welding jig

Abstract

The present invention relates to a welding jig, which can prevent spatter, which is a foreign matter generated by welding, from flowing into a secondary battery when welding between a current collector plate connected to an electrode assembly inside a can body of a secondary battery and a beading portion which is a portion recessed inward from the can body, and can improve the quality of welding by increasing the pressure between the current collector plate and the beading portion which are objects to be welded. The welding jig according to the present invention relates to a welding jig used in a welding process when manufacturing a secondary battery, and includes a main body and a protrusion extending downward from a lower surface of the main body, having a size corresponding to an upper opening of the secondary battery, and inserted into the upper opening of the secondary battery during the welding process, and a welding hole through which a welding laser passes is formed in a periphery of the protrusion and in an area of ​​the main body corresponding to the periphery of the protrusion, and the protrusion includes a pressing portion around the welding hole for pressing an object to be welded in the secondary battery.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0186536 dated December 23, 2021 and Korean Patent Application No. 10-2022-0178491 dated December 19, 2022, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a welding jig that can prevent spatter, which is foreign matter generated during welding, from flowing into a secondary battery when welding a current collector plate connected to an electrode assembly inside a can body of a secondary battery to a beading portion that is a recessed portion from the can body inward, and can improve welding quality by increasing the pressure between the current collector plate, which is the object to be welded, and the beading portion. [Background technology]

[0003] Depending on the shape of the battery case, secondary batteries are classified into cylindrical batteries and prismatic batteries, in which the electrode assembly is housed in a cylindrical or prismatic metal can, and pouch-type batteries, in which the electrode assembly is housed in a pouch-type case made of an aluminum laminate sheet.

[0004] The electrode assembly housed in the battery case is a chargeable and dischargeable power generating element having a stacked structure of a positive electrode / separator / negative electrode, and can be classified into a jelly roll structure in which a separator is interposed between long sheet-like positive and negative electrodes coated with an active material and wound up, a stack structure in which a number of positive and negative electrodes of a predetermined size are sequentially stacked with a separator interposed therebetween, and a stack / folding type electrode assembly having a structure in which a bicell or full cell in which a predetermined number of positive and negative electrodes are stacked with a separator interposed therebetween is wound up.

[0005] Among these, jelly-roll electrode assemblies are widely used due to their advantages of ease of manufacture and high energy density per weight. A jelly-roll electrode assembly can be fabricated by assembling a laminate of long, sheet-shaped positive and negative electrodes with a separator interposed therebetween, and then winding the sheet in the longitudinal direction while contacting a winding core with one end of the electrode laminate. This jelly-roll electrode assembly can then be inserted into a battery case, which is a cylindrical metal can, to form a cylindrical secondary battery.

[0006] Such cylindrical secondary batteries are designed to have high energy density, and therefore the demand for cylindrical secondary batteries is also on the rise.

[0007] Among these cylindrical secondary batteries, the new size cell (Tabless Cell), which is manufactured without tabs, has five times higher energy density than existing batteries, making it a highly investment-efficient secondary battery.

[0008] In the case of the new Tabless Cell manufactured in this way, the jelly roll electrode assembly, which is welded to the current collector plate, is inserted into the can (see Figure 6), and welding is performed between the beading, which is formed by indenting the upper part of the can, and the current collector plate. However, because this welding work is performed inside the can, there is a problem that spatter, which is foreign matter generated during welding, flows into the can, degrading the quality.

[0009] Furthermore, when welding the current collector plate and the beading, if the beading is not flat or if there is poor contact between the current collector plate and the beading, the welding cannot proceed sufficiently, resulting in problems with the welding quality and the quality of the entire secondary battery. Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been devised to solve the above problems, and an object of the present invention is to provide a welding jig that can prevent spatter, which is foreign matter generated during welding, from flowing into the secondary battery when welding between a current collector plate connected to an electrode assembly inside the can body of a secondary battery and a beading portion, which is a portion recessed inward from the can body, and can improve the quality of welding by increasing the pressure between the current collector plate, which is the object to be welded, and the beading portion. [Means for solving the problem]

[0011] The welding jig according to the present invention relates to a welding jig used in the welding process when manufacturing a secondary battery, and includes a main body and a protrusion extending downward from the underside of the main body, having a size corresponding to the upper opening of the secondary battery, and inserted into the upper opening of the secondary battery during the welding process, and a welding hole through which a welding laser passes is formed in the surrounding portion of the protrusion and in the area of ​​the main body corresponding to the surrounding portion of the protrusion, and the protrusion includes a pressure portion around the welding hole that applies pressure to the object to be welded in the secondary battery.

[0012] The welding hole may have an exit size from which the laser exits that is smaller than the entrance size from which the laser enters.

[0013] The welding hole may have a shape in which the width gradually decreases in the downward direction.

[0014] The welding holes may be formed in pairs at positions that divide the periphery of the protruding portion into four equal parts at 90-degree intervals, resulting in a total of eight through holes.

[0015] The welding holes may be formed at four equal positions at 90-degree intervals around the periphery of the protruding portion, one at each position, for a total of four through holes.

[0016] The pressure applying portion may be a portion of the lower surface of the protrusion that applies pressure to the workpiece.

[0017] The protrusion may include a shielding gas drawing nozzle inside the peripheral portion for drawing the shielding gas into the interior of the secondary battery.

[0018] A shielding gas transfer hole may be formed in the lower part of the protrusion for supplying the shielding gas drawn into the secondary battery into the welding hole.

[0019] The shielding gas transfer hole may be formed in communication with the lower end of the weld hole.

[0020] The lower end of the shielding gas intake nozzle may be positioned a predetermined distance further below the lower end of the weld hole.

[0021] A shielding gas supply pipe for supplying the shielding gas to the shielding gas intake nozzle may be connected to the side surface of the main body.

[0022] The main body may include a frame portion that is a region other than the region where the protrusion is formed, and a fastening hole for fixing may be formed in the frame portion.

[0023] The pressure portion may be a pressure protrusion formed on the lower surface of the protrusion for applying pressure to the object to be welded.

[0024] The pressure protrusion may be formed adjacent to one side or the other side of the weld hole in the circumferential direction of the protrusion.

[0025] The secondary battery is a cylindrical secondary battery, and the protrusion is formed in a columnar shape and can extend downward from the bottom surface of the main body.

[0026] The pressing portion may pressurize the upper surface of the current collector plate to perform welding between the current collector plate connected to the electrode assembly inside the cylindrical secondary battery and the beading portion formed on the can body of the cylindrical secondary battery. [Effects of the Invention]

[0027] The present invention relates to a welding jig that can prevent spatter, which is foreign matter generated during welding, from flowing into the secondary battery when welding between a current collector plate connected to an electrode assembly inside the can body of a secondary battery and a beading portion that is a recessed portion from the can body inward, and can improve welding quality by increasing the pressure between the current collector plate, which is the object to be welded, and the beading portion. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a perspective view showing a welding jig according to a first embodiment of the present invention. [Figure 2] 1 is a front view showing a welding jig according to a first embodiment of the present invention. [Figure 3] 1 is a plan view showing a welding jig according to a first embodiment of the present invention. [Figure 4] FIG. 2 is a bottom view showing the welding jig according to the first embodiment of the present invention. [Figure 5(a)] 4 is a cross-sectional view showing an electrode assembly and a current collector plate connected to the electrode assembly; FIG. [Figure 5(b)] FIG. 6 is a plan view showing the object of FIG. 5(a) as viewed from above. [Figure 6(a)] 4 is a cross-sectional view showing a state in which an electrode assembly connected to a current collecting plate is inserted into a can body of a secondary battery; [Figure 6(b)] FIG. 6 is a plan view showing the object of FIG. 5(a) as viewed from above. [Figure 7] 1 is a cross-sectional view showing a state in which a welding jig according to a first embodiment of the present invention is used in a manufacturing (welding) process of a secondary battery. [Figure 8] FIG. 1 is a perspective view showing only a welding jig and a current collecting plate according to a first embodiment of the present invention. [Figure 9] FIG. 10 is a front view showing a welding jig according to a second embodiment of the present invention. [Figure 10] FIG. 10 is a bottom view showing a welding jig according to a second embodiment of the present invention. [Figure 11]FIG. 10 is a plan view showing a portion of a current collector plate that is pressed by a welding jig according to a second embodiment of the present invention. [Figure 12] FIG. 10 is a plan view showing a welding jig according to a third embodiment of the present invention. [Figure 13] FIG. 10 is a bottom view showing a welding jig according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029]

[0033] 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 many different forms and should not be construed as being limited to the following embodiments.

[0030] 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 unnecessarily obscure the gist of the present invention are omitted, and in adding reference symbols to components in each figure in this specification, the same or similar reference symbols are used for the same or similar components throughout the specification.

[0031] 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 as meanings and concepts that are consistent with the technical idea of ​​the present invention, in accordance with the principle that an inventor can appropriately define the concepts of terms in order to best explain his or her invention.

[0032] Example 1 FIG. 1 is a perspective view of a welding jig according to a first embodiment of the present invention. FIG. 2 is a front view of the welding jig according to the first embodiment of the present invention. FIG. 3 is a plan view of the welding jig according to the first embodiment of the present invention. FIG. 4 is a bottom view of the welding jig according to the first embodiment of the present invention. FIG. 5(a) is a cross-sectional view of an electrode assembly and a current collector plate connected to the electrode assembly. FIG. 5(b) is a plan view of the object of FIG. 5(a) viewed from above. FIG. 6(a) is a cross-sectional view of the electrode assembly connected to the current collector plate inserted into the can body of a secondary battery. FIG. 6(b) is a plan view of the object of FIG. 5(a) viewed from above. FIG. 7 is a cross-sectional view of the welding jig according to the first embodiment of the present invention being used in the manufacturing process of a secondary battery. FIG. 8 is a perspective view of only the welding jig and current collector plate according to the first embodiment of the present invention.

[0033] Hereinafter, a welding jig according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 8. FIG.

[0034] The welding jig 100 according to the first embodiment of the present invention may be a welding jig 100 used in a welding process when manufacturing a secondary battery. The welding jig 100 according to the first embodiment of the present invention may include a main body 110 and a protrusion 120.

[0035] 1 to 4, the body 110 may be a portion that forms the main body of the welding jig 100. The protrusion 120 may be a portion that extends downward (D) from the lower surface 111 of the body. The protrusion 120 may be a portion that is inserted into an opening of the secondary battery during the welding process, and thus the protrusion 120 may have a size that corresponds to the upper opening of the secondary battery. Here, "having a corresponding size" may mean that, if the secondary battery is cylindrical, the diameter of the opening of the secondary battery and the diameter of the protrusion 120 correspond to each other.

[0036] For example, if the secondary battery is a cylindrical secondary battery, the protrusion 120 may be formed in a cylindrical shape and extend downward from the lower surface 111 of the body. If it is not circular, it may mean that its shape, width, etc. are formed correspondingly to allow insertion.

[0037] In the welding jig 100 according to the first embodiment of the present invention, weld holes 121 through which a welding laser passes may be formed in a periphery of the protrusion 120 and in a region of the body 110 corresponding to the periphery of the protrusion 120. That is, the weld holes 121 may be formed in the periphery of the protrusion 120, and weld holes 121 may also be formed in the body 110 to communicate with the weld holes 121 formed in the periphery of the protrusion 120. Specifically, the welding laser must pass through the body 110 and the protrusion 120, and the path through which the laser passes may be the weld holes 121. The weld holes 121 may be formed in pairs at positions dividing the periphery of the protrusion 120 into four equal parts at 90-degree intervals, resulting in a total of eight through holes.

[0038] The protrusion 120 may include a pressure portion 122 around the welding hole 121 that applies pressure to the objects to be welded in the secondary battery. The pressure portion 122 may be a portion on the underside of the protrusion 120 that applies pressure to the objects to be welded. That is, when laser welding is performed by irradiating the objects to be welded with a laser through the welding hole 121, pressure must be applied to bring the two objects to be welded into close contact with each other, and for this reason, a configuration that applies pressure to the objects to be welded may be required. The pressure portion 122 may be the portion that applies pressure to the objects to be welded as needed. Therefore, the pressure portion 122 may be a portion on the underside of the protrusion 120 that is located around the welding hole 121.

[0039] The pressure application portion 122 may be a pressure application surface formed in a flat shape, but is not necessarily limited to a flat shape. As will be discussed in Example 2 below, the pressure application portion 122 may be formed in the shape of a protrusion, and any other shape that allows pressure to be applied effectively and efficiently is also applicable.

[0040] 5 and 6 show a cylindrical secondary battery 1 to which a welding jig 100 according to a first embodiment of the present invention can be applied. In particular, FIGS. 5 and 6 show a welding process in a manufacturing process of a new table cell manufactured without tabs. FIG. 5 shows a current collector 30 being connected by welding to a jelly-roll type electrode assembly 10 inserted into the new table cell. The current collector 30 may be a material welded to the jelly-roll type electrode assembly 10 and may be configured to collect electrons.

[0041] The electrode assembly 10 and current collector plate 30 combination shown in FIG. 5 may be inserted into the can body 20 shown in FIG. 6. After the electrode assembly 10 and current collector plate 30 combination is inserted into the can body 20, a beading portion 21 formed by indenting the upper portion of the can body 20 may be formed on the inside. As a result, the frame portion of the current collector plate 30 may be placed on the top surface of the beading portion 21. In this manner, welding may be performed between the beading portion 21 formed by indenting the upper side of the can and the current collector plate 30. The welding jig 100 according to the first embodiment of the present invention may be, for example, a jig used when welding between the beading portion 21 and the current collector plate 30.

[0042] Figure 7 shows the protrusion 120 extending downward (D) from the underside 111 of the main body being inserted into the upper end opening of the secondary battery 1, and the welding jig 100 according to Example 1 of the present invention performing welding while applying pressure to the upper surface of the current collector plate 30 placed on the upper surface of the beading portion 21.

[0043] 1 to 4 and 7, the pressure applying portion 122 can apply pressure to the upper surface of the current collecting plate 30 in order to perform welding between the current collecting plate 30 connected to the electrode assembly 10 inside the cylindrical secondary battery 1 and the beading portion 21 formed on the can body 20 of the cylindrical secondary battery 1. The pressure applying portion 122 can improve the degree of completion of the welding by increasing the pressure between the current collecting plate 30 and the beading portion 21, which are the objects to be welded.

[0044] 8 is a view showing the welding jig 100 and the current collecting plate 30 to clearly show how the welding jig 100 presses the current collecting plate 30 according to the first embodiment of the present invention. Although welding positions (W) are shown in FIGS. 6 and 8, these welding positions may be positions where the laser passing through the welding holes 121 performs welding. The welding positions (W) may be formed in pairs at positions that divide the periphery of the current collecting plate 30 into four equal parts at 90-degree intervals, resulting in a total of eight welding positions. These positions may correspond to the positions of the welding holes 121.

[0045] As shown in FIG. 7, the welding hole 121 formed through the protrusion 120 and the body 110 may have a shape in which the size of the exit from which the laser exits is smaller than the size of the entrance from which the laser enters.

[0046] The welding hole 121 may have a shape in which its width gradually decreases toward the bottom. The lower end of the welding hole 121 may have a narrow width to prevent the laser from reaching other points, as it must accurately point to the welding point. The upper end of the welding hole 121 may have a wide width to accommodate a wider laser beam. Thus, the welding hole 121 may have a shape in which its width is wide at the top and narrows toward the bottom. For example, the welding hole 121 may have an inverted truncated cone shape. As shown in FIG. 7 , the welding hole 121 may have an outer surface that slopes vertically and an inner surface that slopes gently within the welding hole 121. Of course, the welding hole does not necessarily have to have a shape in which its width continuously narrows, and various embodiments are possible in which the outlet is smaller than the inlet.

[0047] As shown in FIGS. 1 to 4 and 7 , in a welding jig 100 according to a first embodiment of the present invention, a protrusion 120 may include a shielding gas inlet nozzle 130 inside its periphery for injecting a shielding gas into the interior of a secondary battery 1. Here, the shielding gas may refer to an inert or semi-inert gas generally used in welding processes. The shielding gas may serve to block the inflow of atmospheric oxygen during a high-temperature reaction of the welded object. In the first embodiment of the present invention, the shielding gas may be nitrogen gas.

[0048] The shielding gas may be supplied from the outside of the main body 110, and a shielding gas supply pipe 140 may be connected to the side of the main body 110 to supply the shielding gas to the shielding gas inlet nozzle 130. That is, the shielding gas may enter the inside of the main body 110 from the outside of the main body 110 through the shielding gas supply pipe 140, and then enter the inside of the secondary battery 1 through the shielding gas inlet nozzle 130.

[0049] 7, the shielding gas can enter the can body 20 through the shielding gas intake nozzle 130. The shielding gas must form an atmosphere at the welding area (W), so it must move to the welding area. For this reason, a shielding gas moving hole 123 may be formed in the lower part of the protrusion 120.

[0050] The shielding gas transfer hole 123 may be formed in the lower part of the protruding portion 120 and configured to supply the shielding gas drawn into the interior of the secondary battery 1 into the welded hole 121. The shielding gas transfer hole 123 may be formed to communicate with the lower end of the welded hole 121 and supplied directly to the welded portion (see arrow G in FIG. 7). The shielding gas supplied to the welded portion in this manner can then move upward through the welded hole 121 and escape to the outside (see arrow F in FIG. 7).

[0051] As discussed above, the welding jig 100 according to the first embodiment of the present invention has a structure that shields all parts except the laser irradiation part for welding between the current collector plate 30 and the beading part 21 and the shielding gas insertion part for forming the atmosphere during welding, thereby preventing spatter, which is a foreign substance generated by welding, from flowing into the secondary battery 1.

[0052] Furthermore, in the welding jig 100 according to the first embodiment of the present invention, the lower end of the shielding gas supply nozzle 130 may be positioned a predetermined distance lower than the lower end of the welding hole 121. This structure can further prevent spatter, which is foreign matter generated during welding, from flowing into the secondary battery, and can also serve to allow the shielding gas to move smoothly.

[0053] Meanwhile, in the welding jig 100 according to the first embodiment of the present invention, the main body 110 may include a frame 112, which is an area other than the area where the protrusions 120 are formed. The frame 112 may have fastening holes 113 formed therein for fixation. To ensure stable welding during the welding process, the main body 110 and the protrusions 120 must not be shaken, and therefore, the main body 110 and the protrusions 120 can be fixed to a fixing device via the fastening holes 113 to ensure stable welding. As shown in FIGS. 1 and 3, a total of six fastening holes 113 may be formed, for example, three on one side and three on the other side.

[0054] Example 2 Fig. 9 is a front view showing a welding jig according to Example 2 of the present invention. Fig. 10 is a bottom view showing a welding jig according to Example 2 of the present invention. Fig. 11 is a plan view showing a portion of a current collecting plate that is pressed by a welding jig according to Example 2 of the present invention.

[0055] The second embodiment of the present invention is different from the first embodiment in that the protrusion 120 of the welding jig according to the first embodiment of the present invention includes a pressure protrusion 250 .

[0056] The content common to Example 1 will be omitted as much as possible, and the features of the manufacturing method will be mainly described in Example 2. In other words, if content not described in Example 2 is necessary, it is obvious that it may be regarded as the content of Example 1.

[0057] 9 and 10 , a welding jig 200 according to a second embodiment of the present invention relates to a welding jig 200 used in a welding process when manufacturing a secondary battery, and includes a main body 110 and a protrusion 120 that extends downward from a lower surface 111 of the main body, has a size corresponding to the upper opening of the secondary battery, and is inserted into the upper opening of the secondary battery during the welding process. Welding holes 121 through which a welding laser passes are formed around the protrusion 120 and in an area of ​​the main body 110 corresponding to the area around the protrusion 120, and the protrusion 120 includes a pressure portion 122 around the welding hole 121 that applies pressure to an object to be welded in the secondary battery 1.

[0058] Here, the pressure portion 122 may be a pressure protrusion 250 formed on the lower surface of the protrusion 120 to apply pressure to the workpiece. The pressure protrusion 250 may be a portion formed by further protruding in a downward direction (D) from the lower surface of the protrusion 120 adjacent to the welding hole 121. An enlarged view of the pressure protrusion 250 is shown in FIG. 10.

[0059] 9 and 10, the pressure protrusion 250 may be formed adjacent to one or the other side of the welding hole 121 based on the circumferential direction of the protrusion 120. As a result, the pressure protrusion 250 can apply pressure adjacent to one or the other side of the welding position (W) where welding is performed (see FIG. 11).

[0060] The pressure protrusions 250 of the protruding portion 120 may be configured to make point contact rather than surface contact when applying pressure to the workpieces to be welded. Therefore, the pressure protrusions 250 increase the pressure between the current collector plate 30, which is the workpiece to be welded, and the beading portion 21, thereby improving the completeness of the weld and the quality of the weld.

[0061] 11 shows the positions where the pressure protrusions 250 apply pressure on the upper surface of the current collecting plate 30. As shown in Fig. 11, the pressure protrusions 250 may be formed in pairs at positions that divide the periphery of the current collecting plate 30 into four equal parts at 90-degree intervals. When formed in this manner, a total of eight pressure protrusions 250 may be formed.

[0062] Example 3 Fig. 12 is a plan view showing a welding jig according to a third embodiment of the present invention. Fig. 13 is a bottom view showing a welding jig according to the third embodiment of the present invention.

[0063] The third embodiment of the present invention is different from the first embodiment of the present invention in that the welding jig has a different shape, such as the number of welding holes.

[0064] The content common to Example 1 will be omitted as much as possible, and the features of the weld hole will be mainly described in Example 3. In other words, if content not described in Example 3 is necessary, it is obvious that it may be regarded as the content of Example 1.

[0065] In the welding jig 300 according to the third embodiment of the present invention, weld holes 321 through which a welding laser passes may also be formed in the periphery of the protrusion 120 and in the region of the body 110 corresponding to the periphery of the protrusion 120. That is, the weld holes 321 may be formed in the periphery of the protrusion 120, and weld holes 321 may also be formed in the body 110 so as to be in communication with the weld holes 321 formed in the periphery of the protrusion 120. Specifically, the welding laser must pass through the body 110 and the protrusion 120, and the path through which the laser passes may be the weld holes 321. The weld holes 321 may be formed at four equal positions at 90-degree intervals around the periphery of the protrusion 120, one at each position, for a total of four through holes.

[0066] The protrusion 120 may include a pressure portion 122 around the welding hole 321 that applies pressure to the objects to be welded in the secondary battery. The pressure portion 122 may be a portion on the underside of the protrusion 120 that applies pressure to the objects to be welded. That is, during laser welding, when a laser passes through the welding hole 321 and irradiates the objects to be welded, pressure must be applied to bring the two objects to be welded into close contact with each other. For this reason, a configuration that applies pressure to the objects to be welded may be required. The pressure portion 122 may be the portion that applies pressure to the objects to be welded as needed. Therefore, the pressure portion 122 may be a portion on the underside of the protrusion 120 that is located around the welding hole 321.

[0067] Although the present invention has been described above using limited embodiments and drawings, 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]

[0068] 1 Secondary battery 10 Electrode assembly 20 Can body 21 Beading section 30 Current collector plate 100, 200, 300 welding jig 110 Main body 111 Underside of main body 112 Frame 113 Fastening hole 120 Protrusion 121, 321 welding holes 122 Pressurized part 123 Shielding gas transfer hole 130 Shielding gas intake nozzle 140 Shielding gas supply pipe 250 pressure protrusion W Welding position

Claims

1. A welding jig used in a welding process during the manufacture of a secondary battery, a main body, and a protrusion extending downward from the lower surface of the body, having a size corresponding to an upper end opening of the secondary battery, and inserted into the upper end opening of the secondary battery during the welding process; Including, a welding hole through which a welding laser passes is formed in a peripheral portion of the protrusion and in a region of the main body corresponding to the peripheral portion of the protrusion; the protrusion includes a pressure applying portion that applies pressure to an object to be welded in the secondary battery around the welding hole, the protrusion includes a shielding gas drawing nozzle inside the peripheral portion for drawing a shielding gas into the interior of the secondary battery; The welding jig is characterized in that a shielding gas transfer hole is formed in a lower portion of the protrusion for supplying the shielding gas drawn into the interior of the secondary battery into the welding hole.

2. 2. The welding jig according to claim 1, wherein the welding hole has an exit from which the laser beam exits that is smaller than an entrance from which the laser beam enters.

3. The welding jig according to claim 1, wherein the welding hole has a shape in which its width gradually decreases in a downward direction.

4. 2. The welding jig according to claim 1, wherein the welding holes are formed at four equal positions at 90-degree intervals around the periphery of the protrusion, so that a total of four through holes are formed.

5. 2. The welding jig according to claim 1, wherein the welding holes are formed in pairs at positions that divide the peripheral portion of the protrusion into four equal parts at 90-degree intervals, thereby forming a total of eight through holes.

6. The welding jig according to claim 1 , wherein the pressure application portion is a portion of the lower surface of the protrusion that applies pressure to the workpiece.

7. The welding jig according to claim 1 , wherein the shielding gas transfer hole is formed to communicate with a lower end of the welding hole.

8. 2. The welding jig according to claim 1, wherein a lower end of the shielding gas intake nozzle is positioned a predetermined distance below a lower end of the welding hole.

9. The welding jig according to claim 1 , wherein a shielding gas supply pipe is connected to a side surface of the body for supplying the shielding gas to the shielding gas inlet nozzle.

10. the main body portion includes a frame portion that is a region other than a region where the protrusion is formed, The welding jig according to claim 1, wherein the frame portion has fastening holes for fastening.

11. The welding jig according to claim 1 , wherein the pressure applying portion is a pressure protrusion formed on a lower surface of the protruding portion and applying pressure to the workpiece.

12. The welding jig according to claim 11, wherein the pressure protrusion is formed adjacent to one side or the other side of the welding hole in a circumferential direction of the protrusion.

13. the secondary battery is a cylindrical secondary battery, The welding jig according to claim 1 , wherein the protrusion is cylindrical and extends downward from the lower surface of the main body.

14. The pressure applying portion is 14. The welding jig according to claim 13, wherein pressure is applied to an upper surface of the current collector plate in order to perform welding between the current collector plate connected to an electrode assembly inside the cylindrical secondary battery and a beading portion formed on a can body of the cylindrical secondary battery.

Images