Welding device, method for manufacturing secondary battery, and secondary battery

Abstract

The invention relates to a welding apparatus, a method of manufacturing a secondary battery, and a secondary battery. The welding apparatus for manufacturing a secondary battery includes: an electrode tab welding tool configured to weld a plurality of electrode tabs formed on an electrode plate of an electrode assembly to form an electrode tab welding portion; and a bar conductor welding tool configured to weld a bar conductor to the welded electrode tab to form a bar conductor welded portion. The bar conductor is configured to be electrically connected to an external terminal, and the bar conductor welding tool and the electrode tab welding tool are configured to form a bar conductor welding portion and an electrode tab welding portion in a region that does not overlap each other.

Description

Technical Field

[0001] Embodiments of this disclosure relate to a welding apparatus for manufacturing secondary batteries, a method for manufacturing secondary batteries, and secondary batteries themselves. Background Technology

[0002] Batteries can be classified into non-rechargeable (or primary) batteries and rechargeable (or secondary) batteries. Low-capacity batteries are used in small portable electronic devices (such as smartphones, feature phones, laptops, digital cameras, and camcorders), while high-capacity batteries are widely used as power sources for driving motors in hybrid electric vehicles, electric vehicles, and other vehicles, as well as for energy storage. Secondary batteries typically include electrode assemblies containing positive and negative electrodes (or composed of positive and negative electrodes), external components (such as a casing or canister) housing the electrode assemblies, and external terminals electrically connected to the electrode assemblies.

[0003] Electrode assemblies and external terminals can be electrically connected by welding electrode tabs and strip conductors formed on the electrode assembly. Multiple electrode tabs can be formed on the electrode assembly, in which case the multiple electrode tabs can be welded together, and the strip conductors can be welded to the welded electrode tabs. Ultrasonic welding can be used to weld the electrode tabs and weld the electrode tabs and strip conductors.

[0004] In this welding method, the electrode contact welding portion and the strip conductor welding portion may overlap, resulting in double welding. Due to this overlap, problems such as electrode plate cracking, reduced or insufficient weld strength may occur.

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

[0006] The embodiments disclosed herein aim to provide a welding method for preventing double welding between the electrode contact welding portion and the strip conductor welding portion.

[0007] According to embodiments of this disclosure, a welding apparatus for manufacturing secondary batteries includes: an electrode tab welding tool configured to weld a plurality of electrode tabs formed on an electrode plate of an electrode assembly to form an electrode tab weld portion; and a strip conductor welding tool configured to weld a strip conductor, configured to be electrically connected to an external terminal, to the welded electrode tabs to form a strip conductor weld portion. The strip conductor welding tool and the electrode tab welding tool are configured to form the strip conductor weld portion and the electrode tab weld portion in areas that do not overlap with each other.

[0008] According to another embodiment of this disclosure, a method of manufacturing a secondary battery includes: welding a plurality of electrode tabs formed on an electrode plate of an electrode assembly to form electrode tab weld portions; and welding a strip conductor to the welded electrode tabs to form strip conductor weld portions, the strip conductor being configured for electrical connection to an external terminal. The electrode tab weld portions formed on the electrode tabs and the strip conductor weld portions formed on the strip conductors exist in areas that do not overlap with each other.

[0009] According to another embodiment of this disclosure, a secondary battery includes: an electrode assembly including a plurality of electrode tabs welded together at electrode tab welding portions; and a strip conductor welded to the electrode tabs at strip conductor welding portions, the strip conductor being configured for electrical connection to an external terminal. The strip conductor welding portions and the electrode tab welding portions are formed in areas that do not overlap with each other.

[0010] The aspects and features of this disclosure are not limited to those described above, and those skilled in the art will clearly understand from the following description of the disclosure other aspects and features not specifically mentioned herein. Attached Figure Description

[0011] The following accompanying drawings illustrate embodiments of the present disclosure and further describe aspects and features of the disclosure together with the detailed description thereof. Therefore, the present disclosure should not be construed as limited to the drawings, in which:

[0012] Figure 1 and Figure 2 An illustration of the electrode assembly of a secondary battery;

[0013] Figure 3 A pouch-type secondary battery is illustrated schematically.

[0014] Figure 4 This is a detailed view of the welded portions of the electrode tabs and the welded portions of the strip conductors of an electrode assembly according to some embodiments of the present disclosure;

[0015] Figure 5 The electrode tab welding portions according to some embodiments of the present disclosure are shown;

[0016] Figure 6 Examples can be used as welding tools to form, such as Figure 5 The ultrasonic welding horn for the electrode connection welding section shown;

[0017] Figure 7 The strip conductor is shown by using Figure 6 The welding tools shown are used to weld to, for example Figure 5 The state of the electrode terminals with the electrode terminal welding portion shown;

[0018] Figure 8A and Figure 8B Examples can be used as welding tools to form [symbols]. Figure 7 An ultrasonic welding head for welding strip conductors in the form shown.

[0019] Figure 9 The electrode tab welding portions according to some other embodiments of the present disclosure are shown;

[0020] Figure 10 Examples used to form Figure 9 The ultrasonic welding head for the electrode connection welding part shown;

[0021] Figure 11 This shows the state in which a strip conductor is welded to an electrode terminal forming an electrode terminal welding portion;

[0022] Figure 12 Examples used to form Figure 11 The ultrasonic welding head for the welded section of the strip conductor shown;

[0023] Figure 13 This is a view of the electrode terminals of a secondary battery manufactured using an ultrasonic welding apparatus for manufacturing secondary batteries.

[0024] Figure 14 This is another view of the electrode terminal section of a secondary battery manufactured using an ultrasonic welding apparatus for manufacturing secondary batteries.

[0025] Figures 15A to 15C This is a view depicting conventional electrode contact welding and strip conductor welding; and

[0026] Figure 16 A prismatic secondary battery is illustrated schematically. Detailed Implementation

[0027] In the following, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The terms or words used in this specification and claims should not be interpreted narrowly according to their general or dictionary meaning, but rather should be interpreted as having meanings and concepts consistent with the technical spirit of the present disclosure, based on the principle that the inventor is capable of being his / her own lexicographer to appropriately define the concepts of the terms and best describe his / her invention.

[0028] The embodiments described in this specification and the configurations shown in the accompanying drawings are merely some embodiments of this disclosure and do not represent all aspects, features, and embodiments of this disclosure. Accordingly, it should be understood that various equivalents and modifications that can replace or modify one or more embodiments or features described herein may exist at the time of filing this application.

[0029] It will be understood that if an element or layer is referred to as being "on" another element or layer, "connected to," or "linked to" another element or layer, then it can be directly on, directly connected to, or linked to the other element or layer, or one or more intermediary elements or layers may exist. When an element or layer is referred to as being "directly on" another element or layer, "directly connected to," or "directly linked to" another element or layer, no intermediary element or layer exists. For example, if a first element is described as being "linked" or "connected" to a second element, then the first element can be directly linked to or connected to the second element, or the first element can be indirectly linked to or connected to the second element via one or more intermediary elements.

[0030] In the figures, the dimensions of various elements, layers, etc., may be exaggerated for clarity of illustration. The same reference numerals indicate the same elements. As used herein, the term “and / or” includes any one and all combinations of one or more of the associated listed items. Furthermore, if the word “may” is used to describe embodiments of this disclosure, it refers to “one or more embodiments of this disclosure.” Expressions such as “at least one of…” and “any one of…” modify the entire list of elements if they follow a list of elements, not individual elements in that list. When phrases such as “at least one of A, B, and C,” “at least one of A, B, or C,” “at least one selected from the group of A, B, and C,” or “at least one selected from A, B, and C” are used to indicate a list of elements A, B, and C, the phrase may refer to any one of A, B, and C and all suitable combinations or subsets, such as A, B, C, A and B, A and C, B and C, or A and B and C. As used herein, the term “use” may be considered synonymous with the term “utilize.” As used herein, the terms “substantially,” “about,” and similar terms are used as approximations and not as terms of degree, and are intended to take into account the inherent variations in the measured or calculated values ​​that would be recognized by one of ordinary skill in the art.

[0031] It will be understood that although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or segment from another element, component, region, layer, or segment. Therefore, without departing from the teachings of the exemplary embodiments, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment.

[0032] For ease of description, spatial relative terms (such as "below," "below," "down," "above," "up," etc.) may be used herein to describe the relationship of one element or feature to another element or feature as shown in the figure. It will be understood that spatial relative terms are intended to cover different orientations of the device in use or operation other than the orientation depicted in the figure. For example, if the device in the figure is flipped, an element described as "below" or "below" other elements or features would then be oriented as "above" or "upon" other elements or features. Therefore, the term "below" can encompass both above and below orientations. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptors used herein should be interpreted accordingly.

[0033] The terminology used herein is for the purpose of describing embodiments of this disclosure and is not intended to limit this disclosure. As used herein, unless the context clearly indicates otherwise, the singular form “a” is intended to include the plural form as well. It will be further understood that the terms “comprising” and / or “including” as used in this specification specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0034] Furthermore, any numerical range disclosed and / or described herein is intended to include all subranges with the same numerical precision contained within the described range. For example, the range “1.0 to 10.0” is intended to include all subranges between (and including) the described minimum value of 1.0 and the described maximum value of 10.0, i.e., all subranges having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0 (e.g., such as 2.4 to 7.6). Any maximum numerical limit described herein is intended to include all lower numerical limits contained therein, and any minimum numerical limit described herein is intended to include all higher numerical limits contained therein. Accordingly, the applicant reserves the right to amend this specification, including the claims, to explicitly describe any subranges contained within the range explicitly described herein. All such ranges are intended to be inherently described in this specification such that modifications made to explicitly describe any such subranges will comply with the requirements of patent law.

[0035] Referring to two compared elements, features, etc., as “identical” can mean that they are “substantially identical.” Therefore, the phrase “substantially identical” can include cases with a deviation considered low in the art (e.g., about 5% or less). Additionally, if a parameter is said to be consistent in a given region, it can mean that it is consistent in terms of average value.

[0036] Throughout this specification, unless otherwise stated, each element may be singular or plural.

[0037] Placing any element "above (or below)" or "above (or below)" another element can mean that the arbitrary element can contact the upper (or lower) surface of the element, and that the other element can be located between the element and any element located above (or below) the element.

[0038] Additionally, it will be understood that if a component is referred to as “linked,” “connected,” or “attached” to another component, then these components can be directly “linked,” “attached,” or “attached” to each other, or another component can be “between” these components.

[0039] Throughout this specification, unless otherwise stated, the statement "A and / or B" means A, B, or A and B. That is, "and / or" includes any one or all combinations of the listed items. Unless otherwise stated, the statement "C to D" means C and below D.

[0040] The terminology used herein is for the purpose of describing embodiments of this disclosure and is not intended to limit this disclosure.

[0041] Figure 1 and Figure 2 The electrode assembly of a secondary battery is shown schematically. Figure 1 A wound electrode assembly is shown, and Figure 2 A stacked electrode assembly is shown.

[0042] The electrode assembly 10 can be formed by winding or stacking a first electrode plate 11, a diaphragm 12, and a second electrode plate 13, each formed as a thin plate or film. When the electrode assembly 10 is a wound stack, the winding axis can be parallel to the longitudinal direction of the housing. (Reference) Figure 2 The electrode assembly 10' can be stacked rather than as shown. Figure 1 The diagram shows a wound type. The shape or type of the electrode assembly is not limited in this disclosure. Alternatively, the electrode assembly can be a Z-stacked electrode assembly in which positive and negative electrode plates are inserted into both sides (e.g., opposite sides) of a diaphragm, and the diaphragm is then bent (or folded) into a Z-stack. Additionally, one or more electrode assemblies can be stacked (e.g., arranged) such that the long sides of the electrode assemblies are adjacent to each other and housed in a housing, and the number of electrode assemblies in the housing is not limited in this disclosure. The first electrode plate 11 of the electrode assembly can be used as a negative electrode, and the second electrode plate 13 can be used as a positive electrode. Of course, the reverse is also possible.

[0043] The first electrode plate 11 can be formed by coating (e.g., coating or depositing) a first electrode active material (such as graphite or carbon) onto a first electrode substrate formed of a metal foil (such as copper, copper alloy, nickel, or nickel alloy). The first electrode plate 11 may include a first electrode tab 14 (e.g., a first uncoated portion), which is an area where the first electrode active material is not coated. The first electrode tab 14 can be connected to an external first terminal. In some embodiments, when manufacturing the first electrode plate 11, the first electrode tab 14 can be formed by being pre-cut to protrude toward (or from) one side of the electrode assembly 10, or the first electrode tab 14 can protrude toward one side of the electrode assembly 10 more than (e.g., farther or beyond) the diaphragm 12 without being separately cut.

[0044] The second electrode plate 13 can be formed by coating (e.g., coating or depositing) a second electrode active material (such as a transition metal oxide) onto a second electrode substrate formed of a metal foil (such as aluminum or an aluminum alloy). The second electrode plate 13 may include a second electrode tab 15 (e.g., a second uncoated portion), which is an area where the second electrode active material is not coated. The second electrode tab 15 can be connected to an external second terminal. In some embodiments, when manufacturing the second electrode plate 13, the second electrode tab 15 can be formed by being pre-cut to protrude toward the other side (e.g., the opposite side) of the electrode assembly 10, or the second electrode plate 13 can protrude toward the other side of the electrode assembly more than (e.g., farther or beyond) the diaphragm 12 without being separately cut.

[0045] The diaphragm 12 prevents short circuits between the first electrode plate 11 and the second electrode plate 13 while allowing lithium ions to move between them. The diaphragm 12 can be made of, for example, a polyethylene membrane, a polypropylene membrane, or a polyethylene-polypropylene membrane.

[0046] In some embodiments, the electrode assembly 10 may be housed within a housing along with the electrolyte. In a pouch-type secondary battery, the electrode assembly 10 may be housed within a pouch made of a flexible material (e.g., see...). Figure 3 In cylindrical or prismatic secondary batteries, the electrode assembly 10 can be housed in a cylindrical or prismatic metal casing (e.g., Figure 16 )middle.

[0047] Suitable materials that can be used in secondary batteries according to embodiments of this disclosure will be described below.

[0048] As the 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.

[0049] The composite oxide can be a lithium transition metal composite oxide, examples of which may 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.

[0050] As an example, a compound represented by any of the following molecular 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, 0≤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); Li a Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn1-g G g PO4 (0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5); Li (3-f) Fe2(PO4)3 (0 ≤ f ≤ 2); and Li a FePO4 (0.90 ≤ a ≤ 1.8).

[0051] In the above chemical formulas: A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, 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 L 1 is Mn, Al, or a combination thereof.

[0052] The positive electrode for a lithium secondary battery may include a substrate and a positive electrode active material layer formed on the substrate. The positive electrode active material layer may include a positive electrode active material and may further include a binder and / or a conductive material.

[0053] Based on 100 wt% of the positive electrode active material layer, the content of the positive electrode active material is in the range of about 90 wt% to about 99 wt%, and based on 100 wt% of the positive electrode active material layer, the contents of the binder and the conductive material are each in the range of about 0.5 wt% to about 5 wt%.

[0054] The substrate may be aluminum (Al), but is not limited thereto.

[0055] The negative electrode active material may include a material capable of reversibly inserting / extracting lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0056] 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.

[0057] A Si-based negative electrode active material or a Sn-based negative electrode active material may be used as the material capable of doping and dedoping lithium. The Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiO x (0 < x ≤ 2), a Si-based alloy, or a combination thereof.

[0058] 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.

[0059] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core comprising crystalline carbon and silicon particles, and an amorphous carbon coating on the surface of the core.

[0060] The negative electrode for a lithium secondary battery may include a substrate and a negative electrode active material layer disposed 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.

[0061] 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.

[0062] Non-aqueous adhesives, aqueous adhesives, dry adhesives, or combinations thereof can be used as adhesives. When an aqueous adhesive is used as a negative electrode adhesive, it may further include a cellulose compound capable of imparting viscosity.

[0063] 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.

[0064] Electrolytes used in lithium secondary batteries may include non-aqueous organic solvents and lithium salts.

[0065] Non-aqueous organic solvents act as a medium through which ions participating in the electrochemical reactions of the battery can move.

[0066] Non-aqueous organic solvents can be carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, and aprotic solvents, and can be used alone or in combination of two or more.

[0067] In addition, when using carbonate solvents, a mixture of cyclic carbonates and chain carbonates can be used.

[0068] Depending on the type of lithium-ion secondary battery, a separator can be present between the first electrode plate (e.g., the negative electrode) and the second electrode plate (e.g., the positive electrode). As the separator, polyethylene, polypropylene, polyvinylidene fluoride, or multilayer films comprising two or more layers thereof can be used.

[0069] 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.

[0070] Organic materials may include polyvinylidene fluoride polymers or (meth)acrylic acid polymers.

[0071] 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.

[0072] Organic and inorganic materials can be mixed in a coating, or they can be in the form of coatings that include (or contain) organic materials and coatings that include (or contain) inorganic materials stacked on top of each other.

[0073] Figure 3 A pouch-type secondary battery according to some embodiments of the present disclosure is illustrated schematically.

[0074] According to this embodiment, the pouch-type secondary battery may include an electrode assembly 10 and a pouch 20 for housing the electrode assembly 10.

[0075] like Figure 1 and Figure 2 The first electrode tab 14 and the second electrode tab 15 of the electrode assembly 10 shown can be electrically connected by being respectively bonded to a first strip conductor 16 and a second strip conductor 17 exposed to the outside of the bag 20 and serving as terminals. A tab film 18 made of polypropylene (PP) material to insulate from the bag 20 can be attached to the first strip conductor 16 and the second strip conductor 17. The first electrode tab 14 and the first strip conductor 16, and the second electrode tab 15 and the second strip conductor 17 can be bonded using ultrasonic welding.

[0076] Since the electrical connection between the electrode plates of the electrode assembly and the exposed terminals is a fundamental configuration of a secondary battery, the welding of the electrode terminals and strip conductors (or current collectors) of the electrode assembly is not only applied to... Figure 3 The illustrated pouch-type secondary battery. For example, the welding configuration described above can also be applied to... Figure 16 The prism-shaped secondary battery shown.

[0077] Figure 4 This is a detailed view of the welded portions of the electrode tabs 14 or 15 and the welded portions of the strip conductors 16 or 17 of the electrode assembly 10 according to some embodiments of the present disclosure.

[0078] Figure 4 The portion of the electrode assembly 10 shown has multiple electrode tabs 14 and 15 (so-called multi-tap structure). Figure 4 The area shown can be included Figure 1 The wound electrode assembly 10 shown and Figure 2 The stacked electrode assembly 10' shown.

[0079] As shown, the welding part is mainly divided into two parts, namely, the electrode connecting piece welding part 22 and the strip conductor welding part 24. At the electrode connecting piece welding part 22, multiple electrode connecting pieces 14 are welded, and at the strip conductor welding part 24, the strip conductor 16 is welded to the welded electrode connecting pieces 14.

[0080] The electrode tab welding portion 22 and the strip conductor welding portion 24 are formed in areas that do not overlap with each other. For example, the electrode tab welding portion 22 is formed outside the area occupied by the strip conductor 16, and the strip conductor welding portion 24 is formed in the area inside (or above) the strip conductor 16.

[0081] although Figure 4 The electrode tab welding portion 22 and the strip conductor welding portion 24 are shown to have different welding marks (such as the shape of the welding portion), but this is only for easy distinction between the two welding portions. In reality, the shapes of the welding portions (e.g., welding marks) can be the same, similar or completely different.

[0082] The electrode terminal welding portion 22 and the strip conductor welding portion 24 can be formed by using an ultrasonic welding tool with a welding head, in which a welding nozzle with a shape corresponding to these welding portions is formed.

[0083] To describe embodiments of this disclosure in comparison with conventional welding methods, reference will be made to... Figures 15A to 15C This describes conventional electrode patch welding (referred to as pre-welding) and strip conductor welding (referred to as main welding). In the conventional ultrasonic pre-welding process, methods such as... Figure 15A The pre-welding head 51 shown has a welding nozzle 52 for welding the entire surface of the electrode terminals, and uses, as shown in the figure Figure 15B The diagram shows a main welding head 53 with a welding nozzle 54 for welding strip conductors, used for main welding of the strip conductors after pre-welding. According to this welding method, when the strip conductor 58 is main welded after the pre-welded electrode terminals 56, as... Figure 15C As shown, the strip conductor welding portion 54' overlaps with the electrode tab welding portion 52' to form a double weld (e.g., to form an overlapping weld area). Additionally, when the welding nozzle of the main welding head extends beyond (or extends beyond) the strip conductor area during the main welding process, a double weld may be formed in the electrode tab area (e.g., 55a or 55b) where the strip conductor is not present. Due to this overlap and double welding, welding quality problems such as a high probability of cracks in the welded portion, weld pinholes, and reduced weld strength occur. Furthermore, the number of welding strokes may increase due to the steps at the side edge portions caused by the thickness of the strip conductor 58, thereby increasing wear on the welding head and shortening its lifespan.

[0084] To avoid this overlap between the pre-welding area and the main welding area, embodiments of this disclosure aim at an electrode tab-strip conductor welding method and a welding tool for the method. According to the electrode tab-strip conductor welding method according to embodiments of this disclosure, the pre-welding portion (i.e., the electrode tab welding portion 22 (e.g., see...)...) Figure 4 )) and the main welded portion (i.e., the strip conductor welded portion 24 (for example, see Figure 4 Separate welding is performed. For this purpose, the electrode bonding tool can be an ultrasonic welding head designed (or configured) to weld areas other than the strip conductor area, and the strip conductor welding tool can be an ultrasonic welding head designed (or configured) to weld only the strip conductor area.

[0085] Figure 5 Electrode tab welding portions 22 are shown according to some embodiments of the present disclosure. Welding is performed on electrode tabs 14 formed on a plurality of electrode plates to form electrode tab welding portions 22a and 22b. Electrode tab welding portions 22a and 22b may be formed at locations that do not overlap with (e.g., offset from) the region 30 where the strip conductor 16 will later be welded. Figure 5 In this embodiment, electrode bonding portions 22a and 22b are formed in some regions outside the bonding portion of the strip conductor 16 where it will be bonded, i.e., in the regions outside the two ends (e.g., opposite ends) of the strip conductor 16 in the width direction, but this disclosure is not limited thereto.

[0086] Figure 6 Examples can be used as welding tools to form [symbols]. Figure 5 The ultrasonic welding head 26 for forming the electrode tab welding portion 22 is shown in the form of an ultrasonic welding head 26. The welding head 26 for forming the electrode tab welding portion has a position relative to... Figure 5 The electrode tab welding portions 22a and 22b shown are located in the corresponding regions of the welding nozzles 28a and 28b. Furthermore, since there is an empty space 31 between the first set of welding nozzles 28a and the second set of welding nozzles 28b, corresponding to the region 30 where the strip conductor welding portion will later be formed, the strip conductor welding portion 24 and the electrode tab welding portions 22a and 22b will not overlap each other later.

[0087] Figure 7 The strip conductor 16 is shown using... Figure 6 The welding tools shown are used to weld to, for example Figure 5The diagram shows the state of the electrode piece 14 with electrode tab weld portions 22a and 22b. A strip conductor weld portion 24, formed by welding, exists in the width direction of the strip conductor 16. As described above, the strip conductor weld portion 24 does not overlap with the electrode tab weld portions 22a and 22b. Therefore, since there are no problems due to double welding and the strip conductor 16 can be welded to the blank surface of the electrode piece 14 (e.g., a surface without any weld portions), good weld strength can be ensured.

[0088] refer to Figure 7 For ease of distinction, the shapes of the welding marks on the strip conductor welding portion 24 and the welding marks on the electrode terminal welding portions 22a and 22b are shown differently, but in practice, they can be similar or the same.

[0089] Figure 8A The examples according to the embodiments can be used for forming having Figure 7 The ultrasonic welding head 32 of the welding tool for the welding portion 24 of the strip conductor, as shown in the diagram (or configuration). In the welding head 32 used to form the strip conductor welding portion, a welding nozzle 34 is formed in conjunction with... Figure 7 The location corresponding to the strip conductor welding section 24 shown.

[0090] The solder nozzle 34 for forming the welding portion 24 of the strip conductor can be formed in an area smaller than the width of the strip conductor 16 (e.g., it can have an area smaller than the width of the strip conductor 16). Therefore, double welding with the electrode tab welding portions 22a and 22b can be prevented. In one embodiment, the solder nozzle 34 can be formed in an area ranging from about 70% to about 90% of the width of the strip conductor 16 (e.g., it can be formed to cover this area).

[0091] Empty weld avoidance portions 36a and 36b are located on both sides of the weld nozzle 34 forming the strip conductor weld portion 24 to prevent weld overlap at positions corresponding to the previously formed electrode tab weld portions 22a and 22b. In this way, double welding is prevented by avoiding overlap between the pre-welded area (e.g., electrode tab weld portion 22) and the main welded area (e.g., strip conductor weld portion 24), thereby avoiding weld quality problems such as weld pinholes and reduced weld strength due to the appearance of cracks.

[0092] Figure 8B An ultrasonic welding head 32' for welding a strip conductor is illustrated according to another embodiment. The welding head 32' itself may be manufactured (or may be formed) to be smaller than the outer boundary of the strip conductor 16. In the illustrated embodiment, only the welding nozzle 34 is formed, and no other features such as... Figure 8AThe welding avoidance portions 36a and 36b are shown. In this way, by manufacturing a strip conductor welding head 32' smaller than the area of ​​the strip conductor 16, wear on the strip conductor welding head caused by the step of the strip conductor 16 being higher than the surface of the electrode terminal block 14 due to the thickness of the strip conductor 16 can be prevented or reduced, thereby extending the service life (e.g., lifespan) of the welding head.

[0093] Figure 9 Electrode tab welding portions 22a to 22d are shown according to some other embodiments of this disclosure. Figure 5 Unlike the illustrated embodiment, the electrode tab welding portions 22a, 22b, 22c, and 22d close around the region 38 where the strip conductor 16 is later welded (e.g., extending around the entire periphery of region 38 or completely around the periphery of region 38). However, this disclosure is not limited thereto. For example, in other embodiments, the electrode tab welding portions do not close around the region 38 where the strip conductor 16 is welded, but may instead surround the region 38 (e.g., may extend around a portion of the periphery of region 38), such that a portion of it (e.g., regions 22c or 22d) is open (e.g., not welded). Figure 9 In the illustrated embodiment, the area of ​​the electrode tab welding portion 22 can be enlarged, thereby increasing the bonding strength of the electrode tab 14.

[0094] Figure 10 Examples can be used as welding tools to form [symbols]. Figure 9 The ultrasonic welding heads 40 shown are for electrode tab welding portions 22a, 22b, 22c, and 22d. The welding heads 40 used to form the electrode tab welding portions have [features / features] that [are used in conjunction with / with / etc.]. Figure 9 The electrode tabs 42a, 42b, 42c, and 42d are formed in the form of closed circuits (e.g., in the shape of closed loops) in the regions corresponding to the electrode tab welding portions 22a, 22b, 22c, and 22d shown. Since the inner sides of the tabs 42a, 42b, 42c, and 42d form empty spaces 44 corresponding to the region 38 where the strip conductor welding portion will be formed later, the strip conductor welding portion 24 and the electrode tab welding portions 22a, 22b, 22c, and 22d do not overlap each other.

[0095] Figure 11 The strip conductor 16 is shown using... Figure 10 The welding tool shown is welded to, as Figure 9 The electrode contacts 14 shown are in the state of having electrode contact welding portions 22a, 22b, 22c, and 22d. (Refer to...) Figure 11The strip conductor weld portion 24, formed by welding, exists in the width direction of the strip conductor 16. As described above, the strip conductor weld portion 24 does not overlap with the electrode terminal weld portions 22a, 22b, 22c, and 22d.

[0096] Figure 12 The examples according to the embodiments can be used for forming having Figure 11 The ultrasonic welding head 46 of the welding tool for forming the strip conductor weld portion 24 in the form (or configuration) shown. In the welding head 46 used to form the strip conductor weld portion, a welding nozzle 48 is formed in conjunction with... Figure 11 The solder nozzle 48 is located at the position corresponding to the strip conductor welding portion 24 shown. It can be formed in an area smaller than the width of the strip conductor 16 (e.g., it can have an area smaller than the width of the strip conductor 16). Therefore, double welding with the electrode tab welding portions 22a, 22b, 22c, and 22d can be prevented. In one embodiment, the solder nozzle 48 can be formed in an area of ​​approximately 70% to approximately 90% of the width of the strip conductor 16 (e.g., it can be formed in this area).

[0097] The empty welding avoidance portion 50 is located near the welding nozzle 48 to prevent welding overlap at positions corresponding to the previously formed electrode terminal welding portions 22a, 22b, 22c and 22d.

[0098] In another embodiment, the strip conductor welding head can be formed as follows: Figure 8B The welding head 32' is shown.

[0099] Figure 13 An example of a secondary battery manufactured using the aforementioned ultrasonic welding apparatus for manufacturing secondary batteries is shown. Figure 13 The above reference shows Figure 5 The electrode terminal portion of the secondary battery manufactured by the welding apparatus of the embodiment described in FIG8.

[0100] Electrode tab weld portions 22a and 22b, formed by welding multiple electrical tabs 14 formed on multiple electrode plates of the electrode assembly, exist on the electrode tabs 14, and a strip conductor 16 configured to be electrically connected to an external terminal is welded to the electrode tabs 14. A strip conductor weld portion 24, formed by welding the electrode tabs 14, exists on the strip conductor 16. The strip conductor weld portion 24 and the electrode tab weld portions 22a and 22b are formed in areas that do not overlap with each other (e.g., offset relative to each other).

[0101] In one embodiment, the strip conductor weld portion 24 may exist in an area smaller than the width of the strip conductor 16 (e.g., it may have an area smaller than the width of the strip conductor 16). For example, the strip conductor weld portion 24 may exist in an area ranging from about 70% to about 90% of the width of the strip conductor 16.

[0102] Electrode tab welding portions 22a and 22b may exist outside the strip conductor welding portion 24 (e.g., strip conductor 16 on...). Figure 13 In some areas (outside the boundary of the edge portion on both sides in the width direction).

[0103] Figure 14 This is shown by referring to the above reference. Figures 10 to 12 The electrode terminals of a secondary battery manufactured by the welding apparatus described in the embodiment.

[0104] and Figure 13 Compared to the illustrated embodiment, the electrode tab welding portions 22a, 22b, 22c, and 22d formed on the electrode tab 14 have enlarged areas (e.g., covering a larger area) and are formed to surround the periphery of the strip conductor welding portion 24 (e.g., extending around the periphery of the strip conductor welding portion 24). Figure 13 In the illustrated embodiment, the strip conductor welding portion 24 and the electrode terminal welding portions 22a, 22b, 22c and 22d are formed in areas that do not overlap with each other (e.g., are offset relative to each other) to prevent double welding.

[0105] For example, the strip conductor weld portion 24 may be present in an area smaller than the width of the strip conductor 16. In one embodiment, the strip conductor weld portion 24 may be present in an area ranging from about 70% to about 90% of the width of the strip conductor 16.

[0106] In addition, such as Figure 14 As shown, electrode tab welding portions 22a, 22b, 22c, and 22d may exist in a region that closes around the strip conductor welding portion 24 (e.g., extends around the entire periphery of the strip conductor welding portion 24). In another embodiment, electrode tab welding portions 22a, 22b, 22c, and 22d may exist in a region that partially surrounds the strip conductor welding portion 24 (e.g., extends around a portion of the periphery of the strip conductor welding portion 24) and has some openings.

[0107] Hereinafter, a method for manufacturing a secondary battery according to some embodiments of the present disclosure will be described. The following description of the method will be primarily based on the electrode tab-strip conductor welding process performed by the welding apparatus described in the above embodiments.

[0108] A method for manufacturing a secondary battery according to some embodiments of the present disclosure includes: providing an electrode assembly including a plurality of electrode plates having electrode tabs formed thereon; welding a plurality of electrode tabs formed on the electrode plates of the electrode assembly to form an electrode tab welded portion; and welding the welded electrode tabs to a strip conductor configured for electrical connection to an external terminal to form a strip conductor welded portion.

[0109] According to embodiments of the present disclosure, the electrode terminal welding portion formed on the electrode terminal and the strip conductor welding portion formed on the strip conductor exist in areas that do not overlap with each other.

[0110] In some embodiments, the electrode contact welding portion and the strip conductor welding portion can be formed by ultrasonic welding.

[0111] In some embodiments, the strip conductor weld portion may be formed in an area smaller than the width of the strip conductor, and in one embodiment, the strip conductor weld portion may be formed in an area ranging from about 70% to about 90% of the width of the strip conductor.

[0112] In some embodiments, electrode tab welding portions may be formed in some regions outside the strip conductor welding portion. In some other embodiments, electrode tab welding portions may be formed in regions that close around the strip conductor welding portion (e.g., extending around the entire periphery of the strip conductor welding portion), and in some other embodiments, electrode tab welding portions may be formed in regions that partially surround the strip conductor welding portion (e.g., extending around a portion of the periphery of the strip conductor welding portion).

[0113] The ultrasonic welding apparatus and method for manufacturing secondary batteries according to the above embodiments of this disclosure can also be applied to applications other than... Figure 3 Electrode assemblies used in other types of secondary batteries besides pouch cells (e.g., prismatic secondary batteries).

[0114] Figure 16 A prismatic secondary battery is schematically shown.

[0115] Electrode assembly 210 can be formed by winding or stacking a first electrode plate, a diaphragm, and a second electrode plate into a thin sheet or film. When electrode assembly 210 is a wound stack, the winding axis can be parallel to the longitudinal direction of housing 200. In some other embodiments, electrode assembly 210 can be a stack type instead of a wound type, but the shape of electrode assembly 210 is not limited in this disclosure. Alternatively, electrode assembly 210 can be a Z-stacked electrode assembly in which positive and negative electrode plates are inserted into both sides (e.g., opposite sides) of a diaphragm, and then the diaphragm is bent into a Z-stack. Additionally, one or more electrode assemblies can be stacked such that the long sides of the electrode assemblies are adjacent to each other and housed in a housing, and the number of electrode assemblies in the housing is not limited in this disclosure. The first electrode plate of the electrode assembly can be used as a negative electrode, and the second electrode plate can be used as a positive electrode. Of course, the reverse is also possible.

[0116] The first electrode plate can be formed by coating a first electrode active material (such as graphite, carbon, etc.) onto a first electrode current collector formed of a metal foil (such as copper, copper alloy, nickel, nickel alloy, etc.). The first electrode plate may include a first electrode tab 212 (e.g., a first uncoated portion), which is an area where the first electrode active material is not coated. The first electrode tab 212 can serve as a current flow path between the first electrode plate and the first current collector 130. In some embodiments, when manufacturing the first electrode plate, the first electrode tab 212 is formed by being pre-cut to protrude toward one side of the electrode assembly 210, or the first electrode tab 212 protrudes toward one side of the electrode assembly 210 more than (e.g., farther or beyond) the diaphragm without being separately cut.

[0117] The second electrode plate can be formed by coating a second electrode active material (such as a transition metal oxide) onto a second electrode current collector formed of a metal foil (such as aluminum or an aluminum alloy). The second electrode plate may include a second electrode tab 214 (e.g., a second uncoated portion), which is an area where the second electrode active material is not coated. The second electrode tab 214 can serve as a current flow path between the second electrode plate and the second current collector 140. In some embodiments, when manufacturing the second electrode plate, the second electrode tab 214 can be formed by being pre-cut to protrude to the other side (e.g., the opposite side) of the electrode assembly, or the second electrode plate can protrude to the other side of the electrode assembly more than (e.g., further or beyond) the diaphragm without being separately cut.

[0118] The separator prevents or significantly reduces short circuits between the first and second electrodes while allowing lithium ions to move between them. The separator can be made of, for example, polyethylene membranes, polypropylene membranes, or polyethylene-polypropylene membranes.

[0119] In some embodiments, the electrode assembly 210 is housed together with the electrolyte in the housing 200.

[0120] In electrode assembly 210, first electrode tabs 212 and second electrode tabs 214, protruding from the first electrode plate and the second electrode plate, can be connected to the first current collector 130 and the second current collector 140, respectively. In some embodiments where the first electrode tabs 212 and 214 are located at both ends of electrode assembly 210, the first current collector and the second current collector are positioned across both ends and the upper portion of electrode assembly 210.

[0121] The first current collector 130 and the second current collector 140 can be electrically connected to the first terminal 150, the second terminal 160, and the conductive bosses 170 and 180, respectively.

[0122] As mentioned above, Figure 16 The secondary battery shown is a secondary battery with a top-mounted terminal block structure. In this structure, the electrode assembly 210 is arranged such that the first electrode terminal block 212 and the second electrode terminal block 214 are located at the upper portion of the electrode assembly 210. Furthermore, since the first terminal 150 and the second terminal 160 are located at the upper portion of the housing 200, this is referred to as a top-mounted substructure. For example, the first electrode terminal block 212 and the second electrode terminal block 214 of the electrode assembly 210 are located at the upper portion within the housing 200, and the first current collector 130 and the second current collector 140 are respectively connected to the first electrode terminal block 212 and the second electrode terminal block 214, and the first terminal 150 and the second terminal 160, respectively connected to the first current collector 130 and the second current collector 140, are mounted on the outside of the cover plate 110 (e.g., protruding to the outside of the cover plate 110).

[0123] According to this disclosure, double welding is prevented by avoiding overlapping areas between the pre-welded area (e.g., electrode tab welding portion) and the main welding area (e.g., strip conductor welding portion), thereby avoiding welding quality problems such as welding pinholes and reduced welding strength due to the appearance of cracks.

[0124] In addition, since the strip conductor can be soldered to the blank surface of the electrode terminals (e.g., areas without any soldering), good solder strength is ensured, and wear on the strip conductor solder head caused by the thickness step of the strip conductor being higher than the surface of the electrode terminals is reduced, thereby extending the service life (e.g., lifespan) of the solder head.

[0125] Although the present disclosure has been described above with reference to embodiments thereof, the present disclosure is not limited thereto. Various modifications and variations can be made by those skilled in the art within the spirit of the present disclosure as defined by the appended claims and their equivalents.

Claims

1. A welding apparatus for manufacturing secondary batteries, the welding apparatus comprising: An electrode bonding tool is configured to bond multiple electrode bonding pieces formed on the electrode plate of an electrode assembly to form a welded portion of the electrode bonding piece. as well as A strip conductor welding tool is configured to weld a strip conductor to the welded electrode tab to form a strip conductor welded portion, the strip conductor being configured for electrical connection to external terminals. The strip conductor welding tool and the electrode connector welding tool are configured to form the strip conductor welding portion and the electrode connector welding portion in areas that do not overlap with each other.

2. The welding apparatus according to claim 1, wherein the electrode bonding plate welding tool comprises a welding head having a welding nozzle for ultrasonically welding the plurality of electrode bonding plates, and The strip conductor welding tool includes a welding head having a welding nozzle for ultrasonically welding the strip conductor to the welded electrode tab.

3. The welding apparatus of claim 1, wherein the strip conductor welding tool is configured such that the welded portion of the strip conductor is formed in a region smaller than the width of the strip conductor.

4. The welding apparatus of claim 3, wherein the strip conductor welding tool is configured such that the welded portion of the strip conductor is formed in a region within a range of 70% to 90% of the width of the strip conductor.

5. The welding apparatus according to any one of claims 1 to 4, wherein the electrode tab welding tool is configured such that the electrode tab welding portion is formed in a region outside the strip conductor welding portion.

6. The welding apparatus according to any one of claims 1 to 4, wherein the electrode tab welding tool is configured such that the electrode tab welding portion is formed in a region extending completely around the periphery of the strip conductor welding portion.

7. The welding apparatus according to any one of claims 1 to 4, wherein the electrode tab welding tool is configured such that the electrode tab welding portion is formed in a region extending partially around the periphery of the strip conductor welding portion.

8. A method for manufacturing a secondary battery, the method comprising: Multiple electrode terminals are welded onto the electrode plate of the electrode assembly to form the electrode terminal welded portion; as well as A strip conductor configured to be electrically connected to an external terminal is soldered to the soldered electrode tab to form a strip conductor solder section. The electrode terminal weld portion formed on the electrode terminal and the strip conductor weld portion formed on the strip conductor exist in areas that do not overlap with each other.

9. The method according to claim 8, wherein the electrode terminal welding portion and the strip conductor welding portion are formed by ultrasonic welding.

10. The method of claim 8, wherein the strip conductor weld portion is formed in a region smaller than the width of the strip conductor.

11. The method of claim 10, wherein the strip conductor weld portion is formed in a region within a range of 70% to 90% of the width of the strip conductor.

12. The method according to any one of claims 8 to 11, wherein the electrode tab welding portion is formed in the region outside the strip conductor welding portion.

13. The method according to any one of claims 8 to 11, wherein the electrode tab welding portion is formed in a region extending around the entire periphery of the strip conductor welding portion.

14. The method according to any one of claims 8 to 11, wherein the electrode tab welding portion is formed in a region that extends partially around the periphery of the strip conductor welding portion.

15. A secondary battery, comprising: An electrode assembly, comprising multiple electrode terminals welded together at an electrode terminal welding section; as well as A strip conductor, welded to the electrode tab at its welded portion, is configured for electrical connection to external terminals. The strip conductor welding portion and the electrode terminal welding portion are formed in areas that do not overlap with each other.

16. The secondary battery of claim 15, wherein the strip conductor welded portion exists in a region smaller than the width of the strip conductor.

17. The secondary battery according to claim 16, wherein the welded portion of the strip conductor exists in a region ranging from 70% to 90% of the width of the strip conductor.

18. The secondary battery according to any one of claims 15 to 17, wherein the electrode terminal welding portion is located in the region outside the strip conductor welding portion.

19. The secondary battery according to any one of claims 15 to 17, wherein the electrode terminal weld portion exists in a region extending completely around the periphery of the strip conductor weld portion.

20. The secondary battery according to any one of claims 15 to 17, wherein the electrode tab weld portion exists in a region extending partially around the periphery of the strip conductor weld portion.

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