Secondary battery electrode and manufacturing method for the same

Abstract

To provide a secondary battery electrode and a manufacturing method for the same.SOLUTION: The electrode includes a substrate, a first composition coated portion containing an active material disposed on one surface of the substrate, and a first uncoated portion disposed on one surface of the substrate, contacting the first composition coated portion, and exposing the substrate. A first side portion of the first composition coated portion contacting the first uncoated portion has a stepped surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an electrode for a secondary battery and a method for manufacturing the same. [Background technology]

[0002] Unlike primary batteries, which cannot be recharged, secondary batteries are batteries that can be charged and discharged. Low-capacity secondary batteries are used in small portable electronic devices such as smartphones, feature phones, laptop computers, digital cameras, and camcorders, while high-capacity secondary batteries are widely used as motor drive power sources and power storage batteries in hybrid vehicles, electric vehicles, and the like. Such secondary batteries include an electrode assembly consisting of a positive electrode and a negative electrode, a case that houses the electrode assembly, and electrode terminals connected to the electrode assembly.

[0003] Electrodes used in secondary batteries are manufactured by coating an active material on a thin metal electrode substrate made of lithium, aluminum, nickel, copper, or the like, followed by drying and rolling. The electrode substrate has a composition-coated portion where the active material is coated and an uncoated portion where the substrate is exposed without the active material. However, shrinkage of the active material and the substrate during the drying process can cause wrinkles in the uncoated portion, which can degrade the quality of the battery.

[0004] The foregoing information disclosed in this Background of the Invention section is intended solely to enhance understanding of the background of the present invention and may therefore include information that does not constitute prior art. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Korean Patent Publication No. 10-2016-0111709 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present disclosure is to provide an electrode for a secondary battery and a method for manufacturing the same that solves the above problems.

[0007] However, the technical problems that the present invention aims to solve are not limited to the problems mentioned above, and other problems not mentioned should be clearly understood by those skilled in the art from the description of the invention described below. [Means for solving the problem]

[0008] According to some embodiments of the present disclosure for solving the technical problem, an electrode includes a substrate, a first composition-coated portion containing an active material and disposed on one side of the substrate, and a first uncoated portion disposed on one side of the substrate, in contact with the first composition-coated portion, and exposing the substrate, and a first side portion of the first composition-coated portion in contact with the first uncoated portion has a stepped surface.

[0009] According to some embodiments of the present disclosure, the first side portion includes a first sidewall formed at a first angle relative to one surface of the substrate and a second sidewall formed at a second angle relative to one surface of the substrate, a step surface connecting the first sidewall and the second sidewall, and the first sidewall contacting the first uncoated portion.

[0010] According to some embodiments of the present disclosure, each of the first angle and the second angle is between 80° and 90°.

[0011] According to some embodiments of the present disclosure, the first angle and the second angle are different from each other.

[0012] According to some embodiments of the present disclosure, the substrate includes a plurality of first uncoated portions.

[0013] According to some embodiments of the present disclosure, the notched first uncoated portion abuts the first side portion of the first composition coated portion.

[0014] According to some embodiments of the present disclosure, the electrode further includes a second composition-coated portion disposed on the other side of the substrate and a second uncoated portion disposed on the other side of the substrate, exposing the substrate, and the second side portion of the second composition-coated portion in contact with the second uncoated portion has a stepped surface.

[0015] According to some embodiments of the present disclosure, the second uncoated portion is formed at a position corresponding to the first uncoated portion.

[0016] According to some embodiments of the present disclosure, a substrate includes a plurality of first uncoated portions and a plurality of second uncoated portions.

[0017] According to some embodiments of the present disclosure for solving a technical problem, an electrode assembly includes a first electrode, a second electrode, and a separator disposed between the first electrode and the second electrode, wherein the first electrode includes a substrate having uncoated portions disposed on both sides thereof, a first composition-coated portion including a first active material disposed on one side of the substrate, and a second composition-coated portion including a second active material disposed on the other side of the substrate, and a first side portion of the first composition-coated portion in contact with the uncoated portion has a stepped surface.

[0018] According to some embodiments of the present disclosure, the second side portion of the second composition-coated portion that contacts the uncoated portion has a stepped surface.

[0019] According to some embodiments of the present disclosure for solving a technical problem, a method for manufacturing an electrode for a secondary battery includes a step of forming a first composition coated portion containing an active material on one surface of a substrate, and a step of etching a first region of the first composition coated portion to form a first uncoated portion that exposes one surface of the substrate, and a side portion of the first composition coated portion that contacts the first uncoated portion has a stepped surface.

[0020] According to some embodiments of the present disclosure, the etching step includes laser etching the first region of the first composition application.

[0021] According to some embodiments of the present disclosure, the etching step includes a first laser etching step of laser etching the first region with a first irradiation area, and a second laser etching step of laser etching the first region with a second irradiation area different from the first irradiation area.

[0022] According to some embodiments of the present disclosure, the first illumination area is smaller than the second illumination area.

[0023] According to some embodiments of the present disclosure, the first illuminated area has a first depth, the second illuminated area has a second depth, and the first depth is greater than the second depth.

[0024] According to some embodiments of the present disclosure, the laser output intensities for the laser etching in the first laser etching step and the second laser etching step are different from each other.

[0025] According to some embodiments of the present disclosure, the etching step includes simultaneously etching a plurality of first regions of the first composition coating.

[0026] According to some embodiments of the present disclosure, the method further includes notching the substrate relative to the first region to form a tap.

[0027] According to some embodiments of the present disclosure, the method further includes the steps of forming a second composition-coated portion containing an active material on the other side of the substrate, and etching a plurality of second regions of the second composition-coated portion to form second uncoated portions that expose the other side of the substrate, wherein the side portion of the second composition-coated portion in contact with the second uncoated portion has a stepped surface, and the second uncoated portion is formed at a position corresponding to the first uncoated portion. [Effects of the Invention]

[0028] According to some embodiments of the present invention, by forming a step at the boundary between the composition-coated portion and the uncoated portion of the electrode where the heat-affected zone is formed by the laser etching process, the contact area between the heat-affected zone of the composition-coated portion and the separator can be increased during the battery assembly process.

[0029] According to some embodiments of the present invention, the flatness of the active material can be maintained at the boundary between the composition-coated portion and the uncoated portion, while the risk of damage to the separator can be reduced.

[0030] However, the effects obtained by the present invention are not limited to the effects described above, and other technical effects not mentioned herein should be clearly understood by those skilled in the art from the description of the invention described below. [Brief explanation of the drawings]

[0031] The following drawings and the like attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention to be given later, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be analyzed by being limited to the matters depicted in such drawings. [Figure 1] 1 is a perspective view illustrating an example of a secondary battery according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram showing a first comparative example of a method for manufacturing an electrode for a secondary battery. [Figure 3] FIG. 2 is an enlarged cross-sectional view of a contact area between a composition-coated portion and an uncoated portion according to a first comparative example. [Figure 4] FIG. 10 is a diagram showing a second comparative example of a method for manufacturing an electrode for a secondary battery. [Figure 5] FIG. 4 is an enlarged cross-sectional view of a contact area between a composition-coated portion and an uncoated portion according to a second comparative example. [Figure 6] FIG. 2 is an enlarged cross-sectional view of a region where a composition-coated portion and an uncoated portion contact each other according to one embodiment of the present disclosure. [Figure 7] FIG. 2 is an enlarged perspective view showing an uncoated portion according to an embodiment of the present disclosure. [Figure 8]1 is a graph showing the thickness of an active material layer depending on the position of a contact area between a composition-coated portion and an uncoated portion according to an example of the present disclosure. [Figure 9] FIG. 10 is an enlarged perspective view showing an uncoated portion according to another embodiment of the present disclosure. [Figure 10] FIG. 10 is an enlarged perspective view showing an uncoated portion according to still another embodiment of the present disclosure. [Figure 11] FIG. 10 is a diagram showing an example in which uncoated portions are formed on both sides of a substrate according to an embodiment of the present disclosure. [Figure 12] FIG. 10 is a diagram showing an example in which a plurality of uncoated portions are formed on one surface of a substrate according to an embodiment of the present disclosure. [Figure 13] 1 is a flowchart illustrating a method for manufacturing an electrode for a secondary battery according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0032] Preferred embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. First, the terms and phrases used in this specification and claims should not be interpreted in a limited manner based on their ordinary and dictionary meanings, but should be interpreted in a manner consistent with the technical concept of the present invention, based on the principle that the inventor may appropriately define the concepts of terms in order to best describe his or her invention. Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely preferred embodiments of the present invention and do not represent the entire technical concept of the present invention, and that various equivalents and modifications may exist as of the time of filing this application.

[0033] Furthermore, as used herein, "comprise," "comprising," "include," "including" specifies the presence of a stated shape, number, step, operation, member, element, and / or group, but does not exclude the presence or addition of one or more other shapes, numbers, operations, members, elements, and / or groups. Furthermore, when describing an embodiment of the present invention, "may" and "may be" can include "one or more embodiments of the present invention."

[0034] In order to facilitate understanding of the invention, the accompanying drawings may not be drawn to scale, and the dimensions of some components may be exaggerated. In addition, the same reference numerals are used to refer to the same components in different embodiments.

[0035] A statement that two comparison objects are "identical" means that they are "substantially identical." Therefore, being substantially identical can include cases where there is a deviation that is considered low in the art, for example, a deviation of 5% or less. Furthermore, a statement that a certain parameter is uniform in a given region can mean that the parameter is uniform on average.

[0036] Although terms such as "first" and "second" are used to describe various components, it is understood that these components are not limited by these terms. These terms are merely used to distinguish one component from another, and unless otherwise specified, a first component can be a second component.

[0037] Throughout the specification, unless specifically stated to the contrary, each element may be singular or plural.

[0038] The phrase "above (or below)" a component or "above (or below)" a component means that the component is not only placed in contact with the upper surface (or lower surface) of the component, but also means that other components may be interposed between the component and the component placed above (or below) the component.

[0039] Furthermore, when a component is described as being "coupled," "coupled," or "connected" to another component, it should be understood that the components may be directly coupled or connected to each other, but that other components may be "intervening" between the components, or that each component may be "coupled," "coupled," or "connected" via other components.

[0040] Furthermore, when a part is said to be electrically coupled to another part, this includes not only a direct connection but also a connection via another element therebetween.

[0041] Throughout the specification, "A and / or B" means A, B, or A and B, unless expressly stated to the contrary. That is, "and / or" includes all or any combination of the listed items. "C through D" means at least C and at most D, unless expressly stated to the contrary.

[0042] 1 is a perspective view illustrating an example of a secondary battery 100 according to an embodiment of the present disclosure. The secondary battery 100 according to this embodiment may include at least one electrode assembly 10 formed by winding a positive electrode 11 and a negative electrode 12 with an insulating separator 13 sandwiched between them, a case 20 in which the electrode assembly 10 is housed, and a cap assembly 30 coupled to an opening of the case 20.

[0043] The secondary battery 100 according to this embodiment will be described as a rectangular lithium ion secondary battery, but the present invention is not limited thereto and can be applied to batteries of various shapes, such as lithium polymer batteries or cylindrical batteries.

[0044] The positive electrode 11 and the negative electrode 12 can include a composition-coated portion in which an active material is applied to a current collector made of a thin metal foil, and uncoated portions 11a, 12a in which no active material is applied.

[0045] The positive electrode 11 and the negative electrode 12 are wound with an insulating separator 13 sandwiched between them. However, the present invention is not limited thereto, and the electrode assembly 10 may have a structure in which positive electrodes and negative electrodes made of a plurality of sheets are alternately stacked with a separator sandwiched between them.

[0046] The case 20 forms the overall appearance of the secondary battery 100 and may be made of a conductive metal such as aluminum, an aluminum alloy, nickel-plated steel, or stainless steel (SUS). The case 110 may also provide a space in which the electrode assembly 10 is housed.

[0047] The cap assembly 30 may include a cap plate 31 that covers the opening of the case 20, and the case 20 and the cap plate 31 may be made of a conductive material. Here, a positive electrode terminal 21 and a negative electrode terminal 22 electrically connected to the positive electrode 11 or the negative electrode 12 may be installed to penetrate the cap plate 31 and protrude outward.

[0048] The outer peripheral surfaces of the upper posts of the positive and negative terminals 21, 22 protruding outward from the cap plate 31 are threaded and can be fixed to the cap plate 31 using nuts.

[0049] However, the present invention is not limited to this, and the positive and negative electrode terminals 21, 22 may be riveted together using a rivet structure, or may be joined to the cap plate 31 by welding.

[0050] The cap plate 31 is made of a thin plate and can be attached to the opening of the case 20. The cap plate 31 can be formed with an electrolyte injection hole 32 to which a sealing plug 33 is attached, and can be provided with a vent portion 34 in which a notch is formed.

[0051] The positive electrode terminal and the negative electrode terminal 21, 22 may be electrically connected to current collectors including first and second current collectors 40, 50 (hereinafter referred to as positive electrode current collector and negative electrode current collector) joined to the positive electrode uncoated portion 11 a or the negative electrode uncoated portion 12 a by welding.

[0052] For example, the positive and negative electrode terminals 21 and 22 may be joined to the positive and negative electrode current collectors 40 and 50 by welding. However, the present invention is not limited thereto, and the positive and negative electrode terminals 21 and 22 may be integrally formed with the positive and negative electrode current collectors 40 and 50.

[0053] An insulating member may be installed between the electrode assembly 10 and the cap plate 31. Here, the insulating member may include first and second lower insulating members 60 and 70, and each of the first and second lower insulating members 60 and 70 may be installed between the electrode assembly 10 and the cap plate 31.

[0054] Furthermore, according to this embodiment, one end of a separating member may be installed between the insulating member and the positive or negative electrode terminal 21 or 22 so as to face one side of the electrode assembly 10 .

[0055] Here, the separating members may include first and second separating members 80, 90.

[0056] Therefore, one end of the first and second separating members 80, 90 may be installed between the first and second lower insulating members 60, 70 and the positive and negative terminals 21, 22, facing one side of the electrode assembly 10.

[0057] In other words, the positive and negative electrode terminals 21 and 22, which are joined to the positive and negative electrode current collectors 40 and 50 by welding, can be combined with one end of the first and second lower insulating members 60 and 70 and one end of the first and second separating members 80 and 90.

[0058] FIG. 2 is a diagram showing a first comparative example of a method for manufacturing an electrode for a secondary battery, and FIG. 3 is an enlarged cross-sectional view of a region where a composition-coated portion 310 and an uncoated portion 320 according to the first comparative example come into contact.

[0059] According to one embodiment, an electrode for a secondary battery is manufactured by coating an active material on a substrate in the form of a metal thin film. For example, the electrode manufacturing process may involve coating an active material on a roll-shaped substrate in the form of a metal thin film, performing a roll pressing process to roll the substrate coated with the active material, and then performing a slitting and notching process to cut the substrate into an electrode of a desired shape.

[0060] The electrode according to the present disclosure may be a substrate coated with an active material before the notching process, or a substrate coated with an active material after the notching process. In the case of a substrate coated with an active material before the notching process, a plurality of structures corresponding to the taps may be disposed on the electrode. In the case of a substrate coated with an active material after the notching process, a single structure corresponding to the tap may be disposed on the electrode.

[0061] As shown in FIG. 2, composition-coated portions 210 and uncoated portions 220 may be alternately formed on a substrate 200 coated with an active material. The composition-coated portions 210 refer to regions on the substrate 200 where the active material is coated, and the uncoated portions 220 refer to regions where the substrate 200 is exposed without the active material. The active material may be coated at regular intervals along the width direction of the substrate 200. This allows the composition-coated portions 210 and the uncoated portions 220 to be alternately formed along the length direction of the substrate 200. However, shrinkage of the active material and the substrate 200 can cause wrinkles in the uncoated portions 220, which can degrade the quality of the battery.

[0062] FIG. 3 is an enlarged cross-sectional view of region A in FIG. 2. As shown in FIG. 3, a substrate 300 may have a composition-coated portion 310, on which an active material is coated, and an uncoated portion 320, on which no active material is coated. The composition-coated portion 310 may have an inclined surface 312 at a boundary 302 where the composition-coated portion 310 and the uncoated portion 320 meet. For example, the thickness of the active material formed in the composition-coated portion 310 decreases as it approaches the boundary 302 where the composition-coated portion 310 and the uncoated portion 320 meet. This phenomenon occurs due to the constraints imposed by the shape of the outlet of the slot die, which can lead to a decrease in the flatness of the active material near the boundary 302 where the composition-coated portion 310 and the uncoated portion 320 meet. This can lead to a decrease in adhesion during the subsequent electrode lamination process, shortening the battery's lifespan and reducing its capacity.

[0063] FIG. 4 illustrates a second comparative example of a method for manufacturing a secondary battery electrode, and FIG. 5 is an enlarged cross-sectional view of a contact area between a composition-coated portion 510 and an uncoated portion 520 according to the second comparative example. According to one embodiment, the uncoated portion 420 of the electrode can be formed by etching a portion of the composition-coated portion 410. Specifically, the region corresponding to the uncoated portion 420 can be selectively laser-etched on a substrate 400 that is entirely coated with an active material. In this case, minimizing the area of ​​the uncoated portion 420 formed on the substrate 400 can partially resolve the problem of wrinkles occurring in the uncoated portion 420.

[0064] Figure 5 is an enlarged cross-sectional view showing region B in Figure 4. As shown in Figure 5, a composition-coated portion 510, on which an active material is coated, and an uncoated portion 520, which is formed by laser etching the active material coated on the substrate 500, can be formed on the substrate 500. When the uncoated portion 520 is formed by the laser etching process, the side portion of the composition-coated portion 510 can be formed to be approximately perpendicular to the substrate 500 at a boundary portion 502 where the composition-coated portion 510 and the uncoated portion 520 come into contact. This can solve some of the problems that arise due to reduced flatness of the active material at the boundary portion 502 between the composition-coated portion 510 and the uncoated portion 520.

[0065] However, when the uncoated portion is formed by a laser etching process, a heat-affected zone (HAFZ) may be formed near the boundary 502 where the composition-coated portion 510 and the uncoated portion 520 come into contact due to the laser output. The heat-affected active material increases in hardness, which may damage the separator at the contact point between the heat-affected zone of the composition-coated portion 510 and the separator during the subsequent battery assembly process. This phenomenon is exacerbated by the reduction in the contact area between the separator and the composition-coated portion 510, which occurs when the side surfaces of the composition-coated portion 510 are formed substantially vertically. Damage to the separator may result in a battery short circuit. This disclosure describes a method for manufacturing an electrode to solve the above-mentioned problems.

[0066] 6 is an enlarged cross-sectional view of a contact area between a composition-coated portion 610 and an uncoated portion 620 according to an embodiment of the present disclosure. According to an embodiment, a stepped surface 616 may be formed on a side surface of the composition-coated portion 610 at the contact area between the composition-coated portion 610 and the uncoated portion 620. Specifically, the side surface may include a first side wall 612, a second side wall 614, and a stepped surface 616 connecting the first side wall 612 and the second side wall 614. One end of the first side wall 612 is connected to the exposed substrate corresponding to the uncoated portion, and the other end of the first side wall 612 is connected to the stepped surface 616. The first side wall 612 may form a first angle with respect to one surface of the substrate 600. The first angle may be, but is not limited to, 80° to 90°.

[0067] The stepped surface 616 is connected to the first side wall 612 and the second side wall 614. The stepped surface 616 can be formed parallel to one surface of the substrate or the top surface of the composition-coated portion. Alternatively, the stepped surface 616 can be formed obliquely relative to one surface of the substrate or the top surface of the composition-coated portion.

[0068] One end of the second side wall 614 is connected to the stepped surface 616, and the other end of the second side wall 614 is connected to the top surface of the composition application portion 610. The second side wall 614 may form a second angle with respect to one surface of the substrate 600. The second angle may be, but is not limited to, 80° to 90°. The stepped surface 616 may be formed approximately parallel to one surface of the substrate 600, but is not limited to this.

[0069] According to one embodiment, the uncoated portion 620 may be formed by etching a portion of the composition-coated portion 610 formed on the substrate 600. Specifically, a region corresponding to the uncoated portion 620 may be selectively laser-etched on the substrate 600, which is entirely coated with an active material. When the uncoated portion 620 is formed by the laser etching process, the side of the composition-coated portion 610 may be formed to be approximately perpendicular to the substrate 600 at a first boundary portion 602 where the composition-coated portion 610 and the uncoated portion 620 come into contact. For example, the first sidewall 612 of the composition-coated portion 610 may be formed to form an angle of 80° to 90° with respect to one surface of the substrate 600.

[0070] According to one embodiment, two laser etching processes may be performed to form a stepped surface on the side surface of composition-coated portion 610. For example, the active material coated in the region abutting first boundary portion 602 may be etched in a first laser etching process, and then the active material coated in the region abutting second boundary portion 604 may be etched in a second laser etching process. Alternatively, the active material coated in the region abutting second boundary portion 604 may be etched in a first laser etching process, and then the active material coated in the region abutting first boundary portion 602 may be etched in a second laser etching process.

[0071] According to one embodiment, the laser irradiation area and laser irradiation depth of the regions etched by the first laser etching process and the second laser etching process may be different from each other. Furthermore, the laser output intensities for the first laser etching process and the second laser etching process may be different from each other. The heat-affected zone can be controlled by controlling the laser output intensities for the respective laser etching processes to be different from each other. An example of forming a stepped surface 616 on the side surface of the composition-coated portion by the laser etching process will be described in detail below with reference to FIG. 7.

[0072] This configuration allows a step to be formed at the boundary between the composition-coated portion 610 and the uncoated portion 620 where the heat-affected zone is formed. This increases the contact area between the heat-affected zone of the composition-coated portion 610 and the separator during the subsequent battery assembly process. At this time, the flatness of the active material can be maintained at the boundary between the composition-coated portion 610 and the uncoated portion 620, while reducing the risk of damage to the separator.

[0073] 7 is an enlarged perspective view showing an uncoated portion 720 according to one embodiment of the present disclosure. According to one embodiment, the uncoated portion 720 may be formed by laser etching a partial region of the composition-coated portion 710. In this case, a stepped surface 716 may be formed on a side portion of the composition-coated portion 710 formed at a location where the composition-coated portion 710 and the uncoated portion 720 contact each other. For example, the side portion may include a first side wall 712, a second side wall 714, and a stepped surface 716 connecting the first side wall 712 and the second side wall 714.

[0074] According to one embodiment, the stepped surface 716 formed on the side surface of the composition-coated portion 710 can be formed by two laser etching processes. For example, the first sidewall 712 is formed by a first laser etching process, and the second sidewall 714 and the stepped surface 716 connecting the two sidewalls are formed by a second laser etching process.

[0075] According to one embodiment, the first laser etching process etches the region corresponding to the uncoated portion 720 with a first irradiation area 730 and a first depth, which may be the depth (Δh1+Δh2) from the surface (h3) of the composition-coated portion 710 to the surface (h1) of the substrate.

[0076] Then, a second laser etching step is performed to etch the area corresponding to the uncoated portion 720 with a second irradiation area 740 and a second depth, which may be a depth (Δh2) from the surface (h3) of the composition-coated portion 710 to the surface (h2) of the predetermined step surface 716.

[0077] According to one embodiment, second irradiation area 740 may include first irradiation area 730 and may be larger than first irradiation area 730. The difference between second irradiation area 740 and first irradiation area 730 determines the width of step surface 716 formed on the side surface of composition-applied portion 710.

[0078] According to one embodiment, the laser output intensities for the first and second laser etching processes may be different from each other. For example, the laser output intensity for the first laser etching process, which etches to a first depth, may be greater than the laser output intensity for the second laser etching process, which etches to a second depth that is shallower than the first depth.

[0079] According to one embodiment, a first sidewall 712 may be formed on a side surface of the composition-coated portion 710 by a first laser etching process that etches the composition-coated portion 710 to a first depth from the surface of the composition-coated portion 710. The first sidewall 712 may be formed at an angle of 80° to 90° with respect to one surface of the substrate, but is not limited thereto.

[0080] According to one embodiment, a step surface 716 and a second side wall 714 can be formed on the side surface of the composition-coated portion 710 by a second laser etching process in which etching is performed to a second depth from the surface of the composition-coated portion 710. The second side wall 714 can be formed at an angle of 80° to 90° with respect to one surface of the substrate, but is not limited to this. The step surface 716 connecting the first side wall 712 and the second side wall 714 can be formed approximately parallel to one surface of the substrate, but is not limited to this.

[0081] Although FIG. 7 illustrates the second laser etching step being performed after the first laser etching step, the order of the laser etching steps is not limited thereto. For example, the second laser etching step etches the region corresponding to the uncoated portion 720 with a second irradiation area 740 and a second depth. The second depth may be a depth (Δh2) from the surface (h3) of the composition-coated portion 710 to the surface (h2) of the predetermined step surface. Then, the first laser etching step etches the region corresponding to the uncoated portion 720 with a first irradiation area 730 and a first depth. The first depth may be a depth (Δh1) from the surface (h2) of the predetermined step surface to the surface (h1) of the substrate.

[0082] According to one embodiment, the laser etching process can be controlled so that only one laser etching is performed on overlapping etching areas that occur during multiple laser etching processes. For example, if some of the irradiation areas in each laser etching process overlap, laser etching can be performed only on the non-overlapping irradiation areas. Instead of irradiating the entire area represented by the irradiation areas with laser, laser etching can be performed only on the areas where the irradiation areas for each laser etching process do not overlap.

[0083] Alternatively, multiple laser etchings can be performed with overlapping etching areas occurring during multiple laser etching steps.

[0084] FIG. 8 is a graph 800 showing the thickness of the active material layer depending on the position of the contact area between the composition-coated portion and the uncoated portion according to one embodiment of the present disclosure. FIG. 8 is a graph showing the thickness of the active material layer based on a vertical cross section of the contact area between the composition-coated portion 710 and the uncoated portion 720 shown in FIG. 7. As shown in FIG. 8, it can be seen that a stepped surface is formed on the side surface of the composition-coated portion. Specifically, the side surface of the composition-coated portion includes a first sidewall (e.g., 712 in FIG. 7), a second sidewall (e.g., 714 in FIG. 7), and a stepped surface (e.g., 716 in FIG. 7).

[0085] According to one embodiment, the first point (X1) may be the point where the surface of the composition-coated portion and the second sidewall come into contact, the second point (X2) may be the point where the second sidewall and the stepped surface come into contact, the third point (X3) may be the point where the stepped surface and the first sidewall come into contact, and the fourth point (X4) may be the point where the first sidewall and the surface of the substrate come into contact, and the surface of the substrate that comes into contact with the second sidewall may be an uncoated portion.

[0086] According to one embodiment, the first point (X1) and the second point (X2) may be located on the second side wall, and the third point (X3) and the fourth point (X4) may be located on the first side wall. Each of the first side wall and the second side wall formed on the side portion of the composition-coated portion may be formed at an angle of 80° to 90° with respect to one surface of the substrate. The angle formed by the first side wall and one surface of the substrate and the angle formed by the second side wall and one surface of the substrate may be different from each other, but is not limited to this.

[0087] The values ​​for the width and height of the first side wall, the second side wall, and the step surface shown in graph 800 are merely examples and are not intended to be limiting. For example, the total width of the side surface of the composition-coated portion is shown to be approximately 0.117 mm, but is not limited to this, and the total width of the side surface can be determined to be approximately within 0.1 mm.

[0088] FIG. 9 is an enlarged perspective view showing an uncoated portion 920 according to another embodiment of the present disclosure. According to one embodiment, the uncoated portion 920 can be formed by laser etching a partial region of the composition-coated portion 910. In this case, multiple stepped surfaces can be formed on the side surface of the composition-coated portion 910 at the contact points between the composition-coated portion 910 and the uncoated portion 920. For convenience of explanation, FIG. 9 illustrates an example in which two stepped surfaces are formed on the side surface of the composition-coated portion 910. For example, the side surface of the composition-coated portion 910 can include a first side wall 912, a second side wall 914, a third side wall 916, a first stepped surface 913 connecting the first side wall 912 and the second side wall 914, and a second stepped surface 915 connecting the second side wall 914 and the third side wall 916.

[0089] According to one embodiment, the stepped surface formed on the side surface of the composition-coated portion 910 can be formed by three laser etching processes. For example, a first sidewall 912 is formed by a first laser etching process, a first stepped surface 913 and a second sidewall 914 are formed by a second laser etching process, and a second stepped surface 915 and a third sidewall 916 are formed by a third laser etching process.

[0090] According to one embodiment, a first laser etching process etches the region corresponding to the uncoated portion 920 with a first irradiation area 930 and a first depth. The first depth may be a depth (Δh1 + Δh2 + Δh3) from the surface (h4) of the composition-coated portion 910 to the surface (h1) of the substrate. Thereafter, a second laser etching process etches the region corresponding to the uncoated portion 920 with a second irradiation area 940 and a second depth. The second depth may be a depth (Δh2 + Δh3) from the surface (h4) of the composition-coated portion 910 to the surface (h2) of the predetermined first step surface 913. Thereafter, a third laser etching process etches the region corresponding to the uncoated portion 920 with a third irradiation area 950 and a third depth. The third depth may be a depth (Δh3) from the surface (h4) of the composition-coated portion 910 to the surface (h3) of the predetermined second step surface 915.

[0091] According to one embodiment, the second illumination area 940 may include the first illumination area 930 and be larger than the first illumination area 930. The difference between the second illumination area 940 and the first illumination area 930 determines the width of the first step surface 913. The third illumination area 950 may include the second illumination area 940 and be larger than the second illumination area 940. The difference between the third illumination area 950 and the second illumination area 940 determines the width of the second step surface 915.

[0092] According to one embodiment, the laser output intensities for the first, second, and third laser etching processes may be different from one another. For example, the laser output intensity for the first laser etching process, which etches to a first depth, may be greater than the laser output intensity for the second laser etching process, which etches to a second depth that is shallower than the first depth. Also, the laser output intensity for the second laser etching process, which etches to a second depth, may be greater than the laser output intensity for the third laser etching process, which etches to a third depth that is shallower than the second depth.

[0093] According to one embodiment, a first sidewall 912 may be formed on a side surface of the composition-coated portion 910 by a first laser etching process that etches the composition-coated portion 910 to a first depth from the surface of the composition-coated portion 910. The first sidewall 912 may be formed at an angle of 80° to 90° with respect to one surface of the substrate, but is not limited thereto.

[0094] According to one embodiment, a first stepped surface 913 and a second sidewall 914 can be formed on the side surface of the composition-coated portion 910 by a second laser etching process in which etching is performed to a second depth from the surface of the composition-coated portion 910. The second sidewall 914 can be formed at an angle of 80° to 90° with respect to one surface of the substrate, but is not limited to this. The first stepped surface 913 connecting the first sidewall 912 and the second sidewall 914 can be formed approximately parallel to one surface of the substrate, but is not limited to this.

[0095] According to one embodiment, a second stepped surface 915 and a third sidewall 916 can be formed on the side surface of the composition-coated portion 910 by a third laser etching process in which etching is performed to a third depth from the surface of the composition-coated portion 910. The third sidewall 916 can be formed at an angle of 80° to 90° with respect to one surface of the substrate, but is not limited to this. The second stepped surface 915 connecting the second sidewall 914 and the third sidewall 916 can be formed approximately parallel to one surface of the substrate, but is not limited to this.

[0096] Although FIG. 9 illustrates the first laser etching step followed by the second laser etching step and the second laser etching step followed by the third laser etching step, the order of the laser etching steps is not limited thereto. For example, the third laser etching step etches the region corresponding to the uncoated portion 920 to a third irradiation area 950 and a third depth. The third depth may be a depth (Δh3) from the surface (h4) of the composition-coated portion 910 to the predetermined surface (h3) of the second step surface. Then, the second laser etching step etches the region corresponding to the uncoated portion 920 to a second irradiation area 940 and a second depth. The second depth may be a depth (Δh2) from the predetermined surface (h3) of the second step surface to the surface (h2) of the first step surface. Then, the first laser etching step etches the region corresponding to the uncoated portion 920 to a first irradiation area 930 and a first depth. The first depth may be a depth (Δh1) from a predetermined first step surface (h2) to a substrate surface (h1).

[0097] In Figure 9, it is explained that two step surfaces are formed on the side surface of the composition-coated portion 910, but the number of step surfaces is not limited to this and can be appropriately changed depending on the thickness of the composition-coated portion, the angle of the side surface of the composition-coated portion, etc.

[0098] 10 is an enlarged perspective view showing an uncoated portion according to still another embodiment of the present disclosure, in which configurations that are explained or overlap with those in FIG.

[0099] According to one embodiment, the stepped surface 1016 formed on the side surface of the composition-coated portion 1010 can be formed by two laser etching processes. For example, the first sidewall 1012 can be formed by a first laser etching process, and the second sidewall 1014 and the stepped surface 1016 can be formed by a second laser etching process.

[0100] According to one embodiment, the stepped surface 1016 may be formed on at least one surface of a side portion of the composition-coated portion 1010. For example, as shown in the figure, if the region in which the uncoated portion 1020 is formed is substantially rectangular, the stepped surface 1016 may be formed on a side portion of the composition-coated portion 1010 corresponding to at least one side of the rectangle. In this case, the side portion of the composition-coated portion 1010 on which the stepped surface 1016 is formed may correspond to the portion where the composition-coated portion and the uncoated portion of the electrode come into contact after the notching process.

[0101] According to one embodiment, a first laser etching process etches the region corresponding to the uncoated portion 1020 with a first irradiation area 1030 and a first depth. The first depth may be a depth (Δh1+Δh2) from the surface (h3) of the composition-coated portion 1010 to the surface (h1) of the substrate. Then, a second laser etching process etches the region corresponding to the uncoated portion 1020 with a second irradiation area 1040 and a second depth. The second depth may be a depth (Δh2) from the surface (h3) of the composition-coated portion 1010 to the surface (h2) of the predetermined step surface 1016.

[0102] According to one embodiment, the second irradiation area 1040 may include the first irradiation area 1030 and may be larger than the first irradiation area 1030. For example, as shown in Figure 10, when the first irradiation area 1030 and the second irradiation area 1040 are substantially rectangular, one length of the first irradiation area 1030 and one length of the second irradiation area 1040 may be the same, and the other length of the first irradiation area 1030 may be shorter than the other length of the second irradiation area 1040. In this case, the width of the step surface 1016 can be determined by the difference between the other length of the first irradiation area 1030 and the other length of the second irradiation area 1040.

[0103] FIG. 11 is a diagram showing an example in which uncoated portions 1120_1 and 1120_2 are formed on both sides of a substrate according to an embodiment of the present disclosure. According to one embodiment, an electrode for a secondary battery is manufactured by coating an active material on a substrate in the form of a metal thin film. In this case, the active material is coated on the entire surface of both sides of the substrate. For example, a first composition-coated portion 1100_1 is formed by coating a first active material on a first side of the substrate, and a second composition-coated portion 1100_2 is formed by coating a second active material on a second side opposite the first side. The substrate coated with the active material may be rolled using a roll press process to form uncoated portions on the rolled substrate.

[0104] According to one embodiment, the uncoated portion of the electrode can be formed by etching a portion of the composition-coated portion. Specifically, the region corresponding to the uncoated portion can be selectively laser-etched on a substrate entirely coated with an active material. For example, the first composition-coated portion 1100_1 formed on the first surface of the substrate can be etched to form the uncoated portion. Using a laser etching device, multiple uncoated portions can be continuously formed on the substrate while the first surface of the substrate is moved along a first direction. Then, multiple uncoated portions can be continuously formed on the substrate while the second surface of the substrate is moved along a second direction. The second surface corresponds to the surface opposite the first surface of the substrate.

[0105] In one embodiment, the plurality of uncoated portions formed on the second surface may be formed at positions corresponding to the plurality of uncoated portions formed on the first surface. For example, the second uncoated portion 1120_2 formed on the second surface of the substrate may be formed at a position corresponding to the first uncoated portion 1120_1 formed on the first surface of the substrate. In this case, the error range for the positions of the first uncoated portion 1120_1 and the second uncoated portion 1120_2 may be adjusted to within 2 mm in the longitudinal direction of the substrate.

[0106] For convenience of explanation, FIG. 11 shows a case in which the moving direction of the first surface of the substrate and the moving direction of the second surface of the substrate are opposite to each other, but the present invention is not limited to this.

[0107] 12 is a diagram illustrating an example in which multiple uncoated portions are formed on one surface of a substrate according to an embodiment of the present disclosure. According to one embodiment, multiple uncoated portions can be simultaneously etched using a laser etching device. For example, the laser etching device can include multiple laser heads. The laser etching device can simultaneously etch multiple regions corresponding to the uncoated portions on the substrate using the multiple laser heads while moving the substrate coated with an active material in a certain direction.

[0108] Although Fig. 12 shows a laser etching apparatus having six laser heads, the present invention is not limited to this. Also, Fig. 12 shows an uncoated portion formed by the laser etching apparatus having a substantially square shape, but the present invention is not limited to this, and the shape and size of the uncoated portion can be appropriately changed depending on the design of the electrode to be manufactured.

[0109] 13 is a flowchart illustrating a method 1300 for manufacturing an electrode for a secondary battery according to one embodiment of the present disclosure. According to one embodiment, the method 1300 for manufacturing an electrode for a secondary battery can begin by forming a first composition coating portion containing an active material on one surface of a substrate (S1310).

[0110] Thereafter, a first region of the first composition-coated portion can be etched to form a first uncoated portion that exposes one surface of the substrate (S1320). For example, the first region of the first composition-coated portion can be laser etched. According to one embodiment, multiple first regions of the first composition-coated portion can be etched simultaneously. Then, the substrate can be notched relative to the etched first region of the first composition-coated portion to form a tap.

[0111] According to one embodiment, the side surface of the first composition-coated portion that contacts the first uncoated portion may have a stepped surface. Specifically, the first region may be laser-etched with a first irradiation area in the first laser etching step, and the first region may be laser-etched with a second irradiation area different from the first irradiation area in the second laser etching step. In this case, the first irradiation area may be smaller than the second irradiation area.

[0112] The first irradiation area may have a first depth, and the second irradiation area may have a second depth. In this case, the first depth may be deeper than the second depth. The laser output intensities for the first and second laser etching steps may be different from each other.

[0113] According to one embodiment, the method may further include forming a second composition-coated portion containing an active material on the other surface of the substrate. Furthermore, a plurality of second regions of the second composition-coated portion may be etched to form second uncoated portions that expose the other surface of the substrate. In this case, the side portion of the second composition-coated portion that contacts the second uncoated portion may also have a stepped surface. Furthermore, the second uncoated portion may be formed at a position corresponding to the first uncoated portion.

[0114] Although the present invention has been described above using limited examples and drawings, it is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims. [Explanation of symbols]

[0115] 10 Electrode assembly 11 Positive electrode 11a Positive electrode uncoated area 12 Negative electrode 12a Negative electrode uncoated area 13 Separator 20 cases 21 Positive terminal 22 Negative terminal 30 Cap Assembly 31 Cap plate 32 Electrolyte inlet 33 Sealing plug 34 Vent section 40 Positive electrode current collector 50 Negative electrode current collector 60 First lower insulating member 70 Second lower insulating member 80 first separating member 90 Second separating member 100 Secondary battery

Claims

1. A substrate; a first composition-coated portion including an active material and disposed on one surface of the substrate; a first uncoated portion disposed on one side of the substrate, in contact with the first composition-coated portion, and exposing the substrate; An electrode, wherein a first side portion of the first composition-coated portion that contacts the first uncoated portion has a stepped surface.

2. the first side portion includes a first sidewall formed at a first angle with respect to one surface of the base material, and a second sidewall formed at a second angle with respect to the one surface of the base material, the step surface connects the first side wall and the second side wall, The electrode of claim 1 , wherein the first sidewall contacts the first uncoated portion.

3. The electrode of claim 2 , wherein the first angle and the second angle are each between 80° and 90°.

4. The electrode of claim 2 , wherein the first angle and the second angle are different from each other.

5. The electrode of claim 1 , wherein the substrate comprises a plurality of first uncoated portions.

6. The electrode according to claim 1 , wherein the notched first uncoated portion contacts a first side portion of the first composition coated portion.

7. a second composition-coated portion disposed on the other surface of the substrate; a second uncoated portion disposed on the other surface of the substrate, where the substrate is exposed; The electrode according to claim 1 , wherein a second side surface portion of the second composition-coated portion that contacts the second uncoated portion has a stepped surface.

8. The electrode according to claim 7 , wherein the second uncoated portion is formed at a position corresponding to the first uncoated portion.

9. The electrode of claim 8 , wherein the substrate comprises a plurality of first uncoated portions and a plurality of second uncoated portions.

10. a first electrode; a second electrode; and a separator disposed between the first electrode and the second electrode; the first electrode includes a substrate having uncoated portions disposed on both sides thereof, a first composition-coated portion including a first active material disposed on one side of the substrate, and a second composition-coated portion including a second active material disposed on the other side of the substrate; An electrode assembly, wherein a first side portion of the first composition coated portion that contacts the uncoated portion has a stepped surface.

11. The electrode assembly according to claim 10 , wherein a second side surface portion of the second composition-coated portion that contacts the uncoated portion has a stepped surface.

12. forming a first composition coated portion containing an active material on one surface of a substrate; etching a first region of the first composition coated portion to form a first uncoated portion exposing one surface of the substrate; A method for manufacturing an electrode for a secondary battery, wherein a side portion of the first composition coated portion in contact with the first uncoated portion has a stepped surface.

13. The method for manufacturing an electrode for a secondary battery according to claim 12 , wherein the etching step includes a step of laser etching the first region of the first composition coated portion.

14. The etching step includes: a first laser etching step for laser etching the first region with a first irradiation area; and a step of laser etching the first region with a second irradiation area different from the first irradiation area by a second laser etching step.

15. The method for manufacturing an electrode for a secondary battery according to claim 14 , wherein the first irradiation area is smaller than the second irradiation area.

16. the first illuminated area has a first depth; the second illuminated area has a second depth; The method for manufacturing an electrode for a secondary battery according to claim 14 , wherein the first depth is greater than the second depth.

17. The method of claim 14 , wherein the first laser etching step and the second laser etching step have different laser output intensities.

18. The method for manufacturing a secondary battery electrode according to claim 12 , wherein the etching step includes a step of simultaneously etching a plurality of first regions of the first composition coated portion.

19. The method for manufacturing an electrode for a secondary battery according to claim 12 , further comprising the step of notching the substrate in the first region to form a tap.

20. forming a second composition-coated portion containing an active material on the other surface of the substrate; etching a plurality of second regions of the second composition-coated portion to form second uncoated portions that expose the other surface of the substrate; a side surface of the second composition-coated portion in contact with the second uncoated portion has a stepped surface; The method for manufacturing an electrode for a secondary battery according to claim 12 , wherein the second uncoated portion is formed at a position corresponding to the first uncoated portion.

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