Secondary battery and manufacturing method therefor

Abstract

The present invention relates to a secondary battery and a manufacturing method therefor. A current collecting plate according to the present invention has a predetermined portion of some foil tabs positioned on the upper side of the end in a bending direction, and the predetermined portion corresponds to a range of a blank region. In the foil tabs of which a predetermined portion is positioned on the upper side of the current collecting plate, the predetermined portion and / or a portion positioned on the lower side of the current collecting plate are melted and integrated with, by means of welding, a portion of the current collecting plate. In the present invention, an electrode assembly positioned below the blank region can be prevented from being affected during welding. Therefore, a separator and the like of the electrode assembly are prevented from being damaged during welding.

Description

Secondary battery and its manufacturing method

[0001] The present invention relates to a secondary battery and a method for manufacturing the same, and more particularly, to a secondary battery and a method for manufacturing the same, in which when welding a foil tab and a current collector plate, a predetermined portion of a portion of a foil tab is positioned on the upper side of the current collector plate and welded.

[0002] Recently, with the rapid increase in demand for portable electronic products and the full-scale development of electric vehicles, energy storage batteries, robots, satellites, etc., research on high-performance secondary batteries capable of repeated charging and discharging is actively being conducted.

[0003] Secondary batteries can be classified into can-type secondary batteries, in which the electrode assembly is housed in a metal can, and pouch-type secondary batteries, in which the electrode assembly is housed in a pouch made of an aluminum laminate sheet, depending on the shape of the battery case. Can-type secondary batteries can be classified into cylindrical secondary batteries and square secondary batteries, depending on the shape of the metal can.

[0004] Secondary batteries are connected by welding the foil tabs and collector plates of the electrode assembly. Fig. 1 is a drawing showing welding the foil tabs and collector plates by bending them in the bending direction. Referring to Fig. 1, when welding the foil tab (20) and the collector plate (30), in order to increase the contact area between the foil tab (20) and the collector plate (30), the foil tab (20) is bent in the bending direction (BD), and then the collector plate (30) is placed on the upper side of the foil tab (20) and welded. In this case, the collector plate (30) comes into contact with the upper part of one side of the foil tab (20) rather than the upper end of the foil tab (20), so that stable welding is possible. The welding is performed on the upper side of the collector plate (30) using a laser or ultrasonic welding device (100).

[0005] However, when the foil tab (20) is bent in the bending direction, a blank area (A) is formed between the foil tab (20) located at the outer side in the bending direction and the electrode assembly (10). Since the blank area (A) has a smaller number of overlapping foil tabs (20) than other areas, the layer of the foil tab (20) to be welded becomes thinner than other areas. Therefore, when welding is performed on the upper part of the blank area (A), the heat generated during the welding process may be transferred to the electrode assembly (10), and as a result, a problem may occur in which the separator of the electrode assembly (10) is melted at the lower part of the blank area (A).

[0006] An object of the present invention is to provide a secondary battery and a method for manufacturing the same that can prevent damage to an electrode assembly when welding a foil tab and a current collector plate.

[0007] A secondary battery according to an embodiment of the present invention includes an electrode assembly having an electrode portion, a plurality of foil tabs formed at one end of the electrode portion, and a current collector plate welded on an upper side of the foil tab while the foil tab is bent in a bending direction, and some of the plurality of foil tabs may be welded to the current collector plate at a predetermined portion positioned on an upper side of the current collector plate at an end in the bending direction.

[0008] In a secondary battery according to an embodiment of the present invention, the foil tab in which the predetermined portion is located on the upper side of the current collector plate can be welded so that at least a portion of the predetermined portion and the portion located on the lower side of the current collector plate are melted and become one piece with a portion of the current collector plate.

[0009] In a secondary battery according to an embodiment of the present invention, the range in which the predetermined portion covers the upper side of the current collector plate may correspond to the range of a blank area formed between the foil tab located at the outer side in the bending direction and the electrode portion when the foil tab is bent in the bending direction.

[0010] In a secondary battery according to an embodiment of the present invention, a first welded portion that is welded without including the predetermined portion and a second welded portion that is welded including the predetermined portion may be formed on the current collector plate.

[0011] In a secondary battery according to an embodiment of the present invention, the bending direction end of the current collector plate may be rounded.

[0012] In a secondary battery according to an embodiment of the present invention, the foil tab in which the predetermined portion is located on the upper side of the current collector plate may be longer than other foil tabs.

[0013] In a secondary battery according to an embodiment of the present invention, a folding groove may be formed in the foil tab where the predetermined portion is located on the upper side of the current collector plate.

[0014] In a secondary battery according to an embodiment of the present invention, the predetermined portion may have a thickness that increases toward the top in the height direction.

[0015] In a secondary battery according to an embodiment of the present invention, the foil tabs in which the predetermined portion is located on the upper side of the current collector plate may be 1 to 7 foil tabs located on the outer side in the bending direction.

[0016] In a secondary battery according to an embodiment of the present invention, the predetermined portion may be from a position of 2 / 3 to 4 / 5 of the height of the foil tab based on the electrode portion to the upper end.

[0017] In a secondary battery according to an embodiment of the present invention, the length of the predetermined portion may vary depending on the bending angle at which the foil tab is bent in the bending direction.

[0018] In a secondary battery according to an embodiment of the present invention, the current collector plate may further include a supplementary portion formed to be positioned between the bent foil tab and the current collector plate at an end opposite to the bending direction.

[0019] A method for manufacturing a secondary battery according to an embodiment of the present invention may include a preparation step in which an electrode assembly having an electrode portion and a plurality of foil tabs formed at one end of the electrode portion is prepared, a bending step in which the plurality of foil tabs are bent in a bending direction, a mounting step in which a current collector is mounted on an upper side of the bent foil tab, and a predetermined portion of some of the plurality of foil tabs is positioned on an upper side of the current collector at an end in the bending direction, and a welding step in which the foil tab and the current collector are welded.

[0020] In the welding step of the secondary battery manufacturing method according to an embodiment of the present invention, the foil tab having the predetermined portion located on the upper side of the current collector plate can be formed into one body by melting at least a portion of the predetermined portion and the portion located on the lower side of the current collector plate with a portion of the current collector plate.

[0021] The welding step of the secondary battery manufacturing method according to an embodiment of the present invention may include a first welding step of welding without including the predetermined portion, and a second welding step of welding including the predetermined portion.

[0022] In the fixing step of the secondary battery manufacturing method according to an embodiment of the present invention, the range in which the predetermined portion covers the upper side of the current collector plate may correspond to the range of a blank area formed between the foil tab located at the outer side in the bending direction and the electrode portion when the foil tab is bent in the bending direction.

[0023] In the fixing step of the secondary battery manufacturing method according to an embodiment of the present invention, the predetermined portion may be from a position of 2 / 3 to 4 / 5 of the height of the foil tab based on the electrode portion to the upper end.

[0024] In the fixing step of the secondary battery manufacturing method according to an embodiment of the present invention, the length of the predetermined portion can be determined according to the bending angle at which the foil tab is bent in the bending direction.

[0025] When welding a portion including the predetermined portion in the welding step of the secondary battery manufacturing method according to an embodiment of the present invention, the strength of the welding can be adjusted according to the thickness of the overlapping predetermined portion.

[0026] In the welding step of the secondary battery manufacturing method according to an embodiment of the present invention, welding may be performed on the upper side of the current collector plate.

[0027] A secondary battery and its manufacturing method according to an embodiment of the present invention welds a foil tab and a current collector plate by positioning a predetermined portion of the foil tab on the upper side of the current collector plate. Accordingly, damage to the electrode assembly located below the blank area can be prevented during the welding process.

[0028] Figure 1 is a drawing showing welding by bending the foil tab in the bending direction when welding the foil tab and the collector plate.

[0029] FIG. 2 is a drawing showing a secondary battery according to one embodiment of the present invention.

[0030] FIG. 3 is a drawing showing an exploded view of a secondary battery according to one embodiment of the present invention.

[0031] FIG. 4 is a drawing showing a state in which a current collector plate and a foil tab are welded in a secondary battery according to one embodiment of the present invention.

[0032] FIG. 5 is a conceptual drawing showing that a predetermined portion of a plurality of foil tabs according to one embodiment of the present invention is positioned on the upper side of the current collector at the bending direction end.

[0033] FIG. 6 is a drawing showing a foil tab having a predetermined portion positioned on the upper side of a current collector plate according to one embodiment of the present invention.

[0034] FIG. 7 is a drawing showing a current collector plate with a rounded end in the bending direction according to one embodiment of the present invention.

[0035] Figure 8 is a drawing showing the concept of a bending angle in which a foil tab is bent in the bending direction.

[0036] FIG. 9 is a drawing showing a predetermined area in a foil tab according to one embodiment of the present invention.

[0037] FIG. 10 is a conceptual drawing showing that a predetermined portion of the outermost foil tab in the bending direction according to one embodiment of the present invention is located on the upper side of the current collector plate.

[0038] FIG. 11 is a conceptual drawing showing a current collector plate having a supplementary portion according to one embodiment of the present invention welded to a foil tab.

[0039] Fig. 12 is a drawing showing a weld formed on the upper side of a current collector plate according to one embodiment of the present invention.

[0040] FIG. 13a and FIG. 13b are drawings showing that a first welding portion and a second welding portion are formed on the upper side of a current collector plate according to another embodiment of the present invention.

[0041] Figure 14 is a flowchart showing a method for manufacturing a secondary battery according to one embodiment of the present invention.

[0042] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0043] The terminology used in the present invention is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In the present invention, it should be understood that the terms "comprise" or "have" are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0044] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Please note that, where possible, identical components are represented by identical reference numerals throughout the drawings. Furthermore, detailed descriptions of well-known functions and configurations that may obscure the gist of the present invention will be omitted. For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted.

[0045]

[0046] FIG. 2 is a drawing showing a secondary battery according to one embodiment of the present invention, FIG. 3 is a drawing showing an exploded view of a secondary battery according to one embodiment of the present invention, and FIG. 4 is a drawing showing a state in which a current collector plate and a foil tab are welded in a secondary battery according to one embodiment of the present invention.

[0047] Referring to FIGS. 2 to 4, a secondary battery (1000) according to one embodiment of the present invention includes a case (1100), an electrode assembly (1200), a collector plate (1300), and a cap assembly (1400).

[0048] The case (1100) forms the exterior of the secondary battery (100). The case (1100) may have a space formed therein to accommodate an electrode assembly (1200), and an opening may be formed on one side. In the present embodiment, the case (1100) has a rectangular parallelepiped shape, but is not limited thereto and may be modified in various ways. The case (1100) may be made of a sturdy material capable of protecting the electrode assembly (1200) accommodated therein. For example, the case (1100) may be made of a metal such as aluminum or stainless steel.

[0049] An electrolyte may be accommodated together with the electrode assembly (1200) inside the case (1100). The electrolyte may be composed of a lithium salt such as LiPF6 or LiBF4 in an organic solvent such as EC, PC, DEC, EMC, or DMC. The electrolyte may be liquid, solid, or gel-like.

[0050] The electrode assembly (1200) is housed inside the case (1100). The electrode assembly (1200) includes an electrode portion (1210) and a plurality of foil tabs (1220, 1220a).

[0051] The electrode part (1210) includes a plurality of unit electrode plates (1211, 1212) and a separator (1213). An active material may be applied to the unit electrode plates (1211, 1212). The plurality of unit electrode plates (1211, 1212) may include a first unit electrode plate (1211) in which an active material such as a transition metal oxide is applied to a metal plate such as aluminum, and a second unit electrode plate (1212) in which an active material such as graphite or carbon is applied to a metal plate such as copper or nickel.

[0052] A separator (1213) is positioned between a plurality of unit electrode plates (1211, 1212) to prevent short circuits between the unit electrode plates (1211, 1212). The material of the separator (316) may be polyethylene, polypropylene, or a composite thereof.

[0053] The electrode portion (1210) can be formed by positioning a separator (1213) between first unit electrode plates (1211) and second unit electrode plates (1212) that are alternately arranged. That is, in one embodiment, the electrode portion (1210) is formed by alternately stacking the first unit electrode plate (1211), the separator (1213), the second unit electrode plate (1212), and the separator (1213) in that order. In another embodiment, the electrode portion (1210) can be formed by arranging the first unit electrode plate (1211), the separator (1213), and the second unit electrode plate (1212) in that order and then winding them.

[0054] In this embodiment, the electrode assembly (1200) has one electrode portion (1210), but in other embodiments, the electrode assembly (1200) may have a plurality of electrode portions (1210). The plurality of electrode portions (1210) may be electrically connected to each other.

[0055] A foil tab (1220, 1220a) on which no active material is applied is formed at one end of a plurality of unit electrode plates (1211, 1212). In one embodiment, the unit electrode plates (1211, 1212) and the foil tab (1220, 1220a) may be integrally formed by cutting a predetermined portion from a single metal plate using a laser or the like to leave the unit electrode plates (1211, 1212) and the foil tab (1220, 1220a). The foil tab (1220, 1220a) may be formed in a direction toward the cap assembly (1400).

[0056] The foil tabs (1220) of the first unit electrode plate (1211) overlap each other at a first position, and the foil tabs (1220a) of the second unit electrode plate (1212) overlap each other at a second position. In another embodiment, there may be two or more positions where the foil tabs (1220, 1220a) overlap each other on each of the first unit electrode plate (1211) and the second unit electrode plate (1212). A plurality of foil tabs (1220, 1220a) that overlap at the same position may be joined to each other by ultrasonic welding, laser welding, or the like to facilitate the movement of current.

[0057] The current collector plate (1300) electrically connects the foil tabs (1220, 1220a) and the terminals (1420, 1420a) of the cap assembly (1400). In the present embodiment, the current collector plate (1300) has a plate shape, but is not limited thereto.

[0058] The current collector plate (1300) is welded to the foil tab (1220, 1220a) on the upper side of the foil tab (1220, 1220a). Welding may be performed using a method such as ultrasonic welding or laser welding. When welding the foil tab (1220, 1220a) and the current collector plate (1300), in order to increase the contact area between the foil tab (1220, 1220a) and the current collector plate (1300) and to ensure stable welding, the foil tab (1220, 1220a) is bent in the bending direction, and then the current collector plate (1300) is placed on the upper side of the foil tab (1220, 1220a) and welding is performed. During welding, the current collector plate (1300) may be pressed toward the foil tab (1220, 1220a).

[0059] In this embodiment, the foil tabs (1220, 1220a) joined to each other can be bent in the same bending direction. The foil tab (1220) of the first unit electrode plate (1211) and the foil tab (1220a) of the second unit electrode plate (1212) can be bent in different bending directions.

[0060] The upper surface of the current collector plate (1300) is connected to the terminals (1420, 1420a). The current collector plate (1300) may be provided with a connecting portion (1310) for connection to the terminals (1420, 1420a). In the present embodiment, the connecting portion (1310) is shaped like a rod, but is not limited thereto. In another embodiment, a portion of the current collector plate (1300) may be convexly protruded so that the convex portion is connected to the terminals (1420, 1420a).

[0061] In this embodiment, a predetermined portion of a foil tab (1220, 1220a) is positioned on the upper side of the bending direction end of the current collector plate (1300). Some of the foil tabs (1220, 1220a) having a predetermined portion positioned on the upper side of the current collector plate (1300) can be welded so that at least a portion of the predetermined portion and a portion positioned on the lower side of the current collector plate (1300) are melted and become one with a portion of the current collector plate (1300).

[0062] The cap assembly (1400) seals the opening of the case (1100) in which the electrode assembly (1200) is accommodated. The cap assembly (1400) includes a cap plate (1410) and terminals (1420, 1420a).

[0063] The cap plate (1410) may be a plate shape that covers the opening of the case (1100). The cap plate (1410) may have a shape corresponding to the shape of the opening of the case (1100). The cap plate (1410) may be formed of the same material as the case (1100), and the cap plate (1410) may be fixed to the case (1100) by a method such as laser welding.

[0064] An electrolyte injection port (1411) and a vent hole (1412) may be formed in the cap plate (1410). An electrolyte may be injected into the interior of the case (1100) through the electrolyte injection port (1411). The vent hole (1412) is opened when the internal pressure of the case (1100) exceeds a reference value. In the present embodiment, the vent hole (1412) is formed in the cap plate (1410), but in other embodiments, the vent hole (1412) may be formed in the case (1100).

[0065] The terminals (1420, 1420a) may be formed to protrude from the cap plate (1410). The terminals (1420, 1420a) are electrically connected to the foil tabs (1220, 1220a) through the current collector plate (1300). The terminals (1420, 1420a) may be formed in the shape of a circular or rectangular plate.

[0066] A terminal hole (1421, 1421a) may be formed in the terminal (1420, 1420a). A connecting portion (1310) is inserted into the terminal hole (1421, 1421a).

[0067] An insulating member (1430, 1430a) may be positioned between the terminal (1420, 1420a) and the cap plate (1410). The insulating member (1430, 1430a) insulates the terminal (1420, 1420a) and the cap plate (1410) from each other.

[0068]

[0069] FIG. 5 is a drawing conceptually showing that a predetermined portion of a plurality of foil tabs according to one embodiment of the present invention is positioned above a collector plate at an end in a bending direction, FIG. 6 is a drawing showing a foil tab according to one embodiment of the present invention in which a predetermined portion is positioned above a collector plate, FIG. 7 is a drawing showing a collector plate having a rounded end in a bending direction according to one embodiment of the present invention, FIG. 8 is a drawing showing the concept of a bending angle at which a foil tab is bent in a bending direction, and FIG. 9 is a drawing showing a predetermined area in a foil tab according to one embodiment of the present invention.

[0070] Referring to FIGS. 5 to 9, some of the plurality of foil tabs (1220) have a predetermined portion (S) positioned on the upper side of the current collector plate (1300) at the end in the bending direction (BD). At this time, the range in which the predetermined portion (S) covers the upper side of the current collector plate (1300) may correspond to the range of a blank area formed between the foil tab (1220) and the electrode portion (1210) positioned on the outer side in the bending direction (BD) when the foil tab (1220) is bent in the bending direction (BD). Corresponding to the range of the blank area means that the blank area does not extend beyond the predetermined portion when viewed from above.

[0071] The foil tab (1220) is welded to the collector plate (1300) with the predetermined portion (S) positioned on the upper side of the collector plate (1300). The welding can be performed along the bending direction (BD) from the upper side of the collector plate (1300) using a welding device. In this case, since the predetermined portion (S) is positioned on the upper side of the blank area, there is the same effect as when the predetermined portion (S) fills the blank area. Accordingly, overwelding does not occur even if the welding strength is the same as when welding a part other than the blank area. Therefore, the problem of the separator of the electrode part (1210) melting and being damaged at the lower side of the blank area does not occur. The welding strength can be adjusted by adjusting the output of the welding device.

[0072] In this embodiment, in order to position a predetermined portion (S) of the foil tab (1220) on the upper side of the current collector plate (1300), the predetermined portion (S) of the foil tab (1220) may be folded and raised toward the upper side of the current collector plate (1300). In another embodiment, the predetermined portion (S) of the foil tab (1220) may be rolled into a circle and raised toward the upper side of the current collector plate (1300).

[0073] In order to smoothly position a predetermined portion (S) of the foil tab (1220) on the upper side of the current collector plate (1300), referring to FIG. 6, a folding groove (1221, 1222) may be formed in the foil tab (1220). By forming the folding groove (1221, 1222), it becomes easy to fold or roll up the predetermined portion (S) of the foil tab (1220).

[0074] In this embodiment, two fold grooves (1221, 1222) can be formed vertically. This is because the foil tab (1220) that positions a predetermined portion (S) on the upper side of the current collector plate (1300) contacts two corners of the current collector plate (1300). The upper side of the fold groove (1221) located at the top becomes the predetermined portion (S) located on the upper side of the current collector plate (1300).

[0075] When a predetermined portion of the foil tab (1220) is positioned on the upper side of the current collector plate (1300), a portion of the foil tab (1220) comes into contact with the bending end of the current collector plate (1300). In this case, in order to prevent a portion of the foil tab (1220) from being damaged by the corner portion of the current collector plate (1300), referring to FIG. 7, the bending end of the current collector plate (1300) may be rounded.

[0076] In this embodiment, the number of foil tabs (1220) positioned on the upper side of the current collector plate (1300) is three, but the number of foil tabs (1220) positioned on the upper side of the current collector plate (1300) may vary depending on the bending angle (θ) at which the foil tabs (1220) are bent in the bending direction (BD). Referring to FIG. 8, the bending angle (θ) is the angle that the foil tabs (1220) form with a plane perpendicular to the upper surface of the electrode portion (1210) when the foil tabs (1220) are bent in the bending direction (BD). If the bending angle (θ) is large, the number of foil tabs (1220) positioned on the upper side of the current collector plate (1300) may increase, and if the bending angle (θ) is small, the number of foil tabs (1220) positioned on the upper side of the current collector plate (1300) may decrease. If the bending angle (θ) is small, there is a problem that the area of ​​the foil tab (1220) in contact with the collector plate (1300) becomes small, and if the bending angle (θ) is too large, the collector plate (1300) and the electrode assembly (1200) become too close, and there is a problem that the welding heat is transferred to the electrode assembly (1200). Therefore, in the present embodiment, the bending angle (θ) can be set so that the number of foil tabs (1220) located on the upper side of the collector plate (1300) is 1 to 7, but is not limited thereto.

[0077] In addition, in the present embodiment, the foil tab (1220) positioned on the upper side of the current collector plate (1300) may be formed to have a longer length than other foil tabs (1220). The longer the length of the foil tab (1220), the more smoothly a predetermined portion (S) of the foil tab (1220) can be positioned on the upper side of the current collector plate (1300). In one embodiment, the length of the foil tab (1220) may vary depending on the bending angle (θ). When the bending angle (θ) is large, the length of the foil tab (1220) is lengthened, and when the bending angle (θ) is small, the length of the foil tab (1220) is shortened.

[0078] The predetermined portion (S) located on the upper side of the current collector (1300) in the foil tab (1220) is, with reference to FIG. 9, the upper portion of the foil tab (1220). Here, the upper portion means the end of the foil tab (1220) in a direction in which it is not connected to the electrode portion (1210), which is the end in the height direction of the foil tab (1220). In the present embodiment, the predetermined portion (S) may be from a position of 2 / 3 to 4 / 5 of the height of the foil tab (1220) based on the electrode portion (1210) to the upper end of the foil tab (1220). That is, the relationship between the length (Ls) of the predetermined portion (S) and the total length (L) of the foil tab (1220) is L / 5≤Ls≤L / 3. When in this relationship, a predetermined portion (S) of the foil tab (1220) can be stably positioned on the upper side of the current collector plate (1300).

[0079] The length of the predetermined portion (S) may vary depending on the bending angle (θ). If the bending angle (θ) is large, the length occupied by the predetermined portion (S) in the foil tab (1200) becomes longer, and if the bending angle (θ) is small, the length occupied by the predetermined portion (S) in the foil tab (1220) becomes shorter. In addition, the length of the predetermined portion (S) becomes longer as the foil tab (1220) is positioned further outward in the bending direction (BD).

[0080] The thickness of the predetermined portion (S) may become thicker as it goes up in the height direction, as illustrated in FIG. 9. Since the thickness of the foil tab (1220) overlapped in the opposite direction of the bending direction (BD) on the upper side of the current collector plate (1300) becomes thinner, overwelding may occur in this portion during welding. Therefore, if the thickness of the predetermined portion (S) becomes thicker as it goes up in the height direction, it is possible to compensate for the thinning of the foil tab (1220) overlapped in the opposite direction of the bending direction (BD) on the upper side of the current collector plate (1300).

[0081]

[0082] FIG. 10 is a conceptual drawing showing that a predetermined portion of the outermost foil tab in the bending direction according to one embodiment of the present invention is located on the upper side of the current collector plate.

[0083] Referring to FIG. 10, in the present embodiment, only a predetermined portion (S) of the outermost foil tab (1220-1) in the bending direction (BD) among the plurality of foil tabs (1220) is positioned on the upper side of the current collector plate (1300). At this time, the range in which the predetermined portion (S) covers the upper side of the current collector plate (1300) corresponds to the range of the blank area.

[0084] In this embodiment, the length of the outermost foil tab (1220-1) may be formed longer than the other foil tabs (1220). In one embodiment, the length of the outermost foil tab (1220-1) may vary depending on the bending angle (θ). As the bending angle (θ) increases, the length of the outermost foil tab (1220-1) becomes longer so that a predetermined portion (S) of the outermost foil tab (1220-1) can correspond to the range of the blank area.

[0085] The fewer the number of foil tabs positioned on the upper side of the current collector plate (1300), the easier the work becomes. Therefore, by adjusting the length of the outermost foil tab (1220-1) so that only a certain portion of the outermost foil tab (1220-1) is positioned on the upper side of the current collector plate (1300), the manufacturing efficiency can be increased.

[0086]

[0087] FIG. 11 is a conceptual drawing showing a current collector plate having a supplementary portion according to one embodiment of the present invention welded to a foil tab.

[0088] Referring to FIG. 11, a current collector plate (1300) according to one embodiment of the present invention may have a supplementary portion (1320) formed at an end opposite to the bending direction (BD). That is, the supplementary portion (1320) is positioned to face a predetermined portion (S) of the foil tab (1220) with respect to the current collector plate (1300). The supplementary portion (1340) is positioned on the upper portion of the foil tab (1220) located at the outer edge opposite to the bending direction (BD) from the lower side of the current collector plate (1300) when the foil tab (1220) is bent in the bending direction (BD). Therefore, the supplementary portion (1340) fills the space formed between the current collector plate (1300) and the foil tab (1220) as the foil tab (1220) is bent in the bending direction (BD). By providing a supplementary part (1320), when the foil tab (1220) and the current collector plate (1300) are welded to each other, overwelding is prevented without adjusting the welding strength.

[0089] The supplementary portion (1340) may be formed in various shapes. For example, the supplementary portion (1340) may be formed in a shape in which the end of the current collector plate (1300) is bent. In another embodiment, the supplementary portion (1340) may be formed in a protrusion shape protruding from the lower side of the current collector plate (1300).

[0090] The size of the supplementary portion (1340) may vary depending on the gap between the collector plate (1300) and the bent foil tab (1220). In addition, the supplementary portion (1340) may have a lower height relative to the bottom surface of the collector plate (1300) as it goes in the bending direction (BD).

[0091]

[0092] FIG. 12 is a drawing showing that a welded portion is formed on the upper side of a current collector plate according to one embodiment of the present invention, and FIGS. 13a and 13b are drawings showing that a first welded portion and a second welded portion are formed on the upper side of a current collector plate according to another embodiment of the present invention.

[0093] Referring to FIG. 12, the foil tab (1220) and the current collector plate (1300) can be welded to each other while a predetermined portion (S) of the foil tab (1220) is positioned on the upper side of the current collector plate (1300). The welding can be performed using a laser welding device or an ultrasonic welding device (100), etc. The welding method can be line welding that is performed along the bending direction (BD). In the present embodiment, the welding can be performed on the upper side of the current collector plate (1300).

[0094] In this embodiment, an area that does not include a predetermined portion (S) and an area that includes a predetermined portion (S) can be welded in a single line so that a welded portion (1500) is formed in a single continuous line on the current collector plate (1300). In this embodiment, three welded portions (1500) are formed, but this is not limited thereto.

[0095] In another embodiment, referring to FIGS. 13a and 13b, welding of an area not including the predetermined portion (S) and welding of an area including the predetermined portion (S) can be performed separately. Accordingly, a first welded portion (1500-1) that is welded not including the predetermined portion (S) and a second welded portion (1500-2) that is welded including the predetermined portion (S) are formed on the current collector plate (1300). In this case, welding of an area not including the predetermined portion (S) can be performed first, and subsequently welding of an area including the predetermined portion (S) can be performed. In another embodiment, the welding order can be changed.

[0096] The first weld (1500-1) and the second weld (1500-2) may be formed to be positioned on the same line, as illustrated in FIG. 13a. In another embodiment, referring to FIG. 13b, the first weld (1500-1) and the second weld (1500-2) may be formed at staggered positions.

[0097] In this embodiment, when welding the current collector (1300) and the foil tab (1220), the welding strength can be adjusted differently depending on the thickness of the predetermined portion (S). In addition, the welding strength can be adjusted differently when welding an area that does not include the predetermined portion (S) and when welding an area that includes the predetermined portion (S). By adjusting the welding strength, damage to the electrode assembly (1200) can be prevented during welding.

[0098]

[0099] Figure 14 is a drawing showing a method for manufacturing a secondary battery according to one embodiment of the present invention.

[0100] Referring to FIG. 14, a method for manufacturing a secondary battery according to one embodiment of the present invention includes a preparation step (S2100), a bending step (S2200), a settling step (S2300), and a welding step (S2400).

[0101] In the preparation step (S2100), an electrode assembly is prepared. The electrode assembly includes an electrode portion and a plurality of foil tabs formed at one end of the electrode portion. The electrode portion includes a plurality of unit electrode plates coated with an active material, and a separator that prevents short circuits between the plurality of unit electrode plates. The foil tabs are formed at one end of the plurality of unit electrode plates and are not coated with an active material.

[0102] The electrode portion may be formed by positioning a separator between alternately arranged unit electrode plates. In one embodiment, the electrode portion is formed by alternately stacking unit electrode plates, separators, and unit electrode plates in that order. In another embodiment, the electrode portion may be formed by sequentially arranging unit electrode plates, separators, and unit electrode plates and then winding them.

[0103] In the bending step (S2200), multiple foil tabs are bent in the bending direction. This allows the foil tabs and the collector plate to contact a wide area during welding, enabling stable welding.

[0104] In the settling step (S2300), the current collector plate is set on the upper side of the bent foil tab. A predetermined portion of a portion of the plurality of foil tabs is positioned on the upper side of the current collector plate at the bending direction end. In this embodiment, the range over which the predetermined portion covers the upper side of the current collector plate may correspond to the range of the blank area.

[0105] The foil tabs positioned on the upper side of the current collector plate may be one to seven foil tabs positioned on the outer side in the bending direction. The predetermined portion positioned on the upper side of the current collector plate may be from a position of 2 / 3 to 4 / 5 of the height of the foil tabs based on the electrode portion to the top. The length of the predetermined portion may vary depending on the bending angle at which the foil tabs are bent in the bending direction.

[0106] In the welding step (S2400), the foil tab and the collector plate are welded. Welding is performed using a welding device. In the present invention, methods such as laser welding and ultrasonic welding can be applied. When welding is performed, the foil tab, where a predetermined portion is located on the upper side of the collector plate, can be formed into a single body by melting at least a portion of the predetermined portion and the portion located on the lower side of the collector plate with a portion of the collector plate.

[0107] In one embodiment, when welding a portion including a predetermined portion in the welding step (S2400), the welding strength can be adjusted according to the overlapping thickness of the predetermined portion. In this embodiment, since the predetermined portion is located above the blank area, the difference in the thickness of the foil tab overlapping with other areas can be compensated for. In this case, if there is no difference in the thickness of the overlapping foil tab between the blank area and other areas due to the predetermined portion, the problem of overwelding does not occur even if the blank area is welded with the same strength as other areas. In another embodiment, if there is a difference in the thickness of the foil tab overlapping with other areas even after considering the overlapping thickness of the predetermined portion, the welding strength is lowered when welding the predetermined portion to prevent overwelding.

[0108] In this embodiment, the welding step (S2400) may include a first welding step for welding without including a predetermined portion, and a second welding step for welding including the predetermined portion. That is, in this embodiment, welding of an area not including a predetermined portion and welding of an area including a predetermined portion may be performed separately. Accordingly, a first welded portion that is welded without including a predetermined portion and a second welded portion that is welded including a predetermined portion are formed on the current collector plate.

[0109] In one embodiment, the first welding step may be performed first, followed by the second welding step. In another embodiment, the second welding step may be performed first, followed by the first welding step. The first and second welding steps may be performed on the same line, but this is not limited thereto, and the first and second welding steps may be performed on different lines.

[0110]

[0111] Above, one embodiment of the present invention has been described, but a person having ordinary skill in the art will be able to modify and change the present invention in various ways by adding, changing, deleting or adding components, etc., within the scope that does not depart from the spirit of the present invention described in the claims, and this will also be considered to be included within the scope of the rights of the present invention.

Claims

1. An electrode assembly having an electrode part and a plurality of foil tabs formed at one end of the electrode part; and The above foil tab includes a current collector plate welded on the upper side of the above foil tab while the above foil tab is bent in the bending direction, A secondary battery, wherein some of the plurality of foil tabs are welded to the collector plate so that a predetermined portion thereof is positioned on the upper side of the collector plate at the bending direction end.

2. In paragraph 1, A secondary battery in which the foil tab, which is located on the upper side of the current collector plate, is formed by welding such that at least a portion of the predetermined portion and a portion located on the lower side of the current collector plate are melted and become one with a portion of the current collector plate.

3. In paragraph 1, A secondary battery in which the above-mentioned predetermined portion covers the upper side of the current collector plate, wherein the range corresponds to the range of a blank area formed between the foil tab located at the outer side in the bending direction and the electrode portion when the foil tab is bent in the bending direction.

4. In paragraph 1, On the above collector plate A secondary battery, wherein a first welded portion is formed without including the above-mentioned predetermined portion, and a second welded portion is formed including the above-mentioned predetermined portion.

5. In paragraph 1, The above-mentioned current collector plate is a secondary battery having a rounded end in the bending direction.

6. In paragraph 1, A secondary battery, wherein the foil tab located on the upper side of the current collector plate has a longer length than other foil tabs.

7. In paragraph 1, A secondary battery, wherein a folding groove is formed in the foil tab located on the upper side of the above-mentioned collector plate.

8. In paragraph 1, A secondary battery in which the above-mentioned portion becomes thicker towards the top in the height direction.

9. In paragraph 1, A secondary battery, wherein the foil tabs located on the upper side of the current collector plate are 1 to 7 foil tabs located on the outer side in the bending direction.

10. In paragraph 1, A secondary battery, wherein the above-mentioned portion is from a position of 2 / 3 to 4 / 5 of the height of the foil tab based on the electrode portion to the top.

11. In paragraph 1, A secondary battery, wherein the length of the above-mentioned predetermined portion varies depending on the bending angle at which the foil tab is bent in the bending direction.

12. In paragraph 1, The above collector plate A secondary battery further comprising a supplementary portion formed between the bent foil tab and the current collector plate at an end opposite to the bending direction.

13. A preparatory step in which an electrode assembly having an electrode part and a plurality of foil tabs formed on one end of the electrode part is prepared; A bending step in which the plurality of foil tabs are bent in the bending direction; A mounting step in which a current collector plate is mounted on the upper side of the bent foil tab, and some of the plurality of foil tabs have a predetermined portion positioned on the upper side of the current collector plate at the bending direction end; and A method for manufacturing a secondary battery, comprising a welding step in which the foil tab and the current collector plate are welded.

14. In paragraph 13, In the above welding step A method for manufacturing a secondary battery, wherein the foil tab, which has the predetermined portion located on the upper side of the current collector plate, is formed by melting at least a portion of the predetermined portion and a portion located on the lower side of the current collector plate to become one with a portion of the current collector plate.

15. In paragraph 13, The above welding step A method for manufacturing a secondary battery, comprising a first welding step of welding without including the above-mentioned predetermined portion, and a second welding step of welding including the above-mentioned predetermined portion.

16. In paragraph 13, In the above settling stage A method for manufacturing a secondary battery, wherein the range of the above-mentioned predetermined portion covering the upper side of the current collector corresponds to the range of a blank area formed between the foil tab located at the outer side in the bending direction and the electrode portion when the foil tab is bent in the bending direction.

17. In paragraph 13, In the above settling stage A method for manufacturing a secondary battery, wherein the above-mentioned predetermined portion is from a position of 2 / 3 to 4 / 5 of the height of the foil tab based on the electrode portion to the upper end.

18. In paragraph 13, In the above settling stage A method for manufacturing a secondary battery, wherein the length of the above-mentioned predetermined portion is determined according to the bending angle at which the foil tab is bent in the bending direction.

19. In paragraph 13, In the above welding step A secondary battery manufacturing method in which, when welding a portion including the above-mentioned predetermined portion, the strength of the welding is adjusted according to the thickness of the overlapping of the above-mentioned predetermined portion.

20. In paragraph 13, In the above welding step A method for manufacturing a secondary battery, wherein welding is performed on the upper side of the above-mentioned current collector plate.

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