Method for manufacturing electrodes and electrodes manufactured thereby

Abstract

A method for manufacturing an electrode according to one embodiment of the present invention may include the steps of: coating at least one surface of a current collector containing a metal material with a first coating layer containing an active material; coating at least one surface of the first coating layer with a plurality of second coating layers containing an active material; and rolling the current collector, the first coating layer, and the second coating layer by a rolling mill.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0179051 filed on December 11, 2023, and all the contents disclosed in the corresponding Korean patent application document are incorporated herein by reference in their entirety.

[0002] The present invention relates to a method for manufacturing an electrode and an electrode manufactured thereby.

Background Art

[0003] In order to solve environmental pollution caused by the use of petroleum resources and the problem of insufficient energy sources due to the depletion of petroleum resources, research and development on power generation based on environmentally friendly energy sources have been carried out. In particular, research on secondary batteries that can be repeatedly charged and discharged and have high utilization has been actively conducted, and research has been carried out on various aspects such as the materials, structures, processes, and stabilities of secondary batteries.

[0004] Generally, types of secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries. Such secondary batteries are not only used in small products such as digital cameras, P-DVDs, MP3Ps, mobile phones, PDAs, portable game devices, power tools, and electric bicycles, but also in large products that require high power such as electric vehicles and hybrid vehicles, as well as in power storage devices for storing surplus generated power and new / renewable energy, and backup power storage devices.

[0005] To manufacture such secondary batteries, first, an electrode active material slurry is applied to a positive electrode current collector and a negative electrode current collector to manufacture a positive electrode and a negative electrode, and these are laminated on both sides of a separator to form an electrode assembly of a predetermined shape. Also, the electrode assembly is housed in a battery case, an electrolyte is injected, and then sealed.

[0006] Rechargeable batteries manufactured in this way are used in a variety of ways across all sectors of industry. However, research is actively being conducted to increase the capacity of rechargeable batteries in order to further enhance their performance. One typical method for increasing the capacity of rechargeable batteries is to apply high pressure to the electrodes during the manufacturing process of electrode assemblies, thereby increasing the density of the electrodes.

[0007] However, a problem arises in electrodes that have been stretched under high pressure: the electrolyte impregnation rate decreases. When the electrolyte impregnation rate is low, the electrolyte cannot reach the electrode active material particles quickly, so lithium ions cannot move smoothly, which can degrade the performance of the secondary battery. In addition, when the electrolyte impregnation rate is low, the impregnation rate is slow, which can increase the time required to manufacture secondary batteries, resulting in poor productivity.

[0008] Therefore, there is a need for technology to manufacture secondary batteries that have both high capacity and excellent electrolyte impregnation properties. [Overview of the project] [Problems that the invention aims to solve]

[0009] One problem that the present invention aims to solve is to provide a method for manufacturing an electrode, in which a plurality of second coating layers are coated onto a first coating layer so as to form regions in which the active material density and electrolyte impregnation properties differ from each other, and an electrode manufactured by this method. [Means for solving the problem]

[0010] A method for manufacturing an electrode according to one embodiment of the present invention may include the steps of: coating at least one surface of a current collector containing a metal material with a first coating layer containing an active material; coating at least one surface of the first coating layer with a plurality of second coating layers containing an active material; and rolling the current collector, the first coating layer, and the second coating layer by a rolling mill.

[0011] In the step of coating the second coating layer, the plurality of second coating layers may be coated at predetermined intervals from each other.

[0012] In the step of being rolled by the rolling mill, a first active material layer in which both the first coating layer and the second coating layer are rolled together, and a second active material layer in which the first coating layer is rolled alone can be formed.

[0013] In the step of rolling by the rolling mill, the active material density of the first active material layer can be made higher than that of the second active material layer.

[0014] In the step of being rolled by the rolling mill, the electrolyte impregnation properties of the second active material layer can be made higher than those of the first active material layer.

[0015] In the step of being rolled by the rolling mill, the electrodes, the first coating layer, and the second coating layer can be rolled such that the outer surface of the first active material layer and the outer surface of the second active material layer are located on the same plane.

[0016] In the step of applying the second coating layer, the second coating layer may be applied along the width direction of the current collector.

[0017] An electrode according to another embodiment of the present invention includes a current collector made of a metal material and an active material layer coated on at least one surface of the current collector, wherein the active material layer may include a first active material layer and a second active material layer alternately positioned with the first active material layer and having a lower active material density than the first active material layer.

[0018] The electrolyte impregnation properties of the second active material layer can be made higher than those of the first active material layer.

[0019] The first active material layer and the second active material layer can be formed along the width direction of the current collector.

Advantages of the Invention

[0020] According to a preferred embodiment of the present invention, by coating a plurality of second coating layers on the first coating layer so that regions having different active material densities and electrolyte impregnation properties are formed, a high-capacity electrode can be manufactured, and an electrode excellent in electrolyte impregnation property can be manufactured.

[0021] In addition, effects that can be easily predicted by those skilled in the art from the configuration according to the preferred embodiment of the present invention can be included.

Brief Description of the Drawings

[0022] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described later, serve to further understand the technical idea of the present invention. The present invention should not be construed as being limited only to the matters described in such drawings.

[0023] [Figure 1] It is a flowchart of a method for manufacturing an electrode according to an embodiment of the present invention. [Figure 2] It is a perspective view of a state where a second coating layer is coated on the outer surface of a first coating layer according to a method for manufacturing an electrode according to an embodiment of the present invention. [Figure 3] It is a cross-sectional view of a state where a first coating layer, a second coating layer, and a current collector are rolled according to a method for manufacturing an electrode according to an embodiment of the present invention. [Figure 4] It is a perspective view of an electrode according to another embodiment of the present invention. [Figure 5] It is a perspective view of an electrode according to still another embodiment of the present invention.

Modes for Carrying Out the Invention

[0024] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings, so that they can be easily implemented by a person with ordinary skill in the art to which the present invention pertains. However, the present invention can be realized in a variety of different forms and is not limited or restricted by the following embodiments.

[0025] For the purpose of clearly describing the present invention, detailed descriptions of related known technologies that are irrelevant to the description or that could obscure the gist of the invention have been omitted. In this specification, when assigning reference numerals to components in each drawing, the same or similar reference numerals are used throughout the specification for components that are the same or similar.

[0026] Furthermore, the terms and words used in this specification and in the claims should not be interpreted in a manner limited to their general or dictionary meanings, but rather should be interpreted 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.

[0027] Figure 1 is a flowchart of a method for manufacturing an electrode according to one embodiment of the present invention.

[0028] Referring to Figure 1, an electrode 1 can be manufactured by a method for manufacturing an electrode according to one embodiment of the present invention. For example, according to the electrode manufacturing method, a coating layer containing an active material can be coated on at least one surface of the current collector 10. With the coating layer coated on at least one surface of the current collector 10, the current collector 10 and the coating layer can be rolled by a rolling mill to manufacture an electrode 1 according to another embodiment of the present invention, which will be described later.

[0029] Specifically, by a method for manufacturing electrodes, a first coating layer 11a and a second coating layer 11b are sequentially coated on at least one surface of the current collector 10, and then the current collector 10, the first coating layer 11a, and the second coating layer 11b can be rolled by a rolling mill.

[0030] The current collector 10 can refer to a thin film made of a plate-like material, which may include a structure that is wound like a roll or cut and laminated, and is used to form an electrode assembly. The current collector 10 can play a role in transferring electrons from the outside to the active material or releasing them from the active material to the outside so that an electrochemical reaction can take place during the charging and discharging process of the secondary battery.

[0031] The current collector 10 may include a metallic material. Specifically, the material of the current collector 10 may differ depending on the type of electrode plates, which are divided into a negative electrode and a positive electrode. For the negative electrode current collector 10, copper foil is mainly used as it is stable in electrochemical reactions within the operating range of the carbon electrode 1 and has good electrical conductivity. On the other hand, for the positive electrode current collector 10, aluminum foil is used as it is stable in electrochemical reactions even at high potentials and has good electrical conductivity.

[0032] Depending on the type of electrode plate, the manufacturing method of the current collector 10 may differ. Aluminum foil can be manufactured by rolling out thin aluminum scraps. On the other hand, copper foil can be manufactured by dissolving copper wire in an electrolytic plating process.

[0033] The first coating layer 11a and the second coating layer 11b may contain an active material slurry. An active material slurry may refer to a substance applied to the outer surface of the current collector 10 that generates electrical energy through a chemical reaction. The active material slurry may also contain an active material, a conductive material, and a binder. In other words, the first coating layer 11a and the second coating layer 11b may contain an active material.

[0034] The active material can generate electrical energy through chemical reactions. The active material may include a positive electrode active material or a negative electrode active material.

[0035] The positive electrode active material includes, for example, layered compounds such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and compounds substituted with one or more transition metals; lithium manganese oxides such as LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiFe3O4, V2O5, Cu2V2O7; and the chemical formula LiNi 1-x M x O2 (M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, x = 0.01 to 0.3) nickel-site type lithium nickel oxide represented by; the chemical formula LiMn 2-x M x O2 (M = Co, Ni, Fe, Cr, Zn or Ta, x = 0.01 to 0.1) or lithium manganese composite oxide represented by Li2Mn3MO8 (M = Fe, Co, Ni, Cu or Zn); LiNi x Mn 2-x O4 spinel-structured lithium manganese composite oxide represented by; Li x Lithium transition metal phosphates such as CoPO4 (0.5 < x < 1.3), LiMn2O4 in which part of the Li in the chemical formula is substituted with alkaline earth metal ions; disulfide compounds; Fe2(MoO4)3, etc. can be included, but are not limited to only these.

[0036] The negative electrode active material includes carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, amorphous carbon; metallic compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy or Al alloy; SiO x(0 < x < 2), metal oxides such as SnO2, vanadium oxides, and lithium vanadium oxides that can be coated and uncoated with lithium; compounds containing the metal compound and a carbonaceous material such as lithium titanate, metal composite oxides containing two or more metals, or Si-C composites or Sn-C composites, etc. can be mentioned, and any one or a mixture of two or more of these can be used. Further, a thin film of metallic lithium may be used as the negative electrode active material. Furthermore, all carbon materials such as low-crystalline carbon and high-crystalline carbon can be used. Representative examples of low-crystalline carbon are soft carbon and hard carbon, and representative examples of high-crystalline carbon are amorphous, plate-like, flaky, spherical or fibrous natural graphite or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbons such as petroleum or coal tar pitch derived cokes.

[0037] The conductive material can promote the movement of electrons between the positive electrode active material and the negative electrode active material. For example, the conductive material contains a small amount of fine powder carbon, can improve the conductivity between the active material particles or the current collector 10, and can prevent the binder from acting as an insulator.

[0038] The conductive material is not particularly limited, but specific examples include carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; graphite such as natural graphite or artificial graphite; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives. One of these can be used alone or as a mixture of two or more. The conductive material may be present in an amount of 1% to 30% by weight, more specifically 1% to 10% by weight, and more specifically 1% to 5% by weight, relative to the total weight of the solid content of the active material slurry.

[0039] A binder can bond the active material and the conductive material together. For example, the binder can function to allow the active material and the conductive material to mix easily with each other. This allows the binder to function to ensure that the active material and the conductive material are uniformly applied to the current collector 10. Repeated charging and discharging of a secondary battery weakens the bond between the active material and the conductive material, causing volume changes in the current collector 10 and reducing the lifespan and function of the secondary battery. However, a binder can enhance the bonding strength between the active material and the conductive material, better addressing this problem.

[0040] The binder is not particularly limited, but specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one or more of these can be used. The binder may be present in the active material slurry at an amount of 1% to 30% by weight, more specifically 1% to 10% by weight, and more specifically 1% to 5% by weight, based on the total weight of the solids.

[0041] According to the electrode manufacturing method, multiple coating layers are applied to the outer surface of the current collector, and the second coating layer 11b is coated with a specific structure, thereby forming multiple regions on the electrode 1 with different active material densities and electrolyte impregnation properties. In other words, regions with relatively higher active material densities and regions with relatively higher electrolyte impregnation properties can be formed on the electrode 1.

[0042] Figure 2 is a perspective view showing how the second coating layer 11b is coated on the outer surface of the first coating layer 11a according to a method for manufacturing an electrode according to one embodiment of the present invention.

[0043] Referring to Figure 2, the method for manufacturing the electrode may include the steps of coating a first coating layer 11a (S10), coating a second coating layer 11b (S20), and rolling by a rolling mill (S30).

[0044] In step (S10) in which the first coating layer 11a is applied, the first coating layer 11a can be applied to at least one surface of the current collector 10, which includes a metal material. For example, the first coating layer 11a can be applied to one surface of the current collector 10 or to both surfaces of the current collector 10. Furthermore, the first coating layer 11a can be formed only on a specific portion of the current collector 10, rather than on the entire current collector 10.

[0045] The first coating layer 11a can be coated on at least one surface of the current collector 10 along its longitudinal direction. For example, the first coating layer 11a can be coated on the outer surface of the current collector 10 such that its longitudinal direction is parallel to the longitudinal direction of the current collector 10.

[0046] When electrode 1 is manufactured, a portion of the current collector 10 on which the first coating layer 11a is formed can become a retaining portion containing the active material slurry. The other portion of the current collector 10 on which the first coating layer 11a is not formed can become a plain portion that does not contain the active material slurry.

[0047] In step (S20) in which the second coating layer 11b is applied, multiple second coating layers 11b containing active material can be applied to at least one surface of the first coating layer 11a. For example, one surface of the first coating layer 11a can be coated with the second coating layer 11b, and the other surface of the first coating layer 11a can be coated onto the current collector 10. In other words, the upper surface of the current collector 10 can be coated with the first coating layer 11a, and the upper surface of the first coating layer 11a can be coated with the second coating layer 11b.

[0048] In step (S20) in which the second coating layer 11b is applied, multiple second coating layers 11b can be applied at intervals from one another. For example, the second coating layer 11b can be applied along the width direction of the current collector 10, and multiple second coating layers 11b can be formed spaced apart from each other at predetermined intervals. That is, the longitudinal direction of the second coating layer 11b may be parallel to the width direction of the current collector 10. In other words, multiple second coating layers 11b can be applied to the outer surface of the first coating layer 11a in a stripe-like shape.

[0049] However, the direction in which the second coating layer 11b is coated is not limited to this, and the second coating layer 11b may be coated perpendicular to the width direction of the current collector 10.

[0050] The second coating layer 11b can be formed so as to be separated from both ends of the first coating layer 11a. For example, a pair of second coating layers 11b located at the outermost edge of a plurality of second coating layers 11b can be separated from both ends of the first coating layer 11a by a predetermined distance.

[0051] With this structure of the second coating layer 11b, the second coating layer 11b is not formed at both ends of the first coating layer 11a. This prevents the formation of a high concentration of active material slurry at both ends of the first coating layer 11a, thereby preventing problems such as sliding of the active material slurry.

[0052] In step (S30), the current collector 10, the first coating layer 11a, and the second coating layer 11b can be rolled by the rolling mill. For example, the rolling mill may include a roller press.

[0053] Specifically, a current collector 10 coated with a first coating layer 11a and a second coating layer 11b can move between a pair of roller presses. The first coating layer 11a, the second coating layer 11b, and the current collector 10 can be rolled by being pressed by the pair of roller presses.

[0054] The rolling process of such a rolling mill increases the density of the manufactured electrode 1, thereby increasing the adhesion and bonding force between the current collector 10 and the active material slurry. Furthermore, the rolling process introduces directionality into the crystal structure of the electrode 1, allowing for the generation of electrical energy from the electrode 1 with greater output. As a result, the performance of the manufactured electrode 1 can be enhanced through the rolling process.

[0055] Figure 3 is a cross-sectional view showing the rolling of the first coating layer 11a, the second coating layer 11b, and the current collector 10 according to a method for manufacturing an electrode according to one embodiment of the present invention.

[0056] Referring to Figure 3, in the step (S30) in which the material is rolled by a rolling mill, a first active material layer 110 can be formed in which both the first coating layer 11a and the second coating layer 11b are rolled together, and a second active material layer 111 can be formed in which the first coating layer 11a is rolled alone. For example, when multiple second coating layers 11b are coated on one surface of the first coating layer 11a at predetermined intervals from each other, the first coating layer 11a and the second coating layer 11b are rolled by a rolling mill, thereby forming an overlapping region of the first coating layer 11a and the second coating layer 11b. In other words, the first active material layer 110 can be formed only on a specific portion of the first coating layer 11a to which the second coating layer 11b is coated.

[0057] Multiple first active material layers 110 and second active material layers 111 can be formed, and these multiple first active material layers 110 and multiple second active material layers 111 can be formed along the current collector 10. For example, the first active material layers 110 and second active material layers 111 can be formed alternately along the longitudinal direction of the current collector 10.

[0058] Furthermore, the first active material layer 110 and the second active material layer 111 can be formed along the width direction of the current collector 10. In other words, the first active material layer 110 and the second active material layer 111 can be formed in a direction parallel to the width direction of the current collector 10.

[0059] In step (S30) of being rolled by a rolling mill, the electrode 1, the first coating layer 11a, and the second coating layer 11b can be rolled such that the outer surface of the first active material layer 110 and the outer surface of the second active material layer 111 are located on the same plane.

[0060] In the step of rolling by a rolling mill (S30), the active material density of the first active material layer 110 can be higher than that of the second active material layer 111. In other words, the first active material layer 110 is the portion formed by rolling together the first coating layer 11a and the second coating layer 11b, and unlike the second active material layer 111, which is formed from the first coating layer 11a alone, it can contain a larger amount of active material. That is, since the first active material layer 110 contains a larger amount of active material for the same volume, the active material density of the first active material layer 110 can be higher than that of the second active material layer 111.

[0061] Therefore, unlike the case where only the first coating layer 11a is coated on the current collector 10 and then rolled, the second coating layer 11b is secondarily coated on the first coating layer 11a before rolling. As a result, according to the electrode manufacturing method of one embodiment of the present invention, a higher density active material region is formed, and an electrode 1 with higher capacity and higher performance can be manufactured.

[0062] Conversely, in the step of rolling by a rolling mill (S30), the electrolyte impregnation of the second active material layer 111 can be made higher than that of the first active material layer 110. In other words, the second active material layer 111 is a layer formed only of the first coating layer 11a that does not overlap with the second coating layer 11b, and can be impregnated with electrolyte more effectively.

[0063] Therefore, since the second active material layer 111 has relatively high electrolyte impregnation properties, the electrolyte impregnation rate is increased during the manufacturing of secondary batteries using the electrode 1, thereby increasing the productivity of secondary batteries. In addition, due to the second active material layer 111's high electrolyte impregnation properties, the electrolyte can reach the electrode active material particles quickly, and lithium ions can move more smoothly, thus improving the performance of secondary batteries manufactured using the electrode 1.

[0064] As a result, by manufacturing an electrode according to one embodiment of the present invention, an electrode 1 can be manufactured by forming a first active material layer 110 and a second active material layer 111, thereby producing an electrode 1 with high capacity and excellent electrolyte impregnation properties.

[0065] The following describes an electrode 1 according to another embodiment of the present invention. As described above, an electrode 1 according to another embodiment of the present invention can be manufactured by the electrode manufacturing method according to one embodiment of the present invention.

[0066] Figure 4 is a perspective view of an electrode according to another embodiment of the present invention.

[0067] Referring to Figure 4, the electrode 1 can be manufactured by coating a current collector 10 with an active material layer 11. For example, the current collector 10 may include a metallic material, and the active material layer 11 may be coated on at least one surface of the current collector 10.

[0068] The active material layer 11 may include a first active material layer 110 and a second active material layer 111 that alternates with the first active material layer 110. For example, multiple first active material layers 110 and second active material layers 111 may be formed, and multiple first active material layers 110 and multiple second active material layers 111 may be formed along the current collector 10. The first active material layers 110 and second active material layers 111 may be formed alternately with each other along the longitudinal direction of the current collector 10.

[0069] Furthermore, the first active material layer 110 and the second active material layer 111 can be formed along the width direction of the current collector 10. In other words, the first active material layer 110 and the second active material layer 111 can be formed in a direction parallel to the width direction of the current collector 10.

[0070] The first active material layer 110 and the second active material layer 111 can be formed on the outer surface of the current collector 10 such that their outer surfaces lie on the same plane.

[0071] The active material density of the first active material layer 110 can be made higher than that of the second active material layer 111. Furthermore, the electrolyte impregnation properties of the second active material layer 111 can be made higher than those of the first active material layer 110.

[0072] Figure 5 is a perspective view of an electrode according to yet another embodiment of the present invention.

[0073] Referring to Figure 5, the electrode 1 according to yet another embodiment of the present invention may include a first active material layer 110 formed along the longitudinal direction of the current collector 10. For example, the first active material layer 110 according to yet another embodiment of the present invention may be formed parallel to the longitudinal direction of the current collector 10. Thus, the second active material layer 111 may also be formed parallel to the longitudinal direction of the current collector 10. In other words, the first active material layer 110 and the second active material layer 111 according to yet another embodiment of the present invention may be formed perpendicular to the width direction of the current collector 10.

[0074] The above description is merely illustrative of the technical concept of the present invention, and any person with ordinary skill in the art to which the present invention belongs can make various modifications and alterations without departing from the essential characteristics of the present invention.

[0075] Therefore, the embodiments disclosed in this invention are for illustrative purposes only and not to limit the technical concept of the invention, and the scope of the technical concept of the invention is not limited by such embodiments.

[0076] The scope of protection of this invention shall be interpreted in accordance with the following claims, and all technical ideas within an equivalent scope shall be interpreted as being included within the scope of the rights of this invention. [Explanation of Symbols]

[0077] 1 electrode 10 Current collector 11 Active material layer 110 First active material layer 111 Second active material layer 11a First coating layer 11b Second coating layer

Claims

1. A step in which a first coating layer containing an active material is coated on at least one surface of a current collector containing a metal material, The steps include: coating at least one surface of the first coating layer with a plurality of second coating layers containing an active material; The steps include: rolling the current collector, the first coating layer, and the second coating layer by a rolling mill; A method for manufacturing electrodes, including

2. The method for manufacturing an electrode according to claim 1, wherein, in the step of coating the second coating layer, a plurality of the second coating layers are coated so as to be spaced apart from each other.

3. In the step of being rolled by the rolling mill, A first active material layer in which both the first coating layer and the second coating layer are rolled, The first coating layer is rolled alone, and the second active material layer A method for manufacturing an electrode according to claim 2, wherein the electrode is formed.

4. The method for manufacturing an electrode according to claim 3, wherein in the step of rolling by the rolling mill, the active material density of the first active material layer is higher than the active material density of the second active material layer.

5. The method for manufacturing an electrode according to claim 3, wherein, in the step of rolling by the rolling mill, the electrolyte impregnation properties of the second active material layer are higher than those of the first active material layer.

6. The method for manufacturing an electrode according to claim 3, wherein, in the step of being rolled by the rolling apparatus, the electrode, the first coating layer, and the second coating layer are rolled such that the outer surface of the first active material layer and the outer surface of the second active material layer are located on the same plane.

7. The method for manufacturing an electrode according to claim 2, wherein in the step of coating the second coating layer, the second coating layer is coated along the width direction of the current collector.

8. A current collector containing a metal material, An active material layer coated on at least one surface of the current collector, Includes, The aforementioned active material layer is The first active material layer, A second active material layer is positioned alternately with the first active material layer and has a lower active material density than the first active material layer, Electrodes, including

9. The electrode according to claim 8, wherein the electrolyte impregnation properties of the second active material layer are higher than those of the first active material layer.

10. The electrode according to claim 8, wherein the first active material layer and the second active material layer are formed along the width direction of the current collector.

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