view of a second pressurizing region and its surroundings of the sealing device shown in FIG. 3. FIG. [Figure 4b] 4 is an enlarged view of a second pressurizing region and its surroundings of the sealing device shown in FIG. 3. FIG. [Figure 5] 5 is a schematic diagram for explaining the operation of the sealing device according to the embodiment of the present invention. FIG. [Figure 6] 6 is an enlarged cross-sectional view of the sealing tool shown in FIG. 5 and the seal formed by the sealing tool on the pouch-type battery case. FIG. [Figure 7] 10 is an enlarged cross-sectional view of a sealing tool according to another embodiment of the present invention and a seal formed by the sealing tool on a pouch-type battery case. FIG. [Figure 8a] 10 is a graph summarizing the results of an experiment conducted to confirm the effect of the sealing device according to one embodiment of the present invention. [Figure 8b] 10 is a graph summarizing the results of an experiment conducted to confirm the effect of the sealing device according to one embodiment of the present invention. [Figure 8c] 10 is a graph summarizing the results of an experiment conducted to confirm the effect of the sealing device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0034] The present invention will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily understand the preferred embodiments of the present invention. However, the present invention can be realized in various different forms and is not limited to the following embodiments.

[0035] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the explanation or related known technologies that may obscure the gist of the present invention will be omitted, and when assigning reference symbols to components in each drawing in this specification, the same or similar reference symbols will be assigned to the same or similar components throughout the specification.

[0036] Furthermore, the terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, in accordance with the principle that an inventor can appropriately define the concept of a term in order to best explain his or her invention.

[0037] FIG. 1 is an assembly diagram of a pouch-type secondary battery according to one embodiment of the present invention.

[0038] A pouch-type secondary battery 1 (hereinafter referred to as "secondary battery") according to one embodiment of the present invention may be a secondary battery sealed by a sealing device according to the present invention. The secondary battery 1 described in this specification may be in a state at a particular point in the manufacturing process or in a final completed state, and can be interpreted appropriately according to the context or need.

[0039] The secondary battery 1 may include an electrode assembly 10 and a pouch-type battery case 20 (hereinafter referred to as a "battery case").

[0040] The electrode assembly 10 may be formed by alternately stacking positive and negative electrodes with a separator interposed therebetween. That is, the electrode assembly 10 may include a plurality of electrodes and a separator interposed between the plurality of electrodes to insulate the plurality of electrodes from one another. The electrode assembly 10 may be housed together with an electrolyte in a battery case 20, more specifically, in a housing portion 22 described below.

[0041] The electrode assembly 10 may be of various types, such as a stack type, a jelly roll type, or a stack-and-fold type, and the type of the electrode assembly 10 is not limited.

[0042] The electrode assembly 10 may include electrode tabs 11. The electrode tabs 11 are connected to the positive and negative electrodes of the electrode assembly 10, respectively, and protrude from the electrode assembly 10 to the outside, thereby functioning as a path for electrons to move between the inside and outside of the electrode assembly 10.

[0043] The electrode tab 11 may be formed by cutting the uncoated portion of the electrode current collector, or by connecting another conductive member to the uncoated portion by ultrasonic welding or the like.

[0044] The electrode tabs 11 may include a positive electrode tab 11a connected to the positive electrode and a negative electrode tab 11b connected to the negative electrode. The positive electrode tab 11a and the negative electrode tab 11b may protrude in different directions from the electrode assembly 10, but are not limited thereto, and may be formed to protrude in various directions, such as protruding in parallel in the same direction from one side.

[0045] An electrode lead 12 that supplies electricity to the outside of the battery cell 1 may be connected to the electrode tab 11 of the electrode assembly 10. A portion of the electrode lead 12 may be surrounded by an insulating member 14. The insulating member 14 may be sealed together with the first case 20a and the second case 20b. Thus, the insulating member 14 insulates the electrode lead 12 from the battery case 20 and maintains the seal of the battery case 20. Generally, insulating tape, which is easy to attach to the electrode lead 12 and has a relatively thin thickness, is often used as the insulating member 14, but the insulating member is not limited to this and various materials can be used as long as they can insulate the electrode lead 12.

[0046] One end of the electrode lead 12 may be connected to the electrode tab 11, and the other end may protrude outside the battery case 20. The electrode lead 12 may include a positive electrode lead 12a connected to the positive electrode tab 11a and a negative electrode lead 12b connected to the negative electrode tab 11b.

[0047] The electrode lead 12 can electrically connect the electrode assembly 10 to the outside. In addition, since the positive electrode tab 11a and the negative electrode tab 11b are formed to protrude in different directions, the positive electrode lead 12a and the negative electrode lead 12b can also extend in different directions.

[0048] The battery case 20 can accommodate the electrode assembly 10 therein, and may be formed by molding a laminate sheet. For example, when a flexible laminate sheet is drawn using a die, a punch, or the like, a portion of the laminate sheet is stretched to form the accommodation portion 22 having a pocket-shaped accommodation space, thereby manufacturing the battery case 20.

[0049] However, the configuration of the receiving portion 22 is not limited thereto and may be formed in a manner different from that shown in the drawings. For example, the receiving portion 22 may be formed by folding the laminate sheet into a predetermined shape.

[0050] Hereinafter, the battery case 20 may refer to a state at a particular point in the manufacturing process or a final completed state. That is, the description of the battery case 20 encompasses both the sealed state shown in FIG. 2 and the expanded state shown in FIG. 1, and can be interpreted appropriately according to the context and needs.

[0051] The battery case 20 may house the electrode assembly 10 and be sealed so that a portion of the electrode lead 12 is exposed.

[0052] The battery case 20 may include a first case 20a and a second case 20b that are sealed to each other via the electrode assembly 10.

[0053] At least one of the first case 20a and the second case 20b preferably has a storage section 22. The peripheral area of ​​the storage section 22 may form a terrace section 23. That is, the battery case 20 may include the storage section 22 and the terrace section 23 located outside the storage section 22.

[0054] The first case 20a and the second case 20b may be connected to each other by the folding portion 21. However, this is not limitative, and it goes without saying that the first case 20a and the second case 20b may be separated and manufactured separately.

[0055] The receiving portion 22 can define a receiving space capable of receiving the electrode assembly 10. The receiving portion 22 may have a pocket shape.

[0056] The following description will be given taking as an example a case where the housing portion 22 is formed in each of the first case 20a and the second case 20b. Those skilled in the art will be able to easily understand a case where the housing portion 22 is formed in only one of the pair of cases 20a, 20b.

[0057] The accommodating portions 22 of the pair of cases 20a, 20b are arranged opposite to each other and can both accommodate the electrode assembly 10. That is, the accommodating portions 22 of the pair of cases 20a, 20b are arranged opposite to each other and can define an accommodating space for accommodating the electrode assembly 10. In this case, the electrode assembly 20 can accommodate an electrode assembly 10 that is thicker and has a larger capacity than when the accommodating portion 22 is formed in only one of the pair of cases 20a, 20b.

[0058] First case 20a and second case 20b may be connected to each other by folding portion 21. When first case 20a and second case 20b are unfolded, a portion of folding portion 21 may be located between storage portion 22 of first case 20a and storage portion 22 of second case 20b, and another portion of folding portion 21 may be located between terrace portion 23 of first case 20a and terrace portion 23 of second case 20b.

[0059] When the folding portion 21 is folded, the first case 20a and the second case 20b may face each other. The folding portion 21 may extend parallel to the overall length of the electrode assembly 10, but is not limited thereto.

[0060] Each of the cases 20 a and 20 b may include a terrace portion 23 located on the periphery of the housing portion 22 .

[0061] When the first case 20a and the second case 20b are separate members that are not connected to each other by the folding portion 21, the terrace portion 23 may be formed on the periphery of the four sides of the storage portion 22.

[0062] When the first case 20a and the second case 20b are connected to each other by the folding portion 21, the terrace portion 23 may be formed on the periphery of three of the four sides of the storage portion 22, excluding the side facing the folding portion 21.

[0063] When the folding portion 21 is folded, the terrace portions 23 of the first case 20a and the second case 20b may abut against each other. Here, the insulating member 14 of the electrode assembly 10 may be located between the terrace portions 23 of the pair of cases 20a and 20b.

[0064] FIG. 2 is a plan view of a pouch-type secondary battery according to one embodiment of the present invention.

[0065] The terrace portion 23 may include a seal portion 24. The seal portion 24 may be a portion where the first case 20a and the second case 20b are sealed to each other by heat fusion or the like while they are in contact with each other. More specifically, the seal portion 24 may be formed by sealing a portion of the outer sides of the terrace portions 23 of the pair of cases 20a, 20b to each other. The width of the seal portion 24 may be formed to be approximately constant, but is not limited to this.

[0066] The seal portion 24 may include a first seal area 241 where the inner surfaces of the terrace portions 23 and the insulating member 14 are sealed together, and a second seal area 242 where the inner surfaces of the terrace portions 23 are sealed together.

[0067] The second sealing areas 242 may be located on both sides of the first sealing area 241. Both second sealing areas 242 may extend so as to be inclined or curved relative to the extension direction of the first sealing area 241. Both second sealing areas 242 may extend in different directions. The extension direction of each second sealing area 242 may not be constant, but may change midway. However, this is not limited thereto, and the second sealing area 242 and the first sealing area 241 may also extend parallel to each other.

[0068] The first sealing area 241 may be formed by fusing a polymer layer (e.g., polypropylene) that forms the innermost layer of each of the first case 20a and the second case 20b to the insulating member 14. The second sealing area 242 may be formed by fusing the polymer layers (e.g., polypropylene) that form the innermost layers of each of the first case 20a and the second case 20b to each other.

[0069] The terrace portion 23 may include a gas pocket portion 25 located between the seal portion 24 and the storage portion 22. The gas pocket portion 25 may be a portion that is not sealed when the first case 20a and the second case 20b are in contact with each other. More specifically, the gas pocket portion 25 is located on a portion of the inside of the terrace portions 23 of the pair of cases 20a, 20b, and can define a pocket space that communicates with the storage space of the storage portion 22. The shape of the gas pocket portion 25 is not limited.

[0070] A portion of the gas generated due to abnormal operation of the electrode assembly 10 can flow from the storage portion 22 into the gas pocket portion 25. Therefore, an increase in the internal pressure of the battery case 20 due to the gas can be sufficiently prevented or delayed.

[0071] Meanwhile, the sealing portion 24 according to one embodiment of the present invention may include a pattern for improving the sealing strength. More specifically, the sealing portion 24 may include a thin-part 243 extending along the edge of the sealing portion 24 and a thick-part 244 extending parallel to the thin-part 243 and thicker than the thin-part 243 (see FIG. 6).

[0072] The thin portion 243 may be formed by being pressed by a protruding portion 121 of the sealing tool 100, which will be described later. The thick portion 244 may be formed by being pressed by a recessed portion 122 of the sealing tool 100, which will be described later. That is, the thin portion 243 may be formed by being pressed relatively more strongly than the thick portion 244. Therefore, the sealing strength of the thin portion 243 may be higher than the sealing strength of the thick portion 244.

[0073] When the internal pressure of the battery case 20 becomes very high, the seal portion 24 may break discontinuously due to the difference in seal strength between the thin portion 243 and the thick portion 244. In other words, the number of breakage or peeling paths in the polymer layer that forms the innermost layer of the seal portion 24 can be increased. Therefore, compared to when the seal portion 24 breaks continuously, the overall seal strength of the seal portion 24 is improved, and gas venting can be delayed.

[0074] The thin portions 243 and thick portions 244 may be formed alternately in the width direction of the sealed portion 24. More specifically, the shortest path along which gas in the battery case 20 breaks the sealed portion 24 and is vented may be parallel to the width direction of the sealed portion 24. Multiple thin portions may be positioned at predetermined intervals along such a path. This increases the sealing strength of the sealed portion 24, effectively delaying breakage.

[0075] The thin portion 243 and the thick portion 244 may be included in the second sealing region 242 of the sealing portion 24. The thin portion 243 and the thick portion 244 may not be included in the first sealing region 241 of the sealing portion 24. In other words, the first sealing region 241 may be formed flat.

[0076] According to conventional wisdom and data, when the internal pressure of the battery case 20 increases due to gas generated by abnormal operation of the electrode assembly 10, rupture is more likely to occur in the second sealing area 242 than in the first sealing area 241. Therefore, forming a pattern in the second sealing area 242 increases the sealing strength and delays gas venting. Furthermore, by forming the first sealing area 241 flat without forming a pattern, it is possible to minimize the effects on gas release by the insulating member 14 and the insulating performance of the insulating member 14.

[0077] However, it goes without saying that the present invention is not limited to this, and the first sealing region 241 may include a thin portion 243 and a thick portion 244 .

[0078] The thin portion 243 and the thick portion 244 will be described in detail later.

[0079] FIG. 3 is a perspective view of a sealing device according to one embodiment of the present invention, FIGS. 4a and 4b are enlarged views of the second pressure region and its surroundings of the sealing device shown in FIG. 3, and FIG. 5 is a schematic diagram for explaining the operation of a sealing device according to one embodiment of the present invention.

[0080] The sealing device according to one embodiment of the present invention can seal the battery case 20 of the secondary battery 1, more specifically, the terrace portion 23.

[0081] The sealing device may include a pair of sealing tools 100 that face each other across the terrace portion 23 of the battery case 20 and are configured so that the distance between them is adjustable. A portion of the terrace portion 23 may be crimped and sealed between the pair of sealing tools 100 to form a seal portion 24. The adjustment of the distance between the pair of sealing tools 100 can be performed by a driving device including a linear actuator, a motor, etc., and this is a well-known technique, so a description thereof will be omitted.

[0082] Each sealing tool 100 may include a first pressure region 110 that seals the inner surfaces of the terrace portions 23 with the insulating member 14, and a second pressure region 120 that seals the inner surfaces of the terrace portions 23 with each other. That is, the first pressure region 110 can form a first seal region 241 in the terrace portions 23, and the second pressure region 120 can form a second seal region 242 in the terrace portions 23.

[0083] The second pressure regions 120 may be located on both sides of the first pressure region 110. The second pressure regions 120 may extend so as to be inclined or curved relative to the extension direction of the first pressure region 110. The second pressure regions 120 may extend in different directions. The extension direction of each second pressure region 120 may not be constant, but may change midway. However, this is not limited thereto, and the second pressure region 120 and the first pressure region 110 may also extend parallel to each other.

[0084] Of the two second pressure regions 120, one second pressure region 120A may be formed relatively long, and the other second pressure region 120B may be formed relatively short.

[0085] Meanwhile, the sealing tool 100 according to an embodiment of the present invention may include a pattern structure for improving the sealing strength of the sealing portion 24. More specifically, the sealing tool 100 may include a protruding portion 121 protruding toward the terrace portion 23 and a recessed portion 122 formed to have a step relative to the protruding portion 121.

[0086] The protrusions 121 and the depressions 122 may extend in parallel to each other. The protrusions 121 and the depressions 122 may be alternately formed in the width direction of the sealing tool 100. This increases the sealing strength of the seal portion 24 formed in the terrace portion 23, and effectively delays rupture.

[0087] The protrusion 121 and the depression 122 may be included in the second pressure region 120 of the sealing tool 100. The protrusion 121 and the depression 122 may not be included in the first pressure region 110 of the sealing tool 100. That is, the first pressure region 110 may be formed flat.

[0088] However, it is not limited to this, and it goes without saying that the first pressure region 110 may include the protrusion 121 and the depression 122.

[0089] The protrusions 121 and depressions 122 will be described in detail later.

[0090] FIG. 6 is an enlarged cross-sectional view of the sealing tool shown in FIG. 5 and the seal formed by the sealing tool on the pouch-type battery case.

[0091] In the seal portion 24 of the battery case 20 , the portion pressed by the protrusion 121 can form a thin portion 243 , and the portion pressed by the depression 122 can form a thick portion 244 .

[0092] The protrusions 121 and the depressions 122 may be arranged alternately in the width direction of the sealing tool 100. A plurality of protrusions 121 may be provided, and a depression 122 may be provided together with at least one protrusion 121. That is, each depression 122 may be located between a plurality of protrusions 121.

[0093] Therefore, the thin portions 243 and the thick portions 244 may be formed alternately in the width direction of the seal portion 24. A plurality of thin portions 243 may be formed, and at least one thick portion 244 may be formed. That is, each thick portion 244 may be located between a plurality of thin portions 243.

[0094] A protrusion 121 may be located on the innermost side of the sealing tool 100. The inner side of the sealing tool 100 may refer to the side closer to the housing portion 22 (see FIG. 5) of the battery case 20 in the width direction of the sealing tool 100. This prevents the polymer layer (e.g., polypropylene) that forms the innermost layer of the battery case 20 from melting and entering the gas pocket portion 25 side during the process of forming the seal portion 24.

[0095] As a result, the thin portion 243 may be located on the innermost side of the sealed portion 24. The inner side of the sealed portion 24 may refer to the side closer to the storage portion 22 (see FIG. 5) in the width direction of the sealed portion 24. This allows the innermost side of the sealed portion 24 to be tightly sealed, and the occurrence of the first rupture can be delayed as much as possible.

[0096] The plurality of protrusions 121 of the sealing tool 100 may include a first protrusion 121a and a second protrusion 121b located outside the first protrusion 121a. The first protrusion 121a may be located at the innermost side of the sealing tool 100 and may be referred to as the innermost protrusion.

[0097] The plurality of protrusions 121 may further include a third protrusion 121c located outward from the second protrusion 121b. If necessary, the plurality of protrusions 121 may further include a fourth protrusion, a fifth protrusion, and so on.

[0098] The multiple protrusions 121 may have a wider width as they are positioned more inward in the width direction of the sealing tool 100. More specifically, the width W11 of the first protrusion 121a may be wider than the width W12 of the second protrusion 121b. The width W12 of the second protrusion 121b may be wider than the width W13 of the third protrusion 121c. For example, the width W11 of the first protrusion 121a may be 30% of the width of the sealing tool 100, the width W12 of the second protrusion 121b may be 20% of the width of the sealing tool 100, and the width W13 of the third protrusion 121c may be 10% of the width of the sealing tool 100. Here, the width of the sealing tool 100 may refer to the width of the portion overlapping with the sealing portion 24 (e.g., W11 + W2 + W12 + W2 + W13).

[0099] The plurality of recesses 122 may have a constant width W2, which may be narrower than the width W11 of the first protrusion 121a.

[0100] The plurality of thin portions 243 of the seal portion 24 may include a first thin portion 243a and a second thin portion 243b located outside the first thin portion 243a. The first thin portion 243a may be located on the innermost side of the seal portion 24, and may be referred to as the innermost thin portion.

[0101] The plurality of thin portions 243 may further include a third thin portion 243c located outside the second thin portion 243b. If necessary, the plurality of thin portions 243 may further include a fourth thin portion, a fifth thin portion, and so on.

[0102] The plurality of thin portions 243 may have a width that is wider as they are positioned more inward in the width direction of the sealed portion 24. More specifically, the width W11 of the first thin portion 243a may be wider than the width W12 of the second thin portion 243b. The width W12 of the second thin portion 243b may be wider than the width W13 of the third thin portion 243c. For example, the width W11 of the first thin portion 243a may be 30% of the width of the sealed portion 24, the width W12 of the second thin portion 243b may be 20% of the width of the sealed portion 24, and the width W13 of the third thin portion 243c may be 10% of the width of the sealed portion 24. Here, the width of the sealed portion 24 may refer to the width of the portion that is pressed by the sealing tool 100 (e.g., W11 + W2 + W12 + W2 + W13).

[0103] The plurality of recesses 122 may have a constant width W2, which may be narrower than the width W11 of the first protrusion 121a.

[0104] Therefore, in the seal portion 24, which has a limited width, the width of the thin portions 243 located on the inner side can be increased, thereby effectively delaying the rupture of the seal portion 24. This is because the more the thin portions 243 are located on the inner side, the stronger the rupture delay effect due to their width.

[0105] On the other hand, when the pair of sealing tools 100 pressurize the terrace portion 23, the distance t1 between the protrusions 121 of the pair of sealing tools 100 may be adjusted to be 68% to 82% of the initial thickness t0 of the terrace portion 23. The initial thickness t0 of the terrace portion 23 may be based on a value measured when the terrace portion 23 of the first case 20a and the terrace portion 23 of the second case 20b are in close contact with each other. In other words, the initial thickness t0 of the terrace portion 23 may mean the sum of the thickness of the terrace portion 23 of the first case 20a and the thickness of the terrace portion 23 of the second case 20b.

[0106] As a result, the thickness t1 of the thin portion 243 of the seal portion 24 formed when the pair of sealing tools 100 presses the terrace portion 23 can be 68% to 82% of the thickness t0 of the gas pocket portion 25. Since the gas pocket portion 25 is an unsealed portion, it can have the same thickness as the initial thickness t0 of the terrace portion 23. The thickness t0 of the gas pocket portion 25 may be based on a value measured in a tightly packed state so that no space is created within the gas pocket portion 25.

[0107] Therefore, the thin portion 243 of the seal portion 24 can have sufficiently strong seal strength and can effectively delay gas venting. If the distance t1 between the protrusions 121 of the pair of seal tools 100 is shorter than 68% of the initial thickness t0 of the terrace portion 23, the seal portion 24 may be pushed too hard and break. On the other hand, if the distance t1 between the protrusions 121 of the pair of seal tools 100 is longer than 82% of the initial thickness t0 of the terrace portion 23, it may be difficult to achieve sufficient seal strength.

[0108] On the other hand, when the pair of sealing tools 100 pressurize the terrace portion 23, the distance t2 between the depressions 122 of the pair of sealing tools 100 may be adjusted to be 86% to 99% of the initial thickness t0 of the terrace portion 23.

[0109] As a result, the thickness t2 of the thick portion 244 of the seal portion 24 formed by pressing the terrace portion 23 with the pair of sealing tools 100 can be 86% to 99% of the thickness t0 of the gas pocket portion 25.

[0110] Therefore, the thick portion 244 of the seal portion 24 can also have a predetermined sealing strength, further delaying gas venting. If the distance t2 between the recessed portions 122 of the pair of sealing tools 100 is shorter than 86% of the initial thickness t0 of the terrace portion 23, the difference in level between the protrusion 121 and the recessed portion 122 will be very small, and the sealing strength of the thin portion 243 and the sealing strength of the thick portion 244 may become similar. In other words, the vent delay effect obtained by the difference in sealing strength between the thin portion 243 and the thick portion 244 may be difficult to achieve. On the other hand, if the distance t2 between the recessed portions 122 of the pair of sealing tools 100 is longer than 99% of the initial thickness t0 of the terrace portion 23, the thick portion 244 may not be properly sealed.

[0111] FIG. 7 is an enlarged cross-sectional view of a sealing tool according to another embodiment of the present invention and a seal formed by the sealing tool on a pouch-type battery case.

[0112] Hereinafter, the overlapping content with the above content will be omitted and the differences will be mainly explained.

[0113] The sealing tool 100 according to another embodiment of the present invention may include a dam structure to improve the sealing strength of the seal portion 24. More specifically, the single protrusion 121 may be located inside the recess 122. The single protrusion 121 may be located at the innermost position of the sealing tool 100.

[0114] The protrusion 121 may have a sufficient width. For example, the width W1′ of the protrusion 121 may be 40% of the width of the sealing tool 100. The width W2′ of the depression 122 may be greater than the width W1′ of the protrusion 121.

[0115] Thereby, the sealing portion 24 may include a dam structure for improving the seal strength. More specifically, the single thin portion 243 may be located inside the thick portion 244. The single thin portion 243 may be located at the innermost side of the sealing portion 24.

[0116] The thin portion 243 may have a sufficient width. For example, the width W1' of the thin portion 243 may be 40% of the width of the sealing portion 24. The width W2' of the thick portion 244 may be greater than the width W1' of the thin portion 243.

[0117] On the other hand, when the pair of sealing tools 100 pressurize the terrace portion 23, the distance t1 between the protrusions 121 of the pair of sealing tools 100 may be adjusted to be 68% to 82% of the initial thickness t0 of the terrace portion 23. As a result, the thickness t1 of the thin portion 243 of the seal portion 24 can be 68% to 82% of the thickness t0 of the gas pocket portion 25. This is within the same numerical range as in the above-described embodiment.

[0118] When the pair of sealing tools 100 pressurize the terrace portion 23, the distance t2' between the recesses 122 of the pair of sealing tools 100 may be adjusted to be 78% to 92% of the initial thickness t0 of the terrace portion 23. As a result, the thickness t2 of the thick portion 244 of the seal portion 24 can be 78% to 92% of the thickness t0 of the gas pocket portion 25.

[0119] This is a different range from the range of 86% to 99% in the embodiment described above, because the sealing tool 100 has only one protrusion 121, and to compensate for this, the recess 122 applies stronger pressure to the sealing portion 24.

[0120] 8a to 8c are graphs summarizing the results of an experiment conducted to confirm the effectiveness of the sealing device according to one embodiment of the present invention.

[0121] 8a is an experimental graph showing the tensile force required to peel a seal formed by a sealing tool according to an embodiment of the present invention versus displacement in the width direction, and FIG. 8b is an experimental graph showing the tensile force required to peel a seal formed by a conventional sealing tool (comparative example) having a flat pattern sealing area versus displacement in the width direction.

[0122] 8a, compared with FIG. 8b, it can be seen that peaks that hinder rupture occur repeatedly when the seal is peeled. That is, compared to when the seal is continuously peeled, it can be seen that the sealing tool 100 according to the present invention increases the peel path of the seal, and a high tensile force is required several times to completely peel the seal. That is, it can be seen that the total amount of tensile force required to completely peel or rupture the seal formed by the sealing tool 100 according to the present invention is greater than that required for a seal formed by a conventional sealing tool.

[0123] FIG. 8c is an experimental graph showing the pressure ranges at which the seal portion of FIG. 8a and the seal portion of FIG. 8b completely rupture.

[0124] 8c, it can be seen that the seal formed by the sealing tool according to the present invention can withstand higher pressure than the seal formed by a conventional sealing tool, and therefore it can be seen that venting caused by the rupture of the seal can be sufficiently delayed.

[0125] The above description merely exemplifies the technical concept of the present invention, and various modifications and variations may be made by a person having ordinary knowledge in the technical field to which the present invention pertains without departing from the essential characteristics of the present invention.

[0126] Therefore, the embodiments disclosed in the present invention are for illustrative purposes and not for limiting the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by such embodiments.

[0127] The scope of protection of the present invention should be interpreted by the appended claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention. [Explanation of symbols]

[0128] 1. Pouch-type secondary battery 10 Electrode assembly 11 Electrode tab 12 electrode leads 14 Insulating material 20 Pouch-type battery case 21 Folding section 22 Storage section 23 Terrace 24 Seal part 241 First seal area 242 Second seal area 243 Thin part 244 Atsushibe 25 Gas pocket 100 sealing tools 110 First pressure area 120 Second pressure area 121 Protrusion 122 Depression

Claims

1. A sealing device for sealing a pouch-type battery case including a housing portion in which an electrode assembly is housed and a terrace portion located on a periphery of the housing portion, a pair of sealing tools configured to face each other across the terrace portion and to be able to adjust the distance between them; Each sealing tool is a protruding portion protruding toward the terrace portion; a recessed portion formed to have a step with respect to the protruding portion, a sealing device, wherein when the pair of sealing tools press against the terrace portion, the distance between the protrusions of the pair of sealing tools is adjusted to be 68% to 82% of the initial thickness of the terrace portion.

2. The sealing device according to claim 1 , wherein the protrusion is located at the innermost portion of the sealing tool.

3. The sealing device according to claim 1 or 2, wherein the protrusions and the recesses are arranged alternately in the width direction of the sealing tool.

4. 4. The sealing device according to claim 3, wherein when the pair of sealing tools pressurize the terrace portion, the distance between the recessed portions of the pair of sealing tools is adjusted to be 86% to 99% of the initial thickness of the terrace portion.

5. The plurality of protrusions are A first protrusion; a second protrusion located outside the first protrusion and having a width narrower than that of the first protrusion; The sealing device of claim 3 , comprising:

6. The sealing device according to claim 3 , wherein the width of the recessed portion is narrower than the width of the innermost protrusion.

7. The sealing device according to claim 3 , wherein the plurality of protrusions have widths that are wider as they are positioned more inward in the width direction of the sealing tool.

8. The sealing device according to claim 1 , wherein the single protrusion is located inwardly of the recess.

9. 9. The sealing device according to claim 8, wherein when the pair of sealing tools pressurize the terrace portion, a distance between the recessed portions of the pair of sealing tools is adjusted to be 78% to 92% of an initial thickness of the terrace portion.

10. Each sealing tool is a first pressure region that seals an inner surface of the terrace portion and an insulating member that surrounds an electrode lead connected to the electrode assembly; a second pressure region that seals the inner surfaces of the terrace portions, The sealing device according to claim 1 , wherein the protrusion and the depression are included in the second pressure region.

11. an electrode assembly; a pouch-type battery case having a housing portion that houses the electrode assembly and a terrace portion located on a periphery of the housing portion, The terrace portion is A seal portion; a gas pocket portion located between the seal portion and the storage portion, The sealing portion is a thin part extending along the edge of the seal; a thick part extending parallel to the thin part and thicker than the thin part; A pouch-type secondary battery, wherein the thickness of the thin portion is 68% to 82% of the thickness of the gas pocket portion.

12. The pouch-type secondary battery according to claim 11 , wherein the thin portion is located on the innermost side of the sealed portion.

13. The pouch-type secondary battery according to claim 11 or 12, wherein the thin portions and the thick portions are alternately formed in the width direction of the seal portion.

14. 14. The pouch-type secondary battery according to claim 13, wherein the thickness of the thick portion is 86% to 99% of the thickness of the gas pocket portion.

15. The plurality of thin portions are A first thin portion; a second thin portion located outside the first thin portion and having a width narrower than that of the first thin portion; The pouch-type secondary battery according to claim 13 , comprising:

16. The pouch-type secondary battery according to claim 13 , wherein the width of the thick portion is narrower than the width of the innermost thin portion.

17. The pouch-type secondary battery according to claim 13 , wherein the plurality of thin portions have a width that increases as they are positioned more inward in the width direction of the seal portion.

18. The pouch-type secondary battery according to claim 11 , wherein the single thin portion is located more inward than the thick portion in the width direction of the sealed portion.

19. 19. The pouch-type secondary battery according to claim 18, wherein the thickness of the thick portion is 78% to 92% of the thickness of the gas pocket portion.

20. an electrode lead connected to the electrode assembly and protruding outside the terrace portion; an insulating member that insulates the electrode lead from the battery case, The sealing portion is a first sealing region in which the inner surface of the terrace portion and the insulating member are sealed; a second sealing region in which the inner surfaces of the terrace portions are sealed to each other, The pouch-type secondary battery according to claim 11 , wherein the thin portion and the thick portion are included in the second seal area.

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