Secondary battery and method for manufacturing the same

Abstract

This invention relates to a secondary battery and a method for manufacturing the secondary battery. The technical problem to be solved is to prevent damage caused by fatigue loads that may occur during ultrasonic welding between the electrode terminals and the auxiliary terminals by strong laser welding between the auxiliary terminal and the current collector of the single plate. To this end, a secondary battery and a method for manufacturing the secondary battery are disclosed, wherein the secondary battery includes: an electrode assembly having electrode terminals; an auxiliary terminal, which is a metal single plate mechanically and electrically connected to the electrode terminals; and a current collector mechanically and electrically connected to the auxiliary terminal; wherein the auxiliary terminal includes: a terminal connection portion welded to the electrode terminals; a current collector connection portion welded to the current collector and disposed parallel to the terminal connection portion; and a bending portion connected between the terminal connection portion and the current collector connection portion and surrounding one side of the current collector.

Description

Technical Field

[0001] Various embodiments of the present invention relate to secondary batteries and methods for manufacturing such secondary batteries. Background Technology

[0002] Unlike primary batteries, secondary batteries are rechargeable. Among these secondary batteries, low-capacity batteries, which consist of groups of battery cells, can be used in small portable electronic devices such as cell phones or portable cameras, while high-capacity batteries, which consist of dozens of battery cells connected to each other, can be used as a power source for driving motors, such as those used in electric motorcycles, hybrid vehicles, or electric vehicles.

[0003] A secondary battery is constructed by housing an electrode assembly (which can be formed by arranging a separator, acting as an insulator, between the positive and negative electrode plates) together with an electrolyte solution in a housing and attaching a cover plate to the housing. As an example, the electrode assembly can be formed into a jelly roll configuration. This jelly roll electrode assembly is configured such that the main terminal piece (e.g., the uncoated portion of the positive or negative electrode plate) protrudes upward from the electrode assembly or from its left and right sides, and a current collector connects to the main terminal piece or the uncoated portion.

[0004] The information disclosed in this background section is only intended to enhance the understanding of the background of the present invention, and therefore may contain information that does not constitute prior art known to those skilled in the art in this country. Summary of the Invention

[0005] Technical issues

[0006] The object of the present invention is to provide a secondary battery and a method for manufacturing the secondary battery, wherein the auxiliary terminal piece and the current collector, which are single plates, are subjected to high-intensity laser welding, thereby preventing damage caused by fatigue loads that may occur during ultrasonic welding between the electrode terminal piece and the auxiliary terminal piece.

[0007] Another object of the present invention is to provide a secondary battery and a method for manufacturing the secondary battery, wherein the electrode terminals and the auxiliary terminals are welded together by using a flexible rigid material in the auxiliary terminals, thereby preventing the weld from breaking during bending after the electrode terminals and the auxiliary terminals are welded together.

[0008] Solution to the problem

[0009] In the secondary battery and method for manufacturing the secondary battery according to the present invention, the secondary battery may include: an electrode assembly having electrode terminals; an auxiliary terminal, which is a metal plate mechanically and electrically connected to the electrode terminals; and a current collector mechanically and electrically connected to the auxiliary terminal, wherein the auxiliary terminal includes: a terminal connection portion welded to the electrode terminals; a current collector connection portion welded to the current collector and disposed parallel to the terminal connection portion; and a bending portion connected between the terminal connection portion and the current collector connection portion and surrounding one side of the current collector.

[0010] The current collector connection may have a laser-welded part that is connected to the current collector by laser welding.

[0011] The laser welding portion may include: a linear welding portion that is straight and spaced a predetermined distance from the bent portion; and a circular welding portion that has an end that overlaps with the linear welding portion.

[0012] When the electrode tab has a thickness of at least about 0.4 mm to about 0.5 mm, the linear weld portion may be spaced from the bend portion by a distance of at least about 0.8 mm to about 1.2 mm.

[0013] When the electrode tab has a thickness of at least about 0.5 mm to about 0.7 mm, the linear weld portion may be spaced from the bend portion by a distance of at least about 1.2 mm to about 1.8 mm.

[0014] The length of the linear welded section may be greater than the length of the current collection connection section, and the start and end points of the linear welded section may be located in the current collection section.

[0015] The laser-welded portion may be a circular welded portion, which is circular and spaced from the bent portion by a distance of at least about 1.5 mm to about 1.8 mm.

[0016] The auxiliary connector can be made of 1050-O aluminum or 1100-O copper, which have high rigidity and ductility.

[0017] According to another aspect, a method for manufacturing a secondary battery is provided, comprising the following steps: preparing an auxiliary terminal piece by bending the auxiliary terminal piece, which is a flat rectangular plate, by bending it 90 degrees, the auxiliary terminal piece having a terminal piece connecting portion and a current collector connecting portion located on the opposite side of the bent portion; performing laser welding with the inner surface of the current collector connecting portion in contact with the inner surface of the current collector; ultrasonically welding the terminal piece connecting portion to an electrode terminal piece of an electrode assembly; and bending the terminal piece connecting portion and the electrode terminal piece to contact the outer surface of the current collector.

[0018] In the laser welding process, a linear weld portion and a circular weld portion may be formed. The linear weld portion is straight and spaced at least about 0.8 mm to about 1.8 mm away from the bent portion. The circular weld portion is circular and has an end that overlaps with the linear weld portion.

[0019] Beneficial effects

[0020] As described above, in the secondary battery and the method for manufacturing the secondary battery, the auxiliary terminal piece and the current collector, which are single plates, are subjected to high-intensity laser welding, thereby preventing damage caused by fatigue loads that may occur during ultrasonic welding between the electrode terminal piece and the auxiliary terminal piece.

[0021] In addition, in the secondary battery and the method for manufacturing the secondary battery, the electrode terminals and the auxiliary terminals are welded together using a flexible rigid material in the auxiliary terminals, thereby preventing the welded part from breaking during bending after the electrode terminals and the auxiliary terminals are welded together. Attached Figure Description

[0022] Figure 1 A perspective view of a secondary battery according to various embodiments of the present invention is shown.

[0023] Figure 2a and Figure 2b for Figure 1 The image shows a longitudinal view and a cross-sectional view of the secondary battery.

[0024] Figure 3 A perspective view of an electrode assembly in a secondary battery according to various embodiments of the present invention is shown.

[0025] Figure 4 for Figure 2b A magnified view of part A.

[0026] Figure 5a and Figure 5b In manufacturing Figure 1 The diagram shows a perspective view and an exploded perspective view of the current collector and auxiliary terminals during secondary battery operation.

[0027] Figure 6 for Figure 5b An enlarged view of an example of the welding of the current collector and auxiliary connector shown.

[0028] Figure 7 This shows the result of a break between the auxiliary connector and the current collector.

[0029] Figure 8 This refers to the result of the electrode plate being squeezed when the auxiliary connecting piece is bent.

[0030] Figure 9 for Figure 5bAnother example enlarged view of the welded portion of the current collector and auxiliary connector shown.

[0031] Figure 10 for Figure 5b An enlarged view of another example of the welding of the current collector and auxiliary connector shown. Detailed Implementation

[0032] Exemplary embodiments will now be described more fully with reference to the accompanying drawings.

[0033] This invention may be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be comprehensive and complete, and will fully convey the scope of the invention to those skilled in the art.

[0034] In the accompanying drawings, for clarity, the thickness of layers, films, panels, areas, etc., is exaggerated. The same reference numerals refer to the same elements throughout the specification. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Furthermore, it will be understood that when element A is referred to as being "connected to" element B, element A may be directly connected to element B, or an intermediate element C may exist between them, thus indirectly connecting element A and element B to each other.

[0035] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. Throughout this specification, singular forms may include plural forms unless specifically described to the contrary. Moreover, terms such as “comprising” or “including” are used to indicate the presence of said forms, quantities, processes, operations, components and / or groups thereof, but do not exclude the presence of one or more other said forms, one or more quantities thereof, one or more other processes, one or more other operations, one or more other components and / or groups thereof.

[0036] It will be understood that while the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, and / or segment from another. Therefore, the first element, component, region, layer, and / or segment discussed below may be referred to as the second element, component, region, layer, and / or segment without departing from the teachings of the invention.

[0037] For ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” and “up” are used herein to describe the relationship between one element or feature and another element or feature as shown in the figures. It will be understood that, in addition to the orientation depicted in the figures, spatial relative terms are intended to encompass different orientations of the device in use or operation. For example, if the device in the figure is flipped, an element described as “below” or “under” other elements or features would then be oriented “above” other elements or features. Thus, the exemplary term “below” can encompass both above and below orientations.

[0038] See Figure 1 A perspective view illustrating a secondary battery according to various embodiments of the present invention is shown. See also Figure 2a and Figure 2b , example Figure 1 The image shows a longitudinal view and a cross-sectional view of the secondary battery.

[0039] See Figure 1 , Figure 2a and Figure 2b The secondary battery 100 according to the present invention includes a stacked electrode assembly 110, a first auxiliary terminal 120 electrically connected to one side of the electrode assembly 110 (e.g., the first electrode terminal 114), a first current collector 130 electrically connected to the first auxiliary terminal 120, a first terminal portion 140 electrically connected to the first current collector 130, a second auxiliary terminal 150 electrically connected to the other side of the electrode assembly 110 (e.g., the second electrode terminal 115), a second current collector 160 electrically connected to the second auxiliary terminal 150, a second terminal portion 170 electrically connected to the second current collector 160, a housing 180 for accommodating the electrode assembly 110, and a cover assembly 190 connected to an opening of the housing 180.

[0040] The secondary battery 100 according to an embodiment of the present invention will now be described by way of example with reference to a lithium-ion secondary battery having a prismatic shape. However, the invention is not limited thereto and can be applied to various types of batteries, including lithium polymer batteries.

[0041] The electrode assembly 110 may include a stacked structure comprising a first electrode plate 111, a second electrode plate 112, and a partition 113 between the first electrode plate 111 and the second electrode plate 112. See also Figure 3 A perspective view of electrode assembly 110 is shown, see below. Figure 4 , example Figure 2b An enlarged view of the electrode assembly 110 of part 4 is shown. In the following text, reference will be made to... Figure 3 and Figure 4 The structure of electrode assembly 110 is described.

[0042] The electrode assembly 110 includes a first electrode tab 114 and a second electrode tab 115, which protrude from opposite sides of a cuboid structure formed by sequentially stacking a first electrode plate 111 having a generally rectangular shape, a partition plate 113 having a rectangular shape, and a second electrode plate 112 having a generally rectangular shape, rather than from a structure wound into a jelly roll. The first electrode tab 114 and the second electrode tab 115 may have a thickness of approximately 0.4 mm to approximately 0.7 mm.

[0043] Here, the first electrode plate 111 can be used as a negative electrode, and the second electrode plate 112 can be used as a positive electrode. Conversely, the first electrode plate 111 can be used as a positive electrode, and the second electrode plate 112 can be used as a negative electrode. However, for ease of explanation, the invention will be described by way of example with the case where the first electrode plate 111 is used as a negative electrode and the second electrode plate 112 is used as a positive electrode.

[0044] The first electrode plate 111 can be formed by coating a first electrode active material 111b, such as graphite or carbon, onto a first current collector 111a formed of a metal foil such as copper, copper alloy, nickel, or nickel alloy, and may include a first electrode terminal piece 114 (or a first uncoated portion), which is the area not coated with the first electrode active material. The first electrode terminal piece 114 is the current path between the first electrode plate 111 and the first auxiliary terminal piece 120.

[0045] like Figure 2b As shown, the first electrode tab 114 can protrude / extend to one side of the electrode assembly 110 by a predetermined length and can be bent in a generally "L" shape. Specifically, the first electrode tab 114 can be bent in an "L" shape after being welded to the first auxiliary tab 120. That is, the first electrode tab 114 of the electrode assembly 110 is initially approximately parallel to the first electrode plate 111, but once the first electrode tab 114 is welded to the first auxiliary tab, it can be bent in an "L" shape to be approximately parallel to a surface of the first current collector 130. Here, the first electrode tab 114 can be joined by ultrasonic welding while overlapping with the first auxiliary tab 120.

[0046] The second electrode plate 112 can be formed by coating a second electrode active material 112b, such as a transition metal oxide, onto a second current collector 112a formed of a metal foil such as aluminum or an aluminum alloy. The second electrode terminal 115 (or the second uncoated portion) is the area where the second electrode active material 112b is not coated. The second electrode terminal 115 is the current path between the second electrode plate 112 and the second auxiliary terminal 150.

[0047] like Figure 2b As shown, the first electrode tab 114 can protrude / extend to one side of the electrode assembly 110 by a predetermined length and can be bent in a generally "L" shape. Specifically, the first electrode tab 114 can be bent in an "L" shape after being welded to the first auxiliary tab 120. That is, the first electrode tab 114 of the electrode assembly 110 is initially approximately parallel to the first electrode plate 111, but once the first electrode tab 114 is welded to the first auxiliary tab, it can be bent in an "L" shape to be approximately parallel to a surface of the first current collector 130. Here, the first electrode tab 114 can be joined by ultrasonic welding while overlapping with the first auxiliary tab 120.

[0048] Like the first electrode tab 114, the second electrode tab 115 can protrude / extend a predetermined length from the electrode assembly 110 to the other side and can be bent in a generally "L" shape. Specifically, the second electrode tab 115 can be bent in an "L" shape after being welded to the second auxiliary tab 150. That is, the second electrode tab 115 of the electrode assembly 110 is initially generally parallel to the second electrode plate 112, but once the second electrode tab 115 is welded to the second auxiliary tab 150, the second electrode tab 115 can be bent in an "L" shape to be generally parallel to a surface of the second current collector 160. Here, the second electrode tab 115 can be joined by ultrasonic welding while it overlaps with the second auxiliary tab 150.

[0049] In addition, the first electrode tab 114 and the second electrode tab 115 are configured to protrude / extend a predetermined length in the opposite direction to the electrode assembly 110.

[0050] The separator 113 located between the first electrode plate 111 and the second electrode plate 112 prevents short circuits between them and allows for the movement of lithium ions. Furthermore, the separator 113 can be made of polyethylene, polypropylene, or a composite film of polyethylene and polypropylene, but the present invention does not limit the material of the separator 113 to these. In some cases, the separator 113 can be replaced by a solid electrolyte.

[0051] For example, electrode assembly 110 may be housed together with electrolyte solution in housing 180, but is not limited thereto. The electrolyte solution may, for example, consist of lithium salts such as LiPF6 or LiBF4, or organic solvents such as EC, PC, DEC, EMC, and DMC. Alternatively, the electrolyte solution may be liquid, solid, or gel.

[0052] The first auxiliary connector 120 may include a first connector connection portion 121 electrically and mechanically grounded to the first electrode connector 114, a first current collector connection portion 122 electrically and mechanically grounded to the first current collector 130, and a first bend portion 123 connecting the first connector connection portion 121 and the first current collector connection portion 122. The first auxiliary connector 120 may be formed by bending a flat sheet. The first connector connection portion 121 and the first current collector connection portion 122 may become parallel to each other by means of the first bend portion 123. The first connector connection portion 121 may be located between the first electrode connector 114 and the first current collector 130, and the first current collector connection portion 122 may be located between the first current collector 130 and a side surface of the electrode assembly 110. The first auxiliary connector 120 may be a metal sheet.

[0053] With the first auxiliary connector 120 bent in an "L" shape, the first current collector connection portion 122 provided on one side of the first auxiliary connector 120 can first be welded to the first current collector 130, and the first connector portion 121 provided on the other side of the first auxiliary connector 120 can then be welded to the first electrode connector 114. After the first auxiliary connector 120 is welded to the first electrode connector 114, the first bending portion 123 can be bent in a "U" shape so that it is substantially parallel to one surface of the first current collector 130 together with the first electrode connector 114. That is, since the first auxiliary connector 120 should be bent in a "U" shape during the manufacturing process of the secondary battery 100, a flexible material can be used for the first auxiliary connector 120. For this purpose, the first auxiliary connector 120 can have a smaller thickness than the first current collector 130. Preferably, the first auxiliary connector 120 can be made of 1050-O aluminum with high rigidity and ductility, and its thickness can be approximately 0.3 mm. As shown in Table 1, when the first auxiliary connector 120 is made of 0.3mm thick 1050-O aluminum, the plastic strain of the first auxiliary connector 120 is within the range of the reference elongation of all materials when the first auxiliary connector 120 is bent at 90 degrees and 180 degrees, indicating that no local cracking or damage has occurred.

[0054] [Table 1]

[0055]

[0056]

[0057] The first auxiliary connector 120 can be ultrasonically welded to the first electrode connector 114. The welding between the first auxiliary connector 120 and the first current collector 130 and the welding between the first auxiliary connector 120 and the first electrode connector 114 will be described in more detail below.

[0058] The first current collector 130 includes a first electrode connection portion 131 that is electrically and mechanically grounded to the first auxiliary terminal block 120, and a first terminal connection portion 132 that bends and extends from the top of the first electrode connection portion 131 and is electrically and mechanically grounded to the first terminal portion 140.

[0059] The first electrode connection portion 131 contacts and is connected to the first auxiliary connector 120 so as to be electrically connected to the first electrode connector 114 of the electrode assembly 110. The first electrode connection portion 131 is welded to the first auxiliary connector 120 and has a vertical standing shape. The first electrode connection portion 131 can be connected to the first auxiliary connector 120 by laser welding. The welding between the first electrode connection portion 131 and the first auxiliary connector 120 will be described in more detail below.

[0060] The first terminal connection portion 132 is connected to the first terminal portion 140 in a horizontally positioned plate shape, parallel to the cover plate 191. The first terminal connection portion 132 can be soldered to the first terminal portion 140 and can be located between the cover plate 191 of the cover assembly 190 (described later) and the electrode assembly 110. The first terminal connection portion 132 can be perpendicular to the top end of the first electrode connection portion 131.

[0061] The first auxiliary terminal block 120, the first current collector 130, and the first electrode terminal block 114 may be made of the same material. Preferably, if the first electrode terminal block 114 is made of copper, then the first auxiliary terminal block 120 and the first current collector 130 may also be made of copper-based material.

[0062] The first terminal portion 140 is electrically connected to the first electrode terminal 114 of the electrode assembly 110 via the first current collector 130 and the first auxiliary terminal 120. Here, the first terminal portion 140 may include a first terminal post 141 passing through a cover plate 191 of the cover assembly 190, and the first electrode connection portion 131 of the first current collector 130 is electrically connected to the first terminal post 141 within the housing 180. Furthermore, the first auxiliary terminal 120 is connected to the first current collector 130, and the first electrode terminal 114 of the electrode assembly 110 is then electrically connected to the first auxiliary terminal 120. Additionally, the first terminal portion 140 is located on the cover plate 191 and may include a first terminal plate 142 (e.g., made of aluminum) connected to the first terminal post 141, a first terminal upper insulating member 143 installed between the first terminal plate 142 and the cover plate 191, a first terminal sealing gasket 144 located between the first terminal post 141 and the cover plate 191, and a first terminal lower insulating member 145 installed between the first current collector 130 connected to the first terminal post 141 and the cover plate 191.

[0063] Furthermore, those skilled in the art will understand that the first terminal portion 140 is provided only as an example for understanding one or more embodiments of the present invention, and the first terminal portion 140 can be modified in various types / structures.

[0064] The second auxiliary connector 150 may include a second connector connection portion 151 electrically and mechanically grounded to the second electrode connector 115, a second current collector connection portion 152 electrically and mechanically grounded to the second current collector 160, and a second bending portion 153 connecting the second connector connection portion 151 to the second current collector connection portion 152. The second auxiliary connector 150 may be formed by bending a flat sheet. The second connector connection portion 151 and the second current collector connection portion 152 may become parallel to each other by means of the second bending portion 152. The second connector connection portion 151 may be located between the second electrode connector 115 and the second current collector 160, and the second current collector connection portion 152 may be located between the second current collector 160 and a side surface of the electrode assembly 110. The second auxiliary connector 150 may be a metal sheet.

[0065] With the second auxiliary connector 150 bent in an "L" shape, the second current collector connection portion 152 provided on one side of the second auxiliary connector 150 can first be soldered to the second current collector 160, and the second connector portion 151 provided on the other side of the second auxiliary connector 150 can then be soldered to the second electrode connector 115. After the second auxiliary connector 150 is soldered to the second electrode connector 115, the second bending portion 153 can be bent in a "U" shape so that it is substantially parallel to one surface of the second current collector 160 together with the second electrode connector 115. That is, since the second auxiliary connector 150 should be bent in a "U" shape during the manufacturing process of the secondary battery 100, flexible material can be used for the second auxiliary connector 150. For this purpose, the second auxiliary connector 150 can have a smaller thickness than the second current collector 160.

[0066] Preferably, the second auxiliary connector 150 may be made of 1100-O copper with high rigidity and ductility, and its thickness may be approximately 0.2 mm. As shown in Table 2, when the second auxiliary connector 150 is made of 0.2 mm thick 1100-O copper, the plastic strain of the second auxiliary connector 150 is within the range of the reference elongation of all materials when the second auxiliary connector 150 is bent at 90 degrees and 180 degrees, indicating that no local cracking or damage has occurred.

[0067] [Table 2]

[0068]

[0069] The second auxiliary connector 150 can be laser-welded to the second current collector 160 and ultrasonically welded to the second electrode connector 115.

[0070] The second current collector 160 may include a second electrode connection portion 161 that is electrically and mechanically grounded to the second auxiliary terminal block 150, and a second terminal connection portion 152 that bends and extends from the top end of the second electrode connection portion 161 and is electrically and mechanically grounded to the second terminal portion 170.

[0071] The second electrode connection portion 161 contacts and is connected to the second auxiliary connector 150 so as to be electrically connected to the second electrode connector 115 of the electrode assembly 110. The second electrode connection portion 161 is welded to the second auxiliary connector 150 and has a vertical standing shape. The second electrode connection portion 161 can be connected to the second auxiliary connector 150 by laser welding.

[0072] The second terminal connection portion 162 is connected to the second terminal portion 170 in a horizontally positioned plate shape, parallel to the cover plate 191. The second terminal connection portion 162 can be soldered to the second terminal portion 160 and can be located between the cover plate 191 of the cover assembly 190 (described later) and the electrode assembly 110. The second terminal connection portion 162 can be perpendicular to the top end of the second electrode connection portion 161.

[0073] The second auxiliary terminal block 150, the second current collector 160, and the second electrode terminal block 115 can be made of the same material. Preferably, if the second electrode terminal block 115 is made of aluminum, then the second auxiliary terminal block 150 and the second current collector 160 can also be made of aluminum-based material.

[0074] The second terminal portion 170 is electrically connected to the second electrode terminal 115 of the electrode assembly 110 via the second current collector 160 and the second auxiliary terminal 150. Here, the second terminal portion 170 may include a second terminal post 171 passing through a cover plate 191 of the cover assembly 190, and the second electrode connection portion 161 of the second current collector 160 is electrically connected to the second terminal post 171 within the housing 180. Furthermore, the second auxiliary terminal 150 is connected to the second current collector 160, and the second electrode terminal 115 of the electrode assembly 110 is then electrically connected to the second auxiliary terminal 150.

[0075] Additionally, the second terminal portion 170 is located on the cover plate 191 and may include a second terminal plate 172 (e.g., made of aluminum) connected to the second terminal post 171, a second terminal upper insulating member 173 installed between the first terminal plate 132 and the cover plate 191, a second terminal sealing gasket 174 located between the second terminal post 171 and the cover plate 191, and a second terminal lower insulating member 175 installed between the second current collector 170 connected to the second terminal post 171 and the cover plate 191.

[0076] Here, the insulating member 173 on the second terminal can be replaced by a high-resistance conductor. In this case, the cover plate 191 and the housing 180 can have the same polarity as the second terminal portion 170. That is, the housing 180 and the cover plate 191 can carry a positive charge in the secondary battery 100.

[0077] Furthermore, those skilled in the art will understand that the second terminal portion 170 is provided only as an example for understanding one or more embodiments of the present invention, and the second terminal portion 170 can be modified in various types / structures.

[0078] The housing 180 may be generally rectangular in shape and have an opening formed in its upper part. The electrode assembly 110 can be inserted into the interior of the housing 180 through this opening. In addition, the first auxiliary connector 120, the first current collector 130, the second auxiliary connector 150, and the second current collector 160 may be located inside the housing 180.

[0079] First, the cover assembly 190 may include a plate-shaped cover plate 191. That is, the cover plate 191 is made of a sheet material and is attached to an opening in the housing 180 to then seal the opening. Additionally, the cover plate 191 includes an electrolyte injection port 192 for injecting electrolyte into the sealed housing 180. Once the electrolyte is injected, the electrolyte injection port 192 is sealed by a sealing plug 193. Furthermore, the cover plate 191 includes a vent hole 194, and a vent plate 195 is installed in the vent hole 194, which breaks when the internal pressure of the sealed housing 180 is greater than or equal to a preset pressure level.

[0080] See Figure 5a For example, in manufacturing Figure 1 The perspective view of the current collector and auxiliary terminals during secondary battery operation is illustrated; see [link to relevant documentation]. Figure 5b An exploded perspective view is shown, exemplified by the welding between the current collector and the auxiliary terminal block.

[0081] In the following text, reference will be made to Figure 5a and Figure 5b The welding between the auxiliary connector 120 and the current collector 130 is described. Here, the auxiliary connector 120 refers to the first auxiliary connector 120, and the current collector 130 refers to the first current collector 130, which can also be applied to the second auxiliary connector 150 and the second current collector 160.

[0082] First, the auxiliary terminal block 120 can be formed by bending a single flat rectangular plate by 90 degrees. The auxiliary terminal block 120 may include a bend 123 provided along the longitudinal direction, and the terminal block connection portion 121 and the current collector connection portion 122 may be located on opposite sides of the bend 123. The auxiliary terminal block 120 may have a bend 123 with a 90-degree bend, such that the terminal block connection portion 121 and the current collector connection portion 122 may become perpendicular to each other around the bend 123.

[0083] Alternatively, the current collector 130 can be formed by bending a single plate. The current collector 130 includes an electrode connection portion 131 and a terminal connection portion 132 that is bent and extends from the top end of the first electrode connection portion 131. The width of the electrode connection portion 131 may be smaller than the width of the terminal connection portion 132. The electrode connection portion 131 may be provided on only one side around the centerline of the width of the electrode connection portion 131 extending from the terminal connection portion 132. This is to facilitate soldering between the electrode connection portion 131 of the current collector 130 and the auxiliary terminal piece 120 via electrode tabs 114 and 115 located at the center in the width direction of the electrode assembly 10. The electrode connection portion 131 of the current collector 130 may be longer than the current collector connection portion 122 of the auxiliary terminal piece 120. That is, the current collector connection portion 122 of the auxiliary terminal piece 120 may be soldered to surround only a portion of the electrode connection portion 131 of the current collector 130.

[0084] With the current collector connection 122 of the auxiliary connector 120 in contact with the electrode connection 131 of the current collector 130, the auxiliary connector 120 and the current collector 130 can be welded together and connected. Here, the bend 123 can be kept in close contact with one side surface of the electrode connection 131. That is, with the inner surface 123a of the bend 123 of the auxiliary connector 120 in contact with one side surface of the electrode connection 131 and the inner surface 122a of the current collector 122 in contact with the inner surface 131a of the electrode connection 131, the auxiliary connector 120 and the current collector 130 can be welded together. The current collector connection 122 can be connected to the electrode connection 131 by laser welding, thereby improving safety and reducing welding failures that may occur during ultrasonic welding.

[0085] Figure 6 Show Figure 5b An enlarged view of an example of the weld between the current collector and the auxiliary connector shown. The laser welding between the current collector connection 122 and the electrode connection 131 will be described below.

[0086] Preferably, the laser welding portion 124 for connecting the current collector connection portion 122 and the electrode connection portion 131 may include a linear welding portion 124a that is straight and spaced at a predetermined distance from the bend portion 123 of the auxiliary connecting piece 120, and a circular welding portion 124b that has an end overlapping with the linear welding portion 124a. Here, the linear welding portion 124a may be spaced from the bend portion 123 by at least approximately 0.8 mm to approximately 1.2 mm. Preferably, when the electrode connecting pieces 114 and 115 have a thickness of approximately 0.4 mm to approximately 0.5 mm, the linear welding portion 124a may be spaced from the bend portion 123 by at least approximately 0.8 mm to approximately 1.2 mm.

[0087] When the distance between the linear welded portion 124a and the bent portion 123 is less than 0.8 mm, due to the fatigue load (vibration energy) generated during ultrasonic welding of the auxiliary welding piece 120 and the electrode welding pieces 114 and 115, fracture or breakage may occur between the current collector connection portion 122 and the electrode connection portion 131. Figure 7 As shown in Figure A, as the linear weld portion 124a gets closer to the bend portion 123, the breakage between the auxiliary connector 120 and the current collector 130 may occur more severely during ultrasonic welding between the auxiliary connector 120 and the electrode connectors 114 and 115.

[0088] Furthermore, when the distance between the linear welding portion 124a and the bending portion 123 is greater than 1.2 mm, during the bending of the auxiliary welding piece 120 and the electrode assembly 110 after the ultrasonic welding auxiliary welding piece 120 and the electrode welding pieces 114 and 115, the auxiliary welding piece 120 may rise instead of being bent together with the electrode connection portion 131 that is in close contact with it. Figure 8 As shown, the electrode plates of the extruded electrode terminals 114 and 115 may be squeezed.

[0089] Furthermore, when the electrode tabs 114 and 115 have a thickness of approximately 0.5 mm to approximately 0.7 mm, the linear weld portion 124a can be spaced from the bend portion 123 by a distance of approximately 1.2 mm to approximately 1.8 mm. Here, when the distance between the linear weld portion 124a and the bend portion 123 is less than 1.2 mm, due to the fatigue load (vibration energy) generated during ultrasonic welding between the auxiliary tab 120 and the electrode tabs 114 and 115, a breakage may occur between the current collector connection portion 122 and the electrode connection portion 131, such as... Figure 7As shown in Figure A. Additionally, when the distance between the linear welding portion 124a and the bending portion 123 is greater than 1.8 mm, during the bending of the auxiliary welding piece 120 and the electrode assembly 110 after the ultrasonic welding auxiliary welding piece 120 and electrode welding pieces 114 and 115, the auxiliary welding piece 120 may rise instead of being bent together with the electrode connection portion 131 in close contact with it, as shown in Figure A. Figure 8 As shown, the electrode plates of the extruded electrode terminals 114 and 115 may be squeezed.

[0090] In other words, the linear welding section 124a can vary according to the thickness of the electrode terminals 114 and 115 of the electrode assembly 110 in order to prevent cracking or electrode plate compression during bending after welding the auxiliary terminals 120 and the electrode terminals 114 and 115.

[0091] Furthermore, the circular weld portion 124b may be located within the current collector connection portion 122 of the auxiliary connector 120, and one end of one side of the circular weld portion 124b may contact the linear weld portion 124a. Here, the welding time of the laser weld portion 124 (i.e., the linear weld portion 124a and the circular weld portion 124b) may be any one in the range of approximately 0.2 seconds to approximately 0.3 seconds. Additionally, the laser welding amplitude of the laser weld portion 124 (i.e., the linear weld portion 124a and the circular weld portion 124b) may be any one in the range of approximately 40 μm to approximately 50 μm.

[0092] In addition, although in Figure 6 Three circular weld portions 124 are shown, but the invention is not limited to this number. However, the distance between each circular weld portion 124b can be at least about 1.0 mm.

[0093] Furthermore, the linear weld portion 124a may extend longer than the current collector connection portion 122. Preferably, the start and end points of the linear weld portion 124a may be located within the electrode connection portion 131 of the current collector portion 130. This enables uniform welding of the linear weld portion 124a, thereby ensuring that the start and end points of the linear weld portion 124a are located within the electrode connection portion 131 of the current collector portion 130.

[0094] Figure 9 Show Figure 5b Another enlarged view of the welded joint between the current collector and the auxiliary terminal block. Referring below... Figure 9 Another example of laser welding is described between the current collector connection 122 and the electrode connection 131.

[0095] Preferably, the laser welding portion 124 used to connect the current collector connection portion 122 and the electrode connection portion 131 to each other may include a circular welding portion 124 spaced at a predetermined distance from the bent portion 123 of the auxiliary connector 120.

[0096] Furthermore, the circular welding portion 124 can be located within the current collector connection portion 122 of the auxiliary connector 120. Here, the welding time of the circular welding portion 124 can be any one in the range of approximately 0.3 seconds to approximately 0.4 seconds. Additionally, the laser welding amplitude of the circular welding portion 124 can be any one in the range of approximately 40 μm to approximately 40 μm. Therefore, when the current collector connection portion 122 of the auxiliary connector 120 and the electrode connection portion 131 of the current collector 130 are welded solely through the circular welding portion 124 without utilizing a linear welding portion, the welding time and welding amplitude can be increased, thereby achieving a strong weld.

[0097] Furthermore, since welding is performed solely through the circular weld portion 124, the circular weld portion 124 can be spaced from the bent portion 123 by at least approximately 1.5 mm to approximately 1.8 mm to prevent breakage due to fatigue loads (vibration energy) generated during ultrasonic welding of the auxiliary welding tab 120 and the electrode welding tabs 114 and 115. In other words, when welding is performed solely through the circular weld portion 124, to prevent breakage due to fatigue loads generated during ultrasonic welding, the circular weld portion 124 is preferably spaced at a relatively large distance from the bent portion 123 compared to when a linear weld portion is provided.

[0098] Here, when the distance between the circular welded portion 124 and the bent portion 123 is less than 1.5 mm, due to the fatigue load (vibration energy) generated during ultrasonic welding between the auxiliary connecting piece 120 and the electrode connecting pieces 114 and 115, a crack may occur between the current collector connection portion 122 and the electrode connection portion 131, such as... Figure 7 As shown in Figure A. Additionally, when the distance between the circular welded portion 124 and the bent portion 123 is greater than 1.8 mm, during the bending of the auxiliary welding piece 120 and the electrode assembly 110 after ultrasonic welding of the auxiliary welding piece 120 and electrode welding pieces 114 and 115, the auxiliary welding piece 120 may rise, as shown in Figure A. Figure 8 As shown, the electrode plates of the extruded electrode terminals 114 and 115 may be squeezed.

[0099] See Figure 10 ,exist Figure 1 The illustration shows an example of ultrasonic welding between auxiliary terminals and electrode terminals during the manufacturing process of a secondary battery. In the following text, reference will be made to... Figure 10The welding between the current collector connection 122 and the electrode connection 131 is described. Here, auxiliary connector 120 refers to the first auxiliary connector 120, and electrode connector 114 refers to the first electrode connector 114. This also applies to the second auxiliary connector 150 and the second electrode connector 115.

[0100] After the auxiliary connector 120 and the current collector 130 are laser welded, with one side surface of the connector 121 of the auxiliary connector 120 in contact with one side surface of the electrode connector 114, the connector 121 and the electrode connector 114 can be ultrasonically welded together by pressure and vibration applied from the ultrasonic welding head 10. Here, the ultrasonic welding head 10 can perform welding in the direction from the connector 121 of the auxiliary connector 120 to the electrode connector 114. To prevent damage to the electrode connector 114 which is a thin film, the connector 121 and the electrode connector 114 can be ultrasonically welded with the ultrasonic welding head 10 located on one side of the connector 121 of the auxiliary connector 120 which is a single board. Here, the side surface of the electrode assembly 110 (from which the electrode connector 114 protrudes) can be positioned adjacent to the current collector 122.

[0101] Furthermore, after the connector 121 and electrode connector 114 are ultrasonically welded together, the connector 121 and electrode connector 114 can be bent toward the electrode connector 131 of the current collector 130. Here, the connector 121 and electrode connector 114 can be bent toward the electrode connector 131 to contact the outer surface 131b opposite to the inner surface 131a of the electrode connector 131 welded to the current collector connector 122. That is, the electrode connector 131 of the current collector 130 can be located between the current collector connector 122 and the connector 121 of the auxiliary connector 120. In addition, the bending portion 123 of the auxiliary connector 120 is bent 180 degrees, so that the current collector connector 122 and the connector 121 can become parallel to each other. That is, the auxiliary connector 120 can be bent in a "U" shape by the bending portion 123.

[0102] In the secondary battery 100, the auxiliary connecting piece and the current collector, both made of a single board, are welded by a high-intensity laser, thereby preventing damage caused by fatigue loads that may occur during ultrasonic welding of the electrode connecting piece and the auxiliary connecting piece. Furthermore, the secondary battery 100 includes an auxiliary connecting piece made of a flexible yet rigid material, thereby preventing the welded portion of the electrode connecting piece and the auxiliary connecting piece from breaking during bending after they have been welded together.

[0103] Although the foregoing embodiments have been described to practice the secondary battery and method for manufacturing the secondary battery according to the invention, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims.

[0104] Industrial applicability

[0105] Various embodiments of the present invention relate to a secondary battery and a method for manufacturing the secondary battery.

Claims

1. A secondary battery, comprising: Electrode assembly with electrode terminals; The auxiliary terminal block is a metal plate that is mechanically and electrically connected to the electrode terminal block; as well as The auxiliary terminal block is mechanically and electrically connected to its current collection section. The auxiliary connector includes: The connector portion of the electrode connector is welded to the electrode connector; A current collector connection portion welded to the current collector and disposed parallel to the terminal block connection portion; and A bent portion, which connects the terminal block connection portion and the current collector connection portion and surrounds one side of the current collector portion. The bent portion is located between the current collector and the electrode terminal piece, and The electrode terminals are L-shaped, and the auxiliary terminals are U-shaped.

2. The secondary battery according to claim 1, wherein the current collector connection has a laser-welded portion connected to the current collector by laser welding.

3. The secondary battery according to claim 2, wherein the laser-welded portion comprises: A straight, linear welded portion spaced a predetermined distance from the bent portion; as well as A circular weld portion having an end that overlaps with the linear weld portion.

4. The secondary battery according to claim 3, wherein when the electrode terminal has a thickness of 0.4 mm to 0.5 mm, the linear weld portion and the bent portion are spaced apart by a distance of at least 0.8 mm to 1.2 mm.

5. The secondary battery according to claim 3, wherein when the electrode terminal has a thickness of 0.5 mm to 0.7 mm, the linear weld portion and the bent portion are spaced apart by a distance of at least 1.2 mm to 1.8 mm.

6. The secondary battery according to claim 3, wherein the length of the linear welded portion is greater than the length of the current collector connection portion, and the start and end points of the linear welded portion are located in the current collector portion.

7. The secondary battery according to claim 2, wherein the laser-welded portion is a circular welded portion, which is circular and spaced at least 1.5 mm to 1.8 mm away from the bent portion.

8. The secondary battery according to claim 1, wherein the auxiliary terminal is made of 1050-O aluminum or 1100-O copper with high rigidity and ductility.

9. A method for manufacturing a secondary battery, the method comprising the following steps: An auxiliary terminal block is prepared by bending the auxiliary terminal block, which is a flat rectangular single plate, by 90 degrees. The auxiliary terminal block has a terminal block connection portion and a current collection connection portion located on the opposite side of the bent portion. Laser welding is performed while the inner surface of the current collector connection is in contact with the inner surface of the current collector. The connecting portion of the terminal block is ultrasonically welded to the electrode terminal block of the electrode assembly; and Bend the connector portion and the electrode connector to make them contact the outer surface of the current collector. In the manufactured secondary battery, the bent portion is located between the current collector and the electrode terminal piece, the electrode terminal piece has an L-shape, and the auxiliary terminal piece has a U-shape.

10. The method of claim 9, wherein in the step of performing laser welding, a linear weld portion and a circular weld portion are formed, the linear weld portion being straight and spaced at least 0.8 mm to 1.8 mm from the bent portion, and the circular weld portion being circular and having an end overlapping the linear weld portion.

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