Welding mask and welding method

Abstract

A welding mask according to one embodiment of the present invention includes a welding mask body configured to cover one side opening of a housing of a battery cell and having a laser passing portion configured to allow a laser irradiated inside the housing to pass therethrough, and an insertion guide having a hollow structure, connected to the laser passing portion, and configured to be inserted into a winding center hole of an electrode assembly accommodated inside the housing.

Description

Technical Field

[0001] The present invention relates to a welding mask and a welding method.

[0002] This application claims priority based on Korean Patent Application No. 10-2021-0136996 filed on October 14, 2021, and Korean Patent Application No. 10-2022-0123919 filed on September 29, 2022, and the contents disclosed in the specifications and drawings of the applications are all incorporated into this application.

Background Art

[0003] In the manufacture of battery cells, for example, ultrasonic welding can be applied to the connection between the electrode assembly and the current collector plate, and the connection between the current collector plate and the terminal. As shown in FIG. 1, ultrasonic welding is a method in which after the ultrasonic welding horn 1 and the anvil 2 are brought into contact with both sides of the workpiece 3 to be welded, welding is performed using the vibration of the ultrasonic welding horn 1.

[0004] Referring to FIG. 2, in the battery cell 4, when attempting to weld the workpiece 3 including the current collector 3a and the terminal 3b located on the closed portion side of the battery can 5 provided on the side opposite to the open portion formed on one side of the battery can 5, the welding tip of the ultrasonic welding horn 1 must be inserted through the winding center hole of the electrode assembly 6. As a result, the extension length of the welding tip of the ultrasonic welding horn 1 has no choice but to become longer, and thereby, the welding tip of the ultrasonic welding horn 1 may be warped or broken during ultrasonic welding.

[0005] In addition, when applying vibration to perform ultrasonic welding in the narrow space inside the winding center hole of the electrode assembly 6, the electrode assembly 6 may be damaged due to interference between the inner wall surface of the winding center hole and the ultrasonic welding horn 1.

[0006] Thus, in order to weld the welded body 3 located on the closing portion side of the battery can 5, a welding tool must be inserted through the winding center hole of the electrode assembly 6. Therefore, there are many restrictions when performing welding, and the same difficulties can occur not only in ultrasonic welding but also when applying resistance welding.

[0007] Considering such points, a solution of applying laser welding that enables welding without inserting the welding tool through the winding center hole of the electrode assembly 6 can be considered. However, there can still be restrictions in such laser welding.

[0008] That is, in the battery cell 4 as shown in FIG. 2, when applying laser welding for welding the welded body 3 where the battery can 5 is located on the closing portion side, it is necessary to prevent the laser from contacting the inner wall surface of the winding center hole during the process of the laser passing from the entrance to near the exit of the winding center hole of the electrode assembly 6 having a narrow width. In addition, when foreign substances such as welding spatter and welding fumes generated during laser welding scatter on the inner wall surface of the electrode assembly 6, physical damage to the electrode assembly 6 may occur, and in addition, a short circuit inside the battery cell 4 due to metal foreign substances may also occur. Therefore, when welding the welded body 3 located inside the battery cell 4 by laser welding, a solution is required to prevent damage to the electrode assembly 6.

[0009] On the other hand, it is necessary to remove the oxygen atmosphere near the welded body 3 during laser welding. Therefore, a solution is required to easily allow the purge gas for removing the oxygen atmosphere to flow near the welded body during laser welding.

[0010] In addition, when welding the welded body 3 by laser welding, if foreign substances generated during the welding process are not appropriately removed, the laser focus may not be achieved due to interference between the foreign substances and the laser, and smooth welding may not be possible. Therefore, a solution is required to appropriately remove foreign substances generated during laser welding.

Summary of the Invention

Problems to be Solved by the Invention

[0011] The present invention has been made in view of the above-described problems, and an object thereof is to prevent damage to the electrode assembly when welding a welded body located inside a battery cell by laser welding.

[0012] In another aspect, an object of the present invention is to allow a purge gas to easily flow into the vicinity of a welded body in order to remove the oxygen atmosphere in the vicinity of the welded body during laser welding.

[0013] In still another aspect, an object of the present invention is to appropriately remove foreign matter generated when welding a welded body located inside a battery cell by laser welding.

[0014] However, the technical problems to be solved by the present invention are not limited to the above-described problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description of the invention.

Means for Solving the Problems

[0015] A welding mask according to an embodiment of the present invention for solving the above-described problems includes a laser passage portion configured to allow a laser irradiated inside a housing of a battery cell to pass therethrough, a welding mask body configured to cover one open portion of the housing, and an insertion guide having a hollow structure, connected to the laser passage portion, and configured to be inserted into a winding center hole of an electrode assembly housed inside the housing.

[0016] An inlet of the laser passage portion can have a width larger than that of an outlet of the laser passage portion.

[0017] The insertion guide is inserted through an inlet of the winding center hole and can extend to an outlet of the winding center hole located on the opposite side of the inlet.

[0018] The welding mask body can be provided with a gas injection part configured to be able to inject purge gas into the housing through the welding mask body.

[0019] The insertion guide can be arranged at a distance from the inner wall surface of the winding center hole.

[0020] The welding mask can further include a gas guide configured to be able to guide the flow of the purge gas in a direction toward a gap formed between the inner wall surface of the winding center hole and the insertion guide.

[0021] The insertion guide can be configured such that the purge gas flowing into the separation space formed between the inner wall surface of the winding center hole and the insertion guide can flow inside.

[0022] The insertion guide can be provided with at least one gas inlet.

[0023] The gas inlet can have a form that is notched upward from the lowermost end of the insertion guide.

[0024] The gas inlet can be located at a predetermined distance upward from the lowermost end of the insertion guide.

[0025] The welding mask can further include a mesh member configured to cover the gas inlet.

[0026] The lowermost end of the insertion guide can be located at a distance from the object to be welded.

[0027] The welding mask can further include a sealing member configured to improve the airtightness of the coupling part between the welding mask body and the housing.

[0028] The welding mask body can further include a suction part communicating with the internal space of the insertion guide.

[0029] On the one hand, a welding method according to an embodiment of the present invention is a method for welding a welded body located inside a housing of a battery cell, including lowering a welding mask including a welding mask body and an insertion guide extending downward from the welding mask body to cover an opening formed in the housing of the battery cell, and inserting the insertion guide into a winding center hole of an electrode assembly provided inside the housing, a welding mask mounting step (A step); and a welding step (B step) of welding a welded body located on the closed portion side of the housing provided on the opposite side of the opening by irradiating a laser through a laser passing portion provided in the welding mask body and the insertion guide.

[0030] The welding method may further include a gas injection step (C step) of injecting a purge gas into the housing through the welding mask body.

[0031] The gas injection step (C step) may be a step of allowing the purge gas injected into the housing to flow into a separation space formed between an inner wall surface of the winding center hole and the insertion guide and then into the insertion guide.

[0032] The gas injection step (C step) may be a step of allowing the purge gas flowing through the separation space formed between the inner wall surface of the winding center hole and the insertion guide to flow into the insertion guide through a gas inlet formed in the insertion guide.

[0033] The gas injection step (C step) may be a step of allowing the purge gas to flow into the insertion guide through a gas inlet formed at a lower end portion of the insertion guide.

[0034] The gas injection step (C step) may be a step of allowing purge gas flowing in through a gap space formed between the inner wall surface of the winding center hole and the insertion guide to flow into the inside of the insertion guide through a gap formed between the lowermost end of the insertion guide and the object to be welded.

[0035] The welding method may further include a suction step (D step) of sucking foreign matter including at least one of welding spatters and welding fumes generated inside the insertion guide when welding the object to be welded through the welding mask body.

[0036] The suction step (D step) may be a step of sucking the foreign matter through a suction part configured to communicate with the insertion guide.

[0037] The suction step (D step) may be a step of performing suction through a suction part configured to communicate with the laser passing part.

Advantages of the Invention

[0038] According to one aspect of the present invention, when welding an object to be welded located inside a battery cell by laser welding, damage to the electrode assembly can be prevented.

[0039] According to another aspect of the present invention, a purge gas for removing an oxygen atmosphere near the object to be welded during laser welding can be easily made to flow near the object to be welded.

[0040] According to still another aspect of the present invention, foreign matter generated when welding an object to be welded located inside a battery cell by laser welding can be appropriately removed.

[0041] However, the advantageous effects derived through the present invention are not limited to the effects described above, and other advantageous effects not mentioned will be clearly understood by those skilled in the art from the following description of the invention.

[0042] The following drawings attached to this specification illustrate desirable embodiments of the present invention and serve to further understand the technical idea of the present invention together with the detailed description of the invention. Therefore, the present invention should not be construed as being limited only to the matters described in the drawings.

Brief Description of the Drawings

[0043]

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Figure 14

[0044] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in this specification and claims are not to be construed as limited to ordinary and dictionary meanings, and the inventors themselves interpret them in accordance with the meaning and concept corresponding to the technical idea of the present invention in accordance with the principle that they can appropriately define the concept of the terms in order to explain the invention in the best way. Therefore, it should be understood that the configurations shown in the embodiments described in this specification are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention, and thus there can be various equivalents and modifications that can replace them at the time of this application.

[0045] Before describing the welding mask 100 of the present invention, first, an exemplary form of a battery cell 200 including an object to be laser welded using the welding mask 100 of the present invention will be described.

[0046] FIG. 3 is a diagram showing the appearance of the welding mask of the present invention, and FIG. 4 is a diagram showing the internal structure of an assembly in which a battery cell and the welding mask of the present invention are combined.

[0047] Referring to FIGS. 3 and 4, a welding mask 100 according to an embodiment of the present invention is a tool for performing laser welding on a weldment located inside a battery cell 200, and can descend from the upper part of the battery cell 200 and be coupled to the upper end of the battery cell 200. The laser welding process using the welding mask 100 of the present invention can be performed in a state where one side of a housing 220 provided in the battery cell 200 is open without being finished.

[0048] The battery cell 200 can be, for example, a cylindrical battery cell 200. The battery cell 200 can include an electrode assembly 210, a housing 220, a current collector plate (first current collector plate) 230, and a terminal 240. The electrode assembly 210 can be a jelly roll type electrode assembly having a winding center hole formed in the center portion. The housing 220 can be configured to accommodate the electrode assembly 210 through an opening formed at the upper end. The current collector plate (first current collector plate) 230 can be coupled to the lower end of the electrode assembly 210. The current collector plate (first current collector plate) 230 can be coupled to a first plain portion 211 provided at the lower end of the electrode assembly 210. In this case, the current collector plate (first current collector plate) 230 can be interposed between a closed portion of the housing 220 provided on the side opposite to the opening of the housing 220 and the electrode assembly 210.

[0049] The laser welding process using the welding mask 100 of the present invention can be a welding process for joining the current collector plate (first current collector plate) 230 of the battery cell 200 and the terminal 240. That is, in the present invention, the object to be welded can include the current collector plate (first current collector plate) 230 and the terminal 240. The terminal 240 can be fixed to the housing 220 through, for example, a closing portion provided at the lower end of the housing 220. In this case, the combined body of the electrode assembly 210 and the current collector plate (first current collector plate) 230 is inserted into the housing 220 through the upper end opening of the housing 220, and the current collector plate (first current collector plate) 230 and the terminal 240 are in contact with each other. By irradiating the current collector plate (first current collector plate) 230 with a laser through the winding center hole of the electrode assembly 210, the current collector plate (first current collector plate) 230 and the terminal 240 can be welded.

[0050] On the other hand, the battery cell 200 can further include a current collector plate (second current collector plate) 250. The current collector plate (second current collector plate) 250 can be coupled to the upper end of the electrode assembly 210. The current collector plate (second current collector plate) 250 can be coupled to the second plain portion 212 provided at the lower end of the electrode assembly 210. The current collector plate (second current collector plate) 250 can be provided with a current collector plate hole formed at a position corresponding to the winding center hole so as not to cover the winding center hole of the electrode assembly 210. In this case, for example, after inserting the combined body of the electrode assembly 210 and the pair of current collector plates 230, 250 into the housing 220 through the upper end opening of the housing 220, by irradiating a laser through the winding center hole of the electrode assembly 210 as described above, the current collector plate (first current collector plate) 230 and the terminal 240 can be welded.

[0051] As described above, in the laser welding process using the welding mask 100 of the present invention, the battery cell 200 including the object to be welded has been described. However, in the laser welding using the welding mask 100 of the present invention, the object to be welded is not limited to the current collector plate (first current collector plate) 230 and the terminal 240 provided in the battery cell 200 having the structure as described above. That is, as long as a winding center hole is formed in the electrode assembly 210 provided in the battery cell 200, and the object to be welded is located on the outlet side of the winding center hole, which is on the opposite side of the inlet of the winding center hole where the laser is incident, it can be used as the object to be welded in the laser welding using the welding mask 100 of the present invention.

[0052] Referring to FIGS. 3 and 4, the welding mask 100 according to an embodiment of the present invention may include a welding mask body 110 and an insertion guide 120.

[0053] The welding mask body 110 may include a laser passing portion 111 configured to allow the laser irradiated inside the housing 220 of the battery cell 200 to pass through. The welding mask body 110 may be configured to cover an opening formed on one side of the housing 220. The insertion guide 120 may have a hollow structure through which the laser can pass. The insertion guide 120 may be connected to the laser passing portion 111. The internal space of the insertion guide 120 may communicate with the internal space of the laser passing portion 111. The insertion guide 120 may be configured to be inserted into the winding center hole of the electrode assembly 210 accommodated inside the housing 220.

[0054] With such a configuration of the welding mask 100, the laser irradiated from the outside of the battery cell 200 can pass through the winding center hole of the electrode assembly 210 via the laser passage portion 111 and the insertion guide 120 and reach the workpiece to be welded. Further, since the insertion guide 120 can function as a mask between the laser and the inner wall surface of the winding center hole, it is possible to prevent the electrode assembly 210 from being damaged by the laser in the case of an error in the apparatus setting for laser irradiation or the like. In addition, it is possible to prevent foreign matters such as welding spatters and welding fumes that may occur during the laser welding process from hitting the inner wall surface of the winding center hole and damaging the electrode assembly 210, and / or prevent a phenomenon in which metal foreign matters cause a short circuit within the electrode assembly 210.

[0055] The laser passage portion 111 may be in the form of a hole penetrating the welding mask body 110. The inlet of the laser passage portion 111 can have a width larger than that of the outlet. With such a configuration of the welding mask 100, a laser irradiation device (not shown) can be easily inserted into the laser passage portion 111. On the other hand, the width of the inlet of the laser passage portion 111 can mean the maximum width of the inlet of the laser passage portion 111. Similarly, the width of the outlet of the laser passage portion 111 can mean the maximum width of the outlet of the laser passage portion 111. If the inlet and / or outlet of the laser passage portion 111 is substantially circular, the width of the inlet and / or the width of the outlet can be defined as the inner diameter of the inlet and / or the inner diameter of the outlet.

[0056] The laser passage portion 111 may be provided at a substantially central portion of the welding mask body 110. The laser passage portion 111 may be provided at a position corresponding to the winding center hole of the electrode assembly 210 when the welding mask body 110 covers the upper end opening portion of the housing 220. With such a configuration of the welding mask 100, it becomes easy to prevent the laser passing through the laser passage portion 111 from contacting the inner wall surface of the insertion guide 120 inserted into the winding center hole of the electrode assembly 210.

[0057] Referring to FIG. 4, the insertion guide 120 can be inserted through the inlet of the winding center hole of the electrode assembly 210 and extend to the outlet of the winding center hole located on the opposite side of the inlet. According to such a configuration of the welding mask 100, the electrode assembly 210 can be protected from foreign matters generated by the laser and laser welding in the entire region along the extending direction (the direction aligned with the Z-axis) of the winding center hole of the electrode assembly 210. The foreign matters generated by welding can include at least one of welding spatter and welding fume.

[0058] Referring to FIGS. 3 and 4, the welding mask body 110 can include a gas injection portion 112. The gas injection portion 112 can be configured to inject purging gas into the interior of the housing 220 through the welding mask body 110. According to such a configuration of the welding mask 100, it becomes possible to easily inject purging gas into the interior of the housing 220. By injecting purging gas into the interior of the housing 220, the oxygen concentration inside the housing 220 of the battery cell 200 can be reduced. During the process of performing laser welding, internal ignition can be prevented by reducing the oxygen concentration inside the housing 220 to a level below a certain level. In addition, when the purging gas is supplied to the welding region of the workpiece to be welded, corrosion due to oxidation of the workpiece to be welded can be prevented.

[0059] The gas injection portion 112 can be in the form of a hole penetrating the welding mask body 110. For example, a gas injection device (not shown) can be inserted into the gas injection portion 112. A plurality of the gas injection portions 112 can be provided, and in this case, the plurality of gas injection portions 112 can be arranged around the laser passing portion 111. As the purging gas, for example, N2 gas can be used. However, the type of the purging gas is not limited to this, and various inert gases can be applied as the purging gas.

[0060] Referring to FIGS. 3 and 4, the insertion guide 120 can be arranged at a distance from the inner wall surface of the winding center hole of the electrode assembly 210. For example, when the winding center hole of the electrode assembly 210 and the insertion guide 120 are each substantially cylindrical, the inner diameter of the winding center hole of the electrode assembly 210 can be formed larger than the outer diameter of the insertion guide 120. For example, the inner diameter of the winding center hole of the electrode assembly 210 can be formed in the range of about 5 mm to 8 mm, and the outer diameter of the insertion guide 120 can be formed about 1 mm to 2 mm smaller than the winding center hole of the electrode assembly 210.

[0061] In this way, when a separation space is formed between the inner wall surface of the winding center hole of the electrode assembly 210 and the outer peripheral surface of the insertion guide 120, the purge gas flowing into the inside of the housing 220 through the opening of the housing 220 can be supplied to the welded body side through the separation space. The purge gas supplied to the welded body in this way can reduce the oxygen concentration in the vicinity of the welded body during laser welding.

[0062] FIG. 5 is a diagram for explaining an embodiment in which a gas guide is provided in the welding mask body of the present invention.

[0063] Referring to FIG. 5, the welding mask 100 can include a gas guide 114 configured to guide the flow of the purge gas. The gas guide 114 can be configured to guide the flow of the purge gas in a direction toward the gap formed between the inner wall surface of the winding center hole of the electrode assembly 210 and the insertion guide 120.

[0064] When the welding mask 100 is provided with the gas guide 114 in this way, the purge gas injected into the inside of the housing 220 through the gas injection portion 112 can be intensively supplied to the space side between the inner wall surface of the winding center hole and the insertion guide 120. Therefore, the oxygen concentration in the vicinity of the welded body can be reduced more efficiently.

[0065] On the one hand, as shown in FIG. 5, the welding mask body 110 can include a body extension 115 extending from its lower surface toward the internal space of the housing 220. In this case, the body extension 115 can be configured to be separated from the electrode assembly 210 or the current collector plate (second current collector plate) 250 when the welding mask body 110 is in close contact with the upper end of the housing 220. Thus, when the welding mask body 110 includes the body extension 115, the gas guide 114 extends from the outlet of the gas injection portion 112 and through the space formed between the body extension 115 and the current collector plate (second current collector plate) 250 or between the body extension 115 and the electrode assembly 210 to extend to the vicinity of the inlet of the winding center hole of the electrode assembly 210.

[0066] FIGS. 6 and 7 are diagrams for explaining an embodiment in which the insertion guide of the present invention includes a notch-shaped gas inlet formed at its lower end, and FIG. 8 is a diagram for explaining an embodiment in which the insertion guide of the present invention includes a hole-shaped gas inlet. Further, FIG. 9 is a diagram for explaining an embodiment in which the welding mask of the present invention includes a mesh member configured to cover the gas inlet, and FIG. 10 is a diagram for explaining an embodiment in which the insertion guide of the present invention is configured to be separated from the object to be welded by a predetermined distance.

[0067] Referring to FIGS. 3 and 4 and FIGS. 6 to 10, the insertion guide 120 can be configured such that the purge gas flowing into the separation space formed between the inner wall surface of the winding center hole of the electrode assembly 210 and the insertion guide 120 can flow into the insertion guide 120. FIGS. 6 to 10 are diagrams showing exemplary forms of such a configuration of the insertion guide 120.

[0068] According to such a configuration of the insertion guide 120, the purge gas flowing into the interior of the housing 220 through the gas injection portion 112 can flow into the interior of the insertion guide 120 through the gap space formed between the winding center hole and the insertion guide 120. Thereby, the purge gas can reduce the oxygen concentration in the welding region of the weldment irradiated with the laser L.

[0069] Referring to FIG. 6, the insertion guide 120 can include at least one gas inlet 121. In this case, the purge gas flowing in through the gap space between the inner wall surface of the winding center hole and the outer peripheral surface of the insertion guide 120 can flow into the internal space of the insertion guide 120 through the gas inlet 121. The gas inlet 121 can have, for example, a form that is cut out upward from the lower end of the insertion guide 120. Thus, when the gas inlet 121 is formed at the lowermost end portion of the insertion guide 120, the purge gas flowing into the interior of the insertion guide 120 can be intensively supplied to the welding region of the weldment irradiated with the laser L, whereby an inert atmosphere in the welding region can be efficiently formed.

[0070] Referring to FIG. 7, a plurality of the gas inlets 121 can be provided. The plurality of gas inlets 121 can be spaced apart from each other along the periphery of the lower end portion of the insertion guide 120. Thus, when a plurality of the gas inlets 121 are provided, the inflow of the purge gas into the internal space of the insertion guide 120 becomes smoother.

[0071] Referring to FIG. 8, unlike those shown in FIGS. 6 and 7, the gas inlet 121 can be located at a predetermined distance H above the lowermost end of the insertion guide 120. In this case, the phenomenon that foreign matter generated during laser welding jumps out of the outside of the insertion guide 120 can be minimized. A plurality of the gas inlets 121 can be provided. In this case, the plurality of gas inlets 121 can be spaced apart from each other along the circumferential direction of the insertion guide 120.

[0072] On the one hand, in such an embodiment, it may be advantageous to limit the formation height H of the gas inlet 121 to a certain level or below. Considering only the function of the insertion guide 120 as a shield, it may be advantageous to increase the formation height H of the gas inlet 121. However, if the formation height H of the gas inlet 121 is excessively high, unless the circulation speed of the purge gas is reduced to a certain level or below, the purge gas flowing into the insertion guide 120 may not be supplied to the lowermost end of the insertion guide 120. Therefore, when the formation height of the gas inlet 121 exceeds a certain level, in order to supply the purge gas well to the welding area, the circulation speed of the purge gas must be reduced, which may lead to a decrease in productivity. Considering this, the gas inlet 121 can be located at a height exceeding about 0 and not exceeding 10 mm, preferably exceeding about 0 and not exceeding 15 mm, more preferably exceeding about 0 and not exceeding 20 mm from the lowermost end of the insertion guide 120.

[0073] On the other hand, as shown in FIGS. 6 to 8, when the insertion guide 120 of the present invention includes the gas inlet 121, the lowermost end of the insertion guide 120 can contact the object to be welded. In this case, the insertion guide 120 can function as a shield to prevent foreign matter that may be generated during laser welding from scattering toward the electrode assembly 210 in all regions except the region where the gas inlet 121 is formed. Thereby, damage to the electrode assembly 210 can be effectively prevented. Of course, it is also possible for the lowermost end of the insertion guide 120 to be separated from the object to be welded without contacting it. However, in this case, considering the function of the insertion guide 120 as a shield, it may be advantageous to form only a very fine gap between the lowermost end of the insertion guide 120 and the object to be welded.

[0074] Referring to FIG. 9, the welding mask 100 (refer to FIG. 4) of the present invention can further include a mesh member M. The mesh member M can be configured to cover the gas inlet 121. In this way, when the gas inlet 121 is covered by the mesh member M, the purge gas can smoothly flow into the inside of the insertion guide 120 through the fine holes formed in the mesh member M, while foreign matters including welding spatters and / or welding fumes generated in the welding region inside the insertion guide 120 do not easily flow out to the outside of the insertion guide 120. Therefore, both the formation of an inert atmosphere in the welding region and the prevention of damage to the electrode assembly 210 can be achieved.

[0075] On the other hand, referring to FIG. 10, the lowermost end of the insertion guide 120 can be positioned at a distance from the workpiece to be welded. The insertion guide 120 can be configured not to separately include the gas inlet 121 as described above. In this case, the purge gas can flow into the inside of the insertion guide 120 only through the gap formed between the lowermost end of the insertion guide 120 and the workpiece to be welded.

[0076] FIGS. 11 and 12 are diagrams for explaining an embodiment in which the welding mask of the present invention includes a sealing member.

[0077] Referring to FIGS. 11 and 12, the welding mask 100 can further include a sealing member G configured to improve the airtightness of the coupling site between the welding mask body 110 and the housing 220. When the sealing member G is provided, the inside of the housing 220 of the battery cell 200 can be sealed during the progress of the laser welding process. Therefore, the phenomenon that the purge gas supplied to the inside of the housing 220 leaks to the outside through the coupling interface between the welding mask body 110 and the upper end of the housing 220 can be prevented.

[0078] The sealing member G can be, for example, a rubber material having elasticity. However, this does not limit the material of the sealing member G, and any material that can be interposed between objects to improve airtightness is applicable as the sealing member G of the present invention. On the other hand, in the drawings of the present invention, only the case where the sealing member G is configured to be in close contact with the outer peripheral surface of the upper end region of the housing 220 (see FIG. 13) and the case where the sealing member G is configured to be in close contact with the inner peripheral surface of the upper end region of the housing 220 (see FIG. 14) are shown respectively, but the present invention is not limited to these embodiments. The sealing member G can be configured to be in close contact with both the inner peripheral surface and the outer peripheral surface of the upper end region of the housing 220. The sealing member G can also be configured to be interposed between the uppermost end of the housing 220 and the lower surface of the welding mask body 110.

[0079] Referring to FIGS. 3 and 4, the welding mask body 110 of the present invention can be provided with a suction portion 113. The suction portion 113 can be configured to communicate with the internal space of the insertion guide 120. When the welding mask body 110 is provided with the suction portion 113 in this way, foreign matters including welding spatter and / or welding fume generated inside the insertion guide 120 by laser welding can be smoothly discharged to the outside.

[0080] The suction portion 113 may be in the form of a hole penetrating the welding mask body 110. For example, a suction device can be inserted into the suction portion 113. When suction is performed through the suction portion 113 while injecting purge gas through the above-described gas injection portion 112, foreign matter generated during laser welding is discharged through the suction portion 113 and the circulation of the purge gas is also performed. A plurality of the suction portions 113 can be provided. In this case, the plurality of suction portions 113 can be arranged around the laser passing portion 111. In this way, when foreign matter due to laser welding is not discharged to the outside through the laser passing portion 111 but is discharged to the outside through a separate suction portion 113, the devices for laser irradiation and the devices for suction can be installed on the welding mask body 110 at different positions from each other, so that interference between the two devices can be prevented.

[0081] Referring to FIG. 4, the suction portion 113 can be configured to communicate directly with the laser passing portion 111. In this case, foreign matter generated during laser welding can be discharged to the outside through the suction portion 113 through the internal space of the insertion guide 120 and the internal space of the laser passing portion 111.

[0082] FIG. 13 is a diagram for explaining an embodiment in which the suction portion provided in the welding mask of the present invention is configured to communicate directly with the insertion guide.

[0083] Referring to FIG. 13, the suction portion 113, unlike that shown in FIG. 4, can be configured to be directly connected to the insertion guide 120. In this case, foreign matter generated by laser welding can be discharged to the outside from the internal space of the insertion guide 120 through the internal space of the suction portion 113 without passing through the laser passing portion 111. In this way, when foreign matter generated by laser welding is discharged to the outside without passing through the laser passing portion 111, problems such as the laser focal distance not being adjusted due to interference between the foreign matter and the laser can be prevented.

[0084] FIG. 14 is a diagram for explaining the circulation path of the purge gas and the path through which foreign matter generated by welding is discharged when the welding mask of the present invention includes all of a laser passing portion, a purge gas injection portion, and a suction portion.

[0085] Referring to FIG. 14, when the laser passing portion 111, the gas injection portion 112, and the suction portion 113 are independently provided in the welding mask body 110, the purge gas can flow into and out of the inside of the housing 220 through paths (1) to (4). That is, the purge gas is introduced into the inside of the housing 220 along path (1), flows into the gap space between the inner wall surface of the winding center hole and the insertion guide 120 along path (2), flows into the inside of the insertion guide 120 along path (3), and can be discharged to the outside of the welding mask 100 and the battery cell 200 along path (4). On the other hand, foreign matter including welding spatter and / or welding fume generated at the lowermost end of the winding center hole of the electrode assembly 210 can be discharged to the outside of the welding mask 100 and the battery cell 200 along path (4).

[0086] According to such a configuration of the present invention, by intensively supplying the purge gas to the welding area, not only can the oxygen concentration in the welding area be reduced as much as possible, but also the phenomenon that foreign matter generated during laser welding damages the electrode assembly 210 and the phenomenon that foreign matter accumulates in the welding area and the welding quality deteriorates can be prevented.

[0087] Next, with reference to FIGS. 3 to 14 of the present application, a method of welding a welded body provided in the battery cell 200 using the welding mask 100 of the present invention described above will be described.

[0088] A welding method according to an embodiment of the present invention relates to a method of welding a welded body located inside a housing 220 of a battery cell 200. The welding method may include a welding mask mounting step (step A) of mounting a welding mask on an opening formed in the housing 220 of the battery cell 200, and a welding step (step B) of welding a welded body inside the housing 220 through the welding mask 100.

[0089] In the step A, the welding mask 100 including a welding mask body 110 and an insertion guide 120 extending downward from the welding mask body 110 is lowered to cover the opening formed in the housing 220 of the battery cell 200 so that the insertion guide 120 is inserted into the winding center hole of the electrode assembly 210 provided inside the housing 220. In the step B, the laser L is irradiated through the laser passing portion 111 and the insertion guide 120 provided in the welding mask body 110 to weld a welded body located on the closed portion side of the housing 220 provided on the opposite side of the opening.

[0090] According to this, the laser irradiated from the outside of the battery cell 200 can pass through the winding center hole of the electrode assembly 210 through the laser passing portion 111 and the insertion guide 120 and reach the welded body. Further, since the insertion guide 120 can function as a mask between the laser and the inner wall surface of the winding center hole, it is possible to prevent the electrode assembly 210 from being damaged by the laser when an error occurs in the apparatus setting for laser irradiation or the like. In addition, it is possible to prevent phenomena such as foreign matters such as welding spatter and welding fumes generated during the laser welding process from contacting the inner wall surface of the winding center hole and damaging the assembly 210, and / or a phenomenon in which metal foreign matters cause a short circuit in the electrode assembly 210.

[0091] In addition to the two steps as described above, the welding method can further include a gas injection step (step C). The step C can be a step of injecting a purge gas into the housing 220 through the welding mask body 110. According to this, the oxygen concentration inside the housing 220 of the battery cell 200 can be reduced.

[0092] The step C can be a step of allowing the purge gas injected into the housing 220 to flow into the inside of the insertion guide 120 after flowing into the separation space formed between the inner wall surface of the winding center hole and the insertion guide 120. According to this, the oxygen concentration in the welding region of the welded body irradiated with the laser L can be effectively reduced.

[0093] The step C can be a step of allowing the purge gas flowing in through the separation space formed between the inner wall surface of the winding center hole and the insertion guide 120 to flow into the inside of the insertion guide 120 through, for example, the gas inlet 121 formed in the insertion guide 120. Differently, the step C can be a step of allowing the purge gas flowing in through the separation space formed between the inner wall surface of the winding center hole and the insertion guide 120 to flow into the inside of the insertion guide 120 through the gap formed between the lowermost end of the insertion guide 120 and the welded body.

[0094] The welding method can further include a suction step (step D) of sucking foreign matters generated during laser welding. That is, the welding method can include the step A and the step B, or include the step A, the step B and the step C, or include the step A, the step B and the step D, or include the step A, the step B, the step C and the step D.

[0095] The D step may be a step of sucking foreign matter including at least one of welding spatters and welding fumes generated inside the insertion guide 120 during welding of the workpiece through the welding mask body 110. According to this, foreign matter including welding spatters and / or welding fumes generated inside the insertion guide 120 by laser welding can be smoothly discharged to the outside.

[0096] The D step may be a step of sucking foreign matter through the suction part 113 configured to communicate with the insertion guide 120. The D step may be, for example, a step of sucking through the suction part 113 configured to communicate directly with the laser passing part 111. Differently, the D step may be a step of sucking through the suction part 113 configured to communicate directly with the insertion guide 120. Thus, when the foreign matter is discharged by suction without passing through the laser passing part 111, problems such as the laser focal length not being adjusted due to interference between the foreign matter and the laser can be prevented.

[0097] As described above, the present invention has been described with reference to limited embodiments and drawings, but the present invention is not limited thereby, and it goes without saying that various modifications and variations are possible within the technical idea of the present invention and the equivalent scope of the following claims by those having ordinary knowledge in the technical field to which the present invention belongs.

Explanation of Reference Numerals

[0098] 100 Welding mask 110 Welding mask body 111 Laser passing part 112 Purge gas injection part 113 Suction part 114 Gas guide 115 Body extension part 120 Insertion guide 121 Gas inlet M Mesh member G Sealing member L Laser 200 battery cells 210 electrode assembly 211 first plain part 212 second plain part 220 housing 230 current collector plate (first current collector plate) 240 terminal 250 current collector plate (second current collector plate)

Claims

1. A welding mask body comprising a laser passing portion configured to allow a laser irradiated inside the housing of a battery cell that houses an electrode current collector through an open portion on one side of the housing to pass through, the welding mask body being located at the one-side open portion of the housing with the one-side open portion of the housing being open and configured to cover the one-side open portion; An insertion guide having a hollow structure, connected to the laser passing portion, and configured to be inserted into a winding center hole of an electrode assembly housed inside the housing; A welding mask including the above.

2. The welding mask according to claim 1, wherein an inlet of the laser passing portion has a width larger than that of an outlet of the laser passing portion.

3. The insertion guide: The welding mask according to claim 1, wherein the insertion guide is inserted through an inlet of the winding center hole and extends to an outlet of the winding center hole located on the opposite side of the inlet.

4. The welding mask body: The welding mask according to claim 1, wherein the welding mask body includes a gas injection portion configured to be able to inject a purge gas into the housing through the welding mask body.

5. The insertion guide: The welding mask according to claim 4, wherein the insertion guide is disposed at a distance from an inner wall surface of the winding center hole.

6. The welding mask: The welding mask according to claim 5, further including a gas guide configured to be able to guide a flow of the purge gas in a direction toward a gap formed between an inner wall surface of the winding center hole and the insertion guide.

7. The insertion guide: The welding mask according to claim 5, wherein the insertion guide is configured such that the purge gas flowing into a space formed between an inner wall surface of the winding center hole and the insertion guide can flow into the interior.

8. The insertion guide: The welding mask according to claim 7, wherein the insertion guide includes at least one gas inlet.

9. The gas inlet: The welding mask according to claim 8, wherein the gas inlet has a form of being notched upward from the lowermost end of the insertion guide.

10. The welding mask according to claim 8, wherein the gas inlet is located at a predetermined distance upward from the lowermost end of the insertion guide.

11. The welding mask: The welding mask according to claim 8, further comprising a mesh member configured to cover the gas inlet.

12. The welding mask according to claim 7, wherein the lowermost end of the insertion guide is positioned at a distance from the object to be welded.

13. The welding mask is The welding mask according to any one of claims 1 to 12, further comprising a sealing member configured to improve the airtightness of the joint portion between the welding mask body and the housing.

14. The welding mask body is The welding mask according to claim 1, further comprising a suction portion communicating with the internal space of the insertion guide.

15. The suction portion is The welding mask according to claim 14, wherein the suction portion directly communicates with the internal space of the laser passing portion.

16. A method of welding an object to be welded located inside the housing of a battery cell that houses an electrode current collector through an open portion on one side of the housing, comprising: A welding mask mounting step (A step) of lowering a welding mask including a welding mask body and an insertion guide extending downward from the welding mask body, so that the welding mask body is positioned in and covers the open portion with the open portion formed in the housing of the battery cell being open, and the insertion guide is inserted into a winding center hole of an electrode assembly provided inside the housing; A welding step (B step) of welding the object to be welded located on the closed portion side of the housing provided on the opposite side of the open portion by irradiating a laser through a laser passing portion provided in the welding mask body and the insertion guide; A welding method including.

17. The welding method is The welding method according to claim 16, further comprising a gas injection step (C step) of injecting a purge gas into the housing through the welding mask body.

18. The gas injection step (C step) is The welding method according to claim 17, wherein after the purge gas injected into the housing flows into the space formed between the inner wall surface of the winding center hole and the insertion guide, the purge gas flows into the insertion guide.

19. The gas injection step (C step) is The step of allowing purge gas that has flowed in through the gap space formed between the inner wall surface of the winding center hole and the insertion guide to flow into the interior of the insertion guide through a gas inlet formed in the insertion guide, characterized in that it is the welding method according to claim 18.

20. The gas injection step (C step) is The step of allowing the purge gas to flow into the interior of the insertion guide through a gas inlet formed at the lower end of the insertion guide, characterized in that it is the welding method according to claim 18.

21. The gas injection step (C step) is The step of allowing purge gas that has flowed in through the gap space formed between the inner wall surface of the winding center hole and the insertion guide to flow into the interior of the insertion guide through a gap formed between the lowermost end of the insertion guide and the workpiece to be welded, characterized in that it is the welding method according to claim 18.

22. The welding method is Further including a suction step (D step) of sucking foreign matter including at least one of welding spatters and welding fumes generated inside the insertion guide during welding of the workpiece to be welded through the welding mask body, characterized in that it is the welding method according to any one of claims 16 to 21.

23. The suction step (D step) is The step of sucking the foreign matter through a suction portion configured to communicate with the insertion guide, characterized in that it is the welding method according to claim 22.

24. The suction step (D step) is The step of performing suction through a suction portion configured to communicate with the laser passing portion, characterized in that it is the welding method according to claim 22.

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