Sealing device and pouch-type secondary battery sealed by same

Abstract

A sealing apparatus according to an embodiment of the present invention may seal a pouch-type battery case including a housing portion housing an electrode assembly and a halfpace portion on a periphery of the housing portion. The sealing apparatus may include a pair of sealing tools configured to face each other with the halfpace portion located therebetween, and the pair of sealing tools configured to adjust a distance therebetween. Each sealing tool may include: a protruding portion protruding toward the halfpace portion; and a recess that forms a stepped shape with the protrusion. When the pair of sealing tools presses the halfpace portion, a distance between the protrusions of the pair of sealing tools may be adjusted to 68% to 82% of an initial thickness of the halfpace portion.

Description

Technical Field

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10 - 2022 - 0182074, filed on December 22, 2022, and No. 10 - 2023 - 0188447, filed on December 21, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0004] The present invention relates to a sealing device for a terrace part of a sealed - bag - type battery case and a pouch - type secondary battery sealed thereby. Background Art

[0005] A lithium secondary battery is manufactured by applying an electrode - active - material slurry to a positive - electrode current collector and a negative - electrode current collector to form a positive electrode and a negative electrode, stacking the positive electrode and the negative electrode on both sides of a separator to form an electrode assembly, then accommodating the electrode assembly in a pouch, and injecting an electrolyte into a case.

[0006] Such secondary batteries are classified into pouch - type secondary batteries and can - type secondary batteries according to the material of the case accommodating the electrode assembly. Among them, a pouch - type secondary battery is generally manufactured by providing a receiving part in a flexible pouch film, accommodating the electrode assembly in the receiving part, injecting an electrolyte, and then sealing a terrace part around the receiving part.

[0007] In the prior art, when sealing a terrace part including an air - bag part of a pouch - type secondary battery, a plain shape has been applied to set a sealing part.

[0008] However, the sealing strength of the sealing part (especially, the part where the innermost layer of the battery case is sealed) is insufficient, and thus, there is a problem of early venting compared to the intention of the designer. More specifically, due to the gas generated during high - temperature storage and charge / discharge cycles of the secondary battery, the pressure applied to the terrace part increases. Here, once the innermost layer of the battery case starts to rupture in the sealing part, the sealing part with a plain shape does not block the ruptured part, and thus, the ruptured area rapidly increases over time, eventually leading to venting.

[0009] Therefore, it is necessary to increase the sealing strength of the part where the innermost layer of the battery case is sealed and delay abnormal venting. Summary of the Invention

[0010] Technical Problem

[0011] An object of the present invention to solve the above problems is to provide a sealing device provided with a sealing part having high sealing strength and a rupture - delay effect.

[0012] Another object of the present invention for solving the above problems is to provide a pouch secondary battery including a sealing portion having high sealing strength and a rupture delay effect.

[0013] Technical solution

[0014] A sealing device according to an embodiment of the present invention can seal a pouch battery case including a receiving portion for receiving an electrode assembly and a stepped portion provided around the receiving portion. The sealing device can include: a pair of sealing tools configured to face each other with the stepped portion therebetween, and the pair of sealing tools being configured to adjust the mutual distance. Each of the sealing tools can include: a protrusion protruding toward the stepped portion; and a recess defined to be stepped with respect to the protrusion. When the pair of sealing tools press the stepped portion, the distance between the protrusions of the pair of sealing tools is adjusted to 68% to 82% of the initial thickness of the stepped portion.

[0015] The protrusion can be provided at the innermost side of the sealing tool.

[0016] The protrusion and the recess can be alternately provided in the width direction of the sealing tool.

[0017] When the pair of sealing tools press the stepped portion, the distance between the recesses of the pair of sealing tools can be adjusted to 86% to 99% of the initial thickness of the stepped portion.

[0018] The plurality of protrusions can include: a first protrusion; and a second protrusion provided outside the first protrusion and having a width smaller than that of the first protrusion.

[0019] The width of the recess can be smaller than the width of the innermost protrusion.

[0020] The protrusion can be plural, and has a larger width as it is provided inside in the width direction of the sealing tool.

[0021] The protrusion can be single and provided inside the recess.

[0022] When the pair of sealing tools press the stepped portion, the distance between the recesses of the pair of sealing tools can be adjusted to 78% to 92% of the initial thickness of the stepped portion.

[0023] Each sealing tool may include: a first pressing area where the inner surface of the stepped portion and the insulating member surrounding the electrode lead connected to the electrode assembly are sealed to each other; a second pressing area where the inner surfaces of the stepped portion are sealed to each other. The protrusion and the recess may be included in the second pressing area.

[0024] A pouch-type secondary battery according to an embodiment of the present invention may include: an electrode assembly; and a pouch-type battery case including a receiving portion configured to receive the electrode assembly and a stepped portion provided around the receiving portion. The stepped portion may include: a sealing portion; and an air bag portion provided between the sealing portion and the receiving portion. The sealing portion may include: a thin portion extending along an edge of the sealing 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 air bag portion.

[0025] The thin portion may be provided at the innermost side of the sealing portion.

[0026] The thin portion and the thick portion may be alternately provided in a width direction of the sealing portion.

[0027] The thickness of the thick portion may be 86% to 99% of the thickness of the air bag portion.

[0028] The plurality of thin portions may include: a first thin portion; and a second thin portion provided outside the first thin portion and having a width smaller than the width of the first thin portion.

[0029] The width of the thick portion may be smaller than the width of the innermost thin portion.

[0030] The thin portion may be plural, and have a greater width as the thin portion is provided inside in a width direction of the sealing tool.

[0031] The thin portion may be single and provided inside the thick portion in a width direction of the sealing portion.

[0032] The thickness of the thick portion may be 78% to 92% of the thickness of the air bag portion.

[0033] The pouch-type secondary battery may further include: an electrode lead connected to the electrode assembly to protrude outside the stepped portion; and an insulating member configured to insulate the electrode lead and the battery case from each other. The sealing portion may include: a first sealing area where the inner surface of the stepped portion and the insulating member are sealed to each other; and a second sealing area where the inner surfaces of the stepped portion are sealed to each other. The thin portion and the thick portion may be included in the second sealing area.

[0034] Advantageous Effects

[0035] According to a preferred embodiment of the present invention, the sealing strength of the sealing portion provided in the pouch-type battery case may be increased to prevent or delay the occurrence of abnormal exhaust.

[0036] In addition, effects obvious to those skilled in the art may be predicted according to the configuration of the embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The following drawings attached to this specification illustrate preferred embodiments of the present invention and are used to further understand the technical spirit of the present invention and the detailed description of the present invention. Therefore, the present invention should not be construed as being limited to the drawings.

[0038] Figure 1 is an assembled view of a pouch-type secondary battery according to an embodiment of the present invention.

[0039] Figure 2 is a plan view of a pouch-type secondary battery according to an embodiment of the present invention; and

[0040] Figure 3 is a perspective view of a sealing device according to an embodiment of the present invention.

[0041] Figure 4a and Figure 4b is Figure 3 an enlarged view of the second pressing area of the shown sealing device and its surroundings.

[0042] Figure 5 is a schematic diagram for explaining the operation of the sealing device according to an embodiment of the present invention.

[0043] Figure 6 is Figure 5 an enlarged cross-sectional view of the shown sealing tool and the sealing portion provided in the pouch-type battery case by the sealing tool.

[0044] Figure 7 is an enlarged cross-sectional view of the sealing tool and the sealing portion provided in the pouch-type battery case by the sealing tool according to another embodiment of the present invention.

[0045] Figures 8a to 8c It is a chart obtained by summarizing the experimental results to confirm the effect of the sealing device according to an embodiment of the present invention. Detailed Embodiment

[0046] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily implement the present invention. However, the present invention can be implemented in several different forms and is not limited or restricted by the following examples.

[0047] To clearly explain the present invention, parts irrelevant to the description or detailed descriptions of related known technologies that may unnecessarily obscure the gist of the present invention are omitted, and in this specification, reference numerals are added to the components in each drawing. In this case, throughout the specification, the same or similar reference numerals are assigned to the same or similar elements.

[0048] In addition, the terms or words used in this specification and claims should not be construed restrictively as ordinary meanings or dictionary-based meanings, but should be construed as meanings and concepts that conform to the scope of the present invention based on the concept that the inventor can appropriately define the terms to best describe and explain the principle of his or her invention.

[0049] Figure 1 It is an assembly diagram of a pouch-type secondary battery according to an embodiment of the present invention.

[0050] The pouch-type secondary battery 1 (hereinafter referred to as "secondary battery") according to an embodiment of the present invention may be a secondary battery sealed by the sealing device according to the present invention. The secondary battery 1 described in this specification may be in a state at a specific point during the manufacturing process or may be in a final completed state, and may be appropriately interpreted according to the context or need.

[0051] The secondary battery 1 may include an electrode assembly 10 and a pouch-type battery case 20 (hereinafter referred to as "battery case").

[0052] The electrode assembly 10 may be provided by alternately stacking a positive electrode and a negative electrode and placing a separator between the positive electrode and the negative electrode. That is, the electrode assembly 10 may include a plurality of electrodes and a separator disposed between the plurality of electrodes to insulate the plurality of electrodes from each other. The electrode assembly 10 may be accommodated in the battery case 20 together with an electrolyte (and more specifically, in the accommodation part 22 to be described below).

[0053] The electrode assembly 10 may be provided in various types such as a stacked type, a jelly-roll type, a stacked and folded type, and the type of the electrode assembly 10 is not limited thereto.

[0054] The electrode assembly 10 may include electrode connectors 11. The electrode connectors 11 may be connected to each of the positive and negative electrodes of the electrode assembly 10 to protrude outward from the electrode assembly 10, thereby serving as a path for electrons to move between the inside and the outside of the electrode assembly 10.

[0055] The electrode connectors 11 may be provided by cutting an uncoated portion or by connecting a separate conductive member to the uncoated portion via ultrasonic welding.

[0056] The electrode connectors 11 may include a positive electrode connector 11a connected to the positive electrode and a negative electrode connector 11b connected to the negative electrode. Although the positive electrode connector 11a and the negative electrode connector 11b protrude in different directions along the electrode assembly 10, embodiments of the present invention are not limited thereto. For example, the electrode connectors 11a and 11b may protrude in various directions, for example, protruding parallel to each other in the same direction from one side.

[0057] An electrode lead 12 for supplying power to the outside of the battery cell may be connected to the electrode connector 11 of the electrode assembly 10. In addition, a part of the electrode lead 12 may be surrounded by an insulating member 14. The sealing member 14 may be sealed together with the first sealing portion 20a and the second sealing portion 114b. Therefore, the insulating member 14 may insulate the electrode lead 12 from the battery case 20 to maintain the seal of the battery case 20. Generally, although an insulating tape that is easily attached to the electrode lead 12 and has a relatively thin thickness is mainly used as the insulating member 14, the present invention is not limited thereto. For example, various members may be used as the insulating member 14 as long as the member can insulate the electrode lead 12.

[0058] The electrode lead 12 may have one end connected to the electrode connector 11 and the other end protruding to the outside of the battery case 20. The electrode lead 12 may include a positive electrode lead 12a connected to the positive electrode connector 11a and a negative electrode lead 12b connected to the negative electrode connector 11b.

[0059] The electrode lead 12 may electrically connect the electrode assembly 10 to the outside. In addition, since each of the positive electrode connector 11a and the negative electrode connector 112 protrudes in various directions, each of the positive electrode lead 12a and the negative electrode lead 12b may extend in various directions.

[0060] The battery case 20 may accommodate the electrode assembly 10 therein and may be formed by molding a laminate. More specifically, when a flexible laminate is stretched and molded using a mold and a punch, a part of the battery case 20 may be stretched to provide an accommodating portion 22 having a bag-shaped accommodating space, thereby manufacturing the battery case 20.

[0061] However, the configuration of the accommodation part 22 is not limited thereto, and it may be provided in a manner different from that shown in the drawings. For example, the laminate may be folded in a preset shape to provide the accommodation part 22.

[0062] Hereinafter, the battery case 20 may be in a state at a specific time point during the manufacturing process or may be in a final completed state. That is, the description of the battery case 20 may include both the sealed state as shown in Figure 2 and the unfolded state as shown in Figure 1 and may be appropriately interpreted according to the context or need.

[0063] The battery case 20 may accommodate the electrode assembly 10 such that a part of the electrode lead 12 is exposed and then may be sealed.

[0064] The battery case 20 may include a first case 20a and a second case 20b that are sealed to each other, and the electrode assembly 10 is disposed between the first case 20a and the second case 20b.

[0065] Preferably, the accommodation part 22 may be provided in at least one of the first case 20a and the second case 20b. In addition, the peripheral area of the accommodation part 22 may define a stepped part 23. That is, the battery case 20 may include the accommodation part 22 and the stepped part 23 provided outside the accommodation part 22.

[0066] The first case 20a and the second case 20b may be connected to each other through a folding part 21. However, it is not limited thereto, and the first case 20a and the second case 20b may also be separated from each other and manufactured separately.

[0067] The accommodation part 22 may define an accommodation space capable of accommodating the electrode assembly 10. The accommodation part 22 may have a pocket shape.

[0068] Hereinafter, the case where the accommodation part 22 is provided in each of the first case 20a and the second case 20b is described as an example. Those skilled in the art will also be able to easily understand the case where the accommodation part 22 is provided only in one of the paired cases 20a and 20b.

[0069] The accommodation parts 22 of the paired cases 20a and 20b may be provided to face each other in order to accommodate the electrode assembly 10. That is, the accommodation parts 22 of the paired cases 20a and 20b may be provided to face each other to define an accommodation space for accommodating the electrode assembly 10. In this case, when compared with the case where the accommodation part 22 is provided only in one of the paired cases 20a and 20b, the electrode assembly 20 may accommodate the electrode assembly 10 having a large thickness and a large capacity.

[0070] The first housing 20a and the second housing 20b can be connected to each other through the folding part 21. In a state where the first housing 20a and the second housing 20b are unfolded, a part of the folding part 21 can be disposed between the accommodating part 22 of the first housing 20a and the accommodating part 22 of the second housing 20b, and another part of the folding part 21 can be disposed between the stepped part 23 of the first housing 20a and the stepped part 23 of the second housing 20b.

[0071] When the folding part 21 is folded, the first housing 20a and the second housing 20b can face each other. The folding part 21 can extend parallel to the entire length direction of the electrode assembly 10, but is not limited thereto.

[0072] Each of the housings 20a and 20b can include a stepped part 23 disposed around the accommodating part 22.

[0073] When the first housing 20a and the second housing 20b are provided as separate members not connected to each other through the folding part 21, the stepped part 23 can be disposed around four sides of the accommodating part 22.

[0074] When the first housing 20a and the second housing 20b are connected to each other through the folding part 21, the stepped part 23 can be disposed around three sides of the four sides of the accommodating part 22 except for the side of the folding part 21.

[0075] When the folding part 21 is folded, the stepped parts 23 of the first housing 20a and the second housing 20b can contact each other. Here, the insulating member 14 of the electrode assembly 10 can be disposed between the stepped parts 23 of the paired housings 20a and 20b.

[0076] Figure 2 is a plan view of a pouch-type secondary battery according to an embodiment of the present invention; and

[0077] Each stepped part 23 can include a sealing part 24. The sealing part 24 can be a part that is heat-fused and sealed to each other in a state where the first housing 20a and the second housing 20b are in contact with each other. More specifically, the sealing part 24 can be provided by sealing the components outside the stepped parts 23 of the paired housings 20a and 20b to each other. The width of the sealing part 24 can be approximately constant, but is not limited thereto.

[0078] The sealing part 24 can include a first sealing area 241 and a second sealing area 242. The inner surface of the stepped part 23 and the insulating member 14 are sealed on the first sealing area 241, and the inner surfaces of the stepped parts 23 are sealed to each other on the second sealing area 242.

[0079] The second sealing region 242 may be provided on both sides and have a first sealing region 241 therebetween. The two second sealing regions 242 may extend to be inclined or rounded with respect to the extending direction of the first sealing region 241. The two second sealing regions 242 may extend in different directions. The extending direction of each second sealing region 242 may not be constant and may change during the extension. However, without being limited thereto, the second sealing region 242 and the first sealing region 241 may extend parallel to each other.

[0080] The first sealing region 242 may be provided by fusing a polymer layer (e.g., polypropylene) that defines the innermost layer of each of the first housing 20a and the second housing 20b to the insulating member 14. The second sealing region 242 may be provided by fusing the polymer layer (e.g., polypropylene) that defines the innermost layer of each of the first housing 20a and the second housing 20b.

[0081] The stepped portion 23 may include an airbag portion 25 provided between the sealing portion 24 and the accommodating portion 22. The airbag portion 25 may be a portion that is not sealed in a state where the first housing 20a and the second housing 20b are in contact with each other. More specifically, the airbag portion 25 may be provided on a portion inside the stepped portion 23 of each of the paired housings 20a and 20b, and define a bag space communicating with the accommodating space of the accommodating portion 22. The shape of the airbag portion 25 is not limited.

[0082] A part of the gas generated due to the abnormal operation of the electrode assembly 10 may be introduced from the accommodating portion 22 into the airbag portion 25. Accordingly, an increase in the internal pressure of the battery housing 20 due to the gas can be sufficiently prevented or delayed.

[0083] The sealing portion 24 according to an embodiment of the present invention may include a pattern for improving the sealing strength. More specifically, the sealing portion 24 may include a thin portion 243 extending along the edge of the sealing portion 24 and a thick portion 244 extending parallel to the thin portion 243 and thicker than the thin portion 243 (see Figure 6 ).

[0084] The thin portion 243 may be provided by being pressed by a protrusion 121 of a sealing tool 100 to be described later. The thick portion 244 may be provided by being pressed by a recess 122 of the sealing tool 100 to be described later. That is, the thin portion 243 may be a portion provided by being pressed relatively stronger than the thick portion 244. Accordingly, the sealing strength of the thin portion 243 may be greater than the sealing strength of the thick portion 244.

[0085] When the internal pressure of the battery case 20 becomes very high, due to the difference in the sealing strength between the thin portion 243 and the thick portion 244, the sealing portion 24 may rupture discontinuously. That is, the rupture path or peeling path of the polymer layer that defines the innermost layer of the sealing portion 24 may increase. As a result, when compared with the case where the sealing portion 24 ruptures continuously, the overall sealing strength of the sealing portion 24 can be improved, and the discharge of gas is delayed.

[0086] The thin portion 243 and the thick portion 244 may be alternately provided in the width direction of the sealing portion 24. More specifically, the shortest path for the gas in the battery case 20 to rupture the sealing portion 23 and exhaust gas may be parallel to the width direction of the sealing portion 23. A plurality of thin portions may be provided in the path at a predetermined interval. As a result, the sealing strength of the sealing portion 24 can be increased, and rupture can be effectively delayed.

[0087] The thin portion 243 and the thick portion 244 may be included in the second sealing area 242 of the sealing portion 24. The thin portion 243 and the thick portion 244 may not be included in the first sealing area 241 of the sealing portion 24. That is, the first sealing area 241 may be set to be flat.

[0088] According to common sense or data, when the internal pressure of the battery case 20 increases due to the gas generated by the 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, a pattern may be provided on the second sealing area 242 to increase the sealing strength and delay the exhaust. In addition, the first sealing area 241 may be set to be flat without forming a pattern, and thus, the gas release through the insulating member 14 or the influence on the insulating performance of the insulating member 14 can be minimized.

[0089] However, it is not limited thereto, and the first sealing area 241 may include the thin portion 243 and the thick portion 244.

[0090] The thin portion 243 and the thick portion 244 will be described in more detail later.

[0091] Figure 3 is a perspective view of a sealing device according to an embodiment of the present invention, Figure 4a and Figure 4b is Figure 3 an enlarged view of the second pressing area of the shown sealing device and its surroundings, and Figure 5 is a schematic diagram for explaining the operation of the sealing device according to an embodiment of the present invention.

[0092] The sealing device according to an embodiment of the present invention can seal the battery case 20, and more specifically, seal the stepped portion 23 of the secondary battery 1.

[0093] The sealing device may include a pair of sealing tools 100 that face each other with the stepped portion 23 of the battery case 20 therebetween, and the pair of sealing tools 100 are configured to adjust the mutual distance. A portion of the stepped portion 23 may be pressed and sealed between the pair of sealing tools 100, and a sealing portion 24 may be provided. The adjustment of the distance between the pair of sealing tools 100 may be performed by a driving device including a linear actuator or a motor, and since this is a well-known technique, its description will be omitted.

[0094] Each sealing tool 100 may include a first pressing area 110 that seals the inner surface of the stepped portion 23 to the insulating member 14 and a second pressing area 120 that seals the inner surfaces of the stepped portion 23 to each other. That is, the first pressing area 110 may define a first sealing area 241 on the stepped portion 23, and the second pressing area 120 may define a second sealing area 242 on the stepped portion 23.

[0095] The second pressing area 120 may be provided on both sides and the first pressing area 110 is located therebetween. The two second pressing areas 120 may extend inclined or rounded with respect to the extending direction of the first pressing area 110. The two second pressing areas 120 may extend in different directions. The extending direction of each second pressing area 120 may not be constant but may change during the extension. However, it is not limited thereto, and the second pressing area 120 and the first pressing area 110 may extend parallel to each other.

[0096] One 120A of the second pressing areas 120 may be provided relatively long, and the other 120B may be provided relatively short.

[0097] The sealing tool 100 according to an embodiment of the present invention may include a pattern structure to improve the sealing strength of the sealing portion 24. More specifically, the sealing tool 100 may include a protrusion 121 protruding toward the stepped portion 23 and a recess 122 provided in a step with respect to the protrusion 121.

[0098] The protrusion 121 and the recess 122 may extend parallel to each other. The protrusion 121 and the recess 122 may be alternately provided in the width direction of the sealing tool 100. As a result, the sealing strength of the sealing portion 24 provided on the stepped portion 23 may be increased, and the breakage may be effectively delayed.

[0099] The protrusion 121 and the recess 122 may be included in the second pressing area 120 of the sealing tool 100. The protrusion 121 and the recess 122 may not be included in the first pressing area 110 of the sealing tool 100. That is, the first pressing area 110 may be provided flat.

[0100] However, not limited thereto, and the first pressing area 110 may include a protrusion 121 and a recess 122.

[0101] The protrusion 121 and the recess 122 will be described in more detail later.

[0102] Figure 6 Yes Figure 5 An enlarged cross-sectional view of the shown sealing tool and the sealing portion provided in the bag-type battery case by the sealing tool.

[0103] In the sealing portion 24 of the battery case 20, the portion pressed by the protrusion 121 may be set as a thin portion 243, and the portion pressed by the recess 122 may be set as a thick portion 244.

[0104] The protrusion 121 and the recess 122 may be alternately arranged with respect to the width direction of the sealing tool 100. The protrusion 121 may be provided in a plurality, and the recess 122 may be provided with at least one protrusion 121. That is, each recess 122 may be provided between the protrusions 121.

[0105] Therefore, the thin portion 243 and the thick portion 244 may be alternately arranged with respect to the width direction of the sealing portion 24. The thin portion 243 may be provided in a plurality, and at least one thick portion 244 may be provided. That is, each thick portion 244 may be provided between the thin portions 243.

[0106] The protrusion 121 may be provided at the innermost side of the sealing tool 100. The inner side of the sealing tool 100 may refer to the side closer to the accommodating portion 22 of the battery case 20 (see Figure 5 ) in the width direction of the sealing tool 100. As a result, it is possible to prevent the following phenomenon from occurring: during the formation of the sealing portion 24, the polymer layer (for example, polypropylene) defining the innermost layer of the battery case 20 melts and is pushed toward the airbag portion 25.

[0107] Therefore, the thin portion 243 may be provided at the innermost side of the sealing portion 24. The inner side of the sealing portion 24 may refer to the side closer to the accommodating portion 22 (see Figure 5 ) in the width direction of the sealing portion 24. As a result, the innermost side of the sealing portion 24 can be strongly sealed, and the occurrence of the first rupture can be delayed as much as possible.

[0108] The plurality of protrusions 121 of the sealing tool 100 may include a first protrusion 121a and a second protrusion 121b provided outside the first protrusion 121a. The first protrusion 121a may be provided at the innermost side of the sealing tool 100 and may be referred to as the innermost protrusion.

[0109] The plurality of protrusions 121 may further include a third protrusion 121c disposed outside the second protrusion 121b. If necessary, the plurality of protrusions 121 may further include a fourth protrusion, a fifth protrusion, and the like.

[0110] The plurality of protrusions 121 may have a greater width as the protrusions are disposed inside the sealing tool 100 in the width direction. More specifically, the width W11 of the first protrusion 121a may be greater than the width W12 of the second protrusion 121b. The width W12 of the second protrusion 121b may be greater 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, and 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 represent the width of the portion overlapping with the sealing portion 24 (e.g., W11 + W2 + W12 + W2 + W13).

[0111] Each of the plurality of recesses 122 may have a constant width W2. The width W2 of each recess 122 may be less than the width W11 of the first protrusion 121a.

[0112] The plurality of thin portions 243 of the sealing portion 24 may include a first thin portion 243a and a second thin portion 243b disposed outside the first thin portion 243a. The first thin portion 243a may be disposed at the innermost side of the sealing portion 24 and may be referred to as the innermost thin portion.

[0113] The plurality of thin portions 243 may further include a third thin portion 243c disposed outside the second thin portion 243b. When necessary, the plurality of thin portions 243 may further include a fourth thin portion, a fifth thin portion, and the like.

[0114] The plurality of thin portions 243 may have a greater width as the thin portions are disposed inside the sealing portion 24 in the width direction. More specifically, the width W11 of the first thin portion 243a may be greater than the width W12 of the second thin portion 243b. The width W12 of the second thin portion 243b may be greater 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 sealing portion 24, and the width W12 of the second thin portion 243b may be 20% of the width of the sealing portion 24, and the width W13 of the third thin portion 243c may be 10% of the width of the sealing portion 24. Here, the width of the sealing portion 24 may represent the width of the portion pressed by the sealing tool 100 (e.g., W11 + W2 + W12 + W2 + W13).

[0115] Each of the plurality of recesses 122 may have a constant width W2. The width W2 of each recess 122 may be less than the width W11 of the first protrusion 121a.

[0116] As a result, the width of the thin portion 243 provided within the sealing portion 24 having a finite width can be increased to effectively delay the rupture of the sealing portion 24. This is because the more the plurality of thin portions 243 are provided on the inner side, the stronger the rupture delay effect due to their width.

[0117] When the pair of sealing tools 100 press the stepped portion 23, the distance t1 between the protrusions 121 of the pair of sealing tools 100 can be adjusted to 68% to 82% of the initial thickness t0 of the stepped portion 23. The initial thickness t0 of the stepped portion 23 can be based on the measurement in a state where the stepped portion 23 of the first housing 20a and the stepped portion 23 of the second housing 20b are in close contact with each other. That is, the initial thickness t0 of the stepped portion 23 can represent the sum of the thickness of the stepped portion 23 of the first housing 20a and the thickness of the stepped portion 23 of the second housing 20b.

[0118] Therefore, the thickness t1 of the thin portion 243 of the sealing portion 24 provided by pressing the stepped portion 23 by the pair of sealing tools 100 can be 68% to 82% of the thickness t0 of the airbag portion 25. Since the airbag portion 25 is an unsealed portion, the airbag portion 25 can have the same thickness as the initial thickness t0 of the stepped portion 23. The thickness t0 of the airbag portion 25 can be based on the measurement in a state where they are in close contact so that no space is generated within the airbag portion 25.

[0119] As a result, the thin portion 243 of the sealing portion 24 can have a sufficiently strong sealing strength and can effectively delay the discharge of gas. If the distance t1 between the protrusions 121 of the pair of sealing tools 100 is less than 68% of the initial thickness t0 of the stepped portion 23, the sealing portion 24 may be over-pressed and damaged. On the contrary, if the distance t1 between the protrusions 121 of the pair of sealing tools 100 is less than 82% of the initial thickness t0 of the stepped portion 23, it may be difficult to achieve sufficient sealing strength.

[0120] When the pair of sealing tools 100 press the stepped portion 23, the distance t1 between the recesses 122 of the pair of sealing tools 100 can be adjusted to 86% to 99% of the initial thickness t0 of the stepped portion 23.

[0121] Therefore, the thickness t1 of the thin portion 244 of the sealing portion 24 provided by pressing the stepped portion 23 by the pair of sealing tools 100 can be 86% to 99% of the thickness t0 of the airbag portion 25.

[0122] As a result, the rear portion 243 of the sealing portion 24 can also have a predetermined sealing strength and can further delay the discharge of gas. If the distance t2 between the recesses 122 of the pair of sealing tools 100 is less than 86% of the initial thickness t0 of the stepped portion 23, since the height difference between the protrusion 121 and the recess 122 is too small, the sealing strengths of the thin portion 243 and the thick portion 244 may be similar to each other. That is, it may be difficult to obtain the exhaust delay effect achievable due to the difference in the sealing strengths between the thin portion 243 and the thick portion 244. Conversely, if the distance t2 between the recesses 122 of the pair of sealing tools 100 is greater than 99% of the initial thickness t0 of the stepped portion 23, the sealing of the thick portion 244 may not be properly performed.

[0123] Figure 7 is an enlarged cross-sectional view of a sealing tool according to another embodiment of the present invention and a sealing portion provided in a pouch-type battery case by the sealing tool.

[0124] Hereinafter, the content repeated with the foregoing embodiment will be omitted, and the differences will be mainly described.

[0125] The sealing tool 100 according to another embodiment of the present invention may include a dam structure to improve the sealing strength of the sealing portion 24. More specifically, a single protrusion 121 may be provided within the recess 122. The single protrusion 121 may be provided at the innermost side of the sealing tool 100.

[0126] 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 recess 122 may be greater than the width W1' of the protrusion 121.

[0127] Accordingly, the sealing portion 24 may include a dam structure to improve the sealing strength. More specifically, a single thin portion 243 may be provided within the thick portion 244. The single thin portion 243 may be provided at the innermost side of the sealing portion 24.

[0128] 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.

[0129] When the pair of sealing tools 100 presses the stepped portion 23, the distance t1 between the protrusions 121 of the pair of sealing tools 100 may be adjusted to 68% to 82% of the initial thickness t0 of the stepped portion 23. Accordingly, the thickness t1 of the thin portion 243 of the sealing portion 24 may be 68% to 82% of the thickness t0 of the airbag portion 25. This is the same numerical range as the previously described embodiment.

[0130] When the pair of sealing tools 100 press the stepped portion 23, the distance t1 between the concave portions 122 of the pair of sealing tools 100 can be adjusted to 78% to 92% of the initial thickness t0 of the stepped portion 23. Accordingly, the thickness t2 of the thick portion 244 of the sealing portion 24 can be 78% to 92% of the thickness t0 of the airbag portion 25.

[0131] This is a numerical range different from the numerical range of 86% to 99% in the previously described embodiments. According to the present embodiment, since the sealing tool 100 has only one protrusion 121, in order to compensate for this, the concave portion 122 can press the sealing portion 24 more strongly.

[0132] Figures 8a to 8c is a graph obtained by summarizing experimental results to confirm the effect of the sealing device according to an embodiment of the present invention.

[0133] Figure 8a is an experimental graph illustrating the pulling force required to peel the sealing portion sealed by the sealing tool in the width direction according to an embodiment of the present invention. Figure 8b is an experimental graph illustrating the pulling force required to peel the sealing portion sealed by a general sealing tool (comparative example) having a smooth sealing area in the width direction.

[0134] When compared with Figure 8b it can be seen that when the sealing portion is peeled in Figure 8a peaks for preventing rupture repeatedly appear. That is, when compared with the case of continuously peeling the sealing portion, it is confirmed that the sealing tool 100 according to the present invention increases the peeling path of the sealing portion, and a high pulling force is required multiple times to completely peel the sealing portion. That is, it is confirmed that the total amount of pulling force required for the complete peeling or rupture of the sealing portion provided by the sealing tool 100 according to the present invention is greater than the total amount of pulling force required for the complete peeling or rupture of the sealing portion provided by the general sealing tool.

[0135] Figure 8c is an illustration of Figure 8a the sealing portion of Figure 8b and the experimental graph of the pressure range in which each of the sealing portions of

[0136] is completely disconnected. Figure 8c Referring to

[0137] it is confirmed that the sealing portion provided by the sealing tool according to the present invention has a higher pressure than the sealing portion formed by the general sealing tool. As a result, it is confirmed that the exhaust gas caused by the rupture of the sealing portion is sufficiently delayed.

[0138] Therefore, the embodiments of the present invention are considered to be illustrative rather than restrictive, and the technical spirit of the present invention is not limited to the foregoing embodiments.

[0139] Therefore, the scope of the present invention is defined not by the detailed description of the present invention but by the appended claims, and all differences within the scope will be construed as being included in the present invention.

[0140] [Description of Symbols]

[0141] 1: Pouch secondary battery 10: Electrode assembly

[0142] 11: Electrode terminal 12: Electrode lead

[0143] 14: Insulating member 20: Pouch battery case

[0144] 21: Folding portion 22: Accommodating portion

[0145] 23: Trapezoidal portion 24: Sealing portion

[0146] 241: First sealing area 242: Second sealing area

[0147] 243: Thin portion 244: Thick portion

[0148] 25: Air bag portion 100: Sealing tool

[0149] 110: First pressing area 120: Second pressing area

[0150] 121: Protrusion 122: Recess

Claims

1. A sealing device for sealing a pouch-type battery case, the pouch-type battery case including a receiving portion configured to receive an electrode assembly and a stepped portion disposed around the receiving portion, the sealing device comprising: A pair of sealing tools configured to face each other with the stepped portion therebetween, and the pair of sealing tools being configured to adjust the distance therebetween. Wherein each of the sealing tools includes: A protrusion protruding toward the stepped portion; and A recess defined to be stepped relative to the protrusion; Wherein when the pair of sealing tools press the stepped portion, the distance between the protrusions of the pair of sealing tools is adjusted to 68% to 82% of the initial thickness of the stepped portion.

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

3. The sealing device according to claim 1, wherein, The protrusion and the recess are alternately provided in the width direction of the sealing tool.

4. The sealing device according to claim 3, wherein, When the pair of sealing tools press the stepped portion, the distance between the recesses of the pair of sealing tools is adjusted to 86% to 99% of the initial thickness of the stepped portion.

5. The sealing device according to claim 3, wherein, The plurality of protrusions include: A first protrusion; and A second protrusion provided outside the first protrusion and having a width smaller than that of the first protrusion.

6. The sealing device according to claim 3, wherein The width of the recess is smaller than the width of the innermost protrusion.

7. The sealing device according to claim 3, wherein The protrusions are multiple, and have a larger width as they are disposed more inward in the width direction of the sealing tool.

8. The sealing device according to claim 1, wherein, The protrusion is single and is disposed within the recess.

9. The sealing device according to claim 8, wherein, When the pair of sealing tools press the stepped portion, the distance between the recesses of the pair of sealing tools is adjusted to 78% to 92% of the initial thickness of the stepped portion.

10. The sealing device according to claim 1, wherein, Each sealing tool includes: A first pressing area where the inner surface of the stepped portion and an insulating member around an electrode lead connected to the electrode assembly are sealed to each other; A second pressing area where the inner surfaces of the stepped portion are sealed to each other; Wherein the protrusion and the recess are included in the second pressing area.

11. A pouch-type secondary battery, the pouch-type secondary battery comprising: An electrode assembly; And A pouch-type battery case including a receiving portion configured to receive the electrode assembly and a stepped portion disposed around the receiving portion, Wherein the stepped portion includes: A sealing portion; and An airbag portion disposed between the sealing portion and the receiving portion, Wherein the sealing portion includes: A thin portion extending along the edge of the sealing portion; A thick portion extending parallel to the thin portion and being thicker than the thin portion; Wherein the thickness of the thin portion is 68% to 82% of the thickness of the airbag portion.

12. The pouch secondary battery according to claim 11, wherein, The thin portion is provided at the innermost side of the sealing portion.

13. The pouch secondary battery according to claim 11, wherein The thin portion and the thick portion are alternately provided in the width direction of the sealing portion.

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

15. The pouch secondary battery according to claim 13, wherein, The plurality of thin portions include: A first thin portion; and A second thin portion, the second thin portion being disposed outside the first thin portion and having a width smaller than that of the first thin portion.

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

17. The pouch secondary battery according to claim 13, wherein, There are a plurality of the thin portions, and the thin portions have a greater width as they are disposed closer to the inside in the width direction of the sealing portion.

18. The pouch secondary battery according to claim 11, wherein, There is a single thin portion, and the thin portion is disposed inside the thick portion in the width direction of the sealing portion.

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

20. The pouch-type secondary battery according to claim 11, wherein the pouch-type secondary battery further comprises: An electrode lead, the electrode lead being connected to the electrode assembly and protruding outside the stepped portion; And An insulating member, the insulating member being configured to insulate the electrode lead and the battery case from each other, wherein the sealing portion includes: A first sealing region, on which the inner surface of the stepped portion and the insulating member are sealed to each other; and A second sealing region, on which the inner surfaces of the stepped portion are sealed to each other, wherein the thin portion and the thick portion are included in the second sealing region.

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