Electrode tab and method for cutting electrode tab

Abstract

The electrode tab cutting method according to the present invention is a method for cutting an electrode tab protruding from an electrode, comprising: a contacting step of contacting a receiving part with the electrode tab so that the receiving part supports one side of the electrode tab; and a cutting step of applying pressure to the electrode tab with a cutting knife so that pressure is applied to the other side of the electrode tab, and cutting the electrode tab with the cutting knife, wherein the cutting knife advances so that an acute angle is formed between the cutting knife and the electrode tab. The electrode tab cut by the cutting method according to the present invention is an electrode tab protruding from an electrode and having one flat side and another side parallel to the one side, with one end connected to the one side and the other end connected to the other side, and the cut surface is formed having an inclined surface such that an acute angle is formed with either the one side or the other side.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0108326 dated August 17, 2021, and all contents disclosed in the documents of this Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a cutting method for cutting an electrode tab protruding from an electrode, and more particularly to a cutting method for an electrode tab in which the cut end is formed as thin as possible to prevent cracks from occurring at the cut surface and to achieve close contact with an electrode lead at the contact surface, and to an electrode tab cut by the cutting method. [Background technology]

[0003] Batteries that store electrical energy are generally classified as primary batteries and secondary batteries. Primary batteries are disposable, consumable batteries, while secondary batteries are rechargeable batteries manufactured using materials that can undergo repeated oxidation and reduction processes between electric current and materials. That is, when a reduction reaction occurs on a material due to electric current, the power source is charged, and when an oxidation reaction occurs on the material, the power source is discharged. Electricity is generated through repeated charge-discharge cycles.

[0004] Generally, types of secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, lithium-ion polymer batteries, etc. These secondary batteries are used not only in small products such as digital cameras, DVD players, MP3 players, mobile phones, PDAs, portable game devices, power tools, and electric bicycles, but also in large products that require high output such as electric vehicles and hybrid vehicles, as well as in power storage devices and backup power storage devices that store surplus generated power and renewable energy.

[0005] Among these, lithium secondary batteries are generally formed by stacking a cathode, a separator, and an anode. The materials for these are selected in consideration of battery life, charge / discharge capacity, temperature characteristics, stability, etc. Charging and discharging of lithium secondary batteries proceeds as lithium ions are repeatedly intercalated and deintercalated from the lithium metal oxide of the cathode to the anode.

[0006] Generally, a secondary battery is manufactured by housing an electrode assembly, in which a positive electrode, a separator, and a negative electrode are repeatedly stacked, in a case such as a cylindrical can or a square pouch.

[0007] Meanwhile, the positive and negative electrodes are manufactured by processing a metal current collector (e.g., copper for the negative electrode and aluminum for the positive electrode) to a predetermined size, and then coating the surface with positive electrode slurry or negative electrode slurry, respectively, except for a portion of the end.

[0008] In this case, the uncoated portion of the current collector where the positive electrode slurry or the negative electrode slurry is not applied is processed into an electrode tab (a positive electrode tab for the positive electrode, and a negative electrode tab for the negative electrode) that serves as a path for current to flow to the outside, or an electrode tab is provided by additionally welding a separate tab made of nickel or the like to the uncoated portion.

[0009] Among the various types of secondary batteries, the wound (jelly roll) electrode assembly 3 inserted into a cylindrical can is manufactured by cutting the negative electrode, positive electrode, and separator to the required width and length, laminating the separator between the negative electrode and positive electrode, and then winding it into a spiral.

[0010] Referring to FIG. 1a, which shows a longitudinal cross-sectional view of a cylindrical secondary battery and an exploded view of the electrode assembly and top cap in a can, electrode tabs 10 (for reference, in FIG. 1a, the one protruding from the upper end is a positive electrode tab, and the one protruding from the lower end is a negative electrode tab) of the electrode assembly 3 are cut off so that the electrode tabs can be welded to the can 1 or top cap 2 before the electrode assembly 3 is mounted in the can 1.

[0011] However, as shown in FIG. 1b, which shows a state in which burrs b are generated at the cut portion when an electrode tab is cut according to a conventional method, the conventional knife 4 applies pressure from above downward to perform the cutting, which causes the cut surface of the electrode tab 10 to deform downward, resulting in problems such as burrs b and / or deformation. As a result, the electrode lead cannot be tightly welded, causing lifting or gaps at the welded portion (see FIG. 6). Alternatively, charging and discharging may occur in a state in which abrupt steps are generated on the surface of the electrode lead 40, which causes repeated heating and cooling, resulting in cracks. Summary of the Invention [Problem to be solved by the invention]

[0012] Therefore, a main object of the present invention is to provide a method for cutting an electrode tab, which can prevent the occurrence of steps and deformation at the cut portion, suppress the occurrence of burrs, and ensure close contact with the electrode lead, in order to solve the problems that occur in the conventional cutting methods, and to provide an electrode tab cut by the cutting method. [Means for solving the problem]

[0013] To achieve the above-mentioned object, an electrode tab cutting method according to the present invention is a method for cutting an electrode tab (positive electrode tab or negative electrode tab) protruding from an electrode (positive electrode or negative electrode), and includes: a contacting step of contacting a receiving part with the electrode tab so that the receiving part supports one side of the electrode tab; and a cutting step of applying pressure to the electrode tab with a cutting knife so that pressure is applied to the other side of the electrode tab, thereby cutting the electrode tab; wherein the cutting knife is inserted so that an acute angle is formed between the cutting knife and the electrode tab.

[0014] The acute angle formed between the cutting knife and the electrode tab during the cutting step is set to 10° to 80°.

[0015] The cutting knife has a terminal end formed so that one surface is a flat surface extending along the longitudinal direction and the other surface has an inclined surface.

[0016] At this time, the cutting knife is advanced with its inclined surface facing the electrode tab.

[0017] In the cutting step, the cutting knife may descend vertically and the receiving portion may be arranged at an angle so that the electrode tabs are inclined, or the receiving portion may be arranged flat so that the electrode tabs are placed horizontally and the cutting knife may slide in an inclined state.

[0018] The cutting knife is made of a metal material having a greater hardness than the electrode tab, and the receiving part is made of a material that does not undergo elastic deformation when the cutting knife presses the electrode tab.

[0019] The present invention also provides an electrode tab cut by the above-described cutting method.

[0020] The electrode tab according to the present invention is an electrode tab that protrudes from an electrode and has one flat side and another side parallel to the one side, and has a cut surface where one end is connected to the one side and the other end is connected to the other side, and the cut surface is formed with an inclined surface so that an acute angle is formed with either the one side or the other side.

[0021] The angle between one of the side surfaces and the inclined surface on the cut surface is 10° to 80°.

[0022] Meanwhile, in the present invention, the electrode may be a negative electrode, and the electrode tab may be a negative electrode tab provided on the negative electrode. [Effects of the Invention]

[0023] The electrode tab cutting method according to the present invention as described above can remove burrs that are generated in conventional cutting methods by cutting so that the angle formed between the cutting knife and the electrode tab is acute.

[0024] As a result, the cut portion is formed into an inclined surface, but the surface that comes into contact with the electrode lead is formed into a flat surface. This makes it possible to prevent lifting and gaps that occur at the contact surface when the electrode tab and the electrode lead are welded, and also to prevent cracks that occur at the portion where burrs are formed and short circuits caused by the cracks. [Brief explanation of the drawings]

[0025] [Figure 1a] 1A and 1B are longitudinal cross-sectional views of a cylindrical secondary battery and a view showing a state in which an electrode assembly and a top cap are disassembled in a can. [Figure 1b] FIG. 10 is a diagram showing a state in which burrs (b) are generated at the cut portion when an electrode tab is cut according to a conventional method. [Figure 2] 10 is a view showing a cutting knife sliding vertically while cutting an electrode tab in accordance with the method of cutting an electrode tab according to the present invention; FIG. [Figure 3]10 is a view showing a state in which the cutting knife slides in an inclined direction while cutting the electrode tab by the electrode tab cutting method according to the present invention; FIG. [Figure 4] FIG. 10 is a side view of a cut electrode tab. [Figure 5] 1A is a diagram showing a state in which an electrode tab cut by the cutting method according to the present invention is joined to an electrode lead, and FIG. 1B is a diagram showing a state in which an electrode tab cut by the conventional cutting method is joined to an electrode lead. DETAILED DESCRIPTION OF THE INVENTION

[0026] DETAILED DESCRIPTION OF THE INVENTION The present invention will now be described in detail with reference to the accompanying drawings so that those skilled in the art can easily practice the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments set forth herein.

[0027] In order to clearly explain the present invention, parts that are not relevant to the description will be omitted, and the same reference numerals will be used throughout the specification to refer to the same or similar components.

[0028] Furthermore, the terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted as meanings and concepts that are consistent with the technical idea of the present invention, in accordance with the principle that an inventor can appropriately define the concepts of terms in order to best explain his or her invention.

[0029] The present invention relates to an electrode tab cutting method for cutting an electrode tab (negative electrode tab or positive electrode tab) protruding from one or both sides of an electrode (negative electrode or positive electrode) before welding the electrode tab to an electrode lead (positive electrode lead or negative electrode lead), and an electrode tab cut by the cutting method. Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0030] First embodiment FIG. 2 is a diagram showing how the cutting knife slides vertically while cutting an electrode tab using the electrode tab cutting method according to the present invention, and FIG. 3 is a diagram showing how the cutting knife slides in an inclined direction.

[0031] Referring to Figures 2 and 3, the present invention provides, as a first embodiment, a method for cutting an electrode tab 10, in which the electrode tab 10 is cut before being welded to an electrode lead 40. The cutting method provided in this embodiment is characterized in that a cutting knife 20 for cutting the electrode tab 10 approaches the electrode tab 10 at an angle relative to the electrode tab 10 to perform the cutting.

[0032] More specifically, the process includes a contact step in which the receiving portion 30 is brought into close contact with the electrode tab 10 so that the receiving portion 30 supports one side 10b (see FIG. 4) of the electrode tab 10, and a cutting step in which the cutting knife 20 presses and cuts the electrode tab 10 so that pressure is applied to the other side 10a of the electrode tab 10.

[0033] In this case, the cutting knife 20 provided in the present invention is made of a metal material having a greater hardness than the electrode tab 10, and the receiving part 30 is made of a material that does not undergo elastic deformation when the cutting knife 20 presses the electrode tab 10.

[0034] The cutting knife 20 has a terminal end formed to have a flat surface 20a extending along the longitudinal direction on one side and an inclined surface 20b on the other side.

[0035] Furthermore, when cutting the electrode tab 10, the cutting knife 20 advances so that the angle formed between the cutting knife 20 and the electrode tab 10 is an acute angle, for example, the angle d between the cutting knife 20 and the electrode tab 10 is 10° to 80°.

[0036] At this time, as shown in Figures 2 and 3, the cutting knife 20 is inserted with the inclined surface 20b positioned close to the electrode tab 10 so that the end of the electrode tab 10 has a sharp shape.

[0037] The cleavage step provided in this embodiment may be performed in two ways.

[0038] 2, in the cutting step, the cutting knife 20 descends vertically, and the receiving part 30 may be disposed at an angle so that the electrode tab 10 is inclined. In this case, the angle c formed by the receiving part 30 and the ground may be set in the range of 10 to 80 degrees, but is preferably set to 50 degrees or less to prevent slippage between the cutting knife 20 and the electrode tab 10.

[0039] Meanwhile, in order to fix the movement of the electrode tab 10 as it tilts, temporary adhesion may be applied partially or entirely to the surface where the receiving part 30 and the electrode tab 10 come into contact. That is, before the electrode tab 10 is placed on the receiving part 30, an adhesive or the like may be applied, and the electrode tab 10 may be temporarily adhered and fixed so that it is not pushed out when the cutting knife 20 applies pressure to cut it. In this case, the adhesive strength of the temporary fixation may be determined to a degree that allows easy separation after the electrode tab 10 is cut. In addition, a material with high frictional force may be selectively attached or coated on the surface of the receiving part 30 to prevent the electrode tab 10 from being pushed out.

[0040] 3, in the cutting step, the receiving part 30 may be positioned flat so that the electrode tab 10 is placed horizontally, and the cutting knife 20 may slide in an inclined state. In this case, since the angle formed by the receiving part 30 and the ground is 0°, it is preferable that the angle d between the cutting knife 20 and the electrode tab 10 is formed in the range of 10° to 80°.

[0041] Second embodiment FIG. 4 is a diagram showing a side view of a cut electrode tab 10, and FIG. 5 is a diagram showing (a) an electrode tab 10 cut by the cutting method according to the present invention joined to an electrode lead 40, and (b) an electrode tab cut by a conventional cutting method joined to an electrode lead 40.

[0042] The present invention provides, as a second embodiment, an electrode tab 10 cut by the cutting method provided in the first embodiment.

[0043] The electrode tab 10 according to the present invention protrudes from one or both sides of an electrode (not shown) (a positive electrode tab or a negative electrode tab protrudes from the positive electrode or the negative electrode, respectively), and has one flat side surface 10b and another side surface 10a parallel to the one side surface 10b.

[0044] The electrode tab 10 is cut before being welded in a state of surface contact with the electrode lead 40. At this time, one end (the lower end of the left end in FIG. 4) is connected to one side surface (the lower surface in FIG. 4), and the other end (the upper end of the left end in FIG. 4) has a cut surface 11 that is connected to the other side surface (the upper surface in FIG. 4).

[0045] The cut surface 11 is formed to have an inclined surface so that an acute angle is formed with either one of the side surfaces 10b or the other side surface 10a. For example, as shown in Figure 4, the angle between the inclined surface and the bottom surface is formed in the range of 10° to 80°, and the bottom end protrudes further than the top end so that the cross section of the end 10c has an angle shape.

[0046] In this case, in the present invention, the electrode may be a negative electrode and the electrode tab may be a negative electrode tab provided on the negative electrode, or the electrode may be a positive electrode and the electrode tab may be a positive electrode tab provided on the positive electrode.

[0047] 5, welding is performed with the lower surface in close contact with the upper surface of the electrode lead 40.

[0048] Therefore, while electrode tabs cut using conventional methods have burrs at the ends, causing lifting or gaps, the electrode tab 10 of the present invention (because no burrs or deformation occur) can be welded in a state of close contact with the electrode lead 40. This allows for more stable welding and reduces defects such as cracks.

[0049] The method of cutting the electrode tab 10 according to the present invention as described above can remove burrs that would have been generated in the conventional cutting method by cutting the electrode tab 10 at an acute angle between the cutting knife 20 and the electrode tab 10.

[0050] As a result, the cut portion is formed with an inclined surface, but the surface that comes into contact with the electrode lead is formed flat, so that lifting and gaps that occur at the contact surface when the electrode tab and the electrode lead are welded can be suppressed, and cracks that occur at the portion where burrs are formed and short circuits caused by the cracks can be suppressed.

[0051] Although the present invention has been described above using limited embodiments and drawings, the present invention is not limited thereto, and various embodiments can be made by a person having ordinary skill in the art to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims set forth below. [Explanation of symbols]

[0052] 10: Electrode tab 11: Inclined surface 20: Cutting knife 30: Receiving part 40: Electrode lead

Claims

1. 1. A method for cutting an electrode tab protruding from an electrode, comprising: a step of closely fitting the receiving portion to the electrode tab so that the receiving portion supports one side of the electrode tab; and a cutting step in which a cutting knife presses and cuts the electrode tab so that pressure is applied to the other side of the electrode tab; The end of the cutting knife has one surface that is a flat surface extending along the longitudinal direction and the other surface that has an inclined surface, The cutting knife is inserted so that an acute angle is formed between the cutting knife and the electrode tab, The cutting knife is inserted with its inclined surface facing the electrode tab.

2. 2. The method of claim 1, wherein the acute angle formed between the cutting knife and the electrode tab in the cutting step is set to 10 to 80 degrees.

3. 2. The method of claim 1, wherein in the cutting step, the cutting knife descends vertically and the receiving portion is inclined so that the electrode tab is inclined.

4. 2. The method of claim 1, wherein, in the cutting step, the receiving portion is positioned flat so that the electrode tab is placed horizontally, and the cutting knife slides in an inclined state.

5. The cutting knife is made of a metal material having a hardness greater than that of the electrode tab, 2. The method of claim 1, wherein the receiving portion is made of a material that does not undergo elastic deformation when the cutting knife presses the electrode tab.

6. an electrode tab protruding from the electrode and having one flat side and another side parallel to the one side, One end has a cut surface connected to one side surface and the other end has a cut surface connected to the other side surface, The cut surface is formed to have an inclined surface so that an included angle with either one of the side surfaces is an acute angle, The electrode tab is characterized in that the side of the one side and the other side that forms an acute angle with the cut surface contacts the electrode lead.

7. The electrode tab according to claim 6, wherein an included angle between one of the side surfaces and the inclined surface in the cut surface is 10 to 80 degrees.

8. The electrode tab according to claim 6 , wherein the electrode is a negative electrode, and the electrode tab is a negative electrode tab provided on the negative electrode.

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