Electrode lead of secondary battery and secondary battery including the electrode lead

Abstract

According to this embodiment, there are provided an electrode lead of a secondary battery and a secondary battery including the electrode lead, wherein the lead includes a metal substrate and a coating formed on the surface of the metal substrate, at least one of the top surface and the bottom surface of the lead is surface-treated with a non-adhesive material or has a gas release portion, and the gas release portion has a structure formed by removing the coating.

Description

Technical Field

[0001] This application claims priority to Korean Patent Application No. 10-2020-0184482 filed on December 28, 2020, and Korean Patent Application No. 10-2021-0148398 filed on November 2, 2021, in Korea.

[0002] The present disclosure relates to an electrode lead of a secondary battery having a gas release portion and a secondary battery including the electrode lead. Background Art

[0003] Due to the rapid increase in the use of fossil fuels, the demand for the use of alternative or clean energy is increasing, and the most actively researched field as a part of it is the field of power generation and power storage using electrochemistry.

[0004] Currently, typical examples of electrochemical devices using electrochemical energy include secondary batteries, and the range of use of secondary batteries is gradually expanding.

[0005] Recently, with the increase in technology development and demand for mobile instruments such as portable computers, cellular phones and cameras, the demand for secondary batteries as energy sources has increased. In particular, lithium secondary batteries that exhibit high charge / discharge characteristics and life characteristics and are eco-friendly have been intensively studied, commercialized and widely used.

[0006] However, as the application range of lithium secondary batteries as mentioned above expands, it is required to increase energy density. Therefore, such lithium secondary batteries cause an increase in gas generated inside the secondary batteries due to such an increase in energy density.

[0007] Furthermore, when water infiltrates into the secondary battery, a side reaction occurs, thereby undesirably accelerating the performance degradation of the secondary battery and the problem of gas generation.

[0008] In these cases, the above-mentioned safety issues have been solved by forming a gas release portion in the secondary battery so that the gas generated inside the secondary battery can be released to the outside. However, when the secondary battery is vented, the life of the secondary battery is significantly shortened. Therefore, it is urgent to solve the above-mentioned problems. Summary of the invention

[0009] Technical issues

[0010] The present disclosure is designed to solve the problems of the related art as well as technical problems that have needed to be solved in the past.

[0011] In particular, the present disclosure relates to providing an electrode lead of a secondary battery and a secondary battery including the electrode lead, the electrode lead having an efficiently constructed gas release path to improve the safety of the secondary battery.

[0012] Technical Solution

[0013] In one aspect of the present disclosure, an electrode lead according to any one of the following embodiments is provided.

[0014] According to the first embodiment,

[0015] Provided is an electrode lead for a secondary battery,

[0016] The electrode lead includes a metal substrate and a coating formed on a surface of the metal substrate, wherein at least one of a top surface and a bottom surface of the electrode lead has a gas release portion having a structure formed by surface treatment with a non-adhesive material or by removing the coating.

[0017] According to a second embodiment, there is provided an electrode lead of a secondary battery as defined in the first embodiment,

[0018] The coating has a thickness of 0.1 μm to 5 μm.

[0019] According to a third embodiment, there is provided an electrode lead of a secondary battery as defined in the first or second embodiment,

[0020] The gas release portion has a structure formed by partially or entirely removing the coating layer in a thickness direction through a physical etching process or a chemical etching process.

[0021] According to a fourth embodiment, there is provided an electrode lead of a secondary battery as defined in the third embodiment,

[0022] The gas release portion has a structure formed by removing the coating layer in the thickness direction by 50% to 100% based on the total thickness of the coating layer.

[0023] According to a fifth embodiment, there is provided an electrode lead of a secondary battery as defined in any one of the first to fourth embodiments,

[0024] Herein, the gas release portion has a structure formed by coating with at least one non-adhesive material selected from the group consisting of a polyimide-based material, a fluorine-based material, and polymethylpentene.

[0025] According to a sixth embodiment, there is provided an electrode lead of a secondary battery as defined in the fifth embodiment,

[0026] Wherein, the fluorine-based material includes at least one selected from the group consisting of polytetrafluoroethylene and polyvinylidene fluoride.

[0027] According to a seventh embodiment, there is provided an electrode lead of a secondary battery as defined in any one of the first to sixth embodiments,

[0028] The non-adhesive material is coated to a thickness of 30 nm to 10 μm.

[0029] According to an eighth embodiment, there is provided an electrode lead of a secondary battery as defined in any one of the first to seventh embodiments,

[0030] Wherein, the gas releasing portion has a plane shape selected from a circular shape, an elliptical shape and a polygonal shape.

[0031] According to a ninth embodiment, there is provided an electrode lead of a secondary battery as defined in any one of the first to eighth embodiments,

[0032] Here, the gas release portion is formed with an area corresponding to 10% to 70% based on the total area of ​​the electrode lead.

[0033] According to a tenth embodiment, there is provided an electrode lead of a secondary battery as defined in any one of the first to ninth embodiments,

[0034] The metal substrate includes at least one selected from the group consisting of nickel (Ni), aluminum (Al), copper (Cu) and stainless steel.

[0035] According to an eleventh embodiment, there is provided an electrode lead of a secondary battery as defined in any one of the first to tenth embodiments,

[0036] Wherein, the coating includes at least one selected from the group consisting of chromium (Cr), nickel (Ni), iron (Fe), molybdenum (Mo), silicon (Si), titanium (Ti), niobium (Cb), silicon oxide, tin oxide and titanium oxide.

[0037] In another aspect of the present disclosure, provided is a secondary battery according to any one of the following embodiments.

[0038] According to the twelfth embodiment,

[0039] Provided is a secondary battery including an electrode assembly, the electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and the electrode assembly is accommodated in a battery case together with an electrolyte,

[0040] Wherein, the positive electrode comprises a positive electrode connector, and the negative electrode comprises a negative electrode connector,

[0041] The positive electrode connector is electrically connected to the positive electrode lead, the negative electrode connector is electrically connected to the negative electrode lead, and the positive electrode lead and the negative electrode lead are exposed to the outside through the sealing portion of the battery case,

[0042] An insulating film is attached to a portion where the positive electrode lead and the negative electrode lead are in contact with the sealing portion of the battery case, and

[0043] At least one of the positive electrode lead and the negative electrode lead includes a metal substrate and a coating formed on a surface of the metal substrate.

[0044] A gas release portion is formed on at least one of the top and bottom surfaces of the electrode lead at a portion where the insulating film is attached, and the gas release portion has a structure formed by surface treatment with a non-adhesive material or by removing the coating.

[0045] According to a thirteenth embodiment, there is provided the secondary battery as defined in the twelfth embodiment,

[0046] The coating has a thickness of 0.1 μm to 5 μm.

[0047] According to a fourteenth embodiment, there is provided a secondary battery as defined in the twelfth or thirteenth embodiment,

[0048] The gas release portion has a structure formed by partially or entirely removing the coating layer in a thickness direction through a physical etching process or a chemical etching process.

[0049] According to a fifteenth embodiment, there is provided a secondary battery as defined in the fourteenth embodiment,

[0050] The gas release portion has a structure formed by removing the coating layer in the thickness direction by 50% to 100% based on the total thickness of the coating layer.

[0051] According to a sixteenth embodiment, there is provided the secondary battery as defined in any one of the twelfth to fifteenth embodiments,

[0052] Herein, the gas release portion has a structure formed by coating with at least one non-adhesive material selected from the group consisting of a polyimide-based material, a fluorine-based material, and polymethylpentene.

[0053] According to a seventeenth embodiment, there is provided a secondary battery as defined in the sixteenth embodiment,

[0054] Wherein, the fluorine-based material includes at least one selected from the group consisting of polytetrafluoroethylene and polyvinylidene fluoride.

[0055] According to an eighteenth embodiment, there is provided the secondary battery as defined in any one of the twelfth to seventeenth embodiments,

[0056] The non-adhesive material is coated to a thickness of 30 nm to 10 μm.

[0057] According to a nineteenth embodiment, there is provided the secondary battery as defined in any one of the twelfth to eighteenth embodiments,

[0058] Wherein, the gas releasing portion has a plane shape selected from a circular shape, an elliptical shape and a polygonal shape.

[0059] According to a twentieth embodiment, there is provided a secondary battery as defined in any one of the twelfth to nineteenth embodiments,

[0060] The gas release portion is formed with an area corresponding to 20% to 90% of a total area in which the electrode lead is in contact with the insulating film.

[0061] According to a twenty-first embodiment, there is provided the secondary battery as defined in any one of the twelfth to twentieth embodiments,

[0062] The bonding strength between the gas release portion and the insulating film is 20% to 80% of the bonding strength between the electrode lead and the insulating film except for the gas release portion.

[0063] Beneficial Effects

[0064] An electrode lead of a secondary battery according to an embodiment of the present disclosure has a gas release portion to provide increased utility value.

[0065] In addition, the gas release portion can be formed by a simplified process of providing a non-bonding surface to an insulating film to be subsequently bonded to an electrode lead, and thus can be formed quickly and efficiently. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 is a schematic diagram illustrating an electrode lead of a secondary battery according to an embodiment of the present disclosure.

[0067] Figure 2 is a schematic diagram illustrating a secondary battery including an electrode lead according to another embodiment of the present disclosure.

[0068] Figure 3 An electrode lead according to another embodiment of the present disclosure is illustrated.

[0069] Figures 4 to 7is a schematic diagram illustrating a method for manufacturing an electrode lead according to another embodiment of the present disclosure.

[0070] Figure 8 The electrode lead according to Example 3 is illustrated.

[0071] Fig. 9 is a graph illustrating the adhesive strength between the positive electrode lead of Example 1 and the insulating film according to Test Example 1.

[0072] Fig.10 is a graph illustrating the adhesive strength between the negative electrode lead of Example 2 and the insulating film according to Test Example 1.

[0073] Fig.11 is a graph illustrating the adhesive strength between the positive electrode lead of Example 1 and the insulating film according to Test Example 2.

[0074] Fig.12 is a graph illustrating the adhesive strength between the negative electrode lead of Example 2 and the insulating film according to Test Example 2.

[0075] Fig.13 is a graph illustrating the gas release amount of the gas release portion of Example 3 over time. DETAILED DESCRIPTION

[0076] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0077] Before proceeding with the description, it should be understood that the terms used in the specification and the appended claims should not be construed as limited to the general meanings and dictionary meanings, but should be interpreted based on the meanings and concepts corresponding to the technical aspects of the present disclosure on the basis of the principle that enables the inventor to define terms suitable for the best description.

[0078] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present disclosure.As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0079] It should also be understood that the terms "include" and / or its variations, "comprises" and / or its variations, or "has" and / or its variations, when used in this specification, indicate the presence of the stated features, quantities, steps, elements, or a combination thereof, but do not exclude the presence or addition of one or more other features, quantities, steps, elements, or a combination thereof.

[0080] In one aspect of the present disclosure,

[0081] Provided is an electrode lead for a secondary battery,

[0082] The electrode lead includes a metal substrate and a coating formed on a surface of the metal substrate.

[0083] At least one of the top and bottom surfaces of the electrode lead has a gas release portion having a structure formed by surface treatment with a non-adhesive material or by removing a coating.

[0084] Herein, the coating layer may include a coating layer for improving adhesion with an insulating film while preventing corrosion of the electrode lead due to a strong acid or the like.

[0085] The coating may have a thickness of 0.1 μm to 5 μm.

[0086] When the thickness of the coating layer satisfies the above-defined range, it is possible to prevent the thickness of the electrode lead from being excessively increased, while preventing the electrode lead from being corroded by strong acid generated inside the secondary battery.

[0087] In addition, according to the related art, various methods for forming a gas release portion for releasing the gas generated inside the secondary battery to the outside have been developed. For example, attempts have been made to ensure the safety of the secondary battery by releasing the gas inside the secondary battery by forming a notch in the bag, forming a separate gas release member between the lead parts, etc.

[0088] However, the above-mentioned method may not be advantageous in terms of processing efficiency and cost competitiveness because the secondary battery can no longer be used when exhausted, thereby causing significant deterioration in the life of the battery and requiring a separate component.

[0089] On the contrary, according to the present disclosure, a gas release portion can be formed on an electrode lead of a secondary battery through a simplified process, thereby improving the life of the secondary battery while ensuring the safety of the secondary battery.

[0090] In particular, the gas release portion formed on at least one surface of the electrode lead can be formed by a very simple and economical process.

[0091] For example, the gas release portion may be formed by partially or completely removing the coating in the thickness direction using a physical or chemical etching process, wherein the gas release portion may have a structure formed by removing the coating in the thickness direction by 50% to 100% based on the total thickness of the coating.

[0092] When the removal of the coating satisfies the range defined above, it is possible to ensure the effect of exhaust and prevent the electrode lead itself from being damaged.

[0093] Herein, the physical or chemical etching process is not particularly limited as long as it can remove the coating. For example, physical etching or chemical etching can be practiced by wet etching process using ultraviolet ozone (UVO) treatment and exposure to an acidic solution, sputtering etching process, plasma etching process, etc. In other words, the gas release portion can be formed by setting a mask on the electrode lead and removing the coating of the electrode lead by various etching processes, wherein the mask has an opening corresponding to the shape of the gas release portion to be formed on the electrode lead.

[0094] Hereinafter, this method will be described in more detail.

[0095] In a modified form, the gas release portion may be formed by coating a polymer having a melting point of 220° C. or higher. In addition, the gas release portion may be formed by coating a polymer having a glass transition temperature of 100° C. or higher. When the gas release portion uses a polymer having a glass transition temperature range defined above, the gas release portion may be more easily formed when the electrode lead is attached to the insulating film as described below.

[0096] The melting point can be determined by using a differential scanning calorimeter (DSC). For example, after the temperature of the sample is increased from 30°C to 280°C at a rate of 10°C / min, the sample is allowed to stand at 280°C for 10 minutes, cooled to 30°C at a rate of 10°C / min, and the sample is allowed to stand at 30°C for 10 minutes. Then, the temperature of the sample is increased from 30°C to 280°C at a rate of 10°C / min, the sample is allowed to stand at 280°C for 10 minutes to measure the temperature of each melting peak, and the top of the DSC curve is regarded as the melting point.

[0097] The glass transition temperature can be determined by using a differential scanning calorimeter (DSC). For example, after the temperature of the sample is increased from 30°C to 280°C at a rate of 10°C / min, the sample is allowed to stand at 280°C for 10 minutes, cooled to 30°C at a rate of 10°C / min, and the sample is allowed to stand at 30°C for 10 minutes. Then, the glass transition temperature can be determined by measuring the intersection of the endothermic heat when the temperature is maintained and the tangent at the inflection point of the enthalpy curve obtained by increasing the temperature of the sample from 30°C to 280°C at a rate of 10°C / min and leaving the sample at 280°C for 10 minutes.

[0098] According to an embodiment of the present disclosure, the gas release portion may be formed by coating with at least one non-adhesive material selected from the group consisting of a polyimide-based material, polytetrafluoroethylene, a polyvinylidene fluoride-based material, and polymethylpentene.

[0099] The non-adhesive material is a material that does not adhere to an insulating film that is subsequently attached to an electrode lead.

[0100] The non-adhesive material may be applied by a conventional known coating process without particular limitation. For example, the non-adhesive material may be applied by a spin coating process, a blade coating process, a spray coating process, or an inkjet printing process, wherein, similar to the above-mentioned method, in order to form a gas release portion having a specific shape, a mask having an opening corresponding to the shape of the gas release portion may be used. In a modified form, the non-adhesive material may be transferred by a rolling process.

[0101] Hereinafter, this method will be described in more detail.

[0102] Herein, the non-adhesive material may be coated to a thickness of 30 nm to 10 μm.

[0103] When the thickness of the non-adhesive material satisfies the range defined above, there is no difficulty in processing, and problems such as leakage of electrolyte caused by insufficient sealing of other parts can be easily prevented.

[0104] In other words, when the insulating film is subsequently attached to the electrode lead during the manufacture of the secondary battery, the gas release portion can be formed by a very simple process of forming a portion where the insulating film is not attached to the electrode lead.

[0105] Therefore, gas inside the secondary battery may be released to the outside through the portion not attached to the insulating film.

[0106] In this way, according to the present disclosure, the gas release portion can be formed by a very simple and economical process of removing the coating of the electrode lead showing high adhesion to the insulating film or applying a material without adhesion to the insulating film. Therefore, the desired effect of the present disclosure can be achieved with high processing efficiency and cost efficiency.

[0107] Herein, the gas release portion may be formed in an area corresponding to 10% to 70% (particularly, 20% to 50%) based on the total plane area of ​​the electrode lead in consideration of an area where an insulating film is subsequently attached.

[0108] When the area of ​​the gas release portion satisfies the range defined above, it is possible to form the gas release portion at the insulating film attachment portion and prevent sealing-related problems such as excessive peeling of the coating and electrolyte leakage.

[0109] In addition, the gas release portion has any planar shape without particular limitation, and may have various shapes such as a circular, elliptical or polygonal shape. However, the gas release portion may be formed with a pattern capable of efficiently releasing gas while preventing problems such as electrolyte leakage.

[0110] Figure 1is a schematic diagram illustrating a gas release portion 101 on an electrode lead according to an embodiment of the present disclosure.

[0111] Reference Figure 1 , Figure 1 (a) shows a rectangular-shaped gas release portion 101, Figure 1 (b) shows the gas release portion 101 in an elliptical shape, Figure 1 (c) shows a gas release portion 101 having an irregular polygonal shape, and Figure 1 (d) shows a gas release portion 101 in a triangular shape.

[0112] However, Figure 1 The shapes shown in FIG. 1 are for illustrative purposes only, and the scope of the present disclosure is not limited thereto.

[0113] In addition, an electrode lead according to the present disclosure includes a metal substrate and a coating layer coated on the metal substrate.

[0114] Herein, the metal substrate may include at least one selected from the group consisting of nickel (Ni), aluminum (Al), copper (Cu) and stainless steel. More specifically, the preferred material for the metal substrate may vary depending on whether the electrode lead is a positive electrode lead or a negative electrode lead. For example, in the case of a positive electrode lead, aluminum, nickel, or an alloy containing at least one of them may be used. In the case of a negative electrode lead, copper, nickel, or an alloy containing at least one of them may be used.

[0115] In addition, the electrode lead according to the present disclosure may have a coating formed on a metal substrate, and the coating prevents water from penetrating into the secondary battery and reacting with the electrolyte to generate a strong acid that causes corrosion of the secondary battery, and improves adhesion to the insulating film. Herein, the coating may include a metal or a metal oxide, specifically, at least one selected from the group consisting of chromium (Cr), nickel (Ni), iron (Fe), molybdenum (Mo), silicon (Si), titanium (Ti), niobium (Cb), silicon oxide, tin oxide, and titanium oxide.

[0116] Herein, the thickness of the coating layer may be 5 μm or less, specifically, 0.1 μm to 5 μm, more specifically, 0.1 μm to 0.5 μm, and most specifically 0.2 μm to 0.3 μm.

[0117] When the coating thickness satisfies the above-defined range, corrosion of the electrode lead caused by strong acid generated in the secondary battery can be prevented, and an excessive increase in the thickness of the electrode lead can be suppressed.

[0118] In addition, the coating layer can be formed by using conventional methods well known to those skilled in the art without particular limitation. For example, the coating layer can be formed by electroplating or the like.

[0119] The gas release portion according to the present disclosure is formed by partially or entirely removing the coating layer in a thickness direction or by surface-treating the coating layer using a non-adhesive material.

[0120] In another aspect of the present disclosure, there is provided a secondary battery including an electrode assembly,

[0121] The electrode assembly includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and the electrode assembly is accommodated in a battery case together with an electrolyte.

[0122] The positive electrode includes a positive electrode connector, and the negative electrode includes a negative electrode connector.

[0123] The positive electrode tab is electrically connected to the positive electrode lead, the negative electrode tab is electrically connected to the negative electrode lead, and the positive electrode lead and the negative electrode lead are exposed to the outside through the sealing portion of the battery case.

[0124] An insulating film is attached to a portion where the positive electrode lead and the negative electrode lead are in contact with a sealing portion of the battery case, and

[0125] At least one of the positive electrode lead and the negative electrode lead includes a metal substrate and a coating formed on a surface of the metal substrate,

[0126] A gas release portion is formed on at least one of the top and bottom surfaces of the electrode lead at a portion where the insulating film is attached, the gas release portion having a structure formed by surface treatment with a non-adhesive material or by removing a coating.

[0127] Will refer to Figure 2 The secondary battery will be described in more detail. Figure 2 is a schematic diagram illustrating a secondary battery 200 according to an embodiment of the present disclosure.

[0128] Reference Figure 2 An electrode assembly 201 including a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode is contained in a battery case 202 together with an electrolyte, wherein the positive electrode includes a positive electrode connector 203 and the negative electrode includes a negative electrode connector 204, the positive electrode connector 203 is electrically connected to a positive electrode lead 110, the negative electrode connector 204 is electrically connected to a negative electrode lead 100, and the positive electrode lead 110 and the negative electrode lead 100 are exposed to the outside through a sealing portion of the battery case 202, and insulating films 205 and 206 are attached to portions of the positive electrode lead 110 and the negative electrode lead 100 that contact the sealing portion of the battery case 202.

[0129] Herein, when the negative electrode lead 100 is enlarged to view its structure (part A), it can be seen that the gas release portion 101 is partially formed in a portion where the insulating film 206 is attached to the negative electrode lead 100 .

[0130] Herein, the gas release portion 101 is not bonded to the insulating film 205 so as to provide a gas release path.

[0131] Although not shown in the drawings, the gas release portion may be formed in the positive electrode lead 110 , or in both the positive electrode lead 110 and the negative electrode lead 120 .

[0132] In addition, the gas release portion 101 may be formed at an area corresponding to 20% to 90% (particularly, 30% to 80%) based on an area where the electrode lead is in contact with the insulating film.

[0133] When the area of ​​the gas release portion 101 satisfies the above-defined range, it is possible to ensure the exhaust effect while ensuring an area in which the sealing property between the electrode lead and the insulating film can be maintained.

[0134] In addition, the structure, shape, material, etc. of the gas release portion 101 are the same as those described above. In addition, the other constituent elements of the electrode lead are the same as those described above.

[0135] Figure 3 An electrode lead 100 according to another embodiment of the present disclosure is illustrated.

[0136] Reference Figure 3 , the electrode lead 100 is exposed to the outside through the sealing portion of the battery case 202, and the insulating film 205 is attached to the portion where the electrode lead 100 contacts the sealing portion of the battery case 202. Herein, it can be seen that the gas release portion 101 is formed in a portion of the electrode lead 100.

[0137] Reference Figure 3 The gas release portion 101 includes a first gas release portion 101A and a second gas release portion 101B connected to each other, wherein the first gas release portion 101A may extend along the width direction of the electrode lead, and the second gas release portion 101B may extend along the protruding direction of the electrode lead.

[0138] Reference Figure 3 , the length of the first gas releasing portion 101A may be smaller than the width of the electrode lead.

[0139] In addition, refer to Figure 3, based on the protruding direction of the electrode lead, the end of the second gas release portion 101B on the outside of the battery can be arranged more inwardly in the battery than the end of the portion of the electrode lead facing the insulating film on the outside of the battery. In addition, the other end of the second gas release portion 101B on the inside of the battery can be arranged more inwardly in the battery than the end of the portion of the electrode lead facing the insulating film on the inside of the battery. In addition, the insulating films 205, 206 may include any material selected from electrically insulating thermoplastics, thermosetting and light-curing resins. For example, the material may include butadiene-styrene resins, styrene resins, epoxy resins, polyurethane resins, acrylic resins, phenolic resins, amide resins, acrylate resins and modified resins thereof. However, the material is not particularly limited as long as it can perform the functions mentioned above.

[0140] Reference will be made to known contents regarding other specifications of the insulating film.

[0141] The adhesive strength between the gas release portion 101 of the electrode lead 100 formed according to the present disclosure and the insulating film 206 may be 20% to 30%, specifically 30% to 70%, of the adhesive strength between the electrode lead 100 and the insulating film 206 excluding the gas release portion 101 .

[0142] Herein, the bonding strength can be obtained by performing melt fusion of the electrode lead forming the gas release portion 101 with the insulating film 206 made of polypropylene, storing the resulting structure in a chamber including 30 g of an electrolyte and 1.3 g of dry ice at 60°C and 90% RH for 2 weeks, partially peeling the electrode lead from the insulating film, and measuring the strength depending on strain loading by using UTM while pulling the electrode lead and the insulating film at 180°.

[0143] Furthermore, the battery case is not particularly limited but may be a pouch-type battery case that allows the above-described configuration to be appropriately utilized.

[0144] Since other constituent elements such as a positive electrode, a negative electrode, a separator, a positive electrode terminal, a negative electrode terminal, a battery case, and an electrolyte are known to those skilled in the art, a detailed description thereof will be omitted herein.

[0145] In addition, as described above, the gas release portion 101 has a structure formed by removing a coating or by performing a surface treatment with a non-adhesive material. Figures 4 to 7 This structure is described in more detail.

[0146] According to an embodiment of the present disclosure, the gas release portion may be formed by removing a coating layer.

[0147] In particular, the gas release portion may be formed by a method including the following steps: (a) preparing a preliminary electrode lead including a metal substrate and a coating layer formed on a surface of the metal substrate;

[0148] (b) preparing a mask including an opening corresponding to the shape of a gas release portion to be formed in the electrode lead; and

[0149] (c) placing a mask on at least one of the top surface and the bottom surface of the preliminary electrode lead,

[0150] And the coating is partially removed in a shape corresponding to the opening of the mask.

[0151] exist Figure 4 and Figure 5 A specific embodiment of a method for partial removal of a coating is shown in FIG.

[0152] First, refer to Figure 4 , showing a method of forming a gas release portion by a physical etching process.

[0153] In particular, a mask 310 including an opening 311 corresponding to the shape of a gas release portion 301 to be formed is set on the preliminary electrode lead 300, and a gas ionized by a sputtering device 320 is impacted through the opening 311 of the mask 310 to remove a coating having a shape corresponding to the opening 311 from the preliminary electrode lead 300, thereby forming the gas release portion 301.

[0154] In addition, refer to Figure 5 , showing a method of forming a gas release portion by a chemical etching process.

[0155] Specifically, a mask 410 including an opening 411 is disposed on the preliminary electrode lead 400 , and an acid solution 420 is introduced through the opening 411 to perform a chemical etching process so that the coating of the preliminary electrode lead 400 may be removed, thereby forming a gas release portion 401 .

[0156] Herein, the acidic solution 420 is not particularly limited as long as it is acidic and can remove the coating. For example, the acidic solution may be a mixed solution of perchloric acid and ammonium nitrate.

[0157] According to another embodiment, the gas release portion on the electrode lead may be formed by surface-treating the electrode lead with a non-adhesive material that does not adhere to the insulating film.

[0158] Specifically, the gas release portion may be formed by a method including the following steps: (a) preparing a preliminary electrode lead including a metal substrate and a coating layer formed on a surface of the metal substrate; and

[0159] (b) surface treating a portion of at least one of the top surface and the bottom surface of the preliminary electrode lead with a non-adhesive material,

[0160] To form a gas release portion.

[0161] exist Figure 6 and Figure 7 A specific implementation of this method is shown in FIG.

[0162] Reference Figure 6 , showing a coating process such as spray coating, inkjet coating or doctor blade coating.

[0163] In particular, a mask 510 including an opening 511 corresponding to the shape of a gas release portion 501 to be formed is disposed on at least one of the top and bottom surfaces of the preliminary electrode lead 500, and a non-adhesive material 521 is applied through the opening 511 of the mask 510 by using various methods such as a spray coater 520 to form the gas release portion 501.

[0164] In deformed form, Figure 7 A method of coating a non-adhesive material by a roll pressing process is exemplified.

[0165] In particular, the gas release portion 601 is formed by transferring and coating the non-adhesive material 611 onto the surface of the preliminary electrode lead 600 through a pressing process using a roller 610 on which a non-adhesive material 611 is formed (the non-adhesive material 611 has a shape corresponding to the shape of the gas release portion 601).

[0166] Herein, specific examples of the non-adhesive materials 521 , 611 are the same as described above.

[0167] Mode of the present disclosure

[0168] Hereinafter, the present disclosure will be described with reference to preferred examples, comparative examples and test examples. However, it should be understood that the specific examples are given by way of illustration only, as various changes and modifications within the scope of the present disclosure will be apparent to those skilled in the art from the detailed description.

[0169] <Example 1>

[0170] A preliminary electrode lead including an aluminum (Al) foil having a thickness of 200 μm and coated with chromium (Cr) to a thickness of 0.2 μm was irradiated with laser (output: 70 W, wavelength: 300 nm) to perform the following steps: Figure 1 Etching of the rectangular shape of Cr shown in (a) (no Cr layer is left at the corresponding portion).

[0171] Then, a polypropylene film (thickness: 100 μm) as an insulating film was stacked on the corresponding portion and fused therewith in such a manner that it could cover the corresponding portion to prepare an electrode lead / insulating film laminate.

[0172] <Example 2>

[0173] An electrode lead / insulating film laminate was obtained in the same manner as in Example 1 except that a preliminary electrode lead including a copper (Cu) foil having a thickness of 200 μm and coated with nickel (Ni) to a thickness of 1 μm and chromium (Cr) to a thickness of 0.2 μm was used.

[0174] <Example 3>

[0175] On the surface of the preliminary electrode lead 100 including an aluminum (Al) foil having a thickness of 200 μm and coated with chromium (Cr) to a thickness of 0.2 μm, by Figure 8 The copolymer of vinylidene monomer, hexafluoropropylene monomer and tetrafluoroethylene monomer was applied using a T-shaped dispenser as shown in . After the application was completed, UV rays were irradiated at 3W to perform curing for 30 seconds, and hot air drying was performed at 140°C for 5 minutes to form a gas release portion 101.

[0176] Then, polypropylene films (thickness: 100 μm) as insulating films were stacked and fused in such a manner that they could cover the corresponding portions to prepare an electrode lead / insulating film laminate, such as Figure 8 as shown in .

[0177] <Test Example 1>

[0178] Each of the laminate according to Example 1 and the laminate according to Example 2 was stored in a chamber containing 30 g of a solution of fluoroethylene carbonate (FEC) and ethyl methyl carbonate (EMC) in a volume ratio of 3:7 and 1M LiFSI dissolved therein and 1.3 g of dry ice at 60°C and 90% RH for 2 weeks.

[0179] After 2 weeks, each laminate was mounted on a UTM system (LLOYD Instrument LF Plus) and a force was applied thereto at a rate of 300 mm / min at 180° to determine the separation strength (i.e., adhesion strength) required to separate the insulating film and the electrode lead from each other. Fig. 9 and Fig.10 Shown in.

[0180] Reference Fig. 9 and Fig.10 , it can be seen that the bonding strength is significantly reduced at the portion where Cr is removed by laser processing.

[0181] <Test Example 2>

[0182] Each of the laminate according to Example 1 and the laminate according to Example 2 was immersed in a solution containing fluoroethylene carbonate (FEC) and ethyl methyl carbonate (EMC) in a volume ratio of 3:7 and 1M LiFSI dissolved therein in an oven at 25°C (RT), 60°C, 80°C or 100°C for 1 day. Then, the laminate was taken out and mounted on a UTM system (LLOYDInstrument LF Plus), and a force was applied thereto at a rate of 300 mm / min at 180° to determine the separation strength (i.e., adhesive strength) required to separate the insulating film and the electrode lead from each other. The results were Fig.11 and Fig.12 Shown in.

[0183] Reference Fig.11 and Fig.12 , it can be seen that as the temperature increases, the gas release part is more effective.

[0184] <Test Example 3>

[0185] Fig.13 is a graph illustrating the amount of gas release of the electrode lead / insulating film laminate of Example 3 over time.

[0186] The amount of gas released over time is determined by the following steps: three secondary batteries are prepared, each including an electrode lead / insulating film laminate according to Example 3 and a gas pipeline capable of injecting gas from the outside, gas is injected from the outside through the gas pipeline at a rate of 50sc / cm to a pressure of 1, 1.5 or 2atm, how the pressure changes over time is observed, and the gas release amount is calculated based on the correlation equation between pressure and gas injection amount.

[0187] from Fig.13 As can be seen in FIG. 1 , the gas release portion according to the present disclosure can function under various conditions.

[0188] It should be understood that various changes and modifications within the scope of the present disclosure will be apparent to those skilled in the art from this detailed description.

Claims

1. An electrode lead of a secondary battery, the electrode lead comprising a metal substrate and a coating formed on a surface of the metal substrate, wherein: At least one of the top and bottom surfaces of the electrode lead has a gas release portion having a structure formed by surface treatment with a non-adhesive material or by removing the coating, The non-adhesive material is coated on the coating layer, and the non-adhesive material is a material that does not adhere to an insulating film attached to the electrode lead.

2. The electrode lead of a secondary battery according to claim 1, wherein: The coating has a thickness of 0.1 μm to 5 μm.

3. The electrode lead of the secondary battery according to claim 1, wherein: The gas release portion has a structure formed by partially or entirely removing the coating layer in a thickness direction through a physical etching process or a chemical etching process.

4. The electrode lead of the secondary battery according to claim 3, wherein: The gas release portion has a structure formed by removing the coating layer in the thickness direction by 50% to 100% based on the total thickness of the coating layer.

5. The electrode lead of a secondary battery according to claim 1, wherein: The gas release portion has a structure formed by coating with at least one non-adhesive material selected from the group consisting of a polyimide-based material, a fluorine-based material, and polymethylpentene.

6. The electrode lead of the secondary battery according to claim 5, wherein: The fluorine-based material includes at least one selected from the group consisting of polytetrafluoroethylene and polyvinylidene fluoride.

7. The electrode lead of a secondary battery according to claim 1, wherein: The non-adhesive material is coated to a thickness of 30 nm to 10 μm.

8. The electrode lead of a secondary battery according to claim 1, wherein: The gas release portion has a planar shape selected from a circular shape, an elliptical shape, and a polygonal shape.

9. The electrode lead of a secondary battery according to claim 1, wherein: The gas release portion is formed with an area corresponding to 10% to 70% based on a total area of ​​the electrode lead.

10. The electrode lead of a secondary battery according to claim 1, wherein: The metal substrate includes at least one selected from the group consisting of nickel Ni, aluminum Al, copper Cu, and stainless steel.

11. The electrode lead of a secondary battery according to claim 1, wherein: The coating layer includes at least one selected from the group consisting of chromium Cr, nickel Ni, iron Fe, molybdenum Mo, silicon Si, titanium Ti, niobium Cb, silicon oxide, tin oxide, and titanium oxide.

12. A secondary battery comprising an electrode assembly, the electrode assembly comprising a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and the electrode assembly is accommodated in a battery case together with an electrolyte, in, The positive electrode includes a positive electrode contact, and the negative electrode includes a negative electrode contact, The positive electrode connector is electrically connected to the positive electrode lead, the negative electrode connector is electrically connected to the negative electrode lead, and the positive electrode lead and the negative electrode lead are exposed to the outside through the sealing portion of the battery case, An insulating film is attached to a portion where the positive electrode lead and the negative electrode lead are in contact with the sealing portion of the battery case, and At least one of the positive electrode lead and the negative electrode lead includes a metal substrate and a coating formed on a surface of the metal substrate, wherein a gas release portion is formed on at least one of a top surface and a bottom surface of the electrode lead at a portion to which the insulating film is attached, the gas release portion having a structure formed by surface treatment with a non-adhesive material or by removing the coating, The non-adhesive material is coated on the coating layer, and the non-adhesive material is a material that does not adhere to the insulating film attached to the electrode lead.

13. The secondary battery according to claim 12, wherein: The coating has a thickness of 0.1 μm to 5 μm.

14. The secondary battery according to claim 12, wherein: The gas release portion has a structure formed by partially or entirely removing the coating layer in a thickness direction through a physical etching process or a chemical etching process.

15. The secondary battery according to claim 14, wherein The gas release portion has a structure formed by removing the coating layer in the thickness direction by 50% to 100% based on the total thickness of the coating layer.

16. The secondary battery according to claim 12, wherein The gas release portion has a structure formed by coating with at least one non-adhesive material selected from the group consisting of a polyimide-based material, a fluorine-based material, and polymethylpentene.

17. The secondary battery according to claim 16, wherein The fluorine-based material includes at least one selected from the group consisting of polytetrafluoroethylene and polyvinylidene fluoride.

18. The secondary battery according to claim 12, wherein The non-adhesive material is coated to a thickness of 30 nm to 10 μm.

19. The secondary battery according to claim 12, wherein The gas release portion has a planar shape selected from a circular shape, an elliptical shape, and a polygonal shape.

20. The secondary battery according to claim 12, wherein The gas release portion is formed with an area corresponding to 20% to 90% based on a total area in which the electrode lead is in contact with the insulating film.

21. The secondary battery according to claim 12, wherein The adhesive strength between the gas release portion and the insulating film is 20% to 80% based on the adhesive strength between the electrode lead excluding the gas release portion and the insulating film.

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