Secondary battery manufacturing method and secondary battery manufacturing apparatus used therein

Abstract

The present invention relates to a manufacturing method for a secondary battery and a manufacturing apparatus for a secondary battery used therein, and more particularly to a manufacturing method for a secondary battery that manufactures a secondary battery including a plurality of electrode tabs and electrode leads, and a manufacturing apparatus for a secondary battery used therein. The present invention provides a method for manufacturing a secondary battery, including: a tab-lead laminate welding step of welding a tab-lead laminate in which a plurality of electrode tabs and electrode leads are stacked, to connect the electrode tabs and the electrode leads; and a tab-lead laminate processing step of continuously applying pressure to a welded portion of the tab-lead laminate along a length direction to process the welded portion.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0015837, filed February 7, 2022, and all contents disclosed in the documents of this Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a method for manufacturing a secondary battery and a manufacturing apparatus for a secondary battery used therein, and more particularly to a method for manufacturing a secondary battery including a plurality of electrode tabs and electrode leads, and a manufacturing apparatus for a secondary battery used therein. [Background technology]

[0003] As portable wireless devices such as video cameras, mobile phones, and portable PCs become lighter and more functional, the demand for secondary batteries as an energy source is rapidly increasing. Among such secondary batteries, lithium secondary batteries, which have high energy density and discharge voltage, have been actively researched and are now widely used commercially.

[0004] Secondary batteries are also attracting attention as a power source for electric vehicles (EVs) and hybrid electric vehicles (HEVs), which are being proposed as a way to solve air pollution caused by existing gasoline and diesel vehicles that use fossil fuels.

[0005] Recently, pouch-type batteries, which have a structure in which a stack-type or stack / fold-type electrode assembly is housed in a pouch-type battery case made of an aluminum laminate sheet, have been attracting much attention due to their low manufacturing cost, small weight, and easy shape modification, and their usage is gradually increasing.

[0006] Such a pouch-type secondary battery typically includes an electrode assembly in which electrode plates are stacked in order with separators interposed therebetween, and a battery case that serves as an outer casing for housing the electrode assembly. The electrode assembly has a plurality of electrode tabs extending from the electrode plates. The electrode tabs can be connected to electrode leads protruding from the battery case, thereby electrically connecting the electrode assembly inside the battery case to an external electrical device or an external secondary battery.

[0007] Meanwhile, the electrode tabs are fixed to each other or connected to an electrode lead by welding. However, after welding the electrode tabs or the electrode tabs to the electrode lead, the surface of the weld becomes relatively rough, as shown in FIG. 1, and surface tensile residual stress is added due to the welding. In this case, the roughened surface in a fatigue fracture environment provides a site for microcrack initiation, and the surface tensile residual stress acts as a driving force that promotes the growth and propagation of the microcracks. This causes the weld to fracture earlier, which reduces the reliability of the product.

[0008] Therefore, in the past, attempts were made to eliminate the surface roughness of the welded portions by pressing the welded portions after welding multiple electrode tabs or multiple electrode tabs and an electrode lead, but even in this case, there was a limit to the improvement of surface characteristics such as the degree of surface roughness and the length and magnitude of surface compressive residual stress. Therefore, a technology that can solve the above problems is currently needed. Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been devised to solve the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing a secondary battery that can effectively process the welding points between the electrode tab and the electrode lead, and a secondary battery manufacturing apparatus used therefor. [Means for solving the problem]

[0010] The present invention provides a method for manufacturing a secondary battery, including: a tab-lead laminate welding step of welding a tab-lead laminate in which a plurality of electrode tabs and electrode leads are stacked together, to connect the plurality of electrode tabs and the electrode leads; and a tab-lead laminate processing step of processing the welded portions of the tab-lead laminate by continuously applying pressure along a length direction to the welded portions.

[0011] A plurality of shape-deformed portions, which are deformed by welding, may be formed in at least one direction at the welded portion of the tab-lead laminate, and the processing of the tab-lead laminate may process the welded portion by sequentially applying pressure to the plurality of shape-deformed portions in a direction in which the plurality of shape-deformed portions are formed.

[0012] The tab-lead laminate processing step can be performed by a roll burnishing or ball burnishing process.

[0013] The tab-lead laminate processing step can apply a pressure of 100 kgf or more to the welding points.

[0014] The tab-lead stack welding step can be performed by ultrasonic welding or laser welding.

[0015] In addition, the method for manufacturing a secondary battery according to the present invention may further include, before the tab-lead stack welding step, an electrode tab stack in which a plurality of electrode tabs are stacked is welded to connect the plurality of electrode tabs.

[0016] In addition, the method for manufacturing a secondary battery according to the present invention may further include, between the electrode tab laminate welding step and the tab-lead laminate welding step, an electrode tab laminate processing step of processing the welded portion of the electrode tab laminate by continuously applying pressure along a length direction.

[0017] At the welding points of the electrode tab laminate, a plurality of shape-deformed portions, which are deformed by welding, are formed along at least one direction, and the electrode tab laminate processing step can process the welding points by sequentially applying pressure to the plurality of shape-deformed portions along the direction in which the shape-deformed portions are formed.

[0018] In addition, the method for manufacturing a secondary battery according to the present invention may further include, after the tab-lead laminate processing step, a tape attaching step of attaching an insulating tape to a welding portion of the tab-lead laminate.

[0019] Meanwhile, the present invention provides a secondary battery manufacturing apparatus for processing a welding portion of at least one of a tab-lead laminate in which a plurality of electrode tabs and electrode leads are stacked, and an electrode tab laminate in which a plurality of electrode tabs are stacked, the secondary battery manufacturing apparatus including: a main body; and a processing unit installed in the main body for continuously applying pressure to the welding portion to process it.

[0020] The processing unit may include a pressure unit that applies pressure to the welding location while rotating and moving, and a support unit that rotatably supports the pressure unit.

[0021] The pressure unit may include a roller or a ball.

[0022] The material of the pressure member may be iron or ceramic. [Effects of the Invention]

[0023] The present invention effectively reduces the surface roughness of the welded portion by continuously applying pressure along the length of the welded portion of the tab-lead laminate or electrode tab laminate, thereby suppressing the expansion of microcracks at the welded portion.

[0024] Furthermore, the present invention effectively applies surface residual stress to the welded portion of the tab-lead laminate or electrode tab laminate by continuously pressurizing the welded portion along the length, thereby mitigating the expansion and growth of microcracks and increasing the fatigue strength, fatigue limit, and weld tensile strength of the welded object. [Brief explanation of the drawings]

[0025] [Figure 1] 10 is an image showing the state of the welded portion after welding of the electrode tab laminate. [Figure 2] 3 is a flowchart showing a flow of a method for manufacturing a secondary battery according to the first embodiment of the present invention. [Figure 3] FIG. 10 is a perspective view showing an apparatus for manufacturing a secondary battery according to a second embodiment of the present invention. [Figure 4] 4 is a conceptual diagram showing how the secondary battery manufacturing apparatus of FIG. 3 sequentially applies pressure to the welded portions of the tab-lead laminate. FIG. [Figure 5a] 1 is a graph comparing residual stress values ​​of a tab-lead laminate after a conventional method for manufacturing a secondary battery and a method for manufacturing a secondary battery according to the present invention; [Figure 5b] 10 is a graph comparing the height of a deformed portion of a tab-lead laminate after a conventional method for manufacturing a secondary battery and a method for manufacturing a secondary battery according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The present invention will now be described in detail with reference to the accompanying drawings, in order to enable those skilled in the art to easily carry out the present invention. However, the present invention may be embodied in various different forms and should not be construed as being limited to the following embodiments.

[0027] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the explanation or related known technologies that may obscure the gist of the present invention are omitted, and in this specification, when referring to components in each drawing, the same or similar reference symbols are used throughout the specification for the same or similar components.

[0028] Furthermore, the terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors can appropriately define the concepts of terms in order to best explain their inventions.

[0029] Secondary battery manufacturing method The present invention provides a method for manufacturing a secondary battery, including a tab-lead laminate welding step (S30) of welding a tab-lead laminate 100, in which a plurality of electrode tabs and electrode leads are stacked, to connect the electrode tabs and the electrode leads, and a tab-lead laminate processing step (S40) of processing the welded portion W of the tab-lead laminate 100 by continuously applying pressure along the length direction.

[0030] First, the tab-lead stack welding step (S30) is a step of welding the tab-lead stack 100, in which a plurality of electrode tabs and electrode leads are stacked, to connect the electrode tabs and the electrode leads, and can be performed by various methods.

[0031] Specifically, the tab-lead stack welding step (S30) may be performed by welding at least one region of the overlapping portions of the electrode tab and the electrode lead to weld and join the electrode tab and the electrode lead. Here, the tab-lead stack welding step (S30) may be performed by various welding methods, such as ultrasonic welding or laser welding.

[0032] The tab-lead laminate welding step (S30) can form a welded area W of a predetermined size on the tab-lead laminate 100. Here, the welded area W can be understood as a concept that includes not only the area on the tab-lead laminate 100 where the electrode tab and electrode lead are directly connected by welding, but also the area indirectly affected by welding, such as deformation of the external shape or deformation of the connection structure between internal metals. In addition, the area on the tab-lead laminate 100 other than the welded area W can be defined as an unwelded area N below.

[0033] Here, the welded portion W may be a portion whose surface shape is deformed by pressure and / or heat during welding. For example, a plurality of shape-deformed portions a, which are deformed by welding, may be formed along at least one direction on the surface of the welded portion W. Here, the shape-deformed portions a are portions on the tab-lead laminate 100 whose shape is deformed by welding heat, pressure, vibration, etc., and may be understood as portions that protrude and / or are recessed from at least one surface of the tab-lead laminate 100.

[0034] Such a shape deformation portion a increases the surface roughness of the tab-lead laminate 100, generates tensile residual stress, causes stress concentration, and leads to the occurrence of microcracks, which has a fatal impact on the reliability of the semi-finished product.

[0035] Therefore, the present invention effectively prevents the above-mentioned problems by performing the tab-lead laminate processing step (S40) after the tab-lead laminate welding step (S30), as shown in FIG.

[0036] The tab-lead laminate processing step (S40) is a step of continuously pressing the welding point W of the tab-lead laminate 100 along the length direction to process the welding point W, and can be performed by various methods. Here, the welding point W can be pressed with various pressures, for example, a pressure of 100 kgf or more.

[0037] Specifically, in the tab-lead laminate processing step (S40), a processing unit 20 (described later) applies pressure to the welding points W of the tab-lead laminate 100 in a vertical direction (a direction parallel to the Z axis in FIG. 3) and moves horizontally along the length direction of the welding points W (X direction in FIG. 3), thereby processing the welding points W of the tab-lead laminate 100. However, it goes without saying that the tab-lead laminate processing step (S40) is not limited to the processing unit 20 moving horizontally along the length direction of the welding points W (X direction in FIG. 3), and may also move horizontally along the width direction of the welding points W (Y direction in FIG. 3).

[0038] Here, when a plurality of shape deformation portions a are formed at the welding point W, the tab-lead laminate processing step (S40) can process the welding point W by continuously pressing the plurality of shape deformation portions a in the forming direction of the shape deformation portions a. For example, as shown in Fig. 4, the tab-lead laminate processing step (S40) can process the welding point W of the tab-lead laminate 100 while a processing unit 20 (described later) moves and presses along the forming direction of the shape deformation portions a (X direction in Fig. 4).

[0039] Therefore, the tab-lead laminate processing step (S40) can apply pressure to the welding area W for a relatively long period of time compared to a press process that instantaneously presses the entire area of ​​the welding area W, and can provide shear deformation simultaneously with compressive deformation, thereby effectively imparting compressive residual stress in the thickness direction (Z direction in FIG. 3) of the tab-lead laminate 100 and significantly reducing surface roughness. Here, while the press process can pressurize the welding area W for about 0.2 seconds, the tab-lead laminate processing step (S40) according to the present invention can apply pressure to the welding area W for 0.2 seconds or more.

[0040] The tab-lead laminate processing step (S40) can be performed by a roll burnishing or ball burnishing process, etc. Here, the moving path, moving speed, size, and shape of the rolls and balls can be variously set depending on the required process time, number of times of processing, etc.

[0041] For example, the tab-lead laminate processing step (S40) may perform roll burnishing or ball burnishing at least once on the welding portion W. Specifically, the tab-lead laminate processing step (S40) may perform a roll burnishing or ball burnishing process by reciprocating a roll and a ball on the welding portion W. Here, the tab-lead laminate processing step (S40) may perform roll burnishing or ball burnishing not only on the welding portion W but also on the unwelded portion N.

[0042] Furthermore, in the tab-lead laminate processing step (S40), the size of the rolls can be adjusted to adjust the pressing area of ​​the welding points W. That is, in the tab-lead laminate processing step (S40), the size of the rolls can be set relatively small to press the welding points W more precisely, or the size of the rolls can be set relatively large to press the welding points W quickly, thereby shortening the processing time. In this case, it goes without saying that the size of the rolls can be adjusted depending on the number and spacing of the shape deformation portions a described above.

[0043] Meanwhile, after the tab-lead laminate processing step (S40), a tape attaching step (S50) of attaching an insulating tape to the welding point W of the tab-lead laminate 100 may be performed.

[0044] Here, the tape attaching step (S50) may be performed by attaching insulating tape to the welding point W of the tab-lead laminate 100 to prevent the welding point W from being exposed to the outside and being damaged.

[0045] Meanwhile, before the tab-lead stack welding step (S30), an electrode tab stack welding step (S10) of welding and joining a plurality of electrode tabs may be performed.

[0046] Specifically, the electrode tab stack welding step (S10) is a step of welding an electrode tab stack (not shown) in which a plurality of electrode tabs are stacked, thereby connecting the plurality of electrode tabs, and can be performed by various methods.

[0047] Specifically, the electrode tab stack welding step (S10) may be performed by welding at least one region of the stacked electrode tabs to weld the electrode tabs together. Here, the electrode tab stack welding step (S10) may be performed using various welding methods, such as ultrasonic welding or laser welding.

[0048] The electrode tab laminate welding step (S10) can form a welded area W of a predetermined size on the electrode tab laminate, similar to the above-described tab-lead laminate welding step (S30). Here, the welded area W can be understood as a concept that includes not only areas on the electrode tab laminate where the electrode tabs are directly joined to each other by welding, but also areas that are indirectly affected by welding, such as deformation of the external shape or deformation of the joining structure between internal metals, etc. Furthermore, areas on the electrode tab laminate other than the welded area W can be defined as unwelded areas N below.

[0049] Here, the welded portion W may be a portion whose surface shape is deformed by pressure and / or heat applied during welding. For example, a plurality of deformed portions a, which are deformed by welding, may be formed along at least one direction on the surface of the welded portion W. Here, the deformed portions a are portions on the electrode tab laminate whose shape is deformed by welding heat, pressure, vibration, etc., and may be understood as portions that protrude and / or are recessed from at least one surface of the electrode tab laminate.

[0050] Such shape deformation portion a increases the surface roughness of the electrode tab laminate, generates tensile residual stress, causes stress concentration, and leads to the occurrence of microcracks, which has a fatal impact on the reliability of the semi-finished product.

[0051] Therefore, as shown in FIG. 2, the present invention effectively prevents the above-mentioned problems by performing the electrode tab laminate processing step (S20) after the electrode tab laminate welding step (S10).

[0052] The electrode tab laminate processing step (S20) is a step of continuously applying pressure to the welding point W of the electrode tab laminate along the length direction between the electrode tab laminate welding step (S10) and the tab-lead laminate welding step (S30) to process the welding point W, and can be performed by various methods. Here, the welding point W can be pressed at various pressures, for example, at a pressure of 100 kgf or more.

[0053] Specifically, the electrode tab laminate processing step (S20) may process the welding point W of the electrode tab laminate by vertically pressing the welding point W of the electrode tab laminate and moving horizontally along the length of the welding point W.

[0054] However, it goes without saying that the electrode tab laminate processing step (S20) is not limited to the processing unit 20 moving horizontally along the length direction of the welding area W, but can also move horizontally along the width direction of the welding area W.

[0055] Here, when a plurality of shape deformation portions a are formed at the welding point W, the electrode tab laminate processing step (S20) can process the welding point W by continuously pressurizing the plurality of shape deformation portions a along the formation direction of the shape deformation portions a. For example, in the electrode tab laminate processing step (S20), a processing unit 20 (described later) can process the welding point W of the electrode tab laminate while pressing and moving along the formation direction of the shape deformation portions a.

[0056] As a result, the electrode tab laminate processing step (S20) can apply pressure to the welding points W for a relatively long period of time compared to a press process that instantaneously pressurizes the welding points W, and can provide shear deformation at the same time as compressive deformation. This makes it possible to effectively impart compressive residual stress in the thickness direction of the electrode tab laminate, thereby significantly reducing surface roughness.

[0057] The electrode tab laminate processing step (S20) may be performed by a roll burnishing or ball burnishing process, etc. Here, the moving path, moving speed, size, and shape of the rolls and balls may be variously set depending on the required process time, number of treatments, etc.

[0058] For example, the electrode tab laminate processing step (S20) may involve performing roll burnishing or ball burnishing at least once on the welding portion W. Specifically, the electrode tab laminate processing step (S20) may involve performing a roll burnishing or ball burnishing process by reciprocating a roll and a ball on the welding portion W. Here, the electrode tab laminate processing step (S20) may involve performing roll burnishing or ball burnishing not only on the welding portion W but also on the unwelded portion N.

[0059] Furthermore, in the electrode tab laminate processing step (S20), the size of the rolls can be adjusted to adjust the pressing area of ​​the welding points W. That is, in the electrode tab laminate processing step (S20), the size of the rolls can be set relatively small to more precisely press the welding points W, or the size of the rolls can be set relatively large to quickly press the welding points W, thereby shortening the processing time. In this case, it goes without saying that the size of the rolls can be adjusted depending on the number and spacing of the shape deformation portions a described above.

[0060] Secondary battery manufacturing equipment Meanwhile, the present invention provides a secondary battery manufacturing apparatus 1 for processing a welding point W of at least one of a tab-lead laminate 100 in which a plurality of electrode tabs and electrode leads are stacked and an electrode tab laminate in which a plurality of electrode tabs are stacked, the secondary battery manufacturing apparatus 1 including a main body 10 and a processing unit 20 installed on the main body 10 and for processing the welding point W by continuously applying pressure.

[0061] The above-described secondary battery manufacturing apparatus 1 can be installed at various positions from the tab-lead laminate 100 and the electrode tab laminate. For example, the secondary battery manufacturing apparatus 1 may be installed above, below, or both above and below the tab-lead laminate 100 and the electrode tab laminate.

[0062] Here, the main body 10 is configured to have the above-mentioned processing unit 20 installed therein, and may have various configurations. For example, the main body 10 may include a moving device (not shown) that allows the processing unit 20 to move. Here, the moving device may be configured with a hydraulic cylinder or the like, and may be connected to and controlled by an industrial computer or the like via wired or wireless communication.

[0063] The processing unit 20 is installed on the main body 10 and is configured to continuously apply pressure to the welding point W to process it, and various configurations are possible.

[0064] Here, the processing unit 20 can perform pressure processing not only on the welded portion W but also on the boundary between the welded portion W and the unwelded portion N, thereby enabling the processing area to be expanded.

[0065] The processing unit 20 may have various structures. For example, the processing unit 20 may include a pressure unit 21 that applies pressure to the welding point W while rotating, and a support unit 22 that rotatably supports the pressure unit 21.

[0066] Here, the pressure unit 21 is configured to apply pressure to the welding point W while rotating, and various configurations are possible.

[0067] For example, the pressure unit 21 may include a roller or a ball so as to rotate and pressurize the welding point W. However, the structure of the pressure unit 21 is not limited to the roller or ball, and any structure may be used as long as it can rotate and pressurize the welding point W.

[0068] The pressure member 21 may be made of various materials. For example, the pressure member 21 may be made of iron or ceramic material to minimize wear due to contact with the welding point W. More specifically, the pressure member 21 may be made of cemented carbide tool steel or tool ceramic.

[0069] On the other hand, the support part 22 is configured to rotatably support the pressure part 21, and various configurations are possible.

[0070] For example, one end of the support portion 22 rotatably supports the pressure portion 21, and the other end is connected to the main body 10 so that the pressure portion 21 can move along the welding point W while applying pressure.

[0071] Meanwhile, the quantitative effects of the present invention can be more specifically confirmed with reference to Figures 5a and 5b, where Figure 5a is a graph comparing the residual stress values ​​of the tab-lead laminate 100 after the conventional secondary battery manufacturing method and the secondary battery manufacturing method of the present invention, and Figure 5b is a graph comparing the surface roughness of the tab-lead laminate 100 after the conventional secondary battery manufacturing method and the secondary battery manufacturing method of the present invention.

[0072] Here, the conventional method for manufacturing a secondary battery involves welding the tab-lead laminate 100 and then performing a press process to instantly press the entire area of ​​the welding point W of the tab-lead laminate 100, whereas the method for manufacturing a secondary battery according to the present invention can be understood as performing the above-mentioned roll burnishing process on the welding point W of the tab-lead laminate 100 after performing the welding step of the tab-lead laminate 100.

[0073] First, referring to Figure 5a, the change in residual stress of the tab-lead laminate 100 produced by the conventional secondary battery manufacturing method can be compared with the change in residual stress of the tab-lead laminate 100 produced by the secondary battery manufacturing method of the present invention. It should be noted that the values ​​for the tab-lead laminate 100 produced by the conventional secondary battery manufacturing method are represented on the graph as "Press_0.2s" or "Press_1.0s," while the values ​​for the tab-lead laminate 100 produced by the secondary battery manufacturing method of the present invention are represented as "Burnishing_0.2s" or "Burnishing_1.0s." It should also be noted that tensile residual stress is represented as a positive value, and compressive residual stress is represented as a negative value.

[0074] 5a, the maximum absolute value of the compressive residual stress of the tab-lead laminate 100 after the conventional secondary battery manufacturing method (Press_0.2s, Press_1.0s) was confirmed to be about 35 MPa. Also, the maximum absolute value of the compressive residual stress of the tab-lead laminate 100 after the secondary battery manufacturing method according to the present invention (Burnishing_0.2s) was confirmed to be about 80 MPa. Also, the maximum absolute value of the compressive residual stress of the tab-lead laminate 100 after the secondary battery manufacturing method according to the present invention (Burnishing_1.0s) was confirmed to be about 70 MPa.

[0075] 5a, comparing the maximum absolute values ​​of compressive residual stress between the conventional secondary battery manufacturing method and the secondary battery manufacturing method of the present invention, it is confirmed that the secondary battery manufacturing method of the present invention can impart approximately twice as much compressive residual stress to the tab-lead laminate 100 as the conventional secondary battery manufacturing method. Furthermore, it was confirmed that the secondary battery manufacturing method of the present invention can impart compressive residual stress not only to the electrode leads but also to the electrode tabs provided below the electrode leads, thereby providing the advantage of more effectively imparting compressive residual stress to the tab-lead laminate 100.

[0076] 5b, the change in height of the shape-deformed portion a when a conventional secondary battery manufacturing method is performed and the change in height of the shape-deformed portion a when a secondary battery manufacturing method according to the present invention is performed can be compared. Here, the height of the shape-deformed portion a can be understood as the maximum protruding height of the shape-deformed portion a before and after the secondary battery manufacturing method is performed. It should also be noted that the values ​​for the tab-lead laminate 100 manufactured by the conventional secondary battery manufacturing method are represented on the graph as Press_0.2s or Press_1.0s, while the values ​​for the tab-lead laminate 100 manufactured by the secondary battery manufacturing method according to the present invention are represented as Burnishing_0.2s or Burnishing_1.0s.

[0077] Specifically, referring to the graph in Figure 5b, after performing the conventional secondary battery manufacturing method (Press_0.2s, Press_1.0s), the height of the shape-deformed portion a was 0.054mm, which was approximately 19.4% smaller than the height of the conventional shape-deformed portion a (0.067mm). Meanwhile, after performing the secondary battery manufacturing method of the present invention (Burnishing_0.2s) for 0.2 seconds, the height of the shape-deformed portion a was 0.035mm, which was approximately 52.2% smaller than the height of the conventional shape-deformed portion a (0.067mm). Furthermore, after performing the secondary battery manufacturing method of the present invention (Burnishing_1.0s) for 1 second, the height of the shape-deformed portion a was 0.020mm, which was approximately 70.1% smaller than the height of the conventional shape-deformed portion a (0.067mm).

[0078] That is, referring to the graph of FIG. 5b, a comparison was made between the change in height of the deformed portion a according to the conventional manufacturing method of a secondary battery and the manufacturing method of a secondary battery of the present invention. As a result, it was confirmed that the manufacturing method of a secondary battery according to the present invention can effectively improve the surface roughness by at least 2.7 times more than the conventional manufacturing method of a secondary battery.

[0079] Furthermore, in the case of conventional secondary battery manufacturing methods, the degree of improvement in surface roughness is unrelated to the process processing time, but in the case of the secondary battery manufacturing method according to the present invention, it has been confirmed that the surface roughness improves in proportion to the process execution time (e.g., 0.2 sec, 1 sec). Therefore, there is an advantage that the degree of improvement in surface roughness can be easily adjusted by adjusting the process execution time.

[0080] The present invention has been described above using limited embodiments and drawings, but the present invention is not limited thereto, and various implementations are possible within the technical spirit of the present invention and the scope of the claims set forth below by a person having ordinary skill in the art to which the present invention pertains. [Explanation of symbols]

[0081] 1. Secondary battery manufacturing equipment 10 Main Unit 20 Processing Department 21 Pressure unit 22 Support part W Welding point N Unwelded area 100 Tab-lead laminate A. Shape transformation part S10 Electrode tab stack welding step S20 Electrode tab laminate processing step S30 Tab-Lead Laminate Welding Step S40 Tab-Lead Laminate Processing Step S50 Tape attachment step

Claims

1. a tab-lead laminate forming step of laminating a plurality of electrode tabs and electrode leads to form a tab-lead laminate; a tab-lead stack welding step of welding the tab-lead stack to connect the plurality of electrode tabs and the electrode leads; a tab-lead laminate processing step of sequentially applying pressure to the welded portions of the tab-lead laminate to process the welded portions; The tab-lead laminate processing step is performed by a roll-burnishing process or a ball-burnishing process; In the method for manufacturing a secondary battery, the rolls in the roll burnishing process or the balls in the ball burnishing process are made of iron or ceramic material.

2. a plurality of shape-deformed portions, the shape of which is deformed by the welding, are formed along at least one direction at the welded portion; 2. The method for manufacturing a secondary battery according to claim 1, wherein the tab-lead laminate processing step processes the welding points by continuously pressing the plurality of shape deformation portions along a direction in which the plurality of shape deformation portions are formed.

3. The method for manufacturing a secondary battery according to claim 1 , wherein the tab-lead laminate processing step applies pressure to the welding points with a pressure of 100 kgf or more.

4. The method for manufacturing a secondary battery according to claim 1 , wherein the tab-lead laminate welding step is performed by ultrasonic welding or laser welding.

5. Before the tab-lead laminate forming step, an electrode tab stack forming step of stacking the plurality of electrode tabs to form an electrode tab stack; The method of manufacturing a secondary battery according to claim 1 , further comprising: an electrode tab stack welding step of welding the electrode tab stack to connect the plurality of electrode tabs.

6. Between the electrode tab stack welding step and the tab-lead stack forming step, The method for manufacturing a secondary battery according to claim 5 , further comprising: a step of processing the electrode tab laminate by sequentially applying pressure to the welding points of the electrode tab laminate to process the welding points.

7. After the tab-lead laminate processing step, The method of claim 1, further comprising the step of attaching an insulating tape to the welded portion of the tab-lead laminate.

8. 1. A secondary battery manufacturing device for processing a welding portion of at least one of a tab-lead laminate in which a plurality of electrode tabs and electrode leads are laminated, and an electrode tab laminate in which a plurality of electrode tabs are laminated, The main body and a processing unit that is installed on the main body and sequentially pressurizes and processes the welding points, The processing unit includes a roller or a ball that rotates and applies pressure to the welding area. The manufacturing apparatus for a secondary battery, wherein the processing part is made of iron or ceramic material.

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