Method and apparatus for manufacturing electrode using volatile guide liquid and electrode manufactured using the same

Abstract

The method for manufacturing an electrode according to some embodiments includes: a guide liquid applying step of applying a guide liquid defining an electrode slurry applying region to a current collector sheet; an electrode paste application step of applying an electrode paste to the electrode paste application region; and a drying step of drying the guide liquid and the electrode slurry, in which 85 wt% to 95 wt% of the guide liquid may be evaporated in the drying step. Some embodiments of the present invention can improve the edge profile of the electrode.

Description

Technical Field

[0001] This application claims the benefit of Korean Patent Application No. 10-2024-0074674, filed on June 10, 2024, the disclosure of which is incorporated herein by reference.

[0002] This disclosure relates to methods for manufacturing electrodes, apparatus for manufacturing electrodes, and electrodes, and more particularly to methods and apparatus for manufacturing electrodes using volatile guiding liquids, and electrodes manufactured using the same. Background Technology

[0003] Interest is growing in rechargeable batteries that can be reused for extended periods to reduce reliance on fossil fuels and decrease carbon emissions. In particular, lithium-ion batteries offer excellent energy density and lifespan. Therefore, lithium-ion batteries are used in various fields, such as portable electronic devices, vehicles, and energy storage systems (ESS).

[0004] The electrodes applied to a lithium-ion secondary battery include a current collector and an electrode active material layer coated on one or both sides of the current collector. The electrode active material layer is typically formed by applying an electrode slurry to the current collector and then drying it. The electrode active material layer is manufactured by dispensing a fluid electrode slurry onto the current collector and then drying it. During this process, slippage occurs at the edge portions of the electrode active material layer, causing the thickness to decrease outwards. To improve electrode quality and increase capacity, a technique is needed to control the angle at the edges of the electrode active material layer to be close to a right angle.

[0005] To achieve this, conventional methods include applying an insulating tape or coating an insulating layer onto the sliding region of the electrode active material layer. However, these methods suffer from the problem of residual components from the insulating tape or insulating layer remaining after drying. These residual components reduce the activity of the electrode active material layer, leading to a decrease in electrode capacity.

[0006] Therefore, a new manufacturing method is needed that can suppress the slippage phenomenon that occurs in the slip region of the electrode active material layer during electrode manufacturing, while minimizing the reduction in electrode capacity. Summary of the Invention

[0007] Technical issues

[0008] This disclosure can suppress the sliding phenomenon that occurs in the sliding region of the electrode active material layer, while minimizing the reduction in electrode capacity.

[0009] Technical solution

[0010] The method for manufacturing an electrode according to this disclosure includes: a guiding liquid application step, applying a guiding liquid defining an electrode slurry application area onto a current collector sheet; an electrode slurry application step, applying an electrode slurry onto the electrode slurry application area defined by the guiding liquid; and a drying step, drying the guiding liquid and electrode slurry applied to the electrode sheet. In one embodiment, at least 85% by weight of the guiding liquid is evaporated during the drying step. Specifically, from 85% to 95% by weight of the guiding liquid is evaporated during the drying step.

[0011] In one example, the guiding fluid may include solvents and adhesives.

[0012] Solvents may include one or more of dimethyl sulfoxide, isopropanol, N-methylpyrrolidone, acetone, methyl acetate, ethyl acetate, γ-butyrolactone, ε-caprolactone, dibutyl ether, tetrahydrofuran, cyclohexanone, benzene, fluorobenzene, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, and water.

[0013] The adhesive may include one or more of polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, and styrene-butadiene rubber-carboxymethyl cellulose fluororubber.

[0014] In one embodiment, the method for manufacturing the electrode is a method for manufacturing a positive electrode. In this case, the electrode paste is a positive electrode paste and satisfies the following formula 1.

[0015] [Formula 1]

[0016]

[0017] In Equation 1,

[0018] Vs1 represents the viscosity of the cathode slurry measured at a shear rate of 2.5 cps at 25°C, and is in the range of 5,000 cps to 30,000 cps.

[0019] Vg1 represents the viscosity (cps) of the guiding fluid measured at a shear rate of 2.5 / s at 25°C.

[0020] In another embodiment, the method for manufacturing the electrode is the method for manufacturing the negative electrode. In this case, the electrode paste is a negative electrode paste and satisfies the following formula 2.

[0021] [Equation 2]

[0022]

[0023] In Equation 2,

[0024] Vs2 represents the viscosity of the negative electrode slurry measured at a shear rate of 2.5 / s at 25°C, and is in the range of 2,000 cps to 6,000 cps.

[0025] Vg2 represents the viscosity (cps) of the guiding fluid measured at a shear rate of 2.5 / s at 25°C.

[0026] In one implementation, the time interval (|T1-T3|) between the start time (T1) of the guiding liquid application step and the completion time (T3) of the drying step is in the range of 300 seconds or less.

[0027] In another embodiment, the time interval (|T1-T2|) between the start time of the guide liquid application step (T1) and the start time of the electrode slurry application step (T2) is 3 seconds or less.

[0028] In another embodiment, the time interval (|T1-T2|) between the start time (T1) of the guide liquid application step and the start time (T2) of the electrode slurry application step is greater than 3 seconds and less than 20 seconds.

[0029] This disclosure provides a manufacturing apparatus for implementing the above-described method of manufacturing an electrode. In one embodiment, the apparatus for manufacturing an electrode according to this disclosure includes: a coating section that applies a guiding liquid defining an electrode slurry application area to a current collector and applies electrode slurry to the electrode slurry application area; and a drying section that dries the guiding liquid and the electrode slurry. In one embodiment, the viscosity of the guiding liquid is controlled to be lower than the viscosity of the electrode slurry.

[0030] In one embodiment, the coating section includes a first coating mold and a second coating mold. The first coating mold applies a guiding liquid to the current collector, and the second coating mold applies an electrode paste to the current collector.

[0031] In another embodiment, the coating section includes a single coating mold that simultaneously applies the guide liquid and electrode slurry to the current collector sheet.

[0032] This disclosure provides an electrode manufactured by the above-described method or apparatus for manufacturing electrodes. In one embodiment, the electrode according to this disclosure includes: a current collector and an electrode active material layer formed on one or both surfaces of the current collector. Furthermore, the electrode active material layer includes a flat portion and a sliding portion formed at the edge of the flat portion. The sliding angle of the sliding portion is in the range of 45° to 90°.

[0033] Beneficial effects

[0034] Some embodiments of this disclosure can improve the edge profile of the electrode. Furthermore, some embodiments of this disclosure can avoid reducing the conductivity of the electrode.

[0035] This disclosure can suppress the sliding phenomenon that occurs in the sliding region of the electrode active material layer, while minimizing the reduction in electrode capacity. Attached Figure Description

[0036] Figure 1 This is a schematic diagram illustrating an apparatus for manufacturing electrodes according to some embodiments.

[0037] Figure 2 yes Figure 1 Top view.

[0038] Figure 3 This is a schematic diagram illustrating an apparatus for manufacturing electrodes according to other embodiments.

[0039] Figure 4 yes Figure 3 Top view.

[0040] Figure 5 This is a flowchart illustrating a method for manufacturing an electrode according to some embodiments.

[0041] Figure 6 It is along Figure 4 The sectional view taken by section lines 4I-4I' in the diagram.

[0042] Figure 7 It is along Figure 4 The sectional view taken by section lines 4II-4II' in the diagram.

[0043] Figure 8 It is along Figure 4 The sectional view taken by section lines 4III-4III' in the diagram.

[0044] Figure 9 It is along Figure 4 The cross-sectional view taken from the section line 4Ⅳ-4Ⅳ'.

[0045] Figure 10 This is a schematic diagram showing electrodes according to some embodiments. Detailed Implementation

[0046] The terms and words used in this specification should not be construed as limited to their conventional or dictionary meanings, but rather as being interpreted in accordance with the principles of their invention in a manner best possible to describe the inventors, so as to conform to the technical concept of this disclosure.

[0047] In this specification, terms such as “comprising” or “having” are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should not be construed as excluding the presence or possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof. Furthermore, when a part such as a layer, film, region, or plate is described as being “on” another part, this includes not only the case where it is directly above the other part, but also the case where another part is present between them. Conversely, when a part such as a layer, film, region, or plate is described as being “below” another part, this includes not only the case where it is directly below the other part, but also the case where another part is present between them.

[0048] The method for manufacturing an electrode according to this disclosure includes: a guiding liquid application step, applying a guiding liquid defining an electrode slurry application area onto a current collector sheet; an electrode slurry application step, applying an electrode slurry onto the electrode slurry application area defined by the guiding liquid; and a drying step, drying the guiding liquid and electrode slurry applied to the electrode sheet. In one example, at least 85% by weight of the guiding liquid is evaporated during the drying step. Specifically, 85% to 95% by weight of the guiding liquid is evaporated during the drying step. In this disclosure, by forming a guiding liquid with highly volatile components, slippage of the electrode slurry is suppressed, while most of the guiding liquid components are simultaneously evaporated during the drying process, thereby minimizing residual components.

[0049] In one example, the guiding fluid may include a solvent and a binder. In this disclosure, the guiding fluid may also consist of only a solvent. However, by including a certain level of binder in the guiding fluid, the viscosity of the guiding fluid can be increased. This allows for more effective suppression of electrode slurry slippage. In the guiding fluid, the solvent to binder content ratio, based on weight ratio, can range from 80:20 to 98:2. More specifically, the solvent to binder content ratio can range from 85:15 to 95:5, 90:10 to 95:5, 85:15 to 90:10, or 88:12 to 92:8. Within the above ranges, if the binder content becomes too high, the ionic conductivity may decrease as the amount of binder retained on the current collector surface increases. Conversely, if the binder content becomes too low, the viscosity of the guiding fluid may not reach the desired level and may be insufficient to suppress electrode slurry slippage.

[0050] Solvents may include one or more of dimethyl sulfoxide, isopropanol, N-methylpyrrolidone, acetone, methyl acetate, ethyl acetate, γ-butyrolactone, ε-caprolactone, dibutyl ether, tetrahydrofuran, cyclohexanone, benzene, fluorobenzene, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, and water.

[0051] The adhesive may include one or more of polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, and styrene-butadiene rubber-carboxymethyl cellulose fluororubber.

[0052] In one embodiment, the method for manufacturing the electrode is a method for manufacturing a positive electrode. In this case, the electrode paste is a positive electrode paste and satisfies the following formula 1.

[0053] [Formula 1]

[0054]

[0055] In Equation 1,

[0056] Vs1 represents the viscosity of the cathode slurry measured at a shear rate of 2.5 cps at 25°C, and is in the range of 5,000 cps to 30,000 cps.

[0057] Vg1 represents the viscosity (cps) of the guiding fluid measured at a shear rate of 2.5 / s at 25°C.

[0058] Specifically, the value (cps) calculated according to Equation 1 falls within the range of 150 to 7,000, 150 to 6,500, 2,500 to 7,000, 3,000 to 7,000, 3,000 to 6,500, 4,000 to 6,500, 4,500 to 6,500, or 4,500 to 5,500.

[0059] In another embodiment, the method for manufacturing the electrode is the method for manufacturing the negative electrode. In this case, the electrode paste is a negative electrode paste and satisfies the following formula 2.

[0060] [Equation 2]

[0061]

[0062] In Equation 2,

[0063] Vs2 represents the viscosity of the negative electrode slurry measured at a shear rate of 2.5 / s at 25°C, and is in the range of 2,000 cps to 6,000 cps.

[0064] Vg2 represents the viscosity (cps) of the guiding fluid measured at a shear rate of 2.5 / s at 25°C.

[0065] Specifically, the value (cps) calculated according to Equation 2 falls within the range of 100 to 4,500, 200 to 4,500, 100 to 3,500, 1,000 to 4,500, 2,000 to 4,000, 1,000 to 3,500, 1,500 to 3,500, or 1,500 to 2,500.

[0066] In one implementation, the time interval (|T1-T3|) between the start time (T1) of the guiding liquid application step and the completion time (T3) of the drying step is in the range of 300 seconds or less.

[0067] In another embodiment, the time interval (|T1-T2|) between the start time of the guide liquid application step (T1) and the start time of the electrode slurry application step (T2) is 3 seconds or less. In this case, the guide liquid and electrode slurry on a single coating mold can be applied to the current collector simultaneously.

[0068] In another embodiment, the time interval (|T1-T2|) between the start time (T1) of the guide liquid application step and the start time (T2) of the electrode slurry application step is greater than 3 seconds and less than 20 seconds. In this case, the guide liquid and electrode slurry in two coating molds may be applied sequentially to the current collector sheet.

[0069] This disclosure provides a manufacturing apparatus for implementing the above-described method of manufacturing an electrode. In one embodiment, the apparatus for manufacturing an electrode according to this disclosure includes: a coating section that applies a guiding liquid defining an electrode slurry application area to a current collector and applies electrode slurry to the electrode slurry application area; and a drying section that dries the guiding liquid and the electrode slurry. In one embodiment, the viscosity of the guiding liquid is controlled to be lower than the viscosity of the electrode slurry.

[0070] In one embodiment, the coating section includes a first coating mold and a second coating mold. The first coating mold applies a guiding liquid to the current collector, and the second coating mold applies an electrode paste to the current collector.

[0071] In another embodiment, the coating section simultaneously applies the guiding liquid and electrode slurry from a single coating mold to the current collector sheet. For example, the single coating mold is a double-slit mold having a guiding liquid discharge lip and an electrode slurry discharge lip formed together.

[0072] This disclosure provides an electrode manufactured by the method or apparatus described above. In one embodiment, the electrode according to this disclosure includes a current collector and an electrode active material layer formed on one or both surfaces of the current collector. Furthermore, the electrode active material layer includes a flat portion and a sliding portion formed at the edge of the flat portion. The sliding angle of the sliding portion is in the range of 45° to 90°.

[0073] Specifically, the sliding angle of the sliding part is 30° or greater, specifically within the range of 45° to 90°, 45° to 80°, or 50° to 80°.

[0074] The present disclosure is described in more detail below with reference to the accompanying drawings. The drawings are provided to provide a more complete explanation of the disclosure to those skilled in the art. Therefore, for clarity, the shape, size, and number of parts in the drawings may be enlarged, omitted, or shown schematically. The shape, size, scale, and number of each part in the drawings do not necessarily perfectly reflect the actual shape, size, scale, and number of each part.

[0075] apparatus for manufacturing electrodes

[0076] One aspect of this disclosure relates to an apparatus for manufacturing electrodes.

[0077] Figure 1 This is a schematic diagram illustrating an apparatus for manufacturing electrodes according to some embodiments.

[0078] Figure 2 yes Figure 1 Top view.

[0079] refer to Figure 1 and 2 The electrode manufacturing apparatus 1000 may include a first roller 1011, a second roller 1012, a coating apparatus 1020, and a drying apparatus 1030.

[0080] The first roller 1011 can carry a current collector (CC). The first roller 1011 can be configured to unwind the current collector (CC). The second roller 1012 can be configured to move the current collector (CC). Figure 1 The first roller 1011 and the second roller 1012 shown are merely exemplary. The electrode manufacturing apparatus 1000 may include multiple rollers capable of performing a so-called roll-to-roll process.

[0081] In the following text, the direction of movement of the current collector (CC) is referred to as MD (machine direction). MD can be called the longitudinal direction. In the following text, the direction that is substantially perpendicular to MD but substantially parallel to the upper surface of the current collector (CC) is referred to as TD (transverse direction). TD can be called the width direction. In the following text, the direction that is substantially perpendicular to both MD and TD is referred to as VD (vertical direction). VD can be called the thickness direction.

[0082] The coating apparatus 1020 can be configured to apply a guiding liquid (GL) defining the electrode slurry application area to the current collector (CC) and to apply electrode slurry (ES) to the electrode slurry application area.

[0083] In some embodiments, the coating apparatus 1020 may include an upper mold, a lower mold, and a coating shim inserted between the upper and lower molds. Insulating liquid application flow paths may be formed on both sides of the coating shim.

[0084] In some embodiments, the coating apparatus 1020 may include an upper mold, a middle mold, a lower mold, a first coating pad inserted between the upper mold and the middle mold, and a second coating pad inserted between the middle mold and the lower mold. An insulating liquid application flow path may be formed on both sides of at least one of the first and second coating pads.

[0085] The drying device 1030 can be configured to dry the guide liquid (GL) and the electrode paste (ES). The drying device 1030 can be located downstream of the coating device 1020. The drying device 1030 can be configured to remove solvent from the guide liquid (GL) and the electrode paste (ES) or reduce the solvent content therein. The drying device 1030 can be a hot air jetting device. The drying device 1030 can include multiple hot air jetting devices with different air temperatures, air jetting speeds, and air jetting volumes.

[0086] In some embodiments, the hot air jetting device may include a drying oven, a hot air jetting nozzle, a hot air generating unit, and a pipe connecting the hot air jetting nozzle and the hot air generating unit.

[0087] Figure 3 This is a schematic diagram illustrating an apparatus for manufacturing electrodes according to other embodiments.

[0088] Figure 4 yes Figure 3 Top view.

[0089] refer to Figure 3 and Figure 4The electrode manufacturing apparatus 1000' may include a first roller 1011, a second roller 1012, a first coating device 1021, a second coating device 1022, and a drying device 1030.

[0090] The first coating apparatus 1021 may be configured to apply a guiding liquid (GL) to a current collector (CC) to define an electrode slurry application area. In some embodiments, the first coating apparatus 1021 may include an upper mold, a lower mold, and a coating pad inserted between the upper mold and the lower mold.

[0091] The second coating device 1022 can be configured to apply electrode paste (ES) to the electrode paste application area. The second coating device 1022 can be located downstream of the first coating device 1021. In some embodiments, the second coating device 1022 may include an upper mold, a lower mold, and a coating pad inserted between the upper mold and the lower mold. In some embodiments, the second coating device 1022 may include an upper mold, a middle mold, a lower mold, a first coating pad inserted between the upper mold and the middle mold, and a second coating pad inserted between the middle mold and the lower mold.

[0092] Methods for manufacturing electrodes

[0093] Another aspect of this disclosure relates to a method for manufacturing an electrode.

[0094] Figure 5 This is a flowchart illustrating a method for manufacturing an electrode according to some embodiments.

[0095] Reference Figure 5 The method for manufacturing an electrode may include a guiding liquid application step P110, an electrode slurry application step P120, and a drying step P130. The method for manufacturing an electrode according to some embodiments can be performed in the aforementioned electrode manufacturing apparatus.

[0096] In the guide liquid application step P110, the guide liquid (GL) can be applied to the current collector (CC) to define the electrode slurry application area. Figure 6 It is along Figure 4 The sectional view is taken from section lines 4I-4I'. (Reference) Figure 4 and Figure 6During the guiding liquid application step P110, the guiding liquid (GL) can be applied to the current collector (CC) in the transverse direction along two lines spaced apart by a predetermined distance. Here, the area on the current collector located between the two lines can be defined as the electrode slurry application area. However, this is merely illustrative; the guiding liquid (GL) can define the electrode slurry application area on the current collector (CC) in other ways. For example, the guiding liquid (GL) can be applied to the current collector (CC) in the longitudinal direction (MD) along two lines spaced apart by a predetermined distance, thereby defining the electrode slurry application area on the current collector (CC).

[0097] The current collector (CC) can comprise a conductive material that does not cause chemical changes in the final electrode. For example, the current collector (CC) can comprise aluminum, copper, stainless steel, nickel, titanium, or calcined carbon. Alternatively, the current collector (CC) can comprise aluminum, copper, and stainless steel that have been surface-treated with carbon, nickel, titanium, silver, etc. The surface of the current collector (CC) can have a formed micro-irregular structure to enhance adhesion to the electrode active material layer. The shape of the current collector (CC) can be a sheet, film, foil, mesh, porous body, foam, or nonwoven fabric. The thickness of the current collector (CC) can range from about 3 μm to about 500 μm.

[0098] In the electrode slurry application step P120, electrode slurry (ES) can be applied to the electrode slurry application area. Figure 7 It is along Figure 4 The sectional view taken by section lines 4II-4II' in the diagram. Figure 8 It is along Figure 4 The sectional view taken by section lines 4III-4III' in the diagram. (Refer to...) Figure 4 , Figure 7 and Figure 8 In the electrode slurry application step P120, the electrode slurry (ES) can be applied between two lines formed by the guide liquid (GL).

[0099] During drying step P130, the guiding liquid (GL) and electrode slurry (ES) can be dried. During drying step P130, the solvent in the guiding liquid (GL) and electrode slurry (ES) can be removed. Figure 9 It is along Figure 4 The sectional view taken by section line 4Ⅳ-4Ⅳ'. (Refer to...) Figure 4 and Figure 9During the drying step P130, the guiding liquid (GL) and electrode slurry (ES) can be integrated into the electrode active material layer (AL). Taking into account the boiling points of the solvents in the guiding liquid (GL) and electrode slurry (ES) and the amount of solvent present, the temperature and duration of the drying step P130 can be determined. As a non-limiting example, the drying step P130 can be carried out at a temperature of approximately 100°C to 300°C for approximately 30 to 150 seconds.

[0100] refer to Figures 6 to 9 This paper describes a method for manufacturing an electrode according to some embodiments, showing how it improves the electrode edge profile. The profile of the guiding liquid (GL) can be maintained before the drying step P130, similar to when the guiding liquid (GL) is initially applied to the current collector (CC). The guiding liquid (GL) can mitigate the tendency of electrode slurry (ES) to diffuse into the current collector (TD). Therefore, the edge profile of the electrode formed after the drying step P130 can be improved. Here, during the drying step P130, 85% to 95% by weight of the guiding liquid (GL) is evaporated. That is, most of the guiding liquid (GL) evaporates during the drying step P130. Therefore, the conductivity of the finally manufactured electrode can be excellent.

[0101] In some implementations, the guiding fluid (GL) may include solvents and adhesives.

[0102] The solvent can be almost completely evaporated during the drying step P130. The solvent may include one or more of dimethyl sulfoxide, isopropanol, N-methylpyrrolidone, acetone, methyl acetate, ethyl acetate, γ-butyrolactone, ε-caprolactone, dibutyl ether, tetrahydrofuran, cyclohexanone, benzene, fluorobenzene, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, and water. As a specific example, the solvent may be N-methylpyrrolidone. As a specific example, the solvent may be a mixture of N-methylpyrrolidone and ethylene carbonate, or a mixture of N-methylpyrrolidone and propylene carbonate. The solvent can be selected considering the viscosity of the guiding liquid (GL). The content of solvent in the guiding liquid (GL) can be selected considering the viscosity of the guiding liquid (GL). In some embodiments, the guiding liquid (GL) may contain 85% by weight or more, or 85% by weight to 95% by weight of solvent. In some embodiments, the guiding fluid (GL) may contain 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, or 94% or more of a solvent. In some embodiments, the guiding fluid (GL) may contain 94% or less, 93% or less, 92% or less, 91% or less, 90% or less, 89% or less, 88% or less, 87% or less, or 86% or less of a solvent.

[0103] An adhesive can increase the viscosity of the guiding fluid (GL). The adhesive may include one or more of polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, and styrene-butadiene rubber-carboxymethyl cellulose fluororubber. As a specific example, the adhesive may be polyvinylidene fluoride. The adhesive can be selected considering the viscosity of the guiding fluid (GL). The content of the adhesive in the guiding fluid (GL) can be selected considering the viscosity of the guiding fluid (GL). In some embodiments, the guiding fluid (GL) may contain 5% to 15% by weight of adhesive. In some embodiments, the guiding fluid (GL) may contain 6% or more, 7% or more, 8% or more, 9% or more, 10% or more, 11% or more, 12% or more, 13% or more, or 14% or more of adhesive. In some embodiments, the guiding fluid (GL) may contain 14% or less, 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, or 6% or less of adhesive.

[0104] In some embodiments, the guiding liquid (GL) may include a solvent and a binder. The solvent and binder are described as described above. In some embodiments, the guiding liquid (GL) may not include inorganic particles. Therefore, after drying step P130, inorganic particles may not remain on the current collector, thereby preventing a decrease in the conductivity of the electrode. As a non-limiting example, the inorganic particles may be one or more of Al O(OH), Al2O3, Al(OH)3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, and Mg(OH)2.

[0105] Factors such as the viscosity of the electrode slurry (ES) and the time interval between the start time of the guiding liquid application step P110 and the completion time of the drying step P130 can be considered to determine the viscosity of the guiding liquid (GL). For example, a higher viscosity of the electrode slurry (ES) can increase the viscosity of the guiding liquid (GL). For example, the longer the time interval between the start time of the guiding liquid application step P110 and the completion time of the drying step P130, the higher the viscosity of the guiding liquid (GL) can be increased. If the viscosity of the guiding liquid (GL) is too low relative to the viscosity of the electrode slurry (ES), the guiding liquid (GL) may be insufficient to mitigate the tendency of the electrode slurry (ES) to diffuse toward the TD.

[0106] In some embodiments, the electrode slurry (ES) can be a positive electrode slurry. The viscosity of the positive electrode slurry, measured at 25°C and a shear rate of 2.5 / s, can be in the range of 5,000 cps to 30,000 cps. In this case, the viscosity of the guiding fluid (GL), measured at 25°C and a shear rate of 2.5 / s, can be controlled to be lower than the viscosity of the positive electrode slurry.

[0107] In some embodiments, the electrode slurry (ES) can be a negative electrode slurry. The viscosity of the negative electrode slurry, measured at 25°C and a shear rate of 2.5 / s, can be in the range of 2000 cps to 6000 cps. In this case, the viscosity of the guiding fluid (GL), measured at 25°C and a shear rate of 2.5 / s, can be controlled to be lower than the viscosity of the negative electrode slurry.

[0108] Electrode paste (ES) may include electrode active materials, solvents, binders, and conductive materials. The electrode active materials may be positive or negative electrode active materials.

[0109] The positive electrode active material may include one or more of the following: lithium-iron oxides (e.g., LiFePO4), lithium-manganese oxides (e.g., LiMnO2, LiMn2O4), lithium-cobalt oxides (e.g., LiCoO2), lithium-nickel oxides (e.g., LiNiO2), lithium-nickel-manganese oxides (e.g., LiNi 1-y1 Mn y1 O2 (where 0 < y1 < 1) and LiMn 2-z1 Ni z1 O4 (where 0 < z1 < 2)), lithium-nickel-cobalt oxides (e.g., LiNi 1-y2 Co y2 O2 (where 0 < y2 < 1), etc.), lithium-manganese-cobalt oxides (e.g., LiCo 1-y3 Mn y3 O2 (where 0 < y3 < 1) and LiMn 2-z2 Co z2 O4 (where 0 < z2 < 2), etc.), lithium-nickel-manganese-cobalt oxides (e.g., Li(Ni p1 Co q1 Mn r1 )O2 (where 0 < p1 < 1, 0 < q1 < 1, 0 < r1 < 1, p1 + q1 + r1 = 1), Li(Ni p2 Co q2 Mn r2 )O4 (where 0 < p2 < 2, 0 < q2 < 2, 0 < r2 < 2, p2 + q2 + r2 = 2), etc.), and lithium-nickel-cobalt-metal (M) oxides (e.g., Li(Ni p3 Co q3 Mn r3 M s1 )O2 (where M is selected from the group consisting of Al, Cu, Fe, V, Cr, Ti, Zr, Zn, Ta, Nb, Mg, B, W, and Mo, and p3, q3, r3, and s1 are the atomic fractions of the corresponding independent elements, where 0 < p3 < 1, 0 < q3 < 1, 0 < r3 < 1, 0 < s1 < 1, and p3 + q3 + r3 + s1 = 1).

[0110] The negative electrode active material may include one or more of the following: lithium metal; graphite-based carbon materials such as natural or synthetic graphite in amorphous, flake, layered, spherical or fibrous form; amorphous carbon materials such as soft carbon and hard carbon; metals such as Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al and Sn, or alloys of these metals with lithium; PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5, Li x Fe2O3(0 ≤ x ≤ 1), Li x WO2(0 ≤ x ≤ 1), Sn x Me 1-x Me' y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of Groups 1, 2, 3 of the periodic table, halogens; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8); Si, SiO x (0 < x ≤ 2), Si-Y alloy (where Y is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements and combinations thereof, and Si is excluded), Sn, SnO2, Sn-Y (where Y is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements and combinations thereof, and is not Sn), or more than one of them.

[0111] The solvent may include one or more of dimethyl sulfoxide, isopropyl alcohol, N-methylpyrrolidone, acetone, methyl acetate, ethyl acetate, γ-butyrolactone, ε-caprolactone, dibutyl ether, tetrahydrofuran, cyclohexanone, benzene, fluorobenzene, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, and water.

[0112] The binder may include one or more of polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, and styrene-butadiene rubber-carboxymethyl cellulose fluororubber.

[0113] Conductive materials may include one or more of the following: carbon nanotubes; graphite; carbon-based materials, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and pyrolytic black; conductive fibers, such as carbon fibers or metal fibers; metal powders, such as fluorocarbon powders, aluminum powders, and nickel powders; conductive whiskers, such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxides; and polyphenylene oxide.

[0114] In some embodiments, the time interval between the start time of the guide liquid application step P110 and the start time of the drying step P130 may be in the range of about 300 seconds or less. The solids content of the guide liquid (GL) is lower than that of the electrode slurry (ES). Therefore, it is desirable for the guide liquid (GL) to dry as quickly as possible after being applied to the current collector (CC) to maintain a profile similar to that when it was initially applied and to mitigate the tendency of the electrode slurry (ES) to diffuse into the TD. In some embodiments, the time interval between the start time of the guide liquid application step P110 and the start time of the drying step P130 may be about 5 seconds or longer, or about 30 seconds or longer. In some embodiments, the time interval between the start time of the guide liquid application step P110 and the start time of the drying step P130 may be about 240 seconds or less, or about 180 seconds or less.

[0115] In some embodiments, the time interval between the start time of the guide liquid application step P110 and the start time of the electrode slurry application step P120 may be 3 seconds or less. The guide liquid application step P110 and the electrode slurry application step P120 may be performed almost simultaneously in a single coating apparatus. For example, the guide liquid application step P110 and the electrode slurry application step P120 may be performed almost simultaneously in coating apparatus 1020.

[0116] In some embodiments, the time interval between the start time of the guide liquid application step P110 and the start time of the electrode slurry application step P120 may be greater than about 3 seconds and less than 20 seconds. The guide liquid application step P110 and the electrode slurry application step P120 may be performed in separate coating apparatuses. For example, the guide liquid application step P110 may be performed in a first coating apparatus 1021 and the electrode slurry application step P120 may be performed in a second coating apparatus 1022.

[0117] electrode

[0118] Another aspect of this disclosure relates to an electrode.

[0119] Figure 10 This is a schematic diagram showing electrodes according to some embodiments.

[0120] refer to Figure 10The electrode may include a current collector (CC) and an electrode active material layer (AL). Electrodes according to some embodiments can be manufactured using the methods described above for manufacturing electrodes.

[0121] The electrode active material layer (AL) may include a planar portion (FP) and a sliding portion (SP).

[0122] A planar portion (FP) refers to a section within the electrode active material layer (AL) where the thickness is maintained at a constant level, having a thickness similar to the target thickness. Here, maintaining a constant thickness can mean a thickness deviation within approximately ±3%. The target thickness refers to the thickness of the electrode active material layer (AL) targeted during electrode fabrication. Having a thickness similar to the target thickness can mean a thickness difference from the target thickness of less than ±1%.

[0123] The sliding portion (SP) refers to the section of the electrode active material layer (AL) where the thickness gradually decreases towards the end in the width direction. However, the sliding portion (SP) does not include any portion where the thickness of the electrode active material layer (AL) is less than approximately 5% of the average thickness of the flat portion (FP). The sliding portion (SP) is formed at the edge of the flat portion (FP).

[0124] The angle between the sliding part (SP) and the current collector (CC) is called the sliding angle (θ). For example... Figure 10 As shown, the sliding angle (θ) can be measured by simplifying the cross-section of the electrode to an isosceles trapezoid. In this case, the flat portion (FP) can be simplified to a rectangular shape, and the sliding portion (SP) can be simplified to a right-angled triangle. The length of the shorter side of the rectangle can be approximately equal to the average thickness of the flat portion (FP). When the sliding portion (SP) is simplified to a right-angled triangle, the thickness of the thinnest part of the sliding portion (SP) (or the part with a thickness of approximately 5% of the average thickness of the flat portion (FP)) can be assumed to be zero, and the hypotenuse of the right-angled triangle can be drawn.

[0125] In some embodiments, the sliding angle (θ) can be in the range of 45° to 90°. In some embodiments, the sliding angle (θ) can be in the range of 60° to 90°. In some embodiments, the sliding angle (θ) can be in the range of 75° to 90°.

[0126] [Modes for Implementing the Invention]

[0127] The following describes an embodiment compared to a comparative example.

[0128] Examples 1 to 5 and Comparative Example 1

[0129] A guiding liquid containing N-methylpyrrolidone and polyvinylidene fluoride was prepared. The contents of N-methylpyrrolidone and polyvinylidene fluoride, as well as the viscosity of the guiding liquid, are shown in Table 1 below.

[0130] The cathode slurry was prepared by adding 97 wt% lithium-nickel-manganese-cobalt oxide, 1.5 wt% polyvinylidene fluoride, and 1.5 wt% carbon nanotubes to N-methylpyrrolidone and mixing them together. The viscosity of the cathode slurry was approximately 7,000 cps.

[0131] A guiding liquid is applied to the current collector, followed by the application of the positive electrode slurry, and then dried to prepare the positive electrode. Comparative Example 1 is the case without using a guiding liquid.

[0132] Examples 6 to 10 and Comparative Example 2

[0133] A guiding liquid containing N-methylpyrrolidone and polyvinylidene fluoride was prepared. The contents of N-methylpyrrolidone and polyvinylidene fluoride, as well as the viscosity of the guiding liquid, are shown in Table 1 below.

[0134] A negative electrode slurry was prepared by adding 96% by weight of graphite, 3% by weight of SBR-CMC, and 1% by weight of carbon black to water and mixing them. The viscosity of the negative electrode slurry was approximately 4,000 cps.

[0135] A guiding liquid is applied to the current collector, followed by the application of the negative electrode slurry, and then dried to prepare the negative electrode. Comparative Example 2 is the case without using a guiding liquid.

[0136] Slide angle measurement

[0137] The sliding angles of the electrodes according to Examples 1 to 10 and Comparative Examples 1 to 2 were measured. The measurement results are shown in Tables 1 and 2 below.

[0138] [Table 1]

[0139]

[0140] [Table 2]

[0141]

[0142] Referring to Tables 1 and 2, it can be seen that the electrodes of Examples 1 to 10, using the guiding liquid, controlled the slip angle to a certain level. For the positive electrode, although the slip angle of Comparative Example 1, which did not use the guiding liquid, was about 32°, Examples 1 to 5 controlled it to be higher than this slip angle. Specifically, in Examples 2 to 4, where the binder content was 5% by weight or higher, the slip angle was controlled in the range of 51° to 76°. However, the slip angle in Example 5, with a binder content of 22% by weight, was actually smaller than that in Example 4, possibly due to the excessive viscosity of the guiding liquid. Furthermore, Example 5 showed the limitation of a decreased evaporation rate of the guiding liquid.

[0143] For the negative electrode, Comparative Example 2, which did not use a guiding liquid, had a sliding angle of approximately 27°, while Examples 6 to 10 controlled for a higher angle. Specifically, with a binder content of 5% by weight or higher, the sliding angle in Examples 7 to 9 was controlled in the range of 46° to 77°. However, in Example 10, with a binder content of 22% by weight, the sliding angle decreased compared to Example 9 as the viscosity of the guiding liquid became excessive. Furthermore, Example 10 demonstrated the limitation of a decreased evaporation rate of the guiding liquid.

[0144] Measurement of electrode conductivity

[0145] The interfacial resistance between the electrode active material layer and the current collector of the manufactured electrode samples was measured using an electrode resistance measurement system (Hiokki, RM2610). Specifically, the resistance of the electrode samples according to Example 2 and Example 5 was compared and measured. The measurement results confirmed that the resistance of the electrode sample in Example 5 was approximately 32% higher than that in Example 2. This is understood to be due to the increase in electrode resistance caused by the increased binder component retained on the current collector in Example 5.

[0146] The above description is merely illustrative of this disclosure. The scope of this disclosure should be interpreted according to the claims, and all technical concepts within the scope of the claims (including those equivalent to or consistent with the claims) should be interpreted as falling within the scope of this disclosure.

[0147] [Symbol Explanation]

[0148] 1000, 1000′: Apparatus for manufacturing electrodes

[0149] 1011: First Roller

[0150] 1012: Second Roller

[0151] 1020: Coating apparatus

[0152] 1021: First Coating Device

[0153] 1022: Second coating device

[0154] 1030: Drying device

[0155] GL: Guiding fluid

[0156] ES: Electrode paste

[0157] AL: Electrode active material layer

[0158] CC: Current collector

[0159] FP: Flat area

[0160] SP: Sliding part

[0161] θ: Sliding angle

Claims

1. A method for manufacturing an electrode, comprising: The guiding liquid application step involves applying a guiding liquid that defines the electrode slurry application area onto the current collector sheet; The electrode slurry application step involves applying the electrode slurry to the electrode slurry application area defined by the guiding liquid; as well as The drying step involves drying the guiding liquid and the electrode slurry applied to the electrode sheet, wherein... During the drying step, at least 85% by weight of the guiding liquid is evaporated.

2. The method for manufacturing an electrode according to claim 1, wherein, The guiding liquid contains solvents and adhesives.

3. The method for manufacturing an electrode according to claim 2, wherein, The solvent includes one or more of dimethyl sulfoxide, isopropanol, N-methylpyrrolidone, acetone, methyl acetate, ethyl acetate, γ-butyrolactone, ε-caprolactone, dibutyl ether, tetrahydrofuran, cyclohexanone, benzene, fluorobenzene, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, and water.

4. The method for manufacturing an electrode according to claim 2, wherein, The adhesive comprises one or more of polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, and styrene-butadiene rubber-carboxymethyl cellulose fluororubber.

5. The method for manufacturing an electrode according to claim 1, wherein, The method for manufacturing the electrode is a method for manufacturing the positive electrode, wherein, The electrode paste is a positive electrode paste and satisfies the following formula 1: [Formula 1] In Equation 1, Vs1 represents the viscosity of the positive electrode slurry measured at a shear rate of 2.5 / s at 25°C, and is in the range of 5,000 cps to 30,000 cps. Vg1 represents the viscosity (cps) of the guiding fluid as measured at a shear rate of 2.5 / s at 25°C.

6. The method for manufacturing an electrode according to claim 1, wherein, The method for manufacturing the electrode is a method for manufacturing the negative electrode, wherein, The electrode paste is a negative electrode paste and satisfies the following equation 2: [Equation 2] In Equation 2, Vs2 represents the viscosity of the negative electrode slurry measured at a shear rate of 2.5 / s at 25°C, and is in the range of 2,000 cps to 6,000 cps. Vg2 represents the viscosity (cps) of the guiding fluid as measured at a shear rate of 2.5 / s at 25°C.

7. The method for manufacturing an electrode according to claim 1, wherein, The time interval (|T1-T3|) between the start time (T1) of the guiding liquid application step and the completion time (T3) of the drying step is in the range of 300 seconds or less.

8. The method for manufacturing an electrode according to claim 1, wherein, The time interval (|T1-T2|) between the start time of the guiding liquid application step (T1) and the start time of the electrode slurry application step (T2) is 3 seconds or less.

9. The method for manufacturing an electrode according to claim 1, wherein, The time interval (|T1-T2|) between the start time of the guiding liquid application step (T1) and the start time of the electrode slurry application step (T2) is greater than 3 seconds and less than 20 seconds.

10. An apparatus for manufacturing electrodes, comprising: The coating section applies a guiding liquid defining an electrode slurry application area to the current collector sheet and applies electrode slurry to the electrode slurry application area; as well as The drying section dries the guiding liquid and the electrode slurry, wherein... The viscosity of the guiding liquid is controlled to be lower than that of the electrode slurry.

11. The apparatus for manufacturing electrodes according to claim 10, wherein, The coating section includes a first coating mold and a second coating mold, wherein... The first coating mold applies the guiding liquid onto the current collector plate, wherein, The second coating mold applies the electrode slurry onto the current collector sheet.

12. The apparatus for manufacturing electrodes according to claim 10, wherein, The coating section includes a single coating mold, wherein, The single coating mold simultaneously applies the guiding liquid and the electrode slurry to the current collector sheet.

13. An electrode, comprising: A current collector and an electrode active material layer formed on one or both surfaces of the current collector, wherein, The electrode active material layer includes a flat portion and a sliding portion formed at the edge of the flat portion, wherein... The sliding angle of the sliding part is in the range of 45° to 90°.

Images