Electrodes for secondary batteries and methods for manufacturing 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

[0005]

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

Background Art

[0002] [[ID=​​​​​​​​​​​​​​​​​​​​​​​​​​​​

[0006] The problem that this disclosure aims to solve is to provide an electrode for a secondary battery and a method for manufacturing the same that solve the aforementioned problems.

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

[0008] According to some embodiments of the present disclosure for solving technical problems, the electrode includes a substrate, a first composition coating portion containing an active material disposed on one surface of the substrate, and a first uncoated portion disposed on one surface of the substrate, in contact with the first composition coating portion, and exposing the substrate, wherein the first side surface of the first composition coating 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 side wall formed at a first angle with respect to one surface of the substrate and a second side wall formed at a second angle with respect to one surface of the substrate, the stepped surface connecting the first side wall and the second side wall, and the first side wall in contact with the first uncoated portion.

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

[0011] According to some embodiments of this 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 is in contact with 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 in which the substrate is exposed, wherein 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 this disclosure, a second uncoated area is formed at a position corresponding to a first uncoated area.

[0016] According to some embodiments of the present disclosure, the 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 technical problems, 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, a first composition coated portion containing a first active material disposed on one side of the substrate, and a second composition coated portion containing a second active material disposed on the other side of the substrate, wherein the 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 surface of the second composition-coated portion that is in contact with the uncoated portion has a stepped surface.

[0019] According to some embodiments of the present disclosure for solving technical problems, a method for manufacturing an electrode for a secondary battery includes the steps of forming a first composition coating portion containing an active material on one surface of a substrate, and etching a first region of the first composition coating portion to form a first uncoated portion on one surface of the substrate, wherein the side portion of the first composition coating portion in contact with the first uncoated portion has a stepped surface.

[0020] According to some embodiments of the present disclosure, the etching step includes the step of laser etching a first area of ​​the first composition coated portion.

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

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

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

[0024] According to some embodiments of the present disclosure, the laser output intensities for laser-etching in the first laser-etching process and the second laser-etching process 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 a first composition coating section.

[0026] According to some embodiments of the present disclosure, the method further includes notching a base material with respect to the first region to form a tap.

[0027] According to some embodiments of the present disclosure, the method further includes forming a second composition coating section containing an active material on the other surface of the base material, and etching a plurality of second regions of the second composition coating section to form a second uncoated section where the other surface of the base material is exposed. A side surface portion of the second composition coating section in contact with the second uncoated section has a stepped surface, and the second uncoated section is formed at a position corresponding to the first uncoated section.

Advantages 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 coated and uncoated portions of the composition, while simultaneously reducing the risk of damage to the separator.

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

[0031] The following drawings and other illustrations attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention later, play a role in further understanding the technical concept of the present invention. Therefore, the present invention should not be analyzed in isolation from the matters described in such drawings. [Figure 1] This is a perspective view showing an example of a secondary battery according to one embodiment of the present disclosure. [Figure 2] This figure shows a first comparative example of a method for manufacturing electrodes for secondary batteries. [Figure 3] This is an enlarged cross-sectional view of the area where the coated and uncoated portions of the composition come into contact in the first comparative example. [Figure 4] This figure shows a second comparative example of a method for manufacturing electrodes for secondary batteries. [Figure 5] This is an enlarged cross-sectional view of the area where the coated and uncoated portions of the composition come into contact in the second comparative example. [Figure 6] This is an enlarged cross-sectional view of the area where the coated portion and the uncoated portion of the composition come into contact, according to one embodiment of the present disclosure. [Figure 7] This is an enlarged perspective view showing an unpainted portion according to one embodiment of the present disclosure. [Figure 8]This graph shows the thickness of the active material layer at the location of contact between the coated and uncoated portions of the composition according to one embodiment of the present disclosure. [Figure 9] This is an enlarged perspective view showing an uncoated portion according to another embodiment of the present disclosure. [Figure 10] This is an enlarged perspective view showing an unpainted area according to another embodiment of the present disclosure. [Figure 11] This figure shows an example in which uncoated areas are formed on both sides of a substrate according to one embodiment of the present disclosure. [Figure 12] This figure shows an example in which multiple uncoated areas are formed on one surface of a substrate according to one embodiment of the present disclosure. [Figure 13] This flowchart shows a method for manufacturing an electrode for a secondary battery according to one embodiment of the present disclosure. [Modes for carrying out the invention]

[0032] Preferred embodiments of this disclosure will now be described in detail based on the accompanying drawings. First, terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary and dictionary meanings, but rather in a manner consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors may define the concepts of terms as appropriate to best describe their invention. Accordingly, it should be understood that the embodiments and configurations shown in the drawings described herein represent only a selection of preferred embodiments of the present invention and do not represent the entirety of the technical idea of ​​the present invention, and that there may be a variety of equivalents and modifications that can substitute for them at the time of filing this application.

[0033] Furthermore, as used herein, “comprise,” “comprising,” “include,” and “including” specify the presence of the shapes, figures, steps, actions, members, elements, and / or groups mentioned, but do not exclude the presence or addition of one or more other shapes, figures, actions, members, elements, and / or groups. Also, when describing embodiments of the present invention, “may be,” and “may include,” “one or more embodiments of the present invention.”

[0034] Furthermore, to aid in understanding the invention, the accompanying drawings may not be shown to actual scale, and the dimensions of some components may be exaggerated. Also, the same reference numeral is assigned to the same component in different embodiments.

[0035] The statement that two comparison objects are "identical" means that they are "substantially identical." Therefore, being substantially identical may include having deviations that are considered low in this industry, for example, deviations of 5% or less. Furthermore, the uniformity of a parameter within a given domain can mean uniformity in terms of the average.

[0036] While terms like "first," "second," etc., are used to describe various components, these components are not limited by these terms. These terms are merely used to distinguish one component from another, and unless otherwise stated, the first component can be the second component.

[0037] Throughout the specification, unless otherwise stated, each component may be singular or plural.

[0038] When we say that any component is placed "above (or below)" or "above (or below)" a component, it means not only that the component is placed in contact with the top (or bottom) surface of the component, but also that other components may be interposed between the component and any component placed above (or below) it.

[0039] Furthermore, when it is stated that one component is "linked," "joined," or "connected" to another component, it must be understood that these components can be directly linked or connected to each other, but that other components can also "intersect" between them, or that components can be "linked," "joined," or "connected" through other components.

[0040] Furthermore, when we say that one part is electrically coupled to another part, this includes not only cases where they are directly connected, but also cases where other elements are in between to form the connection.

[0041] Throughout the specification, when we refer to "A and / or B," we mean A, B, or A and B unless otherwise specified. That is, "and / or" includes all combinations or any combination of the listed items. When we refer to "C through D," we mean C or greater and D or less, unless otherwise specified.

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

[0043] In this embodiment, the secondary battery 100 is described using a prismatic lithium-ion secondary battery as an example. However, the present invention is not limited thereto and can be applied to various types of batteries, such as lithium polymer batteries or cylindrical batteries.

[0044] The positive electrode 11 and the negative electrode 12 may include a composition-coated portion where an active material is applied to a current collector made of a thin metal foil, and uncoated portions 11a and 12a where the active material is not applied.

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

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

[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, the positive and negative terminals 21 and 22, which are electrically connected to the positive electrode 11 or the negative electrode 12, can be installed so as to penetrate the cap plate 31 and protrude outward.

[0048] Furthermore, the outer surfaces of the upper columns of the positive and negative terminals 21 and 22, which protrude from the outside of the cap plate 31, can be threaded and fixed to the cap plate 31 using nuts.

[0049] However, the present invention is not limited thereto, and the positive terminal and the negative terminal 21, 22 may be riveted together by a rivet structure, or they may be welded to the cap plate 31.

[0050] Furthermore, 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 have an electrolyte inlet 32 ​​to which a sealing plug 33 is attached, and a vent section 34 with a notch can be installed.

[0051] The positive and negative terminals 21 and 22 can be electrically connected to a current collector including first and second current collectors 40 and 50 (hereinafter referred to as the positive current collector and the negative current collector) which are joined by welding to the unpainted portion 11a of the positive electrode or the unpainted portion 12a of the negative electrode.

[0052] For example, the positive and negative terminals 21 and 22 can be joined to the positive and negative current collectors 40 and 50 by welding. However, the present invention is not limited thereto, and the positive and negative terminals 21 and 22 and the positive and negative current collectors 40 and 50 can also be formed as a single integrated unit.

[0053] Furthermore, an insulating member can 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 can be installed between the electrode assembly 10 and the cap plate 31.

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

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

[0056] Therefore, one end of the first and second separating members 80 and 90, which are installed so as to face one side of the electrode assembly 10, can be installed between the first and second lower insulating members 60 and 70 and the positive and negative terminals 21 and 22.

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

[0058] Figure 2 shows a first comparative example of the method for manufacturing electrodes for secondary batteries, and Figure 3 is an enlarged cross-sectional view of the area where the composition-coated portion 310 and the uncoated portion 320 come into contact according to the first comparative example.

[0059] According to one embodiment, electrodes for secondary batteries are manufactured by coating an active material onto a metal thin-film substrate. For example, the electrode manufacturing process involves coating a roll-shaped metal thin-film substrate with the active material, followed by a roll pressing process to roll the substrate coated with the active material. Subsequently, slitting and notching processes are performed to cut the substrate into the desired electrode shape.

[0060] The electrode according to this disclosure may be a substrate coated with the active material before the notching process, or a substrate coated with the active material after the notching process. In the case of a substrate coated with the active material before the notching process, multiple tap-corresponding components may be arranged on the electrode. In the case of a substrate coated with the active material after the notching process, one tap-corresponding component may be arranged on the electrode.

[0061] As shown in Figure 2, on a substrate 200 coated with active material, coated areas 210 and uncoated areas 220 can be alternately formed. The coated areas 210 refer to the regions on the substrate 200 to which the active material is coated, and the uncoated areas 220 refer to the regions where the active material is not coated and the substrate 200 is exposed. The active material can be applied at regular intervals along the width direction of the substrate 200. This allows for the alternate formation of coated areas 210 and uncoated areas 220 along the longitudinal direction of the substrate 200. However, shrinkage of the active material and the substrate 200 can cause wrinkles in the uncoated areas 220, which can degrade the quality of the battery.

[0062] Figure 3 is an enlarged cross-sectional view showing area A in Figure 2. As shown in Figure 3, a composition-coated portion 310 on the substrate 300 can be formed, where the active material is applied, and an uncoated portion 320 on which the active material is not applied. The composition-coated portion 310 can form an inclined surface 312 at the boundary portion 302 where the composition-coated portion 310 and the uncoated portion 320 come into contact. For example, the thickness of the active material formed on the composition-coated portion 310 decreases as it approaches the boundary portion 302 that comes into contact with the uncoated portion 320. This phenomenon occurs due to constraints imposed by the shape of the ejection portion of the slot die, and has the problem of reducing the flatness of the active material near the boundary portion 302 where the composition-coated portion 310 and the uncoated portion 320 come into contact. As a result, the adhesive strength decreases during the subsequent electrode stacking process, which may lead to a shortened battery life and a reduction in battery capacity.

[0063] Figure 4 shows a second comparative example of a method for manufacturing electrodes for secondary batteries, and Figure 5 is an enlarged cross-sectional view of the area where the composition-coated portion 510 and the uncoated portion 520 come into contact 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, in a substrate 400 on which the active material is coated throughout, the area corresponding to the uncoated portion 420 can be selectively laser-etched. In this case, by minimizing the area of ​​the uncoated portion 420 formed on the substrate 400, some of the problems of wrinkles occurring in the uncoated portion 420 can be solved.

[0064] Figure 5 is an enlarged cross-sectional view showing area B in Figure 4. As shown in Figure 5, a composition coating area 510 on which the active material is applied and an uncoated area 520 formed by laser etching the active material applied on the substrate 500 can be formed. When the uncoated area 520 is formed by the laser etching process, the side surface of the composition coating area 510 can be formed to be substantially perpendicular to the substrate 500 at the boundary area 502 where the composition coating area 510 and the uncoated area 520 come into contact. In this case, some of the problems that arise from reducing the flatness of the active material at the boundary area 502 between the composition coating area 510 and the uncoated area 520 can be solved.

[0065] However, when an uncoated area is formed by a laser etching process, a heat-affected zone (HAT) may be formed near the boundary area 502 where the coated portion 510 and the uncoated portion 520 come into contact due to the laser output. The active material affected by the heat increases in hardness, and in subsequent battery assembly processes, there is a risk of damaging the separator at the point where the heat-affected zone of the coated portion 510 comes into contact with the separator. This phenomenon is exacerbated by the fact that the side surface of the coated portion 510 is formed to be substantially vertical, which reduces the contact area between the separator and the coated portion 510. If the separator is damaged, there is a risk of a battery short circuit occurring. This disclosure describes an electrode manufacturing method to solve the above-mentioned problems.

[0066] Figure 6 is an enlarged cross-sectional view of the area where the composition-coated portion 610 and the uncoated portion 620 come into contact according to one embodiment of the present disclosure. According to one embodiment, a stepped surface 616 can be formed on the side surface of the composition-coated portion 610 at the area where the composition-coated portion 610 and the uncoated portion 620 come into contact. 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 can form a first angle with respect to one surface of the substrate 600. The first angle may be 80° to 90°, but is not limited thereto.

[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 uppermost surface of the composition coating. Alternatively, the stepped surface 616 can be formed at an angle to one surface of the substrate or the uppermost surface of the composition coating.

[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 uppermost surface of the composition coated portion 610. The second side wall 614 can form a second angle with respect to one surface of the base material 600. The second angle may be 80° to 90°, but is not limited thereto. The stepped surface 616 can be formed substantially parallel to one surface of the base material 600, but is not limited thereto.

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

[0070] According to one embodiment, two laser etching steps can be performed to form a stepped surface on the side surface of the composition coated portion 610. For example, the first laser etching step can etch the active material applied to the region in contact with the first boundary portion 602, and then the second laser etching step can etch the active material applied to the region in contact with the second boundary portion 604. Alternatively, the first laser etching step can etch the active material applied to the region in contact with the second boundary portion 604, and then the second laser etching step can etch the active material applied to the region in contact with the first boundary portion 602.

[0071] In one embodiment, the laser irradiation area and laser irradiation depth of the region etched by the first laser etching step and the second laser etching step can be different from each other. Furthermore, the laser output intensity for laser etching in the first laser etching step and the second laser etching step can be different from each other. By controlling the laser output intensity for laser etching in each laser etching step to be different from each other, the heat-affected zone can be controlled. An example of forming a stepped surface 616 on the side surface of the composition-coated portion by the laser etching step will be described in detail in Figure 7.

[0072] This configuration allows for the formation of a step at the boundary between the heat-affected zone (HZ) of the composition-coated portion 610 and the uncoated portion 620. This increases the contact area between the heat-affected zone of the composition-coated portion 610 and the separator during subsequent battery assembly processes. At the same time, it is possible to maintain the flatness of the active material at the boundary between the HZ and uncoated portions 620 while simultaneously reducing the risk of damage to the separator.

[0073] Figure 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 can be formed by laser etching a portion of the composition-coated portion 710. At this time, a stepped surface 716 can be formed on the side surface of the composition-coated portion 710 at the point where the composition-coated portion 710 and the uncoated portion 720 come into contact. For example, the side surface 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 steps. For example, the first side wall 712 is formed by the first laser etching step, and the second side wall 714 and the stepped surface 716 connecting both side walls are formed by the second laser etching step.

[0075] According to one embodiment, 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 the depth (Δh1 + Δh2) from the surface (h3) of the composition coated portion 710 to the surface (h1) of the substrate.

[0076] Subsequently, a second laser etching step etches the area corresponding to the uncoated portion 720 with a second irradiation area 740 and a second depth. The second depth may be the depth (Δh2) from the surface (h3) of the composition coated portion 710 to the surface (h2) of a predetermined stepped surface 716.

[0077] According to one embodiment, the second irradiation area 740 may include the first irradiation area 730 and at the same time be larger than the first irradiation area 730. The difference between the second irradiation area 740 and the first irradiation area 730 can be used to determine the width of the stepped surface 716 formed on the side surface of the composition coated portion 710.

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

[0079] According to one embodiment, a first laser etching step, in which the surface of the composition-coated portion 710 is etched to a first depth, can form a first side wall 712 on the side surface of the composition-coated portion 710. The first side wall 712 can 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 stepped 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 step in which etching is performed from the surface of the composition coated portion 710 to a second depth. 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 thereto. The stepped surface 716 connecting the first side wall 712 and the second side wall 714 can be formed substantially parallel to one surface of the substrate, but is not limited thereto.

[0081] Figure 7 illustrates that a second laser etching step is performed after a first laser etching step, but the order of the laser etching steps is not limited to this. For example, in the second laser etching step, the area corresponding to the uncoated portion 720 is etched with a second irradiation area 740 and a second depth. The second depth may be the depth (Δh2) from the surface (h3) of the composition coated portion 710 to the surface (h2) of a predetermined stepped surface. Subsequently, in the first laser etching step, the area corresponding to the uncoated portion 720 is etched with a first irradiation area 730 and a first depth. The first depth may be the depth (Δh1) from the surface (h2) of a predetermined stepped 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 parts 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 area, laser etching can also be performed only on areas where the irradiation areas for each laser etching process do not overlap.

[0083] Alternatively, multiple laser etching processes can be performed on overlapping etching areas that occur during multiple laser etching steps.

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

[0085] In one embodiment, the first point (X1) is the point where the surface of the coated portion of the composition and the second side wall come into contact, and the second point (X2) may be the point where the second side wall and the stepped surface come into contact. Furthermore, the third point (X3) may be the point where the stepped surface and the first side wall come into contact, and the fourth point (X4) may be the point where the first side wall and the surface of the substrate come into contact. The surface of the substrate that the second side wall comes into contact with may be an uncoated portion.

[0086] In 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 and second side walls formed on the side surface 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 between the first side wall and one surface of the substrate, and the angle between the second side wall and one surface of the substrate may be different from each other, but are not limited to this.

[0087] The numerical values ​​for the width and height of the first side wall, second side wall, and stepped surface shown in Graph 800 are merely examples and are not limited thereto. For example, although it is shown that the overall width of the side surface of the composition coated area is approximately 0.117 mm, it is not limited to this, and the overall width of the side surface can be determined to be around 0.1 mm.

[0088] Figure 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 portion 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 in the area where the composition-coated portion 910 and the uncoated portion 920 are in contact. For convenience of explanation, Figure 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 may 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 steps. For example, the first side wall 912 is formed by the first laser etching step, the first stepped surface 913 and the second side wall 914 are formed by the second laser etching step, and the second stepped surface 915 and the third side wall 916 are formed by the third laser etching step.

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

[0091] According to one embodiment, the second irradiation area 940 may include the first irradiation area 930 and be larger than the first irradiation area 930. The width of the first stepped surface 913 can be determined by the difference between the second irradiation area 940 and the first irradiation area 930. The third irradiation area 950 may include the second irradiation area 940 and be larger than the second irradiation area 940. The width of the second stepped surface 915 can be determined by the difference between the third irradiation area 950 and the second irradiation area 940.

[0092] According to one embodiment, the laser output intensities for the first, second, and third laser etching steps may differ from each other. For example, the laser output intensity for the first laser etching step, which etches to a first depth, may be greater than the laser output intensity for the second laser etching step, which etches to a second depth that is shallower than the first depth. Also, the laser output intensity for the second laser etching step, which etches to a second depth, may be greater than the laser output intensity for the third laser etching step, which etches to a third depth that is shallower than the second depth.

[0093] According to one embodiment, a first laser etching step, in which the surface of the composition-coated portion 910 is etched to a first depth, can form a first side wall 912 on the side surface of the composition-coated portion 910. The first side wall 912 can 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 second laser etching step, in which the surface of the composition-coated portion 910 is etched to a second depth, can form a first stepped surface 913 and a second side wall 914 on the side surface of the composition-coated portion 910. The second side wall 914 can be formed at an angle of 80° to 90° with respect to one surface of the substrate, but is not limited thereto. The first stepped surface 913 connecting the first side wall 912 and the second side wall 914 can be formed substantially parallel to one surface of the substrate, but is not limited thereto.

[0095] According to one embodiment, a third laser etching step, in which the surface of the composition-coated portion 910 is etched to a third depth, can form a second stepped surface 915 and a third side wall 916 on the side surface of the composition-coated portion 910. The third side wall 916 can be formed at an angle of 80° to 90° with respect to one surface of the substrate, but is not limited thereto. The second stepped surface 915 connecting the second side wall 914 and the third side wall 916 can be formed substantially parallel to one surface of the substrate, but is not limited thereto.

[0096] Figure 9 illustrates that a second laser etching step is performed after the first laser etching step, and a third laser etching step is performed after the second laser etching step; however, the order of the laser etching steps is not limited to this. For example, in the third laser etching step, the area corresponding to the uncoated portion 920 is etched with a third irradiation area 950 and a third depth. The third depth may be the depth (Δh3) from the surface (h4) of the composition coated portion 910 to the surface (h3) of a predetermined second step surface. Subsequently, in the second laser etching step, the area corresponding to the uncoated portion 920 is etched with a second irradiation area 940 and a second depth. The second depth may be the depth (Δh2) from the surface (h3) of a predetermined second step surface to the surface (h2) of the first step surface. Subsequently, in the first laser etching step, the area corresponding to the uncoated portion 920 is etched with a first irradiation area 930 and a first depth. The first depth may be the depth (Δh1) from the surface (h2) of a predetermined first stepped surface to the surface (h1) of the substrate.

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

[0098] Figure 10 is an enlarged perspective view showing an uncoated portion according to another embodiment of the present disclosure. Components described or duplicated in Figure 7 are omitted in Figure 10.

[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 steps. For example, the first side wall 1012 can be formed by the first laser etching step, and the second side wall 1014 and the stepped surface 1016 can be formed by the second laser etching step.

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

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

[0102] In one embodiment, the second irradiation area 1040 may include the first irradiation area 1030 and be larger than the first irradiation area 1030. For example, as shown in Figure 10, if 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 stepped 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] Figure 11 shows an example in which uncoated portions 1120_1 and 1120_2 are formed on both sides of a substrate according to one embodiment of the present disclosure. According to one embodiment, an electrode for a secondary battery is manufactured by coating an active material onto a substrate in the form of a thin metal film. At this time, the active material is coated evenly on both sides of the substrate. For example, a first composition coated portion 1100_1 is formed on the first surface of the substrate by coating the first active material, and a second composition coated portion 1100_2 is formed on the second surface, which is the opposite side of the first surface, by coating the second active material. The substrate coated with the active material is rolled by a roll press process, and uncoated portions can be formed on the rolled substrate.

[0104] According to one embodiment, an uncoated portion of an electrode can be formed by etching a portion of the composition-coated portion. Specifically, in a substrate coated with an active material, the region corresponding to the uncoated portion can be selectively laser-etched. For example, an uncoated portion can be formed by etching the first composition-coated portion 1100_1 formed on the first surface of the substrate. With a laser etching apparatus, a plurality of uncoated portions can be continuously formed on the substrate as the first surface of the substrate moves along a first direction. Subsequently, a plurality of uncoated portions can be continuously formed on the substrate as the second surface of the substrate moves along a second direction. The second surface corresponds to the surface opposite to the first surface on the substrate.

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

[0106] In Figure 11, for the sake of explanation, the direction of travel of the first surface of the substrate and the direction of travel of the second surface of the substrate are shown to be opposite to each other, but the invention is not limited to this.

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

[0108] Figure 12 shows a laser etching apparatus with six laser heads, but it is not limited to this configuration. Also, Figure 12 shows an uncoated area formed by the laser etching apparatus that is approximately square, but it is not limited to this configuration, and the shape and size of the uncoated area can be appropriately changed depending on the design of the electrode to be manufactured.

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

[0110] Subsequently, the first region of the first composition coating can be etched to form a first uncoated area in which one surface of the substrate is exposed (S1320). For example, the first region of the first composition coating can be laser etched. According to one embodiment, multiple first regions of the first composition coating can be etched simultaneously. Subsequently, the substrate can be notched with respect to the etched first regions of the first composition coating to form taps.

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

[0112] Furthermore, 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 greater than the second depth. Also, the laser output intensities for laser etching in the first laser etching step and the second laser etching step may be different from each other.

[0113] According to one embodiment, the process may further include the step of forming a second composition coating portion containing an active material on the other surface of the substrate. In addition, multiple second regions of the second composition coating portion can be etched in order to form a second uncoated portion on the other surface of the substrate that is exposed. At this time, the side portion of the second composition coating portion that is in contact with the second uncoated portion may also have a stepped surface. Furthermore, the second uncoated portion can be formed at a position corresponding to the first uncoated portion.

[0114] Although the present invention has been described above with reference to limited embodiments and drawings, it is understood that the invention is not limited thereto, and that various modifications and variations are possible within the equivalent scope of the technical concept and claims of the present invention by persons with ordinary skill in the art to which the present invention pertains. [Explanation of symbols]

[0115] 10 Electrode assembly 11 Positive electrode 11a Uncoated part of the positive electrode 12 Negative electrode 12a Uncoated part of the negative electrode 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. Substrate and A first composition coating portion containing an active material is arranged on one surface of the substrate, The substrate includes a first uncoated portion located at the edge of one surface of the substrate, where the substrate is exposed and a tap is formed, The first side surface of the first composition-coated portion that contacts the first uncoated portion has a first side wall and a second side wall that are substantially perpendicular to one surface of the substrate and a stepped surface connecting the first side wall and the second side wall, and a heat-affected zone is formed on the first side wall, the second side wall and the stepped surface, and the notched first uncoated portion is an electrode that contacts the first side surface of the first composition-coated portion.

2. The first side portion includes a first side wall formed at a first angle with respect to one surface of the substrate, and a second side wall formed at a second angle with respect to one surface of the substrate. The stepped surface connects the first side wall and the second side wall, The electrode according to claim 1, wherein the first side wall is in contact with the first uncoated portion.

3. The electrode according to claim 2, wherein each of the first angle and the second angle is 80° to 90°.

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

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

6. A second composition coating portion is disposed on the other side of the substrate, The present invention further includes a second uncoated portion on the other side of the aforementioned substrate, in which the substrate is exposed. The electrode according to claim 1, wherein the second side surface of the second composition-coated portion that contacts the second uncoated portion has a stepped surface.

7. The electrode according to claim 6, wherein the second uncoated portion is formed at a position corresponding to the first uncoated portion.

8. The electrode according to claim 7, wherein the substrate includes a plurality of first uncoated portions and a plurality of second uncoated portions.

9. The first electrode and The second electrode and The system includes a separator disposed between the first electrode and the second electrode, The first electrode includes a substrate having uncoated portions disposed at both ends, a first composition coating portion containing a first active material disposed on one surface of the substrate, and a second composition coating portion containing a second active material disposed on the other surface of the substrate. The uncoated portion exposes the substrate and forms a tap. The electrode assembly wherein the first side surface of the first composition-coated portion that contacts the uncoated portion has a first side wall and a second side wall substantially perpendicular to one surface of the substrate and a stepped surface connecting the first side wall and the second side wall, a heat-affected zone is formed on the first side wall, the second side wall and the stepped surface, and the notched uncoated portion is in contact with the first side surface of the first composition-coated portion.

10. The electrode assembly according to claim 9, wherein the second side surface of the second composition-coated portion that contacts the uncoated portion has a stepped surface.

11. The steps include forming a first composition coating portion containing an active material on one surface of the substrate, The step of etching a first region of the first composition-coated portion to form a tap in order to form a first uncoated portion in which the edge of one surface of the substrate is exposed, A method for manufacturing an electrode for a secondary battery, wherein the side surface of the first composition-coated portion that contacts the first uncoated portion has a first side wall and a second side wall that are substantially perpendicular to one surface of the substrate by laser etching of the active material, and a stepped surface that connects the first side wall and the second side wall, and the notched first uncoated portion is in contact with the side surface of the first composition-coated portion.

12. The method for manufacturing an electrode for a secondary battery according to claim 11, wherein the etching step includes a step of laser etching a first region of the first composition coated portion.

13. The etching step described above is The first step is to laser etch the first region with a first irradiation area using a first laser etching process, A method for manufacturing an electrode for a secondary battery according to claim 12, comprising the step of laser etching the first region with a second irradiation area different from the first irradiation area by a second laser etching step.

14. The method for manufacturing an electrode for a secondary battery according to claim 13, wherein the first irradiation area is smaller than the second irradiation area.

15. The first irradiation area has a first depth, The second irradiation area has a second depth, The method for manufacturing an electrode for a secondary battery according to claim 13, wherein the first depth is deeper than the second depth.

16. The method for manufacturing an electrode for a secondary battery according to claim 13, wherein the laser output intensities for laser etching in the first laser etching step and the second laser etching step are different from each other.

17. The method for manufacturing an electrode for a secondary battery according to claim 11, wherein the etching step includes a step of simultaneously etching a plurality of first regions of the first composition coated portion.

18. The method for manufacturing an electrode for a secondary battery according to claim 11, further comprising the step of notching the substrate with respect to the first region to form a tap.

19. The steps include forming a second composition coating portion containing an active material on the other surface of the substrate, The method further includes the step of etching a plurality of second regions of the second composition-coated portion in order to form a second uncoated portion in which the other side of the substrate is exposed, The side surface of the second composition-coated portion that comes into contact with the second uncoated portion has a stepped surface. The method for manufacturing an electrode for a secondary battery according to claim 11, wherein the second uncoated portion is formed at a position corresponding to the first uncoated portion.

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