Pouch type secondary battery, battery pack and method of manufacturing the pouch type secondary battery

Abstract

A pouch-type secondary battery, a battery pack, and a method for manufacturing a pouch-type secondary battery are disclosed. According to one aspect of the present invention, an outer material accommodating an electrode assembly has a seal portion formed along the perimeter of the electrode assembly, and the seal portion includes a first seal portion formed to cover an electrode lead, wherein one end of the first seal portion is formed within a predetermined distance from the upper corner portion of the perimeter of a cup formed in the pouch. A pouch-type secondary battery is disclosed.

Description

Technology Field

[0001] The present invention relates to a pouch-type secondary battery, a battery pack, and a method for manufacturing a pouch-type secondary battery. Background Technology

[0002] Rechargeable batteries capable of repeated charging and discharging can be classified into cylindrical, prismatic, and pouch-type batteries depending on their structure and manufacturing method. Among these, pouch-type batteries are manufactured by housing an electrode assembly within a pouch-type sheet and then sealing the sheet; compared to other types of rechargeable batteries, they have a simple structure and a high capacity per unit volume, making them widely used in automotive batteries or energy storage devices.

[0003] More specifically, a pouch-type secondary battery is generally manufactured by forming a cup with an indented shape in a pouch-type sheet, accommodating an electrode assembly within the cup, folding the pouch-type sheet so that a region of the pouch-type sheet covers the electrode assembly, and then forming a sealing portion that seals the perimeter of the electrode assembly.

[0004] Meanwhile, to enable the pouch-type secondary battery to be electrically connected to an external component, the pouch-type secondary battery is equipped with electrode leads having a protruding shape. At this time, the sealing portion is formed to cover the electrode leads. However, according to the prior art, there was a problem in which cracks occurred around the electrode leads.

[0005] FIG. 1 is a plan view illustrating the structure of a pouch-type secondary battery according to the prior art.

[0006] Referring to FIG. 1, in a secondary battery (1) according to the prior art, an electrode assembly (20) is contained within a pouch (30), and a sealing portion (30a) is formed around the electrode assembly (20).

[0007] Meanwhile, in the area around the electrode assembly (20) where the sealing portion (30a) is not formed, a folding portion (F) is formed where the sheet constituting the pouch (30) is folded. According to the prior art, since the sealing portion is not formed in the folding portion (F), the sheets constituting the pouch are not bonded to each other in the folding portion (F) and are in contact with each other.

[0008] However, since the sheets constituting the pouch are not bonded to each other in the folding portion (F), when the sealing portion (30a) is folded, a phenomenon occurs in which stress is concentrated in the area adjacent to the sealing portion (30a) within the folding portion (F), causing damage such as cracks to occur in the pouch forming the folding portion (F).

[0009] In particular, this problem frequently occurred in the vicinity of the sealing portion (see A in FIG. 1) formed to cover the electrode leads (20a, 20b) within the folding portion (F). For example, when configuring a battery module or battery pack, multiple pouch-type secondary batteries can be stacked, and electrode leads extending outward from each pouch-type secondary battery can be gathered and welded together to form an electrode lead bundle. Then, a battery module or battery pack can be made by forming an electrode lead bundle in this way and assembling multiple secondary battery groups. However, during this assembly process, there may be cases where the electrode leads bend upward or downward relative to the thickness direction of the secondary battery. In this case, force is concentrated in a part near the sealing portion (A in FIG. 1) formed to cover the electrode leads (20a, 20b) within the folding portion (F), causing a sharply folded shape. Furthermore, if bent beyond a certain angle, stress is concentrated, resulting in a pouch crack (including internal aluminum crack) problem. The problem to be solved

[0010] Therefore, the problem that the present invention aims to solve is to resolve the issue of damage to the pouch or cracking occurring in the area adjacent to the sealing portion covering the electrode lead among the folding portions (F). means of solving the problem

[0011] A pouch-type secondary battery according to the present invention comprises: an electrode assembly having a structure in which electrodes and separators are alternately arranged; a pouch-type outer casing having a cup (P) formed with an indented shape to accommodate the electrode assembly; and an electrode lead electrically connected to the electrode assembly and protruding outward through the periphery of the outer casing; wherein a sealing portion is formed along the periphery of the electrode assembly in the outer casing, and the electrode lead comprises a first electrode lead protruding outward through the upper periphery of the outer casing; wherein the sealing portion comprises a first sealing portion formed to cover the first electrode lead; and one end of the first sealing portion is formed within a predetermined distance from the upper corner portion of the periphery of the cup (P).

[0012] The left end and the right end of the first sealing portion may each be formed within a predetermined distance from the upper left corner of the perimeter of the cup (P) and within a predetermined distance from the upper right corner, respectively.

[0013] The electrode lead includes a second electrode lead that protrudes outward through the lower perimeter of the outer material; and the sealing part includes a second sealing part formed to cover the second electrode lead; and one end of the second sealing part may be formed within a predetermined distance from the lower corner portion of the perimeter of the cup (P).

[0014] The left end and right end of the second sealing portion may be formed within a predetermined distance from the left lower corner portion of the perimeter of the cup (P) and within a predetermined distance from the right lower corner portion.

[0015] At this time, the predetermined distance may be 5mm.

[0016] The inner perimeter of the area provided within a predetermined distance from the upper corner portion of the perimeter of the cup (P) among the first sealing portions can be formed as a straight line.

[0017] The inner perimeter of the area provided within a predetermined distance from the upper corner portion of the perimeter of the cup (P) among the first sealing portions may be formed as a curve.

[0018] The inner perimeter of the area provided within a predetermined distance from the upper corner portion of the perimeter of the cup (P) among the first sealing portions may include straight lines and curves.

[0019] The curve can be formed concavely when viewed from the electrode assembly.

[0020] The curve can be formed convexly when viewed from the electrode assembly.

[0021] The pouch-type outer material includes a first region and a second region, and the pouch-type outer material has a folding portion formed at the boundary between the first region and the second region, such that the first region and the second region face each other by folding the first region relative to the second region, and one end portion of the left end portion and the right end portion of the first sealing portion that is adjacent to the folding portion is formed within a predetermined distance from the upper corner portion of the perimeter of the cup (P), and one end portion of the left end portion and the right end portion of the second sealing portion that is adjacent to the folding portion can be formed within a predetermined distance from the lower corner portion of the perimeter of the cup (P).

[0022] At this time, the predetermined distance may be 5mm.

[0023] The sealing portion may further include a third sealing portion formed to connect the first sealing portion and the second sealing portion.

[0024] The upper end of the third sealing part is connected to the first sealing part, and the lower end of the third sealing part can be connected to the second sealing part.

[0025] The third seal can be bent in the thickness (t) direction of the electrode assembly.

[0026] At least one of the upper corner portion and the lower corner portion may be formed in a round shape.

[0027] The first sealing portion may include a normal lead sealing area (S1) formed by sealing a region located above a region within a predetermined distance from the upper corner portion of the perimeter of the cup to cover the first electrode lead by a sealing tool, and an additional sealing area (S2) formed by sealing a region within a predetermined distance from the upper corner portion of the perimeter of the cup by a sealing tool.

[0028] Typically, the sealing thickness may differ between the lead sealing area (S1) and the additional sealing area (S2).

[0029] A method for manufacturing a pouch-type secondary battery according to the present invention comprises the steps of: preparing an electrode assembly having a structure in which electrodes and separators are alternately arranged, and a pouch-type outer material having a cup (P) having an indented shape; receiving the electrode assembly in the cup; folding the outer material so that one area of ​​the outer material and another area of ​​the outer material face each other; arranging a first electrode lead protruding outward through the upper perimeter of the outer material and a second electrode lead protruding outward through the lower perimeter of the outer material; forming a first sealing portion on the outer material to cover the first electrode lead; and forming a second sealing portion on the outer material to cover the second electrode lead; wherein, in the step of forming the first sealing portion, one end of the first sealing portion is sealed so as to be formed within a predetermined distance from the upper corner portion of the perimeter of the cup (P).

[0030] In the step of forming the second sealing portion, one end of the second sealing portion may be sealed so as to be formed within a predetermined distance from the lower corner portion of the perimeter of the cup (P).

[0031] The step of forming the first seal may include a two-step sealing process, a normal lead sealing process and an additional sealing process.

[0032] The conventional lead sealing process is a process of forming a conventional lead sealing area (S1) by sealing an area located above a predetermined distance from the upper corner portion of the perimeter of the cup through a sealing tool so that the first area pouch and the second area pouch cover the first electrode lead, and the additional sealing process may be a process of forming an additional sealing area (S2) by sealing an area within a predetermined distance from the upper corner portion of the perimeter of the cup through a sealing tool so that the first area pouch and the second area pouch are joined to each other.

[0033] The step of forming the first sealing portion may typically involve sealing with different sealing thicknesses for each section of the lead sealing area (S1) and the additional sealing area (S2).

[0034] The method may further include the step of forming a third seal portion that is formed along the perimeter of the electrode assembly and connects the first seal portion and the second seal portion. Effects of the invention

[0035] According to the present invention, the problem of damage to the pouch or cracking occurring in the area adjacent to the sealing portion covering the electrode lead among the folding portions (F) is solved. Brief explanation of the drawing

[0036] FIG. 1 is a plan view illustrating the structure of a pouch-type secondary battery according to the prior art. FIG. 2 is a plan view illustrating the first sealing portion and the second sealing portion formed in a pouch-type secondary battery according to the present invention. Figure 3 is a vertical cross-sectional view showing the appearance of a pouch-type secondary battery when cut along the CC line of Figure 2. FIG. 4 is an enlarged view illustrating the appearance of the first sealing portion of a pouch-type secondary battery according to the first embodiment of the present invention. FIG. 5 is an enlarged view illustrating the appearance of the first sealing portion of a pouch-type secondary battery according to a second embodiment of the present invention. FIG. 6 is an enlarged view illustrating the appearance of the first sealing portion of a pouch-type secondary battery according to the third embodiment of the present invention. FIG. 7 is a plan view illustrating the first to third sealing portions formed in a pouch-type secondary battery according to the present invention. FIG. 8 is a plan view illustrating the formation of a first seal through a normal lead sealing process and an additional sealing process. Specific details for implementing the invention

[0037] Hereinafter, a pouch-type secondary battery, a battery pack, and a method for manufacturing a pouch-type secondary battery according to the present invention will be described with reference to the drawings.

[0039] Pouch-type secondary batteries and battery packs

[0041] FIG. 2 is a plan view illustrating the first sealing portion and the second sealing portion formed in a pouch-type secondary battery according to the present invention. FIG. 3 is a vertical cross-sectional view illustrating the appearance of a pouch-type secondary battery when cut along the CC line of FIG. 2. FIG. 4 is an enlarged view illustrating the appearance of the first sealing portion of a pouch-type secondary battery according to the first embodiment of the present invention. FIG. 5 is an enlarged view illustrating the appearance of the first sealing portion of a pouch-type secondary battery according to the second embodiment of the present invention. FIG. 6 is an enlarged view illustrating the appearance of the first sealing portion of a pouch-type secondary battery according to the third embodiment of the present invention. FIG. 7 is a plan view illustrating the appearance of the first to third sealing portions formed in a pouch-type secondary battery according to the present invention.

[0043] As illustrated in FIGS. 2, 3 and 7, a pouch-type secondary battery (10, hereinafter referred to as 'secondary battery') according to the present invention may include an electrode assembly (100) having a structure in which electrodes and separators are alternately arranged, and a pouch-type outer material (200, hereinafter referred to as 'outer material') having a cup (cup, P) formed with an indented shape to accommodate the electrode assembly (100).

[0044] As illustrated in FIG. 3, the exterior material (200) may include a first region (210) and a second region (220). At this time, the exterior material (200) may have a folding portion (F) formed at the boundary between the first region (210) and the second region (220), and such that the first region (210) and the second region (220) face each other by folding the first region (210) with respect to the second region (220). This can also be interpreted as the second region (220) being folded with respect to the first region (210) at the folding portion (F). Meanwhile, FIG. 3 shows a cup (P) formed in a second region (220) provided at the bottom of the exterior material (200), but alternatively, a cup (P) may be formed in a first region (210) provided at the top, or a cup (P) may be formed in both the first region (210) and the second region (220). FIG. 2 shows a boundary (L) around the cup (P) formed in the exterior material (200) as a dotted line.

[0045] Continuing with reference to FIGS. 2 and FIGS. 7, the secondary battery (10) according to the present invention may further include electrode leads (310, 320) that are electrically connected to the electrode assembly (100) and protrude outward through the circumference of the outer casing (200).

[0046] At this time, the electrode leads (310, 320) may include a first electrode lead (310) that protrudes outward through the upper circumference of the outer casing (200) and a second electrode lead (320) that protrudes outward through the lower circumference of the outer casing (200) and has a polarity different from that of the first electrode lead. That is, in the secondary battery (10) according to the present invention, the first electrode lead (310) and the second electrode lead (320) may protrude in opposite directions from each other (protruding in opposite directions from the first electrode lead and the second electrode lead is merely one embodiment of the present invention and is not limited thereto, and the technical concept of the present invention may also be applied even when the first electrode lead and the second electrode lead protrude in the same direction).

[0047] Meanwhile, according to FIGS. 2 and 7, a sealing portion (400) may be formed along the perimeter of the electrode assembly (100) in the outer material (200). The sealing portion (400) may be formed by the first region (210) and the second region (220) of the outer material (200) being bonded to each other. At this time, the sealing portion (400) may be formed in the outer material (200) that surrounds the perimeter of the electrode assembly (100), excluding the region where the folding portion (F) is formed.

[0048] The sealing portion (400) may include a first sealing portion (410) formed to cover a first electrode lead (310), a second sealing portion (420) formed to cover a second electrode lead (320), and a third sealing portion (430) formed to connect the first sealing portion (410) and the second sealing portion (420). Referring to FIG. 7, the upper end of the third sealing portion (430) may be connected to the first sealing portion (410), and the lower end of the third sealing portion (430) may be connected to the second sealing portion (420). Additionally, the third sealing portion (430) may be formed to face the folding portion (F) with the electrode assembly (100) or the cup (P) in between. Additionally, as described below, the third sealing part (430) may be formed later in time than the first sealing part (410) and the second sealing part (420) (however, the present invention is not limited thereto, and in some cases, when using a single sealing tool, the third sealing part (430) may be formed simultaneously with the first sealing part (410) and the second sealing part (420)).

[0049] Meanwhile, referring to FIGS. 2 and 7, one end of the first sealing portion (410) or one end of the second sealing portion (420) of the pouch-type secondary battery (10) according to the present invention may be formed to face the folding portion (F). Additionally, one end (410-1) of the first sealing portion (410) according to the present invention may be formed in an area within a predetermined distance (R) from the upper corner portion (510) of the perimeter of the cup (P) of the outer material (200), and one end (420-1) of the second sealing portion (420) may be formed in an area within a predetermined distance (R) from the lower corner portion (520) of the perimeter of the cup (P) of the outer material (200). In FIG. 2, it is shown that one end (410-1) of the first sealing part (410) is formed on a virtual circle with radius R centered on the upper corner part (510) of the circumference of the cup (P). The fact that one end (410-1) of the first sealing part (410) is formed within a predetermined distance (R) from the upper corner part (510) of the circumference of the cup (P) of the exterior material (200) may mean that one end (410-1) of the first sealing part (410) is formed within the virtual circle range.

[0050] According to one example of the present invention, as shown in FIGS. 2 and FIGS. 7, both the left end and the right end of the first sealing part (410) may be formed within a predetermined distance (R) from the upper corner part (510) of the circumference of the cup (P), and both the left end and the right end of the second sealing part (420) may also be formed within a predetermined distance (R) from the lower corner part (520) of the circumference of the cup (P).

[0051] Specifically, the left end and the right end of the first sealing portion may be formed within a predetermined distance (R) from the upper left corner of the perimeter of the cup (P) and within a predetermined distance (R) from the upper right corner, respectively. Additionally, the left end and the right end of the second sealing portion may be formed within a predetermined distance (R) from the lower left corner of the perimeter of the cup (P) and within a predetermined distance (R) from the lower right corner. At this time, the predetermined distance (R) may be 5mm. If the predetermined distance (R) is too large, the sealing portion may not reach the area where the pouch cracks, and if the predetermined distance (R) is too small, sealing may have to be performed at an excessive and unnecessary location. Therefore, the predetermined distance (R) may be 5mm.

[0052] However, according to another example of the present invention, only one end portion (i.e., the left end portion based on FIG. 2 and FIG. 7) of the first sealing portion (410) that is adjacent to the folding portion (F) among the left end portion and the right end portion may be formed within a predetermined distance (R) from the upper corner portion (510) of the perimeter of the cup (P), and only one end portion (i.e., the left end portion based on FIG. 2 and FIG. 7) of the second sealing portion (420) that is adjacent to the folding portion (F) among the left end portion and the right end portion may be formed within a predetermined distance (R) from the lower corner portion (520) of the perimeter of the cup (P). In this case as well, the predetermined distance (R) may be 5 mm. If the predetermined distance (R) is too large, the sealing portion may not reach the area where the pouch cracks, and if the predetermined distance (R) is too small, sealing may have to be performed at an excessive and unnecessary location.

[0054] According to the present invention, one end of the first sealing portion (410) covering the first electrode lead (310) and the second electrode lead (320) is formed to extend in the direction of the folding portion (F) so as to enter an area within a predetermined distance (R) from the upper corner portion (510) of the perimeter of the cup (P) compared to the conventional method, or one end of the second sealing portion (420) is formed to extend in the direction of the folding portion (F) so as to enter an area within a predetermined distance (R) from the lower corner portion (520) of the perimeter of the cup (P) compared to the conventional method, thereby preventing the occurrence of cracks in the folding portion or near the folding portion due to stress concentration.

[0055] In particular, according to the present invention, the end portion adjacent to the folding portion among the end portions of the first sealing portion and the second sealing portion is formed to extend in the direction of the folding portion and extend downward or upward, so that the phenomenon of cracking occurring in the area where cracks frequently occurred when manufacturing a pouch-type secondary battery according to the prior art (see reference numeral A in FIG. 1) can be prevented.

[0056] For example, in the process of assembling multiple secondary battery groups to make a battery module or battery pack, there may be cases where the electrode lead bends upward or downward relative to the thickness direction of the secondary battery. In this case, since the area near the sealing portion (A in FIG. 1) formed to cover the electrode lead (20a, 20b) among the folding portion (F) is sealed in the present invention, a sharp folding shape does not occur, thereby preventing pouch cracks caused by stress concentration. That is, if it is not sealed, when the lead bends upward or downward relative to the thickness direction of the secondary battery, a phenomenon in which the pouch in part A folds sharply may occur; however, if it is sealed, even if the lead bends, the pouch sealing portion in part A only bends (i.e., only bends) and does not fold sharply. Accordingly, the occurrence of pouch cracks can be prevented.

[0058] Example 1

[0059] Meanwhile, as illustrated in FIG. 4, according to the first embodiment of the present invention, the inner circumference of the area provided within a predetermined distance (R) from the upper corner portion (510) of the circumference of the cup (P) in the first sealing portion (410) may be formed as a curve. Additionally, according to the first embodiment of the present invention, the inner circumference of the area provided within a predetermined distance (R) from the lower corner portion (520) of the circumference of the cup (P) in the second sealing portion (420) may also be formed as a curve.

[0060] Example 2

[0061] On the other hand, as illustrated in FIG. 5, according to the second embodiment of the present invention, the inner circumference of the area provided within a predetermined distance (R) from the upper corner portion (510) of the circumference of the cup (P) in the first sealing portion (410) may be straight. Additionally, according to the second embodiment of the present invention, the inner circumference of the area provided within a predetermined distance (R) from the lower corner portion (520) of the circumference of the cup (P) in the second sealing portion (420) may also be straight.

[0062] Example 3

[0063] Alternatively, as illustrated in FIG. 6, according to the third embodiment of the present invention, the inner circumference of the area provided within a predetermined distance (R) from the upper corner portion (510) of the circumference of the cup (P) in the first sealing portion (410) may include straight lines and curves. Additionally, according to the third embodiment of the present invention, the inner circumference of the area provided within a predetermined distance (R) from the lower corner portion (520) of the circumference of the cup (P) in the second sealing portion (420) may also include straight lines and curves.

[0064] At this time, according to the first and third embodiments of the present invention, the curve formed on the inner circumference of the first sealing portion (410) and the second sealing portion (420) may be formed concavely when viewed from the electrode assembly (100) (see FIG. 4). However, the curve may also be formed convexly when viewed from the electrode assembly (100) (see FIG. 6). In addition, it may be formed to include both a concave shape and a convex shape.

[0066] Example 4

[0067] According to the fourth embodiment of the present invention, at least one of the upper corner portion (510) and the lower corner portion (520) may be formed in a round shape. Referring to FIG. 8, FIG. 8 illustrates a case where the upper corner portion (510) is formed in a round shape.

[0068] In this case (i.e., when the upper corner portion is formed in a round shape), the fact that one end portion (410-1) of the first sealing portion (410) is formed within a predetermined distance (R) from the upper corner portion (510) of the perimeter of the cup (P) may mean that one end portion (410-1) of the first sealing portion (410) is formed within a virtual arc (Q) range that is separated by a predetermined distance (R) from the round upper corner portion (510). At this time, the predetermined distance (R) may be 5mm.

[0069] This method of interpretation can be applied in the same way even when the lower corner portion (520) is formed in a round shape. In this case as well, a predetermined distance from the lower corner portion (520) may be 5mm.

[0071] Meanwhile, in the secondary battery (10) according to the present invention, the third sealing portion (430) can be bent in the direction of the thickness (t, see FIG. 3) of the electrode assembly (100). In this case, the volume occupied by the third sealing portion (430) can be reduced, so the capacity per unit volume of the secondary battery can be improved.

[0073] Meanwhile, the battery pack according to the present invention may include a plurality of secondary batteries (10). The description of the secondary batteries (10) replaces the description above.

[0075] Method for manufacturing a pouch-type secondary battery

[0077] Referring to FIGS. 2 to 7, a method for manufacturing a pouch-type secondary battery according to the present invention comprises the steps of: preparing an electrode assembly (100) having a structure in which electrodes and separators are alternately arranged, and a pouch-type outer material (200) having a cup (P) having an indented shape; receiving the electrode assembly (100) in the cup (P); folding the outer material (200) so that one region (210) and another region (220) of the outer material (200) face each other; arranging a first electrode lead (310) protruding outward through the upper circumference of the outer material (200) and a second electrode lead (320) protruding outward through the lower circumference of the outer material (200); forming a first sealing portion (410) on the outer material (200) to cover the first electrode lead (310) and forming a second sealing portion on the outer material (200) to cover the second electrode lead (320). It may include a step of forming a seal (420).

[0078] At this time, in the step of forming the first sealing portion (410) and the second sealing portion (420), one end of the first sealing portion (410) may be sealed so as to be formed within a predetermined distance (R) from the upper corner portion (510) of the circumference of the cup (P), and one end of the second sealing portion (420) may be sealed so as to be formed within a predetermined distance (R) from the lower corner portion (520) of the circumference of the cup (P). Here, the predetermined distance (R) may be 5mm.

[0079] And at this time, the one end of the first sealing part (410) may be an end that is adjacent to the folding part (F) among the left end and right end of the first sealing part (410), and the one end of the second sealing part (420) may be an end that is adjacent to the folding part (F) among the left end and right end of the second sealing part (420).

[0080] The process of forming the first sealing portion (410) may more specifically be a two-step sealing process. This two-step sealing may mean a normal lead sealing process and an additional sealing process.

[0081] FIG. 8 is a plan view showing the formation of a first sealing part (410) through a normal lead sealing process and an additional sealing process.

[0082] Referring to FIG. 8, a conventional lead sealing process may mean a process of sealing a first region (210) pouch and a second region (220) pouch through a sealing tool so that the first electrode lead (310) covers an area located above a predetermined distance from the upper corner portion of the perimeter of the cup (P). Through this, a conventional lead sealing area (S1) can be formed.

[0083] The additional sealing process may refer to a process of sealing the first area (210) pouch and the second area (220) pouch together using a sealing tool within a predetermined distance from the upper corner portion of the perimeter of the cup (P). Through this, an additional sealing area (S2) may be formed. Through the additional sealing process, a portion within the inner area of ​​a virtual arc (Q) located at a predetermined distance (R) from the upper corner portion (510) may be sealed. The inner area of ​​the virtual arc (Q) may refer to a pouch area that is closer to the upper corner portion (510) relative to the virtual arc (Q).

[0085] Through this sealing process, the first sealing portion (410) may include a standard lead sealing area (S1) and an additional sealing area (S2).

[0086] Here, the lead sealing area (S1) may be an area formed by sealing the first electrode lead by a sealing tool, wherein the area located above the area within a predetermined distance from the upper corner portion of the perimeter of the cup is sealed.

[0087] The additional sealing area (S2) may be an area formed by sealing the first area (210) pouch and the second area (220) pouch together by means of a sealing tool within a predetermined distance from the upper corner portion of the perimeter of the cup.

[0088] Meanwhile, the method for manufacturing a pouch-type secondary battery according to the present invention may vary the sealing thickness between the standard lead sealing region (S1) and the additional sealing region (S2) during the sealing process. In this case, the pouch-type secondary battery according to the present invention may be a secondary battery having different sealing thicknesses between the standard lead sealing region (S1) and the additional sealing region (S2).

[0089] For example, referring to Fig. 8, the sealing thickness can be different in sections ab and bc. Section ab can have a standard pouch-to-pouch sealing thickness (reference sealing thickness), while section bc can have a sealing thickness that is thicker or thinner than this. Additionally, the sealing thickness can be constant or varied within a single section. That is, the sealing thickness can be constant within a single section ab, but it is not limited to this; it can also be implemented to increase or decrease the sealing thickness within section ab at a constant rate. Furthermore, the sealing thickness can be set to vary irregularly within a single section. The above description can also be applied within a single section bc.

[0090] By applying sealing forms in such diverse ways, an optimal sealing portion can be configured to prevent pouch cracking in accordance with variations in the size, shape, type, material, and thickness of the pouch, thereby enabling the manufacture of an excellent secondary battery that maximizes the pouch crack prevention, which is the unique effect of the present invention, to suit each type of pouch.

[0092] Additionally, referring to FIG. 7, the method for manufacturing a pouch-type secondary battery according to the present invention may further include the step of forming a third sealing part (430) that is formed along the circumference of an electrode assembly (100) and connects a first sealing part (410) and a second sealing part (420). The third sealing part (430) may be formed after the first sealing part (410) and the second sealing part (420) are formed (however, as described above, if a single sealing tool is used, the third sealing part (430) may be formed simultaneously with the first sealing part (410) and the second sealing part (420)). Here, one end of the third sealing part (430) may be connected to the first sealing part (410), and the other end of the third sealing part (430) may be connected to the second sealing part (420).

[0094] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various implementations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs. Explanation of the symbols

[0095] 10 : Secondary battery 100 : Electrode assembly 200 : Exterior materials 210: Zone 1 220 : Second Zone 300 ; Electrode lead 310: First electrode lead 320: Second electrode lead 400 : Sealing part 410: First seal 410-1: One end of the first seal 420 : Second seal 420-1: One end of the second seal (420) 430 : Third seal 510: Upper corner of the rim of the cup 520: Lower corner of the cup's rim P : cup L: The boundary of the cup F : Folding part S1: Standard lead sealing area S2: Additional sealing area Q: A virtual arc located at a predetermined distance from the upper corner

Claims

Claim 1 An electrode assembly having a structure in which electrodes and separators are alternately arranged; a pouch-type outer casing having a cup (P) formed with an indented shape to accommodate the electrode assembly; and an electrode lead electrically connected to the electrode assembly and protruding outward through the perimeter of the outer casing; wherein the outer casing has a seal formed along the perimeter of the electrode assembly, and the electrode lead includes a first electrode lead protruding outward through the upper perimeter of the outer casing; wherein the seal includes a first seal formed to cover the first electrode lead; wherein one end of the first seal is formed in an area within a predetermined distance from the upper corner portion of the perimeter of the cup (P), and the area within a predetermined distance (R) from the upper corner portion (510) of the perimeter of the cup (P) is defined as one of the following a) and b), a) a virtual circle centered on the upper corner portion (510) of the perimeter of the cup (P) and having a radius R; or b) a virtual arc (Q) located at a predetermined distance (R) from the upper corner (510) of the circumference of the cup (P). Claim 2 A pouch-type secondary battery in claim 1, wherein the left end and right end of the first sealing portion are formed within a predetermined distance from the left upper corner portion and within a predetermined distance from the right upper corner portion, respectively, of the perimeter of the cup (P). Claim 3 A pouch-type secondary battery according to claim 1, wherein the electrode lead comprises a second electrode lead protruding outward through the lower circumference of the outer casing; the sealing portion comprises a second sealing portion formed to cover the second electrode lead; and one end of the second sealing portion is formed within a predetermined distance from the lower corner portion of the circumference of the cup (P). Claim 4 In claim 3, the left end and right end of the second sealing portion are formed in an area within a predetermined distance from the left lower corner portion and an area within a predetermined distance from the right lower corner portion of the perimeter of the cup (P), respectively, in a pouch-type secondary battery. Claim 5 A pouch-type secondary battery characterized in that, in any one of claims 1 to 4, the predetermined distance is 5 mm. Claim 6 A pouch-type secondary battery in claim 1, wherein the inner perimeter of the area provided within a predetermined distance from the upper corner portion of the perimeter of the cup (P) among the first sealing portions is a straight line. Claim 7 A pouch-type secondary battery in claim 1, wherein the inner perimeter of the area provided within a predetermined distance from the upper corner portion of the perimeter of the cup (P) among the first sealing portions is formed as a curve. Claim 8 In claim 1, the inner perimeter of the area provided within a predetermined distance from the upper corner portion of the perimeter of the cup (P) among the first sealing portions is a pouch-type secondary battery comprising straight lines and curves. Claim 9 In claim 7 or claim 8, the curve is formed concavely when viewed from the electrode assembly. Claim 10 In claim 7 or claim 8, the curve is formed convexly when viewed from the electrode assembly, a pouch-type secondary battery. Claim 11 In claim 3, the pouch-type outer material comprises a first region and a second region, and the pouch-type outer material has a folding portion formed at the boundary between the first region and the second region, such that the first region and the second region face each other by folding the first region relative to the second region, and one end portion of the left end portion and the right end portion of the first sealing portion that is adjacent to the folding portion is formed within a predetermined distance from the upper corner portion of the perimeter of the cup (P), and one end portion of the left end portion and the right end portion of the second sealing portion that is adjacent to the folding portion is formed within a predetermined distance from the lower corner portion of the perimeter of the cup (P). Claim 12 A pouch-type secondary battery characterized in that, in claim 11, the predetermined distance is 5 mm. Claim 13 A pouch-type secondary battery further comprising, in claim 3, a third sealing portion formed to connect the first sealing portion and the second sealing portion. Claim 14 A pouch-type secondary battery in claim 13, wherein the upper end of the third seal is connected to the first seal and the lower end of the third seal is connected to the second seal. Claim 15 In claim 13, the third seal is a pouch-type secondary battery that is folded in the thickness (t) direction of the electrode assembly. Claim 16 A pouch-type secondary battery according to any one of claims 3, 4 and 11 to 15, wherein at least one of the upper corner portion and the lower corner portion is formed in a round shape. Claim 17 A pouch-type secondary battery according to claim 1, wherein the first sealing portion comprises a normal lead sealing area (S1) formed by sealing a region located above a region within a predetermined distance from the upper corner portion of the perimeter of the cup to cover a first electrode lead by a sealing tool, and an additional sealing area (S2) formed by sealing a region within a predetermined distance from the upper corner portion of the perimeter of the cup by a sealing tool. Claim 18 A pouch-type secondary battery characterized in that, in claim 17, the sealing thickness is different for each section of the normal lead sealing region (S1) and the additional sealing region (S2). Claim 19 A battery pack comprising a secondary battery according to claim 1. Claim 20 A step of preparing an electrode assembly having a structure in which electrodes and separators are alternately arranged, and a pouch-type outer material having a cup (P) having an indented shape; a step of receiving the electrode assembly in the cup; a step of folding the outer material so that one region of the outer material and another region of the outer material face each other; a step of arranging a first electrode lead protruding outward through the upper perimeter of the outer material and a second electrode lead protruding outward through the lower perimeter of the outer material; a step of forming a first sealing portion on the outer material to cover the first electrode lead; and a step of forming a second sealing portion on the outer material to cover the second electrode lead. A method for manufacturing a pouch-type secondary battery comprising, in the step of forming the first sealing portion, wherein one end of the first sealing portion is sealed to be formed within a predetermined distance from the upper corner portion of the perimeter of the cup (P), and the area within a predetermined distance (R) from the upper corner portion (510) of the perimeter of the cup (P) is defined as one of the following a) and b): a) a virtual circle centered on the upper corner portion (510) of the perimeter of the cup (P) and having radius R; or b) a virtual arc (Q) located at a predetermined distance (R) from the upper corner portion (510) of the perimeter of the cup (P). Claim 21 A method for manufacturing a pouch-type secondary battery in claim 20, wherein, in the step of forming the second sealing portion, one end of the second sealing portion is sealed so as to be formed within a predetermined distance from the lower corner portion of the perimeter of the cup (P). Claim 22 A method for manufacturing a pouch-type secondary battery, wherein, in claim 20, the step of forming the first sealing portion comprises a two-step sealing process consisting of a conventional lead sealing process and an additional sealing process. Claim 23 Claim 22, wherein the conventional lead sealing process is a process of forming a conventional lead sealing area (S1) by sealing an area located above a predetermined distance from the upper corner portion of the perimeter of the cup through a sealing tool so that the first area pouch and the second area pouch cover the first electrode lead, and the additional sealing process is a process of forming an additional sealing area (S2) by sealing an area within a predetermined distance from the upper corner portion of the perimeter of the cup through a sealing tool so that the first area pouch and the second area pouch are joined to each other. Claim 24 Claim 23, a method for manufacturing a pouch-type secondary battery, wherein the step of forming the first sealing portion is characterized by sealing with different sealing thicknesses for each section of the normal lead sealing area (S1) and the additional sealing area (S2). Claim 25 A method for manufacturing a pouch-type secondary battery, further comprising the step of forming a third seal portion formed along the circumference of the electrode assembly and connecting the first seal portion and the second seal portion in claim 20.

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