Electrode lead, method for manufacturing electrode lead, and lithium secondary battery including electrode lead

Abstract

The invention relates to an electrode lead. And an electrode lead electrically connected to the electrode assembly, the electrode lead including: a metal terminal; and a film layer disposed on the metal terminal and having two or more patterns engraved on a surface of the film layer, in which the two or more patterns are spaced apart from each other at equal intervals and arranged in a horizontal direction of the film layer, and each of the two or more patterns includes a side surface and a bottom surface.

Description

Technical Field

[0002] Cross-reference to related applications

[0003] This application claims priority to Korean Patent Application No. 10-2023-0114977, filed on August 30, 2023, the disclosure of which is incorporated herein by reference. Technical Field

[0004] The present invention relates to an electrode lead, a method for preparing the electrode lead, and a lithium secondary battery including the electrode lead, and more specifically, to an electrode lead wherein heat generation and resistance between the electrode lead and the fixture are reduced, a method for preparing the electrode lead, and a lithium secondary battery including the electrode lead. Background Technology

[0005] With technological advancements and increasing demand for mobile devices, the demand for rechargeable batteries has also grown rapidly. Among these rechargeable batteries, lithium-ion batteries are widely used as energy sources for various electronic products and mobile devices due to their high energy density, high operating voltage, and excellent storage and lifespan characteristics.

[0006] A lithium secondary battery typically consists of an electrode assembly including a positive electrode, a negative electrode, and spacers; a battery case housing the electrode assembly; an electrolyte injected into the battery case; and electrode leads that electrically connect the lithium secondary battery to an external device or to each other.

[0007] In this configuration, a lead film is attached to the interface between the electrode leads and the battery case to prevent short circuits and to seal both. The lead film is typically made of polymer for insulation and fusion with the battery case, and therefore presents a problem of reduced seal strength at the interface with the metal electrode leads. Consequently, as the lead film peels off from the electrode lead surface, electrolyte solution leaks at the interface between the lead film and the electrode leads, or moisture permeates from the outside, leading to stability issues.

[0008] To address these issues, attempts have been made to improve the electrolyte solution resistance and sealing strength between the electrode leads and the lead film by surface treatment, such as forming an oxide film. However, when a film layer is formed on the surface of the electrode leads through surface treatment, the surface resistance of the electrode leads increases due to the thickness of the film layer. This increases the amount of heat generated from the electrode leads during charging and discharging, leading to a decrease in the lifespan and stability of the lithium-ion battery. Summary of the Invention

[0009] Technical issues

[0010] To address the problems described above, one aspect of the present invention provides an electrode lead, a method for preparing the electrode lead, and a lithium secondary battery including the electrode lead, wherein the electrode lead can improve the sealing strength between the lead film and the electrode lead, while reducing the amount of heat and resistance generated in the electrode lead during charging and discharging.

[0011] Technical solution

[0012] [1] The present invention provides an electrode lead electrically connected to an electrode assembly, the electrode lead including a metal terminal; and a film layer disposed on the metal terminal and having two or more patterns etched on the surface of the film layer, wherein the two or more patterns are arranged to be spaced apart from each other at equal intervals in a direction parallel to the film layer, and each pattern includes a side surface and a bottom surface.

[0013] [2] The present invention provides the electrode leads of [1] above, wherein the shape of the bottom surface of the pattern is polygonal, circular or elliptical.

[0014] [3] The present invention provides the electrode leads of [1] or [2] above, wherein each pattern in the pattern has the same depth.

[0015] [4] The present invention provides electrode leads of at least one of [1] to [3] above, wherein each pattern in the pattern has the same bottom surface area.

[0016] [5] The present invention provides an electrode lead of at least one of [1] to [4] above, wherein the bottom surface and side surface of the pattern are perpendicular to each other.

[0017] [6] The present invention provides an electrode lead of at least one of [1] to [5] above, wherein the ratio of the bottom surface area of ​​the entire pattern to the cross-sectional area of ​​the film is in the range of 0.05 to 0.7, preferably 0.06 to 0.6, and more preferably 0.07 to 0.5.

[0018] [7] The present invention provides an electrode lead of at least one of [1] to [6] above, wherein the ratio of the bottom surface area of ​​a single pattern to the cross-sectional area of ​​the film layer is in the range of 0.005 to 0.010, preferably 0.0058 to 0.009, and more preferably 0.006 to 0.008.

[0019] [8] The present invention provides an electrode lead of at least one of [1] to [7] above, wherein the ratio of the depth of the pattern to the thickness of the film is in the range of 0.3 to 0.7, preferably 0.4 to 0.65, more preferably 0.45 to 0.6, and even more preferably 0.45 to 0.55.

[0020] [9] The present invention provides electrode leads of at least one of [1] to [8] above, wherein the film layer may include at least one selected from the group consisting of chromates, zirconium salts, titanium salts and phosphates, and may preferably include chromates.

[0021]

[10] The present invention provides an electrode lead of at least one of [1] to [9] above, wherein the metal terminal comprises at least one selected from the group consisting of aluminum, copper, nickel and nickel-plated copper, specifically aluminum, nickel or combinations thereof, and more specifically aluminum.

[0022]

[11] The present invention provides an electrode lead of at least one of [1] to

[10] above, wherein the ratio of the thickness of the metal terminal to the thickness of the film layer is in the range of 10000:1 to 500:1, preferably 6000:1 to 500:1, and more preferably 5000:1 to 500:1.

[0023]

[12] The present invention provides a lithium secondary battery comprising: an electrode assembly including a positive electrode, a negative electrode and a spacer; a battery case housing the electrode assembly; an electrolyte; an electrode tab, each of the positive and negative electrodes being connected to the electrode tab and the electrode tab protruding from one side of the assembly; an electrode lead as described above, one end of which is connected to the electrode tab; and a lead film disposed at the interface between the electrode lead and the battery case.

[0024]

[13] The present invention provides a method for preparing electrode leads, the method comprising the step of forming a film layer on a metal terminal by means of a gravure coating apparatus, wherein the gravure coating apparatus includes a rolling roller and a gravure roller, wherein the gravure roller has a surface rough portion and two or more patterns are engraved on the surface of the film layer, wherein the two or more patterns are arranged to be spaced apart from each other at equal intervals in a direction parallel to the film layer, and each pattern includes a side surface and a bottom surface.

[0025]

[14] The present invention provides a method for preparing electrode leads as described in

[13] above, wherein the film layer may include at least one selected from the group consisting of chromates, zirconium salts, titanium salts and phosphates, and may preferably include chromates.

[0026]

[15] The present invention provides the method of preparing electrode leads as described in

[13] or

[14] above, wherein each pattern in the pattern has the same depth and each pattern in the pattern has the same bottom surface area.

[0027] Beneficial effects

[0028] According to the present invention, since an engraved pattern is uniformly formed on the film layer disposed on the metal terminal surface of the electrode lead, the amount of heat generated from the electrode lead and the contact resistance during charging and discharging while pressing the electrode lead with a clamp can be reduced, while the electrolyte solution resistance and sealing strength between the electrode lead and the lead film can be improved. Therefore, the output characteristics, life characteristics, and stability of the lithium secondary battery can be improved. Attached Figure Description

[0029] Figure 1 This is a cross-sectional view illustrating a schematic structure of an electrode lead according to an embodiment of the present invention.

[0030] Figure 2 This is a perspective view illustrating a schematic structure of an electrode lead according to an embodiment of the present invention.

[0031] Figure 3 It is a schematic cross-sectional view of the electrode leads including the film layer, in which two or more patterns are arranged at unequal intervals in a direction parallel to the film layer.

[0032] Figure 4 This is a schematic process diagram of a gravure coating apparatus for preparing electrode leads according to an embodiment of the present invention.

[0033] Figure 5 An exploded assembly diagram of a lithium secondary battery according to the present invention is shown. Detailed Implementation

[0034] The invention will be described in more detail below.

[0035] It will be understood that the words or terms used in the specification and claims should not be interpreted as having the meaning defined in a commonly used dictionary, and it will also be understood that, based on the principle that the inventors may appropriately define the meaning of words or terms to best interpret the invention, the words or terms should be interpreted as having a meaning consistent with their meaning in the relevant field and in the context of the inventive concept.

[0036] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to limit the invention. In the specification, unless otherwise stated, singular terms may include plural forms.

[0037] It will also be understood that the terms “comprising,” “including,” or “having” as used in this specification indicate the presence of the stated features, number, steps, elements, or combinations thereof, but do not exclude the presence or addition of one or more other features, number, steps, elements, or combinations thereof.

[0038] The present invention will be described in detail below.

[0039] The precursor for a positive electrode active material, the method for preparing the precursor, the positive electrode active material, the positive electrode and / or the lithium secondary battery according to the present invention include at least one of the configurations disclosed below, and may include any combination of technically possible configurations among the following configurations.

[0040] Electrode leads

[0041] The electrode lead according to the invention is an electrode lead electrically connected to an electrode assembly, wherein the electrode lead includes: a metal terminal; and a film layer disposed on the metal terminal and having two or more patterns etched on the surface of the film layer, wherein the two or more patterns are arranged to be spaced apart from each other at equal intervals in a direction parallel to the film layer, and each pattern includes a side surface and a bottom surface.

[0042] Electrode leads are connected to electrode contacts that extend and protrude from the positive and negative plates included in the electrode assembly and can be used as electrode terminals for electrically connecting the secondary battery to an external device of the secondary battery or for electrically connecting the secondary batteries to each other.

[0043] Figure 1 This is a cross-sectional view illustrating a schematic structure of an electrode lead according to an embodiment of the present invention, and Figure 2 This is a perspective view illustrating a schematic structure of an electrode lead according to an embodiment of the present invention.

[0044] Reference Figure 1 and Figure 2 The electrode lead 10 includes a metal terminal 1 and a film layer 2 disposed on the metal terminal 1.

[0045] In the following text, reference will be made to Figure 1 and Figure 2 Each configuration of electrode lead 10 is described in detail.

[0046] When the lithium secondary battery and its external device are electrically connected via electrode leads, or when the secondary batteries are electrically connected to each other, the metal terminal 1 serves as a pathway for current to flow through.

[0047] Specifically, the metal terminal 1 may include at least one selected from the group consisting of aluminum (Al), nickel (Ni), copper (Cu), nickel-plated copper, gold (Au), silver (Ag), platinum (Pt), iron (Fe), chromium (Cr), and manganese (Mn). Specifically, the metal terminal 1 may include at least one selected from the group consisting of aluminum, copper, nickel, and nickel-plated copper because it promotes electron movement, does not react with organic solvents, and has excellent chemical stability, preventing oxidation or reduction even under prolonged battery operating conditions. Furthermore, the metal terminal 1 may more specifically include aluminum, nickel, or combinations thereof, or even more specifically, aluminum.

[0048] The metal terminal 1 may be in the form of a rectangular plate, but is not limited thereto, and may be any form that can function in the electrical connection of the secondary battery without limitation.

[0049] The thickness of the metal terminal 1 can be from 0.05 mm to 0.8 mm, preferably from 0.1 mm to 0.7 mm, and more preferably from 0.15 mm to 0.65 mm.

[0050] Specifically, when the electrode lead 10 is connected to the positive electrode contact 282, the thickness of the metal terminal 1 can be in the range of 0.2 mm to 0.6 mm, preferably 0.3 mm to 0.5 mm, and more preferably 0.35 mm to 0.45 mm, or in the range of 0.4 mm to 0.8 mm, preferably 0.5 mm to 0.7 mm, and more preferably 0.55 mm to 0.65 mm. Furthermore, when the electrode lead 10 is connected to the negative electrode contact 284, the thickness of the metal terminal 1 can be in the range of 0.05 mm to 0.35 mm, preferably 0.1 mm to 0.3 mm, and more preferably 0.15 mm to 0.25 mm, or in the range of 0.1 mm to 0.5 mm, preferably 0.2 mm to 0.4 mm, and more preferably 0.25 mm to 0.35 mm. By satisfying these ranges, the sealing strength of the battery case can be ensured, thus reducing concerns about electrolyte solution leakage and moisture penetration.

[0051] The film layer 2 is disposed on the metal terminal 1 to improve the sealing strength between the lead film and the electrode lead 10.

[0052] Furthermore, the film layer 2 can be conductive. Since the film layer is disposed on the metal terminal and pressed together when the electrode leads are pressed by the clamp, the electrode leads can remain conductive when the film layer is conductive, and therefore, current can flow smoothly through the electrode leads.

[0053] Specifically, the film layer 2 can be disposed on one or both surfaces of the metal terminal 1.

[0054] The film layer 2 may include at least one selected from the group consisting of chromates, zirconium salts, titanium salts, and phosphates, and may preferably include chromates. Chromates may be represented, for example, by Cr2O3H2O. When the film layer includes chromates, a stable film layer can be formed on the surface of the metal terminal, and the adhesion performance of the lead film relative to different materials can be improved due to the increased wettability of the electrode lead surface. Furthermore, when the film layer includes chromates, the conductivity of the electrode leads can be maintained.

[0055] When the metal terminal 1 is in direct contact with the lead film without the film layer 2, there is a problem of reduced sealing performance due to the weak thermal adhesion between the metal terminal and the lead film made of different materials. Therefore, delamination may occur between the lead film and the metal terminal, leading to leakage of the electrolyte solution between them, moisture penetration from the outside, or corrosion of the metal terminal. Consequently, the battery's lifespan, output characteristics, and stability are reduced. Therefore, this invention solves this problem by forming a film layer on the surface of the metal terminal.

[0056] However, when charging is performed while the electrode leads are pressed against the clamp, the film layer can act as a resistor compared to the metal terminals, and therefore, the battery's output characteristics may be degraded. Furthermore, when reducing the film layer thickness to improve resistance, the increased amount of heat generated at the contact surface between the electrode leads and the clamp when high current flows through the battery leads to reduced battery stability and lifespan.

[0057] Therefore, since the film layer 2 according to the invention comprises two or more regularly engraved patterns 3, the film layer can ensure adhesion to the lead film, while reducing the resistance and heat generated at the contact surface between the electrode lead and the clamp when the electrode lead is pressed with a clamp for charging and discharging.

[0058] Specifically, two or more patterns 3 are etched on the surface of the film layer 2.

[0059] Because the film layer 2 reduces the contact area with the clamp and relatively reduces the current density due to its wider surface area, the resistance generated by the film layer can be reduced when the electrode leads are pressed with the clamp, thanks to the multiple engraved patterns 3. Furthermore, since this method forms the engraved patterns as thin sections while maintaining the maximum thickness of the film layer, the heat generated when high current flows through the electrode leads can be reduced. Therefore, the lifespan characteristics, output characteristics, and stability of the lithium secondary battery can be improved.

[0060] Figure 3It is a cross-sectional view of the electrode leads including the film layer, in which two or more patterns are arranged at unequal intervals in a direction parallel to the film layer.

[0061] Will Figure 1 and Figure 2 and Figure 3 In comparison, the electrode lead 10 according to the present invention has a pattern 3 etched on the surface of the film layer 2, and the pattern 3 can be formed uniformly and regularly.

[0062] Specifically, in the electrode leads according to the invention, two or more patterns 3 are arranged to be spaced apart from each other at equal intervals in a direction parallel to the film layer 2. In this case, the interval refers to the shortest length between the respective edges of one pattern and another adjacent pattern on the uppermost surface of the film layer. Furthermore, equal intervals mean that the intervals are equal within an error range of ±10%. Parallel direction means a direction parallel to the surface of the film layer, and can specifically mean a direction parallel to the interface between the metal terminal and the film layer.

[0063] Therefore, two or more patterns can be regularly arranged on the surface of the film. In this case, when the electrode leads are fastened to the clamp and current is applied, the contact resistance and heat generation of the entire electrode leads can be reduced because the current can be prevented from flowing densely in specific areas of the electrode leads.

[0064] Each pattern in Pattern 3 includes a side surface and a bottom surface. The bottom surface is the lower surface of the pattern that is recessed from the uppermost surface of the film layer, where the bottom surface means the surface parallel to the interface between the metal terminal and the film layer, and the side surface means the surface that extends from the bottom surface to the uppermost surface of the film layer.

[0065] Each pattern in the pattern can have the same depth. In this case, the depth of the pattern refers to the vertical length from the uppermost surface of the film layer to the bottom surface of the pattern.

[0066] Having the same depth for each pattern within the pattern means that the depth is identical within a ±5% error range. As the standard deviation of the height distribution of the engraved pattern decreases, the pattern size decreases, and the pattern density increases, the contact resistance between the electrode lead and the electrode clamp decreases. In this case, since the contact resistance varies linearly with respect to pattern density and pattern size, but exponentially with respect to the standard deviation of the height distribution of the engraved pattern, the standard deviation of the height distribution of the engraved pattern may have the greatest impact on the contact resistance. That is, with each pattern having the same depth, a decrease in the standard deviation of the height distribution of the engraved pattern leads to a decrease in contact resistance and a reduction in the amount of heat generated from the electrode lead.

[0067] Each pattern in Pattern 3 can have the same bottom surface area. In this case, each pattern having the same bottom surface area means that the bottom surface area is the same within a ±5% error range. Since the patterns etched on the surface of the film can have the same surface area, each pattern can exhibit the same current density when charging and discharging while the electrode leads are fastened to the clamp. Therefore, there will be no problem of particularly increased or decreased resistance in specific areas of the electrode leads, and the contact resistance and heat generation of the entire electrode leads can be reduced.

[0068] The shape of the bottom surface of pattern 3 is not limited, and can be, for example, a polygon, a circle or an ellipse.

[0069] The bottom and side surfaces of pattern 3 can be perpendicular to each other. That is, the cross-sectional area of ​​the pattern can remain constant without decreasing or increasing along the depth direction of the electrode leads. In this case, the depth direction refers to the direction perpendicular to the interface between the film and the metal terminal. In this case, since the standard deviation of the height distribution of the engraved pattern can be reduced even in a single pattern, the contact resistance can be reduced as described above, and the contact resistance and heat generation of the electrode leads when they are fastened to the fixture can be further reduced.

[0070] The ratio of the bottom surface area of ​​all the patterns 3 to the cross-sectional area of ​​the film layer 2 can be in the range of 0.05 to 0.7, preferably 0.06 to 0.6, and more preferably 0.07 to 0.5. In this specification, the cross-sectional area of ​​the film layer refers to the surface area when no patterns are formed on the film layer. When this ratio is less than 0.05, the contact resistance between the electrode leads and the clamp may increase because the ratio of the bottom surface area of ​​all the patterns to the cross-sectional area of ​​the film layer may be small. Furthermore, when this ratio is greater than 0.7, the sealing strength between the electrode leads and the lead film may not be improved. Therefore, when the ratio meets the above-mentioned range, the sealing strength between the electrode leads and the lead film can be ensured by the film layer, while the amount of heat generated from the electrode leads during charging and discharging can be sufficiently reduced, and the contact resistance between the electrode leads and the clamp can also be reduced.

[0071] The ratio of the bottom surface area of ​​a single pattern 3 to the cross-sectional area of ​​the film layer 2 can be in the range of 0.005 to 0.010, preferably 0.0058 to 0.009, and more preferably 0.006 to 0.008. When the above range is met, since each pattern can be formed in a small size, even if all the patterns have the same bottom surface area, the surface area of ​​the entire film layer is relatively large, and therefore the contact resistance between the electrode leads and the clamp can be reduced. Furthermore, since the formation of large-sized individual patterns can be prevented, the current can flow uniformly through the entire electrode lead during charging and discharging, and therefore, the amount of contact resistance and heat generated between the electrode leads and the clamp can be uniformly reduced.

[0072] The ratio of the depth of pattern 3 to the thickness of film 2 can be in the range of 0.3 to 0.7, preferably 0.4 to 0.65, and more preferably 0.45 to 0.6, or even more preferably 0.45 to 0.55. In this case, the thickness of the film refers to the vertical length from the uppermost surface of the film to the interface between the metal terminal and the film, and the depth of the pattern refers to the vertical length from the uppermost surface of the film to the bottom surface of the pattern. By satisfying the above ranges, the adhesion between the entire film and the lead film can be sufficiently ensured, while the contact resistance of the film during charging and discharging can be sufficiently reduced, and the amount of heat generated from the electrode leads can also be reduced.

[0073] The thickness of film 2 can be in the range of 10 nm to 60 nm, preferably 15 nm to 40 nm, and more preferably 18 nm to 30 nm. When the above range is met, the sealing strength of the interface between the electrode lead and the lead film can be sufficiently ensured by increasing the adhesion between the electrode lead and the lead film, thus preventing delamination problems at the interface.

[0074] Furthermore, the ratio of the thickness of the metal terminal 1 to the thickness of the film layer 2 can be in the range of 10000:1 to 500:1, preferably 6000:1 to 500:1, and more preferably 5000:1 to 500:1. When the above range is met, since the electrode leads can electrically connect the secondary batteries to each other or smoothly connect the secondary batteries to external devices, output characteristics can be ensured. At the same time, the adhesion strength relative to the lead film can be improved through the film layer, and the increase in resistance and the resulting heat generated in the electrode leads can be reduced.

[0075] Methods for preparing electrode leads

[0076] Next, the method for preparing the electrode leads according to the invention includes the step of forming a film layer on a metal terminal by a gravure coating apparatus, wherein the gravure coating apparatus includes a rolling roller and a gravure roller, wherein the gravure roller has a surface rough portion and two or more patterns are engraved on the surface of the film layer, wherein the two or more patterns are arranged to be spaced apart from each other at equal intervals in a direction parallel to the film layer, and each pattern includes a side surface and a bottom surface.

[0077] Figure 4 This is a schematic process diagram of a gravure coating apparatus 300 for preparing electrode leads 10 according to an embodiment of the present invention.

[0078] Reference Figure 4 In the process of forming a film layer 2 on a metal terminal 1 by the gravure coating apparatus 300, the film layer 2 can be formed on the metal terminal 1 by supplying coating liquid to the gravure roller 310 and rotating the gravure roller 310 while in contact with the metal terminal 1. In this case, since the rolling roller 320 is in contact with a surface other than the surface on which the film layer 2 is formed and rotates in the opposite direction to the gravure roller 310, the metal terminal 1 can be moved, so that the film layer 2 is formed on the metal terminal 1 by the gravure roller 310.

[0079] The gravure coating apparatus 300 includes a rolling roller 320 and a gravure roller 310. Furthermore, the gravure coating apparatus 300 may also include a coating liquid supply tray 330 capable of supplying coating liquid.

[0080] The gravure roller 310 has a rough surface portion. Two or more patterns 3 can be engraved on the film layer 2 through the rough portion formed on the surface of the gravure roller 310. That is, the gravure roller 310 has the same shape and arrangement as the pattern 3, but may include an embossed pattern as a rough portion that is opposite to the pattern 3 described above.

[0081] The coating solution may include at least one selected from the group consisting of chromic acid, zirconium, titanium and phosphoric acid, and may preferably include chromic acid.

[0082] The metal terminal 1 may include at least one selected from the group consisting of aluminum, nickel, copper, gold, silver, platinum, iron, chromium and manganese, and more specifically, the metal terminal may include at least one selected from the group consisting of aluminum and nickel, because it promotes electron movement, does not react with organic solvents, and has excellent chemical stability so that it does not oxidize or reduce even under long-term battery operating conditions.

[0083] The metal terminal 1 may be in the form of a rectangular plate, but is not limited thereto, and may be any form that can function in the electrical connection of the secondary battery without limitation.

[0084] The thickness of the metal terminal 1 can be from 0.05 mm to 0.8 mm, preferably from 0.1 mm to 0.7 mm, and more preferably from 0.15 mm to 0.65 mm.

[0085] Specifically, when the electrode lead 10 is connected to the positive electrode contact 282, the thickness of the metal terminal 1 can be in the range of 0.2 mm to 0.6 mm, preferably 0.3 mm to 0.5 mm, and more preferably 0.35 mm to 0.45 mm, or in the range of 0.4 mm to 0.8 mm, preferably 0.5 mm to 0.7 mm, and more preferably 0.55 mm to 0.65 mm. Furthermore, when the electrode lead 10 is connected to the negative electrode contact 284, the thickness of the metal terminal 1 can be in the range of 0.05 mm to 0.35 mm, preferably 0.1 mm to 0.3 mm, and more preferably 0.15 mm to 0.25 mm, or in the range of 0.1 mm to 0.5 mm, preferably 0.2 mm to 0.4 mm, and more preferably 0.25 mm to 0.35 mm. By satisfying these ranges, the sealing strength of the battery case can be ensured, thus reducing concerns about electrolyte solution leakage and moisture penetration.

[0086] A film layer 2 is formed on the metal terminal 1 according to the method for preparing the electrode lead 10 according to the present invention. Specifically, the film layer 2 may be formed on one or both surfaces of the metal terminal 1, and may serve to improve the sealing strength between the lead film and the electrode lead.

[0087] The film layer 2 thus formed may include at least one selected from the group consisting of chromates, zirconium salts, titanium salts, and phosphates, and may preferably include chromates. Chromates may be represented, for example, by Cr2O3H2O. When the film layer includes chromates, a stable film layer can be formed on the surface of the metal terminal, and the adhesion performance of the lead film relative to different materials can be improved due to the increased wettability of the electrode lead surface.

[0088] Two or more patterns 3 are engraved on the surface of the film layer 2, and the patterns 3 can be formed in an engraving manner according to the shape of the roughness formed on the surface of the gravure roller 310. Therefore, patterns 2 having the same number and shape as the roughness formed in relief on the surface of the gravure roller 310 can be engraved on the film layer 2.

[0089] Since the film layer 2 and pattern formed according to the method for preparing electrode leads 10 according to the present invention are the same as those described above, their detailed description is omitted.

[0090] Lithium secondary batteries

[0091] According to another embodiment, the lithium secondary battery of the present invention includes: an electrode assembly including a positive electrode, a negative electrode, and a separator; a battery case housing the electrode assembly; an electrolyte; an electrode tab connected to the positive and negative electrodes and protruding from one side of the assembly; an electrode lead according to any one of claims 1 to 9, one end of the electrode lead being connected to the electrode tab; and a lead film disposed at the interface between the electrode lead and the battery case.

[0092] Figure 5 This is an exploded assembly diagram of a lithium secondary battery according to the present invention.

[0093] In the following text, reference will be made to Figure 5 Each configuration of the lithium secondary battery of the present invention is described in detail.

[0094] (1) Electrode assembly

[0095] The electrode assembly includes a positive electrode, a negative electrode, and a spacer.

[0096] Reference Figure 5 In the case of a pouch-type secondary lithium battery, the electrode assembly 270 can be inserted into the pouch-type battery case 210 and can be sealed through the pouch-type battery case 210 after electrolyte (not shown) is injected.

[0097] Electrode assembly 270 can be formed by sequentially stacking a positive electrode, a spacer and a negative electrode, and specifically, electrode assembly 270 can include two types of electrodes, such as a positive electrode and a negative electrode, and spacers disposed between the electrodes to insulate the electrodes from each other.

[0098] The positive and negative electrodes can be structures in which an active material slurry is applied, respectively, to an electrode current collector in the form of a metal foil or mesh, including aluminum and copper. The slurry is typically formed by stirring granular active material, auxiliary conductors, binders, and conductive agents in the presence of a solvent. This solvent can be removed in a subsequent process.

[0099] Positive and negative electrodes are prepared by applying a slurry containing electrode active materials, binders, and / or conductive agents to positive and negative current collectors, and electrode assembly 270 can be prepared in a predetermined shape by stacking the positive and negative electrodes on both sides of a spacer. The type of electrode assembly 270 may include, but is not limited to, stacked, wound, and stacked and folded types.

[0100] (2) Battery box

[0101] The battery case serves to house the electrode assembly. Specifically, after housing the electrode assembly and injecting electrolyte, the battery case is sealed. The battery case, in which the housing portion can be formed, is made of a material with predetermined flexibility. While the shape of the battery case is not limited, it is preferably cylindrical, coin-shaped, prismatic, or pouch-shaped. The upper and lower shells constituting the battery case can be separate components or essentially a single component connected at one side. The external shape of the battery case can be manufactured in various ways, and the invention is not limited thereto.

[0102] For example, the battery compartment can be a pouch-type battery compartment. (See reference...) Figure 5 The pouch-shaped battery case 210 can be fabricated by forming a pouch-shaped film laminate 220. The pouch-shaped battery case 210 can internally house the electrode assembly 270.

[0103] The base material layer 221, the gas barrier layer 222, and the sealant layer 223 can be sequentially laminated in the bag-shaped film laminate 220, but the present invention is not limited thereto.

[0104] The base material layer 221 is formed as the outermost layer of the pouch-shaped film laminate 220 to protect the secondary battery from friction and impact with the outside. The base material layer is formed of a polymer, which allows it to electrically insulate the electrode assembly 270 from the outside.

[0105] The base material layer 221 may be formed of at least one material selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, nylon, polyester, poly(p-phenylenebenzobisoxazole), polyaryl compounds, and Teflon. Among these materials, it is desirable that the base material layer 221 be formed of polyethylene terephthalate (PET), nylon, or a combination thereof, which have abrasion resistance and heat resistance.

[0106] A gas barrier layer 222 is laminated between the base material layer 221 and the sealant layer 223 to ensure the mechanical strength of the bag, prevent gas or moisture from entering and escaping from the outside of the secondary battery, and prevent electrolyte leakage from the inside of the pouch-type battery case. The gas barrier layer 222 can be formed of metal. For example, the gas barrier layer 222 can be a thin film of at least one metal selected from the group consisting of aluminum (Al), copper (Cu), stainless steel (SUS), nickel (Ni), titanium (Ti), and Invar alloys, but is not limited thereto.

[0107] When the pouch-type battery case containing the electrode assembly 270 is sealed, the sealant layer 223 is used to completely seal the interior of the pouch-type battery case by thermal bonding with each other at the sealing portions. For this purpose, the sealant layer 223 can be formed of a material with excellent thermal adhesion strength.

[0108] The sealant layer 223 can be formed of a material with insulating, corrosion-resistant, and sealing properties. Specifically, since the sealant layer 223 is in direct contact with the electrode assembly 270 and / or electrolyte (not shown) inside the pouch cell 210, it can be formed of a material with insulating and corrosion-resistant properties. Furthermore, since the sealant layer 223 completely seals the interior of the pouch cell to prevent material movement between the interior and exterior, it can be formed of a material with high sealing properties (e.g., excellent thermal adhesion strength). To ensure these insulating, corrosion-resistant, and sealing properties, the sealant layer 223 can be formed of a polymer material.

[0109] Specifically, the sealant layer 223 may be formed of at least one material selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, nylon, polyester, poly(p-phenylenebenzobisoxazole), polyaryl compounds, and Teflon, and may preferably be formed of a polyolefin-based resin, such as polypropylene (PP) and / or polyethylene (PE). In this case, polypropylene (PP) may include cast polypropylene (CPP), acid-modified polypropylene (PPa), polypropylene-ethylene copolymer, and / or polypropylene-butene-ethylene terpolymer.

[0110] The pouch-shaped battery case 210 can be prepared by stretching the pouch-shaped film laminate 220 using a stamping machine or similar means. Therefore, the pouch-shaped battery case 210 may include a cup-shaped portion 232 and a receiving portion 234. The receiving portion 234 is where the electrode assembly 270 is received; it can refer to the receiving space formed in a pouch shape inside the cup-shaped portion 232 when the cup-shaped portion 232 is formed.

[0111] The pouch-type battery case 210 may include a first shell 230 and a second shell 240. The first shell 230 includes a receiving portion 234 capable of accommodating an electrode assembly 270, and the second shell 240 can cover the receiving portion 234 from the top, such that the electrode assembly 270 does not detach from the outside of the battery case. The first shell 230 and the second shell 240 can be fabricated by connecting one side of the first shell 230 and the second shell 240 to each other, but the invention is not limited thereto, and the first shell 230 and the second shell 240 can be fabricated in various ways, for example, the first shell 230 and the second shell 240 can be fabricated separately from each other.

[0112] According to another embodiment of the invention, when the cup-shaped portion 242 is formed on the pouch-shaped film laminate 220, two symmetrical cup-shaped portions 242 can be pulled out adjacent to each other on a pouch-shaped film laminate 220. In this case, the cup-shaped portions 242 can be formed in the first shell 230 and the second shell 240, respectively. After the electrode assembly 270 is accommodated in the receiving portion 234 provided in the cup-shaped portion 232 of the first shell 230, the bridge-shaped portion 250 formed between the two cup-shaped portions 232 and 242 can be folded so that the two cup-shaped portions 242 face each other. In this case, the cup-shaped portion 242 of the second shell 240 can accommodate the electrode assembly 270 from above. Therefore, since the two cup-shaped portions 232 and 242 accommodate one electrode assembly 270, an electrode assembly 270 with a thickness greater than that when there is only one cup-shaped portion can be accommodated. Furthermore, since one edge of the secondary battery is formed by folding the pouch-shaped battery case 210, the number of edges to be sealed can be reduced when the sealing process is performed later. Therefore, the processing speed of the pouch-type secondary battery 200 can be increased, and the number of sealing processes can be reduced.

[0113] The pouch-type battery case 210 can be sealed while housing the electrode assembly 270, exposing a portion of the electrode leads 10, i.e., the terminal portion, which will be described later. Specifically, when the electrode leads 10 are connected to the electrode tabs 280 of the electrode assembly 270 and the lead film 290 is attached to this portion of the electrode leads 10, the electrode assembly 270 is housed in a receiving portion 234 disposed in a cup-shaped portion 232 of the first housing 230, and the second housing 240 can cover the receiving portion 234 from the top. Subsequently, electrolyte (not shown) is injected into the receiving portion 234, and the sealing portions 260 formed on the edges of the first housing 230 and the second housing 240 can be sealed.

[0114] The sealing portion 260 can be used to seal the receiving portion 234. Specifically, the sealing portion 260 can seal the receiving portion 234 while being formed along its edge. The sealing temperature of the sealing portion 260 can be in the range of 180°C to 250°C, particularly 200°C to 250°C, and more particularly 210°C to 240°C. When the sealing temperature meets the above-mentioned numerical range, the pouch-type battery box 210 can ensure sufficient sealing strength through thermal bonding.

[0115] In this case, the sealed portion 260 can be formed by folding towards the housing portion 234 to ensure the energy density of the lithium secondary battery.

[0116] (3) Electrolytes

[0117] The electrolyte used in this invention may include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, etc., which can be used in the preparation of secondary batteries, but this invention is not limited thereto.

[0118] Specifically, electrolytes may include organic solvents and lithium salts.

[0119] Any organic solvent can be used without limitation, as long as it serves as a medium through which ions participating in the electrochemical reactions of the battery can move. Specifically, the following can be used as organic solvents: ester solvents, such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents, such as dibutyl ether or tetrahydrofuran; ketone solvents, such as cyclohexanone; aromatic hydrocarbon solvents, such as benzene and fluorobenzene; or carbonate solvents, such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents, such as ethanol and isopropanol; nitriles, such as R-CN (where R is a straight-chain, branched, or cyclic C2 to C20 hydrocarbon group, and may include double-bonded aromatic rings or ether bonds); amides, such as dimethylformamide; dioxolane, such as 1,3-dioxolane; or sulfolane. Among these solvents, carbonate-based solvents are preferred, and mixtures of cyclic carbonates (e.g., ethylene carbonate or propylene carbonate) with high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery and low-viscosity linear carbonate-based compounds (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate, etc.) are more preferred. In this case, the performance of the electrolyte solution can be excellent when the cyclic carbonate and the linear carbonate are mixed in a volume ratio of about 1:1 to about 1:9.

[0120] Lithium salts can be used without particular restrictions, as long as they are compounds that can provide lithium ions used in lithium secondary batteries. Specifically, the anion of the lithium salt can be selected from F... - Cl - ,Br - I - NO3 - N(CN)2 - BF4 - CF3CF2SO3 - (CF3SO2)2N - (FSO2)2N - CF3CF2(CF3)2CO - (CF3SO2)2CH - (SF5)3C - (CF3SO2)3C -CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - and (CF3CF2SO2)2N - At least one of the following groups can be used as a lithium salt: LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2. The lithium salt can be used in a concentration range from 0.1 M to 2.0 M. If the concentration of the lithium salt is within the above range, excellent electrolyte performance can be obtained because the electrolyte can have suitable conductivity and viscosity, and lithium ions can move efficiently.

[0121] To improve battery life characteristics, suppress battery capacity reduction, and improve battery discharge capacity, in addition to the electrolyte components mentioned above, the electrolyte may also include at least one additive, such as a haloalkyl carbonate ester compound, like ethylene difluorocarbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, N-glycol dimethyl ether, triammonium hexaphosphate, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolides, ethylene glycol dialkyl ethers, ammonium salts, pyrroles, 2-methoxyethanol, or aluminum trichloride, etc. In this case, the additive may be included in an amount from 0.1 wt% to 5 wt% based on the total weight of the electrolyte.

[0122] (4) Electrode contacts

[0123] The electrode tabs are connected to each of the positive and negative electrodes and protrude from one side of the assembly.

[0124] Reference Figure 5 The electrode tab 280 is connected to each of the positive and negative electrodes of the electrode assembly 270 and protrudes from the electrode assembly to the outside, so that it can serve as a path for electrons to move between the inside and outside of the electrode assembly 270. The electrode current collector included in the electrode assembly 270 can consist of a portion to which an electrode active material is applied and an end portion to which no electrode active material is applied, i.e., an uncoated portion. The electrode tab 280 can be formed by cutting the uncoated portion, or by connecting individual conductive components to the uncoated portion via ultrasonic welding or the like. Figure 5As shown, the electrode tabs 280 may protrude in different directions of the electrode assembly 270, but are not limited thereto, and may be formed to protrude in various directions, for example, the electrode tabs 280 may protrude side by side from one side of the electrode assembly 270 in the same direction.

[0125] (5) Electrode leads

[0126] Electrode lead 10 serves to connect the secondary battery to an external power source. (Refer to...) Figure 5 The electrode leads 10 can be soldered to a plurality of electrode tabs 280 extending from the current collector of each electrode of the electrode assembly 270, for example, by spot welding.

[0127] Electrode leads 10 are connected to electrode assembly 270 and can protrude to the outside of the battery compartment. Specifically, one end of electrode lead 10 is connected to electrode assembly 270, particularly electrode tab 280, and the other end of electrode lead 10 can protrude to the outside of the battery compartment.

[0128] The electrode leads 10 may include a positive lead 20 and a negative lead 30. One end of the positive lead 20 is connected to the positive electrode contact 282 and extends in the protruding direction of the positive electrode contact 282. One end of the negative lead 30 is connected to the negative electrode contact 282 and extends in the protruding direction of the negative electrode. The other ends of both the positive lead 20 and the negative lead 30 may protrude to the outside of the battery compartment. Therefore, the electricity generated inside the electrode assembly 270 can be supplied to the outside. Furthermore, since the positive electrode contact 282 and the negative electrode contact 284 are formed to protrude in each direction, the positive lead 20 and the negative lead 30 may also extend in each direction. The materials of the positive lead 20 and the negative lead 30 may be different from each other. For example, the positive lead 20 may be formed of the same aluminum (Al) material as the positive current collector, and the negative lead 30 may be formed of the same copper (Cu) material as the negative current collector or nickel (Ni) coated copper material. Since the portion of the electrode lead 10 that protrudes to the outside of the battery box becomes a terminal portion, it can be electrically connected to an external terminal.

[0129] Since the other configurations of electrode lead 10 are the same as those described above, their detailed description is omitted.

[0130] (6) Lead film

[0131] The lead film prevents current generated from the electrode assembly from flowing through the electrode leads to the battery compartment and maintains the battery compartment's seal. For this purpose, the lead film can be formed of a non-conductive insulator that does not conduct electricity well. Generally, relatively thin insulating tapes or films that are easy to attach to the innermost layer of the electrode leads and / or battery compartment are widely used as lead films; however, the invention is not limited to this, and any component capable of insulating the electrode leads can be used.

[0132] Reference Figure 5 In the case of a pouch-type lithium secondary battery, the lead film 290 can be configured to surround the interface between the electrode lead 10 and the pouch-type battery case 210. For example, the first shell 230, the lead film 290, the electrode lead 10, the lead film 290, and the second shell 240 can be arranged in a sequentially stacked manner in the area of ​​the sealing portion 260 of the battery case. Specifically, the electrode lead 10 and the battery case are in contact with each other on one side, wherein, in this case, at least a portion of the electrode lead 10 and the pouch-type battery case 210 can be surrounded by the lead film 290, and the electrode lead and the battery case can be adhered to each other.

[0133] The lithium secondary battery according to the present invention is suitable for: portable devices, such as mobile phones, laptops and digital cameras; and electric vehicles, such as hybrid electric vehicles (HEVs).

[0134] In addition, battery packs or battery modules, including lithium secondary batteries as unit batteries, can be used as power sources for at least one medium and large device of power tools, electric vehicles including electric vehicles (EVs), hybrid electric vehicles and plug-in hybrid electric vehicles (PHEVs), or power storage systems.

[0135] The lithium secondary battery according to the present invention can be used not only in battery cells used as power sources for small devices, but also as a unit battery in medium and large battery modules comprising multiple battery cells.

[0136] Examples of medium and large-sized devices can be electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and energy storage systems, but medium and large-sized devices are not limited to these.

[0137] The invention will be described in more detail below with reference to specific examples.

[0138] Example 1

[0139] After preparing an aluminum (Al) metal terminal with a thickness of 0.4 mm, a width of 45 mm, and a length of 41 mm, a 20 nm thick film containing chromate (Cr2O3H2O) is formed on the surface of the metal terminal.

[0140] Subsequently, a striped engraving pattern was formed by applying a constant force to the surface of the film layer through a physical etching process, with equal intervals. The striped engraving pattern was formed such that the interval between the engraving patterns was 4 mm, the horizontal width of the engraving pattern was 0.35 mm, and the depth was 10 nm, thus preparing an electrode lead that simulates the pattern formed using a gravure coating device.

[0141] Comparison Example 1

[0142] After preparing an aluminum (Al) metal terminal with a thickness of 0.4 mm, a width of 45 mm, and a length of 41 mm, a 20 nm thick film containing chromate (Cr2O3H2O) is formed on the surface of the metal terminal to prepare the electrode lead. No special treatment is performed on the surface of the oxide film.

[0143] Comparison Example 2

[0144] After preparing an aluminum (Al) metal terminal with a thickness of 0.4 mm, a width of 45 mm, and a length of 41 mm, a 20 nm thick film containing chromate (Cr2O3H2O) is formed on the surface of the metal terminal.

[0145] Subsequently, an engraved pattern is formed on the surface of the film layer by physical etching. However, unlike Example 1, since the force applied when forming a pattern is not constant, the engraved pattern is formed such that the depth is not constant and the spacing is irregular. Therefore, electrode leads simulating the case without using a gravure coating device are prepared.

[0146] Experimental Example 1: Evaluation of Resistance Measurement During Fixture Tightening

[0147] After securing the electrode leads prepared in Example 1, Comparative Example 1, and Comparative Example 2 to the fixture, a direct current of 400 A was applied for 10 minutes, and the resistance of each electrode lead was measured by measuring the pressure difference before and after the current was applied. The measurement results are shown in Table 1 below.

[0148] [Table 1]

[0149] Referring to Table 1, it can be confirmed that, compared with the surface resistance of Comparative Example 1 in which no pattern is formed on the surface of the film layer and Comparative Example 2 in which an uneven engraved pattern is formed, the surface resistance of Example 1 in which a uniform engraved pattern is formed on the surface of the film layer of the electrode leads is reduced.

[0150] Experimental Example 2: Evaluation of Temperature Measurement of Electrode Leads During Fixture Tightening

[0151] After the electrode leads prepared in Example 1, Comparative Example 1, and Comparative Example 2 were secured to the fixture at room temperature, a direct current of 400 A was applied for 10 minutes, and then the temperature of each electrode lead was measured. The measurement results are shown in Table 2 below.

[0152] [Table 2]

[0153] Referring to Table 2, when the same amount of direct current is applied, it is understood that the electrode lead prepared in Example 1 has a lower temperature rise compared to the electrode leads prepared in Comparative Example 1 and Comparative Example 2. Therefore, it is understood that for the electrode lead prepared in Example 1, the amount of heat generated between the electrode lead and the fixture during charging and discharging is reduced compared to the amount of heat generated by the electrode leads prepared in Comparative Example 1 and Comparative Example 2.

[0154] (See attached image labels)

[0155] 1: Metal terminals

[0156] 2: Membrane layer

[0157] 3: Pattern

[0158] 10: Electrode leads

[0159] 20: Positive lead

[0160] 30: Negative lead

[0161] 200: Secondary battery

[0162] 210: Battery Box

[0163] 220: Bag-shaped film laminate

[0164] 221: Basic Material Layer

[0165] 222: Gas Barrier Layer

[0166] 223: Sealant layer

[0167] 230: The First Shell

[0168] 232: Cup-shaped part

[0169] 234: Accommodation section

[0170] 240: Second Shell

[0171] 242: Cup-shaped portion

[0172] 250: Bridge-shaped section

[0173] 260: Sealing part

[0174] 270: Electrode assembly

[0175] 280: Electrode contacts

[0176] 282: Positive electrode connector

[0177] 284: Negative electrode connector

[0178] 290: Lead film

[0179] 300: Gravure Coating Device

[0180] 310: Gravure Roll

[0181] 320: Rolling roller

[0182] 330: Coating liquid supply tray

Claims

1. An electrode lead electrically connected to an electrode assembly, the electrode lead comprising: Metal terminals; as well as A film layer disposed on the metal terminal and having two or more patterns etched on its surface. Wherein, the two or more patterns are arranged to be spaced apart from each other at equal intervals in a direction parallel to the film layer, and Each pattern in the pattern includes a side surface and a bottom surface.

2. The electrode lead according to claim 1, wherein, The bottom surface of the pattern is polygonal, circular, or elliptical in shape.

3. The electrode lead according to claim 1, wherein, Each pattern in the pattern has the same depth.

4. The electrode lead according to claim 1, wherein, Each pattern in the design has the same bottom surface area.

5. The electrode lead according to claim 1, wherein, The bottom surface and the side surface of the pattern are perpendicular to each other.

6. The electrode lead according to claim 1, wherein, The ratio of the bottom surface area of ​​all the patterns to the cross-sectional area of ​​the film layer is in the range of 0.05 to 0.

7.

7. The electrode lead according to claim 1, wherein, The ratio of the bottom surface area of ​​a single pattern to the cross-sectional area of ​​the film layer is in the range of 0.005 to 0.

010.

8. The electrode lead according to claim 1, wherein, The ratio of the depth of the pattern to the thickness of the film is in the range of 0.3 to 0.

7.

9. The electrode lead according to claim 1, wherein, The membrane layer comprises at least one selected from the group consisting of chromates, zirconium salts, titanium salts, and phosphates.

10. The electrode lead according to claim 1, wherein, The metal terminals include at least one selected from the group consisting of aluminum, copper, nickel, and nickel-plated copper.

11. The electrode lead according to claim 1, wherein, The ratio of the thickness of the metal terminal to the thickness of the film layer is in the range of 10000:1 to 500:

1.

12. A lithium secondary battery, comprising: An electrode assembly, comprising a positive electrode, a negative electrode, and a spacer; A battery case that houses the electrode assembly; Electrolytes; An electrode tab, which is connected to each of the positive and negative electrodes and protrudes from one side of the assembly; The electrode lead according to any one of claims 1 to 11, wherein one end of the electrode lead is connected to the electrode tab; and A lead film is disposed at the interface between the electrode lead and the battery box.

13. A method for preparing an electrode lead, the method comprising: The step of forming a film layer on metal terminals using a gravure coating apparatus. The gravure coating apparatus includes a rolling roller and a gravure roller. The gravure roller has a rough surface portion, and Two or more patterns are etched on the surface of the film layer. Wherein, the two or more patterns are arranged to be spaced apart from each other at equal intervals in a direction parallel to the film layer, and Each pattern in the pattern includes a side surface and a bottom surface.

14. The method for preparing electrode leads according to claim 13, wherein, The membrane layer comprises at least one selected from the group consisting of chromates, zirconium salts, titanium salts, and phosphates.

15. The method for preparing electrode leads according to claim 13, wherein, Each pattern in the pattern has the same depth, and Each pattern in the design has the same bottom surface area.

Images