Electrode leads for electrochemical element and electrochemical element incorporating the same

Abstract

To provide an electrode lead for electrochemical elements with improved adhesion between the electrode lead and a lead film, and an electrochemical element having the lead.SOLUTION: The present invention relates to an electrode lead for electrochemical elements and an electrochemical element having the same, in which a nickel plating layer is located on the surface of a metal terminal, an uneven structure is located on the nickel plating layer, and a coating layer containing a polar group is included, and the contact area between the electrode lead and the lead film can be increased without damaging the surface of the electrode lead, thereby enhancing the bonding strength between the electrode lead and the lead film.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electrode lead for an electrochemical element and an electrochemical element including the same.

[0002] This application claims priority based on Korean Patent Application No. 10-2021-0146111, filed on October 28, 2021, and the entire contents disclosed in the specification and drawings of that application are incorporated herein by reference. [Background technology]

[0003] Mobile IT devices such as mobile phones, laptops, and tablet PCs are closely intertwined with modern life, and the demand for electrochemical devices, a core component of these devices, is rapidly increasing along with the growth of the IT industry market. Among these electrochemical devices, secondary batteries can be used repeatedly through charging and discharging. They are an environmentally friendly battery technology that does not use hazardous substances such as lead, nickel, or cadmium. They are lightweight yet have high energy density, allowing them to store large amounts of energy in a small volume. This makes them the core of a new, growing power industry of the future. In particular, lithium secondary batteries are not only the most widely used power source for mobile IT devices, which are closely related to human life, but are also increasingly being used as a power source for electric vehicles and as a power storage device for renewable energy.

[0004] Generally, an electrochemical device comprises a positive electrode, a negative electrode, a separator separating them, an electrolyte that transfers lithium ions through the separator, a battery case that accommodates these components, and electrode leads that serve as a path for current to the outside of the battery case. The device may further comprise a lead film that is attached to the electrode lead to prevent short circuits between the electrode lead and the battery case and to seal the electrode lead and the battery case.

[0005] However, the interface between the electrode lead and the battery case has a weak sealing strength, which frequently causes problems such as electrolyte leakage and gas ingress / egress at the interface between the electrode lead and the battery case, and therefore active research is being conducted to improve this.

[0006] The sealing strength between the electrode lead and the battery case is affected by the sealing strength between the electrode lead and the lead film and the sealing strength between the lead film and the battery case.

[0007] In order to improve the sealing strength between the lead film and the battery case, active development efforts have been made to increase the thickness of the lead film and to use a material for the lead film that has roughly the same physical properties as the fused portion of the battery case. However, the current situation is that improving the sealing strength between the electrode lead and the lead film has reached its technical limit.

[0008] Therefore, there is still a great need to develop a technique for improving the sealing strength between the electrode lead and the lead film. Summary of the Invention [Problem to be solved by the invention]

[0009] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrode lead for an electrochemical device, in which the adhesive strength between the electrode lead and the lead film is improved, and an electrochemical device including the electrode lead. [Means for solving the problem]

[0010] In order to solve the above problems, according to one aspect of the present invention, there is provided an electrode lead for an electrochemical element having the following configuration.

[0011] The first aspect is A metal terminal; a nickel plating layer located on the surface of the metal terminal; a coating layer located on the nickel plating layer and including a polar group; Including, The electrode lead for an electrochemical element is characterized in that the coating layer has an uneven structure.

[0012] A second aspect is the electrode lead for an electrochemical element according to the first aspect, The polar group may be an —OH group or an —O group.

[0013] A third aspect is the electrode lead for an electrochemical element according to the first or second aspect, The coating layer containing the polar group may contain an anhydrous oxide.

[0014] A fourth aspect is the electrode lead for an electrochemical element according to the third aspect, The anhydrous oxide may include an anhydrous chromium-based oxide, an anhydrous zirconium-based oxide, an anhydrous titanium-based oxide, an anhydrous manganese-based oxide, an anhydrous molybdenum-based oxide, an anhydrous cerium-based oxide, or two or more of these.

[0015] A fifth aspect is the electrode lead for an electrochemical element according to any one of the first to fourth aspects, The coating layer containing the polar group may further contain a binder polymer.

[0016] A sixth aspect is the electrode lead for an electrochemical element according to the fifth aspect, The binder polymer may include polyvinyl alcohol, an acrylic polymer, an epoxy polymer, an olefin polymer, a phenol resin, or two or more of these.

[0017] A seventh aspect is the electrode lead for an electrochemical element according to any one of the first to sixth aspects, The uneven structure may be formed by mechanical surface treatment such as rolling, sandblasting, polishing with SiC (silicon carbide) paper, laser irradiation or ultrasonic application, chemical surface treatment such as partial erosion with chemicals, or a combination of these.

[0018] In order to solve the above problems, according to another aspect of the present invention, there is provided an electrochemical device having the following configuration.

[0019] The eighth aspect is an electrode assembly having an electrode lead attached thereto; a battery case that houses the electrode assembly; a lead film that encloses a portion of the outer surface of the electrode lead and is interposed between the electrode lead and a battery case; Equipped with The electrode lead relates to an electrochemical element, characterized in that the electrode lead includes the electrode lead for an electrochemical element according to any one of claims 1 to 7.

[0020] A ninth aspect is the electrochemical device according to the eighth aspect, The lead film may include a non-polar polymer resin, a polar polymer resin, or a combination thereof.

[0021] A tenth aspect is the electrochemical device according to the ninth aspect, The non-polar polymer resin may include oriented polypropylene (OPP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), polyimide (PI), or two or more of these.

[0022] An eleventh aspect is the electrochemical device according to the ninth aspect, The polar polymer resin may include acid modified polypropylene (PPa).

[0023] A twelfth aspect is the electrochemical device according to the ninth or eleventh aspect, The polar polymer resin may be maleic acid, maleic anhydride, fumaric acid, maleimide, maleimide anhydride, itaconic acid, itaconic anhydride, a derivative thereof, or a resin having two or more polar groups introduced therein.

[0024] A thirteenth aspect is the electrochemical device according to any one of the eighth to twelfth aspects, The electrode lead may be a negative electrode lead, The negative electrode lead may include a metal terminal plated with nickel from the nickel plating layer. [Effects of the Invention]

[0025] The electrochemical device according to an embodiment of the present invention includes a coating layer having a concave-convex structure and polar groups on the surface of the metal terminal, thereby improving the adhesive strength between the electrode lead and the lead film.

[0026] In an electrochemical element according to one embodiment of the present invention, even though a textured structure is formed on the surface of the metal terminal, the surface of the electrode lead is not damaged, and therefore the adhesion strength between the electrode lead and the lead film is improved without impairing corrosion resistance. [Brief explanation of the drawings]

[0027] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical concept of the present invention, and therefore the present invention should not be interpreted as being limited to only the matters depicted in such drawings.

[0028] [Figure 1] 1 is a diagram showing an electrode lead for an electrochemical element according to one embodiment of the present invention. [Figure 2] 1 shows an electrochemical device according to one embodiment of the present invention. [Figure 3] 3 is an enlarged view showing an interface between an electrode lead and a lead film in an electrochemical element according to one embodiment of the present invention. FIG. [Figure 4] FIG. 2 is an enlarged view showing the interface between the electrode lead and the lead film in the electrochemical element according to one embodiment of the present invention. [Figure 5]1 is a scanning electron microscope (SEM) image of a surface portion of an electrode lead that is in contact with a lead film in an electrode lead manufactured in Example 1. [Figure 6] 1 is a diagram showing survey scan spectra of the cross section of a portion in contact with a lead film and a portion not in contact with the lead film in an electrode lead manufactured in Example 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in the specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as having meanings and concepts corresponding to the technical ideas of the present invention, in accordance with the principle that the inventor himself can appropriately define the concepts of terms in order to best describe the invention.

[0030] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be various equivalents and modifications that can be substituted therefor at the time of this application.

[0031] An electrode lead for an electrochemical device according to one embodiment of the present invention has a metal terminal having a textured surface, and a coating layer including a polar group on the surface of the metal terminal having the textured surface.

[0032] FIG. 1 is a diagram showing an electrode lead for an electrochemical element according to one embodiment of the present invention.

[0033] 1, an electrode lead 10 for an electrochemical element according to one embodiment of the present invention has a concave-convex structure on the surface of a metal terminal. More specifically, the concave-convex structure is formed on the surface of the electrode lead in a portion that comes into contact with a lead film.

[0034] The electrode lead 10 for an electrochemical element according to one embodiment of the present invention has a concave-convex structure on the surface of the metal terminal, thereby providing a large surface area for the electrode lead and improving the adhesive strength between the electrode lead and the lead film through an anchor effect. Furthermore, if moisture penetrates or electrolyte leaks into the bonded portion between the lead film and the electrode lead, the migration path of the moisture or electrolyte can be significantly extended, thereby minimizing the migration of the moisture or electrolyte.

[0035] The uneven structure may be formed over the entire contact surface between the electrode lead and the lead film, or may be formed only in part.

[0036] The uneven structure may be formed by various methods, such as mechanical surface treatments such as rolling, sandblasting, grinding with SiC paper, laser irradiation, and ultrasonic application, or chemical surface treatments such as partial erosion with chemicals. Alternatively, the uneven structure may be formed by a combination of mechanical and chemical surface treatments.

[0037] As the rolling method, a temper rolling process can be used. The temper rolling process refers to performing a light cold rolling of about 0.3 to 3.0% on the electrode lead after annealing in order to improve the mechanical properties of the electrode lead and adjust the surface condition.

[0038] Partial erosion by chemicals can be achieved by applying, for example, phosphoric acid, hydrochloric acid, or nitric acid to the electrode lead, allowing time for the desired fine irregularities to form, and then washing with distilled water or the like, thereby forming an irregular structure on the surface of the electrode lead.

[0039] The formation and orientation of the uneven structure are not particularly limited, but may be formed so that multiple grooves are formed at an angle of 0° (horizontal) to 49° with respect to the surface of the electrode lead that is not in contact with the lead film. Such grooves tend to further increase the contact area with the lead film and tend to further extend the migration length of water and electrolyte.

[0040] The size of the unevenness in the uneven structure (i.e., the depth of the valleys) may be 1% to 50% of the thickness of the electrode lead. When the size of the unevenness satisfies the above-mentioned range, the adhesive strength between the electrode lead and the lead film is further improved, which is more advantageous in preventing the extension of the migration path of moisture, etc. In addition, it is easy to prevent the mechanical properties of the electrode lead 10 from being damaged.

[0041] Referring to Figure 1, an electrode lead 10 for an electrochemical device according to one embodiment of the present invention includes a coating layer 11 containing polar groups on the surface of the metal terminal having the textured structure. The polar groups can improve the adhesive strength between the electrode lead and the lead film by forming van der Waals bonds, which are electrostatic attraction forces, between the lead film and the electrode lead. They can also increase the corrosion resistance of the surface of the electrode lead.

[0042] In one embodiment of the present invention, the polar group may be an —OH group or an —O group.

[0043] In one embodiment of the present invention, the polar group-containing coating layer 11 may contain an anhydrous oxide, which contains an -OH group or an -O group, allowing the lead film and the electrode lead 10 to form van der Waals bonds, thereby further improving the adhesive strength between the electrode lead 10 and the lead film.

[0044] In one embodiment of the present invention, the anhydrous oxide may be a chromium-based anhydrous oxide or a non-chromium-based anhydrous oxide.

[0045] The non-chromium-based anhydrous oxide may include, for example, a zirconium-based anhydrous oxide, a titanium-based anhydrous oxide, a manganese-based anhydrous oxide, a molybdenum-based anhydrous oxide, a cerium-based anhydrous oxide, or two or more of these.

[0046] When the anhydrous oxide is a chromium (Cr)-based anhydrous oxide, the coating layer 11 containing polar groups may be formed on the surface of the electrode lead 10 through a chromate treatment. The chromate treatment is performed by immersing the electrode lead in a treatment solution containing chromic acid (usually a mixture of chromic acid and sulfuric acid), thereby forming a chromate film on the surface of the electrode lead, improving corrosion resistance and providing a glossy surface.

[0047] The treatment solution for the chromate treatment may contain, based on the total weight of the treatment solution, 1 to 4 wt % of potassium ferricyanide, 3 to 8 wt % of trivalent chromium or hexavalent chromium, 8 to 15 wt % of hydrofluoric acid, 5 to 10 wt % of zirconium fluoride, and 63 to 83 wt % of an aqueous sulfuric acid solution.

[0048] The chromate treatment may be carried out with a deposition time of 30 to 50 seconds and at a process temperature of 15 to 50°C.

[0049] When the anhydrous oxide is a non-chromium (Cr) based anhydrous oxide, a metal salt or a metal precursor may be used to form the metal oxide film.

[0050] As an example, a zirconium oxide film may be formed from hexafluorozirconate (H2ZrF6), and when forming a titanium oxide film, hexafluorotitanate (H2TiF6) is often used.

[0051] In one embodiment of the present invention, the polar group-containing coating layer 11 may further include a binder polymer. When the polar group-containing coating layer 11 further includes a binder polymer, the adhesive strength between the electrode lead and the lead film can be further increased.

[0052] In one embodiment of the present invention, the binder polymer may include polyvinyl alcohol, an acrylic polymer, an epoxy polymer, an olefin polymer, a phenol resin, or two or more of these.

[0053] The electrode lead for an electrochemical element according to one embodiment of the present invention has a coating layer containing a concave-convex structure and polar groups on the surface of the electrode lead, thereby achieving both mechanical and chemical bonding effects between the electrode lead and the lead film.

[0054] An electrochemical device according to one embodiment of the present invention includes an electrode assembly having an electrode lead attached thereto, a battery case that houses the electrode assembly, and a lead film that encloses a portion of an outer surface of the electrode lead and is interposed between the electrode lead and the battery case, and is characterized by including the electrode lead described above.

[0055] FIG. 2 is an enlarged view of an electrochemical device according to one embodiment of the present invention.

[0056] Referring to FIG. 2, an electrochemical device 100 according to one embodiment of the present invention includes an electrode assembly 20 to which an electrode lead 10 is attached, and a battery case 30.

[0057] The electrode assembly 20 includes a positive electrode plate, a negative electrode plate, and a separator. The electrode assembly 20 may be formed by stacking the positive electrode plate and the negative electrode plate in this order with the separator sandwiched therebetween.

[0058] The positive electrode plate may be formed by including a positive electrode current collector made of a thin metal plate with excellent conductivity, for example, aluminum (Al) foil, and a positive electrode active material layer coated on at least one side of the current collector. The positive electrode plate may also include a positive electrode tab made of a metal material, for example, aluminum (Al), at one end. The positive electrode tab may extend and protrude from one end of the positive electrode plate, or may be welded to one end of the positive electrode plate, or may be attached using a conductive adhesive.

[0059] The negative electrode plate may be formed by including a negative electrode current collector made of a conductive metal thin plate, for example, copper (Cu) foil, and a negative electrode active material layer coated on at least one side of the negative electrode current collector. The negative electrode plate may also include a negative electrode tab at one end made of a metal material, for example, nickel (Ni). The negative electrode tab may extend and protrude from one end of the negative electrode plate, or may be welded to one end of the negative electrode plate, or may be attached using a conductive adhesive.

[0060] The separator may be sandwiched between the positive and negative electrode plates to electrically insulate the positive and negative electrode plates from each other and may be formed in the form of a porous membrane that allows lithium ions to pass between the positive and negative electrode plates. The separator may include, for example, a porous membrane made of polyethylene (PE), polypropylene (PP), or a composite film thereof.

[0061] The separator may have an inorganic coating layer on its surface, which may have a structure in which inorganic particles are bound and fixed together by a binder, forming a pore structure due to the interstitial volume between the particles.

[0062] Examples of the electrode assembly 20 include a jelly roll (winding) electrode assembly having a structure in which long sheet-like positive and negative electrode plates are wound up with a separator interposed therebetween, a stack (lamination) electrode assembly having a structure in which a plurality of positive and negative electrode plates cut into units of a predetermined size are stacked in this order with a separator interposed therebetween, and a stack / folding electrode assembly having a structure in which a bi-cell or full cell having a predetermined unit of positive and negative electrode plates stacked with a separator interposed therebetween is wound up.

[0063] The case 30 serves to house the electrode assembly 20 .

[0064] In one embodiment of the present invention, the battery case 30 may include a receiving portion 30 a for receiving the electrode assembly 20 and a sealing portion 30 b formed to seal the electrode assembly 20 .

[0065] The sealing portion 30b may include a sealant resin, and the sealant resin may be fused along the outer circumferential surface of the receiving portion 30a to seal the electrode assembly 20.

[0066] The fusion may be heat fusion, ultrasonic fusion, or the like, but is not particularly limited as long as it can fusion-bond the seal portion 30b.

[0067] In one embodiment of the present invention, the battery case 30 may be provided in the form of a multi-layered film including an outer layer for protection from external impact, a metal barrier layer for blocking moisture, and a sealant layer for sealing the case 30.

[0068] The outer layer may include a polyester-based film using poly(ethylene terephthalate) (PET), polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymer polyester, polycarbonate, nylon, or the like, and may be configured as a single layer or multiple layers.

[0069] The metal barrier layer may include aluminum, copper, or the like.

[0070] The sealant layer may contain a sealant resin and may be configured as a single layer or multiple layers.

[0071] In one embodiment of the present invention, the sealant resin may include polypropylene (PP), acid-modified polypropylene (PPa), random polypropylene, ethylene-propylene copolymer, or two or more of these. The ethylene-propylene copolymer may include, but is not limited to, ethylene-propylene rubber, ethylene-propylene block copolymer, etc.

[0072] In one embodiment of the present invention, the battery case 30 may be in the form of a pouch.

[0073] In one embodiment of the present invention, when the battery case 30 is pouch-shaped, it may include an upper pouch and a lower pouch. When the battery case 30 includes an upper pouch and a lower pouch, the outer peripheries of the upper pouch and the lower pouch can be fused together by heat and pressure to seal the battery.

[0074] When the battery case 30 is pouch-shaped, the sealing portion 30b may be four-sided sealed or three-sided sealed at the periphery of the battery case. The three-sided sealed structure refers to a structure in which an upper pouch and a lower pouch are formed from a single pouch sheet, and then the boundary between the upper pouch and the lower pouch is folded so that the electrode assembly receiving portions 30a formed in the upper pouch and the lower pouch overlap, and the remaining three peripheries excluding the folded portion are sealed.

[0075] Referring to FIG. 2, the electrode lead 10 may be housed in the battery case 30 such that a portion of the electrode lead 10 is exposed to the outside of the battery case 30 .

[0076] Referring to FIG. 2, an electrochemical device 100 according to one embodiment of the present invention includes a lead film 40 .

[0077] The lead film 40 wraps around a portion of the outer surface of the electrode lead 10 and is interposed between the electrode lead 10 and the battery case 30. The lead film 40 is interposed between the electrode lead 10 and the battery case 30 and assists in bonding the electrode lead 10 to the battery case 30. The battery is sealed at the surface where the lead film 40 abuts against the battery case 30.

[0078] The lead film 40 may be located on at least one surface of the electrode lead 10. Alternatively, the lead films 40 may be arranged on the upper and lower surfaces of the electrode lead 10 so as to face each other, and the electrode lead 10 and the lead film 40, or the lead film 40 and the battery case 30, may be bonded together by thermal fusion.

[0079] The lead film 40 may include a non-polar polymer resin, a polar polymer resin, or a combination thereof.

[0080] In one embodiment of the present invention, the non-polar polymer resin may include oriented polypropylene (OPP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), polyimide (PI), or two or more of these.

[0081] 3 and 4 are enlarged views showing the interface between the electrode lead and the lead film in an electrochemical element according to one embodiment of the present invention.

[0082] 3 and 4, when the lead film 40 contains a polar polymer resin, the van der Waals bonding force between the polar groups of the lead film 40 and the polar groups of the electrode lead 10 is increased, thereby further improving the adhesive strength between the electrode lead 10 and the lead film 40.

[0083] In one embodiment of the present invention, the polar polymer resin may include acid-modified polypropylene (PPa). When the polar polymer resin includes acid-modified polypropylene, the polar groups of the acid-modified polypropylene and the polar groups of the electrode lead 10 form van der Waals bonds, which can further increase the adhesive strength between the electrode lead 10 and the lead film 40.

[0084] The polypropylene resin may include a propylene polymer (homopolypropylene), a propylene copolymer (PP copolymer), a propylene terpolymer (PP terpolymer), etc. The propylene copolymer (PP copolymer) may include a propylene-ethylene block copolymer, etc., and the propylene terpolymer (PP terpolymer) may include a propylene-ethylene-butylene block copolymer, etc.

[0085] In one embodiment of the present invention, the polar polymer resin may be maleic acid, maleic anhydride, fumaric acid, maleimide, maleimide anhydride, itaconic acid, itaconic anhydride, a derivative thereof, or a resin having two or more polar groups introduced therein.

[0086] In one embodiment of the present invention, the electrode lead 10 may be a positive lead or a negative lead.

[0087] When the electrode lead 10 is a positive electrode lead, the metal terminal constituting the electrode lead 10 may contain aluminum metal, which has advantageous electrical conductivity.

[0088] When the electrode lead 10 is a negative electrode lead, the metal terminal constituting the electrode lead 10 may be a nickel-plated metal terminal. When the metal terminal constituting the electrode lead 10 is nickel-plated, it is advantageous in terms of conductivity and can prevent corrosion of the electrode lead 10 from a long-term perspective. That is, when the electrode lead 10 includes a nickel-plated metal terminal and the surface of the nickel-plated metal terminal includes a coating layer 11 having an uneven structure and polar groups, it is possible to improve the adhesive strength between the electrode lead 10 and the lead film 40 without impairing corrosion resistance.

[0089] As described above, the metal terminal constituting the electrode lead 10 may be a metal terminal plated with nickel. In other words, the electrode lead 10 may include the metal terminal, a nickel plating layer located on the surface of the metal terminal, and a coating layer 11 containing polar groups located on the nickel plating layer. Even if the metal terminal constituting the electrode lead 10 is plated with nickel, the electrode lead in an electrochemical element according to one embodiment of the present invention can prevent the nickel plating from being damaged by the uneven structure formed on the surface of the electrode lead. In other words, by setting the size of the uneven structure thin, limited to the thickness of the coating layer 11, the nickel plating on the surface of the metal terminal can remain undamaged. As a result, the surface of the nickel-plated metal terminal is not physically or chemically damaged, and the adhesion strength between the electrode lead 10 and the lead film 40 can be improved without impairing corrosion resistance.

[0090] As a method for plating the metal terminal with nickel, a nickel strike process for forming a weak nickel plating film to improve the adhesion of the nickel plating, or a nickel plating process for forming a nickel plating film to a desired thickness, etc. may be used.

[0091] The present invention will be described in more detail below with reference to examples to aid in understanding the present invention. However, the examples according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the following examples. The examples of the present invention are provided to more completely explain the present invention to those skilled in the art.

[0092] Example 1

[0093] A nickel plating film was formed on the surface of a copper foil having a thickness of 200 μm by an electrochemical method (electrolytic plating method) using a plating solution containing 600 ml / L of nickel sulfamate, 6 g / L of nickel chloride, and 30 g / L of boric acid.

[0094] The electrode lead was immersed in a treatment solution containing 800 ppm to 1000 ppm of chromium on the surface of the copper foil on which the nickel plating film was formed, to form a chromate film containing a polar group on the surface of the electrode lead.

[0095] The surface of the copper foil on which the polar group-containing coating layer was formed was laser patterned, and the surface-treated copper foil was attached to the electrode tab of the electrode assembly by welding. Polypropylene films having maleic acid polar groups were attached to the upper and lower surfaces of the electrode lead, respectively, to prepare an electrode lead.

[0096] Next, the electrode assembly was placed in a pouch-type case of an aluminum laminate sheet, and a carbonate-based lithium electrolyte solution containing 1 M lithium hexafluorophosphate (LiPF6) was injected into the case. The sheet was then heat-sealed to prepare an electrochemical device.

[0097] Evaluation example 1: Surface analysis of electrode leads

[0098] In the electrode lead manufactured in Example 1, cross sections of the portion in contact with the lead film and the portion not in contact with the lead film were observed with a scanning electron microscope (SEM) and are shown in FIG.

[0099] It was confirmed that the electrode lead manufactured in Example 1 had an uneven structure formed on its surface, but the nickel plating layer on the surface of the electrode lead that contacts the lead film was not damaged.

[0100] In addition, for the electrode lead manufactured in Example 1, the survey scan spectrum of the cross section of the part in contact with the lead film and the part not in contact with the lead film is shown in Figure 6, and the results of the quantitative analysis of the surface of the electrode lead are shown in Table 1.

[0101] The quantitative analysis of the electrode lead surface was performed by X-ray photoelectron spectroscopy (XPS) using a K-Alpha instrument manufactured by Thermo Fisher Scientific Co., Ltd., under the following specific conditions:

[0102] X-ray source: Monochromatic Al Kα (1486.6 eV) X-ray spot diameter: 400 μm Survey scan: pass energy 200 eV, energy step 1 eV, dwell time 10 ms

[0103] [Table 1]

[0104] 6 and Table 1, it was confirmed that the nickel plating layer on the surface of the electrode lead that contacts the lead film was not damaged, even though the electrode lead manufactured in Example 1 had a concave-convex structure formed on the surface. In other words, it was confirmed that the nickel was not removed but remained even in the area where laser patterning was applied to the electrode lead manufactured in Example 1. [Explanation of symbols]

[0105] 10: Electrode lead 11: Coating layer containing polar groups 20: Electrode assembly 30: Battery case 30a: storage section, 30b: Seal part 40: Lead film 100: Electrochemical element

Claims

1. an electrode assembly to which a negative electrode lead is attached; a battery case that houses the electrode assembly; a lead film that wraps a portion of the outer surface of the negative electrode lead and is interposed between the electrode lead and the battery case; Equipped with The negative electrode lead is A metal terminal; a nickel plating layer located on the surface of the metal terminal; a coating layer located on the nickel plating layer and including a polar group; Including, The coating layer has an uneven structure at least in part only in an area that comes into contact with the lead film.

2. 2. The electrochemical device according to claim 1, wherein the polar group is an —OH group or an —O group.

3. 2. The electrochemical device according to claim 1, wherein the coating layer containing polar groups comprises an anhydrous oxide.

4. 4. The electrochemical element according to claim 3, wherein the anhydrous oxide comprises an anhydrous chromium-based oxide, an anhydrous zirconium-based oxide, an anhydrous titanium-based oxide, an anhydrous manganese-based oxide, an anhydrous molybdenum-based oxide, an anhydrous cerium-based oxide, or two or more of these.

5. The electrochemical element according to claim 1 , wherein the coating layer containing the polar group further comprises a binder polymer.

6. 6. The electrochemical element according to claim 5, wherein the binder polymer comprises polyvinyl alcohol, an acrylic polymer, an epoxy polymer, an olefin polymer, a phenolic resin, or two or more of these.

7. 10. The electrochemical device of claim 1, wherein the lead film comprises a non-polar polymer resin, a polar polymer resin, or a combination thereof.

8. 8. The electrochemical element according to claim 7, wherein the non-polar polymer resin comprises oriented polypropylene (OPP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), polyimide (PI), or two or more of these.

9. 8. The electrochemical device according to claim 7, wherein the polar polymer resin comprises acid-modified polypropylene (PPa).

10. 8. The electrochemical element according to claim 7, wherein the polar polymer resin has introduced therein a polar group selected from maleic acid, maleic anhydride, fumaric acid, maleimide, maleimide anhydride, itaconic acid, itaconic anhydride, derivatives thereof, or two or more of these.

11. 2. The electrochemical element according to claim 1, wherein the uneven structure includes a plurality of grooves inclined at an angle of 0° to 49° with respect to the surface of the electrode lead that is not in contact with the lead film.

12. forming a nickel plating layer on at least one surface of the metal terminal; forming a coating layer containing a polar group on the nickel plating layer; forming a relief structure on the coating layer; A method for producing an electrode lead for an electrochemical element, comprising:

13. The method for producing an electrode lead for an electrochemical element according to claim 12 , wherein the uneven structure is formed in an area where the metal terminal and the lead film are in contact with each other.

14. The method for producing an electrode lead for an electrochemical element according to claim 12 , wherein the nickel plating layer is not damaged by the step of forming the uneven structure.

15. The method for producing an electrode lead for an electrochemical element according to claim 12 , wherein the step of forming the nickel plating layer includes a Ni striking step, a Ni plating step, or a combination thereof.

16. The method for producing an electrode lead for an electrochemical element according to claim 12 , wherein the coating layer containing a polar group contains an anhydrous oxide.

17. 17. The method for producing an electrode lead for an electrochemical element according to claim 16, wherein the anhydrous oxide comprises a chromium-based anhydrous oxide, a zirconium-based anhydrous oxide, a titanium-based anhydrous oxide, a manganese-based anhydrous oxide, a molybdenum-based anhydrous oxide, a cerium-based anhydrous oxide, or two or more of these.

18. The method for producing an electrode lead for an electrochemical element according to claim 12 , wherein the coating layer containing a polar group further contains a binder polymer.

19. 19. The method for producing an electrode lead for an electrochemical element according to claim 18, wherein the binder polymer comprises polyvinyl alcohol, an acrylic polymer, an epoxy polymer, an olefin polymer, a phenolic resin, or two or more of these.

20. 13. The method for manufacturing an electrode lead for an electrochemical element according to claim 12, wherein the step of forming the uneven structure is performed by rolling, sandblasting, polishing with SiC paper, mechanical surface treatment using laser irradiation or ultrasonic application, chemical surface treatment using partial erosion with a chemical substance, or a combination of these.

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