Ultrasonic welding apparatus, secondary battery, and method of manufacturing secondary battery

Abstract

The invention discloses an ultrasonic welding apparatus, a secondary battery, and a method of manufacturing the secondary battery. The ultrasonic welding apparatus includes: an anvil configured to support a lower portion of a welding target; and a welding head above the anvil with a welding target between the welding head and the anvil, and the welding head includes a body, a head at an end of the body, and a plurality of movable welding knurls on a surface of the head.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2024-0120844, filed on September 5, 2024, with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The embodiments relate to an ultrasonic welding apparatus, a secondary battery, and a method for manufacturing a secondary battery. Background Technology

[0004] Unlike primary batteries, which are designed not to be (re)charged, secondary (or rechargeable) batteries are designed to be discharged and recharged. Low-capacity secondary batteries are used in portable small electronic devices such as smartphones, feature phones, laptops, digital cameras, and camcorders, while high-capacity secondary batteries are widely used as power sources for motors in hybrid and electric vehicles and for storing electricity (e.g., household and / or utility-scale power storage). A secondary battery typically includes an electrode assembly containing positive and negative electrodes, a housing of the electrode assembly, and electrode terminals connected to the electrode assembly.

[0005] The information disclosed in this section is provided only to enhance understanding of the background of this disclosure, and therefore may contain information that does not constitute related (prior) art. Summary of the Invention

[0006] According to some embodiments of this disclosure, an ultrasonic welding apparatus includes: an anvil configured to support the lower part of a welding target; and a welding horn disposed above the anvil and including a body, a head provided at one end of the body, and a plurality of movable welding knurlings provided on a surface of the head, wherein the plurality of movable welding knurlings are capable of rising or falling.

[0007] Welding knurling can be configured to have multiple rows or multiple columns, or welding knurling can be configured to have multiple rows and multiple columns.

[0008] Each of the plurality of movable weld knurlings includes threads or helical grooves on at least a portion of the outer surface of the movable weld knurling.

[0009] The head may include a helical groove corresponding to the thread of each of the plurality of movable weld knurlings or a thread corresponding to the helical groove of each of the plurality of movable weld knurlings.

[0010] Each of the plurality of movable welding knurls can be inserted into one of the plurality of horizontal holes in a state of being coupled to the head by rotating up or down.

[0011] Each of the plurality of movable welding knurls can include a protrusion protruding from an outer surface of the movable welding knurl.

[0012] The head can include a vertical hole and a plurality of horizontal holes into which the protrusions of the movable welding knurls are insertable.

[0013] The number of the horizontal holes can be odd.

[0014] The protrusion of each of the plurality of movable welding knurls can be inserted into one of the plurality of horizontal holes in a state of being coupled to the head.

[0015] In a base set state, the protrusion of each of the plurality of movable welding knurls can be inserted into a horizontal hole disposed at the middle among the plurality of horizontal holes.

[0016] In an up state, the protrusion of each of the plurality of movable welding knurls can be inserted into an uppermost horizontal hole among the plurality of horizontal holes.

[0017] In a down state, the protrusion of each of the plurality of movable welding knurls can be inserted into a lowermost horizontal hole among the plurality of horizontal holes.

[0018] According to some embodiments, a method of manufacturing a secondary battery includes forming an electrode assembly including a negative electrode substrate tab and a positive electrode substrate tab, and welding a pair of lead tabs to the negative electrode substrate tab and the positive electrode substrate tab by an ultrasonic welding device so that the pair of lead tabs are electrically connected to the negative electrode substrate tab and the positive electrode substrate tab, respectively.

[0019] According to some embodiments, a secondary battery includes an electrode assembly including a negative electrode plate provided with a plurality of negative electrode substrate tabs and a positive electrode plate provided with a plurality of positive electrode substrate tabs, a separator interposed between the positive electrode plate and the negative electrode plate, and a pair of lead tabs electrically connected to the negative electrode substrate tabs and the positive electrode substrate tabs, respectively, wherein the negative electrode substrate tabs and the positive electrode substrate tabs are welded to the lead tabs by an ultrasonic welding device according to embodiments of the present disclosure.

[0020] The plurality of negative electrode substrate tabs are welded to each other by the ultrasonic welding device according to embodiments of the present disclosure.

[0021] A plurality of negative electrode base material tabs are welded to each other by the ultrasonic welding device according to the embodiment of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0022] The following accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the description of the present disclosure, further serve to describe aspects and features of the present disclosure. Accordingly, the present disclosure should not be construed as being limited to the accompanying drawings.

[0023] Figure 1 A schematic view illustrating an exemplary ultrasonic welding device according to an embodiment;

[0024] Figure 2 A plan view illustrating a welding head according to an embodiment;

[0025] Figure 3 A side view illustrating a welding head according to an embodiment;

[0026] Figure 4 A schematic view illustrating a structure of a welding knurl according to an embodiment;

[0027] Figures 5 to 7 A schematic view illustrating a structure and an operating state of a welding knurl according to another embodiment;

[0028] Figure 8 And Figure 9 A schematic view illustrating a process of adjusting a height of a welding knurl in a row direction;

[0029] Figure 10 And Figure 11 A schematic view illustrating a process of adjusting a height of a welding knurl in a column direction;

[0030] Figure 12 And Figure 13 A photograph obtained by comparing results of adjusting a height of a welding knurl;

[0031] Figure 14 A perspective view illustrating an exemplary secondary battery manufactured by an ultrasonic welding device; and

[0032] Figure 15 A schematic view illustrating a welding portion of a secondary battery in Figure 14 DETAILED DESCRIPTION

[0033] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The terms or words used in the present specification and claims should not be interpreted as being limited to commonly used meanings or meanings in dictionaries and should be interpreted as having meanings and concepts consistent with the technical idea of the present disclosure based on the principle that the inventor can appropriately define the concept of terms to best explain his / her own invention.​

[0034] The embodiments described in this specification and the configurations shown in the drawings are only some of the embodiments of the present disclosure, and do not represent all technological ideas, aspects, and features of the present disclosure. Accordingly, it will be understood that, at the time of filing this application, there can be various equivalents and modifications that can replace or modify the embodiments described herein.

[0035] It will be further understood that, as used in this specification, the terms "comprises" and variations of the term "comprises", such as "comprising", "includes", "including", "contains", "containing", "consists of and variations of the term "consists of", such as "consisting of", mean "including, but not limited to", and are not intended to (and do not) exclude other moieties, elements, steps, integers, or groups thereof.

[0036] Also, the accompanying drawings are not drawn to scale in order to facilitate understanding of the present disclosure, and the sizes of some components can be exaggerated. Also, the same reference numerals are designated to the same components in different embodiments.

[0037] Referring to two compared elements, features, etc., as "the same" can mean that they are "substantially the same". Thus, the phrase "substantially the same" can include cases where there is a deviation considered to be low in the art (e.g., a deviation of 5% or less). Also, when a certain parameter is referred to as being uniform in a given region, this can mean that it is uniform in terms of average value.

[0038] It will be understood that, although the terms "first", "second", "third", and the like can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of example embodiments.

[0039] Throughout the specification, unless otherwise indicated, each element can be singular or plural.

[0040] Placing an arbitrary element "on (or under)" or "on (under)" another element can mean that the arbitrary element can be disposed in contact with the upper (or lower) surface of the element, and still another element can be interposed between the element and the arbitrary element disposed on (or under) the element.

[0041] Also, it will be understood that when a component is referred to as being "joined", "coupled", or "connected" to another component, that the element can be "joined", "coupled", or "connected" directly to the other component or a further component can be "interposed" between the components.

[0042] Throughout the specification, unless otherwise indicated, when stating "A and / or B", it means A, B, or A and B. That is, "and / or" includes any or all combinations of the items listed. When stating "C ~ D", it means C or more and D or less, unless otherwise indicated.

[0043] The terms used in the present specification are used to describe the factual meanings of the present disclosure and are not intended to limit the present disclosure.

[0044] Generally, an ultrasonic welding device can be used to weld base material tabs of a secondary battery to each other and to weld the base material tabs to lead tabs. The ultrasonic welding device is a device that places a welding target on an anvil, presses the welding target by a welding head whose welding knurl protrusion, and applies heat and pressure to the welding target by ultrasonic waves, thereby performing welding. Therefore, close contact with the welding target and uniform pressure transmission are important factors. Hereinafter, an ultrasonic welding device according to an embodiment will be described.

[0045] Figure 1 FIG. 1 illustrates a schematic diagram of an exemplary ultrasonic welding device according to an embodiment. Figure 2 FIG. 2 illustrates a plan view of a welding head according to an embodiment. Figure 3 FIG. 3 illustrates a side view of a welding head according to an embodiment. Figure 4 FIG. 4 illustrates a schematic diagram of a structure of a welding knurl according to an embodiment. Figures 5 to 7 FIG. 5 illustrates a schematic diagram of a structure and an operating state of a welding knurl according to another embodiment. Figure 8 Figure 9 FIG. 6 illustrates a schematic diagram of a process of adjusting the height of a welding knurl in a row direction. Figure 10 Figure 11 FIG. 7 illustrates a schematic diagram of a process of adjusting the height of a welding knurl in a column direction. Figure 12 Figure 13 FIG. 8 illustrates a photograph obtained by comparing the results of adjusting the height of a welding knurl.

[0046] Referring to Figure 1 , the exemplary ultrasonic welding device 1000 can include an ultrasonic controller 1100, a vibrator 1200, a booster 1300, a welding head 1400, and an anvil 1500.

[0047] ​​​The ultrasonic controller 1100 converts or generates ultrasonic waves of the frequency required for welding. The vibrator 1200, also known as a transducer, converts electrical energy into mechanical energy. The amplifier 1300 amplifies the amplitude of the ultrasonic waves. The welding head 1400 amplifies the amplitude of the ultrasonic waves a second time to transmit the amplified ultrasonic waves to the welding target. The anvil 1500 secures and supports the welding target. The welding target can be located between the welding head 1400 and the anvil 1500. The welding head 1400 can be positioned above the welding target, and the anvil 1500 can be positioned below the welding target. Any other suitable configuration of the welding head 1400 relative to the anvil 1500 and / or the ultrasonic controller 1100 is possible.

[0048] In the following text, reference will be made to Figures 2 to 4 The welding head 1400 according to the example embodiment is described in detail.

[0049] First, refer to Figures 2 to 4 The welding head 1400 may include a body 1410, a head 1420, a connector 1430, and multiple welding knurlings (which may also be referred to as movable welding knurlings) 1440.

[0050] The body 1410 may be generally cylindrical or polyhedral in shape. A head 1420 may be provided at one end (e.g., a first end) of the body 1410, and a connector 1430 may be provided at a second end of the body 1410. For example, the head 1420 and connector 1430 may be located at opposite ends of the body 1410 along its longitudinal direction. For example, connector 1430 may be provided inside the body 1410 and may not be exposed externally. The aforementioned enhancer 1300 may be coupled to connector 1430; for example, the second end of the body 1410 including connector 1430 may face enhancer 1300 and be connected to enhancer 1300. Figure 1 For example, the width of the second end of the body 1410 on the connector 1430 side (e.g., based on...). Figure 3 The width (along the vertical direction) can be the largest in the body 1410, while the width of the first end of the body 1410 at the head 1420 side can be the smallest in the body 1410. During the ultrasonic welding process, the body 1410 can vibrate in the longitudinal direction of the body 1410 (e.g., along the vertical direction). Figure 1 (The direction of the double-headed arrow in the image).

[0051] The head 1420 may have a polyhedral shape, wherein portions of the top and bottom surfaces of the polyhedral shape are flat when viewed from above. For example, see reference... Figure 1The bottom surface of the head 1420 may be flat and may be positioned facing the anvil 1500, and the top surface of the head 1420 may be opposite to the bottom surface of the head 1420. The head 1420 may be provided integrally with the body 1410 (e.g., as a monolithic and seamless structure) or may be provided separately.

[0052] Multiple weld knurling 1440s may be provided on one surface of the head 1420, for example, weld knurling 1440 may be provided on the bottom surface of the head 1420 facing the anvil 1500 (based on...). Figure 1 and Figure 3 The bottom surface of the head 1420 may be provided with holes into which each weld knurling 1440 can be inserted (e.g., the holes in the bottom surface of the head 1420 and the weld knurling 1440 can be arranged in a one-to-one correspondence).

[0053] The welding knurling 1440 may be referred to as a tip, protrusion, point, node, etc. The welding knurling 1440 can be arranged in at least one of multiple rows and multiple columns. The welding knurling 1440 can be formed in multiple rows and multiple columns on the bottom surface of the head 1420. For example, the welding knurling 1440 of this disclosure can be provided as (e.g., arranged as) 2 rows and N columns. The number of rows, number of columns, and arrangement of the welding knurling 1440 can vary depending on the size of the welding target. The welding knurling 1440 can have a cross-sectional shape such as circular or square. In some embodiments, the welding knurling 1440 can have a circular, elliptical, or square cross-sectional shape. For convenience, the accompanying drawings show an example of a welding knurling 1440 with an elliptical cross-sectional shape.

[0054] The comparative knurling can have a raised, protruding shape on the plate. Therefore, depending on the flatness of the welding target, only a portion of the comparative knurling may wear off, allowing the unworn welding knurling to be cut to match the height of the remaining knurling outside the worn area for reuse. However, since all unworn welding knurling needs to be cut, this can increase process time. Furthermore, if wear persists, the plate itself with the comparative knurling may need to be replaced, thus increasing process costs.

[0055] In contrast, according to the embodiment, a structure is provided that allows for adjustment of the height of the welding knurling without cutting. That is, according to the embodiment, a plurality of welding knurlings 1440 can be provided, and each welding knurling 1440 can have a structure that can rise or fall. For example, each welding knurling 1440 can be independently moved up and down in a direction perpendicular to the bottom surface of the head 1420 (e.g., the normal direction).

[0056] See Figure 4Each weld knurling 1440 may have a thread 1422 or a helical groove 1442 on at least a portion of its outer surface. Correspondingly, the head 1420 of the weld head 1400 may have a helical groove 1442 or a thread 1422 within the hole into which the weld knurling 1440 is to be inserted (e.g., the helical groove 1442 and the thread 1422 may have complementary shapes that mate with each other). In some embodiments, a helical groove or thread may be provided for a separate plate coupled to the head 1420. If the thread is provided on the outer surface of the weld knurling 1440, a helical groove may be provided inside the head 1420. Thus, the weld knurling 1440 and the head 1420 may be threadedly connected to each other via threads and helical grooves, similar to the connection of a bolt and nut. The weld knurling 1440 may be configured to rise or fall by rotation when coupled to the head 1420. For example, an operator can rotate (e.g., manually) the welding knurling 1440 itself to allow it to move up or down in the direction of the arrow. In another example, a separate tool T can be used to rotate the welding knurling 1440 to allow it to move up and down in the direction of the arrow. For this purpose, a groove for inserting the tool T can be provided at the upper end of the welding knurling 1440 (e.g., the tool T can be operated manually or automatically via a computing device, a controller with sensors, a processor including software, etc.).

[0057] refer to Figures 5 to 7 According to other embodiments, the welding knurling 1440a can rise or fall in a structure similar to a vehicle gearshift lever. For example, the head 1420a of the welding head 1400 may include a height adjustment hole 1422a on one side of the head 1420a. The number of height adjustment holes 1422a may be the same as the number of welding knurling 1440a; for example, each height adjustment hole 1422a may correspond to one welding knurling 1440a. Based on Figure 5 The height adjustment hole 1422a may include a vertical hole (e.g., the vertical hole may extend in a direction oriented from the bottom surface to the top surface of the head 1420a) and a plurality of horizontal holes (e.g., the plurality of horizontal holes may intersect the vertical hole and be perpendicular to the vertical hole). For example, the number of horizontal holes may be odd. The plurality of horizontal holes may be arranged at regular intervals along the length direction of the vertical hole (e.g., spaced apart from each other). For example, the weld knurling 1440a may include a protrusion 1442a projecting from one side of the outer surface.

[0058] For example, see Figure 5The basic setting state of the weld knurling 1440a can be a state in which the protrusion 1442a is inserted (e.g., insertable) into the horizontal hole defined in the middle of the height adjustment hole 1422a. Therefore, the weld knurling 1440a can be maintained in the basic setting state. See, for example, [link to relevant documentation]. Figure 6 The lowered state of the weld knurling 1440a can be the state in which the protrusion 1442a is inserted into the horizontal hole (e.g., the horizontal hole closest to the bottom surface of the head 1420a) defined at the lowest position of the height adjustment hole 1422a. Therefore, the weld knurling 1440a can be maintained in the lowered state. See, for example, [link to relevant documentation]. Figure 7 The raised state of the welding knurling 1440a can be such that the protrusion 1442a is inserted into the horizontal hole (e.g., the horizontal hole furthest from the bottom surface of the head 1420a) that is defined at the uppermost position of the height adjustment hole 1422a. Therefore, the welding knurling 1440a can remain in the raised state. The raised or lowered position of the welding knurling 1440a (i.e., the height of the welding knurling relative to the welding target) can be adjusted according to the length of the vertical hole and the number of horizontal holes.

[0059] The positioning of the welding knurling can be adjusted as follows (in some embodiments, the rows and columns of the welding knurling are based on...). Figure 2 ).

[0060] refer to Figure 8 Depending on the flatness of the welding target (e.g., the base material tabs (118, 138) and the lead tabs 500), some rows of the welding knurling may contact the welding target, and some rows may not. For example, in a weld head 1400 having a first row of welding knurling 1440b and a second row of welding knurling 1440c, the first row of welding knurling 1440b may contact the welding target, and the second row of welding knurling 1440c may not contact the welding target. In some embodiments, such as Figure 9 As shown in the diagram, the entire first row of welding knurling 1440b can be raised (e.g., moved or movable away from the welding target) and can be adjusted to the same position as the second row of welding knurling 1440c (e.g., so that the tips of the first row of welding knurling 1440b face the welding target, and the tips of the second row of welding knurling 1440c face the welding target at the same height relative to the welding target or anvil 1500).

[0061] refer to Figure 10 Some columns 1440g of the weld knurling may be completely worn. Unworn columns 1440d, 1440e, and 1440f of the weld knurling can contact the welding target. However, for the worn column 1440g of the weld knurling, the weld knurling may not contact the welding target. In some embodiments, such as Figure 11As shown in the diagram, multiple rows 1440d, 1440e, and 1440f of unworn weld knurling can rise to the same position as row 1440g of worn weld knurling.

[0062] See Figure 12 The comparative example illustrates a situation where one row of weld knurling in two rows does not properly contact the weld target. In some embodiments, it can be as follows: Figure 9 The diagram illustrates adjusting the height of the entire first row of weld knurling. In some embodiments, both rows of weld knurling can make uniform contact with the welding target. Therefore, the weld shape appears to have a uniform shape and size.

[0063] refer to Figure 13 The comparative example illustrates a state where some rows of weld knurling in a multi-row weld knurling pattern do not properly contact the weld target. In some embodiments, it can be as follows: Figure 11 The diagram illustrates adjusting the height of the entire series of weld knurling. In some embodiments, all multiple columns of weld knurling can make uniform contact with the welding target. Therefore, the weld shape appears to have a uniform shape and size.

[0064] In the following, a secondary battery manufactured by the ultrasonic welding apparatus according to the above embodiment will be described in detail with reference to the accompanying drawings.

[0065] Figure 14 The illustration shows a perspective view of an exemplary secondary battery manufactured using an ultrasonic welding apparatus. Figure 15 Illustration Figure 14 A schematic diagram of the welding part of the secondary battery.

[0066] refer to Figure 14 and Figure 15 The exemplary secondary battery 10 may be a pouch-type battery. However, embodiments of this disclosure may include all types of secondary batteries to which ultrasonic welding is performed. The exemplary secondary battery 10 may include an electrode assembly 100, a housing 300, and a pair of lead terminals 500.

[0067] The electrode assembly 100 can be provided by winding or stacking a negative electrode plate, a diaphragm, and a positive electrode plate, wherein the negative electrode plate, the diaphragm, and the positive electrode plate are provided in a thin film shape. The electrode assembly 100 can be housed together with the electrolyte in a housing 300.

[0068] The negative electrode plate may include a negative electrode current collector (the negative electrode current collector being a metal foil) and a negative electrode active material layer applied to the negative electrode current collector. The negative electrode plate may further include a negative electrode uncoated portion to which the negative electrode active material is not applied. The negative electrode current collector may be provided as a metal foil, such as copper, copper alloy, nickel, or nickel alloy. The negative electrode uncoated portion may be cut into a specific shape to become the negative electrode substrate material tab 118. A plurality of negative electrode substrate material tabs 118 may be provided. The lead tab 500 may be electrically connected to the negative electrode substrate material tab 118. For example, the negative electrode substrate material tabs 118 may be first aggregated and welded together, and then welded to the lead tab 500. In some embodiments, the above ultrasonic welding device 1000 may be used for welding between the negative electrode substrate material tabs 118 and for welding between the negative electrode substrate material tab 118 and the lead tab 500.

[0069] The negative electrode active material may include a material capable of reversibly inserting / extracting lithium ions, lithium metal, a lithium metal alloy, a material capable of doping and undoping lithium, or a transition metal oxide.

[0070] The material capable of reversibly inserting / extracting lithium ions may be a carbon-based negative electrode active material, which may include, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of crystalline carbon may include graphite such as natural graphite or artificial graphite, and examples of amorphous carbon may include soft carbon, hard carbon, pitch carbide, mesophase pitch carbide, sintered coke, etc.

[0071] The Si-based negative electrode active material or the Sn-based negative electrode active material may be used as the material capable of doping and undoping lithium. The Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiOx (0 < x ≤ 2, for example, SiO2), a Si-based alloy, or a combination thereof.

[0072] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles.

[0073] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core containing crystalline carbon and silicon particles and an amorphous carbon coating on the surface of the core.

[0074] The negative electrode for a lithium secondary battery may include a substrate and a negative electrode active material layer provided on the substrate. The negative electrode active material layer may include a negative electrode active material and may further include a binder and / or a conductive material.

[0075] For example, the negative electrode active material layer may include about 90 wt% to about 99 wt% of negative electrode active material, about 0.5 wt% to about 5 wt% of binder, and about 0 wt% to about 5 wt% of conductive material.

[0076] Non-aqueous binders, aqueous binders, dry binders, or combinations thereof can be used as binders. When an aqueous binder is used as a negative electrode binder, it may further include cellulose compounds capable of imparting viscosity.

[0077] As the negative electrode substrate, one can be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with conductive metal, and combinations thereof.

[0078] Electrolytes used in lithium secondary batteries may include non-aqueous organic solvents and lithium salts.

[0079] Non-aqueous organic solvents act as a medium through which ions participating in the electrochemical reactions of the battery can move.

[0080] Non-aqueous organic solvents can be carbonate-based solvents, ester-based solvents, ether-based solvents, ketone-based solvents, alcohol-based solvents, or aprotic solvents, and can be used alone or in combination of two or more.

[0081] In addition, when using carbonate-based solvents, a mixture of cyclic carbonates and chain carbonates can be used.

[0082] Depending on the type of lithium-ion secondary battery, a separator may be present between the first electrode plate (e.g., the negative electrode) and the second electrode plate (e.g., the positive electrode). Polyethylene, polypropylene, polyvinylidene fluoride, or multilayer films comprising two or more layers thereof can be used as the separator.

[0083] The positive electrode plate may include a positive electrode current collector (which is a metal foil) and a layer of positive electrode active material applied to the positive electrode current collector. The positive electrode plate may further include an uncoated portion of the positive electrode to which the positive electrode active material is not applied. The negative electrode current collector is provided as a metal foil, such as aluminum or an aluminum alloy. The uncoated portion of the positive electrode may be cut into a specific shape to become a positive electrode substrate material connector 138. Multiple positive electrode connectors 138 may be provided. Lead connectors 500 may be electrically connected to the positive electrode connectors 138. For example, the positive electrode substrate material connectors 138 may be assembled and welded together first, and then welded to the lead connectors 500. In some embodiments, the ultrasonic welding apparatus 1000 described above may be used for welding between positive electrode substrate material connectors 138 and for welding between positive electrode substrate material connectors 138 and lead connectors 500.

[0084] Simultaneously, as a positive electrode active material, compounds capable of reversibly inserting / deintercalating lithium (e.g., lithiation intercalation compounds) can be used. For example, at least one of lithium and a composite oxide of a metal selected from cobalt, manganese, nickel, and combinations thereof can be used.

[0085] The composite oxide can be a lithium transition metal composite oxide, and examples of it can include lithium nickel-based oxides, lithium cobalt-based oxides, lithium manganese-based oxides, lithium iron phosphate-based compounds, cobalt-free nickel manganese-based oxides, or combinations thereof.

[0086] As an example, a compound represented by any of the following formulas can be used: Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni b Co c L 1 d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, O≤e≤0.1); Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Lia Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3 (0≤f≤2); Li a FePO4 (0.90≤a≤1.8).

[0087] In the formulas in this paper: A is Ni, Co, Mn or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or a combination thereof; D is O, F, S, P or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof; and L1 is Mn, Al or a combination thereof.

[0088] The positive electrode for a lithium secondary battery may include a current collector and a layer of positive electrode active material formed on the current collector. The positive electrode active material layer may include a positive electrode active material and may further include a binder and / or a conductive material.

[0089] Based on a 100wt% positive electrode active material layer, the content of the positive electrode active material is in the range of about 90wt% to about 99wt%, and based on the 100wt% positive electrode active material layer, the contents of the binder and the conductive material are in the range of about 0.5wt% to about 5wt%, respectively.

[0090] The current collector can be aluminum (Al) foil, but is not limited to this.

[0091] A diaphragm can be inserted between the negative electrode plate and the positive electrode plate to prevent short circuits between them and to enable the movement of lithium ions.

[0092] The diaphragm may include a porous substrate and a coating on one or both surfaces of the porous substrate, comprising organic materials, inorganic materials, or combinations thereof.

[0093] Organic materials may include polyvinylidene fluoride polymers or (meth)acrylic acid polymers.

[0094] Inorganic materials may include, but are not limited to, inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite and combinations thereof.

[0095] Organic and inorganic materials can be mixed in a single coating, or they can be layered together as a mixture of organic and inorganic materials.

[0096] The electrolyte solution of a rechargeable lithium battery may include non-aqueous organic solvents and lithium salts.

[0097] Non-aqueous organic solvents can serve as media for transporting ions that participate in the electrochemical reactions of a battery. These non-aqueous organic solvents can be carbonates, esters, ethers, ketones, alcohols, aprotic solvents, or combinations thereof, and can be used alone or in combination of two or more.

[0098] In addition, when using carbonate solvents, cyclic carbonates and chain carbonates can be used in combination.

[0099] The housing 300 defines the appearance of the secondary battery 10 and houses the electrode assembly 100. The housing 300 may be in the form of a bag having a receiving space defined in one surface of the housing 300 to accommodate the electrode assembly 100. The housing 300 may be referred to as a laminated housing, a housing, a bag housing, a pouch shell, etc. The housing 300 may include a recess 310 and a sealing portion 330. For example, the housing 300 may be bent to face a plate-like housing, and then one surface of the housing 300 may be compressed or stretched to provide the recess 310. The sealing portion 330 may be provided around the open side of the recess 310. With the electrode assembly 100 housed in the recess 310, the sealing portion 330 may be sealed by heat sealing or the like. In some embodiments, with the insulating portion 510, described later, disposed between the sealing portions 330, a portion of the lead tab 500 may be exposed to the outside of the housing 300.

[0100] The lead-connector 500 can be ultrasonically welded to the negative electrode substrate material connector 118 and the positive electrode substrate material connector 138. An insulating portion 510 can be provided on the lead-connector 500. The insulating portion 510 can be made of an insulating material, such as insulating tape. The lead-connector 500 can be insulated from the housing 300 by the insulating portion 510. For example, the insulating portion 510 can be placed on the sealing portion 330 of the housing 300. In some embodiments, the width of the insulating portion 510 can be equal to or greater than the width of the sealing portion 330.

[0101] See Figure 15Since the secondary battery 10 is welded using the ultrasonic welding apparatus 1000 of this disclosure, the welding areas of the substrate material connector 118 and the lead connector 500 can be welded by uniformly applying pressure, thereby improving welding strength and quality. That is, according to embodiments of this disclosure, the height of the welding knurling 1440 in the welding head 1400 of the ultrasonic welding apparatus 1000 can be adjusted according to the degree of wear of the welding knurling 1440 at the end of the welding head. Therefore, the welding target can be contacted and compressed with uniform pressure during welding, thereby improving welding quality. In some embodiments, even if the degree of wear of the welding knurling varies according to differences in the flatness of the welded portion, uniform welding pressure can be ensured.

[0102] The method for manufacturing a secondary battery according to this disclosure may include: forming an electrode assembly including a negative electrode substrate material terminal block and a positive electrode substrate material terminal block; and welding a pair of lead terminals to the negative electrode substrate material terminal block and the positive electrode substrate material terminal block using the ultrasonic welding apparatus of this disclosure, such that the pair of lead terminals are electrically connected to the negative electrode substrate material terminal block and the positive electrode substrate material terminal block, respectively.

[0103] By summarizing and reviewing, some embodiments of this disclosure provide an ultrasonic welding apparatus capable of adjusting the height of the welding knurling at the end of the welding head without cutting. That is, the ultrasonic welding apparatus according to embodiments includes a welding head with movable welding knurling that can be independently adjusted to provide a uniform weld.

[0104] The aspects and features of this disclosure are not limited to those described above, and those skilled in the art will clearly understand other aspects and features not specifically mentioned from the above description of this disclosure.

[0105] This document has disclosed exemplary embodiments. Although specific terminology has been used, it is used in a general, descriptive sense only and should be interpreted in a general, descriptive sense only, and is not intended to be limiting. In some instances, as would be apparent to those skilled in the art at the time of filing this application, unless otherwise specifically stated, features, characteristics, and / or elements described in connection with particular embodiments may be used alone or in combination with features, characteristics, and / or elements described in connection with other embodiments. Therefore, those skilled in the art will understand that various changes in form and detail may be made without departing from the spirit and scope of the invention.

Claims

1. An ultrasonic welding device comprising: an anvil configured to support a lower portion of a welding target; and a horn above the anvil, the welding target between the horn and the anvil, and the horn including a main body, a head at an end of the main body, and a plurality of movable welding knurls on a surface of the head.

2. The ultrasonic welding device of claim 1, wherein, The plurality of movable welding knurls are arranged in at least one of a plurality of rows and a plurality of columns.

3. The ultrasonic welding device of claim 2, wherein, Each of the plurality of movable welding knurls includes a thread or a helical groove on at least a portion of an outer surface of the movable welding knurl.

4. The ultrasonic welding device of claim 3, wherein, The head includes a helical groove corresponding to the thread of each of the plurality of movable welding knurls or a thread corresponding to the helical groove of each of the plurality of movable welding knurls.

5. The ultrasonic welding device of claim 4, wherein, Each of the plurality of movable welding knurls is configured to be raised or lowered by rotation in a state of being coupled to the head.

6. The ultrasonic welding device of any one of claims 2 to 5, wherein, Each of the plurality of movable welding knurls includes a protrusion protruding from an outer surface of the movable welding knurl. 7.The ultrasonic welding device of claim 6, wherein: the head includes a vertical hole corresponding to each of the plurality of movable welding knurls, and a plurality of horizontal holes intersecting the vertical hole, and the protrusion of each of the plurality of movable welding knurls is insertable into a corresponding horizontal hole.

8. The ultrasonic welding device of claim 7, wherein, A number of the plurality of horizontal holes intersecting the vertical hole is odd.

9. The ultrasonic welding device of claim 8, wherein, The protrusion of each of the plurality of movable welding knurls is insertable into one of the plurality of horizontal holes in a state of being coupled to the head.

10. The ultrasonic welding device of claim 9, wherein, In a base set state, the protrusion of each of the plurality of movable welding knurls is insertable into a middle one of the plurality of horizontal holes.

11. The ultrasonic welding device of claim 9, wherein, In a raised state, the protrusion of each of the plurality of movable welding knurls is insertable into an uppermost one of the plurality of horizontal holes.

12. The ultrasonic welding device of claim 9, wherein, In a lowered state, the protrusion of each of the plurality of movable welding knurls is insertable into a lowermost one of the plurality of horizontal holes. 13.A method of manufacturing a secondary battery, the method comprising: forming an electrode assembly including a negative electrode base material tab and a positive electrode base material tab; and welding a pair of lead tabs to the negative electrode base material tab and the positive electrode base material tab by the ultrasonic welding device according to any one of claims 1 to 12, such that the pair of lead tabs are electrically connected to the negative electrode base material tab and the positive electrode base material tab, respectively. 14.A secondary battery comprising: an electrode assembly including a negative electrode base material tab and a positive electrode base material tab; and A pair of lead tabs are electrically connected to the negative electrode base material tab and the positive electrode base material tab, respectively, which are welded to the lead tabs by the ultrasonic welding device according to any one of claims 1 to 12.

15. The secondary battery according to claim 14, wherein The negative electrode base material tabs are welded to each other by the ultrasonic welding device.

16. The secondary battery according to claim 14 or 15, wherein The negative electrode base material tabs are welded to each other by the ultrasonic welding device.

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