Method for preparing corrosion preventing layer and cylindrical secondary battery

Abstract

This specification relates to a method for manufacturing a corrosion-preventive layer, and A method for manufacturing a corrosion-preventive layer of a cylindrical secondary battery comprising: a jelly-roll type electrode assembly having a structure in which a first electrode, a second electrode, and a separator interposed between them are wound in one direction with respect to a winding axis; a battery can that accommodates the electrode assembly and includes a metal plating layer; and a connecting lead plate that joins the battery can and the electrode assembly. (A) A step of applying a corrosion-preventing resin to a damaged area of ​​the metal plating layer at a welded portion formed by the melting of the connection lead plate and the battery can when welding the outer bottom surface of the battery can; and (B) A step of curing the above-mentioned resin for the corrosion-preventing layer by ultraviolet light to form a corrosion-preventing layer Includes, The resin for the corrosion-preventive layer described above comprises one or more liquid substances, and The above one or more liquid substances are UV-curable and have a viscosity of 1 cP or more and 5000 cP or less. A method for manufacturing a corrosion-preventive layer is provided.

Description

Technology Field

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2021-0030319 filed with the Korean Intellectual Property Office on March 8, 2021, and all contents disclosed in the document of said Korean patent application are incorporated into this specification.

[0002] The present invention relates to a method for manufacturing a corrosion-preventing layer and a cylindrical secondary battery, and more specifically, to a method for manufacturing a corrosion-preventing layer capable of preventing corrosion of a battery can and a cylindrical secondary battery. Background Technology

[0003] Conventional cylindrical secondary batteries have a structure in which a tab connecting the jelly-roll electrode assembly and the external terminal is welded to the foil of the jelly-roll electrode assembly. Cylindrical secondary batteries with this structure had the problem of a limited current path and high resistance of the jelly-roll electrode assembly itself.

[0004] To improve this, attempts have been made to lower resistance by increasing the number of taps, but there are limitations in securing a sufficient current path or lowering resistance to the desired level. To overcome these limitations, there are attempts to lower resistance in the welding process applied to battery cans.

[0005] However, the exterior of a cylindrical secondary battery can is typically composed of a metal plating layer, and since the electrode welding process is laser welding, bottom welding can be performed on the exterior of the battery can made of a metal plating layer, which can cause damage to the metal plating layer constituting the exterior of the battery can.

[0006] If the metal plating layer is damaged in this way, the surface is exposed to the air, and the battery can may corrode.

[0007] To resolve the above problem, a method of applying an anti-corrosion solution to the metal plating layer and then washing it was applied. However, even with the above method, the anti-corrosion solution components can be easily removed, so the battery can can easily corrode.

[0008] Therefore, other materials or methods are required to comprehensively resolve the above problems and efficiently prevent corrosion of battery cans. The problem to be solved

[0009] To resolve the aforementioned problems, one objective of the present invention is to provide a method for manufacturing a corrosion-preventing layer and a cylindrical secondary battery.

[0010] However, the problems that the present invention aims to solve are not limited to those described above, and other problems not mentioned in this specification will be clearly understood by a person skilled in the art from the description of the invention that follows. means of solving the problem

[0011] To achieve the above-mentioned objective, the present invention provides a method for manufacturing a corrosion-resistant layer and a secondary battery according to the following aspects.

[0012] According to one aspect of the present invention, a method for manufacturing a corrosion-preventing layer of a cylindrical secondary battery comprising a jelly-roll type electrode assembly having a structure in which a first electrode, a second electrode, and a separator interposed between them are wound in one direction with respect to a winding axis, a battery can that accommodates the electrode assembly and includes a metal plating layer, and a connecting lead plate that joins the battery can and the electrode assembly, wherein

[0013] (A) A step of applying a corrosion-preventing resin to a damaged area of ​​the metal plating layer at a welded portion formed by the melting of the connection lead plate and the battery can when welding the outer bottom surface of the battery can; and

[0014] (B) A step of curing the above-mentioned resin for the corrosion-preventing layer by ultraviolet light to form a corrosion-preventing layer

[0015] Includes,

[0016] The resin for the corrosion-preventive layer described above comprises one or more liquid substances, and

[0017] The above one or more liquid substances are UV-curable and have a viscosity of 1 cP or more and 5000 cP or less.

[0018] A method for manufacturing a corrosion-preventive layer is provided.

[0019] According to one aspect of the present invention, a jelly-roll type electrode assembly having a structure in which a first electrode, a second electrode, and a separator interposed between them are wound in one direction with respect to a winding axis;

[0020] A battery can accommodating the above electrode assembly and including a metal plating layer;

[0021] A connecting lead plate for joining the above-mentioned battery can and electrode assembly; and

[0022] A corrosion-resistant layer manufactured by the method for manufacturing the corrosion-resistant layer described above.

[0023] A cylindrical secondary battery comprising

[0024] According to one aspect of the present invention, a jelly-roll type electrode assembly having a structure in which a first electrode, a second electrode, and a separator interposed between them are wound in one direction with respect to a winding axis;

[0025] A battery can accommodating the above electrode assembly and including a metal plating layer;

[0026] A connecting lead plate for joining the above-mentioned battery can and electrode assembly; and

[0027] A corrosion-preventing layer is disposed at a damaged portion of the outer surface of the battery can at a welded portion formed by the melting of the connection lead plate on the outer bottom surface of the battery can and the battery can.

[0028] A cylindrical secondary battery comprising Effects of the invention

[0029] A method for manufacturing a corrosion-preventing layer and a cylindrical secondary battery according to one aspect of the present invention can prevent corrosion of the battery can due to damage to the metal plating layer caused by welding on the battery can, thereby preventing product defects.

[0030] A method for manufacturing a corrosion-preventive layer according to one aspect of the present invention is simple because the resin for the corrosion-preventive layer is easily cured by ultraviolet rays. In addition, after applying the resin for the corrosion-preventive layer, the metal plating layer present on the outside of the battery can is prevented from being exposed to corrosive factors such as air and moisture, thereby preventing corrosion of the battery can and improving the safety of the battery.

[0031] A method for manufacturing a corrosion-resistant layer and a cylindrical secondary battery according to one aspect of the present invention can provide the advantage of not being deformed under an activation process (typically, left for approximately 24 hours under high temperature and high humidity conditions (a temperature of about 65°C or higher, a humidity of about 90% or higher)).

[0032] However, the effects obtainable through the present invention are not limited to those described above, and other technical effects not mentioned in this specification will be clearly understood by a person skilled in the art from the description of the invention that follows. Brief explanation of the drawing

[0033] FIGS. 1 and 2 are schematic diagrams illustrating an embodiment of the present invention. Specific details for implementing the invention

[0034] The present invention may be subject to various modifications and may include various embodiments or examples, but specific embodiments or embodiments are illustrated in the drawings and will be described in detail based thereon. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, or substitutions that fall within the technical spirit and scope of the present invention.

[0035] In this specification, terms such as first, second, A, B, etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component.

[0036] In this specification, terms such as "and / or" include a combination of multiple related items or some of the multiple related items.

[0037] In this specification, where a component is expressed in the singular, it may include a plural concept unless otherwise specified in this specification.

[0038] In this specification, terms such as "comprising," "having," etc., unless otherwise specified in this specification, mean the existence of the features, numbers, steps, actions, processes, components, parts, etc., or combinations thereof described in this specification, and do not mean the exclusion of other features, numbers, etc.

[0039] In this specification, the term 'battery can' may have an opening, cylindrical sides, and a bottom (or bottom surface), and may typically be made of a metal or alloy material. Preferably, the battery can may be made of nickel-plated iron (a battery can comprising a nickel-containing metal plating layer and iron).

[0040] In addition, the above 'battery can' is an object that accommodates an electrode assembly of a secondary battery. The battery can may be cylindrical, and its size may be such that the diameter of the circular portions at both ends is 30 mm to 55 mm and the height is 60 mm to 120 mm. For example, the circular diameter x height of the cylindrical battery can may be 40 mm x 60 mm, 40 mm x 80 mm, or 40 mm x 90 mm, or 40 mm x 120 mm.

[0041] In this specification, the term 'secondary battery' refers to a battery capable of repeated use for a long period through recharging. Secondary batteries may be classified into nickel-cadmium secondary batteries, lithium-ion secondary batteries, etc., depending on the electrode active material.

[0042] In this specification, the term "cylindrical secondary battery" refers to a secondary battery having a cylindrical shape or a similar form. Cylindrical secondary batteries are widely used in large-capacity electronic and electrical devices due to their high energy density per unit volume, and can be used in a form where multiple units are combined to form a battery pack. For example, a cylindrical secondary battery may have a structure in which a rivet inserted through the bottom opposite the opening is used as the cathode, and the battery can itself is used as the anode.

[0043] In this specification, the term 'first electrode' is a cathode and the term 'second electrode' is an anode, or vice versa.

[0044] In this specification, the term 'cathode' includes a cathode current collector and a cathode active material coated on at least one surface of the cathode current collector. Examples of the cathode current collector may be aluminum or an alloy, but are not limited thereto. Examples of the cathode active material may be a lithium-containing transition metal oxide, but are not limited thereto.

[0045] In this specification, the term 'anode' includes an anode current collector and an anode active material coated on at least one surface of the anode current collector. Examples of the anode current collector may be copper or an alloy, but are not limited thereto. Examples of the anode active material may be carbon materials, but are not limited thereto.

[0046] In this specification, the term "separator" refers to a membrane interposed between the cathode and the anode, which serves to separate the cathode and the anode while facilitating the movement of ions required to interrupt the circuit. Examples of the separator may include, but are not limited to, a microporous film composed of a polyolefin-based membrane.

[0047] In this specification, the term 'liquid substance' refers to a substance at room temperature (about 25°C o It refers to a substance that remains in a liquid state in C).

[0048] In this specification, the term 'ultraviolet curable' refers to the property of being cured by ultraviolet rays. For example, if a material is 'ultraviolet curable,' it refers to the material hardening and curing by ultraviolet rays.

[0049] In this specification, the term 'metal plating layer' refers to a layer applied to the outer surface of a battery can, and includes a metal plating material. For example, it may be a nickel plating layer.

[0050] In this specification, the term "damaged area" refers to an area on the exterior of a battery can (including the metal plating layer if applied) that is damaged by a welding process. The welding process is typically performed on the exterior of the bottom of the battery can. However, the metal plating layer may be damaged by this welding process. Consequently, the electrolyte may leak due to easy exposure to corrosive environments such as air and moisture.

[0051] Unless otherwise defined, all terms used in this specification, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains.

[0052] Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings.

[0053] According to one embodiment of the present invention, a method for manufacturing a corrosion-preventing layer of a cylindrical secondary battery comprising: a jelly-roll type electrode assembly having a structure in which a first electrode, a second electrode, and a separator interposed between them are wound in one direction with respect to a winding axis; a battery can that accommodates the electrode assembly and includes a metal plating layer; and a connecting lead plate that joins the battery can and the electrode assembly, wherein

[0054] (A) A step of applying a corrosion-preventing resin to a damaged area of ​​the metal plating layer at a welded portion formed by the melting of the connection lead plate and the battery can when welding the outer bottom surface of the battery can; and

[0055] (B) A step of curing the above-mentioned resin for the corrosion-preventing layer by ultraviolet light to form a corrosion-preventing layer

[0056] Includes,

[0057] The resin for the corrosion-preventive layer described above comprises one or more liquid substances, and

[0058] The above one or more liquid substances are UV-curable and have a viscosity of 1 cP or more and 5000 cP or less.

[0059] A method for manufacturing a corrosion-preventive layer is provided.

[0060] For example, the resin for the corrosion-preventing layer may have a viscosity of 1 cP or more, 200 cP or more, 400 cP or more, 600 cP or more, 800 cP or more, 1000 cP or more, 1200 cP or more, 1400 cP or more, 1600 cP or more, 1800 cP or more, 2000 cP or more, 2200 cP or more, or 2400 cP or more.

[0061] In addition, the resin for the corrosion-preventing layer may have a viscosity of 5000 cP or less, 4800 cP or less, 4600 cP or less, 4400 cP or less, 4200 cP or less, 4000 cP or less, 3800 cP or less, 3600 cP or less, 3400 cP or less, 3200 cP or less, 3000 cP or less, 2800 cP or less, or 2600 cP or less.

[0062] In relation to the above embodiment, with reference to FIG. 1 and / or FIG. 2, it is shown that a resin (4) for a corrosion-resistant layer is cured by ultraviolet rays (7) to form a corrosion-resistant layer (6).

[0063] In relation to the above embodiment, with reference to FIG. 2(B), the resin (4) for the corrosion-preventing layer described above is sprayed and applied onto a battery can (1), and with reference to FIG. 2(C), ultraviolet rays (7) are irradiated to form a cured form of the resin (4) for the corrosion-preventing layer, i.e., a corrosion-preventing layer (6). The spraying method is based on a conventional method.

[0064] The resin for the corrosion-preventing layer used in the above embodiment prevents corrosion by blocking corrosion factors, such as contact with air or moisture, to damaged areas of the battery can. A resin for the corrosion-preventing layer characterized by UV curability and low viscosity is used. The corrosion-preventing layer formed with such a resin can be formed with a uniform thickness, can prevent bubbles from forming in the corrosion-preventing layer, and can provide excellent physical properties in terms of heat resistance, heat conductivity, etc. Furthermore, the corrosion-preventing layer formed with the above-mentioned resin is not deformed by an activation process (typically, left for approximately 24 hours under high temperature and high humidity conditions (a temperature of about 65°C or higher, and a humidity of about 90% or higher)).

[0065] The method of applying the resin for the corrosion-preventive layer can be performed in a manner appropriate in the art. The spraying can be performed through equipment such as a nozzle (5), and the discharge volume and discharge pressure applied to the nozzle can be selected within an appropriate range in the art. The ultraviolet (7) irradiation can be performed by equipment such as a UV lamp (8), and the wavelength of light applied to the light source of the UV lamp can be selected within an appropriate range in the art.

[0066] The method for manufacturing a corrosion-preventing layer according to the above embodiment provides process simplicity by using one or more liquid materials that are UV-curable in the resin for the corrosion-preventing layer described above. In addition, since one or more liquid materials having a low viscosity of 1 cP or more and 5000 cP or less are used, the corrosion-preventing layer formed from the resin for the corrosion-preventing layer can be formed with a uniform thickness, prevent bubbles from forming in the corrosion-preventing layer, and provide excellent physical properties in terms of heat resistance and thermal conductivity. Furthermore, the corrosion-preventing layer formed by the above manufacturing method prevents corrosion of the battery can by blocking corrosion factors such as contact with air or moisture to the metal plating layer. In addition, the corrosion-preventing layer formed from the resin for the corrosion-preventing layer according to the above embodiment is not deformed by a subsequent activation process (typically, left for approximately 24 hours under high temperature and high humidity conditions (a temperature of about 65°C or higher and a humidity of about 90% or higher)).

[0067] In particular, it can resolve the problem of corrosion occurring when the coating layer formed by conventional inkjet printing methods peels off.

[0068] According to a further embodiment of the present invention, the resin for the corrosion-preventing layer further comprises a luminescent material, and

[0069] (C) A method for manufacturing a corrosion-preventing layer is provided, which further includes the step of checking the state of application of a resin for a corrosion-preventing layer on the battery can using ultraviolet light.

[0070] The manufacturing method according to the above embodiment checks the application state of the corrosion-preventing resin to the area where the outer surface of the battery can is damaged with a luminescent material in the corrosion-preventing resin, thereby enabling more efficient corrosion prevention.

[0071] If necessary, a breaking valve may be provided in the battery can to discharge internal gas to the outside when pressure rises due to gas present inside the cylindrical secondary battery. In this case, a step of forming a corrosion-preventing layer by bypassing the breaking valve may be further included.

[0072] In an additional embodiment, a method for manufacturing a corrosion-preventing layer is provided, wherein the resin for the corrosion-preventing layer comprises one or more selected from epoxy-based, acrylate-based, silicone-based, and urethane-acrylic-based resins.

[0073] In relation to the above embodiment, with reference to FIG. 2(B), a corrosion-preventing resin (4) comprising one or more selected from the above-described epoxy-based, acrylate-based, silicone-based, and urethane-acrylic-based resins is sprayed and applied onto a battery can (1), and with reference to FIG. 2(C), ultraviolet rays (7) are irradiated to form a cured form of the corrosion-preventing resin (4), i.e., a corrosion-preventing layer (6).

[0074] The method for manufacturing a corrosion-preventing layer according to the above embodiment includes one or more selected from epoxy-based, acrylate-based, silicone-based, and urethane-acrylic-based resins having UV curability and low viscosity characteristics among the resins for the corrosion-preventing layer described above. Therefore, the process for forming the corrosion-preventing layer is simple, the thickness of the corrosion-preventing layer can be formed uniformly, bubbles formed in the corrosion-preventing layer can be prevented, and excellent physical properties in terms of heat resistance and thermal conductivity can be provided.

[0075] According to a further embodiment of the present invention, a method for manufacturing a corrosion-preventing layer is provided, wherein the curing time of step (B) is 5 seconds or more and 30 seconds or less.

[0076] Preferably, the curing time may be 5 seconds or more, 10 seconds or more, or 15 seconds or more.

[0077] Preferably, the curing time may be 30 seconds or less, 25 seconds or less, or 20 seconds or less.

[0078] In relation to the above embodiment, referring to FIG. 2(B), the resin (4) for the corrosion-preventing layer described above is sprayed and applied onto a battery can (1). Also, referring to FIG. 2(C), the process of irradiating ultraviolet rays (7) for 5 seconds or more and 30 seconds or less to cure the resin (4) for the corrosion-preventing layer and form a corrosion-preventing layer (6) is illustrated.

[0079] The method for manufacturing a corrosion-preventive layer according to the above embodiment provides process speed due to a short curing time of 5 seconds or more and 30 seconds or less, and a secondary battery satisfying the above range can ensure safety.

[0080] According to an additional embodiment, the battery can provides a method for manufacturing a corrosion-resistant layer comprising iron.

[0081] According to an additional embodiment, a method for manufacturing a corrosion-resistant layer is provided in which the metal plating layer comprises nickel.

[0082] The manufacturing method according to the above embodiments can primarily prevent corrosion of the battery can by providing a metal plating layer (or nickel-containing layer). However, when the bottom surface of the battery can is welded from the outside, the metal plating layer may also melt, exposing the surface of the battery can. Nevertheless, in the above embodiment, after welding the battery can containing the metal plating layer, the exposure of the surface of the battery can can be prevented by placing a corrosion-preventing layer on the area damaged by the welding.

[0083] According to a further embodiment of the present invention, a method for manufacturing a corrosion-preventing layer is provided, wherein the thickness of the corrosion-preventing layer is greater than 1 μm and less than 10 μm.

[0084] Preferably, the thickness of the corrosion-preventing layer may be greater than 1 μm, greater than 2 μm, greater than 3 μm, greater than 4 μm, or greater than 5 μm.

[0085] Preferably, the thickness of the corrosion-preventing layer may be less than 10 μm, less than 9 μm, less than 8 μm, less than 7 μm, or less than 6 μm.

[0086] When the thickness range according to the above embodiment is satisfied, it enables optimization of the cell dimension range of the secondary battery.

[0087] According to a further embodiment of the present invention, a corrosion-resistant layer is provided according to a manufacturing method of any one of the embodiments.

[0088] In relation to the above embodiment, referring to FIG. 1 or FIG. 2, the corrosion-resistant layer (6) is formed by curing a corrosion-resistant resin provided on a welded portion (3) located on a metal plating layer (2) applied to a battery can (1) by ultraviolet light (7).

[0089] The corrosion-preventing layer according to the above embodiment prevents corrosion of the battery can by blocking corrosion factors, such as contact of air or moisture with the metal plating layer. Since the resin for the corrosion-preventing layer uses one or more liquid materials that are UV-curable and have low viscosity, the corrosion-preventing layer formed using this material has a uniform thickness, is almost free of bubbles, and can possess excellent physical properties in terms of heat resistance and heat transfer. In addition, the corrosion-preventing layer is not deformed by the activation process (typically, left for approximately 24 hours under high temperature and high humidity conditions (a temperature of about 65°C or higher, and a humidity of about 90% or higher)).

[0090] In addition, the above corrosion-preventing layer can also resolve the problem of corrosion occurring when the coating layer formed by the conventional inkjet printing method peels off.

[0091] According to one embodiment of the present invention, a jelly-roll type electrode assembly having a structure in which a first electrode, a second electrode, and a separator interposed between them are wound in one direction with respect to a winding axis;

[0092] A battery can accommodating the above electrode assembly and including a metal plating layer;

[0093] A connecting lead plate for joining the above-mentioned battery can and electrode assembly; and

[0094] A corrosion-resistant layer manufactured by any one of the methods for manufacturing a corrosion-resistant layer described above.

[0095] A cylindrical secondary battery comprising

[0096] Alternatively, according to one embodiment of the present invention, a jelly-roll type electrode assembly having a structure in which a first electrode, a second electrode, and a separator interposed between them are wound in one direction with respect to a winding axis;

[0097] A battery can accommodating the above electrode assembly and including a metal plating layer;

[0098] A connecting lead plate for joining the above-mentioned battery can and electrode assembly; and

[0099] A corrosion-preventing layer disposed at a damaged portion of the outer surface of the battery can at the weld formed by the melting of the connection lead plate on the outer bottom surface of the battery can and the battery can.

[0100] A cylindrical secondary battery comprising

[0101] In relation to the above embodiments, with reference to FIG. 1(C) or FIG. 2(C), an electrode assembly (not shown) having a structure in which a first electrode, a separator, and a second electrode are sequentially stacked and wound, and a corrosion-preventing layer (6) located on a weld (3) located on a metal plating layer (2) applied to the outer bottom surface (1) of a battery can are shown.

[0102] The secondary battery according to the above embodiment includes a corrosion-preventing layer that prevents corrosion of the battery can by blocking corrosive factors, such as contact of air or moisture with a metal plating layer, and includes a corrosion-preventing layer that has a uniform thickness, is almost free of bubbles, and possesses excellent physical properties in terms of heat resistance and thermal conductivity. In addition, it includes a corrosion-preventing layer that is not deformed by an activation process (typically, being left for approximately 24 hours under high temperature and high humidity conditions (a temperature of about 65°C or higher, and a humidity of about 90% or higher)). Accordingly, the cylindrical secondary battery including the corrosion-preventing layer has stability and / or safety. Furthermore, when including the corrosion-preventing layer, the defect rate of the cylindrical secondary battery can be minimized.

[0103] If necessary, a shut-off valve may be provided in the battery can to discharge internal gas to the outside when pressure rises due to gas present inside the cylindrical secondary battery. In this case, a corrosion-preventing layer may be formed by bypassing the shut-off valve.

[0104] According to an additional embodiment, the corrosion-resistant layer comprises a resin for a corrosion-resistant layer, and

[0105] The present invention provides a cylindrical secondary battery in which the resin for the corrosion-preventing layer is one or more selected from epoxy-based, acrylate-based, silicone-based, and urethane-acrylic-based resins.

[0106] In relation to the above embodiment, with reference to FIG. 2(B), a corrosion-preventing resin (4) comprising one or more selected from the above-described epoxy-based, acrylate-based, silicone-based, and urethane-acrylic-based resins is sprayed and applied onto a battery can (1).

[0107] The cylindrical cell according to the above embodiment includes one or more selected from epoxy-based, acrylate-based, silicone-based, and urethane-acrylic-based resins having UV curability and low viscosity characteristics as a resin for the corrosion-preventing layer, so the process for forming the corrosion-preventing layer is simple, the thickness of the corrosion-preventing layer can be formed uniformly, bubbles formed in the corrosion-preventing layer can be prevented, and excellent physical properties in terms of heat resistance, heat transfer, etc.

[0108] According to an additional embodiment, a cylindrical secondary battery is provided in which the resin for the corrosion-preventing layer further comprises a luminescent material.

[0109] The cylindrical secondary battery according to the above embodiment allows corrosion prevention to be achieved more efficiently by checking the application state of the corrosion-preventing resin on the damaged area of ​​the outer surface of the battery can with a luminescent material in the corrosion-preventing resin.

[0110] According to an additional embodiment, the battery can provides a cylindrical secondary battery containing iron.

[0111] According to an additional embodiment, the metal plating layer provides a cylindrical secondary battery containing nickel.

[0112] The cylindrical secondary battery according to the above embodiments can primarily prevent corrosion of the battery can containing iron by providing a metal plating layer (or including nickel). However, when the bottom surface of the battery can is welded from the outside, the metal plating layer may also melt, exposing the surface of the battery can. Nevertheless, in the above embodiment, after welding the battery can containing the metal plating layer, the exposure of the surface of the battery can can be prevented by placing a corrosion-preventing layer on the area damaged by the welding.

[0113] According to an additional embodiment, a cylindrical secondary battery is provided in which the thickness of the corrosion-resistant layer is greater than 1 μm and less than 10 μm.

[0114] Preferably, the thickness of the corrosion-preventing layer may be greater than 1 μm, greater than 2 μm, greater than 3 μm, greater than 4 μm, or greater than 5 μm.

[0115] Preferably, the thickness of the corrosion-preventing layer may be less than 10 μm, less than 9 μm, less than 8 μm, less than 7 μm, or less than 6 μm.

[0116] When the thickness range according to the above embodiment is satisfied, it enables optimization of the cell dimension range of the secondary battery.

[0117] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto and may be implemented with various modifications within the scope of the claims and the detailed description of the invention, and such modifications also fall within the scope of the invention. Explanation of the symbols

[0118] 1: Battery can 2: Metal plating layer 3: Welded part 4: Resin for anti-corrosion layer 5: Nozzle 6: Anti-corrosion layer 7: Ultraviolet rays 8: UV lamp

Claims

Claim 1 A method for manufacturing a corrosion-preventing layer for a cylindrical secondary battery comprising: a jelly-roll type electrode assembly having a structure in which a first electrode, a second electrode, and a separator interposed between them are wound in one direction with respect to a winding axis; a battery can that accommodates the electrode assembly and includes a metal plating layer; and a connection lead plate that joins the battery can and the electrode assembly, wherein the method comprises: (A) a step of applying a corrosion-preventing layer resin to a portion where the metal plating layer is damaged in a welded portion formed by melting the connection lead plate and the battery can when welding the outer bottom surface of the battery can; and (B) a step of curing the corrosion-preventing layer resin by ultraviolet rays to form a corrosion-preventing layer, wherein the corrosion-preventing layer resin comprises one or more liquid substances, wherein the one or more liquid substances are ultraviolet curable and have a viscosity of 1 cP or more and 5000 cP or less, and the thickness of the corrosion-preventing layer is greater than 1 μm and less than 10 μm. Claim 2 A method for manufacturing a corrosion-preventing layer according to claim 1, wherein the resin for the corrosion-preventing layer further comprises a luminescent material, (C) and further comprises the step of checking the coating state of the resin for the corrosion-preventing layer on the battery can using ultraviolet light. Claim 3 A method for manufacturing a corrosion-preventing layer according to claim 1, wherein the resin for the corrosion-preventing layer is one or more selected from epoxy-based, acrylate-based, silicone-based, and urethane-acrylic-based resins. Claim 4 A method for manufacturing a corrosion-preventive layer according to claim 1, wherein the curing time of step (B) is 5 seconds or more and 30 seconds or less. Claim 5 A method for manufacturing a corrosion-preventing layer according to claim 1, wherein the battery can comprises iron. Claim 6 A method for manufacturing a corrosion-resistant layer according to claim 1, wherein the metal plating layer comprises nickel. Claim 7 delete Claim 8 A jelly-roll type electrode assembly having a structure in which a first electrode, a second electrode, and a separator interposed between them are wound in one direction with respect to a winding axis; a battery can that accommodates the electrode assembly and includes a metal plating layer; a connecting lead plate that joins the battery can and the electrode assembly; and a corrosion-resistant layer manufactured by a method for manufacturing a corrosion-resistant layer according to any one of claims 1 to 6, wherein the thickness of the corrosion-resistant layer is greater than 1 μm and less than 10 μm. Claim 9 delete Claim 10 A cylindrical secondary battery according to claim 8, wherein the corrosion-resistant layer comprises a resin for a corrosion-resistant layer, and the resin for the corrosion-resistant layer is one or more selected from epoxy-based, acrylate-based, silicone-based, and urethane-acrylic-based resins. Claim 11 A cylindrical secondary battery according to claim 10, wherein the resin for the corrosion-preventing layer further comprises a luminescent material. Claim 12 In claim 8, the battery can is a cylindrical secondary battery comprising iron. Claim 13 A cylindrical secondary battery according to claim 8, wherein the metal plating layer comprises nickel. Claim 14 delete

Images