Electrode

Abstract

The invention provides an electrode. The electrode comprises a current collector and an electrode layer, the electrode layer is positioned on at least one surface of the current collector, and the electrode layer can comprise a cutting surface with a concave-convex shape. According to the present invention, stable electrode quality can be maintained, the problem that the generation capacity is lower than the design capacity of the battery can be improved, the charging / discharging speed of the battery can be improved, the performance degradation of the electrode can be reduced, and the life can be prolonged.

Description

Technical Field

[0001] The present invention relates to an electrode, in particular to an electrode having a long life and capable of high-speed charging. Background Art

[0002] As the demand for mobile devices such as mobile phones, smart phones, laptops, wearable devices (such as smart watches, smart glasses, head mounted displays (HMD)) increases, the demand for secondary batteries that power mobile devices is increasing. Therefore, a lot of research is being conducted on secondary batteries.

[0003] Secondary batteries can be roughly divided into a positive electrode, a negative electrode, a separator, and an electrolyte.

[0004] Secondary batteries can generate electricity through chemical reactions in which lithium ions move between the positive electrode active material and the negative electrode active material. Specifically, the lithium ions of the positive electrode active material move to the negative electrode, thereby charging the secondary battery, and the lithium ions of the negative electrode active material return to the positive electrode active material and release energy, thereby enabling discharge. In this way, lithium ions can travel back and forth between the two electrodes (positive and negative electrodes), and energy can be converted through this process, thereby enabling the charging and discharging of the secondary battery.

[0005] On the one hand, the electrolyte acts as a channel for the movement of lithium ions, and the separator prevents the positive and negative electrodes from contacting each other.

[0006] The electrode of a secondary lithium battery can be manufactured by dispersing active material and a binder to make an active material slurry, and then coating an active material layer on one surface of a current collector. When the active material slurry is coated on one surface of a current collector, a sliding phenomenon occurs. The sliding phenomenon refers to the phenomenon of diffusion of the active material slurry.

[0007] Figure 1 is a schematic diagram of an electrode in the prior art.

[0008] Reference Figure 1 The electrode 10 may include an electrode layer 12 on one surface of the current collector 11 .

[0009] On the one hand, when the current collector 11 is wet-coated, the slurry may spread, and thus, sliding portions S may be formed at both ends of the electrode layer 12 due to the sliding phenomenon. Figure 1 Only one end of the electrode layer 12 is shown in FIG. 1 , but it is also possible to form the sliding portion S at the other end.

[0010] The sliding portion S extends to both ends of the center of the electrode layer 12 and becomes thinner toward the ends of the active material layer, that is, gradually becomes thinner from the center of the active material layer toward the uncoated portion 13 where the active material layer is not formed.

[0011] On the one hand, during the rolling process, as the thickness of the center portion of the electrode 10 decreases, the area of ​​the sliding portion S formed at one end of the electrode 10 decreases to a certain extent. However, since the sliding portion S remains in a certain area, it may cause various performance degradations.

[0012] Specifically, when there is a sliding portion S, the loading amount at both ends of the active material layer is lower than that at the center portion, which may cause a problem that the capacity is lower than the designed capacity of the battery.

[0013] In addition, in the uncoated portion 13 (pole piece portion) of the electrode, the ratio of the positive electrode and the negative electrode may be reversed due to the sliding portion S, and physical isolation may occur. In addition, since it is difficult to control the sliding portion, it will be difficult to maintain stable electrode quality.

[0014] In addition, in an electrochemical device using the electrode 10 having the sliding portion S formed therein, a reversal phenomenon occurs in the capacity balance (N / P balance) between the positive electrode and the negative electrode, which causes Li precipitation and deteriorates the electrochemical device.

[0015] Therefore, there is an urgent need to develop a method for manufacturing an electrode including an electrode layer from which the sliding portion S is removed.

[0016] Prior art literature

[0017] Patent Literature

[0018] Patent Document 0001 Korean Patent Application No. 10-2022-0183678 (filed on December 23, 2022) Summary of the invention

[0019] The present invention aims to solve the above problems and other problems. The technical problem to be achieved by some embodiments of the present invention is to maintain stable electrode quality.

[0020] The technical problems to be solved by the present invention are not limited to the technical problems mentioned above, and those skilled in the art can clearly understand other technical problems not mentioned from the following description.

[0021] The electrodes of some embodiments of the present invention include: a current collector, and an electrode layer located on at least one surface of the current collector; the electrode layer includes a concave-convex cutting surface.

[0022] According to some embodiments of the present invention, the cut surface may include a plurality of concave portions and a plurality of convex portions repeatedly formed in a width direction of the electrode.

[0023] According to some embodiments of the present invention, each of the plurality of recesses may include a curved end surface recessed toward an inner side of the electrode layer.

[0024] According to some embodiments of the present invention, two adjacent virtual circles among virtual circles extending according to the curvature formed by the end surfaces of the plurality of recesses may form surfaces that overlap with each other.

[0025] According to some embodiments of the present invention, the curvatures formed by the end surfaces of the plurality of recesses may be the same.

[0026] According to some embodiments of the present invention, each of the plurality of concave portions and the plurality of convex portions may extend in a direction perpendicular to the one surface of the current collector.

[0027] According to some embodiments of the present invention, the cut surface may include: a first cut surface; and a second cut surface located between the current collector and the first cut surface.

[0028] According to some embodiments of the present invention, the first cutting surface may include a plurality of first recesses recessed into a concave curve shape toward the inside of the electrode layer, and the second cutting surface may include a plurality of second recesses recessed into a concave curve shape toward the inside of the electrode layer.

[0029] According to some embodiments of the present invention, the first cutting surface is more recessed toward the inner side of the electrode layer than the second cutting surface, and the upper side surface of the second cutting surface can be defined as an area exposed to the upper side due to the first cutting surface being more recessed toward the inner side of the electrode layer than the second cutting surface.

[0030] According to some embodiments of the present invention, the curvature formed by each of the plurality of first recesses and the curvature formed by each of the plurality of second recesses may be the same.

[0031] According to some embodiments of the present invention, when defining heights of the first cut surface and the second cut surface in a direction toward the one surface of the current collector, the height of the first cut surface may be lower than the height of the second cut surface.

[0032] According to some embodiments of the present invention, the cut surface may be cut along a direction toward the one surface of the current collector.

[0033] According to some embodiments of the present invention, the electrode may further include an uncoated portion, wherein the uncoated portion is defined as a region on the one surface of the current collector where the electrode layer is not provided.

[0034] The technical solutions that can be obtained by the present invention are not limited to the solutions mentioned above, and those skilled in the art can clearly understand other solutions not mentioned from the following description.

[0035] The effects of the electrode of the present invention are explained below.

[0036] According to some embodiments of the present invention, stable electrode quality can be maintained, the problem of capacity being lower than the design capacity of the battery can be improved, the charging and discharging speed of the battery can be improved, and the performance degradation of the electrode can be reduced and the life of the electrode can be extended.

[0037] The effects that can be obtained by the present invention are not limited to the effects mentioned above, and those skilled in the art can clearly understand other effects not mentioned from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Various embodiments of the present invention are described with reference to the accompanying drawings, wherein similar reference numerals are used to represent similar components as a whole. In the following embodiments, for illustrative purposes, a number of specific details are described in order to provide an overall understanding of more than one embodiment. However, it is apparent that these embodiments can also be implemented without these specific details.

[0039] Figure 1 is a schematic diagram of an electrode in the prior art.

[0040] Figure 2 1 is a perspective view showing a partial etching process of an electrode layer according to some embodiments of the present invention.

[0041] Figure 3 This is a perspective view showing an example of an electrode layer on which a cut surface having a concavo-convex shape is drawn according to some embodiments of the present invention.

[0042] Figure 4 yes Figure 3 The AA' cross-sectional view shows an example of the end surface of the cutting surface portion of some embodiments of the present invention.

[0043] Figure 5 yes Figure 3 The AA' cross-sectional view shows another example of the end surface of the cutting surface portion of some embodiments of the present invention.

[0044] Figure 6 This is a stereogram showing another example of the cut surface of some embodiments of the present invention. DETAILED DESCRIPTION

[0045] Hereinafter, some embodiments of the electrode, secondary battery and battery control method of the present invention will be described in detail with reference to the accompanying drawings, wherein the same or similar components are marked with the same symbols regardless of the figure numbers, and their repeated descriptions are omitted.

[0046] References and Attachments Figure 1 In the description of one or more embodiments of the present invention, when it is determined that the specific description of the known technology confuses the main idea of ​​at least one embodiment of the present invention, its detailed description is omitted.

[0047] The terms of the present invention are defined in consideration of the functions of the present invention and may vary depending on the intention or convention of the user or the application. In addition, the drawings are only used to facilitate the understanding of one or more embodiments of the present invention. The technical concept of the present invention is not limited by the drawings and should be understood to include all changes, equivalents or alternative technical solutions included in the concept and technical scope of the present invention.

[0048] Terms including ordinal numbers such as first and second may be used to describe various constituent elements, but the constituent elements are not limited to the terms. The terms are only used to distinguish one constituent element from other constituent elements. Therefore, the first constituent element referred to below may also become the second constituent element within the technical concept of the present invention.

[0049] When it is mentioned that one component is “connected” or “connected to” another component, it is understood that it can be directly connected or connected to the other component, or other components may be present in between. On the contrary, when it is mentioned that one component is “directly connected” or “directly connected to” another component, it is understood that there are no other components in between.

[0050] Unless the context clearly indicates otherwise, a singular expression includes a plural expression. That is, when the context is unclear due to no explicit expression or explicit indication of a singular form, the singular in the present invention and claims should generally be interpreted as "one or more".

[0051] In the present invention, terms such as "include", "comprises" or "has" should be understood as being used to specify the existence of features, numbers, steps, actions, constituent elements, parts or combinations thereof recorded in the present invention, rather than excluding the existence or additional possibilities of one or more other features, numbers, steps, actions, constituent elements, parts or combinations thereof in advance.

[0052] In the present invention, the term "or" should be understood as an inclusive "or" rather than an exclusive "or". That is, unless otherwise specified or the context makes it clear, "X utilizes A or B" is intended to mean one of the naturally inclusive alternatives. That is, "X utilizes A or B" can apply to any of X utilizes A, X utilizes B, or X utilizes A and B. In addition, the term "and / or" used in the present invention should be understood to mean and include all possible combinations of more than one of the listed related items.

[0053] Unless otherwise defined, all terms (including technical terms and scientific terms) used in the present invention may be used as meanings commonly understood by those skilled in the art. Also, unless otherwise clearly defined, terms defined in commonly used dictionaries are not over-interpreted.

[0054] However, the present invention is not limited to the embodiments disclosed below, and can be implemented in various forms. Some embodiments of the present invention are provided only to enable those skilled in the art to fully understand the scope of the present invention, and the present invention is only defined by the claims. Therefore, its definition should be determined based on the entire description of the present invention.

[0055] Figure 1 is a schematic diagram of an electrode in the prior art.

[0056] Reference Figure 1 , the electrode 10 may include a current collector 11. The electrode 10 may include an electrode layer 12. The electrode layer 12 may be located on at least one surface of the current collector 11.

[0057] The electrode 10 may include an uncoated portion 13. When the electrode layer 12 is located on one surface of the current collector 11, the uncoated portion 13 may be defined as a region on one surface of the current collector 11 where the electrode layer 12 is not provided. The uncoated portion 13 may be defined as a surface portion where the electrode layer 12 is not provided and the current collector 11 is exposed. The uncoated portion 13 may be adjacent to one end of the electrode layer 12. The uncoated portion 13 may be adjacent to the sliding portion S.

[0058] In the conventional electrode 10, since the current collector 11 is wet coated, a sliding portion S is generated at both ends of the wet-coated electrode layer 12 due to the diffusion of the slurry. In an electrochemical device using the electrode 10 formed with the sliding portion S, the capacity balance (N / P balance) between the positive electrode and the negative electrode is reversed, resulting in Li precipitation, which may cause degradation of the electrochemical device. Figures 2 to 6 The electrode of the present invention that solves the problems of the conventional electrode 10 will be described in more detail.

[0059] Figure 2 1 is a perspective view showing a process of partially etching an electrode layer according to some embodiments of the present invention. Figure 3 This is a perspective view showing an example of an electrode layer on which a cut surface having a concavo-convex shape is drawn according to some embodiments of the present invention.

[0060] Reference Figure 2 , the sliding portion S can be removed from the electrode layer 22. When the sliding portion S is cut from the electrode layer 22, a Figure 3 Electrode 20.

[0061] According to some embodiments of the present invention, the sliding portion S may be removed by laser ablation. Laser ablation refers to the use of a laser to ablate a specific pattern shape on a negative electrode material such as graphite or silicon coated on a negative electrode for making a secondary battery or a positive electrode material such as lithium iron phosphate (LFP), nickel cobalt manganese (NCM), or nickel cobalt aluminum oxide (NCA) coated on a positive electrode. Specifically, a high-power pulsed laser is used to focus a laser beam L on a sample to remove the focused portion.

[0062] In the present invention, in order to prevent the quality and function of the electrode from being reduced, when laser ablation is performed, the output wavelength of the laser can be 355nm to 2000nm, and the pulse repetition rate can be 1 to 10,000kHz. In addition, the shape of the laser spot in the processing part can generally be circular. However, the present invention is not limited thereto.

[0063] In the present invention, the laser beam (L, Figure 2 ) removes the sliding portion S. The laser beam L may be irradiated to the electrode layer 12 in a direction toward one surface of the current collector 11 , that is, in a direction perpendicular to one surface of the current collector 11 or in a height direction of the electrode 20 .

[0064] The electrode 20 may include a current collector 21, an electrode layer 22, and a non-coating portion 23. However, the present invention is not limited thereto, and the electrode 20 may include fewer or more components than the above components.

[0065] The current collector 21 may be formed in a thin plate shape and may support one surface of the electrode layer 22 .

[0066] The electrode layer 22 may be located on at least one surface of the current collector 21 .

[0067] In the present invention, the electrode 20 may be a positive electrode or a negative electrode, and the electrode layer 22 may be a positive electrode active material layer or a negative electrode active material layer.

[0068] As an example, when the electrode layer 22 is a positive electrode active material layer, a lithium-containing transition metal oxide can be used as the electrode layer. For example, the lithium-containing transition metal oxide can be selected from Li x Ni a Co b Mn c O2(0.5 <x<1.3,0<a<1,0<b<1,0<c<1,a+b+c=1)、Li xFePO4(0.5 < x < 1.3), Li x CoO2(0.5 < x < 1.3), Li x NiO2(0.5 < x < 1.3), Li x MnO2(0.5 < x < 1.3), Li x Mn2O4(0.5 < x < 1.3), Li x Ni 1-y Co y O2(0.5 < x < 1.3, 0 < y < 1), Li x Co 1-y Mn y O2(0.5 < x < 1.3, 0 ≤ y < 1), Li x Ni 1-y Mn y O2(0.5 < x < 1.3, O ≤ y < 1), Li x Ni a Co b Mn c O4(0.5 < x < 1.3, 0 < a < 2, 0 < b < 2, 0 < c < 2, a + b + c = 2), Li x Mn 2-z Ni z O4(0.5 < x < 1.3, 0 < z < 2), Li x Mn 2-z Co z O4(0.5 < x < 1.3, 0 < z < 2) and Li x One or a mixture of two or more of the group consisting of CoPO4(0.5 < x < 1.3). The lithium-containing transition metal oxide may also be coated with a metal or metal oxide such as aluminum (Al). In addition, in addition to the lithium-containing transition metal oxide, sulfides, selenides, halides, etc. may also be used. However, the present invention is not limited to the above examples.

[0069] As another example, when the electrode layer 22 is a negative electrode active material layer, carbon such as non-graphitizable carbon and graphite-based carbon, Li x Fe2O3(0 ≤ x ≤ 1), Li x WO2(0 ≤ x ≤ 1), Sn x Me 1-x Me' y O zMetal composite oxides such as (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of Group 1, Group 2, Group 3 of the periodic table, halogen; 0≤x≤1; 1≤y≤3; 1≤z≤8), lithium metal, lithium alloy, silicon-based alloy, tin-based alloy, SiO, SiO / C, SiO2 and other silicon-based oxides, SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4 and Bi2O5 and other metal oxides, conductive polymers such as polyacetylene, Li-Co-Ni based materials, etc. can be used as the negative electrode active material layer. However, the present invention is not limited to the above examples.

[0070] When electrode layer 22 is disposed on one surface of current collector 21, non-coating portion 21 may be defined as a region without electrode layer 22 on one surface of current collector 21. That is, non-coating portion 23 may be defined as an exposed surface portion of current collector 11 without electrode layer 22.

[0071] Reference Figure 3 The electrode 20 may include a cut surface 24. The cut surface 24 may be formed by cutting or etching one end of the electrode layer 22. That is, the cut surface 24 may be formed at one end of the electrode layer 22.

[0072] For example, Figure 2 As shown, the cut surface 24 can be formed by etching a part of the electrode layer 22 using the laser beam L. However, this is only an example, and the method of forming the cut surface 24 is not limited thereto.

[0073] The cut surface 24 may be cut in a direction toward one surface of the current collector 21 , that is, in a height direction of the electrode 20 . The cut surface 24 may be formed in a width direction of the electrode 20 .

[0074] The cut surface 24 may be in a concave-convex shape. The concave-convex shape may refer to a shape formed by continuous intersection of concave and convex shapes. For example, when the electrode 20 is observed from above, the concave-convex shape may form a wave pattern based on the plane of the electrode 20.

[0075] Specifically, the cutting surface 24 may have a plurality of curved portions arranged side by side along the width direction of the electrode 20. The cross-cutting surface of the curved portion may be in a semicircular shape, and the outer peripheral surface of the curved portion may have an orthographic projection of an arc.

[0076] Figure 4 yes Figure 3 The AA' cross-sectional view shows an example of the end surface of the cutting surface portion of some embodiments of the present invention. Figure 5 yes Figure 3 The AA' cross-sectional view shows another example of the end surface of the cutting surface portion of some embodiments of the present invention.

[0077] Reference Figure 4 and Figure 5 , the cut surface 24 may include a concave portion 241 and a convex portion 242. The concave portion 241 and the convex portion 242 may be formed crosswise and repeatedly along the width direction of the electrode 20. Therefore, the cut surface 24 may include a plurality of concave portions and a plurality of convex portions.

[0078] In the present invention, the convex portion 242 may be located between two adjacent concave portions 241 . Also, the concave portion 241 may be located between two adjacent convex portions 242 .

[0079] The concave portion 241 and the convex portion 242 may be formed at one end of the electrode layer 22 .

[0080] The recess 241 may have a shape that is recessed toward the inside of the electrode layer 22 in the length direction of the electrode 20. The recess 241 may include a curved end surface. That is, the recess 241 may have a shape that is recessed toward the inside of the electrode layer 22 into a recessed curved shape. For example, when the electrode 20 is viewed from above, the end surface of the recess 241 may include a curved shape.

[0081] The projection 242 may have a shape that projects outward from the electrode layer 22 in the length direction of the electrode 20. When the electrode 20 is viewed from above, the end surface width of the projection 242 may become narrower toward the outer end of the projection 242. The projection 242 may have a pointed shape.

[0082] Both sides of the end surface of the convex portion 242 may be recessed inward. The end surface of the convex portion 242 may become narrower toward the end.

[0083] The end surface of the curved concave portion 241 may have a certain curvature. When a virtual line is extended according to the curvature formed by the end surface of the concave portion 241, a virtual circle may be formed. The end surface of the concave portion 241 may be included in a part of the virtual circle.

[0084] Reference Figure 4 , the cutting surface 24a may include a concave portion 241a and a convex portion 242a. Virtual circles C11, C12, ... extending according to the curvature formed by the end faces of the plurality of concave portions 241a may be defined. Two adjacent virtual circles C11, C12 in the virtual circles extending according to the curvature formed by the end faces of the plurality of concave portions 241a may be in line contact with each other or may not be in line contact with each other. The curvature and radius Ra formed by the virtual circles C11, C12, ... may be the same.

[0085] The curvature formed by the end faces of the plurality of recessed portions 241a may be the same. The curvature formed by the virtual circles C11 and C12 may be the same.

[0086] The convex portion 242 a may be formed between the virtual circles C11 , C12 , ... With reference to the width direction of the electrode 20 , the length of the convex portion 242 a may be shorter than the length of the concave portion 241 a .

[0087] Figure 4 In the embodiment, the plurality of convex portions 242a and the plurality of concave portions 241a forming the cut surface 24a can be laser ablated on the sliding portion S ( Figure 2 ) is formed by etching.

[0088] According to some embodiments of the present invention, when etching an electrode roll having a width of 600 mm, if the laser etching area is 400 mm, the scanning speed of the laser scanner is 1 m / sec, and the pulse repetition rate is 10 kHz, a concave-convex shape with a total of 4,000 virtual circles C11, C12, ... can be formed in a length of 400 mm. Furthermore, if the diameter of the virtual circles C11, C12, ... extending according to the curvature formed by the end faces of each of the plurality of concave portions 241a is 100 μm, there are 10 virtual circles in the 1 mm processing area. Among them, if the pulse repetition rate is increased to 20 kHz, then Figure 5 As shown, there are 20 virtual circles C11, C12, ... extending in accordance with the curvature formed by the end faces of the plurality of recesses 241b within 1 mm. However, even if the pulse repetition rate is changed, the diameters of the virtual circles C11, C12, ... do not change.

[0089] Specifically, refer to Figure 5 , the cutting surface 24b may include a concave portion 241b and a convex portion 242b. Virtual circles C11, C12, ... extending according to the curvature formed by the end faces of the plurality of concave portions 241b may be defined. Two adjacent virtual circles C21, C22 in the virtual circles extending according to the curvature formed by the end faces of the plurality of concave portions 242b may form a mutually overlapping surface. The curvature and radius Rb formed by the virtual circles C11, C12, ... may be the same.

[0090] The convex portion 242 b may be formed between the virtual circles C11 , C12 , ... In the width direction of the electrode 20 , the length of the convex portion 242 b may be shorter than the length of the concave portion 241 b .

[0091] Figure 5 In the embodiment, the plurality of convex portions 242b and the plurality of concave portions 241b forming the cut surface 24b can be formed by laser ablation on the sliding portion S ( Figure 2 ) is formed by etching.

[0092] exist Figure 4 and Figure 5 Based on the reference Figure 3, each of the plurality of recesses 241 and the plurality of protrusions 242 may extend in a direction perpendicular to one surface of the current collector 21, that is, in the height direction of the electrode 2. In this case, each of the plurality of recesses 241 may have a partial shape of a cylindrical outer surface.

[0093] Figure 6 This is a stereogram showing another example of the cut surface of some embodiments of the present invention.

[0094] For etching of secondary batteries, laser scanning is usually repeated 2 to 10 times. In this case, a predetermined amount of material can be left on the boundary side of the etching pattern, such as Figure 6 As shown, multiple sections of cutting surfaces can be processed.

[0095] Reference Figure 6 The cut surface 240 may include a first cut surface 245 and a second cut surface 246 . The second cut surface 246 may be located between the current collector 21 and the first cut surface 245 .

[0096] The first cut surface 245 and the second cut surface 246 may be formed at one end of the electrode layer 22. The first cut surface 245 may be located above the second cut surface 246. The second cut surface 246 may be located below the first cut surface 245. The second cut surface 246 may be disposed adjacent to the current collector 21.

[0097] The first cutting surface 245 and the second cutting surface 246 may include end surfaces of a concavo-convex shape. For example, when viewed from above, the first cutting surface 245 and the second cutting surface 246 may include a wave pattern.

[0098] The first cut surface 245 and the second cut surface 246 may include concave portions 245a and 246a and convex portions 245b and 246b. The concave portions 245a and the convex portions 245b may be repeatedly formed in the width direction of the electrode 20. Also, the concave portions 246a and the convex portions 246b may be repeatedly formed in the width direction of the electrode 20.

[0099] Specifically, the first cutting surface 245 may include a first concave portion 245a and a first convex portion 245b. The first concave portion 245a and the first convex portion 245b may be repeatedly formed in the width direction of the electrode 20. And, the second cutting surface 246 may include a second concave portion 246a and a second convex portion 246b. The second concave portion 246a and the second convex portion 246b may be repeatedly formed along the width direction of the electrode 20. The first concave portion 245a may be recessed into a concave curve shape toward the inner side of the electrode layer 22 in the length direction of the electrode 20. The second concave portion 246a may be recessed into a concave curve shape toward the inner side of the electrode layer 22 in the length direction of the electrode 20. The curvature of the first concave portion 245a and the curvature of the second concave portion 256a may be the same.

[0100] The shapes of the first cutting surface 245 and the second cutting surface 246 may have Figures 3 to 5 The shape of the cutting surface 24 mentioned above.

[0101] The first cutting surface 245 can be cut or etched Figure 3 The cutting surface 24 is formed.

[0102] Compared with the second cut surface 246, the first cut surface 245 may be more recessed toward the inner side of the electrode layer 22 in the length direction of the electrode 20. Compared with the first cut surface 245, the second cut surface 246 may be more protruding toward the outer side of the electrode layer 22. That is, compared with the second cut surface 246, the first cut surface 245 may be arranged closer to the inner side in the length direction of the electrode 20.

[0103] The upper side surface 247 of the second cutting surface 246 may be defined as a region where the first cutting surface 245 is recessed further toward the inside of the electrode layer 22 than the second cutting surface 246 and is exposed toward the upper side.

[0104] A vertical height h1 of the first cut surface 245 may be lower than a vertical height h2 of the second cut surface 246. The vertical direction may be defined as a height direction of an electrode or a direction toward one surface of the current collector 21.

[0105] The manufacturing method of the electrode 20 according to some embodiments of the present invention is as follows.

[0106] The electrode 20 of some embodiments of the present invention may include: a current collector 21; an active material layer electrode layer 22, which is located on one surface of the current collector 21 and is a region formed by stacking active material slurry including active material, conductive material and adhesive; and an uncoated portion 23, which is located on the one surface of the current collector 21 and is a region where the active material layer is not stacked.

[0107] When the electrode is a positive electrode and the active material is a positive electrode active material, the positive electrode current collector 21 can usually be made to have a thickness of about 3 to 50 μm. There is no particular limitation on the positive electrode current collector 21 as long as it does not cause chemical changes in the battery and has high conductivity. For example, stainless steel, aluminum, nickel, titanium, plastic carbon, or a material in which the surface of aluminum or stainless steel is surface-treated with carbon, nickel, titanium, silver, etc. can be used.

[0108] The positive electrode current collector 21 may also have fine concavoconvexities formed on its surface to increase the binding force of the positive electrode active material, and may be in various forms such as a film, sheet, foil, net, porous material, foam, non-woven fabric, etc.

[0109] In the present invention, the conductive material contained in the active material layer can be generally added in an amount of 0.2 to 5 wt % based on the total weight of the mixture including the positive electrode active material. Such conductive material is not particularly limited as long as it does not cause chemical changes in the battery and has conductivity.

[0110] For example, graphite such as natural graphite or artificial graphite, carbon black, acetylene black, Ketjen black, gas black, furnace black, lamp black, summer black and other carbon black, conductive fibers such as carbon fiber and metal fiber, metal powders such as carbon fluoride, aluminum, nickel powder and other metal powders, conductive metal oxides such as zinc oxide, potassium titanate, titanium oxide and other conductive materials such as polystyrene derivatives and the like can be used as conductive materials.

[0111] In the present invention, the binder contained in the active material layer 22 is a component that helps the active material to bind to the conductive material and the current collector, and can usually be added in an amount of 0.2 to 5% by weight based on the total weight of the slurry containing the positive electrode active material. Examples of such a binder include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene propylene diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber, fluororubber, various copolymers, and the like.

[0112] When the electrode is a negative electrode, the negative electrode current collector 21 is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity.

[0113] For example, copper, stainless steel, aluminum, nickel, titanium, plastic carbon, materials obtained by surface treating copper or stainless steel with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloys, etc. can be used as the negative electrode current collector.

[0114] In addition, the negative electrode current collector 21 may generally have a thickness of 3 μm to 50 μm, and like the positive electrode current collector, the binding force of the negative electrode active material may be enhanced by forming fine concave and convex on the surface of the current collector. Various forms such as thin film, sheet, foil, net, porous, foam, non-woven fabric, etc. may be used. In addition, the conductive material and binder contained in the active material layer may be the same as those described above for the positive electrode.

[0115] According to some embodiments of the present invention, the electrode layer 22 may be formed by coating and drying a slurry for the electrode layer on one surface of the current collector 21. In this case, the slurry for the electrode layer 22 may be coated and dried on one surface of the current collector 21 to generate an area where the slurry for the electrode layer is not provided, i.e., an uncoated portion 23. In this case, the electrode layer 22 may have a sliding portion S, wherein the height of the electrode layer in the area connected to the uncoated portion 23 is reduced to a height lower than the center of the electrode layer 22 and abuts against the uncoated portion 23.

[0116] When the slurry for the electrode layer 22 is applied to the current collector 21, the current collector 21 formed with the electrode layer 22 is rolled. In this case, the rolling process can be applied without limitation as long as it is a process implemented on a general electrode. Through the above-mentioned rolling process, the thickness of the electrode layer (22) can reach a desired level.

[0117] After the current collector 21 formed with the electrode layer 22 is rolled, the sliding portion S of the electrode layer 22 can be removed. The sliding portion S extends from both ends of the central portion of the electrode layer 22 and may include a portion whose thickness gradually becomes thinner in the direction of the uncoated portion 3 where the electrode layer 22 is not formed.

[0118] The sliding portion S may be removed by various commonly used etching methods as long as physical and chemical deformation of the current collector 21 and the residual electrode layer 22 is not caused.

[0119] According to some embodiments of the present invention, laser ablation may be used to remove the sliding portion S. The detailed description thereof is omitted as described above.

[0120] In the present invention, Figures 3 to 6 In the embodiment, the electrode shape can be generated by laser ablation. Laser scanning can be repeated 2 to 10 times for laser ablation. In this case, a predetermined amount of material can be retained on the boundary side of the etching pattern, such as Figure 6 As shown, multiple sections of cutting surfaces can be processed.

[0121] According to some embodiments of the present invention, the sliding portion of the electrode layer may be removed after rolling, or may be performed after rolling and sheeting.

[0122] According to some embodiments of the present invention, when a pulsed laser is used to perform laser filming on a negative electrode, a positive electrode, a positive electrode active material layer, a negative electrode active material layer, etc., the cut surface cut by laser filming can be Figures 3 to 6 The cut surface 24 of the electrode layer 22 described above corresponds to the shape. However, the present invention is not limited thereto.

[0123] In the present invention, laser filming may refer to the process of forming an electrode using a laser beam on an electrode roll. For the positive electrode, laser filming can generally be performed by coating an insulating material such as ceramic on an aluminum sheet, then coating NCM, NCA or LFP material, and using a laser filming machine to cut the electrode roll into an electrode shape. For the negative electrode, laser filming can be performed by coating graphite or SI-C on a copper sheet instead of aluminum, and then using a laser filming machine to form an electrode. Among them, the laser filming machine can use a pulsed laser like laser ablation. However, the present invention is not limited to this.

[0124] The secondary battery of the present invention comprises a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode. The positive electrode or the negative electrode may be the electrode of some embodiments of the present invention described above.

[0125] The separator used with the electrode of the present invention is not particularly limited. An insulating film that separates the positive electrode and the negative electrode and has high ion transmittance and mechanical strength can be used as a separator. As long as it is used as a separator in a conventional secondary battery, it can be used without particular limitation.

[0126] Specifically, porous polymer films, such as ethylene homopolymers, propylene homopolymers, ethylene / butene copolymers, ethylene / hexene copolymers, ethylene / hexene copolymers and ethylene / methacrylate copolymers, etc., which can be prepared from polyolefin polymers or their two or more layered structures can be used as separators. In addition, common porous nonwoven fabrics such as nonwoven fabrics made of high melting point glass fibers, polyethylene terephthalate fibers, etc. can also be used as separators.

[0127] In addition, in order to ensure heat resistance or mechanical strength, a separator coated with inorganic particles, a binder polymer, or a mixture of inorganic particles and a binder polymer can be used, and can be selectively used as a single layer or multilayer structure. At the same time, when a solid electrolyte such as a polymer is used as an electrolyte, the solid electrolyte can also serve as a separator.

[0128] According to some of the above-mentioned embodiments of the present invention, the reversal of the capacity balance (N / Pbalance) of the positive electrode and the negative electrode can be prevented, the Li precipitation phenomenon can be suppressed by calculating the electrolyte concentration generated in the sliding portion, the overvoltage and cycle characteristics of the secondary battery using such an electrode can be improved, and the adhesion between the end side electrode and the diaphragm can be improved.

[0129] On the one hand, according to at least one of the above-mentioned embodiments of the present invention, there is an advantage that the charging and discharging speed of the secondary battery can be accelerated and the life of the secondary battery can be prolonged.

[0130] In the present invention, the electrode can not only be limited to some of the embodiments described above, but also can selectively combine all or part of the embodiments so as to implement various modifications to the embodiments.

[0131] On the one hand, the present invention is described with reference to the accompanying drawings, but these are only embodiments and are not limited to specific embodiments. Various contents that can be implemented by those skilled in the art in a modified manner also fall within the scope of protection of the claims. In addition, the modified embodiments should not be understood additionally from the technical concept of the present invention.

Claims

1. An electrode, characterized in that: include: current collector; as well as The electrode layer is located on at least one surface of the current collector, and the electrode layer includes a concave-convex cutting surface.

2. The electrode according to claim 1, characterized in that The cut surface includes a plurality of concave portions and a plurality of convex portions repeatedly formed in a width direction of the electrode.

3. The electrode according to claim 2, characterized in that Each of the plurality of recesses includes a curved end surface recessed toward the inside of the electrode layer.

4. The electrode according to claim 3, characterized in that Two adjacent virtual circles among the virtual circles extending along the curvature formed by the end faces of the plurality of recessed portions form surfaces that overlap with each other.

5. The electrode according to claim 3, characterized in that The end surfaces of the plurality of recesses each have the same curvature.

6. The electrode according to claim 3, characterized in that Each of the plurality of concave portions and the plurality of convex portions extends in a direction perpendicular to the one surface of the current collector.

7. The electrode according to claim 2, characterized in that The cutting surface comprises: a first cutting surface; and The second cutting surface is located between the current collector and the first cutting surface.

8. The electrode according to claim 7, characterized in that The first cut surface includes a plurality of first recessed portions recessed into a concave curve shape toward the inside of the electrode layer, and the second cut surface includes a plurality of second recessed portions recessed into a concave curve shape toward the inside of the electrode layer.

9. The electrode according to claim 8, characterized in that The first cutting surface is recessed further into the electrode layer than the second cutting surface, and the upper side surface of the second cutting surface is defined as a region where the first cutting surface is recessed further into the electrode layer than the second cutting surface and is exposed to the upper side.

10. The electrode according to claim 8, characterized in that The curvature formed by each of the plurality of first recesses is the same as the curvature formed by each of the plurality of second recesses.

11. The electrode according to claim 7, characterized in that When heights of the first cut surface and the second cut surface are defined in a direction toward the one surface of the current collector, the height of the first cut surface is lower than the height of the second cut surface.

12. The electrode according to claim 2, characterized in that The cut surface is cut along a direction toward the one surface of the current collector.

13. The electrode according to claim 11, characterized in that The electrode further includes an uncoated portion defined as a region on the one surface of the current collector where the electrode layer is not disposed.

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