Electrode assembly and manufacturing method thereof

Abstract

To solve the above problems, a method for manufacturing an electrode assembly according to an embodiment of the present invention includes the steps of: manufacturing an electrode by applying an electrode active material to at least a portion of an electrode current collector formed by sequentially stacking a first electrode foil, an electrode insulating layer, and a second electrode foil; stacking the electrode and a separator; and connecting an electrode lead to an uncoated portion of the electrode current collector where the electrode active material is not applied, wherein the step of connecting the electrode lead involves connecting the electrode current collector and the electrode lead by a fastening portion penetrating both of them.

Description

[Technical field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0148935 filed on November 19, 2019, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to an electrode assembly and a manufacturing method thereof, and more particularly to an electrode assembly in which an electrode current collector is formed in a multi-layer structure including an electrode insulating layer, and only one electrode lead is connected to an uncoated portion, thereby enabling all electricity generated inside to be fully supplied to the outside, and a manufacturing method thereof. [Background technology]

[0003] Generally, types of secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries. Such secondary batteries are used not only in small products such as digital cameras, portable DVD players (P-DVDs), MP3 players (MP3Ps), mobile phones, PDAs, portable game devices, power tools, and E-bikes, but also in large products that require high output such as electric vehicles and hybrid vehicles, power storage devices that store surplus generated power and renewable energy, and backup power storage devices.

[0004] To manufacture an electrode assembly, a cathode, a separator, and an anode are manufactured and stacked. Specifically, a cathode active material slurry is applied to a cathode current collector, and an anode active material slurry is applied to an anode current collector to manufacture a cathode and an anode. Then, when a separator is interposed between the manufactured cathode and anode and they are stacked, a unit cell is formed, and the unit cells are stacked on top of each other to form an electrode assembly. Then, the electrode assembly is housed in a specific case and an electrolyte is injected to manufacture a secondary battery.

[0005] In the past, the positive and negative electrodes were formed in a single-layer structure, and electricity could flow between both sides of the electrodes. Therefore, when the electrode assembly was damaged by an external impact, a short circuit occurred on one side of the electrodes, and when a short circuit also occurred on the other side of the electrodes, there was a problem that a risk of explosion or the like could occur. Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to provide an electrode assembly and a manufacturing method thereof, in which an electrode current collector is formed in a multi-layer structure including an electrode insulating layer, and only one electrode lead is connected to an uncoated portion, so that all electricity generated inside can be sufficiently supplied to the outside.

[0007] The object of the present invention is not limited to the above-mentioned objects, and other objects not mentioned herein will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0008] In order to solve the above problems, a method for manufacturing an electrode assembly according to an embodiment of the present invention includes the steps of manufacturing an electrode by applying an electrode active material to at least a portion of an electrode collector formed by sequentially stacking a first electrode foil, an electrode insulating layer, and a second electrode foil, stacking the electrode and a separator, and connecting an electrode lead to an uncoated portion of the electrode collector where the electrode active material is not applied, wherein the step of connecting the electrode lead comprises a fastening portion penetrating and connecting both the electrode collector and the electrode lead.

[0009] In addition, in the step of connecting the electrode lead, the electrode current collector and the electrode lead may be connected by rivet connection.In addition, in the step of connecting the electrode lead, the electrode current collector and the electrode lead may be connected by screw connection.

[0010] In the step of connecting the electrode lead, the fastening portion may be made of a conductive material, and in the step of connecting the electrode lead, the fastening portion may penetrate all of the first electrode foil, the electrode insulating layer, and the second electrode foil of the electrode current collector.

[0011] To solve the above problems, an electrode assembly according to an embodiment of the present invention includes electrodes having an electrode active material applied to at least a portion of an electrode collector, a separator stacked between the electrodes, an electrode lead connected to an uncoated portion of the electrode collector where the electrode active material is not applied, and a fastening portion that penetrates and connects the electrode collector and the electrode lead together, and the electrode collector is formed by sequentially stacking a first electrode foil, an electrode insulating layer, and a second electrode foil.

[0012] The fastening portion may be a rivet, the fastening portion may be a screw, and the fastening portion may be made of a conductive material.

[0013] In addition, the fastening portion may penetrate through all of the first electrode foil, the electrode insulating layer, and the second electrode foil of the electrode current collector. Other specific features of the present invention are included in the detailed description and drawings. Effect of the Invention

[0014] According to the embodiment of the present invention, at least the following effects are obtained: The electrode collector is formed in a multi-layer structure including an electrode insulating layer, and a conductive fastening part penetrates and connects both the uncoated part of the electrode collector and the electrode lead, so that electricity generated inside the electrode assembly can be fully supplied to the outside with only one electrode lead.

[0015] The effects of the present invention are not limited to the above-mentioned examples, and various other effects are included within the present specification. [Brief description of the drawings]

[0016] [Figure 1] 1 is an enlarged cross-sectional view of a cylindrical secondary battery according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing a side surface of an electrode current collector according to one embodiment of the present invention. [Diagram 3] 11A and 11B are schematic diagrams showing a state in which a plurality of electrode leads are connected to uncoated portions of a positive electrode foil and a negative electrode foil, respectively, from the side. [Figure 4] 13 is a schematic diagram showing a state in which a plurality of electrode leads are connected to a plain portion from above. FIG. [Diagram 5] 13 is a schematic diagram showing a state in which a plurality of electrode leads are connected to the uncoated portion, as viewed from below. FIG. [Figure 6] 4A and 4B are schematic side views showing electrode leads connected to uncoated portions of a positive electrode foil and a negative electrode foil according to an embodiment of the present invention; [Figure 7] 13 is a schematic diagram showing an electrode lead connected to a plain portion from above. FIG. [Figure 8] 13 is a schematic diagram showing an electrode lead connected to a plain portion from below. FIG. [Figure 9] 11A and 11B are schematic side views showing electrode leads connected to uncoated portions of a positive electrode foil and a negative electrode foil according to another embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The advantages and features of the present invention, and the methods for achieving them, will become apparent from the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be realized in various different forms. The embodiments are provided merely to make the disclosure of the present invention complete and to fully convey the scope of the invention to those skilled in the art to which the present invention pertains, and the present invention is defined only by the scope of the claims. The same reference numerals refer to the same elements throughout the specification.

[0018] Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used as meanings commonly understood by those having ordinary skill in the art to which the present invention belongs. Furthermore, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless clearly defined otherwise.

[0019] The terms used in this specification are for describing the embodiments and are not intended to limit the present invention. In this specification, the singular form includes the plural form unless otherwise specified in the phrase. The words "comprise" and / or "comprising" used in the specification do not exclude the presence or addition of one or more other components in addition to the components mentioned.

[0020] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an enlarged cross-sectional view of a cylindrical secondary battery 1 according to an embodiment of the present invention. To manufacture the cylindrical secondary battery 1, a slurry containing a mixture of an electrode active material, a binder, and a plasticizer is applied to a positive electrode collector 101 and a negative electrode collector 102 to manufacture electrodes such as a positive electrode and a negative electrode, which are then laminated on both sides of a separator to form an electrode assembly 11 having a predetermined shape. Then, a pressure is applied from the outside to the inside of the upper part of the battery can 12 to stretch the battery can 12, thereby forming a beading part 14. Then, the electrode assembly 11 is inserted into the battery can 12, and an electrolyte is injected. Next, a crimping gasket 136 is placed on the upper part of the beading part 14, and the upper open part of the battery can 12 is sealed with a cap assembly 13. The cylindrical secondary battery 1 can be used as a power source for mobile phones, notebook computers, electric vehicles, etc., which stably provide a constant output.

[0021] As shown in FIG. 1, a cylindrical secondary battery 1 includes a jelly-roll-shaped electrode assembly 11, a cylindrical battery can 12 that houses the electrode assembly 11 therein, a cap assembly 13 that is coupled to the top of the battery can 12 and seals the open top end of the battery can 12, a beading portion 14 that is recessed from the outside to the inside of the top of the battery can 12 to attach the cap assembly 13, and a crimping portion 15 for sealing the battery.

[0022] The electrode assembly 11 is formed by stacking electrodes and separators. Specifically, the electrode assembly 11 includes two types of electrodes, such as a positive electrode and a negative electrode, and a separator interposed between the electrodes to insulate the electrodes from each other. The electrode assembly 11 may be of a stack type, a jelly roll type, a stack & folding type, or the like. The two types of electrodes, i.e., the positive electrode and the negative electrode, are each structured such that an active material slurry is applied to electrode collectors 101 and 102 having a multilayer structure including electrode insulating layers 1013 and 1023. The electrode collectors 101 and 102 according to an embodiment of the present invention are formed in a multilayer structure in which electrode insulating layers 1013 and 1023 are stacked between two electrode foils. The electrode collectors 101 and 102 will be described in detail later. The slurry may be formed by stirring a granular active material, an auxiliary conductor, a binder, a plasticizer, and the like, with a solvent added thereto. The solvent is removed in a subsequent process. Hereinafter, the electrode assembly 11 according to an embodiment of the present invention will be described as having a jelly roll type, but this is for convenience of explanation and is not intended to limit the scope of the invention.

[0023] To manufacture the jelly roll type electrode assembly 11, a pair of long positive and negative electrodes and one separator are stacked and wound from one side to the other. The electrodes of the electrode assembly 11 are composed of electrode current collectors 101, 102, which are coated with an electrode active material, and end portions, i.e., uncoated portions 111, 112, where the electrode active material is not coated. The uncoated portions 111, 112 (shown in FIG. 3) may be present at the start and end of the electrode in the direction in which it is wound. A pair of electrode leads 113 corresponding to the respective electrodes are connected to the uncoated portions 111, 112. A positive electrode lead 1131 having one end connected to the positive electrode uncoated portion 111 is drawn out from the upper end of the electrode assembly 11 and has the other end electrically connected to the cap assembly 13, and a negative electrode lead 1132 having one end connected to the negative electrode uncoated portion 112 is drawn out from the lower end of the electrode assembly 11 and has the other end connected to the bottom of the battery can 12. However, without being limited thereto, the positive electrode lead 1131 and the negative electrode lead 1132 may both be drawn out in various directions, such as toward the cap assembly 13.

[0024] Insulating plates 16 that insulate the electrode assembly 11 are disposed at the upper and lower ends of the electrode assembly 11. The upper insulating plate 16 disposed at the upper end is disposed between the electrode assembly 11 and the cap assembly 13 to insulate the electrode assembly 11, and the lower insulating plate (not shown) disposed at the lower end is disposed between the electrode assembly 11 and the bottom of the battery can 12 to insulate the electrode assembly 11.

[0025] The battery can 12 is a can made of a rigid material that houses the electrode assembly 11. The battery can 12 may be formed in a cylindrical shape, but may be formed in various shapes such as a rectangular shape depending on the shape of the electrode assembly 11, so that the electrode assembly 11 can be easily housed inside.

[0026] The battery can 12 may be made of a lightweight conductive metal material such as aluminum, nickel, stainless steel, or an alloy thereof, and may have an open top and a sealed bottom opposite the open top. A center pin (not shown) may be inserted into the center of the battery can 12 to prevent the electrode assembly 11 wound up in a jelly roll shape from unwinding and to function as a passage for gas movement inside the secondary battery 1.

[0027] The cap assembly 13 is coupled to an opening formed at the upper end of the battery can 12 to seal the opening of the battery can 12. The cap assembly 13 may be formed in various shapes, such as a circular or rectangular shape, depending on the shape of the battery can 12. If the battery can 12 is formed in a cylindrical shape, it is preferable that the cap assembly 13 is also formed in a corresponding disc shape.

[0028] The cap assembly 13 has a structure in which a top cap 131 that seals the open part of the battery can 12 and forms the positive electrode terminal, a PTC element 132 that increases in resistance and cuts off the current when the temperature inside the battery rises, a safety vent 133 that cuts off the current and exhausts the internal gas when the pressure inside the battery rises due to an abnormal current, a CID gasket 134 that electrically isolates the safety vent 133 from the CID filter 135 except for specific parts, and a CID filter 135 to which a positive electrode lead 1131 connected to the positive electrode is connected and which cuts off the current when high pressure is generated inside the battery is connected, are sequentially stacked.

[0029] The cap assembly 13 is attached to the crimping gasket 136 and is then placed on the beading portion 14 of the battery can 12. Thus, under normal operating conditions, the positive electrode of the electrode assembly 11 is connected to the top cap 131 via the positive electrode lead 1131, the CID filter 135, the safety vent 133, and the PTC element 132 to conduct electricity.

[0030] The top cap 131 is disposed at the top of the cap assembly 13 in a form of protruding upward to form a positive electrode terminal. Thus, the top cap 131 can be electrically connected to an external device such as a load or a charging device. The top cap 131 may have a gas hole 1311 through which gas generated inside the secondary battery 1 is discharged. Thus, when gas is generated from the electrode assembly 11 side due to overcharging or the like and the internal pressure increases, the CID filter 135 and the safety vent 133 of the current interrupting member are ruptured, and the internal gas can be discharged to the outside through the ruptured portion and the gas hole 1311. Thus, charging and discharging do not proceed any further, and the safety of the secondary battery 1 can be ensured. The top cap 131 may be manufactured from a metal material such as stainless steel or aluminum.

[0031] The thickness of the portion of top cap 131 that comes into contact with PTC element 132 is not particularly limited as long as it is within a range capable of protecting various components of cap assembly 13 from pressure applied from the outside, and may be, for example, 0.3 to 0.5 mm. If the thickness of top cap 131 is too thin, it is difficult to exert mechanical rigidity, and conversely, if it is too thick, the increase in size and weight may reduce the capacity of the battery compared to the same specification.

[0032] When the temperature inside the battery rises, the PTC element (Positive Temperature Coefficient element) 132 cuts off the current by increasing the battery resistance. That is, the PTC element 132 electrically connects the top cap 131 and the safety vent 133 in a normal state. However, in an abnormal state, for example, when the temperature rises abnormally, the PTC element 132 cuts off the electrical connection between the top cap 131 and the safety vent 133. The thickness of the PTC element 132 may also vary depending on the material and structure, and may be, for example, 0.2 to 0.4 mm. If the thickness of the PTC element 132 is thicker than 0.4 mm, the internal resistance increases, the size of the battery increases, and the battery capacity may decrease compared to the same standard. Conversely, if the thickness of the PTC element 132 is thinner than 0.2 mm, it is difficult to exhibit a current cut-off effect at high temperatures and may be destroyed even by a weak external impact. Therefore, the thickness of the PTC element 132 may be appropriately determined within the above thickness range by considering these factors in a comprehensive manner.

[0033] The safety vent 133 may be made of a metal material, and may cut off the current or exhaust gas when the pressure inside the battery increases due to an abnormal current. The outer periphery of the safety vent 133 is inserted into the crimping gasket 136, and the lower surface of the center part is connected to the CID filter 135. When the internal pressure of the battery increases, the CID filter 135 bursts and the shape of the safety vent 133 is reversed. The thickness of the safety vent 133 may vary depending on the material and structure, and is not particularly limited as long as it can burst and exhaust gas when a predetermined high pressure is generated inside the battery, and may be, for example, 0.2 to 0.6 mm.

[0034] A current interrupt device (CID) is located between the safety vent 133 and the electrode assembly 11, and electrically connects the electrode assembly 11 and the safety vent 133. The current interrupt device includes a CID filter 135 that contacts the safety vent 133 to transmit current, and a CID gasket 134 that spatially separates and insulates the CID filter 135 and the safety vent 133 except for some areas.

[0035] At least a portion of the upper part of the CID filter 135 is connected to the lower surface of the central portion protruding toward the center of the safety vent 133, and at least a portion of the lower part is connected to the electrode lead 113, particularly the positive lead 1131, of the electrode assembly 11. Thus, in a normal state, a positive current generated from the electrode assembly 11 flows through the positive lead 1131 and the CID filter 135 to the safety vent 133, thereby discharging the secondary battery 1. However, when the internal pressure of the battery increases due to gas generated inside the secondary battery 1 and the shape of the safety vent 133 is reversed, the connection between the safety vent 133 and the CID filter 135 is detached or the CID filter 135 is ruptured. As a result, the electrical connection between the safety vent 133 and the electrode assembly 11 is cut off, ensuring safety.

[0036] A secondary battery 1 including such a cap assembly 13, when used as a power source for a power tool such as an electric drill, can provide instantaneous high output and can be stable against external physical shocks such as vibrations and drops.

[0037] A beading portion 14 is formed by bending the top of the battery can 12 from the outside to the inside. The beading portion 14 positions the cap assembly 13, in which the top cap 131, the PTC element 132, the safety vent 133, and the current interrupting member are stacked, at the upper end of the battery can 12 and prevents the electrode assembly 11 from moving up and down.

[0038] As described above, the cap assembly 13 is attached to the beading portion 14 of the battery can 12 while being attached to the crimping gasket 136. The crimping gasket 136 surrounds and insulates the outermost portion of the periphery 1331 of the safety vent 133, thereby preventing a short circuit from occurring due to contact between the positive electrode current flowing through the safety vent 133 and the negative electrode current flowing through the battery can 12.

[0039] The crimping gasket 136 has a cylindrical shape with both ends open so as to easily surround the peripheral portion 1331 of the safety vent 133, and one end facing the inside of the battery can 12 is primarily bent approximately vertically toward the central axis as shown in FIG. 2, and then bent again approximately vertically toward the inside of the battery can 12 to be placed on the beading portion 14. The other end of the crimping gasket 136 initially extends in a direction parallel to the central axis. However, when the cap assembly 13 is then joined and the upper outer wall of the battery can 12 is pressed to proceed with the crimping process, the other end is bent approximately vertically along the shape of the crimping portion 15 toward the central axis. Thus, the inner circumferential surface of the crimping gasket 136 is in close contact with the cap assembly 13, and the outer circumferential surface is in close contact with the inner circumferential surface of the battery can 12. Here, the crimping process refers to bending the crimping portion 15 so that the crimping portion 15 and the crimping gasket 136 seal the outer surface of the cap assembly 13. The crimping gasket 136 is preferably made of a material having insulating properties, impact resistance, elasticity, and durability, for example, a polymer such as polyolefine or polypropylene (PP).

[0040] When the electrode lead 113 is connected to the uncoated portions 111 and 112 of the electrode assembly 11, the electrode assembly 11 is inserted into the battery can 12, the positive electrode lead 1131 is connected to the CID filter 135 of the cap assembly 13, and the negative electrode lead 1132 is connected to the bottom of the battery can 12. Then, an electrolyte is injected into the battery can 12. Next, a crimping gasket 136 is placed on the top of the beading portion 14, and the upper open portion of the battery can 12 is sealed by the cap assembly 13. The electrolyte is for moving lithium ions generated by an electrochemical reaction of the electrodes when the secondary battery 1 is charged and discharged, and may include a non-aqueous organic electrolyte that is a mixture of a lithium salt and a high-purity organic solvent, or a polymer using a polymer electrolyte. By this method, a cylindrical secondary battery 1 can be manufactured.

[0041] 2 is a schematic diagram showing the side of electrode current collectors 101 and 102 according to one embodiment of the present invention. As described above, electrodes such as a positive electrode and a negative electrode are manufactured by coating a slurry in which an electrode active material, a binder, and a plasticizer are mixed onto electrode current collectors 101 and 102, such as a positive electrode current collector 101 and a negative electrode current collector 102, respectively.

[0042] Conventionally, the positive electrode current collector 101 and the negative electrode current collector 102 are each formed in a single layer structure. Therefore, if the electrode assembly 11 is damaged by an external impact, there is a problem that a risk of explosion due to a short circuit may occur. However, according to an embodiment of the present invention, as shown in FIG. 2, the electrode current collectors 101 and 102 are formed in a multi-layer structure in which electrode insulating layers 1013 and 1023 are laminated between first and second electrode foils. Specifically, the positive electrode current collector 101 is formed by sequentially laminating a first positive electrode foil 1011, a positive electrode insulating layer 1013, and a second positive electrode foil 1012. And, the negative electrode current collector 102 is formed by sequentially laminating a first negative electrode foil 1021, a negative electrode insulating layer 1023, and a second negative electrode foil 1022.

[0043] The first and second positive electrode foils 1011, 1012 are made of a material that does not induce chemical changes and has high conductivity. For example, they may be stainless steel, aluminum, nickel, titanium, baked carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., and aluminum is particularly preferable, but is not limited thereto. The first and second positive electrode foils 1011, 1012 may have fine irregularities on their surfaces to increase the adhesive strength of the positive electrode active material.

[0044] The first and second negative electrode foils 1021, 1022 are made of a material that does not induce chemical changes and has electrical conductivity. For example, the material may be copper, stainless steel, nickel, titanium, calcined carbon, or a copper or stainless steel surface treated with carbon, nickel, titanium, silver, or an aluminum-cadmium alloy, and in particular, copper or nickel-plated copper is preferable, but is not limited thereto. The first and second negative electrode foils 1021, 1022 may have fine irregularities on their surfaces to increase the binding strength of the negative electrode active material.

[0045] The positive electrode insulating layer 1013 is laminated between the first positive electrode foil 1011 and the second positive electrode foil 1012 to insulate the first positive electrode foil 1011 from the second positive electrode foil 1012. The negative electrode insulating layer 1023 is laminated between the first negative electrode foil 1021 and the second negative electrode foil 1022 to insulate the first negative electrode foil 1021 from the second negative electrode foil 1022. As a result, even if the electrode assembly 11 is damaged by an external impact, one side and the other side of one electrode are electrically disconnected, thereby preventing dangers such as explosion due to a short circuit and ensuring safety. The positive electrode insulating layer 1013 and the negative electrode insulating layer 1023 may be made of one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon (registered trademark), and glass fiber. In particular, polymers such as nylon resin or polyethylene terephthalate (PET), which are mainly abrasion-resistant and heat-resistant, are used.

[0046] FIG. 3 is a schematic diagram showing from the side the state in which multiple electrode leads 113 are connected to the uncoated portions 111, 112 of the positive electrode foils 1011, 1012 and the negative electrode foils 1021, 1022, respectively; FIG. 4 is a schematic diagram showing from above the state in which multiple electrode leads 113 are connected to the uncoated portions 111, 112; and FIG. 5 is a schematic diagram showing from below the state in which multiple electrode leads 113 are connected to the uncoated portions 111, 112.

[0047] As described above, one end of the positive electrode lead 1131 is connected to the positive electrode uncoated portion 111, is drawn out from the upper end of the electrode assembly 11, and is electrically connected to the cap assembly 13 at the other end. And, the negative electrode lead 1132 is connected to the negative electrode uncoated portion 112 at one end, is drawn out from the lower end of the electrode assembly 11, and is connected to the bottom of the battery can 12 at the other end.

[0048] The positive electrode lead 1131 and the negative electrode lead 1132 may be made of different materials. That is, the positive electrode lead 1131 may be made of the same aluminum (Al) material as the positive electrode foils 1011 and 1012 of the positive electrode current collector 101, and the negative electrode lead 1132 may be made of the same copper (Cu) material or nickel (Ni) coated copper material as the negative electrode foils 1021 and 1022 of the negative electrode current collector 102.

[0049] On the other hand, if the electrode collectors 101, 102 are formed in a single layer structure, even if one electrode lead 113 is connected to only one side of the uncoated portions 111, 112, all of the electricity generated inside the electrode assembly 11 can be sufficiently supplied to the outside of the secondary battery 1.

[0050] However, according to one embodiment of the present invention, since the electrode current collectors 101, 102 are formed in a multi-layer structure in which the electrode insulating layers 1013, 1023 are laminated between the first and second electrode foils, if one electrode lead 113 is connected to only one electrode foil, the other electrode foils are not connected to the electrode lead 113, and therefore, electricity generated inside the electrode assembly 11 is not entirely supplied to the outside. Therefore, the multiple electrode leads 113 must all be connected to the respective electrode foils.

[0051] As shown in FIG. 3, the multiple electrode leads 113 include two positive electrode leads 1131 connected to the first positive electrode foil 1011 and the second positive electrode foil 1012, respectively, and two negative electrode leads 1132 connected to the first negative electrode foil 1021 and the second negative electrode foil 1022, respectively.

[0052] Specifically, the two positive electrode leads 1131 are connected to the positive electrode uncoated portion 111 of the first positive electrode foil 1011 and the positive electrode uncoated portion 111 of the second positive electrode foil 1012, respectively. And, the two negative electrode leads 1132 are connected to the negative electrode uncoated portion 112 of the first negative electrode foil 1021 and the negative electrode uncoated portion 112 of the second negative electrode foil 1022, respectively. Thus, electricity generated inside the electrode assembly 11 can be entirely supplied to the outside of the secondary battery 1 through the plurality of electrode leads 113. The positive electrode lead 1131 and the negative electrode lead 1132 may be connected to the positive electrode uncoated portion 111 and the negative electrode uncoated portion 112, respectively, by ultrasonic welding, spot welding, etc. Then, welding may be repeatedly performed along the longitudinal direction of the positive electrode lead 1131 and the negative electrode lead 1132 to form a plurality of welded parts 2 arranged in a line, as shown in FIGS.

[0053] However, this method requires a plurality of electrode leads 113, which must be separately welded to the first and second electrode foils, resulting in excessive manufacturing costs and time.

[0054] FIG. 6 is a schematic diagram showing, from the side, how electrode leads 113 are connected to uncoated portions 111 and 112 of positive electrode foils 1011 and 1012 and negative electrode foils 1021 and 1022, respectively, in one embodiment of the present invention; FIG. 7 is a schematic diagram showing, from above, how electrode leads 113 are connected to uncoated portions 111 and 112; and FIG. 8 is a schematic diagram showing, from below, how electrode leads 113 are connected to uncoated portions 111 and 112.

[0055] According to one embodiment of the present invention, the electrode collectors 101, 102 are formed in a multi-layer structure including electrode insulating layers 1013, 1023, and a conductive fastening portion 114 penetrates and connects the uncoated portions 111, 112 of the electrode collectors 101, 102 and the electrode lead 113, so that all of the electricity generated inside the electrode assembly 11 can be sufficiently supplied to the outside using only one electrode lead 113.

[0056] To this end, a method for manufacturing an electrode assembly 11 according to one embodiment of the present invention includes the steps of manufacturing an electrode by applying an electrode active material to at least a portion of an electrode collector 101, 102 formed by sequentially stacking first electrode foils 1011, 1021, electrode insulating layers 1013, 1023, and second electrode foils 1012, 1022, stacking the electrodes and separators, and connecting an electrode lead 113 to uncoated portions 111, 112 of the electrode collectors 101, 102 where the electrode active material is not applied, and the step of connecting the electrode lead 113 comprises connecting the electrode collectors 101, 102 and the electrode lead 113 by a fastening portion 114 penetrating both the electrode collectors 101, 102 and the electrode lead 113.

[0057] The electrode assembly 11 according to one embodiment of the present invention manufactured by this method includes electrodes having an electrode active material applied to at least a portion of electrode collectors 101, 102, a separator laminated between the electrodes, an electrode lead 113 connected to uncoated portions 111, 112 of the electrode collectors 101, 102 where the electrode active material is not applied, and a fastening portion 114 penetrating and connecting the electrode collectors 101, 102 and the electrode lead 113, and the electrode collectors 101, 102 are formed by sequentially laminating first electrode foils 1011, 1021, electrode insulating layers 1013, 1023, and second electrode foils 1012, 1022.

[0058] One electrode lead 113 is in contact with the first electrode foils 1011, 1021 of the electrode collectors 101, 102. A fastening part 114 penetrates and connects the electrode collectors 101, 102 and the electrode lead 113. Specifically, as shown in FIG. 6, first, one positive electrode lead 1131 is in contact with the first positive electrode foil 1011 at the uncoated parts 111, 112 of the positive electrode collector 101, and one negative electrode lead 1132 is in contact with the first negative electrode foil 1021 at the uncoated parts 111, 112 of the negative electrode collector 102. One fastening part 114 penetrates and connects the positive electrode collector 101 and the positive electrode lead 1131, and the other fastening part 114 penetrates and connects the negative electrode collector 102 and the negative electrode lead 1132.

[0059] According to an embodiment of the present invention, the fastening portion 114 is a rivet. Thus, the electrode collectors 101, 102 and the electrode lead 113 may be connected by riveting using a rivet. In this case, the electrode collectors 101, 102 and the electrode lead 113 may be separately drilled and then riveted, but it is preferable to connect them by passing the rivet through without a separate drilling operation using a rivet gun. When the electrode collectors 101, 102 and the electrode lead 113 are riveted, the heads on both ends of the rivet are formed larger than the size of the hole through which the rivet is passed, so that the rivet can be fixed so as not to come off to the outside.

[0060] Riveting may be repeated along the longitudinal direction of the positive electrode lead 1131 and the negative electrode lead 1132 to form a plurality of fastening portions 114 arranged in a line, as shown in Figures 7 and 8. This allows the electrode current collectors 101, 102 and the electrode lead 113 to be more firmly connected to each other.

[0061] When the fastening part 114 connects the electrode collectors 101, 102 and the electrode lead 113, it penetrates all of the first electrode foils 1011, 1021, the electrode insulating layers 1013, 1023, and the second electrode foils 1012, 1022 of the electrode collectors 101, 102. The fastening part 114 is made of a conductive material and can be electrically conductive. Thus, electricity generated in the first electrode foils 1011, 1021 is supplied to the outside via the directly connected electrode lead 113, and electricity generated in the second electrode foils 1012, 1022 can be supplied to the outside after being transferred to the electrode lead 113 via the conductive fastening part 114. Thus, electricity generated inside the electrode assembly 11 can be fully supplied to the outside with only one electrode lead 113.

[0062] FIG. 9 is a schematic side view showing electrode leads 113 connected to uncoated portions 111, 112 of positive electrode foils 1011, 1012 and negative electrode foils 1021, 1022 according to another embodiment of the present invention.

[0063] According to one embodiment of the present invention, the fastening portion 114 is a rivet, but according to another embodiment of the present invention, the fastening portion 114a is a screw. Thus, the electrode collectors 101, 102 and the electrode lead 113 may be connected by screw connection using a screw. In this case, the electrode collectors 101, 102 and the electrode lead 113 may be separately drilled and then the screw may be connected. If a drilling operation for forming a thread is performed, the connection may be achieved by inserting only a bolt into the through hole. However, if a drilling operation without forming a thread is performed, a bolt may be inserted from one side of the through hole and then a nut may be fastened to the end of the bolt protruding from the other side. In this case, the screw may not have a sharp end. However, without being limited thereto, the screw may be directly rotated and inserted immediately while a drilling operation for forming a thread is performed on the electrode collectors 101, 102 and the electrode lead 113. In this case, the screw must have a sharp end. When the electrode current collectors 101, 102 and the electrode lead 113 are screwed together, the threads formed in the through holes are coupled with the threads of the screws themselves, so that the screws can be fixed so as not to come off to the outside.

[0064] A person having ordinary skill in the art to which the present invention pertains can understand that the present invention can be implemented in other specific forms without changing its technical idea or essential features. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and are not limiting. The scope of the present invention is defined by the claims below rather than the above detailed description, and various embodiments derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. [Explanation of symbols]

[0065] 1. Cylindrical secondary battery 2. Welding 11 Jelly roll type electrode assembly 12 Cylindrical battery can 13 Cap assembly 14 Beading section 15 Crimping section 16 Upper insulation plate 101 Positive electrode current collector 102 Negative electrode current collector 111 Positive electrode uncoated area 112 Negative electrode uncoated area 113 Electrode Lead 114 Fastening Part 131 Top Cap 132 PTC element 133 Safety Vent 134 CID gasket 135 CID Filter 136 Crimping Gasket 1011 1st positive foil 1012 2nd positive foil 1013 Positive electrode insulating layer 1021 1st negative electrode foil 1022 2nd negative electrode foil 1023 Negative electrode insulating layer 1131 Positive lead 1132 Negative lead 1311 Gas hole 1331 Periphery

Claims

1. manufacturing an electrode by applying an electrode active material to at least a portion of an electrode current collector formed by sequentially stacking a first electrode foil, an electrode insulating layer, and a second electrode foil; laminating the electrodes and separator; and connecting an electrode lead to a non-coated portion of the electrode current collector on which the electrode active material is not applied, The step of connecting the electrode leads includes connecting the electrode current collector and the electrode lead to each other by a fastening portion penetrating both the electrode current collector and the electrode lead, The fastening portion is coupled along a longitudinal direction of the electrode lead, In the step of connecting the electrode lead, the fastening portion penetrates through all of the first electrode foil, the electrode insulating layer, and the second electrode foil of the electrode current collector; The fastening portion is a rivet, and the electrode current collector and the electrode lead are drilled and riveted at the same time using a rivet gun.

2. The method for manufacturing an electrode assembly according to claim 1 , wherein in the step of connecting the electrode lead, the fastening portion is made of a conductive material.

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