Method for manufacturing electrode for lithium secondary battery, electrode for lithium secondary battery manufactured thereby, lithium secondary battery comprising same, and transfer laminate for pre-lithiation

Abstract

The present invention relates to a method for manufacturing an electrode for a lithium secondary battery, an electrode for a lithium secondary battery manufactured thereby, a lithium secondary battery comprising same, and a transfer laminate for pre-lithiation, the method comprising a step of laminating a transfer laminate comprising a lithium metal layer and a carrier film, on one side of an electrode active material layer provided on at least one side of an electrode current collector layer, wherein at least one side of the carrier film has a maximum height roughness (Sz) of 17 μm or less in the vertical direction and an arithmetic mean roughness (Sa) of 3 μm or less.

Description

Method for manufacturing an electrode for a lithium secondary battery, an electrode for a lithium secondary battery manufactured therefrom, a lithium secondary battery including the same, and a transfer laminate for pre-lithiation

[0001] The present invention relates to a method for manufacturing an electrode for a lithium secondary battery, an electrode for a lithium secondary battery manufactured therefrom, a lithium secondary battery including the same, and a transfer laminate for pre-lithiation.

[0002] The present invention claims the benefit of the filing dates of Korean Patent Application No. 10-2024-0129762 filed with the Korean Intellectual Property Office on September 25, 2024 and Korean Patent Application No. 10-2025-0136087 filed with the Korean Intellectual Property Office on September 22, 2025, the entire contents of which are incorporated herein.

[0003] Due to the rapid increase in the use of fossil fuels, there is a growing demand for alternative or clean energy. As part of this effort, the fields of power generation and energy storage utilizing electrochemical reactions are the most actively researched.

[0004] Currently, a representative example of an electrochemical device utilizing such electrochemical energy is the secondary battery, and its scope of application is steadily expanding.

[0005] With the increasing technological development and demand for mobile devices, the demand for secondary batteries as an energy source is rapidly rising. Among these secondary batteries, lithium-ion batteries, which possess high energy density and voltage, long cycle life, and low self-discharge rates, have been commercialized and are widely used. Furthermore, active research is being conducted on methods to manufacture high-density electrodes with higher energy density per unit volume for use in such high-capacity lithium-ion batteries.

[0006] Generally, a secondary battery includes a positive electrode, a negative electrode, a separator interposed between the positive and negative electrodes, and an electrolyte. Additionally, electrodes such as the positive and negative electrodes may have an electrode active material layer provided on a current collector.

[0007] Meanwhile, lithium loss in rechargeable lithium batteries begins from the first charge after manufacturing. During subsequent charge-discharge cycles and high-temperature storage periods, lithium loss occurs continuously, albeit in small amounts, leading to battery degradation. To compensate for this lithium loss, the process of adding additional lithium to the battery before operation is called pre-lithiation.

[0008] However, residual lithium that is not used in the pre-lithiation reaction may remain on the surface of the electrode, which may cause problems such as lithium precipitation or lithium loss during battery operation.

[0009] [Prior Art Literature]

[0010] [Patent Literature]

[0011] (Patent Document 1) Japanese Published Patent Application No. 2009-080971

[0012] The present invention aims to provide a method for manufacturing an electrode for a lithium secondary battery capable of reducing residual lithium formed on the electrode surface due to pre-lithiation, an electrode for a lithium secondary battery manufactured therefrom, a lithium secondary battery including the same, and a transfer laminate for pre-lithiation.

[0013] One embodiment of the present specification includes the step of laminating a transfer laminate comprising a lithium metal layer and a carrier film on one surface of an electrode active material layer provided on at least one surface of an electrode current collector layer, and

[0014] A method for manufacturing an electrode for a lithium secondary battery is provided, wherein at least one surface of the carrier film has a maximum height roughness (Sz) in the vertical direction of 17 μm or less and an arithmetic mean roughness (Sa) of 3 μm or less.

[0015] One embodiment of the present specification includes an electrode current collector layer; and an electrode active material layer, and

[0016] As an electrode for a lithium secondary battery manufactured by the above-described manufacturing method,

[0017] The present invention provides a lithium secondary battery electrode in which the area of ​​residual lithium occupying the surface of the lithium secondary battery electrode is 6% or less of the total surface area of ​​the lithium secondary battery electrode.

[0018] Another embodiment of the present specification is the aforementioned electrode for a lithium secondary battery;

[0019] Separator; and

[0020] A lithium secondary battery containing an electrolyte is provided.

[0021] One embodiment of the present specification provides a battery module comprising the aforementioned lithium secondary battery.

[0022] Another embodiment of the present specification provides a battery pack comprising the aforementioned battery module.

[0023] One embodiment of the present specification provides a battery pack comprising the aforementioned lithium secondary battery.

[0024] Finally, one embodiment of the present specification comprises a lithium metal layer; and a carrier film, and

[0025] The carrier film provides a transfer laminate for pre-lithiation in which the maximum height roughness (Sz) in the vertical direction of the surface facing the lithium metal layer is 17 μm or less, and the arithmetic mean roughness (Sa) is 3 μm or less.

[0026] A method for manufacturing an electrode for a lithium secondary battery according to one embodiment described in this specification can manufacture an electrode for a lithium secondary battery and a lithium secondary battery including the same, in which lithium precipitation or lithium loss that may occur during battery operation is suppressed by reducing the amount of residual lithium remaining on the electrode surface that is not used in the pre-lithiation reaction.

[0027] When pre-lithiation is performed using a transfer laminate for pre-lithiation according to one embodiment described in this specification, residual lithium formed on the surface of the pre-lithiated electrode is reduced, thereby obtaining an electrode for a lithium secondary battery in which lithium precipitation or lithium loss that may occur during battery operation is suppressed.

[0028] FIG. 1 is a flowchart illustrating a method for manufacturing an electrode for a lithium secondary battery according to one embodiment of the present invention.

[0029] FIG. 2 is a figure showing a transfer laminate and an electrode for a lithium secondary battery according to one embodiment of the present invention.

[0030] FIG. 3 is a figure showing the surface of an electrode for a lithium secondary battery that has completed pre-lithiation according to an embodiment and a comparative example of the present invention.

[0031] FIG. 4 is a figure showing the surface of an electrode for a lithium secondary battery that has completed pre-lithiation according to an embodiment and a comparative example of the present invention, observed at a microscope magnification of ×200.

[0032] FIG. 5 is a diagram showing the stacked structure of a lithium secondary battery manufactured according to one embodiment of the present invention.

[0033] Figure 6 is a figure showing the surface roughness of a carrier film used in the manufacture of electrodes for lithium secondary batteries of the embodiments and comparative examples of the present invention.

[0034] Before describing the present invention, some terms are defined first.

[0035] In this specification, when a part is described as "comprising" a certain component, it means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0036] In this specification, terms such as “comprising,” “comprising,” or “having” are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0037] In this specification, 'p to q' means a range of 'p or more and q or less'.

[0038] In this specification, when a part such as a layer is described as being "above" or "on" another part, this includes not only the case where it is "immediately above" another part, but also the case where there is another part in between. Conversely, when a part is described as being "immediately above" another part, it means that there is no other part in between. Furthermore, being described as being "above" or "on" a reference part means being located above or below the reference part, and does not necessarily mean being located "above" or "on" in a direction opposite to gravity.

[0039] The singular expressions of terms used in this specification include the plural expressions unless the context clearly indicates otherwise.

[0040] Hereinafter, the present invention will be described in more detail to aid in understanding the invention. The present invention may be embodied in various different forms and is not limited to the embodiments described herein. In this case, terms or words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0041] A method for manufacturing an electrode for a lithium secondary battery according to one embodiment of the present specification includes the step of laminating a transfer laminate comprising a lithium metal layer and a carrier film on one surface of an electrode active material layer provided on at least one surface of an electrode current collector layer, wherein at least one surface of the carrier film has a maximum height roughness (Sz) in the vertical direction of 17 μm or less and an arithmetic mean roughness (Sa) of 3 μm or less.

[0042] In one embodiment of the present specification, the step of laminating the transfer laminate on at least one surface of the electrode active material layer is to laminate the transfer laminate so that the lithium metal layer contacts at least one surface of the electrode active material layer, and is a step for pre-lithiating the electrode active material layer with lithium metal.

[0043] A method for manufacturing an electrode for a lithium secondary battery according to one embodiment of the present specification can compensate for irreversible capacity by preventing lithium loss by pre-lithiating at least one surface of the electrode active material layer, and thereby improve battery capacity or cycle performance.

[0044] According to one embodiment of the present specification, the pre-lithiation may be any one of pre-lithiation by an electrochemical method, pre-lithiation using SLMP, and pre-lithiation by a direct contact method, and specifically, it may be pre-lithiation by a direct contact method.

[0045] The above-mentioned pre-lithiation by direct contact method can be divided into a dry method in which a lithium metal layer is transferred by contacting and pressurizing the electrode active material layer, and a wet method in which a lithium metal layer is contacted by contacting the electrode active material layer wetted in the electrolyte. In particular, when performed by the transfer method through direct contact of the lithium metal layer, it can be applied to a roll-to-roll process which is useful for mass-producing electrodes compared to other methods, so there is an advantage that the process speed is fast and effective for mass production.

[0046] However, if the transfer method is performed by direct contact with the lithium metal layer, residual lithium that has not undergone the pre-lithiation reaction may form on the electrode surface after the pre-lithiation is completed. This residual lithium can act as a point where lithium can be precipitated during subsequent battery operation, and if the residual lithium is excessive, it may result in a loss of the lithium added.

[0047] Accordingly, the present invention is characterized by using a carrier film with low surface roughness to reduce the height difference of the lithium metal layer formed on one side of the carrier film, thereby allowing the entire surface area of ​​the lithium metal layer to uniformly contact the electrode active material layer and enabling a pre-lithiation reaction to occur, which can reduce the amount of lithium remaining on the electrode surface.

[0048] That is, the method for manufacturing an electrode for a lithium secondary battery according to one embodiment of the present specification is characterized by using a transfer laminate comprising a lithium metal layer on at least one surface of an electrode active material layer during pre-lithiation, and a carrier film satisfying the range of a maximum height roughness (Sz) in the vertical direction of at least one surface being 17 μm or less and an arithmetic mean roughness (Sa) being 3 μm or less, thereby reducing the amount of residual lithium generated on the electrode surface after lamination and thereby suppressing lithium deposition and loss of the added lithium.

[0049] In one embodiment of the present specification, at least one surface of the carrier film may have a maximum height roughness (Sz) in the vertical direction of 17 μm or less and an arithmetic mean roughness (Sa) of 3 μm or less.

[0050] In one embodiment of the present specification, the maximum height roughness (Sz) and arithmetic mean roughness (Sa) in the vertical direction of the carrier film can be calculated by specifying an area after taking an image with a microscope (KEYENCE VHX-7000N) at a magnification of ×200.

[0051] In addition, the maximum height roughness (Sz) and the arithmetic mean roughness (Sa) of the carrier film are roughnesses before a lithium metal layer is provided on one side of the carrier film, but the roughness range may remain the same even after the lithium metal layer is provided.

[0052] In one embodiment of the present specification, the maximum height roughness (Sz) in the vertical direction of the surface of the carrier film facing the lithium metal layer may be 17 μm or less, and the arithmetic mean roughness (Sa) may be 3 μm or less.

[0053] In one embodiment of the present specification, the maximum height roughness (Sz) in the vertical direction of the surface of the carrier film facing the lithium metal layer may be 17 μm or less, and the arithmetic mean roughness (Sa) may be 3 μm or less. Specifically, the maximum height roughness (Sz) may be 15 μm or less, and the arithmetic mean roughness (Sa) may be 2 μm or less. More specifically, the maximum height roughness (Sz) may be 10 μm or less, and the arithmetic mean roughness (Sa) may be 1 μm or less.

[0054] In one embodiment of the present specification, the maximum height roughness (Sz) in the vertical direction of the surface of the carrier film facing the lithium metal layer may be 0.5 μm or more and the arithmetic mean roughness (Sa) may be 0.05 μm or more, specifically the maximum height roughness (Sz) may be 1 μm or more and the arithmetic mean roughness (Sa) may be 0.1 μm or more, and more specifically the maximum height roughness (Sz) may be 2 μm or more and the arithmetic mean roughness (Sa) may be 0.2 μm or more.

[0055] That is, in one embodiment of the present specification, the maximum height roughness (Sz) in the vertical direction of the surface of the carrier film facing the lithium metal layer may be 0.5 μm or more and 17 μm or less, and the arithmetic mean roughness (Sa) may be 0.05 μm or more and 3 μm or less. Specifically, the maximum height roughness (Sz) may be 1 μm or more and 15 μm or less, and the arithmetic mean roughness (Sa) may be 0.1 μm or more and 2 μm or less. More specifically, the maximum height roughness (Sz) may be 2 μm or more and 10 μm or less, and the arithmetic mean roughness (Sa) may be 0.2 μm or more and 1 μm or less.

[0056] In the case where the surface roughness of the surface of the carrier film facing the lithium metal layer according to one embodiment of the present specification satisfies the above range, the lithium metal layer is evenly distributed on the carrier film during the process of manufacturing a transfer laminate, thereby reducing the height difference of the lithium metal layer. As a result, when pressure is applied during lamination, the entire surface area of ​​the lithium metal layer can uniformly come into contact with the electrode active material layer, so that it is not excessively pre-lithiated in one part but is evenly pre-lithiated, thereby minimizing residual lithium on the electrode surface.

[0057] In one embodiment of the present specification, the maximum height roughness (Sz) in the vertical direction of the back surface of the carrier film facing the lithium metal layer may be 17 μm or less, and the arithmetic mean roughness (Sa) may be 3 μm or less.

[0058] In one embodiment of the present specification, the maximum height roughness (Sz) in the vertical direction of the back surface of the carrier film facing the lithium metal layer may be 17 μm or less, and the arithmetic mean roughness (Sa) may be 3 μm or less. Specifically, the maximum height roughness (Sz) may be 15 μm or less, and the arithmetic mean roughness (Sa) may be 2 μm or less. More specifically, the maximum height roughness (Sz) may be 10 μm or less, and the arithmetic mean roughness (Sa) may be 1 μm or less.

[0059] In one embodiment of the present specification, the maximum height roughness (Sz) in the vertical direction of the back surface of the carrier film facing the lithium metal layer may be 0.5 μm or more, and the arithmetic mean roughness (Sa) may be 0.05 μm or more. Specifically, the maximum height roughness (Sz) may be 1 μm or more, and the arithmetic mean roughness (Sa) may be 0.1 μm or more. More specifically, the maximum height roughness (Sz) may be 2 μm or more, and the arithmetic mean roughness (Sa) may be 0.2 μm or more.

[0060] That is, in one embodiment of the present specification, the maximum height roughness (Sz) in the vertical direction of the back surface of the carrier film facing the lithium metal layer may be 0.5 μm or more and 17 μm or less, and the arithmetic mean roughness (Sa) may be 0.05 μm or more and 3 μm or less. Specifically, the maximum height roughness (Sz) may be 1 μm or more and 15 μm or less, and the arithmetic mean roughness (Sa) may be 0.1 μm or more and 2 μm or less. More specifically, the maximum height roughness (Sz) may be 2 μm or more and 10 μm or less, and the arithmetic mean roughness (Sa) may be 0.2 μm or more and 1 μm or less.

[0061] The transfer laminate comprising the lithium metal layer and the carrier film may exist in a wound state before contacting one surface of the electrode active material layer. At this time, the back surface of the carrier film, on which the lithium metal layer is not formed, comes into contact with the lithium metal layer. Since the lithium metal layer is a soft metal, a certain pressure is applied during winding. Consequently, it is affected by factors such as being pressed by the surface roughness of the back surface of the carrier film, which causes a height difference in the lithium metal layer, potentially resulting in residual lithium during pre-lithiation. Therefore, the present invention is characterized by minimizing residual lithium on the electrode surface by reducing the surface roughness of the back surface of the carrier film. That is, if the surface roughness of the back surface of the carrier film facing the lithium metal layer, according to one embodiment of the present specification, satisfies the above range, the generation of residual lithium on the electrode surface can be minimized.

[0062] In one embodiment of the present specification, the maximum height roughness (Sz) of both sides of the carrier film may be 17 μm or less and the arithmetic mean roughness (Sa) may be 3 μm or less, specifically the maximum height roughness (Sz) may be 15 μm or less and the arithmetic mean roughness (Sa) may be 2 μm or less, more specifically the maximum height roughness (Sz) may be 10 μm or less and the arithmetic mean roughness (Sa) may be 1 μm or less, and when the surface roughness of both sides satisfies the above range, the aforementioned effect can be maximized.

[0063] A method for manufacturing an electrode for a lithium secondary battery according to one embodiment of the present specification may further include the step of preparing a transfer laminate comprising a lithium metal layer and a carrier film before the lamination step.

[0064] In one embodiment of the present specification, the step of preparing a transfer laminate comprising the lithium metal layer and the carrier film may be performed by any one of the methods of depositing, rolling, and melting the lithium metal layer on one surface of the carrier film. Specifically, in one embodiment of the present specification, the step of preparing a transfer laminate comprising the lithium metal layer and the carrier film may be performed by any one of the methods of depositing and rolling the lithium metal layer on one surface of the carrier film, and more specifically, the step of preparing a transfer laminate comprising the lithium metal layer and the carrier film may be performed by the method of depositing the lithium metal layer on one surface of the carrier film.

[0065] That is, in one embodiment of the present specification, the transfer laminate may be provided on one surface of the carrier film by any one of the methods of depositing, rolling, and melting the lithium metal layer, specifically by either the method of deposition or rolling, and more specifically by the method of deposition.

[0066] In one embodiment of the present specification, the method for depositing the lithium metal layer on one surface of the carrier film may be selected from Physical Vapor Deposition (PDV) and Chemical Vapor Deposition (CVD). Among the Physical Vapor Deposition methods, Thermal Evaporation may be primarily used, but is not limited thereto, and various deposition methods used in the industry may be used.

[0067] In one embodiment of the present specification, the method of rolling the lithium metal layer onto one surface of the carrier film may involve contacting a lithium foil onto one surface of the carrier film and then forming a lithium thin film with a thickness of 10 μm or less through a continuous rolling process.

[0068] In one embodiment of the present specification, the method of melting the lithium metal layer on one surface of the carrier film may be to melt a lithium metal having a low melting point of 180.5°C and then coat it onto the carrier film using a doctor blade or the like.

[0069] In one embodiment of the present specification, the transfer laminate comprises a lithium metal layer. The lithium metal layer is a layer comprising lithium metal for pre-lithiating at least one surface of the electrode active material layer, and may use a commonly used Li metal foil, but is not limited thereto.

[0070] In one embodiment of the present specification, the thickness of the lithium metal layer may be 10 μm or less, specifically 8 μm or less, more specifically 6.5 μm or less, and 0.1 μm or more, specifically 0.5 μm or more, more specifically 1 μm or more.

[0071] In one embodiment of the present specification, the thickness of the lithium metal layer may be 0.1 μm or more and 10 μm or less, specifically 0.5 μm or more and 8 μm or less, and more specifically 1 μm or more and 6.5 μm or less.

[0072] In the case where the thickness of the lithium metal layer according to one embodiment of the present specification satisfies the above range, the irreversible capacity during charging and discharging of the lithium secondary battery can be sufficiently compensated.

[0073] In one embodiment of the present specification, the transfer laminate comprises the aforementioned carrier film.

[0074] Specifically, according to one embodiment of the present specification, the transfer laminate may have a lithium metal layer and a carrier film sequentially laminated.

[0075] In one embodiment of the present specification, the carrier film is an essential component for supporting a lithium metal layer during the process of preparing a transfer laminate, and can be used without limitation as long as it has the characteristics of being able to withstand process conditions such as a high temperature during the step of depositing the lithium metal layer and preventing the problem of reverse delamination where the lithium metal layer is transferred onto the carrier film during the process of laminating the lithium metal layer.

[0076] In one embodiment of the present specification, the carrier film may comprise one or more selected from the group consisting of polyethylene terephthalate (PET), polyimide (PI), poly(methylmethacrylate), PMMA, polypropylene, polyethylene, and polycarbonate; specifically, the carrier film may comprise one or more selected from the group consisting of polyethylene terephthalate (PET), polyimide (PI), and polyethylene; more specifically, the carrier film may comprise polyethylene terephthalate (PET).

[0077] In one embodiment of the present specification, the carrier film may reduce the formation of unreacted residual lithium on the surface of the pre-lithiated electrode by having at least one surface having the surface roughness described above.

[0078] In one embodiment of the present specification, the thickness of the carrier film may be 1 μm or more and 300 μm or less, specifically 5 μm or more and 200 μm or less, and more specifically 10 μm or more and 100 μm or less.

[0079] As the thickness of the carrier film satisfies the above range, the transfer of lithium metal to the electrode active material layer can occur efficiently, and it has the characteristic of preventing reverse transfer.

[0080] In one embodiment of the present specification, the transfer laminate may further include a release layer between the lithium metal layer and the carrier film.

[0081] That is, in one embodiment of the present specification, the transfer laminate may further include a release layer, and in this case, the transfer laminate may be formed by sequentially laminating a lithium metal layer, a release layer, and a carrier film.

[0082] In one embodiment of the present specification, the release layer may be one or more selected from the group consisting of polycarbonate (PC), polydimethylsiloxane (PDMS), polymethylhydrosiloxane (PMHS), polyimide (PI), and polymethylmethacrylate (PMMA); specifically, the release layer may be one or more selected from the group consisting of polycarbonate (PC), polydimethylsiloxane (PDMS), and polymethylmethacrylate (PMMA); more specifically, the release layer may be polymethylmethacrylate (PMMA).

[0083] In one embodiment of the present specification, the thickness of the release layer may be 0.1 μm or more and 5 μm or less, specifically 0.2 μm or more and 3 μm or less, and more specifically 0.5 μm or more and 1 μm or less.

[0084] In one embodiment of the present specification, when the thickness of the release layer satisfies the above range, sufficient release force can be secured, and the release layer located on the surface after lamination of the lithium metal layer does not perform the role of blocking heat release, so the formation of byproducts may not be accelerated.

[0085] In one embodiment of the present specification, the release layer may be formed by a coating method, for example, the coating method may be selected from the group consisting of dip coating, spray coating, spin coating, die coating, gravure coating, micro-gravure coating, comma coating, and roll coating, but is not limited thereto, and various coating methods that can be used in the art to form a coating layer may be used.

[0086] In one embodiment of the present specification, the step of laminating the transfer laminate on one surface of the electrode active material layer comprises: the step of positioning the transfer laminate so that the lithium metal layer contacts one surface of the electrode active material layer; and the step of pressing the electrode active material layer and the transfer laminate together.

[0087] A method for manufacturing an electrode for a lithium secondary battery according to one embodiment of the present specification has the effect of enabling more active pre-lithiation by transfer to the electrode active material layer through the pressurizing step, and forming a thin electrode thickness despite high energy density.

[0088] In one embodiment of the present specification, the pressing step may be performed through a roll pressing process after positioning the transfer laminate so that the lithium metal layer contacts at least one surface of the electrode active material layer. That is, the step of pressing after positioning the transfer laminate so that the lithium metal layer contacts at least one surface of the electrode active material layer is a step of causing the prelithiation reaction between the electrode active material layer and the lithium metal layer to occur actively by applying a load through a roller. Since the load is applied in a linear manner as it passes through the roller, the unit is kgf.

[0089] In one embodiment of the present specification, the pressing step may be to pressurize with a load of 600 kgf or less.

[0090] Specifically, in one embodiment of the present specification, the pressing step may be a pressing with a load of 600 kgf or less, 500 kgf or less, 450 kgf or less, or 400 kgf or less, or a pressing with a load of 50 kgf or more, 60 kgf or more, 80 kgf or more, 100 kgf or more, 200 kgf or more, or more than 200 kgf.

[0091] In one embodiment of the present specification, the pressing step may be a pressing with a load of 50 kgf or more and 600 kgf or less, specifically a pressing with a load of 50 kgf or more and 500 kgf or less, and more specifically a pressing with a load of 50 kgf or more and 400 kgf or less, 60 kgf or more and 400 kgf or less, 100 kgf or more and 400 kgf or less, or a pressing with a load of more than 200 kgf and 400 kgf or less.

[0092] In one embodiment of the present specification, when pressure is applied with a load satisfying the above range, pre-lithiation due to transfer can proceed more actively, and simultaneously, since pre-lithiation proceeds to an appropriate range, residual lithium on the electrode surface can be minimized and the loss of the added lithium can be minimized. In addition, the thickness of the electrode can be formed thinly despite the high energy density.

[0093] That is, the lamination step according to one embodiment of the present specification may be to position the transfer laminate so that the lithium metal layer contacts one or both sides of the electrode active material layer, and then apply a load within the range and perform the transfer through a roll pressing process.

[0094] A method for manufacturing an electrode for a lithium secondary battery according to one embodiment of the present specification may further include the step of removing the carrier film.

[0095] In one embodiment of the present specification, the pre-lithiation may be such that the pre-lithiation reaction between the electrode active material layer and the lithium metal layer begins from the point in time when the lithium metal layer contacts at least one surface of the electrode active material layer, may begin within a few seconds to minutes from the point in time when the lithium metal layer contacts, or may begin from the point in time when the carrier film begins to be removed.

[0096] In one embodiment of the present specification, the pre-lithiation reaction may be terminated within a few days from the time when the lithium metal layer contacts at least one surface of the electrode active material layer, may be terminated within 24 hours, or may be terminated within minutes to seconds.

[0097] In one embodiment of the present specification, whether the pre-lithiation reaction is completed can be determined by visually observing the color change of the electrode surface. Specifically, the surface immediately after lamination with the transfer laminate is silver, such as lithium metal, but when the pre-lithiation reaction is completed, the pre-lithiated negative electrode surface takes on the color of the electrode or the color of the polymer of the release layer.

[0098] FIG. 1 is a flowchart illustrating a method for manufacturing an electrode for a lithium secondary battery according to one embodiment of the present specification. Specifically, FIG. 1(a) illustrates a method for manufacturing an electrode for a lithium secondary battery comprising the step (S1) of laminating a transfer laminate on one surface of an electrode active material layer provided on at least one surface of an electrode current collector layer, wherein the transfer laminate may include a lithium metal layer and a carrier film.

[0099] FIG. 1(b) illustrates a method for manufacturing an electrode for a lithium secondary battery, comprising the steps of: preparing a transfer laminate including a lithium metal layer and a carrier film (S1-1); positioning the transfer laminate so that the lithium metal layer contacts at least one surface of the electrode active material layer (S1-2); and pressing the electrode active material layer and the transfer laminate together (S1-3).

[0100] At this time, the step (not shown) of providing an electrode active material layer on at least one surface of an electrode current collector layer according to one embodiment of the present specification may be performed before step S1-1, may be performed simultaneously with S1-1, or may be performed between steps S1-1 and S1-2, but there are no limitations thereon.

[0101] FIG. 2 is a figure showing a transfer laminate (600) and an electrode (300) for a lithium secondary battery. Referring to FIG. 2, a transfer laminate (600) including a lithium metal layer (400) formed on one surface of a carrier film (500) can be seen first, and the surface roughness of the carrier film (500) is omitted from the illustration.

[0102] Additionally, referring to FIG. 2, the above-mentioned transfer laminate (600) can be laminated so that a lithium metal layer (400) contacts one side of the electrode active material layer (60), and then the carrier film (500) is removed to reveal the electrode (300) for a lithium secondary battery. At this time, the electrode active material layer (60) in FIG. 2 is specifically provided with the electrode active material layer (60) on both sides of the electrode current collector layer (not shown), but the illustration of the electrode current collector layer has been omitted for brevity. That is, the electrode for a lithium secondary battery in FIG. 2 shows a stacked structure in the order of lithium metal layer (400) / electrode active material layer (60) / electrode current collector layer (not shown) / electrode active material layer (60) / lithium metal layer (400).

[0103] At this time, at the boundary between the lithium metal layer (400) and the electrode active material layer (60) located on both sides of the lithium secondary battery electrode (300) of FIG. 2, pre-lithiation may be in progress or the pre-lithiation reaction may be completed. Depending on the degree of progress of the pre-lithiation reaction, the thickness of the lithium metal layer (400) of the transfer laminate (600) and the lithium metal layer (400) of the lithium secondary battery electrode (300) may be the same or different from each other.

[0104] A transfer laminate for pre-lithiation according to another embodiment of the present specification comprises a lithium metal layer; and a carrier film, wherein the carrier film may have a maximum height roughness (Sz) in the vertical direction of the surface facing the lithium metal layer of 17 μm or less and an arithmetic mean roughness (Sa) of 3 μm or less.

[0105] In another embodiment of this specification, the transfer laminate for pre-lithiation refers to the same as the transfer laminate in the method for manufacturing an electrode for a lithium secondary battery described above. That is, the contents regarding the lithium metal layer and carrier film described above, the surface roughness of the carrier film, the method for manufacturing the transfer laminate, and the method for laminating on at least one surface of the electrode active material layer can all be applied in the same way.

[0106] A method for manufacturing an electrode for a lithium secondary battery according to one embodiment of the present specification may further include the step of providing an electrode active material layer on at least one surface of an electrode current collector layer, and the step of providing the electrode active material layer may include the step of preparing an electrode slurry; and the step of applying and drying the electrode slurry on at least one surface of an electrode current collector layer.

[0107] In one embodiment of the present specification, the electrode slurry may include an electrode active material layer composition; and a slurry solvent.

[0108] In one embodiment of the present specification, the solid content of the electrode slurry may satisfy a range of 5% or more and 60% or less, specifically 7% or more and 50% or less, and more specifically 10% or more and 40% or less.

[0109] The solid content of the electrode slurry may refer to the content of the electrode active material layer composition included in the electrode slurry, and may refer to the content of the electrode active material layer composition based on 100 parts by weight of the total electrode slurry.

[0110] When the solid content of the electrode slurry satisfies the above range, the viscosity is suitable when forming the electrode active material layer, thereby minimizing particle aggregation of the electrode active material layer composition and enabling the electrode active material layer to be formed efficiently.

[0111] In one embodiment of the present specification, the slurry solvent is not limited thereto as long as it can dissolve the electrode active material layer composition, and for example, the slurry solvent may be water (e.g., distilled water) or NMP.

[0112] In one embodiment of the present specification, the electrode may be a negative electrode or a positive electrode.

[0113] That is, in one embodiment of the present specification, the step of providing an electrode active material layer on at least one surface of the electrode current collector layer may be a step of providing a negative active material layer on at least one surface of the negative current collector layer, or a step of providing a positive active material layer on at least one surface of the positive current collector layer.

[0114] Hereinafter, the step of providing a negative electrode active material layer is described first, but the same method may be applied to the step of providing a positive electrode active material layer, and the following description may be applied to each component of the positive electrode active material layer (positive electrode active material, positive electrode conductive material, positive electrode binder, etc.).

[0115] A cathode according to one embodiment of the present specification can be formed by applying and drying the cathode slurry on a cathode current collector layer, and the slurry solvent in the cathode slurry can be dried through the drying step.

[0116] In one embodiment of the present specification, the negative electrode active material layer composition may comprise one or more selected from the group consisting of a negative electrode active material; a negative electrode conductive material; and a negative electrode binder, and specifically, the negative electrode active material may comprise a carbon-based active material and a silicon-based active material.

[0117] That is, according to one embodiment of the present specification, the negative electrode active material layer may include a carbon-based active material and a silicon-based active material as negative electrode active materials.

[0118] According to one embodiment of the present specification, the negative electrode active material layer comprises a carbon-based active material and a silicon-based active material as negative electrode active materials, and the silicon-based active material may comprise one or more selected from the group consisting of Si, silicon oxide, Si / C and Si alloy.

[0119] Specifically, in one embodiment of the present specification, the silicon-based active material may comprise one or more selected from the group consisting of Si and silicon oxide, and more specifically, the silicon-based active material may comprise Si.

[0120] In one embodiment of the present specification, the carbon-based active material may comprise one or more selected from the group consisting of graphite such as natural graphite or artificial graphite, carbon fiber, non-graphitizable carbon, carbon black, carbon nanotubes, fullerene, and activated carbon, and specifically, may comprise one or more selected from the group consisting of natural graphite and artificial graphite.

[0121] When the above-described carbon-based active material is used as a negative electrode active material according to one embodiment of the present specification, reversible intercalation and extraction of lithium ions are possible, and structural and electrical properties can be maintained. Among these, the graphite-based active material can guarantee the lifespan characteristics of a lithium secondary battery due to its excellent reversibility. Since the discharge voltage of the graphite-based active material is low at -0.2V compared to lithium, a battery using the graphite-based active material can exhibit a high discharge voltage of 3.6V, thereby providing many advantages in terms of energy density of the lithium secondary battery.

[0122] In one embodiment of the present specification, when artificial graphite is used as the carbon-based active material, the degree of orientation during electrode rolling is relatively low, so the lithium ion entry and exit characteristics are good, resulting in excellent rapid charging performance of the battery, and the degree of expansion due to charging and discharging is low, so the lifespan characteristics can be excellent.

[0123] In one embodiment of the present specification, when natural graphite is used as a carbon-based active material, the output and capacity of the lithium secondary battery are improved, and since the adhesive strength is excellent, the amount of binder used can be reduced and a high-capacity, high-density negative electrode can be realized.

[0124] The above natural graphite may generally exist as plate-shaped aggregates prior to processing, and the plate-shaped particles may be manufactured into a spherical shape with a smooth surface through post-processing such as particle grinding and reassembly processes in order to be used as an active material for manufacturing electrodes.

[0125] In one embodiment of the present specification, the negative electrode active material layer comprises a carbon-based active material and a silicon-based active material as negative electrode active materials, wherein the carbon-based active material comprises one or more selected from the group consisting of natural graphite and artificial graphite, and the silicon-based active material may comprise Si.

[0126] In one embodiment of the present specification, the negative electrode active material may include the carbon-based active material and the silicon-based active material in a weight ratio of 90:10 to 40:60, specifically in a weight ratio of 80:20 to 50:50, and more specifically in a weight ratio of 70:30 to 60:40.

[0127] In one embodiment of the present specification, the negative electrode active material may be included in an amount of 60 parts by weight or more and 99 parts by weight or less based on 100 parts by weight of the negative electrode active material layer, specifically 70 parts by weight or more and 95 parts by weight or less, and more specifically 80 parts by weight or more and 90 parts by weight or less.

[0128] In one embodiment of the present specification, the cathode conductive material is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, ketjen black, channel black, Farnes black, lamp black, thermal black; conductive fibers such as carbon fibers or metal fibers; conductive tubes such as carbon nanotubes; metal powders such as fluorocarbon, aluminum, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive materials such as polyphenylene derivatives may be used.

[0129] In one embodiment of the present specification, the cathode conductive material may be a conductive tube such as a single-walled carbon nanotube (SWCNT) or a multi-walled carbon nanotube (MWCNT), and more specifically, a single-walled carbon nanotube (SWCNT) may be used.

[0130] In one embodiment of the present invention, the content of the cathode conductive material in the cathode active material layer may be 0.01 to 30 parts by weight, specifically 0.03 to 25 parts by weight, and more specifically 0.1 to 10 parts by weight, relative to 100 parts by weight of the cathode active material layer.

[0131] In one embodiment of the present specification, the cathode binder may serve to improve adhesion between cathode active material particles and adhesion between the cathode active material particles and the cathode current collector. The above-mentioned cathode binder may include those known in the art, and non-limiting examples may include at least one selected from the group consisting of polyvinylidenefluoride-polyhexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidenefluoride, polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, polyhydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluororubber, polyacrylic acid, and materials in which hydrogens thereof are substituted with Li, Na, or Ca, etc., and may also include various copolymers thereof.

[0132] In particular, the cathode binder according to one embodiment of the present specification serves to hold the cathode active material and the cathode conductive material to prevent distortion and structural deformation of the cathode structure during volume expansion and relaxation of the silicon-based active material. Any general cathode binder that satisfies the above role can be applied, specifically, a water-based binder can be used, and more specifically, a styrene butadiene rubber (SBR)-based binder can be used.

[0133] According to another embodiment of the present specification, the cathode active material layer may further comprise a dispersant. The dispersant is characterized by improving the dispersibility of the cathode active material or cathode binder material, while simultaneously contributing to the adhesion with the cathode current collector layer, thereby preventing the cathode active material from detaching from the cathode current collector layer.

[0134] A dispersant according to one embodiment of the present specification may be a cellulose-based polymer and may be one or more selected from the group consisting of carboxymethylcellulose (CMC), methylcellulose (MC), hydroxypropylcellulose (HPC), methyl hydroxypropylcellulose (MHPC), ethyl hydroxyethylcellulose (EHEC), methyl ethyl hydroxyethylcellulose (MEHEC), and cellulose gum; specifically, it may be one or more selected from the group consisting of carboxymethylcellulose (CMC), methylcellulose (MC), and hydroxypropylcellulose (HPC); and more specifically, it may be carboxymethylcellulose (CMC).

[0135] In one embodiment of the present specification, the dispersant may be included in an amount of 0.1 parts by weight or more and 1 part by weight or less per 100 parts by weight of the total solid content of the cathode slurry, specifically in an amount of 0.15 parts by weight or more and 0.9 parts by weight or less, and more specifically in an amount of 0.3 parts by weight or more and 0.8 parts by weight or less.

[0136] In one embodiment of the present specification, the negative current collector layer may generally have a thickness of 1 μm to 100 μm, specifically 1 μm to 50 μm, and more specifically 1 μm to 30 μm. Such a negative current collector layer is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface treated with carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloy may be used. In addition, fine irregularities may be formed on the surface to strengthen the bonding strength of the negative active material, and it may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0137] An electrode for a lithium secondary battery manufactured by the above-described manufacturing method according to one embodiment of the present specification comprises an electrode current collector layer and an electrode active material layer, and the area of ​​residual lithium occupying the surface of the electrode for the lithium secondary battery may be 6% or less of the total surface area of ​​the electrode for the lithium secondary battery.

[0138] Figure 3 is a figure showing the surface of a lithium secondary battery electrode after complete pre-lithiation (KEYENCE VHX-7000N). Specifically, referring to Figure 3, when residual lithium remains on the surface of a lithium secondary battery electrode after complete pre-lithiation, it can be seen that the residual lithium portion is reflected in a color close to white and appears bright.

[0139] In the present specification, the area of ​​lithium remaining on the surface of the electrode for the lithium secondary battery can be calculated by observing the surface of the electrode, after the carrier film removal and pre-lithiation are completed, under a microscope.

[0140] FIG. 4 is a figure showing the surface of a lithium secondary battery electrode that has completed pre-lithiation, observed at 200× magnification using a microscope (KEYENCE VHX-7000N). Specifically, referring to FIG. 4, as in FIG. 3, it can be seen that the residual lithium portion reflects in a color close to white and appears as a bright dot. After designating a certain area (shaded area at the top of the right figure), the area of ​​residual lithium relative to the area of ​​the certain area can be calculated by detecting the part with a difference in brightness. In one embodiment of the present specification, the area of ​​residual lithium in the lithium secondary battery electrode may be 6% or less of the area of ​​the certain area.

[0141] A lithium secondary battery according to another embodiment of the present specification may include the aforementioned electrode for a lithium secondary battery; a separator; and an electrolyte.

[0142] FIG. 5 is a diagram showing a stacked structure of a lithium secondary battery manufactured according to one embodiment of the present invention. Specifically, a positive electrode (100) for a lithium secondary battery including a positive active material layer (20) on one surface of a positive current collector layer (10) can be seen, and a negative electrode (200) for a lithium secondary battery including a negative active material layer (40) on one surface of a negative current collector layer (50) can be seen, and the structure is formed such that the positive electrode (100) for a lithium secondary battery and the negative electrode (200) for a lithium secondary battery are stacked with a separator (30) in between. The electrode for a lithium secondary battery according to one embodiment of the present specification may be the positive electrode (100) for a lithium secondary battery or the negative electrode (200) for a lithium secondary battery.

[0143] In one embodiment of the present specification, the anode may comprise a lithium complex transition metal compound as an anode active material, comprising nickel (Ni) and cobalt (Co) and further comprising one or more elements selected from the group consisting of Na, K, Mg, Ca, Sr, Ni, Co, Ti, Al, Si, Sn, Mn, Cr, Fe, V, and Zr.

[0144] In one embodiment of the present specification, the anode may include a lithium complex transition metal compound comprising nickel (Ni), cobalt (Co), and manganese (Mn) as the anode active material.

[0145] In one embodiment of the present specification, the positive active material may be included in an amount of 60 parts by weight or more and 99 parts by weight or less based on 100 parts by weight of the positive active material layer, specifically in an amount of 70 parts by weight or more and 95 parts by weight or less, and more specifically in an amount of 80 parts by weight or more and 94 parts by weight or less.

[0146] In one embodiment of the present specification, the anode slurry comprises an anode conductive material and an anode binder, and may further comprise a thickener and a slurry solvent.

[0147] In one embodiment of the present specification, additional components such as the anode current collector layer, anode conductive material, anode binder, thickener and slurry solvent, and the method for manufacturing the anode may be used without limitation as long as they are known in the art within the scope to which the above description applies.

[0148] In one embodiment of the present specification, the separator separates the negative electrode and the positive electrode and provides a pathway for the movement of lithium ions. It may be used without special limitations as long as it is typically used as a separator in a secondary battery, and it is particularly desirable that it has low resistance to the movement of electrolyte ions and excellent electrolyte wettability. Specifically, a porous polymer film, such as a porous polymer film made of a polyolefin-based polymer like an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof may be used. In addition, a conventional porous nonwoven fabric, such as a nonwoven fabric made of high-melting-point glass fibers or polyethylene terephthalate fibers, may be used. Furthermore, a coated separator containing a ceramic component or a polymer material may be used to ensure heat resistance or mechanical strength, and it may optionally be used in a single-layer or multi-layer structure.

[0149] In one embodiment of the present specification, the electrolyte may be an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, a molten inorganic electrolyte, etc., which can be used in the manufacture of a lithium secondary battery, but is not limited to these.

[0150] Specifically, the electrolyte may include a non-aqueous organic solvent and a metal salt.

[0151] A battery module according to one embodiment of the present specification may include the aforementioned lithium secondary battery.

[0152] A battery pack according to another embodiment of the present specification may include the aforementioned lithium secondary battery or a battery module including the aforementioned lithium secondary battery.

[0153] Since the lithium secondary battery according to the embodiments of this specification stably exhibits excellent discharge capacity, output characteristics, and cycle performance, it can be used as a power source for portable devices such as mobile phones, laptop computers, and digital cameras, as well as for medium-to-large devices selected from the group consisting of electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and power storage systems. For example, the battery module or battery pack can be used as a power source for one or more medium-to-large devices, including a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0154] Hereinafter, preferred embodiments are presented to aid in understanding the present invention; however, the above embodiments are merely illustrative of the description, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and spirit of the description, and that such variations and modifications fall within the scope of the appended claims.

[0155] Preparation Example

[0156] Example 1

[0157] Manufacturing of transfer laminates

[0158] A transfer laminate was prepared by coating a solution containing polymethylmethacrylate (PMMA) onto a PET (polyethylene terephthalate) carrier film satisfying the maximum height roughness (Sz) and arithmetic mean roughness (Sa) of Table 1 below to form a release layer, and then depositing a lithium metal layer (thickness: 6.2 μm) on top of it by physical vapor deposition (PVD).

[0159] Manufacturing of electrodes

[0160] A cathode slurry was prepared by including 90 g of Si and graphite in a ratio of 30:70 as cathode active materials, 5 g of SBR (styrene-butadiene rubber) and 4 g of CMC (carboxymethyl cellulose) as binders, and additionally a CNT pre-dispersion liquid containing 0.09 g of dispersant and 0.91 g of single-walled CNT.

[0161] The above cathode slurry is placed on a copper foil (thickness 8 μm) with a capacity of 3.8 mAh / cm² per unit area 2 The cathode was manufactured by coating and drying to achieve this.

[0162] Subsequently, the transfer laminate prepared above is laminated onto both sides of the electrode active material layer of the above electrode while applying a transfer load of 400 kgf to produce 1 mAh / cm² 2 Full lithium conversion was carried out with the capacity of .

[0163] Comparative Example 1

[0164] The electrode for a lithium secondary battery of Comparative Example 1 was prepared in the same manner as in Example 1, except that the arithmetic mean roughness (Sa) of the PET carrier film used during pre-lithiation was 1.28 μm and the maximum height roughness (Sz) was 17.62 μm.

[0165] Comparative Example 2

[0166] The electrode for a lithium secondary battery of Comparative Example 2 was prepared in the same manner as in Example 1, except that the arithmetic mean roughness (Sa) of the PET carrier film used during pre-lithiation was 13.34 μm and the maximum height roughness (Sz) was 53.9 μm.

[0167] Comparative Example 3

[0168] The electrode for a lithium secondary battery of Comparative Example 3 was manufactured in the same manner as Comparative Example 2, except that the pressure load during pre-lithiation was 200 kgf.

[0169] FIG. 6 is a 3D figure showing the surface roughness of the carrier film before deposition of the lithium metal layer used in Example 1 and Comparative Examples 1 to 3. Specifically, FIG. 6 shows the roughness measurement performed after height correction following image measurement using a microscope (KEYENCE VHX-7000N), and the roughness was visualized in 3D to better represent the roughness. With reference to FIG. 6, the arithmetic mean roughness (Sa) and maximum height roughness (Sz) in Table 1 below are shown.

[0170] Experimental Example 1: Visual Evaluation of Residual Lithium on the Surface of Electrode for Lithium Secondary Battery

[0171] The surfaces of the lithium secondary battery electrodes of Example 1, Comparative Examples 1 and 2 were photographed (KEYENCE VHX-7000N) and are shown in FIG. 3. Specifically, referring to FIG. 3, it can be seen that the surface of the lithium secondary battery electrode of Example 1 has significantly fewer bright areas because there is less residual lithium, whereas the lithium secondary battery electrodes of Comparative Examples 1 and 2 have many bright areas that reflect light close to white because residual lithium remains on the surface. Although the surface of the lithium secondary battery electrode of Comparative Example 3 is not shown, a large amount of residual lithium remained on the surface, similar to Comparative Example 2.

[0172] Experimental Example 2: Evaluation of Residual Lithium Area on the Surface of an Electrode for a Lithium Secondary Battery

[0173] The carrier film used in the manufacture of the electrodes for lithium secondary batteries of Example 1 and Comparative Examples 1 to 3 and the pressure load applied during lamination are as shown in Table 1 below.

[0174] As shown in FIG. 4, the electrodes for the lithium secondary batteries of Example 1 and Comparative Examples 1 to 3, which had completed pre-lithiation, were observed under a microscope (KEYENCE VHX-7000N) at a magnification of 200×. After designating a certain area (shaded portion at the top of the right figure) on the surface, a portion with a difference in brightness was detected, and the area of ​​residual lithium relative to the area of ​​the certain area was calculated and shown in Table 1 below.

[0175] Arithmetic Mean Roughness (Sa) (μm) Max Height Roughness (Sz) (μm) Pressurized Load (kgf) Residual Lithium Area (%) Example 1 0.27 7.06 400 5.5 Comparative Example 11.28 17.6 2400 6.1 Comparative Example 2 13.3 45 3.9 400 8.65 Comparative Example 3 13.3 45 3.9 200 9.07

[0176] Referring to Table 1 above, it can be confirmed that the electrode for a lithium secondary battery of Example 1, manufactured using a carrier film satisfying the surface roughness range according to one embodiment of the present specification, has the smallest area of ​​lithium remaining on the electrode surface compared to Comparative Examples 1 to 3.

[0177] Specifically, the electrode for a lithium secondary battery of Comparative Example 1, manufactured using a carrier film in which either the maximum height roughness (Sz) or the arithmetic mean roughness (Sa) does not satisfy the surface roughness range according to one embodiment of the present specification, particularly a carrier film in which the maximum height roughness (Sz) range does not satisfy, had a residual lithium area increased by 10.9% compared to Example 1.

[0178] The electrode for a lithium secondary battery of Comparative Example 2, which does not satisfy both the maximum height roughness (Sz) and arithmetic mean roughness (Sa) ranges according to one embodiment of the present specification, has an area of ​​residual lithium increased by 57.27% compared to Example 1.

[0179] Comparative Example 3 has the same maximum height roughness (Sz) and arithmetic mean roughness (Sa) as Comparative Example 2, but because the transfer laminate was pressed with a smaller load than Comparative Example 2 after contacting one side of the electrode active material layer, it can be confirmed that the pre-lithiation reaction did not occur sufficiently, resulting in a larger amount of residual lithium being generated on the electrode surface. In other words, the area of ​​residual lithium in the lithium secondary battery electrode of Comparative Example 3 increased by as much as 64.9% compared to Example 1.

[0180] Accordingly, by performing lamination with a transfer laminate comprising a carrier film that satisfies the range of a maximum height roughness (Sz) in the vertical direction of 17 μm or less and an arithmetic mean roughness (Sa) of 3 μm or less according to one embodiment of the present invention, the amount of residual lithium generated on the electrode surface after completion of prelithiation can be significantly reduced, and thereby, lithium precipitation and loss of the added lithium can be suppressed.

[0181]

[0182] [Explanation of the symbol]

[0183] 10: Positive current collector layer

[0184] 20: Positive active material layer

[0185] 30: Separator

[0186] 40: Cathode active material layer

[0187] 50: Cathode current collector layer

[0188] 60: Electrode active material layer

[0189] 100: Cathode for lithium secondary batteries

[0190] 200: Negative electrode for lithium secondary batteries

[0191] 300: Electrode for lithium secondary battery

[0192] 400: Lithium metal layer

[0193] 500: Carrier Film

[0194] 600: Transfer laminate

Claims

The method includes the step of laminating a transfer laminate comprising a lithium metal layer and a carrier film on one surface of an electrode active material layer provided on at least one surface of an electrode current collector layer, A method for manufacturing an electrode for a lithium secondary battery, wherein at least one surface of the carrier film has a maximum height roughness (Sz) in the vertical direction of 17 μm or less and an arithmetic mean roughness (Sa) of 3 μm or less. In claim 1, A method for manufacturing an electrode for a lithium secondary battery, wherein the maximum height roughness (Sz) in the vertical direction of the surface of the carrier film facing the lithium metal layer is 17 μm or less, and the arithmetic mean roughness (Sa) is 3 μm or less. In claim 1, A method for manufacturing an electrode for a lithium secondary battery, wherein the maximum height roughness (Sz) in the vertical direction of the back surface of the surface facing the lithium metal layer of the carrier film is 17 μm or less, and the arithmetic mean roughness (Sa) is 3 μm or less. In claim 1, A method for manufacturing an electrode for a lithium secondary battery, wherein the carrier film comprises one or more selected from the group consisting of polyethylene terephthalate (PET), polyimide (PI), poly(methylmethacrylate), PMMA, polypropylene, polyethylene, and polycarbonate. In claim 1, A method for manufacturing an electrode for a lithium secondary battery, wherein the thickness of the lithium metal layer is 10 μm or less. In claim 1, The step of laminating a transfer laminate on one surface of the electrode active material layer is A step of positioning the transfer laminate so that the lithium metal layer contacts one surface of the electrode active material layer; and A method for manufacturing an electrode for a lithium secondary battery, comprising the step of pressing the electrode active material layer and the transfer laminate together. In claim 1, A method for manufacturing an electrode for a lithium secondary battery, wherein the above-described transfer laminate is provided by any one of the methods of depositing, rolling, and melting the lithium metal layer on one surface of the carrier film. The electrode current collector layer; and the electrode active material layer are included, An electrode for a lithium secondary battery manufactured by a manufacturing method according to any one of claims 1 to 7, A lithium secondary battery electrode in which the area of ​​residual lithium occupying the surface of the lithium secondary battery electrode is 6% or less of the total surface area of ​​the lithium secondary battery electrode. Electrode for a lithium secondary battery according to claim 8; Separator; and A lithium secondary battery containing an electrolyte. A battery module comprising a lithium secondary battery according to claim 9. A battery pack comprising a battery module according to claim 10. A battery pack comprising a lithium secondary battery according to claim 9. It comprises a lithium metal layer; and a carrier film, A transfer laminate for pre-lithiation, wherein the maximum height roughness (Sz) in the vertical direction of the surface of the carrier film facing the lithium metal layer is 17 μm or less, and the arithmetic mean roughness (Sa) is 3 μm or less. In claim 13, A transfer laminate for pre-lithiation, wherein the maximum height roughness (Sz) in the vertical direction of the back surface of the surface facing the lithium metal layer of the carrier film is 17 μm or less, and the arithmetic mean roughness (Sa) is 3 μm or less. In claim 13, The above carrier film comprises one or more selected from the group consisting of polyethylene terephthalate (PET), polyimide (PI), poly(methylmethacrylate), PMMA, polypropylene, polyethylene, and polycarbonate, for a pre-lithiation transfer laminate. In claim 13, A transfer laminate for pre-lithiation having a lithium metal layer thickness of 0.1 μm or more and 10 μm or less.

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