Pouch-type secondary battery

Abstract

A pouch-type secondary battery according to an embodiment of the present invention may include an electrode assembly and a pouch-type battery case. The pouch type battery case may include: a cup portion for accommodating the electrode assembly; a pair of first sealing parts positioned on both sides in the full length direction of the cup part; and a second sealing part connecting the pair of first sealing parts and positioned on one side in the full width direction of the cup part. When the area of each first sealing portion is A mm2 and the weight of the electrode assembly is B g, A / B may be 0.29 or more.

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the priority of Korean Patent Application No. 10-2022-0121205 filed on September 23, 2022, in the Korean Intellectual Property Office and Korean Patent Application No. 10-2023-0127258 filed on September 22, 2023, in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference. Technical Field

[0004] The present invention relates to a pouch type secondary battery, and more particularly to a pouch type secondary battery having excellent impact resistance. Background Art

[0005] Lithium secondary batteries are generally manufactured by applying electrode active material slurry to positive and negative current collectors to manufacture positive and negative electrodes. The positive and negative electrodes are then stacked on both sides of the separator to form an electrode assembly. Next, the electrode assembly is housed in a housing, and an electrolyte is injected into the housing.

[0006] Conventionally, secondary batteries are classified according to the shape of the housing that houses the electrode assembly. Exemplary secondary batteries include pouch-type secondary batteries, can-type secondary batteries, and prismatic secondary batteries. For example, a pouch-type secondary battery is manufactured by pressing a flexible bag film to form a cup portion that houses the electrode assembly before sealing the bag and injecting the electrolyte. On the other hand, a can-type secondary battery is manufactured by accommodating the electrode assembly in a can made of a metal material, the can is provided with a top cover to seal the can, and the electrolyte material is injected into the sealed can.

[0007] Although pouch-type secondary batteries are lightweight, exhibit excellent space utilization, and have high energy density due to their stacked electrode assemblies, they are more susceptible to fire, explosion, and electrolyte leakage when subjected to external impact than can-type secondary batteries.

[0008] Secondary batteries are used in various products including electric vehicles to reduce and / or prevent greenhouse gas emissions. When secondary batteries are used in electric vehicles, such batteries need to have excellent safety to protect passengers. Therefore, it is desirable to improve the impact resistance of pouch-type secondary batteries. Summary of the invention

[0009] Technical issues

[0010] One aspect of the present invention provides a pouch type secondary battery in which separation of an electrode assembly and / or leakage of an electrolyte is suppressed when an external impact is applied.

[0011] Technical Solution

[0012] According to one aspect of the present invention, a pouch-type secondary battery is provided, comprising: an electrode assembly; and a pouch-type battery case. The pouch-type battery case may include: a cup portion configured to accommodate the electrode assembly; a pair of first sealing portions, the pair of first sealing portions being respectively arranged on both sides of the cup portion in the length direction; and a second sealing portion, the second sealing portion connecting the pair of first sealing portions to each other and being arranged on one side of the cup portion in the width direction. When the area of ​​the first sealing portion is A mm 2 , and when the weight of the electrode assembly is B g, the ratio A / B may be greater than about 0.29.

[0013] The ratio A / B may be approximately 0.37 or less.

[0014] The pouch type battery case may further include an air pocket portion disposed between the cup portion and one of the pair of first sealing portions. The air pocket portion may be configured to contain gas exhausted from the electrode assembly.

[0015] A minimum distance between the first sealing portion and the electrode assembly in a length direction of the cup portion may be in a range between about 0.5% and about 0.8% of a length of the electrode assembly.

[0016] The first sealing portion may include: a first segment, which is connected to the second sealing portion and whose distance from the cup portion in the length direction of the cup portion increases as it moves away from the second sealing portion; and a second segment, which is connected to the first segment and from which an electrode lead connected to the electrode assembly protrudes.

[0017] A minimum distance between the first section and the electrode assembly in a length direction of the cup portion may be in a range between about 0.5% and about 0.8% of a length of the electrode assembly.

[0018] The pouch-type battery case may further include a folding portion, the folding portion being disposed at an opposite side of the second sealing portion relative to the cup portion and connecting the pair of first sealing portions to each other. Each of the pair of first sealing portions may further include a third section, the third section connecting the second section to the folding portion and having a distance from the cup portion in the length direction of the cup portion that increases as it moves away from the folding portion.

[0019] In a length direction of the cup portion, a minimum distance between the first section and the electrode assembly may be smaller than a minimum distance between the third section and the electrode assembly.

[0020] The length of the first section may be greater than the length of the third section.

[0021] According to another aspect of the present invention, there is provided a pouch-type secondary battery, comprising: an electrode assembly; and a pouch-type battery case. The pouch-type battery case may include: a cup portion configured to accommodate the electrode assembly; a pair of first sealing portions, the pair of first sealing portions being respectively disposed on both sides of the cup portion in the length direction; and a second sealing portion, the second sealing portion connecting the pair of first sealing portions to each other and being disposed on at least one side in the width direction of the cup portion. The minimum distance between the first sealing portion and the electrode assembly in the length direction of the cup portion may be about 0.5% or more of the length of the electrode assembly.

[0022] A minimum distance between the first sealing portion and the electrode assembly in a length direction of the cup portion may be less than about 0.8% of a length of the electrode assembly.

[0023] When the area of ​​the first sealing portion is A mm 2 , and when the weight of the electrode assembly is B g, the ratio A / B may range from about 0.29 to about 0.37.

[0024] The pouch type battery case may further include an air pocket portion provided between the cup portion and at least one of the pair of first sealing portions.

[0025] According to another aspect of the present invention, there is provided a pouch-type secondary battery, comprising: an electrode assembly; and a pouch-type battery case. The pouch-type battery case may include: a cup portion configured to accommodate the electrode assembly; a pair of first sealing portions, the pair of first sealing portions being respectively arranged on both sides of the cup portion in the length direction; a second sealing portion, the second sealing portion connecting the pair of first sealing portions to each other and being arranged on at least one side of the cup portion in the width direction; and an air pocket portion, the air pocket portion being arranged between the cup portion and at least one of the pair of first sealing portions. The first sealing portion may include a first section, the first section defining an inclined bending length between the second sealing portion and the second section.

[0026] The pouch type battery case may further include a folded portion provided at an opposite side of the second sealing portion with respect to the cup portion, the folded portion connecting the pair of first sealing portions to each other.

[0027] The first sealing portion may further include a third section defining an inclined bending length between the folded portion and the second section.

[0028] When the area of ​​the first sealing portion is A mm 2And when the weight of the electrode assembly is B g, the ratio A / B may be between about 0.29 and about 0.37.

[0029] The pouch type battery case may further include a sub-sealing portion disposed on or adjacent to the folded portion and between the third section and the cup portion.

[0030] A minimum distance between the first section of the first sealing portion and the electrode assembly in a length direction of the cup portion may be between about 0.5% and about 0.8% of a length of the electrode assembly.

[0031] The minimum distance may be a distance between the cup portion and an end portion of the first section of the first sealing portion connected to the second sealing portion.

[0032] Beneficial Effects

[0033] According to a preferred embodiment of the present invention, the ratio of the area of ​​the first sealing portion of the battery case to the weight of the electrode assembly may satisfy a specific condition, or the ratio of the minimum distance between the first sealing portion and the electrode assembly to the total length of the electrode assembly may satisfy a specific condition, or both may satisfy a specific condition. Therefore, when an external impact is applied, the risk of damage or penetration of the first sealing portion due to the electrode assembly can be reduced, and the separation of the electrode assembly and / or the leakage of the electrolyte can be suppressed to achieve excellent impact resistance.

[0034] Furthermore, effects that are obvious to those skilled in the art can be predicted from the configuration according to the embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and other aspects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0036] Figure 1 is an exploded view of a pouch-type secondary battery according to an embodiment of the present invention;

[0037] Figure 2 yes Figure 1 A plan view of a pouch-type secondary battery; and

[0038] Figure 3 is based on Figure 2 A partially enlarged plan view of a pouch-type secondary battery. DETAILED DESCRIPTION

[0039] Hereinafter, various aspects of the present invention will be described in detail with reference to the accompanying drawings so that those skilled 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 constrained by the following embodiments.

[0040] Figure 1 is an exploded view of a pouch-type secondary battery 1 according to an embodiment of the present invention.

[0041] The pouch-type secondary battery 1 may include an electrode assembly 10 and a pouch-type battery case 20 (hereinafter, referred to as a “battery case”).

[0042] like Figure 1 As shown in , the electrode assembly 10 can be provided by alternately stacking the positive electrode and the negative electrode with a separator sandwiched therebetween. 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. Alternatively, the electrode assembly 10 may be a roll core type, a stacked and folded type, etc. The electrode assembly 10 may then be housed in the cup portion 22 of the battery case 20 together with the electrolyte.

[0043] The electrode assembly 10 may include a plurality of electrode taps 11. Each electrode tap 11 may be connected to a positive electrode and a negative electrode and 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.

[0044] The electrode tab 11 may be formed by cutting the non-coating portion or by connecting a separate conductive member to the non-coating portion by ultrasonic welding.

[0045] The plurality of electrode tabs 11 may include a positive electrode tab 111 connected to the positive electrode and a negative electrode tab 112 connected to the negative electrode. Figure 1 The positive and negative electrode tabs 111 and 112 are shown protruding in opposite directions of the electrode assembly 10, but the present invention is not limited thereto. For example, the positive and negative electrode tabs 111 and 112 may protrude from one side of the electrode assembly 10 in parallel with each other in the same direction.

[0046] The electrode lead 12 that supplies power to the outside of the secondary battery 1 can be connected to the electrode connector 11 of the electrode assembly 10 by spot welding or the like. In addition, a portion of the electrode lead 12 may be surrounded by an insulating portion 14. The insulating portion 14 may be constrained to the terraces 23 and 26 of the battery case 20, and more specifically, to the terraces 23 and 26 that are thermally fused to the first shell 20a and the second shell 20b of the battery case 20. Therefore, the insulating portion 14 can insulate the electrode lead 12 from the battery case 20 and maintain the sealing of the battery case 20. Although the insulating portion 14 is generally formed of a relatively thin insulating tape that can be easily attached to the electrode lead 12, the present invention is not limited thereto. For example, other materials may also be used as the insulating portion 14 as long as the electrode lead 12 can be insulated.

[0047] The electrode lead 12 may have one end connected to the electrode tab 11 and the other end protruding to the outside of the battery case 20. The electrode lead 12 may include a positive lead 121 connected to the positive tab 111 and a negative lead 122 connected to the negative tab 112.

[0048] In this regard, the electrode lead 12 may electrically connect the electrode assembly 10 to electrical components outside the battery case 20. In addition, since each of the positive electrode tab 111 and the negative electrode tab 112 is formed to protrude in various directions, the positive electrode lead 121 and the negative electrode lead 122 may extend in various directions, for example, in opposite directions from opposite sides of the battery case 20, or in the same direction from one side of the battery case.

[0049] The battery case 20 may accommodate the electrode assembly 10 therein and may be formed by molding a laminate sheet. In more detail, when the laminate sheet having flexibility is stretched and molded using a die and a punch, a portion of the battery case 20 may be extended to form a cup portion 22 having a pouch-shaped accommodation space.

[0050] The electrode assembly 10 may be housed in the cup portion 22 of the battery case 20 so that a portion of the electrode lead 12 is exposed, and then the battery case 20 may be sealed. In one embodiment, the battery case 20 may include a pair of cases 20a and 20a, more specifically, a first case 20a and a second case 20b.

[0051] The first shell 20a and the second shell 20b may be connected to each other by means of the folding portion 21. However, the present invention is not limited thereto. For example, the first shell 20a and the second shell 20b may be manufactured separately, and then the first shell 20a and the second shell 20b may be sealed together after the electrode assembly 10 is accommodated therein.

[0052] The cup portion 22 may be provided in at least one of the pair of cases 20a and 20b to provide an accommodation space capable of accommodating the electrode assembly 10. The cup portion 22 may have a concave shape.

[0053] Hereinafter, a case where the cup portion 22 is provided in each of the housings 20a and 20b will be described. However, those skilled in the art will appreciate that the cup portion 22 may be provided in only one of the pair of housings 20a and 20b.

[0054] The cup portion 22 in each of the pair of cases 20a and 20B may be disposed to face each other and may accommodate the electrode assembly 10. When compared with the case where the cup portion 22 is disposed in only one of the pair of cases 20a and 20B, the battery case 20 may accommodate the electrode assembly 10 having an increased thickness and thus a larger capacity.

[0055] The first shell 20a and the second shell 20b may be connected to each other by means of the folding portion 21. When the cup portion 22 is provided in each of the shells 20a and 20b, a portion of the folding portion 21 may be provided between the cup portion 22 of the first shell 20a and the cup portion 22 of the second shell 20b, and another portion of the folding portion 21 may be provided between the first step portion 23 of the first shell 20a and the first step portion 23 of the second shell 20b. The first step portion 23 will be described later.

[0056] The folded portion 21 may be parallel to the length direction of the electrode assembly 10 (eg, parallel to Figures 1 to 3 When the folding portion 21 is folded, the first shell 20a and the second shell 20b can face each other.

[0057] The housings 20a and 20B may include step portions 23 and 26 respectively disposed around the cup portion 22. In more detail, the step portions 23 and 26 may include a pair of first step portions 23 disposed on both sides of the cup portion 22 in the longitudinal direction (e.g., a direction parallel to the X-axis) and a second step portion 26 connecting the pair of first step portions 23 to each other and disposed on one side of the cup portion 22 in the width direction (e.g., a direction parallel to the Y-axis).

[0058] The second step portion 26 may be provided on the opposite side of the folding portion 21 relative to the cup portion 22. If the first and second shells 20a and 20b are manufactured separately and connected to each other without the folding portion 21, the second step portion 26 may be provided on both sides of the cup portion 22 in the width direction.

[0059] When the folding portion 21 is folded, the step portions 23 and 26 of the first and second shells 20a and 20b may contact each other. Here, the insulating portion 14 of the electrode assembly 10 may be disposed between the step portions 23 and 26 of the pair of shells 20a and 20b. For example, the insulating portion 14 may be disposed between the first step portions 23 of the pair of shells 20a and 20b.

[0060] Figure 2 is a plan view of a pouch-type secondary battery according to an embodiment of the present invention, Figure 3 is based on Figure 2 A partially enlarged plan view of a pouch-type secondary battery.

[0061] The battery case 20 may include a pair of first sealing portions 24 and a second sealing portion 27, wherein the pair of first sealing portions 24 are arranged on both sides of the cup portion 22 in the length direction, and the second sealing portion 27 connects the pair of first sealing portions 24 to each other and is arranged on the side of the cup portion 22 in the width direction opposite to the folding portion 21.

[0062] The sealing portions 24 and 27 may be a portion of the step portions 23 and 26 that are sealed to each other when the first shell 20a and the second shell 20b are in contact with each other. In more detail, the first sealing portion 24 may be provided by sealing the outsides of the first step portion 23 of the pair of shells 20a and 20b to each other. Similarly, the second sealing portion 27 may be provided by sealing the outsides of the second step portion 26 of the pair of shells 20a and 20b to each other.

[0063] Each first sealing portion 24 may connect the folded portion 21 to the second sealing portion 27. Therefore, the battery case 20 may be sealed by the second sealing portion 27 and the pair of first sealing portions 24.

[0064] A size (eg, width) of each of the first sealing portion 24 and the second sealing portion 27 may be substantially constant, but the present invention is not limited thereto.

[0065] Additional references Figure 3 The first sealing portion 24 may include a first section 241 , a second section 242 and a third section 243 .

[0066] The first section 241 may extend between the second seal portion 27 and the second section 242. The distance between the first section 241 and the cup portion 22 may increase along the length of the first section 241 in a direction from the second seal portion 27 toward the second section 242. That is, the first section 241 may extend in an inclined or curved direction relative to the width direction of the cup portion 22.

[0067] The second section 242 may extend between the first section 241 and the third section 243, and the electrode lead 12 may protrude through the second section 242. In more detail, the insulating portion 14 insulating the electrode lead 12 may be provided between the second sections 242 of the first sealing portions 24 of the pair of housings 20a and 20b. The distance between the second section 242 and the cup portion 22 may be constant over the length of the second section 242. That is, the second section 242 may extend parallel to the width direction of the cup portion 22.

[0068] The third section 243 may extend between the second section 242 and the folding portion 21. The distance between the third section 243 and the cup portion 22 increases along the length of the third section 243 in a direction from the folding portion 21 toward the second section 242. That is, the third section 243 may extend in an inclined or curved direction relative to the width direction of the cup portion 22.

[0069] The size of the first section 241 may be greater than the size of the third section 243. The size of the second section 242 may be greater than the size of the third section 243.

[0070] In the length direction of the cup portion 22 , a minimum distance d1 between the first segment 241 and the electrode assembly 10 may be smaller than a minimum distance d2 between the third segment 243 and the electrode assembly 10 .

[0071] Due to the configuration of the first sealing portion 24 , a space in a battery module (not shown) accommodating a plurality of pouch-type secondary batteries 1 may be effectively utilized.

[0072] The second sealed portion 27 may be folded at least once toward the cup portion 21. For example, the second sealed portion 27 may be double folded (DSF). Therefore, the energy density of the pouch type secondary battery 1 may be increased.

[0073] The battery case 20 may further include an air pocket portion 25 disposed between the cup portion 22 and the first sealing portion 24 .

[0074] The air pocket portion 25 may include an interior that is not sealed from each other on the first terrace portion 23 of the pair of shells 20a and 20b. In this regard, the interior of the air pocket portion 25 communicates with the accommodation space of the cup portion 22, thereby allowing the gas generated in the electrode assembly 10 to be accommodated in the air pocket portion 25 and the cup portion 22.

[0075] The battery case 20 may further include a non-sealing portion 28 disposed between the cup portion 22 and the second sealing portion 27 .

[0076] The non-sealed portion 28 may be the inner part of the second terrace portion 26 of the pair of cases 20a and 20b that is not sealed with each other. Due to the non-sealed portion 28, a high temperature sealing tool for forming the second sealed portion 27 may be prevented from contacting the cup portion 22 and affecting the electrode assembly 10.

[0077] The non-sealed portion 28 may also communicate with the air pocket portion 25, so that the gas generated in the electrode assembly 10 may be contained in the non-sealed portion 28 and travel to the air pocket portion 25. Since the width of the non-sealed portion 28 is narrower than that of the air pocket portion 25, the amount of gas that the non-sealed portion 28 alone can contain may be insufficient.

[0078] The battery case 20 may further include a sub-seal portion 29 connected to the first seal portion 24. The sub-seal portion 29 may be formed by sealing a portion of the outside of the folded portion 21. In more detail, the sub-seal portion 29 may be formed by sealing a portion of the folded portion 21 disposed on the first terrace portion 23 of a pair of housings 20a and 20b between the third section 243 and the cup portion 22. The sub-seal portion 29 may extend substantially parallel to the length direction of the cup portion 22 and have a predetermined interval with the cup portion 22.

[0079] The sub-sealing portion 29 can further improve the overall sealing strength of the battery case 20 .

[0080] As the demand for high-capacity batteries (such as batteries for electric vehicles) increases, the size and weight of the electrode assembly increases to meet the high-capacity demand. However, when an external impact occurs, such as when an electric vehicle collides, the pouch-type battery case 20 that accommodates the larger size and heavier weight of the electrode assembly is more susceptible to damage. In other words, when the electrode assembly is forced to shift into the battery case, the larger and heavier electrode assembly may penetrate the pouch-type battery case. If the pouch-type battery case is damaged, the electrolyte may leak, or the electrode assembly may deform, resulting in fire, explosion, or other serious limitations on battery performance and safety.

[0081] To alleviate the problem that the electrode assembly 10 is displaced from its original position to be forced to contact and damage / penetrate the battery case 20 , the pouch-type secondary battery 1 according to the present invention may be formed such that the ratio of the area of ​​the first sealing portion 24 to the weight of the electrode assembly 10 satisfies certain conditions.

[0082] In more detail, when the area of ​​the first sealing portion 24 is A mm 2 , and when the weight of the electrode assembly 10 is B g, the ratio A / B may be greater than or equal to about 0.29. That is, the area (mm2) of each first sealing portion 24 2 ) may be greater than about 0.29 times the weight (g) of the electrode assembly 10.

[0083] Since inertia increases as the weight of the electrode assembly 10 increases, the heavier the electrode assembly 10 is, the higher the risk that the battery case 20 may be damaged when an external impact is applied.

[0084] In addition, the stress applied to the battery case 20 can be changed according to the direction in which the external impact is applied. In other words, since the length of each first seal portion 24 is shorter than the length of the second seal portion 27, when an external impact is applied from the electrode assembly 10 to the first seal portion 24, the stress applied to the battery case 20 is greater than the case where the same force is applied to the second seal portion 27. Therefore, the risk of damage or penetration of the first seal portion 24 is greater than the risk of damage or penetration of the second seal portion 27.

[0085] Therefore, in order to improve impact resistance, the area of ​​the first sealing portion 24 should be increased to offset the stress applied to the battery case 20 by the heavier electrode assembly 10 .

[0086] More specifically, if the area (mm) of the first sealing portion 24 is 2 ) is approximately less than 0.29 times the weight (g) of the electrode assembly 10, when an external impact is applied to the pouch-type secondary battery 1, there is a risk that the battery case 20 may be damaged by the electrode assembly 10 or the electrode assembly 10 may penetrate the battery case 20.

[0087] In addition, when the area of ​​the first sealing portion 24 is excessively increased, the energy density of the pouch-type secondary battery 1 may be reduced. Therefore, the area (mm 2 ) may be less than about 0.37 times the weight (g) of the electrode assembly 10, thereby providing improved safety without sacrificing the performance of the secondary battery 1. That is, the ratio A / B may be in the range of about 0.29 to about 0.37.

[0088] Furthermore, if the area (mm) of the first sealing portion 24 2 ) is about 0.37 times the weight (g) of the electrode assembly 10, the energy density of the pouch-type secondary battery may be too low. In addition, when the size of the pouch-type secondary battery 1 increases, it may be difficult to accommodate a plurality of larger pouch-type secondary batteries in a battery module (not shown).

[0089] In the following, reference will be made to Figures 1 to 3 Additional features of the pouch-type secondary battery 1 are described.

[0090] The pouch-type secondary battery 1 can also minimize the force that occurs when the electrode assembly 10 is displaced from its original position due to an external impact, thereby minimizing damage or penetration. Specifically, this result occurs when the ratio of the minimum distance d1 between the first sealing portion 24 and the electrode assembly 10 in the length direction of the cup portion 22 relative to the length L of the electrode assembly 10 meets a specific condition.

[0091] In more detail, in the pouch type secondary battery 1 , a minimum distance d1 (hereinafter, referred to as “gap distance”) between the first sealing portion 24 and the electrode assembly 10 in the length direction of the cup portion 22 may be about 0.5% or more compared to the length L of the electrode assembly 10 .

[0092] As described above, since the minimum distance d1 between the first segment 241 and the electrode assembly 10 in the length direction of the cup portion 22 is smaller than the minimum distance d2 between the third segment 243 and the electrode assembly 10 , the gap distance d1 may refer to the minimum distance between the first segment 241 of the first sealing portion 24 and the electrode assembly 10 .

[0093] When the length L of the electrode assembly 10 increases, if an external impact is applied and the electrode assembly 10 is forced to be displaced against the inner surface of the battery case, the battery case 20 may be easily damaged.

[0094] However, since the gap distance d1 is the distance that the electrode assembly 10 may be displaced from its original position before it contacts the first seal, the risk that the electrode assembly 10 may damage and / or penetrate the first seal decreases as the gap distance increases.

[0095] Therefore, in order to achieve excellent impact resistance, the gap distance d1 should increase as the length L of the electrode assembly 10 increases.

[0096] If the gap distance d1 is less than about 0.5% of the total length L of the electrode assembly 10 , the electrode assembly 10 may damage the battery case 20 or penetrate the battery case 20 when an external impact is applied to the pouch-type secondary battery 1 .

[0097] In addition, in order to prevent the energy density of the pouch-type secondary battery 1 from being reduced due to an excessive increase in the gap distance d1, the gap distance d1 may be approximately 0.8% or less of the total length L of the electrode assembly 10. That is, the gap distance d1 may be approximately 0.5% to approximately 0.8% of the total length L of the electrode assembly 10. Therefore, the safety of the secondary battery 1 may be improved without sacrificing the performance of the secondary battery 1.

[0098] If gap distance d1 is greater than about 0.8% of total length L of electrode assembly 10, energy density of pouch type secondary battery 1 may be too low. In addition, when pouch type secondary battery 1 increases in size, it may be difficult to accommodate a plurality of larger pouch type secondary batteries in a battery module (not shown).

[0099] The ratio condition of the area of ​​the first sealing portion to the weight of the electrode assembly 10 and the ratio condition of the gap distance d to the length L of the electrode assembly 10 may be either one or the other, or the pouch-type secondary battery 1 may satisfy both conditions simultaneously. In addition, the above-mentioned shape of the first sealing portion 24 (specifically, the structure of the first segment 241, the second segment 242, and the third segment 243) may contribute to the above-mentioned ratio.

[0100] The above-disclosed subject matter is to be considered illustrative and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments that fall within the true spirit and scope of the present invention.

[0101] Therefore, the embodiments of the present invention should be regarded as illustrative rather than restrictive, and the technical idea of ​​the present invention is not limited to the aforementioned embodiments.

[0102] Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope will be construed as being included in the present invention.

[0103] [Explanation of Reference Numerals]

[0104] 1: Pouch-type secondary battery 10: Electrode assembly

[0105] 12: Electrode lead 14: Insulation

[0106] 20: Pouch-type battery case 21: Folding part

[0107] 22: Cup part 23: First step part

[0108] 24: First sealing portion 241: First section

[0109] 242: Second section 243: Third section

[0110] 25: Airbag section 26: Second landing section

[0111] 27: Second sealing part 28: Non-sealing part

[0112] 29: Sub-seal

Claims

1. A pouch-type secondary battery, comprising: Electrode assembly; as well as Pouch type battery housing, Wherein, the pouch-type battery housing comprises: a cup portion configured to accommodate the electrode assembly; a pair of first sealing portions, the pair of first sealing portions being respectively arranged on both sides of the cup portion in the length direction; and a second sealing portion connecting the pair of first sealing portions to each other and provided on one side of the cup portion in the width direction, Wherein, when the area of ​​the first sealing portion is A mm 2 , and when the weight of the electrode assembly is B g, the ratio A / B is approximately greater than 0.

29.

2. The pouch-type secondary battery according to claim 1, wherein: The ratio A / B is approximately 0.37 or less.

3. The pouch-type secondary battery according to claim 1, wherein: The pouch-type battery case further includes an air pocket portion disposed between the cup portion and one of the pair of first sealing portions, wherein the air pocket portion is configured to contain gas exhausted from the electrode assembly.

4. The pouch-type secondary battery according to claim 1, wherein A minimum distance between the first sealing portion and the electrode assembly in the length direction of the cup portion is in a range between about 0.5% and about 0.8% of the length of the electrode assembly.

5. The pouch type secondary battery according to claim 1, wherein The first sealing portion comprises: a first section connected to the second sealing portion and having a distance from the cup portion increasing as the distance from the second sealing portion increases in the length direction of the cup portion; and A second section is connected to the first section and an electrode lead connected to the electrode assembly protrudes from the second section.

6. The pouch type secondary battery according to claim 5, wherein: A minimum distance between the first section and the electrode assembly in the length direction of the cup portion is in a range between about 0.5% and about 0.8% of the length of the electrode assembly.

7. The pouch type secondary battery according to claim 5, wherein: The pouch type battery case further includes a folded portion that is provided at an opposite side of the second sealing portion relative to the cup portion and connects the pair of first sealing portions to each other, and Each of the pair of first sealing portions further includes a third section that connects the second section to the folded portion and whose distance from the cup portion in the length direction of the cup portion increases as it moves away from the folded portion.

8. The pouch type secondary battery according to claim 7, wherein: In the length direction of the cup portion, a minimum distance between the first section and the electrode assembly is smaller than a minimum distance between the third section and the electrode assembly.

9. The pouch type secondary battery according to claim 7, wherein: The length of the first section is greater than the length of the third section.

10. A pouch-type secondary battery, comprising: Electrode assembly; as well as Pouch type battery housing, Wherein, the pouch-type battery housing comprises: a cup portion configured to accommodate the electrode assembly; a pair of first sealing portions, the pair of first sealing portions being respectively arranged on both sides of the cup portion in the length direction; and a second sealing portion connecting the pair of first sealing portions to each other and provided on at least one side in the width direction of the cup portion, Wherein, a minimum distance between the first sealing portion and the electrode assembly in the length direction of the cup portion is greater than about 0.5% of the length of the electrode assembly.

11. The pouch type secondary battery according to claim 10, wherein: A minimum distance between the first sealing portion and the electrode assembly in a length direction of the cup portion is less than or equal to about 0.8% of a length of the electrode assembly.

12. The pouch type secondary battery according to claim 10, wherein: When the area of ​​the first sealing portion is A mm 2 , and when the weight of the electrode assembly is B g, the ratio A / B ranges from 0.29 to 0.

37.

13. The pouch type secondary battery according to claim 10, wherein: The pouch type battery case further includes an air pocket portion disposed between the cup portion and at least one of the pair of first sealing portions.

14. A pouch-type secondary battery, comprising: Electrode assembly; as well as A pouch-type battery case, the pouch-type battery case comprising: a cup portion configured to accommodate the electrode assembly; A pair of first sealing portions, the pair of first sealing portions are respectively arranged on both sides of the cup portion in the length direction; a second sealing portion connecting the pair of first sealing portions to each other and provided on at least one side of the cup portion in the width direction; and an air pocket portion, the air pocket portion being disposed between the cup portion and at least one of the pair of first sealing portions, The first sealing portion includes a first section, and the first section defines an inclined bending length between the second sealing portion and the second section.

15. The pouch type secondary battery according to claim 14, wherein The pouch type battery case further includes a folded portion provided at an opposite side of the second sealing portion with respect to the cup portion, the folded portion connecting the pair of first sealing portions to each other.

16. The pouch type secondary battery according to claim 15, wherein The first seal portion further includes a third section defining an inclined bend length between the folded portion and the second section.

17. The pouch type secondary battery according to claim 15, wherein: When the area of ​​the first sealing portion is A mm 2 And when the weight of the electrode assembly is B g, the ratio A / B is between about 0.29 and about 0.

37.

18. The pouch type secondary battery according to claim 16, wherein The pouch-type battery case further includes a sub-sealing portion disposed on or adjacent to the folded portion and disposed between the third section and the cup portion.

19. The pouch type secondary battery according to claim 16, wherein: A minimum distance between the first section of the first sealing portion and the electrode assembly in a length direction of the cup portion is between about 0.5% and about 0.8% of a length of the electrode assembly.

20. The pouch type secondary battery according to claim 19, wherein The minimum distance is a distance between the cup portion and an end portion of the first section of the first seal portion connected to the second seal portion.

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