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 that accommodates the electrode assembly, a pair of first seal portions located on both sides of the cup portion in a length direction, and a second seal portion that connects the pair of first seal portions and is located on one side of the cup portion in a width direction. The area of ​​each of the first seal portions may be expressed as A mm 2 When the weight of the electrode assembly is Bg, A / B may be 0.29 or more.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0121205 filed on September 23, 2022 and Korean Patent Application No. 10-2023-0127258 filed on September 22, 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 pouch-type secondary battery, and more particularly to a pouch-type secondary battery having excellent impact resistance. [Background technology]

[0003] Lithium secondary batteries are generally manufactured by coating a positive electrode active material slurry onto a positive electrode current collector and a negative electrode current collector to form a positive electrode and a negative electrode. The positive electrode and the negative electrode are then stacked on either side of a separator to form an electrode assembly of a predetermined shape. The electrode assembly is then placed in a case and an electrolyte is injected.

[0004] In general, secondary batteries are classified according to the shape of the case that houses the electrode assembly. Examples of secondary batteries include pouch-type secondary batteries, can-type secondary batteries, and prismatic-type secondary batteries. For example, a pouch-type secondary battery is manufactured by compressing a flexible pouch film laminate to form a cup, placing an electrode assembly in the cup, injecting an electrolyte, and then sealing the seal. In contrast, a can-type secondary battery is manufactured by placing an electrode assembly in a metal can, which is equipped with a top cap to seal the can, and injecting an electrolyte into the sealed can.

[0005] Pouch-type secondary batteries are lightweight, exhibit excellent space utilization, and have high energy density due to the use of stacked electrode assemblies. However, compared to can-type secondary batteries, they are more vulnerable to fire and explosion due to external impact and electrolyte leakage.

[0006] Secondary batteries are used in various products, including electric vehicles, to reduce or prevent greenhouse gas emissions. When used in electric vehicles, the secondary batteries are required to have excellent safety to protect passengers. Therefore, there is a need to improve the impact resistance of pouch-type secondary batteries. Summary of the Invention [Problem to be solved by the invention]

[0007] One problem to be solved by the present invention relates to a pouch-type secondary battery in which displacement of an electrode assembly and / or leakage of an electrolyte solution is suppressed when an external impact is applied. [Means for solving the problem]

[0008] 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 that accommodates the electrode assembly, a pair of first seal portions located on both sides of the cup portion in a length direction, and a second seal portion that connects the pair of first seal portions and is located on one side of the cup portion in a width direction. The area of ​​each of the first seal portions may be expressed as A mm 2 When the weight of the electrode assembly is Bg, A / B may be 0.29 or more.

[0009] The A / B may be 0.37 or less.

[0010] The pouch-type battery case may further include a gas pocket portion located between the cup portion and one of the pair of first seal portions and configured to accommodate gas discharged from the electrode assembly.

[0011] The minimum distance between the first seal portion and the electrode assembly in the overall length direction of the cup portion may be 0.5% to 0.8% of the overall length of the electrode assembly.

[0012] The first sealing portion may include a first section connected to the second sealing portion, the distance between the first sealing portion and the cup portion in the overall length direction of the cup portion increasing with increasing distance from the second sealing portion, and a second section connected to the first section, from which an electrode lead connected to the electrode assembly protrudes.

[0013] The minimum distance between the first section and the electrode assembly in the overall length direction of the cup portion may be 0.5% to 0.8% of the overall length of the electrode assembly.

[0014] The pouch-type battery case may further include a folding portion located on the opposite side of the cup portion from the second sealing portion and connecting the pair of first sealing portions. The first sealing portion may further include a third section connecting the second section and the folding portion, the distance between the first sealing portion and the cup portion in the overall length direction of the cup portion increasing with increasing distance from the folding portion.

[0015] 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.

[0016] The length of the first section may be longer than the length of the third section.

[0017] 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 that accommodates the electrode assembly, a pair of first seal portions located on both sides of the cup portion in a length direction, and a second seal portion that connects the pair of first seal portions and is located on at least one side of the cup portion in a width direction. A minimum distance between the first seal portions and the electrode assembly in the length direction of the cup portion may be 0.5% or more of the length of the electrode assembly.

[0018] The minimum distance between the first seal portion and the electrode assembly in the overall length direction of the cup portion may be 0.8% or less of the overall length of the electrode assembly.

[0019] The area of ​​each of the first seal portions is A mm 2 When the weight of the electrode assembly is Bg, A / B may be 0.29 to 0.37.

[0020] The pouch-type battery case may further include a gas pocket portion disposed between the cup portion and at least one of the pair of first seal portions.

[0021] 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 that accommodates the electrode assembly, a pair of first seal portions located on both sides of the cup portion in a full-length direction, a second seal portion connecting the pair of first seal portions and located on at least one side of the cup portion in a full-width direction, and a gas pocket portion located between the cup portion and at least one of the pair of first seal portions. The first seal portion may include a first section connected to the second seal portion and curved at an angle, and a second section connected to the first section.

[0022] The pouch-type battery case may further include a folding portion located on the opposite side of the second sealing portion with respect to the cup portion and connecting the pair of first sealing portions.

[0023] The first sealing portion may further include a third section that connects the folding portion and the second section and is curved at an angle.

[0024] The area of ​​each of the first seal portions is A mm 2 When the weight of the electrode assembly is Bg, A / B may be 0.29 to 0.37.

[0025] The pouch-type battery case may further include a sub-seal portion located in the folding portion between the third section and the cup portion.

[0026] The minimum distance between the first seal portion and the electrode assembly in the overall length direction of the cup portion may be 0.5% to 0.8% of the overall length of the electrode assembly.

[0027] The minimum distance may be a distance between the cup portion and an end of the first section connected to the second seal portion. [Effects of the Invention]

[0028] According to a preferred embodiment of the present invention, the ratio of the area of ​​the first seal portion of the pouch-type battery case to the weight of the electrode assembly satisfies a specific condition, or the ratio of the minimum distance between the first seal portion and the electrode assembly to the overall length of the electrode assembly satisfies a specific condition, or both of these conditions are satisfied. This reduces the risk of the first seal portion being damaged or perforated by the electrode assembly upon external impact, and suppresses displacement of the electrode assembly and / or leakage of electrolyte, thereby achieving excellent impact resistance.

[0029] 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. [Brief explanation of the drawings]

[0030] 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.

[0031] [Figure 1] 1 is an exploded view of a pouch-type secondary battery according to an embodiment of the present invention; [Figure 2] FIG. 2 is a plan view of the pouch-type secondary battery of FIG. [Figure 3]FIG. 3 is a partially enlarged plan view of the pouch-type secondary battery of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0032] 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.

[0033] FIG. 1 is an exploded view of a pouch-type secondary battery 1 according to one embodiment of the present invention.

[0034] 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").

[0035] As shown in FIG. 1, the electrode assembly 10 may be formed by alternately stacking positive and negative electrodes with separators interposed therebetween. That is, the electrode assembly 10 may include a plurality of electrodes and separators interposed between the electrodes to insulate the electrodes from one another. Alternatively, the electrode assembly 10 may be of a jelly roll type, a stack-and-fold type, or the like. The electrode assembly 10 may be housed in the cup portion 22 of the battery case 20 together with an electrolyte.

[0036] The electrode assembly 10 may include multiple electrode tabs 11. Each electrode tab 11 is connected to a positive electrode or a negative electrode, protrudes from the electrode assembly 10, and serves as a path for electrons to move between the inside and outside of the electrode assembly 10.

[0037] 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.

[0038] The electrode tabs 11 may include a positive electrode tab 111 connected to a positive electrode and a negative electrode tab 112 connected to a negative electrode. The positive electrode tab 111 and the negative electrode tab 112 may protrude in opposite directions from the electrode assembly 10 as shown in FIG. 1, but the present invention is not limited thereto. For example, the positive electrode tab 111 and the negative electrode tab 112 may protrude in parallel in the same direction from one side of the electrode assembly 10.

[0039] An electrode lead 12 for supplying electricity to the outside of the secondary battery 1 may be connected to the electrode tab 11 of the electrode assembly 10 by spot welding or the like. A portion of the electrode lead 12 may be surrounded by an insulating portion 14. The insulating portion 14 may be limited to the terrace portions 23, 26 of the battery case 20, more specifically, the terrace portions 23, 26 where the first case 20a and the second case 20b of the battery case 20 are thermally fused together. Thus, the insulating portion 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 portion 14, but the present invention is not limited thereto. For example, other materials may be used as long as they can insulate the electrode lead 12.

[0040] 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 121 connected to the positive electrode tab 111 and a negative electrode lead 122 connected to the negative electrode tab 112.

[0041] In this regard, the electrode lead 12 can electrically connect the electrode assembly 10 to electrical components outside the battery case 20. In addition, since the positive electrode tab 111 and the negative electrode tab 112 are formed to protrude in different directions, the positive electrode lead 121 and the negative electrode lead 122 can also extend in different directions. For example, the positive electrode lead 121 and the negative electrode lead 122 may extend in opposite directions from both sides of the battery case 20 or may extend in the same direction from one side of the battery case 20.

[0042] The battery case 20 can accommodate the electrode assembly 10 therein, and may be formed by molding a laminate sheet. More specifically, a flexible laminate sheet may be drawn using a die, a punch, or the like, so that a portion of the laminate sheet is stretched to form the cup portion 22 having a pocket-shaped storage space.

[0043] The electrode assembly 10 is housed in a cup portion 22 of a battery case 20 so that a portion of the electrode lead 12 is exposed, and the battery case 20 may be sealed. For example, the battery case 20 may include a pair of cases 20a and 20b, more specifically, a first case 20a and a second case 20b.

[0044] The first case 20a and the second case 20b may be connected by a folding portion 21. However, the present invention is not limited thereto. For example, the first case 20a and the second case 20b may be manufactured separately, and the first case 20a and the second case 20b may be sealed together after the electrode assembly 10 is housed inside.

[0045] At least one of the pair of cases 20a, 20b may be formed with a cup portion 22 to provide an accommodating space capable of accommodating the electrode assembly 10. The cup portion 22 may have a recessed shape.

[0046] The following description will be given of a case where each of the cases 20a and 20b is formed with a cup portion 22. However, those skilled in the art will understand that the cup portion 22 may be provided on only one of the pair of cases 20a and 20b.

[0047] The cup portions 22 of the pair of cases 20a, 20b are arranged opposite each other and can both accommodate the electrode assembly 10. Compared to when the cup portion 22 is formed in only one of the pair of cases 20a, 20b, the thickness of the battery case 20 is increased, and therefore, an electrode assembly 10 with a larger capacity can be accommodated.

[0048] The first case 20a and the second case 20b may be connected by a folding portion 21. When a cup portion 22 is formed in each of the cases 20a and 20b, a portion of the folding portion 21 may be located between the cup portion 22 of the first case 20a and the cup portion 22 of the second case 20b, and another portion of the folding portion 21 may be located between the first terrace portion 23 of the first case 20a and the first terrace portion 23 of the second case 20b. The first terrace portion 23 will be described later.

[0049] The folding portion 21 may extend parallel to the overall length of the electrode assembly 10 (for example, a direction parallel to the X-axis shown in FIGS. 1 to 3). When the folding portion 21 is folded, the first case 20a and the second case 20b may face each other.

[0050] Each of the cases 20a, 20b may include terrace portions 23, 26 located on the periphery of the cup portion 22. More specifically, the terrace portions 23, 26 may include a pair of first terrace portions 23 located on both sides of the cup portion 22 in the overall length direction (e.g., a direction parallel to the X-axis), and a second terrace portion 26 connecting the pair of first terrace portions 23 and located on one side of the cup portion 22 in the overall width direction (e.g., a direction parallel to the Y-axis).

[0051] The second terrace portion 26 may be located on the opposite side of the cup portion 22 from the folding portion 21. When the first case 20a and the second case 20b are manufactured separately and not connected by the folding portion 21, the second terrace portion 26 may be located on both sides of the cup portion 22 in the overall width direction.

[0052] When the folding portion 21 is folded, the terrace portions 23, 26 of the first case 20a and the second case 20b may abut against each other. Here, the insulating portion 14 of the electrode assembly 10 may be located between the terrace portions 23, 26 of the pair of cases 20a, 20b. For example, the insulating portion 14 may be located between the first terrace portion 23 of the pair of cases 20a, 20b.

[0053] FIG. 2 is a plan view of a pouch-type secondary battery according to one embodiment of the present invention, and FIG. 3 is a partially enlarged plan view of the pouch-type secondary battery of FIG.

[0054] The battery case 20 may include a pair of first sealing portions 24 located on both sides of the cup portion 22 in the overall length direction, and a second sealing portion 27 connecting the pair of first sealing portions 24 and located on one side of the cup portion 22 in the overall width direction, opposite the folding portion 21.

[0055] The seal portions 24, 27 may be portions where the terrace portions 23, 26 are sealed to each other when the first case 20a and the second case 20b are brought into contact with each other. More specifically, the first seal portion 24 may be formed by sealing portions of the outer sides of the first terrace portions 23 of the pair of cases 20a, 20b to each other. Similarly, the second seal portion 27 may be formed by sealing portions of the outer sides of the second terrace portions 26 of the pair of cases 20a, 20b to each other.

[0056] Each first seal portion 24 can connect the folding portion 21 and the second seal portion 27. Therefore, the battery case 20 can be sealed by the pair of the first seal portion 24 and the second seal portion 27.

[0057] The dimensions (for example, width) of the first seal portion 24 and the second seal portion 27 may be formed to be substantially constant, but the present invention is not limited to this.

[0058] Referring further to FIG. 3, the first sealing portion 24 may further include a first section 241, a second section 242, and a third section 243.

[0059] 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 the direction from the second seal portion 27 toward the second section 242. That is, the first section 241 may extend obliquely or in a curved direction relative to the overall width direction of the cup portion 22.

[0060] 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. More specifically, an insulating section 14 that insulates the electrode lead 12 may be located between the second sections 242 of the first seal portions 24 of the pair of cases 20a, 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 overall width direction of the cup portion 22.

[0061] 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 may increase along the length of the third section 243 in the direction from the folding portion 21 toward the second section 242. That is, the third section 243 may extend obliquely or in a curved direction relative to the overall width direction of the cup portion 22.

[0062] The dimensions of the first section 241 may be greater than the dimensions of the third section 243. The dimensions of the second section 242 may be greater than the dimensions of the third section 243.

[0063] In the overall length direction of the cup portion 22, the minimum distance d1 between the first section 241 and the electrode assembly 10 may be smaller than the minimum distance d2 between the third section 243 and the electrode assembly 10.

[0064] Such a configuration of the first seal portion 24 allows efficient use of the space within a battery module (not shown) that houses a plurality of pouch-type secondary batteries 1.

[0065] The second seal portion 27 may be folded at least once toward the cup portion 22. For example, the second seal portion 27 may be double-side folded (DSF), thereby increasing the energy density of the pouch-type secondary battery 1.

[0066] The battery case 20 may further include a gas pocket portion 25 located between the cup portion 22 and the first seal portion 24 .

[0067] The gas pocket portion 25 may include a part of the inside of the first terrace portions 23 of the pair of cases 20a, 20b that is not sealed to each other. In this regard, the interior of the gas pocket portion 25 may be in communication with the storage space of the cup portion 22, so that the gas generated from the electrode assembly 10 is stored not only in the cup portion 22 but also in the gas pocket portion 25.

[0068] The battery case 20 may further include an unsealed portion 28 located between the cup portion 22 and the second sealed portion 27 .

[0069] The unsealed portion 28 may be a part of the inside of the second terrace portions 26 of the pair of cases 20 a, 20 b that is not sealed to each other. The unsealed portion 28 can prevent a high-temperature sealing tool used to form the second seal portion 27 from coming into contact with the cup portion 22 and affecting the electrode assembly 10.

[0070] The unsealed portion 28 may also communicate with the gas pocket portion 25. The gas generated from the electrode assembly 10 may be accommodated in the unsealed portion 28 and move to the gas pocket portion 25. Because the width of the unsealed portion 28 is narrower than that of the gas pocket portion 25, the amount of gas that the unsealed portion 28 can accommodate by itself may be insufficient.

[0071] 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 folding portion 21. More specifically, the sub-seal portion 29 may be formed by sealing a portion of the folding portion 21 that is located between the third section 243 and the cup portion 22 in the first terrace portion 23 of the pair of cases 20a, 20b. The sub-seal portion 29 may extend substantially parallel to the entire length of the cup portion 22 and may be spaced a predetermined distance from the cup portion 22.

[0072] The sub-seal portion 29 further improves the overall seal strength of the battery case 20 .

[0073] Meanwhile, as demand for batteries requiring high capacity, such as batteries for electric vehicles, has increased, the size and weight of electrode assemblies have increased to meet the demand for high capacity. However, pouch-type battery cases housing large and heavy electrode assemblies are prone to damage when subjected to external impacts, such as an electric vehicle collision. That is, when the electrode assembly is forcibly moved toward the battery case, the large and heavy electrode assembly may protrude from the pouch-type battery case. Such damage to the pouch-type battery case can lead to electrolyte leakage and deformation of the electrode assembly, which can cause serious problems in battery performance and safety, such as fires and explosions.

[0074] In order to mitigate the risk of the electrode assembly 10 being displaced from its original position and forcibly contacting the battery case 20, damaging / piercing the battery case 20, the pouch-type secondary battery 1 according to the present invention may be formed so that the ratio of the area of ​​the first seal portion 24 to the weight of the electrode assembly 10 satisfies a specific condition.

[0075] More specifically, the area of ​​the first seal portion 24 is set to A mm 2 If the weight of the electrode assembly 10 is Bg, A / B may be 0.29 or more. 2 ) may be 0.29 times or more the weight (g) of the electrode assembly 10.

[0076] As the weight of the electrode assembly 10 increases, the inertia increases, and therefore a heavier electrode assembly 10 is more likely to damage the battery case 20 when subjected to an external impact.

[0077] Furthermore, the stress applied to the battery case 20 varies depending on the direction of the external impact. In other words, because each first seal portion 24 is shorter than the second seal portion 27, when an external impact is applied to the first seal portion 24 from the electrode assembly 10, the stress applied to the battery case 20 is greater than when the same force is applied to the second seal portion 27. Therefore, the first seal portion 24 is more likely to be damaged or perforated than the second seal portion 27.

[0078] Therefore, in order to improve the impact resistance, the area of ​​the first seal portion 24 needs to be increased to accommodate the stress applied to the battery case 20 by the heavier electrode assembly 10.

[0079] More specifically, the area (mm 2 ) is 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, the electrode assembly 10 may damage the battery case 20 or protrude from the battery case 20.

[0080] Furthermore, if the area of ​​the first seal portion 24 is excessively increased, the energy density of the pouch-type secondary battery 1 decreases. 2 ) may be 0.37 times or less the weight (g) of the electrode assembly 10, thereby providing improved safety without deteriorating the performance of the secondary battery 1. That is, the A / B ratio may be within the range of 0.29 to 0.37.

[0081] That is, the area of ​​the first seal portion 24 (mm 2 ) is greater than 0.37 times the weight (g) of the electrode assembly 10, the energy density of the pouch-type secondary battery 1 may be too low. Also, it may be difficult to accommodate multiple enlarged pouch-type secondary batteries 1 in a battery module (not shown).

[0082] Further features of the present invention will be described below with reference to FIGS.

[0083] The pouch-type secondary battery 1 can minimize the force generated when the electrode assembly 10 is displaced from its original position due to an external impact, as well as the resulting damage and penetration. More specifically, this result can be obtained when the ratio of the minimum distance d1 between the first seal portion 24 and the electrode assembly 10 in the overall length direction of the cup portion 22 to the overall length L of the electrode assembly 10 satisfies a specific condition.

[0084] More specifically, the pouch-type secondary battery 1 may have a minimum distance d1 (hereinafter referred to as the "clearance distance") between the first seal portion 24 and the electrode assembly 10 in the overall length direction of the cup portion 22 that is 0.5% or more of the overall length L of the electrode assembly 10.

[0085] As described above, in the overall length direction of the cup portion 22, the minimum distance d1 between the first section 241 and the electrode assembly 10 is smaller than the minimum distance d2 between the third section 243 and the electrode assembly 10, so the clearance distance d1 can mean the minimum distance between the first section 241 of the first seal portion 24 and the electrode assembly 10.

[0086] If the overall length L of the electrode assembly 10 is increased, the battery case 20 is likely to be damaged if an external impact is applied and the electrode assembly 10 is forcibly moved against the inner surface of the battery case.

[0087] However, because the clearance distance d1 is the distance that the electrode assembly 10 can be displaced from its original position before it contacts the first seal portion, as the clearance distance increases, the risk of the electrode assembly 10 damaging and / or penetrating the first seal portion decreases.

[0088] Therefore, in order to achieve excellent impact resistance, the clearance distance d1 must be increased as the overall length L of the electrode assembly 10 increases.

[0089] If the clearance distance d1 is less than 0.5% of the total length L of the electrode assembly 10, when an external impact is applied to the pouch-type secondary battery 1, the electrode assembly 10 may damage the battery case 20 or protrude from the battery case 20.

[0090] Furthermore, to prevent the energy density of the pouch-type secondary battery 1 from being reduced due to the clearance distance d1 being too large, the clearance distance d1 may be 0.8% or less of the total length L of the electrode assembly 10. In other words, the clearance distance d1 may be 0.5% to 0.8% of the total length L of the electrode assembly 10. As a result, the safety of the secondary battery 1 can be improved without deteriorating the performance of the secondary battery 1.

[0091] If the clearance distance d1 is greater than 0.8% of the total length L of the electrode assembly 10, the energy density of the pouch-type secondary battery 1 may become excessively low. Also, if the pouch-type secondary battery 1 becomes large, it may become difficult to ensure internal space in a battery module case that accommodates multiple pouch-type secondary batteries 1.

[0092] It is sufficient if either the ratio of the area of ​​the first seal portion 24 to the weight of the electrode assembly 10 or the ratio of the clearance distance d to the total length L of the electrode assembly 10 is satisfied, or the pouch-type secondary battery 1 may satisfy both of these conditions simultaneously. In addition, the shape of the first seal portion 24, specifically the structures of the first section 241, the second section 242, and the third section 243, can contribute to the aforementioned ratio.

[0093] 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.

[0094] Therefore, the embodiments disclosed in the present invention are for illustrative purposes only and are not intended to limit the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by such embodiments.

[0095] 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]

[0096] 1. Pouch-type secondary battery 10 Electrode assembly 12 electrode leads 14 Insulation section 20 Pouch-type battery case 21 Folding section 22 Cup section 23 First Terrace 24 First seal part 241 Section 1 242 Section 2 243 Section 3 25 Gas pocket 26 Second Terrace 27 Second seal part 28 Unsealed area 29 Sub-seal section

Claims

1. A pouch-type secondary battery including an electrode assembly and a pouch-type battery case, The pouch-type battery case includes: a cup portion that accommodates the electrode assembly; a pair of first seal portions located on both sides of the cup portion in the overall length direction; a second seal portion connecting the pair of first seal portions and positioned on one side of the cup portion in the overall width direction, The area of ​​each of the first seal portions is A mm ２ , wherein A / B is 0.29 or more, where Bg is the weight of the electrode assembly.

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

3. The pouch-type battery case includes:

2. The pouch-type secondary battery according to claim 1, further comprising a gas pocket portion located between the cup portion and one of the pair of first seal portions and configured to accommodate gas discharged from the electrode assembly.

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

5. The first seal portion is a first section connected to the second seal portion, the distance between the first section and the cup portion increasing in a length direction of the cup portion as the distance from the second seal portion increases; 5. The pouch-type secondary battery of claim 1, further comprising: a second section connected to the first section and having an electrode lead connected to the electrode assembly protruding therefrom.

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

7. The pouch-type battery case includes: a folding portion located on the opposite side of the second seal portion with respect to the cup portion and connecting the pair of first seal portions; The first seal portion is 6. The pouch-type secondary battery of claim 5, further comprising a third section connecting the second section and the folding section, the third section having a distance from the cup section increasing in a length direction of the cup section as the distance from the folding section increases.

8. The pouch-type secondary battery of claim 7 , wherein a minimum distance between the first section and the electrode assembly in the overall length direction of the cup portion 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 longer than the length of the third section.

10. A pouch-type secondary battery including an electrode assembly and a pouch-type battery case, The pouch-type battery case includes: a cup portion that accommodates the electrode assembly; a pair of first seal portions located on both sides of the cup portion in the overall length direction; a second seal portion connecting the pair of first seal portions and positioned on at least one side of the cup portion in the overall width direction, A pouch-type secondary battery, wherein a minimum distance between the first seal portion and the electrode assembly in a length direction of the cup portion is 0.5% or more of a length of the electrode assembly.

11. The pouch-type secondary battery of claim 10 , wherein a minimum distance between the first seal and the electrode assembly in a length direction of the cup is 0.8% or less of a length of the electrode assembly.

12. The area of ​​each of the first seal portions is A mm ２ 11. The pouch-type secondary battery according to claim 10, wherein, when the weight of the electrode assembly is Bg, A / B is 0.29 to 0.

37.

13. The pouch-type battery case includes: The pouch-type secondary battery according to claim 10 , further comprising a gas pocket portion disposed between the cup portion and at least one of the pair of first seal portions.

14. A pouch-type secondary battery including an electrode assembly and a pouch-type battery case, The pouch-type battery case includes: a cup portion that accommodates the electrode assembly; a pair of first seal portions located on both sides of the cup portion in the overall length direction; a second seal portion connecting the pair of first seal portions and positioned on at least one side of the cup portion in the overall width direction; a gas pocket portion located between the cup portion and at least one of the pair of first seal portions, The first seal portion is a first section connected to the second seal portion and curved at an angle; a second section connected to the first section.

15. The pouch-type battery case includes: The pouch-type secondary battery of claim 14 , further comprising a folding portion located on the opposite side of the second sealing portion with respect to the cup portion and connecting the pair of first sealing portions.

16. The first seal portion is The pouch-type secondary battery of claim 15 , further comprising a third section that connects the folding portion and the second section and is curved at an angle.

17. The area of ​​each of the first seal portions is A mm ２ 16. The pouch-type secondary battery according to claim 14, wherein, when the weight of the electrode assembly is Bg, A / B is 0.29 to 0.

37.

18. The pouch-type battery case includes: The pouch-type secondary battery of claim 16 , further comprising a sub-seal portion located in the folding portion between the third section and the cup portion.

19. 17. The pouch-type secondary battery of claim 16, wherein a minimum distance between the first seal and the electrode assembly in the overall length direction of the cup portion is 0.5% to 0.8% of the overall length of the electrode assembly.

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

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