Secondary battery and method for manufacturing secondary battery

Abstract

The embodiment of the invention provides a secondary battery and a manufacturing method of the secondary battery. The secondary battery includes: an electrode assembly including an electrode tab; a collector plate which includes at least one opening and is in contact with one surface of the electrode tab; and a welding portion formed along at least a portion of a boundary where the electrode tab and the collector plate are in contact within the opening portion, the welding portion joining a portion of one surface of the electrode tab exposed through the opening portion and the collector plate.

Description

Technical Field

[0001] The present disclosure relates to a secondary battery and a method for manufacturing the secondary battery. Background Art

[0002] Secondary batteries are batteries that can be repeatedly charged and discharged. With the development of information communication and display industries, secondary batteries are widely used as power sources for portable electronic communication devices such as cameras, mobile phones, and notebook computers. In addition, in recent years, battery modules or battery packs including secondary batteries are being developed and applied as power sources for environmentally friendly cars.

[0003] The secondary battery may include an electrode assembly and an electrolyte impregnated with the electrode assembly, wherein the electrode assembly includes a positive electrode, a negative electrode, and a separator. The secondary battery may further include an outer packaging material that accommodates the electrode assembly and the electrolyte.

[0004] For example, the electrode assembly may be manufactured in a jelly roll form by winding or folding a separator, or may be manufactured in a stacked form by stacking separators.

[0005] The collector plate can be connected between the uncoated uncoated portion of the electrode (e.g., the electrode tab) and the terminal to transfer current. For example, the collector plate can have a bent shape and be bonded to the uncoated portion, or a flat plate-shaped collector plate can be bonded to the folded surface of the uncoated portion when the uncoated portion is folded. Compared with the bent shape, the flat plate-shaped collector plate occupies a smaller volume, so the energy density per unit volume of the secondary battery can be increased.

[0006] In recent years, research on a welding structure capable of improving welding efficiency and reliability between a current collector plate and an uncoated portion has been conducted. Summary of the invention

[0007] 1. Technical issues to be resolved

[0008] According to one aspect of the present disclosure, a secondary battery having improved electrical characteristics and stability and a method of manufacturing the secondary battery are provided.

[0009] (II) Technical solution

[0010] According to the present disclosure, a secondary battery includes: an electrode assembly, including an electrode tab; a collector plate, including at least one opening portion and in contact with one side of the electrode tab; a welding portion formed in the opening portion along at least a portion of the boundary where the electrode tab contacts the collector plate, the welding portion joining a portion of the one side of the electrode tab exposed through the opening portion and the collector plate.

[0011] In some embodiments, the opening may penetrate one side and the other side of the collector plate.

[0012] In some embodiments, the welding portion may not penetrate the collector plate.

[0013] In some embodiments, the welding portion may cover at least one side surface of the collector plate exposed through the opening portion, and may be partially inserted into the interior of the electrode tab.

[0014] In some embodiments, the electrode tab may include: a first engaging portion protruding from the electrode assembly; a second engaging portion extending in a direction opposite to the first engaging portion; and a bent portion disposed between the first engaging portion and the second engaging portion.

[0015] In some embodiments, the first engaging portion and the second engaging portion may face each other through the bent portion.

[0016] In some embodiments, one surface of the collector plate may be in contact with the first joint portion, and the other surface of the collector plate may be in contact with the second joint portion.

[0017] In some embodiments, the electrode assembly may include a plurality of electrodes repeatedly stacked and a separator interposed between the plurality of electrodes, and each of the plurality of electrodes may include a non-coating portion.

[0018] In some embodiments, the electrode tab may be formed by bending the uncoated portion protruding from one side of the electrode assembly in one direction.

[0019] In some embodiments, the electrode assembly may include: a plurality of positive electrodes, each of the plurality of positive electrodes including a positive electrode uncoated portion; and a plurality of negative electrodes, each of the plurality of negative electrodes including a negative electrode uncoated portion, the positive electrode uncoated portion may protrude from one side of the electrode assembly, and the negative electrode uncoated portion may protrude from another side of the electrode assembly.

[0020] In some embodiments, the electrode tab may include a positive electrode tab formed by bending the positive electrode uncoated portion together and a negative electrode tab formed by bending the negative electrode uncoated portion together.

[0021] In some embodiments, the secondary battery may further include: a housing to accommodate the electrode assembly; a cap plate to close the housing; and an electrode terminal mounted on the cap plate and electrically connected to the electrode tab.

[0022] In the manufacturing method of a secondary battery according to the present disclosure, a preliminary electrode assembly is prepared, and an uncoated portion protrudes to the outside of the electrode assembly. The uncoated portion is bent in one direction to form an electrode tab. A collector plate including at least one opening is arranged on the electrode tab so that one side of the collector plate overlaps with one side of the electrode tab. The electrode tab and the collector plate are welded through the opening along at least one side of the opening. The end of the electrode tab protruding to the outside of the collector plate can be bent so that the end overlaps with the other side of the collector plate.

[0023] In some embodiments, laser may be irradiated along a boundary between the electrode tab and the collector plate exposed through the opening to weld the electrode tab and the collector plate.

[0024] In some embodiments, the end portion of the electrode tab protruding to the outside of the collector plate may be bent in a direction opposite to a direction in which the uncoated portion is bent.

[0025] (III) Beneficial effects

[0026] According to an embodiment of the present disclosure, a secondary battery may include: an electrode assembly including an electrode tab; and a collector plate including at least one opening and connected to the electrode tab. The secondary battery may include a welding portion that joins the collector plate and the electrode tab through the opening. The welding portion may be formed along a portion of the electrode tab exposed through the opening and a side surface of the opening.

[0027] Therefore, a welded structure can be formed even under low energy and low temperature conditions, and the generation of foreign matter and cracks can be suppressed. Even if the thickness of the collector plate increases, high welding reliability can be ensured, and the resistance of the secondary battery can be reduced. In addition, the stress applied to the weld can be reduced, and the capacity and electrical characteristics can be improved.

[0028] The secondary battery disclosed herein can be widely used in electric vehicles, battery charging stations, and other green technology fields such as solar power generation and wind power generation using batteries. In addition, the secondary battery disclosed herein can be used in eco-friendly electric vehicles and hybrid vehicles that prevent climate change by suppressing air pollution and greenhouse gas emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is an exploded perspective view of a secondary battery according to an embodiment of the present disclosure.

[0030] Figure 2 is an exploded perspective view of an electrode assembly according to an embodiment of the present disclosure.

[0031] Figure 3 and Figure 4 They are perspective views for explaining a bonding process of a current collector plate and an electrode tab according to an exemplary embodiment.

[0032] Figure 5 is along Figure 4 A cross-sectional view of the secondary battery taken along line AA'.

[0033] Figure 6 is a perspective view for explaining a welding process of a current collector plate and an electrode tab according to an exemplary embodiment.

[0034] Figure 7 and Figure 8 Each of them is a cross-sectional view for explaining a process of forming a weld portion.

[0035] Fig. 9 and Fig.10 Each is a cross-sectional view for explaining a welding process according to a comparative example.

[0036] Fig.11 is a perspective view for explaining a secondary battery according to an exemplary embodiment.

[0037] Fig.12 is along Fig.11 A cross-sectional view of the secondary battery taken along line CC'. DETAILED DESCRIPTION

[0038] Hereinafter, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. However, the accompanying drawings are intended to illustrate preferred embodiments of the present invention, and together with the above-mentioned content of the invention, help to more deeply understand the technical concept of the present invention, and therefore, the present invention should not be interpreted as being limited to the contents shown in the accompanying drawings.

[0039] The terms "upper surface", "bottom surface", "upper part", "bottom", "lower surface", "lower part" etc. used in this specification are used in a relative sense to distinguish the positions of components and are not used to specify absolute positions.

[0040] The term "first direction" used in this specification may refer to the direction in which the electrode tab 120 is bent. The first direction may refer to the direction in which the electrodes are stacked in the electrode assembly 100. The first direction may refer to the width direction of the electrode assembly 100. The first direction may refer to Figure 1 and Figures 3 to 7 The first direction in .

[0041] The term “second direction” used in this specification may refer to a length direction of the electrode assembly 100. The second direction may refer to a direction from one side of the electrode assembly 100 toward the other side.

[0042] The term "third direction" used in this specification may refer to the height direction of the electrode assembly 100. Figure 1 and Figures 3 to 7 The third direction may represent a direction perpendicular to the first direction and the second direction.

[0043] Figure 1 is an exploded perspective view of a secondary battery according to an embodiment of the present disclosure.

[0044] Reference Figure 1 , the secondary battery may include an electrode assembly 100. The electrode assembly 100 may include an electrode tab 120. The electrode tab 120 may protrude from one side of the electrode assembly.

[0045] For example, the electrode assembly 100 may include a plurality of electrodes that are repeatedly stacked. The electrode assembly 100 may further include a separator 105 interposed between the plurality of electrodes.

[0046] Each of the plurality of electrodes may include an uncoated portion. For example, the uncoated portion may protrude from the electrode assembly 100. The uncoated portions may be assembled to form an electrode tab 120.

[0047] Figure 2 is an exploded perspective view of an electrode assembly according to an embodiment of the present disclosure.

[0048] Reference Figure 2 , the electrode assembly 100 may include a positive electrode 102, a negative electrode 104, and a separator 105 interposed between the positive electrode 102 and the negative electrode 104. The positive electrode 102, the separator 105, and the negative electrode 104 may be stacked in sequence.

[0049] According to an exemplary embodiment, positive electrodes 102 and negative electrodes 104 may be alternately and repeatedly stacked with separators 105 interposed therebetween to form the electrode assembly 100 .

[0050] Each of the positive electrode 102 and the negative electrode 104 may include a coating portion 112 and a non-coating portion 122 .

[0051] The coating portion 112 may include a current collector 110 and an active material layer 115 disposed on at least one side of the current collector 110. The uncoated portion 122 may be defined as a region of the current collector 110 where the active material layer 115 is not formed. The uncoated portion 122 may extend from the current collector 110 of the coating portion 112 and protrude from the coating portion 112.

[0052] In some embodiments, active material layers may be formed on both sides of the current collector.

[0053] The coating portion 112 may include a positive electrode coating portion 112a and a negative electrode coating portion 112b. The positive electrode coating portion 112a and the negative electrode coating portion 112b may overlap each other in a vertical direction. The term "vertical direction" used in this specification may refer to the direction of the electrode stack or the first direction. The separator 105 may be interposed between the positive electrode coating portion 112a and the negative electrode coating portion 112b.

[0054] The uncoated portion 122 may include a positive uncoated portion 122a and a negative uncoated portion 122b. According to an exemplary embodiment, the positive uncoated portion 122a and the negative uncoated portion 122b may protrude in opposite directions to each other. For example, the positive uncoated portion 122a may protrude from the positive coating portion 112a in one direction, and the negative uncoated portion 122b may protrude from the negative coating portion 112b in a direction opposite to the one direction.

[0055] The positive electrode 102 may include a positive electrode current collector and a positive electrode active material layer.

[0056] The positive electrode active material layer may include a positive electrode active material. The positive electrode active material may include a compound capable of reversibly inserting and releasing lithium ions.

[0057] In an exemplary embodiment, the positive electrode active material may include lithium metal oxide particles. For example, the lithium metal oxide particles may include nickel (Ni) and may further include at least one of cobalt (Co), manganese (Mn), and aluminum (Al).

[0058] In some embodiments, the lithium metal oxide particles may include lithium nickel cobalt manganese-based (LNCM) oxide, lithium nickel manganese-based (LNM) oxide, lithium nickel aluminum-based (LNA) oxide, and the like.

[0059] For example, the positive electrode current collector may include stainless steel, nickel, aluminum, titanium, copper, zinc or an alloy thereof. In one embodiment, the positive electrode current collector may include aluminum or an aluminum alloy.

[0060] For example, the positive electrode active material may be mixed and stirred with a binder, a conductive agent and / or a dispersant in a solvent to prepare a slurry. The slurry may be coated on a positive electrode collector, compressed and dried to manufacture the positive electrode 102 including a positive electrode active material layer.

[0061] The binder may include an organic binder such as polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethylmethacrylate, or a water-based binder such as styrene-butadiene rubber (SBR), and may be used together with a thickener such as carboxymethyl cellulose (CMC). For example, as a binder for the positive electrode, a PVDF-based binder may be used.

[0062] The conductive material may be included to facilitate electron movement between active material particles. For example, the conductive material may include a carbon-based conductive material such as graphite, carbon black, graphene, carbon nanotubes, etc. and / or include tin, tin oxide, titanium oxide, such as LaSrCoO 3 、LaSrMnO 3 Metal-based conductive materials such as perovskite substances.

[0063] The negative electrode 104 may include a negative electrode current collector and a negative electrode active material layer.

[0064] The negative electrode active material layer may include a negative electrode active material. The negative electrode active material may include, for example, a carbon-based material such as crystalline carbon, amorphous carbon, carbon composite, carbon fiber, etc.; a lithium alloy; a silicon (Si)-based active material, etc.

[0065] Examples of the amorphous carbon may include hard carbon, coke, mesocarbon microbeads (MCMB), mesophase pitch-based carbon fibers (MPCF), etc. Examples of the crystalline carbon may include graphite-based carbon such as natural graphite, artificial graphite, graphitized coke, graphitized MCMB, and graphitized MPCF. The elements contained in the lithium alloy may include aluminum, zinc, bismuth, cadmium, antimony, silicon, lead, tin, gallium, or indium, etc.

[0066] The negative electrode current collector may include stainless steel, copper, nickel, aluminum, titanium or an alloy thereof. In one embodiment, the negative electrode current collector may include copper or a copper alloy.

[0067] For example, the negative electrode active material may be mixed and stirred with the above-mentioned binder, conductive agent, thickener, etc. in a solvent to prepare a slurry. The slurry may be coated on at least one side of a negative electrode collector, compressed and dried to manufacture the negative electrode 104 including the negative electrode active material layer.

[0068] As the binder and the conductive agent, a material substantially the same as or similar to the above-mentioned material used in the positive electrode active material layer can be used. In some embodiments, for compatibility with the carbon-based active material, the binder used to form the negative electrode may include a water-based binder such as styrene-butadiene rubber (SBR), and may be used together with a thickener such as carboxymethyl cellulose (CMC).

[0069] The separator 105 may include a porous polymer film made of polyolefin-based polymers such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer. The separator 105 may also include a non-woven fabric formed of high-melting-point glass fiber, polyethylene terephthalate fiber, etc.

[0070] Refer again Figure 1 The electrode tabs 120 may include a positive electrode tab 120 a protruding from the positive electrode and a negative electrode tab 120 b protruding from the negative electrode.

[0071] For example, the positive electrode uncoated portions may be gathered to form a positive electrode tab 120 a , and the negative electrode uncoated portions may be gathered to form a negative electrode tab 120 b .

[0072] The positive electrode tab 120a and the negative electrode tab 120b may protrude from both sides of the electrode assembly 100. For example, the positive electrode tab 120a may protrude from one side of the electrode assembly 100 in the second direction, and the negative electrode tab 120b may protrude from the other side of the electrode assembly 100 in the second direction.

[0073] The secondary battery may include a case 400 accommodating the electrode assembly 100. The case 400 may form an outer surface of the secondary battery. In one embodiment, the case 400 may include metal. Therefore, the case 400 may maintain rigidity and may buffer impact, etc., applied to the electrode assembly 100.

[0074] The housing 400 may include a receiving portion 410 for receiving the electrode assembly 100. For example, an opening may be formed on the upper surface of the housing 400 so that the housing 400 may be open in the third direction. The electrode assembly 100 may be received in the receiving portion 410 through the opening.

[0075] The secondary battery may include a cap plate 300. The cap plate 300 may be assembled on the case 400. For example, the cap plate 300 may be assembled on the opening of the case 400 to close the receiving part 410.

[0076] The cap plate 300 may include a cover 310 . The cover 310 may have a plate shape. The cap plate 300 may be combined or connected with the housing 400 through the cover 310 .

[0077] The cap plate 300 may include an injection hole 340. The injection hole 340 may be a hole or an opening formed on the cap 310. The electrolyte may be injected into the case 400 through the injection hole 340.

[0078] The cap plate 300 may further include a vent hole 330. The vent hole 330 may penetrate the cover 310. The space inside the housing 400 may communicate with the outside through the vent hole 330.

[0079] The exhaust hole 330 may be combined with an exhaust plate. When the internal pressure of the housing 400 is greater than or equal to a set pressure, the exhaust plate may be broken. Therefore, the gas inside the housing 400 may be discharged to the outside of the housing 400, so that the internal pressure of the housing 400 may be reduced.

[0080] The cap plate 300 may include an electrode terminal 320. The electrode terminal 320 may be coupled to the cap 310. For example, the cap 310 may include an opening to which the electrode terminal 320 may be coupled. The opening may penetrate the cap 310. The electrode terminal 320 may be connected to the electrode assembly 100 through the opening.

[0081] The electrode terminal 320 may include a positive electrode terminal 320a and a negative electrode terminal 320b. The positive electrode terminal 320a may be electrically connected to the positive electrode tab 120a. The negative electrode terminal 320b may be electrically connected to the negative electrode tab 120b.

[0082] The secondary battery may include a collector plate 200. The collector plate 200 may have a plate shape. Therefore, the volume occupied by the collector plate 200 may be reduced and the space of the electrode assembly 100 may be increased, thereby increasing the capacity and energy density. In addition, the contact area between the collector plate 200 and the electrode assembly 100 increases, thereby reducing the internal resistance of the secondary battery.

[0083] The collector plate 200 may be engaged with the electrode tab 120. The collector plate 200 may be assembled or attached to the cap plate 300 and connected with the electrode terminal 320. The electrode terminal 320 and the electrode tab 120 may be electrically connected to each other through the collector plate 200.

[0084] The collector plate 200 may include a positive collector plate 200a and a negative collector plate 200b. The positive collector plate 200a may be connected to the positive electrode tab 120a and the positive terminal 320a, and the negative collector plate 200b may be connected to the negative electrode tab 120b and the negative terminal 320b.

[0085] The collector plate 200 may include at least one opening 205. The opening 205 may penetrate one side and the other side of the collector plate 200. The collector plate 200 and the electrode tab 120 may be joined through the opening 205.

[0086] According to an exemplary embodiment, a plurality of openings 205 may be formed in the collector plate 200 along the third direction.

[0087] Figure 3 and Figure 4 are three-dimensional diagrams for explaining the joining process of the collector plate and the electrode tab according to an exemplary embodiment. Figure 3 is a perspective view showing a state before a current collector plate is placed on an electrode tab. Figure 4 It is a perspective view showing a state after a current collector plate is placed on an electrode tab.

[0088] Reference Figure 3 and Figure 4 The collector plate 200 may be overlapped on the electrode tab 120. For example, the collector plate 200 may be overlapped on one side of the electrode tab 120 formed by folding the uncoated portion.

[0089] At least a portion of the electrode tab 120 may protrude outside the electrode assembly 100. The electrode tab 120 may partially overlap with the collector plate 200. For example, a portion of the electrode tab 120 that overlaps with the electrode assembly 100 in the second direction may overlap with the collector plate 200 in the second direction.

[0090] The collector plate 200 may be in physical contact with and electrically connected to the electrode tab 120. As described above, the collector plate 200 may include a plurality of openings 205 through which the electrode tab 120 may be partially exposed.

[0091] Figure 5 is along Figure 4 A cross-sectional view of a secondary battery taken along line A-A'. For example, Figure 5 is along Figure 4 The AA' line is a cross-sectional view of the secondary battery observed from the third direction.

[0092] Reference Figure 5 The uncoated portion 122 may protrude from one side of the electrode assembly 100 in the second direction and be aligned. The uncoated portion 122 protruding from the one side may be bent together in one direction. The bent uncoated portion 122 may be assembled to form the electrode tab 120 .

[0093] Since the uncoated portion 122 lies flat in one direction together, a direction perpendicular to the bending direction, such as Figure 5 The collector plate 200 may be arranged so that one surface of the collector plate 200 contacts the curved surface of the electrode tab 120 .

[0094] exist Figure 5FIG. 4 shows a state where the non-coating portion 122 is not completely lying, but the non-coating portion 122 may be pressed by the collector plate 200 to completely lie in the bending direction. Therefore, the collector plate 200 may be disposed closer to the electrode assembly 100 .

[0095] In some embodiments, the uncoated portion 122 may be folded as a whole to form the electrode tab 120 without notching the uncoated portion 122 (eg, referring to Figure 2 ). The electrode assembly can be assembled only through a reel cutting and stacking process without performing a cutting process on the uncoated portion, thereby simplifying the manufacturing process of the secondary battery.

[0096] Figure 6 is a perspective view for explaining a welding process of a current collector plate and an electrode tab according to an exemplary embodiment.

[0097] Reference Figure 6 The electrode tab 120 can be welded to the collector plate 200 through the opening 205 of the collector plate 200 .

[0098] In some embodiments, ultrasonic welding or laser welding may be performed along the boundary of the collector plate 200 and the electrode tab 120 through the opening 205. The collector plate 200 and the electrode tab 120 may be joined to each other by welding.

[0099] The secondary battery may include a welding portion 250 that joins a portion of the electrode tab 120 exposed through the opening 205 and a side edge of the collector plate 200 exposed through the opening 205 .

[0100] The welding portion 250 may be formed along at least one side of the opening portion 205. In one embodiment, the welding portion 250 may be formed along two facing sides of the opening portion 205.

[0101] For example, the welding portion 250 may have a substantially rectangular shape. In one embodiment, the welding portion 250 may be formed along the facing long sides of the opening portion 205. For example, the long sides may face in the third direction. Therefore, the connection reliability of the electrode tab 120 and the collector plate 200 may be improved.

[0102] In one embodiment, the welding portion 250 may also be formed along all sides of the opening portion 205. For example, the welding portion 250 may be formed along facing short sides and facing long sides of the opening portion 250.

[0103] Figure 7 and Figure 8 They are cross-sectional views for explaining the formation process of the welding part. For example, Figure 7 and Figure 8 Along Figure 6 A cross-sectional view of the secondary battery taken along line BB' as viewed from the first direction.

[0104] Reference Figure 7 The heating device may irradiate the laser L or the like to the boundary between one side of the electrode tab 120 exposed through the opening 205 and the side of the collector plate exposed through the opening 205 . The heating device may irradiate along one side of the opening 205 .

[0105] In some embodiments, the current collector plate 200 and the electrode tab 120 may be directly melted and joined by laser or the like at a point where the current collector plate 200 and the electrode tab 120 intersect each other.

[0106] In some embodiments, a bonding material may be inserted into the opening 205 . For example, the bonding material may be inserted along the exposed boundary between the electrode tab 120 and the collector plate 200 , and the bonding material may be melted by a heating device such as a laser to form the weld 250 .

[0107] Reference Figure 8 The welding portion 250 may be formed on the side of the opening 205 and on one side of the electrode tab 120 . The welding portion 250 may cover the side of the collector plate 200 exposed through the opening 205 , and may be partially inserted into the interior of the electrode tab 120 .

[0108] The welding portion 250 may be formed only at the edge of the opening portion 205. For example, even after the welding portion 250 is formed, at least a portion of the electrode tab 120 may be exposed through the opening portion 205.

[0109] For example, the weld portion 250 may be formed by fillet welding. Since the weld portion 250 is formed by fillet welding, the electrode tab 120 and the current collector plate 200 may be welded to each other without the weld portion 250 penetrating the current collector plate 200 .

[0110] Since the weld part 250 is formed by fillet welding, the welding process may be performed even at low energy and low temperature, and impurities generated in the welding process may be prevented from entering the inside of the electrode assembly 100 .

[0111] Fig. 9 and Fig.10 Each is a cross-sectional view for explaining a welding process according to a comparative example. Fig.10 Observed from the first direction Fig. 9 Cross-sectional view of the welded portion.

[0112] Reference Fig. 9, the electrode tab 12 may protrude from one side of the electrode assembly 10. The collector plate 20 may be disposed on the electrode tab 12. The collector plate 20 may be in the shape of a plate without an opening or a through hole.

[0113] When the collector plate 20 and the electrode tab 12 overlap, the laser L may be irradiated to the upper surface of the collector plate 20. For example, the laser L may first contact the collector plate 20 and then penetrate the collector plate 20 to contact the electrode tab 12 below the collector plate 20.

[0114] For example, the current collector plate 20 and the electrode tab 12 may be lap-welded to form a welded portion 25 connecting the current collector plate 20 and the electrode tab 12 .

[0115] Reference Fig.10 In order to join the electrode tab 12 located below the collector plate 20 to the collector plate 20, the welding portion 25 may penetrate the collector plate 20. In this case, since the welding portion 25 penetrates the collector plate 20, the thickness of the collector plate 20 needs to be thinner, and the resistance of the collector plate 20 may increase.

[0116] In addition, the laser L used for welding is emitted to the electrode assembly 10 , and foreign matters such as spatter, dust, and smoke generated during the welding process may enter the interior of the electrode assembly 10 .

[0117] According to an exemplary embodiment of the present disclosure, since the welding portion 250 is formed by fillet welding through the opening portion 205, it can be formed at relatively low energy and low temperature. Therefore, foreign matter such as spatter and fume can be reduced. In addition, the thickness of the collector plate 200 can be increased, thereby reducing resistance and improving the degree of freedom of design and process.

[0118] In some embodiments, the weld 250 may be at least partially exposed to the outside through the opening 205. For example, the weld 250 may be partially formed along the edge of the opening 205. Since the weld 250 is not restricted by the substrates such as the collector plate 200 and the electrode tab 120, the stress generated by metal solidification may be reduced, and the crack sensitivity of the weld 250 may be reduced.

[0119] For example, in Fig.10 In the comparative example of , since the base material surrounds the welding portion 25, the stress generated by the base material due to metal solidification may increase. In this case, since a strong stress acts on the welding portion 25, cracks may be generated.

[0120] In addition, according to the embodiment of the present disclosure, the welded portion 250 can be confirmed from the outside after the welding process of the current collector plate 200 and the electrode tab 120. Therefore, the welding quality and foreign matter management can be easily performed.

[0121] Fig.11 is a perspective view for explaining a secondary battery according to an exemplary embodiment.

[0122] Reference Fig.11 , the end of the electrode tab 120 protruding to the outside of the collector plate 200 may be folded to set the end of the electrode tab 120 on the collector plate 200 .

[0123] The end portion of the electrode tab 120 may be bent in a direction opposite to a direction in which the uncoated portion 122 is bent.

[0124] The end of the electrode tab 120 may be joined to the collector plate 200. For example, the end of the electrode tab 120 and the collector plate 200 may be fixed by welding.

[0125] Fig.12 is along Fig.11 The cross-sectional view of the secondary battery taken along the CC' line. For example, Fig.12 is along Fig.11 The CC' line is a cross-sectional view of the secondary battery observed from the third direction.

[0126] Reference Fig.12 The electrode tab 120 may include a first bonding portion CP1, a bent portion BP, and a second bonding portion CP2. The first bonding portion CP1 and the second bonding portion CP2 may be connected to each other through the bent portion BP.

[0127] The first bonding portion CP1 and the second bonding portion CP2 may extend in opposite directions to each other. The first bonding portion CP1 and the second bonding portion CP2 may face each other through the bent portion BP.

[0128] The collector plate 200 may be interposed between the first joint portion CP1 and the second joint portion CP2. For example, the first joint portion CP1 may contact the lower surface of the collector plate 200, and the second joint portion CP2 may contact the upper surface of the collector plate 200. Therefore, the contact area between the collector plate 200 and the electrode tab 120 may be increased, and the internal resistance of the secondary battery may be reduced.

[0129] In one embodiment, the second joint portion CP2 and the collector plate 200 may be fillet welded through the opening 205. For example, a weld may be formed along one side of the second joint portion CP2 facing the collector plate 200 and the side surface of the collector plate 200 exposed through the opening 205.

[0130] In one embodiment, when viewed on a plane viewed from the second direction, the area of ​​the opening 205 may be less than 40% of the total area of ​​the collector plate 200. Therefore, an increase in resistance caused by the opening 205 may be suppressed.

[0131] In one embodiment, when viewed from the plane viewed from the second direction, the area of ​​the opening 205 may be greater than 5% of the total area of ​​the collector plate 200. Therefore, sufficient space may be ensured for fillet welding of the collector plate 200 and the electrode tab 120.

[0132] In some embodiments, the area of ​​the welding portion 250 may be 1% to 10% of the total area of ​​the opening 205 on a plane viewed from the second direction. Within the above range, welding efficiency and reliability may be ensured, while resistance increase and foreign matter generation caused by the welding portion 250 may be suppressed.

[0133] In some embodiments, the opening 205 may have a circular shape or a polygonal shape such as a triangle, a quadrilateral, a pentagon, or a hexagon.

[0134] In some embodiments, the case 400 may contain an electrolyte inside to impregnate the electrode assembly 100. For example, a non-aqueous electrolyte may be used as the electrolyte.

[0135] The non-aqueous electrolyte may include a lithium salt and an organic solvent. The lithium salt may be represented by Li + X - The negative ion (X - ) can use F - , Cl - Br - ,I - 、NO 3 - 、N(CN) 2 - , BF 4 - , ClO 4 - PF 6 - ,(CF 3 ) 2 PF 4 - ,(CF 3 ) 3 PF 3 - ,(CF 3 ) 4 PF 2 - ,(CF 3 ) 5 PF - ,(CF 3 ) 6 P - CF 3 SO3 - CF 3 CF 2 SO 3 - ,(CF 3 SO 2 ) 2 N - 、(FSO 2 ) 2 N - CF 3 CF 2 (CF 3 ) 2 CO - ,(CF 3 SO 2 ) 2 CH - , (SF 5 ) 3 C - ,(CF 3 SO 2 ) 3 C - CF 3 (CF 2 ) 7 SO 3 - CF 3 CO 2 - , CH 3 CO 2 - 、SCN - ,(CF 3 CF 2 SO 2 ) 2 N - Etc. These may be used alone or in combination of two or more.

[0136] Non-limiting examples of the organic solvent may include propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), methyl propyl carbonate, dipropyl carbonate, dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, vinylene carbonate, sulfolane, γ-butyrolactone, propylene sulfite, tetrahydrofuran, etc. They may be used alone or in combination of two or more.

[0137] Figure 1The shape of the case 400 shown is exemplary and may be appropriately changed according to the shape and height of the electrode assembly 100 and the structure of a module or battery pack to which the secondary battery is applied.

Claims

1. A secondary battery comprising: An electrode assembly, including an electrode tab; A collector plate, comprising at least one opening and contacting one side of the electrode tab; as well as A welding portion is formed in the opening along at least a portion of a boundary where the electrode tab contacts the collector plate, and the welding portion joins a portion of the one surface of the electrode tab exposed through the opening and the collector plate.

2. The secondary battery according to claim 1, wherein The opening penetrates one surface and the other surface of the current collector plate.

3. The secondary battery according to claim 1, wherein The welding portion does not penetrate the current collecting plate.

4. The secondary battery according to claim 1, wherein The welding portion covers at least one side surface of the current collector plate exposed through the opening and is partially inserted into the electrode tab.

5. The secondary battery according to claim 1, wherein The electrode tab comprises: a first engaging portion protruding from the electrode assembly; a second engaging portion extending in a direction opposite to the first engaging portion; and The bent portion is disposed between the first joining portion and the second joining portion.

6. The secondary battery according to claim 5, wherein The first engaging portion and the second engaging portion face each other through the bent portion.

7. The secondary battery according to claim 5, wherein One surface of the collector plate is in contact with the first joint portion, and the other surface of the collector plate is in contact with the second joint portion.

8. The secondary battery according to claim 1, wherein The electrode assembly includes a plurality of electrodes repeatedly stacked and a separator interposed between the plurality of electrodes. Each of the plurality of electrodes includes an uncoated portion.

9. The secondary battery according to claim 8, wherein The electrode tab is formed by bending the uncoated portion protruding from one side of the electrode assembly in one direction.

10. The secondary battery according to claim 8, wherein The electrode assembly includes: a plurality of positive electrodes, each of which includes a positive electrode non-coating portion; and a plurality of negative electrodes, each of which includes a negative electrode non-coating portion. The positive electrode non-coating portion protrudes from one side of the electrode assembly, and the negative electrode non-coating portion protrudes from the other side of the electrode assembly.

11. The secondary battery according to claim 10, wherein The electrode tab includes a positive electrode tab formed by bending the positive electrode uncoated portion together and a negative electrode tab formed by bending the negative electrode uncoated portion together.

12. The secondary battery according to claim 1, further comprising: A shell, accommodating the electrode assembly; A cover plate, closing the housing; as well as The electrode terminal is mounted on the cover plate and is electrically connected to the electrode tab.

13. A method for manufacturing a secondary battery, comprising the following steps: preparing a preliminary electrode assembly, the uncoated portion protruding outside the preliminary electrode assembly; bending the uncoated portion in one direction to form an electrode tab; Disposing a current collector plate including at least one opening on the electrode tab so that one side of the current collector plate overlaps with one side of the electrode tab; Through the opening, welding the electrode tab and the collector plate along at least one side of the opening; as well as The end portion of the electrode tab protruding to the outside of the current collector plate is bent so that the end portion overlaps with the other surface of the current collector plate.

14. The method for manufacturing a secondary battery according to claim 13, wherein: The step of welding the electrode tab and the collector plate includes irradiating laser along a boundary between the electrode tab and the collector plate exposed through the opening.

15. The method for manufacturing a secondary battery according to claim 13, wherein: The end portion of the electrode tab protruding to the outside of the current collector plate is bent in a direction opposite to a direction in which the uncoated portion is bent.

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