Electrodes for secondary batteries and methods for manufacturing the same

Abstract

According to one embodiment of the present invention, an electrode for a secondary battery includes an electrode collector including a coating portion, a first active material layer positioned on the coating portion, and an electrode tab electrically connected to the electrode collector, the electrode tab being positioned on one side of the electrode collector, with at least one hole formed in the electrode tab, and an extension of the electrode tab extending through the hole contacting the electrode collector.

Description

Technical Field

[0001] Cross - reference to related applications This application claims the benefit of priority based on Korean Patent Application No. 10 - 2020 - 0160316, filed on November 25, 2020, and all the contents disclosed in the literature of the Korean patent application are incorporated herein by reference.

[0002] The present invention relates to an electrode for a secondary battery and a method for manufacturing the same, and more specifically, to an electrode for a secondary battery in which the efficiency of the electrode process is improved and the electrode capacity is increased, and a method for manufacturing the same.

Background Art

[0003] As the technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source has been rapidly increasing. Among such secondary batteries, lithium secondary batteries having a high energy density, voltage, long cycle life, and low self - discharge rate have been commercialized and widely used.

[0004] Particularly, secondary batteries have received much attention not only as an energy source for mobile devices such as mobile phones, digital cameras, notebook computers, wearable devices, etc., but also as an energy source for power devices such as electric bicycles, electric vehicles, and hybrid electric vehicles.

[0005] A secondary battery can be formed by inserting an electrode assembly composed of a positive electrode, a negative electrode, and a separator into a case and then sealing it. Here, an electrode for a secondary battery such as a positive electrode or a negative electrode includes a coated portion and an uncoated portion on a current collector. The coated portion corresponds to a grounded portion on which an active material layer coated with an active material slurry is formed, and the uncoated portion corresponds to an ungrounded portion on which the active material slurry is not coated.

[0006] FIG. 1 is a plan view schematically showing a conventional electrode for a secondary battery. FIG. 2 is a cross - sectional view of the electrode for a secondary battery of FIG. 1.

[0007] Referring to Figures 1 and 2, a conventional secondary battery electrode 10 includes an electrode current collector 60 and an active material layer 70 located on the electrode current collector 60. The active material layer 70 can be composed of an electrode mixture containing an electrode active material, a binder, a conductive material, etc. In the electrode 10, an ultrasonic fusion portion 15 is formed on the plain portion of the electrode current collector 60 through an ultrasonic fusion method, thereby allowing the electrode tap 50 to be attached to the electrode current collector 60. The electrode current collector 60 includes a coated portion 30 on which the active material layer 70 is formed and an uncoated portion 40 on which the active material layer 70 is not formed. In this case, the electrode tap 50 can be fused onto the uncoated portion 40. That is, the uncoated portion 40 is necessary for the fusion of the electrode tap 50 in a conventional secondary battery electrode 10.

[0008] However, the formation of the uncoated portion 40 reduces the area of ​​the coated portion 30 to which the active material layer 70 is coated, leading to a decrease in electrode capacity. In particular, in the case of ultra-small secondary batteries, although the overall volume of the secondary battery is reduced significantly, there is a limit to the reduction in the volume of the uncoated portion 40 in order to secure space for electrode tap 50 fusion, resulting in a large loss of electrode capacity. Furthermore, although a pattern coating method is used to form the coated portion 30 and the uncoated portion 40, the implementation of this pattern coating method can sometimes lead to problems such as uneven slurry loading.

[0009] This necessitates the development of electrodes to reduce the problems associated with the formation of blank areas for electrode tap 50 fusion in conventional secondary battery electrodes 10. [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] The problem that this invention aims to solve is to provide an electrode for a secondary battery and a method for manufacturing the same, in which the efficiency of the electrode process is improved and the capacity is increased.

[0011] However, the problems that the embodiments of the present invention aim to solve are not limited to those described above, and can be broadly extended within the scope of the technical ideas included in the present invention. [Means for solving the problem]

[0012] An electrode for a secondary battery according to one embodiment of the present invention includes an electrode current collector including a coated portion; a first active material layer located on the coated portion; and an electrode tap electrically connected to the electrode current collector, wherein the electrode tap is located on one surface of the electrode current collector, at least one hole is formed in the electrode tap, and an extension of the electrode tap extending through the hole is in contact with the electrode current collector.

[0013] The extension of the electrode tap may be in contact with the side surface of the electrode current collector exposed by the hole.

[0014] The electrode tap may be arranged on the first active material layer while superimposing it with the first active material layer.

[0015] The electrode current collector has an upper surface on which the first active material layer is located and a bottom surface located on the opposite side of the upper surface, and the extension of the electrode tap can be bent so as to overlap with the bottom surface of the electrode current collector to form an electrode tap fixing portion.

[0016] The electrode current collector further includes a second active material layer located on its bottom surface, and the electrode tap fixing portion may be in contact with the second active material layer.

[0017] The electrode current collector may further include an uncoated portion formed on the same surface as one surface on which the coated portion is formed, and the electrode tap may be arranged on the uncoated portion while overlapping with the uncoated portion.

[0018] The electrode current collector has an upper surface on which the first active material layer is located and a bottom surface located on the opposite side of the upper surface, and the electrode tap may be in contact with the upper surface of the electrode current collector at the uncoated portion.

[0019] The extension of the electrode tab can be bent so as to overlap with the bottom surface of the electrode current collector to form an electrode tab fixing portion.

[0020] The width of the uncoated portion may be shorter than the width of the coated portion.

[0021] A method for manufacturing an electrode for a secondary battery according to another embodiment of the present invention includes a step of arranging an electrode tab so as to overlap on an electrode current collector, a step of forming at least one hole passing through the electrode tab and the electrode current collector, a step of pressurizing at least one of the upper and lower portions of the electrode including the electrode current collector, and a step of bending the extension of the electrode tab extended along the inner wall of the hole so as to overlap with the bottom surface of the electrode current collector to form an electrode tab fixing portion.

[0022] The method may further include a step of forming a notch or a slit in the electrode tab portion where the hole is to be formed before forming the hole in the electrode tab.

[0023] The extension of the electrode tab may contact the side surface of the electrode current collector exposed by the hole.

[0024] The step of forming the electrode tab fixing portion may contact the bottom surface of the electrode current collector or the active material layer formed on the bottom surface of the electrode current collector while the remaining trace of the extension of the electrode tab is bent by the pressing force.

[0025] A secondary battery according to another embodiment of the present invention includes the aforementioned electrode for a secondary battery.

Advantages of the Invention

[0026] According to an embodiment of the present invention, by physically fusing an electrode tab having a plurality of holes on a coated portion to an electrode with a strong pressure, the efficiency of the electrode process can be improved and the electrode capacity can be increased.

[0027] The effects of the present invention are not limited to the above-mentioned effects, and the effects not mentioned should be clearly understood by those with ordinary knowledge in the technical field to which the present invention pertains from this specification and the attached drawings.

Brief Description of the Drawings

[0028] [Figure 1] It is a plan view schematically showing a conventional electrode for a secondary battery. [Figure 2] It is a cross-sectional view taken along the cutting line A-A of FIG. 1. [Figure 3] It is a plan view of an electrode for a secondary battery according to an embodiment of the present invention. [Figure 4] It is a cross-sectional view taken along the cutting line B-B of FIG. 3. [Figure 5] It is a diagram showing a manufacturing method of an electrode for a secondary battery according to another embodiment of the present invention. [Figure 6] It is a diagram showing a manufacturing method of an electrode for a secondary battery according to another embodiment of the present invention. [Figure 7] It is a diagram showing a manufacturing method of an electrode for a secondary battery according to another embodiment of the present invention. [Figure 8] It is a plan view showing the state around a hole when viewed from the bottom surface of the electrode current collector of the electrode for a secondary battery of FIG. 7. [Figure 9] It is a plan view of an electrode for a secondary battery according to another embodiment of the present invention. [Figure 10] It is a cross-sectional view taken along the cutting line C-C of FIG. 9.

Modes for Carrying Out the Invention

[0029] Hereinafter, with reference to the attached drawings, various embodiments of the present invention will be described in detail so that those with ordinary knowledge in the technical field to which the present invention pertains can easily implement them. The present invention can be realized in various different forms and is not limited to the embodiments described here.

[0030] To clearly explain the present invention, unnecessary explanatory parts have been omitted, and the same or similar components are given the same reference numerals throughout the specification.

[0031] Furthermore, the dimensions and thicknesses of each component shown in the drawings are arbitrary for the sake of explanation, and therefore the present invention is not necessarily limited to what is shown. In the drawings, the thicknesses are shown enlarged to clearly represent various layers and regions. Also, in the drawings, the thicknesses of some layers and regions are shown in an exaggerated manner for the sake of explanation.

[0032] Furthermore, when a part such as a layer, membrane, region, or plate is said to be "on top of" or "on" another part, this includes not only the case where it is directly "on top of" the other part, but also the case where there is another part in between. Conversely, when a part is said to be "directly "on top of" another part, it means that there is no other part in between. Also, being "on top of" or "on" a reference part means being located above or below the reference part, and does not necessarily mean being located "on top of" or "on" in the opposite direction of gravity.

[0033] Furthermore, when a specification states that a certain part "includes" a certain component, unless otherwise stated, this means that it may include other components rather than excluding them.

[0034] Furthermore, throughout the specification, "on a plane" means when the subject is viewed from above, and "on a cross-section" means when the subject is viewed from the side of a cross-section obtained by cutting the subject perpendicularly.

[0035] The following describes an electrode for a secondary battery according to one embodiment of the present invention. However, although the electrode is described here with reference to the upper surface of the current collector, it is not necessarily limited to this, and the case of the lower surface can be described in the same or similar manner.

[0036] The following describes in detail the configurations of the electrode 100 for a secondary battery according to one embodiment of this application. However, although the description here is based on the case where the electrode 100 is a positive electrode, it is not necessarily limited to this, and the case of a negative electrode can be described in the same or similar terms.

[0037] Figure 3 is a plan view of an electrode for a secondary battery according to one embodiment of the present invention. Figure 4 is a cross-sectional view taken along the cutting line BB in Figure 1.

[0038] Referring to Figures 3 and 4, an electrode 100 for a secondary battery according to one embodiment of the present invention includes an electrode current collector 110, an active material layer 200, and an electrode tap 300.

[0039] The active material layer 200 can be coated on the coating portion 130 of the electrode current collector 110 in the form of an electrode slurry. The electrode slurry is a mixture formed by mixing fine solid particles in a liquid to create a state with low fluidity. By mixing a binder in a solvent at a certain ratio, the electrode slurry can be coated onto the electrode current collector as a thin film, and through drying and crimping processes, electrodes for a secondary battery can be formed.

[0040] The active material layer 200 can be placed on at least one of the upper or lower surfaces of the electrode current collector 110.

[0041] In this embodiment, the electrode current collector 110 may consist only of the coated portion 130. Here, the coated portion 130 of the electrode current collector 110 may be the region to which the electrode composition is coated. Generally, an electrode slurry can be manufactured by applying a positive electrode mixture containing a mixture of active material, conductive material, and binder to the remaining portion of the electrode current collector 110, excluding the plain portion where the electrode taps are formed, and then drying and pressing it. If necessary, fillers can be further added to the mixture.

[0042] However, according to this embodiment, by forming an active material layer 200 on one or both sides of the electrode current collector 110 without forming a blank area, the electrode tap 300 can be directly fused onto the area that is not blank. In other words, the electrode tap 300 can be fused onto the active material layer 200.

[0043] Furthermore, the electrode current collector 110 is not particularly limited as long as it has high conductivity without inducing chemical changes in the battery. For example, among the electrode current collectors, the positive electrode current collector is not particularly limited as long as it has high conductivity without inducing chemical changes in the electrodes for the secondary battery according to this embodiment. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surfaces treated with carbon, nickel, titanium, silver, etc., can be used. Fine irregularities can also be formed on the surface of the positive electrode current collector to increase the bonding strength of the positive electrode active material, and the positive electrode current collector can have a variety of forms such as film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0044] Among the electrode current collectors, the negative electrode current collector is not particularly limited as long as it has high conductivity without inducing chemical changes in the electrodes for the secondary battery according to this embodiment. For example, copper, stainless steel, aluminum-cadmium alloy, etc., can be used. Also, similar to the positive electrode current collector, fine irregularities can be formed on the surface to strengthen the bonding force of the negative electrode active material, and the negative electrode current collector can have a variety of forms such as film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0045] The electrode tap 300 according to this embodiment can be physically fused to the electrode current collector 110. Specifically, at least one hole 300h is formed in the secondary battery electrode 100, and the electrode tap 300 on the active material layer 200 is extended along the inner wall of the hole 300h. At this time, the extended portion of the electrode tap 300 will come into contact with the side surface of the electrode current collector 110 that is exposed by the hole 300h. The extended portion of the electrode tap 300 will come into contact with the bottom surface of the electrode current collector 110 or the active material layer 200 formed on the bottom surface of the electrode current collector 110 on the opposite side of the fusion surface of the electrode tap 300.

[0046] A method for manufacturing electrodes for secondary batteries according to another embodiment of the present invention will be described below with reference to Figure 5.

[0047] Figures 5 to 7 show a method for manufacturing an electrode for a secondary battery according to another embodiment of the present invention. Figure 8 is a plan view of the secondary battery electrode of Figure 7, showing the area around the hole as seen from the bottom surface of the electrode current collector.

[0048] Referring to Figure 5, the electrode tap 300 can be superimposed and placed on the active material layer 200 to be fused. Subsequently, a notch or break 300p can be formed in the portion of the electrode tap 300 where a hole is to be formed.

[0049] Referring to Figure 6, at least one hole 300h can be formed in the electrode for the secondary battery when the active material layer 200 and the electrode tap 300 are superimposed. In this case, the hole 300h can be formed by applying pressure using a pin after forming the notch or break 300p in the electrode tap 300 portion, but the method is not limited to this.

[0050] In the process of forming such a hole 300h, the electrode tap 300 on the active material layer 200 is extended along the inner wall of the hole 300h. The extension 300e of the electrode tap 300 extends not only along the electrode tap 300 but also along the inner wall of the hole 300h, which penetrates the active material layer 200 and the electrode current collector 110.

[0051] Referring to Figure 7, at least one of the upper and lower parts of the secondary battery electrode can be pressurized so that the electrode tap 300 is physically fused to the active material layer 200 and the electrode current collector 110. At this time, the force from the pressurization causes the remnant of the extension 300e of the electrode tap 300 to bend and come into contact with the bottom surface of the electrode current collector 110 or the active material layer 200' formed on the bottom surface of the electrode current collector 110. Specifically, the extension 300e of the electrode tap 300 is bent after passing through the hole 300h, so that an electrode tap 300 fixing part 300c can be formed on the bottom surface of the electrode current collector 110 or the active material layer 200' formed on the bottom surface of the electrode current collector 110. That is, the electrode tap 300 passes through the hole 300h and has a structure that surrounds the active material layer 200, 200' and the electrode current collector 110, so that the electrode tap 300 is fixed and in contact with the electrode current collector 110. In the aforementioned fixing case, the fixing may include, but is not limited to, a fixing plate (not shown) that is coupled to the hole 300h while in contact with the electrode tap fixing portion 300c.

[0052] Referring to Figure 8, when viewed from the opposite side of the fusion surface of the electrode tap 300, the area around the hole 300h will be bent to form the electrode tap fixing portion 300c, while clip-shaped fusion occurs.

[0053] Multiple holes 300h can be formed in various sizes or shapes. For example, multiple holes 300h can be formed in circular, square, triangular, rhombus, or trapezoidal shapes, and the sizes of the multiple holes 300h may be the same or different.

[0054] This enables physical fusion of the electrode current collector 110 and the electrode tap 300, rather than using ultrasonic fusion, and allows for the fusion of the electrode tap 300 even without a blank area. The size and number of holes 300h are not limited, but a smaller and more numerous hole 300h may be advantageous in terms of resistance because it increases the current path.

[0055] Figure 9 is a plan view of an electrode for a secondary battery according to another embodiment of the present invention. Figure 10 is a cross-sectional view taken along the cutting line CC in Figure 9.

[0056] Referring to Figures 9 and 10, the electrode current collector 110 in this embodiment includes a coated portion 130 and an uncoated portion 140. Here, the uncoated portion 140 of the electrode current collector 110 is the portion on which the active material layer 200 is not formed. The uncoated portion 140 and the coated portion 130 may be formed on one surface of the electrode current collector 110 by a pattern coating method, or the coated portion 130' may be formed on the other surface of the electrode current collector 110 without an uncoated portion.

[0057] The electrode tap 300 can be placed on the uncoated portion 140 of the electrode current collector 110. Alternatively, the electrode tap 300 can be fused to the electrode current collector 110 on the uncoated portion 140 and fixed to the electrode current collector 110.

[0058] The fusion of the electrode tap 300 according to this embodiment may be the same as the method described in the embodiments of Figures 5 to 7. In other words, after forming multiple holes in the electrode tap 300 while it is superimposed on the uncoated portion 140, the extension of the electrode tap 300 penetrates the holes by pressurization. The remaining trace of the electrode tap 300 is then bent into a clip shape, fixing and fusing the electrode tap 300 to the bottom surface of the electrode current collector 110 or to the active material layer 200' formed on the bottom surface of the electrode current collector 110.

[0059] According to this embodiment, the electrode tap 300 can form a plain area only in the fusion portion, thereby increasing the contact area for current flow.

[0060] The width of the uncoated portion 140 formed on one surface of the electrode current collector 110 is shorter than the width of the coated portion 130 on one surface or the coated portion 130' on the other surface. The shorter the width of the uncoated portion 140, the greater the electrode capacity, which can eliminate the non-uniformity problem that occurs during the patterning process.

[0061] However, the width and length of the uncoated portion 140 are not limited to those described above; they can be formed to various lengths as long as they provide sufficient width to improve electrode performance.

[0062] The secondary battery electrodes described above can be applied to a variety of secondary batteries. Such secondary batteries include cylindrical batteries in which the electrode assembly is housed in a cylindrical metal can, rectangular batteries in which the electrode assembly is housed in a rectangular metal can, and pouch-type batteries in which the electrode assembly is housed in a pouch-type case made of aluminum laminate sheet. However, the present invention is not limited to these, and can be applied to a variety of secondary batteries in which secondary battery electrodes are used, and this also falls within the scope of the present invention.

[0063] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto. Various modifications and improvements by those skilled in the art, using the basic concepts of the present invention as defined in the following claims, also fall within the scope of the present invention. [Explanation of symbols]

[0064] 100: Electrode for secondary batteries 110: Electrode current collector 130: Coating part 140: Uncoated area 200: Active material layer 300: Electrode Tap 300h: Hall

Claims

1. Electrode current collector including the coated portion; A first active material layer located on the coating portion; and This includes an electrode tap electrically connected to the electrode current collector (excluding one having a layer made of a non-metallic conductive material on the side facing the first active material layer), The electrode tap is located on one surface of the electrode current collector, and the electrode tap has a plurality of holes formed in the shape of a square, triangle, rhombus, or trapezoid, and the extension of the electrode tap that extends through the holes is in contact with the electrode current collector. The extension of the electrode tap contacts the side surface of the electrode current collector exposed by the hole, The electrode current collector has an upper surface on which the first active material layer is located and a bottom surface located on the opposite side of the upper surface. The electrode tap is located on the first active material layer while overlapping with the first active material layer, and the electrode tap is physically fused to the bottom surface of the electrode current collector in the form of a bent clip, An electrode for a secondary battery, wherein the extension of the electrode tap is bent so as to overlap with the bottom surface of the electrode current collector and come into contact with the bottom surface of the electrode current collector.

2. An electrode current collector with a coated portion on one side and the other side; A first active material layer located on the coating portion; and Includes an electrode tap electrically connected to the electrode current collector, The electrode tap is located on one surface of the electrode current collector, and the electrode tap has a plurality of holes formed in the shape of a square, triangle, rhombus, or trapezoid, and the extension of the electrode tap that extends through the holes is in contact with the electrode current collector. The extension of the electrode tap contacts the side surface of the electrode current collector exposed by the hole, The present invention further includes an uncoated portion formed on the same surface as one surface of the electrode current collector on which the coating portion is formed, The electrode tap is positioned on the uncoated portion while overlapping with the uncoated portion. The electrode tap is physically fused to the electrode current collector on the uncoated portion. An electrode for a secondary battery, wherein the uncoated portion is formed only on the fused portion of the electrode tap.

3. The electrode for a secondary battery according to claim 2, wherein the electrode current collector has an upper surface on which the first active material layer is located and a bottom surface located on the opposite side of the upper surface, and the electrode tap contacts the upper surface of the electrode current collector at the uncoated portion.

4. The electrode for a secondary battery according to claim 3, wherein the extension of the electrode tap is bent so as to overlap with the bottom surface of the electrode current collector to form an electrode tap fixing portion.

5. The electrode for a secondary battery according to any one of claims 2 to 4, wherein the width of the uncoated portion is shorter than the width of the coated portion.

6. In the step of arranging the electrode taps so that they overlap on the electrode current collector, The step of forming at least one hole through which the electrode tap and the electrode current collector pass, A step of pressurizing at least one of the upper and lower parts of the electrode including the electrode current collector, and A method for manufacturing an electrode for a secondary battery according to any one of claims 1 to 5, comprising the step of bending the extension of the electrode tap, which extends along the inner wall of the hole, so as to overlap with the bottom surface of the electrode current collector, in order to form an electrode tap fixing portion.

7. The method for manufacturing an electrode for a secondary battery according to claim 6, further comprising the step of forming a notch or crack in the portion of the electrode tap where the hole is to be formed, prior to forming the hole in the electrode tap.

8. The method for manufacturing an electrode for a secondary battery according to claim 7, wherein the extension of the electrode tap contacts the side surface of the electrode current collector exposed by the hole.

9. The method for manufacturing an electrode for a secondary battery according to any one of claims 6 to 8, wherein the step of forming the electrode tap fixing portion is such that the residual portion of the extension of the electrode tap is bent by the pressurizing force and comes into contact with the bottom surface of the electrode current collector or the active material layer formed on the bottom surface of the electrode current collector.

10. A secondary battery comprising an electrode for a secondary battery as described in any one of claims 1 to 5.

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