Secondary battery and method for manufacturing same

Abstract

The present invention relates to a secondary battery and a method for manufacturing same. The secondary battery according to the present invention is welded in a state in which a current-collecting plate is pressed in the direction of a foil tab and a crumpled area is formed at the top of the foil tab. At least one guide line is formed on the foil tab, enabling the setting of the inclination direction of the foil tab being pressed. The secondary battery according to the present invention can reduce the length of the foil tab without bending the foil tab in order to weld. The reduction in the length of the foil tab means that the size of a cell can be reduced or the capacity can be increased compared to a cell of the same size. In addition, since the foil tab is not bent, welding can be performed without forming gaps, thereby preventing any impact on an electrode assembly 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, which enable welding of a current collector plate and a foil tab in a state where the length of the foil tab is shortened and no blank area is created.

[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. As illustrated in 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 (30) and welded. In this case, since the upper side of one side of the foil tab (20) comes into contact with the collector plate (30), 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 welding by bending the foil tab (20), the length of the foil tab (20) must be formed long considering the bent portion. An increase in the length of the foil tab (20) leads to the problem that the cell size must increase.

[0006] In addition, 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 is thinner than other areas. In this case, if the output of the welding device is the same in the area without the blank area (A) and in the area with the blank area (A), when welding is performed above the blank area (A), the heat generated during the welding process may be transferred to the electrode assembly (10). As a result, a problem may occur in which the separator of the electrode assembly (10) melts at the lower part of the blank area (A).

[0007] In this way, welding with the foil tab (20) folded has the problem of the cell size increasing and the problem of affecting the electrode assembly (10) during the welding process.

[0008] The purpose of the present invention is to provide a secondary battery and a method for manufacturing the same, which can reduce the size of a cell by shortening the length of a foil tab and can be welded without creating a blank area.

[0009] In one aspect of the present invention, a secondary battery may include an electrode assembly having an electrode portion and a plurality of foil tabs formed at one end of the electrode portion and having a wrinkled area formed at an upper portion thereof, a current collector plate disposed on an upper side of the wrinkled area and welded to the plurality of foil tabs, and a case accommodating the electrode assembly.

[0010] In one aspect of the present invention, the wrinkle region in the secondary battery can be formed by pressing the current collector plate in the direction of the plurality of foil tabs.

[0011] In one aspect of the present invention, in the secondary battery, the wrinkle area may be formed to be 1 / 5 or more and 1 / 2 or less of the total length of the foil tab from the upper portion of the foil tab.

[0012] In one aspect of the present invention, at least one guideline may be formed on each of the plurality of foil tabs in the secondary battery.

[0013] In one aspect of the present invention, in the secondary battery, the plurality of foil tabs may be formed into a first group bent in a first direction and a second group bent in a second direction.

[0014] In one aspect of the present invention, in the secondary battery, the first direction and the second direction may be directions that are opposite to each other and may be in the inner direction of the case.

[0015] In one aspect of the present invention, in the secondary battery, the current collector plate may have a receiving groove formed at a position where the first group and the second group meet to receive some of the foil tabs of the first group and the second group.

[0016] In one aspect of the present invention, in the secondary battery, the plurality of foil tabs may have an upper portion that is in contact with the current collector plate and may be thicker than a lower portion.

[0017] In one aspect of the present invention, the secondary battery may have a protrusion or groove formed on the lower surface of the current collector plate.

[0018] In one aspect of the present invention, the secondary battery may further include a protective member interposed in at least a portion of an area between the upper surface of the electrode portion and the current collector plate.

[0019] In one aspect of the present invention, a dummy having a certain height may be interposed between the plurality of foil tabs in the secondary battery.

[0020] A method for manufacturing a secondary battery according to one aspect of the present invention may include a preparation step of preparing an electrode assembly having an electrode portion and a plurality of foil tabs formed at one end of the electrode portion, a mounting step of positioning a current collector plate on the upper side of the plurality of foil tabs, a pressing step of pressing the current collector plate in the direction of the plurality of foil tabs to form a wrinkle area on the upper side of the plurality of foil tabs, and a welding step of welding the current collector plate and the plurality of foil tabs while the plurality of foil tabs are pressed.

[0021] In a method for manufacturing a secondary battery according to one aspect of the present invention, the current collector plate may be pressed so that the wrinkle area is formed such that the wrinkle area is 1 / 5 or more and 1 / 2 or less of the total length of the foil tab from the top of the foil tab in the pressing step.

[0022] In a secondary battery manufacturing method according to one aspect of the present invention, at least one guideline is formed on each of the plurality of foil tabs, and in the pressing step, the foil tab can be bent in a predetermined direction depending on the formation position of the guideline when pressing.

[0023] A method for manufacturing a secondary battery according to one aspect of the present invention may be such that, in the pressing step, the plurality of foil tabs may be formed into a first group bent in a first direction and a second group bent in a second direction.

[0024] In a method for manufacturing a secondary battery according to one aspect of the present invention, the first direction and the second direction may be directions that are opposite to each other and may be an inner direction of the case.

[0025] In a secondary battery manufacturing method according to one aspect of the present invention, in the pressurizing step, some of the foil tabs of the first group and the second group can be accommodated in a receiving groove formed at a location where the first group and the second group of the current collector meet.

[0026] In a secondary battery manufacturing method according to one aspect of the present invention, a protective member may be interposed in at least a portion of an area between the upper surface of the electrode portion and the current collector plate in the preparation step.

[0027] In a method for manufacturing a secondary battery according to one aspect of the present invention, in the preparation step, the plurality of foil tabs may be formed so that the upper portion that comes into contact with the current collector is thicker than the lower portion.

[0028] In a method for manufacturing a secondary battery according to one aspect of the present invention, in the pressing step, the foil tabs located on both outer sides among the plurality of foil tabs can be pressed while being supported so as not to bend outward.

[0029] Since the secondary battery according to the present invention does not require bending of the foil tab for welding, the length of the foil tab can be shortened to reduce the size of the cell, or the capacity can be increased compared to a cell of the same size.

[0030] In addition, the secondary battery according to the present invention can be welded without creating a blank area by not bending the foil tab, thereby preventing the electrode assembly from being affected during the welding process.

[0031] 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.

[0032] FIG. 2 is a drawing showing a secondary battery according to the first embodiment of the present invention.

[0033] Figure 3 is a drawing showing an exploded view of a secondary battery according to the first embodiment of the present invention.

[0034] 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 the first embodiment of the present invention.

[0035] FIG. 5a and FIG. 5b are drawings showing a current collecting plate of a secondary battery according to the first embodiment of the present invention.

[0036] FIG. 6a and FIG. 6b are conceptual drawings showing that a current collector located on the upper side of a foil tab according to one embodiment of the present invention is pressed in the direction of the foil tab to form a wrinkled area.

[0037] FIG. 7a and FIG. 7b are conceptual drawings showing a current collector plate being pressed to form a wrinkled region while a dummy is interposed between a plurality of foil tabs according to one embodiment of the present invention.

[0038] Fig. 8 is a drawing showing a unit electrode plate according to a second embodiment of the present invention.

[0039] Figure 9 is a drawing showing that multiple foil tabs are formed into a first group and a second group.

[0040] FIG. 10 is a drawing showing cross-sections of various types of foil tabs according to an embodiment of the present invention.

[0041] FIG. 11 is a drawing showing that a protective member is interposed in at least a portion of the area between the upper surface of the electrode portion and the current collector plate according to an embodiment of the present invention.

[0042] Fig. 12 is a drawing showing a method for manufacturing a secondary battery according to an embodiment of the present invention.

[0043] FIG. 13 is a conceptual drawing showing that foil tabs located on both outer sides among a plurality of foil tabs according to an embodiment of the present invention are supported and pressed by a support member.

[0044] 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.

[0045] The terminology used herein is merely 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.

[0046] 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.

[0047]

[0048] Hereinafter, a secondary battery according to the first embodiment of the present invention will be described.

[0049] FIG. 2 is a drawing showing a secondary battery according to a first embodiment of the present invention, FIG. 3 is an exploded drawing showing a secondary battery according to the first 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 the first embodiment of the present invention, and FIGS. 5a and 5b are drawings showing a current collector plate of a secondary battery according to the first embodiment of the present invention.

[0050] Referring to FIGS. 2 to 5b, a secondary battery (1000) according to the first embodiment of the present invention may include a case (1100), an electrode assembly (1200), a collector plate (1300), and a cap assembly (1400).

[0051] 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 formed on one side. In the present embodiment, the case (1100) has a rectangular parallelepiped shape, but is not limited thereto and may have various shapes. 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.

[0052] 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.

[0053] 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).

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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 formed integrally 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).

[0059] 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.

[0060] 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) may include a main body (1310) and a connection portion (1320). Referring to FIGS. 5A and 5B , the main body (1310) has a plate shape, but is not limited thereto. The lower surface of the main body (1310) is welded to the foil tabs (1220, 1220a) on the upper side of the foil tabs (1220, 1220a). For welding, a method such as ultrasonic welding or laser welding may be used. Referring to FIG. 5B, a groove (1311) or a protrusion (not shown) may be formed on the lower surface of the main body (1300) to ensure good welding with the foil tabs (1220, 1220a). In this case, the foil tabs (1220, 122a) may be welded while being inserted between the grooves (1311) or the protrusions.

[0061] The collector plate (1300) may be provided with a connecting portion (1320) for connection with the terminal (1420, 1420a). In the present embodiment, the connecting portion (1320) is shaped like a rod, but is not limited thereto. In another embodiment, a portion of the collector plate (1300) may be convexly protruded so that the convex portion is connected to the terminal (1420, 1420a).

[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 in the shape of a plate 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 have a circular or square plate shape.

[0066] A terminal hole (1421, 1421a) may be formed in the terminal (1420, 1420a). A connecting portion (1320, 1320a) of the current collector (1300) 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] FIGS. 6A and 6B are conceptual drawings showing that a collector plate located on an upper side of a foil tab according to one embodiment of the present invention is pressed in the direction of the foil tab to form a wrinkled area, and FIGS. 7A and 7B are conceptual drawings showing that a collector plate is pressed to form a wrinkled area while a dummy is interposed between a plurality of foil tabs according to one embodiment of the present invention.

[0070] Referring to FIGS. 6A and 6B, to form a wrinkle area (PA), a current collector (1300) is placed on the upper side of a foil tab (1220), and the current collector (1300) is pressed toward the foil tab (1220). Accordingly, the foil tab (1220) is pressed by the current collector (1300), and a wrinkle area (PA) that is bent or crumpled while being pressed is formed on the upper side of the foil tab (1220). Thereafter, the foil tab (1220) and the current collector (1300) are welded.

[0071] When the current collector plate (1300) and the foil tab (1220) are welded in a state where a wrinkle area (PA) is formed in the foil tab (1220) in this way, the contact area between the current collector plate (1300) and the foil tab (1220) is increased by the wrinkle area (PA), so that the foil tab (1220) can be stably welded without having to bend in the bending direction. In addition, since it is not necessary to consider that the foil tab (1220) is bent, the length of the foil tab (1220) can be shortened.

[0072] When welding the current collector plate (1300) and the foil tab (1220), the height of the foil tab (1220) may not be constant due to processing errors, and as a result, a foil tab (1200) with a low height may not make proper contact with the current collector plate (1300). However, as in the present embodiment, when a wrinkle area (PA) is formed in the foil tab (1220) by the pressure of the current collector plate (1300), all foil tabs (1220) make proper contact with the current collector plate (1300) regardless of the height of the foil tab (1220).

[0073] The wrinkle area (PA) may be formed to be 1 / 5 or more and 1 / 2 or less of the total length of the foil tab from the upper portion of the foil tab (1220). If the wrinkle area (PA) exceeds 1 / 2 of the total length of the foil tab, the current collector (1300) and the electrode portion (1210) become too close, and the electrode portion (1210) may be affected by welding heat, etc. during welding. If the wrinkle area (PA) is less than 1 / 5 of the total length of the foil tab, it is difficult to achieve the effect of increasing the contact area between the foil tab (1220) and the current collector (1300). The range of the wrinkle area (PA) can be adjusted by changing the pressure applied to the current collector (1300).

[0074] In another embodiment, referring to FIGS. 7A and 7B, a dummy (100) having a certain height may be interposed between a plurality of foil tabs (1220). When the dummy (100) is interposed, even if pressure is applied to the foil tabs (1220), the dummy (100) supports the pressure, so that the portion of the foil tabs (1220) that is in contact with the dummy (100) does not bend or wrinkle. Accordingly, the portion of the foil tabs (1220) that is not in contact with the dummy (100) becomes a wrinkle area (PA). The dummy (100) may be removed after welding is completed, or may be left as is.

[0075] Although this embodiment describes that the wrinkle area (PA) is formed by pressing the foil tab (1220) of the collector plate (1300), the present invention is not limited thereto, and the wrinkle area (PA) can be formed in the foil tab (1220) in various ways. In addition, although this embodiment describes the foil tab (1220) and the collector plate (1300) for one pole, this configuration can be equally applied to the foil tab (1220a) and the collector plate (1300a) for the other poles illustrated in FIGS. 3 and 4.

[0076]

[0077] Below, a secondary battery according to a second embodiment of the present invention is described.

[0078] FIG. 8 is a drawing showing a unit electrode plate according to a second embodiment of the present invention, and FIG. 9 is a drawing showing that a plurality of foil tabs are formed into a first group and a second group.

[0079] Referring to Fig. 8, a guideline (1221) may be formed on the foil tab (1220) of the unit electrode plate (1211) according to the second embodiment of the present invention. The guideline (1221) is formed lower than the wrinkle area.

[0080] The guideline (1221) may be a groove, etc. In the present embodiment, the guideline (1221) is formed on only one of the two sides of the foil tab (1220). When the guideline (1221) is formed on the foil tab (1220), the foil tab (1220) is inclined toward the side on which the guideline (1221) is formed when pressurized. In the present embodiment, one guideline (1221) is formed on one foil tab (1220), but multiple guidelines (1221) may be formed on one foil tab (1220) as needed.

[0081] Referring to FIG. 9, in the present embodiment, a plurality of foil tabs (1220) can be formed into a first group (1220-1) inclined in a first direction and a second group (1220-2) inclined in a second direction. The direction in which the plurality of foil tabs (1220) are inclined can be controlled through the formation position of the guideline (1221). The first direction and the second direction are inward directions of the case. That is, in the present embodiment, the first direction and the second direction are opposite directions, and the plurality of foil tabs (1220) are inclined in a direction in which they converge from the outside to the inside. Through this configuration, the foil tabs (1220) are not inclined outward when pressed, and are stably aligned.

[0082] The current collector plate (1300) may have a receiving groove (1312) formed at a position where the first group (1220-1) and the second group (1220-2) of the foil tabs (1220) meet on the lower surface of the main body (1310). As the receiving groove (1312) is formed, a free space can be secured even when the foil tabs (1220) of the inclined first group (1220-1) and the second group (1220-2) overlap. This allows the foil tabs (1220) to stably tilt in a direction from the outside to the inside.

[0083]

[0084] FIG. 10 is a drawing showing cross-sections of various types of foil tabs according to an embodiment of the present invention.

[0085] Referring to Fig. 10, the foil tab (1220) may be thicker at the top than at the bottom. To this end, when forming the unit electrode plate (1211), the laser device output for cutting may be increased or the scanning speed may be increased when cutting the top portion of the foil tab (1220) compared to when cutting the bottom portion, so as to form a protrusion that is melted and solidified. In this case, as shown in (a) of Fig. 10, a protrusion is formed at the top of the foil tab (1220). In another embodiment, as shown in (b) of Fig. 10, the foil tab (1220) may be formed in a tapered shape in which the cross-sectional area becomes narrower from the top to the bottom.

[0086] In this way, when the upper part of the foil tab (1220) is thicker than the lower part, the foil tab (1220) can have a wide contact area with the collector plate (1300), so that it can be welded stably. In particular, in the present embodiment, since the foil tab (1220) is not bent during welding, it is meaningful to increase the contact area between the foil tab (1220) and the collector plate (1300) through this configuration.

[0087]

[0088] FIG. 11 is a drawing showing that a protective member is interposed in at least a portion of the area between the upper surface of the electrode portion and the current collector plate according to an embodiment of the present invention.

[0089] Referring to FIG. 11, in a secondary battery according to an embodiment of the present invention, a current collector plate (1300) covers a foil tab (1220) on the upper side of the foil tab (1220). In this case, the cross-section of the current collector plate (1300) is larger than the area where the foil tab (1220) is formed, and therefore, the current collector plate (1300) covers a portion of the upper surface of the electrode portion (1210). As a result, when the current collector plate (1300) and the foil tab (1220) are welded, welding heat, etc., affects the electrode portion (1210). In particular, when the length of the foil tab (1220) is short, as in the present embodiment, the effect is greater.

[0090] To prevent this, in the present embodiment, a protective member (1500) may be interposed in at least a portion of the area between the upper surface of the electrode portion (1210) and the current collector plate (1300). More specifically, the protective member (1500) is interposed in a portion of the upper surface of the electrode portion (1210) covered by the current collector plate (1300) where the foil tab (1220) is not formed. The protective member (1500) insulates the electrode portion (1210).

[0091] The protective member (1500) may be an insulating tape or a polymer material. The insulating tape is attached to the upper surface of the electrode portion (1210). The polymer material may be one selected from a polyolefin resin, an acrylic resin, a polyurethane resin, a polyester resin, a polyimide resin, a fluorine resin, an epoxy resin, a phenol resin, a melamine resin, a styrene resin, and a combination thereof, and is preferably polypropylene or polyimide, and is applied to the upper surface of the electrode portion (1210).

[0092]

[0093] FIG. 12 is a drawing showing a method for manufacturing a secondary battery according to an embodiment of the present invention, and FIG. 13 is a drawing conceptually showing that foil tabs located on both outer sides among a plurality of foil tabs according to an embodiment of the present invention are supported and pressed by a support member.

[0094] Referring to FIG. 12, a method for manufacturing a secondary battery according to an embodiment of the present invention includes a preparation step (S2100), a settling step (S2200), a pressurizing step (S2300), and a welding step (S2400).

[0095] 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.

[0096] 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.

[0097] In the settling step (S2200), a current collector plate is positioned on the upper side of a plurality of foil tabs. In this embodiment, the current collector plate has a plate shape, and a connecting portion for connection with a terminal is formed on the upper surface, and a protrusion or groove may be formed on the lower surface.

[0098] In the pressurizing step (S2300), the current collector plate is pressed toward a plurality of foil tabs. By pressing, a wrinkled region is formed on the upper portion of the foil tabs. The extent of the wrinkled region formation can be controlled by varying the pressure applied to the current collector plate. In the present embodiment, the current collector plate can be pressed so that the wrinkled region is formed from the upper portion of the foil tabs to a distance of 1 / 5 or more and 1 / 2 or less of the total length of the foil tabs.

[0099] In another embodiment, a dummy layer may be interposed between the foil tabs before pressurizing the current collector plate. The portion of the foil tab that contacts the dummy layer does not form a wrinkled area. The dummy layer may be removed before welding, or, depending on the material of the dummy layer, the welding step (S2400) may proceed without removing the dummy layer.

[0100] In the welding step (S2400), the foil tab and the current collector are welded. Welding is performed using a welding device. In the present invention, methods such as laser welding and ultrasonic welding can be applied.

[0101] In one embodiment, at least one guideline may be formed in the width direction on each of the plurality of foil tabs. When pressed, the foil tabs are inclined toward the side on which the guideline is formed. Additionally, the plurality of foil tabs may be formed so that the upper portion contacting the collector plate is thicker than the lower portion.

[0102] In this embodiment, by adjusting the formation position of the guideline, a plurality of foil tabs can be formed into a first group inclined in a first direction and a second group inclined in a second direction. The first and second directions are the inner direction of the case (1300). When the foil tabs are formed into the first group and the second group in this way, even if the foil tabs are deformed by pressure, the foil tabs can be efficiently accommodated in a predetermined space.

[0103] In one embodiment of the present invention, in the pressurizing step (S2300), a receiving groove is formed at a location where the first group and the second group of foil tabs meet on the current collector plate, and a portion of the first group and the second group of foil tabs can be received in the receiving groove. This can prevent the current collector plate from being tilted or warped due to the foil tabs (1220) of the inclined first group (1220-1) and the second group (1220-2) overlapping.

[0104] In one embodiment of the present invention, a protective member may be interposed in at least a portion of an area between the upper surface of the electrode portion and the current collector plate in the preparation step (S2100). The protective member (1500) may be an insulating tape or a polymer material. The insulating tape is attached to the upper surface of the electrode portion (1210). The polymer material may be one selected from a polyolefin-based resin, an acrylic resin, a polyurethane-based resin, a polyester-based resin, a polyimide-based resin, a fluorine-based resin, an epoxy-based resin, a phenol-based resin, a melamine-based resin, a styrene-based resin, and a combination thereof, and may preferably be polypropylene or polyimide, and is attached to the upper surface of the electrode portion (1210).

[0105] In one embodiment of the present invention, as illustrated in FIG. 13, in the pressurizing step (S2300), the foil tabs located on both outer sides among the plurality of foil tabs can be pressed while being supported so as not to bend outward. A supporting member or the like can be used to support the outer foil tabs on both sides.

[0106] In this case, the pressurizing step may include a step of supporting foil tabs located on both outer sides of a plurality of foil tabs with a support member, a step of applying pressure to a collector plate, and a step of removing the support member. In another embodiment, a dummy may be interposed between a plurality of collector plates and then the foil tabs may be supported with a support member.

[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 comprising an electrode portion and a plurality of foil tabs formed at one end of the electrode portion and having a wrinkled area formed at the upper portion; A current collector plate disposed on the upper side of the above wrinkled area and welded to the plurality of foil tabs; and A secondary battery comprising a case that accommodates the electrode assembly.

2. In paragraph 1, A secondary battery in which the above wrinkled region is formed by the current collector plate being pressed in the direction of the plurality of foil tabs.

3. In paragraph 1, A secondary battery, wherein the above wrinkle area is formed such that it is 1 / 5 or more and 1 / 2 or less of the total length of the foil tab from the upper portion of the foil tab.

4. In paragraph 1, A secondary battery, wherein each of the plurality of foil tabs has at least one guideline formed thereon.

5. In paragraph 1, A secondary battery, wherein the above plurality of foil tabs are formed into a first group bent in a first direction and a second group bent in a second direction.

6. In paragraph 5, A secondary battery, wherein the first direction and the second direction are opposite to each other and are in the inner direction of the case.

7. In paragraph 5, A secondary battery, wherein the above current collector plate has a receiving groove formed at a location where the first group and the second group meet to receive some of the foil tabs of the first group and the second group.

8. In paragraph 1, A secondary battery in which the plurality of foil tabs are thicker at the upper end than at the lower end in contact with the current collector plate.

9. In paragraph 1, The above-mentioned current collector plate is a secondary battery having a protrusion or groove formed on the lower surface.

10. In paragraph 1, A secondary battery further comprising a protective member interposed in at least a portion of an area between the upper surface of the electrode portion and the current collector plate.

11. In paragraph 1, A secondary battery, wherein a dummy having a certain height is interposed between the plurality of foil tabs.

12. A preparatory step in which an electrode assembly having an electrode portion and a plurality of foil tabs formed on one end of the electrode portion is prepared; A mounting step of positioning a current collector plate on the upper side of the plurality of foil tabs; A pressing step of pressing the above-mentioned current collector plate in the direction of the plurality of foil tabs to form a wrinkle area on the upper portion of the plurality of foil tabs; and A method for manufacturing a secondary battery, comprising a welding step of welding the plurality of foil tabs and the current collector plate while the plurality of foil tabs are pressurized.

13. In paragraph 12, In the above pressurizing step A method for manufacturing a secondary battery, wherein the current collector plate is pressed so that the wrinkle area is formed such that the wrinkle area is 1 / 5 or more and 1 / 2 or less of the total length of the foil tab from the upper portion of the foil tab.

14. In paragraph 12, At least one guideline is formed on each of the plurality of foil tabs, A secondary battery manufacturing method, wherein the foil tab is bent in a predetermined direction according to the formation position of the guideline during pressurization in the pressurizing step.

15. In paragraph 12, In the above pressurizing step A method for manufacturing a secondary battery, wherein the plurality of foil tabs are formed into a first group bent in a first direction and a second group bent in a second direction.

16. In paragraph 15, A method for manufacturing a secondary battery, wherein the first direction and the second direction are opposite to each other and are in an inner direction of the case.

17. In paragraph 15, In the above pressurizing step A method for manufacturing a secondary battery, wherein some of the foil tabs of the first group and the second group are accommodated in a receiving groove formed at a location where the first group and the second group of the above-mentioned current collector plate meet.

18. In paragraph 12, In the above preparation stage A method for manufacturing a secondary battery, wherein a protective member is interposed in at least a portion of an area between the upper surface of the electrode portion and the current collector plate.

19. In paragraph 12, In the above preparation stage A battery manufacturing method wherein the plurality of foil tabs are formed so that the upper portion that comes into contact with the current collector is thicker than the lower portion.

20. In paragraph 12, In the above pressurizing step A method for manufacturing a secondary battery, wherein the foil tabs located on both outer sides of the plurality of foil tabs are supported and pressed so as not to bend outward.

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