Ultrasonic welding apparatus, ultrasonic welding method, battery cell manufactured by the ultrasonic welding method, battery pack, and vehicle including the battery pack
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- LG ENERGY SOLUTION LTD
- Filing Date
- 2025-09-18
- Publication Date
- 2026-07-14
Smart Images
Figure CN122396562A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to ultrasonic welding apparatus and ultrasonic welding method, battery cells manufactured by ultrasonic welding method, battery packs, and vehicles including the battery packs. Background Technology
[0002] Secondary batteries are receiving significant attention as an energy source for improving environmental sustainability and energy efficiency, not only because of their high energy density and significant potential to reduce fossil fuel consumption, but also because of their advantage of producing no byproducts during energy use. Unlike primary batteries, which are non-rechargeable, secondary batteries are rechargeable and dischargeable. They are used not only in portable electronic devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs) powered by electric drive systems.
[0003] When a high output voltage is required, multiple secondary battery cells (i.e., battery cells) are connected in series to configure a battery pack. Alternatively, depending on the required charge / discharge capacity of the battery pack, multiple battery cells can be connected in parallel to form a battery pack. The number of battery cells included in a battery pack can be set differently depending on the required output voltage and / or charge / discharge capacity.
[0004] Lithium-ion rechargeable batteries are classified into square rechargeable batteries (battery cells) in which the electrode assembly is housed within a metal can (battery casing), and cylindrical rechargeable batteries, as well as pouch-type rechargeable batteries in which the electrode assembly is sealed within a pouch casing made of aluminum laminates. In the case of cylindrical batteries, terminals (rivets) located on the closed side of the battery casing (battery can) pass through this closed side and contact a current collector arranged on the inner side of the battery can. The current collector and terminals can be connected by ultrasonic welding. When ultrasonic welding is performed by bringing a welding horn into contact with the current collector on the inner side of the battery can, the contact area between the current collector and the terminals can be welded.
[0005] Ultrasonic welding apparatuses have an anvil on which terminals are mounted and a welding head that applies pressure to a current collector. The welding head of an ultrasonic welding apparatus can have a structure with multiple protrusions to increase friction and pressure with the workpiece. To increase energy capacity, it is necessary to reduce the size of the core around which the electrode assembly of a cylindrical battery cell is wound, and in this case, it is also necessary to reduce the diameter of the ultrasonic welding head inserted into the core of the electrode assembly. However, as the diameter of the welding head decreases, a reduction in weld joint strength may occur due to the reduced welding area.
[0006] Another problem encountered during ultrasonic welding of manifolds and terminals is the difficulty in forming a complete knurling pattern at the outermost weld joint between the manifold and the terminals. As a result, a uniform knurling pattern cannot be produced along the outer edge of the weld joint, thus reducing the total knurling area. Consequently, excessive stress is concentrated on the irregular knurling pattern formed at the outer edge, increasing plastic deformation and potentially generating foreign matter or burrs. Therefore, a new knurling pattern is needed to ensure sufficient weld strength within a limited weld head diameter. The background art described above is intended to explain the context from which this disclosure originates and is not intended to imply that it was art known prior to the filing of this disclosure. Summary of the Invention
[0007] Technical issues
[0008] The purpose of this invention is to provide an ultrasonic welding apparatus, an ultrasonic welding method, a battery cell manufactured by the ultrasonic welding method, a battery pack, and a vehicle including the battery pack, which can ensure enhanced welding strength between the current collector and the terminal (rivet) of the battery cell.
[0009] In addition, the purpose of this disclosure is to prevent excessive stress concentration on the outermost part of the welded portion of the current collector and terminals of the battery cell, thereby preventing increased plastic deformation and reducing foreign matter or burrs.
[0010] The technical problems to be solved by this disclosure are not limited to those described above, and other problems that will be obvious to those skilled in the art will become apparent from the following detailed description.
[0011] Technical solution
[0012] An ultrasonic welding apparatus according to an embodiment of the present disclosure includes a welding tip for joining a current collector of a cylindrical battery cell to a rivet by ultrasonic welding. The welding tip includes a welding head disposed at its end to press at least one of the current collector and the rivet onto the workpieces to be welded via contact surfaces having an uneven configuration. The welding head includes a knurled portion comprising a plurality of protrusions disposed on the end surface of the welding tip to press the workpieces onto the workpieces using the uneven contact surfaces. The plurality of protrusions in the knurled portion are formed to project from the end surface in a direction toward the workpieces to be welded. Among the plurality of protrusions, a first protrusion disposed in the central region of the knurled portion is formed with a hexagonal cross-sectional shape. The cross-sectional area of the first protrusion gradually decreases in the direction toward the workpieces to be welded.
[0013] The first protrusion can be formed such that the first cross-sectional shape at the end point and the second cross-sectional shape at the starting point of the protrusion are each hexagonal in the direction toward the workpiece to be welded, and the first cross-sectional shape and the second cross-sectional shape can be arranged coaxially.
[0014] The aforementioned first protrusion can be arranged in a honeycomb structure.
[0015] Multiple protrusions may also include a second protrusion located in the outer region surrounding the central region of the knurled portion.
[0016] The second protrusion can be formed in a different shape than the first protrusion.
[0017] The aforementioned second protrusion can be formed into a truncated cone shape.
[0018] The outer protrusions of the first protrusion can be arranged at intervals from each other. The second protrusion can be arranged between the outer protrusions.
[0019] The second protrusion can be positioned at the location corresponding to the corner point of the hexagon.
[0020] An ultrasonic welding method according to an embodiment of the present disclosure includes the following steps: preparing an ultrasonic welding apparatus having a welding nozzle, wherein the welding nozzle includes a welding head located at the end of the welding nozzle to press at least one of the current collector of a cylindrical battery cell and a rivet with a contact surface having an uneven shape; and using the ultrasonic welding apparatus to join the current collector of the cylindrical battery cell to the rivet by ultrasonic welding.
[0021] The steps of joining by ultrasonic welding include pressing a welding head having a knurled portion against the workpiece to be welded, wherein the knurled portion includes a plurality of protrusions disposed on the end surface of the welding head, the protrusions being configured to protrude from the end surface toward the workpiece to be welded and defining a contact surface having an uneven configuration.
[0022] Among the multiple protrusions that are joined to the workpiece to be welded, the first protrusion located in the central region of the knurled portion is formed with a hexagonal cross-sectional shape and is pressed against the workpiece to be welded, and the first protrusion has a cross-sectional area that gradually decreases in the direction toward the workpiece to be welded.
[0023] In the step of joining by ultrasonic welding, the first protrusion can be arranged in a honeycomb structure and pressed against the workpiece to be welded.
[0024] In the step of joining by ultrasonic welding, among the multiple protrusions, the second protrusion located in the outer region of the knurled portion surrounding the central region is formed into a truncated cone shape and can be pressed into the outer region of the welded portion of the workpiece being welded.
[0025] In the step of joining by ultrasonic welding, the outer protrusions of the first protrusion are arranged spaced apart from each other and pressed into the edge region of the central region of the welded portion of the workpiece being welded; the second protrusion, arranged at a position corresponding to the corner of the hexagon, is arranged between the outer protrusions and can be pressed into the outer region of the welded portion of the workpiece being welded.
[0026] A cylindrical battery cell according to an embodiment of the present disclosure includes: a cylindrical battery casing; a cylindrical electrode assembly housed within the battery casing, the electrode assembly being formed by winding a first electrode, a second electrode, and a separator around a winding axis; a current collector disposed within the battery casing and electrically connected to at least one of the first and second electrodes; and a rivet, at least a portion of which is inserted through an opening in the battery casing and engaged with the current collector.
[0027] The aforementioned manifold and rivet are joined by ultrasonic welding, and multiple indentations are formed at the welded portions of the manifold and rivet by ultrasonic welding. The multiple indentations are formed by pressing the contact surface of the welding head, which has an uneven configuration, located at the end of the welding nozzle of the ultrasonic welding apparatus, onto at least one of the workpieces being welded, namely the manifold and the rivet. The multiple indentations are formed in a hexagonal cross-sectional shape corresponding to multiple protrusions of the knurled portion arranged on the end surface of the welding nozzle. The multiple indentations are formed to protrude from the end surface in the direction toward the workpiece being welded.
[0028] Among multiple indentations, the first indentation formed in the central region of the welded portion may include a first indentation groove formed by pressing into the workpiece being welded. The first indentation groove may be formed in the shape of a truncated hexagonal pyramid, the cross-sectional area of which decreases with increasing depth from the surface of the workpiece being welded.
[0029] Multiple indentations may include second indentation grooves arranged in the outer region of the weld portion surrounding the central region. The second indentation grooves may be formed in the shape of a truncated cone, the cross-sectional area of which decreases with increasing depth from the surface of the workpiece being welded.
[0030] According to embodiments of the present disclosure, a battery pack is provided, the battery pack including at least one cylindrical battery cell.
[0031] According to embodiments of the present disclosure, a vehicle is provided that includes at least one battery pack.
[0032] Beneficial effects
[0033] According to embodiments of this disclosure, an ultrasonic welding apparatus, an ultrasonic welding method, a battery cell, a battery pack, and a vehicle manufactured by the ultrasonic welding method are provided, which can ensure the welding strength between the current collector and the terminal (rivet) of a battery cell.
[0034] In addition, according to the embodiments of this disclosure, excessive stress concentration is prevented in the outermost part of the welded portion of the current collector and terminal of the battery cell, which prevents increased plastic deformation and can reduce foreign matter or burrs.
[0035] However, the beneficial effects of this disclosure are not limited to those described above, and other technical effects not explicitly mentioned will be readily understood by those skilled in the art from the following description. Attached Figure Description
[0036] Figure 1 This is a perspective view of a battery cell according to an embodiment of the present disclosure.
[0037] Figure 2 It is based on Figure 1 A three-dimensional view of the longitudinal cross-section of the battery cell in the embodiment of the invention.
[0038] Figure 3 It is based on Figure 1 A longitudinal cross-sectional view of the battery cell in the embodiment of the method.
[0039] Figure 4 This is a cross-sectional view showing the process of ultrasonically welding the current collector and rivets of a battery cell according to an embodiment of the present disclosure.
[0040] Figure 5 This is a cross-sectional view showing the welding head of the welding nozzle constituting an ultrasonic welding apparatus according to an embodiment of the present disclosure.
[0041] Figure 6 This is a plan view showing the welding head constituting an ultrasonic welding apparatus according to an embodiment of the present disclosure.
[0042] Figure 7 This is a plan view showing an enlarged view of the protrusion of the welding head constituting an ultrasonic welding apparatus according to an embodiment of the present disclosure.
[0043] Figure 8 This is a side view showing an enlarged view of the protrusion of the welding head constituting an ultrasonic welding apparatus according to an embodiment of the present disclosure.
[0044] Figure 9 This is a cross-sectional view showing the welding head of the welding nozzle constituting an ultrasonic welding apparatus according to another embodiment of the present disclosure.
[0045] Figure 10 It shows the basis Figure 9A plan view of the welding head of the ultrasonic welding apparatus according to the embodiment.
[0046] Figure 11 It shows the basis Figure 9 A side view of an enlarged view of the second protrusion of the welding head constituting the ultrasonic welding apparatus according to the embodiment.
[0047] Figure 12 This is a diagram illustrating a battery pack including battery cells according to an embodiment of the present disclosure.
[0048] Figure 13 It is used to explain including at least one Figure 12 A picture of a vehicle with a battery pack. Detailed Implementation
[0049] The advantages and features of this disclosure, as well as the methods for implementing this disclosure, will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings. However, this disclosure is not limited to the embodiments disclosed below, but can be implemented in various other forms. These embodiments are provided only to ensure a complete disclosure and to fully inform those skilled in the art of the scope of the invention. This disclosure is defined only by the scope of the appended claims. Therefore, in some embodiments, well-known process steps, well-known apparatus structures, and well-known techniques have not been described in detail to avoid obscuring the disclosure. Throughout the specification, the same reference numerals denote the same elements.
[0050] In the accompanying drawings, the thickness of layers and regions may be exaggerated for clarity. Throughout the specification, similar components are indicated by the same reference numerals. When an element such as a layer, film, region, or plate is referred to as being "on" another element, the element may be directly on the other element, or there may be intermediate elements present. Conversely, when a component is referred to as being "directly on" another component, it should be understood that no intermediate elements exist. Furthermore, when an element is referred to as being "below" another element, the element may be directly disposed below the other element, or there may be one or more intermediate elements between them. Conversely, when a component is referred to as being "directly below" another component, it should be understood that no intermediate elements exist.
[0051] The following describes an ultrasonic welding apparatus according to embodiments of the present disclosure and a cylindrical battery cell manufactured by the ultrasonic welding apparatus, followed by a detailed description of an ultrasonic welding method according to embodiments of the present disclosure. According to one embodiment of the present disclosure, the ultrasonic welding apparatus and ultrasonic welding method apply a knurled portion having hexagonal cross-section protrusions to the welding head of a welding nozzle used when ultrasonically welding the current collector of a cylindrical battery cell to a rivet, thereby increasing the pressure area of the workpiece (current collector, rivet) and ensuring sufficient weld joint strength. According to another embodiment of the present disclosure, the ultrasonic welding apparatus and ultrasonic welding method employ a knurled portion in which protrusions having a hexagonal cross-section are provided in the central region of the welding head, and protrusions having a circular cross-section are provided in the outer region, thereby preventing excessive stress concentration at the outermost portion of the welded portion between the current collector and the terminal of the battery cell, thereby reducing plastic deformation and minimizing the generation of foreign matter or burrs.
[0052] According to embodiments of the present disclosure, a cylindrical battery cell is configured such that an electrode assembly is inserted into a cylindrical battery casing. For ease of explanation, in this specification, the direction corresponding to the length direction of the winding axis of the electrode assembly wound in a core-like form is referred to as the "axial direction," "vertical direction," or "height direction." The direction around the winding axis is referred to as the "circumferential direction" or "outer circumferential direction." The direction toward or away from the winding axis is referred to as the "radial direction." The direction in the radial direction approaching the winding axis can be referred to as the "centripetal direction," and the direction away from the winding axis can be referred to as the "centrifugal direction."
[0053] Figure 1 This is a perspective view of a battery cell according to an embodiment of the present disclosure. Figure 2 It is based on Figure 1 A three-dimensional view of the longitudinal cross-section of the battery cell in the embodiment of the invention. Figure 3 It is based on Figure 1 A longitudinal cross-sectional view of the battery cell according to the embodiment. (Refer to...) Figures 1 to 3 According to one embodiment of the present disclosure, the battery cell 1 includes an electrode assembly 10, a battery casing 20, a current collector 30, a battery cap 40, a sealing gasket 50, a current collector plate 60, and rivets 70. The battery cell of the present disclosure is not limited to... Figures 1 to 3 The shape shown is applicable to battery cells in other configurations. To avoid obscuring the essence of the invention, components for electrical connections, such as busbars, cooling units, and power terminals, are omitted from the drawings.
[0054] According to one embodiment of this disclosure, the battery cell 1 can be a cylindrical secondary battery (cylindrical battery cell). The electrode assembly 10 can be formed into a cylindrical shape having a core and an outer peripheral surface by winding a first electrode (e.g., negative electrode), a second electrode (e.g., positive electrode), and a separator interposed therebetween around a winding axis. The electrode assembly 10 can be a wound core type. An additional separator can be provided on the outer peripheral surface of the electrode assembly 10 for insulation from the battery housing 20. The electrode assembly 10 can have a winding structure known in the art, but is not limited thereto.
[0055] The first electrode includes a first electrode current collector and a first electrode active material coated on one or both surfaces of the first electrode current collector. In the width direction of the first electrode (with... Figure 1 At one end (upper end) of the battery cell shown (parallel to the height direction), there is an uncoated portion that is not coated with the first electrode active material. That is, along the winding direction, the first electrode includes an uncoated portion exposed to the outside of the separator at one longitudinal end where the active material is not coated. The uncoated portion that serves as the first electrode tab is referred to as the first uncoated portion 11. The first uncoated portion 11 is disposed on the upper side relative to the electrode assembly 10 housed in the battery housing 20 in the height direction. At least a portion of the first uncoated portion 11 itself serves as an electrode tab. The first uncoated portion 11 may be, for example, a negative electrode tab.
[0056] The second electrode includes a second electrode current collector and a second electrode active material layer coated on one or both surfaces of the second electrode current collector. Based on the width (height) direction of the second electrode, there is an uncoated portion at the opposite end where the second electrode active material is not coated. That is, in the winding direction, the second electrode includes an uncoated portion exposed to the outside of the separator at the opposite longitudinal end where no active material layer is formed. The uncoated portion serving as a second electrode tab is referred to as the second uncoated portion 12. The second uncoated portion 12 is disposed on the lower side relative to the height direction of the electrode assembly 10 housed in the battery housing 20. At least a portion of the second uncoated portion 12 itself serves as an electrode tab. The second uncoated portion 12 can be, for example, a positive electrode tab.
[0057] The battery housing 20 is a generally cylindrical receiving portion with an opening formed on one side, and may be made of a conductive metal. The battery housing 20 is configured to receive and accommodate the electrode assembly 10 of a secondary battery. The side surface of the battery housing 20 and the bottom surface positioned opposite the opening 20a may be integrally formed. In the height direction, the upper side of the battery housing 20 may be open, and the lower side may be closed. The bottom surface of the battery housing 20 may be formed to have a substantially flat shape. The battery housing 20 is configured to receive the electrode assembly 10 and the electrolyte through the opening 20a formed on its top.
[0058] The battery housing 20 may include a rolled edge 21 formed in an end region adjacent to an opening 20a at its top, and a crimping portion 22 formed on the rolled edge 21. The rolled edge 21 has a recessed shape formed by pressing the outer peripheral portion of the battery housing 20 inward to a predetermined depth. The rolled edge 21 can be pressed inward in the region between the opening 20a of the battery housing 20 and the internal receiving space for accommodating the electrode assembly 10.
[0059] The crimped portion 21 provides a support surface on which the sealing gasket 50 and the battery cap 40 can be disposed. Additionally, the crimped portion 21 provides a support surface on which at least a portion of the periphery of the current collector 30 can be disposed and attached. At least a portion of the edge of the current collector 30, at least a portion of the edge of the sealing gasket 50, and at least a portion of the edge of the battery cap 40 can be disposed on the upper surface of the crimped portion 21. The crimped portion 21 can be formed by pressing inwardly against the outer peripheral surface of the battery housing 20 in a region adjacent to the opening 20a of the battery housing 20, after the electrode assembly 10 has been inserted through the opening 20a and is received within the battery housing 20.
[0060] To stably support the current collector 30, battery cap 40, and sealing gasket 50, the upper surface of the rolled edge 21 can extend in a direction substantially parallel to the bottom surface of the battery housing 20 (that is, substantially perpendicular to the sidewall of the battery housing 20). The rolled edge 21 prevents the electrode assembly 10, whose size corresponds to the inner diameter of the internal accommodating space of the battery housing 20, from protruding through the opening 20a at the top of the battery housing 20, and serves as a support for the battery cap 40 and the like to be placed on it.
[0061] A crimping portion 22 extends upward from and is formed above the rolled edge portion 21. The crimping portion 22 has a curved shape that extends to surround at least a portion of the edge and upper surface of the battery cap 40 disposed on the rolled edge portion 21. The battery cap 40 is secured to the rolled edge portion 21 by the crimping portion 22. The crimping portion 22 extends inwardly from the circumferential edge of the battery housing 20 along the radial (centripetal) direction of the battery cell 1. The crimping portion 22 is disposed in a region corresponding to the edge of the upper surface of the battery cap 40, in which the crimping portion 22 secures the battery cap 40 and prevents it from separating upwards.
[0062] The upper end of the crimping portion 22 extends inward a predetermined distance along the radial direction of the battery cell 1 and is bent to wrap around a portion of the upper surface of the battery cap 40, thereby fixing the periphery of the upper surface of the battery cap 40. The edge region of the battery cap 40 is inserted between the upper end of the crimping portion 22 and the rolled edge portion 21, fixed to the battery housing 20, and covers the opening 20a of the battery housing 20.
[0063] The current collector 30 is housed inside the battery casing 20. The current collector 30 is made of a conductive metal material and is electrically connected to the electrode assembly 10. The current collector 30 can be electrically connected to the battery casing 20. That is, the current collector 30 can electrically connect the first electrode of the electrode assembly 10 to the battery casing 20. The current collector 30 may include a support portion 31, a tab engagement portion 32, and a casing engagement portion 33.
[0064] The current collector 30 has a support portion 31 and a tab engagement portion 32 disposed above the electrode assembly 10. The support portion 31 is disposed on one side of the electrode assembly 10. The tab engagement portion 32 extends from the support portion 31 and engages with the first uncoated portion 11 of the electrode assembly 10. For example, when disposed on the first uncoated portion 11 of the electrode assembly 10, the tab engagement portion 32 can be engaged with the electrode assembly 10 by welding in a certain area. The tab engagement portion 32 of the current collector 30 may be located below the lower surface of the crimped portion 21.
[0065] A through-hole (not shown) can be formed in the current collector 30 to allow the flame generated inside the battery cell 1 to be smoothly discharged. Therefore, even if thermal runaway occurs on the electrode assembly 10 side, the flame and exhaust gas generated from the electrode assembly 10 can be smoothly discharged through the through-hole without being blocked by the current collector 30 located above the electrode assembly 10. Thus, the flame can be prevented from propagating toward the rolled edge 21 located near the electrode assembly 10 and the current collector 30, thereby preventing the formation of pinholes in the rolled edge 21 and suppressing the spread of the flame to other battery cells 1 adjacent to the battery cell 1 where the flame occurred.
[0066] The support portion 31 may have a current collector hole H2 formed at a position corresponding to the winding hole H1 formed approximately at the center of the electrode assembly 10. The winding hole H1 and the current collector hole H2, which are in communication with each other, can be used as channels for inserting a welding electrode (welding nozzle) for welding between the electrode terminals of the electrode assembly 10 and the current collector 30, or between the electrode terminals and the lead tabs (not shown).
[0067] If the diameter of the current collector hole H2 is much smaller than the diameter of the winding hole H1, the opening of the winding hole H1 may be covered, thereby degrading the electrolyte filling characteristics and failing to ensure sufficient space for insertion into the welding device or for laser irradiation. Therefore, in order to prevent the current collector hole H2 from covering the winding hole H1 formed in the core of the electrode assembly 10, the winding hole H1 of the electrode assembly 10 may have a diameter that is substantially the same as or larger than the diameter of the current collector hole H2.
[0068] The housing engagement portion 33 extends from the support portion 31 toward the surrounding area and engages with the inner wall surface of the battery housing 20. The housing engagement portion 33 can extend from the support portion 31 and be electrically engaged with the inner surface of the battery housing 20. For example, the housing engagement portion 33 can be engaged with the upper surface of the rolled edge portion 21 (which is part of the inner surface of the battery housing 20).
[0069] The inner diameter of the region of the battery housing 20 where the rolled edge 21 is formed is smaller than the inner diameter of the electrode assembly 10. For stable contact and connection, the rolled edge 21 may have a shape extending in a direction substantially parallel to the bottom surface of the battery housing 20 (that is, substantially perpendicular to the sidewalls of the battery housing 20). The housing joint 33 may be welded to the upper surface of the rolled edge 21. The welding for joining the battery housing 20 and the current collector 30 may be performed, for example, by laser welding, ultrasonic welding, or spot welding.
[0070] The battery cap 40 is configured to cover the opening 20a of the battery housing 20. The battery cap 40 can be joined to the battery housing 20 by a crimping process using a sealing gasket 50 to seal the opening 20a of the battery housing 20. The battery cap 40 may include a vent 41 configured to prevent an increase in internal pressure caused by gas generated inside the battery housing 20.
[0071] The vent 41 can be configured to rupture when the internal pressure of the battery casing 20 increases above a predetermined level. The vent 41 is formed in a portion of the battery cap 40 and can be structurally weaker than the surrounding area so that it is easily ruptured when internal pressure is applied, for example, due to thermal runaway. For example, the vent 41 can be a region with a smaller thickness than the surrounding area. The vent 41 can be formed as a substantially circular closed loop.
[0072] The battery cap 40 covers the opening 20a formed on one side of the battery housing 20. The battery cap 40 can be fixed by a crimping portion 22 formed at the top of the battery housing 20. To improve the fixing force and sealing of the battery housing 20, a sealing gasket 50 is inserted between the battery housing 20 and the battery cap 40, and between the current collector 30 and the battery cap 40. Therefore, the current collector 30 can be inserted between the rolled edge 21 of the battery housing 20 and the sealing gasket 50 to be positioned between them. The current collector 30 inserted between the rolled edge 21 and the sealing gasket 50 can be fixed by bending the crimping portion 22 that extends upward from the rolled edge 21.
[0073] A sealing gasket 50 is configured to surround the battery cap 40 and hermetically seal the space between the battery cap 40 and the battery housing 20. The sealing gasket 50 maintains the airtightness between the battery housing 20 and the battery cap 40. By ensuring excellent sealing performance, the sealing gasket 50 prevents moisture from penetrating into the battery housing 20 and also prevents electrolyte or gas inside the battery housing 20 from leaking to the outside through the gap between the battery housing 20 and the battery cap 40.
[0074] The current collector 60 is housed inside the battery housing 20. The current collector 60 is made of conductive metal and is electrically connected to the electrode assembly 10. The current collector 60 is electrically connected to the second electrode of the electrode assembly 10. The current collector 60 is disposed above the electrode assembly 10. The current collector 60 is disposed on the lower surface of the electrode assembly 10 and is joined to the second uncoated portion 12 of the electrode assembly 10. When disposed on the second uncoated portion 12 of the electrode assembly 10, the current collector 60 can be joined to the electrode assembly 10 by welding over a specific area. The welding for joining the battery housing 20 and the current collector 30 can be performed, for example, by laser welding, ultrasonic welding, or spot welding.
[0075] A rivet 70 is inserted into and engaged with an opening formed in the bottom of the battery housing 20. An insulating portion 80 may be inserted between the rivet 70 and the opening in the battery housing 20. The insulating portion 80 electrically insulates the rivet 70 from the battery housing 20. Figure 4 This is a cross-sectional view illustrating the process of ultrasonically welding a current collector 60 and a rivet 70 of a battery cell according to an embodiment of the present disclosure. The current collector 60 and the rivet 70 of the battery cell can be welded together using an ultrasonic welding apparatus. The ultrasonic welding apparatus may include a welding nozzle 100. The welding nozzle 100 can be inserted into a winding hole H1 to ultrasonically weld and join the current collector 60 and the rivet 70 as workpieces. A welded portion 110 is formed through the welding nozzle 100, and the current collector 60 and the rivet 70 can be joined through the welded portion 110.
[0076] The rivet 70 may include a rivet body having a generally cylindrical shape, and upper and lower protrusions extending and protruding from the upper and lower surfaces of the rivet body in a radial direction parallel to the horizontal direction, respectively, such that the rivet body can be positioned within an opening formed in the bottom of the battery housing 20. The rivet body of the rivet 70 may be located within an opening formed in the central portion of the bottom of the battery housing 20. For this purpose, the outer diameter of the rivet body may be formed to be smaller than the diameter of the opening formed in the bottom of the battery housing 20.
[0077] The upper protrusion of the rivet 70 can be inserted through an opening formed in the lower surface of the battery housing 20 and is positioned between the battery housing 20 and the current collector 60. The outer diameter of the upper protrusion can be larger than the diameter of the opening formed in the lower surface of the battery housing 20. The lower protrusion of the rivet 70 is located on the outer side of the bottom surface of the battery housing 20. The outer diameter of the lower protrusion can be larger than the diameter of the opening formed in the bottom of the battery housing 20. To allow the rivet 70 to be smoothly inserted through the opening of the battery housing 20 and to allow the rivet 70 to be stably connected through the opening of the battery housing 20, the outer diameter of the lower protrusion can be larger than the outer diameter of the upper protrusion.
[0078] The insulating portion 80 may have a shape corresponding to the rivet 70. Therefore, the insulating portion 80 may include a cylindrical insulating body, an upper insulating protrusion having a disc-shaped ring, and a lower insulating protrusion. The vertical height of the insulating portion 80 may be set to be the same as the distance between the bottom surface of the upper protrusion and the upper surface of the lower protrusion of the rivet 70. The inner diameter of the insulating body of the insulating portion 80 may be set to be equal to the diameter of the opening formed in the bottom of the battery housing 20, and the outer diameter may be set to be equal to the outer diameter of the rivet body of the rivet 70.
[0079] The upper insulating protrusion of the insulating portion 80 can be formed by protruding and extending from the upper surface of the insulating body of the insulating portion 80 in a radial direction parallel to the horizontal direction. The upper insulating protrusion is inserted through an opening formed in the lower surface of the battery housing 20 and is inserted between the lower surface of the battery housing 20 and the upper protrusion of the rivet 70. The outer diameter of the upper insulating protrusion can be formed to be larger than the diameter of the opening formed in the bottom of the battery housing 20.
[0080] The lower insulating protrusion of the insulating portion 80 can be formed by protruding and extending from the lower surface (bottom) of the insulating body in a radial direction parallel to the horizontal direction. The lower insulating protrusion is located outside the bottom surface of the battery housing 20. The outer diameter of the lower insulating protrusion can be formed to be larger than the diameter of the opening formed in the bottom surface of the battery housing 20. In order to allow the insulating portion 80 to be smoothly inserted through the opening of the battery housing 20 and stably connected to the opening of the battery housing 20, the outer diameter of the lower insulating protrusion can be formed to be larger than the outer diameter of the upper insulating protrusion. In order to ensure the insulating performance of the insulating portion 80, the outer diameter of the upper insulating protrusion can be formed to be larger than the outer diameter of the upper protrusion of the rivet 70, and the outer diameter of the lower insulating protrusion can be formed to be larger than the outer diameter of the lower protrusion of the rivet 70.
[0081] Next, an ultrasonic welding apparatus for ultrasonically welding the rivets 70 of the aforementioned battery cells to the current collector 60 will be described. Figure 5 This is a cross-sectional view showing the welding head of the welding nozzle constituting an ultrasonic welding apparatus according to an embodiment of the present disclosure. Figure 6 This is a plan view showing the welding head constituting an ultrasonic welding apparatus according to an embodiment of the present disclosure. Figure 7 This is a plan view showing an enlarged view of the protrusion of the welding head constituting an ultrasonic welding apparatus according to an embodiment of the present disclosure. Figure 8 This is a side view showing an enlarged view of the protrusion of the welding head constituting an ultrasonic welding apparatus according to an embodiment of the present disclosure.
[0082] Reference Figures 5 to 8 The welding nozzle 100 includes a welding head 200 disposed at its end and having a plurality of protrusions 210 configured to press at least one workpiece selected from the manifold 60 and the rivet 70 into contact with a contact surface having an uneven configuration. The welding head 200 includes a knurled portion comprising a plurality of protrusions 210 disposed on the end surface of the welding nozzle 100 to press the workpiece using the contact surface having an uneven shape.
[0083] The plurality of protrusions 210 constituting the knurling portion are formed to protrude from the end surface of the welding nozzle 100 in the direction toward the workpiece. The plurality of protrusions 210 may include a first protrusion 210 disposed in the central region of the knurling portion. The first protrusion 210 may be formed with a hexagonal cross-sectional shape and may be formed such that the cross-sectional area decreases in the direction toward the workpiece.
[0084] The first protrusion 210 can be formed such that, based on the direction toward the workpiece, the first cross-sectional shape at the end point 212 and the second cross-sectional shape at the protrusion starting point 211 each have a hexagonal cross-sectional shape. The first cross-sectional shape at the end point 212 and the second cross-sectional shape at the protrusion starting point 211 of the first protrusion 210 can be formed to be arranged coaxially. That is, the first protrusion 210 can have a truncated conical shape. The first protrusion 210 can be arranged in a hexagonal honeycomb structure.
[0085] The first protrusion 210 may have six trapezoidal sides 213 between the hexagonal protrusion starting point 211 and the hexagonal end point 212. The six sides 213 of the first protrusion 210, together with the hexagonal end points 212, press the current collector 60, which is the workpiece, toward the rivet 70, thereby enabling the current collector 60 and the rivet 70 to be ultrasonically welded with a large pressing area.
[0086] According to embodiments of this disclosure, by using a welding head with a knurled pattern having a hexagonal cross-section to weld the current collector 60 and rivet 70 of the battery cell, the surface area in contact with the substrate material can be increased, and sufficient welding area can be ensured. Therefore, even if the diameter of the welding head is reduced to increase energy capacity by reducing the diameter of the winding hole H1, sufficient welding strength can be ensured.
[0087] The first cross-sectional dimension (b) at the end point 212 of the first protrusion 210 can be formed to be smaller than the second cross-sectional dimension (a) at the starting point 211 of the protrusion. Therefore, the six sides 213 of the first protrusion 210 are formed as inclined surfaces. The first cross-section at the end point 212 of the first protrusion 210 and the six sides 213 serve as areas for applying pressure to the welded component. In order to ensure a proper pressing area for ultrasonic welding and to form an inclined angle suitable for applying pressure to the workpiece at the sides 213, the first cross-sectional dimension (b) at the end point 212 of the first protrusion 210 can be designed to be in the range of 1 / 10 to 1 / 2 of the second cross-sectional dimension (a) at the starting point 211 of the protrusion.
[0088] In embodiments of this disclosure, to ensure a suitable pressing area for the workpiece, the second cross-sectional dimension (a) at the protrusion initiation point 211 of the first protrusion 210 can be designed to be in the range of 0.1 mm to 1 mm. Figure 6 In this embodiment, the knurled portion of the welding head 200 includes 19 first protrusions 210. When the pressing area (welding area) of one first protrusion 210 is 0.2 mm... 2 up to 0.3 mm 2 At that time, the total pressing area became 3.8 mm. 2 Up to 5.7 mm 2 .
[0089] Conversely, when the knurled protrusions are designed with a square cross-sectional shape (comparative example), the pressing area of each protrusion is 0.3 mm. 2 up to 0.4 mm 2 However, since the knurled portion of the welding head 200 of the same area includes 9 protrusions, the total pressing area becomes 2.7 mm. 2 Up to 3.6 mm 2 Therefore, according to embodiments of this disclosure, the total pressing area of the welding head of the ultrasonic welding apparatus can be increased by about 40% or more compared to the total pressing area of a welding head having a square cross-sectional shape.
[0090] Figure 9 This is a cross-sectional view showing the welding head of the welding nozzle constituting an ultrasonic welding apparatus according to another embodiment of the present disclosure. Figure 10 It shows the basis Figure 9 A plan view of the welding head of the ultrasonic welding apparatus according to the embodiment. Figure 11 It means according to Figure 9 A side view magnified of the second protrusion of the welding head constituting the ultrasonic welding apparatus of the embodiment. In the description Figures 9 to 11In implementing this method, redundant descriptions of components that are the same as or correspond to those in the previously described embodiments may be omitted. Hereinafter, we will focus on describing components that differ from those in the embodiments described above.
[0091] Reference Figures 9 to 11 According to embodiments of the present disclosure, the knurled portion of the welding head 200 constituting the ultrasonic welding apparatus may include a first protrusion 220 formed in the central region 121 of the knurled portion and a second protrusion 230 disposed in the outer region 122 surrounding the central region 121 of the knurled portion. Figures 9 to 11 The first protrusion 220 can be with Figures 5 to 8 The first protrusion 210 has the same / similar shape.
[0092] The second protrusion 230 can be formed in a different shape than the first protrusion 220. The second protrusion 230 can be formed in the shape of a truncated cone. The outer protrusions of the first protrusion 220 can be arranged at intervals. The second protrusion 230 can be arranged between the outer protrusions of the first protrusion 220. The second protrusion 230 can be arranged at a position corresponding to the corner point of the hexagon.
[0093] The second protrusion 230 can be configured such that its cross-sectional area decreases in the direction toward the workpiece. The second protrusion 230 can be configured such that, based on the direction toward the workpiece, the first cross-sectional shape at the end point 232 and the second cross-sectional shape at the protrusion starting point 231 each have a circular shape. The first cross-sectional shape at the end point 232 and the second cross-sectional shape at the protrusion starting point 231 of the second protrusion 230 can be coaxially arranged.
[0094] Since the shape of the first protrusion 220 is the same as or similar to that of the first protrusion 210 in the above embodiment, its description will be omitted. The first cross-sectional dimension (d) at the end point 232 of the second protrusion 230 can be formed to be smaller than the second cross-sectional dimension (c) at the protrusion initiation point 231. Therefore, the side portion 233 of the second protrusion 230 is formed as an inclined surface. The first cross-section at the end point 232 and the side portion 233 of the second protrusion 230 serve as areas for pressing the workpiece. In order to ensure a proper pressing area for ultrasonic welding and to form an inclination angle suitable for applying pressure to the workpiece at the side portion 233, the first cross-sectional dimension (d) at the end point 232 of the second protrusion 230 can be designed to be in the range of 1 / 10 to 1 / 2 of the second cross-sectional dimension (c) at the protrusion initiation point 231.
[0095] according to Figures 9 to 11In this implementation, by combining various knurled patterns of protrusions, the pressing area of the welding head in contact with the substrate material can be expanded, and even within a limited welding head diameter, the weld joint strength between the current collector 60 and the rivet 70 can be ensured. Therefore, the energy capacity can be increased by reducing the core size of the cylindrical battery cell. Furthermore, according to... Figures 9 to 11 In this implementation, by alternating between knurling patterns with hexagonal and circular cross-sections, a complete knurling pattern can be applied to the outermost region, reducing the appearance of foreign objects and burrs in the outer region of the weld. Furthermore, by arranging the knurling of truncated cones in the outer region of the weld head, stress concentration caused by increased curvature can be prevented, and by reducing the stress in the outer region of the weld head where displacement due to torsional vibration is large, the amount of plastic deformation can be reduced.
[0096] An ultrasonic welding method according to an embodiment of the present disclosure may include the step of preparing an ultrasonic welding apparatus as described above, and the step of ultrasonically welding and joining a current collector 60 of a cylindrical battery cell to a rivet 70 by means of a welding nozzle of the ultrasonic welding apparatus, the welding nozzle of the ultrasonic welding apparatus having a knurled pattern of protrusions in a hexagonal cross-section shape or a combination of protrusions in a hexagonal cross-section shape and a circular cross-section shape.
[0097] When the ultrasonic welding method is performed using the ultrasonic welding apparatus according to an embodiment of the present disclosure, multiple indentations 61, 62, and 63 corresponding to the knurled pattern (protrusion) of the welding nozzle 100 constituting the ultrasonic welding apparatus can be formed at the welding portion 110 of the manifold 60 and the rivet 70 by ultrasonic welding. Multiple indentations 61, 62, and 63 can be formed by pressing the uneven contact surface of the welding head 200 provided at the end of the welding nozzle 100 of the ultrasonic welding apparatus onto at least one workpiece among the manifold 60 and the rivet 70.
[0098] Multiple indentations 61, 62, 63 can be formed into hexagonal cross-sectional shapes corresponding to the multiple protrusions 210, 220, 230 of the knurled portion arranged on the end surface of the welding nozzle 100 (see...). Figure 5 Alternatively, it can be arranged in a combination of hexagonal and circular cross-sectional shapes (see...). Figure 9 Multiple indentations 61, 62, and 63 can be formed to protrude from the end surface in the direction toward the workpiece.
[0099] Among the plurality of indentations 61, 62, and 63, the first indentations 61 and 62 formed in the central regions 111 and 121 of the welded portion 110 may include first indentation grooves formed by pressing into the workpiece. The first indentation groove may be formed in the shape of a truncated hexagonal pyramid, the cross-sectional area of which decreases with increasing depth from the workpiece surface. Among the plurality of indentations 61, 62, and 63, the second indentation groove of the second indentation 63 arranged in the outer regions 112 and 122 surrounding the central regions 111 and 121 of the welded portion 110 may be formed in the shape of a truncated cone, the cross-sectional area of which decreases with increasing depth from the workpiece surface.
[0100] The plurality of indentations 61, 62, 63 formed on at least one workpiece in the manifold 60 and rivet 70 are recessed shapes corresponding to the knurled pattern (protrusion shape) of the welding head of the ultrasonic welding apparatus, and the strength of the weld joint can be increased by increasing the pressing area by the knurled portion of the welding head of the ultrasonic welding apparatus. In addition, according to the embodiment having indentations 63 corresponding to protrusions with hexagonal and circular cross sections, the weld joint strength can be ensured, and the increase in plastic deformation due to excessive stress concentration at the outermost portion of the welded portion of the manifold 60 and rivet 70 can be prevented, and the effect of reducing foreign matter or burrs can also be provided.
[0101] Figure 12 This is a diagram illustrating a battery pack including battery cells according to an embodiment of the present disclosure. (Refer to...) Figure 12 According to an embodiment of the present disclosure, the battery pack 3 includes a battery assembly and a battery pack housing 2 that houses the battery assembly, wherein a plurality of battery cells 1, as described above, are electrically connected according to an embodiment of the present disclosure. Figure 13 It is used to explain including at least one Figure 12 A diagram of a vehicle with a battery pack. See also... Figure 13 The vehicle 5 according to an embodiment of the present disclosure may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle, and may include a battery pack 3 according to one embodiment of the present disclosure. The vehicle 5 may include a four-wheeled vehicle and a two-wheeled vehicle. The vehicle 5 operates by receiving electricity from the battery pack 3 according to one embodiment of the present disclosure.
[0102] Although this disclosure has been described with reference to limited embodiments and accompanying drawings, it is not limited thereto, and those skilled in the art will understand that various modifications and variations can be made within the technical spirit of this disclosure and the equivalents of the set forth claims.
Claims
1. An ultrasonic welding apparatus, the ultrasonic welding apparatus comprising: A welding nozzle, used for ultrasonic welding to join the current collector of a cylindrical battery cell to a rivet. The welding nozzle includes: A welding head, located at the end of the welding nozzle, presses against at least one of the workpieces to be welded, namely the manifold and the rivet, using an uneven contact surface. The welding head includes: The knurled portion includes a plurality of protrusions arranged on the end surface of the welding nozzle to press the workpiece being welded using the uneven contact surface. The knurled portion has multiple protrusions that protrude from the end surface in a direction toward the workpiece being welded. Among the plurality of protrusions, the first protrusion located in the central region of the knurled portion is formed with a hexagonal cross-sectional shape, and The first protrusion has a cross-sectional area that gradually decreases in the direction toward the workpiece being welded.
2. The ultrasonic welding apparatus according to claim 1, wherein, The first protrusion is formed such that a first cross-sectional shape at the end point and a second cross-sectional shape at the starting point of the protrusion, based on the direction toward the workpiece being welded, are each hexagonal cross-sectional shapes. The first cross-sectional shape and the second cross-sectional shape are arranged coaxially.
3. The ultrasonic welding apparatus according to claim 1, wherein, The first protrusion is arranged in a honeycomb structure.
4. The ultrasonic welding apparatus according to claim 1, wherein, The plurality of protrusions further includes a second protrusion disposed in the outer region of the knurled portion surrounding the central region, and The second protrusion is formed in a different shape than the first protrusion.
5. The ultrasonic welding apparatus according to claim 4, wherein, The second protrusion is formed in the shape of a truncated cone.
6. The ultrasonic welding apparatus according to claim 5, wherein, The outermost protrusions arranged in the first protrusion are spaced apart from each other, and The second protrusion is arranged between the outer protrusions.
7. The ultrasonic welding apparatus according to claim 6, wherein, The second protrusion is positioned at a location corresponding to the corner point of the hexagon.
8. An ultrasonic welding method, the ultrasonic welding method comprising the following steps: An ultrasonic welding apparatus is prepared, comprising a welding nozzle, wherein the welding nozzle includes a welding head at its end for pressing at least one of a current collector of a cylindrical battery cell and a rivet, using an uneven contact surface; and The current collector of the cylindrical battery cell is joined to the rivet by the ultrasonic welding device using ultrasonic welding. The step of joining by ultrasonic welding includes the following steps: The welding head, including the knurled portion, is pressed against the workpiece to be welded using the uneven contact surface, wherein the knurled portion includes a plurality of protrusions arranged on the end surface of the welding head, and the plurality of protrusions are formed to project from the end surface in a direction toward the workpiece to be welded. In the step of joining by ultrasonic welding, the first protrusion among the plurality of protrusions joined to the workpiece to be welded, which is arranged in the central region of the knurled portion, is formed with a hexagonal cross-sectional shape and is pressed against the workpiece to be welded. The first protrusion has a cross-sectional area that gradually decreases in the direction toward the workpiece to be welded.
9. The ultrasonic welding method according to claim 8, wherein, In the step of joining by ultrasonic welding, the first protrusion is arranged in a honeycomb structure to be pressed against the workpiece to be welded.
10. The ultrasonic welding method according to claim 8, wherein, In the step of joining by ultrasonic welding, the second protrusion among the plurality of protrusions, located in the outer region of the knurled portion surrounding the central region, is formed into a truncated cone shape to be pressed against the outer region of the welded portion of the workpiece being welded.
11. The ultrasonic welding method according to claim 10, wherein, In the step of joining by ultrasonic welding. The outermost protrusions of the first protrusion are arranged spaced apart from each other to be pressed against the edge region of the central region of the welded portion of the workpiece being welded, and The second protrusion, located at a position corresponding to the corner of the hexagon, is arranged between the outer protrusions to be pressed against the outer region of the welded portion of the workpiece.
12. A cylindrical battery cell, the cylindrical battery cell comprising: Cylindrical battery casing; A cylindrical electrode assembly, which is housed in the battery housing and formed by winding a first electrode, a second electrode, and a separator around a winding axis; A current collector, wherein the current collector is disposed within the battery housing and electrically connected to at least one of the first electrode and the second electrode of the electrode assembly; as well as A rivet, at least a portion of which is inserted through an opening in the battery casing and engaged with the current collector. The manifold and the rivet are joined by ultrasonic welding, and multiple indentations are formed at the welded portion of the manifold and the rivet by the ultrasonic welding. The plurality of indentations are formed by pressing the uneven contact surface of the welding head, located at the end of the welding nozzle of the ultrasonic welding device, against at least one of the workpieces to be welded, namely the manifold and the rivet. The plurality of indentations are formed into a hexagonal cross-sectional shape corresponding to the plurality of protrusions of the knurled portion arranged on the end surface of the welding nozzle. The plurality of indentations are formed to protrude from the end surface in a direction toward the workpiece being welded. The first indentation among the plurality of indentations, formed in the central region of the welded portion, includes a first indentation groove formed by pressing into the workpiece being welded. The first pressing groove has a truncated hexagonal pyramid shape, and the cross-sectional area of the truncated hexagonal pyramid shape decreases with increasing depth from the surface of the workpiece being welded.
13. The cylindrical battery cell according to claim 12, wherein, The plurality of indentations includes a second indentation groove, the second indentation groove being disposed in the outer region surrounding the central region of the welded portion, and The second pressing groove is formed in the shape of a truncated cone, the cross-sectional area of which decreases from the surface of the workpiece to be welded as the depth increases.
14. A battery pack comprising at least one cylindrical battery cell according to claim 12.
15. A vehicle comprising at least one battery pack according to claim 14.