Secondary battery and manufacturing method thereof

Abstract

The present invention relates to a secondary battery and a manufacturing method thereof. A current collector plate according to the present invention includes a main body part and an accommodation part formed at an end of the main body part in a bending direction. A predetermined portion of a foil tab is welded to the current collector plate while accommodated in the accommodation part, and the predetermined portion of the foil tab is melted and integrated with a portion of the main body part and at least a portion of the accommodation part by welding. According to the present invention, it is possible to prevent an electrode assembly located below a blank area from being affected during a welding process. Therefore, it is possible to prevent a separator of the electrode assembly from being damaged during the welding process.

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 received in a receiving portion of the current collector plate.

[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, 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. A laser or ultrasonic welding device (100) is used for welding.

[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 and a plurality of foil tabs formed at one end of the electrode portion, a main body portion welded on an upper side of the foil tabs while the plurality of foil tabs are bent in a bending direction, and a current collector plate having a receiving portion formed at an end of the main body portion in the bending direction to receive a predetermined portion of some of the plurality of foil tabs, wherein the predetermined portion of the foil tab can be welded to the current collector plate while being received in the receiving portion.

[0008] In a secondary battery according to an embodiment of the present invention, a predetermined portion of the foil tab can be melted and integrated with a portion of the main body and at least a portion of the receiving portion by welding.

[0009] In a secondary battery according to an embodiment of the present invention, the receiving portion can be formed by bending an end of the main body portion in a bending direction.

[0010] In a secondary battery according to an embodiment of the present invention, the receiving portion can be bent at a certain angle in a direction opposite to the bending direction.

[0011] In a secondary battery according to an embodiment of the present invention, the receiving portion may have a first bend portion bent at a first angle and a second bend portion bent in a direction opposite to the bending direction.

[0012] In a secondary battery according to an embodiment of the present invention, the receiving portion may be located in a blank area between the outermost foil tab and the electrode portion in the bending direction when the foil tab is bent in the bending direction.

[0013] In the secondary battery according to an embodiment of the present invention, the blank area is divided into N areas according to the number of foil tabs located at the lower portion of the main body, and the thickness of the receiving portion in the blank area may be the same in the same area and may be different thicknesses in different areas.

[0014] In a secondary battery according to an embodiment of the present invention, the thickness of the receiving portion may be thicker as the number of foil tabs located at the lower portion of the main body portion decreases.

[0015] In a secondary battery according to an embodiment of the present invention, some of the foil tabs accommodated in the receiving portion may be 2 to 7 foil tabs positioned 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 1 / 5 to 2 / 3 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 thickness of the receiving portion may become thinner toward the end.

[0019] In a secondary battery according to an embodiment of the present invention, the current collector plate may further include a supplementary part formed to be positioned between the bent foil tab and the main body at an end opposite to the bending direction.

[0020] 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 main body portion and a current collector plate having a receiving portion formed at an end of the main body portion in the bending direction are mounted on an upper side of the bent foil tabs, and a predetermined portion of some of the plurality of foil tabs is received in the receiving portion, and a welding step in which the foil tabs and the current collector plate are welded in a state in which the predetermined portion of the foil tab is received in the receiving portion.

[0021] In a method for manufacturing a secondary battery according to an embodiment of the present invention, a predetermined portion of the foil tab can be melted and integrated with a portion of the main body and at least a portion of the receiving portion in the welding step.

[0022] In the secondary battery manufacturing method according to an embodiment of the present invention, welding can be performed on the upper side of the main body in the welding step.

[0023] In a secondary battery manufacturing method according to an embodiment of the present invention, the length of the foil tab accommodated in the accommodation portion in the settling step may vary depending on the bending angle at which the foil tab is bent in the bending direction.

[0024] In the secondary battery manufacturing method according to an embodiment of the present invention, in the settling step, the receiving portion may be located in a blank area between the outermost foil tab and the electrode portion in the bending direction.

[0025] The secondary battery manufacturing method according to an embodiment of the present invention can adjust the output of the welding device according to the thickness of the receiving portion when welding the upper portion of the blank area in the welding step.

[0026] In a secondary battery manufacturing method according to an embodiment of the present invention, the receiving portion can be formed by bending an end of the main body portion in a bending direction.

[0027] A secondary battery and its manufacturing method according to an embodiment of the present invention comprises a method in which a receiving portion of a current collector plate is positioned in a blank area, and a predetermined portion of a foil tab is received within the receiving portion while welding the current collector plate and the foil tab. Accordingly, damage to the electrode assembly 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 drawing showing a current collector plate in a secondary battery according to one embodiment of the present invention.

[0033] FIG. 6 is a drawing showing a foil tab being accommodated in a receiving portion of a current collector plate during welding in a secondary battery according to one embodiment of the present invention.

[0034] Figure 7 is a drawing showing the concept of a bending angle in which a foil tab is bent in the bending direction.

[0035] FIG. 8 is a drawing showing the range of a predetermined portion in a foil tab according to one embodiment of the present invention.

[0036] FIG. 9 is a conceptual diagram showing that a blank area according to another embodiment of the present invention is divided into N areas and the thickness of the receiving portion changes stepwise for each area.

[0037] FIG. 10 is a drawing conceptually illustrating that the thickness of a receiving portion gradually changes according to another embodiment of the present invention.

[0038] FIGS. 11A to 11E are drawings showing various modified examples of a receiving portion according to one embodiment of the present invention.

[0039] FIG. 12 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.

[0040] Figure 13 is a flowchart showing a method for manufacturing a secondary battery according to one embodiment of the present invention.

[0041] 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.

[0042] 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.

[0043] 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.

[0044]

[0045] FIG. 2 is a drawing showing a secondary battery according to one embodiment of the present invention, FIG. 3 is an exploded drawing showing a secondary battery according to one embodiment of the present invention, 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, and FIG. 5 is a drawing showing a current collector plate in a secondary battery according to one embodiment of the present invention.

[0046] Referring to FIGS. 2 to 5, 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).

[0047] The case (1100) forms the exterior of the secondary battery (1000). The case (1100) may have a space formed therein to accommodate an electrode assembly (1200), and an opening 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.

[0048] 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.

[0049] 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).

[0050] 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.

[0051] 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 (1213) may be polyethylene, polypropylene, or a composite thereof.

[0052] 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.

[0053] 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.

[0054] 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 away from the electrode portion (1210). In the present embodiment, the foil tab (1220, 1220a) may be formed in a direction toward the cap assembly (1400).

[0055] 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.

[0056] The current collector plate (1300) electrically connects the foil tabs (1220, 1220a) and the terminals (1420, 1420a) of the cap assembly (1400). Referring to FIG. 5, the current collector plate (1300) has a main body (1310) and a receiving portion (1320). In the present embodiment, the main body (1310) has a plate shape, but is not limited thereto.

[0057] The main body (1310) of the current collector (1300) is welded to the foil tabs (1220, 1220a) on the upper side thereof. The welding can be performed by a method such as ultrasonic welding or laser welding. When welding the foil tabs (1220, 1220a) and the main body (1310), in order to increase the contact area between the foil tabs (1220, 1220a) and the main body (1310) and to ensure stable welding, the foil tabs (1220, 1220a) are bent in the bending direction (BD), and then the main body (1310) is placed on the upper side of the foil tabs (1220, 1220a) and welding is performed. The welding can be performed by pressing the main body (1310) toward the foil tabs (1220, 1220a).

[0058] In this embodiment, the foil tabs (1220, 1220a) joined to each other can be bent in the same bending direction (BD). 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 (BD).

[0059] 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 (1330) for connection to the terminals (1420, 1420a). In the present embodiment, the connecting portion (1330) 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).

[0060] A receiving portion (1320) is formed at the end of the current collector plate (1300). A predetermined portion of a foil tab (1220, 1220a) is received in the receiving portion (1320). A predetermined portion of the foil tab (1220, 1220a) is welded to the current collector plate (1300) while being received in the receiving portion (1320).

[0061] 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).

[0062] 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.

[0063] 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).

[0064] 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.

[0065] A terminal hole (1421, 1421a) may be formed in the terminal (1420, 1420a). A connecting portion (1330) is inserted into the terminal hole (1421, 1421a).

[0066] 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.

[0067]

[0068] FIG. 6 is a drawing showing a foil tab being received in a receiving portion of a current collector plate during welding in a secondary battery according to one embodiment of the present invention, FIG. 7 is a drawing showing the concept of a bending angle at which a foil tab is bent in a bending direction, and FIG. 8 is a drawing showing a range of a predetermined portion in a foil tab according to one embodiment of the present invention.

[0069] Referring to FIGS. 6 to 8, a current collector (1300) according to one embodiment of the present invention has a receiving portion (1320) formed at an end in the bending direction (BD) of the main body (1310). The receiving portion (1320) is positioned in a blank area formed between the foil tab (1220) and the electrode portion (1210) located at the outer side in the bending direction (BD) when the foil tab (1220) is bent in the bending direction (BD).

[0070] The receiving portion (1320) receives a predetermined portion of some of the foil tabs (1220) positioned at the outer edge in the bending direction (BD) among the plurality of foil tabs (1220). In the present embodiment, three foil tabs (1220) are received in the receiving portion (1320), but the number of foil tabs (1220) received in the receiving portion (1320) may vary depending on the bending angle (θ) at which the foil tabs (1220) are bent in the bending direction (BD). Referring to FIG. 7, the bending angle (θ) is the angle formed by the foil tabs (1220) 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). When the bending angle (θ) is large, the number of foil tabs (1220) accommodated in the receiving portion (1320) increases, and when the bending angle (θ) is small, the number of foil tabs (1220) decreases.

[0071] 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, causing a problem that welding heat is transferred to the electrode assembly (1200). Therefore, it is preferable to set the bending angle (θ) so that the number of foil tabs (1220) accommodated in the receiving portion (1320) is 2 to 7.

[0072] The predetermined portion of each foil tab (1220) accommodated in the receiving portion (1320) is, with reference to FIG. 8, 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). In the present embodiment, the predetermined portion of the foil tab (1220) accommodated in the receiving portion (1320) may be from a position of 1 / 5 to 2 / 3 of the height of the foil tab (1220) from the electrode portion (1210) in the height direction of the foil tab (1220) to the upper portion. That is, the relationship between the length (Ls) of the predetermined portion and the total length (L) of the foil tab (1220) is L / 3≤Ls≤4L / 5. When such a relationship exists, the predetermined portion of the foil tab (1220) can be stably accommodated in the receiving portion (1320).

[0073] A predetermined portion of the foil tab (1220) accommodated in the receiving portion (1320) varies depending on the bending angle (θ) at which the foil tab (1220) is bent in the bending direction (BD). If the bending angle (θ) is large, the length of the accommodated foil tab (1220) becomes longer, and if the bending angle (θ) is small, the length of the foil tab (1220) becomes shorter. In addition, the length of the predetermined portion becomes longer as the foil tab (1220) is positioned further outward in the bending direction (BD).

[0074] With a predetermined portion of the foil tab (1220) accommodated within the receiving portion (1320), the foil tab (1220) and the collector plate (1300) are welded to each other. The welding is performed along the bending direction (BD) from the upper portion of the collector plate (1300) using a welding device. In this case, since the receiving portion (1320) fills the empty area, overwelding does not occur even if the output of the welding device is the same. Accordingly, the problem of the separator of the electrode portion (1210) melting does not occur at the lower portion of the empty area. By welding, a predetermined portion of the foil tab (1220) is melted and integrated with a portion of the main body portion (1310) and at least a portion of the receiving portion (1320).

[0075]

[0076] FIG. 9 is a drawing conceptually showing that a blank area according to one embodiment of the present invention is divided into N areas and the thickness of the receiving portion changes stepwise for each area, and FIG. 10 is a drawing conceptually showing that the thickness of the receiving portion gradually changes according to another embodiment of the present invention.

[0077] Referring to FIG. 9, the blank area can be divided into N areas according to the number of foil tabs (1220) located at the bottom of the main body (1310). In the present embodiment, the blank area is divided into three areas (A1, A2, A3), but in other embodiments, it can be divided into two or four or more areas.

[0078] In the A1 region, one foil tab (1220) is positioned at the bottom of the main body (1310), in the A2 region, two foil tabs (1220) are positioned at the bottom of the main body (1310), and in the A3 region, three foil tabs (1220) are positioned at the bottom of the main body (1310). Therefore, the thickness of the overlapping foil tabs (1220) in the A2 region is twice that of the A1 region, and in the A3 region, it is three times that of the A1 region. In this case, if the output of the welding device is set so as to prevent overwelding in the A1 region and welding is performed, weak welding may occur not only in the A2 and A3 regions, but also in the foil tab (1220) portion where no blank region is formed. Therefore, it is necessary to set the output of the welding device so that proper welding can be performed in the foil tab (1220) portion where no blank area is formed, and to adjust the thickness of the receiving portion (1320) so that overwelding does not occur in the blank area. It is also necessary to vary the thickness of the receiving portion (1320) depending on each area of ​​the blank area.

[0079] In this embodiment, the thickness of the receiving portion (1320) is increased in the order of the A1, A2, and A3 regions. However, the thickness of the receiving portion (1320) is kept constant within each region. In other words, the thickness of the receiving portion (1320) changes in a stepwise manner. This prevents overwelding from occurring in some regions of the blank area.

[0080] In another embodiment of the present invention, referring to FIG. 10, the receiving portion (1320) of the current collector plate (1300) has an end facing in the opposite direction of the bending direction. Since the blank area becomes smaller in the direction opposite to the bending direction, the receiving portion (1320) of the current collector plate (1300) can be gradually thinner in thickness toward the end. This structure can also prevent overwelding in some areas of the blank area. A gradual change in the thickness of the receiving portion (1320) is easier to manufacture than a stepwise change.

[0081]

[0082] FIGS. 11A to 11E are drawings showing various modified examples of a receiving portion according to one embodiment of the present invention.

[0083] According to one embodiment of the present invention, the receiving portion (1320) can be formed by bending the bending direction end of the main body portion (1320). This has the advantage of allowing the main body portion (1320) and the receiving portion (1320) to be manufactured simply and quickly by bending a single plate. Depending on the number of bends and the bending angle, various shapes of the receiving portion (1320) can be manufactured.

[0084] In Fig. 11a, the receiving portion (1320) is shown as having a bent shape while maintaining a certain angle in the opposite direction of the bending direction. This shape is easy to manufacture as it can be formed with a single bend.

[0085] In Fig. 11b, the receiving portion (1320) has a first bend portion (1321) bent at a first angle and a second bend portion (1322) bent in the opposite direction to the bending direction. By performing the bending twice in this way, the receiving portion (1320) can be shaped to accommodate the foil tab well.

[0086] Figures 11c and 11d illustrate that a specific corner portion of the shape of the receiving portion (1320) illustrated in Figure 11b has been rounded. Figure 11e illustrates that the receiving portion (1320) has been bent to form a semicircular shape.

[0087] In the present invention, the shape of the receiving portion (1320) is not limited to that shown in FIGS. 11a to 11e, and may have various shapes that can receive a predetermined portion of the foil tab and at least a portion of which can be positioned in a blank area.

[0088]

[0089] FIG. 12 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.

[0090] Referring to FIG. 12, a current collector (1300) according to one embodiment of the present invention may have a supplementary portion (1340) formed at an end opposite to the bending direction (BD) of the main body portion (1310). That is, the supplementary portion (1340) is positioned to face the receiving portion (1320) with respect to the main body portion (1310).

[0091] The supplementary portion (1340) is located on the upper portion of the foil tab (1220) located on the outer side opposite to the bending direction (BD) from the lower side of the main body (1310) when the foil tab (1220) is bent in the bending direction (BD). Therefore, the supplementary portion (1340) fills the space formed between the main body (1310) and the foil tab (1220) as the foil tab (1220) is bent in the bending direction (BD). Due to this, when the foil tab (1220) and the collector plate (1300) are welded to each other, overwelding does not occur even if the output of the welding device is the same.

[0092] The supplementary portion (1340) may be formed in various shapes. For example, the supplementary portion (1340) may be formed by bending the end of the main body portion (1310) in the same manner as the receiving portion (1320). In another embodiment, the supplementary portion (1340) may be formed in the shape of a protrusion protruding from the lower side of the main body portion (1310).

[0093] The size of the supplementary portion (1340) may vary depending on the gap between the main body portion (1310) and the bent foil tab (1220). In addition, the supplementary portion (1340) may have a lower height relative to the bottom surface of the main body portion (1310) as it goes in the bending direction (BD).

[0094]

[0095] Figure 13 is a drawing showing a method for manufacturing a secondary battery according to one embodiment of the present invention.

[0096] Referring to FIG. 13, 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).

[0097] 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 the foil tabs are not coated with an active material.

[0098] 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.

[0099] In the bending step (S2200), multiple foil tabs are bent in the bending direction. This allows the foil tabs and the main body of the current collector to come into contact over a wide area during welding, enabling stable welding. In the present embodiment, the foil tabs (1220, 1220a) joined to each other can be bent in the same bending direction (BD), and 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 (BD).

[0100] In the settling step (S2300), the current collector is set on the upper side of the bent foil tab. The current collector has a main body and a receiving portion formed at one end of the main body, and a predetermined portion of some of the plurality of foil tabs is received in the receiving portion. The receiving portion can be formed into various shapes by bending the end of the main body in the bending direction.

[0101] The foil tabs accommodated in the receiving portion may be two to seven foil tabs positioned on the outer side in the bending direction. The predetermined portion may be from a position of 1 / 5 to 2 / 3 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.

[0102] In the welding step (S2400), the foil tab and the current 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. Upon welding, at least a portion of the receiving portion can be fused and integrated with a predetermined portion of the foil tab. Welding can be performed on the upper side of the main body.

[0103] In one embodiment, when welding the upper portion of the blank area in the welding step (S2400), the output of the welding device can be adjusted according to the thickness of the receiving portion. In the blank area, the thickness of the overlapping foil tab is thinner than in other areas. Therefore, if welding is performed with the same output as in other areas, overwelding may occur, causing the separator of the electrode part to melt in the lower portion of the blank area. To prevent this, a method of welding by lowering the output of the welding device in the blank area may be considered.

[0104] In the present invention, the receiving portion is positioned in the blank area, thereby compensating for the difference in foil tab thickness overlapping other areas. In this case, if the receiving portion does not cause a difference in foil tab thickness between the blank area and other areas due to the presence of the receiving portion, the blank area can be welded with the same output as other areas without causing overwelding.

[0105] In another embodiment, referring to FIG. 9, even within the blank area, the thickness of the overlapping foil tabs varies depending on the number of foil tabs positioned at the bottom of the main body. In this case, if the thickness of the receiving portion is constant, the output of the welding device must vary depending on the blank area when welding due to the difference in the thickness of the overlapping foil tabs.

[0106] If the thickness of the receiving portion is varied by considering the difference in the thickness of the overlapping foil tabs within the blank area and the sum of the thickness of the overlapping foil tabs and the thickness of the receiving portion is made constant, the output of the welding device can be made the same when welding within the blank area.

[0107]

[0108] 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 A current collector plate having a main body part welded on the upper side of the foil tabs while the plurality of foil tabs are bent in the bending direction, and a receiving part formed to receive a predetermined portion of some of the plurality of foil tabs at an end of the main body part in the bending direction, A secondary battery in which a predetermined portion of the above foil tab is welded to the current collector plate while being accommodated in the accommodation portion.

2. In paragraph 1, A secondary battery, wherein a predetermined portion of the above foil tab is melted and integrated with a portion of the main body and at least a portion of the receiving portion by welding.

3. In paragraph 1, A secondary battery in which the above-mentioned receiving portion is formed by bending the bending direction end of the above-mentioned main body portion.

4. In paragraph 3, A secondary battery in which the above-mentioned receiving portion is bent at a certain angle in the opposite direction to the above-mentioned bending direction.

5. In paragraph 3, A secondary battery, wherein the above-mentioned receiving portion has a first bend portion bent at a first angle and a second bend portion bent in a direction opposite to the bending direction.

6. In paragraph 1, A secondary battery, wherein the above-mentioned receiving portion is located in a blank area between the outermost foil tab and the electrode portion in the bending direction when the foil tab is bent in the bending direction.

7. In paragraph 6, The above blank area is divided into N areas according to the number of foil tabs located at the bottom of the main body. A secondary battery, wherein the thickness of the receptacle in the above blank area is the same in the same area and different in different areas.

8. In paragraph 7, The thickness of the above-mentioned receiving portion is thicker as the number of foil tabs located at the lower part of the above-mentioned main body is smaller, the secondary battery.

9. In paragraph 1, A secondary battery, wherein some of the foil tabs accommodated in the above-mentioned receiving portion are 2 to 7 foil tabs positioned 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 1 / 5 to 2 / 3 of the height of the foil tab based on the electrode portion to the upper end.

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, A secondary battery in which the thickness of the above-mentioned receiving portion becomes thinner towards the end.

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

14. 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 main body and a collector plate having a receiving portion formed at an end of the main body in the bending direction are mounted on the upper side of the bent foil tab, and a predetermined portion of some of the plurality of foil tabs is received in the receiving portion; and A method for manufacturing a secondary battery, comprising a welding step in which the foil tab and the current collector plate are welded while a predetermined portion of the foil tab is accommodated in the accommodation portion.

15. In paragraph 14, In the above welding step A method for manufacturing a secondary battery, wherein a predetermined portion of the above foil tab is melted and becomes integral with a portion of the main body and at least a portion of the receiving portion.

16. In paragraph 14, In the above welding step A method for manufacturing a secondary battery, wherein welding is performed on the upper side of the main body.

17. In paragraph 14, In the above settling stage A secondary premise manufacturing method, wherein the length of the foil tab accommodated in the above-mentioned receiving portion is different depending on the bending angle at which the foil tab is bent in the above-mentioned bending direction.

18. In paragraph 14, In the above settling stage A method for manufacturing a secondary battery, wherein the above-mentioned receiving portion is located in a blank area between the outermost foil tab and the electrode portion in the bending direction.

19. In paragraph 18, In the above welding step A secondary battery manufacturing method, wherein the output of the welding device is adjusted according to the thickness of the receiving portion when welding the upper portion of the blank area.

20. In paragraph 14, A method for manufacturing a secondary battery, characterized in that the receiving portion is formed by bending the bending direction end of the main body portion.

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